X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/73feed4f401660e3374ea0f783ae7b7c6ea4c0c8..f89c329410c18fe1f09d843747fad77babb9f89c:/ssh.c

diff --git a/ssh.c b/ssh.c
index 69ff1746..f92975d9 100644
--- a/ssh.c
+++ b/ssh.c
@@ -104,7 +104,7 @@
  * Packet type contexts, so that ssh2_pkt_type can correctly decode
  * the ambiguous type numbers back into the correct type strings.
  */
-#define SSH2_PKTCTX_DHGROUP1         0x0001
+#define SSH2_PKTCTX_DHGROUP          0x0001
 #define SSH2_PKTCTX_DHGEX            0x0002
 #define SSH2_PKTCTX_PUBLICKEY        0x0010
 #define SSH2_PKTCTX_PASSWORD         0x0020
@@ -162,7 +162,7 @@ static const char *const ssh2_disconnect_reasons[] = {
 #define BUG_CHOKES_ON_RSA	        	  8
 #define BUG_SSH2_RSA_PADDING	        	 16
 #define BUG_SSH2_DERIVEKEY                       32
-#define BUG_SSH2_DH_GEX                          64
+/* 64 was BUG_SSH2_DH_GEX, now spare */
 #define BUG_SSH2_PK_SESSIONID                   128
 
 #define translate(x) if (type == x) return #x
@@ -222,8 +222,8 @@ static char *ssh2_pkt_type(int pkt_ctx, int type)
     translate(SSH2_MSG_SERVICE_ACCEPT);
     translate(SSH2_MSG_KEXINIT);
     translate(SSH2_MSG_NEWKEYS);
-    translatec(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP1);
-    translatec(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP1);
+    translatec(SSH2_MSG_KEXDH_INIT, SSH2_PKTCTX_DHGROUP);
+    translatec(SSH2_MSG_KEXDH_REPLY, SSH2_PKTCTX_DHGROUP);
     translatec(SSH2_MSG_KEX_DH_GEX_REQUEST, SSH2_PKTCTX_DHGEX);
     translatec(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
     translatec(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
@@ -316,20 +316,24 @@ enum {
 #define crWaitUntilV(c)	do { crReturnV; } while (!(c))
 
 typedef struct ssh_tag *Ssh;
-
-static void ssh2_pkt_init(Ssh, int pkt_type);
-static void ssh2_pkt_addbool(Ssh, unsigned char value);
-static void ssh2_pkt_adduint32(Ssh, unsigned long value);
-static void ssh2_pkt_addstring_start(Ssh);
-static void ssh2_pkt_addstring_str(Ssh, char *data);
-static void ssh2_pkt_addstring_data(Ssh, char *data, int len);
-static void ssh2_pkt_addstring(Ssh, char *data);
+struct Packet;
+
+static struct Packet *ssh2_pkt_init(int pkt_type);
+static void ssh2_pkt_addbool(struct Packet *, unsigned char value);
+static void ssh2_pkt_adduint32(struct Packet *, unsigned long value);
+static void ssh2_pkt_addstring_start(struct Packet *);
+static void ssh2_pkt_addstring_str(struct Packet *, char *data);
+static void ssh2_pkt_addstring_data(struct Packet *, char *data, int len);
+static void ssh2_pkt_addstring(struct Packet *, char *data);
 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);
+static void ssh2_pkt_addmp(struct Packet *, Bignum b);
+static int ssh2_pkt_construct(Ssh, struct Packet *);
+static void ssh2_pkt_send(Ssh, struct Packet *);
+static void ssh2_pkt_send_noqueue(Ssh, struct Packet *);
+static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
+			 struct Packet *pktin);
+static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
+			     struct Packet *pktin);
 
 /*
  * Buffer management constants. There are several of these for
@@ -356,11 +360,6 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt);
 #define SSH_MAX_BACKLOG 32768
 #define OUR_V2_WINSIZE 16384
 
-const static struct ssh_kex *kex_algs[] = {
-    &ssh_diffiehellman_gex,
-    &ssh_diffiehellman
-};
-
 const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
 
 static void *nullmac_make_context(void)
@@ -460,7 +459,7 @@ struct ssh_channel {
 	struct ssh_agent_channel {
 	    unsigned char *message;
 	    unsigned char msglen[4];
-	    int lensofar, totallen;
+	    unsigned lensofar, totallen;
 	} a;
 	struct ssh_x11_channel {
 	    Socket s;
@@ -495,27 +494,62 @@ struct ssh_channel {
  * of its ports was connected to; and _you_ have to remember what
  * local host:port pair went with that port number.
  * 
- * Hence: in SSH 1 this structure stores host:port pairs we intend
- * to allow connections to, and is indexed by those host:port
- * pairs. In SSH 2 it stores a mapping from source port to
- * destination host:port pair, and is indexed by source port.
+ * Hence, in SSH 1 this structure is indexed by destination
+ * host:port pair, whereas in SSH 2 it is indexed by source port.
  */
+struct ssh_portfwd; /* forward declaration */
+
 struct ssh_rportfwd {
     unsigned sport, dport;
     char dhost[256];
+    char *sportdesc;
+    struct ssh_portfwd *pfrec;
+};
+#define free_rportfwd(pf) ( \
+    ((pf) ? (sfree((pf)->sportdesc)) : (void)0 ), sfree(pf) )
+
+/*
+ * Separately to the rportfwd tree (which is for looking up port
+ * open requests from the server), a tree of _these_ structures is
+ * used to keep track of all the currently open port forwardings,
+ * so that we can reconfigure in mid-session if the user requests
+ * it.
+ */
+struct ssh_portfwd {
+    int keep;
+    int type;
+    unsigned sport, dport;
+    char *saddr, *daddr;
+    struct ssh_rportfwd *remote;
+    void *local;
 };
+#define free_portfwd(pf) ( \
+    ((pf) ? (sfree((pf)->saddr), sfree((pf)->daddr)) : (void)0 ), sfree(pf) )
 
 struct Packet {
     long length;
     int type;
+    unsigned long sequence;
     unsigned char *data;
     unsigned char *body;
     long savedpos;
     long maxlen;
+    long encrypted_len;		       /* for SSH2 total-size counting */
+
+    /*
+     * State associated with packet logging
+     */
+    int logmode;
+    int nblanks;
+    struct logblank_t *blanks;
 };
 
-static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt);
-static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt);
+static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen,
+			  struct Packet *pktin);
+static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen,
+			  struct Packet *pktin);
+static void ssh1_protocol_setup(Ssh ssh);
+static void ssh2_protocol_setup(Ssh ssh);
 static void ssh_size(void *handle, int width, int height);
 static void ssh_special(void *handle, Telnet_Special);
 static int ssh2_try_send(struct ssh_channel *c);
@@ -524,6 +558,12 @@ 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);
+static unsigned long ssh_pkt_getuint32(struct Packet *pkt);
+static int ssh2_pkt_getbool(struct Packet *pkt);
+static void ssh_pkt_getstring(struct Packet *pkt, char **p, int *length);
+static void ssh2_timer(void *ctx, long now);
+static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
+			     struct Packet *pktin);
 
 struct rdpkt1_state_tag {
     long len, pad, biglen, to_read;
@@ -531,6 +571,7 @@ struct rdpkt1_state_tag {
     unsigned char *p;
     int i;
     int chunk;
+    struct Packet *pktin;
 };
 
 struct rdpkt2_state_tag {
@@ -538,6 +579,18 @@ struct rdpkt2_state_tag {
     int i;
     int cipherblk;
     unsigned long incoming_sequence;
+    struct Packet *pktin;
+};
+
+typedef void (*handler_fn_t)(Ssh ssh, struct Packet *pktin);
+typedef void (*chandler_fn_t)(Ssh ssh, struct Packet *pktin, void *ctx);
+
+struct queued_handler;
+struct queued_handler {
+    int msg1, msg2;
+    chandler_fn_t handler;
+    void *ctx;
+    struct queued_handler *next;
 };
 
 struct ssh_tag {
@@ -586,7 +639,7 @@ struct ssh_tag {
     struct ssh_channel *mainchan;      /* primary session channel */
     int exitcode;
 
-    tree234 *rportfwds;
+    tree234 *rportfwds, *portfwds;
 
     enum {
 	SSH_STATE_PREPACKET,
@@ -598,19 +651,13 @@ struct ssh_tag {
 
     int size_needed, eof_needed;
 
-    struct Packet pktin;
-    struct Packet pktout;
+    struct Packet **queue;
+    int queuelen, queuesize;
+    int queueing;
     unsigned char *deferred_send_data;
     int deferred_len, deferred_size;
 
     /*
-     * State associated with packet logging
-     */
-    int pktout_logmode;
-    int pktout_nblanks;
-    struct logblank_t *pktout_blanks;
-
-    /*
      * Gross hack: pscp will try to start SFTP but fall back to
      * scp1 if that fails. This variable is the means by which
      * scp.c can reach into the SSH code and find out which one it
@@ -626,7 +673,6 @@ struct ssh_tag {
     int userpass_input_bufpos;
     int userpass_input_echo;
 
-    char *portfwd_strptr;
     int pkt_ctx;
 
     void *x11auth;
@@ -642,8 +688,8 @@ struct ssh_tag {
     int ssh2_rdpkt_crstate;
     int do_ssh_init_crstate;
     int ssh_gotdata_crstate;
-    int ssh1_protocol_crstate;
     int do_ssh1_login_crstate;
+    int do_ssh1_connection_crstate;
     int do_ssh2_transport_crstate;
     int do_ssh2_authconn_crstate;
 
@@ -655,8 +701,12 @@ struct ssh_tag {
     struct rdpkt1_state_tag rdpkt1_state;
     struct rdpkt2_state_tag rdpkt2_state;
 
-    void (*protocol) (Ssh ssh, unsigned char *in, int inlen, int ispkt);
-    int (*s_rdpkt) (Ssh ssh, unsigned char **data, int *datalen);
+    /* ssh1 and ssh2 use this for different things, but both use it */
+    int protocol_initial_phase_done;
+
+    void (*protocol) (Ssh ssh, unsigned char *in, int inlen,
+		      struct Packet *pkt);
+    struct Packet *(*s_rdpkt) (Ssh ssh, unsigned char **data, int *datalen);
 
     /*
      * We maintain a full _copy_ of a Config structure here, not
@@ -671,6 +721,32 @@ struct ssh_tag {
      */
     void *agent_response;
     int agent_response_len;
+
+    /*
+     * Dispatch table for packet types that we may have to deal
+     * with at any time.
+     */
+    handler_fn_t packet_dispatch[256];
+
+    /*
+     * Queues of one-off handler functions for success/failure
+     * indications from a request.
+     */
+    struct queued_handler *qhead, *qtail;
+
+    /*
+     * This module deals with sending keepalives.
+     */
+    Pinger pinger;
+
+    /*
+     * Track incoming and outgoing data sizes and time, for
+     * size-based rekeys.
+     */
+    unsigned long incoming_data_size, outgoing_data_size, deferred_data_size;
+    unsigned long max_data_size;
+    int kex_in_progress;
+    long next_rekey, last_rekey;
 };
 
 #define logevent(s) logevent(ssh->frontend, s)
@@ -699,21 +775,21 @@ static void logeventf(Ssh ssh, const char *fmt, ...)
 
 /* Functions to leave bits out of the SSH packet log file. */
 
-static void dont_log_password(Ssh ssh, int blanktype)
+static void dont_log_password(Ssh ssh, struct Packet *pkt, int blanktype)
 {
     if (ssh->cfg.logomitpass)
-	ssh->pktout_logmode = blanktype;
+	pkt->logmode = blanktype;
 }
 
-static void dont_log_data(Ssh ssh, int blanktype)
+static void dont_log_data(Ssh ssh, struct Packet *pkt, int blanktype)
 {
     if (ssh->cfg.logomitdata)
-	ssh->pktout_logmode = blanktype;
+	pkt->logmode = blanktype;
 }
 
-static void end_log_omission(Ssh ssh)
+static void end_log_omission(Ssh ssh, struct Packet *pkt)
 {
-    ssh->pktout_logmode = PKTLOG_EMIT;
+    pkt->logmode = PKTLOG_EMIT;
 }
 
 static int ssh_channelcmp(void *av, void *bv)
@@ -763,6 +839,47 @@ static int ssh_rportcmp_ssh2(void *av, void *bv)
     return 0;
 }
 
+/*
+ * Special form of strcmp which can cope with NULL inputs. NULL is
+ * defined to sort before even the empty string.
+ */
+static int nullstrcmp(const char *a, const char *b)
+{
+    if (a == NULL && b == NULL)
+	return 0;
+    if (a == NULL)
+	return -1;
+    if (b == NULL)
+	return +1;
+    return strcmp(a, b);
+}
+
+static int ssh_portcmp(void *av, void *bv)
+{
+    struct ssh_portfwd *a = (struct ssh_portfwd *) av;
+    struct ssh_portfwd *b = (struct ssh_portfwd *) bv;
+    int i;
+    if (a->type > b->type)
+	return +1;
+    if (a->type < b->type)
+	return -1;
+    if ( (i = nullstrcmp(a->saddr, b->saddr)) != 0)
+	return i < 0 ? -1 : +1;
+    if (a->sport > b->sport)
+	return +1;
+    if (a->sport < b->sport)
+	return -1;
+    if (a->type != 'D') {
+	if ( (i = nullstrcmp(a->daddr, b->daddr)) != 0)
+	    return i < 0 ? -1 : +1;
+	if (a->dport > b->dport)
+	    return +1;
+	if (a->dport < b->dport)
+	    return -1;
+    }
+    return 0;
+}
+
 static int alloc_channel_id(Ssh ssh)
 {
     const unsigned CHANNEL_NUMBER_OFFSET = 256;
@@ -829,54 +946,69 @@ static void c_write_str(Ssh ssh, const char *buf)
     c_write(ssh, buf, strlen(buf));
 }
 
+static void ssh_free_packet(struct Packet *pkt)
+{
+    sfree(pkt->data);
+    sfree(pkt);
+}
+static struct Packet *ssh_new_packet(void)
+{
+    struct Packet *pkt = snew(struct Packet);
+
+    pkt->data = NULL;
+    pkt->maxlen = 0;
+    pkt->logmode = PKTLOG_EMIT;
+    pkt->nblanks = 0;
+    pkt->blanks = NULL;
+
+    return pkt;
+}
+
 /*
  * Collect incoming data in the incoming packet buffer.
  * Decipher and verify the packet when it is completely read.
  * Drop SSH1_MSG_DEBUG and SSH1_MSG_IGNORE packets.
  * Update the *data and *datalen variables.
- * Return the additional nr of bytes needed, or 0 when
- * a complete packet is available.
+ * Return a Packet structure when a packet is completed.
  */
-static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
+static struct Packet *ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 {
     struct rdpkt1_state_tag *st = &ssh->rdpkt1_state;
 
     crBegin(ssh->ssh1_rdpkt_crstate);
 
-  next_packet:
+    st->pktin = ssh_new_packet();
 
-    ssh->pktin.type = 0;
-    ssh->pktin.length = 0;
+    st->pktin->type = 0;
+    st->pktin->length = 0;
 
     for (st->i = st->len = 0; st->i < 4; st->i++) {
 	while ((*datalen) == 0)
-	    crReturn(4 - st->i);
+	    crReturn(NULL);
 	st->len = (st->len << 8) + **data;
 	(*data)++, (*datalen)--;
     }
 
     st->pad = 8 - (st->len % 8);
     st->biglen = st->len + st->pad;
-    ssh->pktin.length = st->len - 5;
+    st->pktin->length = st->len - 5;
 
     if (st->biglen < 0) {
         bombout(("Extremely large packet length from server suggests"
 		 " data stream corruption"));
-        crStop(0);
+	ssh_free_packet(st->pktin);
+        crStop(NULL);
     }
 
-    if (ssh->pktin.maxlen < st->biglen) {
-	ssh->pktin.maxlen = st->biglen;
-	ssh->pktin.data = sresize(ssh->pktin.data, st->biglen + APIEXTRA,
-				  unsigned char);
-    }
+    st->pktin->maxlen = st->biglen;
+    st->pktin->data = snewn(st->biglen + APIEXTRA, unsigned char);
 
     st->to_read = st->biglen;
-    st->p = ssh->pktin.data;
+    st->p = st->pktin->data;
     while (st->to_read > 0) {
 	st->chunk = st->to_read;
 	while ((*datalen) == 0)
-	    crReturn(st->to_read);
+	    crReturn(NULL);
 	if (st->chunk > (*datalen))
 	    st->chunk = (*datalen);
 	memcpy(st->p, *data, st->chunk);
@@ -886,49 +1018,52 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 	st->to_read -= st->chunk;
     }
 
-    if (ssh->cipher && detect_attack(ssh->crcda_ctx, ssh->pktin.data,
+    if (ssh->cipher && detect_attack(ssh->crcda_ctx, st->pktin->data,
 				     st->biglen, NULL)) {
         bombout(("Network attack (CRC compensation) detected!"));
-        crStop(0);
+	ssh_free_packet(st->pktin);
+        crStop(NULL);
     }
 
     if (ssh->cipher)
-	ssh->cipher->decrypt(ssh->v1_cipher_ctx, ssh->pktin.data, st->biglen);
+	ssh->cipher->decrypt(ssh->v1_cipher_ctx, st->pktin->data, st->biglen);
 
-    st->realcrc = crc32_compute(ssh->pktin.data, st->biglen - 4);
-    st->gotcrc = GET_32BIT(ssh->pktin.data + st->biglen - 4);
+    st->realcrc = crc32_compute(st->pktin->data, st->biglen - 4);
+    st->gotcrc = GET_32BIT(st->pktin->data + st->biglen - 4);
     if (st->gotcrc != st->realcrc) {
 	bombout(("Incorrect CRC received on packet"));
-	crStop(0);
+	ssh_free_packet(st->pktin);
+	crStop(NULL);
     }
 
-    ssh->pktin.body = ssh->pktin.data + st->pad + 1;
-    ssh->pktin.savedpos = 0;
+    st->pktin->body = st->pktin->data + st->pad + 1;
+    st->pktin->savedpos = 0;
 
     if (ssh->v1_compressing) {
 	unsigned char *decompblk;
 	int decomplen;
 	if (!zlib_decompress_block(ssh->sc_comp_ctx,
-				   ssh->pktin.body - 1, ssh->pktin.length + 1,
+				   st->pktin->body - 1, st->pktin->length + 1,
 				   &decompblk, &decomplen)) {
 	    bombout(("Zlib decompression encountered invalid data"));
-	    crStop(0);
+	    ssh_free_packet(st->pktin);
+	    crStop(NULL);
 	}
 
-	if (ssh->pktin.maxlen < st->pad + decomplen) {
-	    ssh->pktin.maxlen = st->pad + decomplen;
-	    ssh->pktin.data = sresize(ssh->pktin.data,
-				      ssh->pktin.maxlen + APIEXTRA,
+	if (st->pktin->maxlen < st->pad + decomplen) {
+	    st->pktin->maxlen = st->pad + decomplen;
+	    st->pktin->data = sresize(st->pktin->data,
+				      st->pktin->maxlen + APIEXTRA,
 				      unsigned char);
-	    ssh->pktin.body = ssh->pktin.data + st->pad + 1;
+	    st->pktin->body = st->pktin->data + st->pad + 1;
 	}
 
-	memcpy(ssh->pktin.body - 1, decompblk, decomplen);
+	memcpy(st->pktin->body - 1, decompblk, decomplen);
 	sfree(decompblk);
-	ssh->pktin.length = decomplen - 1;
+	st->pktin->length = decomplen - 1;
     }
 
-    ssh->pktin.type = ssh->pktin.body[-1];
+    st->pktin->type = st->pktin->body[-1];
 
     /*
      * Log incoming packet, possibly omitting sensitive fields.
@@ -939,82 +1074,39 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 	if (ssh->cfg.logomitdata) {
 	    int do_blank = FALSE, blank_prefix = 0;
 	    /* "Session data" packets - omit the data field */
-	    if ((ssh->pktin.type == SSH1_SMSG_STDOUT_DATA) ||
-		(ssh->pktin.type == SSH1_SMSG_STDERR_DATA)) {
+	    if ((st->pktin->type == SSH1_SMSG_STDOUT_DATA) ||
+		(st->pktin->type == SSH1_SMSG_STDERR_DATA)) {
 		do_blank = TRUE; blank_prefix = 0;
-	    } else if (ssh->pktin.type == SSH1_MSG_CHANNEL_DATA) {
+	    } else if (st->pktin->type == SSH1_MSG_CHANNEL_DATA) {
 		do_blank = TRUE; blank_prefix = 4;
 	    }
 	    if (do_blank) {
 		blank.offset = blank_prefix;
-		blank.len = ssh->pktin.length;
+		blank.len = st->pktin->length;
 		blank.type = PKTLOG_OMIT;
 		nblanks = 1;
 	    }
 	}
 	log_packet(ssh->logctx,
-		   PKT_INCOMING, ssh->pktin.type,
-		   ssh1_pkt_type(ssh->pktin.type),
-		   ssh->pktin.body, ssh->pktin.length,
+		   PKT_INCOMING, st->pktin->type,
+		   ssh1_pkt_type(st->pktin->type),
+		   st->pktin->body, st->pktin->length,
 		   nblanks, &blank);
     }
 
-    if (ssh->pktin.type == SSH1_SMSG_STDOUT_DATA ||
-	ssh->pktin.type == SSH1_SMSG_STDERR_DATA ||
-	ssh->pktin.type == SSH1_MSG_DEBUG ||
-	ssh->pktin.type == SSH1_SMSG_AUTH_TIS_CHALLENGE ||
-	ssh->pktin.type == SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
-	long stringlen = GET_32BIT(ssh->pktin.body);
-	if (stringlen + 4 != ssh->pktin.length) {
-	    bombout(("Received data packet with bogus string length"));
-	    crStop(0);
-	}
-    }
-
-    if (ssh->pktin.type == SSH1_MSG_DEBUG) {
-	/* log debug message */
-	char buf[512];
-	int stringlen = GET_32BIT(ssh->pktin.body);
-	strcpy(buf, "Remote debug message: ");
-	if (stringlen > 480)
-	    stringlen = 480;
-	memcpy(buf + 8, ssh->pktin.body + 4, stringlen);
-	buf[8 + stringlen] = '\0';
-	logevent(buf);
-	goto next_packet;
-    } else if (ssh->pktin.type == SSH1_MSG_IGNORE) {
-	/* do nothing */
-	goto next_packet;
-    }
-
-    if (ssh->pktin.type == SSH1_MSG_DISCONNECT) {
-	/* log reason code in disconnect message */
-	char buf[256];
-	unsigned msglen = GET_32BIT(ssh->pktin.body);
-	unsigned nowlen;
-	strcpy(buf, "Remote sent disconnect: ");
-	nowlen = strlen(buf);
-	if (msglen > sizeof(buf) - nowlen - 1)
-	    msglen = sizeof(buf) - nowlen - 1;
-	memcpy(buf + nowlen, ssh->pktin.body + 4, msglen);
-	buf[nowlen + msglen] = '\0';
-	/* logevent(buf); (this is now done within the bombout macro) */
-	bombout(("Server sent disconnect message:\n\"%s\"", buf+nowlen));
-	crStop(0);
-    }
-
-    crFinish(0);
+    crFinish(st->pktin);
 }
 
-static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
+static struct Packet *ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 {
     struct rdpkt2_state_tag *st = &ssh->rdpkt2_state;
 
     crBegin(ssh->ssh2_rdpkt_crstate);
 
-  next_packet:
-    ssh->pktin.type = 0;
-    ssh->pktin.length = 0;
+    st->pktin = ssh_new_packet();
+
+    st->pktin->type = 0;
+    st->pktin->length = 0;
     if (ssh->sccipher)
 	st->cipherblk = ssh->sccipher->blksize;
     else
@@ -1022,11 +1114,7 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     if (st->cipherblk < 8)
 	st->cipherblk = 8;
 
-    if (ssh->pktin.maxlen < st->cipherblk) {
-	ssh->pktin.maxlen = st->cipherblk;
-	ssh->pktin.data = sresize(ssh->pktin.data, st->cipherblk + APIEXTRA,
-				  unsigned char);
-    }
+    st->pktin->data = snewn(st->cipherblk + APIEXTRA, unsigned char);
 
     /*
      * Acquire and decrypt the first block of the packet. This will
@@ -1034,20 +1122,20 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      */
     for (st->i = st->len = 0; st->i < st->cipherblk; st->i++) {
 	while ((*datalen) == 0)
-	    crReturn(st->cipherblk - st->i);
-	ssh->pktin.data[st->i] = *(*data)++;
+	    crReturn(NULL);
+	st->pktin->data[st->i] = *(*data)++;
 	(*datalen)--;
     }
 
     if (ssh->sccipher)
 	ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
-			       ssh->pktin.data, st->cipherblk);
+			       st->pktin->data, st->cipherblk);
 
     /*
      * Now get the length and padding figures.
      */
-    st->len = GET_32BIT(ssh->pktin.data);
-    st->pad = ssh->pktin.data[4];
+    st->len = GET_32BIT(st->pktin->data);
+    st->pad = st->pktin->data[4];
 
     /*
      * _Completely_ silly lengths should be stomped on before they
@@ -1055,7 +1143,8 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      */
     if (st->len < 0 || st->pad < 0 || st->len + st->pad < 0) {
 	bombout(("Incoming packet was garbled on decryption"));
-	crStop(0);
+	ssh_free_packet(st->pktin);
+	crStop(NULL);
     }
 
     /*
@@ -1063,7 +1152,7 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      */
     st->payload = st->len - st->pad - 1;
 
-    ssh->pktin.length = st->payload + 5;
+    st->pktin->length = st->payload + 5;
 
     /*
      * So now we can work out the total packet length.
@@ -1072,14 +1161,12 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     st->maclen = ssh->scmac ? ssh->scmac->len : 0;
 
     /*
-     * Adjust memory allocation if packet is too big.
+     * Allocate memory for the rest of the packet.
      */
-    if (ssh->pktin.maxlen < st->packetlen + st->maclen) {
-	ssh->pktin.maxlen = st->packetlen + st->maclen;
-	ssh->pktin.data = sresize(ssh->pktin.data,
-				  ssh->pktin.maxlen + APIEXTRA,
-				  unsigned char);
-    }
+    st->pktin->maxlen = st->packetlen + st->maclen;
+    st->pktin->data = sresize(st->pktin->data,
+			      st->pktin->maxlen + APIEXTRA,
+			      unsigned char);
 
     /*
      * Read and decrypt the remainder of the packet.
@@ -1087,26 +1174,30 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     for (st->i = st->cipherblk; st->i < st->packetlen + st->maclen;
 	 st->i++) {
 	while ((*datalen) == 0)
-	    crReturn(st->packetlen + st->maclen - st->i);
-	ssh->pktin.data[st->i] = *(*data)++;
+	    crReturn(NULL);
+	st->pktin->data[st->i] = *(*data)++;
 	(*datalen)--;
     }
     /* Decrypt everything _except_ the MAC. */
     if (ssh->sccipher)
 	ssh->sccipher->decrypt(ssh->sc_cipher_ctx,
-			       ssh->pktin.data + st->cipherblk,
+			       st->pktin->data + st->cipherblk,
 			       st->packetlen - st->cipherblk);
 
+    st->pktin->encrypted_len = st->packetlen;
+
     /*
      * Check the MAC.
      */
     if (ssh->scmac
-	&& !ssh->scmac->verify(ssh->sc_mac_ctx, ssh->pktin.data, st->len + 4,
+	&& !ssh->scmac->verify(ssh->sc_mac_ctx, st->pktin->data, st->len + 4,
 			       st->incoming_sequence)) {
 	bombout(("Incorrect MAC received on packet"));
-	crStop(0);
+	ssh_free_packet(st->pktin);
+	crStop(NULL);
     }
-    st->incoming_sequence++;	       /* whether or not we MACed */
+
+    st->pktin->sequence = st->incoming_sequence++;
 
