]> asedeno.scripts.mit.edu Git - PuTTY.git/blobdiff - ssh.c
Fix a mismerge in kex null-pointer checks.
[PuTTY.git] / ssh.c
diff --git a/ssh.c b/ssh.c
index a9bed27a48fa932b081edc41da58f3beffe041b0..a41a576c66ec9d25dd18453c7fcf54c9d0291f14 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -1,11 +1,21 @@
+/*
+ * SSH backend.
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #include <assert.h>
+#include <limits.h>
+#include <signal.h>
 
 #include "putty.h"
 #include "tree234.h"
 #include "ssh.h"
+#ifndef NO_GSSAPI
+#include "sshgssc.h"
+#include "sshgss.h"
+#endif
 
 #ifndef FALSE
 #define FALSE 0
 #define TRUE 1
 #endif
 
-#define SSH1_MSG_DISCONNECT                       1    /* 0x1 */
-#define SSH1_SMSG_PUBLIC_KEY                      2    /* 0x2 */
-#define SSH1_CMSG_SESSION_KEY                     3    /* 0x3 */
-#define SSH1_CMSG_USER                            4    /* 0x4 */
-#define SSH1_CMSG_AUTH_RSA                        6    /* 0x6 */
-#define SSH1_SMSG_AUTH_RSA_CHALLENGE              7    /* 0x7 */
-#define SSH1_CMSG_AUTH_RSA_RESPONSE               8    /* 0x8 */
-#define SSH1_CMSG_AUTH_PASSWORD                   9    /* 0x9 */
-#define SSH1_CMSG_REQUEST_PTY                     10   /* 0xa */
-#define SSH1_CMSG_WINDOW_SIZE                     11   /* 0xb */
-#define SSH1_CMSG_EXEC_SHELL                      12   /* 0xc */
-#define SSH1_CMSG_EXEC_CMD                        13   /* 0xd */
-#define SSH1_SMSG_SUCCESS                         14   /* 0xe */
-#define SSH1_SMSG_FAILURE                         15   /* 0xf */
-#define SSH1_CMSG_STDIN_DATA                      16   /* 0x10 */
-#define SSH1_SMSG_STDOUT_DATA                     17   /* 0x11 */
-#define SSH1_SMSG_STDERR_DATA                     18   /* 0x12 */
-#define SSH1_CMSG_EOF                             19   /* 0x13 */
-#define SSH1_SMSG_EXIT_STATUS                     20   /* 0x14 */
-#define SSH1_MSG_CHANNEL_OPEN_CONFIRMATION        21   /* 0x15 */
-#define SSH1_MSG_CHANNEL_OPEN_FAILURE             22   /* 0x16 */
-#define SSH1_MSG_CHANNEL_DATA                     23   /* 0x17 */
-#define SSH1_MSG_CHANNEL_CLOSE                    24   /* 0x18 */
-#define SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION       25   /* 0x19 */
-#define SSH1_SMSG_X11_OPEN                        27   /* 0x1b */
-#define SSH1_CMSG_PORT_FORWARD_REQUEST            28   /* 0x1c */
-#define SSH1_MSG_PORT_OPEN                        29   /* 0x1d */
-#define SSH1_CMSG_AGENT_REQUEST_FORWARDING        30   /* 0x1e */
-#define SSH1_SMSG_AGENT_OPEN                      31   /* 0x1f */
-#define SSH1_MSG_IGNORE                           32   /* 0x20 */
-#define SSH1_CMSG_EXIT_CONFIRMATION               33   /* 0x21 */
-#define SSH1_CMSG_X11_REQUEST_FORWARDING          34   /* 0x22 */
-#define SSH1_CMSG_AUTH_RHOSTS_RSA                 35   /* 0x23 */
-#define SSH1_MSG_DEBUG                            36   /* 0x24 */
-#define SSH1_CMSG_REQUEST_COMPRESSION             37   /* 0x25 */
-#define SSH1_CMSG_AUTH_TIS                        39   /* 0x27 */
-#define SSH1_SMSG_AUTH_TIS_CHALLENGE              40   /* 0x28 */
-#define SSH1_CMSG_AUTH_TIS_RESPONSE               41   /* 0x29 */
-#define SSH1_CMSG_AUTH_CCARD                      70   /* 0x46 */
-#define SSH1_SMSG_AUTH_CCARD_CHALLENGE            71   /* 0x47 */
-#define SSH1_CMSG_AUTH_CCARD_RESPONSE             72   /* 0x48 */
-
-#define SSH1_AUTH_TIS                             5    /* 0x5 */
-#define SSH1_AUTH_CCARD                           16   /* 0x10 */
-
-#define SSH1_PROTOFLAG_SCREEN_NUMBER              1    /* 0x1 */
-/* Mask for protoflags we will echo back to server if seen */
-#define SSH1_PROTOFLAGS_SUPPORTED                 0    /* 0x1 */
-
-#define SSH2_MSG_DISCONNECT                       1    /* 0x1 */
-#define SSH2_MSG_IGNORE                           2    /* 0x2 */
-#define SSH2_MSG_UNIMPLEMENTED                    3    /* 0x3 */
-#define SSH2_MSG_DEBUG                            4    /* 0x4 */
-#define SSH2_MSG_SERVICE_REQUEST                  5    /* 0x5 */
-#define SSH2_MSG_SERVICE_ACCEPT                   6    /* 0x6 */
-#define SSH2_MSG_KEXINIT                          20   /* 0x14 */
-#define SSH2_MSG_NEWKEYS                          21   /* 0x15 */
-#define SSH2_MSG_KEXDH_INIT                       30   /* 0x1e */
-#define SSH2_MSG_KEXDH_REPLY                      31   /* 0x1f */
-#define SSH2_MSG_KEX_DH_GEX_REQUEST               30   /* 0x1e */
-#define SSH2_MSG_KEX_DH_GEX_GROUP                 31   /* 0x1f */
-#define SSH2_MSG_KEX_DH_GEX_INIT                  32   /* 0x20 */
-#define SSH2_MSG_KEX_DH_GEX_REPLY                 33   /* 0x21 */
-#define SSH2_MSG_USERAUTH_REQUEST                 50   /* 0x32 */
-#define SSH2_MSG_USERAUTH_FAILURE                 51   /* 0x33 */
-#define SSH2_MSG_USERAUTH_SUCCESS                 52   /* 0x34 */
-#define SSH2_MSG_USERAUTH_BANNER                  53   /* 0x35 */
-#define SSH2_MSG_USERAUTH_PK_OK                   60   /* 0x3c */
-#define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ        60   /* 0x3c */
-#define SSH2_MSG_USERAUTH_INFO_REQUEST            60   /* 0x3c */
-#define SSH2_MSG_USERAUTH_INFO_RESPONSE           61   /* 0x3d */
-#define SSH2_MSG_GLOBAL_REQUEST                   80   /* 0x50 */
-#define SSH2_MSG_REQUEST_SUCCESS                  81   /* 0x51 */
-#define SSH2_MSG_REQUEST_FAILURE                  82   /* 0x52 */
-#define SSH2_MSG_CHANNEL_OPEN                     90   /* 0x5a */
-#define SSH2_MSG_CHANNEL_OPEN_CONFIRMATION        91   /* 0x5b */
-#define SSH2_MSG_CHANNEL_OPEN_FAILURE             92   /* 0x5c */
-#define SSH2_MSG_CHANNEL_WINDOW_ADJUST            93   /* 0x5d */
-#define SSH2_MSG_CHANNEL_DATA                     94   /* 0x5e */
-#define SSH2_MSG_CHANNEL_EXTENDED_DATA            95   /* 0x5f */
-#define SSH2_MSG_CHANNEL_EOF                      96   /* 0x60 */
-#define SSH2_MSG_CHANNEL_CLOSE                    97   /* 0x61 */
-#define SSH2_MSG_CHANNEL_REQUEST                  98   /* 0x62 */
-#define SSH2_MSG_CHANNEL_SUCCESS                  99   /* 0x63 */
-#define SSH2_MSG_CHANNEL_FAILURE                  100  /* 0x64 */
-
 /*
  * Packet type contexts, so that ssh2_pkt_type can correctly decode
  * the ambiguous type numbers back into the correct type strings.
  */
-#define SSH2_PKTCTX_DHGROUP          0x0001
-#define SSH2_PKTCTX_DHGEX            0x0002
-#define SSH2_PKTCTX_KEX_MASK         0x000F
-#define SSH2_PKTCTX_PUBLICKEY        0x0010
-#define SSH2_PKTCTX_PASSWORD         0x0020
-#define SSH2_PKTCTX_KBDINTER         0x0040
-#define SSH2_PKTCTX_AUTH_MASK        0x00F0
-
-#define SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1  /* 0x1 */
-#define SSH2_DISCONNECT_PROTOCOL_ERROR            2    /* 0x2 */
-#define SSH2_DISCONNECT_KEY_EXCHANGE_FAILED       3    /* 0x3 */
-#define SSH2_DISCONNECT_HOST_AUTHENTICATION_FAILED 4   /* 0x4 */
-#define SSH2_DISCONNECT_MAC_ERROR                 5    /* 0x5 */
-#define SSH2_DISCONNECT_COMPRESSION_ERROR         6    /* 0x6 */
-#define SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE     7    /* 0x7 */
-#define SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8       /* 0x8 */
-#define SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE   9    /* 0x9 */
-#define SSH2_DISCONNECT_CONNECTION_LOST           10   /* 0xa */
-#define SSH2_DISCONNECT_BY_APPLICATION            11   /* 0xb */
-#define SSH2_DISCONNECT_TOO_MANY_CONNECTIONS      12   /* 0xc */
-#define SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER    13   /* 0xd */
-#define SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14      /* 0xe */
-#define SSH2_DISCONNECT_ILLEGAL_USER_NAME         15   /* 0xf */
+typedef enum {
+    SSH2_PKTCTX_NOKEX,
+    SSH2_PKTCTX_DHGROUP,
+    SSH2_PKTCTX_DHGEX,
+    SSH2_PKTCTX_RSAKEX
+} Pkt_KCtx;
+typedef enum {
+    SSH2_PKTCTX_NOAUTH,
+    SSH2_PKTCTX_PUBLICKEY,
+    SSH2_PKTCTX_PASSWORD,
+    SSH2_PKTCTX_GSSAPI,
+    SSH2_PKTCTX_KBDINTER
+} Pkt_ACtx;
 
 static const char *const ssh2_disconnect_reasons[] = {
     NULL,
-    "SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT",
-    "SSH_DISCONNECT_PROTOCOL_ERROR",
-    "SSH_DISCONNECT_KEY_EXCHANGE_FAILED",
-    "SSH_DISCONNECT_HOST_AUTHENTICATION_FAILED",
-    "SSH_DISCONNECT_MAC_ERROR",
-    "SSH_DISCONNECT_COMPRESSION_ERROR",
-    "SSH_DISCONNECT_SERVICE_NOT_AVAILABLE",
-    "SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED",
-    "SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE",
-    "SSH_DISCONNECT_CONNECTION_LOST",
-    "SSH_DISCONNECT_BY_APPLICATION",
-    "SSH_DISCONNECT_TOO_MANY_CONNECTIONS",
-    "SSH_DISCONNECT_AUTH_CANCELLED_BY_USER",
-    "SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE",
-    "SSH_DISCONNECT_ILLEGAL_USER_NAME",
+    "host not allowed to connect",
+    "protocol error",
+    "key exchange failed",
+    "host authentication failed",
+    "MAC error",
+    "compression error",
+    "service not available",
+    "protocol version not supported",
+    "host key not verifiable",
+    "connection lost",
+    "by application",
+    "too many connections",
+    "auth cancelled by user",
+    "no more auth methods available",
+    "illegal user name",
 };
 
-#define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED     1    /* 0x1 */
-#define SSH2_OPEN_CONNECT_FAILED                  2    /* 0x2 */
-#define SSH2_OPEN_UNKNOWN_CHANNEL_TYPE            3    /* 0x3 */
-#define SSH2_OPEN_RESOURCE_SHORTAGE               4    /* 0x4 */
-
-#define SSH2_EXTENDED_DATA_STDERR                 1    /* 0x1 */
-
 /*
  * Various remote-bug flags.
  */
@@ -165,11 +72,19 @@ static const char *const ssh2_disconnect_reasons[] = {
 #define BUG_SSH2_DERIVEKEY                       32
 #define BUG_SSH2_REKEY                           64
 #define BUG_SSH2_PK_SESSIONID                   128
+#define BUG_SSH2_MAXPKT                                256
+#define BUG_CHOKES_ON_SSH2_IGNORE               512
+#define BUG_CHOKES_ON_WINADJ                   1024
+#define BUG_SENDS_LATE_REQUEST_REPLY           2048
+#define BUG_SSH2_OLDGEX                        4096
+
+#define DH_MIN_SIZE 1024
+#define DH_MAX_SIZE 8192
 
 /*
  * Codes for terminal modes.
  * Most of these are the same in SSH-1 and SSH-2.
- * This list is derived from draft-ietf-secsh-connect-25 and
+ * This list is derived from RFC 4254 and
  * SSH-1 RFC-1.2.31.
  */
 static const struct {
@@ -271,7 +186,8 @@ static unsigned int ssh_tty_parse_boolean(char *s)
 }
 
 #define translate(x) if (type == x) return #x
-#define translatec(x,ctx) if (type == x && (pkt_ctx & ctx)) return #x
+#define translatek(x,ctx) if (type == x && (pkt_kctx == ctx)) return #x
+#define translatea(x,ctx) if (type == x && (pkt_actx == ctx)) return #x
 static char *ssh1_pkt_type(int type)
 {
     translate(SSH1_MSG_DISCONNECT);
@@ -317,8 +233,14 @@ static char *ssh1_pkt_type(int type)
     translate(SSH1_CMSG_AUTH_CCARD_RESPONSE);
     return "unknown";
 }
-static char *ssh2_pkt_type(int pkt_ctx, int type)
+static char *ssh2_pkt_type(Pkt_KCtx pkt_kctx, Pkt_ACtx pkt_actx, int type)
 {
+    translatea(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE,SSH2_PKTCTX_GSSAPI);
+    translatea(SSH2_MSG_USERAUTH_GSSAPI_TOKEN,SSH2_PKTCTX_GSSAPI);
+    translatea(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,SSH2_PKTCTX_GSSAPI);
+    translatea(SSH2_MSG_USERAUTH_GSSAPI_ERROR,SSH2_PKTCTX_GSSAPI);
+    translatea(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK,SSH2_PKTCTX_GSSAPI);
+    translatea(SSH2_MSG_USERAUTH_GSSAPI_MIC, SSH2_PKTCTX_GSSAPI);
     translate(SSH2_MSG_DISCONNECT);
     translate(SSH2_MSG_IGNORE);
     translate(SSH2_MSG_UNIMPLEMENTED);
@@ -327,20 +249,24 @@ static char *ssh2_pkt_type(int pkt_ctx, int type)
     translate(SSH2_MSG_SERVICE_ACCEPT);
     translate(SSH2_MSG_KEXINIT);
     translate(SSH2_MSG_NEWKEYS);
-    translatec(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP);
-    translatec(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP);
-    translatec(SSH2_MSG_KEX_DH_GEX_REQUEST, SSH2_PKTCTX_DHGEX);
-    translatec(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
-    translatec(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
-    translatec(SSH2_MSG_KEX_DH_GEX_REPLY, SSH2_PKTCTX_DHGEX);
+    translatek(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP);
+    translatek(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP);
+    translatek(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD, SSH2_PKTCTX_DHGEX);
+    translatek(SSH2_MSG_KEX_DH_GEX_REQUEST, SSH2_PKTCTX_DHGEX);
+    translatek(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
+    translatek(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
+    translatek(SSH2_MSG_KEX_DH_GEX_REPLY, SSH2_PKTCTX_DHGEX);
+    translatek(SSH2_MSG_KEXRSA_PUBKEY, SSH2_PKTCTX_RSAKEX);
+    translatek(SSH2_MSG_KEXRSA_SECRET, SSH2_PKTCTX_RSAKEX);
+    translatek(SSH2_MSG_KEXRSA_DONE, SSH2_PKTCTX_RSAKEX);
     translate(SSH2_MSG_USERAUTH_REQUEST);
     translate(SSH2_MSG_USERAUTH_FAILURE);
     translate(SSH2_MSG_USERAUTH_SUCCESS);
     translate(SSH2_MSG_USERAUTH_BANNER);
-    translatec(SSH2_MSG_USERAUTH_PK_OK, SSH2_PKTCTX_PUBLICKEY);
-    translatec(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, SSH2_PKTCTX_PASSWORD);
-    translatec(SSH2_MSG_USERAUTH_INFO_REQUEST, SSH2_PKTCTX_KBDINTER);
-    translatec(SSH2_MSG_USERAUTH_INFO_RESPONSE, SSH2_PKTCTX_KBDINTER);
+    translatea(SSH2_MSG_USERAUTH_PK_OK, SSH2_PKTCTX_PUBLICKEY);
+    translatea(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ, SSH2_PKTCTX_PASSWORD);
+    translatea(SSH2_MSG_USERAUTH_INFO_REQUEST, SSH2_PKTCTX_KBDINTER);
+    translatea(SSH2_MSG_USERAUTH_INFO_RESPONSE, SSH2_PKTCTX_KBDINTER);
     translate(SSH2_MSG_GLOBAL_REQUEST);
     translate(SSH2_MSG_REQUEST_SUCCESS);
     translate(SSH2_MSG_REQUEST_FAILURE);
@@ -363,9 +289,6 @@ static char *ssh2_pkt_type(int pkt_ctx, int type)
 /* Enumeration values for fields in SSH-1 packets */
 enum {
     PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM,
-    /* These values are for communicating relevant semantics of
-     * fields to the packet logging code. */
-    PKTT_OTHER, PKTT_PASSWORD, PKTT_DATA
 };
 
 /*
@@ -389,12 +312,16 @@ enum {
  *    Database for Edit and Continue'.
  */
 #define crBegin(v)     { int *crLine = &v; switch(v) { case 0:;
-#define crState(t) \
-    struct t *s; \
-    if (!ssh->t) ssh->t = snew(struct t); \
-    s = ssh->t;
+#define crBeginState   crBegin(s->crLine)
+#define crStateP(t, v)                         \
+    struct t *s;                               \
+    if (!(v)) { s = (v) = snew(struct t); s->crLine = 0; }     \
+    s = (v);
+#define crState(t)     crStateP(t, ssh->t)
 #define crFinish(z)    } *crLine = 0; return (z); }
 #define crFinishV      } *crLine = 0; return; }
+#define crFinishFree(z)        } sfree(s); return (z); }
+#define crFinishFreeV  } sfree(s); return; }
 #define crReturn(z)    \
        do {\
            *crLine =__LINE__; return (z); case __LINE__:;\
@@ -408,20 +335,19 @@ enum {
 #define crWaitUntil(c) do { crReturn(0); } while (!(c))
 #define crWaitUntilV(c)        do { crReturnV; } while (!(c))
 
-typedef struct ssh_tag *Ssh;
 struct Packet;
 
 static struct Packet *ssh1_pkt_init(int pkt_type);
 static struct Packet *ssh2_pkt_init(int pkt_type);
 static void ssh_pkt_ensure(struct Packet *, int length);
-static void ssh_pkt_adddata(struct Packet *, void *data, int len);
+static void ssh_pkt_adddata(struct Packet *, const void *data, int len);
 static void ssh_pkt_addbyte(struct Packet *, unsigned char value);
 static void ssh2_pkt_addbool(struct Packet *, unsigned char value);
 static void ssh_pkt_adduint32(struct Packet *, unsigned long value);
 static void ssh_pkt_addstring_start(struct Packet *);
-static void ssh_pkt_addstring_str(struct Packet *, char *data);
-static void ssh_pkt_addstring_data(struct Packet *, char *data, int len);
-static void ssh_pkt_addstring(struct Packet *, char *data);
+static void ssh_pkt_addstring_str(struct Packet *, const char *data);
+static void ssh_pkt_addstring_data(struct Packet *, const char *data, int len);
+static void ssh_pkt_addstring(struct Packet *, const char *data);
 static unsigned char *ssh2_mpint_fmt(Bignum b, int *len);
 static void ssh1_pkt_addmp(struct Packet *, Bignum b);
 static void ssh2_pkt_addmp(struct Packet *, Bignum b);
@@ -432,6 +358,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                         struct Packet *pktin);
 static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                             struct Packet *pktin);
+static void ssh2_channel_check_close(struct ssh_channel *c);
+static void ssh_channel_destroy(struct ssh_channel *c);
 
 /*
  * Buffer management constants. There are several of these for
@@ -452,20 +380,35 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
  * 
  *  - OUR_V2_WINSIZE is the maximum window size we present on SSH-2
  *    channels.
+ *
+ *  - OUR_V2_BIGWIN is the window size we advertise for the only
+ *    channel in a simple connection.  It must be <= INT_MAX.
+ *
+ *  - OUR_V2_MAXPKT is the official "maximum packet size" we send
+ *    to the remote side. This actually has nothing to do with the
+ *    size of the _packet_, but is instead a limit on the amount
+ *    of data we're willing to receive in a single SSH2 channel
+ *    data message.
+ *
+ *  - OUR_V2_PACKETLIMIT is actually the maximum size of SSH
+ *    _packet_ we're prepared to cope with.  It must be a multiple
+ *    of the cipher block size, and must be at least 35000.
  */
 
 #define SSH1_BUFFER_LIMIT 32768
 #define SSH_MAX_BACKLOG 32768
 #define OUR_V2_WINSIZE 16384
+#define OUR_V2_BIGWIN 0x7fffffff
 #define OUR_V2_MAXPKT 0x4000UL
+#define OUR_V2_PACKETLIMIT 0x9000UL
 
 const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
 
 const static struct ssh_mac *macs[] = {
-    &ssh_sha1, &ssh_md5
+    &ssh_hmac_sha256, &ssh_hmac_sha1, &ssh_hmac_sha1_96, &ssh_hmac_md5
 };
 const static struct ssh_mac *buggymacs[] = {
-    &ssh_sha1_buggy, &ssh_md5
+    &ssh_hmac_sha1_buggy, &ssh_hmac_sha1_96_buggy, &ssh_hmac_md5
 };
 
 static void *ssh_comp_none_init(void)
@@ -485,7 +428,7 @@ static int ssh_comp_none_disable(void *handle)
     return 0;
 }
 const static struct ssh_compress ssh_comp_none = {
-    "none",
+    "none", NULL,
     ssh_comp_none_init, ssh_comp_none_cleanup, ssh_comp_none_block,
     ssh_comp_none_init, ssh_comp_none_cleanup, ssh_comp_none_block,
     ssh_comp_none_disable, NULL
@@ -500,7 +443,37 @@ enum {                                    /* channel types */
     CHAN_X11,
     CHAN_AGENT,
     CHAN_SOCKDATA,
-    CHAN_SOCKDATA_DORMANT             /* one the remote hasn't confirmed */
+    CHAN_SOCKDATA_DORMANT,            /* one the remote hasn't confirmed */
+    /*
+     * CHAN_SHARING indicates a channel which is tracked here on
+     * behalf of a connection-sharing downstream. We do almost nothing
+     * with these channels ourselves: all messages relating to them
+     * get thrown straight to sshshare.c and passed on almost
+     * unmodified to downstream.
+     */
+    CHAN_SHARING,
+    /*
+     * CHAN_ZOMBIE is used to indicate a channel for which we've
+     * already destroyed the local data source: for instance, if a
+     * forwarded port experiences a socket error on the local side, we
+     * immediately destroy its local socket and turn the SSH channel
+     * into CHAN_ZOMBIE.
+     */
+    CHAN_ZOMBIE
+};
+
+typedef void (*handler_fn_t)(Ssh ssh, struct Packet *pktin);
+typedef void (*chandler_fn_t)(Ssh ssh, struct Packet *pktin, void *ctx);
+typedef void (*cchandler_fn_t)(struct ssh_channel *, struct Packet *, void *);
+
+/*
+ * Each channel has a queue of outstanding CHANNEL_REQUESTS and their
+ * handlers.
+ */
+struct outstanding_channel_request {
+    cchandler_fn_t handler;
+    void *ctx;
+    struct outstanding_channel_request *next;
 };
 
 /*
@@ -521,16 +494,59 @@ struct ssh_channel {
      *   8   We have received SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
      * 
      * A channel is completely finished with when all four bits are set.
+     *
+     * In SSH-2, the four bits mean:
+     *
+     *   1   We have sent SSH2_MSG_CHANNEL_EOF.
+     *   2   We have sent SSH2_MSG_CHANNEL_CLOSE.
+     *   4   We have received SSH2_MSG_CHANNEL_EOF.
+     *   8   We have received SSH2_MSG_CHANNEL_CLOSE.
+     *
+     * A channel is completely finished with when we have both sent
+     * and received CLOSE.
+     *
+     * The symbolic constants below use the SSH-2 terminology, which
+     * is a bit confusing in SSH-1, but we have to use _something_.
      */
+#define CLOSES_SENT_EOF    1
+#define CLOSES_SENT_CLOSE  2
+#define CLOSES_RCVD_EOF    4
+#define CLOSES_RCVD_CLOSE  8
     int closes;
+
+    /*
+     * This flag indicates that an EOF is pending on the outgoing side
+     * of the channel: that is, wherever we're getting the data for
+     * this channel has sent us some data followed by EOF. We can't
+     * actually send the EOF until we've finished sending the data, so
+     * we set this flag instead to remind us to do so once our buffer
+     * is clear.
+     */
+    int pending_eof;
+
+    /*
+     * True if this channel is causing the underlying connection to be
+     * throttled.
+     */
+    int throttling_conn;
     union {
-       struct ssh1_data_channel {
-           int throttling;
-       } v1;
        struct ssh2_data_channel {
            bufchain outbuffer;
            unsigned remwindow, remmaxpkt;
-           unsigned locwindow;
+           /* locwindow is signed so we can cope with excess data. */
+           int locwindow, locmaxwin;
+           /*
+            * remlocwin is the amount of local window that we think
+            * the remote end had available to it after it sent the
+            * last data packet or window adjust ack.
+            */
+           int remlocwin;
+           /*
+            * These store the list of channel requests that haven't
+            * been acked.
+            */
+           struct outstanding_channel_request *chanreq_head, *chanreq_tail;
+           enum { THROTTLED, UNTHROTTLING, UNTHROTTLED } throttle_state;
        } v2;
     } v;
     union {
@@ -538,13 +554,18 @@ struct ssh_channel {
            unsigned char *message;
            unsigned char msglen[4];
            unsigned lensofar, totallen;
+            int outstanding_requests;
        } a;
        struct ssh_x11_channel {
-           Socket s;
+           struct X11Connection *xconn;
+            int initial;
        } x11;
        struct ssh_pfd_channel {
-           Socket s;
+            struct PortForwarding *pf;
        } pfd;
+       struct ssh_sharing_channel {
+           void *ctx;
+       } sharing;
     } u;
 };
 
@@ -579,12 +600,21 @@ struct ssh_portfwd; /* forward declaration */
 
 struct ssh_rportfwd {
     unsigned sport, dport;
-    char dhost[256];
+    char *shost, *dhost;
     char *sportdesc;
+    void *share_ctx;
     struct ssh_portfwd *pfrec;
 };
-#define free_rportfwd(pf) ( \
-    ((pf) ? (sfree((pf)->sportdesc)) : (void)0 ), sfree(pf) )
+
+static void free_rportfwd(struct ssh_rportfwd *pf)
+{
+    if (pf) {
+        sfree(pf->sportdesc);
+        sfree(pf->shost);
+        sfree(pf->dhost);
+        sfree(pf);
+    }
+}
 
 /*
  * Separately to the rportfwd tree (which is for looking up port
@@ -601,51 +631,78 @@ struct ssh_portfwd {
     char *sserv, *dserv;
     struct ssh_rportfwd *remote;
     int addressfamily;
-    void *local;
+    struct PortListener *local;
 };
 #define free_portfwd(pf) ( \
     ((pf) ? (sfree((pf)->saddr), sfree((pf)->daddr), \
             sfree((pf)->sserv), sfree((pf)->dserv)) : (void)0 ), sfree(pf) )
 
 struct Packet {
-    long length;           /* length of `data' actually used */
+    long length;           /* length of packet: see below */
     long forcepad;         /* SSH-2: force padding to at least this length */
     int type;              /* only used for incoming packets */
     unsigned long sequence; /* SSH-2 incoming sequence number */
     unsigned char *data;    /* allocated storage */
     unsigned char *body;    /* offset of payload within `data' */
-    long savedpos;         /* temporary index into `data' (for strings) */
+    long savedpos;         /* dual-purpose saved packet position: see below */
     long maxlen;           /* amount of storage allocated for `data' */
     long encrypted_len;            /* for SSH-2 total-size counting */
 
     /*
-     * State associated with packet logging
+     * A note on the 'length' and 'savedpos' fields above.
+     *
+     * Incoming packets are set up so that pkt->length is measured
+     * relative to pkt->body, which itself points to a few bytes after
+     * pkt->data (skipping some uninteresting header fields including
+     * the packet type code). The ssh_pkt_get* functions all expect
+     * this setup, and they also use pkt->savedpos to indicate how far
+     * through the packet being decoded they've got - and that, too,
+     * is an offset from pkt->body rather than pkt->data.
+     *
+     * During construction of an outgoing packet, however, pkt->length
+     * is measured relative to the base pointer pkt->data, and
+     * pkt->body is not really used for anything until the packet is
+     * ready for sending. In this mode, pkt->savedpos is reused as a
+     * temporary variable by the addstring functions, which write out
+     * a string length field and then keep going back and updating it
+     * as more data is appended to the subsequent string data field;
+     * pkt->savedpos stores the offset (again relative to pkt->data)
+     * of the start of the string data field.
      */
-    int logmode;
-    int nblanks;
-    struct logblank_t *blanks;
+
+    /* Extra metadata used in SSH packet logging mode, allowing us to
+     * log in the packet header line that the packet came from a
+     * connection-sharing downstream and what if anything unusual was
+     * done to it. The additional_log_text field is expected to be a
+     * static string - it will not be freed. */
+    unsigned downstream_id;
+    const char *additional_log_text;
 };
 
 static void ssh1_protocol(Ssh ssh, void *vin, int inlen,
                          struct Packet *pktin);
 static void ssh2_protocol(Ssh ssh, void *vin, int inlen,
                          struct Packet *pktin);
+static void ssh2_bare_connection_protocol(Ssh ssh, void *vin, int inlen,
+                                          struct Packet *pktin);
 static void ssh1_protocol_setup(Ssh ssh);
 static void ssh2_protocol_setup(Ssh ssh);
+static void ssh2_bare_connection_protocol_setup(Ssh ssh);
 static void ssh_size(void *handle, int width, int height);
 static void ssh_special(void *handle, Telnet_Special);
 static int ssh2_try_send(struct ssh_channel *c);
 static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len);
 static void ssh_throttle_all(Ssh ssh, int enable, int bufsize);
-static void ssh2_set_window(struct ssh_channel *c, unsigned newwin);
+static void ssh2_set_window(struct ssh_channel *c, int newwin);
 static int ssh_sendbuffer(void *handle);
 static int ssh_do_close(Ssh ssh, int notify_exit);
 static unsigned long ssh_pkt_getuint32(struct Packet *pkt);
 static int ssh2_pkt_getbool(struct Packet *pkt);
 static void ssh_pkt_getstring(struct Packet *pkt, char **p, int *length);
-static void ssh2_timer(void *ctx, long now);
-static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
-                            struct Packet *pktin);
+static void ssh2_timer(void *ctx, unsigned long now);
+static void do_ssh2_transport(Ssh ssh, void *vin, int inlen,
+                             struct Packet *pktin);
+static void ssh2_msg_unexpected(Ssh ssh, struct Packet *pktin);
 
 struct rdpkt1_state_tag {
     long len, pad, biglen, to_read;
@@ -664,8 +721,13 @@ struct rdpkt2_state_tag {
     struct Packet *pktin;
 };
 
-typedef void (*handler_fn_t)(Ssh ssh, struct Packet *pktin);
-typedef void (*chandler_fn_t)(Ssh ssh, struct Packet *pktin, void *ctx);
+struct rdpkt2_bare_state_tag {
+    char length[4];
+    long packetlen;
+    int i;
+    unsigned long incoming_sequence;
+    struct Packet *pktin;
+};
 
 struct queued_handler;
 struct queued_handler {
@@ -679,7 +741,8 @@ struct ssh_tag {
     const struct plug_function_table *fn;
     /* the above field _must_ be first in the structure */
 
-    SHA_State exhash, exhashbase;
+    char *v_c, *v_s;
+    void *exhash;
 
     Socket s;
 
@@ -704,9 +767,15 @@ struct ssh_tag {
     void *cs_comp_ctx, *sc_comp_ctx;
     const struct ssh_kex *kex;
     const struct ssh_signkey *hostkey;
-    unsigned char v2_session_id[20];
+    char *hostkey_str; /* string representation, for easy checking in rekeys */
+    unsigned char v2_session_id[SSH2_KEX_MAX_HASH_LEN];
+    int v2_session_id_len;
     void *kex_ctx;
 
+    int bare_connection;
+    int attempting_connshare;
+    void *connshare;
+
     char *savedhost;
     int savedport;
     int send_ok;
@@ -719,6 +788,7 @@ struct ssh_tag {
 
     tree234 *channels;                /* indexed by local id */
     struct ssh_channel *mainchan;      /* primary session channel */
+    int ncmode;                               /* is primary channel direct-tcpip? */
     int exitcode;
     int close_expected;
     int clean_exit;
@@ -734,6 +804,8 @@ struct ssh_tag {
     } state;
 
     int size_needed, eof_needed;
+    int sent_console_eof;
+    int got_pty;           /* affects EOF behaviour on main channel */
 
     struct Packet **queue;
     int queuelen, queuesize;
@@ -750,20 +822,16 @@ struct ssh_tag {
     int fallback_cmd;
 
     bufchain banner;   /* accumulates banners during do_ssh2_authconn */
-    /*
-     * Used for username and password input.
-     */
-    char *userpass_input_buffer;
-    int userpass_input_buflen;
-    int userpass_input_bufpos;
-    int userpass_input_echo;
 
-    int pkt_ctx;
+    Pkt_KCtx pkt_kctx;
+    Pkt_ACtx pkt_actx;
 
-    void *x11auth;
+    struct X11Display *x11disp;
+    struct X11FakeAuth *x11auth;
+    tree234 *x11authtree;
 
     int version;
-    int v1_throttle_count;
+    int conn_throttle_count;
     int overall_bufsize;
     int throttled_all;
     int v1_stdout_throttling;
@@ -771,20 +839,19 @@ struct ssh_tag {
 
     int ssh1_rdpkt_crstate;
     int ssh2_rdpkt_crstate;
-    int do_ssh_init_crstate;
+    int ssh2_bare_rdpkt_crstate;
     int ssh_gotdata_crstate;
-    int do_ssh1_login_crstate;
     int do_ssh1_connection_crstate;
-    int do_ssh2_transport_crstate;
-    int do_ssh2_authconn_crstate;
 
     void *do_ssh_init_state;
     void *do_ssh1_login_state;
     void *do_ssh2_transport_state;
     void *do_ssh2_authconn_state;
+    void *do_ssh_connection_init_state;
 
     struct rdpkt1_state_tag rdpkt1_state;
     struct rdpkt2_state_tag rdpkt2_state;
+    struct rdpkt2_bare_state_tag rdpkt2_bare_state;
 
     /* SSH-1 and SSH-2 use this for different things, but both use it */
     int protocol_initial_phase_done;
@@ -792,14 +859,29 @@ struct ssh_tag {
     void (*protocol) (Ssh ssh, void *vin, int inlen,
                      struct Packet *pkt);
     struct Packet *(*s_rdpkt) (Ssh ssh, unsigned char **data, int *datalen);
+    int (*do_ssh_init)(Ssh ssh, unsigned char c);
+
+    /*
+     * We maintain our own copy of a Conf structure here. That way,
+     * when we're passed a new one for reconfiguration, we can check
+     * the differences and potentially reconfigure port forwardings
+     * etc in mid-session.
+     */
+    Conf *conf;
+
+    /*
+     * Values cached out of conf so as to avoid the tree234 lookup
+     * cost every time they're used.
+     */
+    int logomitdata;
 
     /*
-     * We maintain a full _copy_ of a Config structure here, not
-     * merely a pointer to it. That way, when we're passed a new
-     * one for reconfiguration, we can check the differences and
-     * potentially reconfigure port forwardings etc in mid-session.
+     * Dynamically allocated username string created during SSH
+     * login. Stored in here rather than in the coroutine state so
+     * that it'll be reliably freed if we shut down the SSH session
+     * at some unexpected moment.
      */
-    Config cfg;
+    char *username;
 
     /*
      * Used to transfer data back from async callbacks.
@@ -831,6 +913,7 @@ struct ssh_tag {
      * indications from a request.
      */
     struct queued_handler *qhead, *qtail;
+    handler_fn_t q_saved_handler1, q_saved_handler2;
 
     /*
      * This module deals with sending keepalives.
@@ -844,8 +927,20 @@ struct ssh_tag {
     unsigned long incoming_data_size, outgoing_data_size, deferred_data_size;
     unsigned long max_data_size;
     int kex_in_progress;
-    long next_rekey, last_rekey;
+    unsigned long next_rekey, last_rekey;
     char *deferred_rekey_reason;    /* points to STATIC string; don't free */
+
+    /*
+     * Fully qualified host name, which we need if doing GSSAPI.
+     */
+    char *fullhostname;
+
+#ifndef NO_GSSAPI
+    /*
+     * GSSAPI libraries for this session.
+     */
+    struct ssh_gss_liblist *gsslibs;
+#endif
 };
 
 #define logevent(s) logevent(ssh->frontend, s)
@@ -863,54 +958,39 @@ static void logeventf(Ssh ssh, const char *fmt, ...)
     sfree(buf);
 }
 
-#define bombout(msg) \
-    do { \
-        char *text = dupprintf msg; \
-       ssh_do_close(ssh, FALSE); \
-        logevent(text); \
-        connection_fatal(ssh->frontend, "%s", text); \
-        sfree(text); \
-    } while (0)
-
-/* Functions to leave bits out of the SSH packet log file. */
-
-static void dont_log_password(Ssh ssh, struct Packet *pkt, int blanktype)
-{
-    if (ssh->cfg.logomitpass)
-       pkt->logmode = blanktype;
-}
-
-static void dont_log_data(Ssh ssh, struct Packet *pkt, int blanktype)
+static void bomb_out(Ssh ssh, char *text)
 {
-    if (ssh->cfg.logomitdata)
-       pkt->logmode = blanktype;
+    ssh_do_close(ssh, FALSE);
+    logevent(text);
+    connection_fatal(ssh->frontend, "%s", text);
+    sfree(text);
 }
 
-static void end_log_omission(Ssh ssh, struct Packet *pkt)
-{
-    pkt->logmode = PKTLOG_EMIT;
-}
+#define bombout(msg) bomb_out(ssh, dupprintf msg)
 
-/* Helper function for common bits of parsing cfg.ttymodes. */
-static void parse_ttymodes(Ssh ssh, char *modes,
+/* Helper function for common bits of parsing ttymodes. */
+static void parse_ttymodes(Ssh ssh,
                           void (*do_mode)(void *data, char *mode, char *val),
                           void *data)
 {
-    while (*modes) {
-       char *t = strchr(modes, '\t');
-       char *m = snewn(t-modes+1, char);
-       char *val;
-       strncpy(m, modes, t-modes);
-       m[t-modes] = '\0';
-       if (*(t+1) == 'A')
-           val = get_ttymode(ssh->frontend, m);
-       else
-           val = dupstr(t+2);
-       if (val)
-           do_mode(data, m, val);
-       sfree(m);
-       sfree(val);
-       modes += strlen(modes) + 1;
+    char *key, *val;
+
+    for (val = conf_get_str_strs(ssh->conf, CONF_ttymodes, NULL, &key);
+        val != NULL;
+        val = conf_get_str_strs(ssh->conf, CONF_ttymodes, key, &key)) {
+       /*
+        * val[0] is either 'V', indicating that an explicit value
+        * follows it, or 'A' indicating that we should pass the
+        * value through from the local environment via get_ttymode.
+        */
+       if (val[0] == 'A') {
+           val = get_ttymode(ssh->frontend, key);
+           if (val) {
+               do_mode(data, key, val);
+               sfree(val);
+           }
+       } else
+           do_mode(data, key, val + 1);               /* skip the 'V' */
     }
 }
 
@@ -953,7 +1033,9 @@ static int ssh_rportcmp_ssh2(void *av, void *bv)
 {
     struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
     struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
-
+    int i;
+    if ( (i = strcmp(a->shost, b->shost)) != 0)
+       return i < 0 ? -1 : +1;
     if (a->sport > b->sport)
        return +1;
     if (a->sport < b->sport)
@@ -1044,27 +1126,28 @@ static int alloc_channel_id(Ssh ssh)
     return low + 1 + CHANNEL_NUMBER_OFFSET;
 }
 
+static void c_write_stderr(int trusted, const char *buf, int len)
+{
+    int i;
+    for (i = 0; i < len; i++)
+       if (buf[i] != '\r' && (trusted || buf[i] == '\n' || (buf[i] & 0x60)))
+           fputc(buf[i], stderr);
+}
+
 static void c_write(Ssh ssh, const char *buf, int len)
 {
-    if ((flags & FLAG_STDERR)) {
-       int i;
-       for (i = 0; i < len; i++)
-           if (buf[i] != '\r')
-               fputc(buf[i], stderr);
-       return;
-    }
-    from_backend(ssh->frontend, 1, buf, len);
+    if (flags & FLAG_STDERR)
+       c_write_stderr(1, buf, len);
+    else
+       from_backend(ssh->frontend, 1, buf, len);
 }
 
 static void c_write_untrusted(Ssh ssh, const char *buf, int len)
 {
-    int i;
-    for (i = 0; i < len; i++) {
-       if (buf[i] == '\n')
-           c_write(ssh, "\r\n", 2);
-       else if ((buf[i] & 0x60) || (buf[i] == '\r'))
-           c_write(ssh, buf + i, 1);
-    }
+    if (flags & FLAG_STDERR)
+       c_write_stderr(0, buf, len);
+    else
+       from_backend_untrusted(ssh->frontend, buf, len);
 }
 
 static void c_write_str(Ssh ssh, const char *buf)
@@ -1083,13 +1166,119 @@ static struct Packet *ssh_new_packet(void)
 
     pkt->body = pkt->data = NULL;
     pkt->maxlen = 0;
-    pkt->logmode = PKTLOG_EMIT;
-    pkt->nblanks = 0;
-    pkt->blanks = NULL;
 
     return pkt;
 }
 
+static void ssh1_log_incoming_packet(Ssh ssh, struct Packet *pkt)
+{
+    int nblanks = 0;
+    struct logblank_t blanks[4];
+    char *str;
+    int slen;
+
+    pkt->savedpos = 0;
+
+    if (ssh->logomitdata &&
+        (pkt->type == SSH1_SMSG_STDOUT_DATA ||
+         pkt->type == SSH1_SMSG_STDERR_DATA ||
+         pkt->type == SSH1_MSG_CHANNEL_DATA)) {
+        /* "Session data" packets - omit the data string. */
+        if (pkt->type == SSH1_MSG_CHANNEL_DATA)
+            ssh_pkt_getuint32(pkt);    /* skip channel id */
+        blanks[nblanks].offset = pkt->savedpos + 4;
+        blanks[nblanks].type = PKTLOG_OMIT;
+        ssh_pkt_getstring(pkt, &str, &slen);
+        if (str) {
+            blanks[nblanks].len = slen;
+            nblanks++;
+        }
+    }
+    log_packet(ssh->logctx, PKT_INCOMING, pkt->type,
+               ssh1_pkt_type(pkt->type),
+               pkt->body, pkt->length, nblanks, blanks, NULL,
+               0, NULL);
+}
+
+static void ssh1_log_outgoing_packet(Ssh ssh, struct Packet *pkt)
+{
+    int nblanks = 0;
+    struct logblank_t blanks[4];
+    char *str;
+    int slen;
+
+    /*
+     * For outgoing packets, pkt->length represents the length of the
+     * whole packet starting at pkt->data (including some header), and
+     * pkt->body refers to the point within that where the log-worthy
+     * payload begins. However, incoming packets expect pkt->length to
+     * represent only the payload length (that is, it's measured from
+     * pkt->body not from pkt->data). Temporarily adjust our outgoing
+     * packet to conform to the incoming-packet semantics, so that we
+     * can analyse it with the ssh_pkt_get functions.
+     */
+    pkt->length -= (pkt->body - pkt->data);
+    pkt->savedpos = 0;
+
+    if (ssh->logomitdata &&
+        (pkt->type == SSH1_CMSG_STDIN_DATA ||
+         pkt->type == SSH1_MSG_CHANNEL_DATA)) {
+        /* "Session data" packets - omit the data string. */
+        if (pkt->type == SSH1_MSG_CHANNEL_DATA)
+            ssh_pkt_getuint32(pkt);    /* skip channel id */
+        blanks[nblanks].offset = pkt->savedpos + 4;
+        blanks[nblanks].type = PKTLOG_OMIT;
+        ssh_pkt_getstring(pkt, &str, &slen);
+        if (str) {
+            blanks[nblanks].len = slen;
+            nblanks++;
+        }
+    }
+
+    if ((pkt->type == SSH1_CMSG_AUTH_PASSWORD ||
+         pkt->type == SSH1_CMSG_AUTH_TIS_RESPONSE ||
+         pkt->type == SSH1_CMSG_AUTH_CCARD_RESPONSE) &&
+        conf_get_int(ssh->conf, CONF_logomitpass)) {
+        /* If this is a password or similar packet, blank the password(s). */
+        blanks[nblanks].offset = 0;
+        blanks[nblanks].len = pkt->length;
+        blanks[nblanks].type = PKTLOG_BLANK;
+        nblanks++;
+    } else if (pkt->type == SSH1_CMSG_X11_REQUEST_FORWARDING &&
+               conf_get_int(ssh->conf, CONF_logomitpass)) {
+        /*
+         * If this is an X forwarding request packet, blank the fake
+         * auth data.
+         *
+         * Note that while we blank the X authentication data here, we
+         * don't take any special action to blank the start of an X11
+         * channel, so using MIT-MAGIC-COOKIE-1 and actually opening
+         * an X connection without having session blanking enabled is
+         * likely to leak your cookie into the log.
+         */
+        pkt->savedpos = 0;
+        ssh_pkt_getstring(pkt, &str, &slen);
+        blanks[nblanks].offset = pkt->savedpos;
+        blanks[nblanks].type = PKTLOG_BLANK;
+        ssh_pkt_getstring(pkt, &str, &slen);
+        if (str) {
+            blanks[nblanks].len = pkt->savedpos - blanks[nblanks].offset;
+            nblanks++;
+        }
+    }
+
+    log_packet(ssh->logctx, PKT_OUTGOING, pkt->data[12],
+               ssh1_pkt_type(pkt->data[12]),
+               pkt->body, pkt->length,
+               nblanks, blanks, NULL, 0, NULL);
+
+    /*
+     * Undo the above adjustment of pkt->length, to put the packet
+     * back in the state we found it.
+     */
+    pkt->length += (pkt->body - pkt->data);
+}
+
 /*
  * Collect incoming data in the incoming packet buffer.
  * Decipher and verify the packet when it is completely read.
@@ -1163,7 +1352,6 @@ static struct Packet *ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     }
 
     st->pktin->body = st->pktin->data + st->pad + 1;
-    st->pktin->savedpos = 0;
 
     if (ssh->v1_compressing) {
        unsigned char *decompblk;
@@ -1192,37 +1380,167 @@ static struct Packet *ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     st->pktin->type = st->pktin->body[-1];
 
     /*
-     * Log incoming packet, possibly omitting sensitive fields.
+     * Now pktin->body and pktin->length identify the semantic content
+     * of the packet, excluding the initial type byte.
      */
-    if (ssh->logctx) {
-       int nblanks = 0;
-       struct logblank_t blank;
-       if (ssh->cfg.logomitdata) {
-           int do_blank = FALSE, blank_prefix = 0;
-           /* "Session data" packets - omit the data field */
-           if ((st->pktin->type == SSH1_SMSG_STDOUT_DATA) ||
-               (st->pktin->type == SSH1_SMSG_STDERR_DATA)) {
-               do_blank = TRUE; blank_prefix = 0;
-           } else if (st->pktin->type == SSH1_MSG_CHANNEL_DATA) {
-               do_blank = TRUE; blank_prefix = 4;
-           }
-           if (do_blank) {
-               blank.offset = blank_prefix;
-               blank.len = st->pktin->length;
-               blank.type = PKTLOG_OMIT;
-               nblanks = 1;
-           }
-       }
-       log_packet(ssh->logctx,
-                  PKT_INCOMING, st->pktin->type,
-                  ssh1_pkt_type(st->pktin->type),
-                  st->pktin->body, st->pktin->length,
-                  nblanks, &blank);
-    }
+
+    if (ssh->logctx)
+        ssh1_log_incoming_packet(ssh, st->pktin);
+
+    st->pktin->savedpos = 0;
 
     crFinish(st->pktin);
 }
 
+static void ssh2_log_incoming_packet(Ssh ssh, struct Packet *pkt)
+{
+    int nblanks = 0;
+    struct logblank_t blanks[4];
+    char *str;
+    int slen;
+
+    pkt->savedpos = 0;
+
+    if (ssh->logomitdata &&
+        (pkt->type == SSH2_MSG_CHANNEL_DATA ||
+         pkt->type == SSH2_MSG_CHANNEL_EXTENDED_DATA)) {
+        /* "Session data" packets - omit the data string. */
+        ssh_pkt_getuint32(pkt);    /* skip channel id */
+        if (pkt->type == SSH2_MSG_CHANNEL_EXTENDED_DATA)
+            ssh_pkt_getuint32(pkt);    /* skip extended data type */
+        blanks[nblanks].offset = pkt->savedpos + 4;
+        blanks[nblanks].type = PKTLOG_OMIT;
+        ssh_pkt_getstring(pkt, &str, &slen);
+        if (str) {
+            blanks[nblanks].len = slen;
+            nblanks++;
+        }
+    }
+
+    log_packet(ssh->logctx, PKT_INCOMING, pkt->type,
+               ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx, pkt->type),
+               pkt->body, pkt->length, nblanks, blanks, &pkt->sequence,
+               0, NULL);
+}
+
+static void ssh2_log_outgoing_packet(Ssh ssh, struct Packet *pkt)
+{
+    int nblanks = 0;
+    struct logblank_t blanks[4];
+    char *str;
+    int slen;
+
+    /*
+     * For outgoing packets, pkt->length represents the length of the
+     * whole packet starting at pkt->data (including some header), and
+     * pkt->body refers to the point within that where the log-worthy
+     * payload begins. However, incoming packets expect pkt->length to
+     * represent only the payload length (that is, it's measured from
+     * pkt->body not from pkt->data). Temporarily adjust our outgoing
+     * packet to conform to the incoming-packet semantics, so that we
+     * can analyse it with the ssh_pkt_get functions.
+     */
+    pkt->length -= (pkt->body - pkt->data);
+    pkt->savedpos = 0;
+
+    if (ssh->logomitdata &&
+        (pkt->type == SSH2_MSG_CHANNEL_DATA ||
+         pkt->type == SSH2_MSG_CHANNEL_EXTENDED_DATA)) {
+        /* "Session data" packets - omit the data string. */
+        ssh_pkt_getuint32(pkt);    /* skip channel id */
+        if (pkt->type == SSH2_MSG_CHANNEL_EXTENDED_DATA)
+            ssh_pkt_getuint32(pkt);    /* skip extended data type */
+        blanks[nblanks].offset = pkt->savedpos + 4;
+        blanks[nblanks].type = PKTLOG_OMIT;
+        ssh_pkt_getstring(pkt, &str, &slen);
+        if (str) {
+            blanks[nblanks].len = slen;
+            nblanks++;
+        }
+    }
+
+    if (pkt->type == SSH2_MSG_USERAUTH_REQUEST &&
+        conf_get_int(ssh->conf, CONF_logomitpass)) {
+        /* If this is a password packet, blank the password(s). */
+        pkt->savedpos = 0;
+        ssh_pkt_getstring(pkt, &str, &slen);
+        ssh_pkt_getstring(pkt, &str, &slen);
+        ssh_pkt_getstring(pkt, &str, &slen);
+        if (slen == 8 && !memcmp(str, "password", 8)) {
+            ssh2_pkt_getbool(pkt);
+            /* Blank the password field. */
+            blanks[nblanks].offset = pkt->savedpos;
+            blanks[nblanks].type = PKTLOG_BLANK;
+            ssh_pkt_getstring(pkt, &str, &slen);
+            if (str) {
+                blanks[nblanks].len = pkt->savedpos - blanks[nblanks].offset;
+                nblanks++;
+                /* If there's another password field beyond it (change of
+                 * password), blank that too. */
+                ssh_pkt_getstring(pkt, &str, &slen);
+                if (str)
+                    blanks[nblanks-1].len =
+                        pkt->savedpos - blanks[nblanks].offset;
+            }
+        }
+    } else if (ssh->pkt_actx == SSH2_PKTCTX_KBDINTER &&
+               pkt->type == SSH2_MSG_USERAUTH_INFO_RESPONSE &&
+               conf_get_int(ssh->conf, CONF_logomitpass)) {
+        /* If this is a keyboard-interactive response packet, blank
+         * the responses. */
+        pkt->savedpos = 0;
+        ssh_pkt_getuint32(pkt);
+        blanks[nblanks].offset = pkt->savedpos;
+        blanks[nblanks].type = PKTLOG_BLANK;
+        while (1) {
+            ssh_pkt_getstring(pkt, &str, &slen);
+            if (!str)
+                break;
+        }
+        blanks[nblanks].len = pkt->savedpos - blanks[nblanks].offset;
+        nblanks++;
+    } else if (pkt->type == SSH2_MSG_CHANNEL_REQUEST &&
+               conf_get_int(ssh->conf, CONF_logomitpass)) {
+        /*
+         * If this is an X forwarding request packet, blank the fake
+         * auth data.
+         *
+         * Note that while we blank the X authentication data here, we
+         * don't take any special action to blank the start of an X11
+         * channel, so using MIT-MAGIC-COOKIE-1 and actually opening
+         * an X connection without having session blanking enabled is
+         * likely to leak your cookie into the log.
+         */
+        pkt->savedpos = 0;
+        ssh_pkt_getuint32(pkt);
+        ssh_pkt_getstring(pkt, &str, &slen);
+        if (slen == 7 && !memcmp(str, "x11-req", 0)) {
+            ssh2_pkt_getbool(pkt);
+            ssh2_pkt_getbool(pkt);
+            ssh_pkt_getstring(pkt, &str, &slen);
+            blanks[nblanks].offset = pkt->savedpos;
+            blanks[nblanks].type = PKTLOG_BLANK;
+            ssh_pkt_getstring(pkt, &str, &slen);
+            if (str) {
+                blanks[nblanks].len = pkt->savedpos - blanks[nblanks].offset;
+                nblanks++;
+            }
+        }
+    }
+
+    log_packet(ssh->logctx, PKT_OUTGOING, pkt->data[5],
+               ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx, pkt->data[5]),
+               pkt->body, pkt->length, nblanks, blanks,
+               &ssh->v2_outgoing_sequence,
+               pkt->downstream_id, pkt->additional_log_text);
+
+    /*
+     * Undo the above adjustment of pkt->length, to put the packet
+     * back in the state we found it.
+     */
+    pkt->length += (pkt->body - pkt->data);
+}
+
 static struct Packet *ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 {
     struct rdpkt2_state_tag *st = &ssh->rdpkt2_state;
@@ -1239,93 +1557,169 @@ static struct Packet *ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
        st->cipherblk = 8;
     if (st->cipherblk < 8)
        st->cipherblk = 8;
+    st->maclen = ssh->scmac ? ssh->scmac->len : 0;
 
