Implement part of `ssh2-generality': introduce the ability to tell

PuTTY / Plink not to run a remote shell/command at all. Supported in
the GUI configuration and via the (OpenSSH-like) -N command-line
option.

No effort is currently made to arrange `nice' UI properties. If you
do this in GUI PuTTY, a full-size terminal window will still be
created, and will sit there with almost nothing in it throughout
your session. If you do it in Plink, Plink will not accept any kind
of request to terminate gracefully; you'll have to ^C or kill it.
Nonetheless, even this little will be useful to some people...

git-svn-id: http://svn.tartarus.org/sgt/putty@4614 cda61777-01e9-0310-a592-d414129be87e

diff --git a/cmdline.c b/cmdline.c
index 29456a1f18ef1fb6c177632a84789b3e6545f126..82cd4f86f67f280adea7a43522f2c3f8d4dce239 100644 (file)
--- a/cmdline.c
+++ b/cmdline.c
@@ -314,6 +314,13 @@ int cmdline_process_param(char *p, char *value, int need_save, Config *cfg)
        cfg->nopty = 1;
     }
 
+    if (!strcmp(p, "-N")) {
+       RETURN(1);
+       UNAVAILABLE_IN(TOOLTYPE_FILETRANSFER | TOOLTYPE_NONNETWORK);
+       SAVEABLE(0);
+       cfg->ssh_no_shell = 1;
+    }
+
     if (!strcmp(p, "-C")) {
        RETURN(1);
        UNAVAILABLE_IN(TOOLTYPE_NONNETWORK);

diff --git a/config.c b/config.c
index cbf31698e0edda9e5855d49c5ab391b3483d6544..8588b23c31530764a5399148ab7e67f1a50226b7 100644 (file)
--- a/config.c
+++ b/config.c
@@ -1491,6 +1491,10 @@ void setup_config_box(struct controlbox *b, struct sesslist *sesslist,
                      HELPCTX(ssh_nopty),
                      dlg_stdcheckbox_handler,
                      I(offsetof(Config,nopty)));
+       ctrl_checkbox(s, "Don't start a shell or command at all", 'n',
+                     HELPCTX(ssh_noshell),
+                     dlg_stdcheckbox_handler,
+                     I(offsetof(Config,ssh_no_shell)));
        ctrl_checkbox(s, "Enable compression", 'e',
                      HELPCTX(ssh_compress),
                      dlg_stdcheckbox_handler,
@@ -1502,7 +1506,7 @@ void setup_config_box(struct controlbox *b, struct sesslist *sesslist,
                          "1 only", 'l', I(0),
                          "1", '1', I(1),
                          "2", '2', I(2),
-                         "2 only", 'n', I(3), NULL);
+                         "2 only", 'y', I(3), NULL);
 
        s = ctrl_getset(b, "Connection/SSH", "encryption", "Encryption options");
        c = ctrl_draglist(s, "Encryption cipher selection policy:", 's',

diff --git a/doc/config.but b/doc/config.but
index 4b4271bcdbdd0dd4a20d1121521b62c2bffb5235..92b479b257fe69e69b1c9a23c7975109244dd5a1 100644 (file)
--- a/doc/config.but
+++ b/doc/config.but
@@ -1,4 +1,4 @@
-\versionid $Id: config.but,v 1.92 2004/10/06 22:31:07 jacob Exp $
+\versionid $Id: config.but,v 1.93 2004/10/13 13:43:11 simon Exp $
 
 \C{config} Configuring PuTTY
 
@@ -1936,6 +1936,27 @@ in a pseudo-terminal. In PuTTY, this is generally only useful for
 very specialist purposes; although in Plink (see \k{plink}) it is
 the usual way of working.
 
