Fixes (mostly from Colin Watson, a couple redone by me) to make Unix
[u/mdw/putty] / ssh.c
diff --git a/ssh.c b/ssh.c
index 2deaa7b..c3c3f11 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -13,6 +13,7 @@
 #include "tree234.h"
 #include "ssh.h"
 #ifndef NO_GSSAPI
+#include "sshgssc.h"
 #include "sshgss.h"
 #endif
 
@@ -194,6 +195,7 @@ static const char *const ssh2_disconnect_reasons[] = {
 #define BUG_SSH2_REKEY                           64
 #define BUG_SSH2_PK_SESSIONID                   128
 #define BUG_SSH2_MAXPKT                                256
+#define BUG_CHOKES_ON_SSH2_IGNORE               512
 
 /*
  * Codes for terminal modes.
@@ -542,7 +544,7 @@ 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
@@ -588,6 +590,17 @@ struct ssh_channel {
      * A channel is completely finished with when all four bits are set.
      */
     int closes;
+
+    /*
+     * This flag indicates that a close 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 close the channel until we've finished sending
+     * the data, so we set this flag instead to remind us to
+     * initiate the closing process once our buffer is clear.
+     */
+    int pending_close;
+
     /*
      * True if this channel is causing the underlying connection to be
      * throttled.
@@ -928,6 +941,13 @@ struct ssh_tag {
      * 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)
@@ -2011,7 +2031,8 @@ 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.
@@ -2141,7 +2162,8 @@ static void ssh2_pkt_send_with_padding(Ssh ssh, struct Packet *pkt,
         * unavailable, we don't do this trick at all, because we
         * gain nothing by it.)
         */
-       if (ssh->cscipher) {
+       if (ssh->cscipher &&
+           !(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) {
            int stringlen, i;
 
            stringlen = (256 - ssh->deferred_len);
@@ -2508,6 +2530,15 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        ssh->remote_bugs |= BUG_SSH2_MAXPKT;
        logevent("We believe remote version ignores SSH-2 maximum packet size");
     }
+
+    if (ssh->cfg.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");
+    }
 }
 
 /*
@@ -2831,6 +2862,7 @@ static int ssh_do_close(Ssh ssh, int notify_exit)
                x11_close(c->u.x11.s);
                break;
              case CHAN_SOCKDATA:
+             case CHAN_SOCKDATA_DORMANT:
                pfd_close(c->u.pfd.s);
                break;
            }
@@ -2853,6 +2885,8 @@ static int ssh_do_close(Ssh ssh, int notify_exit)
            del234(ssh->portfwds, pf); /* moving next one to index 0 */
            free_portfwd(pf);
        }
+       freetree234(ssh->portfwds);
+       ssh->portfwds = NULL;
     }
 
     return ret;
@@ -4138,7 +4172,7 @@ void sshfwd_close(struct ssh_channel *c)
     if (ssh->state == SSH_STATE_CLOSED)
        return;
 
