Joe Yates's memory leak patches.
[u/mdw/putty] / ssh.c
diff --git a/ssh.c b/ssh.c
index 76dc2ec..1d88723 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -269,11 +269,30 @@ static char *ssh2_pkt_type(int pkt_ctx, int type)
 
 enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM };
 
-/* Coroutine mechanics for the sillier bits of the code */
+/*
+ * Coroutine mechanics for the sillier bits of the code. If these
+ * macros look impenetrable to you, you might find it helpful to
+ * read
+ * 
+ *   http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
+ * 
+ * which explains the theory behind these macros.
+ * 
+ * In particular, if you are getting `case expression not constant'
+ * errors when building with MS Visual Studio, this is because MS's
+ * Edit and Continue debugging feature causes their compiler to
+ * violate ANSI C. To disable Edit and Continue debugging:
+ * 
+ *  - right-click ssh.c in the FileView
+ *  - click Settings
+ *  - select the C/C++ tab and the General category
+ *  - under `Debug info:', select anything _other_ than `Program
+ *    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 = smalloc(sizeof(struct t)); \
+    if (!ssh->t) ssh->t = snew(struct t); \
     s = ssh->t;
 #define crFinish(z)    } *crLine = 0; return (z); }
 #define crFinishV      } *crLine = 0; return; }
@@ -303,6 +322,8 @@ static unsigned char *ssh2_mpint_fmt(Bignum b, int *len);
 static void ssh2_pkt_addmp(Ssh, Bignum b);
 static int ssh2_pkt_construct(Ssh);
 static void ssh2_pkt_send(Ssh);
+static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt);
+static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt);
 
 /*
  * Buffer management constants. There are several of these for
@@ -496,6 +517,7 @@ 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 int ssh_sendbuffer(void *handle);
+static void ssh_do_close(Ssh ssh);
 
 struct rdpkt1_state_tag {
     long len, pad, biglen, to_read;
@@ -629,12 +651,18 @@ struct ssh_tag {
      * potentially reconfigure port forwardings etc in mid-session.
      */
     Config cfg;
+
+    /*
+     * Used to transfer data back from async agent callbacks.
+     */
+    void *agent_response;
+    int agent_response_len;
 };
 
 #define logevent(s) logevent(ssh->frontend, s)
 
 /* logevent, only printf-formatted. */
-static void logeventf(Ssh ssh, char *fmt, ...)
+static void logeventf(Ssh ssh, const char *fmt, ...)
 {
     va_list ap;
     char *buf;
@@ -646,9 +674,14 @@ static void logeventf(Ssh ssh, char *fmt, ...)
     sfree(buf);
 }
 
-#define bombout(msg) ( ssh->state = SSH_STATE_CLOSED, \
-                          (ssh->s ? sk_close(ssh->s), ssh->s = NULL : 0), \
-                          logeventf msg, connection_fatal msg )
+#define bombout(msg) \
+    do { \
+        char *text = dupprintf msg; \
+       ssh_do_close(ssh); \
+        logevent(text); \
+        connection_fatal(ssh->frontend, "%s", text); \
+        sfree(text); \
+    } while (0)
 
 static int ssh_channelcmp(void *av, void *bv)
 {
@@ -795,7 +828,8 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 
     if (ssh->pktin.maxlen < st->biglen) {
        ssh->pktin.maxlen = st->biglen;
-       ssh->pktin.data = srealloc(ssh->pktin.data, st->biglen + APIEXTRA);
+       ssh->pktin.data = sresize(ssh->pktin.data, st->biglen + APIEXTRA,
+                                 unsigned char);
     }
 
     st->to_read = st->biglen;
@@ -815,18 +849,18 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 
     if (ssh->cipher && detect_attack(ssh->crcda_ctx, ssh->pktin.data,
                                     st->biglen, NULL)) {
-        bombout((ssh,"Network attack (CRC compensation) detected!"));
-        crReturn(0);
+        bombout(("Network attack (CRC compensation) detected!"));
+        crStop(0);
     }
 
     if (ssh->cipher)
        ssh->cipher->decrypt(ssh->v1_cipher_ctx, ssh->pktin.data, st->biglen);
 
-    st->realcrc = crc32(ssh->pktin.data, st->biglen - 4);
+    st->realcrc = crc32_compute(ssh->pktin.data, st->biglen - 4);
     st->gotcrc = GET_32BIT(ssh->pktin.data + st->biglen - 4);
     if (st->gotcrc != st->realcrc) {
-       bombout((ssh,"Incorrect CRC received on packet"));
-       crReturn(0);
+       bombout(("Incorrect CRC received on packet"));
+       crStop(0);
     }
 
     ssh->pktin.body = ssh->pktin.data + st->pad + 1;
@@ -834,14 +868,18 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     if (ssh->v1_compressing) {
        unsigned char *decompblk;
        int decomplen;
-       zlib_decompress_block(ssh->sc_comp_ctx,
-                             ssh->pktin.body - 1, ssh->pktin.length + 1,
-                             &decompblk, &decomplen);
+       if (!zlib_decompress_block(ssh->sc_comp_ctx,
+                                  ssh->pktin.body - 1, ssh->pktin.length + 1,
+                                  &decompblk, &decomplen)) {
+           bombout(("Zlib decompression encountered invalid data"));
+           crStop(0);
+       }
 
        if (ssh->pktin.maxlen < st->pad + decomplen) {
            ssh->pktin.maxlen = st->pad + decomplen;
-           ssh->pktin.data = srealloc(ssh->pktin.data,
-                                      ssh->pktin.maxlen + APIEXTRA);
+           ssh->pktin.data = sresize(ssh->pktin.data,
+                                     ssh->pktin.maxlen + APIEXTRA,
+                                     unsigned char);
            ssh->pktin.body = ssh->pktin.data + st->pad + 1;
        }
 
@@ -865,8 +903,8 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
        ssh->pktin.type == SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
        long stringlen = GET_32BIT(ssh->pktin.body);
        if (stringlen + 4 != ssh->pktin.length) {
-           bombout((ssh,"Received data packet with bogus string length"));
-           crReturn(0);
+           bombout(("Received data packet with bogus string length"));
+           crStop(0);
        }
     }
 
@@ -898,8 +936,8 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
        memcpy(buf + nowlen, ssh->pktin.body + 4, msglen);
        buf[nowlen + msglen] = '\0';
        /* logevent(buf); (this is now done within the bombout macro) */
-       bombout((ssh,"Server sent disconnect message:\n\"%s\"", buf+nowlen));
-       crReturn(0);
+       bombout(("Server sent disconnect message:\n\"%s\"", buf+nowlen));
+       crStop(0);
     }
 
     crFinish(0);
@@ -923,7 +961,8 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 
     if (ssh->pktin.maxlen < st->cipherblk) {
        ssh->pktin.maxlen = st->cipherblk;
-       ssh->pktin.data = srealloc(ssh->pktin.data, st->cipherblk + APIEXTRA);
+       ssh->pktin.data = sresize(ssh->pktin.data, st->cipherblk + APIEXTRA,
+                                 unsigned char);
     }
 
     /*
@@ -952,8 +991,8 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      * do us any more damage.
      */
     if (st->len < 0 || st->pad < 0 || st->len + st->pad < 0) {
-       bombout((ssh,"Incoming packet was garbled on decryption"));
-       crReturn(0);
+       bombout(("Incoming packet was garbled on decryption"));
+       crStop(0);
     }
 
     /*
@@ -974,8 +1013,9 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      */
     if (ssh->pktin.maxlen < st->packetlen + st->maclen) {
        ssh->pktin.maxlen = st->packetlen + st->maclen;
-       ssh->pktin.data = srealloc(ssh->pktin.data,
-                                  ssh->pktin.maxlen + APIEXTRA);
+       ssh->pktin.data = sresize(ssh->pktin.data,
+                                 ssh->pktin.maxlen + APIEXTRA,
+                                 unsigned char);
     }
 
     /*
@@ -1000,8 +1040,8 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     if (ssh->scmac
        && !ssh->scmac->verify(ssh->sc_mac_ctx, ssh->pktin.data, st->len + 4,
                               st->incoming_sequence)) {
-       bombout((ssh,"Incorrect MAC received on packet"));
-       crReturn(0);
+       bombout(("Incorrect MAC received on packet"));
+       crStop(0);
     }
     st->incoming_sequence++;          /* whether or not we MACed */
 