+\S{config-ssh-noshell} \q{Don't start a shell or command at all}
+
+\cfg{winhelp-topic}{ssh.noshell}
+
+If you tick this box, PuTTY will not attempt to run a shell or
+command after connecting to the remote server. You might want to use
+this option if you are only using the SSH connection for port
+forwarding, and your user account on the server does not have the
+ability to run a shell.
+
+This feature is only available in SSH protocol version 2 (since the
+version 1 protocol assumes you will always want to run a shell).
+
+This feature can also be enabled using the \c{-N} command-line
+option; see \k{using-cmdline-noshell}.
+
+If you use this feature in Plink, you will not be able to terminate
+the Plink process by any graceful means; the only way to kill it
+will be by pressing Control-C or sending a kill signal from another
+program.
+
 \S{config-ssh-comp} \q{Enable compression}
 
 \cfg{winhelp-topic}{ssh.compress}

diff --git a/doc/index.but b/doc/index.but
index 806acfd39e48a34c7895885b51702a5e721500b6..efc560dd5bb26a8b83242fd51cae1ea6b052a045 100644 (file)
--- a/doc/index.but
+++ b/doc/index.but
@@ -104,6 +104,7 @@ saved sessions from
 \IM{-T-upper} \c{-T} command-line option
 \IM{-t} \c{-t} command-line option
 \IM{-C-upper} \c{-C} command-line option
+\IM{-N-upper} \c{-N} command-line option
 \IM{-1} \c{-1} command-line option
 \IM{-2} \c{-2} command-line option
 \IM{-i} \c{-i} command-line option

diff --git a/doc/using.but b/doc/using.but
index 575603d8d7916116415fde647849b9f3660ffdce..cda9b3b4ac3b408dc8a23b8257aa7c524d8aff26 100644 (file)
--- a/doc/using.but
+++ b/doc/using.but
@@ -1,4 +1,4 @@
-\versionid $Id: using.but,v 1.33 2004/10/06 22:31:07 jacob Exp $
+\versionid $Id: using.but,v 1.34 2004/10/13 13:43:11 simon Exp $
 
 \C{using} Using PuTTY
 
@@ -694,6 +694,24 @@ configuration box (see \k{config-ssh-pty}).
 These options are not available in the file transfer tools PSCP and
 PSFTP.
 
+\S2{using-cmdline-noshell} \I{-N-upper}\c{-N}: suppress starting a
+shell or command
+
+The \c{-N} option prevents PuTTY from attempting to start a shell or
+command on the remote server. You might want to use this option if
+you are only using the SSH connection for port forwarding, and your
+user account on the server does not have the ability to run a shell.
+
+This feature is only available in SSH protocol version 2 (since the
+version 1 protocol assumes you will always want to run a shell).
+
+This option is equivalent to the \q{Don't start a shell or command
+at all} checkbox in the SSH panel of the PuTTY configuration box
+(see \k{config-ssh-noshell}).
+
+These options are not available in the file transfer tools PSCP and
+PSFTP.
+
 \S2{using-cmdline-compress} \I{-C-upper}\c{-C}: enable \i{compression}
 
 The \c{-C} option enables compression of the data sent across the

diff --git a/putty.h b/putty.h
index 780b4eb46979dd7795c96805c9a1790549588068..827f449c52ff45c9201bcc70da206c8139996f3c 100644 (file)
--- a/putty.h
+++ b/putty.h
@@ -358,6 +358,7 @@ struct config_tag {
     int try_ki_auth;
     int ssh_subsys;                   /* run a subsystem rather than a command */
     int ssh_subsys2;                  /* fallback to go with remote_cmd2 */
+    int ssh_no_shell;                 /* avoid running a shell */
     /* Telnet options */
     char termtype[32];
     char termspeed[32];

diff --git a/settings.c b/settings.c
index 679fab151811870bfd558713dffd4b1620caccb0..b0f223e97540dc15df88cd2d091f2f873843049a 100644 (file)
--- a/settings.c
+++ b/settings.c
@@ -228,6 +228,7 @@ void save_open_settings(void *sesskey, int do_host, Config *cfg)
           cfg->ssh_cipherlist);
     write_setting_i(sesskey, "AuthTIS", cfg->try_tis_auth);
     write_setting_i(sesskey, "AuthKI", cfg->try_ki_auth);
+    write_setting_i(sesskey, "SshNoShell", cfg->ssh_no_shell);
     write_setting_i(sesskey, "SshProt", cfg->sshprot);
     write_setting_i(sesskey, "SSH2DES", cfg->ssh2_des_cbc);
     write_setting_filename(sesskey, "PublicKeyFile", cfg->keyfile);
@@ -490,6 +491,7 @@ void load_open_settings(void *sesskey, int do_host, Config *cfg)
     gppi(sesskey, "SSH2DES", 0, &cfg->ssh2_des_cbc);
     gppi(sesskey, "AuthTIS", 0, &cfg->try_tis_auth);
     gppi(sesskey, "AuthKI", 1, &cfg->try_ki_auth);
+    gppi(sesskey, "SshNoShell", 0, &cfg->ssh_no_shell);
     gppfile(sesskey, "PublicKeyFile", &cfg->keyfile);
     gpps(sesskey, "RemoteCommand", "", cfg->remote_cmd,
         sizeof(cfg->remote_cmd));