-    st->pktin->data = snewn(st->cipherblk + APIEXTRA, unsigned char);
+    if (ssh->sccipher && (ssh->sccipher->flags & SSH_CIPHER_IS_CBC) &&
+       ssh->scmac) {
+       /*
+        * When dealing with a CBC-mode cipher, we want to avoid the
+        * possibility of an attacker's tweaking the ciphertext stream
+        * so as to cause us to feed the same block to the block
+        * cipher more than once and thus leak information
+        * (VU#958563).  The way we do this is not to take any
+        * decisions on the basis of anything we've decrypted until
+        * we've verified it with a MAC.  That includes the packet
+        * length, so we just read data and check the MAC repeatedly,
+        * and when the MAC passes, see if the length we've got is
+        * plausible.
+        */
 
-    /*
-     * Acquire and decrypt the first block of the packet. This will
-     * contain the length and padding details.
-     */
-    for (st->i = st->len = 0; st->i < st->cipherblk; st->i++) {
-       while ((*datalen) == 0)
-           crReturn(NULL);
-       st->pktin->data[st->i] = *(*data)++;
-       (*datalen)--;
-    }
+       /* May as well allocate the whole lot now. */
+       st->pktin->data = snewn(OUR_V2_PACKETLIMIT + st->maclen + APIEXTRA,
+                               unsigned char);
 
-    if (ssh->sccipher)
-       ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
-                              st->pktin->data, st->cipherblk);
+       /* Read an amount corresponding to the MAC. */
+       for (st->i = 0; st->i < st->maclen; st->i++) {
+           while ((*datalen) == 0)
+               crReturn(NULL);
+           st->pktin->data[st->i] = *(*data)++;
+           (*datalen)--;
+       }
 
-    /*
-     * Now get the length and padding figures.
-     */
-    st->len = GET_32BIT(st->pktin->data);
-    st->pad = st->pktin->data[4];
+       st->packetlen = 0;
+       {
+           unsigned char seq[4];
+           ssh->scmac->start(ssh->sc_mac_ctx);
+           PUT_32BIT(seq, st->incoming_sequence);
+           ssh->scmac->bytes(ssh->sc_mac_ctx, seq, 4);
+       }
 
-    /*
-     * _Completely_ silly lengths should be stomped on before they
-     * do us any more damage.
-     */
-    if (st->len < 0 || st->len > 35000 || st->pad < 4 ||
-       st->len - st->pad < 1 || (st->len + 4) % st->cipherblk != 0) {
-       bombout(("Incoming packet was garbled on decryption"));
-       ssh_free_packet(st->pktin);
-       crStop(NULL);
-    }
+       for (;;) { /* Once around this loop per cipher block. */
+           /* Read another cipher-block's worth, and tack it onto the end. */
+           for (st->i = 0; st->i < st->cipherblk; st->i++) {
+               while ((*datalen) == 0)
+                   crReturn(NULL);
+               st->pktin->data[st->packetlen+st->maclen+st->i] = *(*data)++;
+               (*datalen)--;
+           }
+           /* Decrypt one more block (a little further back in the stream). */
+           ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
+                                  st->pktin->data + st->packetlen,
+                                  st->cipherblk);
+           /* Feed that block to the MAC. */
+           ssh->scmac->bytes(ssh->sc_mac_ctx,
+                             st->pktin->data + st->packetlen, st->cipherblk);
+           st->packetlen += st->cipherblk;
+           /* See if that gives us a valid packet. */
+           if (ssh->scmac->verresult(ssh->sc_mac_ctx,
+                                     st->pktin->data + st->packetlen) &&
+               ((st->len = toint(GET_32BIT(st->pktin->data))) ==
+                 st->packetlen-4))
+                   break;
+           if (st->packetlen >= OUR_V2_PACKETLIMIT) {
+               bombout(("No valid incoming packet found"));
+               ssh_free_packet(st->pktin);
+               crStop(NULL);
+           }       
+       }
+       st->pktin->maxlen = st->packetlen + st->maclen;
+       st->pktin->data = sresize(st->pktin->data,
+                                 st->pktin->maxlen + APIEXTRA,
+                                 unsigned char);
+    } else {
+       st->pktin->data = snewn(st->cipherblk + APIEXTRA, unsigned char);
 
-    /*
-     * This enables us to deduce the payload length.
-     */
-    st->payload = st->len - st->pad - 1;
+       /*
+        * Acquire and decrypt the first block of the packet. This will
+        * contain the length and padding details.
+        */
+       for (st->i = st->len = 0; st->i < st->cipherblk; st->i++) {
+           while ((*datalen) == 0)
+               crReturn(NULL);
+           st->pktin->data[st->i] = *(*data)++;
+           (*datalen)--;
+       }
 
-    st->pktin->length = st->payload + 5;
+       if (ssh->sccipher)
+           ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
+                                  st->pktin->data, st->cipherblk);
 
-    /*
-     * So now we can work out the total packet length.
-     */
-    st->packetlen = st->len + 4;
-    st->maclen = ssh->scmac ? ssh->scmac->len : 0;
+       /*
+        * Now get the length figure.
+        */
+       st->len = toint(GET_32BIT(st->pktin->data));
 
-    /*
-     * Allocate memory for the rest of the packet.
-     */
-    st->pktin->maxlen = st->packetlen + st->maclen;
-    st->pktin->data = sresize(st->pktin->data,
-                             st->pktin->maxlen + APIEXTRA,
-                             unsigned char);
+       /*
+        * _Completely_ silly lengths should be stomped on before they
+        * do us any more damage.
+        */
+       if (st->len < 0 || st->len > OUR_V2_PACKETLIMIT ||
+           (st->len + 4) % st->cipherblk != 0) {
+           bombout(("Incoming packet was garbled on decryption"));
+           ssh_free_packet(st->pktin);
+           crStop(NULL);
+       }
 
-    /*
-     * Read and decrypt the remainder of the packet.
-     */
-    for (st->i = st->cipherblk; st->i < st->packetlen + st->maclen;
-        st->i++) {
-       while ((*datalen) == 0)
-           crReturn(NULL);
-       st->pktin->data[st->i] = *(*data)++;
-       (*datalen)--;
-    }
-    /* Decrypt everything _except_ the MAC. */
-    if (ssh->sccipher)
-       ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
-                              st->pktin->data + st->cipherblk,
-                              st->packetlen - st->cipherblk);
+       /*
+        * So now we can work out the total packet length.
+        */
+       st->packetlen = st->len + 4;
 
-    st->pktin->encrypted_len = st->packetlen;
+       /*
+        * Allocate memory for the rest of the packet.
+        */
+       st->pktin->maxlen = st->packetlen + st->maclen;
+       st->pktin->data = sresize(st->pktin->data,
+                                 st->pktin->maxlen + APIEXTRA,
+                                 unsigned char);
 
-    /*
-     * Check the MAC.
-     */
-    if (ssh->scmac
-       && !ssh->scmac->verify(ssh->sc_mac_ctx, st->pktin->data, st->len + 4,
-                              st->incoming_sequence)) {
-       bombout(("Incorrect MAC received on packet"));
+       /*
+        * Read and decrypt the remainder of the packet.
+        */
+       for (st->i = st->cipherblk; st->i < st->packetlen + st->maclen;
+            st->i++) {
+           while ((*datalen) == 0)
+               crReturn(NULL);
+           st->pktin->data[st->i] = *(*data)++;
+           (*datalen)--;
+       }
+       /* Decrypt everything _except_ the MAC. */
+       if (ssh->sccipher)
+           ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
+                                  st->pktin->data + st->cipherblk,
+                                  st->packetlen - st->cipherblk);
+
+       /*
+        * Check the MAC.
+        */
+       if (ssh->scmac
+           && !ssh->scmac->verify(ssh->sc_mac_ctx, st->pktin->data,
+                                  st->len + 4, st->incoming_sequence)) {
+           bombout(("Incorrect MAC received on packet"));
+           ssh_free_packet(st->pktin);
+           crStop(NULL);
+       }
+    }
+    /* Get and sanity-check the amount of random padding. */
+    st->pad = st->pktin->data[4];
+    if (st->pad < 4 || st->len - st->pad < 1) {
+       bombout(("Invalid padding length on received packet"));
        ssh_free_packet(st->pktin);
        crStop(NULL);
     }
+    /*
+     * This enables us to deduce the payload length.
+     */
+    st->payload = st->len - st->pad - 1;
+
+    st->pktin->length = st->payload + 5;
+    st->pktin->encrypted_len = st->packetlen;
 
     st->pktin->sequence = st->incoming_sequence++;
 
+    st->pktin->length = st->packetlen - st->pad;
+    assert(st->pktin->length >= 0);
+
     /*
      * Decompress packet payload.
      */
@@ -1348,62 +1742,99 @@ static struct Packet *ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
        }
     }
 
-    st->pktin->savedpos = 6;
-    st->pktin->body = st->pktin->data;
-    st->pktin->type = st->pktin->data[5];
-
     /*
-     * Log incoming packet, possibly omitting sensitive fields.
+     * pktin->body and pktin->length should identify the semantic
+     * content of the packet, excluding the initial type byte.
      */
-    if (ssh->logctx) {
-       int nblanks = 0;
-       struct logblank_t blank;
-       if (ssh->cfg.logomitdata) {
-           int do_blank = FALSE, blank_prefix = 0;
-           /* "Session data" packets - omit the data field */
-           if (st->pktin->type == SSH2_MSG_CHANNEL_DATA) {
-               do_blank = TRUE; blank_prefix = 4;
-           } else if (st->pktin->type == SSH2_MSG_CHANNEL_EXTENDED_DATA) {
-               do_blank = TRUE; blank_prefix = 8;
-           }
-           if (do_blank) {
-               blank.offset = blank_prefix;
-               blank.len = (st->pktin->length-6) - blank_prefix;
-               blank.type = PKTLOG_OMIT;
-               nblanks = 1;
-           }
-       }
-       log_packet(ssh->logctx, PKT_INCOMING, st->pktin->type,
-                  ssh2_pkt_type(ssh->pkt_ctx, st->pktin->type),
-                  st->pktin->data+6, st->pktin->length-6,
-                  nblanks, &blank);
-    }
+    st->pktin->type = st->pktin->data[5];
+    st->pktin->body = st->pktin->data + 6;
+    st->pktin->length -= 6;
+    assert(st->pktin->length >= 0);    /* one last double-check */
+
+    if (ssh->logctx)
+        ssh2_log_incoming_packet(ssh, st->pktin);
+
+    st->pktin->savedpos = 0;
 
     crFinish(st->pktin);
 }
 
-static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt, int *offset_p)
+static struct Packet *ssh2_bare_connection_rdpkt(Ssh ssh, unsigned char **data,
+                                                 int *datalen)
 {
-    int pad, biglen, i, pktoffs;
-    unsigned long crc;
-#ifdef __SC__
+    struct rdpkt2_bare_state_tag *st = &ssh->rdpkt2_bare_state;
+
+    crBegin(ssh->ssh2_bare_rdpkt_crstate);
+
     /*
-     * XXX various versions of SC (including 8.8.4) screw up the
-     * register allocation in this function and use the same register
-     * (D6) for len and as a temporary, with predictable results.  The
-     * following sledgehammer prevents this.
+     * Read the packet length field.
      */
-    volatile
-#endif
-    int len;
-
-    if (ssh->logctx)
-       log_packet(ssh->logctx, PKT_OUTGOING, pkt->data[12],
-                  ssh1_pkt_type(pkt->data[12]),
-                  pkt->body, pkt->length - (pkt->body - pkt->data),
-                  pkt->nblanks, pkt->blanks);
-    sfree(pkt->blanks); pkt->blanks = NULL;
-    pkt->nblanks = 0;
+    for (st->i = 0; st->i < 4; st->i++) {
+        while ((*datalen) == 0)
+            crReturn(NULL);
+        st->length[st->i] = *(*data)++;
+        (*datalen)--;
+    }
+
+    st->packetlen = toint(GET_32BIT_MSB_FIRST(st->length));
+    if (st->packetlen <= 0 || st->packetlen >= OUR_V2_PACKETLIMIT) {
+        bombout(("Invalid packet length received"));
+        crStop(NULL);
+    }
+
+    st->pktin = ssh_new_packet();
+    st->pktin->data = snewn(st->packetlen, unsigned char);
+
+    st->pktin->encrypted_len = st->packetlen;
+
+    st->pktin->sequence = st->incoming_sequence++;
+
+    /*
+     * Read the remainder of the packet.
+     */
+    for (st->i = 0; st->i < st->packetlen; st->i++) {
+        while ((*datalen) == 0)
+            crReturn(NULL);
+        st->pktin->data[st->i] = *(*data)++;
+        (*datalen)--;
+    }
+
+    /*
+     * pktin->body and pktin->length should identify the semantic
+     * content of the packet, excluding the initial type byte.
+     */
+    st->pktin->type = st->pktin->data[0];
+    st->pktin->body = st->pktin->data + 1;
+    st->pktin->length = st->packetlen - 1;
+
+    /*
+     * Log incoming packet, possibly omitting sensitive fields.
+     */
+    if (ssh->logctx)
+        ssh2_log_incoming_packet(ssh, st->pktin);
+
+    st->pktin->savedpos = 0;
+
+    crFinish(st->pktin);
+}
+
+static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt, int *offset_p)
+{
+    int pad, biglen, i, pktoffs;
+    unsigned long crc;
+#ifdef __SC__
+    /*
+     * XXX various versions of SC (including 8.8.4) screw up the
+     * register allocation in this function and use the same register
+     * (D6) for len and as a temporary, with predictable results.  The
+     * following sledgehammer prevents this.
+     */
+    volatile
+#endif
+    int len;
+
+    if (ssh->logctx)
+        ssh1_log_outgoing_packet(ssh, pkt);
 
     if (ssh->v1_compressing) {
        unsigned char *compblk;
@@ -1411,6 +1842,7 @@ static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt, int *offset_p)
        zlib_compress_block(ssh->cs_comp_ctx,
                            pkt->data + 12, pkt->length - 12,
                            &compblk, &complen);
+       ssh_pkt_ensure(pkt, complen + 2);   /* just in case it's got bigger */
        memcpy(pkt->data + 12, compblk, complen);
        sfree(compblk);
        pkt->length = complen + 12;
@@ -1437,11 +1869,21 @@ static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt, int *offset_p)
     return biglen + 4;         /* len(length+padding+type+data+CRC) */
 }
 
+static int s_write(Ssh ssh, void *data, int len)
+{
+    if (ssh->logctx)
+       log_packet(ssh->logctx, PKT_OUTGOING, -1, NULL, data, len,
+                  0, NULL, NULL, 0, NULL);
+    if (!ssh->s)
+        return 0;
+    return sk_write(ssh->s, (char *)data, len);
+}
+
 static void s_wrpkt(Ssh ssh, struct Packet *pkt)
 {
     int len, backlog, offset;
     len = s_wrpkt_prepare(ssh, pkt, &offset);
-    backlog = sk_write(ssh->s, (char *)pkt->data + offset, len);
+    backlog = s_write(ssh, pkt->data + offset, len);
     if (backlog > SSH_MAX_BACKLOG)
        ssh_throttle_all(ssh, 1, backlog);
     ssh_free_packet(pkt);
@@ -1478,6 +1920,7 @@ static struct Packet *construct_packet(Ssh ssh, int pkttype, va_list ap)
 
     while ((argtype = va_arg(ap, int)) != PKT_END) {
        unsigned char *argp, argchar;
+       char *sargp;
        unsigned long argint;
        int arglen;
        switch (argtype) {
@@ -1496,23 +1939,13 @@ static struct Packet *construct_packet(Ssh ssh, int pkttype, va_list ap)
            ssh_pkt_adddata(pkt, argp, arglen);
            break;
          case PKT_STR:
-           argp = va_arg(ap, unsigned char *);
-           ssh_pkt_addstring(pkt, argp);
+           sargp = va_arg(ap, char *);
+           ssh_pkt_addstring(pkt, sargp);
            break;
          case PKT_BIGNUM:
            bn = va_arg(ap, Bignum);
            ssh1_pkt_addmp(pkt, bn);
            break;
-         /* Tokens for modifications to packet logging */
-         case PKTT_PASSWORD:
-           dont_log_password(ssh, pkt, PKTLOG_BLANK);
-           break;
-         case PKTT_DATA:
-           dont_log_data(ssh, pkt, PKTLOG_OMIT);
-           break;
-         case PKTT_OTHER:
-           end_log_omission(ssh, pkt);
-           break;
        }
     }
 
@@ -1561,21 +1994,21 @@ static int ssh_versioncmp(char *a, char *b)
 
 /*
  * Utility routines for putting an SSH-protocol `string' and
- * `uint32' into a SHA state.
+ * `uint32' into a hash state.
  */
-static void sha_string(SHA_State * s, void *str, int len)
+static void hash_string(const struct ssh_hash *h, void *s, void *str, int len)
 {
     unsigned char lenblk[4];
     PUT_32BIT(lenblk, len);
-    SHA_Bytes(s, lenblk, 4);
-    SHA_Bytes(s, str, len);
+    h->bytes(s, lenblk, 4);
+    h->bytes(s, str, len);
 }
 
-static void sha_uint32(SHA_State * s, unsigned i)
+static void hash_uint32(const struct ssh_hash *h, void *s, unsigned i)
 {
     unsigned char intblk[4];
     PUT_32BIT(intblk, i);
-    SHA_Bytes(s, intblk, 4);
+    h->bytes(s, intblk, 4);
 }
 
 /*
@@ -1585,23 +2018,14 @@ static void ssh_pkt_ensure(struct Packet *pkt, int length)
 {
     if (pkt->maxlen < length) {
        unsigned char *body = pkt->body;
-       int offset = body ? pkt->data - body : 0;
+       int offset = body ? body - pkt->data : 0;
        pkt->maxlen = length + 256;
        pkt->data = sresize(pkt->data, pkt->maxlen + APIEXTRA, unsigned char);
        if (body) pkt->body = pkt->data + offset;
     }
 }
-static void ssh_pkt_adddata(struct Packet *pkt, void *data, int len)
+static void ssh_pkt_adddata(struct Packet *pkt, const void *data, int len)
 {
-    if (pkt->logmode != PKTLOG_EMIT) {
-       pkt->nblanks++;
-       pkt->blanks = sresize(pkt->blanks, pkt->nblanks, struct logblank_t);
-       assert(pkt->body);
-       pkt->blanks[pkt->nblanks-1].offset = pkt->length -
-                                            (pkt->body - pkt->data);
-       pkt->blanks[pkt->nblanks-1].len = len;
-       pkt->blanks[pkt->nblanks-1].type = pkt->logmode;
-    }
     pkt->length += len;
     ssh_pkt_ensure(pkt, pkt->length);
     memcpy(pkt->data + pkt->length - len, data, len);
@@ -1625,17 +2049,18 @@ static void ssh_pkt_addstring_start(struct Packet *pkt)
     ssh_pkt_adduint32(pkt, 0);
     pkt->savedpos = pkt->length;
 }
-static void ssh_pkt_addstring_str(struct Packet *pkt, char *data)
+static void ssh_pkt_addstring_str(struct Packet *pkt, const char *data)
 {
     ssh_pkt_adddata(pkt, data, strlen(data));
     PUT_32BIT(pkt->data + pkt->savedpos - 4, pkt->length - pkt->savedpos);
 }
-static void ssh_pkt_addstring_data(struct Packet *pkt, char *data, int len)
+static void ssh_pkt_addstring_data(struct Packet *pkt, const char *data,
+                                   int len)
 {
     ssh_pkt_adddata(pkt, data, len);
     PUT_32BIT(pkt->data + pkt->savedpos - 4, pkt->length - pkt->savedpos);
 }
-static void ssh_pkt_addstring(struct Packet *pkt, char *data)
+static void ssh_pkt_addstring(struct Packet *pkt, const char *data)
 {
     ssh_pkt_addstring_start(pkt);
     ssh_pkt_addstring_str(pkt, data);
@@ -1643,7 +2068,7 @@ static void ssh_pkt_addstring(struct Packet *pkt, char *data)
 static void ssh1_pkt_addmp(struct Packet *pkt, Bignum b)
 {
     int len = ssh1_bignum_length(b);
-    unsigned char *data = snewn(len, char);
+    unsigned char *data = snewn(len, unsigned char);
     (void) ssh1_write_bignum(data, b);
     ssh_pkt_adddata(pkt, data, len);
     sfree(data);
@@ -1679,6 +2104,9 @@ static struct Packet *ssh1_pkt_init(int pkt_type)
     pkt->length = 4 + 8;           /* space for length + max padding */
     ssh_pkt_addbyte(pkt, pkt_type);
     pkt->body = pkt->data + pkt->length;
+    pkt->type = pkt_type;
+    pkt->downstream_id = 0;
+    pkt->additional_log_text = NULL;
     return pkt;
 }
 
@@ -1695,10 +2123,13 @@ static struct Packet *ssh1_pkt_init(int pkt_type)
 static struct Packet *ssh2_pkt_init(int pkt_type)
 {
     struct Packet *pkt = ssh_new_packet();
-    pkt->length = 5;
+    pkt->length = 5; /* space for packet length + padding length */
     pkt->forcepad = 0;
+    pkt->type = pkt_type;
     ssh_pkt_addbyte(pkt, (unsigned char) pkt_type);
-    pkt->body = pkt->data + pkt->length;
+    pkt->body = pkt->data + pkt->length; /* after packet type */
+    pkt->downstream_id = 0;
+    pkt->additional_log_text = NULL;
     return pkt;
 }
 
@@ -1712,12 +2143,18 @@ static int ssh2_pkt_construct(Ssh ssh, struct Packet *pkt)
     int cipherblk, maclen, padding, i;
 
     if (ssh->logctx)
-       log_packet(ssh->logctx, PKT_OUTGOING, pkt->data[5],
-                  ssh2_pkt_type(ssh->pkt_ctx, pkt->data[5]),
-                  pkt->body, pkt->length - (pkt->body - pkt->data),
-                  pkt->nblanks, pkt->blanks);
-    sfree(pkt->blanks); pkt->blanks = NULL;
-    pkt->nblanks = 0;
+        ssh2_log_outgoing_packet(ssh, pkt);
+
+    if (ssh->bare_connection) {
+        /*
+         * Trivial packet construction for the bare connection
+         * protocol.
+         */
+        PUT_32BIT(pkt->data + 1, pkt->length - 5);
+        pkt->body = pkt->data + 1;
+        ssh->v2_outgoing_sequence++;   /* only for diagnostics, really */
+        return pkt->length - 1;
+    }
 
     /*
      * Compress packet payload.
@@ -1768,6 +2205,7 @@ static int ssh2_pkt_construct(Ssh ssh, struct Packet *pkt)
     pkt->encrypted_len = pkt->length + padding;
 
     /* Ready-to-send packet starts at pkt->data. We return length. */
+    pkt->body = pkt->data;
     return pkt->length + padding + maclen;
 }
 
@@ -1825,12 +2263,13 @@ static void ssh2_pkt_send_noqueue(Ssh ssh, struct Packet *pkt)
        return;
     }
     len = ssh2_pkt_construct(ssh, pkt);
-    backlog = sk_write(ssh->s, (char *)pkt->data, len);
+    backlog = s_write(ssh, pkt->body, len);
     if (backlog > SSH_MAX_BACKLOG)
        ssh_throttle_all(ssh, 1, backlog);
 
     ssh->outgoing_data_size += pkt->encrypted_len;
     if (!ssh->kex_in_progress &&
+        !ssh->bare_connection &&
        ssh->max_data_size != 0 &&
        ssh->outgoing_data_size > ssh->max_data_size)
        do_ssh2_transport(ssh, "too much data sent", -1, NULL);
@@ -1845,12 +2284,14 @@ static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt, int noignore)
 {
     int len;
     if (ssh->cscipher != NULL && (ssh->cscipher->flags & SSH_CIPHER_IS_CBC) &&
-       ssh->deferred_len == 0 && !noignore) {
+       ssh->deferred_len == 0 && !noignore &&
+       !(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) {
        /*
         * Interpose an SSH_MSG_IGNORE to ensure that user data don't
         * get encrypted with a known IV.
         */
        struct Packet *ipkt = ssh2_pkt_init(SSH2_MSG_IGNORE);
+       ssh2_pkt_addstring_start(ipkt);
        ssh2_pkt_defer_noqueue(ssh, ipkt, TRUE);
     }
     len = ssh2_pkt_construct(ssh, pkt);
@@ -1860,7 +2301,7 @@ static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt, int noignore)
                                          ssh->deferred_size,
                                          unsigned char);
     }
-    memcpy(ssh->deferred_send_data + ssh->deferred_len, pkt->data, len);
+    memcpy(ssh->deferred_send_data + ssh->deferred_len, pkt->body, len);
     ssh->deferred_len += len;
     ssh->deferred_data_size += pkt->encrypted_len;
     ssh_free_packet(pkt);
@@ -1893,7 +2334,6 @@ static void ssh2_pkt_send(Ssh ssh, struct Packet *pkt)
        ssh2_pkt_send_noqueue(ssh, pkt);
 }
 
-#if 0 /* disused */
 /*
  * Either queue or defer a packet, depending on whether queueing is
  * set.
@@ -1905,7 +2345,6 @@ static void ssh2_pkt_defer(Ssh ssh, struct Packet *pkt)
     else
        ssh2_pkt_defer_noqueue(ssh, pkt, FALSE);
 }
-#endif
 
 /*
  * Send the whole deferred data block constructed by
@@ -1923,8 +2362,7 @@ static void ssh2_pkt_defer(Ssh ssh, struct Packet *pkt)
 static void ssh_pkt_defersend(Ssh ssh)
 {
     int backlog;
-    backlog = sk_write(ssh->s, (char *)ssh->deferred_send_data,
-                      ssh->deferred_len);
+    backlog = s_write(ssh, ssh->deferred_send_data, ssh->deferred_len);
     ssh->deferred_len = ssh->deferred_size = 0;
     sfree(ssh->deferred_send_data);
     ssh->deferred_send_data = NULL;
@@ -1933,12 +2371,82 @@ static void ssh_pkt_defersend(Ssh ssh)
 
     ssh->outgoing_data_size += ssh->deferred_data_size;
     if (!ssh->kex_in_progress &&
+        !ssh->bare_connection &&
        ssh->max_data_size != 0 &&
        ssh->outgoing_data_size > ssh->max_data_size)
        do_ssh2_transport(ssh, "too much data sent", -1, NULL);
     ssh->deferred_data_size = 0;
 }
 
+/*
+ * Send a packet whose length needs to be disguised (typically
+ * passwords or keyboard-interactive responses).
+ */
+static void ssh2_pkt_send_with_padding(Ssh ssh, struct Packet *pkt,
+                                      int padsize)
+{
+#if 0
+    if (0) {
+       /*
+        * The simplest way to do this is to adjust the
+        * variable-length padding field in the outgoing packet.
+        * 
+        * Currently compiled out, because some Cisco SSH servers
+        * don't like excessively padded packets (bah, why's it
+        * always Cisco?)
+        */
+       pkt->forcepad = padsize;
+       ssh2_pkt_send(ssh, pkt);
+    } else
+#endif
+    {
+       /*
+        * If we can't do that, however, an alternative approach is
+        * to use the pkt_defer mechanism to bundle the packet
+        * tightly together with an SSH_MSG_IGNORE such that their
+        * combined length is a constant. So first we construct the
+        * final form of this packet and defer its sending.
+        */
+       ssh2_pkt_defer(ssh, pkt);
+
+       /*
+        * Now construct an SSH_MSG_IGNORE which includes a string
+        * that's an exact multiple of the cipher block size. (If
+        * the cipher is NULL so that the block size is
+        * unavailable, we don't do this trick at all, because we
+        * gain nothing by it.)
+        */
+       if (ssh->cscipher &&
+           !(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) {
+           int stringlen, i;
+
+           stringlen = (256 - ssh->deferred_len);
+           stringlen += ssh->cscipher->blksize - 1;
+           stringlen -= (stringlen % ssh->cscipher->blksize);
+           if (ssh->cscomp) {
+               /*
+                * Temporarily disable actual compression, so we
+                * can guarantee to get this string exactly the
+                * length we want it. The compression-disabling
+                * routine should return an integer indicating how
+                * many bytes we should adjust our string length
+                * by.
+                */
+               stringlen -=
+                   ssh->cscomp->disable_compression(ssh->cs_comp_ctx);
+           }
+           pkt = ssh2_pkt_init(SSH2_MSG_IGNORE);
+           ssh2_pkt_addstring_start(pkt);
+           for (i = 0; i < stringlen; i++) {
+               char c = (char) random_byte();
+               ssh2_pkt_addstring_data(pkt, &c, 1);
+           }
+           ssh2_pkt_defer(ssh, pkt);
+       }
+       ssh_pkt_defersend(ssh);
+    }
+}
+
 /*
  * Send all queued SSH-2 packets. We send them by means of
  * ssh2_pkt_defer_noqueue(), in case they included a pair of
@@ -1971,12 +2479,12 @@ void bndebug(char *string, Bignum b)
 }
 #endif
 
-static void sha_mpint(SHA_State * s, Bignum b)
+static void hash_mpint(const struct ssh_hash *h, void *s, Bignum b)
 {
     unsigned char *p;
     int len;
     p = ssh2_mpint_fmt(b, &len);
-    sha_string(s, p, len);
+    hash_string(h, s, p, len);
     sfree(p);
 }
 
@@ -2008,7 +2516,7 @@ static void ssh_pkt_getstring(struct Packet *pkt, char **p, int *length)
     *length = 0;
     if (pkt->length - pkt->savedpos < 4)
        return;
-    len = GET_32BIT(pkt->body + pkt->savedpos);
+    len = toint(GET_32BIT(pkt->body + pkt->savedpos));
     if (len < 0)
        return;
     *length = len;
@@ -2092,7 +2600,7 @@ static void ssh2_add_sigblob(Ssh ssh, struct Packet *pkt,
      * See if this is in fact an ssh-rsa signature and a buggy
      * server; otherwise we can just do this the easy way.
      */
-    if ((ssh->remote_bugs & BUG_SSH2_RSA_PADDING) &&
+    if ((ssh->remote_bugs & BUG_SSH2_RSA_PADDING) && pkblob_len > 4+7+4 &&
        (GET_32BIT(pkblob) == 7 && !memcmp(pkblob+4, "ssh-rsa", 7))) {
        int pos, len, siglen;
 
@@ -2101,8 +2609,15 @@ static void ssh2_add_sigblob(Ssh ssh, struct Packet *pkt,
         */
 
        pos = 4+7;                     /* skip over "ssh-rsa" */
-       pos += 4 + GET_32BIT(pkblob+pos);   /* skip over exponent */
-       len = GET_32BIT(pkblob+pos);   /* find length of modulus */
+        len = toint(GET_32BIT(pkblob+pos)); /* get length of exponent */
+        if (len < 0 || len > pkblob_len - pos - 4)
+            goto give_up;
+       pos += 4 + len;                /* skip over exponent */
+        if (pkblob_len - pos < 4)
+            goto give_up;
+       len = toint(GET_32BIT(pkblob+pos)); /* find length of modulus */
+        if (len < 0 || len > pkblob_len - pos - 4)
+            goto give_up;
        pos += 4;                      /* find modulus itself */
        while (len > 0 && pkblob[pos] == 0)
            len--, pos++;
@@ -2112,7 +2627,11 @@ static void ssh2_add_sigblob(Ssh ssh, struct Packet *pkt,
         * Now find the signature integer.
         */
        pos = 4+7;                     /* skip over "ssh-rsa" */
-       siglen = GET_32BIT(sigblob+pos);
+        if (sigblob_len < pos+4)
+            goto give_up;
+       siglen = toint(GET_32BIT(sigblob+pos));
+        if (siglen != sigblob_len - pos - 4)
+            goto give_up;
        /* debug(("signature length is %d\n", siglen)); */
 
        if (len != siglen) {
@@ -2134,7 +2653,10 @@ static void ssh2_add_sigblob(Ssh ssh, struct Packet *pkt,
            return;
        }
 
-       /* Otherwise fall through and do it the easy way. */
+       /* Otherwise fall through and do it the easy way. We also come
+         * here as a fallback if we discover above that the key blob
+         * is misformatted in some way. */
+      give_up:;
     }
 
     ssh2_pkt_addstring_start(pkt);
@@ -2156,8 +2678,15 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 
     ssh->remote_bugs = 0;
 
-    if (ssh->cfg.sshbug_ignore1 == FORCE_ON ||
-       (ssh->cfg.sshbug_ignore1 == AUTO &&
+    /*
+     * General notes on server version strings:
+     *  - Not all servers reporting "Cisco-1.25" have all the bugs listed
+     *    here -- in particular, we've heard of one that's perfectly happy
+     *    with SSH1_MSG_IGNOREs -- but this string never seems to change,
+     *    so we can't distinguish them.
+     */
+    if (conf_get_int(ssh->conf, CONF_sshbug_ignore1) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_ignore1) == AUTO &&
         (!strcmp(imp, "1.2.18") || !strcmp(imp, "1.2.19") ||
          !strcmp(imp, "1.2.20") || !strcmp(imp, "1.2.21") ||
          !strcmp(imp, "1.2.22") || !strcmp(imp, "Cisco-1.25") ||
@@ -2171,8 +2700,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH-1 ignore bug");
     }
 
-    if (ssh->cfg.sshbug_plainpw1 == FORCE_ON ||
-       (ssh->cfg.sshbug_plainpw1 == AUTO &&
+    if (conf_get_int(ssh->conf, CONF_sshbug_plainpw1) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_plainpw1) == AUTO &&
         (!strcmp(imp, "Cisco-1.25") || !strcmp(imp, "OSU_1.4alpha3")))) {
        /*
         * These versions need a plain password sent; they can't
@@ -2183,8 +2712,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version needs a plain SSH-1 password");
     }
 
-    if (ssh->cfg.sshbug_rsa1 == FORCE_ON ||
-       (ssh->cfg.sshbug_rsa1 == AUTO &&
+    if (conf_get_int(ssh->conf, CONF_sshbug_rsa1) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_rsa1) == AUTO &&
         (!strcmp(imp, "Cisco-1.25")))) {
        /*
         * These versions apparently have no clue whatever about
@@ -2195,8 +2724,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version can't handle SSH-1 RSA authentication");
     }
 
-    if (ssh->cfg.sshbug_hmac2 == FORCE_ON ||
-       (ssh->cfg.sshbug_hmac2 == AUTO &&
+    if (conf_get_int(ssh->conf, CONF_sshbug_hmac2) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_hmac2) == AUTO &&
         !wc_match("* VShell", imp) &&
         (wc_match("2.1.0*", imp) || wc_match("2.0.*", imp) ||
          wc_match("2.2.0*", imp) || wc_match("2.3.0*", imp) ||
@@ -2208,8 +2737,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH-2 HMAC bug");
     }
 
-    if (ssh->cfg.sshbug_derivekey2 == FORCE_ON ||
-       (ssh->cfg.sshbug_derivekey2 == AUTO &&
+    if (conf_get_int(ssh->conf, CONF_sshbug_derivekey2) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_derivekey2) == AUTO &&
         !wc_match("* VShell", imp) &&
         (wc_match("2.0.0*", imp) || wc_match("2.0.10*", imp) ))) {
        /*
@@ -2221,10 +2750,12 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH-2 key-derivation bug");
     }
 
-    if (ssh->cfg.sshbug_rsapad2 == FORCE_ON ||
-       (ssh->cfg.sshbug_rsapad2 == AUTO &&
+    if (conf_get_int(ssh->conf, CONF_sshbug_rsapad2) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_rsapad2) == AUTO &&
         (wc_match("OpenSSH_2.[5-9]*", imp) ||
-         wc_match("OpenSSH_3.[0-2]*", imp)))) {
+         wc_match("OpenSSH_3.[0-2]*", imp) ||
+         wc_match("mod_sftp/0.[0-8]*", imp) ||
+         wc_match("mod_sftp/0.9.[0-8]", imp)))) {
        /*
         * These versions have the SSH-2 RSA padding bug.
         */
@@ -2232,8 +2763,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH-2 RSA padding bug");
     }
 
-    if (ssh->cfg.sshbug_pksessid2 == FORCE_ON ||
-       (ssh->cfg.sshbug_pksessid2 == AUTO &&
+    if (conf_get_int(ssh->conf, CONF_sshbug_pksessid2) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_pksessid2) == AUTO &&
         wc_match("OpenSSH_2.[0-2]*", imp))) {
        /*
         * These versions have the SSH-2 session-ID bug in
@@ -2243,19 +2774,78 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH-2 public-key-session-ID bug");
     }
 
-    if (ssh->cfg.sshbug_rekey2 == FORCE_ON ||
-       (ssh->cfg.sshbug_rekey2 == AUTO &&
+    if (conf_get_int(ssh->conf, CONF_sshbug_rekey2) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_rekey2) == AUTO &&
         (wc_match("DigiSSH_2.0", imp) ||
          wc_match("OpenSSH_2.[0-4]*", imp) ||
          wc_match("OpenSSH_2.5.[0-3]*", imp) ||
          wc_match("Sun_SSH_1.0", imp) ||
-         wc_match("Sun_SSH_1.0.1", imp)))) {
+         wc_match("Sun_SSH_1.0.1", imp) ||
+         /* All versions <= 1.2.6 (they changed their format in 1.2.7) */
+         wc_match("WeOnlyDo-*", imp)))) {
        /*
         * These versions have the SSH-2 rekey bug.
         */
        ssh->remote_bugs |= BUG_SSH2_REKEY;
        logevent("We believe remote version has SSH-2 rekey bug");
     }
+
+    if (conf_get_int(ssh->conf, CONF_sshbug_maxpkt2) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_maxpkt2) == AUTO &&
+        (wc_match("1.36_sshlib GlobalSCAPE", imp) ||
+          wc_match("1.36 sshlib: GlobalScape", imp)))) {
+       /*
+        * This version ignores our makpkt and needs to be throttled.
+        */
+       ssh->remote_bugs |= BUG_SSH2_MAXPKT;
+       logevent("We believe remote version ignores SSH-2 maximum packet size");
+    }
+
+    if (conf_get_int(ssh->conf, CONF_sshbug_ignore2) == FORCE_ON) {
+       /*
+        * Servers that don't support SSH2_MSG_IGNORE. Currently,
+        * none detected automatically.
+        */
+       ssh->remote_bugs |= BUG_CHOKES_ON_SSH2_IGNORE;
+       logevent("We believe remote version has SSH-2 ignore bug");
+    }
+
+    if (conf_get_int(ssh->conf, CONF_sshbug_oldgex2) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_oldgex2) == AUTO &&
+        (wc_match("OpenSSH_2.[235]*", imp)))) {
+       /*
+        * These versions only support the original (pre-RFC4419)
+        * SSH-2 GEX request.
+        */
+       ssh->remote_bugs |= BUG_SSH2_OLDGEX;
+       logevent("We believe remote version has outdated SSH-2 GEX");
+    }
+
+    if (conf_get_int(ssh->conf, CONF_sshbug_winadj) == FORCE_ON) {
+       /*
+        * Servers that don't support our winadj request for one
+        * reason or another. Currently, none detected automatically.
+        */
+       ssh->remote_bugs |= BUG_CHOKES_ON_WINADJ;
+       logevent("We believe remote version has winadj bug");
+    }
+
+    if (conf_get_int(ssh->conf, CONF_sshbug_chanreq) == FORCE_ON ||
+       (conf_get_int(ssh->conf, CONF_sshbug_chanreq) == AUTO &&
+        (wc_match("OpenSSH_[2-5].*", imp) ||
+         wc_match("OpenSSH_6.[0-6]*", imp) ||
+         wc_match("dropbear_0.[2-4][0-9]*", imp) ||
+         wc_match("dropbear_0.5[01]*", imp)))) {
+       /*
+        * These versions have the SSH-2 channel request bug.
+        * OpenSSH 6.7 and above do not:
+        * https://bugzilla.mindrot.org/show_bug.cgi?id=1818
+        * dropbear_0.52 and above do not:
+        * https://secure.ucc.asn.au/hg/dropbear/rev/cd02449b709c
+        */
+       ssh->remote_bugs |= BUG_SENDS_LATE_REQUEST_REPLY;
+       logevent("We believe remote version has SSH-2 channel request bug");
+    }
 }
 
 /*
@@ -2264,11 +2854,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
  */
 static void ssh_fix_verstring(char *str)
 {
-    /* Eat "SSH-<protoversion>-". */
-    assert(*str == 'S'); str++;
-    assert(*str == 'S'); str++;
-    assert(*str == 'H'); str++;
-    assert(*str == '-'); str++;
+    /* Eat "<protoversion>-". */
     while (*str && *str != '-') str++;
     assert(*str == '-'); str++;
 
@@ -2281,9 +2867,54 @@ static void ssh_fix_verstring(char *str)
     }
 }
 
+/*
+ * Send an appropriate SSH version string.
+ */
+static void ssh_send_verstring(Ssh ssh, const char *protoname, char *svers)
+{
+    char *verstring;
+
+    if (ssh->version == 2) {
+       /*
+        * Construct a v2 version string.
+        */
+       verstring = dupprintf("%s2.0-%s\015\012", protoname, sshver);
+    } else {
+       /*
+        * Construct a v1 version string.
+        */
+        assert(!strcmp(protoname, "SSH-")); /* no v1 bare connection protocol */
+       verstring = dupprintf("SSH-%s-%s\012",
+                             (ssh_versioncmp(svers, "1.5") <= 0 ?
+                              svers : "1.5"),
+                             sshver);
+    }
+
+    ssh_fix_verstring(verstring + strlen(protoname));
+
+    if (ssh->version == 2) {
+       size_t len;
+       /*
+        * Record our version string.
+        */
+       len = strcspn(verstring, "\015\012");
+       ssh->v_c = snewn(len + 1, char);
+       memcpy(ssh->v_c, verstring, len);
+       ssh->v_c[len] = 0;
+    }
+
+    logeventf(ssh, "We claim version: %.*s",
+             strcspn(verstring, "\015\012"), verstring);
+    s_write(ssh, verstring, strlen(verstring));
+    sfree(verstring);
+}
+
 static int do_ssh_init(Ssh ssh, unsigned char c)
 {
+    static const char protoname[] = "SSH-";
+
     struct do_ssh_init_state {
+       int crLine;
        int vslen;
        char version[10];
        char *vstring;
@@ -2292,35 +2923,29 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
        int proto1, proto2;
     };
     crState(do_ssh_init_state);
-
-    crBegin(ssh->do_ssh_init_crstate);
-
-    /* Search for the string "SSH-" in the input. */
-    s->i = 0;
-    while (1) {
-       static const int transS[] = { 1, 2, 2, 1 };
-       static const int transH[] = { 0, 0, 3, 0 };
-       static const int transminus[] = { 0, 0, 0, -1 };
-       if (c == 'S')
-           s->i = transS[s->i];
-       else if (c == 'H')
-           s->i = transH[s->i];
-       else if (c == '-')
-           s->i = transminus[s->i];
-       else
-           s->i = 0;
-       if (s->i < 0)
-           break;
-       crReturn(1);                   /* get another character */
+    
+    crBeginState;
+
+    /* Search for a line beginning with the protocol name prefix in
+     * the input. */
+    for (;;) {
+        for (s->i = 0; protoname[s->i]; s->i++) {
+            if ((char)c != protoname[s->i]) goto no;
+            crReturn(1);
+        }
+       break;
+      no:
+       while (c != '\012')
+           crReturn(1);
+       crReturn(1);
     }
 
-    s->vstrsize = 16;
+    s->vstrsize = sizeof(protoname) + 16;
     s->vstring = snewn(s->vstrsize, char);
-    strcpy(s->vstring, "SSH-");
-    s->vslen = 4;
+    strcpy(s->vstring, protoname);
+    s->vslen = strlen(protoname);
     s->i = 0;
     while (1) {
-       crReturn(1);                   /* get another char */
        if (s->vslen >= s->vstrsize - 1) {
            s->vstrsize += 16;
            s->vstring = sresize(s->vstring, s->vstrsize, char);
@@ -2334,6 +2959,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
                s->version[s->i++] = c;
        } else if (c == '\012')
            break;
+       crReturn(1);                   /* get another char */
     }
 
     ssh->agentfwd_enabled = FALSE;
@@ -2353,74 +2979,169 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     /* Anything greater or equal to "1.99" means protocol 2 is supported. */
     s->proto2 = ssh_versioncmp(s->version, "1.99") >= 0;
 
-    if (ssh->cfg.sshprot == 0 && !s->proto1) {
-       bombout(("SSH protocol version 1 required by user but not provided by server"));
+    if (conf_get_int(ssh->conf, CONF_sshprot) == 0 && !s->proto1) {
+       bombout(("SSH protocol version 1 required by configuration but "
+                "not provided by server"));
        crStop(0);
     }
-    if (ssh->cfg.sshprot == 3 && !s->proto2) {
-       bombout(("SSH protocol version 2 required by user but not provided by server"));
+    if (conf_get_int(ssh->conf, CONF_sshprot) == 3 && !s->proto2) {
+       bombout(("SSH protocol version 2 required by configuration but "
+                "not provided by server"));
        crStop(0);
     }
 
-    {
-        char *verstring;
+    if (s->proto2 && (conf_get_int(ssh->conf, CONF_sshprot) >= 2 || !s->proto1))
+       ssh->version = 2;
+    else
+       ssh->version = 1;
 
-        if (s->proto2 && (ssh->cfg.sshprot >= 2 || !s->proto1)) {
-            /*
-             * Construct a v2 version string.
-             */
-            verstring = dupprintf("SSH-2.0-%s\015\012", sshver);
-            ssh->version = 2;
-        } else {
-            /*
-             * Construct a v1 version string.
-             */
-            verstring = dupprintf("SSH-%s-%s\012",
-                                  (ssh_versioncmp(s->version, "1.5") <= 0 ?
-                                   s->version : "1.5"),
-                                  sshver);
-            ssh->version = 1;
-        }
+    logeventf(ssh, "Using SSH protocol version %d", ssh->version);
 
-        ssh_fix_verstring(verstring);
+    /* Send the version string, if we haven't already */
+    if (conf_get_int(ssh->conf, CONF_sshprot) != 3)
+       ssh_send_verstring(ssh, protoname, s->version);
 
-        if (ssh->version == 2) {
-            /*
-             * Hash our version string and their version string.
-             */
-            SHA_Init(&ssh->exhashbase);
-            sha_string(&ssh->exhashbase, verstring,
-                       strcspn(verstring, "\015\012"));
-            sha_string(&ssh->exhashbase, s->vstring,
-                       strcspn(s->vstring, "\015\012"));
+    if (ssh->version == 2) {
+       size_t len;
+       /*
+        * Record their version string.
+        */
+       len = strcspn(s->vstring, "\015\012");
+       ssh->v_s = snewn(len + 1, char);
+       memcpy(ssh->v_s, s->vstring, len);
+       ssh->v_s[len] = 0;
+           
+       /*
+        * Initialise SSH-2 protocol.
+        */
+       ssh->protocol = ssh2_protocol;
+       ssh2_protocol_setup(ssh);
+       ssh->s_rdpkt = ssh2_rdpkt;
+    } else {
+       /*
+        * Initialise SSH-1 protocol.
+        */
+       ssh->protocol = ssh1_protocol;
+       ssh1_protocol_setup(ssh);
+       ssh->s_rdpkt = ssh1_rdpkt;
+    }
+    if (ssh->version == 2)
+       do_ssh2_transport(ssh, NULL, -1, NULL);
 
-            /*
-             * Initialise SSH-2 protocol.
-             */
-            ssh->protocol = ssh2_protocol;
-            ssh2_protocol_setup(ssh);
-            ssh->s_rdpkt = ssh2_rdpkt;
-        } else {
-            /*
-             * Initialise SSH-1 protocol.
-             */
-            ssh->protocol = ssh1_protocol;
-            ssh1_protocol_setup(ssh);
-            ssh->s_rdpkt = ssh1_rdpkt;
+    update_specials_menu(ssh->frontend);
+    ssh->state = SSH_STATE_BEFORE_SIZE;
+    ssh->pinger = pinger_new(ssh->conf, &ssh_backend, ssh);
+
+    sfree(s->vstring);
+
+    crFinish(0);
+}
+
+static int do_ssh_connection_init(Ssh ssh, unsigned char c)
+{
+    /*
+     * Ordinary SSH begins with the banner "SSH-x.y-...". This is just
+     * the ssh-connection part, extracted and given a trivial binary
+     * packet protocol, so we replace 'SSH-' at the start with a new
+     * name. In proper SSH style (though of course this part of the
+     * proper SSH protocol _isn't_ subject to this kind of
+     * DNS-domain-based extension), we define the new name in our
+     * extension space.
+     */
+    static const char protoname[] =
+        "SSHCONNECTION@putty.projects.tartarus.org-";
+
+    struct do_ssh_connection_init_state {
+       int crLine;
+       int vslen;
+       char version[10];
+       char *vstring;
+       int vstrsize;
+       int i;
+    };
+    crState(do_ssh_connection_init_state);
+    
+    crBeginState;
+
+    /* Search for a line beginning with the protocol name prefix in
+     * the input. */
+    for (;;) {
+        for (s->i = 0; protoname[s->i]; s->i++) {
+            if ((char)c != protoname[s->i]) goto no;
+            crReturn(1);
         }
-        logeventf(ssh, "We claim version: %.*s",
-                  strcspn(verstring, "\015\012"), verstring);
-       sk_write(ssh->s, verstring, strlen(verstring));
-        sfree(verstring);
-       if (ssh->version == 2)
-           do_ssh2_transport(ssh, NULL, -1, NULL);
+       break;
+      no:
+       while (c != '\012')
+           crReturn(1);
+       crReturn(1);
     }
 
-    logeventf(ssh, "Using SSH protocol version %d", ssh->version);
+    s->vstrsize = sizeof(protoname) + 16;
+    s->vstring = snewn(s->vstrsize, char);
+    strcpy(s->vstring, protoname);
+    s->vslen = strlen(protoname);
+    s->i = 0;
+    while (1) {
+       if (s->vslen >= s->vstrsize - 1) {
+           s->vstrsize += 16;
+           s->vstring = sresize(s->vstring, s->vstrsize, char);
+       }
+       s->vstring[s->vslen++] = c;
+       if (s->i >= 0) {
+           if (c == '-') {
+               s->version[s->i] = '\0';
+               s->i = -1;
+           } else if (s->i < sizeof(s->version) - 1)
+               s->version[s->i++] = c;
+       } else if (c == '\012')
+           break;
+       crReturn(1);                   /* get another char */
+    }
+
+    ssh->agentfwd_enabled = FALSE;
+    ssh->rdpkt2_bare_state.incoming_sequence = 0;
+
+    s->vstring[s->vslen] = 0;
+    s->vstring[strcspn(s->vstring, "\015\012")] = '\0';/* remove EOL chars */
+    logeventf(ssh, "Server version: %s", s->vstring);
+    ssh_detect_bugs(ssh, s->vstring);
+
+    /*
+     * Decide which SSH protocol version to support. This is easy in
+     * bare ssh-connection mode: only 2.0 is legal.
+     */
+    if (ssh_versioncmp(s->version, "2.0") < 0) {
+       bombout(("Server announces compatibility with SSH-1 in bare ssh-connection protocol"));
+        crStop(0);
+    }
+    if (conf_get_int(ssh->conf, CONF_sshprot) == 0) {
+       bombout(("Bare ssh-connection protocol cannot be run in SSH-1-only mode"));
+       crStop(0);
+    }
+
+    ssh->version = 2;
+
+    logeventf(ssh, "Using bare ssh-connection protocol");
+
+    /* Send the version string, if we haven't already */
+    ssh_send_verstring(ssh, protoname, s->version);
+
+    /*
+     * Initialise bare connection protocol.
+     */
+    ssh->protocol = ssh2_bare_connection_protocol;
+    ssh2_bare_connection_protocol_setup(ssh);
+    ssh->s_rdpkt = ssh2_bare_connection_rdpkt;
 
     update_specials_menu(ssh->frontend);
     ssh->state = SSH_STATE_BEFORE_SIZE;
-    ssh->pinger = pinger_new(&ssh->cfg, &ssh_backend, ssh);
+    ssh->pinger = pinger_new(ssh->conf, &ssh_backend, ssh);
+
+    /*
+     * Get authconn (really just conn) under way.
+     */
+    do_ssh2_authconn(ssh, NULL, 0, NULL);
 
     sfree(s->vstring);
 
@@ -2430,7 +3151,9 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
 static void ssh_process_incoming_data(Ssh ssh,
                                      unsigned char **data, int *datalen)
 {
-    struct Packet *pktin = ssh->s_rdpkt(ssh, data, datalen);
+    struct Packet *pktin;
+
+    pktin = ssh->s_rdpkt(ssh, data, datalen);
     if (pktin) {
        ssh->protocol(ssh, NULL, 0, pktin);
        ssh_free_packet(pktin);
@@ -2473,6 +3196,11 @@ static void ssh_set_frozen(Ssh ssh, int frozen)
 
 static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
 {
+    /* Log raw data, if we're in that mode. */
+    if (ssh->logctx)
+       log_packet(ssh->logctx, PKT_INCOMING, -1, NULL, data, datalen,
+                  0, NULL, NULL, 0, NULL);
+
     crBegin(ssh->ssh_gotdata_crstate);
 