-    if (c && !c->closes) {
+    if (!c->closes) {
        /*
         * If halfopen is true, we have sent
         * CHANNEL_OPEN for this channel, but it hasn't even been
@@ -4150,14 +4184,42 @@ void sshfwd_close(struct ssh_channel *c)
            if (ssh->version == 1) {
                send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
                            PKT_END);
+               c->closes = 1;                 /* sent MSG_CLOSE */
            } else {
-               struct Packet *pktout;
-               pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
-               ssh2_pkt_adduint32(pktout, c->remoteid);
-               ssh2_pkt_send(ssh, pktout);
+               int bytes_to_send = bufchain_size(&c->v.v2.outbuffer);
+               if (bytes_to_send > 0) {
+                   /*
+                    * If we still have unsent data in our outgoing
+                    * buffer for this channel, we can't actually
+                    * initiate a close operation yet or that data
+                    * will be lost. Instead, set the pending_close
+                    * flag so that when we do clear the buffer
+                    * we'll start closing the channel.
+                    */
+                   char logmsg[160] = {'\0'};
+                   sprintf(
+                           logmsg,
+                           "Forwarded port pending to be closed : "
+                           "%d bytes remaining",
+                           bytes_to_send);
+                   logevent(logmsg);
+
+                   c->pending_close = TRUE;
+               } else {
+                   /*
+                    * No locally buffered data, so we can send the
+                    * close message immediately.
+                    */
+                   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 */
+                   logevent("Nothing left to send, closing channel");
+               }
            }
        }
-       c->closes = 1;                 /* sent MSG_CLOSE */
+
        if (c->type == CHAN_X11) {
            c->u.x11.s = NULL;
            logevent("Forwarded X11 connection terminated");
@@ -4296,6 +4358,7 @@ 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);
     }
 }
@@ -4427,12 +4490,19 @@ 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;
@@ -4465,6 +4535,8 @@ 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;
@@ -4674,6 +4746,7 @@ static void ssh1_smsg_x11_open(Ssh ssh, struct Packet *pktin)
            c->halfopen = FALSE;
            c->localid = alloc_channel_id(ssh);
            c->closes = 0;
+           c->pending_close = FALSE;
            c->throttling_conn = 0;
            c->type = CHAN_X11; /* identify channel type */
            add234(ssh->channels, c);
@@ -4703,6 +4776,7 @@ static void ssh1_smsg_agent_open(Ssh ssh, struct Packet *pktin)
        c->halfopen = FALSE;
        c->localid = alloc_channel_id(ssh);
        c->closes = 0;
+       c->pending_close = FALSE;
        c->throttling_conn = 0;
        c->type = CHAN_AGENT;   /* identify channel type */
        c->u.a.lensofar = 0;
@@ -4757,6 +4831,7 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
            c->halfopen = FALSE;
            c->localid = alloc_channel_id(ssh);
            c->closes = 0;
+           c->pending_close = FALSE;
            c->throttling_conn = 0;
            c->type = CHAN_SOCKDATA;    /* identify channel type */
            add234(ssh->channels, c);
@@ -4996,10 +5071,10 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
        }
     }
 
-    if (ssh->cfg.x11_forward) {
+    if (ssh->cfg.x11_forward &&
+       (ssh->x11disp = x11_setup_display(ssh->cfg.x11_display,
+                                         ssh->cfg.x11_auth, &ssh->cfg))) {
        logevent("Requesting X11 forwarding");
-       ssh->x11disp = x11_setup_display(ssh->cfg.x11_display,
-                                        ssh->cfg.x11_auth, &ssh->cfg);
        /*
         * 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,
@@ -5347,6 +5422,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
        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;
@@ -5362,6 +5439,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
     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.
@@ -5526,26 +5605,32 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
            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) {
+       /* 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);
            }
-       }
-       /* 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) {
-               ssh2_pkt_addstring_str(s->pktout, ",");
-               ssh2_pkt_addstring_str(s->pktout, c->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. */
@@ -5694,6 +5779,13 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
            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 */
@@ -5703,8 +5795,19 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
            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;
@@ -6240,19 +6343,52 @@ 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 (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,
@@ -6270,7 +6406,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                     schedule_timer(ssh->cfg.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);
         }
@@ -6323,7 +6459,7 @@ static int ssh2_try_send(struct ssh_channel *c)
     return bufchain_size(&c->v.v2.outbuffer);
 }
 
-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)
@@ -6347,6 +6483,19 @@ static void ssh2_try_send_and_unthrottle(struct ssh_channel *c)
            break;
        }
     }
+
+    /*
+     * If we've emptied the channel's output buffer and there's a
+     * pending close event, start the channel-closing procedure.
+     */
+    if (c->pending_close && bufchain_size(&c->v.v2.outbuffer) == 0) {
+       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;
+       c->pending_close = FALSE;
+    }
 }
 