diff --git a/ssh.c b/ssh.c
index e8d243133249603d065db425914b7fe787110808..8356a075b184cec79927f54a9437e9cb9cadb4bd 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -5612,43 +5612,47 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * point; there's no need to send SERVICE_REQUEST.
      */
 
+    ssh->channels = newtree234(ssh_channelcmp);
+
     /*
-     * So now create a channel with a session in it.
+     * Create the main session channel.
      */
-    ssh->channels = newtree234(ssh_channelcmp);
-    ssh->mainchan = snew(struct ssh_channel);
-    ssh->mainchan->ssh = ssh;
-    ssh->mainchan->localid = alloc_channel_id(ssh);
-    ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN);
-    ssh2_pkt_addstring(ssh, "session");
-    ssh2_pkt_adduint32(ssh, ssh->mainchan->localid);
-    ssh->mainchan->v.v2.locwindow = OUR_V2_WINSIZE;
-    ssh2_pkt_adduint32(ssh, ssh->mainchan->v.v2.locwindow);/* our window size */
-    ssh2_pkt_adduint32(ssh, 0x4000UL);      /* our max pkt size */
-    ssh2_pkt_send(ssh);
-    crWaitUntilV(ispkt);
-    if (ssh->pktin.type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
-       bombout(("Server refused to open a session"));
-       crStopV;
-       /* FIXME: error data comes back in FAILURE packet */
-    }
-    if (ssh_pkt_getuint32(ssh) != ssh->mainchan->localid) {
-       bombout(("Server's channel confirmation cited wrong channel"));
-       crStopV;
-    }
-    ssh->mainchan->remoteid = ssh_pkt_getuint32(ssh);
-    ssh->mainchan->type = CHAN_MAINSESSION;
-    ssh->mainchan->closes = 0;
-    ssh->mainchan->v.v2.remwindow = ssh_pkt_getuint32(ssh);
-    ssh->mainchan->v.v2.remmaxpkt = ssh_pkt_getuint32(ssh);
-    bufchain_init(&ssh->mainchan->v.v2.outbuffer);
-    add234(ssh->channels, ssh->mainchan);
-    logevent("Opened channel for session");
+    if (!ssh->cfg.ssh_no_shell) {
+       ssh->mainchan = snew(struct ssh_channel);
+       ssh->mainchan->ssh = ssh;
+       ssh->mainchan->localid = alloc_channel_id(ssh);
+       ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN);
+       ssh2_pkt_addstring(ssh, "session");
+       ssh2_pkt_adduint32(ssh, ssh->mainchan->localid);
+       ssh->mainchan->v.v2.locwindow = OUR_V2_WINSIZE;
+       ssh2_pkt_adduint32(ssh, ssh->mainchan->v.v2.locwindow);/* our window size */
+       ssh2_pkt_adduint32(ssh, 0x4000UL);      /* our max pkt size */
+       ssh2_pkt_send(ssh);
+       crWaitUntilV(ispkt);
+       if (ssh->pktin.type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
+           bombout(("Server refused to open a session"));
+           crStopV;
+           /* FIXME: error data comes back in FAILURE packet */
+       }
+       if (ssh_pkt_getuint32(ssh) != ssh->mainchan->localid) {
+           bombout(("Server's channel confirmation cited wrong channel"));
+           crStopV;
+       }
+       ssh->mainchan->remoteid = ssh_pkt_getuint32(ssh);
+       ssh->mainchan->type = CHAN_MAINSESSION;
+       ssh->mainchan->closes = 0;
+       ssh->mainchan->v.v2.remwindow = ssh_pkt_getuint32(ssh);
+       ssh->mainchan->v.v2.remmaxpkt = ssh_pkt_getuint32(ssh);
+       bufchain_init(&ssh->mainchan->v.v2.outbuffer);
+       add234(ssh->channels, ssh->mainchan);
+       logevent("Opened channel for session");
+    } else
+       ssh->mainchan = NULL;
 