     /*
      * Decompress packet payload.
@@ -1116,23 +1207,23 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 	int newlen;
 	if (ssh->sccomp &&
 	    ssh->sccomp->decompress(ssh->sc_comp_ctx,
-				    ssh->pktin.data + 5, ssh->pktin.length - 5,
+				    st->pktin->data + 5, st->pktin->length - 5,
 				    &newpayload, &newlen)) {
-	    if (ssh->pktin.maxlen < newlen + 5) {
-		ssh->pktin.maxlen = newlen + 5;
-		ssh->pktin.data = sresize(ssh->pktin.data,
-					  ssh->pktin.maxlen + APIEXTRA,
+	    if (st->pktin->maxlen < newlen + 5) {
+		st->pktin->maxlen = newlen + 5;
+		st->pktin->data = sresize(st->pktin->data,
+					  st->pktin->maxlen + APIEXTRA,
 					  unsigned char);
 	    }
-	    ssh->pktin.length = 5 + newlen;
-	    memcpy(ssh->pktin.data + 5, newpayload, newlen);
+	    st->pktin->length = 5 + newlen;
+	    memcpy(st->pktin->data + 5, newpayload, newlen);
 	    sfree(newpayload);
 	}
     }
 
-    ssh->pktin.savedpos = 6;
-    ssh->pktin.body = ssh->pktin.data;
-    ssh->pktin.type = ssh->pktin.data[5];
+    st->pktin->savedpos = 6;
+    st->pktin->body = st->pktin->data;
+    st->pktin->type = st->pktin->data[5];
 
     /*
      * Log incoming packet, possibly omitting sensitive fields.
@@ -1143,128 +1234,28 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 	if (ssh->cfg.logomitdata) {
 	    int do_blank = FALSE, blank_prefix = 0;
 	    /* "Session data" packets - omit the data field */
-	    if (ssh->pktin.type == SSH2_MSG_CHANNEL_DATA) {
+	    if (st->pktin->type == SSH2_MSG_CHANNEL_DATA) {
 		do_blank = TRUE; blank_prefix = 4;
-	    } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA) {
+	    } else if (st->pktin->type == SSH2_MSG_CHANNEL_EXTENDED_DATA) {
 		do_blank = TRUE; blank_prefix = 8;
 	    }
 	    if (do_blank) {
 		blank.offset = blank_prefix;
-		blank.len = (ssh->pktin.length-6) - blank_prefix;
+		blank.len = (st->pktin->length-6) - blank_prefix;
 		blank.type = PKTLOG_OMIT;
 		nblanks = 1;
 	    }
 	}
-	log_packet(ssh->logctx, PKT_INCOMING, ssh->pktin.type,
-		   ssh2_pkt_type(ssh->pkt_ctx, ssh->pktin.type),
-		   ssh->pktin.data+6, ssh->pktin.length-6,
+	log_packet(ssh->logctx, PKT_INCOMING, st->pktin->type,
+		   ssh2_pkt_type(ssh->pkt_ctx, st->pktin->type),
+		   st->pktin->data+6, st->pktin->length-6,
 		   nblanks, &blank);
     }
 
-    switch (ssh->pktin.type) {
-        /*
-         * These packets we must handle instantly.
-         */
-      case SSH2_MSG_DISCONNECT:
-        {
-            /* log reason code in disconnect message */
-            char *buf;
-	    int nowlen;
-            int reason = GET_32BIT(ssh->pktin.data + 6);
-            unsigned msglen = GET_32BIT(ssh->pktin.data + 10);
-
-            if (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) {
-                buf = dupprintf("Received disconnect message (%s)",
-				ssh2_disconnect_reasons[reason]);
-            } else {
-                buf = dupprintf("Received disconnect message (unknown"
-				" type %d)", reason);
-            }
-            logevent(buf);
-	    sfree(buf);
-            buf = dupprintf("Disconnection message text: %n%.*s",
-			    &nowlen, msglen, ssh->pktin.data + 14);
-            logevent(buf);
-            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);
-            crStop(0);
-        }
-        break;
-      case SSH2_MSG_IGNORE:
-	goto next_packet;
-      case SSH2_MSG_DEBUG:
-	{
-	    /* log the debug message */
-	    char buf[512];
-	    /* int display = ssh->pktin.body[6]; */
-	    int stringlen = GET_32BIT(ssh->pktin.data+7);
-	    int prefix;
-	    strcpy(buf, "Remote debug message: ");
-	    prefix = strlen(buf);
-	    if (stringlen > (int)(sizeof(buf)-prefix-1))
-		stringlen = sizeof(buf)-prefix-1;
-	    memcpy(buf + prefix, ssh->pktin.data + 11, stringlen);
-	    buf[prefix + stringlen] = '\0';
-	    logevent(buf);
-	}
-        goto next_packet;              /* FIXME: print the debug message */
-
-        /*
-         * These packets we need do nothing about here.
-         */
-      case SSH2_MSG_UNIMPLEMENTED:
-      case SSH2_MSG_SERVICE_REQUEST:
-      case SSH2_MSG_SERVICE_ACCEPT:
-      case SSH2_MSG_KEXINIT:
-      case SSH2_MSG_NEWKEYS:
-      case SSH2_MSG_KEXDH_INIT:
-      case SSH2_MSG_KEXDH_REPLY:
-      /* case SSH2_MSG_KEX_DH_GEX_REQUEST: duplicate case value */
-      /* case SSH2_MSG_KEX_DH_GEX_GROUP: duplicate case value */
-      case SSH2_MSG_KEX_DH_GEX_INIT:
-      case SSH2_MSG_KEX_DH_GEX_REPLY:
-      case SSH2_MSG_USERAUTH_REQUEST:
-      case SSH2_MSG_USERAUTH_FAILURE:
-      case SSH2_MSG_USERAUTH_SUCCESS:
-      case SSH2_MSG_USERAUTH_BANNER:
-      case SSH2_MSG_USERAUTH_PK_OK:
-      /* case SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ: duplicate case value */
-      /* case SSH2_MSG_USERAUTH_INFO_REQUEST: duplicate case value */
-      case SSH2_MSG_USERAUTH_INFO_RESPONSE:
-      case SSH2_MSG_GLOBAL_REQUEST:
-      case SSH2_MSG_REQUEST_SUCCESS:
-      case SSH2_MSG_REQUEST_FAILURE:
-      case SSH2_MSG_CHANNEL_OPEN:
-      case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
-      case SSH2_MSG_CHANNEL_OPEN_FAILURE:
-      case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
-      case SSH2_MSG_CHANNEL_DATA:
-      case SSH2_MSG_CHANNEL_EXTENDED_DATA:
-      case SSH2_MSG_CHANNEL_EOF:
-      case SSH2_MSG_CHANNEL_CLOSE:
-      case SSH2_MSG_CHANNEL_REQUEST:
-      case SSH2_MSG_CHANNEL_SUCCESS:
-      case SSH2_MSG_CHANNEL_FAILURE:
-        break;
-
-        /*
-         * For anything else we send SSH2_MSG_UNIMPLEMENTED.
-         */
-      default:
-	ssh2_pkt_init(ssh, SSH2_MSG_UNIMPLEMENTED);
-	ssh2_pkt_adduint32(ssh, st->incoming_sequence - 1);
-	ssh2_pkt_send(ssh);
-        break;
-    }
-
-    crFinish(0);
+    crFinish(st->pktin);
 }
 
-static void ssh1_pktout_size(Ssh ssh, int len)
+static void ssh1_pktout_size(struct Packet *pkt, int len)
 {
     int pad, biglen;
 
@@ -1272,32 +1263,26 @@ static void ssh1_pktout_size(Ssh ssh, int len)
     pad = 8 - (len % 8);
     biglen = len + pad;
 
-    ssh->pktout.length = len - 5;
-    if (ssh->pktout.maxlen < biglen) {
-	ssh->pktout.maxlen = biglen;
-#ifdef MSCRYPTOAPI
-	/* Allocate enough buffer space for extra block
-	 * for MS CryptEncrypt() */
-	ssh->pktout.data = sresize(ssh->pktout.data, biglen + 12,
-				   unsigned char);
-#else
-	ssh->pktout.data = sresize(ssh->pktout.data, biglen + 4,
-				   unsigned char);
-#endif
+    pkt->length = len - 5;
+    if (pkt->maxlen < biglen) {
+	pkt->maxlen = biglen;
+	pkt->data = sresize(pkt->data, biglen + 4 + APIEXTRA, unsigned char);
     }
-    ssh->pktout.body = ssh->pktout.data + 4 + pad + 1;
+    pkt->body = pkt->data + 4 + pad + 1;
 }
 
-static void s_wrpkt_start(Ssh ssh, int type, int len)
+static struct Packet *s_wrpkt_start(int type, int len)
 {
-    ssh1_pktout_size(ssh, len);
-    ssh->pktout.type = type;
+    struct Packet *pkt = ssh_new_packet();
+    ssh1_pktout_size(pkt, len);
+    pkt->type = type;
     /* Initialise log omission state */
-    ssh->pktout_nblanks = 0;
-    ssh->pktout_blanks = NULL;
+    pkt->nblanks = 0;
+    pkt->blanks = NULL;
+    return pkt;
 }
 
-static int s_wrpkt_prepare(Ssh ssh)
+static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt)
 {
     int pad, biglen, i;
     unsigned long crc;
@@ -1312,75 +1297,77 @@ static int s_wrpkt_prepare(Ssh ssh)
 #endif
     int len;
 
-    ssh->pktout.body[-1] = ssh->pktout.type;
+    pkt->body[-1] = pkt->type;
 
     if (ssh->logctx)
-	log_packet(ssh->logctx, PKT_OUTGOING, ssh->pktout.type,
-		   ssh1_pkt_type(ssh->pktout.type),
-		   ssh->pktout.body, ssh->pktout.length,
-		   ssh->pktout_nblanks, ssh->pktout_blanks);
-    sfree(ssh->pktout_blanks); ssh->pktout_blanks = NULL;
-    ssh->pktout_nblanks = 0;
+	log_packet(ssh->logctx, PKT_OUTGOING, pkt->type,
+		   ssh1_pkt_type(pkt->type),
+		   pkt->body, pkt->length,
+		   pkt->nblanks, pkt->blanks);
+    sfree(pkt->blanks); pkt->blanks = NULL;
+    pkt->nblanks = 0;
 
     if (ssh->v1_compressing) {
 	unsigned char *compblk;
 	int complen;
 	zlib_compress_block(ssh->cs_comp_ctx,
-			    ssh->pktout.body - 1, ssh->pktout.length + 1,
+			    pkt->body - 1, pkt->length + 1,
 			    &compblk, &complen);
-	ssh1_pktout_size(ssh, complen - 1);
-	memcpy(ssh->pktout.body - 1, compblk, complen);
+	ssh1_pktout_size(pkt, complen - 1);
+	memcpy(pkt->body - 1, compblk, complen);
 	sfree(compblk);
     }
 
-    len = ssh->pktout.length + 5;	       /* type and CRC */
+    len = pkt->length + 5;	       /* type and CRC */
     pad = 8 - (len % 8);
     biglen = len + pad;
 
     for (i = 0; i < pad; i++)
-	ssh->pktout.data[i + 4] = random_byte();
-    crc = crc32_compute(ssh->pktout.data + 4, biglen - 4);
-    PUT_32BIT(ssh->pktout.data + biglen, crc);
-    PUT_32BIT(ssh->pktout.data, len);
+	pkt->data[i + 4] = random_byte();
+    crc = crc32_compute(pkt->data + 4, biglen - 4);
+    PUT_32BIT(pkt->data + biglen, crc);
+    PUT_32BIT(pkt->data, len);
 
     if (ssh->cipher)
-	ssh->cipher->encrypt(ssh->v1_cipher_ctx, ssh->pktout.data + 4, biglen);
+	ssh->cipher->encrypt(ssh->v1_cipher_ctx, pkt->data + 4, biglen);
 
     return biglen + 4;
 }
 
-static void s_wrpkt(Ssh ssh)
+static void s_wrpkt(Ssh ssh, struct Packet *pkt)
 {
     int len, backlog;
-    len = s_wrpkt_prepare(ssh);
-    backlog = sk_write(ssh->s, (char *)ssh->pktout.data, len);
+    len = s_wrpkt_prepare(ssh, pkt);
+    backlog = sk_write(ssh->s, (char *)pkt->data, len);
     if (backlog > SSH_MAX_BACKLOG)
 	ssh_throttle_all(ssh, 1, backlog);
 }
 
-static void s_wrpkt_defer(Ssh ssh)
+static void s_wrpkt_defer(Ssh ssh, struct Packet *pkt)
 {
     int len;
-    len = s_wrpkt_prepare(ssh);
+    len = s_wrpkt_prepare(ssh, pkt);
     if (ssh->deferred_len + len > ssh->deferred_size) {
 	ssh->deferred_size = ssh->deferred_len + len + 128;
 	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);
+    memcpy(ssh->deferred_send_data + ssh->deferred_len, pkt->data, len);
     ssh->deferred_len += len;
 }
 
 /*
  * Construct a packet with the specified contents.
  */
-static void construct_packet(Ssh ssh, int pkttype, va_list ap1, va_list ap2)
+static struct Packet *construct_packet(Ssh ssh, int pkttype,
+				       va_list ap1, va_list ap2)
 {
     unsigned char *p, *argp, argchar;
     unsigned long argint;
     int pktlen, argtype, arglen;
     Bignum bn;
+    struct Packet *pkt;
 
     pktlen = 0;
     while ((argtype = va_arg(ap1, int)) != PKT_END) {
@@ -1417,11 +1404,11 @@ static void construct_packet(Ssh ssh, int pkttype, va_list ap1, va_list ap2)
 	}
     }
 
-    s_wrpkt_start(ssh, pkttype, pktlen);
-    p = ssh->pktout.body;
+    pkt = s_wrpkt_start(pkttype, pktlen);
+    p = pkt->body;
 
     while ((argtype = va_arg(ap2, int)) != PKT_END) {
-	int offset = p - ssh->pktout.body, len = 0;
+	int offset = p - pkt->body, len = 0;
 	switch (argtype) {
 	  /* Actual fields in the packet */
 	  case PKT_INT:
@@ -1453,46 +1440,54 @@ static void construct_packet(Ssh ssh, int pkttype, va_list ap1, va_list ap2)
 	    break;
 	  /* Tokens for modifications to packet logging */
 	  case PKTT_PASSWORD:
-	    dont_log_password(ssh, PKTLOG_BLANK);
+	    dont_log_password(ssh, pkt, PKTLOG_BLANK);
 	    break;
 	  case PKTT_DATA:
-	    dont_log_data(ssh, PKTLOG_OMIT);
+	    dont_log_data(ssh, pkt, PKTLOG_OMIT);
 	    break;
 	  case PKTT_OTHER:
-	    end_log_omission(ssh);
+	    end_log_omission(ssh, pkt);
 	    break;
 	}
 	p += len;
 	/* Deal with logfile omission, if required. */
-	if (len && (ssh->pktout_logmode != PKTLOG_EMIT)) {
-	    ssh->pktout_nblanks++;
-	    ssh->pktout_blanks = sresize(ssh->pktout_blanks,
-					 ssh->pktout_nblanks,
-					 struct logblank_t);
-	    ssh->pktout_blanks[ssh->pktout_nblanks-1].offset = offset;
-	    ssh->pktout_blanks[ssh->pktout_nblanks-1].len    = len;
-	    ssh->pktout_blanks[ssh->pktout_nblanks-1].type   =
-		ssh->pktout_logmode;
+	if (len && (pkt->logmode != PKTLOG_EMIT)) {
+	    pkt->nblanks++;
+	    pkt->blanks = sresize(pkt->blanks, pkt->nblanks,
+				  struct logblank_t);
+	    pkt->blanks[pkt->nblanks-1].offset = offset;
+	    pkt->blanks[pkt->nblanks-1].len    = len;
+	    pkt->blanks[pkt->nblanks-1].type   = pkt->logmode;
 	}
     }
+
+    return pkt;
 }
 
 static void send_packet(Ssh ssh, int pkttype, ...)
 {
+    struct Packet *pkt;
     va_list ap1, ap2;
     va_start(ap1, pkttype);
     va_start(ap2, pkttype);
-    construct_packet(ssh, pkttype, ap1, ap2);
-    s_wrpkt(ssh);
+    pkt = construct_packet(ssh, pkttype, ap1, ap2);
+    va_end(ap2);
+    va_end(ap1);
+    s_wrpkt(ssh, pkt);
+    ssh_free_packet(pkt);
 }
 
 static void defer_packet(Ssh ssh, int pkttype, ...)
 {
+    struct Packet *pkt;
     va_list ap1, ap2;
     va_start(ap1, pkttype);
     va_start(ap2, pkttype);
-    construct_packet(ssh, pkttype, ap1, ap2);
-    s_wrpkt_defer(ssh);
+    pkt = construct_packet(ssh, pkttype, ap1, ap2);
+    va_end(ap2);
+    va_end(ap1);
+    s_wrpkt_defer(ssh, pkt);
+    ssh_free_packet(pkt);
 }
 
 static int ssh_versioncmp(char *a, char *b)
@@ -1538,73 +1533,66 @@ static void sha_uint32(SHA_State * s, unsigned i)
 /*
  * SSH2 packet construction functions.
  */
-static void ssh2_pkt_ensure(Ssh ssh, int length)
-{
-    if (ssh->pktout.maxlen < length) {
-	ssh->pktout.maxlen = length + 256;
-	ssh->pktout.data = sresize(ssh->pktout.data,
-				   ssh->pktout.maxlen + APIEXTRA,
-				   unsigned char);
-	if (!ssh->pktout.data)
-	    fatalbox("Out of memory");
+static void ssh2_pkt_ensure(struct Packet *pkt, int length)
+{
+    if (pkt->maxlen < length) {
+	pkt->maxlen = length + 256;
+	pkt->data = sresize(pkt->data, pkt->maxlen + APIEXTRA, unsigned char);
     }
 }
-static void ssh2_pkt_adddata(Ssh ssh, void *data, int len)
+static void ssh2_pkt_adddata(struct Packet *pkt, void *data, int len)
 {
-    if (ssh->pktout_logmode != PKTLOG_EMIT) {
-	ssh->pktout_nblanks++;
-	ssh->pktout_blanks = sresize(ssh->pktout_blanks, ssh->pktout_nblanks,
-				     struct logblank_t);
-	ssh->pktout_blanks[ssh->pktout_nblanks-1].offset =
-	    ssh->pktout.length - 6;
-	ssh->pktout_blanks[ssh->pktout_nblanks-1].len = len;
-	ssh->pktout_blanks[ssh->pktout_nblanks-1].type = ssh->pktout_logmode;
-    }
-    ssh->pktout.length += len;
-    ssh2_pkt_ensure(ssh, ssh->pktout.length);
-    memcpy(ssh->pktout.data + ssh->pktout.length - len, data, len);
+    if (pkt->logmode != PKTLOG_EMIT) {
+	pkt->nblanks++;
+	pkt->blanks = sresize(pkt->blanks, pkt->nblanks, struct logblank_t);
+	pkt->blanks[pkt->nblanks-1].offset = pkt->length - 6;
+	pkt->blanks[pkt->nblanks-1].len = len;
+	pkt->blanks[pkt->nblanks-1].type = pkt->logmode;
+    }
+    pkt->length += len;
+    ssh2_pkt_ensure(pkt, pkt->length);
+    memcpy(pkt->data + pkt->length - len, data, len);
 }
-static void ssh2_pkt_addbyte(Ssh ssh, unsigned char byte)
+static void ssh2_pkt_addbyte(struct Packet *pkt, unsigned char byte)
 {
-    ssh2_pkt_adddata(ssh, &byte, 1);
+    ssh2_pkt_adddata(pkt, &byte, 1);
 }
-static void ssh2_pkt_init(Ssh ssh, int pkt_type)
+static struct Packet *ssh2_pkt_init(int pkt_type)
 {
-    ssh->pktout.length = 5;
-    ssh->pktout_nblanks = 0; ssh->pktout_blanks = NULL;
-    ssh2_pkt_addbyte(ssh, (unsigned char) pkt_type);
+    struct Packet *pkt = ssh_new_packet();
+    pkt->length = 5;
+    ssh2_pkt_addbyte(pkt, (unsigned char) pkt_type);
+    return pkt;
 }
-static void ssh2_pkt_addbool(Ssh ssh, unsigned char value)
+static void ssh2_pkt_addbool(struct Packet *pkt, unsigned char value)
 {
-    ssh2_pkt_adddata(ssh, &value, 1);
+    ssh2_pkt_adddata(pkt, &value, 1);
 }
-static void ssh2_pkt_adduint32(Ssh ssh, unsigned long value)
+static void ssh2_pkt_adduint32(struct Packet *pkt, unsigned long value)
 {
     unsigned char x[4];
     PUT_32BIT(x, value);
-    ssh2_pkt_adddata(ssh, x, 4);
+    ssh2_pkt_adddata(pkt, x, 4);
 }
-static void ssh2_pkt_addstring_start(Ssh ssh)
+static void ssh2_pkt_addstring_start(struct Packet *pkt)
 {
-    ssh2_pkt_adduint32(ssh, 0);
-    ssh->pktout.savedpos = ssh->pktout.length;
+    ssh2_pkt_adduint32(pkt, 0);
+    pkt->savedpos = pkt->length;
 }
-static void ssh2_pkt_addstring_str(Ssh ssh, char *data)
+static void ssh2_pkt_addstring_str(struct Packet *pkt, char *data)
 {
-    ssh2_pkt_adddata(ssh, data, strlen(data));
-    PUT_32BIT(ssh->pktout.data + ssh->pktout.savedpos - 4,
-	      ssh->pktout.length - ssh->pktout.savedpos);
+    ssh2_pkt_adddata(pkt, data, strlen(data));
+    PUT_32BIT(pkt->data + pkt->savedpos - 4, pkt->length - pkt->savedpos);
 }
-static void ssh2_pkt_addstring_data(Ssh ssh, char *data, int len)
+static void ssh2_pkt_addstring_data(struct Packet *pkt, char *data, int len)
 {
-    ssh2_pkt_adddata(ssh, data, len);
-    PUT_32BIT(ssh->pktout.data + ssh->pktout.savedpos - 4,
-	      ssh->pktout.length - ssh->pktout.savedpos);
+    ssh2_pkt_adddata(pkt, data, len);
+    PUT_32BIT(pkt->data + pkt->savedpos - 4, pkt->length - pkt->savedpos);
 }
-static void ssh2_pkt_addstring(Ssh ssh, char *data)
+static void ssh2_pkt_addstring(struct Packet *pkt, char *data)
 {
-    ssh2_pkt_addstring_start(ssh);
-    ssh2_pkt_addstring_str(ssh, data);
+    ssh2_pkt_addstring_start(pkt);
+    ssh2_pkt_addstring_str(pkt, data);
 }
 static unsigned char *ssh2_mpint_fmt(Bignum b, int *len)
 {
@@ -1623,32 +1611,32 @@ static unsigned char *ssh2_mpint_fmt(Bignum b, int *len)
     *len = n + 1 - i;
     return p;
 }
-static void ssh2_pkt_addmp(Ssh ssh, Bignum b)
+static void ssh2_pkt_addmp(struct Packet *pkt, Bignum b)
 {
     unsigned char *p;
     int len;
     p = ssh2_mpint_fmt(b, &len);
-    ssh2_pkt_addstring_start(ssh);
-    ssh2_pkt_addstring_data(ssh, (char *)p, len);
+    ssh2_pkt_addstring_start(pkt);
+    ssh2_pkt_addstring_data(pkt, (char *)p, len);
     sfree(p);
 }
 
 /*
  * Construct an SSH2 final-form packet: compress it, encrypt it,
  * put the MAC on it. Final packet, ready to be sent, is stored in
- * ssh->pktout.data. Total length is returned.
+ * pkt->data. Total length is returned.
  */
-static int ssh2_pkt_construct(Ssh ssh)
+static int ssh2_pkt_construct(Ssh ssh, struct Packet *pkt)
 {
     int cipherblk, maclen, padding, i;
 
     if (ssh->logctx)
-	log_packet(ssh->logctx, PKT_OUTGOING, ssh->pktout.data[5],
-		   ssh2_pkt_type(ssh->pkt_ctx, ssh->pktout.data[5]),
-		   ssh->pktout.data + 6, ssh->pktout.length - 6,
-		   ssh->pktout_nblanks, ssh->pktout_blanks);
-    sfree(ssh->pktout_blanks); ssh->pktout_blanks = NULL;
-    ssh->pktout_nblanks = 0;
+	log_packet(ssh->logctx, PKT_OUTGOING, pkt->data[5],
+		   ssh2_pkt_type(ssh->pkt_ctx, pkt->data[5]),
+		   pkt->data + 6, pkt->length - 6,
+		   pkt->nblanks, pkt->blanks);
+    sfree(pkt->blanks); pkt->blanks = NULL;
+    pkt->nblanks = 0;
 
     /*
      * Compress packet payload.
@@ -1657,11 +1645,11 @@ static int ssh2_pkt_construct(Ssh ssh)
 	unsigned char *newpayload;
 	int newlen;
 	if (ssh->cscomp &&
-	    ssh->cscomp->compress(ssh->cs_comp_ctx, ssh->pktout.data + 5,
-				  ssh->pktout.length - 5,
+	    ssh->cscomp->compress(ssh->cs_comp_ctx, pkt->data + 5,
+				  pkt->length - 5,
 				  &newpayload, &newlen)) {
-	    ssh->pktout.length = 5;
-	    ssh2_pkt_adddata(ssh, newpayload, newlen);
+	    pkt->length = 5;
+	    ssh2_pkt_adddata(pkt, newpayload, newlen);
 	    sfree(newpayload);
 	}
     }
@@ -1674,67 +1662,149 @@ static int ssh2_pkt_construct(Ssh ssh)
     cipherblk = cipherblk < 8 ? 8 : cipherblk;	/* or 8 if blksize < 8 */
     padding = 4;
     padding +=
-	(cipherblk - (ssh->pktout.length + padding) % cipherblk) % cipherblk;
+	(cipherblk - (pkt->length + padding) % cipherblk) % cipherblk;
     maclen = ssh->csmac ? ssh->csmac->len : 0;
-    ssh2_pkt_ensure(ssh, ssh->pktout.length + padding + maclen);
-    ssh->pktout.data[4] = padding;
+    ssh2_pkt_ensure(pkt, pkt->length + padding + maclen);
+    pkt->data[4] = padding;
     for (i = 0; i < padding; i++)
-	ssh->pktout.data[ssh->pktout.length + i] = random_byte();
-    PUT_32BIT(ssh->pktout.data, ssh->pktout.length + padding - 4);
+	pkt->data[pkt->length + i] = random_byte();
+    PUT_32BIT(pkt->data, pkt->length + padding - 4);
     if (ssh->csmac)
-	ssh->csmac->generate(ssh->cs_mac_ctx, ssh->pktout.data,
-			     ssh->pktout.length + padding,
+	ssh->csmac->generate(ssh->cs_mac_ctx, pkt->data,
+			     pkt->length + padding,
 			     ssh->v2_outgoing_sequence);
     ssh->v2_outgoing_sequence++;       /* whether or not we MACed */
 
     if (ssh->cscipher)
 	ssh->cscipher->encrypt(ssh->cs_cipher_ctx,
-			       ssh->pktout.data, ssh->pktout.length + padding);
+			       pkt->data, pkt->length + padding);
 