     /*
@@ -2485,7 +3213,7 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
        int ret;                       /* need not be kept across crReturn */
        if (datalen == 0)
            crReturnV;                 /* more data please */
-       ret = do_ssh_init(ssh, *data);
+       ret = ssh->do_ssh_init(ssh, *data);
        data++;
        datalen--;
        if (ret == 0)
@@ -2498,24 +3226,29 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
      * everything to s_rdpkt, and then pass the resulting packets
      * to the proper protocol handler.
      */
-    if (datalen == 0)
-       crReturnV;
-
-    /*
-     * Process queued data if there is any.
-     */
-    ssh_process_queued_incoming_data(ssh);
 
     while (1) {
-       while (datalen > 0) {
-           if (ssh->frozen)
+       while (bufchain_size(&ssh->queued_incoming_data) > 0 || datalen > 0) {
+           if (ssh->frozen) {
                ssh_queue_incoming_data(ssh, &data, &datalen);
-
-           ssh_process_incoming_data(ssh, &data, &datalen);
-
+               /* This uses up all data and cannot cause anything interesting
+                * to happen; indeed, for anything to happen at all, we must
+                * return, so break out. */
+               break;
+           } else if (bufchain_size(&ssh->queued_incoming_data) > 0) {
+               /* This uses up some or all data, and may freeze the
+                * session. */
+               ssh_process_queued_incoming_data(ssh);
+           } else {
+               /* This uses up some or all data, and may freeze the
+                * session. */
+               ssh_process_incoming_data(ssh, &data, &datalen);
+           }
+           /* FIXME this is probably EBW. */
            if (ssh->state == SSH_STATE_CLOSED)
                return;
        }
+       /* We're out of data. Go and get some more. */
        crReturnV;
     }
     crFinishV;
@@ -2544,10 +3277,11 @@ static int ssh_do_close(Ssh ssh, int notify_exit)
        while (NULL != (c = index234(ssh->channels, 0))) {
            switch (c->type) {
              case CHAN_X11:
-               x11_close(c->u.x11.s);
+               x11_close(c->u.x11.xconn);
                break;
              case CHAN_SOCKDATA:
-               pfd_close(c->u.pfd.s);
+             case CHAN_SOCKDATA_DORMANT:
+               pfd_close(c->u.pfd.pf);
                break;
            }
            del234(ssh->channels, c); /* moving next one to index 0 */
@@ -2565,34 +3299,94 @@ static int ssh_do_close(Ssh ssh, int notify_exit)
        while (NULL != (pf = index234(ssh->portfwds, 0))) {
            /* Dispose of any listening socket. */
            if (pf->local)
-               pfd_terminate(pf->local);
+               pfl_terminate(pf->local);
            del234(ssh->portfwds, pf); /* moving next one to index 0 */
            free_portfwd(pf);
        }
+       freetree234(ssh->portfwds);
+       ssh->portfwds = NULL;
+    }
+
+    /*
+     * Also stop attempting to connection-share.
+     */
+    if (ssh->connshare) {
+        sharestate_free(ssh->connshare);
+        ssh->connshare = NULL;
     }
 
     return ret;
 }
 
-static void ssh_log(Plug plug, int type, SockAddr addr, int port,
-                   const char *error_msg, int error_code)
+static void ssh_socket_log(Plug plug, int type, SockAddr addr, int port,
+                           const char *error_msg, int error_code)
 {
     Ssh ssh = (Ssh) plug;
     char addrbuf[256], *msg;
 
-    sk_getaddr(addr, addrbuf, lenof(addrbuf));
+    if (ssh->attempting_connshare) {
+        /*
+         * While we're attempting connection sharing, don't loudly log
+         * everything that happens. Real TCP connections need to be
+         * logged when we _start_ trying to connect, because it might
+         * be ages before they respond if something goes wrong; but
+         * connection sharing is local and quick to respond, and it's
+         * sufficient to simply wait and see whether it worked
+         * afterwards.
+         */
+    } else {
+        sk_getaddr(addr, addrbuf, lenof(addrbuf));
 
-    if (type == 0)
-       msg = dupprintf("Connecting to %s port %d", addrbuf, port);
-    else
-       msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
+        if (type == 0) {
+            if (sk_addr_needs_port(addr)) {
+                msg = dupprintf("Connecting to %s port %d", addrbuf, port);
+            } else {
+                msg = dupprintf("Connecting to %s", addrbuf);
+            }
+        } else {
+            msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
+        }
 
-    logevent(msg);
-    sfree(msg);
+        logevent(msg);
+        sfree(msg);
+    }
 }
 
-static int ssh_closing(Plug plug, const char *error_msg, int error_code,
-                      int calling_back)
+void ssh_connshare_log(Ssh ssh, int event, const char *logtext,
+                       const char *ds_err, const char *us_err)
+{
+    if (event == SHARE_NONE) {
+        /* In this case, 'logtext' is an error message indicating a
+         * reason why connection sharing couldn't be set up _at all_.
+         * Failing that, ds_err and us_err indicate why we couldn't be
+         * a downstream and an upstream respectively. */
+        if (logtext) {
+            logeventf(ssh, "Could not set up connection sharing: %s", logtext);
+        } else {
+            if (ds_err)
+                logeventf(ssh, "Could not set up connection sharing"
+                          " as downstream: %s", ds_err);
+            if (us_err)
+                logeventf(ssh, "Could not set up connection sharing"
+                          " as upstream: %s", us_err);
+        }
+    } else if (event == SHARE_DOWNSTREAM) {
+        /* In this case, 'logtext' is a local endpoint address */
+        logeventf(ssh, "Using existing shared connection at %s", logtext);
+        /* Also we should mention this in the console window to avoid
+         * confusing users as to why this window doesn't behave the
+         * usual way. */
+        if ((flags & FLAG_VERBOSE) || (flags & FLAG_INTERACTIVE)) {
+            c_write_str(ssh,"Reusing a shared connection to this server.\r\n");
+        }
+    } else if (event == SHARE_UPSTREAM) {
+        /* In this case, 'logtext' is a local endpoint address too */
+        logeventf(ssh, "Sharing this connection at %s", logtext);
+    }
+}
+
+static int ssh_closing(Plug plug, const char *error_msg, int error_code,
+                      int calling_back)
 {
     Ssh ssh = (Ssh) plug;
     int need_notify = ssh_do_close(ssh, FALSE);
@@ -2604,6 +3398,9 @@ static int ssh_closing(Plug plug, const char *error_msg, int error_code,
            error_msg = "Server closed network connection";
     }
 
+    if (ssh->close_expected && ssh->clean_exit && ssh->exitcode < 0)
+       ssh->exitcode = 0;
+
     if (need_notify)
         notify_remote_exit(ssh->frontend);
 
@@ -2646,7 +3443,7 @@ static const char *connect_to_host(Ssh ssh, char *host, int port,
                                   char **realhost, int nodelay, int keepalive)
 {
     static const struct plug_function_table fn_table = {
-       ssh_log,
+       ssh_socket_log,
        ssh_closing,
        ssh_receive,
        ssh_sent,
@@ -2655,37 +3452,110 @@ static const char *connect_to_host(Ssh ssh, char *host, int port,
 
     SockAddr addr;
     const char *err;
+    char *loghost;
+    int addressfamily, sshprot;
+    
+    loghost = conf_get_str(ssh->conf, CONF_loghost);
+    if (*loghost) {
+       char *tmphost;
+        char *colon;
+
+        tmphost = dupstr(loghost);
+       ssh->savedport = 22;           /* default ssh port */
+
+       /*
+        * A colon suffix on the hostname string also lets us affect
+        * savedport. (Unless there are multiple colons, in which case
+        * we assume this is an unbracketed IPv6 literal.)
+        */
+       colon = host_strrchr(tmphost, ':');
+       if (colon && colon == host_strchr(tmphost, ':')) {
+           *colon++ = '\0';
+           if (*colon)
+               ssh->savedport = atoi(colon);
+       }
 
-    ssh->savedhost = snewn(1 + strlen(host), char);
-    strcpy(ssh->savedhost, host);
+        ssh->savedhost = host_strduptrim(tmphost);
+        sfree(tmphost);
+    } else {
+       ssh->savedhost = host_strduptrim(host);
+       if (port < 0)
+           port = 22;                 /* default ssh port */
+       ssh->savedport = port;
+    }
+
+    ssh->fn = &fn_table;               /* make 'ssh' usable as a Plug */
+
+    /*
+     * Try connection-sharing, in case that means we don't open a
+     * socket after all. ssh_connection_sharing_init will connect to a
+     * previously established upstream if it can, and failing that,
+     * establish a listening socket for _us_ to be the upstream. In
+     * the latter case it will return NULL just as if it had done
+     * nothing, because here we only need to care if we're a
+     * downstream and need to do our connection setup differently.
+     */
+    ssh->connshare = NULL;
+    ssh->attempting_connshare = TRUE;  /* affects socket logging behaviour */
+    ssh->s = ssh_connection_sharing_init(ssh->savedhost, ssh->savedport,
+                                         ssh->conf, ssh, &ssh->connshare);
+    ssh->attempting_connshare = FALSE;
+    if (ssh->s != NULL) {
+        /*
+         * We are a downstream.
+         */
+        ssh->bare_connection = TRUE;
+        ssh->do_ssh_init = do_ssh_connection_init;
+        ssh->fullhostname = NULL;
+        *realhost = dupstr(host);      /* best we can do */
+    } else {
+        /*
+         * We're not a downstream, so open a normal socket.
+         */
+        ssh->do_ssh_init = do_ssh_init;
+
+        /*
+         * Try to find host.
+         */
+        addressfamily = conf_get_int(ssh->conf, CONF_addressfamily);
+        logeventf(ssh, "Looking up host \"%s\"%s", host,
+                  (addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
+                   (addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" : "")));
+        addr = name_lookup(host, port, realhost, ssh->conf, addressfamily);
+        if ((err = sk_addr_error(addr)) != NULL) {
+            sk_addr_free(addr);
+            return err;
+        }
+        ssh->fullhostname = dupstr(*realhost);   /* save in case of GSSAPI */
 
-    if (port < 0)
-       port = 22;                     /* default ssh port */
-    ssh->savedport = port;
+        ssh->s = new_connection(addr, *realhost, port,
+                                0, 1, nodelay, keepalive,
+                                (Plug) ssh, ssh->conf);
+        if ((err = sk_socket_error(ssh->s)) != NULL) {
+            ssh->s = NULL;
+            notify_remote_exit(ssh->frontend);
+            return err;
+        }
+    }
 
     /*
-     * Try to find host.
+     * If the SSH version number's fixed, set it now, and if it's SSH-2,
+     * send the version string too.
      */
-    logeventf(ssh, "Looking up host \"%s\"%s", host,
-             (ssh->cfg.addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
-              (ssh->cfg.addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" : "")));
-    addr = name_lookup(host, port, realhost, &ssh->cfg,
-                      ssh->cfg.addressfamily);
-    if ((err = sk_addr_error(addr)) != NULL) {
-       sk_addr_free(addr);
-       return err;
+    sshprot = conf_get_int(ssh->conf, CONF_sshprot);
+    if (sshprot == 0)
+       ssh->version = 1;
+    if (sshprot == 3 && !ssh->bare_connection) {
+       ssh->version = 2;
+       ssh_send_verstring(ssh, "SSH-", NULL);
     }
 
     /*
-     * Open socket.
+     * loghost, if configured, overrides realhost.
      */
-    ssh->fn = &fn_table;
-    ssh->s = new_connection(addr, *realhost, port,
-                           0, 1, nodelay, keepalive, (Plug) ssh, &ssh->cfg);
-    if ((err = sk_socket_error(ssh->s)) != NULL) {
-       ssh->s = NULL;
-       notify_remote_exit(ssh->frontend);
-       return err;
+    if (*loghost) {
+       sfree(*realhost);
+       *realhost = dupstr(loghost);
     }
 
     return NULL;
@@ -2694,14 +3564,14 @@ static const char *connect_to_host(Ssh ssh, char *host, int port,
 /*
  * Throttle or unthrottle the SSH connection.
  */
-static void ssh1_throttle(Ssh ssh, int adjust)
+static void ssh_throttle_conn(Ssh ssh, int adjust)
 {
-    int old_count = ssh->v1_throttle_count;
-    ssh->v1_throttle_count += adjust;
-    assert(ssh->v1_throttle_count >= 0);
-    if (ssh->v1_throttle_count && !old_count) {
+    int old_count = ssh->conn_throttle_count;
+    ssh->conn_throttle_count += adjust;
+    assert(ssh->conn_throttle_count >= 0);
+    if (ssh->conn_throttle_count && !old_count) {
        ssh_set_frozen(ssh, 1);
-    } else if (!ssh->v1_throttle_count && old_count) {
+    } else if (!ssh->conn_throttle_count && old_count) {
        ssh_set_frozen(ssh, 0);
     }
 }
@@ -2729,88 +3599,16 @@ static void ssh_throttle_all(Ssh ssh, int enable, int bufsize)
             */
            break;
          case CHAN_X11:
-           x11_override_throttle(c->u.x11.s, enable);
+           x11_override_throttle(c->u.x11.xconn, enable);
            break;
          case CHAN_AGENT:
            /* Agent channels require no buffer management. */
            break;
          case CHAN_SOCKDATA:
-           pfd_override_throttle(c->u.pfd.s, enable);
-           break;
-       }
-    }
-}
-
-/*
- * Username and password input, abstracted off into routines
- * reusable in several places - even between SSH-1 and SSH-2.
- */
-
-/* Set up a username or password input loop on a given buffer. */
-static void setup_userpass_input(Ssh ssh, char *buffer, int buflen, int echo)
-{
-    ssh->userpass_input_buffer = buffer;
-    ssh->userpass_input_buflen = buflen;
-    ssh->userpass_input_bufpos = 0;
-    ssh->userpass_input_echo = echo;
-}
-
-/*
- * Process some terminal data in the course of username/password
- * input. Returns >0 for success (line of input returned in
- * buffer), <0 for failure (user hit ^C/^D, bomb out and exit), 0
- * for inconclusive (keep waiting for more input please).
- */
-static int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
-{
-    char c;
-
-    while (inlen--) {
-       switch (c = *in++) {
-         case 10:
-         case 13:
-           ssh->userpass_input_buffer[ssh->userpass_input_bufpos] = 0;
-           ssh->userpass_input_buffer[ssh->userpass_input_buflen-1] = 0;
-           return +1;
-           break;
-         case 8:
-         case 127:
-           if (ssh->userpass_input_bufpos > 0) {
-               if (ssh->userpass_input_echo)
-                   c_write_str(ssh, "\b \b");
-               ssh->userpass_input_bufpos--;
-           }
-           break;
-         case 21:
-         case 27:
-           while (ssh->userpass_input_bufpos > 0) {
-               if (ssh->userpass_input_echo)
-                   c_write_str(ssh, "\b \b");
-               ssh->userpass_input_bufpos--;
-           }
-           break;
-         case 3:
-         case 4:
-           return -1;
-           break;
-         default:
-           /*
-            * This simplistic check for printability is disabled
-            * when we're doing password input, because some people
-            * have control characters in their passwords.o
-            */
-           if ((!ssh->userpass_input_echo ||
-                (c >= ' ' && c <= '~') ||
-                ((unsigned char) c >= 160))
-               && ssh->userpass_input_bufpos < ssh->userpass_input_buflen-1) {
-               ssh->userpass_input_buffer[ssh->userpass_input_bufpos++] = c;
-               if (ssh->userpass_input_echo)
-                   c_write(ssh, &c, 1);
-           }
+           pfd_override_throttle(c->u.pfd.pf, enable);
            break;
        }
     }
-    return 0;
 }
 
 static void ssh_agent_callback(void *sshv, void *reply, int replylen)
@@ -2850,6 +3648,7 @@ static void ssh_agentf_callback(void *cv, void *reply, int replylen)
     Ssh ssh = c->ssh;
     void *sentreply = reply;
 
+    c->u.a.outstanding_requests--;
     if (!sentreply) {
        /* Fake SSH_AGENT_FAILURE. */
        sentreply = "\0\0\0\1\5";
@@ -2861,14 +3660,18 @@ static void ssh_agentf_callback(void *cv, void *reply, int replylen)
     } else {
        send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
                    PKT_INT, c->remoteid,
-                   PKTT_DATA,
                    PKT_INT, replylen,
                    PKT_DATA, sentreply, replylen,
-                   PKTT_OTHER,
                    PKT_END);
     }
     if (reply)
        sfree(reply);
+    /*
+     * If we've already seen an incoming EOF but haven't sent an
+     * outgoing one, this may be the moment to send it.
+     */
+    if (c->u.a.outstanding_requests == 0 && (c->closes & CLOSES_RCVD_EOF))
+        sshfwd_write_eof(c);
 }
 
 /*
@@ -2904,6 +3707,59 @@ static void ssh_disconnect(Ssh ssh, char *client_reason, char *wire_reason,
     sfree(error);
 }
 
+int verify_ssh_manual_host_key(Ssh ssh, const char *fingerprint,
+                               const struct ssh_signkey *ssh2keytype,
+                               void *ssh2keydata)
+{
+    if (!conf_get_str_nthstrkey(ssh->conf, CONF_ssh_manual_hostkeys, 0)) {
+        return -1;                     /* no manual keys configured */
+    }
+
+    if (fingerprint) {
+        /*
+         * The fingerprint string we've been given will have things
+         * like 'ssh-rsa 2048' at the front of it. Strip those off and
+         * narrow down to just the colon-separated hex block at the
+         * end of the string.
+         */
+        const char *p = strrchr(fingerprint, ' ');
+        fingerprint = p ? p+1 : fingerprint;
+        /* Quick sanity checks, including making sure it's in lowercase */
+        assert(strlen(fingerprint) == 16*3 - 1);
+        assert(fingerprint[2] == ':');
+        assert(fingerprint[strspn(fingerprint, "0123456789abcdef:")] == 0);
+
+        if (conf_get_str_str_opt(ssh->conf, CONF_ssh_manual_hostkeys,
+                                 fingerprint))
+            return 1;                  /* success */
+    }
+
+    if (ssh2keydata) {
+        /*
+         * Construct the base64-encoded public key blob and see if
+         * that's listed.
+         */
+        unsigned char *binblob;
+        char *base64blob;
+        int binlen, atoms, i;
+        binblob = ssh2keytype->public_blob(ssh2keydata, &binlen);
+        atoms = (binlen + 2) / 3;
+        base64blob = snewn(atoms * 4 + 1, char);
+        for (i = 0; i < atoms; i++)
+            base64_encode_atom(binblob + 3*i, binlen - 3*i, base64blob + 4*i);
+        base64blob[atoms * 4] = '\0';
+        sfree(binblob);
+        if (conf_get_str_str_opt(ssh->conf, CONF_ssh_manual_hostkeys,
+                                 base64blob)) {
+            sfree(base64blob);
+            return 1;                  /* success */
+        }
+        sfree(base64blob);
+    }
+
+    return 0;
+}
+
 /*
  * Handle the key exchange and user authentication phases.
  */
@@ -2912,9 +3768,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 {
     int i, j, ret;
     unsigned char cookie[8], *ptr;
-    struct RSAKey servkey, hostkey;
     struct MD5Context md5c;
     struct do_ssh1_login_state {
+       int crLine;
        int len;
        unsigned char *rsabuf, *keystr1, *keystr2;
        unsigned long supported_ciphers_mask, supported_auths_mask;
@@ -2922,12 +3778,11 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        int tis_auth_refused, ccard_auth_refused;
        unsigned char session_id[16];
        int cipher_type;
-       char username[100];
        void *publickey_blob;
        int publickey_bloblen;
-       char password[100];
-       char prompt[200];
-       int pos;
+       char *publickey_comment;
+       int publickey_encrypted;
+       prompts_t *cur_prompt;
        char c;
        int pwpkt_type;
        unsigned char request[5], *response, *p;
@@ -2939,10 +3794,12 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        char *commentp;
        int commentlen;
         int dlgret;
+       Filename *keyfile;
+        struct RSAKey servkey, hostkey;
     };
     crState(do_ssh1_login_state);
 
-    crBegin(ssh->do_ssh1_login_crstate);
+    crBeginState;
 
     if (!pktin)
        crWaitUntil(pktin);
@@ -2961,8 +3818,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
     }
     memcpy(cookie, ptr, 8);
 
-    if (!ssh1_pkt_getrsakey(pktin, &servkey, &s->keystr1) ||
-       !ssh1_pkt_getrsakey(pktin, &hostkey, &s->keystr2)) {    
+    if (!ssh1_pkt_getrsakey(pktin, &s->servkey, &s->keystr1) ||
+       !ssh1_pkt_getrsakey(pktin, &s->hostkey, &s->keystr2)) { 
        bombout(("Failed to read SSH-1 public keys from public key packet"));
        crStop(0);
     }
@@ -2974,23 +3831,25 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        char logmsg[80];
        logevent("Host key fingerprint is:");
        strcpy(logmsg, "      ");
-       hostkey.comment = NULL;
+       s->hostkey.comment = NULL;
        rsa_fingerprint(logmsg + strlen(logmsg),
-                       sizeof(logmsg) - strlen(logmsg), &hostkey);
+                       sizeof(logmsg) - strlen(logmsg), &s->hostkey);
        logevent(logmsg);
     }
 
     ssh->v1_remote_protoflags = ssh_pkt_getuint32(pktin);
     s->supported_ciphers_mask = ssh_pkt_getuint32(pktin);
     s->supported_auths_mask = ssh_pkt_getuint32(pktin);
+    if ((ssh->remote_bugs & BUG_CHOKES_ON_RSA))
+       s->supported_auths_mask &= ~(1 << SSH1_AUTH_RSA);
 
     ssh->v1_local_protoflags =
        ssh->v1_remote_protoflags & SSH1_PROTOFLAGS_SUPPORTED;
     ssh->v1_local_protoflags |= SSH1_PROTOFLAG_SCREEN_NUMBER;
 
     MD5Init(&md5c);
-    MD5Update(&md5c, s->keystr2, hostkey.bytes);
-    MD5Update(&md5c, s->keystr1, servkey.bytes);
+    MD5Update(&md5c, s->keystr2, s->hostkey.bytes);
+    MD5Update(&md5c, s->keystr1, s->servkey.bytes);
     MD5Update(&md5c, cookie, 8);
     MD5Final(s->session_id, &md5c);
 
@@ -3000,13 +3859,14 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Verify that the `bits' and `bytes' parameters match.
      */
-    if (hostkey.bits > hostkey.bytes * 8 ||
-       servkey.bits > servkey.bytes * 8) {
+    if (s->hostkey.bits > s->hostkey.bytes * 8 ||
+       s->servkey.bits > s->servkey.bytes * 8) {
        bombout(("SSH-1 public keys were badly formatted"));
        crStop(0);
     }
 
-    s->len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
+    s->len = (s->hostkey.bytes > s->servkey.bytes ?
+              s->hostkey.bytes : s->servkey.bytes);
 
     s->rsabuf = snewn(s->len, unsigned char);
 
@@ -3017,35 +3877,45 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        /*
         * First format the key into a string.
         */
-       int len = rsastr_len(&hostkey);
+       int len = rsastr_len(&s->hostkey);
        char fingerprint[100];
        char *keystr = snewn(len, char);
-       rsastr_fmt(keystr, &hostkey);
-       rsa_fingerprint(fingerprint, sizeof(fingerprint), &hostkey);
-
-        ssh_set_frozen(ssh, 1);
-       s->dlgret = verify_ssh_host_key(ssh->frontend,
-                                        ssh->savedhost, ssh->savedport,
-                                        "rsa", keystr, fingerprint,
-                                        ssh_dialog_callback, ssh);
-       sfree(keystr);
-        if (s->dlgret < 0) {
-            do {
-                crReturn(0);
-                if (pktin) {
-                    bombout(("Unexpected data from server while waiting"
-                             " for user host key response"));
-                    crStop(0);
-                }
-            } while (pktin || inlen > 0);
-            s->dlgret = ssh->user_response;
-        }
-        ssh_set_frozen(ssh, 0);
+       rsastr_fmt(keystr, &s->hostkey);
+       rsa_fingerprint(fingerprint, sizeof(fingerprint), &s->hostkey);
+
+        /* First check against manually configured host keys. */
+        s->dlgret = verify_ssh_manual_host_key(ssh, fingerprint, NULL, NULL);
+        if (s->dlgret == 0) {          /* did not match */
+            bombout(("Host key did not appear in manually configured list"));
+            sfree(keystr);
+            crStop(0);
+        } else if (s->dlgret < 0) { /* none configured; use standard handling */
+            ssh_set_frozen(ssh, 1);
+            s->dlgret = verify_ssh_host_key(ssh->frontend,
+                                            ssh->savedhost, ssh->savedport,
+                                            "rsa", keystr, fingerprint,
+                                            ssh_dialog_callback, ssh);
+            sfree(keystr);
+            if (s->dlgret < 0) {
+                do {
+                    crReturn(0);
+                    if (pktin) {
+                        bombout(("Unexpected data from server while waiting"
+                                 " for user host key response"));
+                        crStop(0);
+                    }
+                } while (pktin || inlen > 0);
+                s->dlgret = ssh->user_response;
+            }
+            ssh_set_frozen(ssh, 0);
 
-        if (s->dlgret == 0) {
-           ssh_disconnect(ssh, "User aborted at host key verification",
-                          NULL, 0, TRUE);
-           crStop(0);
+            if (s->dlgret == 0) {
+                ssh_disconnect(ssh, "User aborted at host key verification",
+                               NULL, 0, TRUE);
+                crStop(0);
+            }
+        } else {
+            sfree(keystr);
         }
     }
 
@@ -3055,14 +3925,14 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
            s->rsabuf[i] ^= s->session_id[i];
     }
 
-    if (hostkey.bytes > servkey.bytes) {
-       ret = rsaencrypt(s->rsabuf, 32, &servkey);
+    if (s->hostkey.bytes > s->servkey.bytes) {
+       ret = rsaencrypt(s->rsabuf, 32, &s->servkey);
        if (ret)
-           ret = rsaencrypt(s->rsabuf, servkey.bytes, &hostkey);
+           ret = rsaencrypt(s->rsabuf, s->servkey.bytes, &s->hostkey);
     } else {
-       ret = rsaencrypt(s->rsabuf, 32, &hostkey);
+       ret = rsaencrypt(s->rsabuf, 32, &s->hostkey);
        if (ret)
-           ret = rsaencrypt(s->rsabuf, hostkey.bytes, &servkey);
+           ret = rsaencrypt(s->rsabuf, s->hostkey.bytes, &s->servkey);
     }
     if (!ret) {
        bombout(("SSH-1 public key encryptions failed due to bad formatting"));
@@ -3076,7 +3946,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        char *cipher_string = NULL;
        int i;
        for (i = 0; !cipher_chosen && i < CIPHER_MAX; i++) {
-           int next_cipher = ssh->cfg.ssh_cipherlist[i];
+           int next_cipher = conf_get_int_int(ssh->conf,
+                                              CONF_ssh_cipherlist, i);
            if (next_cipher == CIPHER_WARN) {
                /* If/when we choose a cipher, warn about it */
                warn = 1;
@@ -3164,21 +4035,21 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
     ssh->crcda_ctx = crcda_make_context();
     logevent("Installing CRC compensation attack detector");
 
-    if (servkey.modulus) {
-       sfree(servkey.modulus);
-       servkey.modulus = NULL;
+    if (s->servkey.modulus) {
+       sfree(s->servkey.modulus);
+       s->servkey.modulus = NULL;
     }
-    if (servkey.exponent) {
-       sfree(servkey.exponent);
-       servkey.exponent = NULL;
+    if (s->servkey.exponent) {
+       sfree(s->servkey.exponent);
+       s->servkey.exponent = NULL;
     }
-    if (hostkey.modulus) {
-       sfree(hostkey.modulus);
-       hostkey.modulus = NULL;
+    if (s->hostkey.modulus) {
+       sfree(s->hostkey.modulus);
+       s->hostkey.modulus = NULL;
     }
-    if (hostkey.exponent) {
-       sfree(hostkey.exponent);
-       hostkey.exponent = NULL;
+    if (s->hostkey.exponent) {
+       sfree(s->hostkey.exponent);
+       s->hostkey.exponent = NULL;
     }
     crWaitUntil(pktin);
 
@@ -3189,72 +4060,101 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 
     logevent("Successfully started encryption");
 
-    fflush(stdout);
+    fflush(stdout); /* FIXME eh? */
     {
-       if (!*ssh->cfg.username) {
-           if (ssh_get_line && !ssh_getline_pw_only) {
-               if (!ssh_get_line("login as: ",
-                                 s->username, sizeof(s->username), FALSE)) {
-                   /*
-                    * get_line failed to get a username.
-                    * Terminate.
-                    */
-                   ssh_disconnect(ssh, "No username provided", NULL, 0, TRUE);
-                   crStop(1);
-               }
-           } else {
-               int ret;               /* need not be kept over crReturn */
-               c_write_str(ssh, "login as: ");
+       if ((ssh->username = get_remote_username(ssh->conf)) == NULL) {
+           int ret; /* need not be kept over crReturn */
+           s->cur_prompt = new_prompts(ssh->frontend);
+           s->cur_prompt->to_server = TRUE;
+           s->cur_prompt->name = dupstr("SSH login name");
+           add_prompt(s->cur_prompt, dupstr("login as: "), TRUE);
+           ret = get_userpass_input(s->cur_prompt, NULL, 0);
+           while (ret < 0) {
                ssh->send_ok = 1;
-
-               setup_userpass_input(ssh, s->username, sizeof(s->username), 1);
-               do {
-                   crWaitUntil(!pktin);
-                   ret = process_userpass_input(ssh, in, inlen);
-               } while (ret == 0);
-               if (ret < 0)
-                   cleanup_exit(0);
-               c_write_str(ssh, "\r\n");
+               crWaitUntil(!pktin);
+               ret = get_userpass_input(s->cur_prompt, in, inlen);
+               ssh->send_ok = 0;
            }
-       } else {
-           strncpy(s->username, ssh->cfg.username, sizeof(s->username));
-           s->username[sizeof(s->username)-1] = '\0';
+           if (!ret) {
+               /*
+                * Failed to get a username. Terminate.
+                */
+               free_prompts(s->cur_prompt);
+               ssh_disconnect(ssh, "No username provided", NULL, 0, TRUE);
+               crStop(0);
+           }
+           ssh->username = dupstr(s->cur_prompt->prompts[0]->result);
+           free_prompts(s->cur_prompt);
        }
 
-       send_packet(ssh, SSH1_CMSG_USER, PKT_STR, s->username, PKT_END);
+       send_packet(ssh, SSH1_CMSG_USER, PKT_STR, ssh->username, PKT_END);
        {
-           char userlog[22 + sizeof(s->username)];
-           sprintf(userlog, "Sent username \"%s\"", s->username);
+           char *userlog = dupprintf("Sent username \"%s\"", ssh->username);
            logevent(userlog);
            if (flags & FLAG_INTERACTIVE &&
                (!((flags & FLAG_STDERR) && (flags & FLAG_VERBOSE)))) {
-               strcat(userlog, "\r\n");
                c_write_str(ssh, userlog);
+               c_write_str(ssh, "\r\n");
            }
+           sfree(userlog);
        }
     }
 
     crWaitUntil(pktin);
 
-    if ((ssh->remote_bugs & BUG_CHOKES_ON_RSA)) {
+    if ((s->supported_auths_mask & (1 << SSH1_AUTH_RSA)) == 0) {
        /* We must not attempt PK auth. Pretend we've already tried it. */
        s->tried_publickey = s->tried_agent = 1;
     } else {
        s->tried_publickey = s->tried_agent = 0;
     }
     s->tis_auth_refused = s->ccard_auth_refused = 0;
-    /* Load the public half of ssh->cfg.keyfile so we notice if it's in Pageant */
-    if (!filename_is_null(ssh->cfg.keyfile)) {
-       if (!rsakey_pubblob(&ssh->cfg.keyfile,
-                           &s->publickey_blob, &s->publickey_bloblen, NULL))
+    /*
+     * Load the public half of any configured keyfile for later use.
+     */
+    s->keyfile = conf_get_filename(ssh->conf, CONF_keyfile);
+    if (!filename_is_null(s->keyfile)) {
+       int keytype;
+       logeventf(ssh, "Reading private key file \"%.150s\"",
+                 filename_to_str(s->keyfile));
+       keytype = key_type(s->keyfile);
+       if (keytype == SSH_KEYTYPE_SSH1) {
+           const char *error;
+           if (rsakey_pubblob(s->keyfile,
+                              &s->publickey_blob, &s->publickey_bloblen,
+                              &s->publickey_comment, &error)) {
+               s->publickey_encrypted = rsakey_encrypted(s->keyfile,
+                                                         NULL);
+           } else {
+               char *msgbuf;
+               logeventf(ssh, "Unable to load private key (%s)", error);
+               msgbuf = dupprintf("Unable to load private key file "
+                                  "\"%.150s\" (%s)\r\n",
+                                  filename_to_str(s->keyfile),
+                                  error);
+               c_write_str(ssh, msgbuf);
+               sfree(msgbuf);
+               s->publickey_blob = NULL;
+           }
+       } else {
+           char *msgbuf;
+           logeventf(ssh, "Unable to use this key file (%s)",
+                     key_type_to_str(keytype));
+           msgbuf = dupprintf("Unable to use key file \"%.150s\""
+                              " (%s)\r\n",
+                              filename_to_str(s->keyfile),
+                              key_type_to_str(keytype));
+           c_write_str(ssh, msgbuf);
+           sfree(msgbuf);
            s->publickey_blob = NULL;
+       }
     } else
        s->publickey_blob = NULL;
 
     while (pktin->type == SSH1_SMSG_FAILURE) {
        s->pwpkt_type = SSH1_CMSG_AUTH_PASSWORD;
 
-       if (agent_exists() && !s->tried_agent) {
+       if (conf_get_int(ssh->conf, CONF_tryagent) && agent_exists() && !s->tried_agent) {
            /*
             * Attempt RSA authentication using Pageant.
             */
@@ -3284,38 +4184,38 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
            if (s->response && s->responselen >= 5 &&
                s->response[4] == SSH1_AGENT_RSA_IDENTITIES_ANSWER) {
                s->p = s->response + 5;
-               s->nkeys = GET_32BIT(s->p);
+               s->nkeys = toint(GET_32BIT(s->p));
+                if (s->nkeys < 0) {
+                    logeventf(ssh, "Pageant reported negative key count %d",
+                              s->nkeys);
+                    s->nkeys = 0;
+                }
                s->p += 4;
                logeventf(ssh, "Pageant has %d SSH-1 keys", s->nkeys);
                for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
-                   logeventf(ssh, "Trying Pageant key #%d", s->keyi);
-                   if (s->publickey_blob &&
-                       !memcmp(s->p, s->publickey_blob,
-                               s->publickey_bloblen)) {
-                       logevent("This key matches configured key file");
-                       s->tried_publickey = 1;
-                   }
+                   unsigned char *pkblob = s->p;
                    s->p += 4;
                    {
                        int n, ok = FALSE;
                        do {           /* do while (0) to make breaking easy */
                            n = ssh1_read_bignum
-                               (s->p, s->responselen-(s->p-s->response),
+                               (s->p, toint(s->responselen-(s->p-s->response)),
                                 &s->key.exponent);
                            if (n < 0)
                                break;
                            s->p += n;
                            n = ssh1_read_bignum
-                               (s->p, s->responselen-(s->p-s->response),
+                               (s->p, toint(s->responselen-(s->p-s->response)),
                                 &s->key.modulus);
                            if (n < 0)
-                           break;
+                                break;
                            s->p += n;
                            if (s->responselen - (s->p-s->response) < 4)
                                break;
-                           s->commentlen = GET_32BIT(s->p);
+                           s->commentlen = toint(GET_32BIT(s->p));
                            s->p += 4;
-                           if (s->responselen - (s->p-s->response) <
+                           if (s->commentlen < 0 ||
+                                toint(s->responselen - (s->p-s->response)) <
                                s->commentlen)
                                break;
                            s->commentp = (char *)s->p;
@@ -3327,6 +4227,17 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                            break;
                        }
                    }
+                   if (s->publickey_blob) {
+                       if (!memcmp(pkblob, s->publickey_blob,
+                                   s->publickey_bloblen)) {
+                           logeventf(ssh, "Pageant key #%d matches "
+                                     "configured key file", s->keyi);
+                           s->tried_publickey = 1;
+                       } else
+                           /* Skip non-configured key */
+                           continue;
+                   }
+                   logeventf(ssh, "Trying Pageant key #%d", s->keyi);
                    send_packet(ssh, SSH1_CMSG_AUTH_RSA,
                                PKT_BIGNUM, s->key.modulus, PKT_END);
                    crWaitUntil(pktin);
@@ -3417,14 +4328,161 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                        break;
                }
                sfree(s->response);
-           }
+               if (s->publickey_blob && !s->tried_publickey)
+                   logevent("Configured key file not in Pageant");
+           } else {
+                logevent("Failed to get reply from Pageant");
+            }
            if (s->authed)
                break;
        }
-       if (!filename_is_null(ssh->cfg.keyfile) && !s->tried_publickey)
-           s->pwpkt_type = SSH1_CMSG_AUTH_RSA;
+       if (s->publickey_blob && !s->tried_publickey) {
+           /*
+            * Try public key authentication with the specified
+            * key file.
+            */
+           int got_passphrase; /* need not be kept over crReturn */
+           if (flags & FLAG_VERBOSE)
+               c_write_str(ssh, "Trying public key authentication.\r\n");
+           s->keyfile = conf_get_filename(ssh->conf, CONF_keyfile);
+           logeventf(ssh, "Trying public key \"%s\"",
+                     filename_to_str(s->keyfile));
+           s->tried_publickey = 1;
+           got_passphrase = FALSE;
+           while (!got_passphrase) {
+               /*
+                * Get a passphrase, if necessary.
+                */
+               char *passphrase = NULL;    /* only written after crReturn */
+               const char *error;
+               if (!s->publickey_encrypted) {
+                   if (flags & FLAG_VERBOSE)
+                       c_write_str(ssh, "No passphrase required.\r\n");
+                   passphrase = NULL;
+               } else {
+                   int ret; /* need not be kept over crReturn */
+                   s->cur_prompt = new_prompts(ssh->frontend);
+                   s->cur_prompt->to_server = FALSE;
+                   s->cur_prompt->name = dupstr("SSH key passphrase");
+                   add_prompt(s->cur_prompt,
+                              dupprintf("Passphrase for key \"%.100s\": ",
+                                        s->publickey_comment), FALSE);
+                   ret = get_userpass_input(s->cur_prompt, NULL, 0);
+                   while (ret < 0) {
+                       ssh->send_ok = 1;
+                       crWaitUntil(!pktin);
+                       ret = get_userpass_input(s->cur_prompt, in, inlen);
+                       ssh->send_ok = 0;
+                   }
+                   if (!ret) {
+                       /* Failed to get a passphrase. Terminate. */
+                       free_prompts(s->cur_prompt);
+                       ssh_disconnect(ssh, NULL, "Unable to authenticate",
+                                      0, TRUE);
+                       crStop(0);
+                   }
+                   passphrase = dupstr(s->cur_prompt->prompts[0]->result);
+                   free_prompts(s->cur_prompt);
+               }
+               /*
+                * Try decrypting key with passphrase.
+                */
+               s->keyfile = conf_get_filename(ssh->conf, CONF_keyfile);
+               ret = loadrsakey(s->keyfile, &s->key, passphrase,
+                                &error);
+               if (passphrase) {
+                   smemclr(passphrase, strlen(passphrase));
+                   sfree(passphrase);
+               }
+               if (ret == 1) {
+                   /* Correct passphrase. */
+                   got_passphrase = TRUE;
+               } else if (ret == 0) {
+                   c_write_str(ssh, "Couldn't load private key from ");
+                   c_write_str(ssh, filename_to_str(s->keyfile));
+                   c_write_str(ssh, " (");
+                   c_write_str(ssh, error);
+                   c_write_str(ssh, ").\r\n");
+                   got_passphrase = FALSE;
+                   break;             /* go and try something else */
+               } else if (ret == -1) {
+                   c_write_str(ssh, "Wrong passphrase.\r\n"); /* FIXME */
+                   got_passphrase = FALSE;
+                   /* and try again */
+               } else {
+                   assert(0 && "unexpected return from loadrsakey()");
+                   got_passphrase = FALSE;   /* placate optimisers */
+               }
+           }
+
+           if (got_passphrase) {
+
+               /*
+                * Send a public key attempt.
+                */
+               send_packet(ssh, SSH1_CMSG_AUTH_RSA,
+                           PKT_BIGNUM, s->key.modulus, PKT_END);
+
+               crWaitUntil(pktin);
+               if (pktin->type == SSH1_SMSG_FAILURE) {
+                   c_write_str(ssh, "Server refused our public key.\r\n");
+                   continue;          /* go and try something else */
+               }
+               if (pktin->type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
+                   bombout(("Bizarre response to offer of public key"));
+                   crStop(0);
+               }
+
+               {
+                   int i;
+                   unsigned char buffer[32];
+                   Bignum challenge, response;
+
+                   if ((challenge = ssh1_pkt_getmp(pktin)) == NULL) {
+                       bombout(("Server's RSA challenge was badly formatted"));
+                       crStop(0);
+                   }
+                   response = rsadecrypt(challenge, &s->key);
+                   freebn(s->key.private_exponent);/* burn the evidence */
+
+                   for (i = 0; i < 32; i++) {
+                       buffer[i] = bignum_byte(response, 31 - i);
+                   }
+
+                   MD5Init(&md5c);
+                   MD5Update(&md5c, buffer, 32);
+                   MD5Update(&md5c, s->session_id, 16);
+                   MD5Final(buffer, &md5c);
+
+                   send_packet(ssh, SSH1_CMSG_AUTH_RSA_RESPONSE,
+                               PKT_DATA, buffer, 16, PKT_END);
+
+                   freebn(challenge);
+                   freebn(response);
+               }
+
+               crWaitUntil(pktin);
+               if (pktin->type == SSH1_SMSG_FAILURE) {
+                   if (flags & FLAG_VERBOSE)
+                       c_write_str(ssh, "Failed to authenticate with"
+                                   " our public key.\r\n");
+                   continue;          /* go and try something else */
+               } else if (pktin->type != SSH1_SMSG_SUCCESS) {
+                   bombout(("Bizarre response to RSA authentication response"));
+                   crStop(0);
+               }
+
+               break;                 /* we're through! */
+           }
+
+       }
+
+       /*
+        * Otherwise, try various forms of password-like authentication.
+        */
+       s->cur_prompt = new_prompts(ssh->frontend);
 
-       if (ssh->cfg.try_tis_auth &&
+       if (conf_get_int(ssh->conf, CONF_try_tis_auth) &&
            (s->supported_auths_mask & (1 << SSH1_AUTH_TIS)) &&
            !s->tis_auth_refused) {
            s->pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE;
@@ -3440,26 +4498,34 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
            } else {
                char *challenge;
                int challengelen;
+               char *instr_suf, *prompt;
 
                ssh_pkt_getstring(pktin, &challenge, &challengelen);
                if (!challenge) {
                    bombout(("TIS challenge packet was badly formed"));
                    crStop(0);
                }
-               c_write_str(ssh, "Using TIS authentication.\r\n");
                logevent("Received TIS challenge");
-               if (challengelen > sizeof(s->prompt) - 1)
-                   challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
-               memcpy(s->prompt, challenge, challengelen);
+               s->cur_prompt->to_server = TRUE;
+               s->cur_prompt->name = dupstr("SSH TIS authentication");
                /* Prompt heuristic comes from OpenSSH */
-               strncpy(s->prompt + challengelen,
-                       memchr(s->prompt, '\n', challengelen) ?
-                       "": "\r\nResponse: ",
-                       (sizeof s->prompt) - challengelen);
-               s->prompt[(sizeof s->prompt) - 1] = '\0';
+               if (memchr(challenge, '\n', challengelen)) {
+                   instr_suf = dupstr("");
+                   prompt = dupprintf("%.*s", challengelen, challenge);
+               } else {
+                   instr_suf = dupprintf("%.*s", challengelen, challenge);
+                   prompt = dupstr("Response: ");
+               }
+               s->cur_prompt->instruction =
+                   dupprintf("Using TIS authentication.%s%s",
+                             (*instr_suf) ? "\n" : "",
+                             instr_suf);
+               s->cur_prompt->instr_reqd = TRUE;
+               add_prompt(s->cur_prompt, prompt, FALSE);
+               sfree(instr_suf);
            }
        }
-       if (ssh->cfg.try_tis_auth &&
+       if (conf_get_int(ssh->conf, CONF_try_tis_auth) &&
            (s->supported_auths_mask & (1 << SSH1_AUTH_CCARD)) &&
            !s->ccard_auth_refused) {
            s->pwpkt_type = SSH1_CMSG_AUTH_CCARD_RESPONSE;
@@ -3474,53 +4540,44 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
            } else {
                char *challenge;
                int challengelen;
+               char *instr_suf, *prompt;
 
                ssh_pkt_getstring(pktin, &challenge, &challengelen);
                if (!challenge) {
                    bombout(("CryptoCard challenge packet was badly formed"));
                    crStop(0);
                }
-               c_write_str(ssh, "Using CryptoCard authentication.\r\n");
                logevent("Received CryptoCard challenge");
-               if (challengelen > sizeof(s->prompt) - 1)
-                   challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
-               memcpy(s->prompt, challenge, challengelen);
-               strncpy(s->prompt + challengelen,
-                       memchr(s->prompt, '\n', challengelen) ?
-                       "" : "\r\nResponse: ",
-                       sizeof(s->prompt) - challengelen);
-               s->prompt[sizeof(s->prompt) - 1] = '\0';
+               s->cur_prompt->to_server = TRUE;
+               s->cur_prompt->name = dupstr("SSH CryptoCard authentication");
+               s->cur_prompt->name_reqd = FALSE;
+               /* Prompt heuristic comes from OpenSSH */
+               if (memchr(challenge, '\n', challengelen)) {
+                   instr_suf = dupstr("");
+                   prompt = dupprintf("%.*s", challengelen, challenge);
+               } else {
+                   instr_suf = dupprintf("%.*s", challengelen, challenge);
+                   prompt = dupstr("Response: ");
+               }
+               s->cur_prompt->instruction =
+                   dupprintf("Using CryptoCard authentication.%s%s",
+                             (*instr_suf) ? "\n" : "",
+                             instr_suf);
+               s->cur_prompt->instr_reqd = TRUE;
+               add_prompt(s->cur_prompt, prompt, FALSE);
+               sfree(instr_suf);
            }
        }
        if (s->pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
-           sprintf(s->prompt, "%.90s@%.90s's password: ",
-                   s->username, ssh->savedhost);
-       }
-       if (s->pwpkt_type == SSH1_CMSG_AUTH_RSA) {
-           char *comment = NULL;
-           int type;
-           if (flags & FLAG_VERBOSE)
-               c_write_str(ssh, "Trying public key authentication.\r\n");
-           logeventf(ssh, "Trying public key \"%s\"",
-                     filename_to_str(&ssh->cfg.keyfile));
-           type = key_type(&ssh->cfg.keyfile);
-           if (type != SSH_KEYTYPE_SSH1) {
-               char *msg = dupprintf("Key is of wrong type (%s)",
-                                     key_type_to_str(type));
-               logevent(msg);
-               c_write_str(ssh, msg);
-               c_write_str(ssh, "\r\n");
-               sfree(msg);
-               s->tried_publickey = 1;
-               continue;
-           }
-           if (!rsakey_encrypted(&ssh->cfg.keyfile, &comment)) {
-               if (flags & FLAG_VERBOSE)
-                   c_write_str(ssh, "No passphrase required.\r\n");
-               goto tryauth;
+           if ((s->supported_auths_mask & (1 << SSH1_AUTH_PASSWORD)) == 0) {
+               bombout(("No supported authentication methods available"));
+               crStop(0);
            }
-           sprintf(s->prompt, "Passphrase for key \"%.100s\": ", comment);
-           sfree(comment);
+           s->cur_prompt->to_server = TRUE;
+           s->cur_prompt->name = dupstr("SSH password");
+           add_prompt(s->cur_prompt, dupprintf("%s@%s's password: ",
+                                               ssh->username, ssh->savedhost),
+                      FALSE);
        }
 
        /*
@@ -3528,245 +4585,152 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
         * or CryptoCard exchange if we're doing TIS or CryptoCard
         * authentication.
         */
-       if (ssh_get_line) {
-           if (!ssh_get_line(s->prompt, s->password,
-                             sizeof(s->password), TRUE)) {
+       {
+           int ret; /* need not be kept over crReturn */
+           ret = get_userpass_input(s->cur_prompt, NULL, 0);
+           while (ret < 0) {
+               ssh->send_ok = 1;
+               crWaitUntil(!pktin);
+               ret = get_userpass_input(s->cur_prompt, in, inlen);
+               ssh->send_ok = 0;
+           }
+           if (!ret) {
                /*
-                * get_line failed to get a password (for example
+                * Failed to get a password (for example
                 * because one was supplied on the command line
                 * which has already failed to work). Terminate.
                 */
-               ssh_disconnect(ssh, NULL, "Unable to authenticate", 0, FALSE);
-               crStop(1);
+               free_prompts(s->cur_prompt);
+               ssh_disconnect(ssh, NULL, "Unable to authenticate", 0, TRUE);
+               crStop(0);
            }
-       } else {
-           /* Prompt may have come from server. We've munged it a bit, so
-            * we know it to be zero-terminated at least once. */
-           int ret;                   /* need not be saved over crReturn */
-           c_write_untrusted(ssh, s->prompt, strlen(s->prompt));
-           s->pos = 0;
-
-           setup_userpass_input(ssh, s->password, sizeof(s->password), 0);
-           do {
-               crWaitUntil(!pktin);
-               ret = process_userpass_input(ssh, in, inlen);
-           } while (ret == 0);
-           if (ret < 0)
-               cleanup_exit(0);
-           c_write_str(ssh, "\r\n");
        }
 
-      tryauth:
-       if (s->pwpkt_type == SSH1_CMSG_AUTH_RSA) {
-           /*
-            * Try public key authentication with the specified
-            * key file.
-            */
-           s->tried_publickey = 1;
-           
-           {
-               const char *error = NULL;
-               int ret = loadrsakey(&ssh->cfg.keyfile, &s->key, s->password,
-                                    &error);
-               if (ret == 0) {
-                   c_write_str(ssh, "Couldn't load private key from ");
-                   c_write_str(ssh, filename_to_str(&ssh->cfg.keyfile));
-                   c_write_str(ssh, " (");
-                   c_write_str(ssh, error);
-                   c_write_str(ssh, ").\r\n");
-                   continue;          /* go and try password */
-               }
-               if (ret == -1) {
-                   c_write_str(ssh, "Wrong passphrase.\r\n");
-                   s->tried_publickey = 0;
-                   continue;          /* try again */
-               }
-           }
-
+       if (s->pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
            /*
-            * Send a public key attempt.
+            * Defence against traffic analysis: we send a
+            * whole bunch of packets containing strings of
+            * different lengths. One of these strings is the
+            * password, in a SSH1_CMSG_AUTH_PASSWORD packet.
+            * The others are all random data in
+            * SSH1_MSG_IGNORE packets. This way a passive
+            * listener can't tell which is the password, and
+            * hence can't deduce the password length.
+            * 
+            * Anybody with a password length greater than 16
+            * bytes is going to have enough entropy in their
+            * password that a listener won't find it _that_
+            * much help to know how long it is. So what we'll
+            * do is:
+            * 
+            *  - if password length < 16, we send 15 packets
+            *    containing string lengths 1 through 15
+            * 
+            *  - otherwise, we let N be the nearest multiple
+            *    of 8 below the password length, and send 8
+            *    packets containing string lengths N through
+            *    N+7. This won't obscure the order of
+            *    magnitude of the password length, but it will
+            *    introduce a bit of extra uncertainty.
+            * 
+            * A few servers can't deal with SSH1_MSG_IGNORE, at
+            * least in this context. For these servers, we need
+            * an alternative defence. We make use of the fact
+            * that the password is interpreted as a C string:
+            * so we can append a NUL, then some random data.
+            * 
+            * A few servers can deal with neither SSH1_MSG_IGNORE
+            * here _nor_ a padded password string.
+            * For these servers we are left with no defences
+            * against password length sniffing.
             */
-           send_packet(ssh, SSH1_CMSG_AUTH_RSA,
-                       PKT_BIGNUM, s->key.modulus, PKT_END);
-
-           crWaitUntil(pktin);
-           if (pktin->type == SSH1_SMSG_FAILURE) {
-               c_write_str(ssh, "Server refused our public key.\r\n");
-               continue;              /* go and try password */
-           }
-           if (pktin->type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
-               bombout(("Bizarre response to offer of public key"));
-               crStop(0);
-           }
-
-           {
-               int i;
-               unsigned char buffer[32];
-               Bignum challenge, response;
-
-               if ((challenge = ssh1_pkt_getmp(pktin)) == NULL) {
-                   bombout(("Server's RSA challenge was badly formatted"));
-                   crStop(0);
-               }
-               response = rsadecrypt(challenge, &s->key);
-               freebn(s->key.private_exponent);/* burn the evidence */
-
-               for (i = 0; i < 32; i++) {
-                   buffer[i] = bignum_byte(response, 31 - i);
-               }
-
-               MD5Init(&md5c);
-               MD5Update(&md5c, buffer, 32);
-               MD5Update(&md5c, s->session_id, 16);
-               MD5Final(buffer, &md5c);
-
-               send_packet(ssh, SSH1_CMSG_AUTH_RSA_RESPONSE,
-                           PKT_DATA, buffer, 16, PKT_END);
-
-               freebn(challenge);
-               freebn(response);
-           }
-
-           crWaitUntil(pktin);
-           if (pktin->type == SSH1_SMSG_FAILURE) {
-               if (flags & FLAG_VERBOSE)
-                   c_write_str(ssh, "Failed to authenticate with"
-                               " our public key.\r\n");
-               continue;              /* go and try password */
-           } else if (pktin->type != SSH1_SMSG_SUCCESS) {
-               bombout(("Bizarre response to RSA authentication response"));
-               crStop(0);
-           }
-
-           break;                     /* we're through! */
-       } else {
-           if (s->pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
+           if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE) &&
+               !(ssh->remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) {
                /*
-                * Defence against traffic analysis: we send a
-                * whole bunch of packets containing strings of
-                * different lengths. One of these strings is the
-                * password, in a SSH1_CMSG_AUTH_PASSWORD packet.
-                * The others are all random data in
-                * SSH1_MSG_IGNORE packets. This way a passive
-                * listener can't tell which is the password, and
-                * hence can't deduce the password length.
-                * 
-                * Anybody with a password length greater than 16
-                * bytes is going to have enough entropy in their
-                * password that a listener won't find it _that_
-                * much help to know how long it is. So what we'll
-                * do is:
-                * 
-                *  - if password length < 16, we send 15 packets
-                *    containing string lengths 1 through 15
-                * 
-                *  - otherwise, we let N be the nearest multiple
-                *    of 8 below the password length, and send 8
-                *    packets containing string lengths N through
-                *    N+7. This won't obscure the order of
-                *    magnitude of the password length, but it will
-                *    introduce a bit of extra uncertainty.
-                * 
-                * A few servers (the old 1.2.18 through 1.2.22)
-                * can't deal with SSH1_MSG_IGNORE. For these
-                * servers, we need an alternative defence. We make
-                * use of the fact that the password is interpreted
-                * as a C string: so we can append a NUL, then some
-                * random data.
-                * 
-                * One server (a Cisco one) can deal with neither
-                * SSH1_MSG_IGNORE _nor_ a padded password string.
-                * For this server we are left with no defences
-                * against password length sniffing.
+                * The server can deal with SSH1_MSG_IGNORE, so
+                * we can use the primary defence.
                 */
-               if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE)) {
-                   /*
-                    * The server can deal with SSH1_MSG_IGNORE, so
-                    * we can use the primary defence.
-                    */
-                   int bottom, top, pwlen, i;
-                   char *randomstr;
+               int bottom, top, pwlen, i;
+               char *randomstr;
 
-                   pwlen = strlen(s->password);
-                   if (pwlen < 16) {
-                       bottom = 0;    /* zero length passwords are OK! :-) */
-                       top = 15;
-                   } else {
-                       bottom = pwlen & ~7;
-                       top = bottom + 7;
-                   }
+               pwlen = strlen(s->cur_prompt->prompts[0]->result);
+               if (pwlen < 16) {
+                   bottom = 0;    /* zero length passwords are OK! :-) */
+                   top = 15;
+               } else {
+                   bottom = pwlen & ~7;
+                   top = bottom + 7;
+               }
 
-                   assert(pwlen >= bottom && pwlen <= top);
+               assert(pwlen >= bottom && pwlen <= top);
 