@@ -1017,8 +1057,9 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
                                    &newpayload, &newlen)) {
            if (ssh->pktin.maxlen < newlen + 5) {
                ssh->pktin.maxlen = newlen + 5;
-               ssh->pktin.data = srealloc(ssh->pktin.data,
-                                          ssh->pktin.maxlen + APIEXTRA);
+               ssh->pktin.data = sresize(ssh->pktin.data,
+                                         ssh->pktin.maxlen + APIEXTRA,
+                                         unsigned char);
            }
            ssh->pktin.length = 5 + newlen;
            memcpy(ssh->pktin.data + 5, newpayload, newlen);
@@ -1058,13 +1099,13 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
             buf = dupprintf("Disconnection message text: %n%.*s",
                            &nowlen, msglen, ssh->pktin.data + 14);
             logevent(buf);
-            bombout((ssh,"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));
            sfree(buf);
-            crReturn(0);
+            crStop(0);
         }
         break;
       case SSH2_MSG_IGNORE:
@@ -1151,9 +1192,11 @@ static void ssh1_pktout_size(Ssh ssh, int len)
 #ifdef MSCRYPTOAPI
        /* Allocate enough buffer space for extra block
         * for MS CryptEncrypt() */
-       ssh->pktout.data = srealloc(ssh->pktout.data, biglen + 12);
+       ssh->pktout.data = sresize(ssh->pktout.data, biglen + 12,
+                                  unsigned char);
 #else
-       ssh->pktout.data = srealloc(ssh->pktout.data, biglen + 4);
+       ssh->pktout.data = sresize(ssh->pktout.data, biglen + 4,
+                                  unsigned char);
 #endif
     }
     ssh->pktout.body = ssh->pktout.data + 4 + pad + 1;
@@ -1167,8 +1210,18 @@ static void s_wrpkt_start(Ssh ssh, int type, int len)
 
 static int s_wrpkt_prepare(Ssh ssh)
 {
-    int pad, len, biglen, i;
+    int pad, biglen, i;
     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;
 
     ssh->pktout.body[-1] = ssh->pktout.type;
 
@@ -1194,7 +1247,7 @@ static int s_wrpkt_prepare(Ssh ssh)
 
     for (i = 0; i < pad; i++)
        ssh->pktout.data[i + 4] = random_byte();
-    crc = crc32(ssh->pktout.data + 4, biglen - 4);
+    crc = crc32_compute(ssh->pktout.data + 4, biglen - 4);
     PUT_32BIT(ssh->pktout.data + biglen, crc);
     PUT_32BIT(ssh->pktout.data, len);
 
@@ -1219,8 +1272,9 @@ static void s_wrpkt_defer(Ssh ssh)
     len = s_wrpkt_prepare(ssh);
     if (ssh->deferred_len + len > ssh->deferred_size) {
        ssh->deferred_size = ssh->deferred_len + len + 128;
-       ssh->deferred_send_data = srealloc(ssh->deferred_send_data,
-                                          ssh->deferred_size);
+       ssh->deferred_send_data = sresize(ssh->deferred_send_data,
+                                         ssh->deferred_size,
+                                         unsigned char);
     }
     memcpy(ssh->deferred_send_data + ssh->deferred_len, ssh->pktout.data, len);
     ssh->deferred_len += len;
@@ -1367,8 +1421,9 @@ static void ssh2_pkt_ensure(Ssh ssh, int length)
 {
     if (ssh->pktout.maxlen < length) {
        ssh->pktout.maxlen = length + 256;
-       ssh->pktout.data = srealloc(ssh->pktout.data,
-                                   ssh->pktout.maxlen + APIEXTRA);
+       ssh->pktout.data = sresize(ssh->pktout.data,
+                                  ssh->pktout.maxlen + APIEXTRA,
+                                  unsigned char);
        if (!ssh->pktout.data)
            fatalbox("Out of memory");
     }
@@ -1424,7 +1479,7 @@ static unsigned char *ssh2_mpint_fmt(Bignum b, int *len)
 {
     unsigned char *p;
     int i, n = (bignum_bitcount(b) + 7) / 8;
-    p = smalloc(n + 1);
+    p = snewn(n + 1, unsigned char);
     if (!p)
        fatalbox("out of memory");
     p[0] = 0;
@@ -1535,8 +1590,9 @@ static void ssh2_pkt_defer(Ssh ssh)
     int len = ssh2_pkt_construct(ssh);
     if (ssh->deferred_len + len > ssh->deferred_size) {
        ssh->deferred_size = ssh->deferred_len + len + 128;
-       ssh->deferred_send_data = srealloc(ssh->deferred_send_data,
-                                          ssh->deferred_size);
+       ssh->deferred_send_data = sresize(ssh->deferred_send_data,
+                                         ssh->deferred_size,
+                                         unsigned char);
     }
     memcpy(ssh->deferred_send_data + ssh->deferred_len, ssh->pktout.data, len);
     ssh->deferred_len += len;
@@ -1629,7 +1685,7 @@ static Bignum ssh2_pkt_getmp(Ssh ssh)
     if (!p)
        return NULL;
     if (p[0] & 0x80) {
-       bombout((ssh,"internal error: Can't handle negative mpints"));
+       bombout(("internal error: Can't handle negative mpints"));
        return NULL;
     }
     b = bignum_from_bytes((unsigned char *)p, length);
@@ -1724,7 +1780,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        (ssh->cfg.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")))) {
+         !strcmp(imp, "1.2.22") || !strcmp(imp, "Cisco-1.25") ||
+         !strcmp(imp, "OSU_1.4alpha3")))) {
        /*
         * These versions don't support SSH1_MSG_IGNORE, so we have
         * to use a different defence against password length
@@ -1736,7 +1793,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 
     if (ssh->cfg.sshbug_plainpw1 == FORCE_ON ||
        (ssh->cfg.sshbug_plainpw1 == AUTO &&
-        (!strcmp(imp, "Cisco-1.25")))) {
+        (!strcmp(imp, "Cisco-1.25") || !strcmp(imp, "OSU_1.4alpha3")))) {
        /*
         * These versions need a plain password sent; they can't
         * handle having a null and a random length of data after
@@ -1760,6 +1817,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 
     if (ssh->cfg.sshbug_hmac2 == FORCE_ON ||
        (ssh->cfg.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) ||
          wc_match("2.1 *", imp)))) {
@@ -1772,6 +1830,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 
     if (ssh->cfg.sshbug_derivekey2 == FORCE_ON ||
        (ssh->cfg.sshbug_derivekey2 == AUTO &&
+        !wc_match("* VShell", imp) &&
         (wc_match("2.0.0*", imp) || wc_match("2.0.10*", imp) ))) {
        /*
         * These versions have the key-derivation bug (failing to
@@ -1847,7 +1906,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     }
 
     s->vstrsize = 16;
-    s->vstring = smalloc(s->vstrsize);
+    s->vstring = snewn(s->vstrsize, char);
     strcpy(s->vstring, "SSH-");
     s->vslen = 4;
     s->i = 0;
@@ -1855,7 +1914,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
        crReturn(1);                   /* get another char */
        if (s->vslen >= s->vstrsize - 1) {
            s->vstrsize += 16;
-           s->vstring = srealloc(s->vstring, s->vstrsize);
+           s->vstring = sresize(s->vstring, s->vstrsize, char);
        }
        s->vstring[s->vslen++] = c;
        if (s->i >= 0) {
@@ -1875,7 +1934,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     s->vstring[strcspn(s->vstring, "\r\n")] = '\0';/* remove EOL chars */
     {
        char *vlog;
-       vlog = smalloc(20 + s->vslen);
+       vlog = snewn(20 + s->vslen, char);
        sprintf(vlog, "Server version: %s", s->vstring);
        logevent(vlog);
        sfree(vlog);
@@ -1892,12 +1951,12 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     s->proto2 = ssh_versioncmp(s->version, "1.99") >= 0;
 
     if (ssh->cfg.sshprot == 0 && !s->proto1) {
-       bombout((ssh,"SSH protocol version 1 required by user but not provided by server"));
-       crReturn(0);
+       bombout(("SSH protocol version 1 required by user but not provided by server"));
+       crStop(0);
     }
     if (ssh->cfg.sshprot == 3 && !s->proto2) {
-       bombout((ssh,"SSH protocol version 2 required by user but not provided by server"));
-       crReturn(0);
+       bombout(("SSH protocol version 2 required by user but not provided by server"));
+       crStop(0);
     }
 
     if (s->proto2 && (ssh->cfg.sshprot >= 2 || !s->proto1)) {
@@ -1938,6 +1997,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
        ssh->version = 1;
        ssh->s_rdpkt = ssh1_rdpkt;
     }
+    update_specials_menu(ssh->frontend);
     ssh->state = SSH_STATE_BEFORE_SIZE;
 
     sfree(s->vstring);
@@ -1991,19 +2051,47 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
     crFinishV;
 }
 