-    /* Ready-to-send packet starts at ssh->pktout.data. We return length. */
-    return ssh->pktout.length + padding + maclen;
+    pkt->encrypted_len = pkt->length + padding;
+
+    /* Ready-to-send packet starts at pkt->data. We return length. */
+    return pkt->length + padding + maclen;
 }
 
 /*
- * Construct and send an SSH2 packet immediately.
+ * Routines called from the main SSH code to send packets. There
+ * are quite a few of these, because we have two separate
+ * mechanisms for delaying the sending of packets:
+ * 
+ *  - In order to send an IGNORE message and a password message in
+ *    a single fixed-length blob, we require the ability to
+ *    concatenate the encrypted forms of those two packets _into_ a
+ *    single blob and then pass it to our <network.h> transport
+ *    layer in one go. Hence, there's a deferment mechanism which
+ *    works after packet encryption.
+ * 
+ *  - In order to avoid sending any connection-layer messages
+ *    during repeat key exchange, we have to queue up any such
+ *    outgoing messages _before_ they are encrypted (and in
+ *    particular before they're allocated sequence numbers), and
+ *    then send them once we've finished.
+ * 
+ * I call these mechanisms `defer' and `queue' respectively, so as
+ * to distinguish them reasonably easily.
+ * 
+ * The functions send_noqueue() and defer_noqueue() free the packet
+ * structure they are passed. Every outgoing packet goes through
+ * precisely one of these functions in its life; packets passed to
+ * ssh2_pkt_send() or ssh2_pkt_defer() either go straight to one of
+ * these or get queued, and then when the queue is later emptied
+ * the packets are all passed to defer_noqueue().
+ */
+
+/*
+ * Send an SSH2 packet immediately, without queuing or deferring.
  */
-static void ssh2_pkt_send(Ssh ssh)
+static void ssh2_pkt_send_noqueue(Ssh ssh, struct Packet *pkt)
 {
     int len;
     int backlog;
-    len = ssh2_pkt_construct(ssh);
-    backlog = sk_write(ssh->s, (char *)ssh->pktout.data, len);
+    len = ssh2_pkt_construct(ssh, pkt);
+    backlog = sk_write(ssh->s, (char *)pkt->data, len);
     if (backlog > SSH_MAX_BACKLOG)
 	ssh_throttle_all(ssh, 1, backlog);
+
+    ssh->outgoing_data_size += pkt->encrypted_len;
+    if (!ssh->kex_in_progress &&
+	ssh->max_data_size != 0 &&
+	ssh->outgoing_data_size > ssh->max_data_size)
+	do_ssh2_transport(ssh, "Initiating key re-exchange "
+			  "(too much data sent)", -1, NULL);
+
+    ssh_free_packet(pkt);
 }
 
 /*
- * Construct an SSH2 packet and add it to a deferred data block.
- * Useful for sending multiple packets in a single sk_write() call,
- * to prevent a traffic-analysing listener from being able to work
- * out the length of any particular packet (such as the password
- * packet).
- * 
- * Note that because SSH2 sequence-numbers its packets, this can
- * NOT be used as an m4-style `defer' allowing packets to be
- * constructed in one order and sent in another.
+ * Defer an SSH2 packet.
  */
-static void ssh2_pkt_defer(Ssh ssh)
+static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt)
 {
-    int len = ssh2_pkt_construct(ssh);
+    int len = ssh2_pkt_construct(ssh, pkt);
     if (ssh->deferred_len + len > ssh->deferred_size) {
 	ssh->deferred_size = ssh->deferred_len + len + 128;
 	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);
+    memcpy(ssh->deferred_send_data + ssh->deferred_len, pkt->data, len);
     ssh->deferred_len += len;
+    ssh->deferred_data_size += pkt->encrypted_len;
+    ssh_free_packet(pkt);
+}
+
+/*
+ * Queue an SSH2 packet.
+ */
+static void ssh2_pkt_queue(Ssh ssh, struct Packet *pkt)
+{
+    assert(ssh->queueing);
+
+    if (ssh->queuelen >= ssh->queuesize) {
+	ssh->queuesize = ssh->queuelen + 32;
+	ssh->queue = sresize(ssh->queue, ssh->queuesize, struct Packet *);
+    }
+
+    ssh->queue[ssh->queuelen++] = pkt;
+}
+
+/*
+ * Either queue or send a packet, depending on whether queueing is
+ * set.
+ */
+static void ssh2_pkt_send(Ssh ssh, struct Packet *pkt)
+{
+    if (ssh->queueing)
+	ssh2_pkt_queue(ssh, pkt);
+    else
+	ssh2_pkt_send_noqueue(ssh, pkt);
+}
+
+/*
+ * Either queue or defer a packet, depending on whether queueing is
+ * set.
+ */
+static void ssh2_pkt_defer(Ssh ssh, struct Packet *pkt)
+{
+    if (ssh->queueing)
+	ssh2_pkt_queue(ssh, pkt);
+    else
+	ssh2_pkt_defer_noqueue(ssh, pkt);
 }
 
 /*
  * Send the whole deferred data block constructed by
  * ssh2_pkt_defer() or SSH1's defer_packet().
+ * 
+ * The expected use of the defer mechanism is that you call
+ * ssh2_pkt_defer() a few times, then call ssh_pkt_defersend(). If
+ * not currently queueing, this simply sets up deferred_send_data
+ * and then sends it. If we _are_ currently queueing, the calls to
+ * ssh2_pkt_defer() put the deferred packets on to the queue
+ * instead, and therefore ssh_pkt_defersend() has no deferred data
+ * to send. Hence, there's no need to make it conditional on
+ * ssh->queueing.
  */
 static void ssh_pkt_defersend(Ssh ssh)
 {
@@ -1746,6 +1816,32 @@ static void ssh_pkt_defersend(Ssh ssh)
     ssh->deferred_send_data = NULL;
     if (backlog > SSH_MAX_BACKLOG)
 	ssh_throttle_all(ssh, 1, backlog);
+
+    ssh->outgoing_data_size += ssh->deferred_data_size;
+    if (!ssh->kex_in_progress &&
+	ssh->max_data_size != 0 &&
+	ssh->outgoing_data_size > ssh->max_data_size)
+	do_ssh2_transport(ssh, "Initiating key re-exchange "
+			  "(too much data sent)", -1, NULL);
+    ssh->deferred_data_size = 0;
+}
+
+/*
+ * Send all queued SSH2 packets. We send them by means of
+ * ssh2_pkt_defer_noqueue(), in case they included a pair of
+ * packets that needed to be lumped together.
+ */
+static void ssh2_pkt_queuesend(Ssh ssh)
+{
+    int i;
+
+    assert(!ssh->queueing);
+
+    for (i = 0; i < ssh->queuelen; i++)
+	ssh2_pkt_defer_noqueue(ssh, ssh->queue[i]);
+    ssh->queuelen = 0;
+
+    ssh_pkt_defersend(ssh);
 }
 
 #if 0
@@ -1774,92 +1870,90 @@ static void sha_mpint(SHA_State * s, Bignum b)
 /*
  * Packet decode functions for both SSH1 and SSH2.
  */
-static unsigned long ssh_pkt_getuint32(Ssh ssh)
+static unsigned long ssh_pkt_getuint32(struct Packet *pkt)
 {
     unsigned long value;
-    if (ssh->pktin.length - ssh->pktin.savedpos < 4)
+    if (pkt->length - pkt->savedpos < 4)
 	return 0;		       /* arrgh, no way to decline (FIXME?) */
-    value = GET_32BIT(ssh->pktin.body + ssh->pktin.savedpos);
-    ssh->pktin.savedpos += 4;
+    value = GET_32BIT(pkt->body + pkt->savedpos);
+    pkt->savedpos += 4;
     return value;
 }
-static int ssh2_pkt_getbool(Ssh ssh)
+static int ssh2_pkt_getbool(struct Packet *pkt)
 {
     unsigned long value;
-    if (ssh->pktin.length - ssh->pktin.savedpos < 1)
+    if (pkt->length - pkt->savedpos < 1)
 	return 0;		       /* arrgh, no way to decline (FIXME?) */
-    value = ssh->pktin.body[ssh->pktin.savedpos] != 0;
-    ssh->pktin.savedpos++;
+    value = pkt->body[pkt->savedpos] != 0;
+    pkt->savedpos++;
     return value;
 }
-static void ssh_pkt_getstring(Ssh ssh, char **p, int *length)
+static void ssh_pkt_getstring(struct Packet *pkt, char **p, int *length)
 {
     int len;
     *p = NULL;
     *length = 0;
-    if (ssh->pktin.length - ssh->pktin.savedpos < 4)
+    if (pkt->length - pkt->savedpos < 4)
 	return;
-    len = GET_32BIT(ssh->pktin.body + ssh->pktin.savedpos);
+    len = GET_32BIT(pkt->body + pkt->savedpos);
     if (len < 0)
 	return;
     *length = len;
-    ssh->pktin.savedpos += 4;
-    if (ssh->pktin.length - ssh->pktin.savedpos < *length)
+    pkt->savedpos += 4;
+    if (pkt->length - pkt->savedpos < *length)
 	return;
-    *p = (char *)(ssh->pktin.body + ssh->pktin.savedpos);
-    ssh->pktin.savedpos += *length;
+    *p = (char *)(pkt->body + pkt->savedpos);
+    pkt->savedpos += *length;
 }
-static void *ssh_pkt_getdata(Ssh ssh, int length)
+static void *ssh_pkt_getdata(struct Packet *pkt, int length)
 {
-    if (ssh->pktin.length - ssh->pktin.savedpos < length)
+    if (pkt->length - pkt->savedpos < length)
 	return NULL;
-    ssh->pktin.savedpos += length;
-    return ssh->pktin.body + (ssh->pktin.savedpos - length);
+    pkt->savedpos += length;
+    return pkt->body + (pkt->savedpos - length);
 }
-static int ssh1_pkt_getrsakey(Ssh ssh, struct RSAKey *key,
+static int ssh1_pkt_getrsakey(struct Packet *pkt, struct RSAKey *key,
 			      unsigned char **keystr)
 {
     int j;
 
-    j = makekey(ssh->pktin.body + ssh->pktin.savedpos,
-		ssh->pktin.length - ssh->pktin.savedpos,
+    j = makekey(pkt->body + pkt->savedpos,
+		pkt->length - pkt->savedpos,
 		key, keystr, 0);
 
     if (j < 0)
 	return FALSE;
     
-    ssh->pktin.savedpos += j;
-    assert(ssh->pktin.savedpos < ssh->pktin.length);
+    pkt->savedpos += j;
+    assert(pkt->savedpos < pkt->length);
 
     return TRUE;
 }
-static Bignum ssh1_pkt_getmp(Ssh ssh)
+static Bignum ssh1_pkt_getmp(struct Packet *pkt)
 {
     int j;
     Bignum b;
 
-    j = ssh1_read_bignum(ssh->pktin.body + ssh->pktin.savedpos,
-			 ssh->pktin.length - ssh->pktin.savedpos, &b);
+    j = ssh1_read_bignum(pkt->body + pkt->savedpos,
+			 pkt->length - pkt->savedpos, &b);
 
     if (j < 0)
 	return NULL;
 
-    ssh->pktin.savedpos += j;
+    pkt->savedpos += j;
     return b;
 }
-static Bignum ssh2_pkt_getmp(Ssh ssh)
+static Bignum ssh2_pkt_getmp(struct Packet *pkt)
 {
     char *p;
     int length;
     Bignum b;
 
-    ssh_pkt_getstring(ssh, &p, &length);
+    ssh_pkt_getstring(pkt, &p, &length);
     if (!p)
 	return NULL;
-    if (p[0] & 0x80) {
-	bombout(("internal error: Can't handle negative mpints"));
+    if (p[0] & 0x80)
 	return NULL;
-    }
     b = bignum_from_bytes((unsigned char *)p, length);
     return b;
 }
@@ -1871,7 +1965,8 @@ static Bignum ssh2_pkt_getmp(Ssh ssh)
  * fiddle with the signature packet if necessary for
  * BUG_SSH2_RSA_PADDING.
  */
-static void ssh2_add_sigblob(Ssh ssh, void *pkblob_v, int pkblob_len,
+static void ssh2_add_sigblob(Ssh ssh, struct Packet *pkt,
+			     void *pkblob_v, int pkblob_len,
 			     void *sigblob_v, int sigblob_len)
 {
     unsigned char *pkblob = (unsigned char *)pkblob_v;
@@ -1909,19 +2004,19 @@ static void ssh2_add_sigblob(Ssh ssh, void *pkblob_v, int pkblob_len,
 
 	if (len != siglen) {
 	    unsigned char newlen[4];
-	    ssh2_pkt_addstring_start(ssh);
-	    ssh2_pkt_addstring_data(ssh, (char *)sigblob, pos);
+	    ssh2_pkt_addstring_start(pkt);
+	    ssh2_pkt_addstring_data(pkt, (char *)sigblob, pos);
 	    /* dmemdump(sigblob, pos); */
 	    pos += 4;		       /* point to start of actual sig */
 	    PUT_32BIT(newlen, len);
-	    ssh2_pkt_addstring_data(ssh, (char *)newlen, 4);
+	    ssh2_pkt_addstring_data(pkt, (char *)newlen, 4);
 	    /* dmemdump(newlen, 4); */
 	    newlen[0] = 0;
 	    while (len-- > siglen) {
-		ssh2_pkt_addstring_data(ssh, (char *)newlen, 1);
+		ssh2_pkt_addstring_data(pkt, (char *)newlen, 1);
 		/* dmemdump(newlen, 1); */
 	    }
-	    ssh2_pkt_addstring_data(ssh, (char *)(sigblob+pos), siglen);
+	    ssh2_pkt_addstring_data(pkt, (char *)(sigblob+pos), siglen);
 	    /* dmemdump(sigblob+pos, siglen); */
 	    return;
 	}
@@ -1929,8 +2024,8 @@ static void ssh2_add_sigblob(Ssh ssh, void *pkblob_v, int pkblob_len,
 	/* Otherwise fall through and do it the easy way. */
     }
 
-    ssh2_pkt_addstring_start(ssh);
-    ssh2_pkt_addstring_data(ssh, (char *)sigblob, sigblob_len);
+    ssh2_pkt_addstring_start(pkt);
+    ssh2_pkt_addstring_data(pkt, (char *)sigblob, sigblob_len);
 }
 
 /*
@@ -2034,13 +2129,28 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 	ssh->remote_bugs |= BUG_SSH2_PK_SESSIONID;
 	logevent("We believe remote version has SSH2 public-key-session-ID bug");
     }
+}
 
-    if (ssh->cfg.sshbug_dhgex2 == FORCE_ON) {
-	/*
-	 * User specified the SSH2 DH GEX bug.
-	 */
-	ssh->remote_bugs |= BUG_SSH2_DH_GEX;
-	logevent("We believe remote version has SSH2 DH group exchange bug");
+/*
+ * The `software version' part of an SSH version string is required
+ * to contain no spaces or minus signs.
+ */
+static void ssh_fix_verstring(char *str)
+{
+    /* Eat "SSH-<protoversion>-". */
+    assert(*str == 'S'); str++;
+    assert(*str == 'S'); str++;
+    assert(*str == 'H'); str++;
+    assert(*str == '-'); str++;
+    while (*str && *str != '-') str++;
+    assert(*str == '-'); str++;
+
+    /* Convert minus signs and spaces in the remaining string into
+     * underscores. */
+    while (*str) {
+        if (*str == '-' || *str == ' ')
+            *str = '_';
+        str++;
     }
 }
 
@@ -2103,7 +2213,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     ssh->rdpkt2_state.incoming_sequence = 0;
 
     s->vstring[s->vslen] = 0;
-    s->vstring[strcspn(s->vstring, "\r\n")] = '\0';/* remove EOL chars */
+    s->vstring[strcspn(s->vstring, "\015\012")] = '\0';/* remove EOL chars */
     {
 	char *vlog;
 	vlog = snewn(20 + s->vslen, char);
@@ -2131,46 +2241,63 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
 	crStop(0);
     }
 
-    if (s->proto2 && (ssh->cfg.sshprot >= 2 || !s->proto1)) {
-	/*
-	 * Use v2 protocol.
-	 */
-	char verstring[80], vlog[100];
-	sprintf(verstring, "SSH-2.0-%s", sshver);
-	SHA_Init(&ssh->exhashbase);
-	/*
-	 * Hash our version string and their version string.
-	 */
-	sha_string(&ssh->exhashbase, verstring, strlen(verstring));
-	sha_string(&ssh->exhashbase, s->vstring, strcspn(s->vstring, "\r\n"));
-	sprintf(vlog, "We claim version: %s", verstring);
-	logevent(vlog);
-	strcat(verstring, "\012");
-	logevent("Using SSH protocol version 2");
-	sk_write(ssh->s, verstring, strlen(verstring));
-	ssh->protocol = ssh2_protocol;
-	ssh->version = 2;
-	ssh->s_rdpkt = ssh2_rdpkt;
-    } else {
-	/*
-	 * Use v1 protocol.
-	 */
-	char verstring[80], vlog[100];
-	sprintf(verstring, "SSH-%s-%s",
-		(ssh_versioncmp(s->version, "1.5") <= 0 ? s->version : "1.5"),
-		sshver);
-	sprintf(vlog, "We claim version: %s", verstring);
-	logevent(vlog);
-	strcat(verstring, "\012");
+    {
+        char *verstring;
+
+        if (s->proto2 && (ssh->cfg.sshprot >= 2 || !s->proto1)) {
+            /*
+             * Construct a v2 version string.
+             */
+            verstring = dupprintf("SSH-2.0-%s\015\012", sshver);
+            ssh->version = 2;
+        } else {
+            /*
+             * Construct a v1 version string.
+             */
+            verstring = dupprintf("SSH-%s-%s\012",
+                                  (ssh_versioncmp(s->version, "1.5") <= 0 ?
+                                   s->version : "1.5"),
+                                  sshver);
+            ssh->version = 1;
+        }
 
-	logevent("Using SSH protocol version 1");
+        ssh_fix_verstring(verstring);
+
+        if (ssh->version == 2) {
+            /*
+             * Hash our version string and their version string.
+             */
+            SHA_Init(&ssh->exhashbase);
+            sha_string(&ssh->exhashbase, verstring,
+                       strcspn(verstring, "\015\012"));
+            sha_string(&ssh->exhashbase, s->vstring,
+                       strcspn(s->vstring, "\015\012"));
+
+            /*
+             * Initialise SSHv2 protocol.
+             */
+            ssh->protocol = ssh2_protocol;
+            ssh2_protocol_setup(ssh);
+            ssh->s_rdpkt = ssh2_rdpkt;
+        } else {
+            /*
+             * Initialise SSHv1 protocol.
+             */
+            ssh->protocol = ssh1_protocol;
+            ssh1_protocol_setup(ssh);
+            ssh->s_rdpkt = ssh1_rdpkt;
+        }
+        logeventf(ssh, "We claim version: %.*s",
+                  strcspn(verstring, "\015\012"), verstring);
 	sk_write(ssh->s, verstring, strlen(verstring));
-	ssh->protocol = ssh1_protocol;
-	ssh->version = 1;
-	ssh->s_rdpkt = ssh1_rdpkt;
+        sfree(verstring);
     }
+
+    logeventf(ssh, "Using SSH protocol version %d", ssh->version);
+
     update_specials_menu(ssh->frontend);
     ssh->state = SSH_STATE_BEFORE_SIZE;
+    ssh->pinger = pinger_new(&ssh->cfg, &ssh_backend, ssh);
 
     sfree(s->vstring);
 
@@ -2208,15 +2335,13 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
 	crReturnV;
     while (1) {
 	while (datalen > 0) {
-	    if (ssh->s_rdpkt(ssh, &data, &datalen) == 0) {
-		if (ssh->state == SSH_STATE_CLOSED) {
-		    return;
-		}
-		ssh->protocol(ssh, NULL, 0, 1);
-		if (ssh->state == SSH_STATE_CLOSED) {
-		    return;
-		}
+	    struct Packet *pktin = ssh->s_rdpkt(ssh, &data, &datalen);
+	    if (pktin) {
+		ssh->protocol(ssh, NULL, 0, pktin);
+		ssh_free_packet(pktin);
 	    }
+	    if (ssh->state == SSH_STATE_CLOSED)
+		return;
 	}
 	crReturnV;
     }
@@ -2232,6 +2357,7 @@ static void ssh_do_close(Ssh ssh)
     if (ssh->s) {
         sk_close(ssh->s);
         ssh->s = NULL;
+	notify_remote_exit(ssh->frontend);
     }
     /*
      * Now we must shut down any port and X forwardings going
@@ -2343,6 +2469,7 @@ static const char *connect_to_host(Ssh ssh, char *host, int port,
 			    0, 1, nodelay, keepalive, (Plug) ssh, &ssh->cfg);
     if ((err = sk_socket_error(ssh->s)) != NULL) {
 	ssh->s = NULL;
+	notify_remote_exit(ssh->frontend);
 	return err;
     }
 
@@ -2479,9 +2606,9 @@ static void ssh_agent_callback(void *sshv, void *reply, int replylen)
     ssh->agent_response_len = replylen;
 
     if (ssh->version == 1)
-	do_ssh1_login(ssh, NULL, -1, 0);
+	do_ssh1_login(ssh, NULL, -1, NULL);
     else
-	do_ssh2_authconn(ssh, NULL, -1, 0);
+	do_ssh2_authconn(ssh, NULL, -1, NULL);
 }
 
 static void ssh_agentf_callback(void *cv, void *reply, int replylen)
@@ -2514,7 +2641,8 @@ static void ssh_agentf_callback(void *cv, void *reply, int replylen)
 /*
  * Handle the key exchange and user authentication phases.
  */
-static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
+static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
+			 struct Packet *pktin)
 {
     int i, j, ret;
     unsigned char cookie[8], *ptr;
@@ -2549,25 +2677,25 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     crBegin(ssh->do_ssh1_login_crstate);
 
-    if (!ispkt)
-	crWaitUntil(ispkt);
+    if (!pktin)
+	crWaitUntil(pktin);
 
-    if (ssh->pktin.type != SSH1_SMSG_PUBLIC_KEY) {
+    if (pktin->type != SSH1_SMSG_PUBLIC_KEY) {
 	bombout(("Public key packet not received"));
 	crStop(0);
     }
 
     logevent("Received public keys");
 
-    ptr = ssh_pkt_getdata(ssh, 8);
+    ptr = ssh_pkt_getdata(pktin, 8);
     if (!ptr) {
 	bombout(("SSH1 public key packet stopped before random cookie"));
 	crStop(0);
     }
     memcpy(cookie, ptr, 8);
 
-    if (!ssh1_pkt_getrsakey(ssh, &servkey, &s->keystr1) ||
-	!ssh1_pkt_getrsakey(ssh, &hostkey, &s->keystr2)) {	
+    if (!ssh1_pkt_getrsakey(pktin, &servkey, &s->keystr1) ||
+	!ssh1_pkt_getrsakey(pktin, &hostkey, &s->keystr2)) {	
 	bombout(("Failed to read SSH1 public keys from public key packet"));
 	crStop(0);
     }
@@ -2585,9 +2713,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	logevent(logmsg);
     }
 
-    ssh->v1_remote_protoflags = ssh_pkt_getuint32(ssh);
-    s->supported_ciphers_mask = ssh_pkt_getuint32(ssh);
-    s->supported_auths_mask = ssh_pkt_getuint32(ssh);
+    ssh->v1_remote_protoflags = ssh_pkt_getuint32(pktin);
+    s->supported_ciphers_mask = ssh_pkt_getuint32(pktin);
+    s->supported_auths_mask = ssh_pkt_getuint32(pktin);
 
     ssh->v1_local_protoflags =
 	ssh->v1_remote_protoflags & SSH1_PROTOFLAGS_SUPPORTED;
@@ -2696,7 +2824,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
 	/* Warn about chosen cipher if necessary. */
 	if (warn)
-	    askcipher(ssh->frontend, cipher_string, 0);
+	    askalg(ssh->frontend, "cipher", cipher_string);
     }
 
     switch (s->cipher_type) {
@@ -2748,9 +2876,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	sfree(hostkey.exponent);
 	hostkey.exponent = NULL;
     }
-    crWaitUntil(ispkt);
+    crWaitUntil(pktin);
 
-    if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
+    if (pktin->type != SSH1_SMSG_SUCCESS) {
 	bombout(("Encryption not successfully enabled"));
 	crStop(0);
     }
@@ -2759,7 +2887,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     fflush(stdout);
     {
-	if ((flags & FLAG_INTERACTIVE) && !*ssh->cfg.username) {
+	if (!*ssh->cfg.username) {
 	    if (ssh_get_line && !ssh_getline_pw_only) {
 		if (!ssh_get_line("login as: ",
 				  s->username, sizeof(s->username), FALSE)) {
@@ -2778,7 +2906,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
 		setup_userpass_input(ssh, s->username, sizeof(s->username), 1);
 		do {
-		    crWaitUntil(!ispkt);
+		    crWaitUntil(!pktin);
 		    ret = process_userpass_input(ssh, in, inlen);
 		} while (ret == 0);
 		if (ret < 0)
@@ -2803,7 +2931,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	}
     }
 
-    crWaitUntil(ispkt);
+    crWaitUntil(pktin);
 
     if ((ssh->remote_bugs & BUG_CHOKES_ON_RSA)) {
 	/* We must not attempt PK auth. Pretend we've already tried it. */
@@ -2820,7 +2948,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     } else
 	s->publickey_blob = NULL;
 
-    while (ssh->pktin.type == SSH1_SMSG_FAILURE) {
+    while (pktin->type == SSH1_SMSG_FAILURE) {
 	s->pwpkt_type = SSH1_CMSG_AUTH_PASSWORD;
 
 	if (agent_exists() && !s->tried_agent) {
@@ -2840,12 +2968,12 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			     ssh_agent_callback, ssh)) {
 		do {
 		    crReturn(0);
-		    if (ispkt) {
+		    if (pktin) {
 			bombout(("Unexpected data from server while waiting"
 				 " for agent response"));
 			crStop(0);
 		    }
-		} while (ispkt || inlen > 0);
+		} while (pktin || inlen > 0);
 		r = ssh->agent_response;
 		s->responselen = ssh->agent_response_len;
 	    }
@@ -2906,13 +3034,13 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		    }
 		    send_packet(ssh, SSH1_CMSG_AUTH_RSA,
 				PKT_BIGNUM, s->key.modulus, PKT_END);
-		    crWaitUntil(ispkt);
-		    if (ssh->pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
+		    crWaitUntil(pktin);
+		    if (pktin->type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
 			logevent("Key refused");
 			continue;
 		    }
 		    logevent("Received RSA challenge");
-		    if ((s->challenge = ssh1_pkt_getmp(ssh)) == NULL) {
+		    if ((s->challenge = ssh1_pkt_getmp(pktin)) == NULL) {
 			bombout(("Server's RSA challenge was badly formatted"));
 			crStop(0);
 		    }
@@ -2944,13 +3072,13 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			    sfree(agentreq);
 			    do {
 				crReturn(0);
-				if (ispkt) {
+				if (pktin) {
 				    bombout(("Unexpected data from server"
 					     " while waiting for agent"
 					     " response"));
 				    crStop(0);
 				}
-			    } while (ispkt || inlen > 0);
+			    } while (pktin || inlen > 0);
 			    vret = ssh->agent_response;
 			    retlen = ssh->agent_response_len;
 			} else
@@ -2963,8 +3091,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 					    PKT_DATA, ret + 5, 16,
 					    PKT_END);
 				sfree(ret);
-				crWaitUntil(ispkt);
-				if (ssh->pktin.type == SSH1_SMSG_SUCCESS) {
+				crWaitUntil(pktin);
+				if (pktin->type == SSH1_SMSG_SUCCESS) {
 				    logevent
 					("Pageant's response accepted");
 				    if (flags & FLAG_VERBOSE) {
@@ -3007,8 +3135,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    s->pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE;
 	    logevent("Requested TIS authentication");
 	    send_packet(ssh, SSH1_CMSG_AUTH_TIS, PKT_END);
-	    crWaitUntil(ispkt);
-	    if (ssh->pktin.type != SSH1_SMSG_AUTH_TIS_CHALLENGE) {
+	    crWaitUntil(pktin);
+	    if (pktin->type != SSH1_SMSG_AUTH_TIS_CHALLENGE) {
 		logevent("TIS authentication declined");
 		if (flags & FLAG_INTERACTIVE)
 		    c_write_str(ssh, "TIS authentication refused.\r\n");
@@ -3018,7 +3146,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		char *challenge;
 		int challengelen;
 