 /*
@@ -6357,6 +6506,7 @@ static void ssh2_channel_init(struct ssh_channel *c)
     Ssh ssh = c->ssh;
     c->localid = alloc_channel_id(ssh);
     c->closes = 0;
+    c->pending_close = FALSE;
     c->throttling_conn = FALSE;
     c->v.v2.locwindow = c->v.v2.locmaxwin = c->v.v2.remlocwin =
        ssh->cfg.ssh_simple ? OUR_V2_BIGWIN : OUR_V2_WINSIZE;
@@ -6540,7 +6690,7 @@ static void ssh2_msg_channel_window_adjust(Ssh ssh, struct Packet *pktin)
        return;
     if (!c->closes) {
        c->v.v2.remwindow += ssh_pkt_getuint32(pktin);
-       ssh2_try_send_and_unthrottle(c);
+       ssh2_try_send_and_unthrottle(ssh, c);
     }
 }
 
@@ -6661,11 +6811,13 @@ static void ssh2_msg_channel_eof(Ssh ssh, struct Packet *pktin)
         * wrap up and close the channel ourselves.
         */
        x11_close(c->u.x11.s);
+       c->u.x11.s = NULL;
        sshfwd_close(c);
     } else if (c->type == CHAN_AGENT) {
        sshfwd_close(c);
     } else if (c->type == CHAN_SOCKDATA) {
        pfd_close(c->u.pfd.s);
+       c->u.pfd.s = NULL;
        sshfwd_close(c);
     }
 }
@@ -7013,6 +7165,7 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
 
     if (typelen == 3 && !memcmp(type, "x11", 3)) {
        char *addrstr;
+       const char *x11err;
 
        ssh_pkt_getstring(pktin, &peeraddr, &peeraddrlen);
        addrstr = snewn(peeraddrlen+1, char);
@@ -7025,8 +7178,9 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
 
        if (!ssh->X11_fwd_enabled)
            error = "X11 forwarding is not enabled";
-       else if (x11_init(&c->u.x11.s, ssh->x11disp, c,
-                         addrstr, peerport, &ssh->cfg) != NULL) {
+       else if ((x11err = x11_init(&c->u.x11.s, ssh->x11disp, c,
+                                   addrstr, peerport, &ssh->cfg)) != NULL) {
+           logeventf(ssh, "Local X11 connection failed: %s", x11err);
            error = "Unable to open an X11 connection";
        } else {
            logevent("Opening X11 forward connection succeeded");
@@ -7102,12 +7256,14 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
 }
 
 /*
- * 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 (ssh->cfg.ssh_show_banner &&
+       bufchain_size(&ssh->banner) <= 131072) {
        char *banner = NULL;
        int size = 0;
        ssh_pkt_getstring(pktin, &banner, &size);
@@ -7161,7 +7317,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        int tried_gssapi;
 #endif
        int kbd_inter_refused;
-       int we_are_in;
+       int we_are_in, userauth_success;
        prompts_t *cur_prompt;
        int num_prompts;
        char username[100];
@@ -7184,6 +7340,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        int num_env, env_left, env_ok;
        struct Packet *pktout;
 #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;
@@ -7196,7 +7353,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     crBegin(ssh->do_ssh2_authconn_crstate);
 
     s->done_service_req = FALSE;
-    s->we_are_in = FALSE;
+    s->we_are_in = s->userauth_success = FALSE;
 #ifndef NO_GSSAPI
     s->tried_gssapi = FALSE;
 #endif
@@ -7452,6 +7609,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        }
 
        while (1) {
+           char *methods = NULL;
+           int methlen = 0;
+
            /*
             * Wait for the result of the last authentication request.
             */
@@ -7483,7 +7643,7 @@ 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;
            }
 
@@ -7501,8 +7661,6 @@ 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);
                if (!ssh2_pkt_getbool(pktin)) {
                    /*
@@ -7558,10 +7716,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                    in_commasep_string("password", methods, methlen);
                s->can_keyb_inter = ssh->cfg.try_ki_auth &&
                    in_commasep_string("keyboard-interactive", methods, methlen);
-#ifndef NO_GSSAPI              
+#ifndef NO_GSSAPI
+               if (!ssh->gsslibs)
+                   ssh->gsslibs = ssh_gss_setup(&ssh->cfg);
                s->can_gssapi = ssh->cfg.try_gssapi_auth &&
-                 in_commasep_string("gssapi-with-mic", methods, methlen) &&
-                 ssh_gss_init();
+                   in_commasep_string("gssapi-with-mic", methods, methlen) &&
+                   ssh->gsslibs->nlibraries > 0;
 #endif
            }
 