     /*
      * Potentially enable X11 forwarding.
      */
-    if (ssh->cfg.x11_forward) {
+    if (ssh->mainchan && ssh->cfg.x11_forward) {
        char proto[20], data[64];
        logevent("Requesting X11 forwarding");
        ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
@@ -5861,7 +5865,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Potentially enable agent forwarding.
      */
-    if (ssh->cfg.agentfwd && agent_exists()) {
+    if (ssh->mainchan && ssh->cfg.agentfwd && agent_exists()) {
        logevent("Requesting OpenSSH-style agent forwarding");
        ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
        ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
@@ -5897,7 +5901,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Now allocate a pty for the session.
      */
-    if (!ssh->cfg.nopty) {
+    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 */
@@ -5954,7 +5958,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * this twice if the config data has provided a second choice
      * of command.
      */
-    while (1) {
+    if (ssh->mainchan) while (1) {
        int subsys;
        char *cmd;
 
@@ -6028,7 +6032,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      */
     if (ssh->ldisc)
        ldisc_send(ssh->ldisc, NULL, 0, 0);/* cause ldisc to notice changes */
-    ssh->send_ok = 1;
+    if (ssh->mainchan)
+       ssh->send_ok = 1;
     while (1) {
        crReturnV;
        s->try_send = FALSE;
@@ -6171,8 +6176,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
                /*
                 * See if that was the last channel left open.
+                * (This is only our termination condition if we're
+                * not running in -N mode.)
                 */
-               if (count234(ssh->channels) == 0) {
+               if (!ssh->cfg.ssh_no_shell && count234(ssh->channels) == 0) {
                    logevent("All channels closed. Disconnecting");
 #if 0
                     /*
@@ -6452,7 +6459,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                bombout(("Strange packet received: type %d", ssh->pktin.type));
                crStopV;
            }
-       } else {
+       } else if (ssh->mainchan) {
            /*
             * We have spare data. Add it to the channel buffer.
             */
@@ -6772,7 +6779,7 @@ static void ssh_size(void *handle, int width, int height)
                            PKT_INT, ssh->term_height,
                            PKT_INT, ssh->term_width,
                            PKT_INT, 0, PKT_INT, 0, PKT_END);
-           } else {
+           } else if (ssh->mainchan) {
                ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
                ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
                ssh2_pkt_addstring(ssh, "window-change");
@@ -6834,7 +6841,7 @@ static void ssh_special(void *handle, Telnet_Special code)
        }
        if (ssh->version == 1) {
            send_packet(ssh, SSH1_CMSG_EOF, PKT_END);
-       } else {
+       } else if (ssh->mainchan) {
            ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_EOF);
            ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
            ssh2_pkt_send(ssh);
@@ -6856,7 +6863,7 @@ static void ssh_special(void *handle, Telnet_Special code)
            || ssh->state == SSH_STATE_PREPACKET) return;
        if (ssh->version == 1) {
            logevent("Unable to send BREAK signal in SSH1");
-       } else {
+       } else if (ssh->mainchan) {
            ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
            ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
            ssh2_pkt_addstring(ssh, "break");

diff --git a/winhelp.h b/winhelp.h
index 6b7ca242cd07ff06925f09b2350ebddea636b1ca..508c0e5431243b3e103d8c691f36ccb82ee299de 100644 (file)
--- a/winhelp.h
+++ b/winhelp.h
@@ -80,6 +80,7 @@
 #define WINHELP_CTX_telnet_newline "telnet.newline"
 #define WINHELP_CTX_rlogin_localuser "rlogin.localuser"
 #define WINHELP_CTX_ssh_nopty "ssh.nopty"
+#define WINHELP_CTX_ssh_noshell "ssh.noshell"
 #define WINHELP_CTX_ssh_ciphers "ssh.ciphers"
 #define WINHELP_CTX_ssh_protocol "ssh.protocol"
 #define WINHELP_CTX_ssh_command "ssh.command"