-static int ssh_closing(Plug plug, char *error_msg, int error_code,
-                      int calling_back)
+static void ssh_do_close(Ssh ssh)
 {
-    Ssh ssh = (Ssh) plug;
+    int i;
+    struct ssh_channel *c;
+
     ssh->state = SSH_STATE_CLOSED;
     if (ssh->s) {
         sk_close(ssh->s);
         ssh->s = NULL;
     }
+    /*
+     * Now we must shut down any port and X forwardings going
+     * through this connection.
+     */
+    if (ssh->channels) {
+       for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
+           switch (c->type) {
+             case CHAN_X11:
+               x11_close(c->u.x11.s);
+               break;
+             case CHAN_SOCKDATA:
+               pfd_close(c->u.pfd.s);
+               break;
+           }
+           del234(ssh->channels, c);
+           if (ssh->version == 2)
+               bufchain_clear(&c->v.v2.outbuffer);
+           sfree(c);
+       }
+    }
+}
+
+static int ssh_closing(Plug plug, const char *error_msg, int error_code,
+                      int calling_back)
+{
+    Ssh ssh = (Ssh) plug;
+    ssh_do_close(ssh);
     if (error_msg) {
        /* A socket error has occurred. */
        logevent(error_msg);
-       connection_fatal(ssh->frontend, error_msg);
+       connection_fatal(ssh->frontend, "%s", error_msg);
     } else {
        /* Otherwise, the remote side closed the connection normally. */
     }
@@ -2015,10 +2103,7 @@ static int ssh_receive(Plug plug, int urgent, char *data, int len)
     Ssh ssh = (Ssh) plug;
     ssh_gotdata(ssh, (unsigned char *)data, len);
     if (ssh->state == SSH_STATE_CLOSED) {
-       if (ssh->s) {
-           sk_close(ssh->s);
-           ssh->s = NULL;
-       }
+       ssh_do_close(ssh);
        return 0;
     }
     return 1;
@@ -2041,8 +2126,8 @@ static void ssh_sent(Plug plug, int bufsize)
  * Also places the canonical host name into `realhost'. It must be
  * freed by the caller.
  */
-static char *connect_to_host(Ssh ssh, char *host, int port,
-                            char **realhost, int nodelay)
+static const char *connect_to_host(Ssh ssh, char *host, int port,
+                                  char **realhost, int nodelay)
 {
     static const struct plug_function_table fn_table = {
        ssh_closing,
@@ -2052,9 +2137,9 @@ static char *connect_to_host(Ssh ssh, char *host, int port,
     };
 
     SockAddr addr;
-    char *err;
+    const char *err;
 
-    ssh->savedhost = smalloc(1 + strlen(host));
+    ssh->savedhost = snewn(1 + strlen(host), char);
     if (!ssh->savedhost)
        fatalbox("Out of memory");
     strcpy(ssh->savedhost, host);
@@ -2068,8 +2153,10 @@ static char *connect_to_host(Ssh ssh, char *host, int port,
      */
     logeventf(ssh, "Looking up host \"%s\"", host);
     addr = name_lookup(host, port, realhost, &ssh->cfg);
-    if ((err = sk_addr_error(addr)) != NULL)
+    if ((err = sk_addr_error(addr)) != NULL) {
+       sk_addr_free(addr);
        return err;
+    }
 
     /*
      * Open socket.
@@ -2134,7 +2221,7 @@ static void ssh_throttle_all(Ssh ssh, int enable, int bufsize)
            /* Agent channels require no buffer management. */
            break;
          case CHAN_SOCKDATA:
-           pfd_override_throttle(c->u.x11.s, enable);
+           pfd_override_throttle(c->u.pfd.s, enable);
            break;
        }
     }
@@ -2193,7 +2280,13 @@ static int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
            return -1;
            break;
          default:
-           if (((c >= ' ' && c <= '~') ||
+           /*
+            * 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;
@@ -2206,6 +2299,44 @@ static int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
     return 0;
 }
 
+static void ssh_agent_callback(void *sshv, void *reply, int replylen)
+{
+    Ssh ssh = (Ssh) sshv;
+
+    ssh->agent_response = reply;
+    ssh->agent_response_len = replylen;
+
+    if (ssh->version == 1)
+       do_ssh1_login(ssh, NULL, -1, 0);
+    else
+       do_ssh2_authconn(ssh, NULL, -1, 0);
+}
+
+static void ssh_agentf_callback(void *cv, void *reply, int replylen)
+{
+    struct ssh_channel *c = (struct ssh_channel *)cv;
+    Ssh ssh = c->ssh;
+    void *sentreply = reply;
+
+    if (!sentreply) {
+       /* Fake SSH_AGENT_FAILURE. */
+       sentreply = "\0\0\0\1\5";
+       replylen = 5;
+    }
+    if (ssh->version == 2) {
+       ssh2_add_channel_data(c, sentreply, replylen);
+       ssh2_try_send(c);
+    } else {
+       send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
+                   PKT_INT, c->remoteid,
+                   PKT_INT, replylen,
+                   PKT_DATA, sentreply, replylen,
+                   PKT_END);
+    }
+    if (reply)
+       sfree(reply);
+}
+
 /*
  * Handle the key exchange and user authentication phases.
  */
@@ -2248,8 +2379,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        crWaitUntil(ispkt);
 
     if (ssh->pktin.type != SSH1_SMSG_PUBLIC_KEY) {
-       bombout((ssh,"Public key packet not received"));
-       crReturn(0);
+       bombout(("Public key packet not received"));
+       crStop(0);
     }
 
     logevent("Received public keys");
@@ -2291,7 +2422,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     s->len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
 
-    s->rsabuf = smalloc(s->len);
+    s->rsabuf = snewn(s->len, unsigned char);
     if (!s->rsabuf)
        fatalbox("Out of memory");
 
@@ -2304,7 +2435,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
         */
        int len = rsastr_len(&hostkey);
        char fingerprint[100];
-       char *keystr = smalloc(len);
+       char *keystr = snewn(len, char);
        if (!keystr)
            fatalbox("Out of memory");
        rsastr_fmt(keystr, &hostkey);
@@ -2358,12 +2489,12 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        }
        if (!cipher_chosen) {
            if ((s->supported_ciphers_mask & (1 << SSH_CIPHER_3DES)) == 0)
-               bombout((ssh,"Server violates SSH 1 protocol by not "
+               bombout(("Server violates SSH 1 protocol by not "
                         "supporting 3DES encryption"));
            else
                /* shouldn't happen */
-               bombout((ssh,"No supported ciphers found"));
-           crReturn(0);
+               bombout(("No supported ciphers found"));
+           crStop(0);
        }
 
        /* Warn about chosen cipher if necessary. */
@@ -2404,11 +2535,27 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     ssh->crcda_ctx = crcda_make_context();
     logevent("Installing CRC compensation attack detector");
 
