Handle packets with no type byte by returning SSH_MSG_UNIMPLEMENTED.

[PuTTY.git] / ssh.c

diff --git a/ssh.c b/ssh.c
index d53b392601db8bc1794b46e4f7ae13cc0de458c3..1f8a214b6a07e165872d4e83cfecd8af7517ac21 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -364,6 +364,7 @@ static void do_ssh2_authconn(Ssh ssh, const 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);
+static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin);
 
 /*
  * Buffer management constants. There are several of these for
@@ -1834,6 +1835,15 @@ static struct Packet *ssh2_rdpkt(Ssh ssh, const unsigned char **data,
        }
     }
 
+    /*
+     * RFC 4253 doesn't explicitly say that completely empty packets
+     * with no type byte are forbidden, so treat them as deserving
+     * an SSH_MSG_UNIMPLEMENTED.
+     */
+    if (st->pktin->length <= 5) { /* == 5 we hope, but robustness */
+        ssh2_msg_something_unimplemented(ssh, st->pktin);
+        crStop(NULL);
+    }
     /*
      * pktin->body and pktin->length should identify the semantic
      * content of the packet, excluding the initial type byte.
@@ -3549,35 +3559,20 @@ static void ssh_sent(Plug plug, int bufsize)
        ssh_throttle_all(ssh, 0, bufsize);
 }
 
-/*
- * Connect to specified host and port.
- * Returns an error message, or NULL on success.
- * Also places the canonical host name into `realhost'. It must be
- * freed by the caller.
- */
-static const char *connect_to_host(Ssh ssh, const char *host, int port,
-                                  char **realhost, int nodelay, int keepalive)
+static void ssh_hostport_setup(const char *host, int port, Conf *conf,
+                               char **savedhost, int *savedport,
+                               char **loghost_ret)
 {
-    static const struct plug_function_table fn_table = {
-       ssh_socket_log,
-       ssh_closing,
-       ssh_receive,
-       ssh_sent,
-       NULL
-    };
+    char *loghost = conf_get_str(conf, CONF_loghost);
+    if (loghost_ret)
+        *loghost_ret = loghost;
 
-    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 */
+       *savedport = 22;               /* default ssh port */
 
        /*
         * A colon suffix on the hostname string also lets us affect
@@ -3588,17 +3583,58 @@ static const char *connect_to_host(Ssh ssh, const char *host, int port,
        if (colon && colon == host_strchr(tmphost, ':')) {
            *colon++ = '\0';
            if (*colon)
-               ssh->savedport = atoi(colon);
+               *savedport = atoi(colon);
        }
 
-        ssh->savedhost = host_strduptrim(tmphost);
+        *savedhost = host_strduptrim(tmphost);
         sfree(tmphost);
     } else {
-       ssh->savedhost = host_strduptrim(host);
+       *savedhost = host_strduptrim(host);
        if (port < 0)
            port = 22;                 /* default ssh port */
-       ssh->savedport = port;
+       *savedport = port;
     }
+}
+
+static int ssh_test_for_upstream(const char *host, int port, Conf *conf)
+{
+    char *savedhost;
+    int savedport;
+    int ret;
+
+    random_ref(); /* platform may need this to determine share socket name */
+    ssh_hostport_setup(host, port, conf, &savedhost, &savedport, NULL);
+    ret = ssh_share_test_for_upstream(savedhost, savedport, conf);
+    sfree(savedhost);
+    random_unref();
+
+    return ret;
+}
+
+/*
+ * Connect to specified host and port.
+ * Returns an error message, or NULL on success.
+ * Also places the canonical host name into `realhost'. It must be
+ * freed by the caller.
+ */
+static const char *connect_to_host(Ssh ssh, const char *host, int port,
+                                  char **realhost, int nodelay, int keepalive)
+{
+    static const struct plug_function_table fn_table = {
+       ssh_socket_log,
+       ssh_closing,
+       ssh_receive,
+       ssh_sent,
+       NULL
+    };
+
+    SockAddr addr;
+    const char *err;
+    char *loghost;
+    int addressfamily, sshprot;
+
+    ssh_hostport_setup(host, port, ssh->conf,
+                       &ssh->savedhost, &ssh->savedport, &loghost);
 
     ssh->fn = &fn_table;               /* make 'ssh' usable as a Plug */
 
@@ -11634,6 +11670,7 @@ Backend ssh_backend = {
     ssh_provide_logctx,
     ssh_unthrottle,
     ssh_cfg_info,
+    ssh_test_for_upstream,
     "ssh",
     PROT_SSH,
     22