-		ssh_pkt_getstring(ssh, &challenge, &challengelen);
+		ssh_pkt_getstring(pktin, &challenge, &challengelen);
 		if (!challenge) {
 		    bombout(("TIS challenge packet was badly formed"));
 		    crStop(0);
@@ -3041,8 +3169,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    s->pwpkt_type = SSH1_CMSG_AUTH_CCARD_RESPONSE;
 	    logevent("Requested CryptoCard authentication");
 	    send_packet(ssh, SSH1_CMSG_AUTH_CCARD, PKT_END);
-	    crWaitUntil(ispkt);
-	    if (ssh->pktin.type != SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
+	    crWaitUntil(pktin);
+	    if (pktin->type != SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
 		logevent("CryptoCard authentication declined");
 		c_write_str(ssh, "CryptoCard authentication refused.\r\n");
 		s->ccard_auth_refused = 1;
@@ -3051,7 +3179,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		char *challenge;
 		int challengelen;
 
-		ssh_pkt_getstring(ssh, &challenge, &challengelen);
+		ssh_pkt_getstring(pktin, &challenge, &challengelen);
 		if (!challenge) {
 		    bombout(("CryptoCard challenge packet was badly formed"));
 		    crStop(0);
@@ -3128,7 +3256,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
 	    setup_userpass_input(ssh, s->password, sizeof(s->password), 0);
 	    do {
-		crWaitUntil(!ispkt);
+		crWaitUntil(!pktin);
 		ret = process_userpass_input(ssh, in, inlen);
 	    } while (ret == 0);
 	    if (ret < 0)
@@ -3169,12 +3297,12 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    send_packet(ssh, SSH1_CMSG_AUTH_RSA,
 			PKT_BIGNUM, s->key.modulus, PKT_END);
 
-	    crWaitUntil(ispkt);
-	    if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
+	    crWaitUntil(pktin);
+	    if (pktin->type == SSH1_SMSG_FAILURE) {
 		c_write_str(ssh, "Server refused our public key.\r\n");
 		continue;	       /* go and try password */
 	    }
-	    if (ssh->pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
+	    if (pktin->type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
 		bombout(("Bizarre response to offer of public key"));
 		crStop(0);
 	    }
@@ -3184,7 +3312,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		unsigned char buffer[32];
 		Bignum challenge, response;
 
-		if ((challenge = ssh1_pkt_getmp(ssh)) == NULL) {
+		if ((challenge = ssh1_pkt_getmp(pktin)) == NULL) {
 		    bombout(("Server's RSA challenge was badly formatted"));
 		    crStop(0);
 		}
@@ -3207,13 +3335,13 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		freebn(response);
 	    }
 
-	    crWaitUntil(ispkt);
-	    if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
+	    crWaitUntil(pktin);
+	    if (pktin->type == SSH1_SMSG_FAILURE) {
 		if (flags & FLAG_VERBOSE)
 		    c_write_str(ssh, "Failed to authenticate with"
 				" our public key.\r\n");
 		continue;	       /* go and try password */
-	    } else if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
+	    } else if (pktin->type != SSH1_SMSG_SUCCESS) {
 		bombout(("Bizarre response to RSA authentication response"));
 		crStop(0);
 	    }
@@ -3347,13 +3475,13 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	}
 	logevent("Sent password");
 	memset(s->password, 0, strlen(s->password));
-	crWaitUntil(ispkt);
-	if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
+	crWaitUntil(pktin);
+	if (pktin->type == SSH1_SMSG_FAILURE) {
 	    if (flags & FLAG_VERBOSE)
 		c_write_str(ssh, "Access denied\r\n");
 	    logevent("Authentication refused");
-	} else if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
-	    bombout(("Strange packet received, type %d", ssh->pktin.type));
+	} else if (pktin->type != SSH1_SMSG_SUCCESS) {
+	    bombout(("Strange packet received, type %d", pktin->type));
 	    crStop(0);
 	}
     }
@@ -3385,9 +3513,10 @@ void sshfwd_close(struct ssh_channel *c)
 		send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
 			    PKT_END);
 	    } else {
-		ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_CLOSE);
-		ssh2_pkt_adduint32(ssh, c->remoteid);
-		ssh2_pkt_send(ssh);
+		struct Packet *pktout;
+		pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
+		ssh2_pkt_adduint32(pktout, c->remoteid);
+		ssh2_pkt_send(ssh, pktout);
 	    }
 	}
 	c->closes = 1;		       /* sent MSG_CLOSE */
@@ -3450,219 +3579,766 @@ void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
     }
 }
 
-static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
+static void ssh_queueing_handler(Ssh ssh, struct Packet *pktin)
 {
-    crBegin(ssh->ssh1_protocol_crstate);
+    struct queued_handler *qh = ssh->qhead;
 
-    random_init();
+    assert(qh != NULL);
 
-    while (!do_ssh1_login(ssh, in, inlen, ispkt)) {
-	crReturnV;
+    assert(pktin->type == qh->msg1 || pktin->type == qh->msg2);
+
+    if (qh->msg1 > 0) {
+	assert(ssh->packet_dispatch[qh->msg1] == ssh_queueing_handler);
+	ssh->packet_dispatch[qh->msg1] = NULL;
+    }
+    if (qh->msg2 > 0) {
+	assert(ssh->packet_dispatch[qh->msg2] == ssh_queueing_handler);
+	ssh->packet_dispatch[qh->msg2] = NULL;
     }
-    if (ssh->state == SSH_STATE_CLOSED)
-	crReturnV;
 
-    if (ssh->cfg.agentfwd && agent_exists()) {
-	logevent("Requesting agent forwarding");
-	send_packet(ssh, SSH1_CMSG_AGENT_REQUEST_FORWARDING, PKT_END);
-	do {
-	    crReturnV;
-	} while (!ispkt);
-	if (ssh->pktin.type != SSH1_SMSG_SUCCESS
-	    && ssh->pktin.type != SSH1_SMSG_FAILURE) {
-	    bombout(("Protocol confusion"));
-	    crStopV;
-	} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
-	    logevent("Agent forwarding refused");
-	} else {
-	    logevent("Agent forwarding enabled");
-	    ssh->agentfwd_enabled = TRUE;
+    if (qh->next) {
+	ssh->qhead = qh->next;
+
+	if (ssh->qhead->msg1 > 0) {
+	    assert(ssh->packet_dispatch[ssh->qhead->msg1] == NULL);
+	    ssh->packet_dispatch[ssh->qhead->msg1] = ssh_queueing_handler;
+	}
+	if (ssh->qhead->msg2 > 0) {
+	    assert(ssh->packet_dispatch[ssh->qhead->msg2] == NULL);
+	    ssh->packet_dispatch[ssh->qhead->msg2] = ssh_queueing_handler;
 	}
+    } else {
+	ssh->qhead = ssh->qtail = NULL;
+	ssh->packet_dispatch[pktin->type] = NULL;
     }
 
-    if (ssh->cfg.x11_forward) {
-	char proto[20], data[64];
-	logevent("Requesting X11 forwarding");
-	ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
-				       data, sizeof(data), ssh->cfg.x11_auth);
-        x11_get_real_auth(ssh->x11auth, ssh->cfg.x11_display);
-	if (ssh->v1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
-	    send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
-			PKT_STR, proto, PKT_STR, data,
-			PKT_INT, x11_get_screen_number(ssh->cfg.x11_display),
-			PKT_END);
-	} else {
-	    send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
-			PKT_STR, proto, PKT_STR, data, PKT_END);
+    qh->handler(ssh, pktin, qh->ctx);
+
+    sfree(qh);
+}
+
+static void ssh_queue_handler(Ssh ssh, int msg1, int msg2,
+			      chandler_fn_t handler, void *ctx)
+{
+    struct queued_handler *qh;
+
+    qh = snew(struct queued_handler);
+    qh->msg1 = msg1;
+    qh->msg2 = msg2;
+    qh->handler = handler;
+    qh->ctx = ctx;
+    qh->next = NULL;
+
+    if (ssh->qtail == NULL) {
+	ssh->qhead = qh;
+
+	if (qh->msg1 > 0) {
+	    assert(ssh->packet_dispatch[qh->msg1] == NULL);
+	    ssh->packet_dispatch[qh->msg1] = ssh_queueing_handler;
 	}
-	do {
-	    crReturnV;
-	} while (!ispkt);
-	if (ssh->pktin.type != SSH1_SMSG_SUCCESS
-	    && ssh->pktin.type != SSH1_SMSG_FAILURE) {
-	    bombout(("Protocol confusion"));
-	    crStopV;
-	} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
-	    logevent("X11 forwarding refused");
-	} else {
-	    logevent("X11 forwarding enabled");
-	    ssh->X11_fwd_enabled = TRUE;
+	if (qh->msg2 > 0) {
+	    assert(ssh->packet_dispatch[qh->msg2] == NULL);
+	    ssh->packet_dispatch[qh->msg2] = ssh_queueing_handler;
 	}
+    } else {
+	ssh->qtail->next = qh;
     }
+    ssh->qtail = qh;
+}
 
-    {
-	char type;
-	int n;
-	int sport,dport,sserv,dserv;
-	char sports[256], dports[256], saddr[256], host[256];
-
-	ssh->rportfwds = newtree234(ssh_rportcmp_ssh1);
-        /* Add port forwardings. */
-	ssh->portfwd_strptr = ssh->cfg.portfwd;
-	while (*ssh->portfwd_strptr) {
-	    type = *ssh->portfwd_strptr++;
-	    saddr[0] = '\0';
-	    n = 0;
-	    while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != '\t') {
-		if (*ssh->portfwd_strptr == ':') {
-		    /*
-		     * We've seen a colon in the middle of the
-		     * source port number. This means that
-		     * everything we've seen until now is the
-		     * source _address_, so we'll move it into
-		     * saddr and start sports from the beginning
-		     * again.
-		     */
-		    ssh->portfwd_strptr++;
-		    sports[n] = '\0';
+static void ssh_rportfwd_succfail(Ssh ssh, struct Packet *pktin, void *ctx)
+{
+    struct ssh_rportfwd *rpf, *pf = (struct ssh_rportfwd *)ctx;
+
+    if (pktin->type == (ssh->version == 1 ? SSH1_SMSG_SUCCESS :
+			SSH2_MSG_REQUEST_SUCCESS)) {
+	logeventf(ssh, "Remote port forwarding from %s enabled",
+		  pf->sportdesc);
+    } else {
+	logeventf(ssh, "Remote port forwarding from %s refused",
+		  pf->sportdesc);
+
+	rpf = del234(ssh->rportfwds, pf);
+	assert(rpf == pf);
+	free_rportfwd(pf);
+    }
+}
+
+static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
+{
+    char type;
+    int n;
+    int sport,dport,sserv,dserv;
+    char sports[256], dports[256], saddr[256], host[256];
+    const char *portfwd_strptr;
+
+    portfwd_strptr = cfg->portfwd;
+
+    if (!ssh->portfwds) {
+	ssh->portfwds = newtree234(ssh_portcmp);
+    } else {
+	/*
+	 * Go through the existing port forwardings and tag them
+	 * with keep==FALSE. Any that we want to keep will be
+	 * re-enabled as we go through the configuration and find
+	 * out which bits are the same as they were before.
+	 */
+	struct ssh_portfwd *epf;
+	int i;
+	for (i = 0; (epf = index234(ssh->portfwds, i)) != NULL; i++)
+	    epf->keep = FALSE;
+    }
+
+    while (*portfwd_strptr) {
+	type = *portfwd_strptr++;
+	saddr[0] = '\0';
+	n = 0;
+	while (*portfwd_strptr && *portfwd_strptr != '\t') {
+	    if (*portfwd_strptr == ':') {
+		/*
+		 * We've seen a colon in the middle of the
+		 * source port number. This means that
+		 * everything we've seen until now is the
+		 * source _address_, so we'll move it into
+		 * saddr and start sports from the beginning
+		 * again.
+		 */
+		portfwd_strptr++;
+		sports[n] = '\0';
+		if (ssh->version == 1 && type == 'R') {
+		    logeventf(ssh, "SSH1 cannot handle remote source address "
+			      "spec \"%s\"; ignoring", sports);
+		} else
 		    strcpy(saddr, sports);
-		    n = 0;
-		}
-		if (n < 255) sports[n++] = *ssh->portfwd_strptr++;
-	    }
-	    sports[n] = 0;
-	    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++;
+	    }
+	    if (n < 255) sports[n++] = *portfwd_strptr++;
+	}
+	sports[n] = 0;
+	if (type != 'D') {
+	    if (*portfwd_strptr == '\t')
+		portfwd_strptr++;
+	    n = 0;
+	    while (*portfwd_strptr && *portfwd_strptr != ':') {
+		if (n < 255) host[n++] = *portfwd_strptr++;
+	    }
+	    host[n] = 0;
+	    if (*portfwd_strptr == ':')
+		portfwd_strptr++;
+	    n = 0;
+	    while (*portfwd_strptr) {
+		if (n < 255) dports[n++] = *portfwd_strptr++;
+	    }
+	    dports[n] = 0;
+	    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);
 		}
-		host[n] = 0;
-		if (*ssh->portfwd_strptr == ':')
-		    ssh->portfwd_strptr++;
-		n = 0;
-		while (*ssh->portfwd_strptr) {
-		    if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
+	    }
+	} else {
+	    while (*portfwd_strptr) portfwd_strptr++;
+	    dport = dserv = -1;
+	    portfwd_strptr++;	       /* eat the NUL and move to next one */
+	}
+	sport = atoi(sports);
+	sserv = 0;
+	if (sport == 0) {
+	    sserv = 1;
+	    sport = net_service_lookup(sports);
+	    if (!sport) {
+		logeventf(ssh, "Service lookup failed for source"
+			  " port \"%s\"", sports);
+	    }
+	}
+	if (sport && dport) {
+	    /* Set up a description of the source port. */
+	    struct ssh_portfwd *pfrec, *epfrec;
+	    char *sportdesc;
+	    sportdesc = dupprintf("%.*s%.*s%.*s%.*s%d%.*s",
+				  (int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
+				  (int)(*saddr?1:0), ":",
+				  (int)(sserv ? strlen(sports) : 0), sports,
+				  sserv, "(", sport, sserv, ")");
+
+	    pfrec = snew(struct ssh_portfwd);
+	    pfrec->type = type;
+	    pfrec->saddr = *saddr ? dupstr(saddr) : NULL;
+	    pfrec->sport = sport;
+	    pfrec->daddr = dupstr(host);
+	    pfrec->dport = dport;
+	    pfrec->local = NULL;
+	    pfrec->remote = NULL;
+
+	    epfrec = add234(ssh->portfwds, pfrec);
+	    if (epfrec != pfrec) {
+		/*
+		 * We already have a port forwarding with precisely
+		 * these parameters. Hence, no need to do anything;
+		 * simply tag the existing one as `keep'.
+		 */
+		epfrec->keep = TRUE;
+		free_portfwd(pfrec);
+	    } else if (type == 'L') {
+		/* Verbose description of the destination port */
+		char *dportdesc = dupprintf("%s:%.*s%.*s%d%.*s",
+					    host,
+					    (int)(dserv ? strlen(dports) : 0), dports,
+					    dserv, "(", dport, dserv, ")");
+		const char *err = pfd_addforward(host, dport,
+						 *saddr ? saddr : NULL,
+						 sport, ssh, &ssh->cfg,
+						 &pfrec->local);
+		if (err) {
+		    logeventf(ssh, "Local port %s forward to %s"
+			      " failed: %s", sportdesc, dportdesc, err);
+		} else {
+		    logeventf(ssh, "Local port %s forwarding to %s",
+			      sportdesc, dportdesc);
 		}
-		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);
-		    }
+		sfree(dportdesc);
+	    } else if (type == 'D') {
+		const char *err = pfd_addforward(NULL, -1,
+						 *saddr ? saddr : NULL,
+						 sport, ssh, &ssh->cfg,
+						 &pfrec->local);
+		if (err) {
+		    logeventf(ssh, "Local port %s SOCKS dynamic forward"
+			      " setup failed: %s", sportdesc, err);
+		} else {
+		    logeventf(ssh, "Local port %s doing SOCKS"
+			      " dynamic forwarding", sportdesc);
 		}
 	    } 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;
-	    if (sport == 0) {
-		sserv = 1;
-		sport = net_service_lookup(sports);
-		if (!sport) {
-		    logeventf(ssh, "Service lookup failed for source"
-			      " port \"%s\"", sports);
+		struct ssh_rportfwd *pf;
+
+		/*
+		 * Ensure the remote port forwardings tree exists.
+		 */
+		if (!ssh->rportfwds) {
+		    if (ssh->version == 1)
+			ssh->rportfwds = newtree234(ssh_rportcmp_ssh1);
+		    else
+			ssh->rportfwds = newtree234(ssh_rportcmp_ssh2);
 		}
-	    }
-	    if (sport && dport) {
-		/* Set up a description of the source port. */
-		char *sportdesc = dupprintf("%.*s%.*s%.*s%.*s%d%.*s",
-			(int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
-			(int)(*saddr?1:0), ":",
-			(int)(sserv ? strlen(sports) : 0), sports,
-			sserv, "(", sport, sserv, ")");
-		if (type == 'L') {
-		    /* Verbose description of the destination port */
-		    char *dportdesc = dupprintf("%s:%.*s%.*s%d%.*s",
-			    host,
-			    (int)(dserv ? strlen(dports) : 0), dports,
-			    dserv, "(", dport, dserv, ")");
-		    const char *err = pfd_addforward(host, dport,
-						     *saddr ? saddr : NULL,
-						     sport, ssh, &ssh->cfg);
-		    if (err) {
-			logeventf(ssh, "Local port %s forward to %s"
-				  " failed: %s", sportdesc, dportdesc, err);
-		    } else {
-			logeventf(ssh, "Local port %s forwarding to %s",
-				  sportdesc, dportdesc);
-		    }
-		    sfree(dportdesc);
-		} else if (type == 'D') {
-		    const char *err = pfd_addforward(NULL, -1,
-						     *saddr ? saddr : NULL,
-						     sport, ssh, &ssh->cfg);
-		    if (err) {
-			logeventf(ssh, "Local port %s SOCKS dynamic forward"
-				  " setup failed: %s", sportdesc, err);
-		    } else {
-			logeventf(ssh, "Local port %s doing SOCKS"
-				  " dynamic forwarding", sportdesc);
-		    }
+
+		pf = snew(struct ssh_rportfwd);
+		strcpy(pf->dhost, host);
+		pf->dport = dport;
+		pf->sport = sport;
+		if (add234(ssh->rportfwds, pf) != pf) {
+		    logeventf(ssh, "Duplicate remote port forwarding to %s:%d",
+			      host, dport);
+		    sfree(pf);
 		} else {
-		    struct ssh_rportfwd *pf;
-		    pf = snew(struct ssh_rportfwd);
-		    strcpy(pf->dhost, host);
-		    pf->dport = dport;
-		    if (*saddr) {
-			logeventf(ssh,
-				  "SSH1 cannot handle source address spec \"%s:%d\"; ignoring",
-				  saddr, sport);
-		    }
-		    if (add234(ssh->rportfwds, pf) != pf) {
-			logeventf(ssh, 
-				  "Duplicate remote port forwarding to %s:%d",
-				  host, dport);
-			sfree(pf);
-		    } else {
-			logeventf(ssh, "Requesting remote port %.*s%.*s%d%.*s"
-				  " forward to %s:%.*s%.*s%d%.*s",
-				  (int)(sserv ? strlen(sports) : 0), sports,
-				  sserv, "(", sport, sserv, ")",
-				  host,
-				  (int)(dserv ? strlen(dports) : 0), dports,
-				  dserv, "(", dport, dserv, ")");
+		    logeventf(ssh, "Requesting remote port %s"
+			      " forward to %s:%.*s%.*s%d%.*s",
+			      sportdesc, host,
+			      (int)(dserv ? strlen(dports) : 0), dports,
+			      dserv, "(", dport, dserv, ")");
+
+		    pf->sportdesc = sportdesc;
+		    sportdesc = NULL;
+		    pfrec->remote = pf;
+		    pf->pfrec = pfrec;
+
+		    if (ssh->version == 1) {
 			send_packet(ssh, SSH1_CMSG_PORT_FORWARD_REQUEST,
 				    PKT_INT, sport,
 				    PKT_STR, host,
 				    PKT_INT, dport,
 				    PKT_END);
-			do {
-			    crReturnV;
-			} while (!ispkt);
-			if (ssh->pktin.type != SSH1_SMSG_SUCCESS
-			    && ssh->pktin.type != SSH1_SMSG_FAILURE) {
-			    bombout(("Protocol confusion"));
-			    crStopV;
-			} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
-			    c_write_str(ssh, "Server refused port"
-					" forwarding\r\n");
+			ssh_queue_handler(ssh, SSH1_SMSG_SUCCESS,
+					  SSH1_SMSG_FAILURE,
+					  ssh_rportfwd_succfail, pf);
+		    } else {
+			struct Packet *pktout;
+			pktout = ssh2_pkt_init(SSH2_MSG_GLOBAL_REQUEST);
+			ssh2_pkt_addstring(pktout, "tcpip-forward");
+			ssh2_pkt_addbool(pktout, 1);/* want reply */
+			if (*saddr) {
+			    ssh2_pkt_addstring(pktout, saddr);
+			} else if (ssh->cfg.rport_acceptall) {
+			    ssh2_pkt_addstring(pktout, "0.0.0.0");
+			} else {
+			    ssh2_pkt_addstring(pktout, "127.0.0.1");
 			}
-			logevent("Remote port forwarding enabled");
+			ssh2_pkt_adduint32(pktout, sport);
+			ssh2_pkt_send(ssh, pktout);
+
+			ssh_queue_handler(ssh, SSH2_MSG_REQUEST_SUCCESS,
+					  SSH2_MSG_REQUEST_FAILURE,
+					  ssh_rportfwd_succfail, pf);
 		    }
 		}
-		sfree(sportdesc);
 	    }
+	    sfree(sportdesc);
+	}
+    }
+
+    /*
+     * Now go through and destroy any port forwardings which were
+     * not re-enabled.
+     */
+    {
+	struct ssh_portfwd *epf;
+	int i;
+	for (i = 0; (epf = index234(ssh->portfwds, i)) != NULL; i++)
+	    if (!epf->keep) {
+		char *message;
+
+		message = dupprintf("%s port forwarding from %s%s%d",
+				    epf->type == 'L' ? "local" :
+				    epf->type == 'R' ? "remote" : "dynamic",
+				    epf->saddr ? epf->saddr : "",
+				    epf->saddr ? ":" : "",
+				    epf->sport);
+
+		if (epf->type != 'D') {
+		    char *msg2 = dupprintf("%s to %s:%d", message,
+					   epf->daddr, epf->dport);
+		    sfree(message);
+		    message = msg2;
+		}
+
+		logeventf(ssh, "Cancelling %s", message);
+		sfree(message);
+
+		if (epf->remote) {
+		    struct ssh_rportfwd *rpf = epf->remote;
+		    struct Packet *pktout;
+
+		    /*
+		     * Cancel the port forwarding at the server
+		     * end.
+		     */
+		    if (ssh->version == 1) {
+			/*
+			 * We cannot cancel listening ports on the
+			 * server side in SSH1! There's no message
+			 * to support it. Instead, we simply remove
+			 * the rportfwd record from the local end
+			 * so that any connections the server tries
+			 * to make on it are rejected.
+			 */
+		    } else {
+			pktout = ssh2_pkt_init(SSH2_MSG_GLOBAL_REQUEST);
+			ssh2_pkt_addstring(pktout, "cancel-tcpip-forward");
+			ssh2_pkt_addbool(pktout, 0);/* _don't_ want reply */
+			if (epf->saddr) {
+			    ssh2_pkt_addstring(pktout, epf->saddr);
+			} else if (ssh->cfg.rport_acceptall) {
+			    ssh2_pkt_addstring(pktout, "0.0.0.0");
+			} else {
+			    ssh2_pkt_addstring(pktout, "127.0.0.1");
+			}
+			ssh2_pkt_adduint32(pktout, epf->sport);
+			ssh2_pkt_send(ssh, pktout);
+		    }
+
+		    del234(ssh->rportfwds, rpf);
+		    free_rportfwd(rpf);
+		} else if (epf->local) {
+		    pfd_terminate(epf->local);
+		}
+
+		delpos234(ssh->portfwds, i);
+		free_portfwd(epf);
+		i--;		       /* so we don't skip one in the list */
+	    }
+    }
+}
+
+static void ssh1_smsg_stdout_stderr_data(Ssh ssh, struct Packet *pktin)
+{
+    char *string;
+    int stringlen, bufsize;
+
+    ssh_pkt_getstring(pktin, &string, &stringlen);
+    if (string == NULL) {
+	bombout(("Incoming terminal data packet was badly formed"));
+	return;
+    }
+
+    bufsize = from_backend(ssh->frontend, pktin->type == SSH1_SMSG_STDERR_DATA,
+			   string, stringlen);
+    if (!ssh->v1_stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) {
+	ssh->v1_stdout_throttling = 1;
+	ssh1_throttle(ssh, +1);
+    }
+}
+
+static void ssh1_smsg_x11_open(Ssh ssh, struct Packet *pktin)
+{
+    /* Remote side is trying to open a channel to talk to our
+     * X-Server. Give them back a local channel number. */
+    struct ssh_channel *c;
+    int remoteid = ssh_pkt_getuint32(pktin);
+
+    logevent("Received X11 connect request");
+    /* Refuse if X11 forwarding is disabled. */
+    if (!ssh->X11_fwd_enabled) {
+	send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
+		    PKT_INT, remoteid, PKT_END);
+	logevent("Rejected X11 connect request");
+    } else {
+	c = snew(struct ssh_channel);
+	c->ssh = ssh;
+
+	if (x11_init(&c->u.x11.s, ssh->cfg.x11_display, c,
+		     ssh->x11auth, NULL, -1, &ssh->cfg) != NULL) {
+	    logevent("Opening X11 forward connection failed");
+	    sfree(c);
+	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
+			PKT_INT, remoteid, PKT_END);
+	} else {
+	    logevent
+		("Opening X11 forward connection succeeded");
+	    c->remoteid = remoteid;
+	    c->localid = alloc_channel_id(ssh);
+	    c->closes = 0;
+	    c->v.v1.throttling = 0;
+	    c->type = CHAN_X11;	/* identify channel type */
+	    add234(ssh->channels, c);
+	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
+			PKT_INT, c->remoteid, PKT_INT,
+			c->localid, PKT_END);
+	    logevent("Opened X11 forward channel");
+	}
+    }
+}
+
+static void ssh1_smsg_agent_open(Ssh ssh, struct Packet *pktin)
+{
+    /* Remote side is trying to open a channel to talk to our
+     * agent. Give them back a local channel number. */
+    struct ssh_channel *c;
+    int remoteid = ssh_pkt_getuint32(pktin);
+
+    /* Refuse if agent forwarding is disabled. */
+    if (!ssh->agentfwd_enabled) {
+	send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
+		    PKT_INT, remoteid, PKT_END);
+    } else {
+	c = snew(struct ssh_channel);
+	c->ssh = ssh;
+	c->remoteid = remoteid;
+	c->localid = alloc_channel_id(ssh);
+	c->closes = 0;
+	c->v.v1.throttling = 0;
+	c->type = CHAN_AGENT;	/* identify channel type */
+	c->u.a.lensofar = 0;
+	add234(ssh->channels, c);
+	send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
+		    PKT_INT, c->remoteid, PKT_INT, c->localid,
+		    PKT_END);
+    }
+}
+
+static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
+{
+    /* Remote side is trying to open a channel to talk to a
+     * forwarded port. Give them back a local channel number. */
+    struct ssh_channel *c;
+    struct ssh_rportfwd pf;
+    int remoteid;
+    int hostsize, port;
+    char *host, buf[1024];
+    const char *e;
+    c = snew(struct ssh_channel);
+    c->ssh = ssh;
+
+    remoteid = ssh_pkt_getuint32(pktin);
+    ssh_pkt_getstring(pktin, &host, &hostsize);
+    port = ssh_pkt_getuint32(pktin);
+
+    if (hostsize >= lenof(pf.dhost))
+	hostsize = lenof(pf.dhost)-1;
+    memcpy(pf.dhost, host, hostsize);
+    pf.dhost[hostsize] = '\0';
+    pf.dport = port;
+
+    if (find234(ssh->rportfwds, &pf, NULL) == NULL) {
+	sprintf(buf, "Rejected remote port open request for %s:%d",
+		pf.dhost, port);
+	logevent(buf);
+	send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
+		    PKT_INT, remoteid, PKT_END);
+    } else {
+	sprintf(buf, "Received remote port open request for %s:%d",
+		pf.dhost, port);
+	logevent(buf);
+	e = pfd_newconnect(&c->u.pfd.s, pf.dhost, port,
+			   c, &ssh->cfg);
+	if (e != NULL) {
+	    char buf[256];
+	    sprintf(buf, "Port open failed: %s", e);
+	    logevent(buf);
+	    sfree(c);
+	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
+			PKT_INT, remoteid, PKT_END);
+	} else {
+	    c->remoteid = remoteid;
+	    c->localid = alloc_channel_id(ssh);
+	    c->closes = 0;
+	    c->v.v1.throttling = 0;
+	    c->type = CHAN_SOCKDATA;	/* identify channel type */
+	    add234(ssh->channels, c);
+	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
+			PKT_INT, c->remoteid, PKT_INT,
+			c->localid, PKT_END);
+	    logevent("Forwarded port opened successfully");
+	}
+    }
+}
+
+static void ssh1_msg_channel_open_confirmation(Ssh ssh, struct Packet *pktin)
+{
+    unsigned int remoteid = ssh_pkt_getuint32(pktin);
+    unsigned int localid = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+
+    c = find234(ssh->channels, &remoteid, ssh_channelfind);
+    if (c && c->type == CHAN_SOCKDATA_DORMANT) {
+	c->remoteid = localid;
+	c->type = CHAN_SOCKDATA;
+	c->v.v1.throttling = 0;
+	pfd_confirm(c->u.pfd.s);
+    }
+
+    if (c && c->closes) {
+	/*
+	 * We have a pending close on this channel,
+	 * which we decided on before the server acked
+	 * the channel open. So now we know the
+	 * remoteid, we can close it again.
+	 */
+	send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE,
+		    PKT_INT, c->remoteid, PKT_END);
+    }
+}
+
+static void ssh1_msg_channel_open_failure(Ssh ssh, struct Packet *pktin)
+{
+    unsigned int remoteid = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+
+    c = find234(ssh->channels, &remoteid, ssh_channelfind);
+    if (c && c->type == CHAN_SOCKDATA_DORMANT) {
+	logevent("Forwarded connection refused by server");
+	pfd_close(c->u.pfd.s);
+	del234(ssh->channels, c);
+	sfree(c);
+    }
+}
+
+static void ssh1_msg_channel_close(Ssh ssh, struct Packet *pktin)
+{
+    /* Remote side closes a channel. */
+    unsigned i = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+    c = find234(ssh->channels, &i, ssh_channelfind);
+    if (c && ((int)c->remoteid) != -1) {
+	int closetype;
+	closetype =
+	    (pktin->type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2);
+
+	if ((c->closes == 0) && (c->type == CHAN_X11)) {
+	    logevent("Forwarded X11 connection terminated");
+	    assert(c->u.x11.s != NULL);
+	    x11_close(c->u.x11.s);
+	    c->u.x11.s = NULL;
+	}
+	if ((c->closes == 0) && (c->type == CHAN_SOCKDATA)) {
+	    logevent("Forwarded port closed");
+	    assert(c->u.pfd.s != NULL);
+	    pfd_close(c->u.pfd.s);
+	    c->u.pfd.s = NULL;
+	}
+
+	c->closes |= (closetype << 2);   /* seen this message */
+	if (!(c->closes & closetype)) {
+	    send_packet(ssh, pktin->type, PKT_INT, c->remoteid,
+			PKT_END);
+	    c->closes |= closetype;      /* sent it too */
+	}
+
+	if (c->closes == 15) {
+	    del234(ssh->channels, c);
+	    sfree(c);
+	}
+    } else {
+	bombout(("Received CHANNEL_CLOSE%s for %s channel %d\n",
+		 pktin->type == SSH1_MSG_CHANNEL_CLOSE ? "" :
+		 "_CONFIRMATION", c ? "half-open" : "nonexistent",
+		 i));
+    }
+}
+
+static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
+{
+    /* Data sent down one of our channels. */
+    int i = ssh_pkt_getuint32(pktin);
+    char *p;
+    unsigned int len;
+    struct ssh_channel *c;
+
+    ssh_pkt_getstring(pktin, &p, &len);
+
+    c = find234(ssh->channels, &i, ssh_channelfind);
+    if (c) {
+	int bufsize = 0;
+	switch (c->type) {
+	  case CHAN_X11:
+	    bufsize = x11_send(c->u.x11.s, p, len);
+	    break;
+	  case CHAN_SOCKDATA:
+	    bufsize = pfd_send(c->u.pfd.s, p, len);
+	    break;
+	  case CHAN_AGENT:
+	    /* Data for an agent message. Buffer it. */
+	    while (len > 0) {
+		if (c->u.a.lensofar < 4) {
+		    unsigned int l = min(4 - c->u.a.lensofar, len);
+		    memcpy(c->u.a.msglen + c->u.a.lensofar, p,
+			   l);
+		    p += l;
+		    len -= l;
+		    c->u.a.lensofar += l;
+		}
+		if (c->u.a.lensofar == 4) {
+		    c->u.a.totallen =
+			4 + GET_32BIT(c->u.a.msglen);
+		    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) {
+		    unsigned int l =
+			min(c->u.a.totallen - c->u.a.lensofar,
+			    len);
+		    memcpy(c->u.a.message + c->u.a.lensofar, p,
+			   l);
+		    p += l;
+		    len -= l;
+		    c->u.a.lensofar += l;
+		}
+		if (c->u.a.lensofar == c->u.a.totallen) {
+		    void *reply;
+		    int replylen;
+		    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;
+		}
+	    }
+	    bufsize = 0;   /* agent channels never back up */
+	    break;
+	}
+	if (!c->v.v1.throttling && bufsize > SSH1_BUFFER_LIMIT) {
+	    c->v.v1.throttling = 1;
+	    ssh1_throttle(ssh, +1);
 	}
     }
+}
+
+static void ssh1_smsg_exit_status(Ssh ssh, struct Packet *pktin)
+{
+    char buf[100];
+    ssh->exitcode = ssh_pkt_getuint32(pktin);
+    sprintf(buf, "Server sent command exit status %d",
+	    ssh->exitcode);
+    logevent(buf);
+    send_packet(ssh, SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
+    /*
+     * In case `helpful' firewalls or proxies tack
+     * extra human-readable text on the end of the
+     * session which we might mistake for another
+     * encrypted packet, we close the session once
+     * we've sent EXIT_CONFIRMATION.
+     */
+    ssh_closing((Plug)ssh, NULL, 0, 0);
+}
+
+static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
+			       struct Packet *pktin)
+{
+    crBegin(ssh->do_ssh1_connection_crstate);
+
+    ssh->packet_dispatch[SSH1_SMSG_STDOUT_DATA] = 
+	ssh->packet_dispatch[SSH1_SMSG_STDERR_DATA] =
+	ssh1_smsg_stdout_stderr_data;
+
+    ssh->packet_dispatch[SSH1_MSG_CHANNEL_OPEN_CONFIRMATION] =
+	ssh1_msg_channel_open_confirmation;
+    ssh->packet_dispatch[SSH1_MSG_CHANNEL_OPEN_FAILURE] =
+	ssh1_msg_channel_open_failure;
+    ssh->packet_dispatch[SSH1_MSG_CHANNEL_CLOSE] =
+	ssh->packet_dispatch[SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION] =
+	ssh1_msg_channel_close;
+    ssh->packet_dispatch[SSH1_MSG_CHANNEL_DATA] = ssh1_msg_channel_data;
+    ssh->packet_dispatch[SSH1_SMSG_EXIT_STATUS] = ssh1_smsg_exit_status;
+
+    if (ssh->cfg.agentfwd && agent_exists()) {
+	logevent("Requesting agent forwarding");
+	send_packet(ssh, SSH1_CMSG_AGENT_REQUEST_FORWARDING, PKT_END);
+	do {
+	    crReturnV;
+	} while (!pktin);
+	if (pktin->type != SSH1_SMSG_SUCCESS
+	    && pktin->type != SSH1_SMSG_FAILURE) {
+	    bombout(("Protocol confusion"));
+	    crStopV;
+	} else if (pktin->type == SSH1_SMSG_FAILURE) {
+	    logevent("Agent forwarding refused");
+	} else {
+	    logevent("Agent forwarding enabled");
+	    ssh->agentfwd_enabled = TRUE;
+	    ssh->packet_dispatch[SSH1_SMSG_AGENT_OPEN] = ssh1_smsg_agent_open;
+	}
+    }
+
+    if (ssh->cfg.x11_forward) {
+	char proto[20], data[64];
+	logevent("Requesting X11 forwarding");
+	ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
+				       data, sizeof(data), ssh->cfg.x11_auth);
+        x11_get_real_auth(ssh->x11auth, ssh->cfg.x11_display);
+	if (ssh->v1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
+	    send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
+			PKT_STR, proto, PKT_STR, data,
+			PKT_INT, x11_get_screen_number(ssh->cfg.x11_display),
+			PKT_END);
+	} else {
+	    send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
+			PKT_STR, proto, PKT_STR, data, PKT_END);
+	}
+	do {
+	    crReturnV;
+	} while (!pktin);
+	if (pktin->type != SSH1_SMSG_SUCCESS
+	    && pktin->type != SSH1_SMSG_FAILURE) {
+	    bombout(("Protocol confusion"));
+	    crStopV;
+	} else if (pktin->type == SSH1_SMSG_FAILURE) {
+	    logevent("X11 forwarding refused");
+	} else {
+	    logevent("X11 forwarding enabled");
+	    ssh->X11_fwd_enabled = TRUE;
+	    ssh->packet_dispatch[SSH1_SMSG_X11_OPEN] = ssh1_smsg_x11_open;
+	}
+    }
+
+    ssh_setup_portfwd(ssh, &ssh->cfg);
+    ssh->packet_dispatch[SSH1_MSG_PORT_OPEN] = ssh1_msg_port_open;
 