-                   randomstr = snewn(top + 1, char);
+               randomstr = snewn(top + 1, char);
 
-                   for (i = bottom; i <= top; i++) {
-                       if (i == pwlen) {
-                           defer_packet(ssh, s->pwpkt_type,
-                                        PKTT_PASSWORD, PKT_STR, s->password,
-                                        PKTT_OTHER, PKT_END);
-                       } else {
-                           for (j = 0; j < i; j++) {
-                               do {
-                                   randomstr[j] = random_byte();
-                               } while (randomstr[j] == '\0');
-                           }
-                           randomstr[i] = '\0';
-                           defer_packet(ssh, SSH1_MSG_IGNORE,
-                                        PKT_STR, randomstr, PKT_END);
+               for (i = bottom; i <= top; i++) {
+                   if (i == pwlen) {
+                       defer_packet(ssh, s->pwpkt_type,
+                                     PKT_STR,s->cur_prompt->prompts[0]->result,
+                                    PKT_END);
+                   } else {
+                       for (j = 0; j < i; j++) {
+                           do {
+                               randomstr[j] = random_byte();
+                           } while (randomstr[j] == '\0');
                        }
+                       randomstr[i] = '\0';
+                       defer_packet(ssh, SSH1_MSG_IGNORE,
+                                    PKT_STR, randomstr, PKT_END);
                    }
-                   logevent("Sending password with camouflage packets");
-                   ssh_pkt_defersend(ssh);
-                   sfree(randomstr);
-               } 
-               else if (!(ssh->remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) {
-                   /*
-                    * The server can't deal with SSH1_MSG_IGNORE
-                    * but can deal with padded passwords, so we
-                    * can use the secondary defence.
-                    */
-                   char string[64];
-                   char *ss;
-                   int len;
-
-                   len = strlen(s->password);
-                   if (len < sizeof(string)) {
-                       ss = string;
-                       strcpy(string, s->password);
-                       len++;         /* cover the zero byte */
-                       while (len < sizeof(string)) {
-                           string[len++] = (char) random_byte();
-                       }
-                   } else {
-                       ss = s->password;
+               }
+               logevent("Sending password with camouflage packets");
+               ssh_pkt_defersend(ssh);
+               sfree(randomstr);
+           } 
+           else if (!(ssh->remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) {
+               /*
+                * The server can't deal with SSH1_MSG_IGNORE
+                * but can deal with padded passwords, so we
+                * can use the secondary defence.
+                */
+               char string[64];
+               char *ss;
+               int len;
+
+               len = strlen(s->cur_prompt->prompts[0]->result);
+               if (len < sizeof(string)) {
+                   ss = string;
+                   strcpy(string, s->cur_prompt->prompts[0]->result);
+                   len++;             /* cover the zero byte */
+                   while (len < sizeof(string)) {
+                       string[len++] = (char) random_byte();
                    }
-                   logevent("Sending length-padded password");
-                   send_packet(ssh, s->pwpkt_type, PKTT_PASSWORD,
-                               PKT_INT, len, PKT_DATA, ss, len,
-                               PKTT_OTHER, PKT_END);
                } else {
-                   /*
-                    * The server has _both_
-                    * BUG_CHOKES_ON_SSH1_IGNORE and
-                    * BUG_NEEDS_SSH1_PLAIN_PASSWORD. There is
-                    * therefore nothing we can do.
-                    */
-                   int len;
-                   len = strlen(s->password);
-                   logevent("Sending unpadded password");
-                   send_packet(ssh, s->pwpkt_type,
-                               PKTT_PASSWORD, PKT_INT, len,
-                               PKT_DATA, s->password, len,
-                               PKTT_OTHER, PKT_END);
+                   ss = s->cur_prompt->prompts[0]->result;
                }
+               logevent("Sending length-padded password");
+               send_packet(ssh, s->pwpkt_type,
+                           PKT_INT, len, PKT_DATA, ss, len,
+                           PKT_END);
            } else {
-               send_packet(ssh, s->pwpkt_type, PKTT_PASSWORD,
-                           PKT_STR, s->password, PKTT_OTHER, PKT_END);
+               /*
+                * The server is believed unable to cope with
+                * any of our password camouflage methods.
+                */
+               int len;
+               len = strlen(s->cur_prompt->prompts[0]->result);
+               logevent("Sending unpadded password");
+               send_packet(ssh, s->pwpkt_type,
+                            PKT_INT, len,
+                           PKT_DATA, s->cur_prompt->prompts[0]->result, len,
+                           PKT_END);
            }
+       } else {
+           send_packet(ssh, s->pwpkt_type,
+                       PKT_STR, s->cur_prompt->prompts[0]->result,
+                       PKT_END);
        }
        logevent("Sent password");
-       memset(s->password, 0, strlen(s->password));
+       free_prompts(s->cur_prompt);
        crWaitUntil(pktin);
        if (pktin->type == SSH1_SMSG_FAILURE) {
            if (flags & FLAG_VERBOSE)
@@ -3778,47 +4742,84 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        }
     }
 
+    /* Clear up */
+    if (s->publickey_blob) {
+       sfree(s->publickey_blob);
+       sfree(s->publickey_comment);
+    }
+
     logevent("Authentication successful");
 
     crFinish(1);
 }
 
-void sshfwd_close(struct ssh_channel *c)
+static void ssh_channel_try_eof(struct ssh_channel *c)
+{
+    Ssh ssh = c->ssh;
+    assert(c->pending_eof);          /* precondition for calling us */
+    if (c->halfopen)
+        return;                 /* can't close: not even opened yet */
+    if (ssh->version == 2 && bufchain_size(&c->v.v2.outbuffer) > 0)
+        return;              /* can't send EOF: pending outgoing data */
+
+    c->pending_eof = FALSE;            /* we're about to send it */
+    if (ssh->version == 1) {
+        send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
+                    PKT_END);
+        c->closes |= CLOSES_SENT_EOF;
+    } else {
+        struct Packet *pktout;
+        pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_EOF);
+        ssh2_pkt_adduint32(pktout, c->remoteid);
+        ssh2_pkt_send(ssh, pktout);
+        c->closes |= CLOSES_SENT_EOF;
+       ssh2_channel_check_close(c);
+    }
+}
+
+Conf *sshfwd_get_conf(struct ssh_channel *c)
+{
+    Ssh ssh = c->ssh;
+    return ssh->conf;
+}
+
+void sshfwd_write_eof(struct ssh_channel *c)
 {
     Ssh ssh = c->ssh;
 
     if (ssh->state == SSH_STATE_CLOSED)
        return;
 
-    if (c && !c->closes) {
-       /*
-        * If halfopen is true, we have sent
-        * CHANNEL_OPEN for this channel, but it hasn't even been
-        * acknowledged by the server. So we must set a close flag
-        * on it now, and then when the server acks the channel
-        * open, we can close it then.
-        */
-       if (!c->halfopen) {
-           if (ssh->version == 1) {
-               send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
-                           PKT_END);
-           } else {
-               struct Packet *pktout;
-               pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
-               ssh2_pkt_adduint32(pktout, c->remoteid);
-               ssh2_pkt_send(ssh, pktout);
-           }
-       }
-       c->closes = 1;                 /* sent MSG_CLOSE */
-       if (c->type == CHAN_X11) {
-           c->u.x11.s = NULL;
-           logevent("Forwarded X11 connection terminated");
-       } else if (c->type == CHAN_SOCKDATA ||
-                  c->type == CHAN_SOCKDATA_DORMANT) {
-           c->u.pfd.s = NULL;
-           logevent("Forwarded port closed");
-       }
+    if (c->closes & CLOSES_SENT_EOF)
+        return;
+
+    c->pending_eof = TRUE;
+    ssh_channel_try_eof(c);
+}
+
+void sshfwd_unclean_close(struct ssh_channel *c, const char *err)
+{
+    Ssh ssh = c->ssh;
+
+    if (ssh->state == SSH_STATE_CLOSED)
+       return;
+
+    switch (c->type) {
+      case CHAN_X11:
+        x11_close(c->u.x11.xconn);
+        logeventf(ssh, "Forwarded X11 connection terminated due to local "
+                  "error: %s", err);
+        break;
+      case CHAN_SOCKDATA:
+      case CHAN_SOCKDATA_DORMANT:
+        pfd_close(c->u.pfd.pf);
+        logeventf(ssh, "Forwarded port closed due to local error: %s", err);
+        break;
     }
+    c->type = CHAN_ZOMBIE;
+    c->pending_eof = FALSE;   /* this will confuse a zombie channel */
+
+    ssh2_channel_check_close(c);
 }
 
 int sshfwd_write(struct ssh_channel *c, char *buf, int len)
@@ -3831,9 +4832,8 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
     if (ssh->version == 1) {
        send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
                    PKT_INT, c->remoteid,
-                   PKTT_DATA,
                    PKT_INT, len, PKT_DATA, buf, len,
-                   PKTT_OTHER, PKT_END);
+                   PKT_END);
        /*
         * In SSH-1 we can return 0 here - implying that forwarded
         * connections are never individually throttled - because
@@ -3851,17 +4851,20 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
 void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
 {
     Ssh ssh = c->ssh;
+    int buflimit;
 
     if (ssh->state == SSH_STATE_CLOSED)
        return;
 
     if (ssh->version == 1) {
-       if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) {
-           c->v.v1.throttling = 0;
-           ssh1_throttle(ssh, -1);
-       }
+       buflimit = SSH1_BUFFER_LIMIT;
     } else {
-       ssh2_set_window(c, OUR_V2_WINSIZE - bufsize);
+       buflimit = c->v.v2.locmaxwin;
+       ssh2_set_window(c, bufsize < buflimit ? buflimit - bufsize : 0);
+    }
+    if (c->throttling_conn && bufsize <= buflimit) {
+       c->throttling_conn = 0;
+       ssh_throttle_conn(ssh, -1);
     }
 }
 
@@ -3875,27 +4878,26 @@ static void ssh_queueing_handler(Ssh ssh, struct Packet *pktin)
 
     if (qh->msg1 > 0) {
        assert(ssh->packet_dispatch[qh->msg1] == ssh_queueing_handler);
-       ssh->packet_dispatch[qh->msg1] = NULL;
+       ssh->packet_dispatch[qh->msg1] = ssh->q_saved_handler1;
     }
     if (qh->msg2 > 0) {
        assert(ssh->packet_dispatch[qh->msg2] == ssh_queueing_handler);
-       ssh->packet_dispatch[qh->msg2] = NULL;
+       ssh->packet_dispatch[qh->msg2] = ssh->q_saved_handler2;
     }
 
     if (qh->next) {
        ssh->qhead = qh->next;
 
        if (ssh->qhead->msg1 > 0) {
-           assert(ssh->packet_dispatch[ssh->qhead->msg1] == NULL);
+           ssh->q_saved_handler1 = ssh->packet_dispatch[ssh->qhead->msg1];
            ssh->packet_dispatch[ssh->qhead->msg1] = ssh_queueing_handler;
        }
        if (ssh->qhead->msg2 > 0) {
-           assert(ssh->packet_dispatch[ssh->qhead->msg2] == NULL);
+           ssh->q_saved_handler2 = ssh->packet_dispatch[ssh->qhead->msg2];
            ssh->packet_dispatch[ssh->qhead->msg2] = ssh_queueing_handler;
        }
     } else {
        ssh->qhead = ssh->qtail = NULL;
-       ssh->packet_dispatch[pktin->type] = NULL;
     }
 
     qh->handler(ssh, pktin, qh->ctx);
@@ -3919,11 +4921,11 @@ static void ssh_queue_handler(Ssh ssh, int msg1, int msg2,
        ssh->qhead = qh;
 
        if (qh->msg1 > 0) {
-           assert(ssh->packet_dispatch[qh->msg1] == NULL);
+           ssh->q_saved_handler1 = ssh->packet_dispatch[ssh->qhead->msg1];
            ssh->packet_dispatch[qh->msg1] = ssh_queueing_handler;
        }
        if (qh->msg2 > 0) {
-           assert(ssh->packet_dispatch[qh->msg2] == NULL);
+           ssh->q_saved_handler2 = ssh->packet_dispatch[ssh->qhead->msg2];
            ssh->packet_dispatch[qh->msg2] = ssh_queueing_handler;
        }
     } else {
@@ -3946,15 +4948,51 @@ static void ssh_rportfwd_succfail(Ssh ssh, struct Packet *pktin, void *ctx)
 
        rpf = del234(ssh->rportfwds, pf);
        assert(rpf == pf);
+       pf->pfrec->remote = NULL;
        free_rportfwd(pf);
     }
 }
 
-static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
+int ssh_alloc_sharing_rportfwd(Ssh ssh, const char *shost, int sport,
+                               void *share_ctx)
+{
+    struct ssh_rportfwd *pf = snew(struct ssh_rportfwd);
+    pf->dhost = NULL;
+    pf->dport = 0;
+    pf->share_ctx = share_ctx;
+    pf->shost = dupstr(shost);
+    pf->sport = sport;
+    pf->sportdesc = NULL;
+    if (!ssh->rportfwds) {
+        assert(ssh->version == 2);
+        ssh->rportfwds = newtree234(ssh_rportcmp_ssh2);
+    }
+    if (add234(ssh->rportfwds, pf) != pf) {
+        sfree(pf->shost);
+        sfree(pf);
+        return FALSE;
+    }
+    return TRUE;
+}
+
+static void ssh_sharing_global_request_response(Ssh ssh, struct Packet *pktin,
+                                                void *ctx)
+{
+    share_got_pkt_from_server(ctx, pktin->type,
+                              pktin->body, pktin->length);
+}
+
+void ssh_sharing_queue_global_request(Ssh ssh, void *share_ctx)
+{
+    ssh_queue_handler(ssh, SSH2_MSG_REQUEST_SUCCESS, SSH2_MSG_REQUEST_FAILURE,
+                      ssh_sharing_global_request_response, share_ctx);
+}
+
+static void ssh_setup_portfwd(Ssh ssh, Conf *conf)
 {
-    const char *portfwd_strptr = cfg->portfwd;
     struct ssh_portfwd *epf;
     int i;
+    char *key, *val;
 
     if (!ssh->portfwds) {
        ssh->portfwds = newtree234(ssh_portcmp);
@@ -3972,64 +5010,63 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
            epf->status = DESTROY;
     }
 
-    while (*portfwd_strptr) {
+    for (val = conf_get_str_strs(conf, CONF_portfwd, NULL, &key);
+        val != NULL;
+        val = conf_get_str_strs(conf, CONF_portfwd, key, &key)) {
+       char *kp, *kp2, *vp, *vp2;
        char address_family, type;
        int sport,dport,sserv,dserv;
-       char sports[256], dports[256], saddr[256], host[256];
-       int n;
+       char *sports, *dports, *saddr, *host;
+
+       kp = key;
 
        address_family = 'A';
        type = 'L';
-       if (*portfwd_strptr == 'A' ||
-           *portfwd_strptr == '4' ||
-           *portfwd_strptr == '6')
-           address_family = *portfwd_strptr++;
-       if (*portfwd_strptr == 'L' ||
-           *portfwd_strptr == 'R' ||
-           *portfwd_strptr == 'D')
-           type = *portfwd_strptr++;
-
-       saddr[0] = '\0';
-
-       n = 0;
-       while (*portfwd_strptr && *portfwd_strptr != '\t') {
-           if (*portfwd_strptr == ':') {
-               /*
-                * We've seen a colon in the middle of the
-                * source port number. This means that
-                * everything we've seen until now is the
-                * source _address_, so we'll move it into
-                * saddr and start sports from the beginning
-                * again.
-                */
-               portfwd_strptr++;
-               sports[n] = '\0';
-               if (ssh->version == 1 && type == 'R') {
-                   logeventf(ssh, "SSH-1 cannot handle remote source address "
-                             "spec \"%s\"; ignoring", sports);
-               } else
-                   strcpy(saddr, sports);
-               n = 0;
-           }
-           if (n < lenof(sports)-1) sports[n++] = *portfwd_strptr++;
+       if (*kp == 'A' || *kp == '4' || *kp == '6')
+           address_family = *kp++;
+       if (*kp == 'L' || *kp == 'R')
+           type = *kp++;
+
+       if ((kp2 = host_strchr(kp, ':')) != NULL) {
+           /*
+            * There's a colon in the middle of the source port
+            * string, which means that the part before it is
+            * actually a source address.
+            */
+           char *saddr_tmp = dupprintf("%.*s", (int)(kp2 - kp), kp);
+            saddr = host_strduptrim(saddr_tmp);
+            sfree(saddr_tmp);
+           sports = kp2+1;
+       } else {
+           saddr = NULL;
+           sports = kp;
        }
-       sports[n] = 0;
-       if (type != 'D') {
-           if (*portfwd_strptr == '\t')
-               portfwd_strptr++;
-           n = 0;
-           while (*portfwd_strptr && *portfwd_strptr != ':') {
-               if (n < lenof(host)-1) host[n++] = *portfwd_strptr++;
-           }
-           host[n] = 0;
-           if (*portfwd_strptr == ':')
-               portfwd_strptr++;
-           n = 0;
-           while (*portfwd_strptr) {
-               if (n < lenof(dports)-1) dports[n++] = *portfwd_strptr++;
+       sport = atoi(sports);
+       sserv = 0;
+       if (sport == 0) {
+           sserv = 1;
+           sport = net_service_lookup(sports);
+           if (!sport) {
+               logeventf(ssh, "Service lookup failed for source"
+                         " port \"%s\"", sports);
            }
-           dports[n] = 0;
-           portfwd_strptr++;
+       }
+
+       if (type == 'L' && !strcmp(val, "D")) {
+            /* dynamic forwarding */
+           host = NULL;
+           dports = NULL;
+           dport = -1;
+           dserv = 0;
+            type = 'D';
+        } else {
+            /* ordinary forwarding */
+           vp = val;
+           vp2 = vp + host_strcspn(vp, ":");
+           host = dupprintf("%.*s", (int)(vp2 - vp), vp);
+           if (*vp2)
+               vp2++;
+           dports = vp2;
            dport = atoi(dports);
            dserv = 0;
            if (dport == 0) {
@@ -4040,33 +5077,18 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                              " port \"%s\"", dports);
                }
            }
-       } else {
-           while (*portfwd_strptr) portfwd_strptr++;
-           host[0] = 0;
-           dports[0] = 0;
-           dport = dserv = -1;
-           portfwd_strptr++;          /* eat the NUL and move to next one */
-       }
-       sport = atoi(sports);
-       sserv = 0;
-       if (sport == 0) {
-           sserv = 1;
-           sport = net_service_lookup(sports);
-           if (!sport) {
-               logeventf(ssh, "Service lookup failed for source"
-                         " port \"%s\"", sports);
-           }
        }
+
        if (sport && dport) {
            /* Set up a description of the source port. */
            struct ssh_portfwd *pfrec, *epfrec;
 
            pfrec = snew(struct ssh_portfwd);
            pfrec->type = type;
-           pfrec->saddr = *saddr ? dupstr(saddr) : NULL;
+           pfrec->saddr = saddr;
            pfrec->sserv = sserv ? dupstr(sports) : NULL;
            pfrec->sport = sport;
-           pfrec->daddr = *host ? dupstr(host) : NULL;
+           pfrec->daddr = host;
            pfrec->dserv = dserv ? dupstr(dports) : NULL;
            pfrec->dport = dport;
            pfrec->local = NULL;
@@ -4077,16 +5099,26 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 
            epfrec = add234(ssh->portfwds, pfrec);
            if (epfrec != pfrec) {
+               if (epfrec->status == DESTROY) {
+                   /*
+                    * We already have a port forwarding up and running
+                    * with precisely these parameters. Hence, no need
+                    * to do anything; simply re-tag the existing one
+                    * as KEEP.
+                    */
+                   epfrec->status = KEEP;
+               }
                /*
-                * We already have a port forwarding with precisely
-                * these parameters. Hence, no need to do anything;
-                * simply tag the existing one as KEEP.
+                * Anything else indicates that there was a duplicate
+                * in our input, which we'll silently ignore.
                 */
-               epfrec->status = KEEP;
                free_portfwd(pfrec);
            } else {
                pfrec->status = CREATE;
            }
+       } else {
+           sfree(saddr);
+           sfree(host);
        }
     }
 
@@ -4115,6 +5147,8 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
            logeventf(ssh, "Cancelling %s", message);
            sfree(message);
 
+           /* epf->remote or epf->local may be NULL if setting up a
+            * forwarding failed. */
            if (epf->remote) {
                struct ssh_rportfwd *rpf = epf->remote;
                struct Packet *pktout;
@@ -4138,13 +5172,13 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                    ssh2_pkt_addbool(pktout, 0);/* _don't_ want reply */
                    if (epf->saddr) {
                        ssh2_pkt_addstring(pktout, epf->saddr);
-                   } else if (ssh->cfg.rport_acceptall) {
-                       /* XXX: ssh->cfg.rport_acceptall may not represent
+                   } else if (conf_get_int(conf, CONF_rport_acceptall)) {
+                       /* XXX: rport_acceptall may not represent
                         * what was used to open the original connection,
                         * since it's reconfigurable. */
-                       ssh2_pkt_addstring(pktout, "0.0.0.0");
+                       ssh2_pkt_addstring(pktout, "");
                    } else {
-                       ssh2_pkt_addstring(pktout, "127.0.0.1");
+                       ssh2_pkt_addstring(pktout, "localhost");
                    }
                    ssh2_pkt_adduint32(pktout, epf->sport);
                    ssh2_pkt_send(ssh, pktout);
@@ -4153,7 +5187,7 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                del234(ssh->rportfwds, rpf);
                free_rportfwd(rpf);
            } else if (epf->local) {
-               pfd_terminate(epf->local);
+               pfl_terminate(epf->local);
            }
 
            delpos234(ssh->portfwds, i);
@@ -4186,29 +5220,31 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
            }
 
            if (epf->type == 'L') {
-               const char *err = pfd_addforward(epf->daddr, epf->dport,
-                                                epf->saddr, epf->sport,
-                                                ssh, cfg,
-                                                &epf->local,
-                                                epf->addressfamily);
+                char *err = pfl_listen(epf->daddr, epf->dport,
+                                       epf->saddr, epf->sport,
+                                       ssh, conf, &epf->local,
+                                       epf->addressfamily);
 
                logeventf(ssh, "Local %sport %s forwarding to %s%s%s",
                          epf->addressfamily == ADDRTYPE_IPV4 ? "IPv4 " :
                          epf->addressfamily == ADDRTYPE_IPV6 ? "IPv6 " : "",
                          sportdesc, dportdesc,
                          err ? " failed: " : "", err ? err : "");
+                if (err)
+                    sfree(err);
            } else if (epf->type == 'D') {
-               const char *err = pfd_addforward(NULL, -1,
-                                                epf->saddr, epf->sport,
-                                                ssh, cfg,
-                                                &epf->local,
-                                                epf->addressfamily);
+               char *err = pfl_listen(NULL, -1, epf->saddr, epf->sport,
+                                       ssh, conf, &epf->local,
+                                       epf->addressfamily);
 
                logeventf(ssh, "Local %sport %s SOCKS dynamic forwarding%s%s",
                          epf->addressfamily == ADDRTYPE_IPV4 ? "IPv4 " :
                          epf->addressfamily == ADDRTYPE_IPV6 ? "IPv6 " : "",
                          sportdesc,
                          err ? " failed: " : "", err ? err : "");
+
+                if (err)
+                    sfree(err);
            } else {
                struct ssh_rportfwd *pf;
 
@@ -4223,9 +5259,16 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                }
 
                pf = snew(struct ssh_rportfwd);
-               strncpy(pf->dhost, epf->daddr, lenof(pf->dhost)-1);
-               pf->dhost[lenof(pf->dhost)-1] = '\0';
+                pf->share_ctx = NULL;
+                pf->dhost = dupstr(epf->daddr);
                pf->dport = epf->dport;
+                if (epf->saddr) {
+                    pf->shost = dupstr(epf->saddr);
+                } else if (conf_get_int(conf, CONF_rport_acceptall)) {
+                    pf->shost = dupstr("");
+                } else {
+                    pf->shost = dupstr("localhost");
+                }
                pf->sport = epf->sport;
                if (add234(ssh->rportfwds, pf) != pf) {
                    logeventf(ssh, "Duplicate remote port forwarding to %s:%d",
@@ -4254,14 +5297,8 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                        pktout = ssh2_pkt_init(SSH2_MSG_GLOBAL_REQUEST);
                        ssh2_pkt_addstring(pktout, "tcpip-forward");
                        ssh2_pkt_addbool(pktout, 1);/* want reply */
-                       if (epf->saddr) {
-                           ssh2_pkt_addstring(pktout, epf->saddr);
-                       } else if (cfg->rport_acceptall) {
-                           ssh2_pkt_addstring(pktout, "0.0.0.0");
-                       } else {
-                           ssh2_pkt_addstring(pktout, "127.0.0.1");
-                       }
-                       ssh2_pkt_adduint32(pktout, epf->sport);
+                       ssh2_pkt_addstring(pktout, pf->shost);
+                       ssh2_pkt_adduint32(pktout, pf->sport);
                        ssh2_pkt_send(ssh, pktout);
 
                        ssh_queue_handler(ssh, SSH2_MSG_REQUEST_SUCCESS,
@@ -4290,7 +5327,7 @@ static void ssh1_smsg_stdout_stderr_data(Ssh ssh, struct Packet *pktin)
                           string, stringlen);
     if (!ssh->v1_stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) {
        ssh->v1_stdout_throttling = 1;
-       ssh1_throttle(ssh, +1);
+       ssh_throttle_conn(ssh, +1);
     }
 }
 
@@ -4311,27 +5348,19 @@ static void ssh1_smsg_x11_open(Ssh ssh, struct Packet *pktin)
        c = snew(struct ssh_channel);
        c->ssh = ssh;
 
-       if (x11_init(&c->u.x11.s, ssh->cfg.x11_display, c,
-                    ssh->x11auth, NULL, -1, &ssh->cfg) != NULL) {
-           logevent("Opening X11 forward connection failed");
-           sfree(c);
-           send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
-                       PKT_INT, remoteid, PKT_END);
-       } else {
-           logevent
-               ("Opening X11 forward connection succeeded");
-           c->remoteid = remoteid;
-           c->halfopen = FALSE;
-           c->localid = alloc_channel_id(ssh);
-           c->closes = 0;
-           c->v.v1.throttling = 0;
-           c->type = CHAN_X11; /* identify channel type */
-           add234(ssh->channels, c);
-           send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
-                       PKT_INT, c->remoteid, PKT_INT,
-                       c->localid, PKT_END);
-           logevent("Opened X11 forward channel");
-       }
+       c->u.x11.xconn = x11_init(ssh->x11authtree, c, NULL, -1);
+        c->remoteid = remoteid;
+        c->halfopen = FALSE;
+        c->localid = alloc_channel_id(ssh);
+        c->closes = 0;
+        c->pending_eof = FALSE;
+        c->throttling_conn = 0;
+        c->type = CHAN_X11;    /* identify channel type */
+        add234(ssh->channels, c);
+        send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
+                    PKT_INT, c->remoteid, PKT_INT,
+                    c->localid, PKT_END);
+        logevent("Opened X11 forward channel");
     }
 }
 
@@ -4353,9 +5382,12 @@ static void ssh1_smsg_agent_open(Ssh ssh, struct Packet *pktin)
        c->halfopen = FALSE;
        c->localid = alloc_channel_id(ssh);
        c->closes = 0;
-       c->v.v1.throttling = 0;
+       c->pending_eof = FALSE;
+       c->throttling_conn = 0;
        c->type = CHAN_AGENT;   /* identify channel type */
        c->u.a.lensofar = 0;
+       c->u.a.message = NULL;
+       c->u.a.outstanding_requests = 0;
        add234(ssh->channels, c);
        send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
                    PKT_INT, c->remoteid, PKT_INT, c->localid,
@@ -4367,23 +5399,17 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
 {
     /* Remote side is trying to open a channel to talk to a
      * forwarded port. Give them back a local channel number. */
-    struct ssh_channel *c;
     struct ssh_rportfwd pf, *pfp;
     int remoteid;
     int hostsize, port;
     char *host;
-    const char *e;
-    c = snew(struct ssh_channel);
-    c->ssh = ssh;
+    char *err;
 
     remoteid = ssh_pkt_getuint32(pktin);
     ssh_pkt_getstring(pktin, &host, &hostsize);
     port = ssh_pkt_getuint32(pktin);
 
-    if (hostsize >= lenof(pf.dhost))
-       hostsize = lenof(pf.dhost)-1;
-    memcpy(pf.dhost, host, hostsize);
-    pf.dhost[hostsize] = '\0';
+    pf.dhost = dupprintf("%.*s", hostsize, host);
     pf.dport = port;
     pfp = find234(ssh->rportfwds, &pf, NULL);
 
@@ -4393,12 +5419,16 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
        send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
                    PKT_INT, remoteid, PKT_END);
     } else {
+        struct ssh_channel *c = snew(struct ssh_channel);
+        c->ssh = ssh;
+
        logeventf(ssh, "Received remote port open request for %s:%d",
                  pf.dhost, port);
-       e = pfd_newconnect(&c->u.pfd.s, pf.dhost, port,
-                          c, &ssh->cfg, pfp->pfrec->addressfamily);
-       if (e != NULL) {
-           logeventf(ssh, "Port open failed: %s", e);
+       err = pfd_connect(&c->u.pfd.pf, pf.dhost, port,
+                          c, ssh->conf, pfp->pfrec->addressfamily);
+       if (err != NULL) {
+           logeventf(ssh, "Port open failed: %s", err);
+            sfree(err);
            sfree(c);
            send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
                        PKT_INT, remoteid, PKT_END);
@@ -4407,7 +5437,8 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
            c->halfopen = FALSE;
            c->localid = alloc_channel_id(ssh);
            c->closes = 0;
-           c->v.v1.throttling = 0;
+           c->pending_eof = FALSE;
+           c->throttling_conn = 0;
            c->type = CHAN_SOCKDATA;    /* identify channel type */
            add234(ssh->channels, c);
            send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
@@ -4416,6 +5447,8 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
            logevent("Forwarded port opened successfully");
        }
     }
+
+    sfree(pf.dhost);
 }
 
 static void ssh1_msg_channel_open_confirmation(Ssh ssh, struct Packet *pktin)
@@ -4429,19 +5462,18 @@ static void ssh1_msg_channel_open_confirmation(Ssh ssh, struct Packet *pktin)
        c->remoteid = localid;
        c->halfopen = FALSE;
        c->type = CHAN_SOCKDATA;
-       c->v.v1.throttling = 0;
-       pfd_confirm(c->u.pfd.s);
+       c->throttling_conn = 0;
+       pfd_confirm(c->u.pfd.pf);
     }
 
-    if (c && c->closes) {
+    if (c && c->pending_eof) {
        /*
         * We have a pending close on this channel,
         * which we decided on before the server acked
         * the channel open. So now we know the
         * remoteid, we can close it again.
         */
-       send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE,
-                   PKT_INT, c->remoteid, PKT_END);
+        ssh_channel_try_eof(c);
     }
 }
 
@@ -4453,7 +5485,7 @@ static void ssh1_msg_channel_open_failure(Ssh ssh, struct Packet *pktin)
     c = find234(ssh->channels, &remoteid, ssh_channelfind);
     if (c && c->type == CHAN_SOCKDATA_DORMANT) {
        logevent("Forwarded connection refused by server");
-       pfd_close(c->u.pfd.s);
+       pfd_close(c->u.pfd.pf);
        del234(ssh->channels, c);
        sfree(c);
     }
@@ -4466,34 +5498,62 @@ static void ssh1_msg_channel_close(Ssh ssh, struct Packet *pktin)
     struct ssh_channel *c;
     c = find234(ssh->channels, &i, ssh_channelfind);
     if (c && !c->halfopen) {
-       int closetype;
-       closetype =
-           (pktin->type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2);
-
-       if ((c->closes == 0) && (c->type == CHAN_X11)) {
-           logevent("Forwarded X11 connection terminated");
-           assert(c->u.x11.s != NULL);
-           x11_close(c->u.x11.s);
-           c->u.x11.s = NULL;
-       }
-       if ((c->closes == 0) && (c->type == CHAN_SOCKDATA)) {
-           logevent("Forwarded port closed");
-           assert(c->u.pfd.s != NULL);
-           pfd_close(c->u.pfd.s);
-           c->u.pfd.s = NULL;
-       }
 
-       c->closes |= (closetype << 2);   /* seen this message */
-       if (!(c->closes & closetype)) {
-           send_packet(ssh, pktin->type, PKT_INT, c->remoteid,
-                       PKT_END);
-           c->closes |= closetype;      /* sent it too */
-       }
+        if (pktin->type == SSH1_MSG_CHANNEL_CLOSE &&
+            !(c->closes & CLOSES_RCVD_EOF)) {
+            /*
+             * Received CHANNEL_CLOSE, which we translate into
+             * outgoing EOF.
+             */
+            int send_close = FALSE;
 
-       if (c->closes == 15) {
-           del234(ssh->channels, c);
-           sfree(c);
-       }
+            c->closes |= CLOSES_RCVD_EOF;
+
+            switch (c->type) {
+              case CHAN_X11:
+                if (c->u.x11.xconn)
+                    x11_send_eof(c->u.x11.xconn);
+                else
+                    send_close = TRUE;
+               break;
+              case CHAN_SOCKDATA:
+                if (c->u.pfd.pf)
+                    pfd_send_eof(c->u.pfd.pf);
+                else
+                    send_close = TRUE;
+               break;
+              case CHAN_AGENT:
+                send_close = TRUE;
+               break;
+            }
+
+            if (send_close && !(c->closes & CLOSES_SENT_EOF)) {
+                send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
+                            PKT_END);
+                c->closes |= CLOSES_SENT_EOF;
+            }
+        }
+
+        if (pktin->type == SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION &&
+            !(c->closes & CLOSES_RCVD_CLOSE)) {
+
+            if (!(c->closes & CLOSES_SENT_EOF)) {
+                bombout(("Received CHANNEL_CLOSE_CONFIRMATION for channel %d"
+                         " for which we never sent CHANNEL_CLOSE\n", i));
+            }
+
+            c->closes |= CLOSES_RCVD_CLOSE;
+        }
+
+        if (!((CLOSES_SENT_EOF | CLOSES_RCVD_EOF) & ~c->closes) &&
+            !(c->closes & CLOSES_SENT_CLOSE)) {
+            send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION,
+                        PKT_INT, c->remoteid, PKT_END);
+            c->closes |= CLOSES_SENT_CLOSE;
+        }
+
+       if (!((CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE) & ~c->closes))
+            ssh_channel_destroy(c);
     } else {
        bombout(("Received CHANNEL_CLOSE%s for %s channel %d\n",
                 pktin->type == SSH1_MSG_CHANNEL_CLOSE ? "" :
@@ -4517,16 +5577,16 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
        int bufsize = 0;
        switch (c->type) {
          case CHAN_X11:
-           bufsize = x11_send(c->u.x11.s, p, len);
+           bufsize = x11_send(c->u.x11.xconn, p, len);
            break;
          case CHAN_SOCKDATA:
-           bufsize = pfd_send(c->u.pfd.s, p, len);
+           bufsize = pfd_send(c->u.pfd.pf, p, len);
            break;
          case CHAN_AGENT:
            /* Data for an agent message. Buffer it. */
            while (len > 0) {
                if (c->u.a.lensofar < 4) {
-                   unsigned int l = min(4 - c->u.a.lensofar, len);
+                   unsigned int l = min(4 - c->u.a.lensofar, (unsigned)len);
                    memcpy(c->u.a.msglen + c->u.a.lensofar, p,
                           l);
                    p += l;
@@ -4543,7 +5603,7 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
                if (c->u.a.lensofar >= 4 && len > 0) {
                    unsigned int l =
                        min(c->u.a.totallen - c->u.a.lensofar,
-                           len);
+                           (unsigned)len);
                    memcpy(c->u.a.message + c->u.a.lensofar, p,
                           l);
                    p += l;
@@ -4553,6 +5613,7 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
                if (c->u.a.lensofar == c->u.a.totallen) {
                    void *reply;
                    int replylen;
+                    c->u.a.outstanding_requests++;
                    if (agent_query(c->u.a.message,
                                    c->u.a.totallen,
                                    &reply, &replylen,
@@ -4565,9 +5626,9 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
            bufsize = 0;   /* agent channels never back up */
            break;
        }
-       if (!c->v.v1.throttling && bufsize > SSH1_BUFFER_LIMIT) {
-           c->v.v1.throttling = 1;
-           ssh1_throttle(ssh, +1);
+       if (!c->throttling_conn && bufsize > SSH1_BUFFER_LIMIT) {
+           c->throttling_conn = 1;
+           ssh_throttle_conn(ssh, +1);
        }
     }
 }
@@ -4607,6 +5668,10 @@ static void ssh1_send_ttymode(void *data, char *mode, char *val)
     ssh2_pkt_addbyte(pktout, arg);
 }
 
+int ssh_agent_forwarding_permitted(Ssh ssh)
+{
+    return conf_get_int(ssh->conf, CONF_agentfwd) && agent_exists();
+}
 
 static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
                               struct Packet *pktin)
@@ -4627,7 +5692,7 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
     ssh->packet_dispatch[SSH1_MSG_CHANNEL_DATA] = ssh1_msg_channel_data;
     ssh->packet_dispatch[SSH1_SMSG_EXIT_STATUS] = ssh1_smsg_exit_status;
 
-    if (ssh->cfg.agentfwd && agent_exists()) {
+    if (ssh_agent_forwarding_permitted(ssh)) {
        logevent("Requesting agent forwarding");
        send_packet(ssh, SSH1_CMSG_AGENT_REQUEST_FORWARDING, PKT_END);
        do {
@@ -4646,64 +5711,66 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
        }
     }
 
-    if (ssh->cfg.x11_forward) {
-       char proto[20], data[64];
-       logevent("Requesting X11 forwarding");
-       ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
-                                      data, sizeof(data), ssh->cfg.x11_auth);
-        x11_get_real_auth(ssh->x11auth, ssh->cfg.x11_display);
-       /*
-        * Note that while we blank the X authentication data here, we don't
-        * take any special action to blank the start of an X11 channel,
-        * so using MIT-MAGIC-COOKIE-1 and actually opening an X connection
-        * without having session blanking enabled is likely to leak your
-        * cookie into the log.
-        */
-       if (ssh->v1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
-           send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
-                       PKT_STR, proto,
-                       PKTT_PASSWORD, PKT_STR, data, PKTT_OTHER,
-                       PKT_INT, x11_get_screen_number(ssh->cfg.x11_display),
-                       PKT_END);
-       } else {
-           send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
-                       PKT_STR, proto,
-                       PKTT_PASSWORD, PKT_STR, data, PKTT_OTHER, PKT_END);
-       }
-       do {
-           crReturnV;
-       } while (!pktin);
-       if (pktin->type != SSH1_SMSG_SUCCESS
-           && pktin->type != SSH1_SMSG_FAILURE) {
-           bombout(("Protocol confusion"));
-           crStopV;
-       } else if (pktin->type == SSH1_SMSG_FAILURE) {
-           logevent("X11 forwarding refused");
-       } else {
-           logevent("X11 forwarding enabled");
-           ssh->X11_fwd_enabled = TRUE;
-           ssh->packet_dispatch[SSH1_SMSG_X11_OPEN] = ssh1_smsg_x11_open;
-       }
+    if (conf_get_int(ssh->conf, CONF_x11_forward)) {
+        ssh->x11disp =
+            x11_setup_display(conf_get_str(ssh->conf, CONF_x11_display),
+                              ssh->conf);
+        if (!ssh->x11disp) {
+            /* FIXME: return an error message from x11_setup_display */
+            logevent("X11 forwarding not enabled: unable to"
+                     " initialise X display");
+        } else {
+            ssh->x11auth = x11_invent_fake_auth
+                (ssh->x11authtree, conf_get_int(ssh->conf, CONF_x11_auth));
+            ssh->x11auth->disp = ssh->x11disp;
+
+            logevent("Requesting X11 forwarding");
+            if (ssh->v1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
+                send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
+                            PKT_STR, ssh->x11auth->protoname,
+                            PKT_STR, ssh->x11auth->datastring,
+                            PKT_INT, ssh->x11disp->screennum,
+                            PKT_END);
+            } else {
+                send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
+                            PKT_STR, ssh->x11auth->protoname,
+                            PKT_STR, ssh->x11auth->datastring,
+                            PKT_END);
+            }
+            do {
+                crReturnV;
+            } while (!pktin);
+            if (pktin->type != SSH1_SMSG_SUCCESS
+                && pktin->type != SSH1_SMSG_FAILURE) {
+                bombout(("Protocol confusion"));
+                crStopV;
+            } else if (pktin->type == SSH1_SMSG_FAILURE) {
+                logevent("X11 forwarding refused");
+            } else {
+                logevent("X11 forwarding enabled");
+                ssh->X11_fwd_enabled = TRUE;
+                ssh->packet_dispatch[SSH1_SMSG_X11_OPEN] = ssh1_smsg_x11_open;
+            }
+        }
     }
 
-    ssh_setup_portfwd(ssh, &ssh->cfg);
+    ssh_setup_portfwd(ssh, ssh->conf);
     ssh->packet_dispatch[SSH1_MSG_PORT_OPEN] = ssh1_msg_port_open;
 
-    if (!ssh->cfg.nopty) {
+    if (!conf_get_int(ssh->conf, CONF_nopty)) {
        struct Packet *pkt;
        /* Unpick the terminal-speed string. */
        /* XXX perhaps we should allow no speeds to be sent. */
        ssh->ospeed = 38400; ssh->ispeed = 38400; /* last-resort defaults */
-       sscanf(ssh->cfg.termspeed, "%d,%d", &ssh->ospeed, &ssh->ispeed);
+       sscanf(conf_get_str(ssh->conf, CONF_termspeed), "%d,%d", &ssh->ospeed, &ssh->ispeed);
        /* Send the pty request. */
        pkt = ssh1_pkt_init(SSH1_CMSG_REQUEST_PTY);
-       ssh_pkt_addstring(pkt, ssh->cfg.termtype);
+       ssh_pkt_addstring(pkt, conf_get_str(ssh->conf, CONF_termtype));
        ssh_pkt_adduint32(pkt, ssh->term_height);
        ssh_pkt_adduint32(pkt, ssh->term_width);
        ssh_pkt_adduint32(pkt, 0); /* width in pixels */
        ssh_pkt_adduint32(pkt, 0); /* height in pixels */
-       parse_ttymodes(ssh, ssh->cfg.ttymodes,
-                      ssh1_send_ttymode, (void *)pkt);
+       parse_ttymodes(ssh, ssh1_send_ttymode, (void *)pkt);
        ssh_pkt_addbyte(pkt, SSH1_TTY_OP_ISPEED);
        ssh_pkt_adduint32(pkt, ssh->ispeed);
        ssh_pkt_addbyte(pkt, SSH1_TTY_OP_OSPEED);
@@ -4721,14 +5788,16 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
        } else if (pktin->type == SSH1_SMSG_FAILURE) {
            c_write_str(ssh, "Server refused to allocate pty\r\n");
            ssh->editing = ssh->echoing = 1;
-       }
-       logeventf(ssh, "Allocated pty (ospeed %dbps, ispeed %dbps)",
-                 ssh->ospeed, ssh->ispeed);
+       } else {
+            logeventf(ssh, "Allocated pty (ospeed %dbps, ispeed %dbps)",
+                      ssh->ospeed, ssh->ispeed);
+            ssh->got_pty = TRUE;
+        }
     } else {
        ssh->editing = ssh->echoing = 1;
     }
 
-    if (ssh->cfg.compression) {
+    if (conf_get_int(ssh->conf, CONF_compression)) {
        send_packet(ssh, SSH1_CMSG_REQUEST_COMPRESSION, PKT_INT, 6, PKT_END);
        do {
            crReturnV;
@@ -4756,12 +5825,11 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
      * exists, we fall straight back to that.
      */
     {
-       char *cmd = ssh->cfg.remote_cmd_ptr;
-
-       if (!cmd) cmd = ssh->cfg.remote_cmd;
+       char *cmd = conf_get_str(ssh->conf, CONF_remote_cmd);
        
-       if (ssh->cfg.ssh_subsys && ssh->cfg.remote_cmd_ptr2) {
-           cmd = ssh->cfg.remote_cmd_ptr2;
+       if (conf_get_int(ssh->conf, CONF_ssh_subsys) &&
+           conf_get_str(ssh->conf, CONF_remote_cmd2)) {
+           cmd = conf_get_str(ssh->conf, CONF_remote_cmd2);
            ssh->fallback_cmd = TRUE;
        }
        if (*cmd)
@@ -4803,9 +5871,9 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
        } else {
            while (inlen > 0) {
                int len = min(inlen, 512);
-               send_packet(ssh, SSH1_CMSG_STDIN_DATA, PKTT_DATA,
+               send_packet(ssh, SSH1_CMSG_STDIN_DATA,
                            PKT_INT, len, PKT_DATA, in, len,
-                           PKTT_OTHER, PKT_END);
+                            PKT_END);
                in += len;
                inlen -= len;
            }
@@ -4937,39 +6005,45 @@ static int first_in_commasep_string(char *needle, char *haystack, int haylen)
 
 /*
  * SSH-2 key creation method.
+ * (Currently assumes 2 lots of any hash are sufficient to generate
+ * keys/IVs for any cipher/MAC. SSH2_MKKEY_ITERS documents this assumption.)
  */
-static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
-                      unsigned char *sessid, char chr,
+#define SSH2_MKKEY_ITERS (2)
+static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H, char chr,
                       unsigned char *keyspace)
 {
-    SHA_State s;
-    /* First 20 bytes. */
-    SHA_Init(&s);
+    const struct ssh_hash *h = ssh->kex->hash;
+    void *s;
+    /* First hlen bytes. */
+    s = h->init();
     if (!(ssh->remote_bugs & BUG_SSH2_DERIVEKEY))
-       sha_mpint(&s, K);
-    SHA_Bytes(&s, H, 20);
-    SHA_Bytes(&s, &chr, 1);
-    SHA_Bytes(&s, sessid, 20);
-    SHA_Final(&s, keyspace);
-    /* Next 20 bytes. */
-    SHA_Init(&s);
+       hash_mpint(h, s, K);
+    h->bytes(s, H, h->hlen);
+    h->bytes(s, &chr, 1);
+    h->bytes(s, ssh->v2_session_id, ssh->v2_session_id_len);
+    h->final(s, keyspace);
+    /* Next hlen bytes. */
+    s = h->init();
     if (!(ssh->remote_bugs & BUG_SSH2_DERIVEKEY))
-       sha_mpint(&s, K);
-    SHA_Bytes(&s, H, 20);
-    SHA_Bytes(&s, keyspace, 20);
-    SHA_Final(&s, keyspace + 20);
+       hash_mpint(h, s, K);
+    h->bytes(s, H, h->hlen);
+    h->bytes(s, keyspace, h->hlen);
+    h->final(s, keyspace + h->hlen);
 }
 
 /*
  * Handle the SSH-2 transport layer.
  */
-static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
+static void do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                             struct Packet *pktin)
 {
     unsigned char *in = (unsigned char *)vin;
     struct do_ssh2_transport_state {
+       int crLine;
        int nbits, pbits, warn_kex, warn_cscipher, warn_sccipher;
        Bignum p, g, e, f, K;
+       void *our_kexinit;
+       int our_kexinitlen;
        int kex_init_value, kex_reply_value;
        const struct ssh_mac **maclist;
        int nmacs;
@@ -4979,15 +6053,18 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
        const struct ssh_mac *scmac_tobe;
        const struct ssh_compress *cscomp_tobe;
        const struct ssh_compress *sccomp_tobe;
-       char *hostkeydata, *sigdata, *keystr, *fingerprint;
-       int hostkeylen, siglen;
+       char *hostkeydata, *sigdata, *rsakeydata, *keystr, *fingerprint;
+       int hostkeylen, siglen, rsakeylen;
        void *hkey;                    /* actual host key */
-       unsigned char exchange_hash[20];
+       void *rsakey;                  /* for RSA kex */
+       unsigned char exchange_hash[SSH2_KEX_MAX_HASH_LEN];
        int n_preferred_kex;
-       const struct ssh_kex *preferred_kex[KEX_MAX];
+       const struct ssh_kexes *preferred_kex[KEX_MAX];
        int n_preferred_ciphers;
        const struct ssh2_ciphers *preferred_ciphers[CIPHER_MAX];
        const struct ssh_compress *preferred_comp;
+       int userauth_succeeded;     /* for delayed compression */
+       int pending_compression;
        int got_session_id, activated_authconn;
        struct Packet *pktout;
         int dlgret;
@@ -4996,13 +6073,17 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
     };
     crState(do_ssh2_transport_state);
 
-    crBegin(ssh->do_ssh2_transport_crstate);
+    assert(!ssh->bare_connection);
+
+    crBeginState;
 
     s->cscipher_tobe = s->sccipher_tobe = NULL;
     s->csmac_tobe = s->scmac_tobe = NULL;
     s->cscomp_tobe = s->sccomp_tobe = NULL;
 
     s->got_session_id = s->activated_authconn = FALSE;
+    s->userauth_succeeded = FALSE;
+    s->pending_compression = FALSE;
 
     /*
      * Be prepared to work around the buggy MAC problem.
@@ -5013,16 +6094,16 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
        s->maclist = macs, s->nmacs = lenof(macs);
 
   begin_key_exchange:
-    ssh->pkt_ctx &= ~SSH2_PKTCTX_KEX_MASK;
+    ssh->pkt_kctx = SSH2_PKTCTX_NOKEX;
     {
-       int i, j, commalist_started;
+       int i, j, k, commalist_started;
 
        /*
         * Set up the preferred key exchange. (NULL => warn below here)
         */
        s->n_preferred_kex = 0;
        for (i = 0; i < KEX_MAX; i++) {
-           switch (ssh->cfg.ssh_kexlist[i]) {
+           switch (conf_get_int_int(ssh->conf, CONF_ssh_kexlist, i)) {
              case KEX_DHGEX:
                s->preferred_kex[s->n_preferred_kex++] =
                    &ssh_diffiehellman_gex;
@@ -5035,7 +6116,11 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                s->preferred_kex[s->n_preferred_kex++] =
                    &ssh_diffiehellman_group1;
                break;
-             case CIPHER_WARN:
+             case KEX_RSA:
+               s->preferred_kex[s->n_preferred_kex++] =
+                   &ssh_rsa_kex;
+               break;
+             case KEX_WARN:
                /* Flag for later. Don't bother if it's the last in
                 * the list. */
                if (i < KEX_MAX - 1) {
@@ -5050,12 +6135,12 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
         */
        s->n_preferred_ciphers = 0;
        for (i = 0; i < CIPHER_MAX; i++) {
-           switch (ssh->cfg.ssh_cipherlist[i]) {
+           switch (conf_get_int_int(ssh->conf, CONF_ssh_cipherlist, i)) {
              case CIPHER_BLOWFISH:
                s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_blowfish;
                break;
              case CIPHER_DES:
-               if (ssh->cfg.ssh2_des_cbc) {
+               if (conf_get_int(ssh->conf, CONF_ssh2_des_cbc)) {
                    s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_des;
                }
                break;
@@ -5081,7 +6166,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
        /*
         * Set up preferred compression.
         */
-       if (ssh->cfg.compression)
+       if (conf_get_int(ssh->conf, CONF_compression))
            s->preferred_comp = &ssh_zlib;
        else
            s->preferred_comp = &ssh_comp_none;
@@ -5107,80 +6192,88 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
        ssh2_pkt_addstring_start(s->pktout);
        commalist_started = 0;
        for (i = 0; i < s->n_preferred_kex; i++) {
-           const struct ssh_kex *k = s->preferred_kex[i];
+           const struct ssh_kexes *k = s->preferred_kex[i];
            if (!k) continue;          /* warning flag */
-           if (commalist_started)
-               ssh2_pkt_addstring_str(s->pktout, ",");
-           ssh2_pkt_addstring_str(s->pktout, s->preferred_kex[i]->name);
-           commalist_started = 1;
-       }
-       /* List server host key algorithms. */
-       ssh2_pkt_addstring_start(s->pktout);
-       for (i = 0; i < lenof(hostkey_algs); i++) {
-           ssh2_pkt_addstring_str(s->pktout, hostkey_algs[i]->name);
-           if (i < lenof(hostkey_algs) - 1)
-               ssh2_pkt_addstring_str(s->pktout, ",");
-       }
-       /* List client->server encryption algorithms. */
-       ssh2_pkt_addstring_start(s->pktout);
-       commalist_started = 0;
-       for (i = 0; i < s->n_preferred_ciphers; i++) {
-           const struct ssh2_ciphers *c = s->preferred_ciphers[i];
-           if (!c) continue;          /* warning flag */
-           for (j = 0; j < c->nciphers; j++) {
+           for (j = 0; j < k->nkexes; j++) {
                if (commalist_started)
                    ssh2_pkt_addstring_str(s->pktout, ",");
-               ssh2_pkt_addstring_str(s->pktout, c->list[j]->name);
+               ssh2_pkt_addstring_str(s->pktout, k->list[j]->name);
                commalist_started = 1;
            }
        }
-       /* List server->client encryption algorithms. */
-       ssh2_pkt_addstring_start(s->pktout);
-       commalist_started = 0;
-       for (i = 0; i < s->n_preferred_ciphers; i++) {
-           const struct ssh2_ciphers *c = s->preferred_ciphers[i];
-           if (!c) continue; /* warning flag */
-           for (j = 0; j < c->nciphers; j++) {
-               if (commalist_started)
-                   ssh2_pkt_addstring_str(s->pktout, ",");
-               ssh2_pkt_addstring_str(s->pktout, c->list[j]->name);
-               commalist_started = 1;
+       /* List server host key algorithms. */
+        if (!s->got_session_id) {
+            /*
+             * In the first key exchange, we list all the algorithms
+             * we're prepared to cope with.
+             */
+            ssh2_pkt_addstring_start(s->pktout);
+            for (i = 0; i < lenof(hostkey_algs); i++) {
+                ssh2_pkt_addstring_str(s->pktout, hostkey_algs[i]->name);
+                if (i < lenof(hostkey_algs) - 1)
+                    ssh2_pkt_addstring_str(s->pktout, ",");
+            }
+        } else {
+            /*
+             * In subsequent key exchanges, we list only the kex
+             * algorithm that was selected in the first key exchange,
+             * so that we keep getting the same host key and hence
+             * don't have to interrupt the user's session to ask for
+             * reverification.
+             */
+            assert(ssh->kex);
+            ssh2_pkt_addstring(s->pktout, ssh->hostkey->name);
+        }
+       /* List encryption algorithms (client->server then server->client). */
+       for (k = 0; k < 2; k++) {
+           ssh2_pkt_addstring_start(s->pktout);
+           commalist_started = 0;
+           for (i = 0; i < s->n_preferred_ciphers; i++) {
+               const struct ssh2_ciphers *c = s->preferred_ciphers[i];
+               if (!c) continue;              /* warning flag */
+               for (j = 0; j < c->nciphers; j++) {
+                   if (commalist_started)
+                       ssh2_pkt_addstring_str(s->pktout, ",");
+                   ssh2_pkt_addstring_str(s->pktout, c->list[j]->name);
+                   commalist_started = 1;
+               }
            }
        }
-       /* List client->server MAC algorithms. */
-       ssh2_pkt_addstring_start(s->pktout);
-       for (i = 0; i < s->nmacs; i++) {
-           ssh2_pkt_addstring_str(s->pktout, s->maclist[i]->name);
-           if (i < s->nmacs - 1)
-               ssh2_pkt_addstring_str(s->pktout, ",");
-       }
-       /* List server->client MAC algorithms. */
-       ssh2_pkt_addstring_start(s->pktout);
-       for (i = 0; i < s->nmacs; i++) {
-           ssh2_pkt_addstring_str(s->pktout, s->maclist[i]->name);
-           if (i < s->nmacs - 1)
-               ssh2_pkt_addstring_str(s->pktout, ",");
-       }
-       /* List client->server compression algorithms. */
-       ssh2_pkt_addstring_start(s->pktout);
-       assert(lenof(compressions) > 1);
-       ssh2_pkt_addstring_str(s->pktout, s->preferred_comp->name);
-       for (i = 0; i < lenof(compressions); i++) {
-           const struct ssh_compress *c = compressions[i];
-           if (c != s->preferred_comp) {
-               ssh2_pkt_addstring_str(s->pktout, ",");
-               ssh2_pkt_addstring_str(s->pktout, c->name);
+       /* List MAC algorithms (client->server then server->client). */
+       for (j = 0; j < 2; j++) {
+           ssh2_pkt_addstring_start(s->pktout);
+           for (i = 0; i < s->nmacs; i++) {
+               ssh2_pkt_addstring_str(s->pktout, s->maclist[i]->name);
+               if (i < s->nmacs - 1)
+                   ssh2_pkt_addstring_str(s->pktout, ",");
            }
        }
-       /* List server->client compression algorithms. */
-       ssh2_pkt_addstring_start(s->pktout);
-       assert(lenof(compressions) > 1);
-       ssh2_pkt_addstring_str(s->pktout, s->preferred_comp->name);
-       for (i = 0; i < lenof(compressions); i++) {
-           const struct ssh_compress *c = compressions[i];
-           if (c != s->preferred_comp) {
+       /* List client->server compression algorithms,
+        * then server->client compression algorithms. (We use the
+        * same set twice.) */
+       for (j = 0; j < 2; j++) {
+           ssh2_pkt_addstring_start(s->pktout);
+           assert(lenof(compressions) > 1);
+           /* Prefer non-delayed versions */
+           ssh2_pkt_addstring_str(s->pktout, s->preferred_comp->name);
+           /* We don't even list delayed versions of algorithms until
+            * they're allowed to be used, to avoid a race. See the end of
+            * this function. */
+           if (s->userauth_succeeded && s->preferred_comp->delayed_name) {
                ssh2_pkt_addstring_str(s->pktout, ",");
-               ssh2_pkt_addstring_str(s->pktout, c->name);
+               ssh2_pkt_addstring_str(s->pktout,
+                                      s->preferred_comp->delayed_name);
+           }
+           for (i = 0; i < lenof(compressions); i++) {
+               const struct ssh_compress *c = compressions[i];
+               if (c != s->preferred_comp) {
+                   ssh2_pkt_addstring_str(s->pktout, ",");
+                   ssh2_pkt_addstring_str(s->pktout, c->name);
+                   if (s->userauth_succeeded && c->delayed_name) {
+                       ssh2_pkt_addstring_str(s->pktout, ",");
+                       ssh2_pkt_addstring_str(s->pktout, c->delayed_name);
+                   }
+               }
            }
        }
        /* List client->server languages. Empty list. */
@@ -5193,15 +6286,14 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
        ssh2_pkt_adduint32(s->pktout, 0);
     }
 