@@ -7904,6 +8064,35 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                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 = ssh->cfg.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, s->username);
@@ -7911,7 +8100,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                ssh2_pkt_addstring(s->pktout, "gssapi-with-mic");
 
                /* add mechanism info */
-               ssh_gss_indicate_mech(&s->gss_buf);
+               s->gsslib->indicate_mech(s->gsslib, &s->gss_buf);
 
                /* number of GSSAPI mechanisms */
                ssh2_pkt_adduint32(s->pktout,1);
@@ -7947,8 +8136,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                }
 
                /* now start running */
-               s->gss_stat = ssh_gss_import_name(ssh->fullhostname,
-                                                 &s->gss_srv_name);
+               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");
@@ -7958,11 +8148,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                }
 
                /* fetch TGT into GSS engine */
-               s->gss_stat = ssh_gss_acquire_cred(&s->gss_ctx);
+               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");
-                   ssh_gss_release_name(&s->gss_srv_name);
+                   s->gsslib->release_name(s->gsslib, &s->gss_srv_name);
                    continue;
                }
 
@@ -7972,17 +8162,20 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 
                /* now enter the loop */
                do {
-                   s->gss_stat = ssh_gss_init_sec_context(&s->gss_ctx,
-                                                          s->gss_srv_name,
-                                                          ssh->cfg.gssapifwd,
-                                                          &s->gss_rcvtok,
-                                                          &s->gss_sndtok);
+                   s->gss_stat = s->gsslib->init_sec_context
+                       (s->gsslib,
+                        &s->gss_ctx,
+                        s->gss_srv_name,
+                        ssh->cfg.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 (ssh_gss_display_status(s->gss_ctx,&s->gss_buf) == SSH_GSS_OK) {
+                       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);
                        }
@@ -7999,7 +8192,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                        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);
-                       ssh_gss_free_tok(&s->gss_sndtok);
+                       s->gsslib->free_tok(s->gsslib, &s->gss_sndtok);
                    }
 
                    if (s->gss_stat == SSH_GSS_S_CONTINUE_NEEDED) {
@@ -8016,8 +8209,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                } while (s-> gss_stat == SSH_GSS_S_CONTINUE_NEEDED);
 
                if (s->gss_stat != SSH_GSS_OK) {
-                   ssh_gss_release_name(&s->gss_srv_name);
-                   ssh_gss_release_cred(&s->gss_ctx);
+                   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");
@@ -8036,17 +8229,17 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                s->gss_buf.value = (char *)s->pktout->data + micoffset;
                s->gss_buf.length = s->pktout->length - micoffset;
 
-               ssh_gss_get_mic(s->gss_ctx, &s->gss_buf, &mic);
+               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);
-               ssh_gss_free_mic(&mic);
+               s->gsslib->free_mic(s->gsslib, &mic);
 
                s->gotit = FALSE;
 
-               ssh_gss_release_name(&s->gss_srv_name);
-               ssh_gss_release_cred(&s->gss_ctx);
+               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) {
@@ -8101,23 +8294,6 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                    ssh_pkt_getstring(pktin, &lang, &lang_len);
                    s->cur_prompt = new_prompts(ssh->frontend);
                    s->cur_prompt->to_server = TRUE;
-                   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;
-                   }
-                   /* FIXME: ugly to print "Using..." in prompt _every_
-                    * time round. Can this be done more subtly? */
-                   s->cur_prompt->instruction =
-                       dupprintf("Using keyboard-interactive authentication.%s%.*s",
-                                 inst_len ? "\n" : "", inst_len, inst);
-                   s->cur_prompt->instr_reqd = TRUE;
 