+    if (servkey.modulus) {
+       sfree(servkey.modulus);
+       servkey.modulus = NULL;
+    }
+    if (servkey.exponent) {
+       sfree(servkey.exponent);
+       servkey.exponent = NULL;
+    }
+    if (hostkey.modulus) {
+       sfree(hostkey.modulus);
+       hostkey.modulus = NULL;
+    }
+    if (hostkey.exponent) {
+       sfree(hostkey.exponent);
+       hostkey.exponent = NULL;
+    }
     crWaitUntil(ispkt);
 
     if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
-       bombout((ssh,"Encryption not successfully enabled"));
-       crReturn(0);
+       bombout(("Encryption not successfully enabled"));
+       crStop(0);
     }
 
     logevent("Successfully started encryption");
@@ -2424,8 +2571,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                     * Terminate.
                     */
                    logevent("No username provided. Abandoning session.");
-                   ssh->state = SSH_STATE_CLOSED;
-                   crReturn(1);
+                    ssh_closing((Plug)ssh, NULL, 0, 0);
+                   crStop(1);
                }
            } else {
                int ret;               /* need not be kept over crReturn */
@@ -2471,7 +2618,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /* 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))
+                           &s->publickey_blob, &s->publickey_bloblen, NULL))
            s->publickey_blob = NULL;
     } else
        s->publickey_blob = NULL;
@@ -2492,7 +2639,19 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            /* Request the keys held by the agent. */
            PUT_32BIT(s->request, 1);
            s->request[4] = SSH1_AGENTC_REQUEST_RSA_IDENTITIES;
-           agent_query(s->request, 5, &r, &s->responselen);
+           if (!agent_query(s->request, 5, &r, &s->responselen,
+                            ssh_agent_callback, ssh)) {
+               do {
+                   crReturn(0);
+                   if (ispkt) {
+                       bombout(("Unexpected data from server while waiting"
+                                " for agent response"));
+                       crStop(0);
+                   }
+               } while (ispkt || 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] == SSH1_AGENT_RSA_IDENTITIES_ANSWER) {
@@ -2542,7 +2701,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        len += ssh1_bignum_length(s->challenge);
                        len += 16;     /* session id */
                        len += 4;      /* response format */
-                       agentreq = smalloc(4 + len);
+                       agentreq = snewn(4 + len, char);
                        PUT_32BIT(agentreq, len);
                        q = agentreq + 4;
                        *q++ = SSH1_AGENTC_RSA_CHALLENGE;
@@ -2554,9 +2713,23 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        memcpy(q, s->session_id, 16);
                        q += 16;
                        PUT_32BIT(q, 1);        /* response format */
-                       agent_query(agentreq, len + 4, &vret, &retlen);
+                       if (!agent_query(agentreq, len + 4, &vret, &retlen,
+                                        ssh_agent_callback, ssh)) {
+                           sfree(agentreq);
+                           do {
+                               crReturn(0);
+                               if (ispkt) {
+                                   bombout(("Unexpected data from server"
+                                            " while waiting for agent"
+                                            " response"));
+                                   crStop(0);
+                               }
+                           } while (ispkt || inlen > 0);
+                           vret = ssh->agent_response;
+                           retlen = ssh->agent_response_len;
+                       } else
+                           sfree(agentreq);
                        ret = vret;
-                       sfree(agentreq);
                        if (ret) {
                            if (ret[4] == SSH1_AGENT_RSA_RESPONSE) {
                                logevent("Sending Pageant's response");
@@ -2702,8 +2875,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                            PKT_END);
                logevent("Unable to authenticate");
                connection_fatal(ssh->frontend, "Unable to authenticate");
-               ssh->state = SSH_STATE_CLOSED;
-               crReturn(1);
+                ssh_closing((Plug)ssh, NULL, 0, 0);
+               crStop(1);
            }
        } else {
            /* Prompt may have come from server. We've munged it a bit, so
@@ -2731,11 +2904,15 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            s->tried_publickey = 1;
            
            {
-               int ret = loadrsakey(&ssh->cfg.keyfile, &s->key, s->password);
+               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, ".\r\n");
+                   c_write_str(ssh, " (");
+                   c_write_str(ssh, error);
+                   c_write_str(ssh, ").\r\n");
                    continue;          /* go and try password */
                }
                if (ret == -1) {
@@ -2757,8 +2934,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                continue;              /* go and try password */
            }
            if (ssh->pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
-               bombout((ssh,"Bizarre response to offer of public key"));
-               crReturn(0);
+               bombout(("Bizarre response to offer of public key"));
+               crStop(0);
            }
 
            {
@@ -2793,8 +2970,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                " our public key.\r\n");
                continue;              /* go and try password */
            } else if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
-               bombout((ssh,"Bizarre response to RSA authentication response"));
-               crReturn(0);
+               bombout(("Bizarre response to RSA authentication response"));
+               crStop(0);
            }
 
            break;                     /* we're through! */
@@ -2857,7 +3034,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
                    assert(pwlen >= bottom && pwlen <= top);
 
-                   randomstr = smalloc(top + 1);
+                   randomstr = snewn(top + 1, char);
 
                    for (i = bottom; i <= top; i++) {
                        if (i == pwlen)
@@ -2876,6 +3053,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    }
                    logevent("Sending password with camouflage packets");
                    ssh_pkt_defersend(ssh);
+                   sfree(randomstr);
                } 
                else if (!(ssh->remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) {
                    /*
@@ -2926,8 +3104,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                c_write_str(ssh, "Access denied\r\n");
            logevent("Authentication refused");
        } else if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
-           bombout((ssh,"Strange packet received, type %d", ssh->pktin.type));
-           crReturn(0);
+           bombout(("Strange packet received, type %d", ssh->pktin.type));
+           crStop(0);
        }
     }
 
@@ -2940,6 +3118,11 @@ void sshfwd_close(struct ssh_channel *c)
 {
     Ssh ssh = c->ssh;
 
+    if (ssh->state != SSH_STATE_SESSION) {
+       assert(ssh->state == SSH_STATE_CLOSED);
+       return;
+    }
+
     if (c && !c->closes) {
        /*
         * If the channel's remoteid is -1, we have sent
@@ -2974,6 +3157,11 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
 {
     Ssh ssh = c->ssh;
 
+    if (ssh->state != SSH_STATE_SESSION) {
+       assert(ssh->state == SSH_STATE_CLOSED);
+       return 0;
+    }
+
     if (ssh->version == 1) {
        send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
                    PKT_INT, c->remoteid,
@@ -2996,6 +3184,11 @@ void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
 {
     Ssh ssh = c->ssh;
 