     if (!ssh->cfg.nopty) {
 	/* Unpick the terminal-speed string. */
@@ -3681,12 +4357,12 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	ssh->state = SSH_STATE_INTERMED;
 	do {
 	    crReturnV;
-	} while (!ispkt);
-	if (ssh->pktin.type != SSH1_SMSG_SUCCESS
-	    && ssh->pktin.type != SSH1_SMSG_FAILURE) {
+	} while (!pktin);
+	if (pktin->type != SSH1_SMSG_SUCCESS
+	    && pktin->type != SSH1_SMSG_FAILURE) {
 	    bombout(("Protocol confusion"));
 	    crStopV;
-	} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
+	} else if (pktin->type == SSH1_SMSG_FAILURE) {
 	    c_write_str(ssh, "Server refused to allocate pty\r\n");
 	    ssh->editing = ssh->echoing = 1;
 	}
@@ -3700,12 +4376,12 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	send_packet(ssh, SSH1_CMSG_REQUEST_COMPRESSION, PKT_INT, 6, PKT_END);
 	do {
 	    crReturnV;
-	} while (!ispkt);
-	if (ssh->pktin.type != SSH1_SMSG_SUCCESS
-	    && ssh->pktin.type != SSH1_SMSG_FAILURE) {
+	} while (!pktin);
+	if (pktin->type != SSH1_SMSG_SUCCESS
+	    && pktin->type != SSH1_SMSG_FAILURE) {
 	    bombout(("Protocol confusion"));
 	    crStopV;
-	} else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
+	} else if (pktin->type == SSH1_SMSG_FAILURE) {
 	    c_write_str(ssh, "Server refused to compress\r\n");
 	}
 	logevent("Started compression");
@@ -3748,315 +4424,22 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     ssh->send_ok = 1;
     ssh->channels = newtree234(ssh_channelcmp);
     while (1) {
-	crReturnV;
-	if (ispkt) {
-	    if (ssh->pktin.type == SSH1_SMSG_STDOUT_DATA ||
-		ssh->pktin.type == SSH1_SMSG_STDERR_DATA) {
-		char *string;
-		int stringlen, bufsize;
-
-		ssh_pkt_getstring(ssh, &string, &stringlen);
-		if (string == NULL) {
-		    bombout(("Incoming terminal data packet was badly formed"));
-		    crStopV;
-		}
-
-		bufsize =
-		    from_backend(ssh->frontend,
-				 ssh->pktin.type == SSH1_SMSG_STDERR_DATA,
-				 string, stringlen);
-		if (!ssh->v1_stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) {
-		    ssh->v1_stdout_throttling = 1;
-		    ssh1_throttle(ssh, +1);
-		}
-	    } else if (ssh->pktin.type == SSH1_MSG_DISCONNECT) {
-                ssh_closing((Plug)ssh, NULL, 0, 0);
-		logevent("Received disconnect request");
-		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. */
-		struct ssh_channel *c;
-		int remoteid = ssh_pkt_getuint32(ssh);
-
-		logevent("Received X11 connect request");
-		/* Refuse if X11 forwarding is disabled. */
-		if (!ssh->X11_fwd_enabled) {
-		    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
-				PKT_INT, remoteid, PKT_END);
-		    logevent("Rejected X11 connect request");
-		} else {
-		    c = snew(struct ssh_channel);
-		    c->ssh = ssh;
-
-		    if (x11_init(&c->u.x11.s, ssh->cfg.x11_display, c,
-				 ssh->x11auth, NULL, -1, &ssh->cfg) != NULL) {
-			logevent("Opening X11 forward connection failed");
-			sfree(c);
-			send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
-				    PKT_INT, remoteid, PKT_END);
-		    } else {
-			logevent
-			    ("Opening X11 forward connection succeeded");
-			c->remoteid = remoteid;
-			c->localid = alloc_channel_id(ssh);
-			c->closes = 0;
-			c->v.v1.throttling = 0;
-			c->type = CHAN_X11;	/* identify channel type */
-			add234(ssh->channels, c);
-			send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
-				    PKT_INT, c->remoteid, PKT_INT,
-				    c->localid, PKT_END);
-			logevent("Opened X11 forward channel");
-		    }
-		}
-	    } else if (ssh->pktin.type == SSH1_SMSG_AGENT_OPEN) {
-		/* Remote side is trying to open a channel to talk to our
-		 * agent. Give them back a local channel number. */
-		struct ssh_channel *c;
-		int remoteid = ssh_pkt_getuint32(ssh);
-
-		/* Refuse if agent forwarding is disabled. */
-		if (!ssh->agentfwd_enabled) {
-		    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
-				PKT_INT, remoteid, PKT_END);
-		} else {
-		    c = snew(struct ssh_channel);
-		    c->ssh = ssh;
-		    c->remoteid = remoteid;
-		    c->localid = alloc_channel_id(ssh);
-		    c->closes = 0;
-		    c->v.v1.throttling = 0;
-		    c->type = CHAN_AGENT;	/* identify channel type */
-		    c->u.a.lensofar = 0;
-		    add234(ssh->channels, c);
-		    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
-				PKT_INT, c->remoteid, PKT_INT, c->localid,
-				PKT_END);
-		}
-	    } else if (ssh->pktin.type == SSH1_MSG_PORT_OPEN) {
-   		/* Remote side is trying to open a channel to talk to a
-		 * forwarded port. Give them back a local channel number. */
-		struct ssh_channel *c;
-		struct ssh_rportfwd pf;
-		int remoteid;
-		int hostsize, port;
-		char *host, buf[1024];
-		const char *e;
-		c = snew(struct ssh_channel);
-		c->ssh = ssh;
-
-		remoteid = ssh_pkt_getuint32(ssh);
-		ssh_pkt_getstring(ssh, &host, &hostsize);
-		port = ssh_pkt_getuint32(ssh);
-
-		if (hostsize >= lenof(pf.dhost))
-		    hostsize = lenof(pf.dhost)-1;
-		memcpy(pf.dhost, host, hostsize);
-		pf.dhost[hostsize] = '\0';
-		pf.dport = port;
-
-		if (find234(ssh->rportfwds, &pf, NULL) == NULL) {
-		    sprintf(buf, "Rejected remote port open request for %s:%d",
-			    pf.dhost, port);
-		    logevent(buf);
-                    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
-                                PKT_INT, remoteid, PKT_END);
-		} else {
-		    sprintf(buf, "Received remote port open request for %s:%d",
-			    pf.dhost, port);
-		    logevent(buf);
-		    e = pfd_newconnect(&c->u.pfd.s, pf.dhost, port,
-				       c, &ssh->cfg);
-		    if (e != NULL) {
-			char buf[256];
-			sprintf(buf, "Port open failed: %s", e);
-			logevent(buf);
-			sfree(c);
-			send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
-				    PKT_INT, remoteid, PKT_END);
-		    } else {
-			c->remoteid = remoteid;
-			c->localid = alloc_channel_id(ssh);
-			c->closes = 0;
-			c->v.v1.throttling = 0;
-			c->type = CHAN_SOCKDATA;	/* identify channel type */
-			add234(ssh->channels, c);
-			send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
-				    PKT_INT, c->remoteid, PKT_INT,
-				    c->localid, PKT_END);
-			logevent("Forwarded port opened successfully");
-		    }
-		}
 
-	    } else if (ssh->pktin.type == SSH1_MSG_CHANNEL_OPEN_CONFIRMATION) {
-		unsigned int remoteid = ssh_pkt_getuint32(ssh);
-		unsigned int localid = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-
-		c = find234(ssh->channels, &remoteid, ssh_channelfind);
-		if (c && c->type == CHAN_SOCKDATA_DORMANT) {
-		    c->remoteid = localid;
-		    c->type = CHAN_SOCKDATA;
-		    c->v.v1.throttling = 0;
-		    pfd_confirm(c->u.pfd.s);
-		}
-
-		if (c && c->closes) {
-		    /*
-		     * We have a pending close on this channel,
-		     * which we decided on before the server acked
-		     * the channel open. So now we know the
-		     * remoteid, we can close it again.
-		     */
-		    send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE,
-				PKT_INT, c->remoteid, PKT_END);
-		}
-
-	    } else if (ssh->pktin.type == SSH1_MSG_CHANNEL_OPEN_FAILURE) {
-		unsigned int remoteid = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-
-		c = find234(ssh->channels, &remoteid, ssh_channelfind);
-		if (c && c->type == CHAN_SOCKDATA_DORMANT) {
-		    logevent("Forwarded connection refused by server");
-		    pfd_close(c->u.pfd.s);
-		    del234(ssh->channels, c);
-		    sfree(c);
-		}
-
-	    } else if (ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE ||
-		       ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION) {
-		/* Remote side closes a channel. */
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (c && ((int)c->remoteid) != -1) {
-		    int closetype;
-		    closetype =
-			(ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2);
-
-		    if ((c->closes == 0) && (c->type == CHAN_X11)) {
-			logevent("Forwarded X11 connection terminated");
-			assert(c->u.x11.s != NULL);
-			x11_close(c->u.x11.s);
-			c->u.x11.s = NULL;
-		    }
-		    if ((c->closes == 0) && (c->type == CHAN_SOCKDATA)) {
-			logevent("Forwarded port closed");
-			assert(c->u.pfd.s != NULL);
-			pfd_close(c->u.pfd.s);
-			c->u.pfd.s = NULL;
-		    }
-
-		    c->closes |= (closetype << 2);   /* seen this message */
-		    if (!(c->closes & closetype)) {
-			send_packet(ssh, ssh->pktin.type, PKT_INT, c->remoteid,
-				    PKT_END);
-			c->closes |= closetype;      /* sent it too */
-		    }
+	/*
+	 * By this point, most incoming packets are already being
+	 * handled by the dispatch table, and we need only pay
+	 * attention to the unusual ones.
+	 */
 
-		    if (c->closes == 15) {
-			del234(ssh->channels, c);
-			sfree(c);
-		    }
-		} else {
-		    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. */
-		int i = ssh_pkt_getuint32(ssh);
-		char *p;
-		int len;
-		struct ssh_channel *c;
-
-		ssh_pkt_getstring(ssh, &p, &len);
-
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (c) {
-		    int bufsize = 0;
-		    switch (c->type) {
-		      case CHAN_X11:
-			bufsize = x11_send(c->u.x11.s, p, len);
-			break;
-		      case CHAN_SOCKDATA:
-			bufsize = pfd_send(c->u.pfd.s, p, len);
-			break;
-		      case CHAN_AGENT:
-			/* Data for an agent message. Buffer it. */
-			while (len > 0) {
-			    if (c->u.a.lensofar < 4) {
-				int l = min(4 - c->u.a.lensofar, len);
-				memcpy(c->u.a.msglen + c->u.a.lensofar, p,
-				       l);
-				p += l;
-				len -= l;
-				c->u.a.lensofar += l;
-			    }
-			    if (c->u.a.lensofar == 4) {
-				c->u.a.totallen =
-				    4 + GET_32BIT(c->u.a.msglen);
-				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) {
-				int l =
-				    min(c->u.a.totallen - c->u.a.lensofar,
-					len);
-				memcpy(c->u.a.message + c->u.a.lensofar, p,
-				       l);
-				p += l;
-				len -= l;
-				c->u.a.lensofar += l;
-			    }
-			    if (c->u.a.lensofar == c->u.a.totallen) {
-				void *reply;
-				int replylen;
-				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;
-			    }
-			}
-			bufsize = 0;   /* agent channels never back up */
-			break;
-		    }
-		    if (!c->v.v1.throttling && bufsize > SSH1_BUFFER_LIMIT) {
-			c->v.v1.throttling = 1;
-			ssh1_throttle(ssh, +1);
-		    }
-		}
-	    } else if (ssh->pktin.type == SSH1_SMSG_SUCCESS) {
+	crReturnV;
+	if (pktin) {
+	    if (pktin->type == SSH1_SMSG_SUCCESS) {
 		/* may be from EXEC_SHELL on some servers */
-	    } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
+	    } else if (pktin->type == SSH1_SMSG_FAILURE) {
 		/* may be from EXEC_SHELL on some servers
 		 * if no pty is available or in other odd cases. Ignore */
-	    } else if (ssh->pktin.type == SSH1_SMSG_EXIT_STATUS) {
-		char buf[100];
-		ssh->exitcode = ssh_pkt_getuint32(ssh);
-		sprintf(buf, "Server sent command exit status %d",
-			ssh->exitcode);
-		logevent(buf);
-		send_packet(ssh, SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
-                /*
-                 * In case `helpful' firewalls or proxies tack
-                 * extra human-readable text on the end of the
-                 * session which we might mistake for another
-                 * encrypted packet, we close the session once
-                 * we've sent EXIT_CONFIRMATION.
-                 */
-                ssh_closing((Plug)ssh, NULL, 0, 0);
-                crStopV;
 	    } else {
-		bombout(("Strange packet received: type %d", ssh->pktin.type));
+		bombout(("Strange packet received: type %d", pktin->type));
 		crStopV;
 	    }
 	} else {
@@ -4071,7 +4454,75 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	}
     }
 
-    crFinishV;
+    crFinishV;
+}
+
+/*
+ * Handle the top-level SSH2 protocol.
+ */
+static void ssh1_msg_debug(Ssh ssh, struct Packet *pktin)
+{
+    char *buf, *msg;
+    int msglen;
+
+    ssh_pkt_getstring(pktin, &msg, &msglen);
+    buf = dupprintf("Remote debug message: %.*s", msglen, msg);
+    logevent(buf);
+    sfree(buf);
+}
+
+static void ssh1_msg_disconnect(Ssh ssh, struct Packet *pktin)
+{
+    /* log reason code in disconnect message */
+    char *msg;
+    int msglen;
+
+    ssh_pkt_getstring(pktin, &msg, &msglen);
+    bombout(("Server sent disconnect message:\n\"%.*s\"", msglen, msg));
+}
+
+void ssh_msg_ignore(Ssh ssh, struct Packet *pktin)
+{
+    /* Do nothing, because we're ignoring it! Duhh. */
+}
+
+static void ssh1_protocol_setup(Ssh ssh)
+{
+    int i;
+
+    /*
+     * Most messages are handled by the coroutines.
+     */
+    for (i = 0; i < 256; i++)
+	ssh->packet_dispatch[i] = NULL;
+
+    /*
+     * These special message types we install handlers for.
+     */
+    ssh->packet_dispatch[SSH1_MSG_DISCONNECT] = ssh1_msg_disconnect;
+    ssh->packet_dispatch[SSH1_MSG_IGNORE] = ssh_msg_ignore;
+    ssh->packet_dispatch[SSH1_MSG_DEBUG] = ssh1_msg_debug;
+}
+
+static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen,
+			  struct Packet *pktin)
+{
+    if (ssh->state == SSH_STATE_CLOSED)
+	return;
+
+    if (pktin && ssh->packet_dispatch[pktin->type]) {
+	ssh->packet_dispatch[pktin->type](ssh, pktin);
+	return;
+    }
+
+    if (!ssh->protocol_initial_phase_done) {
+	if (do_ssh1_login(ssh, in, inlen, pktin))
+	    ssh->protocol_initial_phase_done = TRUE;
+	else
+	    return;
+    }
+
+    do_ssh1_connection(ssh, in, inlen, pktin);
 }
 
 /*
@@ -4133,7 +4584,8 @@ static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
 /*
  * Handle the SSH2 transport layer.
  */
-static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
+static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
+			     struct Packet *pktin)
 {
     struct do_ssh2_transport_state {
 	int nbits, pbits, warn;
@@ -4151,10 +4603,13 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	int hostkeylen, siglen;
 	void *hkey;		       /* actual host key */
 	unsigned char exchange_hash[20];
+	int n_preferred_kex;
+	const struct ssh_kex *preferred_kex[KEX_MAX];
 	int n_preferred_ciphers;
 	const struct ssh2_ciphers *preferred_ciphers[CIPHER_MAX];
 	const struct ssh_compress *preferred_comp;
 	int first_kex;
+	struct Packet *pktout;
     };
     crState(do_ssh2_transport_state);
 
