X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/2856a1b9009fe14b762f61c824d0e8d5cc86b542..679539d7ab96f188640d159ea0b004275db67356:/ssh.c

diff --git a/ssh.c b/ssh.c
index 76dc2ec6..1d887230 100644
--- 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,