+    if (ssh->state != SSH_STATE_SESSION) {
+       assert(ssh->state == SSH_STATE_CLOSED);
+       return;
+    }
+
     if (ssh->version == 1) {
        if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) {
            c->v.v1.throttling = 0;
@@ -3026,8 +3219,8 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        } while (!ispkt);
        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
-           bombout((ssh,"Protocol confusion"));
-           crReturnV;
+           bombout(("Protocol confusion"));
+           crStopV;
        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
            logevent("Agent forwarding refused");
        } else {
@@ -3056,8 +3249,8 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        } while (!ispkt);
        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
-           bombout((ssh,"Protocol confusion"));
-           crReturnV;
+           bombout(("Protocol confusion"));
+           crStopV;
        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
            logevent("X11 forwarding refused");
        } else {
@@ -3097,30 +3290,36 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                if (n < 255) sports[n++] = *ssh->portfwd_strptr++;
            }
            sports[n] = 0;
-           if (*ssh->portfwd_strptr == '\t')
-               ssh->portfwd_strptr++;
-           n = 0;
-           while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':') {
-               if (n < 255) host[n++] = *ssh->portfwd_strptr++;
-           }
-           host[n] = 0;
-           if (*ssh->portfwd_strptr == ':')
+           if (type != 'D') {
+               if (*ssh->portfwd_strptr == '\t')
+                   ssh->portfwd_strptr++;
+               n = 0;
+               while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':') {
+                   if (n < 255) host[n++] = *ssh->portfwd_strptr++;
+               }
+               host[n] = 0;
+               if (*ssh->portfwd_strptr == ':')
+                   ssh->portfwd_strptr++;
+               n = 0;
+               while (*ssh->portfwd_strptr) {
+                   if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
+               }
+               dports[n] = 0;
                ssh->portfwd_strptr++;
-           n = 0;
-           while (*ssh->portfwd_strptr) {
-               if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
-           }
-           dports[n] = 0;
-           ssh->portfwd_strptr++;
-           dport = atoi(dports);
-           dserv = 0;
-           if (dport == 0) {
-               dserv = 1;
-               dport = net_service_lookup(dports);
-               if (!dport) {
-                   logeventf(ssh, "Service lookup failed for"
-                             " destination port \"%s\"", dports);
+               dport = atoi(dports);
+               dserv = 0;
+               if (dport == 0) {
+                   dserv = 1;
+                   dport = net_service_lookup(dports);
+                   if (!dport) {
+                       logeventf(ssh, "Service lookup failed for"
+                                 " destination port \"%s\"", dports);
+                   }
                }
+           } else {
+               while (*ssh->portfwd_strptr) ssh->portfwd_strptr++;
+               dport = dserv = -1;
+               ssh->portfwd_strptr++; /* eat the NUL and move to next one */
            }
            sport = atoi(sports);
            sserv = 0;
@@ -3145,9 +3344,18 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                              host,
                              (int)(dserv ? strlen(dports) : 0), dports,
                              dserv, "(", dport, dserv, ")");
+               } else if (type == 'D') {
+                   pfd_addforward(NULL, -1, *saddr ? saddr : NULL,
+                                  sport, ssh, &ssh->cfg);
+                   logeventf(ssh, "Local port %.*s%.*s%.*s%.*s%d%.*s"
+                             " doing SOCKS dynamic forwarding",
+                             (int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
+                             (int)(*saddr?1:0), ":",
+                             (int)(sserv ? strlen(sports) : 0), sports,
+                             sserv, "(", sport, sserv, ")");
                } else {
                    struct ssh_rportfwd *pf;
-                   pf = smalloc(sizeof(*pf));
+                   pf = snew(struct ssh_rportfwd);
                    strcpy(pf->dhost, host);
                    pf->dport = dport;
                    if (saddr) {
@@ -3178,8 +3386,8 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        } while (!ispkt);
                        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
                            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
-                           bombout((ssh,"Protocol confusion"));
-                           crReturnV;
+                           bombout(("Protocol confusion"));
+                           crStopV;
                        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
                            c_write_str(ssh, "Server refused port"
                                        " forwarding\r\n");
@@ -3203,8 +3411,8 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        } while (!ispkt);
        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
-           bombout((ssh,"Protocol confusion"));
-           crReturnV;
+           bombout(("Protocol confusion"));
+           crStopV;
        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
            c_write_str(ssh, "Server refused to allocate pty\r\n");
            ssh->editing = ssh->echoing = 1;
@@ -3221,8 +3429,8 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        } while (!ispkt);
        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
-           bombout((ssh,"Protocol confusion"));
-           crReturnV;
+           bombout(("Protocol confusion"));
+           crStopV;
        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
            c_write_str(ssh, "Server refused to compress\r\n");
        }
@@ -3280,9 +3488,9 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    ssh1_throttle(ssh, +1);
                }
            } else if (ssh->pktin.type == SSH1_MSG_DISCONNECT) {
-               ssh->state = SSH_STATE_CLOSED;
+                ssh_closing((Plug)ssh, NULL, 0, 0);
                logevent("Received disconnect request");
-               crReturnV;
+               crStopV;
            } else if (ssh->pktin.type == SSH1_SMSG_X11_OPEN) {
                /* Remote side is trying to open a channel to talk to our
                 * X-Server. Give them back a local channel number. */
@@ -3295,7 +3503,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                PKT_INT, GET_32BIT(ssh->pktin.body), PKT_END);
                    logevent("Rejected X11 connect request");
                } else {
-                   c = smalloc(sizeof(struct ssh_channel));
+                   c = snew(struct ssh_channel);
                    c->ssh = ssh;
 
                    if (x11_init(&c->u.x11.s, ssh->cfg.x11_display, c,
@@ -3330,7 +3538,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
                                PKT_INT, GET_32BIT(ssh->pktin.body), PKT_END);
                } else {
-                   c = smalloc(sizeof(struct ssh_channel));
+                   c = snew(struct ssh_channel);
                    c->ssh = ssh;
                    c->remoteid = GET_32BIT(ssh->pktin.body);
                    c->localid = alloc_channel_id(ssh);
@@ -3350,8 +3558,9 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                struct ssh_rportfwd pf;
                int hostsize, port;
                char host[256], buf[1024];
-               char *p, *h, *e;
-               c = smalloc(sizeof(struct ssh_channel));
+               char *p, *h;
+               const char *e;
+               c = snew(struct ssh_channel);
                c->ssh = ssh;
 
                hostsize = GET_32BIT(ssh->pktin.body+4);
@@ -3472,10 +3681,11 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        sfree(c);
                    }
                } else {
-                   bombout((ssh,"Received CHANNEL_CLOSE%s for %s channel %d\n",
+                   bombout(("Received CHANNEL_CLOSE%s for %s channel %d\n",
                             ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE ? "" :
                             "_CONFIRMATION", c ? "half-open" : "nonexistent",
                             i));
+                   crStopV;
                }
            } else if (ssh->pktin.type == SSH1_MSG_CHANNEL_DATA) {
                /* Data sent down one of our channels. */
@@ -3485,7 +3695,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                struct ssh_channel *c;
                c = find234(ssh->channels, &i, ssh_channelfind);
                if (c) {
-                   int bufsize;
+                   int bufsize = 0;
                    switch (c->type) {
                      case CHAN_X11:
                        bufsize = x11_send(c->u.x11.s, (char *)p, len);
@@ -3507,7 +3717,8 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                            if (c->u.a.lensofar == 4) {
                                c->u.a.totallen =
                                    4 + GET_32BIT(c->u.a.msglen);
-                               c->u.a.message = smalloc(c->u.a.totallen);
+                               c->u.a.message = snewn(c->u.a.totallen,
+                                                      unsigned char);
                                memcpy(c->u.a.message, c->u.a.msglen, 4);
                            }
                            if (c->u.a.lensofar >= 4 && len > 0) {
@@ -3521,25 +3732,13 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                c->u.a.lensofar += l;
                            }
                            if (c->u.a.lensofar == c->u.a.totallen) {
-                               void *reply, *sentreply;
+                               void *reply;
                                int replylen;
-                               agent_query(c->u.a.message,
-                                           c->u.a.totallen, &reply,
-                                           &replylen);
-                               if (reply)
-                                   sentreply = reply;
-                               else {
-                                   /* Fake SSH_AGENT_FAILURE. */
-                                   sentreply = "\0\0\0\1\5";
-                                   replylen = 5;
-                               }
-                               send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
-                                           PKT_INT, c->remoteid,
-                                           PKT_INT, replylen,
-                                           PKT_DATA, sentreply, replylen,
-                                           PKT_END);
-                               if (reply)
-                                   sfree(reply);
+                               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.lensofar = 0;
                            }
@@ -3571,11 +3770,11 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                  * encrypted packet, we close the session once
                  * we've sent EXIT_CONFIRMATION.
                  */
-                ssh->state = SSH_STATE_CLOSED;
-                crReturnV;
+                ssh_closing((Plug)ssh, NULL, 0, 0);
+                crStopV;
            } else {
-               bombout((ssh,"Strange packet received: type %d", ssh->pktin.type));
-               crReturnV;
+               bombout(("Strange packet received: type %d", ssh->pktin.type));
+               crStopV;
            }
        } else {
            while (inlen > 0) {
@@ -3847,8 +4046,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        int i, j, len;
 
        if (ssh->pktin.type != SSH2_MSG_KEXINIT) {
-           bombout((ssh,"expected key exchange packet from server"));
-           crReturn(0);
+           bombout(("expected key exchange packet from server"));
+           crStop(0);
        }
        ssh->kex = NULL;
        ssh->hostkey = NULL;
@@ -3897,9 +4096,9 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            }
        }
        if (!s->cscipher_tobe) {
-           bombout((ssh,"Couldn't agree a client-to-server cipher (available: %s)",
+           bombout(("Couldn't agree a client-to-server cipher (available: %s)",
                     str ? str : "(null)"));
-           crReturn(0);
+           crStop(0);
        }
 
        ssh2_pkt_getstring(ssh, &str, &len);    /* server->client cipher */
@@ -3923,9 +4122,9 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            }
        }
        if (!s->sccipher_tobe) {
-           bombout((ssh,"Couldn't agree a server-to-client cipher (available: %s)",
+           bombout(("Couldn't agree a server-to-client cipher (available: %s)",
                     str ? str : "(null)"));
-           crReturn(0);
+           crStop(0);
        }
 