-    ssh->exhash = ssh->exhashbase;
-    sha_string(&ssh->exhash, s->pktout->data + 5, s->pktout->length - 5);
+    s->our_kexinitlen = s->pktout->length - 5;
+    s->our_kexinit = snewn(s->our_kexinitlen, unsigned char);
+    memcpy(s->our_kexinit, s->pktout->data + 5, s->our_kexinitlen); 
 
     ssh2_pkt_send_noqueue(ssh, s->pktout);
 
     if (!pktin)
-       crWaitUntil(pktin);
-    if (pktin->length > 5)
-       sha_string(&ssh->exhash, pktin->data + 5, pktin->length - 5);
+       crWaitUntilV(pktin);
 
     /*
      * Now examine the other side's KEXINIT to see what we're up
@@ -5213,7 +6305,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 
        if (pktin->type != SSH2_MSG_KEXINIT) {
            bombout(("expected key exchange packet from server"));
-           crStop(0);
+           crStopV;
        }
        ssh->kex = NULL;
        ssh->hostkey = NULL;
@@ -5227,24 +6319,32 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 
        pktin->savedpos += 16;          /* skip garbage cookie */
        ssh_pkt_getstring(pktin, &str, &len);    /* key exchange algorithms */
+        if (!str) {
+            bombout(("KEXINIT packet was incomplete"));
+            crStopV;
+        }
 
        preferred = NULL;
        for (i = 0; i < s->n_preferred_kex; i++) {
-           const struct ssh_kex *k = s->preferred_kex[i];
+           const struct ssh_kexes *k = s->preferred_kex[i];
            if (!k) {
                s->warn_kex = TRUE;
            } else {
-               if (!preferred) preferred = k->name;
-               if (in_commasep_string(k->name, str, len))
-                   ssh->kex = k;
+               for (j = 0; j < k->nkexes; j++) {
+                   if (!preferred) preferred = k->list[j]->name;
+                   if (in_commasep_string(k->list[j]->name, str, len)) {
+                       ssh->kex = k->list[j];
+                       break;
+                   }
+               }
            }
            if (ssh->kex)
                break;
        }
        if (!ssh->kex) {
-           bombout(("Couldn't agree a key exchange algorithm (available: %s)",
-                    str ? str : "(null)"));
-           crStop(0);
+            bombout(("Couldn't agree a key exchange algorithm"
+                     " (available: %.*s)", len, str));
+           crStopV;
        }
        /*
         * Note that the server's guess is considered wrong if it doesn't match
@@ -5253,15 +6353,29 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
         */
        s->guessok = first_in_commasep_string(preferred, str, len);
        ssh_pkt_getstring(pktin, &str, &len);    /* host key algorithms */
+        if (!str) {
+            bombout(("KEXINIT packet was incomplete"));
+            crStopV;
+        }
        for (i = 0; i < lenof(hostkey_algs); i++) {
            if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
                ssh->hostkey = hostkey_algs[i];
                break;
            }
        }
+       if (!ssh->hostkey) {
+            bombout(("Couldn't agree a host key algorithm"
+                     " (available: %.*s)", len, str));
+           crStopV;
+       }
+
        s->guessok = s->guessok &&
            first_in_commasep_string(hostkey_algs[0]->name, str, len);
        ssh_pkt_getstring(pktin, &str, &len);    /* client->server cipher */
+        if (!str) {
+            bombout(("KEXINIT packet was incomplete"));
+            crStopV;
+        }
        for (i = 0; i < s->n_preferred_ciphers; i++) {
            const struct ssh2_ciphers *c = s->preferred_ciphers[i];
            if (!c) {
@@ -5278,12 +6392,16 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                break;
        }
        if (!s->cscipher_tobe) {
-           bombout(("Couldn't agree a client-to-server cipher (available: %s)",
-                    str ? str : "(null)"));
-           crStop(0);
+            bombout(("Couldn't agree a client-to-server cipher"
+                     " (available: %.*s)", len, str));
+           crStopV;
        }
 
        ssh_pkt_getstring(pktin, &str, &len);    /* server->client cipher */
+        if (!str) {
+            bombout(("KEXINIT packet was incomplete"));
+            crStopV;
+        }
        for (i = 0; i < s->n_preferred_ciphers; i++) {
            const struct ssh2_ciphers *c = s->preferred_ciphers[i];
            if (!c) {
@@ -5300,12 +6418,16 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                break;
        }
        if (!s->sccipher_tobe) {
-           bombout(("Couldn't agree a server-to-client cipher (available: %s)",
-                    str ? str : "(null)"));
-           crStop(0);
+            bombout(("Couldn't agree a server-to-client cipher"
+                     " (available: %.*s)", len, str));
+           crStopV;
        }
 
        ssh_pkt_getstring(pktin, &str, &len);    /* client->server mac */
+        if (!str) {
+            bombout(("KEXINIT packet was incomplete"));
+            crStopV;
+        }
        for (i = 0; i < s->nmacs; i++) {
            if (in_commasep_string(s->maclist[i]->name, str, len)) {
                s->csmac_tobe = s->maclist[i];
@@ -5313,6 +6435,10 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
            }
        }
        ssh_pkt_getstring(pktin, &str, &len);    /* server->client mac */
+        if (!str) {
+            bombout(("KEXINIT packet was incomplete"));
+            crStopV;
+        }
        for (i = 0; i < s->nmacs; i++) {
            if (in_commasep_string(s->maclist[i]->name, str, len)) {
                s->scmac_tobe = s->maclist[i];
@@ -5320,27 +6446,63 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
            }
        }
        ssh_pkt_getstring(pktin, &str, &len);  /* client->server compression */
+        if (!str) {
+            bombout(("KEXINIT packet was incomplete"));
+            crStopV;
+        }
        for (i = 0; i < lenof(compressions) + 1; i++) {
            const struct ssh_compress *c =
                i == 0 ? s->preferred_comp : compressions[i - 1];
            if (in_commasep_string(c->name, str, len)) {
                s->cscomp_tobe = c;
                break;
+           } else if (in_commasep_string(c->delayed_name, str, len)) {
+               if (s->userauth_succeeded) {
+                   s->cscomp_tobe = c;
+                   break;
+               } else {
+                   s->pending_compression = TRUE;  /* try this later */
+               }
            }
        }
        ssh_pkt_getstring(pktin, &str, &len);  /* server->client compression */
+        if (!str) {
+            bombout(("KEXINIT packet was incomplete"));
+            crStopV;
+        }
        for (i = 0; i < lenof(compressions) + 1; i++) {
            const struct ssh_compress *c =
                i == 0 ? s->preferred_comp : compressions[i - 1];
            if (in_commasep_string(c->name, str, len)) {
                s->sccomp_tobe = c;
                break;
+           } else if (in_commasep_string(c->delayed_name, str, len)) {
+               if (s->userauth_succeeded) {
+                   s->sccomp_tobe = c;
+                   break;
+               } else {
+                   s->pending_compression = TRUE;  /* try this later */
+               }
            }
        }
+       if (s->pending_compression) {
+           logevent("Server supports delayed compression; "
+                    "will try this later");
+       }
        ssh_pkt_getstring(pktin, &str, &len);  /* client->server language */
        ssh_pkt_getstring(pktin, &str, &len);  /* server->client language */
        s->ignorepkt = ssh2_pkt_getbool(pktin) && !s->guessok;
 
+       ssh->exhash = ssh->kex->hash->init();
+       hash_string(ssh->kex->hash, ssh->exhash, ssh->v_c, strlen(ssh->v_c));
+       hash_string(ssh->kex->hash, ssh->exhash, ssh->v_s, strlen(ssh->v_s));
+       hash_string(ssh->kex->hash, ssh->exhash,
+           s->our_kexinit, s->our_kexinitlen);
+       sfree(s->our_kexinit);
+        /* Include the type byte in the hash of server's KEXINIT */
+        hash_string(ssh->kex->hash, ssh->exhash,
+                    pktin->body - 1, pktin->length + 1);
+
        if (s->warn_kex) {
            ssh_set_frozen(ssh, 1);
            s->dlgret = askalg(ssh->frontend, "key-exchange algorithm",
@@ -5348,11 +6510,11 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                               ssh_dialog_callback, ssh);
            if (s->dlgret < 0) {
                do {
-                   crReturn(0);
+                   crReturnV;
                    if (pktin) {
                        bombout(("Unexpected data from server while"
                                 " waiting for user response"));
-                       crStop(0);
+                       crStopV;
                    }
                } while (pktin || inlen > 0);
                s->dlgret = ssh->user_response;
@@ -5361,7 +6523,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
            if (s->dlgret == 0) {
                ssh_disconnect(ssh, "User aborted at kex warning", NULL,
                               0, TRUE);
-               crStop(0);
+               crStopV;
            }
        }
 
@@ -5373,11 +6535,11 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                               ssh_dialog_callback, ssh);
            if (s->dlgret < 0) {
                do {
-                   crReturn(0);
+                   crReturnV;
                    if (pktin) {
                        bombout(("Unexpected data from server while"
                                 " waiting for user response"));
-                       crStop(0);
+                       crStopV;
                    }
                } while (pktin || inlen > 0);
                s->dlgret = ssh->user_response;
@@ -5386,7 +6548,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
            if (s->dlgret == 0) {
                ssh_disconnect(ssh, "User aborted at cipher warning", NULL,
                               0, TRUE);
-               crStop(0);
+               crStopV;
            }
        }
 
@@ -5398,11 +6560,11 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                               ssh_dialog_callback, ssh);
            if (s->dlgret < 0) {
                do {
-                   crReturn(0);
+                   crReturnV;
                    if (pktin) {
                        bombout(("Unexpected data from server while"
                                 " waiting for user response"));
-                       crStop(0);
+                       crStopV;
                    }
                } while (pktin || inlen > 0);
                s->dlgret = ssh->user_response;
@@ -5411,163 +6573,341 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
            if (s->dlgret == 0) {
                ssh_disconnect(ssh, "User aborted at cipher warning", NULL,
                               0, TRUE);
-               crStop(0);
+               crStopV;
            }
        }
 
        if (s->ignorepkt) /* first_kex_packet_follows */
-           crWaitUntil(pktin);                /* Ignore packet */
+           crWaitUntilV(pktin);                /* Ignore packet */
     }
 
-    /*
-     * Work out the number of bits of key we will need from the key
-     * exchange. We start with the maximum key length of either
-     * cipher...
-     */
-    {
-       int csbits, scbits;
+    if (ssh->kex->main_type == KEXTYPE_DH) {
+        /*
+         * Work out the number of bits of key we will need from the
+         * key exchange. We start with the maximum key length of
+         * either cipher...
+         */
+        {
+            int csbits, scbits;
 
-       csbits = s->cscipher_tobe->keylen;
-       scbits = s->sccipher_tobe->keylen;
-       s->nbits = (csbits > scbits ? csbits : scbits);
-    }
-    /* The keys only have 160-bit entropy, since they're based on
-     * a SHA-1 hash. So cap the key size at 160 bits. */
-    if (s->nbits > 160)
-       s->nbits = 160;
+            csbits = s->cscipher_tobe->keylen;
+            scbits = s->sccipher_tobe->keylen;
+            s->nbits = (csbits > scbits ? csbits : scbits);
+        }
+        /* The keys only have hlen-bit entropy, since they're based on
+         * a hash. So cap the key size at hlen bits. */
+        if (s->nbits > ssh->kex->hash->hlen * 8)
+            s->nbits = ssh->kex->hash->hlen * 8;
 
-    /*
-     * If we're doing Diffie-Hellman group exchange, start by
-     * requesting a group.
-     */
-    if (!ssh->kex->pdata) {
-       logevent("Doing Diffie-Hellman group exchange");
-       ssh->pkt_ctx |= SSH2_PKTCTX_DHGEX;
-       /*
-        * Work out how big a DH group we will need to allow that
-        * much data.
-        */
-       s->pbits = 512 << ((s->nbits - 1) / 64);
-       s->pktout = ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, s->pbits);
-       ssh2_pkt_send_noqueue(ssh, s->pktout);
+        /*
+         * If we're doing Diffie-Hellman group exchange, start by
+         * requesting a group.
+         */
+        if (!ssh->kex->pdata) {
+            logevent("Doing Diffie-Hellman group exchange");
+            ssh->pkt_kctx = SSH2_PKTCTX_DHGEX;
+            /*
+             * Work out how big a DH group we will need to allow that
+             * much data.
+             */
+            s->pbits = 512 << ((s->nbits - 1) / 64);
+            if (s->pbits < DH_MIN_SIZE)
+                s->pbits = DH_MIN_SIZE;
+            if (s->pbits > DH_MAX_SIZE)
+                s->pbits = DH_MAX_SIZE;
+            if ((ssh->remote_bugs & BUG_SSH2_OLDGEX)) {
+                s->pktout = ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
+                ssh2_pkt_adduint32(s->pktout, s->pbits);
+            } else {
+                s->pktout = ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST);
+                ssh2_pkt_adduint32(s->pktout, DH_MIN_SIZE);
+                ssh2_pkt_adduint32(s->pktout, s->pbits);
+                ssh2_pkt_adduint32(s->pktout, DH_MAX_SIZE);
+            }
+            ssh2_pkt_send_noqueue(ssh, s->pktout);
 
-       crWaitUntil(pktin);
-       if (pktin->type != SSH2_MSG_KEX_DH_GEX_GROUP) {
-           bombout(("expected key exchange group packet from server"));
-           crStop(0);
-       }
-       s->p = ssh2_pkt_getmp(pktin);
-       s->g = ssh2_pkt_getmp(pktin);
-       if (!s->p || !s->g) {
-           bombout(("unable to read mp-ints from incoming group packet"));
-           crStop(0);
-       }
-       ssh->kex_ctx = dh_setup_gex(s->p, s->g);
-       s->kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
-       s->kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
+            crWaitUntilV(pktin);
+            if (pktin->type != SSH2_MSG_KEX_DH_GEX_GROUP) {
+                bombout(("expected key exchange group packet from server"));
+                crStopV;
+            }
+            s->p = ssh2_pkt_getmp(pktin);
+            s->g = ssh2_pkt_getmp(pktin);
+            if (!s->p || !s->g) {
+                bombout(("unable to read mp-ints from incoming group packet"));
+                crStopV;
+            }
+            ssh->kex_ctx = dh_setup_gex(s->p, s->g);
+            s->kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
+            s->kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
+        } else {
+            ssh->pkt_kctx = SSH2_PKTCTX_DHGROUP;
+            ssh->kex_ctx = dh_setup_group(ssh->kex);
+            s->kex_init_value = SSH2_MSG_KEXDH_INIT;
+            s->kex_reply_value = SSH2_MSG_KEXDH_REPLY;
+            logeventf(ssh, "Using Diffie-Hellman with standard group \"%s\"",
+                      ssh->kex->groupname);
+        }
+
+        logeventf(ssh, "Doing Diffie-Hellman key exchange with hash %s",
+                  ssh->kex->hash->text_name);
+        /*
+         * Now generate and send e for Diffie-Hellman.
+         */
+        set_busy_status(ssh->frontend, BUSY_CPU); /* this can take a while */
+        s->e = dh_create_e(ssh->kex_ctx, s->nbits * 2);
+        s->pktout = ssh2_pkt_init(s->kex_init_value);
+        ssh2_pkt_addmp(s->pktout, s->e);
+        ssh2_pkt_send_noqueue(ssh, s->pktout);
+
+        set_busy_status(ssh->frontend, BUSY_WAITING); /* wait for server */
+        crWaitUntilV(pktin);
+        if (pktin->type != s->kex_reply_value) {
+            bombout(("expected key exchange reply packet from server"));
+            crStopV;
+        }
+        set_busy_status(ssh->frontend, BUSY_CPU); /* cogitate */
+        ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
+        if (!s->hostkeydata) {
+            bombout(("unable to parse key exchange reply packet"));
+            crStopV;
+        }
+        s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
+        s->f = ssh2_pkt_getmp(pktin);
+        if (!s->f) {
+            bombout(("unable to parse key exchange reply packet"));
+            crStopV;
+        }
+        ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
+        if (!s->sigdata) {
+            bombout(("unable to parse key exchange reply packet"));
+            crStopV;
+        }
+
+        {
+            const char *err = dh_validate_f(ssh->kex_ctx, s->f);
+            if (err) {
+                bombout(("key exchange reply failed validation: %s", err));
+                crStopV;
+            }
+        }
+        s->K = dh_find_K(ssh->kex_ctx, s->f);
+
+        /* We assume everything from now on will be quick, and it might
+         * involve user interaction. */
+        set_busy_status(ssh->frontend, BUSY_NOT);
+
+        hash_string(ssh->kex->hash, ssh->exhash, s->hostkeydata, s->hostkeylen);
+        if (!ssh->kex->pdata) {
+            if (!(ssh->remote_bugs & BUG_SSH2_OLDGEX))
+                hash_uint32(ssh->kex->hash, ssh->exhash, DH_MIN_SIZE);
+            hash_uint32(ssh->kex->hash, ssh->exhash, s->pbits);
+            if (!(ssh->remote_bugs & BUG_SSH2_OLDGEX))
+                hash_uint32(ssh->kex->hash, ssh->exhash, DH_MAX_SIZE);
+            hash_mpint(ssh->kex->hash, ssh->exhash, s->p);
+            hash_mpint(ssh->kex->hash, ssh->exhash, s->g);
+        }
+        hash_mpint(ssh->kex->hash, ssh->exhash, s->e);
+        hash_mpint(ssh->kex->hash, ssh->exhash, s->f);
+
+        dh_cleanup(ssh->kex_ctx);
+        freebn(s->f);
+        if (!ssh->kex->pdata) {
+            freebn(s->g);
+            freebn(s->p);
+        }
     } else {
-       ssh->pkt_ctx |= SSH2_PKTCTX_DHGROUP;
-       ssh->kex_ctx = dh_setup_group(ssh->kex);
-       s->kex_init_value = SSH2_MSG_KEXDH_INIT;
-       s->kex_reply_value = SSH2_MSG_KEXDH_REPLY;
-       logeventf(ssh, "Using Diffie-Hellman with standard group \"%s\"",
-                 ssh->kex->groupname);
-    }
+       logeventf(ssh, "Doing RSA key exchange with hash %s",
+                 ssh->kex->hash->text_name);
+       ssh->pkt_kctx = SSH2_PKTCTX_RSAKEX;
+        /*
+         * RSA key exchange. First expect a KEXRSA_PUBKEY packet
+         * from the server.
+         */
+        crWaitUntilV(pktin);
+        if (pktin->type != SSH2_MSG_KEXRSA_PUBKEY) {
+            bombout(("expected RSA public key packet from server"));
+            crStopV;
+        }
 
-    logevent("Doing Diffie-Hellman key exchange");
-    /*
-     * Now generate and send e for Diffie-Hellman.
-     */
-    set_busy_status(ssh->frontend, BUSY_CPU); /* this can take a while */
-    s->e = dh_create_e(ssh->kex_ctx, s->nbits * 2);
-    s->pktout = ssh2_pkt_init(s->kex_init_value);
-    ssh2_pkt_addmp(s->pktout, s->e);
-    ssh2_pkt_send_noqueue(ssh, s->pktout);
+        ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
+        if (!s->hostkeydata) {
+            bombout(("unable to parse RSA public key packet"));
+            crStopV;
+        }
+        hash_string(ssh->kex->hash, ssh->exhash,
+                   s->hostkeydata, s->hostkeylen);
+       s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
+
+        {
+            char *keydata;
+            ssh_pkt_getstring(pktin, &keydata, &s->rsakeylen);
+            if (!keydata) {
+                bombout(("unable to parse RSA public key packet"));
+                crStopV;
+            }
+            s->rsakeydata = snewn(s->rsakeylen, char);
+            memcpy(s->rsakeydata, keydata, s->rsakeylen);
+        }
 
-    set_busy_status(ssh->frontend, BUSY_WAITING); /* wait for server */
-    crWaitUntil(pktin);
-    if (pktin->type != s->kex_reply_value) {
-       bombout(("expected key exchange reply packet from server"));
-       crStop(0);
-    }
-    set_busy_status(ssh->frontend, BUSY_CPU); /* cogitate */
-    ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
-    s->f = ssh2_pkt_getmp(pktin);
-    if (!s->f) {
-       bombout(("unable to parse key exchange reply packet"));
-       crStop(0);
-    }
-    ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
+        s->rsakey = ssh_rsakex_newkey(s->rsakeydata, s->rsakeylen);
+        if (!s->rsakey) {
+            sfree(s->rsakeydata);
+            bombout(("unable to parse RSA public key from server"));
+            crStopV;
+        }
+
+        hash_string(ssh->kex->hash, ssh->exhash, s->rsakeydata, s->rsakeylen);
+
+        /*
+         * Next, set up a shared secret K, of precisely KLEN -
+         * 2*HLEN - 49 bits, where KLEN is the bit length of the
+         * RSA key modulus and HLEN is the bit length of the hash
+         * we're using.
+         */
+        {
+            int klen = ssh_rsakex_klen(s->rsakey);
+            int nbits = klen - (2*ssh->kex->hash->hlen*8 + 49);
+            int i, byte = 0;
+            unsigned char *kstr1, *kstr2, *outstr;
+            int kstr1len, kstr2len, outstrlen;
+
+            s->K = bn_power_2(nbits - 1);
+
+            for (i = 0; i < nbits; i++) {
+                if ((i & 7) == 0) {
+                    byte = random_byte();
+                }
+                bignum_set_bit(s->K, i, (byte >> (i & 7)) & 1);
+            }
+
+            /*
+             * Encode this as an mpint.
+             */
+            kstr1 = ssh2_mpint_fmt(s->K, &kstr1len);
+            kstr2 = snewn(kstr2len = 4 + kstr1len, unsigned char);
+            PUT_32BIT(kstr2, kstr1len);
+            memcpy(kstr2 + 4, kstr1, kstr1len);
+
+            /*
+             * Encrypt it with the given RSA key.
+             */
+            outstrlen = (klen + 7) / 8;
+            outstr = snewn(outstrlen, unsigned char);
+            ssh_rsakex_encrypt(ssh->kex->hash, kstr2, kstr2len,
+                              outstr, outstrlen, s->rsakey);
+
+            /*
+             * And send it off in a return packet.
+             */
+            s->pktout = ssh2_pkt_init(SSH2_MSG_KEXRSA_SECRET);
+            ssh2_pkt_addstring_start(s->pktout);
+            ssh2_pkt_addstring_data(s->pktout, (char *)outstr, outstrlen);
+            ssh2_pkt_send_noqueue(ssh, s->pktout);
+
+           hash_string(ssh->kex->hash, ssh->exhash, outstr, outstrlen);
+
+            sfree(kstr2);
+            sfree(kstr1);
+            sfree(outstr);
+        }
 
-    s->K = dh_find_K(ssh->kex_ctx, s->f);
+        ssh_rsakex_freekey(s->rsakey);
 
-    /* We assume everything from now on will be quick, and it might
-     * involve user interaction. */
-    set_busy_status(ssh->frontend, BUSY_NOT);
+        crWaitUntilV(pktin);
+        if (pktin->type != SSH2_MSG_KEXRSA_DONE) {
+            sfree(s->rsakeydata);
+            bombout(("expected signature packet from server"));
+            crStopV;
+        }
+
+        ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
+        if (!s->sigdata) {
+            bombout(("unable to parse signature packet"));
+            crStopV;
+        }
 
-    sha_string(&ssh->exhash, s->hostkeydata, s->hostkeylen);
-    if (ssh->kex == &ssh_diffiehellman_gex) {
-       sha_uint32(&ssh->exhash, s->pbits);
-       sha_mpint(&ssh->exhash, s->p);
-       sha_mpint(&ssh->exhash, s->g);
+        sfree(s->rsakeydata);
     }
-    sha_mpint(&ssh->exhash, s->e);
-    sha_mpint(&ssh->exhash, s->f);
-    sha_mpint(&ssh->exhash, s->K);
-    SHA_Final(&ssh->exhash, s->exchange_hash);
 
-    dh_cleanup(ssh->kex_ctx);
+    hash_mpint(ssh->kex->hash, ssh->exhash, s->K);
+    assert(ssh->kex->hash->hlen <= sizeof(s->exchange_hash));
+    ssh->kex->hash->final(ssh->exhash, s->exchange_hash);
+
     ssh->kex_ctx = NULL;
 
 #if 0
     debug(("Exchange hash is:\n"));
-    dmemdump(s->exchange_hash, 20);
+    dmemdump(s->exchange_hash, ssh->kex->hash->hlen);
 #endif
 
-    s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
     if (!s->hkey ||
        !ssh->hostkey->verifysig(s->hkey, s->sigdata, s->siglen,
-                                (char *)s->exchange_hash, 20)) {
+                                (char *)s->exchange_hash,
+                                ssh->kex->hash->hlen)) {
        bombout(("Server's host key did not match the signature supplied"));
-       crStop(0);
+       crStopV;
     }
 
-    /*
-     * Authenticate remote host: verify host key. (We've already
-     * checked the signature of the exchange hash.)
-     */
     s->keystr = ssh->hostkey->fmtkey(s->hkey);
-    s->fingerprint = ssh->hostkey->fingerprint(s->hkey);
-    ssh_set_frozen(ssh, 1);
-    s->dlgret = verify_ssh_host_key(ssh->frontend,
-                                    ssh->savedhost, ssh->savedport,
-                                    ssh->hostkey->keytype, s->keystr,
-                                   s->fingerprint,
-                                    ssh_dialog_callback, ssh);
-    if (s->dlgret < 0) {
-        do {
-            crReturn(0);
-            if (pktin) {
-                bombout(("Unexpected data from server while waiting"
-                         " for user host key response"));
-                    crStop(0);
+    if (!s->got_session_id) {
+        /*
+         * Authenticate remote host: verify host key. (We've already
+         * checked the signature of the exchange hash.)
+         */
+        s->fingerprint = ssh->hostkey->fingerprint(s->hkey);
+        logevent("Host key fingerprint is:");
+        logevent(s->fingerprint);
+        /* First check against manually configured host keys. */
+        s->dlgret = verify_ssh_manual_host_key(ssh, s->fingerprint,
+                                               ssh->hostkey, s->hkey);
+        if (s->dlgret == 0) {          /* did not match */
+            bombout(("Host key did not appear in manually configured list"));
+            crStopV;
+        } else if (s->dlgret < 0) { /* none configured; use standard handling */
+            ssh_set_frozen(ssh, 1);
+            s->dlgret = verify_ssh_host_key(ssh->frontend,
+                                            ssh->savedhost, ssh->savedport,
+                                            ssh->hostkey->keytype, s->keystr,
+                                            s->fingerprint,
+                                            ssh_dialog_callback, ssh);
+            if (s->dlgret < 0) {
+                do {
+                    crReturnV;
+                    if (pktin) {
+                        bombout(("Unexpected data from server while waiting"
+                                 " for user host key response"));
+                        crStopV;
+                    }
+                } while (pktin || inlen > 0);
+                s->dlgret = ssh->user_response;
             }
-        } while (pktin || inlen > 0);
-        s->dlgret = ssh->user_response;
-    }
-    ssh_set_frozen(ssh, 0);
-    if (s->dlgret == 0) {
-       ssh_disconnect(ssh, "User aborted at host key verification", NULL,
-                      0, TRUE);
-        crStop(0);
-    }
-    if (!s->got_session_id) {     /* don't bother logging this in rekeys */
-       logevent("Host key fingerprint is:");
-       logevent(s->fingerprint);
+            ssh_set_frozen(ssh, 0);
+            if (s->dlgret == 0) {
+                ssh_disconnect(ssh, "Aborted at host key verification", NULL,
+                               0, TRUE);
+                crStopV;
+            }
+        }
+        sfree(s->fingerprint);
+        /*
+         * Save this host key, to check against the one presented in
+         * subsequent rekeys.
+         */
+        ssh->hostkey_str = s->keystr;
+    } else {
+        /*
+         * In a rekey, we never present an interactive host key
+         * verification request to the user. Instead, we simply
+         * enforce that the key we're seeing this time is identical to
+         * the one we saw before.
+         */
+        if (strcmp(ssh->hostkey_str, s->keystr)) {
+            bombout(("Host key was different in repeat key exchange"));
+            crStopV;
+        }
+        sfree(s->keystr);
     }
-    sfree(s->fingerprint);
-    sfree(s->keystr);
     ssh->hostkey->freekey(s->hkey);
 
     /*
@@ -5576,8 +6916,11 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      * authentication.
      */
     if (!s->got_session_id) {
+       assert(sizeof(s->exchange_hash) <= sizeof(ssh->v2_session_id));
        memcpy(ssh->v2_session_id, s->exchange_hash,
               sizeof(s->exchange_hash));
+       ssh->v2_session_id_len = ssh->kex->hash->hlen;
+       assert(ssh->v2_session_id_len <= sizeof(ssh->v2_session_id));
        s->got_session_id = TRUE;
     }
 
@@ -5612,13 +6955,21 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      * hash from the _first_ key exchange.
      */
     {
-       unsigned char keyspace[40];
-       ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'C',keyspace);
+       unsigned char keyspace[SSH2_KEX_MAX_HASH_LEN * SSH2_MKKEY_ITERS];
+       assert(sizeof(keyspace) >= ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+       ssh2_mkkey(ssh,s->K,s->exchange_hash,'C',keyspace);
+       assert((ssh->cscipher->keylen+7) / 8 <=
+              ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
        ssh->cscipher->setkey(ssh->cs_cipher_ctx, keyspace);
-       ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'A',keyspace);
+       ssh2_mkkey(ssh,s->K,s->exchange_hash,'A',keyspace);
+       assert(ssh->cscipher->blksize <=
+              ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
        ssh->cscipher->setiv(ssh->cs_cipher_ctx, keyspace);
-       ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'E',keyspace);
+       ssh2_mkkey(ssh,s->K,s->exchange_hash,'E',keyspace);
+       assert(ssh->csmac->len <=
+              ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
        ssh->csmac->setkey(ssh->cs_mac_ctx, keyspace);
+       smemclr(keyspace, sizeof(keyspace));
     }
 
     logeventf(ssh, "Initialised %.200s client->server encryption",
@@ -5639,10 +6990,10 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
     /*
      * Expect SSH2_MSG_NEWKEYS from server.
      */
-    crWaitUntil(pktin);
+    crWaitUntilV(pktin);
     if (pktin->type != SSH2_MSG_NEWKEYS) {
        bombout(("expected new-keys packet from server"));
-       crStop(0);
+       crStopV;
     }
     ssh->incoming_data_size = 0;       /* start counting from here */
 
@@ -5670,13 +7021,21 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      * hash from the _first_ key exchange.
      */
     {
-       unsigned char keyspace[40];
-       ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'D',keyspace);
+       unsigned char keyspace[SSH2_KEX_MAX_HASH_LEN * SSH2_MKKEY_ITERS];
+       assert(sizeof(keyspace) >= ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+       ssh2_mkkey(ssh,s->K,s->exchange_hash,'D',keyspace);
+       assert((ssh->sccipher->keylen+7) / 8 <=
+              ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
        ssh->sccipher->setkey(ssh->sc_cipher_ctx, keyspace);
-       ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'B',keyspace);
+       ssh2_mkkey(ssh,s->K,s->exchange_hash,'B',keyspace);
+       assert(ssh->sccipher->blksize <=
+              ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
        ssh->sccipher->setiv(ssh->sc_cipher_ctx, keyspace);
-       ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'F',keyspace);
+       ssh2_mkkey(ssh,s->K,s->exchange_hash,'F',keyspace);
+       assert(ssh->scmac->len <=
+              ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
        ssh->scmac->setkey(ssh->sc_mac_ctx, keyspace);
+       smemclr(keyspace, sizeof(keyspace));
     }
     logeventf(ssh, "Initialised %.200s server->client encryption",
              ssh->sccipher->text_name);
@@ -5687,14 +7046,9 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                  ssh->sccomp->text_name);
 
     /*
-     * Free key exchange data.
+     * Free shared secret.
      */
-    freebn(s->f);
     freebn(s->K);
-    if (ssh->kex == &ssh_diffiehellman_gex) {
-       freebn(s->g);
-       freebn(s->p);
-    }
 
     /*
      * Key exchange is over. Loop straight back round if we have a
@@ -5712,23 +7066,10 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      */
     ssh->kex_in_progress = FALSE;
     ssh->last_rekey = GETTICKCOUNT();
-    if (ssh->cfg.ssh_rekey_time != 0)
-       ssh->next_rekey = schedule_timer(ssh->cfg.ssh_rekey_time*60*TICKSPERSEC,
+    if (conf_get_int(ssh->conf, CONF_ssh_rekey_time) != 0)
+       ssh->next_rekey = schedule_timer(conf_get_int(ssh->conf, CONF_ssh_rekey_time)*60*TICKSPERSEC,
                                         ssh2_timer, ssh);
 
-    /*
-     * If this is the first key exchange phase, we must pass the
-     * SSH2_MSG_NEWKEYS packet to the next layer, not because it
-     * wants to see it but because it will need time to initialise
-     * itself before it sees an actual packet. In subsequent key
-     * exchange phases, we don't pass SSH2_MSG_NEWKEYS on, because
-     * it would only confuse the layer above.
-     */
-    if (s->activated_authconn) {
-       crReturn(0);
-    }
-    s->activated_authconn = TRUE;
-
     /*
      * Now we're encrypting. Begin returning 1 to the protocol main
      * function so that other things can run on top of the
@@ -5736,19 +7077,59 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      * start.
      * 
      * We _also_ go back to the start if we see pktin==NULL and
-     * inlen==-1, because this is a special signal meaning
+     * inlen negative, because this is a special signal meaning
      * `initiate client-driven rekey', and `in' contains a message
      * giving the reason for the rekey.
+     *
+     * inlen==-1 means always initiate a rekey;
+     * inlen==-2 means that userauth has completed successfully and
+     *   we should consider rekeying (for delayed compression).
      */
     while (!((pktin && pktin->type == SSH2_MSG_KEXINIT) ||
-            (!pktin && inlen == -1))) {
+            (!pktin && inlen < 0))) {
         wait_for_rekey:
-       crReturn(1);
+       if (!ssh->protocol_initial_phase_done) {
+           ssh->protocol_initial_phase_done = TRUE;
+           /*
+            * Allow authconn to initialise itself.
+            */
+           do_ssh2_authconn(ssh, NULL, 0, NULL);
+       }
+       crReturnV;
     }
     if (pktin) {
        logevent("Server initiated key re-exchange");
     } else {
+       if (inlen == -2) {
+           /* 
+            * authconn has seen a USERAUTH_SUCCEEDED. Time to enable
+            * delayed compression, if it's available.
+            *
+            * draft-miller-secsh-compression-delayed-00 says that you
+            * negotiate delayed compression in the first key exchange, and
+            * both sides start compressing when the server has sent
+            * USERAUTH_SUCCESS. This has a race condition -- the server
+            * can't know when the client has seen it, and thus which incoming
+            * packets it should treat as compressed.
+            *
+            * Instead, we do the initial key exchange without offering the
+            * delayed methods, but note if the server offers them; when we
+            * get here, if a delayed method was available that was higher
+            * on our list than what we got, we initiate a rekey in which we
+            * _do_ list the delayed methods (and hopefully get it as a
+            * result). Subsequent rekeys will do the same.
+            */
+           assert(!s->userauth_succeeded); /* should only happen once */
+           s->userauth_succeeded = TRUE;
+           if (!s->pending_compression)
+               /* Can't see any point rekeying. */
+               goto wait_for_rekey;       /* this is utterly horrid */
+           /* else fall through to rekey... */
+           s->pending_compression = FALSE;
+       }
         /*
+        * Now we've decided to rekey.
+        *
          * Special case: if the server bug is set that doesn't
          * allow rekeying, we give a different log message and
          * continue waiting. (If such a server _initiates_ a rekey,
@@ -5761,19 +7142,19 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
              * hit the event log _too_ often. */
             ssh->outgoing_data_size = 0;
             ssh->incoming_data_size = 0;
-            if (ssh->cfg.ssh_rekey_time != 0) {
+            if (conf_get_int(ssh->conf, CONF_ssh_rekey_time) != 0) {
                 ssh->next_rekey =
-                    schedule_timer(ssh->cfg.ssh_rekey_time*60*TICKSPERSEC,
+                    schedule_timer(conf_get_int(ssh->conf, CONF_ssh_rekey_time)*60*TICKSPERSEC,
                                    ssh2_timer, ssh);
             }
-            goto wait_for_rekey;       /* this is utterly horrid */
+            goto wait_for_rekey;       /* this is still utterly horrid */
         } else {
             logeventf(ssh, "Initiating key re-exchange (%s)", (char *)in);
         }
     }
     goto begin_key_exchange;
 
-    crFinish(1);
+    crFinishV;
 }
 
 /*
@@ -5792,6 +7173,7 @@ static int ssh2_try_send(struct ssh_channel *c)
 {
     Ssh ssh = c->ssh;
     struct Packet *pktout;
+    int ret;
 
     while (c->v.v2.remwindow > 0 && bufchain_size(&c->v.v2.outbuffer) > 0) {
        int len;
@@ -5803,10 +7185,8 @@ static int ssh2_try_send(struct ssh_channel *c)
            len = c->v.v2.remmaxpkt;
        pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_DATA);
        ssh2_pkt_adduint32(pktout, c->remoteid);
-       dont_log_data(ssh, pktout, PKTLOG_OMIT);
        ssh2_pkt_addstring_start(pktout);
        ssh2_pkt_addstring_data(pktout, data, len);
-       end_log_omission(ssh, pktout);
        ssh2_pkt_send(ssh, pktout);
        bufchain_consume(&c->v.v2.outbuffer, len);
        c->v.v2.remwindow -= len;
@@ -5816,14 +7196,23 @@ static int ssh2_try_send(struct ssh_channel *c)
      * After having sent as much data as we can, return the amount
      * still buffered.
      */
-    return bufchain_size(&c->v.v2.outbuffer);
+    ret = bufchain_size(&c->v.v2.outbuffer);
+
+    /*
+     * And if there's no data pending but we need to send an EOF, send
+     * it.
+     */
+    if (!ret && c->pending_eof)
+        ssh_channel_try_eof(c);
+
+    return ret;
 }
 
-static void ssh2_try_send_and_unthrottle(struct ssh_channel *c)
+static void ssh2_try_send_and_unthrottle(Ssh ssh, struct ssh_channel *c)
 {
     int bufsize;
-    if (c->closes)
-       return;                        /* don't send on closing channels */
+    if (c->closes & CLOSES_SENT_EOF)
+       return;                   /* don't send on channels we've EOFed */
     bufsize = ssh2_try_send(c);
     if (bufsize == 0) {
        switch (c->type) {
@@ -5832,34 +7221,148 @@ static void ssh2_try_send_and_unthrottle(struct ssh_channel *c)
             * notification since it will be polled */
            break;
          case CHAN_X11:
-           x11_unthrottle(c->u.x11.s);
+           x11_unthrottle(c->u.x11.xconn);
            break;
          case CHAN_AGENT:
            /* agent sockets are request/response and need no
             * buffer management */
            break;
          case CHAN_SOCKDATA:
-           pfd_unthrottle(c->u.pfd.s);
+           pfd_unthrottle(c->u.pfd.pf);
            break;
        }
     }
 }
 
+static int ssh_is_simple(Ssh ssh)
+{
+    /*
+     * We use the 'simple' variant of the SSH protocol if we're asked
+     * to, except not if we're also doing connection-sharing (either
+     * tunnelling our packets over an upstream or expecting to be
+     * tunnelled over ourselves), since then the assumption that we
+     * have only one channel to worry about is not true after all.
+     */
+    return (conf_get_int(ssh->conf, CONF_ssh_simple) &&
+            !ssh->bare_connection && !ssh->connshare);
+}
+
+/*
+ * Set up most of a new ssh_channel for SSH-2.
+ */
+static void ssh2_channel_init(struct ssh_channel *c)
+{
+    Ssh ssh = c->ssh;
+    c->localid = alloc_channel_id(ssh);
+    c->closes = 0;
+    c->pending_eof = FALSE;
+    c->throttling_conn = FALSE;
+    c->v.v2.locwindow = c->v.v2.locmaxwin = c->v.v2.remlocwin =
+       ssh_is_simple(ssh) ? OUR_V2_BIGWIN : OUR_V2_WINSIZE;
+    c->v.v2.chanreq_head = NULL;
+    c->v.v2.throttle_state = UNTHROTTLED;
+    bufchain_init(&c->v.v2.outbuffer);
+}
+
+/*
+ * Construct the common parts of a CHANNEL_OPEN.
+ */
+static struct Packet *ssh2_chanopen_init(struct ssh_channel *c, char *type)
+{
+    struct Packet *pktout;
+
+    pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
+    ssh2_pkt_addstring(pktout, type);
+    ssh2_pkt_adduint32(pktout, c->localid);
+    ssh2_pkt_adduint32(pktout, c->v.v2.locwindow);/* our window size */
+    ssh2_pkt_adduint32(pktout, OUR_V2_MAXPKT);      /* our max pkt size */
+    return pktout;
+}
+
+/*
+ * CHANNEL_FAILURE doesn't come with any indication of what message
+ * caused it, so we have to keep track of the outstanding
+ * CHANNEL_REQUESTs ourselves.
+ */
+static void ssh2_queue_chanreq_handler(struct ssh_channel *c,
+                                      cchandler_fn_t handler, void *ctx)
+{
+    struct outstanding_channel_request *ocr =
+       snew(struct outstanding_channel_request);
+
+    assert(!(c->closes & (CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE)));
+    ocr->handler = handler;
+    ocr->ctx = ctx;
+    ocr->next = NULL;
+    if (!c->v.v2.chanreq_head)
+       c->v.v2.chanreq_head = ocr;
+    else
+       c->v.v2.chanreq_tail->next = ocr;
+    c->v.v2.chanreq_tail = ocr;
+}
+
+/*
+ * Construct the common parts of a CHANNEL_REQUEST.  If handler is not
+ * NULL then a reply will be requested and the handler will be called
+ * when it arrives.  The returned packet is ready to have any
+ * request-specific data added and be sent.  Note that if a handler is
+ * provided, it's essential that the request actually be sent.
+ *
+ * The handler will usually be passed the response packet in pktin. If
+ * pktin is NULL, this means that no reply will ever be forthcoming
+ * (e.g. because the entire connection is being destroyed, or because
+ * the server initiated channel closure before we saw the response)
+ * and the handler should free any storage it's holding.
+ */
+static struct Packet *ssh2_chanreq_init(struct ssh_channel *c, char *type,
+                                       cchandler_fn_t handler, void *ctx)
+{
+    struct Packet *pktout;
+
+    assert(!(c->closes & (CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE)));
+    pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+    ssh2_pkt_adduint32(pktout, c->remoteid);
+    ssh2_pkt_addstring(pktout, type);
+    ssh2_pkt_addbool(pktout, handler != NULL);
+    if (handler != NULL)
+       ssh2_queue_chanreq_handler(c, handler, ctx);
+    return pktout;
+}
+
 /*
  * Potentially enlarge the window on an SSH-2 channel.
  */
-static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
+static void ssh2_handle_winadj_response(struct ssh_channel *, struct Packet *,
+                                       void *);
+static void ssh2_set_window(struct ssh_channel *c, int newwin)
 {
     Ssh ssh = c->ssh;
 
     /*
-     * Never send WINDOW_ADJUST for a channel that the remote side
-     * already thinks it's closed; there's no point, since it won't
-     * be sending any more data anyway.
+     * Never send WINDOW_ADJUST for a channel that the remote side has
+     * already sent EOF on; there's no point, since it won't be
+     * sending any more data anyway. Ditto if _we've_ already sent
+     * CLOSE.
      */
-    if (c->closes != 0)
+    if (c->closes & (CLOSES_RCVD_EOF | CLOSES_SENT_CLOSE))
        return;
 
+    /*
+     * Also, never widen the window for an X11 channel when we're
+     * still waiting to see its initial auth and may yet hand it off
+     * to a downstream.
+     */
+    if (c->type == CHAN_X11 && c->u.x11.initial)
+        return;
+
+    /*
+     * If the remote end has a habit of ignoring maxpkt, limit the
+     * window so that it has no choice (assuming it doesn't ignore the
+     * window as well).
+     */
+    if ((ssh->remote_bugs & BUG_SSH2_MAXPKT) && newwin > OUR_V2_MAXPKT)
+       newwin = OUR_V2_MAXPKT;
+
     /*
      * Only send a WINDOW_ADJUST if there's significantly more window
      * available than the other end thinks there is.  This saves us
@@ -5867,9 +7370,35 @@ static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
      *
      * "Significant" is arbitrarily defined as half the window size.
      */
-    if (newwin > c->v.v2.locwindow * 2) {
+    if (newwin / 2 >= c->v.v2.locwindow) {
        struct Packet *pktout;
+       unsigned *up;
+
+       /*
+        * In order to keep track of how much window the client
+        * actually has available, we'd like it to acknowledge each
+        * WINDOW_ADJUST.  We can't do that directly, so we accompany
+        * it with a CHANNEL_REQUEST that has to be acknowledged.
+        *
+        * This is only necessary if we're opening the window wide.
+        * If we're not, then throughput is being constrained by
+        * something other than the maximum window size anyway.
+        */
+       if (newwin == c->v.v2.locmaxwin &&
+            !(ssh->remote_bugs & BUG_CHOKES_ON_WINADJ)) {
+           up = snew(unsigned);
+           *up = newwin - c->v.v2.locwindow;
+           pktout = ssh2_chanreq_init(c, "winadj@putty.projects.tartarus.org",
+                                      ssh2_handle_winadj_response, up);
+           ssh2_pkt_send(ssh, pktout);
 
+           if (c->v.v2.throttle_state != UNTHROTTLED)
+               c->v.v2.throttle_state = UNTHROTTLING;
+       } else {
+           /* Pretend the WINDOW_ADJUST was acked immediately. */
+           c->v.v2.remlocwin = newwin;
+           c->v.v2.throttle_state = THROTTLED;
+       }
        pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
        ssh2_pkt_adduint32(pktout, c->remoteid);
        ssh2_pkt_adduint32(pktout, newwin - c->v.v2.locwindow);
@@ -5878,14 +7407,96 @@ static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
     }
 }
 
+/*
+ * Find the channel associated with a message.  If there's no channel,
+ * or it's not properly open, make a noise about it and return NULL.
+ */
+static struct ssh_channel *ssh2_channel_msg(Ssh ssh, struct Packet *pktin)
+{
+    unsigned localid = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+
+    c = find234(ssh->channels, &localid, ssh_channelfind);
+    if (!c ||
+       (c->type != CHAN_SHARING && c->halfopen &&
+         pktin->type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION &&
+        pktin->type != SSH2_MSG_CHANNEL_OPEN_FAILURE)) {
+       char *buf = dupprintf("Received %s for %s channel %u",
+                             ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx,
+                                           pktin->type),
+                             c ? "half-open" : "nonexistent", localid);
+       ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
+       sfree(buf);
+       return NULL;
+    }
+    return c;
+}
+
+static void ssh2_handle_winadj_response(struct ssh_channel *c,
+                                       struct Packet *pktin, void *ctx)
+{
+    unsigned *sizep = ctx;
+
+    /*
+     * Winadj responses should always be failures. However, at least
+     * one server ("boks_sshd") is known to return SUCCESS for channel
+     * requests it's never heard of, such as "winadj@putty". Raised
+     * with foxt.com as bug 090916-090424, but for the sake of a quiet
+     * life, we don't worry about what kind of response we got.
+     */
+
+    c->v.v2.remlocwin += *sizep;
+    sfree(sizep);
+    /*
+     * winadj messages are only sent when the window is fully open, so
+     * if we get an ack of one, we know any pending unthrottle is
+     * complete.
+     */
+    if (c->v.v2.throttle_state == UNTHROTTLING)
+       c->v.v2.throttle_state = UNTHROTTLED;
+}
+
+static void ssh2_msg_channel_response(Ssh ssh, struct Packet *pktin)
+{
+    struct ssh_channel *c = ssh2_channel_msg(ssh, pktin);
+    struct outstanding_channel_request *ocr;
+
+    if (!c) return;
+    if (c->type == CHAN_SHARING) {
+        share_got_pkt_from_server(c->u.sharing.ctx, pktin->type,
+                                  pktin->body, pktin->length);
+        return;
+    }
+    ocr = c->v.v2.chanreq_head;
+    if (!ocr) {
+       ssh2_msg_unexpected(ssh, pktin);
+       return;
+    }
+    ocr->handler(c, pktin, ocr->ctx);
+    c->v.v2.chanreq_head = ocr->next;
+    sfree(ocr);
+    /*
+     * We may now initiate channel-closing procedures, if that
+     * CHANNEL_REQUEST was the last thing outstanding before we send
+     * CHANNEL_CLOSE.
+     */
+    ssh2_channel_check_close(c);
+}
+
 static void ssh2_msg_channel_window_adjust(Ssh ssh, struct Packet *pktin)
 {
-    unsigned i = ssh_pkt_getuint32(pktin);
     struct ssh_channel *c;
-    c = find234(ssh->channels, &i, ssh_channelfind);
-    if (c && !c->closes) {
+    c = ssh2_channel_msg(ssh, pktin);
+    if (!c)
+       return;
+    if (c->type == CHAN_SHARING) {
+        share_got_pkt_from_server(c->u.sharing.ctx, pktin->type,
+                                  pktin->body, pktin->length);
+        return;
+    }
+    if (!(c->closes & CLOSES_SENT_EOF)) {
        c->v.v2.remwindow += ssh_pkt_getuint32(pktin);
-       ssh2_try_send_and_unthrottle(c);
+       ssh2_try_send_and_unthrottle(ssh, c);
     }
 }
 
@@ -5893,11 +7504,15 @@ static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
 {
     char *data;
     int length;
-    unsigned i = ssh_pkt_getuint32(pktin);
     struct ssh_channel *c;
-    c = find234(ssh->channels, &i, ssh_channelfind);
+    c = ssh2_channel_msg(ssh, pktin);
     if (!c)
-       return;                        /* nonexistent channel */
+       return;
+    if (c->type == CHAN_SHARING) {
+        share_got_pkt_from_server(c->u.sharing.ctx, pktin->type,
+                                  pktin->body, pktin->length);
+        return;
+    }
     if (pktin->type == SSH2_MSG_CHANNEL_EXTENDED_DATA &&
        ssh_pkt_getuint32(pktin) != SSH2_EXTENDED_DATA_STDERR)
        return;                        /* extended but not stderr */
@@ -5905,6 +7520,7 @@ static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
     if (data) {
        int bufsize = 0;
        c->v.v2.locwindow -= length;
+       c->v.v2.remlocwin -= length;
        switch (c->type) {
          case CHAN_MAINSESSION:
            bufsize =
@@ -5913,15 +7529,16 @@ static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
                             data, length);
            break;
          case CHAN_X11:
-           bufsize = x11_send(c->u.x11.s, data, length);
+           bufsize = x11_send(c->u.x11.xconn, data, length);
            break;
          case CHAN_SOCKDATA:
-           bufsize = pfd_send(c->u.pfd.s, data, length);
+           bufsize = pfd_send(c->u.pfd.pf, data, length);
            break;
          case CHAN_AGENT:
            while (length > 0) {
                if (c->u.a.lensofar < 4) {
-                   unsigned int l = min(4 - c->u.a.lensofar, length);
+                   unsigned int l = min(4 - c->u.a.lensofar,
+                                        (unsigned)length);
                    memcpy(c->u.a.msglen + c->u.a.lensofar,
                           data, l);
                    data += l;
@@ -5938,7 +7555,7 @@ static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
                if (c->u.a.lensofar >= 4 && length > 0) {
                    unsigned int l =
                        min(c->u.a.totallen - c->u.a.lensofar,
-                           length);
+                           (unsigned)length);
                    memcpy(c->u.a.message + c->u.a.lensofar,
                           data, l);
                    data += l;
@@ -5948,142 +7565,359 @@ static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
                if (c->u.a.lensofar == c->u.a.totallen) {
                    void *reply;
                    int replylen;
+                    c->u.a.outstanding_requests++;
                    if (agent_query(c->u.a.message,
                                    c->u.a.totallen,
                                    &reply, &replylen,
                                    ssh_agentf_callback, c))
                        ssh_agentf_callback(c, reply, replylen);
                    sfree(c->u.a.message);
+                    c->u.a.message = NULL;
                    c->u.a.lensofar = 0;
                }
            }
            bufsize = 0;
            break;
        }
+       /*
+        * If it looks like the remote end hit the end of its window,
+        * and we didn't want it to do that, think about using a
+        * larger window.
+        */
+       if (c->v.v2.remlocwin <= 0 && c->v.v2.throttle_state == UNTHROTTLED &&
+           c->v.v2.locmaxwin < 0x40000000)
+           c->v.v2.locmaxwin += OUR_V2_WINSIZE;
        /*
         * If we are not buffering too much data,
         * enlarge the window again at the remote side.
+        * If we are buffering too much, we may still
+        * need to adjust the window if the server's
+        * sent excess data.
+        */
+       ssh2_set_window(c, bufsize < c->v.v2.locmaxwin ?
+                       c->v.v2.locmaxwin - bufsize : 0);
+       /*
+        * If we're either buffering way too much data, or if we're
+        * buffering anything at all and we're in "simple" mode,
+        * throttle the whole channel.
         */
-       if (bufsize < OUR_V2_WINSIZE)
-           ssh2_set_window(c, OUR_V2_WINSIZE - bufsize);
+       if ((bufsize > c->v.v2.locmaxwin || (ssh_is_simple(ssh) && bufsize>0))
+            && !c->throttling_conn) {
+           c->throttling_conn = 1;
+           ssh_throttle_conn(ssh, +1);
+       }
     }
 }
 