@@ -4164,12 +4619,42 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     s->csmac_tobe = s->scmac_tobe = NULL;
     s->cscomp_tobe = s->sccomp_tobe = NULL;
 
-    random_init();
     s->first_kex = 1;
 
     {
 	int i;
 	/*
+	 * Set up the preferred key exchange. (NULL => warn below here)
+	 */
+	s->n_preferred_kex = 0;
+	for (i = 0; i < KEX_MAX; i++) {
+	    switch (ssh->cfg.ssh_kexlist[i]) {
+	      case KEX_DHGEX:
+		s->preferred_kex[s->n_preferred_kex++] =
+		    &ssh_diffiehellman_gex;
+		break;
+	      case KEX_DHGROUP14:
+		s->preferred_kex[s->n_preferred_kex++] =
+		    &ssh_diffiehellman_group14;
+		break;
+	      case KEX_DHGROUP1:
+		s->preferred_kex[s->n_preferred_kex++] =
+		    &ssh_diffiehellman_group1;
+		break;
+	      case CIPHER_WARN:
+		/* Flag for later. Don't bother if it's the last in
+		 * the list. */
+		if (i < KEX_MAX - 1) {
+		    s->preferred_kex[s->n_preferred_kex++] = NULL;
+		}
+		break;
+	    }
+	}
+    }
+
+    {
+	int i;
+	/*
 	 * Set up the preferred ciphers. (NULL => warn below here)
 	 */
 	s->n_preferred_ciphers = 0;
@@ -4218,112 +4703,124 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
   begin_key_exchange:
     {
-	int i, j, cipherstr_started;
+	int i, j, commalist_started;
+
+	/*
+	 * Enable queueing of outgoing auth- or connection-layer
+	 * packets while we are in the middle of a key exchange.
+	 */
+	ssh->queueing = TRUE;
+
+	/*
+	 * Flag that KEX is in progress.
+	 */
+	ssh->kex_in_progress = TRUE;
 
 	/*
 	 * Construct and send our key exchange packet.
 	 */
-	ssh2_pkt_init(ssh, SSH2_MSG_KEXINIT);
+	s->pktout = ssh2_pkt_init(SSH2_MSG_KEXINIT);
 	for (i = 0; i < 16; i++)
-	    ssh2_pkt_addbyte(ssh, (unsigned char) random_byte());
+	    ssh2_pkt_addbyte(s->pktout, (unsigned char) random_byte());
 	/* List key exchange algorithms. */
-	ssh2_pkt_addstring_start(ssh);
-	for (i = 0; i < lenof(kex_algs); i++) {
-	    if (kex_algs[i] == &ssh_diffiehellman_gex &&
-		(ssh->remote_bugs & BUG_SSH2_DH_GEX))
-		continue;
-	    ssh2_pkt_addstring_str(ssh, kex_algs[i]->name);
-	    if (i < lenof(kex_algs) - 1)
-		ssh2_pkt_addstring_str(ssh, ",");
+	ssh2_pkt_addstring_start(s->pktout);
+	commalist_started = 0;
+	for (i = 0; i < s->n_preferred_kex; i++) {
+	    const struct ssh_kex *k = s->preferred_kex[i];
+	    if (!k) continue;	       /* warning flag */
+	    if (commalist_started)
+		ssh2_pkt_addstring_str(s->pktout, ",");
+	    ssh2_pkt_addstring_str(s->pktout, s->preferred_kex[i]->name);
+	    commalist_started = 1;
 	}
 	/* List server host key algorithms. */
-	ssh2_pkt_addstring_start(ssh);
+	ssh2_pkt_addstring_start(s->pktout);
 	for (i = 0; i < lenof(hostkey_algs); i++) {
-	    ssh2_pkt_addstring_str(ssh, hostkey_algs[i]->name);
+	    ssh2_pkt_addstring_str(s->pktout, hostkey_algs[i]->name);
 	    if (i < lenof(hostkey_algs) - 1)
-		ssh2_pkt_addstring_str(ssh, ",");
+		ssh2_pkt_addstring_str(s->pktout, ",");
 	}
 	/* List client->server encryption algorithms. */
-	ssh2_pkt_addstring_start(ssh);
-	cipherstr_started = 0;
+	ssh2_pkt_addstring_start(s->pktout);
+	commalist_started = 0;
 	for (i = 0; i < s->n_preferred_ciphers; i++) {
 	    const struct ssh2_ciphers *c = s->preferred_ciphers[i];
 	    if (!c) continue;	       /* warning flag */
 	    for (j = 0; j < c->nciphers; j++) {
-		if (cipherstr_started)
-		    ssh2_pkt_addstring_str(ssh, ",");
-		ssh2_pkt_addstring_str(ssh, c->list[j]->name);
-		cipherstr_started = 1;
+		if (commalist_started)
+		    ssh2_pkt_addstring_str(s->pktout, ",");
+		ssh2_pkt_addstring_str(s->pktout, c->list[j]->name);
+		commalist_started = 1;
 	    }
 	}
 	/* List server->client encryption algorithms. */
-	ssh2_pkt_addstring_start(ssh);
-	cipherstr_started = 0;
+	ssh2_pkt_addstring_start(s->pktout);
+	commalist_started = 0;
 	for (i = 0; i < s->n_preferred_ciphers; i++) {
 	    const struct ssh2_ciphers *c = s->preferred_ciphers[i];
 	    if (!c) continue; /* warning flag */
 	    for (j = 0; j < c->nciphers; j++) {
-		if (cipherstr_started)
-		    ssh2_pkt_addstring_str(ssh, ",");
-		ssh2_pkt_addstring_str(ssh, c->list[j]->name);
-		cipherstr_started = 1;
+		if (commalist_started)
+		    ssh2_pkt_addstring_str(s->pktout, ",");
+		ssh2_pkt_addstring_str(s->pktout, c->list[j]->name);
+		commalist_started = 1;
 	    }
 	}
 	/* List client->server MAC algorithms. */
-	ssh2_pkt_addstring_start(ssh);
+	ssh2_pkt_addstring_start(s->pktout);
 	for (i = 0; i < s->nmacs; i++) {
-	    ssh2_pkt_addstring_str(ssh, s->maclist[i]->name);
+	    ssh2_pkt_addstring_str(s->pktout, s->maclist[i]->name);
 	    if (i < s->nmacs - 1)
-		ssh2_pkt_addstring_str(ssh, ",");
+		ssh2_pkt_addstring_str(s->pktout, ",");
 	}
 	/* List server->client MAC algorithms. */
-	ssh2_pkt_addstring_start(ssh);
+	ssh2_pkt_addstring_start(s->pktout);
 	for (i = 0; i < s->nmacs; i++) {
-	    ssh2_pkt_addstring_str(ssh, s->maclist[i]->name);
+	    ssh2_pkt_addstring_str(s->pktout, s->maclist[i]->name);
 	    if (i < s->nmacs - 1)
-		ssh2_pkt_addstring_str(ssh, ",");
+		ssh2_pkt_addstring_str(s->pktout, ",");
 	}
 	/* List client->server compression algorithms. */
-	ssh2_pkt_addstring_start(ssh);
+	ssh2_pkt_addstring_start(s->pktout);
 	assert(lenof(compressions) > 1);
-	ssh2_pkt_addstring_str(ssh, s->preferred_comp->name);
+	ssh2_pkt_addstring_str(s->pktout, s->preferred_comp->name);
 	for (i = 0; i < lenof(compressions); i++) {
 	    const struct ssh_compress *c = compressions[i];
 	    if (c != s->preferred_comp) {
-		ssh2_pkt_addstring_str(ssh, ",");
-		ssh2_pkt_addstring_str(ssh, c->name);
+		ssh2_pkt_addstring_str(s->pktout, ",");
+		ssh2_pkt_addstring_str(s->pktout, c->name);
 	    }
 	}
 	/* List server->client compression algorithms. */
-	ssh2_pkt_addstring_start(ssh);
+	ssh2_pkt_addstring_start(s->pktout);
 	assert(lenof(compressions) > 1);
-	ssh2_pkt_addstring_str(ssh, s->preferred_comp->name);
+	ssh2_pkt_addstring_str(s->pktout, s->preferred_comp->name);
 	for (i = 0; i < lenof(compressions); i++) {
 	    const struct ssh_compress *c = compressions[i];
 	    if (c != s->preferred_comp) {
-		ssh2_pkt_addstring_str(ssh, ",");
-		ssh2_pkt_addstring_str(ssh, c->name);
+		ssh2_pkt_addstring_str(s->pktout, ",");
+		ssh2_pkt_addstring_str(s->pktout, c->name);
 	    }
 	}
 	/* List client->server languages. Empty list. */
-	ssh2_pkt_addstring_start(ssh);
+	ssh2_pkt_addstring_start(s->pktout);
 	/* List server->client languages. Empty list. */
-	ssh2_pkt_addstring_start(ssh);
+	ssh2_pkt_addstring_start(s->pktout);
 	/* First KEX packet does _not_ follow, because we're not that brave. */
-	ssh2_pkt_addbool(ssh, FALSE);
+	ssh2_pkt_addbool(s->pktout, FALSE);
 	/* Reserved. */
-	ssh2_pkt_adduint32(ssh, 0);
+	ssh2_pkt_adduint32(s->pktout, 0);
     }
 
     ssh->exhash = ssh->exhashbase;
-    sha_string(&ssh->exhash, ssh->pktout.data + 5, ssh->pktout.length - 5);
+    sha_string(&ssh->exhash, s->pktout->data + 5, s->pktout->length - 5);
 
-    ssh2_pkt_send(ssh);
+    ssh2_pkt_send_noqueue(ssh, s->pktout);
 
-    if (!ispkt)
-	crWaitUntil(ispkt);
-    if (ssh->pktin.length > 5)
-	sha_string(&ssh->exhash, ssh->pktin.data + 5, ssh->pktin.length - 5);
+    if (!pktin)
+	crWaitUntil(pktin);
+    if (pktin->length > 5)
+	sha_string(&ssh->exhash, pktin->data + 5, pktin->length - 5);
 
     /*
      * Now examine the other side's KEXINIT to see what we're up
@@ -4333,7 +4830,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	char *str;
 	int i, j, len;
 
-	if (ssh->pktin.type != SSH2_MSG_KEXINIT) {
+	if (pktin->type != SSH2_MSG_KEXINIT) {
 	    bombout(("expected key exchange packet from server"));
 	    crStop(0);
 	}
@@ -4345,25 +4842,36 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	s->scmac_tobe = NULL;
 	s->cscomp_tobe = NULL;
 	s->sccomp_tobe = NULL;
-	ssh->pktin.savedpos += 16;	        /* skip garbage cookie */
-	ssh_pkt_getstring(ssh, &str, &len);    /* key exchange algorithms */
-	for (i = 0; i < lenof(kex_algs); i++) {
-	    if (kex_algs[i] == &ssh_diffiehellman_gex &&
-		(ssh->remote_bugs & BUG_SSH2_DH_GEX))
-		continue;
-	    if (in_commasep_string(kex_algs[i]->name, str, len)) {
-		ssh->kex = kex_algs[i];
+	pktin->savedpos += 16;	        /* skip garbage cookie */
+	ssh_pkt_getstring(pktin, &str, &len);    /* key exchange algorithms */
+	s->warn = 0;
+	for (i = 0; i < s->n_preferred_kex; i++) {
+	    const struct ssh_kex *k = s->preferred_kex[i];
+	    if (!k) {
+		s->warn = 1;
+	    } else if (in_commasep_string(k->name, str, len)) {
+		ssh->kex = k;
+	    }
+	    if (ssh->kex) {
+		if (s->warn)
+		    askalg(ssh->frontend, "key-exchange algorithm",
+			   ssh->kex->name);
 		break;
 	    }
 	}
-	ssh_pkt_getstring(ssh, &str, &len);    /* host key algorithms */
+	if (!ssh->kex) {
+	    bombout(("Couldn't agree a key exchange algorithm (available: %s)",
+		     str ? str : "(null)"));
+	    crStop(0);
+	}
+	ssh_pkt_getstring(pktin, &str, &len);    /* host key algorithms */
 	for (i = 0; i < lenof(hostkey_algs); i++) {
 	    if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
 		ssh->hostkey = hostkey_algs[i];
 		break;
 	    }
 	}
-	ssh_pkt_getstring(ssh, &str, &len);    /* client->server cipher */
+	ssh_pkt_getstring(pktin, &str, &len);    /* client->server cipher */
 	s->warn = 0;
 	for (i = 0; i < s->n_preferred_ciphers; i++) {
 	    const struct ssh2_ciphers *c = s->preferred_ciphers[i];
@@ -4379,7 +4887,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    }
 	    if (s->cscipher_tobe) {
 		if (s->warn)
-		    askcipher(ssh->frontend, s->cscipher_tobe->name, 1);
+		    askalg(ssh->frontend, "client-to-server cipher",
+			   s->cscipher_tobe->name);
 		break;
 	    }
 	}
@@ -4389,7 +4898,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    crStop(0);
 	}
 
-	ssh_pkt_getstring(ssh, &str, &len);    /* server->client cipher */
+	ssh_pkt_getstring(pktin, &str, &len);    /* server->client cipher */
 	s->warn = 0;
 	for (i = 0; i < s->n_preferred_ciphers; i++) {
 	    const struct ssh2_ciphers *c = s->preferred_ciphers[i];
@@ -4405,7 +4914,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    }
 	    if (s->sccipher_tobe) {
 		if (s->warn)
-		    askcipher(ssh->frontend, s->sccipher_tobe->name, 2);
+		    askalg(ssh->frontend, "server-to-client cipher",
+			   s->sccipher_tobe->name);
 		break;
 	    }
 	}
@@ -4415,21 +4925,21 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    crStop(0);
 	}
 
-	ssh_pkt_getstring(ssh, &str, &len);    /* client->server mac */
+	ssh_pkt_getstring(pktin, &str, &len);    /* client->server mac */
 	for (i = 0; i < s->nmacs; i++) {
 	    if (in_commasep_string(s->maclist[i]->name, str, len)) {
 		s->csmac_tobe = s->maclist[i];
 		break;
 	    }
 	}
-	ssh_pkt_getstring(ssh, &str, &len);    /* server->client mac */
+	ssh_pkt_getstring(pktin, &str, &len);    /* server->client mac */
 	for (i = 0; i < s->nmacs; i++) {
 	    if (in_commasep_string(s->maclist[i]->name, str, len)) {
 		s->scmac_tobe = s->maclist[i];
 		break;
 	    }
 	}
-	ssh_pkt_getstring(ssh, &str, &len);  /* client->server compression */
+	ssh_pkt_getstring(pktin, &str, &len);  /* client->server compression */
 	for (i = 0; i < lenof(compressions) + 1; i++) {
 	    const struct ssh_compress *c =
 		i == 0 ? s->preferred_comp : compressions[i - 1];
@@ -4438,7 +4948,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		break;
 	    }
 	}
-	ssh_pkt_getstring(ssh, &str, &len);  /* server->client compression */
+	ssh_pkt_getstring(pktin, &str, &len);  /* server->client compression */
 	for (i = 0; i < lenof(compressions) + 1; i++) {
 	    const struct ssh_compress *c =
 		i == 0 ? s->preferred_comp : compressions[i - 1];
@@ -4470,7 +4980,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * If we're doing Diffie-Hellman group exchange, start by
      * requesting a group.
      */
-    if (ssh->kex == &ssh_diffiehellman_gex) {
+    if (!ssh->kex->pdata) {
 	logevent("Doing Diffie-Hellman group exchange");
 	ssh->pkt_ctx |= SSH2_PKTCTX_DHGEX;
 	/*
@@ -4478,25 +4988,31 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	 * much data.
 	 */
 	s->pbits = 512 << ((s->nbits - 1) / 64);
-	ssh2_pkt_init(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST);
-	ssh2_pkt_adduint32(ssh, s->pbits);
-	ssh2_pkt_send(ssh);
+	s->pktout = ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST);
+	ssh2_pkt_adduint32(s->pktout, s->pbits);
+	ssh2_pkt_send_noqueue(ssh, s->pktout);
 
-	crWaitUntil(ispkt);
-	if (ssh->pktin.type != SSH2_MSG_KEX_DH_GEX_GROUP) {
+	crWaitUntil(pktin);
+	if (pktin->type != SSH2_MSG_KEX_DH_GEX_GROUP) {
 	    bombout(("expected key exchange group packet from server"));
 	    crStop(0);
 	}
-	s->p = ssh2_pkt_getmp(ssh);
-	s->g = ssh2_pkt_getmp(ssh);
-	ssh->kex_ctx = dh_setup_group(s->p, s->g);
+	s->p = ssh2_pkt_getmp(pktin);
+	s->g = ssh2_pkt_getmp(pktin);
+	if (!s->p || !s->g) {
+	    bombout(("unable to read mp-ints from incoming group packet"));
+	    crStop(0);
+	}
+	ssh->kex_ctx = dh_setup_gex(s->p, s->g);
 	s->kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
 	s->kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
     } else {
-	ssh->pkt_ctx |= SSH2_PKTCTX_DHGROUP1;
-	ssh->kex_ctx = dh_setup_group1();
+	ssh->pkt_ctx |= SSH2_PKTCTX_DHGROUP;
+	ssh->kex_ctx = dh_setup_group(ssh->kex);
 	s->kex_init_value = SSH2_MSG_KEXDH_INIT;
 	s->kex_reply_value = SSH2_MSG_KEXDH_REPLY;
+	logeventf(ssh, "Using Diffie-Hellman with standard group \"%s\"",
+		  ssh->kex->groupname);
     }
 
     logevent("Doing Diffie-Hellman key exchange");
@@ -4504,18 +5020,22 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * Now generate and send e for Diffie-Hellman.
      */
     s->e = dh_create_e(ssh->kex_ctx, s->nbits * 2);
-    ssh2_pkt_init(ssh, s->kex_init_value);
-    ssh2_pkt_addmp(ssh, s->e);
-    ssh2_pkt_send(ssh);
+    s->pktout = ssh2_pkt_init(s->kex_init_value);
+    ssh2_pkt_addmp(s->pktout, s->e);
+    ssh2_pkt_send_noqueue(ssh, s->pktout);
 
-    crWaitUntil(ispkt);
-    if (ssh->pktin.type != s->kex_reply_value) {
+    crWaitUntil(pktin);
+    if (pktin->type != s->kex_reply_value) {
 	bombout(("expected key exchange reply packet from server"));
 	crStop(0);
     }
-    ssh_pkt_getstring(ssh, &s->hostkeydata, &s->hostkeylen);
-    s->f = ssh2_pkt_getmp(ssh);
-    ssh_pkt_getstring(ssh, &s->sigdata, &s->siglen);
+    ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
+    s->f = ssh2_pkt_getmp(pktin);
+    if (!s->f) {
+	bombout(("unable to parse key exchange reply packet"));
+	crStop(0);
+    }
+    ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
 
     s->K = dh_find_K(ssh->kex_ctx, s->f);
 
@@ -4564,89 +5084,122 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     ssh->hostkey->freekey(s->hkey);
 
     /*
-     * Send SSH2_MSG_NEWKEYS.
+     * The exchange hash from the very first key exchange is also
+     * the session id, used in session key construction and
+     * authentication.
      */
-    ssh2_pkt_init(ssh, SSH2_MSG_NEWKEYS);
-    ssh2_pkt_send(ssh);
+    if (s->first_kex)
+	memcpy(ssh->v2_session_id, s->exchange_hash,
+	       sizeof(s->exchange_hash));
 
     /*
-     * Expect SSH2_MSG_NEWKEYS from server.
+     * Send SSH2_MSG_NEWKEYS.
      */
-    crWaitUntil(ispkt);
-    if (ssh->pktin.type != SSH2_MSG_NEWKEYS) {
-	bombout(("expected new-keys packet from server"));
-	crStop(0);
-    }
+    s->pktout = ssh2_pkt_init(SSH2_MSG_NEWKEYS);
+    ssh2_pkt_send_noqueue(ssh, s->pktout);
+    ssh->outgoing_data_size = 0;       /* start counting from here */
 
     /*
-     * Create and initialise session keys.
+     * We've sent client NEWKEYS, so create and initialise
+     * client-to-server session keys.
      */
     if (ssh->cs_cipher_ctx)
 	ssh->cscipher->free_context(ssh->cs_cipher_ctx);
     ssh->cscipher = s->cscipher_tobe;
     ssh->cs_cipher_ctx = ssh->cscipher->make_context();
 
-    if (ssh->sc_cipher_ctx)
-	ssh->sccipher->free_context(ssh->sc_cipher_ctx);
-    ssh->sccipher = s->sccipher_tobe;
-    ssh->sc_cipher_ctx = ssh->sccipher->make_context();
-
     if (ssh->cs_mac_ctx)
 	ssh->csmac->free_context(ssh->cs_mac_ctx);
     ssh->csmac = s->csmac_tobe;
     ssh->cs_mac_ctx = ssh->csmac->make_context();
 
-    if (ssh->sc_mac_ctx)
-	ssh->scmac->free_context(ssh->sc_mac_ctx);
-    ssh->scmac = s->scmac_tobe;
-    ssh->sc_mac_ctx = ssh->scmac->make_context();
-
     if (ssh->cs_comp_ctx)
 	ssh->cscomp->compress_cleanup(ssh->cs_comp_ctx);
     ssh->cscomp = s->cscomp_tobe;
     ssh->cs_comp_ctx = ssh->cscomp->compress_init();
 
+    /*
+     * Set IVs on client-to-server keys. Here we use the exchange
+     * hash from the _first_ key exchange.
+     */
+    {
+	unsigned char keyspace[40];
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'C',keyspace);
+	ssh->cscipher->setkey(ssh->cs_cipher_ctx, keyspace);
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'A',keyspace);
+	ssh->cscipher->setiv(ssh->cs_cipher_ctx, keyspace);
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'E',keyspace);
+	ssh->csmac->setkey(ssh->cs_mac_ctx, keyspace);
+    }
+
+    logeventf(ssh, "Initialised %.200s client->server encryption",
+	      ssh->cscipher->text_name);
+    logeventf(ssh, "Initialised %.200s client->server MAC algorithm",
+	      ssh->csmac->text_name);
+    if (ssh->cscomp->text_name)
+	logeventf(ssh, "Initialised %s compression",
+		  ssh->cscomp->text_name);
+
+    /*
+     * Now our end of the key exchange is complete, we can send all
+     * our queued higher-layer packets.
+     */
+    ssh->queueing = FALSE;
+    ssh2_pkt_queuesend(ssh);
+
+    /*
+     * Expect SSH2_MSG_NEWKEYS from server.
+     */
+    crWaitUntil(pktin);
+    if (pktin->type != SSH2_MSG_NEWKEYS) {
+	bombout(("expected new-keys packet from server"));
+	crStop(0);
+    }
+    ssh->incoming_data_size = 0;       /* start counting from here */
+
+    /*
+     * We've seen server NEWKEYS, so create and initialise
+     * server-to-client session keys.
+     */
+    if (ssh->sc_cipher_ctx)
+	ssh->sccipher->free_context(ssh->sc_cipher_ctx);
+    ssh->sccipher = s->sccipher_tobe;
+    ssh->sc_cipher_ctx = ssh->sccipher->make_context();
+
+    if (ssh->sc_mac_ctx)
+	ssh->scmac->free_context(ssh->sc_mac_ctx);
+    ssh->scmac = s->scmac_tobe;
+    ssh->sc_mac_ctx = ssh->scmac->make_context();
+
     if (ssh->sc_comp_ctx)
 	ssh->sccomp->decompress_cleanup(ssh->sc_comp_ctx);
     ssh->sccomp = s->sccomp_tobe;
     ssh->sc_comp_ctx = ssh->sccomp->decompress_init();
 
     /*
-     * Set IVs after keys. Here we use the exchange hash from the
-     * _first_ key exchange.
+     * Set IVs on server-to-client keys. Here we use the exchange
+     * hash from the _first_ key exchange.
      */
     {
 	unsigned char keyspace[40];
-	if (s->first_kex)
-	    memcpy(ssh->v2_session_id, s->exchange_hash,
-		   sizeof(s->exchange_hash));
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'C',keyspace);
-	ssh->cscipher->setkey(ssh->cs_cipher_ctx, keyspace);
 	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'D',keyspace);
 	ssh->sccipher->setkey(ssh->sc_cipher_ctx, keyspace);
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'A',keyspace);
-	ssh->cscipher->setiv(ssh->cs_cipher_ctx, keyspace);
 	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'B',keyspace);
 	ssh->sccipher->setiv(ssh->sc_cipher_ctx, keyspace);
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'E',keyspace);
-	ssh->csmac->setkey(ssh->cs_mac_ctx, keyspace);
 	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'F',keyspace);
 	ssh->scmac->setkey(ssh->sc_mac_ctx, keyspace);
     }
-    logeventf(ssh, "Initialised %.200s client->server encryption",
-	      ssh->cscipher->text_name);
     logeventf(ssh, "Initialised %.200s server->client encryption",
 	      ssh->sccipher->text_name);
-    logeventf(ssh, "Initialised %.200s client->server MAC algorithm",
-	      ssh->csmac->text_name);
     logeventf(ssh, "Initialised %.200s server->client MAC algorithm",
 	      ssh->scmac->text_name);
-    if (ssh->cscomp->text_name)
-	logeventf(ssh, "Initialised %s compression",
-		  ssh->cscomp->text_name);
     if (ssh->sccomp->text_name)
 	logeventf(ssh, "Initialised %s decompression",
 		  ssh->sccomp->text_name);
+
+    /*
+     * Free key exchange data.
+     */
     freebn(s->f);
     freebn(s->K);
     if (ssh->kex == &ssh_diffiehellman_gex) {
@@ -4655,6 +5208,15 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     }
 
     /*
+     * Key exchange is over. Schedule a timer for our next rekey.
+     */
+    ssh->kex_in_progress = FALSE;
+    ssh->last_rekey = GETTICKCOUNT();
+    if (ssh->cfg.ssh_rekey_time != 0)
+	ssh->next_rekey = schedule_timer(ssh->cfg.ssh_rekey_time*60*TICKSPERSEC,
+					 ssh2_timer, ssh);
+    
+    /*
      * If this is the first key exchange phase, we must pass the
      * SSH2_MSG_NEWKEYS packet to the next layer, not because it
      * wants to see it but because it will need time to initialise
@@ -4663,7 +5225,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * it would only confuse the layer above.
      */
     if (!s->first_kex) {
-	crReturn(0);
+	crReturn(1);
     }
     s->first_kex = 0;
 