        ssh2_pkt_getstring(ssh, &str, &len);    /* client->server mac */
@@ -3997,8 +4196,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
        crWaitUntil(ispkt);
        if (ssh->pktin.type != SSH2_MSG_KEX_DH_GEX_GROUP) {
-           bombout((ssh,"expected key exchange group packet from server"));
-           crReturn(0);
+           bombout(("expected key exchange group packet from server"));
+           crStop(0);
        }
        s->p = ssh2_pkt_getmp(ssh);
        s->g = ssh2_pkt_getmp(ssh);
@@ -4023,8 +4222,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     crWaitUntil(ispkt);
     if (ssh->pktin.type != s->kex_reply_value) {
-       bombout((ssh,"expected key exchange reply packet from server"));
-       crReturn(0);
+       bombout(("expected key exchange reply packet from server"));
+       crStop(0);
     }
     ssh2_pkt_getstring(ssh, &s->hostkeydata, &s->hostkeylen);
     s->f = ssh2_pkt_getmp(ssh);
@@ -4055,8 +4254,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     if (!s->hkey ||
        !ssh->hostkey->verifysig(s->hkey, s->sigdata, s->siglen,
                                 (char *)s->exchange_hash, 20)) {
-       bombout((ssh,"Server's host key did not match the signature supplied"));
-       crReturn(0);
+       bombout(("Server's host key did not match the signature supplied"));
+       crStop(0);
     }
 
     /*
@@ -4087,8 +4286,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      */
     crWaitUntil(ispkt);
     if (ssh->pktin.type != SSH2_MSG_NEWKEYS) {
-       bombout((ssh,"expected new-keys packet from server"));
-       crReturn(0);
+       bombout(("expected new-keys packet from server"));
+       crStop(0);
     }
 
     /*
@@ -4156,6 +4355,10 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     if (ssh->sccomp->text_name)
        logeventf(ssh, "Initialised %s decompression",
                  ssh->sccomp->text_name);
+    freebn(s->f);
+    freebn(s->g);
+    freebn(s->K);
+    freebn(s->p);
 
     /*
      * If this is the first key exchange phase, we must pass the
@@ -4302,8 +4505,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     ssh2_pkt_send(ssh);
     crWaitUntilV(ispkt);
     if (ssh->pktin.type != SSH2_MSG_SERVICE_ACCEPT) {
-       bombout((ssh,"Server refused user authentication protocol"));
-       crReturnV;
+       bombout(("Server refused user authentication protocol"));
+       crStopV;
     }
 
     /*
@@ -4351,8 +4554,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                     * Terminate.
                     */
                    logevent("No username provided. Abandoning session.");
-                   ssh->state = SSH_STATE_CLOSED;
-                   crReturnV;
+                    ssh_closing((Plug)ssh, NULL, 0, 0);
+                   crStopV;
                }
            } else {
                int ret;               /* need not be saved across crReturn */
@@ -4409,7 +4612,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            if (keytype == SSH_KEYTYPE_SSH2) {
                s->publickey_blob =
                    ssh2_userkey_loadpub(&ssh->cfg.keyfile, NULL,
-                                        &s->publickey_bloblen);
+                                        &s->publickey_bloblen, NULL);
            } else {
                char *msgbuf;
                logeventf(ssh, "Unable to use this key file (%s)",
@@ -4467,9 +4670,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                if (!s->gotit)
                    s->curr_prompt = 0;
            } else if (ssh->pktin.type != SSH2_MSG_USERAUTH_FAILURE) {
-               bombout((ssh,"Strange packet received during authentication: type %d",
+               bombout(("Strange packet received during authentication: type %d",
                         ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
 