-static void ssh2_msg_channel_eof(Ssh ssh, struct Packet *pktin)
+static void ssh_check_termination(Ssh ssh)
 {
-    unsigned i = ssh_pkt_getuint32(pktin);
-    struct ssh_channel *c;
+    if (ssh->version == 2 &&
+        !conf_get_int(ssh->conf, CONF_ssh_no_shell) &&
+        count234(ssh->channels) == 0 &&
+        !(ssh->connshare && share_ndownstreams(ssh->connshare) > 0)) {
+        /*
+         * We used to send SSH_MSG_DISCONNECT here, because I'd
+         * believed that _every_ conforming SSH-2 connection had to
+         * end with a disconnect being sent by at least one side;
+         * apparently I was wrong and it's perfectly OK to
+         * unceremoniously slam the connection shut when you're done,
+         * and indeed OpenSSH feels this is more polite than sending a
+         * DISCONNECT. So now we don't.
+         */
+        ssh_disconnect(ssh, "All channels closed", NULL, 0, TRUE);
+    }
+}
 
-    c = find234(ssh->channels, &i, ssh_channelfind);
-    if (!c)
-       return;                        /* nonexistent channel */
+void ssh_sharing_downstream_connected(Ssh ssh, unsigned id,
+                                      const char *peerinfo)
+{
+    if (peerinfo)
+        logeventf(ssh, "Connection sharing downstream #%u connected from %s",
+                  id, peerinfo);
+    else
+        logeventf(ssh, "Connection sharing downstream #%u connected", id);
+}
 
-    if (c->type == CHAN_X11) {
-       /*
-        * Remote EOF on an X11 channel means we should
-        * wrap up and close the channel ourselves.
-        */
-       x11_close(c->u.x11.s);
-       sshfwd_close(c);
-    } else if (c->type == CHAN_AGENT) {
-       sshfwd_close(c);
-    } else if (c->type == CHAN_SOCKDATA) {
-       pfd_close(c->u.pfd.s);
-       sshfwd_close(c);
-    }
+void ssh_sharing_downstream_disconnected(Ssh ssh, unsigned id)
+{
+    logeventf(ssh, "Connection sharing downstream #%u disconnected", id);
+    ssh_check_termination(ssh);
 }
 
-static void ssh2_msg_channel_close(Ssh ssh, struct Packet *pktin)
+void ssh_sharing_logf(Ssh ssh, unsigned id, const char *logfmt, ...)
 {
-    unsigned i = ssh_pkt_getuint32(pktin);
-    struct ssh_channel *c;
-    struct Packet *pktout;
+    va_list ap;
+    char *buf;
+
+    va_start(ap, logfmt);
+    buf = dupvprintf(logfmt, ap);
+    va_end(ap);
+    if (id)
+        logeventf(ssh, "Connection sharing downstream #%u: %s", id, buf);
+    else
+        logeventf(ssh, "Connection sharing: %s", buf);
+    sfree(buf);
+}
+
+static void ssh_channel_destroy(struct ssh_channel *c)
+{
+    Ssh ssh = c->ssh;
 
-    c = find234(ssh->channels, &i, ssh_channelfind);
-    if (!c || c->halfopen) {
-       bombout(("Received CHANNEL_CLOSE for %s channel %d\n",
-                c ? "half-open" : "nonexistent", i));
-       return;
-    }
-    /* Do pre-close processing on the channel. */
     switch (c->type) {
       case CHAN_MAINSESSION:
-       ssh->mainchan = NULL;
-       update_specials_menu(ssh->frontend);
-       break;
+        ssh->mainchan = NULL;
+        update_specials_menu(ssh->frontend);
+        break;
       case CHAN_X11:
-       if (c->u.x11.s != NULL)
-           x11_close(c->u.x11.s);
-       sshfwd_close(c);
-       break;
+        if (c->u.x11.xconn != NULL)
+            x11_close(c->u.x11.xconn);
+        logevent("Forwarded X11 connection terminated");
+        break;
       case CHAN_AGENT:
-       sshfwd_close(c);
-       break;
+        sfree(c->u.a.message);
+        break;
       case CHAN_SOCKDATA:
-       if (c->u.pfd.s != NULL)
-           pfd_close(c->u.pfd.s);
-       sshfwd_close(c);
-       break;
+        if (c->u.pfd.pf != NULL)
+            pfd_close(c->u.pfd.pf);
+        logevent("Forwarded port closed");
+        break;
+    }
+
+    del234(ssh->channels, c);
+    if (ssh->version == 2) {
+        bufchain_clear(&c->v.v2.outbuffer);
+       assert(c->v.v2.chanreq_head == NULL);
+    }
+    sfree(c);
+
+    /*
+     * If that was the last channel left open, we might need to
+     * terminate.
+     */
+    ssh_check_termination(ssh);
+}
+
+static void ssh2_channel_check_close(struct ssh_channel *c)
+{
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+
+    if (c->halfopen) {
+        /*
+         * If we've sent out our own CHANNEL_OPEN but not yet seen
+         * either OPEN_CONFIRMATION or OPEN_FAILURE in response, then
+         * it's too early to be sending close messages of any kind.
+         */
+        return;
     }
-    if (c->closes == 0) {
+
+    if ((!((CLOSES_SENT_EOF | CLOSES_RCVD_EOF) & ~c->closes) ||
+        c->type == CHAN_ZOMBIE) &&
+       !c->v.v2.chanreq_head &&
+       !(c->closes & CLOSES_SENT_CLOSE)) {
+        /*
+         * We have both sent and received EOF (or the channel is a
+         * zombie), and we have no outstanding channel requests, which
+         * means the channel is in final wind-up. But we haven't sent
+         * CLOSE, so let's do so now.
+         */
        pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
        ssh2_pkt_adduint32(pktout, c->remoteid);
        ssh2_pkt_send(ssh, pktout);
+        c->closes |= CLOSES_SENT_EOF | CLOSES_SENT_CLOSE;
+    }
+
+    if (!((CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE) & ~c->closes)) {
+       assert(c->v.v2.chanreq_head == NULL);
+        /*
+         * We have both sent and received CLOSE, which means we're
+         * completely done with the channel.
+         */
+        ssh_channel_destroy(c);
+    }
+}
+
+static void ssh2_channel_got_eof(struct ssh_channel *c)
+{
+    if (c->closes & CLOSES_RCVD_EOF)
+        return;                        /* already seen EOF */
+    c->closes |= CLOSES_RCVD_EOF;
+
+    if (c->type == CHAN_X11) {
+       x11_send_eof(c->u.x11.xconn);
+    } else if (c->type == CHAN_AGENT) {
+        if (c->u.a.outstanding_requests == 0) {
+            /* Manufacture an outgoing EOF in response to the incoming one. */
+            sshfwd_write_eof(c);
+        }
+    } else if (c->type == CHAN_SOCKDATA) {
+       pfd_send_eof(c->u.pfd.pf);
+    } else if (c->type == CHAN_MAINSESSION) {
+        Ssh ssh = c->ssh;
+
+        if (!ssh->sent_console_eof &&
+            (from_backend_eof(ssh->frontend) || ssh->got_pty)) {
+            /*
+             * Either from_backend_eof told us that the front end
+             * wants us to close the outgoing side of the connection
+             * as soon as we see EOF from the far end, or else we've
+             * unilaterally decided to do that because we've allocated
+             * a remote pty and hence EOF isn't a particularly
+             * meaningful concept.
+             */
+            sshfwd_write_eof(c);
+        }
+        ssh->sent_console_eof = TRUE;
+    }
+
+    ssh2_channel_check_close(c);
+}
+
+static void ssh2_msg_channel_eof(Ssh ssh, struct Packet *pktin)
+{
+    struct ssh_channel *c;
+
+    c = ssh2_channel_msg(ssh, pktin);
+    if (!c)
+       return;
+    if (c->type == CHAN_SHARING) {
+        share_got_pkt_from_server(c->u.sharing.ctx, pktin->type,
+                                  pktin->body, pktin->length);
+        return;
+    }
+    ssh2_channel_got_eof(c);
+}
+
+static void ssh2_msg_channel_close(Ssh ssh, struct Packet *pktin)
+{
+    struct ssh_channel *c;
+
+    c = ssh2_channel_msg(ssh, pktin);
+    if (!c)
+       return;
+    if (c->type == CHAN_SHARING) {
+        share_got_pkt_from_server(c->u.sharing.ctx, pktin->type,
+                                  pktin->body, pktin->length);
+        return;
     }
-    del234(ssh->channels, c);
-    bufchain_clear(&c->v.v2.outbuffer);
-    sfree(c);
 
     /*
-     * See if that was the last channel left open.
-     * (This is only our termination condition if we're
-     * not running in -N mode.)
+     * When we receive CLOSE on a channel, we assume it comes with an
+     * implied EOF if we haven't seen EOF yet.
      */
-    if (!ssh->cfg.ssh_no_shell && count234(ssh->channels) == 0) {
-       /*
-        * We used to send SSH_MSG_DISCONNECT here,
-        * because I'd believed that _every_ conforming
-        * SSH-2 connection had to end with a disconnect
-        * being sent by at least one side; apparently
-        * I was wrong and it's perfectly OK to
-        * unceremoniously slam the connection shut
-        * when you're done, and indeed OpenSSH feels
-        * this is more polite than sending a
-        * DISCONNECT. So now we don't.
-        */
-       ssh_disconnect(ssh, "All channels closed", NULL, 0, TRUE);
+    ssh2_channel_got_eof(c);
+
+    if (!(ssh->remote_bugs & BUG_SENDS_LATE_REQUEST_REPLY)) {
+        /*
+         * It also means we stop expecting to see replies to any
+         * outstanding channel requests, so clean those up too.
+         * (ssh_chanreq_init will enforce by assertion that we don't
+         * subsequently put anything back on this list.)
+         */
+        while (c->v.v2.chanreq_head) {
+            struct outstanding_channel_request *ocr = c->v.v2.chanreq_head;
+            ocr->handler(c, NULL, ocr->ctx);
+            c->v.v2.chanreq_head = ocr->next;
+            sfree(ocr);
+        }
+    }
+
+    /*
+     * And we also send an outgoing EOF, if we haven't already, on the
+     * assumption that CLOSE is a pretty forceful announcement that
+     * the remote side is doing away with the entire channel. (If it
+     * had wanted to send us EOF and continue receiving data from us,
+     * it would have just sent CHANNEL_EOF.)
+     */
+    if (!(c->closes & CLOSES_SENT_EOF)) {
+        /*
+         * Make sure we don't read any more from whatever our local
+         * data source is for this channel.
+         */
+        switch (c->type) {
+          case CHAN_MAINSESSION:
+            ssh->send_ok = 0;     /* stop trying to read from stdin */
+            break;
+          case CHAN_X11:
+           x11_override_throttle(c->u.x11.xconn, 1);
+           break;
+         case CHAN_SOCKDATA:
+           pfd_override_throttle(c->u.pfd.pf, 1);
+           break;
+        }
+
+        /*
+         * Abandon any buffered data we still wanted to send to this
+         * channel. Receiving a CHANNEL_CLOSE is an indication that
+         * the server really wants to get on and _destroy_ this
+         * channel, and it isn't going to send us any further
+         * WINDOW_ADJUSTs to permit us to send pending stuff.
+         */
+        bufchain_clear(&c->v.v2.outbuffer);
+
+        /*
+         * Send outgoing EOF.
+         */
+        sshfwd_write_eof(c);
+    }
+
+    /*
+     * Now process the actual close.
+     */
+    if (!(c->closes & CLOSES_RCVD_CLOSE)) {
+        c->closes |= CLOSES_RCVD_CLOSE;
+        ssh2_channel_check_close(c);
     }
 }
 
 static void ssh2_msg_channel_open_confirmation(Ssh ssh, struct Packet *pktin)
 {
-    unsigned i = ssh_pkt_getuint32(pktin);
     struct ssh_channel *c;
-    struct Packet *pktout;
 
-    c = find234(ssh->channels, &i, ssh_channelfind);
+    c = ssh2_channel_msg(ssh, pktin);
     if (!c)
-       return;                        /* nonexistent channel */
-    if (c->type != CHAN_SOCKDATA_DORMANT)
-       return;                        /* dunno why they're confirming this */
+       return;
+    if (c->type == CHAN_SHARING) {
+        share_got_pkt_from_server(c->u.sharing.ctx, pktin->type,
+                                  pktin->body, pktin->length);
+        return;
+    }
+    assert(c->halfopen); /* ssh2_channel_msg will have enforced this */
     c->remoteid = ssh_pkt_getuint32(pktin);
     c->halfopen = FALSE;
-    c->type = CHAN_SOCKDATA;
     c->v.v2.remwindow = ssh_pkt_getuint32(pktin);
     c->v.v2.remmaxpkt = ssh_pkt_getuint32(pktin);
-    if (c->u.pfd.s)
-       pfd_confirm(c->u.pfd.s);
-    if (c->closes) {
-       /*
-        * We have a pending close on this channel,
-        * which we decided on before the server acked
-        * the channel open. So now we know the
-        * remoteid, we can close it again.
-        */
-       pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
-       ssh2_pkt_adduint32(pktout, c->remoteid);
-       ssh2_pkt_send(ssh, pktout);
+
+    if (c->type == CHAN_SOCKDATA_DORMANT) {
+        c->type = CHAN_SOCKDATA;
+        if (c->u.pfd.pf)
+            pfd_confirm(c->u.pfd.pf);
+    } else if (c->type == CHAN_ZOMBIE) {
+        /*
+         * This case can occur if a local socket error occurred
+         * between us sending out CHANNEL_OPEN and receiving
+         * OPEN_CONFIRMATION. In this case, all we can do is
+         * immediately initiate close proceedings now that we know the
+         * server's id to put in the close message.
+         */
+        ssh2_channel_check_close(c);
+    } else {
+        /*
+         * We never expect to receive OPEN_CONFIRMATION for any
+         * *other* channel type (since only local-to-remote port
+         * forwardings cause us to send CHANNEL_OPEN after the main
+         * channel is live - all other auxiliary channel types are
+         * initiated from the server end). It's safe to enforce this
+         * by assertion rather than by ssh_disconnect, because the
+         * real point is that we never constructed a half-open channel
+         * structure in the first place with any type other than the
+         * above.
+         */
+        assert(!"Funny channel type in ssh2_msg_channel_open_confirmation");
     }
+
+    if (c->pending_eof)
+        ssh_channel_try_eof(c);        /* in case we had a pending EOF */
 }
 
 static void ssh2_msg_channel_open_failure(Ssh ssh, struct Packet *pktin)
@@ -6095,25 +7929,50 @@ static void ssh2_msg_channel_open_failure(Ssh ssh, struct Packet *pktin)
            "Unknown channel type",
            "Resource shortage",
     };
-    unsigned i = ssh_pkt_getuint32(pktin);
     unsigned reason_code;
     char *reason_string;
     int reason_length;
     struct ssh_channel *c;
-    c = find234(ssh->channels, &i, ssh_channelfind);
-    if (!c)
-       return;                        /* nonexistent channel */
-    if (c->type != CHAN_SOCKDATA_DORMANT)
-       return;                        /* dunno why they're failing this */
 
-    reason_code = ssh_pkt_getuint32(pktin);
-    if (reason_code >= lenof(reasons))
-       reason_code = 0; /* ensure reasons[reason_code] in range */
-    ssh_pkt_getstring(pktin, &reason_string, &reason_length);
-    logeventf(ssh, "Forwarded connection refused by server: %s [%.*s]",
-             reasons[reason_code], reason_length, reason_string);
-
-    pfd_close(c->u.pfd.s);
+    c = ssh2_channel_msg(ssh, pktin);
+    if (!c)
+       return;
+    if (c->type == CHAN_SHARING) {
+        share_got_pkt_from_server(c->u.sharing.ctx, pktin->type,
+                                  pktin->body, pktin->length);
+        return;
+    }
+    assert(c->halfopen); /* ssh2_channel_msg will have enforced this */
+
+    if (c->type == CHAN_SOCKDATA_DORMANT) {
+        reason_code = ssh_pkt_getuint32(pktin);
+        if (reason_code >= lenof(reasons))
+            reason_code = 0; /* ensure reasons[reason_code] in range */
+        ssh_pkt_getstring(pktin, &reason_string, &reason_length);
+        logeventf(ssh, "Forwarded connection refused by server: %s [%.*s]",
+                  reasons[reason_code], reason_length, reason_string);
+
+        pfd_close(c->u.pfd.pf);
+    } else if (c->type == CHAN_ZOMBIE) {
+        /*
+         * This case can occur if a local socket error occurred
+         * between us sending out CHANNEL_OPEN and receiving
+         * OPEN_FAILURE. In this case, we need do nothing except allow
+         * the code below to throw the half-open channel away.
+         */
+    } else {
+        /*
+         * We never expect to receive OPEN_FAILURE for any *other*
+         * channel type (since only local-to-remote port forwardings
+         * cause us to send CHANNEL_OPEN after the main channel is
+         * live - all other auxiliary channel types are initiated from
+         * the server end). It's safe to enforce this by assertion
+         * rather than by ssh_disconnect, because the real point is
+         * that we never constructed a half-open channel structure in
+         * the first place with any type other than the above.
+         */
+        assert(!"Funny channel type in ssh2_msg_channel_open_failure");
+    }
 
     del234(ssh->channels, c);
     sfree(c);
@@ -6121,28 +7980,31 @@ static void ssh2_msg_channel_open_failure(Ssh ssh, struct Packet *pktin)
 
 static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
 {
-    unsigned localid;
     char *type;
     int typelen, want_reply;
     int reply = SSH2_MSG_CHANNEL_FAILURE; /* default */
     struct ssh_channel *c;
     struct Packet *pktout;
 
-    localid = ssh_pkt_getuint32(pktin);
+    c = ssh2_channel_msg(ssh, pktin);
+    if (!c)
+       return;
+    if (c->type == CHAN_SHARING) {
+        share_got_pkt_from_server(c->u.sharing.ctx, pktin->type,
+                                  pktin->body, pktin->length);
+        return;
+    }
     ssh_pkt_getstring(pktin, &type, &typelen);
     want_reply = ssh2_pkt_getbool(pktin);
 
-    /*
-     * First, check that the channel exists. Otherwise,
-     * we can instantly disconnect with a rude message.
-     */
-    c = find234(ssh->channels, &localid, ssh_channelfind);
-    if (!c) {
-       char *buf = dupprintf("Received channel request for nonexistent"
-                             " channel %d", localid);
-       ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
-       sfree(buf);
-       return;
+    if (c->closes & CLOSES_SENT_CLOSE) {
+        /*
+         * We don't reply to channel requests after we've sent
+         * CHANNEL_CLOSE for the channel, because our reply might
+         * cross in the network with the other side's CHANNEL_CLOSE
+         * and arrive after they have wound the channel up completely.
+         */
+        want_reply = FALSE;
     }
 
     /*
@@ -6172,7 +8034,7 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
            int msglen = 0, core = FALSE;
            /* ICK: older versions of OpenSSH (e.g. 3.4p1)
             * provide an `int' for the signal, despite its
-            * having been a `string' in the drafts since at
+            * having been a `string' in the drafts of RFC 4254 since at
             * least 2001. (Fixed in session.c 1.147.) Try to
             * infer which we can safely parse it as. */
            {
@@ -6185,16 +8047,18 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
                    is_int = FALSE;
                } else {
                    int maybe_int = FALSE, maybe_str = FALSE;
-#define CHECK_HYPOTHESIS(offset, result) \
-    do { \
-       long q = offset; \
-       if (q >= 0 && q+4 <= len) { \
-           q = q + 4 + GET_32BIT(p+q); \
-           if (q >= 0 && q+4 <= len && \
-                   ((q = q + 4 + GET_32BIT(p+q))!= 0) && q == len) \
-               result = TRUE; \
-       } \
-    } while(0)
+#define CHECK_HYPOTHESIS(offset, result)                                \
+                    do                                                  \
+                    {                                                   \
+                        int q = toint(offset);                          \
+                        if (q >= 0 && q+4 <= len) {                     \
+                            q = toint(q + 4 + GET_32BIT(p+q));          \
+                            if (q >= 0 && q+4 <= len &&                 \
+                                ((q = toint(q + 4 + GET_32BIT(p+q))) != 0) && \
+                                q == len)                               \
+                                result = TRUE;                          \
+                        }                                               \
+                    } while(0)
                    CHECK_HYPOTHESIS(4+1, maybe_int);
                    CHECK_HYPOTHESIS(4+num+1, maybe_str);
 #undef CHECK_HYPOTHESIS
@@ -6207,13 +8071,15 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
                        is_plausible = FALSE;
                }
            }
+           ssh->exitcode = 128;       /* means `unknown signal' */
            if (is_plausible) {
                if (is_int) {
                    /* Old non-standard OpenSSH. */
                    int signum = ssh_pkt_getuint32(pktin);
                    fmt_sig = dupprintf(" %d", signum);
+                   ssh->exitcode = 128 + signum;
                } else {
-                   /* As per the drafts. */
+                   /* As per RFC 4254. */
                    char *sig;
                    int siglen;
                    ssh_pkt_getstring(pktin, &sig, &siglen);
@@ -6223,6 +8089,60 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
                        fmt_sig = dupprintf(" \"%.*s\"",
                                            siglen, sig);
                    }
+
+                   /*
+                    * Really hideous method of translating the
+                    * signal description back into a locally
+                    * meaningful number.
+                    */
+
+                   if (0)
+                       ;
+#define TRANSLATE_SIGNAL(s) \
+    else if (siglen == lenof(#s)-1 && !memcmp(sig, #s, siglen)) \
+        ssh->exitcode = 128 + SIG ## s
+#ifdef SIGABRT
+                   TRANSLATE_SIGNAL(ABRT);
+#endif
+#ifdef SIGALRM
+                   TRANSLATE_SIGNAL(ALRM);
+#endif
+#ifdef SIGFPE
+                   TRANSLATE_SIGNAL(FPE);
+#endif
+#ifdef SIGHUP
+                   TRANSLATE_SIGNAL(HUP);
+#endif
+#ifdef SIGILL
+                   TRANSLATE_SIGNAL(ILL);
+#endif
+#ifdef SIGINT
+                   TRANSLATE_SIGNAL(INT);
+#endif
+#ifdef SIGKILL
+                   TRANSLATE_SIGNAL(KILL);
+#endif
+#ifdef SIGPIPE
+                   TRANSLATE_SIGNAL(PIPE);
+#endif
+#ifdef SIGQUIT
+                   TRANSLATE_SIGNAL(QUIT);
+#endif
+#ifdef SIGSEGV
+                   TRANSLATE_SIGNAL(SEGV);
+#endif
+#ifdef SIGTERM
+                   TRANSLATE_SIGNAL(TERM);
+#endif
+#ifdef SIGUSR1
+                   TRANSLATE_SIGNAL(USR1);
+#endif
+#ifdef SIGUSR2
+                   TRANSLATE_SIGNAL(USR2);
+#endif
+#undef TRANSLATE_SIGNAL
+                   else
+                       ssh->exitcode = 128;
                }
                core = ssh2_pkt_getbool(pktin);
                ssh_pkt_getstring(pktin, &msg, &msglen);
@@ -6276,6 +8196,30 @@ static void ssh2_msg_global_request(Ssh ssh, struct Packet *pktin)
     }
 }
 
+struct X11FakeAuth *ssh_sharing_add_x11_display(Ssh ssh, int authtype,
+                                                void *share_cs,
+                                                void *share_chan)
+{
+    struct X11FakeAuth *auth;
+
+    /*
+     * Make up a new set of fake X11 auth data, and add it to the tree
+     * of currently valid ones with an indication of the sharing
+     * context that it's relevant to.
+     */
+    auth = x11_invent_fake_auth(ssh->x11authtree, authtype);
+    auth->share_cs = share_cs;
+    auth->share_chan = share_chan;
+
+    return auth;
+}
+
+void ssh_sharing_remove_x11_display(Ssh ssh, struct X11FakeAuth *auth)
+{
+    del234(ssh->x11authtree, auth);
+    x11_free_fake_auth(auth);
+}
+
 static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
 {
     char *type;
@@ -6286,6 +8230,7 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
     char *error = NULL;
     struct ssh_channel *c;
     unsigned remid, winsize, pktsize;
+    unsigned our_winsize_override = 0;
     struct Packet *pktout;
 
     ssh_pkt_getstring(pktin, &type, &typelen);
@@ -6308,42 +8253,69 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
        logeventf(ssh, "Received X11 connect request from %s:%d",
                  addrstr, peerport);
 
-       if (!ssh->X11_fwd_enabled)
+       if (!ssh->X11_fwd_enabled && !ssh->connshare)
            error = "X11 forwarding is not enabled";
-       else if (x11_init(&c->u.x11.s, ssh->cfg.x11_display, c,
-                         ssh->x11auth, addrstr, peerport,
-                         &ssh->cfg) != NULL) {
-           error = "Unable to open an X11 connection";
-       } else {
-           logevent("Opening X11 forward connection succeeded");
+       else {
+            c->u.x11.xconn = x11_init(ssh->x11authtree, c,
+                                      addrstr, peerport);
            c->type = CHAN_X11;
+            c->u.x11.initial = TRUE;
+
+            /*
+             * If we are a connection-sharing upstream, then we should
+             * initially present a very small window, adequate to take
+             * the X11 initial authorisation packet but not much more.
+             * Downstream will then present us a larger window (by
+             * fiat of the connection-sharing protocol) and we can
+             * guarantee to send a positive-valued WINDOW_ADJUST.
+             */
+            if (ssh->connshare)
+                our_winsize_override = 128;
+
+            logevent("Opened X11 forward channel");
        }
 
        sfree(addrstr);
     } else if (typelen == 15 &&
               !memcmp(type, "forwarded-tcpip", 15)) {
        struct ssh_rportfwd pf, *realpf;
-       char *dummy;
-       int dummylen;
-       ssh_pkt_getstring(pktin, &dummy, &dummylen);/* skip address */
+       char *shost;
+       int shostlen;
+       ssh_pkt_getstring(pktin, &shost, &shostlen);/* skip address */
+        pf.shost = dupprintf("%.*s", shostlen, shost);
        pf.sport = ssh_pkt_getuint32(pktin);
        ssh_pkt_getstring(pktin, &peeraddr, &peeraddrlen);
        peerport = ssh_pkt_getuint32(pktin);
        realpf = find234(ssh->rportfwds, &pf, NULL);
-       logeventf(ssh, "Received remote port %d open request "
-                 "from %s:%d", pf.sport, peeraddr, peerport);
+       logeventf(ssh, "Received remote port %s:%d open request "
+                 "from %s:%d", pf.shost, pf.sport, peeraddr, peerport);
+        sfree(pf.shost);
+
        if (realpf == NULL) {
            error = "Remote port is not recognised";
        } else {
-           const char *e = pfd_newconnect(&c->u.pfd.s,
-                                          realpf->dhost,
-                                          realpf->dport, c,
-                                          &ssh->cfg,
-                                          realpf->pfrec->addressfamily);
+            char *err;
+
+            if (realpf->share_ctx) {
+                /*
+                 * This port forwarding is on behalf of a
+                 * connection-sharing downstream, so abandon our own
+                 * channel-open procedure and just pass the message on
+                 * to sshshare.c.
+                 */
+                share_got_pkt_from_server(realpf->share_ctx, pktin->type,
+                                          pktin->body, pktin->length);
+                sfree(c);
+                return;
+            }
+
+            err = pfd_connect(&c->u.pfd.pf, realpf->dhost, realpf->dport,
+                              c, ssh->conf, realpf->pfrec->addressfamily);
            logeventf(ssh, "Attempting to forward remote port to "
                      "%s:%d", realpf->dhost, realpf->dport);
-           if (e != NULL) {
-               logeventf(ssh, "Port open failed: %s", e);
+           if (err != NULL) {
+               logeventf(ssh, "Port open failed: %s", err);
+                sfree(err);
                error = "Port open failed";
            } else {
                logevent("Forwarded port opened successfully");
@@ -6357,6 +8329,8 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
        else {
            c->type = CHAN_AGENT;       /* identify channel type */
            c->u.a.lensofar = 0;
+            c->u.a.message = NULL;
+            c->u.a.outstanding_requests = 0;
        }
     } else {
        error = "Unsupported channel type requested";
@@ -6374,12 +8348,13 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
        logeventf(ssh, "Rejected channel open: %s", error);
        sfree(c);
     } else {
-       c->localid = alloc_channel_id(ssh);
-       c->closes = 0;
-       c->v.v2.locwindow = OUR_V2_WINSIZE;
+       ssh2_channel_init(c);
        c->v.v2.remwindow = winsize;
        c->v.v2.remmaxpkt = pktsize;
-       bufchain_init(&c->v.v2.outbuffer);
+        if (our_winsize_override) {
+            c->v.v2.locwindow = c->v.v2.locmaxwin = c->v.v2.remlocwin =
+                our_winsize_override;
+        }
        add234(ssh->channels, c);
        pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
        ssh2_pkt_adduint32(pktout, c->remoteid);
@@ -6390,13 +8365,52 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
     }
 }
 
+void sshfwd_x11_sharing_handover(struct ssh_channel *c,
+                                 void *share_cs, void *share_chan,
+                                 const char *peer_addr, int peer_port,
+                                 int endian, int protomajor, int protominor,
+                                 const void *initial_data, int initial_len)
+{
+    /*
+     * This function is called when we've just discovered that an X
+     * forwarding channel on which we'd been handling the initial auth
+     * ourselves turns out to be destined for a connection-sharing
+     * downstream. So we turn the channel into a CHAN_SHARING, meaning
+     * that we completely stop tracking windows and buffering data and
+     * just pass more or less unmodified SSH messages back and forth.
+     */
+    c->type = CHAN_SHARING;
+    c->u.sharing.ctx = share_cs;
+    share_setup_x11_channel(share_cs, share_chan,
+                            c->localid, c->remoteid, c->v.v2.remwindow,
+                            c->v.v2.remmaxpkt, c->v.v2.locwindow,
+                            peer_addr, peer_port, endian,
+                            protomajor, protominor,
+                            initial_data, initial_len);
+}
+
+void sshfwd_x11_is_local(struct ssh_channel *c)
+{
+    /*
+     * This function is called when we've just discovered that an X
+     * forwarding channel is _not_ destined for a connection-sharing
+     * downstream but we're going to handle it ourselves. We stop
+     * presenting a cautiously small window and go into ordinary data
+     * exchange mode.
+     */
+    c->u.x11.initial = FALSE;
+    ssh2_set_window(c, ssh_is_simple(c->ssh) ? OUR_V2_BIGWIN : OUR_V2_WINSIZE);
+}
+
 /*
- * Buffer banner messages for later display at some convenient point.
+ * Buffer banner messages for later display at some convenient point,
+ * if we're going to display them.
  */
 static void ssh2_msg_userauth_banner(Ssh ssh, struct Packet *pktin)
 {
     /* Arbitrary limit to prevent unbounded inflation of buffer */
-    if (bufchain_size(&ssh->banner) <= 131072) {
+    if (conf_get_int(ssh->conf, CONF_ssh_show_banner) &&
+       bufchain_size(&ssh->banner) <= 131072) {
        char *banner = NULL;
        int size = 0;
        ssh_pkt_getstring(pktin, &banner, &size);
@@ -6425,94 +8439,499 @@ static void ssh2_send_ttymode(void *data, char *mode, char *val)
     ssh2_pkt_adduint32(pktout, arg);
 }
 
-/*
- * Handle the SSH-2 userauth and connection layers.
- */
-static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
-                            struct Packet *pktin)
+static void ssh2_setup_x11(struct ssh_channel *c, struct Packet *pktin,
+                           void *ctx)
 {
-    struct do_ssh2_authconn_state {
-       enum {
-           AUTH_INVALID, AUTH_PUBLICKEY_AGENT, AUTH_PUBLICKEY_FILE,
-               AUTH_PASSWORD,
-               AUTH_KEYBOARD_INTERACTIVE
-       } method;
-       enum {
-           AUTH_TYPE_NONE,
-               AUTH_TYPE_PUBLICKEY,
-               AUTH_TYPE_PUBLICKEY_OFFER_LOUD,
-               AUTH_TYPE_PUBLICKEY_OFFER_QUIET,
-               AUTH_TYPE_PASSWORD,
-               AUTH_TYPE_KEYBOARD_INTERACTIVE,
-               AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET
-       } type;
-       int done_service_req;
-       int gotit, need_pw, can_pubkey, can_passwd, can_keyb_inter;
-       int tried_pubkey_config, tried_agent;
-       int kbd_inter_running, kbd_inter_refused;
-       int we_are_in;
-       int num_prompts, curr_prompt, echo;
-       char username[100];
-       int got_username;
-       char pwprompt[512];
-       char password[100];
-       void *publickey_blob;
-       int publickey_bloblen;
-       unsigned char request[5], *response, *p;
-       int responselen;
-       int keyi, nkeys;
-       int authed;
-       char *pkblob, *alg, *commentp;
-       int pklen, alglen, commentlen;
-       int siglen, retlen, len;
-       char *q, *agentreq, *ret;
-       int try_send;
-       int num_env, env_left, env_ok;
-       struct Packet *pktout;
+    struct ssh2_setup_x11_state {
+       int crLine;
     };
-    crState(do_ssh2_authconn_state);
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+    crStateP(ssh2_setup_x11_state, ctx);
 
-    crBegin(ssh->do_ssh2_authconn_crstate);
+    crBeginState;
 
-    s->done_service_req = FALSE;
-    s->we_are_in = FALSE;
-    if (!ssh->cfg.ssh_no_userauth) {
-       /*
-        * Request userauth protocol, and await a response to it.
-        */
-       s->pktout = ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
-       ssh2_pkt_addstring(s->pktout, "ssh-userauth");
-       ssh2_pkt_send(ssh, s->pktout);
-       crWaitUntilV(pktin);
-       if (pktin->type == SSH2_MSG_SERVICE_ACCEPT)
-           s->done_service_req = TRUE;
+    logevent("Requesting X11 forwarding");
+    pktout = ssh2_chanreq_init(ssh->mainchan, "x11-req",
+                               ssh2_setup_x11, s);
+    ssh2_pkt_addbool(pktout, 0);              /* many connections */
+    ssh2_pkt_addstring(pktout, ssh->x11auth->protoname);
+    ssh2_pkt_addstring(pktout, ssh->x11auth->datastring);
+    ssh2_pkt_adduint32(pktout, ssh->x11disp->screennum);
+    ssh2_pkt_send(ssh, pktout);
+
+    /* Wait to be called back with either a response packet, or NULL
+     * meaning clean up and free our data */
+    crReturnV;
+
+    if (pktin) {
+        if (pktin->type == SSH2_MSG_CHANNEL_SUCCESS) {
+            logevent("X11 forwarding enabled");
+            ssh->X11_fwd_enabled = TRUE;
+        } else
+            logevent("X11 forwarding refused");
     }
-    if (!s->done_service_req) {
-       /*
-        * Request connection protocol directly, without authentication.
-        */
-       s->pktout = ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
-       ssh2_pkt_addstring(s->pktout, "ssh-connection");
-       ssh2_pkt_send(ssh, s->pktout);
-       crWaitUntilV(pktin);
-       if (pktin->type == SSH2_MSG_SERVICE_ACCEPT) {
-           s->we_are_in = TRUE; /* no auth required */
-       } else {
-           bombout(("Server refused service request"));
-           crStopV;
-       }
+
+    crFinishFreeV;
+}
+
+static void ssh2_setup_agent(struct ssh_channel *c, struct Packet *pktin,
+                                  void *ctx)
+{
+    struct ssh2_setup_agent_state {
+       int crLine;
+    };
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+    crStateP(ssh2_setup_agent_state, ctx);
+
+    crBeginState;
+
+    logevent("Requesting OpenSSH-style agent forwarding");
+    pktout = ssh2_chanreq_init(ssh->mainchan, "auth-agent-req@openssh.com",
+                               ssh2_setup_agent, s);
+    ssh2_pkt_send(ssh, pktout);
+
+    /* Wait to be called back with either a response packet, or NULL
+     * meaning clean up and free our data */
+    crReturnV;
+
+    if (pktin) {
+        if (pktin->type == SSH2_MSG_CHANNEL_SUCCESS) {
+            logevent("Agent forwarding enabled");
+            ssh->agentfwd_enabled = TRUE;
+        } else
+            logevent("Agent forwarding refused");
     }
 
-    /*
-     * We repeat this whole loop, including the username prompt,
-     * until we manage a successful authentication. If the user
-     * types the wrong _password_, they can be sent back to the
-     * beginning to try another username, if this is configured on.
-     * (If they specify a username in the config, they are never
-     * asked, even if they do give a wrong password.)
-     * 
-     * I think this best serves the needs of
-     * 
+    crFinishFreeV;
+}
+
+static void ssh2_setup_pty(struct ssh_channel *c, struct Packet *pktin,
+                                void *ctx)
+{
+    struct ssh2_setup_pty_state {
+       int crLine;
+    };
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+    crStateP(ssh2_setup_pty_state, ctx);
+
+    crBeginState;
+
+    /* Unpick the terminal-speed string. */
+    /* XXX perhaps we should allow no speeds to be sent. */
+    ssh->ospeed = 38400; ssh->ispeed = 38400; /* last-resort defaults */
+    sscanf(conf_get_str(ssh->conf, CONF_termspeed), "%d,%d", &ssh->ospeed, &ssh->ispeed);
+    /* Build the pty request. */
+    pktout = ssh2_chanreq_init(ssh->mainchan, "pty-req",
+                               ssh2_setup_pty, s);
+    ssh2_pkt_addstring(pktout, conf_get_str(ssh->conf, CONF_termtype));
+    ssh2_pkt_adduint32(pktout, ssh->term_width);
+    ssh2_pkt_adduint32(pktout, ssh->term_height);
+    ssh2_pkt_adduint32(pktout, 0);            /* pixel width */
+    ssh2_pkt_adduint32(pktout, 0);            /* pixel height */
+    ssh2_pkt_addstring_start(pktout);
+    parse_ttymodes(ssh, ssh2_send_ttymode, (void *)pktout);
+    ssh2_pkt_addbyte(pktout, SSH2_TTY_OP_ISPEED);
+    ssh2_pkt_adduint32(pktout, ssh->ispeed);
+    ssh2_pkt_addbyte(pktout, SSH2_TTY_OP_OSPEED);
+    ssh2_pkt_adduint32(pktout, ssh->ospeed);
+    ssh2_pkt_addstring_data(pktout, "\0", 1); /* TTY_OP_END */
+    ssh2_pkt_send(ssh, pktout);
+    ssh->state = SSH_STATE_INTERMED;
+
+    /* Wait to be called back with either a response packet, or NULL
+     * meaning clean up and free our data */
+    crReturnV;
+
+    if (pktin) {
+        if (pktin->type == SSH2_MSG_CHANNEL_SUCCESS) {
+            logeventf(ssh, "Allocated pty (ospeed %dbps, ispeed %dbps)",
+                      ssh->ospeed, ssh->ispeed);
+            ssh->got_pty = TRUE;
+        } else {
+            c_write_str(ssh, "Server refused to allocate pty\r\n");
+            ssh->editing = ssh->echoing = 1;
+        }
+    }
+
+    crFinishFreeV;
+}
+
+static void ssh2_setup_env(struct ssh_channel *c, struct Packet *pktin,
+                          void *ctx)
+{
+    struct ssh2_setup_env_state {
+       int crLine;
+       int num_env, env_left, env_ok;
+    };
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+    crStateP(ssh2_setup_env_state, ctx);
+
+    crBeginState;
+
+    /*
+     * Send environment variables.
+     * 
+     * Simplest thing here is to send all the requests at once, and
+     * then wait for a whole bunch of successes or failures.
+     */
+    s->num_env = 0;
+    {
+       char *key, *val;
+
+       for (val = conf_get_str_strs(ssh->conf, CONF_environmt, NULL, &key);
+            val != NULL;
+            val = conf_get_str_strs(ssh->conf, CONF_environmt, key, &key)) {
+           pktout = ssh2_chanreq_init(ssh->mainchan, "env", ssh2_setup_env, s);
+           ssh2_pkt_addstring(pktout, key);
+           ssh2_pkt_addstring(pktout, val);
+           ssh2_pkt_send(ssh, pktout);
+
+           s->num_env++;
+       }
+       if (s->num_env)
+           logeventf(ssh, "Sent %d environment variables", s->num_env);
+    }
+
+    if (s->num_env) {
+       s->env_ok = 0;
+       s->env_left = s->num_env;
+
+       while (s->env_left > 0) {
+            /* Wait to be called back with either a response packet,
+             * or NULL meaning clean up and free our data */
+            crReturnV;
+           if (!pktin) goto out;
+           if (pktin->type == SSH2_MSG_CHANNEL_SUCCESS)
+               s->env_ok++;
+           s->env_left--;
+       }
+
+       if (s->env_ok == s->num_env) {
+           logevent("All environment variables successfully set");
+       } else if (s->env_ok == 0) {
+           logevent("All environment variables refused");
+           c_write_str(ssh, "Server refused to set environment variables\r\n");
+       } else {
+           logeventf(ssh, "%d environment variables refused",
+                     s->num_env - s->env_ok);
+           c_write_str(ssh, "Server refused to set all environment variables\r\n");
+       }
+    }
+  out:;
+    crFinishFreeV;
+}
+
+/*
+ * Handle the SSH-2 userauth and connection layers.
+ */
+static void ssh2_msg_authconn(Ssh ssh, struct Packet *pktin)
+{
+    do_ssh2_authconn(ssh, NULL, 0, pktin);
+}
+
+static void ssh2_response_authconn(struct ssh_channel *c, struct Packet *pktin,
+                                  void *ctx)
+{
+    if (pktin)
+        do_ssh2_authconn(c->ssh, NULL, 0, pktin);
+}
+
+static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
+                            struct Packet *pktin)
+{
+    struct do_ssh2_authconn_state {
+       int crLine;
+       enum {
+           AUTH_TYPE_NONE,
+               AUTH_TYPE_PUBLICKEY,
+               AUTH_TYPE_PUBLICKEY_OFFER_LOUD,
+               AUTH_TYPE_PUBLICKEY_OFFER_QUIET,
+               AUTH_TYPE_PASSWORD,
+               AUTH_TYPE_GSSAPI,      /* always QUIET */
+               AUTH_TYPE_KEYBOARD_INTERACTIVE,
+               AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET
+       } type;
+       int done_service_req;
+       int gotit, need_pw, can_pubkey, can_passwd, can_keyb_inter;
+       int tried_pubkey_config, done_agent;
+#ifndef NO_GSSAPI
+       int can_gssapi;
+       int tried_gssapi;
+#endif
+       int kbd_inter_refused;
+       int we_are_in, userauth_success;
+       prompts_t *cur_prompt;
+       int num_prompts;
+       char *username;
+       char *password;
+       int got_username;
+       void *publickey_blob;
+       int publickey_bloblen;
+       int publickey_encrypted;
+       char *publickey_algorithm;
+       char *publickey_comment;
+       unsigned char agent_request[5], *agent_response, *agentp;
+       int agent_responselen;
+       unsigned char *pkblob_in_agent;
+       int keyi, nkeys;
+       char *pkblob, *alg, *commentp;
+       int pklen, alglen, commentlen;
+       int siglen, retlen, len;
+       char *q, *agentreq, *ret;
+       int try_send;
+       struct Packet *pktout;
+       Filename *keyfile;
+#ifndef NO_GSSAPI
+       struct ssh_gss_library *gsslib;
+       Ssh_gss_ctx gss_ctx;
+       Ssh_gss_buf gss_buf;
+       Ssh_gss_buf gss_rcvtok, gss_sndtok;
+       Ssh_gss_name gss_srv_name;
+       Ssh_gss_stat gss_stat;
+#endif
+    };
+    crState(do_ssh2_authconn_state);
+
+    crBeginState;
+
+    /* Register as a handler for all the messages this coroutine handles. */
+    ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = ssh2_msg_authconn;
+    /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = ssh2_msg_authconn; duplicate case value */
+    /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = ssh2_msg_authconn; duplicate case value */
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_authconn;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_authconn;
+    
+    s->done_service_req = FALSE;
+    s->we_are_in = s->userauth_success = FALSE;
+    s->agent_response = NULL;
+#ifndef NO_GSSAPI
+    s->tried_gssapi = FALSE;
+#endif
+
+    if (!ssh->bare_connection) {
+        if (!conf_get_int(ssh->conf, CONF_ssh_no_userauth)) {
+            /*
+             * Request userauth protocol, and await a response to it.
+             */
+            s->pktout = ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
+            ssh2_pkt_addstring(s->pktout, "ssh-userauth");
+            ssh2_pkt_send(ssh, s->pktout);
+            crWaitUntilV(pktin);
+            if (pktin->type == SSH2_MSG_SERVICE_ACCEPT)
+                s->done_service_req = TRUE;
+        }
+        if (!s->done_service_req) {
+            /*
+             * Request connection protocol directly, without authentication.
+             */
+            s->pktout = ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
+            ssh2_pkt_addstring(s->pktout, "ssh-connection");
+            ssh2_pkt_send(ssh, s->pktout);
+            crWaitUntilV(pktin);
+            if (pktin->type == SSH2_MSG_SERVICE_ACCEPT) {
+                s->we_are_in = TRUE; /* no auth required */
+            } else {
+                bombout(("Server refused service request"));
+                crStopV;
+            }
+        }
+    } else {
+        s->we_are_in = TRUE;
+    }
+
+    /* Arrange to be able to deal with any BANNERs that come in.
+     * (We do this now as packets may come in during the next bit.) */
+    bufchain_init(&ssh->banner);
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] =
+       ssh2_msg_userauth_banner;
+
+    /*
+     * Misc one-time setup for authentication.
+     */
+    s->publickey_blob = NULL;
+    if (!s->we_are_in) {
+
+       /*
+        * Load the public half of any configured public key file
+        * for later use.
+        */
+       s->keyfile = conf_get_filename(ssh->conf, CONF_keyfile);
+       if (!filename_is_null(s->keyfile)) {
+           int keytype;
+           logeventf(ssh, "Reading private key file \"%.150s\"",
+                     filename_to_str(s->keyfile));
+           keytype = key_type(s->keyfile);
+           if (keytype == SSH_KEYTYPE_SSH2) {
+               const char *error;
+               s->publickey_blob =
+                   ssh2_userkey_loadpub(s->keyfile,
+                                        &s->publickey_algorithm,
+                                        &s->publickey_bloblen, 
+                                        &s->publickey_comment, &error);
+               if (s->publickey_blob) {
+                   s->publickey_encrypted =
+                       ssh2_userkey_encrypted(s->keyfile, NULL);
+               } else {
+                   char *msgbuf;
+                   logeventf(ssh, "Unable to load private key (%s)", 
+                             error);
+                   msgbuf = dupprintf("Unable to load private key file "
+                                      "\"%.150s\" (%s)\r\n",
+                                      filename_to_str(s->keyfile),
+                                      error);
+                   c_write_str(ssh, msgbuf);
+                   sfree(msgbuf);
+               }
+           } else {
+               char *msgbuf;
+               logeventf(ssh, "Unable to use this key file (%s)",
+                         key_type_to_str(keytype));
+               msgbuf = dupprintf("Unable to use key file \"%.150s\""
+                                  " (%s)\r\n",
+                                  filename_to_str(s->keyfile),
+                                  key_type_to_str(keytype));
+               c_write_str(ssh, msgbuf);
+               sfree(msgbuf);
+               s->publickey_blob = NULL;
+           }
+       }
+
+       /*
+        * Find out about any keys Pageant has (but if there's a
+        * public key configured, filter out all others).
+        */
+       s->nkeys = 0;
+       s->agent_response = NULL;
+       s->pkblob_in_agent = NULL;
+       if (conf_get_int(ssh->conf, CONF_tryagent) && agent_exists()) {
+
+           void *r;
+
+           logevent("Pageant is running. Requesting keys.");
+
+           /* Request the keys held by the agent. */
+           PUT_32BIT(s->agent_request, 1);
+           s->agent_request[4] = SSH2_AGENTC_REQUEST_IDENTITIES;
+           if (!agent_query(s->agent_request, 5, &r, &s->agent_responselen,
+                            ssh_agent_callback, ssh)) {
+               do {
+                   crReturnV;
+                   if (pktin) {
+                       bombout(("Unexpected data from server while"
+                                " waiting for agent response"));
+                       crStopV;
+                   }
+               } while (pktin || inlen > 0);
+               r = ssh->agent_response;
+               s->agent_responselen = ssh->agent_response_len;
+           }
+           s->agent_response = (unsigned char *) r;
+           if (s->agent_response && s->agent_responselen >= 5 &&
+               s->agent_response[4] == SSH2_AGENT_IDENTITIES_ANSWER) {
+               int keyi;
+               unsigned char *p;
+               p = s->agent_response + 5;
+               s->nkeys = toint(GET_32BIT(p));
+
+                /*
+                 * Vet the Pageant response to ensure that the key
+                 * count and blob lengths make sense.
+                 */
+                if (s->nkeys < 0) {
+                    logeventf(ssh, "Pageant response contained a negative"
+                              " key count %d", s->nkeys);
+                    s->nkeys = 0;
+                    goto done_agent_query;
+                } else {
+                    unsigned char *q = p + 4;
+                    int lenleft = s->agent_responselen - 5 - 4;
+
+                    for (keyi = 0; keyi < s->nkeys; keyi++) {
+                        int bloblen, commentlen;
+                        if (lenleft < 4) {
+                            logeventf(ssh, "Pageant response was truncated");
+                            s->nkeys = 0;
+                            goto done_agent_query;
+                        }
+                        bloblen = toint(GET_32BIT(q));
+                        if (bloblen < 0 || bloblen > lenleft) {
+                            logeventf(ssh, "Pageant response was truncated");
+                            s->nkeys = 0;
+                            goto done_agent_query;
+                        }
+                        lenleft -= 4 + bloblen;
+                        q += 4 + bloblen;
+                        commentlen = toint(GET_32BIT(q));
+                        if (commentlen < 0 || commentlen > lenleft) {
+                            logeventf(ssh, "Pageant response was truncated");
+                            s->nkeys = 0;
+                            goto done_agent_query;
+                        }
+                        lenleft -= 4 + commentlen;
+                        q += 4 + commentlen;
+                    }
+                }
+
+               p += 4;
+               logeventf(ssh, "Pageant has %d SSH-2 keys", s->nkeys);
+               if (s->publickey_blob) {
+                   /* See if configured key is in agent. */
+                   for (keyi = 0; keyi < s->nkeys; keyi++) {
+                       s->pklen = toint(GET_32BIT(p));
+                       if (s->pklen == s->publickey_bloblen &&
+                           !memcmp(p+4, s->publickey_blob,
+                                   s->publickey_bloblen)) {
+                           logeventf(ssh, "Pageant key #%d matches "
+                                     "configured key file", keyi);
+                           s->keyi = keyi;
+                           s->pkblob_in_agent = p;
+                           break;
+                       }
+                       p += 4 + s->pklen;
+                       p += toint(GET_32BIT(p)) + 4; /* comment */
+                   }
+                   if (!s->pkblob_in_agent) {
+                       logevent("Configured key file not in Pageant");
+                       s->nkeys = 0;
+                   }
+               }
+           } else {
+                logevent("Failed to get reply from Pageant");
+           }
+          done_agent_query:;
+       }
+
+    }
+
+    /*
+     * We repeat this whole loop, including the username prompt,
+     * until we manage a successful authentication. If the user
+     * types the wrong _password_, they can be sent back to the
+     * beginning to try another username, if this is configured on.
+     * (If they specify a username in the config, they are never
+     * asked, even if they do give a wrong password.)
+     * 
+     * I think this best serves the needs of
+     * 
      *  - the people who have no configuration, no keys, and just
      *    want to try repeated (username,password) pairs until they
      *    type both correctly
@@ -6527,52 +8946,45 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
      *    the username they will want to be able to get back and
      *    retype it!
      */
-    s->username[0] = '\0';
     s->got_username = FALSE;
-    bufchain_init(&ssh->banner);
-    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] =
-       ssh2_msg_userauth_banner;
     while (!s->we_are_in) {
        /*
         * Get a username.
         */
-       if (s->got_username && !ssh->cfg.change_username) {
+       if (s->got_username && !conf_get_int(ssh->conf, CONF_change_username)) {
            /*
             * We got a username last time round this loop, and
             * with change_username turned off we don't try to get
             * it again.
             */
-       } else if (!*ssh->cfg.username) {
-           if (ssh_get_line && !ssh_getline_pw_only) {
-               if (!ssh_get_line("login as: ",
-                                 s->username, sizeof(s->username), FALSE)) {
-                   /*
-                    * get_line failed to get a username.
-                    * Terminate.
-                    */
-                   ssh_disconnect(ssh, "No username provided", NULL, 0, TRUE);
-                   crStopV;
-               }
-           } else {
-               int ret;               /* need not be saved across crReturn */
-               c_write_str(ssh, "login as: ");
+       } else if ((ssh->username = get_remote_username(ssh->conf)) == NULL) {
+           int ret; /* need not be kept over crReturn */
+           s->cur_prompt = new_prompts(ssh->frontend);
+           s->cur_prompt->to_server = TRUE;
+           s->cur_prompt->name = dupstr("SSH login name");
+           add_prompt(s->cur_prompt, dupstr("login as: "), TRUE); 
+           ret = get_userpass_input(s->cur_prompt, NULL, 0);
+           while (ret < 0) {
                ssh->send_ok = 1;
-               setup_userpass_input(ssh, s->username, sizeof(s->username), 1);
-               do {
-                   crWaitUntilV(!pktin);
-                   ret = process_userpass_input(ssh, in, inlen);
-               } while (ret == 0);
-               if (ret < 0)
-                   cleanup_exit(0);
-               c_write_str(ssh, "\r\n");
+               crWaitUntilV(!pktin);
+               ret = get_userpass_input(s->cur_prompt, in, inlen);
+               ssh->send_ok = 0;
            }
-           s->username[strcspn(s->username, "\n\r")] = '\0';
+           if (!ret) {
+               /*
+                * get_userpass_input() failed to get a username.
+                * Terminate.
+                */
+               free_prompts(s->cur_prompt);
+               ssh_disconnect(ssh, "No username provided", NULL, 0, TRUE);
+               crStopV;
+           }
+           ssh->username = dupstr(s->cur_prompt->prompts[0]->result);
+           free_prompts(s->cur_prompt);
        } else {
            char *stuff;
-           strncpy(s->username, ssh->cfg.username, sizeof(s->username));
-           s->username[sizeof(s->username)-1] = '\0';
            if ((flags & FLAG_VERBOSE) || (flags & FLAG_INTERACTIVE)) {
-               stuff = dupprintf("Using username \"%s\".\r\n", s->username);
+               stuff = dupprintf("Using username \"%s\".\r\n", ssh->username);
                c_write_str(ssh, stuff);
                sfree(stuff);
            }
@@ -6584,10 +8996,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
         * just in case it succeeds, and (b) so that we know what
         * authentication methods we can usefully try next.
         */
-       ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
+       ssh->pkt_actx = SSH2_PKTCTX_NOAUTH;
 
        s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-       ssh2_pkt_addstring(s->pktout, s->username);
+       ssh2_pkt_addstring(s->pktout, ssh->username);
        ssh2_pkt_addstring(s->pktout, "ssh-connection");/* service requested */
        ssh2_pkt_addstring(s->pktout, "none");    /* method */
        ssh2_pkt_send(ssh, s->pktout);
@@ -6596,35 +9008,23 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        s->we_are_in = FALSE;
 
        s->tried_pubkey_config = FALSE;
-       s->tried_agent = FALSE;
-       s->kbd_inter_running = FALSE;
        s->kbd_inter_refused = FALSE;
-       /* Load the pub half of ssh->cfg.keyfile so we notice if it's in Pageant */
-       if (!filename_is_null(ssh->cfg.keyfile)) {
-           int keytype;
-           logeventf(ssh, "Reading private key file \"%.150s\"",
-                     filename_to_str(&ssh->cfg.keyfile));
-           keytype = key_type(&ssh->cfg.keyfile);
-           if (keytype == SSH_KEYTYPE_SSH2) {
-               s->publickey_blob =
-                   ssh2_userkey_loadpub(&ssh->cfg.keyfile, NULL,
-                                        &s->publickey_bloblen, NULL);
+
+       /* Reset agent request state. */
+       s->done_agent = FALSE;
+       if (s->agent_response) {
+           if (s->pkblob_in_agent) {
+               s->agentp = s->pkblob_in_agent;
            } else {
-               char *msgbuf;
-               logeventf(ssh, "Unable to use this key file (%s)",
-                         key_type_to_str(keytype));
-               msgbuf = dupprintf("Unable to use key file \"%.150s\""
-                                  " (%s)\r\n",
-                                  filename_to_str(&ssh->cfg.keyfile),
-                                  key_type_to_str(keytype));
-               c_write_str(ssh, msgbuf);
-               sfree(msgbuf);
-               s->publickey_blob = NULL;
+               s->agentp = s->agent_response + 5 + 4;
+               s->keyi = 0;
            }
-       } else
-           s->publickey_blob = NULL;
+       }
 
        while (1) {
+           char *methods = NULL;
+           int methlen = 0;
+
            /*
             * Wait for the result of the last authentication request.
             */
@@ -6656,28 +9056,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
            }
            if (pktin->type == SSH2_MSG_USERAUTH_SUCCESS) {
                logevent("Access granted");
-               s->we_are_in = TRUE;
+               s->we_are_in = s->userauth_success = TRUE;
                break;
            }
 