@@ -4672,11 +5234,21 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * function so that other things can run on top of the
      * transport. If we ever see a KEXINIT, we must go back to the
      * start.
+     * 
+     * We _also_ go back to the start if we see pktin==NULL and
+     * inlen==-1, because this is a special signal meaning
+     * `initiate client-driven rekey', and `in' contains a message
+     * giving the reason for the rekey.
      */
-    while (!(ispkt && ssh->pktin.type == SSH2_MSG_KEXINIT)) {
+    while (!((pktin && pktin->type == SSH2_MSG_KEXINIT) ||
+	     (!pktin && inlen == -1))) {
 	crReturn(1);
     }
-    logevent("Server initiated key re-exchange");
+    if (pktin) {
+	logevent("Server initiated key re-exchange");
+    } else {
+	logevent((char *)in);
+    }
     goto begin_key_exchange;
 
     crFinish(1);
@@ -4697,6 +5269,7 @@ static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
 static int ssh2_try_send(struct ssh_channel *c)
 {
     Ssh ssh = c->ssh;
+    struct Packet *pktout;
 
     while (c->v.v2.remwindow > 0 && bufchain_size(&c->v.v2.outbuffer) > 0) {
 	int len;
@@ -4706,13 +5279,13 @@ static int ssh2_try_send(struct ssh_channel *c)
 	    len = c->v.v2.remwindow;
 	if ((unsigned)len > c->v.v2.remmaxpkt)
 	    len = c->v.v2.remmaxpkt;
-	ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_DATA);
-	ssh2_pkt_adduint32(ssh, c->remoteid);
-	dont_log_data(ssh, PKTLOG_OMIT);
-	ssh2_pkt_addstring_start(ssh);
-	ssh2_pkt_addstring_data(ssh, data, len);
-	end_log_omission(ssh);
-	ssh2_pkt_send(ssh);
+	pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_DATA);
+	ssh2_pkt_adduint32(pktout, c->remoteid);
+	dont_log_data(ssh, pktout, PKTLOG_OMIT);
+	ssh2_pkt_addstring_start(pktout);
+	ssh2_pkt_addstring_data(pktout, data, len);
+	end_log_omission(ssh, pktout);
+	ssh2_pkt_send(ssh, pktout);
 	bufchain_consume(&c->v.v2.outbuffer, len);
 	c->v.v2.remwindow -= len;
     }
@@ -4731,27 +5304,556 @@ static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
 {
     Ssh ssh = c->ssh;
 
-    /*
-     * Never send WINDOW_ADJUST for a channel that the remote side
-     * already thinks it's closed; there's no point, since it won't
-     * be sending any more data anyway.
-     */
-    if (c->closes != 0)
-	return;
+    /*
+     * Never send WINDOW_ADJUST for a channel that the remote side
+     * already thinks it's closed; there's no point, since it won't
+     * be sending any more data anyway.
+     */
+    if (c->closes != 0)
+	return;
+
+    if (newwin > c->v.v2.locwindow) {
+	struct Packet *pktout;
+
+	pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+	ssh2_pkt_adduint32(pktout, c->remoteid);
+	ssh2_pkt_adduint32(pktout, newwin - c->v.v2.locwindow);
+	ssh2_pkt_send(ssh, pktout);
+	c->v.v2.locwindow = newwin;
+    }
+}
+
+static void ssh2_msg_channel_window_adjust(Ssh ssh, struct Packet *pktin)
+{
+    unsigned i = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+    c = find234(ssh->channels, &i, ssh_channelfind);
+    if (c && !c->closes)
+	c->v.v2.remwindow += ssh_pkt_getuint32(pktin);
+}
+
+static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
+{
+    char *data;
+    unsigned int length;
+    unsigned i = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+    c = find234(ssh->channels, &i, ssh_channelfind);
+    if (!c)
+	return;			       /* nonexistent channel */
+    if (pktin->type == SSH2_MSG_CHANNEL_EXTENDED_DATA &&
+	ssh_pkt_getuint32(pktin) != SSH2_EXTENDED_DATA_STDERR)
+	return;			       /* extended but not stderr */
+    ssh_pkt_getstring(pktin, &data, &length);
+    if (data) {
+	int bufsize = 0;
+	c->v.v2.locwindow -= length;
+	switch (c->type) {
+	  case CHAN_MAINSESSION:
+	    bufsize =
+		from_backend(ssh->frontend, pktin->type ==
+			     SSH2_MSG_CHANNEL_EXTENDED_DATA,
+			     data, length);
+	    break;
+	  case CHAN_X11:
+	    bufsize = x11_send(c->u.x11.s, data, length);
+	    break;
+	  case CHAN_SOCKDATA:
+	    bufsize = pfd_send(c->u.pfd.s, data, length);
+	    break;
+	  case CHAN_AGENT:
+	    while (length > 0) {
+		if (c->u.a.lensofar < 4) {
+		    unsigned int l = min(4 - c->u.a.lensofar, length);
+		    memcpy(c->u.a.msglen + c->u.a.lensofar,
+			   data, l);
+		    data += l;
+		    length -= l;
+		    c->u.a.lensofar += l;
+		}
+		if (c->u.a.lensofar == 4) {
+		    c->u.a.totallen =
+			4 + GET_32BIT(c->u.a.msglen);
+		    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) {
+		    unsigned int l =
+			min(c->u.a.totallen - c->u.a.lensofar,
+			    length);
+		    memcpy(c->u.a.message + c->u.a.lensofar,
+			   data, l);
+		    data += l;
+		    length -= l;
+		    c->u.a.lensofar += l;
+		}
+		if (c->u.a.lensofar == c->u.a.totallen) {
+		    void *reply;
+		    int replylen;
+		    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;
+		}
+	    }
+	    bufsize = 0;
+	    break;
+	}
+	/*
+	 * If we are not buffering too much data,
+	 * enlarge the window again at the remote side.
+	 */
+	if (bufsize < OUR_V2_WINSIZE)
+	    ssh2_set_window(c, OUR_V2_WINSIZE - bufsize);
+    }
+}
+
+static void ssh2_msg_channel_eof(Ssh ssh, struct Packet *pktin)
+{
+    unsigned i = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+
+    c = find234(ssh->channels, &i, ssh_channelfind);
+    if (!c)
+	return;			       /* nonexistent channel */
+
+    if (c->type == CHAN_X11) {
+	/*
+	 * Remote EOF on an X11 channel means we should
+	 * wrap up and close the channel ourselves.
+	 */
+	x11_close(c->u.x11.s);
+	sshfwd_close(c);
+    } else if (c->type == CHAN_AGENT) {
+	sshfwd_close(c);
+    } else if (c->type == CHAN_SOCKDATA) {
+	pfd_close(c->u.pfd.s);
+	sshfwd_close(c);
+    }
+}
+
+static void ssh2_msg_channel_close(Ssh ssh, struct Packet *pktin)
+{
+    unsigned i = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+    struct Packet *pktout;
+
+    c = find234(ssh->channels, &i, ssh_channelfind);
+    if (!c || ((int)c->remoteid) == -1) {
+	bombout(("Received CHANNEL_CLOSE for %s channel %d\n",
+		 c ? "half-open" : "nonexistent", i));
+	return;
+    }
+    /* Do pre-close processing on the channel. */
+    switch (c->type) {
+      case CHAN_MAINSESSION:
+	ssh->mainchan = NULL;
+	update_specials_menu(ssh->frontend);
+	break;
+      case CHAN_X11:
+	if (c->u.x11.s != NULL)
+	    x11_close(c->u.x11.s);
+	sshfwd_close(c);
+	break;
+      case CHAN_AGENT:
+	sshfwd_close(c);
+	break;
+      case CHAN_SOCKDATA:
+	if (c->u.pfd.s != NULL)
+	    pfd_close(c->u.pfd.s);
+	sshfwd_close(c);
+	break;
+    }
+    if (c->closes == 0) {
+	pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
+	ssh2_pkt_adduint32(pktout, c->remoteid);
+	ssh2_pkt_send(ssh, pktout);
+    }
+    del234(ssh->channels, c);
+    bufchain_clear(&c->v.v2.outbuffer);
+    sfree(c);
+
+    /*
+     * See if that was the last channel left open.
+     * (This is only our termination condition if we're
+     * not running in -N mode.)
+     */
+    if (!ssh->cfg.ssh_no_shell && count234(ssh->channels) == 0) {
+	logevent("All channels closed. Disconnecting");
+#if 0
+	/*
+	 * We used to send SSH_MSG_DISCONNECT here,
+	 * because I'd believed that _every_ conforming
+	 * SSH2 connection had to end with a disconnect
+	 * being sent by at least one side; apparently
+	 * I was wrong and it's perfectly OK to
+	 * unceremoniously slam the connection shut
+	 * when you're done, and indeed OpenSSH feels
+	 * this is more polite than sending a
+	 * DISCONNECT. So now we don't.
+	 */
+	s->pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
+	ssh2_pkt_adduint32(s->pktout, SSH2_DISCONNECT_BY_APPLICATION);
+	ssh2_pkt_addstring(s->pktout, "All open channels closed");
+	ssh2_pkt_addstring(s->pktout, "en");	/* language tag */
+	ssh2_pkt_send_noqueue(ssh, s->pktout);
+#endif
+	ssh_closing((Plug)ssh, NULL, 0, 0);
+    }
+}
+
+static void ssh2_msg_channel_open_confirmation(Ssh ssh, struct Packet *pktin)
+{
+    unsigned i = ssh_pkt_getuint32(pktin);
+    struct ssh_channel *c;
+    struct Packet *pktout;
+
+    c = find234(ssh->channels, &i, ssh_channelfind);
+    if (!c)
+	return;			       /* nonexistent channel */
+    if (c->type != CHAN_SOCKDATA_DORMANT)
+	return;			       /* dunno why they're confirming this */
+    c->remoteid = ssh_pkt_getuint32(pktin);
+    c->type = CHAN_SOCKDATA;
+    c->v.v2.remwindow = ssh_pkt_getuint32(pktin);
+    c->v.v2.remmaxpkt = ssh_pkt_getuint32(pktin);
+    if (c->u.pfd.s)
+	pfd_confirm(c->u.pfd.s);
+    if (c->closes) {
+	/*
+	 * We have a pending close on this channel,
+	 * which we decided on before the server acked
+	 * the channel open. So now we know the
+	 * remoteid, we can close it again.
+	 */
+	pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
+	ssh2_pkt_adduint32(pktout, c->remoteid);
+	ssh2_pkt_send(ssh, pktout);
+    }
+}
+
+static void ssh2_msg_channel_open_failure(Ssh ssh, struct Packet *pktin)
+{
+    static const char *const reasons[] = {
+	"<unknown reason code>",
+	    "Administratively prohibited",
+	    "Connect failed",
+	    "Unknown channel type",
+	    "Resource shortage",
+    };
+    unsigned i = ssh_pkt_getuint32(pktin);
+    unsigned reason_code;
+    char *reason_string;
+    int reason_length;
+    char *message;
+    struct ssh_channel *c;
+    c = find234(ssh->channels, &i, ssh_channelfind);
+    if (!c)
+	return;			       /* nonexistent channel */
+    if (c->type != CHAN_SOCKDATA_DORMANT)
+	return;			       /* dunno why they're failing this */
+
+    reason_code = ssh_pkt_getuint32(pktin);
+    if (reason_code >= lenof(reasons))
+	reason_code = 0; /* ensure reasons[reason_code] in range */
+    ssh_pkt_getstring(pktin, &reason_string, &reason_length);
+    message = dupprintf("Forwarded connection refused by"
+			" server: %s [%.*s]", reasons[reason_code],
+			reason_length, reason_string);
+    logevent(message);
+    sfree(message);
+
+    pfd_close(c->u.pfd.s);
+
+    del234(ssh->channels, c);
+    sfree(c);
+}
+
+static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
+{
+    unsigned localid;
+    char *type;
+    int typelen, want_reply;
+    int reply = SSH2_MSG_CHANNEL_FAILURE; /* default */
+    struct ssh_channel *c;
+    struct Packet *pktout;
+
+    localid = ssh_pkt_getuint32(pktin);
+    ssh_pkt_getstring(pktin, &type, &typelen);
+    want_reply = ssh2_pkt_getbool(pktin);
+
+    /*
+     * First, check that the channel exists. Otherwise,
+     * we can instantly disconnect with a rude message.
+     */
+    c = find234(ssh->channels, &localid, ssh_channelfind);
+    if (!c) {
+	char buf[80];
+	sprintf(buf, "Received channel request for nonexistent"
+		" channel %d", localid);
+	logevent(buf);
+	pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
+	ssh2_pkt_adduint32(pktout, SSH2_DISCONNECT_BY_APPLICATION);
+	ssh2_pkt_addstring(pktout, buf);
+	ssh2_pkt_addstring(pktout, "en");	/* language tag */
+	ssh2_pkt_send_noqueue(ssh, pktout);
+	connection_fatal(ssh->frontend, "%s", buf);
+	ssh_closing((Plug)ssh, NULL, 0, 0);
+	return;
+    }
+
+    /*
+     * Having got the channel number, we now look at
+     * the request type string to see if it's something
+     * we recognise.
+     */
+    if (c == ssh->mainchan) {
+	/*
+	 * We recognise "exit-status" and "exit-signal" on
+	 * the primary channel.
+	 */
+	if (typelen == 11 &&
+	    !memcmp(type, "exit-status", 11)) {
+
+	    ssh->exitcode = ssh_pkt_getuint32(pktin);
+	    logeventf(ssh, "Server sent command exit status %d",
+		      ssh->exitcode);
+	    reply = SSH2_MSG_CHANNEL_SUCCESS;
+
+	} else if (typelen == 11 &&
+		   !memcmp(type, "exit-signal", 11)) {
+
+	    int is_plausible = TRUE, is_int = FALSE;
+	    char *fmt_sig = "", *fmt_msg = "";
+	    char *msg;
+	    int msglen = 0, core = FALSE;
+	    /* ICK: older versions of OpenSSH (e.g. 3.4p1)
+	     * provide an `int' for the signal, despite its
+	     * having been a `string' in the drafts since at
+	     * least 2001. (Fixed in session.c 1.147.) Try to
+	     * infer which we can safely parse it as. */
+	    {
+		unsigned char *p = pktin->body +
+		    pktin->savedpos;
+		long len = pktin->length - pktin->savedpos;
+		unsigned long num = GET_32BIT(p); /* what is it? */
+		/* If it's 0, it hardly matters; assume string */
+		if (num == 0) {
+		    is_int = FALSE;
+		} else {
+		    int maybe_int = FALSE, maybe_str = FALSE;
+#define CHECK_HYPOTHESIS(offset, result) \
+    do { \
+	long q = offset; \
+	if (q >= 0 && q+4 <= len) { \
+	    q = q + 4 + GET_32BIT(p+q); \
+	    if (q >= 0 && q+4 <= len && \
+		    (q = q + 4 + GET_32BIT(p+q)) && q == len) \
+		result = TRUE; \
+	} \
+    } while(0)
+		    CHECK_HYPOTHESIS(4+1, maybe_int);
+		    CHECK_HYPOTHESIS(4+num+1, maybe_str);
+#undef CHECK_HYPOTHESIS
+		    if (maybe_int && !maybe_str)
+			is_int = TRUE;
+		    else if (!maybe_int && maybe_str)
+			is_int = FALSE;
+		    else
+			/* Crikey. Either or neither. Panic. */
+			is_plausible = FALSE;
+		}
+	    }
+	    if (is_plausible) {
+		if (is_int) {
+		    /* Old non-standard OpenSSH. */
+		    int signum = ssh_pkt_getuint32(pktin);
+		    fmt_sig = dupprintf(" %d", signum);
+		} else {
+		    /* As per the drafts. */
+		    char *sig;
+		    int siglen;
+		    ssh_pkt_getstring(pktin, &sig, &siglen);
+		    /* Signal name isn't supposed to be blank, but
+		     * let's cope gracefully if it is. */
+		    if (siglen) {
+			fmt_sig = dupprintf(" \"%.*s\"",
+					    siglen, sig);
+		    }
+		}
+		core = ssh2_pkt_getbool(pktin);
+		ssh_pkt_getstring(pktin, &msg, &msglen);
+		if (msglen) {
+		    fmt_msg = dupprintf(" (\"%.*s\")", msglen, msg);
+		}
+		/* ignore lang tag */
+	    } /* else don't attempt to parse */
+	    logeventf(ssh, "Server exited on signal%s%s%s",
+		      fmt_sig, core ? " (core dumped)" : "",
+		      fmt_msg);
+	    if (*fmt_sig) sfree(fmt_sig);
+	    if (*fmt_msg) sfree(fmt_msg);
+	    reply = SSH2_MSG_CHANNEL_SUCCESS;
+
+	}
+    } else {
+	/*
+	 * This is a channel request we don't know
+	 * about, so we now either ignore the request
+	 * or respond with CHANNEL_FAILURE, depending
+	 * on want_reply.
+	 */
+	reply = SSH2_MSG_CHANNEL_FAILURE;
+    }
+    if (want_reply) {
+	pktout = ssh2_pkt_init(reply);
+	ssh2_pkt_adduint32(pktout, c->remoteid);
+	ssh2_pkt_send(ssh, pktout);
+    }
+}
+
+static void ssh2_msg_global_request(Ssh ssh, struct Packet *pktin)
+{
+    char *type;
+    int typelen, want_reply;
+    struct Packet *pktout;
+
+    ssh_pkt_getstring(pktin, &type, &typelen);
+    want_reply = ssh2_pkt_getbool(pktin);
+
+    /*
+     * We currently don't support any global requests
+     * at all, so we either ignore the request or
+     * respond with REQUEST_FAILURE, depending on
+     * want_reply.
+     */
+    if (want_reply) {
+	pktout = ssh2_pkt_init(SSH2_MSG_REQUEST_FAILURE);
+	ssh2_pkt_send(ssh, pktout);
+    }
+}
+
+static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
+{
+    char *type;
+    int typelen;
+    char *peeraddr;
+    int peeraddrlen;
+    int peerport;
+    char *error = NULL;
+    struct ssh_channel *c;
+    unsigned remid, winsize, pktsize;
+    struct Packet *pktout;
+
+    ssh_pkt_getstring(pktin, &type, &typelen);
+    c = snew(struct ssh_channel);
+    c->ssh = ssh;
+
+    remid = ssh_pkt_getuint32(pktin);
+    winsize = ssh_pkt_getuint32(pktin);
+    pktsize = ssh_pkt_getuint32(pktin);
+
+    if (typelen == 3 && !memcmp(type, "x11", 3)) {
+	char *addrstr;
+
+	ssh_pkt_getstring(pktin, &peeraddr, &peeraddrlen);
+	addrstr = snewn(peeraddrlen+1, char);
+	memcpy(addrstr, peeraddr, peeraddrlen);
+	addrstr[peeraddrlen] = '\0';
+	peerport = ssh_pkt_getuint32(pktin);
+
+	logeventf(ssh, "Received X11 connect request from %s:%d",
+		  addrstr, peerport);
 
-    if (newwin > c->v.v2.locwindow) {
-	ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-	ssh2_pkt_adduint32(ssh, c->remoteid);
-	ssh2_pkt_adduint32(ssh, newwin - c->v.v2.locwindow);
-	ssh2_pkt_send(ssh);
-	c->v.v2.locwindow = newwin;
+	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, peerport,
+			  &ssh->cfg) != NULL) {
+	    error = "Unable to open an X11 connection";
+	} else {
+	    logevent("Opening X11 forward connection succeeded");
+	    c->type = CHAN_X11;
+	}
+
+	sfree(addrstr);
+    } else if (typelen == 15 &&
+	       !memcmp(type, "forwarded-tcpip", 15)) {
+	struct ssh_rportfwd pf, *realpf;
+	char *dummy;
+	int dummylen;
+	ssh_pkt_getstring(pktin, &dummy, &dummylen);/* skip address */
+	pf.sport = ssh_pkt_getuint32(pktin);
+	ssh_pkt_getstring(pktin, &peeraddr, &peeraddrlen);
+	peerport = ssh_pkt_getuint32(pktin);
+	realpf = find234(ssh->rportfwds, &pf, NULL);
+	logeventf(ssh, "Received remote port %d open request "
+		  "from %s:%d", pf.sport, peeraddr, peerport);
+	if (realpf == NULL) {
+	    error = "Remote port is not recognised";
+	} else {
+	    const char *e = pfd_newconnect(&c->u.pfd.s,
+					   realpf->dhost,
+					   realpf->dport, c,
+					   &ssh->cfg);
+	    logeventf(ssh, "Attempting to forward remote port to "
+		      "%s:%d", realpf->dhost, realpf->dport);
+	    if (e != NULL) {
+		logeventf(ssh, "Port open failed: %s", e);
+		error = "Port open failed";
+	    } else {
+		logevent("Forwarded port opened successfully");
+		c->type = CHAN_SOCKDATA;
+	    }
+	}
+    } else if (typelen == 22 &&
+	       !memcmp(type, "auth-agent@openssh.com", 3)) {
+	if (!ssh->agentfwd_enabled)
+	    error = "Agent forwarding is not enabled";
+	else {
+	    c->type = CHAN_AGENT;	/* identify channel type */
+	    c->u.a.lensofar = 0;
+	}
+    } else {
+	error = "Unsupported channel type requested";
+    }
+
+    c->remoteid = remid;
+    if (error) {
+	pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_FAILURE);
+	ssh2_pkt_adduint32(pktout, c->remoteid);
+	ssh2_pkt_adduint32(pktout, SSH2_OPEN_CONNECT_FAILED);
+	ssh2_pkt_addstring(pktout, error);
+	ssh2_pkt_addstring(pktout, "en");	/* language tag */
+	ssh2_pkt_send(ssh, pktout);
+	logeventf(ssh, "Rejected channel open: %s", error);
+	sfree(c);
+    } else {
+	c->localid = alloc_channel_id(ssh);
+	c->closes = 0;
+	c->v.v2.locwindow = OUR_V2_WINSIZE;
+	c->v.v2.remwindow = winsize;
+	c->v.v2.remmaxpkt = pktsize;
+	bufchain_init(&c->v.v2.outbuffer);
+	add234(ssh->channels, c);
+	pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
+	ssh2_pkt_adduint32(pktout, c->remoteid);
+	ssh2_pkt_adduint32(pktout, c->localid);
+	ssh2_pkt_adduint32(pktout, c->v.v2.locwindow);
+	ssh2_pkt_adduint32(pktout, 0x4000UL);	/* our max pkt size */
+	ssh2_pkt_send(ssh, pktout);
     }
 }
 
 /*
  * Handle the SSH2 userauth and connection layers.
  */
-static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
+static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
+			     struct Packet *pktin)
 {
     struct do_ssh2_authconn_state {
 	enum {
@@ -4789,6 +5891,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	char *q, *agentreq, *ret;
 	int try_send;
 	int num_env, env_left, env_ok;
+	struct Packet *pktout;
     };
     crState(do_ssh2_authconn_state);
 
@@ -4797,11 +5900,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Request userauth protocol, and await a response to it.
      */
-    ssh2_pkt_init(ssh, SSH2_MSG_SERVICE_REQUEST);
-    ssh2_pkt_addstring(ssh, "ssh-userauth");
-    ssh2_pkt_send(ssh);
-    crWaitUntilV(ispkt);
-    if (ssh->pktin.type != SSH2_MSG_SERVICE_ACCEPT) {
+    s->pktout = ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
+    ssh2_pkt_addstring(s->pktout, "ssh-userauth");
+    ssh2_pkt_send(ssh, s->pktout);
+    crWaitUntilV(pktin);
+    if (pktin->type != SSH2_MSG_SERVICE_ACCEPT) {
 	bombout(("Server refused user authentication protocol"));
 	crStopV;
     }
@@ -4842,7 +5945,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	     * with change_username turned off we don't try to get
 	     * it again.
 	     */
-	} else if ((flags & FLAG_INTERACTIVE) && !*ssh->cfg.username) {
+	} else if (!*ssh->cfg.username) {
 	    if (ssh_get_line && !ssh_getline_pw_only) {
 		if (!ssh_get_line("login as: ",
 				  s->username, sizeof(s->username), FALSE)) {
@@ -4860,7 +5963,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		ssh->send_ok = 1;
 		setup_userpass_input(ssh, s->username, sizeof(s->username), 1);
 		do {
-		    crWaitUntilV(!ispkt);
+		    crWaitUntilV(!pktin);
 		    ret = process_userpass_input(ssh, in, inlen);
 		} while (ret == 0);
 		if (ret < 0)
@@ -4887,11 +5990,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	 */
 	ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
 
-	ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
-	ssh2_pkt_addstring(ssh, s->username);
-	ssh2_pkt_addstring(ssh, "ssh-connection");/* service requested */
-	ssh2_pkt_addstring(ssh, "none");    /* method */
-	ssh2_pkt_send(ssh);
+	s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+	ssh2_pkt_addstring(s->pktout, s->username);
+	ssh2_pkt_addstring(s->pktout, "ssh-connection");/* service requested */
+	ssh2_pkt_addstring(s->pktout, "none");    /* method */
+	ssh2_pkt_send(ssh, s->pktout);
 	s->type = AUTH_TYPE_NONE;
 	s->gotit = FALSE;
 	s->we_are_in = FALSE;
@@ -4930,8 +6033,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	     * Wait for the result of the last authentication request.
 	     */
 	    if (!s->gotit)
-		crWaitUntilV(ispkt);
-	    while (ssh->pktin.type == SSH2_MSG_USERAUTH_BANNER) {
+		crWaitUntilV(pktin);
+	    while (pktin->type == SSH2_MSG_USERAUTH_BANNER) {
 		char *banner;
 		int size;
 		/*
@@ -4943,20 +6046,20 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		 * output of (say) plink.)
 		 */
 		if (flags & (FLAG_VERBOSE | FLAG_INTERACTIVE)) {
-		    ssh_pkt_getstring(ssh, &banner, &size);
+		    ssh_pkt_getstring(pktin, &banner, &size);
 		    if (banner)
 			c_write_untrusted(ssh, banner, size);
 		}
-		crWaitUntilV(ispkt);
+		crWaitUntilV(pktin);
 	    }
-	    if (ssh->pktin.type == SSH2_MSG_USERAUTH_SUCCESS) {
+	    if (pktin->type == SSH2_MSG_USERAUTH_SUCCESS) {
 		logevent("Access granted");
 		s->we_are_in = TRUE;
 		break;
 	    }
 
 	    if (s->kbd_inter_running &&
-		ssh->pktin.type == SSH2_MSG_USERAUTH_INFO_REQUEST) {
+		pktin->type == SSH2_MSG_USERAUTH_INFO_REQUEST) {
 		/*
 		 * This is either a further set-of-prompts packet
 		 * in keyboard-interactive authentication, or it's
@@ -4966,9 +6069,9 @@ 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) {
+	    } else if (pktin->type != SSH2_MSG_USERAUTH_FAILURE) {
 		bombout(("Strange packet received during authentication: type %d",
-			 ssh->pktin.type));
+			 pktin->type));
 		crStopV;
 	    }
 
