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

diff --git a/cmdline.c b/cmdline.c
index 29456a1..82cd4f8 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 cbf3169..8588b23 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 4b4271b..92b479b 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 806acfd..efc560d 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 575603d..cda9b3b 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 780b4eb..827f449 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 679fab1..b0f223e 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 e8d2431..8356a07 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 6b7ca24..508c0e5 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"