-           if (s->kbd_inter_running &&
-               pktin->type == SSH2_MSG_USERAUTH_INFO_REQUEST) {
-               /*
-                * This is either a further set-of-prompts packet
-                * in keyboard-interactive authentication, or it's
-                * the same one and we came back here with `gotit'
-                * set. In the former case, we must reset the
-                * curr_prompt variable.
-                */
-               if (!s->gotit)
-                   s->curr_prompt = 0;
-           } else if (pktin->type == SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ) {
-               /* FIXME: perhaps we should support this? */
-               bombout(("PASSWD_CHANGEREQ not yet supported"));
-               crStopV;
-           } else if (pktin->type != SSH2_MSG_USERAUTH_FAILURE) {
-               bombout(("Strange packet received during authentication: type %d",
-                        pktin->type));
+           if (pktin->type != SSH2_MSG_USERAUTH_FAILURE && s->type != AUTH_TYPE_GSSAPI) {
+               bombout(("Strange packet received during authentication: "
+                        "type %d", pktin->type));
                crStopV;
            }
 
@@ -6689,27 +9074,25 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
             * helpfully try next.
             */
            if (pktin->type == SSH2_MSG_USERAUTH_FAILURE) {
-               char *methods;
-               int methlen;
                ssh_pkt_getstring(pktin, &methods, &methlen);
-               s->kbd_inter_running = FALSE;
                if (!ssh2_pkt_getbool(pktin)) {
                    /*
                     * We have received an unequivocal Access
                     * Denied. This can translate to a variety of
-                    * messages:
-                    * 
-                    *  - if we'd just tried "none" authentication,
-                    *    it's not worth printing anything at all
-                    * 
-                    *  - if we'd just tried a public key _offer_,
-                    *    the message should be "Server refused our
-                    *    key" (or no message at all if the key
-                    *    came from Pageant)
-                    * 
-                    *  - if we'd just tried anything else, the
-                    *    message really should be "Access denied".
-                    * 
+                    * messages, or no message at all.
+                     *
+                     * For forms of authentication which are attempted
+                     * implicitly, by which I mean without printing
+                     * anything in the window indicating that we're
+                     * trying them, we should never print 'Access
+                     * denied'.
+                     *
+                     * If we do print a message saying that we're
+                     * attempting some kind of authentication, it's OK
+                     * to print a followup message saying it failed -
+                     * but the message may sometimes be more specific
+                     * than simply 'Access denied'.
+                     *
                     * Additionally, if we'd just tried password
                     * authentication, we should break out of this
                     * whole loop so as to go back to the username
@@ -6722,14 +9105,31 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                               s->type == AUTH_TYPE_PUBLICKEY_OFFER_QUIET) {
                        if (s->type == AUTH_TYPE_PUBLICKEY_OFFER_LOUD)
                            c_write_str(ssh, "Server refused our key\r\n");
-                       logevent("Server refused public key");
+                       logevent("Server refused our key");
+                    } else if (s->type == AUTH_TYPE_PUBLICKEY) {
+                        /* This _shouldn't_ happen except by a
+                         * protocol bug causing client and server to
+                         * disagree on what is a correct signature. */
+                        c_write_str(ssh, "Server refused public-key signature"
+                                    " despite accepting key!\r\n");
+                        logevent("Server refused public-key signature"
+                                 " despite accepting key!");
                    } else if (s->type==AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET) {
-                       /* server declined keyboard-interactive; ignore */
-                   } else {
+                        /* quiet, so no c_write */
+                        logevent("Server refused keyboard-interactive authentication");
+                   } else if (s->type==AUTH_TYPE_GSSAPI) {
+                       /* always quiet, so no c_write */
+                        /* also, the code down in the GSSAPI block has
+                         * already logged this in the Event Log */
+                   } else if (s->type == AUTH_TYPE_KEYBOARD_INTERACTIVE) {
+                        logevent("Keyboard-interactive authentication failed");
                        c_write_str(ssh, "Access denied\r\n");
-                       logevent("Access denied");
-                       if (s->type == AUTH_TYPE_PASSWORD &&
-                           ssh->cfg.change_username) {
+                    } else {
+                        assert(s->type == AUTH_TYPE_PASSWORD);
+                        logevent("Password authentication failed");
+                       c_write_str(ssh, "Access denied\r\n");
+
+                       if (conf_get_int(ssh->conf, CONF_change_username)) {
                            /* XXX perhaps we should allow
                             * keyboard-interactive to do this too? */
                            s->we_are_in = FALSE;
@@ -6745,198 +9145,177 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                    in_commasep_string("publickey", methods, methlen);
                s->can_passwd =
                    in_commasep_string("password", methods, methlen);
-               s->can_keyb_inter = ssh->cfg.try_ki_auth &&
+               s->can_keyb_inter = conf_get_int(ssh->conf, CONF_try_ki_auth) &&
                    in_commasep_string("keyboard-interactive", methods, methlen);
+#ifndef NO_GSSAPI
+               if (!ssh->gsslibs)
+                   ssh->gsslibs = ssh_gss_setup(ssh->conf);
+               s->can_gssapi = conf_get_int(ssh->conf, CONF_try_gssapi_auth) &&
+                   in_commasep_string("gssapi-with-mic", methods, methlen) &&
+                   ssh->gsslibs->nlibraries > 0;
+#endif
            }
 
-           s->method = 0;
-           ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-           s->need_pw = FALSE;
+           ssh->pkt_actx = SSH2_PKTCTX_NOAUTH;
 
-           /*
-            * Most password/passphrase prompts will be
-            * non-echoing, so we set this to 0 by default.
-            * Exception is that some keyboard-interactive prompts
-            * can be echoing, in which case we'll set this to 1.
-            */
-           s->echo = 0;
+           if (s->can_pubkey && !s->done_agent && s->nkeys) {
 
-           if (!s->method && s->can_pubkey &&
-               agent_exists() && !s->tried_agent) {
                /*
-                * Attempt public-key authentication using Pageant.
+                * Attempt public-key authentication using a key from Pageant.
                 */
-               void *r;
-               s->authed = FALSE;
-
-               ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-               ssh->pkt_ctx |= SSH2_PKTCTX_PUBLICKEY;
-
-               s->tried_agent = TRUE;
-
-               logevent("Pageant is running. Requesting keys.");
-
-               /* Request the keys held by the agent. */
-               PUT_32BIT(s->request, 1);
-               s->request[4] = SSH2_AGENTC_REQUEST_IDENTITIES;
-               if (!agent_query(s->request, 5, &r, &s->responselen,
-                                ssh_agent_callback, ssh)) {
-                   do {
-                       crReturnV;
-                       if (pktin) {
-                           bombout(("Unexpected data from server while"
-                                    " waiting for agent response"));
-                           crStopV;
-                       }
-                   } while (pktin || inlen > 0);
-                   r = ssh->agent_response;
-                   s->responselen = ssh->agent_response_len;
-               }
-               s->response = (unsigned char *) r;
-               if (s->response && s->responselen >= 5 &&
-                   s->response[4] == SSH2_AGENT_IDENTITIES_ANSWER) {
-                   s->p = s->response + 5;
-                   s->nkeys = GET_32BIT(s->p);
-                   s->p += 4;
-                   logeventf(ssh, "Pageant has %d SSH-2 keys", s->nkeys);
-                   for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
-                       void *vret;
 
-                       logeventf(ssh, "Trying Pageant key #%d", s->keyi);
-                       s->pklen = GET_32BIT(s->p);
-                       s->p += 4;
-                       if (s->publickey_blob &&
-                           s->pklen == s->publickey_bloblen &&
-                           !memcmp(s->p, s->publickey_blob,
-                                   s->publickey_bloblen)) {
-                           logevent("This key matches configured key file");
-                           s->tried_pubkey_config = 1;
-                       }
-                       s->pkblob = (char *)s->p;
-                       s->p += s->pklen;
-                       s->alglen = GET_32BIT(s->pkblob);
-                       s->alg = s->pkblob + 4;
-                       s->commentlen = GET_32BIT(s->p);
-                       s->p += 4;
-                       s->commentp = (char *)s->p;
-                       s->p += s->commentlen;
-                       s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-                       ssh2_pkt_addstring(s->pktout, s->username);
-                       ssh2_pkt_addstring(s->pktout, "ssh-connection");        /* service requested */
-                       ssh2_pkt_addstring(s->pktout, "publickey");     /* method */
-                       ssh2_pkt_addbool(s->pktout, FALSE);     /* no signature included */
-                       ssh2_pkt_addstring_start(s->pktout);
-                       ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
-                       ssh2_pkt_addstring_start(s->pktout);
-                       ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
-                       ssh2_pkt_send(ssh, s->pktout);
+               ssh->pkt_actx = SSH2_PKTCTX_PUBLICKEY;
 
-                       crWaitUntilV(pktin);
-                       if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
-                           logevent("Key refused");
-                           continue;
-                       }
+               logeventf(ssh, "Trying Pageant key #%d", s->keyi);
 
-                       if (flags & FLAG_VERBOSE) {
-                           c_write_str(ssh, "Authenticating with "
-                                       "public key \"");
-                           c_write(ssh, s->commentp, s->commentlen);
-                           c_write_str(ssh, "\" from agent\r\n");
-                       }
+               /* Unpack key from agent response */
+               s->pklen = toint(GET_32BIT(s->agentp));
+               s->agentp += 4;
+               s->pkblob = (char *)s->agentp;
+               s->agentp += s->pklen;
+               s->alglen = toint(GET_32BIT(s->pkblob));
+               s->alg = s->pkblob + 4;
+               s->commentlen = toint(GET_32BIT(s->agentp));
+               s->agentp += 4;
+               s->commentp = (char *)s->agentp;
+               s->agentp += s->commentlen;
+               /* s->agentp now points at next key, if any */
 
-                       /*
-                        * Server is willing to accept the key.
-                        * Construct a SIGN_REQUEST.
-                        */
-                       s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-                       ssh2_pkt_addstring(s->pktout, s->username);
-                       ssh2_pkt_addstring(s->pktout, "ssh-connection");        /* service requested */
-                       ssh2_pkt_addstring(s->pktout, "publickey");     /* method */
-                       ssh2_pkt_addbool(s->pktout, TRUE);
-                       ssh2_pkt_addstring_start(s->pktout);
-                       ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
-                       ssh2_pkt_addstring_start(s->pktout);
-                       ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
-
-                       s->siglen = s->pktout->length - 5 + 4 + 20;
-                        if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
-                            s->siglen -= 4;
-                       s->len = 1;       /* message type */
-                       s->len += 4 + s->pklen; /* key blob */
-                       s->len += 4 + s->siglen;        /* data to sign */
-                       s->len += 4;      /* flags */
-                       s->agentreq = snewn(4 + s->len, char);
-                       PUT_32BIT(s->agentreq, s->len);
-                       s->q = s->agentreq + 4;
-                       *s->q++ = SSH2_AGENTC_SIGN_REQUEST;
-                       PUT_32BIT(s->q, s->pklen);
-                       s->q += 4;
-                       memcpy(s->q, s->pkblob, s->pklen);
-                       s->q += s->pklen;
-                       PUT_32BIT(s->q, s->siglen);
+               /* See if server will accept it */
+               s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+               ssh2_pkt_addstring(s->pktout, ssh->username);
+               ssh2_pkt_addstring(s->pktout, "ssh-connection");
+                                                   /* service requested */
+               ssh2_pkt_addstring(s->pktout, "publickey");
+                                                   /* method */
+               ssh2_pkt_addbool(s->pktout, FALSE); /* no signature included */
+               ssh2_pkt_addstring_start(s->pktout);
+               ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
+               ssh2_pkt_addstring_start(s->pktout);
+               ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
+               ssh2_pkt_send(ssh, s->pktout);
+               s->type = AUTH_TYPE_PUBLICKEY_OFFER_QUIET;
+
+               crWaitUntilV(pktin);
+               if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
+
+                   /* Offer of key refused. */
+                   s->gotit = TRUE;
+
+               } else {
+                   
+                   void *vret;
+
+                   if (flags & FLAG_VERBOSE) {
+                       c_write_str(ssh, "Authenticating with "
+                                   "public key \"");
+                       c_write(ssh, s->commentp, s->commentlen);
+                       c_write_str(ssh, "\" from agent\r\n");
+                   }
+
+                   /*
+                    * Server is willing to accept the key.
+                    * Construct a SIGN_REQUEST.
+                    */
+                   s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+                   ssh2_pkt_addstring(s->pktout, ssh->username);
+                   ssh2_pkt_addstring(s->pktout, "ssh-connection");
+                                                       /* service requested */
+                   ssh2_pkt_addstring(s->pktout, "publickey");
+                                                       /* method */
+                   ssh2_pkt_addbool(s->pktout, TRUE);  /* signature included */
+                   ssh2_pkt_addstring_start(s->pktout);
+                   ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
+                   ssh2_pkt_addstring_start(s->pktout);
+                   ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
+
+                   /* Ask agent for signature. */
+                   s->siglen = s->pktout->length - 5 + 4 +
+                       ssh->v2_session_id_len;
+                   if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
+                       s->siglen -= 4;
+                   s->len = 1;       /* message type */
+                   s->len += 4 + s->pklen;     /* key blob */
+                   s->len += 4 + s->siglen;    /* data to sign */
+                   s->len += 4;      /* flags */
+                   s->agentreq = snewn(4 + s->len, char);
+                   PUT_32BIT(s->agentreq, s->len);
+                   s->q = s->agentreq + 4;
+                   *s->q++ = SSH2_AGENTC_SIGN_REQUEST;
+                   PUT_32BIT(s->q, s->pklen);
+                   s->q += 4;
+                   memcpy(s->q, s->pkblob, s->pklen);
+                   s->q += s->pklen;
+                   PUT_32BIT(s->q, s->siglen);
+                   s->q += 4;
+                   /* Now the data to be signed... */
+                   if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
+                       PUT_32BIT(s->q, ssh->v2_session_id_len);
                        s->q += 4;
-                       /* Now the data to be signed... */
-                        if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
-                            PUT_32BIT(s->q, 20);
-                            s->q += 4;
-                        }
-                       memcpy(s->q, ssh->v2_session_id, 20);
-                       s->q += 20;
-                       memcpy(s->q, s->pktout->data + 5,
-                              s->pktout->length - 5);
-                       s->q += s->pktout->length - 5;
-                       /* And finally the (zero) flags word. */
-                       PUT_32BIT(s->q, 0);
-                       if (!agent_query(s->agentreq, s->len + 4,
-                                        &vret, &s->retlen,
-                                        ssh_agent_callback, ssh)) {
-                           do {
-                               crReturnV;
-                               if (pktin) {
-                                   bombout(("Unexpected data from server"
-                                            " while waiting for agent"
-                                            " response"));
-                                   crStopV;
-                               }
-                           } while (pktin || inlen > 0);
-                           vret = ssh->agent_response;
-                           s->retlen = ssh->agent_response_len;
-                       }
-                       s->ret = vret;
-                       sfree(s->agentreq);
-                       if (s->ret) {
-                           if (s->ret[4] == SSH2_AGENT_SIGN_RESPONSE) {
-                               logevent("Sending Pageant's response");
-                               ssh2_add_sigblob(ssh, s->pktout,
-                                                s->pkblob, s->pklen,
-                                                s->ret + 9,
-                                                GET_32BIT(s->ret + 5));
-                               ssh2_pkt_send(ssh, s->pktout);
-                               s->authed = TRUE;
-                               break;
-                           } else {
-                               logevent
-                                   ("Pageant failed to answer challenge");
-                               sfree(s->ret);
+                   }
+                   memcpy(s->q, ssh->v2_session_id,
+                          ssh->v2_session_id_len);
+                   s->q += ssh->v2_session_id_len;
+                   memcpy(s->q, s->pktout->data + 5,
+                          s->pktout->length - 5);
+                   s->q += s->pktout->length - 5;
+                   /* And finally the (zero) flags word. */
+                   PUT_32BIT(s->q, 0);
+                   if (!agent_query(s->agentreq, s->len + 4,
+                                    &vret, &s->retlen,
+                                    ssh_agent_callback, ssh)) {
+                       do {
+                           crReturnV;
+                           if (pktin) {
+                               bombout(("Unexpected data from server"
+                                        " while waiting for agent"
+                                        " response"));
+                               crStopV;
                            }
+                       } while (pktin || inlen > 0);
+                       vret = ssh->agent_response;
+                       s->retlen = ssh->agent_response_len;
+                   }
+                   s->ret = vret;
+                   sfree(s->agentreq);
+                   if (s->ret) {
+                       if (s->retlen >= 9 &&
+                            s->ret[4] == SSH2_AGENT_SIGN_RESPONSE &&
+                            GET_32BIT(s->ret + 5) <= (unsigned)(s->retlen-9)) {
+                           logevent("Sending Pageant's response");
+                           ssh2_add_sigblob(ssh, s->pktout,
+                                            s->pkblob, s->pklen,
+                                            s->ret + 9,
+                                            GET_32BIT(s->ret + 5));
+                           ssh2_pkt_send(ssh, s->pktout);
+                           s->type = AUTH_TYPE_PUBLICKEY;
+                       } else {
+                           /* FIXME: less drastic response */
+                           bombout(("Pageant failed to answer challenge"));
+                           crStopV;
                        }
                    }
-                   if (s->authed)
-                       continue;
                }
-               sfree(s->response);
-           }
 
-           if (!s->method && s->can_pubkey && s->publickey_blob
-               && !s->tried_pubkey_config) {
-               unsigned char *pub_blob;
-               char *algorithm, *comment;
-               int pub_blob_len;
+               /* Do we have any keys left to try? */
+               if (s->pkblob_in_agent) {
+                   s->done_agent = TRUE;
+                   s->tried_pubkey_config = TRUE;
+               } else {
+                   s->keyi++;
+                   if (s->keyi >= s->nkeys)
+                       s->done_agent = TRUE;
+               }
 
-               s->tried_pubkey_config = TRUE;
+           } else if (s->can_pubkey && s->publickey_blob &&
+                      !s->tried_pubkey_config) {
 
-               ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-               ssh->pkt_ctx |= SSH2_PKTCTX_PUBLICKEY;
+               struct ssh2_userkey *key;   /* not live over crReturn */
+               char *passphrase;           /* not live over crReturn */
+
+               ssh->pkt_actx = SSH2_PKTCTX_PUBLICKEY;
+
+               s->tried_pubkey_config = TRUE;
 
                /*
                 * Try the public key supplied in the configuration.
@@ -6944,215 +9323,108 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                 * First, offer the public blob to see if the server is
                 * willing to accept it.
                 */
-               pub_blob =
-                   (unsigned char *)ssh2_userkey_loadpub(&ssh->cfg.keyfile,
-                                                         &algorithm,
-                                                         &pub_blob_len,
-                                                         NULL);
-               if (pub_blob) {
-                   s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-                   ssh2_pkt_addstring(s->pktout, s->username);
-                   ssh2_pkt_addstring(s->pktout, "ssh-connection");    /* service requested */
-                   ssh2_pkt_addstring(s->pktout, "publickey"); /* method */
-                   ssh2_pkt_addbool(s->pktout, FALSE); /* no signature included */
-                   ssh2_pkt_addstring(s->pktout, algorithm);
-                   ssh2_pkt_addstring_start(s->pktout);
-                   ssh2_pkt_addstring_data(s->pktout, (char *)pub_blob,
-                                           pub_blob_len);
-                   ssh2_pkt_send(ssh, s->pktout);
-                   logevent("Offered public key");
-
-                   crWaitUntilV(pktin);
-                   if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
-                       s->gotit = TRUE;
-                       s->type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD;
-                       continue;      /* key refused; give up on it */
-                   }
-
-                   logevent("Offer of public key accepted");
-                   /*
-                    * Actually attempt a serious authentication using
-                    * the key.
-                    */
-                   if (ssh2_userkey_encrypted(&ssh->cfg.keyfile, &comment)) {
-                       sprintf(s->pwprompt,
-                               "Passphrase for key \"%.100s\": ",
-                               comment);
-                       s->need_pw = TRUE;
-                   } else {
-                       s->need_pw = FALSE;
-                   }
-                   if (flags & FLAG_VERBOSE) {
-                       c_write_str(ssh, "Authenticating with public key \"");
-                       c_write_str(ssh, comment);
-                       c_write_str(ssh, "\"\r\n");
-                   }
-                   s->method = AUTH_PUBLICKEY_FILE;
-               }
-           }
-
-           if (!s->method && s->can_keyb_inter && !s->kbd_inter_refused &&
-               !s->kbd_inter_running) {
-               s->method = AUTH_KEYBOARD_INTERACTIVE;
-               s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
-
-               ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-               ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
-
                s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-               ssh2_pkt_addstring(s->pktout, s->username);
-               ssh2_pkt_addstring(s->pktout, "ssh-connection");        /* service requested */
-               ssh2_pkt_addstring(s->pktout, "keyboard-interactive");  /* method */
-               ssh2_pkt_addstring(s->pktout, ""); /* lang */
-               ssh2_pkt_addstring(s->pktout, "");
+               ssh2_pkt_addstring(s->pktout, ssh->username);
+               ssh2_pkt_addstring(s->pktout, "ssh-connection");
+                                               /* service requested */
+               ssh2_pkt_addstring(s->pktout, "publickey");     /* method */
+               ssh2_pkt_addbool(s->pktout, FALSE);
+                                               /* no signature included */
+               ssh2_pkt_addstring(s->pktout, s->publickey_algorithm);
+               ssh2_pkt_addstring_start(s->pktout);
+               ssh2_pkt_addstring_data(s->pktout,
+                                       (char *)s->publickey_blob,
+                                       s->publickey_bloblen);
                ssh2_pkt_send(ssh, s->pktout);
+               logevent("Offered public key");
 
                crWaitUntilV(pktin);
-               if (pktin->type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
-                   if (pktin->type == SSH2_MSG_USERAUTH_FAILURE)
-                       s->gotit = TRUE;
-                   logevent("Keyboard-interactive authentication refused");
-                   s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET;
-                   s->kbd_inter_refused = TRUE; /* don't try it again */
-                   continue;
-               }
-
-               c_write_str(ssh, "Using keyboard-interactive authentication.\r\n");
-               s->kbd_inter_running = TRUE;
-               s->curr_prompt = 0;
-           }
-
-           if (s->kbd_inter_running) {
-               s->method = AUTH_KEYBOARD_INTERACTIVE;
-               s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
-
-               ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-               ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
-
-               if (s->curr_prompt == 0) {
-                   /*
-                    * We've got a fresh USERAUTH_INFO_REQUEST.
-                    * Display header data, and start going through
-                    * the prompts.
-                    */
-                   char *name, *inst, *lang;
-                   int name_len, inst_len, lang_len;
-
-                   ssh_pkt_getstring(pktin, &name, &name_len);
-                   ssh_pkt_getstring(pktin, &inst, &inst_len);
-                   ssh_pkt_getstring(pktin, &lang, &lang_len);
-                   if (name_len > 0) {
-                       c_write_untrusted(ssh, name, name_len);
-                       c_write_str(ssh, "\r\n");
-                   }
-                   if (inst_len > 0) {
-                       c_write_untrusted(ssh, inst, inst_len);
-                       c_write_str(ssh, "\r\n");
-                   }
-                   s->num_prompts = ssh_pkt_getuint32(pktin);
+               if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
+                   /* Key refused. Give up. */
+                   s->gotit = TRUE; /* reconsider message next loop */
+                   s->type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD;
+                   continue; /* process this new message */
                }
+               logevent("Offer of public key accepted");
 
                /*
-                * If there are prompts remaining in the packet,
-                * display one and get a response.
+                * Actually attempt a serious authentication using
+                * the key.
                 */
-               if (s->curr_prompt < s->num_prompts) {
-                   char *prompt;
-                   int prompt_len;
-
-                   ssh_pkt_getstring(pktin, &prompt, &prompt_len);
-                   if (prompt_len > 0) {
-                       static const char trunc[] = "<prompt truncated>: ";
-                       static const int prlen = sizeof(s->pwprompt) -
-                                                lenof(trunc);
-                       if (prompt_len > prlen) {
-                           memcpy(s->pwprompt, prompt, prlen);
-                           strcpy(s->pwprompt + prlen, trunc);
-                       } else {
-                           memcpy(s->pwprompt, prompt, prompt_len);
-                           s->pwprompt[prompt_len] = '\0';
+               if (flags & FLAG_VERBOSE) {
+                   c_write_str(ssh, "Authenticating with public key \"");
+                   c_write_str(ssh, s->publickey_comment);
+                   c_write_str(ssh, "\"\r\n");
+               }
+               key = NULL;
+               while (!key) {
+                   const char *error;  /* not live over crReturn */
+                   if (s->publickey_encrypted) {
+                       /*
+                        * Get a passphrase from the user.
+                        */
+                       int ret; /* need not be kept over crReturn */
+                       s->cur_prompt = new_prompts(ssh->frontend);
+                       s->cur_prompt->to_server = FALSE;
+                       s->cur_prompt->name = dupstr("SSH key passphrase");
+                       add_prompt(s->cur_prompt,
+                                  dupprintf("Passphrase for key \"%.100s\": ",
+                                            s->publickey_comment),
+                                  FALSE);
+                       ret = get_userpass_input(s->cur_prompt, NULL, 0);
+                       while (ret < 0) {
+                           ssh->send_ok = 1;
+                           crWaitUntilV(!pktin);
+                           ret = get_userpass_input(s->cur_prompt,
+                                                    in, inlen);
+                           ssh->send_ok = 0;
+                       }
+                       if (!ret) {
+                           /* Failed to get a passphrase. Terminate. */
+                           free_prompts(s->cur_prompt);
+                           ssh_disconnect(ssh, NULL,
+                                          "Unable to authenticate",
+                                          SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+                                          TRUE);
+                           crStopV;
                        }
+                       passphrase =
+                           dupstr(s->cur_prompt->prompts[0]->result);
+                       free_prompts(s->cur_prompt);
                    } else {
-                       strcpy(s->pwprompt,
-                              "<server failed to send prompt>: ");
+                       passphrase = NULL; /* no passphrase needed */
                    }
-                   s->echo = ssh2_pkt_getbool(pktin);
-                   s->need_pw = TRUE;
-               } else
-                   s->need_pw = FALSE;
-           }
 
-           if (!s->method && s->can_passwd) {
-               s->method = AUTH_PASSWORD;
-               ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-               ssh->pkt_ctx |= SSH2_PKTCTX_PASSWORD;
-               sprintf(s->pwprompt, "%.90s@%.90s's password: ", s->username,
-                       ssh->savedhost);
-               s->need_pw = TRUE;
-           }
-
-           if (s->need_pw) {
-               if (ssh_get_line) {
-                   if (!ssh_get_line(s->pwprompt, s->password,
-                                     sizeof(s->password), TRUE)) {
-                       /*
-                        * get_line failed to get a password (for
-                        * example because one was supplied on the
-                        * command line which has already failed to
-                        * work). Terminate.
-                        */
-                       ssh_disconnect(ssh, NULL, "Unable to authenticate",
-                                      SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
-                                      FALSE);
-                       crStopV;
+                   /*
+                    * Try decrypting the key.
+                    */
+                   s->keyfile = conf_get_filename(ssh->conf, CONF_keyfile);
+                   key = ssh2_load_userkey(s->keyfile, passphrase, &error);
+                   if (passphrase) {
+                       /* burn the evidence */
+                       smemclr(passphrase, strlen(passphrase));
+                       sfree(passphrase);
+                   }
+                   if (key == SSH2_WRONG_PASSPHRASE || key == NULL) {
+                       if (passphrase &&
+                           (key == SSH2_WRONG_PASSPHRASE)) {
+                           c_write_str(ssh, "Wrong passphrase\r\n");
+                           key = NULL;
+                           /* and loop again */
+                       } else {
+                           c_write_str(ssh, "Unable to load private key (");
+                           c_write_str(ssh, error);
+                           c_write_str(ssh, ")\r\n");
+                           key = NULL;
+                           break; /* try something else */
+                       }
                    }
-               } else {
-                   int ret;           /* need not be saved across crReturn */
-                   c_write_untrusted(ssh, s->pwprompt, strlen(s->pwprompt));
-                   ssh->send_ok = 1;
-
-                   setup_userpass_input(ssh, s->password,
-                                        sizeof(s->password), s->echo);
-                   do {
-                       crWaitUntilV(!pktin);
-                       ret = process_userpass_input(ssh, in, inlen);
-                   } while (ret == 0);
-                   if (ret < 0)
-                       cleanup_exit(0);
-                   c_write_str(ssh, "\r\n");
                }
-           }
 
-           if (s->method == AUTH_PUBLICKEY_FILE) {
-               /*
-                * We have our passphrase. Now try the actual authentication.
-                */
-               struct ssh2_userkey *key;
-               const char *error = NULL;
-
-               key = ssh2_load_userkey(&ssh->cfg.keyfile, s->password,
-                                       &error);
-               if (key == SSH2_WRONG_PASSPHRASE || key == NULL) {
-                   if (key == SSH2_WRONG_PASSPHRASE) {
-                       c_write_str(ssh, "Wrong passphrase\r\n");
-                       s->tried_pubkey_config = FALSE;
-                   } else {
-                       c_write_str(ssh, "Unable to load private key (");
-                       c_write_str(ssh, error);
-                       c_write_str(ssh, ")\r\n");
-                       s->tried_pubkey_config = TRUE;
-                   }
-                   /* Send a spurious AUTH_NONE to return to the top. */
-                   s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-                   ssh2_pkt_addstring(s->pktout, s->username);
-                   ssh2_pkt_addstring(s->pktout, "ssh-connection");    /* service requested */
-                   ssh2_pkt_addstring(s->pktout, "none");      /* method */
-                   ssh2_pkt_send(ssh, s->pktout);
-                   s->type = AUTH_TYPE_NONE;
-               } else {
+               if (key) {
                    unsigned char *pkblob, *sigblob, *sigdata;
                    int pkblob_len, sigblob_len, sigdata_len;
-                    int p;
+                   int p;
 
                    /*
                     * We have loaded the private key and the server
@@ -7160,14 +9432,19 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                     * Hallelujah. Generate a signature and send it.
                     */
                    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-                   ssh2_pkt_addstring(s->pktout, s->username);
-                   ssh2_pkt_addstring(s->pktout, "ssh-connection");    /* service requested */
-                   ssh2_pkt_addstring(s->pktout, "publickey"); /* method */
+                   ssh2_pkt_addstring(s->pktout, ssh->username);
+                   ssh2_pkt_addstring(s->pktout, "ssh-connection");
+                                                   /* service requested */
+                   ssh2_pkt_addstring(s->pktout, "publickey");
+                                                   /* method */
                    ssh2_pkt_addbool(s->pktout, TRUE);
+                                                   /* signature follows */
                    ssh2_pkt_addstring(s->pktout, key->alg->name);
-                   pkblob = key->alg->public_blob(key->data, &pkblob_len);
+                   pkblob = key->alg->public_blob(key->data,
+                                                  &pkblob_len);
                    ssh2_pkt_addstring_start(s->pktout);
-                   ssh2_pkt_addstring_data(s->pktout, (char *)pkblob, pkblob_len);
+                   ssh2_pkt_addstring_data(s->pktout, (char *)pkblob,
+                                           pkblob_len);
 
                    /*
                     * The data to be signed is:
@@ -7177,20 +9454,23 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                     * followed by everything so far placed in the
                     * outgoing packet.
                     */
-                   sigdata_len = s->pktout->length - 5 + 4 + 20;
-                    if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
-                        sigdata_len -= 4;
+                   sigdata_len = s->pktout->length - 5 + 4 +
+                       ssh->v2_session_id_len;
+                   if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
+                       sigdata_len -= 4;
                    sigdata = snewn(sigdata_len, unsigned char);
-                    p = 0;
-                    if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
-                        PUT_32BIT(sigdata+p, 20);
-                        p += 4;
-                    }
-                   memcpy(sigdata+p, ssh->v2_session_id, 20); p += 20;
+                   p = 0;
+                   if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
+                       PUT_32BIT(sigdata+p, ssh->v2_session_id_len);
+                       p += 4;
+                   }
+                   memcpy(sigdata+p, ssh->v2_session_id,
+                          ssh->v2_session_id_len);
+                   p += ssh->v2_session_id_len;
                    memcpy(sigdata+p, s->pktout->data + 5,
                           s->pktout->length - 5);
-                    p += s->pktout->length - 5;
-                    assert(p == sigdata_len);
+                   p += s->pktout->length - 5;
+                   assert(p == sigdata_len);
                    sigblob = key->alg->sign(key->data, (char *)sigdata,
                                             sigdata_len, &sigblob_len);
                    ssh2_add_sigblob(ssh, s->pktout, pkblob, pkblob_len,
@@ -7200,11 +9480,409 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                    sfree(sigdata);
 
                    ssh2_pkt_send(ssh, s->pktout);
+                    logevent("Sent public key signature");
                    s->type = AUTH_TYPE_PUBLICKEY;
                    key->alg->freekey(key->data);
+                    sfree(key->comment);
+                    sfree(key);
+               }
+
+#ifndef NO_GSSAPI
+           } else if (s->can_gssapi && !s->tried_gssapi) {
+
+               /* GSSAPI Authentication */
+
+               int micoffset, len;
+               char *data;
+               Ssh_gss_buf mic;
+               s->type = AUTH_TYPE_GSSAPI;
+               s->tried_gssapi = TRUE;
+               s->gotit = TRUE;
+               ssh->pkt_actx = SSH2_PKTCTX_GSSAPI;
+
+               /*
+                * Pick the highest GSS library on the preference
+                * list.
+                */
+               {
+                   int i, j;
+                   s->gsslib = NULL;
+                   for (i = 0; i < ngsslibs; i++) {
+                       int want_id = conf_get_int_int(ssh->conf,
+                                                      CONF_ssh_gsslist, i);
+                       for (j = 0; j < ssh->gsslibs->nlibraries; j++)
+                           if (ssh->gsslibs->libraries[j].id == want_id) {
+                               s->gsslib = &ssh->gsslibs->libraries[j];
+                               goto got_gsslib;   /* double break */
+                           }
+                   }
+                   got_gsslib:
+                   /*
+                    * We always expect to have found something in
+                    * the above loop: we only came here if there
+                    * was at least one viable GSS library, and the
+                    * preference list should always mention
+                    * everything and only change the order.
+                    */
+                   assert(s->gsslib);
+               }
+
+               if (s->gsslib->gsslogmsg)
+                   logevent(s->gsslib->gsslogmsg);
+
+               /* Sending USERAUTH_REQUEST with "gssapi-with-mic" method */
+               s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+               ssh2_pkt_addstring(s->pktout, ssh->username);
+               ssh2_pkt_addstring(s->pktout, "ssh-connection");
+               ssh2_pkt_addstring(s->pktout, "gssapi-with-mic");
+                logevent("Attempting GSSAPI authentication");
+
+               /* add mechanism info */
+               s->gsslib->indicate_mech(s->gsslib, &s->gss_buf);
+
+               /* number of GSSAPI mechanisms */
+               ssh2_pkt_adduint32(s->pktout,1);
+
+               /* length of OID + 2 */
+               ssh2_pkt_adduint32(s->pktout, s->gss_buf.length + 2);
+               ssh2_pkt_addbyte(s->pktout, SSH2_GSS_OIDTYPE);
+
+               /* length of OID */
+               ssh2_pkt_addbyte(s->pktout, (unsigned char) s->gss_buf.length);
+
+               ssh_pkt_adddata(s->pktout, s->gss_buf.value,
+                               s->gss_buf.length);
+               ssh2_pkt_send(ssh, s->pktout);
+               crWaitUntilV(pktin);
+               if (pktin->type != SSH2_MSG_USERAUTH_GSSAPI_RESPONSE) {
+                   logevent("GSSAPI authentication request refused");
+                   continue;
+               }
+
+               /* check returned packet ... */
+
+               ssh_pkt_getstring(pktin, &data, &len);
+               s->gss_rcvtok.value = data;
+               s->gss_rcvtok.length = len;
+               if (s->gss_rcvtok.length != s->gss_buf.length + 2 ||
+                   ((char *)s->gss_rcvtok.value)[0] != SSH2_GSS_OIDTYPE ||
+                   ((char *)s->gss_rcvtok.value)[1] != s->gss_buf.length ||
+                   memcmp((char *)s->gss_rcvtok.value + 2,
+                          s->gss_buf.value,s->gss_buf.length) ) {
+                   logevent("GSSAPI authentication - wrong response from server");
+                   continue;
+               }
+
+               /* now start running */
+               s->gss_stat = s->gsslib->import_name(s->gsslib,
+                                                    ssh->fullhostname,
+                                                    &s->gss_srv_name);
+               if (s->gss_stat != SSH_GSS_OK) {
+                   if (s->gss_stat == SSH_GSS_BAD_HOST_NAME)
+                       logevent("GSSAPI import name failed - Bad service name");
+                   else
+                       logevent("GSSAPI import name failed");
+                   continue;
+               }
+
+               /* fetch TGT into GSS engine */
+               s->gss_stat = s->gsslib->acquire_cred(s->gsslib, &s->gss_ctx);
+
+               if (s->gss_stat != SSH_GSS_OK) {
+                   logevent("GSSAPI authentication failed to get credentials");
+                   s->gsslib->release_name(s->gsslib, &s->gss_srv_name);
+                   continue;
+               }
+
+               /* initial tokens are empty */
+               SSH_GSS_CLEAR_BUF(&s->gss_rcvtok);
+               SSH_GSS_CLEAR_BUF(&s->gss_sndtok);
+
+               /* now enter the loop */
+               do {
+                   s->gss_stat = s->gsslib->init_sec_context
+                       (s->gsslib,
+                        &s->gss_ctx,
+                        s->gss_srv_name,
+                        conf_get_int(ssh->conf, CONF_gssapifwd),
+                        &s->gss_rcvtok,
+                        &s->gss_sndtok);
+
+                   if (s->gss_stat!=SSH_GSS_S_COMPLETE &&
+                       s->gss_stat!=SSH_GSS_S_CONTINUE_NEEDED) {
+                       logevent("GSSAPI authentication initialisation failed");
+
+                       if (s->gsslib->display_status(s->gsslib, s->gss_ctx,
+                                                     &s->gss_buf) == SSH_GSS_OK) {
+                           logevent(s->gss_buf.value);
+                           sfree(s->gss_buf.value);
+                       }
+
+                       break;
+                   }
+                   logevent("GSSAPI authentication initialised");
+
+                   /* Client and server now exchange tokens until GSSAPI
+                    * no longer says CONTINUE_NEEDED */
+
+                   if (s->gss_sndtok.length != 0) {
+                       s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
+                       ssh_pkt_addstring_start(s->pktout);
+                       ssh_pkt_addstring_data(s->pktout,s->gss_sndtok.value,s->gss_sndtok.length);
+                       ssh2_pkt_send(ssh, s->pktout);
+                       s->gsslib->free_tok(s->gsslib, &s->gss_sndtok);
+                   }
+
+                   if (s->gss_stat == SSH_GSS_S_CONTINUE_NEEDED) {
+                       crWaitUntilV(pktin);
+                       if (pktin->type != SSH2_MSG_USERAUTH_GSSAPI_TOKEN) {
+                           logevent("GSSAPI authentication - bad server response");
+                           s->gss_stat = SSH_GSS_FAILURE;
+                           break;
+                       }
+                       ssh_pkt_getstring(pktin, &data, &len);
+                       s->gss_rcvtok.value = data;
+                       s->gss_rcvtok.length = len;
+                   }
+               } while (s-> gss_stat == SSH_GSS_S_CONTINUE_NEEDED);
+
+               if (s->gss_stat != SSH_GSS_OK) {
+                   s->gsslib->release_name(s->gsslib, &s->gss_srv_name);
+                   s->gsslib->release_cred(s->gsslib, &s->gss_ctx);
+                   continue;
+               }
+               logevent("GSSAPI authentication loop finished OK");
+
+               /* Now send the MIC */
+
+               s->pktout = ssh2_pkt_init(0);
+               micoffset = s->pktout->length;
+               ssh_pkt_addstring_start(s->pktout);
+               ssh_pkt_addstring_data(s->pktout, (char *)ssh->v2_session_id, ssh->v2_session_id_len);
+               ssh_pkt_addbyte(s->pktout, SSH2_MSG_USERAUTH_REQUEST);
+               ssh_pkt_addstring(s->pktout, ssh->username);
+               ssh_pkt_addstring(s->pktout, "ssh-connection");
+               ssh_pkt_addstring(s->pktout, "gssapi-with-mic");
+
+               s->gss_buf.value = (char *)s->pktout->data + micoffset;
+               s->gss_buf.length = s->pktout->length - micoffset;
+
+               s->gsslib->get_mic(s->gsslib, s->gss_ctx, &s->gss_buf, &mic);
+               s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_GSSAPI_MIC);
+               ssh_pkt_addstring_start(s->pktout);
+               ssh_pkt_addstring_data(s->pktout, mic.value, mic.length);
+               ssh2_pkt_send(ssh, s->pktout);
+               s->gsslib->free_mic(s->gsslib, &mic);
+
+               s->gotit = FALSE;
+
+               s->gsslib->release_name(s->gsslib, &s->gss_srv_name);
+               s->gsslib->release_cred(s->gsslib, &s->gss_ctx);
+               continue;
+#endif
+           } else if (s->can_keyb_inter && !s->kbd_inter_refused) {
+
+               /*
+                * Keyboard-interactive authentication.
+                */
+
+               s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
+
+               ssh->pkt_actx = SSH2_PKTCTX_KBDINTER;
+
+               s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+               ssh2_pkt_addstring(s->pktout, ssh->username);
+               ssh2_pkt_addstring(s->pktout, "ssh-connection");
+                                                       /* service requested */
+               ssh2_pkt_addstring(s->pktout, "keyboard-interactive");
+                                                       /* method */
+               ssh2_pkt_addstring(s->pktout, "");      /* lang */
+               ssh2_pkt_addstring(s->pktout, "");      /* submethods */
+               ssh2_pkt_send(ssh, s->pktout);
+                
+                logevent("Attempting keyboard-interactive authentication");
+
+               crWaitUntilV(pktin);
+               if (pktin->type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
+                   /* Server is not willing to do keyboard-interactive
+                    * at all (or, bizarrely but legally, accepts the
+                    * user without actually issuing any prompts).
+                    * Give up on it entirely. */
+                   s->gotit = TRUE;
+                   s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET;
+                   s->kbd_inter_refused = TRUE; /* don't try it again */
+                   continue;
+               }
+
+               /*
+                * Loop while the server continues to send INFO_REQUESTs.
+                */
+               while (pktin->type == SSH2_MSG_USERAUTH_INFO_REQUEST) {
+
+                   char *name, *inst, *lang;
+                   int name_len, inst_len, lang_len;
+                   int i;
+
+                   /*
+                    * We've got a fresh USERAUTH_INFO_REQUEST.
+                    * Get the preamble and start building a prompt.
+                    */
+                   ssh_pkt_getstring(pktin, &name, &name_len);
+                   ssh_pkt_getstring(pktin, &inst, &inst_len);
+                   ssh_pkt_getstring(pktin, &lang, &lang_len);
+                   s->cur_prompt = new_prompts(ssh->frontend);
+                   s->cur_prompt->to_server = TRUE;
+
+                   /*
+                    * Get any prompt(s) from the packet.
+                    */
+                   s->num_prompts = ssh_pkt_getuint32(pktin);
+                   for (i = 0; i < s->num_prompts; i++) {
+                       char *prompt;
+                       int prompt_len;
+                       int echo;
+                       static char noprompt[] =
+                           "<server failed to send prompt>: ";
+
+                       ssh_pkt_getstring(pktin, &prompt, &prompt_len);
+                       echo = ssh2_pkt_getbool(pktin);
+                       if (!prompt_len) {
+                           prompt = noprompt;
+                           prompt_len = lenof(noprompt)-1;
+                       }
+                       add_prompt(s->cur_prompt,
+                                  dupprintf("%.*s", prompt_len, prompt),
+                                   echo);
+                   }
+
+                   if (name_len) {
+                       /* FIXME: better prefix to distinguish from
+                        * local prompts? */
+                       s->cur_prompt->name =
+                           dupprintf("SSH server: %.*s", name_len, name);
+                       s->cur_prompt->name_reqd = TRUE;
+                   } else {
+                       s->cur_prompt->name =
+                           dupstr("SSH server authentication");
+                       s->cur_prompt->name_reqd = FALSE;
+                   }
+                   /* We add a prefix to try to make it clear that a prompt
+                    * has come from the server.
+                    * FIXME: ugly to print "Using..." in prompt _every_
+                    * time round. Can this be done more subtly? */
+                   /* Special case: for reasons best known to themselves,
+                    * some servers send k-i requests with no prompts and
+                    * nothing to display. Keep quiet in this case. */
+                   if (s->num_prompts || name_len || inst_len) {
+                       s->cur_prompt->instruction =
+                           dupprintf("Using keyboard-interactive authentication.%s%.*s",
+                                     inst_len ? "\n" : "", inst_len, inst);
+                       s->cur_prompt->instr_reqd = TRUE;
+                   } else {
+                       s->cur_prompt->instr_reqd = FALSE;
+                   }
+
+                   /*
+                     * Display any instructions, and get the user's
+                     * response(s).
+                    */
+                   {
+                       int ret; /* not live over crReturn */
+                       ret = get_userpass_input(s->cur_prompt, NULL, 0);
+                       while (ret < 0) {
+                           ssh->send_ok = 1;
+                           crWaitUntilV(!pktin);
+                           ret = get_userpass_input(s->cur_prompt, in, inlen);
+                           ssh->send_ok = 0;
+                       }
+                       if (!ret) {
+                           /*
+                            * Failed to get responses. Terminate.
+                            */
+                           free_prompts(s->cur_prompt);
+                           ssh_disconnect(ssh, NULL, "Unable to authenticate",
+                                          SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+                                          TRUE);
+                           crStopV;
+                       }
+                   }
+
+                   /*
+                    * Send the response(s) to the server.
+                    */
+                   s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
+                   ssh2_pkt_adduint32(s->pktout, s->num_prompts);
+                   for (i=0; i < s->num_prompts; i++) {
+                       ssh2_pkt_addstring(s->pktout,
+                                          s->cur_prompt->prompts[i]->result);
+                   }
+                   ssh2_pkt_send_with_padding(ssh, s->pktout, 256);
+
+                    /*
+                     * Free the prompts structure from this iteration.
+                     * If there's another, a new one will be allocated
+                     * when we return to the top of this while loop.
+                     */
+                    free_prompts(s->cur_prompt);
+
+                   /*
+                    * Get the next packet in case it's another
+                    * INFO_REQUEST.
+                    */
+                   crWaitUntilV(pktin);
+
+               }
+
+               /*
+                * We should have SUCCESS or FAILURE now.
+                */
+               s->gotit = TRUE;
+
+           } else if (s->can_passwd) {
+
+               /*
+                * Plain old password authentication.
+                */
+               int ret; /* not live over crReturn */
+               int changereq_first_time; /* not live over crReturn */
+
+               ssh->pkt_actx = SSH2_PKTCTX_PASSWORD;
+
+               s->cur_prompt = new_prompts(ssh->frontend);
+               s->cur_prompt->to_server = TRUE;
+               s->cur_prompt->name = dupstr("SSH password");
+               add_prompt(s->cur_prompt, dupprintf("%s@%s's password: ",
+                                                   ssh->username,
+                                                   ssh->savedhost),
+                          FALSE);
+
+               ret = get_userpass_input(s->cur_prompt, NULL, 0);
+               while (ret < 0) {
+                   ssh->send_ok = 1;
+                   crWaitUntilV(!pktin);
+                   ret = get_userpass_input(s->cur_prompt, in, inlen);
+                   ssh->send_ok = 0;
+               }
+               if (!ret) {
+                   /*
+                    * Failed to get responses. Terminate.
+                    */
+                   free_prompts(s->cur_prompt);
+                   ssh_disconnect(ssh, NULL, "Unable to authenticate",
+                                  SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+                                  TRUE);
+                   crStopV;
                }
-           } else if (s->method == AUTH_PASSWORD) {
                /*
+                * Squirrel away the password. (We may need it later if
+                * asked to change it.)
+                */
+               s->password = dupstr(s->cur_prompt->prompts[0]->result);
+               free_prompts(s->cur_prompt);
+
+               /*
+                * Send the password packet.
+                *
                 * We pad out the password packet to 256 bytes to make
                 * it harder for an attacker to find the length of the
                 * user's password.
@@ -7214,59 +9892,217 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                 * people who find out how long their password is!
                 */
                s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-               s->pktout->forcepad = 256;
-               ssh2_pkt_addstring(s->pktout, s->username);
-               ssh2_pkt_addstring(s->pktout, "ssh-connection");        /* service requested */
+               ssh2_pkt_addstring(s->pktout, ssh->username);
+               ssh2_pkt_addstring(s->pktout, "ssh-connection");
+                                                       /* service requested */
                ssh2_pkt_addstring(s->pktout, "password");
                ssh2_pkt_addbool(s->pktout, FALSE);
-               dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
                ssh2_pkt_addstring(s->pktout, s->password);
-               memset(s->password, 0, sizeof(s->password));
-               end_log_omission(ssh, s->pktout);
-               ssh2_pkt_send(ssh, s->pktout);
+               ssh2_pkt_send_with_padding(ssh, s->pktout, 256);
                logevent("Sent password");
                s->type = AUTH_TYPE_PASSWORD;
-           } else if (s->method == AUTH_KEYBOARD_INTERACTIVE) {
-               if (s->curr_prompt == 0) {
-                   s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
-                   s->pktout->forcepad = 256;
-                   ssh2_pkt_adduint32(s->pktout, s->num_prompts);
-               }
-               if (s->need_pw) {      /* only add pw if we just got one! */
-                   dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
+
+               /*
+                * Wait for next packet, in case it's a password change
+                * request.
+                */
+               crWaitUntilV(pktin);
+               changereq_first_time = TRUE;
+
+               while (pktin->type == SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ) {
+
+                   /* 
+                    * We're being asked for a new password
+                    * (perhaps not for the first time).
+                    * Loop until the server accepts it.
+                    */
+
+                   int got_new = FALSE; /* not live over crReturn */
+                   char *prompt;   /* not live over crReturn */
+                   int prompt_len; /* not live over crReturn */
+                   
+                   {
+                       char *msg;
+                       if (changereq_first_time)
+                           msg = "Server requested password change";
+                       else
+                           msg = "Server rejected new password";
+                       logevent(msg);
+                       c_write_str(ssh, msg);
+                       c_write_str(ssh, "\r\n");
+                   }
+
+                   ssh_pkt_getstring(pktin, &prompt, &prompt_len);
+
+                   s->cur_prompt = new_prompts(ssh->frontend);
+                   s->cur_prompt->to_server = TRUE;
+                   s->cur_prompt->name = dupstr("New SSH password");
+                   s->cur_prompt->instruction =
+                       dupprintf("%.*s", prompt_len, prompt);
+                   s->cur_prompt->instr_reqd = TRUE;
+                   /*
+                    * There's no explicit requirement in the protocol
+                    * for the "old" passwords in the original and
+                    * password-change messages to be the same, and
+                    * apparently some Cisco kit supports password change
+                    * by the user entering a blank password originally
+                    * and the real password subsequently, so,
+                    * reluctantly, we prompt for the old password again.
+                    *
+                    * (On the other hand, some servers don't even bother
+                    * to check this field.)
+                    */
+                   add_prompt(s->cur_prompt,
+                              dupstr("Current password (blank for previously entered password): "),
+                              FALSE);
+                   add_prompt(s->cur_prompt, dupstr("Enter new password: "),
+                              FALSE);
+                   add_prompt(s->cur_prompt, dupstr("Confirm new password: "),
+                              FALSE);
+
+                   /*
+                    * Loop until the user manages to enter the same
+                    * password twice.
+                    */
+                   while (!got_new) {
+
+                       ret = get_userpass_input(s->cur_prompt, NULL, 0);
+                       while (ret < 0) {
+                           ssh->send_ok = 1;
+                           crWaitUntilV(!pktin);
+                           ret = get_userpass_input(s->cur_prompt, in, inlen);
+                           ssh->send_ok = 0;
+                       }
+                       if (!ret) {
+                           /*
+                            * Failed to get responses. Terminate.
+                            */
+                           /* burn the evidence */
+                           free_prompts(s->cur_prompt);
+                           smemclr(s->password, strlen(s->password));
+                           sfree(s->password);
+                           ssh_disconnect(ssh, NULL, "Unable to authenticate",
+                                          SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+                                          TRUE);
+                           crStopV;
+                       }
+
+                       /*
+                        * If the user specified a new original password
+                        * (IYSWIM), overwrite any previously specified
+                        * one.
+                        * (A side effect is that the user doesn't have to
+                        * re-enter it if they louse up the new password.)
+                        */
+                       if (s->cur_prompt->prompts[0]->result[0]) {
+                           smemclr(s->password, strlen(s->password));
+                               /* burn the evidence */
+                           sfree(s->password);
+                           s->password =
+                               dupstr(s->cur_prompt->prompts[0]->result);
+                       }
+
+                       /*
+                        * Check the two new passwords match.
+                        */
+                       got_new = (strcmp(s->cur_prompt->prompts[1]->result,
+                                         s->cur_prompt->prompts[2]->result)
+                                  == 0);
+                       if (!got_new)
+                           /* They don't. Silly user. */
+                           c_write_str(ssh, "Passwords do not match\r\n");
+
+                   }
+
+                   /*
+                    * Send the new password (along with the old one).
+                    * (see above for padding rationale)
+                    */
+                   s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+                   ssh2_pkt_addstring(s->pktout, ssh->username);
+                   ssh2_pkt_addstring(s->pktout, "ssh-connection");
+                                                       /* service requested */
+                   ssh2_pkt_addstring(s->pktout, "password");
+                   ssh2_pkt_addbool(s->pktout, TRUE);
                    ssh2_pkt_addstring(s->pktout, s->password);
-                   memset(s->password, 0, sizeof(s->password));
-                   end_log_omission(ssh, s->pktout);
-                   s->curr_prompt++;
-               }
-               if (s->curr_prompt >= s->num_prompts) {
-                   ssh2_pkt_send(ssh, s->pktout);
-               } else {
+                   ssh2_pkt_addstring(s->pktout,
+                                      s->cur_prompt->prompts[1]->result);
+                   free_prompts(s->cur_prompt);
+                   ssh2_pkt_send_with_padding(ssh, s->pktout, 256);
+                   logevent("Sent new password");
+                   
                    /*
-                    * If there are prompts remaining, we set
-                    * `gotit' so that we won't attempt to get
-                    * another packet. Then we go back round the
-                    * loop and will end up retrieving another
-                    * prompt out of the existing packet. Funky or
-                    * what?
+                    * Now see what the server has to say about it.
+                    * (If it's CHANGEREQ again, it's not happy with the
+                    * new password.)
                     */
-                   s->gotit = TRUE;
+                   crWaitUntilV(pktin);
+                   changereq_first_time = FALSE;
+
                }
-               s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
+
+               /*
+                * We need to reexamine the current pktin at the top
+                * of the loop. Either:
+                *  - we weren't asked to change password at all, in
+                *    which case it's a SUCCESS or FAILURE with the
+                *    usual meaning
+                *  - we sent a new password, and the server was
+                *    either OK with it (SUCCESS or FAILURE w/partial
+                *    success) or unhappy with the _old_ password
+                *    (FAILURE w/o partial success)
+                * In any of these cases, we go back to the top of
+                * the loop and start again.
+                */
+               s->gotit = TRUE;
+
+               /*
+                * We don't need the old password any more, in any
+                * case. Burn the evidence.
+                */
+               smemclr(s->password, strlen(s->password));
+               sfree(s->password);
+
            } else {
-               ssh_disconnect(ssh, NULL,
+               char *str = dupprintf("No supported authentication methods available"
+                                     " (server sent: %.*s)",
+                                     methlen, methods);
+
+               ssh_disconnect(ssh, str,
                               "No supported authentication methods available",
                               SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE,
                               FALSE);
+               sfree(str);
+
                crStopV;
+
            }
+
        }
     }
     ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = NULL;
 