            s->gotit = FALSE;
@@ -4565,7 +4768,19 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                /* Request the keys held by the agent. */
                PUT_32BIT(s->request, 1);
                s->request[4] = SSH2_AGENTC_REQUEST_IDENTITIES;
-               agent_query(s->request, 5, &r, &s->responselen);
+               if (!agent_query(s->request, 5, &r, &s->responselen,
+                                ssh_agent_callback, ssh)) {
+                   do {
+                       crReturnV;
+                       if (ispkt) {
+                           bombout(("Unexpected data from server while"
+                                    " waiting for agent response"));
+                           crStopV;
+                       }
+                   } while (ispkt || 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) {
@@ -4647,7 +4862,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        s->len += 4 + s->pklen; /* key blob */
                        s->len += 4 + s->siglen;        /* data to sign */
                        s->len += 4;      /* flags */
-                       s->agentreq = smalloc(4 + s->len);
+                       s->agentreq = snewn(4 + s->len, char);
                        PUT_32BIT(s->agentreq, s->len);
                        s->q = s->agentreq + 4;
                        *s->q++ = SSH2_AGENTC_SIGN_REQUEST;
@@ -4669,7 +4884,21 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        s->q += ssh->pktout.length - 5;
                        /* And finally the (zero) flags word. */
                        PUT_32BIT(s->q, 0);
-                       agent_query(s->agentreq, s->len + 4, &vret, &s->retlen);
+                       if (!agent_query(s->agentreq, s->len + 4,
+                                        &vret, &s->retlen,
+                                        ssh_agent_callback, ssh)) {
+                           do {
+                               crReturnV;
+                               if (ispkt) {
+                                   bombout(("Unexpected data from server"
+                                            " while waiting for agent"
+                                            " response"));
+                                   crStopV;
+                               }
+                           } while (ispkt || inlen > 0);
+                           vret = ssh->agent_response;
+                           s->retlen = ssh->agent_response_len;
+                       }
                        s->ret = vret;
                        sfree(s->agentreq);
                        if (s->ret) {
@@ -4713,7 +4942,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                pub_blob =
                    (unsigned char *)ssh2_userkey_loadpub(&ssh->cfg.keyfile,
                                                          &algorithm,
-                                                         &pub_blob_len);
+                                                         &pub_blob_len,
+                                                         NULL);
                if (pub_blob) {
                    ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
                    ssh2_pkt_addstring(ssh, s->username);
@@ -4865,8 +5095,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        logevent("Unable to authenticate");
                        connection_fatal(ssh->frontend,
                                         "Unable to authenticate");
-                       ssh->state = SSH_STATE_CLOSED;
-                       crReturnV;
+                        ssh_closing((Plug)ssh, NULL, 0, 0);
+                       crStopV;
                    }
                } else {
                    int ret;           /* need not be saved across crReturn */
@@ -4890,14 +5120,18 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                 * 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);
+               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\r\n");
+                       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. */
@@ -4938,7 +5172,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    sigdata_len = ssh->pktout.length - 5 + 4 + 20;
                     if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
                         sigdata_len -= 4;
-                   sigdata = smalloc(sigdata_len);
+                   sigdata = snewn(sigdata_len, unsigned char);
                     p = 0;
                     if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
                         PUT_32BIT(sigdata+p, 20);
@@ -5054,8 +5288,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                   " methods available");
                ssh2_pkt_addstring(ssh, "en");  /* language tag */
                ssh2_pkt_send(ssh);
-               ssh->state = SSH_STATE_CLOSED;
-               crReturnV;
+                ssh_closing((Plug)ssh, NULL, 0, 0);
+               crStopV;
            }
        }
     } while (!s->we_are_in);
@@ -5070,7 +5304,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * So now create a channel with a session in it.
      */
     ssh->channels = newtree234(ssh_channelcmp);
-    ssh->mainchan = smalloc(sizeof(struct ssh_channel));
+    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);
@@ -5082,13 +5316,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     ssh2_pkt_send(ssh);
     crWaitUntilV(ispkt);
     if (ssh->pktin.type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
-       bombout((ssh,"Server refused to open a session"));
-       crReturnV;
+       bombout(("Server refused to open a session"));
+       crStopV;
        /* FIXME: error data comes back in FAILURE packet */
     }
     if (ssh2_pkt_getuint32(ssh) != ssh->mainchan->localid) {
-       bombout((ssh,"Server's channel confirmation cited wrong channel"));
-       crReturnV;
+       bombout(("Server's channel confirmation cited wrong channel"));
+       crStopV;
     }
     ssh->mainchan->remoteid = ssh2_pkt_getuint32(ssh);
     ssh->mainchan->type = CHAN_MAINSESSION;
@@ -5132,9 +5366,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
        if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
            if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
-               bombout((ssh,"Unexpected response to X11 forwarding request:"
+               bombout(("Unexpected response to X11 forwarding request:"
                         " packet type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
            logevent("X11 forwarding refused");
        } else {
@@ -5177,30 +5411,36 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                if (n < 255) sports[n++] = *ssh->portfwd_strptr++;
            }
            sports[n] = 0;
-           if (*ssh->portfwd_strptr == '\t')
-               ssh->portfwd_strptr++;
-           n = 0;
-           while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':') {
-               if (n < 255) host[n++] = *ssh->portfwd_strptr++;
-           }
-           host[n] = 0;
-           if (*ssh->portfwd_strptr == ':')
+           if (type != 'D') {
+               if (*ssh->portfwd_strptr == '\t')
+                   ssh->portfwd_strptr++;
+               n = 0;
+               while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':') {
+                   if (n < 255) host[n++] = *ssh->portfwd_strptr++;
+               }
+               host[n] = 0;
+               if (*ssh->portfwd_strptr == ':')
+                   ssh->portfwd_strptr++;
+               n = 0;
+               while (*ssh->portfwd_strptr) {
+                   if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
+               }
+               dports[n] = 0;
                ssh->portfwd_strptr++;
-           n = 0;
-           while (*ssh->portfwd_strptr) {
-               if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
-           }
-           dports[n] = 0;
-           ssh->portfwd_strptr++;
-           dport = atoi(dports);
-           dserv = 0;
-           if (dport == 0) {
-               dserv = 1;
-               dport = net_service_lookup(dports);
-               if (!dport) {
-                   logeventf(ssh, "Service lookup failed for destination"
-                             " port \"%s\"", dports);
+               dport = atoi(dports);
+               dserv = 0;
+               if (dport == 0) {
+                   dserv = 1;
+                   dport = net_service_lookup(dports);
+                   if (!dport) {
+                       logeventf(ssh, "Service lookup failed for destination"
+                                 " port \"%s\"", dports);
+                   }
                }
+           } else {
+               while (*ssh->portfwd_strptr) ssh->portfwd_strptr++;
+               dport = dserv = -1;
+               ssh->portfwd_strptr++; /* eat the NUL and move to next one */
            }
            sport = atoi(sports);
            sserv = 0;
@@ -5225,9 +5465,18 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                              host,
                              (int)(dserv ? strlen(dports) : 0), dports,
                              dserv, "(", dport, dserv, ")");
+               } else if (type == 'D') {
+                   pfd_addforward(NULL, -1, *saddr ? saddr : NULL,
+                                  sport, ssh, &ssh->cfg);
+                   logeventf(ssh, "Local port %.*s%.*s%.*s%.*s%d%.*s"
+                             " doing SOCKS dynamic forwarding",
+                             (int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
+                             (int)(*saddr?1:0), ":",
+                             (int)(sserv ? strlen(sports) : 0), sports,
+                             sserv, "(", sport, sserv, ")");
                } else {
                    struct ssh_rportfwd *pf;
-                   pf = smalloc(sizeof(*pf));
+                   pf = snew(struct ssh_rportfwd);
                    strcpy(pf->dhost, host);
                    pf->dport = dport;
                    pf->sport = sport;
@@ -5273,10 +5522,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
                        if (ssh->pktin.type != SSH2_MSG_REQUEST_SUCCESS) {
                            if (ssh->pktin.type != SSH2_MSG_REQUEST_FAILURE) {
-                               bombout((ssh,"Unexpected response to port "
+                               bombout(("Unexpected response to port "
                                         "forwarding request: packet type %d",
                                         ssh->pktin.type));
-                               crReturnV;
+                               crStopV;
                            }
                            logevent("Server refused this port forwarding");
                        } else {
@@ -5313,9 +5562,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
        if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
            if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
-               bombout((ssh,"Unexpected response to agent forwarding request:"
+               bombout(("Unexpected response to agent forwarding request:"
                         " packet type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
            logevent("Agent forwarding refused");
        } else {
@@ -5356,9 +5605,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
        if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
            if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
-               bombout((ssh,"Unexpected response to pty request:"
+               bombout(("Unexpected response to pty request:"
                         " packet type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
            c_write_str(ssh, "Server refused to allocate pty\r\n");
            ssh->editing = ssh->echoing = 1;
@@ -5414,9 +5663,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        } while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
        if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
            if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
-               bombout((ssh,"Unexpected response to shell/command request:"
+               bombout(("Unexpected response to shell/command request:"
                         " packet type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
            /*
             * We failed to start the command. If this is the
@@ -5429,8 +5678,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                ssh->fallback_cmd = TRUE;
                continue;
            }
-           bombout((ssh,"Server refused to start a shell/command"));
-           crReturnV;
+           bombout(("Server refused to start a shell/command"));
+           crStopV;
        } else {
            logevent("Started a shell/command");
        }
@@ -5467,7 +5716,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    continue;          /* extended but not stderr */
                ssh2_pkt_getstring(ssh, &data, &length);
                if (data) {
-                   int bufsize;
+                   int bufsize = 0;
                    c->v.v2.locwindow -= length;
                    switch (c->type) {
                      case CHAN_MAINSESSION:
@@ -5495,7 +5744,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                            if (c->u.a.lensofar == 4) {
                                c->u.a.totallen =
                                    4 + GET_32BIT(c->u.a.msglen);
-                               c->u.a.message = smalloc(c->u.a.totallen);
+                               c->u.a.message = snewn(c->u.a.totallen,
+                                                      unsigned char);
                                memcpy(c->u.a.message, c->u.a.msglen, 4);
                            }
                            if (c->u.a.lensofar >= 4 && length > 0) {
@@ -5509,22 +5759,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                c->u.a.lensofar += l;
                            }
                            if (c->u.a.lensofar == c->u.a.totallen) {
-                               void *reply, *sentreply;
+                               void *reply;
                                int replylen;
-                               agent_query(c->u.a.message,
-                                           c->u.a.totallen, &reply,
-                                           &replylen);
-                               if (reply)
-                                   sentreply = reply;
-                               else {
-                                   /* Fake SSH_AGENT_FAILURE. */
-                                   sentreply = "\0\0\0\1\5";
-                                   replylen = 5;
-                               }
-                               ssh2_add_channel_data(c, sentreply, replylen);
-                               s->try_send = TRUE;
-                               if (reply)
-                                   sfree(reply);
+                               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.lensofar = 0;
                            }
@@ -5566,8 +5807,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
                c = find234(ssh->channels, &i, ssh_channelfind);
                if (!c || ((int)c->remoteid) == -1) {
-                   bombout((ssh,"Received CHANNEL_CLOSE for %s channel %d\n",
+                   bombout(("Received CHANNEL_CLOSE for %s channel %d\n",
                             c ? "half-open" : "nonexistent", i));
+                   crStopV;
                }
                /* Do pre-close processing on the channel. */
                switch (c->type) {
@@ -5600,6 +5842,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                 * See if that was the last channel left open.
                 */
                if (count234(ssh->channels) == 0) {
+                   logevent("All channels closed. Disconnecting");
 #if 0
                     /*
                      * We used to send SSH_MSG_DISCONNECT here,
@@ -5612,15 +5855,14 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                      * this is more polite than sending a
                      * DISCONNECT. So now we don't.
                      */
-                   logevent("All channels closed. Disconnecting");
                    ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
                    ssh2_pkt_adduint32(ssh, SSH2_DISCONNECT_BY_APPLICATION);
                    ssh2_pkt_addstring(ssh, "All open channels closed");
                    ssh2_pkt_addstring(ssh, "en");      /* language tag */
                    ssh2_pkt_send(ssh);
 #endif
-                   ssh->state = SSH_STATE_CLOSED;
-                   crReturnV;
+                    ssh_closing((Plug)ssh, NULL, 0, 0);
+                   crStopV;
                }
                continue;              /* remote sends close; ignore (FIXME) */
            } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
@@ -5696,9 +5938,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    ssh2_pkt_addstring(ssh, buf);
                    ssh2_pkt_addstring(ssh, "en");      /* language tag */
                    ssh2_pkt_send(ssh);
-                   connection_fatal("%s", buf);
-                   ssh->state = SSH_STATE_CLOSED;
-                   crReturnV;
+                   connection_fatal(ssh->frontend, "%s", buf);
+                    ssh_closing((Plug)ssh, NULL, 0, 0);
+                   crStopV;
                }
 
