X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/3d88e64dfcf5dc0fd361ce0c504c67a9196ce44c..f85e6f6edb2c9415bc10bd2015479d72ea8c5ae2:/ssh.c

diff --git a/ssh.c b/ssh.c
index 25dee28f..23602f6d 100644
--- a/ssh.c
+++ b/ssh.c
@@ -322,6 +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
@@ -515,6 +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;
@@ -648,12 +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;
@@ -665,9 +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)
 {
@@ -835,18 +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;
@@ -854,9 +868,12 @@ 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;
@@ -886,8 +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);
 	}
     }
 
@@ -919,8 +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);
@@ -974,8 +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);
     }
 
     /*
@@ -1023,8 +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 */
 
@@ -1082,13 +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:
@@ -1230,7 +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);
 
@@ -1668,7 +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);
@@ -1763,7 +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
@@ -1775,7 +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
@@ -1799,6 +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)))) {
@@ -1811,6 +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
@@ -1931,12 +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)) {
@@ -1977,6 +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);
@@ -2030,19 +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. */
     }
@@ -2054,10 +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;
@@ -2080,8 +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,
@@ -2091,7 +2137,7 @@ static char *connect_to_host(Ssh ssh, char *host, int port,
     };
 
     SockAddr addr;
-    char *err;
+    const char *err;
 
     ssh->savedhost = snewn(1 + strlen(host), char);
     if (!ssh->savedhost)
@@ -2107,8 +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.
@@ -2173,7 +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;
 	}
     }
@@ -2251,6 +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.
  */
@@ -2293,8 +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");
@@ -2403,12 +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. */
@@ -2452,8 +2538,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     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");
@@ -2469,8 +2555,8 @@ 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 */
@@ -2537,7 +2623,19 @@ 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) {
@@ -2599,9 +2697,23 @@ 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");
@@ -2747,8 +2859,8 @@ 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
@@ -2802,8 +2914,8 @@ 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);
 	    }
 
 	    {
@@ -2838,8 +2950,8 @@ 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! */
@@ -2971,8 +3083,8 @@ 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);
 	}
     }
 
@@ -2985,6 +3097,11 @@ 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
@@ -3019,6 +3136,11 @@ 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,
@@ -3041,6 +3163,11 @@ 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;
@@ -3071,8 +3198,8 @@ 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 {
@@ -3101,8 +3228,8 @@ 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 {
@@ -3142,30 +3269,35 @@ 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;
 	    }
 	    sport = atoi(sports);
 	    sserv = 0;
@@ -3190,6 +3322,15 @@ 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 = snew(struct ssh_rportfwd);
@@ -3223,8 +3364,8 @@ 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");
@@ -3248,8 +3389,8 @@ 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;
@@ -3266,8 +3407,8 @@ 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");
 	}
@@ -3325,9 +3466,9 @@ 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. */
@@ -3395,7 +3536,8 @@ 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;
+		char *p, *h;
+		const char *e;
 		c = snew(struct ssh_channel);
 		c->ssh = ssh;
 
@@ -3517,10 +3659,11 @@ 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. */
@@ -3530,7 +3673,7 @@ 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);
@@ -3567,25 +3710,13 @@ 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;
 			    }
@@ -3617,11 +3748,11 @@ 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) {
@@ -3893,8 +4024,8 @@ 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;
@@ -3943,9 +4074,9 @@ 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 */
@@ -3969,9 +4100,9 @@ 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 */
@@ -4043,8 +4174,8 @@ 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);
@@ -4069,8 +4200,8 @@ 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);
@@ -4101,8 +4232,8 @@ 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);
     }
 
     /*
@@ -4133,8 +4264,8 @@ 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);
     }
 
     /*
@@ -4348,8 +4479,8 @@ 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;
     }
 
     /*
@@ -4397,8 +4528,8 @@ 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 */
@@ -4513,9 +4644,9 @@ 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;
@@ -4611,7 +4742,19 @@ 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) {
@@ -4715,7 +4858,21 @@ 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) {
@@ -4911,8 +5068,8 @@ 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 */
@@ -4984,7 +5141,7 @@ 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 = snewn(sigdata_len, char);
+		    sigdata = snewn(sigdata_len, unsigned char);
                     p = 0;
                     if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
                         PUT_32BIT(sigdata+p, 20);
@@ -5100,8 +5257,8 @@ 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);
@@ -5128,13 +5285,13 @@ 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;
@@ -5178,9 +5335,9 @@ 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 {
@@ -5223,30 +5380,35 @@ 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;
 	    }
 	    sport = atoi(sports);
 	    sserv = 0;
@@ -5271,6 +5433,15 @@ 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 = snew(struct ssh_rportfwd);
@@ -5319,10 +5490,10 @@ 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 {
@@ -5359,9 +5530,9 @@ 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 {
@@ -5402,9 +5573,9 @@ 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;
@@ -5460,9 +5631,9 @@ 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
@@ -5475,8 +5646,8 @@ 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");
 	}
@@ -5513,7 +5684,7 @@ 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:
@@ -5556,22 +5727,13 @@ 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;
 			    }
@@ -5613,8 +5775,9 @@ 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) {
@@ -5647,6 +5810,7 @@ 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,
@@ -5659,15 +5823,14 @@ 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) {
@@ -5743,9 +5906,9 @@ 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;
 		}
 
 		/*
@@ -5801,7 +5964,7 @@ 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;
@@ -5812,18 +5975,20 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		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 = snewn(peeraddrlen+1, char);
+		    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 {
@@ -5838,12 +6003,16 @@ 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) {
@@ -5891,8 +6060,8 @@ 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 {
 	    /*
@@ -5952,15 +6121,16 @@ 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 = 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;
@@ -6099,7 +6269,7 @@ static void ssh_free(void *handle)
     sfree(ssh->do_ssh2_authconn_state);
     
     if (ssh->s)
-	sk_close(ssh->s);
+	ssh_do_close(ssh);
     sfree(ssh);
 }
 
@@ -6207,6 +6377,31 @@ 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').
@@ -6233,7 +6428,7 @@ 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) {
@@ -6244,6 +6439,19 @@ 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 */
     }
@@ -6359,7 +6567,10 @@ 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);
 }
 
 /*
@@ -6381,6 +6592,7 @@ Backend ssh_backend = {
     ssh_sendbuffer,
     ssh_size,
     ssh_special,
+    ssh_get_specials,
     ssh_socket,
     ssh_return_exitcode,
     ssh_sendok,