-    /*
-     * Now the connection protocol has started, one way or another.
-     */
+    /* Clear up various bits and pieces from authentication. */
+    if (s->publickey_blob) {
+       sfree(s->publickey_blob);
+       sfree(s->publickey_comment);
+    }
+    if (s->agent_response)
+       sfree(s->agent_response);
+
+    if (s->userauth_success && !ssh->bare_connection) {
+       /*
+        * We've just received USERAUTH_SUCCESS, and we haven't sent any
+        * packets since. Signal the transport layer to consider enacting
+        * delayed compression.
+        *
+        * (Relying on we_are_in is not sufficient, as
+        * draft-miller-secsh-compression-delayed is quite clear that it
+        * triggers on USERAUTH_SUCCESS specifically, and we_are_in can
+        * become set for other reasons.)
+        */
+       do_ssh2_transport(ssh, "enabling delayed compression", -2, NULL);
+    }
 
     ssh->channels = newtree234(ssh_channelcmp);
 
@@ -7282,20 +10118,32 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Create the main session channel.
      */
-    if (!ssh->cfg.ssh_no_shell) {
+    if (conf_get_int(ssh->conf, CONF_ssh_no_shell)) {
+       ssh->mainchan = NULL;
+    } else {
        ssh->mainchan = snew(struct ssh_channel);
        ssh->mainchan->ssh = ssh;
-       ssh->mainchan->localid = alloc_channel_id(ssh);
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
-       ssh2_pkt_addstring(s->pktout, "session");
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->localid);
-       ssh->mainchan->v.v2.locwindow = OUR_V2_WINSIZE;
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->v.v2.locwindow);/* our window size */
-       ssh2_pkt_adduint32(s->pktout, OUR_V2_MAXPKT);    /* our max pkt size */
-       ssh2_pkt_send(ssh, s->pktout);
+       ssh2_channel_init(ssh->mainchan);
+
+       if (*conf_get_str(ssh->conf, CONF_ssh_nc_host)) {
+           /*
+            * Just start a direct-tcpip channel and use it as the main
+            * channel.
+            */
+           ssh_send_port_open(ssh->mainchan,
+                              conf_get_str(ssh->conf, CONF_ssh_nc_host),
+                              conf_get_int(ssh->conf, CONF_ssh_nc_port),
+                              "main channel");
+           ssh->ncmode = TRUE;
+       } else {
+           s->pktout = ssh2_chanopen_init(ssh->mainchan, "session");
+           logevent("Opening session as main channel");
+           ssh2_pkt_send(ssh, s->pktout);
+           ssh->ncmode = FALSE;
+       }
        crWaitUntilV(pktin);
        if (pktin->type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
-           bombout(("Server refused to open a session"));
+           bombout(("Server refused to open channel"));
            crStopV;
            /* FIXME: error data comes back in FAILURE packet */
        }
@@ -7306,15 +10154,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        ssh->mainchan->remoteid = ssh_pkt_getuint32(pktin);
        ssh->mainchan->halfopen = FALSE;
        ssh->mainchan->type = CHAN_MAINSESSION;
-       ssh->mainchan->closes = 0;
        ssh->mainchan->v.v2.remwindow = ssh_pkt_getuint32(pktin);
        ssh->mainchan->v.v2.remmaxpkt = ssh_pkt_getuint32(pktin);
-       bufchain_init(&ssh->mainchan->v.v2.outbuffer);
        add234(ssh->channels, ssh->mainchan);
        update_specials_menu(ssh->frontend);
-       logevent("Opened channel for session");
-    } else
-       ssh->mainchan = NULL;
+       logevent("Opened main channel");
+    }
 
     /*
      * Now we have a channel, make dispatch table entries for
@@ -7333,253 +10178,131 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        ssh2_msg_channel_request;
     ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] =
        ssh2_msg_channel_open;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_channel_response;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_channel_response;
 
     /*
-     * Potentially enable X11 forwarding.
+     * Now the connection protocol is properly up and running, with
+     * all those dispatch table entries, so it's safe to let
+     * downstreams start trying to open extra channels through us.
      */
-    if (ssh->mainchan && ssh->cfg.x11_forward) {
-       char proto[20], data[64];
-       logevent("Requesting X11 forwarding");
-       ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
-                                      data, sizeof(data), ssh->cfg.x11_auth);
-        x11_get_real_auth(ssh->x11auth, ssh->cfg.x11_display);
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
-       ssh2_pkt_addstring(s->pktout, "x11-req");
-       ssh2_pkt_addbool(s->pktout, 1);        /* want reply */
-       ssh2_pkt_addbool(s->pktout, 0);        /* many connections */
-       ssh2_pkt_addstring(s->pktout, proto);
+    if (ssh->connshare)
+        share_activate(ssh->connshare, ssh->v_s);
+
+    if (ssh->mainchan && ssh_is_simple(ssh)) {
        /*
-        * Note that while we blank the X authentication data here, we don't
-        * take any special action to blank the start of an X11 channel,
-        * so using MIT-MAGIC-COOKIE-1 and actually opening an X connection
-        * without having session blanking enabled is likely to leak your
-        * cookie into the log.
+        * This message indicates to the server that we promise
+        * not to try to run any other channel in parallel with
+        * this one, so it's safe for it to advertise a very large
+        * window and leave the flow control to TCP.
         */
-       dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
-       ssh2_pkt_addstring(s->pktout, data);
-       end_log_omission(ssh, s->pktout);
-       ssh2_pkt_adduint32(s->pktout, x11_get_screen_number(ssh->cfg.x11_display));
+       s->pktout = ssh2_chanreq_init(ssh->mainchan,
+                                     "simple@putty.projects.tartarus.org",
+                                     NULL, NULL);
        ssh2_pkt_send(ssh, s->pktout);
-
-       crWaitUntilV(pktin);
-
-       if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
-           if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
-               bombout(("Unexpected response to X11 forwarding request:"
-                        " packet type %d", pktin->type));
-               crStopV;
-           }
-           logevent("X11 forwarding refused");
-       } else {
-           logevent("X11 forwarding enabled");
-           ssh->X11_fwd_enabled = TRUE;
-       }
     }
 
     /*
      * Enable port forwardings.
      */
-    ssh_setup_portfwd(ssh, &ssh->cfg);
+    ssh_setup_portfwd(ssh, ssh->conf);
 
-    /*
-     * Potentially enable agent forwarding.
-     */
-    if (ssh->mainchan && ssh->cfg.agentfwd && agent_exists()) {
-       logevent("Requesting OpenSSH-style agent forwarding");
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
-       ssh2_pkt_addstring(s->pktout, "auth-agent-req@openssh.com");
-       ssh2_pkt_addbool(s->pktout, 1);        /* want reply */
-       ssh2_pkt_send(ssh, s->pktout);
+    if (ssh->mainchan && !ssh->ncmode) {
+       /*
+        * Send the CHANNEL_REQUESTS for the main session channel.
+        * Each one is handled by its own little asynchronous
+        * co-routine.
+        */
 
-       crWaitUntilV(pktin);
+       /* Potentially enable X11 forwarding. */
+       if (conf_get_int(ssh->conf, CONF_x11_forward)) {
+            ssh->x11disp =
+                x11_setup_display(conf_get_str(ssh->conf, CONF_x11_display),
+                                  ssh->conf);
+            if (!ssh->x11disp) {
+                /* FIXME: return an error message from x11_setup_display */
+                logevent("X11 forwarding not enabled: unable to"
+                         " initialise X display");
+            } else {
+                ssh->x11auth = x11_invent_fake_auth
+                    (ssh->x11authtree, conf_get_int(ssh->conf, CONF_x11_auth));
+                ssh->x11auth->disp = ssh->x11disp;
+
+                ssh2_setup_x11(ssh->mainchan, NULL, NULL);
+            }
+        }
 
-       if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
-           if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
-               bombout(("Unexpected response to agent forwarding request:"
-                        " packet type %d", pktin->type));
-               crStopV;
-           }
-           logevent("Agent forwarding refused");
-       } else {
-           logevent("Agent forwarding enabled");
-           ssh->agentfwd_enabled = TRUE;
-       }
-    }
+       /* Potentially enable agent forwarding. */
+       if (ssh_agent_forwarding_permitted(ssh))
+           ssh2_setup_agent(ssh->mainchan, NULL, NULL);
 
-    /*
-     * Now allocate a pty for the session.
-     */
-    if (ssh->mainchan && !ssh->cfg.nopty) {
-       /* Unpick the terminal-speed string. */
-       /* XXX perhaps we should allow no speeds to be sent. */
-        ssh->ospeed = 38400; ssh->ispeed = 38400; /* last-resort defaults */
-       sscanf(ssh->cfg.termspeed, "%d,%d", &ssh->ospeed, &ssh->ispeed);
-       /* Build the pty request. */
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid); /* recipient channel */
-       ssh2_pkt_addstring(s->pktout, "pty-req");
-       ssh2_pkt_addbool(s->pktout, 1);        /* want reply */
-       ssh2_pkt_addstring(s->pktout, ssh->cfg.termtype);
-       ssh2_pkt_adduint32(s->pktout, ssh->term_width);
-       ssh2_pkt_adduint32(s->pktout, ssh->term_height);
-       ssh2_pkt_adduint32(s->pktout, 0);              /* pixel width */
-       ssh2_pkt_adduint32(s->pktout, 0);              /* pixel height */
-       ssh2_pkt_addstring_start(s->pktout);
-       parse_ttymodes(ssh, ssh->cfg.ttymodes,
-                      ssh2_send_ttymode, (void *)s->pktout);
-       ssh2_pkt_addbyte(s->pktout, SSH2_TTY_OP_ISPEED);
-       ssh2_pkt_adduint32(s->pktout, ssh->ispeed);
-       ssh2_pkt_addbyte(s->pktout, SSH2_TTY_OP_OSPEED);
-       ssh2_pkt_adduint32(s->pktout, ssh->ospeed);
-       ssh2_pkt_addstring_data(s->pktout, "\0", 1); /* TTY_OP_END */
-       ssh2_pkt_send(ssh, s->pktout);
-       ssh->state = SSH_STATE_INTERMED;
+       /* Now allocate a pty for the session. */
+       if (!conf_get_int(ssh->conf, CONF_nopty))
+           ssh2_setup_pty(ssh->mainchan, NULL, NULL);
 
-       crWaitUntilV(pktin);
+       /* Send environment variables. */
+       ssh2_setup_env(ssh->mainchan, NULL, NULL);
 
-       if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
-           if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
-               bombout(("Unexpected response to pty request:"
-                        " packet type %d", pktin->type));
-               crStopV;
+       /*
+        * Start a shell or a remote command. We may have to attempt
+        * this twice if the config data has provided a second choice
+        * of command.
+        */
+       while (1) {
+           int subsys;
+           char *cmd;
+
+           if (ssh->fallback_cmd) {
+               subsys = conf_get_int(ssh->conf, CONF_ssh_subsys2);
+               cmd = conf_get_str(ssh->conf, CONF_remote_cmd2);
+           } else {
+               subsys = conf_get_int(ssh->conf, CONF_ssh_subsys);
+               cmd = conf_get_str(ssh->conf, CONF_remote_cmd);
            }
-           c_write_str(ssh, "Server refused to allocate pty\r\n");
-           ssh->editing = ssh->echoing = 1;
-       } else {
-           logeventf(ssh, "Allocated pty (ospeed %dbps, ispeed %dbps)",
-                     ssh->ospeed, ssh->ispeed);
-       }
-    } else {
-       ssh->editing = ssh->echoing = 1;
-    }
 
-    /*
-     * Send environment variables.
-     * 
-     * Simplest thing here is to send all the requests at once, and
-     * then wait for a whole bunch of successes or failures.
-     */
-    if (ssh->mainchan && *ssh->cfg.environmt) {
-       char *e = ssh->cfg.environmt;
-       char *var, *varend, *val;
-
-       s->num_env = 0;
-
-       while (*e) {
-           var = e;
-           while (*e && *e != '\t') e++;
-           varend = e;
-           if (*e == '\t') e++;
-           val = e;
-           while (*e) e++;
-           e++;
-
-           s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-           ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
-           ssh2_pkt_addstring(s->pktout, "env");
-           ssh2_pkt_addbool(s->pktout, 1);            /* want reply */
-           ssh2_pkt_addstring_start(s->pktout);
-           ssh2_pkt_addstring_data(s->pktout, var, varend-var);
-           ssh2_pkt_addstring(s->pktout, val);
+           if (subsys) {
+               s->pktout = ssh2_chanreq_init(ssh->mainchan, "subsystem",
+                                             ssh2_response_authconn, NULL);
+               ssh2_pkt_addstring(s->pktout, cmd);
+           } else if (*cmd) {
+               s->pktout = ssh2_chanreq_init(ssh->mainchan, "exec",
+                                             ssh2_response_authconn, NULL);
+               ssh2_pkt_addstring(s->pktout, cmd);
+           } else {
+               s->pktout = ssh2_chanreq_init(ssh->mainchan, "shell",
+                                             ssh2_response_authconn, NULL);
+           }
            ssh2_pkt_send(ssh, s->pktout);
 
-           s->num_env++;
-       }
-
-       logeventf(ssh, "Sent %d environment variables", s->num_env);
-
-       s->env_ok = 0;
-       s->env_left = s->num_env;
-
-       while (s->env_left > 0) {
            crWaitUntilV(pktin);
 
            if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
                if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
-                   bombout(("Unexpected response to environment request:"
+                   bombout(("Unexpected response to shell/command request:"
                             " packet type %d", pktin->type));
                    crStopV;
                }
-           } else {
-               s->env_ok++;
-           }
-
-           s->env_left--;
-       }
-
-       if (s->env_ok == s->num_env) {
-           logevent("All environment variables successfully set");
-       } else if (s->env_ok == 0) {
-           logevent("All environment variables refused");
-           c_write_str(ssh, "Server refused to set environment variables\r\n");
-       } else {
-           logeventf(ssh, "%d environment variables refused",
-                     s->num_env - s->env_ok);
-           c_write_str(ssh, "Server refused to set all environment variables\r\n");
-       }
-    }
-
-    /*
-     * Start a shell or a remote command. We may have to attempt
-     * this twice if the config data has provided a second choice
-     * of command.
-     */
-    if (ssh->mainchan) while (1) {
-       int subsys;
-       char *cmd;
-
-       if (ssh->fallback_cmd) {
-           subsys = ssh->cfg.ssh_subsys2;
-           cmd = ssh->cfg.remote_cmd_ptr2;
-       } else {
-           subsys = ssh->cfg.ssh_subsys;
-           cmd = ssh->cfg.remote_cmd_ptr;
-           if (!cmd) cmd = ssh->cfg.remote_cmd;
-       }
-
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid); /* recipient channel */
-       if (subsys) {
-           ssh2_pkt_addstring(s->pktout, "subsystem");
-           ssh2_pkt_addbool(s->pktout, 1);            /* want reply */
-           ssh2_pkt_addstring(s->pktout, cmd);
-       } else if (*cmd) {
-           ssh2_pkt_addstring(s->pktout, "exec");
-           ssh2_pkt_addbool(s->pktout, 1);            /* want reply */
-           ssh2_pkt_addstring(s->pktout, cmd);
-       } else {
-           ssh2_pkt_addstring(s->pktout, "shell");
-           ssh2_pkt_addbool(s->pktout, 1);            /* want reply */
-       }
-       ssh2_pkt_send(ssh, s->pktout);
-
-       crWaitUntilV(pktin);
-
-       if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
-           if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
-               bombout(("Unexpected response to shell/command request:"
-                        " packet type %d", pktin->type));
+               /*
+                * We failed to start the command. If this is the
+                * fallback command, we really are finished; if it's
+                * not, and if the fallback command exists, try falling
+                * back to it before complaining.
+                */
+               if (!ssh->fallback_cmd &&
+                   *conf_get_str(ssh->conf, CONF_remote_cmd2)) {
+                   logevent("Primary command failed; attempting fallback");
+                   ssh->fallback_cmd = TRUE;
+                   continue;
+               }
+               bombout(("Server refused to start a shell/command"));
                crStopV;
+           } else {
+               logevent("Started a shell/command");
            }
-           /*
-            * We failed to start the command. If this is the
-            * fallback command, we really are finished; if it's
-            * not, and if the fallback command exists, try falling
-            * back to it before complaining.
-            */
-           if (!ssh->fallback_cmd && ssh->cfg.remote_cmd_ptr2 != NULL) {
-               logevent("Primary command failed; attempting fallback");
-               ssh->fallback_cmd = TRUE;
-               continue;
-           }
-           bombout(("Server refused to start a shell/command"));
-           crStopV;
-       } else {
-           logevent("Started a shell/command");
+           break;
        }
-       break;
+    } else {
+       ssh->editing = ssh->echoing = TRUE;
     }
 
     ssh->state = SSH_STATE_SESSION;
@@ -7622,7 +10345,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
             * Try to send data on all channels if we can.
             */
            for (i = 0; NULL != (c = index234(ssh->channels, i)); i++)
-               ssh2_try_send_and_unthrottle(c);
+                if (c->type != CHAN_SHARING)
+                    ssh2_try_send_and_unthrottle(ssh, c);
        }
     }
 
@@ -7636,7 +10360,7 @@ static void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
 {
     /* log reason code in disconnect message */
     char *buf, *msg;
-    int nowlen, reason, msglen;
+    int reason, msglen;
 
     reason = ssh_pkt_getuint32(pktin);
     ssh_pkt_getstring(pktin, &msg, &msglen);
@@ -7650,14 +10374,14 @@ static void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
     }
     logevent(buf);
     sfree(buf);
-    buf = dupprintf("Disconnection message text: %n%.*s",
-                   &nowlen, msglen, msg);
+    buf = dupprintf("Disconnection message text: %.*s",
+                   msglen, msg);
     logevent(buf);
-    bombout(("Server sent disconnect message\ntype %d (%s):\n\"%s\"",
+    bombout(("Server sent disconnect message\ntype %d (%s):\n\"%.*s\"",
             reason,
             (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) ?
             ssh2_disconnect_reasons[reason] : "unknown",
-            buf+nowlen));
+            msglen, msg));
     sfree(buf);
 }
 
@@ -7666,15 +10390,33 @@ static void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
     /* log the debug message */
     char *msg;
     int msglen;
-    int always_display;
 
-    /* XXX maybe we should actually take notice of this */
-    always_display = ssh2_pkt_getbool(pktin);
+    /* XXX maybe we should actually take notice of the return value */
+    ssh2_pkt_getbool(pktin);
     ssh_pkt_getstring(pktin, &msg, &msglen);
 
     logeventf(ssh, "Remote debug message: %.*s", msglen, msg);
 }
 
+static void ssh2_msg_transport(Ssh ssh, struct Packet *pktin)
+{
+    do_ssh2_transport(ssh, NULL, 0, pktin);
+}
+
+/*
+ * Called if we receive a packet that isn't allowed by the protocol.
+ * This only applies to packets whose meaning PuTTY understands.
+ * Entirely unknown packets are handled below.
+ */
+static void ssh2_msg_unexpected(Ssh ssh, struct Packet *pktin)
+{
+    char *buf = dupprintf("Server protocol violation: unexpected %s packet",
+                         ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx,
+                                       pktin->type));
+    ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
+    sfree(buf);
+}
+
 static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
 {
     struct Packet *pktout;
@@ -7701,60 +10443,105 @@ static void ssh2_protocol_setup(Ssh ssh)
        ssh->packet_dispatch[i] = ssh2_msg_something_unimplemented;
 
     /*
-     * Any message we actually understand, we set to NULL so that
-     * the coroutines will get it.
+     * Initially, we only accept transport messages (and a few generic
+     * ones).  do_ssh2_authconn will add more when it starts.
+     * Messages that are understood but not currently acceptable go to
+     * ssh2_msg_unexpected.
      */
-    ssh->packet_dispatch[SSH2_MSG_UNIMPLEMENTED] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_SERVICE_REQUEST] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_KEXINIT] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_NEWKEYS] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_KEXDH_INIT] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_KEXDH_REPLY] = NULL;
-    /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REQUEST] = NULL; duplicate case value */
-    /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_GROUP] = NULL; duplicate case value */
-    ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_INIT] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REPLY] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = NULL;
-    /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = NULL; duplicate case value */
-    /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = NULL; duplicate case value */
-    ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = NULL;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_UNIMPLEMENTED] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_SERVICE_REQUEST] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_KEXINIT] = ssh2_msg_transport;
+    ssh->packet_dispatch[SSH2_MSG_NEWKEYS] = ssh2_msg_transport;
+    ssh->packet_dispatch[SSH2_MSG_KEXDH_INIT] = ssh2_msg_transport;
+    ssh->packet_dispatch[SSH2_MSG_KEXDH_REPLY] = ssh2_msg_transport;
+    /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REQUEST] = ssh2_msg_transport; duplicate case value */
+    /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_GROUP] = ssh2_msg_transport; duplicate case value */
+    ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_INIT] = ssh2_msg_transport;
+    ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REPLY] = ssh2_msg_transport;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = ssh2_msg_unexpected;
+    /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = ssh2_msg_unexpected; duplicate case value */
+    /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = ssh2_msg_unexpected; duplicate case value */
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_unexpected;
 
     /*
-     * These special message types we install handlers for.
+     * These messages have a special handler from the start.
      */
     ssh->packet_dispatch[SSH2_MSG_DISCONNECT] = ssh2_msg_disconnect;
     ssh->packet_dispatch[SSH2_MSG_IGNORE] = ssh_msg_ignore; /* shared with SSH-1 */
     ssh->packet_dispatch[SSH2_MSG_DEBUG] = ssh2_msg_debug;
 }
 
-static void ssh2_timer(void *ctx, long now)
+static void ssh2_bare_connection_protocol_setup(Ssh ssh)
+{
+    int i;
+
+    /*
+     * Most messages cause SSH2_MSG_UNIMPLEMENTED.
+     */
+    for (i = 0; i < 256; i++)
+       ssh->packet_dispatch[i] = ssh2_msg_something_unimplemented;
+
+    /*
+     * Initially, we set all ssh-connection messages to 'unexpected';
+     * do_ssh2_authconn will fill things in properly. We also handle a
+     * couple of messages from the transport protocol which aren't
+     * related to key exchange (UNIMPLEMENTED, IGNORE, DEBUG,
+     * DISCONNECT).
+     */
+    ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_unexpected;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_unexpected;
+
+    ssh->packet_dispatch[SSH2_MSG_UNIMPLEMENTED] = ssh2_msg_unexpected;
+
+    /*
+     * These messages have a special handler from the start.
+     */
+    ssh->packet_dispatch[SSH2_MSG_DISCONNECT] = ssh2_msg_disconnect;
+    ssh->packet_dispatch[SSH2_MSG_IGNORE] = ssh_msg_ignore;
+    ssh->packet_dispatch[SSH2_MSG_DEBUG] = ssh2_msg_debug;
+}
+
+static void ssh2_timer(void *ctx, unsigned long now)
 {
     Ssh ssh = (Ssh)ctx;
 
     if (ssh->state == SSH_STATE_CLOSED)
        return;
 
-    if (!ssh->kex_in_progress && ssh->cfg.ssh_rekey_time != 0 &&
-       now - ssh->next_rekey >= 0) {
+    if (!ssh->kex_in_progress && !ssh->bare_connection &&
+        conf_get_int(ssh->conf, CONF_ssh_rekey_time) != 0 &&
+       now == ssh->next_rekey) {
        do_ssh2_transport(ssh, "timeout", -1, NULL);
     }
 }
@@ -7774,24 +10561,30 @@ static void ssh2_protocol(Ssh ssh, void *vin, int inlen,
            do_ssh2_transport(ssh, "too much data received", -1, NULL);
     }
 
-    if (pktin && ssh->packet_dispatch[pktin->type]) {
+    if (pktin)
        ssh->packet_dispatch[pktin->type](ssh, pktin);
+    else if (!ssh->protocol_initial_phase_done)
+       do_ssh2_transport(ssh, in, inlen, pktin);
+    else
+       do_ssh2_authconn(ssh, in, inlen, pktin);
+}
+
+static void ssh2_bare_connection_protocol(Ssh ssh, void *vin, int inlen,
+                                          struct Packet *pktin)
+{
+    unsigned char *in = (unsigned char *)vin;
+    if (ssh->state == SSH_STATE_CLOSED)
        return;
-    }
 
-    if (!ssh->protocol_initial_phase_done ||
-       (pktin && pktin->type >= 20 && pktin->type < 50)) {
-       if (do_ssh2_transport(ssh, in, inlen, pktin) &&
-           !ssh->protocol_initial_phase_done) {
-           ssh->protocol_initial_phase_done = TRUE;
-           /*
-            * Allow authconn to initialise itself.
-            */
-           do_ssh2_authconn(ssh, NULL, 0, NULL);
-       }
-    } else {
-       do_ssh2_authconn(ssh, in, inlen, pktin);
-    }
+    if (pktin)
+       ssh->packet_dispatch[pktin->type](ssh, pktin);
+    else
+        do_ssh2_authconn(ssh, in, inlen, pktin);
+}
+
+static void ssh_cache_conf_values(Ssh ssh)
+{
+    ssh->logomitdata = conf_get_int(ssh->conf, CONF_logomitdata);
 }
 
 /*
@@ -7800,15 +10593,15 @@ static void ssh2_protocol(Ssh ssh, void *vin, int inlen,
  * Returns an error message, or NULL on success.
  */
 static const char *ssh_init(void *frontend_handle, void **backend_handle,
-                           Config *cfg,
-                           char *host, int port, char **realhost, int nodelay,
-                           int keepalive)
+                           Conf *conf, char *host, int port, char **realhost,
+                           int nodelay, int keepalive)
 {
     const char *p;
     Ssh ssh;
 
     ssh = snew(struct ssh_tag);
-    ssh->cfg = *cfg;                  /* STRUCTURE COPY */
+    ssh->conf = conf_copy(conf);
+    ssh_cache_conf_values(ssh);
     ssh->version = 0;                 /* when not ready yet */
     ssh->s = NULL;
     ssh->cipher = NULL;
@@ -7829,6 +10622,7 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->kex = NULL;
     ssh->kex_ctx = NULL;
     ssh->hostkey = NULL;
+    ssh->hostkey_str = NULL;
     ssh->exitcode = -1;
     ssh->close_expected = FALSE;
     ssh->clean_exit = FALSE;
@@ -7841,22 +10635,25 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->deferred_len = 0;
     ssh->deferred_size = 0;
     ssh->fallback_cmd = 0;
-    ssh->pkt_ctx = 0;
+    ssh->pkt_kctx = SSH2_PKTCTX_NOKEX;
+    ssh->pkt_actx = SSH2_PKTCTX_NOAUTH;
+    ssh->x11disp = NULL;
     ssh->x11auth = NULL;
+    ssh->x11authtree = newtree234(x11_authcmp);
     ssh->v1_compressing = FALSE;
     ssh->v2_outgoing_sequence = 0;
     ssh->ssh1_rdpkt_crstate = 0;
     ssh->ssh2_rdpkt_crstate = 0;
-    ssh->do_ssh_init_crstate = 0;
+    ssh->ssh2_bare_rdpkt_crstate = 0;
     ssh->ssh_gotdata_crstate = 0;
     ssh->do_ssh1_connection_crstate = 0;
-    ssh->do_ssh1_login_crstate = 0;
-    ssh->do_ssh2_transport_crstate = 0;
-    ssh->do_ssh2_authconn_crstate = 0;
     ssh->do_ssh_init_state = NULL;
+    ssh->do_ssh_connection_init_state = NULL;
     ssh->do_ssh1_login_state = NULL;
     ssh->do_ssh2_transport_state = NULL;
     ssh->do_ssh2_authconn_state = NULL;
+    ssh->v_c = NULL;
+    ssh->v_s = NULL;
     ssh->mainchan = NULL;
     ssh->throttled_all = 0;
     ssh->v1_stdout_throttling = 0;
@@ -7867,6 +10664,13 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->deferred_rekey_reason = NULL;
     bufchain_init(&ssh->queued_incoming_data);
     ssh->frozen = FALSE;
+    ssh->username = NULL;
+    ssh->sent_console_eof = FALSE;
+    ssh->got_pty = FALSE;
+    ssh->bare_connection = FALSE;
+    ssh->X11_fwd_enabled = FALSE;
+    ssh->connshare = NULL;
+    ssh->attempting_connshare = FALSE;
 
     *backend_handle = ssh;
 
@@ -7876,8 +10680,8 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
 #endif
 
     ssh->frontend = frontend_handle;
-    ssh->term_width = ssh->cfg.width;
-    ssh->term_height = ssh->cfg.height;
+    ssh->term_width = conf_get_int(ssh->conf, CONF_width);
+    ssh->term_height = conf_get_int(ssh->conf, CONF_height);
 
     ssh->channels = NULL;
     ssh->rportfwds = NULL;
@@ -7886,7 +10690,7 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->send_ok = 0;
     ssh->editing = 0;
     ssh->echoing = 0;
-    ssh->v1_throttle_count = 0;
+    ssh->conn_throttle_count = 0;
     ssh->overall_bufsize = 0;
     ssh->fallback_cmd = 0;
 
@@ -7898,14 +10702,21 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
 
     ssh->incoming_data_size = ssh->outgoing_data_size =
        ssh->deferred_data_size = 0L;
-    ssh->max_data_size = parse_blocksize(ssh->cfg.ssh_rekey_data);
+    ssh->max_data_size = parse_blocksize(conf_get_str(ssh->conf,
+                                                     CONF_ssh_rekey_data));
     ssh->kex_in_progress = FALSE;
 
+#ifndef NO_GSSAPI
+    ssh->gsslibs = NULL;
+#endif
+
+    random_ref(); /* do this now - may be needed by sharing setup code */
+
     p = connect_to_host(ssh, host, port, realhost, nodelay, keepalive);
-    if (p != NULL)
+    if (p != NULL) {
+        random_unref();
        return p;
-
-    random_ref();
+    }
 
     return NULL;
 }
@@ -7915,6 +10726,7 @@ static void ssh_free(void *handle)
     Ssh ssh = (Ssh) handle;
     struct ssh_channel *c;
     struct ssh_rportfwd *pf;
+    struct X11FakeAuth *auth;
 
     if (ssh->v1_cipher_ctx)
        ssh->cipher->free_context(ssh->v1_cipher_ctx);
@@ -7949,7 +10761,7 @@ static void ssh_free(void *handle)
     while (ssh->qhead) {
        struct queued_handler *qh = ssh->qhead;
        ssh->qhead = qh->next;
-       sfree(ssh->qhead);
+       sfree(qh);
     }
     ssh->qhead = ssh->qtail = NULL;
 
@@ -7957,33 +10769,55 @@ static void ssh_free(void *handle)
        while ((c = delpos234(ssh->channels, 0)) != NULL) {
            switch (c->type) {
              case CHAN_X11:
-               if (c->u.x11.s != NULL)
-                   x11_close(c->u.x11.s);
+               if (c->u.x11.xconn != NULL)
+                   x11_close(c->u.x11.xconn);
                break;
              case CHAN_SOCKDATA:
-               if (c->u.pfd.s != NULL)
-                   pfd_close(c->u.pfd.s);
+             case CHAN_SOCKDATA_DORMANT:
+               if (c->u.pfd.pf != NULL)
+                   pfd_close(c->u.pfd.pf);
                break;
            }
+           if (ssh->version == 2) {
+               struct outstanding_channel_request *ocr, *nocr;
+               ocr = c->v.v2.chanreq_head;
+               while (ocr) {
+                   ocr->handler(c, NULL, ocr->ctx);
+                   nocr = ocr->next;
+                   sfree(ocr);
+                   ocr = nocr;
+               }
+               bufchain_clear(&c->v.v2.outbuffer);
+           }
            sfree(c);
        }
        freetree234(ssh->channels);
        ssh->channels = NULL;
     }
 
+    if (ssh->connshare)
+        sharestate_free(ssh->connshare);
+
     if (ssh->rportfwds) {
        while ((pf = delpos234(ssh->rportfwds, 0)) != NULL)
-           sfree(pf);
+           free_rportfwd(pf);
        freetree234(ssh->rportfwds);
        ssh->rportfwds = NULL;
     }
     sfree(ssh->deferred_send_data);
-    if (ssh->x11auth)
-       x11_free_auth(ssh->x11auth);
+    if (ssh->x11disp)
+       x11_free_display(ssh->x11disp);
+    while ((auth = delpos234(ssh->x11authtree, 0)) != NULL)
+        x11_free_fake_auth(auth);
+    freetree234(ssh->x11authtree);
     sfree(ssh->do_ssh_init_state);
     sfree(ssh->do_ssh1_login_state);
     sfree(ssh->do_ssh2_transport_state);
     sfree(ssh->do_ssh2_authconn_state);
+    sfree(ssh->v_c);
+    sfree(ssh->v_s);
+    sfree(ssh->fullhostname);
+    sfree(ssh->hostkey_str);
     if (ssh->crcda_ctx) {
        crcda_free_context(ssh->crcda_ctx);
        ssh->crcda_ctx = NULL;
@@ -7994,6 +10828,12 @@ static void ssh_free(void *handle)
     if (ssh->pinger)
        pinger_free(ssh->pinger);
     bufchain_clear(&ssh->queued_incoming_data);
+    sfree(ssh->username);
+    conf_free(ssh->conf);
+#ifndef NO_GSSAPI
+    if (ssh->gsslibs)
+       ssh_gss_cleanup(ssh->gsslibs);
+#endif
     sfree(ssh);
 
     random_unref();
@@ -8002,22 +10842,24 @@ static void ssh_free(void *handle)
 /*
  * Reconfigure the SSH backend.
  */
-static void ssh_reconfig(void *handle, Config *cfg)
+static void ssh_reconfig(void *handle, Conf *conf)
 {
     Ssh ssh = (Ssh) handle;
     char *rekeying = NULL, rekey_mandatory = FALSE;
     unsigned long old_max_data_size;
+    int i, rekey_time;
 
-    pinger_reconfig(ssh->pinger, &ssh->cfg, cfg);
+    pinger_reconfig(ssh->pinger, ssh->conf, conf);
     if (ssh->portfwds)
-       ssh_setup_portfwd(ssh, cfg);
+       ssh_setup_portfwd(ssh, conf);
 
-    if (ssh->cfg.ssh_rekey_time != cfg->ssh_rekey_time &&
-       cfg->ssh_rekey_time != 0) {
-       long new_next = ssh->last_rekey + cfg->ssh_rekey_time*60*TICKSPERSEC;
-       long now = GETTICKCOUNT();
+    rekey_time = conf_get_int(conf, CONF_ssh_rekey_time);
+    if (conf_get_int(ssh->conf, CONF_ssh_rekey_time) != rekey_time &&
+       rekey_time != 0) {
+       unsigned long new_next = ssh->last_rekey + rekey_time*60*TICKSPERSEC;
+       unsigned long now = GETTICKCOUNT();
 
-       if (new_next - now < 0) {
+       if (now - ssh->last_rekey > rekey_time*60*TICKSPERSEC) {
            rekeying = "timeout shortened";
        } else {
            ssh->next_rekey = schedule_timer(new_next - now, ssh2_timer, ssh);
@@ -8025,7 +10867,8 @@ static void ssh_reconfig(void *handle, Config *cfg)
     }
 
     old_max_data_size = ssh->max_data_size;
-    ssh->max_data_size = parse_blocksize(cfg->ssh_rekey_data);
+    ssh->max_data_size = parse_blocksize(conf_get_str(ssh->conf,
+                                                     CONF_ssh_rekey_data));
     if (old_max_data_size != ssh->max_data_size &&
        ssh->max_data_size != 0) {
        if (ssh->outgoing_data_size > ssh->max_data_size ||
@@ -8033,21 +10876,29 @@ static void ssh_reconfig(void *handle, Config *cfg)
            rekeying = "data limit lowered";
     }
 
-    if (ssh->cfg.compression != cfg->compression) {
+    if (conf_get_int(ssh->conf, CONF_compression) !=
+       conf_get_int(conf, CONF_compression)) {
        rekeying = "compression setting changed";
        rekey_mandatory = TRUE;
     }
 
-    if (ssh->cfg.ssh2_des_cbc != cfg->ssh2_des_cbc ||
-       memcmp(ssh->cfg.ssh_cipherlist, cfg->ssh_cipherlist,
-              sizeof(ssh->cfg.ssh_cipherlist))) {
+    for (i = 0; i < CIPHER_MAX; i++)
+       if (conf_get_int_int(ssh->conf, CONF_ssh_cipherlist, i) !=
+           conf_get_int_int(conf, CONF_ssh_cipherlist, i)) {
+       rekeying = "cipher settings changed";
+       rekey_mandatory = TRUE;
+    }
+    if (conf_get_int(ssh->conf, CONF_ssh2_des_cbc) !=
+       conf_get_int(conf, CONF_ssh2_des_cbc)) {
        rekeying = "cipher settings changed";
        rekey_mandatory = TRUE;
     }
 
-    ssh->cfg = *cfg;                  /* STRUCTURE COPY */
+    conf_free(ssh->conf);
+    ssh->conf = conf_copy(conf);
+    ssh_cache_conf_values(ssh);
 
-    if (rekeying) {
+    if (!ssh->bare_connection && rekeying) {
        if (!ssh->kex_in_progress) {
            do_ssh2_transport(ssh, rekeying, -1, NULL);
        } else if (rekey_mandatory) {
@@ -8093,7 +10944,7 @@ static int ssh_sendbuffer(void *handle)
     if (ssh->version == 1) {
        return override_value;
     } else if (ssh->version == 2) {
-       if (!ssh->mainchan || ssh->mainchan->closes > 0)
+       if (!ssh->mainchan)
            return override_value;
        else
            return (override_value +
@@ -8123,17 +10974,15 @@ static void ssh_size(void *handle, int width, int height)
        ssh->size_needed = TRUE;       /* buffer for later */
        break;
       case SSH_STATE_SESSION:
-       if (!ssh->cfg.nopty) {
+       if (!conf_get_int(ssh->conf, CONF_nopty)) {
            if (ssh->version == 1) {
                send_packet(ssh, SSH1_CMSG_WINDOW_SIZE,
                            PKT_INT, ssh->term_height,
                            PKT_INT, ssh->term_width,
                            PKT_INT, 0, PKT_INT, 0, PKT_END);
            } else if (ssh->mainchan) {
-               pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-               ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
-               ssh2_pkt_addstring(pktout, "window-change");
-               ssh2_pkt_addbool(pktout, 0);
+               pktout = ssh2_chanreq_init(ssh->mainchan, "window-change",
+                                          NULL, NULL);
                ssh2_pkt_adduint32(pktout, ssh->term_width);
                ssh2_pkt_adduint32(pktout, ssh->term_height);
                ssh2_pkt_adduint32(pktout, 0);
@@ -8154,14 +11003,16 @@ static const struct telnet_special *ssh_get_specials(void *handle)
     static const struct telnet_special ssh1_ignore_special[] = {
        {"IGNORE message", TS_NOP}
     };
-    static const struct telnet_special ssh2_transport_specials[] = {
+    static const struct telnet_special ssh2_ignore_special[] = {
        {"IGNORE message", TS_NOP},
+    };
+    static const struct telnet_special ssh2_rekey_special[] = {
        {"Repeat key exchange", TS_REKEY},
     };
     static const struct telnet_special ssh2_session_specials[] = {
        {NULL, TS_SEP},
        {"Break", TS_BRK},
-       /* These are the signal names defined by draft-ietf-secsh-connect-23.
+       /* These are the signal names defined by RFC 4254.
         * They include all the ISO C signals, but are a subset of the POSIX
         * required signals. */
        {"SIGINT (Interrupt)", TS_SIGINT},
@@ -8180,7 +11031,8 @@ static const struct telnet_special *ssh_get_specials(void *handle)
        {NULL, TS_EXITMENU}
     };
     /* XXX review this length for any changes: */
-    static struct telnet_special ssh_specials[lenof(ssh2_transport_specials) +
+    static struct telnet_special ssh_specials[lenof(ssh2_ignore_special) +
+                                             lenof(ssh2_rekey_special) +
                                              lenof(ssh2_session_specials) +
                                              lenof(specials_end)];
     Ssh ssh = (Ssh) handle;
@@ -8199,7 +11051,10 @@ static const struct telnet_special *ssh_get_specials(void *handle)
        if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE))
            ADD_SPECIALS(ssh1_ignore_special);
     } else if (ssh->version == 2) {
-       ADD_SPECIALS(ssh2_transport_specials);
+       if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE))
+           ADD_SPECIALS(ssh2_ignore_special);
+       if (!(ssh->remote_bugs & BUG_SSH2_REKEY) && !ssh->bare_connection)
+           ADD_SPECIALS(ssh2_rekey_special);
        if (ssh->mainchan)
            ADD_SPECIALS(ssh2_session_specials);
     } /* else we're not ready yet */
@@ -8236,9 +11091,7 @@ static void ssh_special(void *handle, Telnet_Special code)
        if (ssh->version == 1) {
            send_packet(ssh, SSH1_CMSG_EOF, PKT_END);
        } else if (ssh->mainchan) {
-           struct Packet *pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_EOF);
-           ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
-           ssh2_pkt_send(ssh, pktout);
+            sshfwd_write_eof(ssh->mainchan);
             ssh->send_ok = 0;          /* now stop trying to read from stdin */
        }
        logevent("Sent EOF message");
@@ -8249,12 +11102,15 @@ static void ssh_special(void *handle, Telnet_Special code)
            if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE))
                send_packet(ssh, SSH1_MSG_IGNORE, PKT_STR, "", PKT_END);
        } else {
-           pktout = ssh2_pkt_init(SSH2_MSG_IGNORE);
-           ssh2_pkt_addstring_start(pktout);
-           ssh2_pkt_send_noqueue(ssh, pktout);
+           if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) {
+               pktout = ssh2_pkt_init(SSH2_MSG_IGNORE);
+               ssh2_pkt_addstring_start(pktout);
+               ssh2_pkt_send_noqueue(ssh, pktout);
+           }
        }
     } else if (code == TS_REKEY) {
-       if (!ssh->kex_in_progress && ssh->version == 2) {
+       if (!ssh->kex_in_progress && !ssh->bare_connection &&
+            ssh->version == 2) {
            do_ssh2_transport(ssh, "at user request", -1, NULL);
        }
     } else if (code == TS_BRK) {
@@ -8263,10 +11119,7 @@ static void ssh_special(void *handle, Telnet_Special code)
        if (ssh->version == 1) {
            logevent("Unable to send BREAK signal in SSH-1");
        } else if (ssh->mainchan) {
-           pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-           ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
-           ssh2_pkt_addstring(pktout, "break");
-           ssh2_pkt_addbool(pktout, 0);
+           pktout = ssh2_chanreq_init(ssh->mainchan, "break", NULL, NULL);
            ssh2_pkt_adduint32(pktout, 0);   /* default break length */
            ssh2_pkt_send(ssh, pktout);
        }
@@ -8291,10 +11144,7 @@ static void ssh_special(void *handle, Telnet_Special code)
        if (signame) {
            /* It's a signal. */
            if (ssh->version == 2 && ssh->mainchan) {
-               pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-               ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
-               ssh2_pkt_addstring(pktout, "signal");
-               ssh2_pkt_addbool(pktout, 0);
+               pktout = ssh2_chanreq_init(ssh->mainchan, "signal", NULL, NULL);
                ssh2_pkt_addstring(pktout, signame);
                ssh2_pkt_send(ssh, pktout);
                logeventf(ssh, "Sent signal SIG%s", signame);
@@ -8305,25 +11155,56 @@ static void ssh_special(void *handle, Telnet_Special code)
     }
 }
 
-void *new_sock_channel(void *handle, Socket s)
+void *new_sock_channel(void *handle, struct PortForwarding *pf)
 {
     Ssh ssh = (Ssh) handle;
     struct ssh_channel *c;
     c = snew(struct ssh_channel);
-    c->ssh = ssh;
 
-    if (c) {
-       c->halfopen = TRUE;
-       c->localid = alloc_channel_id(ssh);
-       c->closes = 0;
-       c->type = CHAN_SOCKDATA_DORMANT;/* identify channel type */
-       c->u.pfd.s = s;
-       bufchain_init(&c->v.v2.outbuffer);
-       add234(ssh->channels, c);
-    }
+    c->ssh = ssh;
+    ssh2_channel_init(c);
+    c->halfopen = TRUE;
+    c->type = CHAN_SOCKDATA_DORMANT;/* identify channel type */
+    c->u.pfd.pf = pf;
+    add234(ssh->channels, c);
     return c;
 }
 
+unsigned ssh_alloc_sharing_channel(Ssh ssh, void *sharing_ctx)
+{
+    struct ssh_channel *c;
+    c = snew(struct ssh_channel);
+
+    c->ssh = ssh;
+    ssh2_channel_init(c);
+    c->type = CHAN_SHARING;
+    c->u.sharing.ctx = sharing_ctx;
+    add234(ssh->channels, c);
+    return c->localid;
+}
+
+void ssh_delete_sharing_channel(Ssh ssh, unsigned localid)
+{
+    struct ssh_channel *c;
+
+    c = find234(ssh->channels, &localid, ssh_channelfind);
+    if (c)
+        ssh_channel_destroy(c);
+}
+
+void ssh_send_packet_from_downstream(Ssh ssh, unsigned id, int type,
+                                     const void *data, int datalen,
+                                     const char *additional_log_text)
+{
+    struct Packet *pkt;
+
+    pkt = ssh2_pkt_init(type);
+    pkt->downstream_id = id;
+    pkt->additional_log_text = additional_log_text;
+    ssh2_pkt_adddata(pkt, data, datalen);
+    ssh2_pkt_send(ssh, pkt);
+}
+
 /*
  * This is called when stdout/stderr (the entity to which
  * from_backend sends data) manages to clear some backlog.
@@ -8331,15 +11212,34 @@ void *new_sock_channel(void *handle, Socket s)
 static void ssh_unthrottle(void *handle, int bufsize)
 {
     Ssh ssh = (Ssh) handle;
+    int buflimit;
+
     if (ssh->version == 1) {
        if (ssh->v1_stdout_throttling && bufsize < SSH1_BUFFER_LIMIT) {
            ssh->v1_stdout_throttling = 0;
-           ssh1_throttle(ssh, -1);
+           ssh_throttle_conn(ssh, -1);
        }
     } else {
-       if (ssh->mainchan && ssh->mainchan->closes == 0)
-           ssh2_set_window(ssh->mainchan, OUR_V2_WINSIZE - bufsize);
+       if (ssh->mainchan) {
+           ssh2_set_window(ssh->mainchan,
+                           bufsize < ssh->mainchan->v.v2.locmaxwin ?
+                           ssh->mainchan->v.v2.locmaxwin - bufsize : 0);
+           if (ssh_is_simple(ssh))
+               buflimit = 0;
+           else
+               buflimit = ssh->mainchan->v.v2.locmaxwin;
+           if (ssh->mainchan->throttling_conn && bufsize <= buflimit) {
+               ssh->mainchan->throttling_conn = 0;
+               ssh_throttle_conn(ssh, -1);
+           }
+       }
     }
+
+    /*
+     * Now process any SSH connection data that was stashed in our
+     * queue while we were frozen.
+     */
+    ssh_process_queued_incoming_data(ssh);
 }
 
 void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
@@ -8348,7 +11248,7 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
     Ssh ssh = c->ssh;
     struct Packet *pktout;
 
-    logeventf(ssh, "Opening forwarded connection to %s:%d", hostname, port);
+    logeventf(ssh, "Opening connection to %s:%d for %s", hostname, port, org);
 
     if (ssh->version == 1) {
        send_packet(ssh, SSH1_MSG_PORT_OPEN,
@@ -8358,30 +11258,32 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
                    /* PKT_STR, <org:orgport>, */
                    PKT_END);
     } else {
-       pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
-       ssh2_pkt_addstring(pktout, "direct-tcpip");
-       ssh2_pkt_adduint32(pktout, c->localid);
-       c->v.v2.locwindow = OUR_V2_WINSIZE;
-       ssh2_pkt_adduint32(pktout, c->v.v2.locwindow);/* our window size */
-       ssh2_pkt_adduint32(pktout, OUR_V2_MAXPKT);      /* our max pkt size */
-       ssh2_pkt_addstring(pktout, hostname);
+       pktout = ssh2_chanopen_init(c, "direct-tcpip");
+        {
+            char *trimmed_host = host_strduptrim(hostname);
+            ssh2_pkt_addstring(pktout, trimmed_host);
+            sfree(trimmed_host);
+        }
        ssh2_pkt_adduint32(pktout, port);
        /*
         * We make up values for the originator data; partly it's
         * too much hassle to keep track, and partly I'm not
         * convinced the server should be told details like that
         * about my local network configuration.
+        * The "originator IP address" is syntactically a numeric
+        * IP address, and some servers (e.g., Tectia) get upset
+        * if it doesn't match this syntax.
         */
-       ssh2_pkt_addstring(pktout, "client-side-connection");
+       ssh2_pkt_addstring(pktout, "0.0.0.0");
        ssh2_pkt_adduint32(pktout, 0);
        ssh2_pkt_send(ssh, pktout);
     }
 }
 
-static Socket ssh_socket(void *handle)
+static int ssh_connected(void *handle)
 {
     Ssh ssh = (Ssh) handle;
-    return ssh->s;
+    return ssh->s != NULL;
 }
 
 static int ssh_sendok(void *handle)
@@ -8418,17 +11320,23 @@ static int ssh_return_exitcode(void *handle)
     if (ssh->s != NULL)
         return -1;
     else
-        return (ssh->exitcode >= 0 ? ssh->exitcode : 0);
+        return (ssh->exitcode >= 0 ? ssh->exitcode : INT_MAX);
 }
 
 /*
- * cfg_info for SSH is the currently running version of the
- * protocol. (1 for 1; 2 for 2; 0 for not-decided-yet.)
+ * cfg_info for SSH is the protocol running in this session.
+ * (1 or 2 for the full SSH-1 or SSH-2 protocol; -1 for the bare
+ * SSH-2 connection protocol, i.e. a downstream; 0 for not-decided-yet.)
  */
 static int ssh_cfg_info(void *handle)
 {
     Ssh ssh = (Ssh) handle;
-    return ssh->version;
+    if (ssh->version == 0)
+       return 0; /* don't know yet */
+    else if (ssh->bare_connection)
+       return -1;
+    else
+       return ssh->version;
 }
 
 /*
@@ -8451,7 +11359,7 @@ Backend ssh_backend = {
     ssh_size,
     ssh_special,
     ssh_get_specials,
-    ssh_socket,
+    ssh_connected,
     ssh_return_exitcode,
     ssh_sendok,
     ssh_ldisc,
@@ -8459,5 +11367,7 @@ Backend ssh_backend = {
     ssh_provide_logctx,
     ssh_unthrottle,
     ssh_cfg_info,
+    "ssh",
+    PROT_SSH,
     22
 };