                    /*
                     * Get any prompt(s) from the packet.
@@ -8141,6 +8317,33 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                                   echo, SSH_MAX_PASSWORD_LEN);
                    }
 
+                   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).
@@ -8422,11 +8625,16 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                sfree(s->password);
 
            } else {
+               char *str = dupprintf("No supported authentication methods available"
+                                     " (server sent: %.*s)",
+                                     methlen, methods);
 
-               ssh_disconnect(ssh, NULL,
+               ssh_disconnect(ssh, str,
                               "No supported authentication methods available",
                               SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE,
                               FALSE);
+               sfree(str);
+
                crStopV;
 
            }
@@ -8443,6 +8651,20 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     if (s->agent_response)
        sfree(s->agent_response);
 
+    if (s->userauth_success) {
+       /*
+        * 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);
+    }
+
     /*
      * Now the connection protocol has started, one way or another.
      */
@@ -8558,7 +8780,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] =
        ssh2_msg_channel_open;
 
-    if (ssh->cfg.ssh_simple) {
+    if (ssh->mainchan && ssh->cfg.ssh_simple) {
        /*
         * This message indicates to the server that we promise
         * not to try to run any other channel in parallel with
@@ -8575,10 +8797,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Potentially enable X11 forwarding.
      */
-    if (ssh->mainchan && !ssh->ncmode && ssh->cfg.x11_forward) {
+    if (ssh->mainchan && !ssh->ncmode && ssh->cfg.x11_forward &&
+       (ssh->x11disp = x11_setup_display(ssh->cfg.x11_display,
+                                         ssh->cfg.x11_auth, &ssh->cfg))) {
        logevent("Requesting X11 forwarding");
-       ssh->x11disp = x11_setup_display(ssh->cfg.x11_display,
-                                        ssh->cfg.x11_auth, &ssh->cfg);
        s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
        ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
        ssh2_pkt_addstring(s->pktout, "x11-req");
@@ -8865,7 +9087,7 @@ 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);
+               ssh2_try_send_and_unthrottle(ssh, c);
        }
     }
 
@@ -8909,10 +9131,9 @@ 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);
@@ -9147,6 +9368,10 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->max_data_size = parse_blocksize(ssh->cfg.ssh_rekey_data);
     ssh->kex_in_progress = FALSE;
 
+#ifndef NO_GSSAPI
+    ssh->gsslibs = NULL;
+#endif
+
     p = connect_to_host(ssh, host, port, realhost, nodelay, keepalive);
     if (p != NULL)
        return p;
@@ -9207,6 +9432,7 @@ static void ssh_free(void *handle)
                    x11_close(c->u.x11.s);
                break;
              case CHAN_SOCKDATA:
+             case CHAN_SOCKDATA_DORMANT:
                if (c->u.pfd.s != NULL)
                    pfd_close(c->u.pfd.s);
                break;
@@ -9219,7 +9445,7 @@ static void ssh_free(void *handle)
 
     if (ssh->rportfwds) {
        while ((pf = delpos234(ssh->rportfwds, 0)) != NULL)
-           sfree(pf);
+           free_rportfwd(pf);
        freetree234(ssh->rportfwds);
        ssh->rportfwds = NULL;
     }
@@ -9243,6 +9469,10 @@ static void ssh_free(void *handle)
     if (ssh->pinger)
        pinger_free(ssh->pinger);
     bufchain_clear(&ssh->queued_incoming_data);
+#ifndef NO_GSSAPI
+    if (ssh->gsslibs)
+       ssh_gss_cleanup(ssh->gsslibs);
+#endif
     sfree(ssh);
 
     random_unref();
@@ -9403,8 +9633,10 @@ 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[] = {
@@ -9429,7 +9661,8 @@ 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;
@@ -9448,7 +9681,10 @@ 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))
+           ADD_SPECIALS(ssh2_rekey_special);
        if (ssh->mainchan)
            ADD_SPECIALS(ssh2_session_specials);
     } /* else we're not ready yet */
@@ -9498,9 +9734,11 @@ 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) {