                /*
@@ -5754,29 +5996,31 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                int typelen;
                char *peeraddr;
                int peeraddrlen;
-               int port;
+               int peerport;
                char *error = NULL;
                struct ssh_channel *c;
                unsigned remid, winsize, pktsize;
                ssh2_pkt_getstring(ssh, &type, &typelen);
-               c = smalloc(sizeof(struct ssh_channel));
+               c = snew(struct ssh_channel);
                c->ssh = ssh;
 
                remid = ssh2_pkt_getuint32(ssh);
                winsize = ssh2_pkt_getuint32(ssh);
                pktsize = ssh2_pkt_getuint32(ssh);
-               ssh2_pkt_getstring(ssh, &peeraddr, &peeraddrlen);
-               port = ssh2_pkt_getuint32(ssh);
 
                if (typelen == 3 && !memcmp(type, "x11", 3)) {
-                   char *addrstr = smalloc(peeraddrlen+1);
+                   char *addrstr;
+
+                    ssh2_pkt_getstring(ssh, &peeraddr, &peeraddrlen);
+                   addrstr = snewn(peeraddrlen+1, char);
                    memcpy(addrstr, peeraddr, peeraddrlen);
                    peeraddr[peeraddrlen] = '\0';
+                    peerport = ssh2_pkt_getuint32(ssh);
 
                    if (!ssh->X11_fwd_enabled)
                        error = "X11 forwarding is not enabled";
                    else if (x11_init(&c->u.x11.s, ssh->cfg.x11_display, c,
-                                     ssh->x11auth, addrstr, port,
+                                     ssh->x11auth, addrstr, peerport,
                                      &ssh->cfg) != NULL) {
                        error = "Unable to open an X11 connection";
                    } else {
@@ -5791,12 +6035,16 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    int dummylen;
                    ssh2_pkt_getstring(ssh, &dummy, &dummylen);/* skip address */
                    pf.sport = ssh2_pkt_getuint32(ssh);
+                    ssh2_pkt_getstring(ssh, &peeraddr, &peeraddrlen);
+                    peerport = ssh2_pkt_getuint32(ssh);
                    realpf = find234(ssh->rportfwds, &pf, NULL);
                    if (realpf == NULL) {
                        error = "Remote port is not recognised";
                    } else {
-                       char *e = pfd_newconnect(&c->u.pfd.s, realpf->dhost,
-                                                realpf->dport, c, &ssh->cfg);
+                       const char *e = pfd_newconnect(&c->u.pfd.s,
+                                                      realpf->dhost,
+                                                      realpf->dport, c,
+                                                      &ssh->cfg);
                        logeventf(ssh, "Received remote port open request"
                                  " for %s:%d", realpf->dhost, realpf->dport);
                        if (e != NULL) {
@@ -5844,8 +6092,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    ssh2_pkt_send(ssh);
                }
            } else {
-               bombout((ssh,"Strange packet received: type %d", ssh->pktin.type));
-               crReturnV;
+               bombout(("Strange packet received: type %d", ssh->pktin.type));
+               crStopV;
            }
        } else {
            /*
@@ -5905,15 +6153,16 @@ static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
  *
  * Returns an error message, or NULL on success.
  */
-static char *ssh_init(void *frontend_handle, void **backend_handle,
-                     Config *cfg,
-                     char *host, int port, char **realhost, int nodelay)
+static const char *ssh_init(void *frontend_handle, void **backend_handle,
+                           Config *cfg,
+                           char *host, int port, char **realhost, int nodelay)
 {
-    char *p;
+    const char *p;
     Ssh ssh;
 
-    ssh = smalloc(sizeof(*ssh));
+    ssh = snew(struct ssh_tag);
     ssh->cfg = *cfg;                  /* STRUCTURE COPY */
+    ssh->version = 0;                 /* when not ready yet */
     ssh->s = NULL;
     ssh->cipher = NULL;
     ssh->v1_cipher_ctx = NULL;
@@ -6050,9 +6299,24 @@ static void ssh_free(void *handle)
     sfree(ssh->do_ssh1_login_state);
     sfree(ssh->do_ssh2_transport_state);
     sfree(ssh->do_ssh2_authconn_state);
-    
+    if (ssh->pktout.data) {
+       sfree(ssh->pktout.data);
+       ssh->pktout.data = NULL;
+    }
+    if (ssh->pktin.data) {
+       sfree(ssh->pktin.data);
+       ssh->pktin.data = NULL;
+    }
+    if (ssh->crcda_ctx) {
+       crcda_free_context(ssh->crcda_ctx);
+       ssh->crcda_ctx = NULL;
+    }
+    if (ssh->logctx) {
+       log_free(ssh->logctx);
+       ssh->logctx = NULL;
+    }
     if (ssh->s)
-       sk_close(ssh->s);
+       ssh_do_close(ssh);
     sfree(ssh);
 }
 
@@ -6160,6 +6424,31 @@ static void ssh_size(void *handle, int width, int height)
 }
 
 /*
+ * Return a list of the special codes that make sense in this
+ * protocol.
+ */
+static const struct telnet_special *ssh_get_specials(void *handle)
+{
+    Ssh ssh = (Ssh) handle;
+
+    if (ssh->version == 1) {
+       static const struct telnet_special ssh1_specials[] = {
+           {"IGNORE message", TS_NOP},
+           {NULL, 0}
+       };
+       return ssh1_specials;
+    } else if (ssh->version == 2) {
+       static const struct telnet_special ssh2_specials[] = {
+           {"Break", TS_BRK},
+           {"IGNORE message", TS_NOP},
+           {NULL, 0}
+       };
+       return ssh2_specials;
+    } else
+       return NULL;
+}
+
+/*
  * Send Telnet special codes. TS_EOF is useful for `plink', so you
  * can send an EOF and collect resulting output (e.g. `plink
  * hostname sort').
@@ -6186,7 +6475,7 @@ static void ssh_special(void *handle, Telnet_Special code)
            ssh2_pkt_send(ssh);
        }
        logevent("Sent EOF message");
-    } else if (code == TS_PING) {
+    } else if (code == TS_PING || code == TS_NOP) {
        if (ssh->state == SSH_STATE_CLOSED
            || ssh->state == SSH_STATE_PREPACKET) return;
        if (ssh->version == 1) {
@@ -6197,6 +6486,19 @@ static void ssh_special(void *handle, Telnet_Special code)
            ssh2_pkt_addstring_start(ssh);
            ssh2_pkt_send(ssh);
        }
+    } else if (code == TS_BRK) {
+       if (ssh->state == SSH_STATE_CLOSED
+           || ssh->state == SSH_STATE_PREPACKET) return;
+       if (ssh->version == 1) {
+           logevent("Unable to send BREAK signal in SSH1");
+       } else {
+           ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
+           ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
+           ssh2_pkt_addstring(ssh, "break");
+           ssh2_pkt_addbool(ssh, 0);
+           ssh2_pkt_adduint32(ssh, 0);   /* default break length */
+           ssh2_pkt_send(ssh);
+       }
     } else {
        /* do nothing */
     }
@@ -6206,7 +6508,7 @@ void *new_sock_channel(void *handle, Socket s)
 {
     Ssh ssh = (Ssh) handle;
     struct ssh_channel *c;
-    c = smalloc(sizeof(struct ssh_channel));
+    c = snew(struct ssh_channel);
     c->ssh = ssh;
 
     if (c) {
@@ -6312,7 +6614,10 @@ static void ssh_provide_logctx(void *handle, void *logctx)
 static int ssh_return_exitcode(void *handle)
 {
     Ssh ssh = (Ssh) handle;
-    return ssh->exitcode;
+    if (ssh->s != NULL)
+        return -1;
+    else
+        return (ssh->exitcode >= 0 ? ssh->exitcode : 0);
 }
 
 /*
@@ -6334,6 +6639,7 @@ Backend ssh_backend = {
     ssh_sendbuffer,
     ssh_size,
     ssh_special,
+    ssh_get_specials,
     ssh_socket,
     ssh_return_exitcode,
     ssh_sendok,