@@ -4979,12 +6082,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	     * we can look at the string in it and know what we can
 	     * helpfully try next.
 	     */
-	    if (ssh->pktin.type == SSH2_MSG_USERAUTH_FAILURE) {
+	    if (pktin->type == SSH2_MSG_USERAUTH_FAILURE) {
 		char *methods;
 		int methlen;
-		ssh_pkt_getstring(ssh, &methods, &methlen);
+		ssh_pkt_getstring(pktin, &methods, &methlen);
 		s->kbd_inter_running = FALSE;
-		if (!ssh2_pkt_getbool(ssh)) {
+		if (!ssh2_pkt_getbool(pktin)) {
 		    /*
 		     * We have received an unequivocal Access
 		     * Denied. This can translate to a variety of
@@ -5004,7 +6107,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		     * Additionally, if we'd just tried password
 		     * authentication, we should break out of this
 		     * whole loop so as to go back to the username
-		     * prompt.
+		     * prompt (iff we're configured to allow
+		     * username change attempts).
 		     */
 		    if (s->type == AUTH_TYPE_NONE) {
 			/* do nothing */
@@ -5018,7 +6122,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		    } else {
 			c_write_str(ssh, "Access denied\r\n");
 			logevent("Access denied");
-			if (s->type == AUTH_TYPE_PASSWORD) {
+			if (s->type == AUTH_TYPE_PASSWORD &&
+			    ssh->cfg.change_username) {
+			    /* XXX perhaps we should allow
+			     * keyboard-interactive to do this too? */
 			    s->we_are_in = FALSE;
 			    break;
 			}
@@ -5070,12 +6177,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 				 ssh_agent_callback, ssh)) {
 		    do {
 			crReturnV;
-			if (ispkt) {
+			if (pktin) {
 			    bombout(("Unexpected data from server while"
 				     " waiting for agent response"));
 			    crStopV;
 			}
-		    } while (ispkt || inlen > 0);
+		    } while (pktin || inlen > 0);
 		    r = ssh->agent_response;
 		    s->responselen = ssh->agent_response_len;
 		}
@@ -5115,19 +6222,19 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			s->p += 4;
 			s->commentp = (char *)s->p;
 			s->p += s->commentlen;
-			ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
-			ssh2_pkt_addstring(ssh, s->username);
-			ssh2_pkt_addstring(ssh, "ssh-connection");	/* service requested */
-			ssh2_pkt_addstring(ssh, "publickey");	/* method */
-			ssh2_pkt_addbool(ssh, FALSE);	/* no signature included */
-			ssh2_pkt_addstring_start(ssh);
-			ssh2_pkt_addstring_data(ssh, s->alg, s->alglen);
-			ssh2_pkt_addstring_start(ssh);
-			ssh2_pkt_addstring_data(ssh, s->pkblob, s->pklen);
-			ssh2_pkt_send(ssh);
-
-			crWaitUntilV(ispkt);
-			if (ssh->pktin.type != SSH2_MSG_USERAUTH_PK_OK) {
+			s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+			ssh2_pkt_addstring(s->pktout, s->username);
+			ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
+			ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
+			ssh2_pkt_addbool(s->pktout, FALSE);	/* no signature included */
+			ssh2_pkt_addstring_start(s->pktout);
+			ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
+			ssh2_pkt_addstring_start(s->pktout);
+			ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
+			ssh2_pkt_send(ssh, s->pktout);
+
+			crWaitUntilV(pktin);
+			if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
 			    logevent("Key refused");
 			    continue;
 			}
@@ -5143,17 +6250,17 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			 * Server is willing to accept the key.
 			 * Construct a SIGN_REQUEST.
 			 */
-			ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
-			ssh2_pkt_addstring(ssh, s->username);
-			ssh2_pkt_addstring(ssh, "ssh-connection");	/* service requested */
-			ssh2_pkt_addstring(ssh, "publickey");	/* method */
-			ssh2_pkt_addbool(ssh, TRUE);
-			ssh2_pkt_addstring_start(ssh);
-			ssh2_pkt_addstring_data(ssh, s->alg, s->alglen);
-			ssh2_pkt_addstring_start(ssh);
-			ssh2_pkt_addstring_data(ssh, s->pkblob, s->pklen);
-
-			s->siglen = ssh->pktout.length - 5 + 4 + 20;
+			s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+			ssh2_pkt_addstring(s->pktout, s->username);
+			ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
+			ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
+			ssh2_pkt_addbool(s->pktout, TRUE);
+			ssh2_pkt_addstring_start(s->pktout);
+			ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
+			ssh2_pkt_addstring_start(s->pktout);
+			ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
+
+			s->siglen = s->pktout->length - 5 + 4 + 20;
                         if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
                             s->siglen -= 4;
 			s->len = 1;       /* message type */
@@ -5177,9 +6284,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                         }
 			memcpy(s->q, ssh->v2_session_id, 20);
 			s->q += 20;
-			memcpy(s->q, ssh->pktout.data + 5,
-			       ssh->pktout.length - 5);
-			s->q += ssh->pktout.length - 5;
+			memcpy(s->q, s->pktout->data + 5,
+			       s->pktout->length - 5);
+			s->q += s->pktout->length - 5;
 			/* And finally the (zero) flags word. */
 			PUT_32BIT(s->q, 0);
 			if (!agent_query(s->agentreq, s->len + 4,
@@ -5187,13 +6294,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 					 ssh_agent_callback, ssh)) {
 			    do {
 				crReturnV;
-				if (ispkt) {
+				if (pktin) {
 				    bombout(("Unexpected data from server"
 					     " while waiting for agent"
 					     " response"));
 				    crStopV;
 				}
-			    } while (ispkt || inlen > 0);
+			    } while (pktin || inlen > 0);
 			    vret = ssh->agent_response;
 			    s->retlen = ssh->agent_response_len;
 			}
@@ -5202,10 +6309,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			if (s->ret) {
 			    if (s->ret[4] == SSH2_AGENT_SIGN_RESPONSE) {
 				logevent("Sending Pageant's response");
-				ssh2_add_sigblob(ssh, s->pkblob, s->pklen,
+				ssh2_add_sigblob(ssh, s->pktout,
+						 s->pkblob, s->pklen,
 						 s->ret + 9,
 						 GET_32BIT(s->ret + 5));
-				ssh2_pkt_send(ssh);
+				ssh2_pkt_send(ssh, s->pktout);
 				s->authed = TRUE;
 				break;
 			    } else {
@@ -5244,20 +6352,20 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 							  &pub_blob_len,
 							  NULL);
 		if (pub_blob) {
-		    ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
-		    ssh2_pkt_addstring(ssh, s->username);
-		    ssh2_pkt_addstring(ssh, "ssh-connection");	/* service requested */
-		    ssh2_pkt_addstring(ssh, "publickey");	/* method */
-		    ssh2_pkt_addbool(ssh, FALSE);	/* no signature included */
-		    ssh2_pkt_addstring(ssh, algorithm);
-		    ssh2_pkt_addstring_start(ssh);
-		    ssh2_pkt_addstring_data(ssh, (char *)pub_blob,
+		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+		    ssh2_pkt_addstring(s->pktout, s->username);
+		    ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
+		    ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
+		    ssh2_pkt_addbool(s->pktout, FALSE);	/* no signature included */
+		    ssh2_pkt_addstring(s->pktout, algorithm);
+		    ssh2_pkt_addstring_start(s->pktout);
+		    ssh2_pkt_addstring_data(s->pktout, (char *)pub_blob,
 					    pub_blob_len);
-		    ssh2_pkt_send(ssh);
-		    logevent("Offered public key");	/* FIXME */
+		    ssh2_pkt_send(ssh, s->pktout);
+		    logevent("Offered public key");
 
-		    crWaitUntilV(ispkt);
-		    if (ssh->pktin.type != SSH2_MSG_USERAUTH_PK_OK) {
+		    crWaitUntilV(pktin);
+		    if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
 			s->gotit = TRUE;
 			s->type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD;
 			continue;      /* key refused; give up on it */
@@ -5293,17 +6401,17 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
 		ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
 
-		ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
-		ssh2_pkt_addstring(ssh, s->username);
-		ssh2_pkt_addstring(ssh, "ssh-connection");	/* service requested */
-		ssh2_pkt_addstring(ssh, "keyboard-interactive");	/* method */
-		ssh2_pkt_addstring(ssh, ""); /* lang */
-		ssh2_pkt_addstring(ssh, "");
-		ssh2_pkt_send(ssh);
-
-		crWaitUntilV(ispkt);
-		if (ssh->pktin.type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
-		    if (ssh->pktin.type == SSH2_MSG_USERAUTH_FAILURE)
+		s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+		ssh2_pkt_addstring(s->pktout, s->username);
+		ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
+		ssh2_pkt_addstring(s->pktout, "keyboard-interactive");	/* method */
+		ssh2_pkt_addstring(s->pktout, ""); /* lang */
+		ssh2_pkt_addstring(s->pktout, "");
+		ssh2_pkt_send(ssh, s->pktout);
+
+		crWaitUntilV(pktin);
+		if (pktin->type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
+		    if (pktin->type == SSH2_MSG_USERAUTH_FAILURE)
 			s->gotit = TRUE;
 		    logevent("Keyboard-interactive authentication refused");
 		    s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET;
@@ -5331,9 +6439,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		    char *name, *inst, *lang;
 		    int name_len, inst_len, lang_len;
 
-		    ssh_pkt_getstring(ssh, &name, &name_len);
-		    ssh_pkt_getstring(ssh, &inst, &inst_len);
-		    ssh_pkt_getstring(ssh, &lang, &lang_len);
+		    ssh_pkt_getstring(pktin, &name, &name_len);
+		    ssh_pkt_getstring(pktin, &inst, &inst_len);
+		    ssh_pkt_getstring(pktin, &lang, &lang_len);
 		    if (name_len > 0) {
 			c_write_untrusted(ssh, name, name_len);
 			c_write_str(ssh, "\r\n");
@@ -5342,7 +6450,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			c_write_untrusted(ssh, inst, inst_len);
 			c_write_str(ssh, "\r\n");
 		    }
-		    s->num_prompts = ssh_pkt_getuint32(ssh);
+		    s->num_prompts = ssh_pkt_getuint32(pktin);
 		}
 
 		/*
@@ -5353,7 +6461,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		    char *prompt;
 		    int prompt_len;
 
-		    ssh_pkt_getstring(ssh, &prompt, &prompt_len);
+		    ssh_pkt_getstring(pktin, &prompt, &prompt_len);
 		    if (prompt_len > 0) {
 			static const char trunc[] = "<prompt truncated>: ";
 			static const int prlen = sizeof(s->pwprompt) -
@@ -5369,7 +6477,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			strcpy(s->pwprompt,
 			       "<server failed to send prompt>: ");
 		    }
-		    s->echo = ssh2_pkt_getbool(ssh);
+		    s->echo = ssh2_pkt_getbool(pktin);
 		    s->need_pw = TRUE;
 		} else
 		    s->need_pw = FALSE;
@@ -5394,12 +6502,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			 * command line which has already failed to
 			 * work). Terminate.
 			 */
-			ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
-			ssh2_pkt_adduint32(ssh,SSH2_DISCONNECT_BY_APPLICATION);
-			ssh2_pkt_addstring(ssh, "No more passwords available"
+			s->pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
+			ssh2_pkt_adduint32(s->pktout,SSH2_DISCONNECT_BY_APPLICATION);
+			ssh2_pkt_addstring(s->pktout, "No more passwords available"
 					   " to try");
-			ssh2_pkt_addstring(ssh, "en");	/* language tag */
-			ssh2_pkt_send(ssh);
+			ssh2_pkt_addstring(s->pktout, "en");	/* language tag */
+			ssh2_pkt_send_noqueue(ssh, s->pktout);
 			logevent("Unable to authenticate");
 			connection_fatal(ssh->frontend,
 					 "Unable to authenticate");
@@ -5414,7 +6522,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		    setup_userpass_input(ssh, s->password,
 					 sizeof(s->password), s->echo);
 		    do {
-			crWaitUntilV(!ispkt);
+			crWaitUntilV(!pktin);
 			ret = process_userpass_input(ssh, in, inlen);
 		    } while (ret == 0);
 		    if (ret < 0)
@@ -5443,11 +6551,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			s->tried_pubkey_config = TRUE;
 		    }
 		    /* Send a spurious AUTH_NONE to return to the top. */
-		    ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
-		    ssh2_pkt_addstring(ssh, s->username);
-		    ssh2_pkt_addstring(ssh, "ssh-connection");	/* service requested */
-		    ssh2_pkt_addstring(ssh, "none");	/* method */
-		    ssh2_pkt_send(ssh);
+		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+		    ssh2_pkt_addstring(s->pktout, s->username);
+		    ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
+		    ssh2_pkt_addstring(s->pktout, "none");	/* method */
+		    ssh2_pkt_send(ssh, s->pktout);
 		    s->type = AUTH_TYPE_NONE;
 		} else {
 		    unsigned char *pkblob, *sigblob, *sigdata;
@@ -5459,15 +6567,15 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		     * has announced that it's willing to accept it.
 		     * Hallelujah. Generate a signature and send it.
 		     */
-		    ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
-		    ssh2_pkt_addstring(ssh, s->username);
-		    ssh2_pkt_addstring(ssh, "ssh-connection");	/* service requested */
-		    ssh2_pkt_addstring(ssh, "publickey");	/* method */
-		    ssh2_pkt_addbool(ssh, TRUE);
-		    ssh2_pkt_addstring(ssh, key->alg->name);
+		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+		    ssh2_pkt_addstring(s->pktout, s->username);
+		    ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
+		    ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
+		    ssh2_pkt_addbool(s->pktout, TRUE);
+		    ssh2_pkt_addstring(s->pktout, key->alg->name);
 		    pkblob = key->alg->public_blob(key->data, &pkblob_len);
-		    ssh2_pkt_addstring_start(ssh);
-		    ssh2_pkt_addstring_data(ssh, (char *)pkblob, pkblob_len);
+		    ssh2_pkt_addstring_start(s->pktout);
+		    ssh2_pkt_addstring_data(s->pktout, (char *)pkblob, pkblob_len);
 
 		    /*
 		     * The data to be signed is:
@@ -5477,7 +6585,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		     * followed by everything so far placed in the
 		     * outgoing packet.
 		     */
-		    sigdata_len = ssh->pktout.length - 5 + 4 + 20;
+		    sigdata_len = s->pktout->length - 5 + 4 + 20;
                     if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
                         sigdata_len -= 4;
 		    sigdata = snewn(sigdata_len, unsigned char);
@@ -5487,19 +6595,19 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                         p += 4;
                     }
 		    memcpy(sigdata+p, ssh->v2_session_id, 20); p += 20;
-		    memcpy(sigdata+p, ssh->pktout.data + 5,
-			   ssh->pktout.length - 5);
-                    p += ssh->pktout.length - 5;
+		    memcpy(sigdata+p, s->pktout->data + 5,
+			   s->pktout->length - 5);
+                    p += s->pktout->length - 5;
                     assert(p == sigdata_len);
 		    sigblob = key->alg->sign(key->data, (char *)sigdata,
 					     sigdata_len, &sigblob_len);
-		    ssh2_add_sigblob(ssh, pkblob, pkblob_len,
+		    ssh2_add_sigblob(ssh, s->pktout, pkblob, pkblob_len,
 				     sigblob, sigblob_len);
 		    sfree(pkblob);
 		    sfree(sigblob);
 		    sfree(sigdata);
 
-		    ssh2_pkt_send(ssh);
+		    ssh2_pkt_send(ssh, s->pktout);
 		    s->type = AUTH_TYPE_PUBLICKEY;
 		    key->alg->freekey(key->data);
 		}
@@ -5518,16 +6626,16 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 		 * that probably doesn't have much to worry about from
 		 * people who find out how long their password is!
 		 */
-		ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
-		ssh2_pkt_addstring(ssh, s->username);
-		ssh2_pkt_addstring(ssh, "ssh-connection");	/* service requested */
-		ssh2_pkt_addstring(ssh, "password");
-		ssh2_pkt_addbool(ssh, FALSE);
-		dont_log_password(ssh, PKTLOG_BLANK);
-		ssh2_pkt_addstring(ssh, s->password);
+		s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+		ssh2_pkt_addstring(s->pktout, s->username);
+		ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
+		ssh2_pkt_addstring(s->pktout, "password");
+		ssh2_pkt_addbool(s->pktout, FALSE);
+		dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
+		ssh2_pkt_addstring(s->pktout, s->password);
 		memset(s->password, 0, sizeof(s->password));
-		end_log_omission(ssh);
-		ssh2_pkt_defer(ssh);
+		end_log_omission(ssh, s->pktout);
+		ssh2_pkt_defer(ssh, s->pktout);
 		/*
 		 * We'll include a string that's an exact multiple of the
 		 * cipher block size. If the cipher is NULL for some
@@ -5553,31 +6661,31 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			stringlen -= 
 			    ssh->cscomp->disable_compression(ssh->cs_comp_ctx);
 		    }
-		    ssh2_pkt_init(ssh, SSH2_MSG_IGNORE);
-		    ssh2_pkt_addstring_start(ssh);
+		    s->pktout = ssh2_pkt_init(SSH2_MSG_IGNORE);
+		    ssh2_pkt_addstring_start(s->pktout);
 		    for (i = 0; i < stringlen; i++) {
 			char c = (char) random_byte();
-			ssh2_pkt_addstring_data(ssh, &c, 1);
+			ssh2_pkt_addstring_data(s->pktout, &c, 1);
 		    }
-		    ssh2_pkt_defer(ssh);
+		    ssh2_pkt_defer(ssh, s->pktout);
 		}
 		ssh_pkt_defersend(ssh);
 		logevent("Sent password");
 		s->type = AUTH_TYPE_PASSWORD;
 	    } else if (s->method == AUTH_KEYBOARD_INTERACTIVE) {
 		if (s->curr_prompt == 0) {
-		    ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE);
-		    ssh2_pkt_adduint32(ssh, s->num_prompts);
+		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
+		    ssh2_pkt_adduint32(s->pktout, s->num_prompts);
 		}
 		if (s->need_pw) {      /* only add pw if we just got one! */
-		    dont_log_password(ssh, PKTLOG_BLANK);
-		    ssh2_pkt_addstring(ssh, s->password);
+		    dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
+		    ssh2_pkt_addstring(s->pktout, s->password);
 		    memset(s->password, 0, sizeof(s->password));
-		    end_log_omission(ssh);
+		    end_log_omission(ssh, s->pktout);
 		    s->curr_prompt++;
 		}
 		if (s->curr_prompt >= s->num_prompts) {
-		    ssh2_pkt_send(ssh);
+		    ssh2_pkt_send(ssh, s->pktout);
 		} else {
 		    /*
 		     * If there are prompts remaining, we set
@@ -5595,12 +6703,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 			    " left to try!\r\n");
 		logevent("No supported authentications offered."
 			 " Disconnecting");
-		ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
-		ssh2_pkt_adduint32(ssh, SSH2_DISCONNECT_BY_APPLICATION);
-		ssh2_pkt_addstring(ssh, "No supported authentication"
+		s->pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
+		ssh2_pkt_adduint32(s->pktout, SSH2_DISCONNECT_BY_APPLICATION);
+		ssh2_pkt_addstring(s->pktout, "No supported authentication"
 				   " methods available");
-		ssh2_pkt_addstring(ssh, "en");	/* language tag */
-		ssh2_pkt_send(ssh);
+		ssh2_pkt_addstring(s->pktout, "en");	/* language tag */
+		ssh2_pkt_send_noqueue(ssh, s->pktout);
                 ssh_closing((Plug)ssh, NULL, 0, 0);
 		crStopV;
 	    }
@@ -5616,41 +6724,69 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     ssh->channels = newtree234(ssh_channelcmp);
 
     /*
+     * Set up handlers for some connection protocol messages, so we
+     * don't have to handle them repeatedly in this coroutine.
+     */
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] =
+	ssh2_msg_channel_window_adjust;
+    ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] =
+	ssh2_msg_global_request;
+
+    /*
      * Create the main session channel.
      */
     if (!ssh->cfg.ssh_no_shell) {
 	ssh->mainchan = snew(struct ssh_channel);
 	ssh->mainchan->ssh = ssh;
 	ssh->mainchan->localid = alloc_channel_id(ssh);
-	ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN);
-	ssh2_pkt_addstring(ssh, "session");
-	ssh2_pkt_adduint32(ssh, ssh->mainchan->localid);
+	s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
+	ssh2_pkt_addstring(s->pktout, "session");
+	ssh2_pkt_adduint32(s->pktout, ssh->mainchan->localid);
 	ssh->mainchan->v.v2.locwindow = OUR_V2_WINSIZE;
-	ssh2_pkt_adduint32(ssh, ssh->mainchan->v.v2.locwindow);/* our window size */
-	ssh2_pkt_adduint32(ssh, 0x4000UL);      /* our max pkt size */
-	ssh2_pkt_send(ssh);
-	crWaitUntilV(ispkt);
-	if (ssh->pktin.type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
+	ssh2_pkt_adduint32(s->pktout, ssh->mainchan->v.v2.locwindow);/* our window size */
+	ssh2_pkt_adduint32(s->pktout, 0x4000UL);      /* our max pkt size */
+	ssh2_pkt_send(ssh, s->pktout);
+	crWaitUntilV(pktin);
+	if (pktin->type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
 	    bombout(("Server refused to open a session"));
 	    crStopV;
 	    /* FIXME: error data comes back in FAILURE packet */
 	}
-	if (ssh_pkt_getuint32(ssh) != ssh->mainchan->localid) {
+	if (ssh_pkt_getuint32(pktin) != ssh->mainchan->localid) {
 	    bombout(("Server's channel confirmation cited wrong channel"));
 	    crStopV;
 	}
-	ssh->mainchan->remoteid = ssh_pkt_getuint32(ssh);
+	ssh->mainchan->remoteid = ssh_pkt_getuint32(pktin);
 	ssh->mainchan->type = CHAN_MAINSESSION;
 	ssh->mainchan->closes = 0;
-	ssh->mainchan->v.v2.remwindow = ssh_pkt_getuint32(ssh);
-	ssh->mainchan->v.v2.remmaxpkt = ssh_pkt_getuint32(ssh);
+	ssh->mainchan->v.v2.remwindow = ssh_pkt_getuint32(pktin);
+	ssh->mainchan->v.v2.remmaxpkt = ssh_pkt_getuint32(pktin);
 	bufchain_init(&ssh->mainchan->v.v2.outbuffer);
 	add234(ssh->channels, ssh->mainchan);
+	update_specials_menu(ssh->frontend);
 	logevent("Opened channel for session");
     } else
 	ssh->mainchan = NULL;
 
     /*
+     * Now we have a channel, make dispatch table entries for
+     * general channel-based messages.
+     */
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] =
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] =
+	ssh2_msg_channel_data;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_channel_eof;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_channel_close;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] =
+	ssh2_msg_channel_open_confirmation;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] =
+	ssh2_msg_channel_open_failure;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] =
+	ssh2_msg_channel_request;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] =
+	ssh2_msg_channel_open;
+
+    /*
      * Potentially enable X11 forwarding.
      */
     if (ssh->mainchan && ssh->cfg.x11_forward) {
@@ -5659,32 +6795,22 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
 				       data, sizeof(data), ssh->cfg.x11_auth);
         x11_get_real_auth(ssh->x11auth, ssh->cfg.x11_display);
-	ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
-	ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
-	ssh2_pkt_addstring(ssh, "x11-req");
-	ssh2_pkt_addbool(ssh, 1);	       /* want reply */
-	ssh2_pkt_addbool(ssh, 0);	       /* many connections */
-	ssh2_pkt_addstring(ssh, proto);
-	ssh2_pkt_addstring(ssh, data);
-	ssh2_pkt_adduint32(ssh, x11_get_screen_number(ssh->cfg.x11_display));
-	ssh2_pkt_send(ssh);
-
-	do {
-	    crWaitUntilV(ispkt);
-	    if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c)
-		    continue;	       /* nonexistent channel */
-		c->v.v2.remwindow += ssh_pkt_getuint32(ssh);
-	    }
-	} 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) {
+	s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+	ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
+	ssh2_pkt_addstring(s->pktout, "x11-req");
+	ssh2_pkt_addbool(s->pktout, 1);	       /* want reply */
+	ssh2_pkt_addbool(s->pktout, 0);	       /* many connections */
+	ssh2_pkt_addstring(s->pktout, proto);
+	ssh2_pkt_addstring(s->pktout, data);
+	ssh2_pkt_adduint32(s->pktout, x11_get_screen_number(ssh->cfg.x11_display));
+	ssh2_pkt_send(ssh, s->pktout);
+
+	crWaitUntilV(pktin);
+
+	if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
+	    if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
 		bombout(("Unexpected response to X11 forwarding request:"
-			 " packet type %d", ssh->pktin.type));
+			 " packet type %d", pktin->type));
 		crStopV;
 	    }
 	    logevent("X11 forwarding refused");
@@ -5697,199 +6823,25 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Enable port forwardings.
      */
-    {
-	char type;
-	int n;
-	int sport,dport,sserv,dserv;
-	char sports[256], dports[256], saddr[256], host[256];
-
-	ssh->rportfwds = newtree234(ssh_rportcmp_ssh2);
-        /* Add port forwardings. */
-	ssh->portfwd_strptr = ssh->cfg.portfwd;
-	while (*ssh->portfwd_strptr) {
-	    type = *ssh->portfwd_strptr++;
-	    saddr[0] = '\0';
-	    n = 0;
-	    while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != '\t') {
-		if (*ssh->portfwd_strptr == ':') {
-		    /*
-		     * We've seen a colon in the middle of the
-		     * source port number. This means that
-		     * everything we've seen until now is the
-		     * source _address_, so we'll move it into
-		     * saddr and start sports from the beginning
-		     * again.
-		     */
-		    ssh->portfwd_strptr++;
-		    sports[n] = '\0';
-		    strcpy(saddr, sports);
-		    n = 0;
-		}
-		if (n < 255) sports[n++] = *ssh->portfwd_strptr++;
-	    }
-	    sports[n] = 0;
-	    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++;
-		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;
-	    if (sport == 0) {
-		sserv = 1;
-		sport = net_service_lookup(sports);
-		if (!sport) {
-		    logeventf(ssh, "Service lookup failed for source"
-			      " port \"%s\"", sports);
-		}
-	    }
-	    if (sport && dport) {
-		/* Set up a description of the source port. */
-		char *sportdesc = dupprintf("%.*s%.*s%.*s%.*s%d%.*s",
-			(int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
-			(int)(*saddr?1:0), ":",
-			(int)(sserv ? strlen(sports) : 0), sports,
-			sserv, "(", sport, sserv, ")");
-		if (type == 'L') {
-		    /* Verbose description of the destination port */
-		    char *dportdesc = dupprintf("%s:%.*s%.*s%d%.*s",
-			    host,
-			    (int)(dserv ? strlen(dports) : 0), dports,
-			    dserv, "(", dport, dserv, ")");
-		    const char *err = pfd_addforward(host, dport,
-						     *saddr ? saddr : NULL,
-						     sport, ssh, &ssh->cfg);
-		    if (err) {
-			logeventf(ssh, "Local port %s forward to %s"
-				  " failed: %s", sportdesc, dportdesc, err);
-		    } else {
-			logeventf(ssh, "Local port %s forwarding to %s",
-				  sportdesc, dportdesc);
-		    }
-		    sfree(dportdesc);
-		} else if (type == 'D') {
-		    const char *err = pfd_addforward(NULL, -1,
-						     *saddr ? saddr : NULL,
-						     sport, ssh, &ssh->cfg);
-		    if (err) {
-			logeventf(ssh, "Local port %s SOCKS dynamic forward"
-				  " setup failed: %s", sportdesc, err);
-		    } else {
-			logeventf(ssh, "Local port %s doing SOCKS"
-				  " dynamic forwarding", sportdesc);
-		    }
-		} else {
-		    struct ssh_rportfwd *pf;
-		    pf = snew(struct ssh_rportfwd);
-		    strcpy(pf->dhost, host);
-		    pf->dport = dport;
-		    pf->sport = sport;
-		    if (add234(ssh->rportfwds, pf) != pf) {
-			logeventf(ssh, "Duplicate remote port forwarding"
-				  " to %s:%d", host, dport);
-			sfree(pf);
-		    } else {
-			logeventf(ssh, "Requesting remote port %s"
-				  " forward to %s:%.*s%.*s%d%.*s",
-				  sportdesc,
-				  host,
-				  (int)(dserv ? strlen(dports) : 0), dports,
-				  dserv, "(", dport, dserv, ")");
-			ssh2_pkt_init(ssh, SSH2_MSG_GLOBAL_REQUEST);
-			ssh2_pkt_addstring(ssh, "tcpip-forward");
-			ssh2_pkt_addbool(ssh, 1);/* want reply */
-			if (*saddr)
-			    ssh2_pkt_addstring(ssh, saddr);
-			if (ssh->cfg.rport_acceptall)
-			    ssh2_pkt_addstring(ssh, "0.0.0.0");
-			else
-			    ssh2_pkt_addstring(ssh, "127.0.0.1");
-			ssh2_pkt_adduint32(ssh, sport);
-			ssh2_pkt_send(ssh);
-
-			do {
-			    crWaitUntilV(ispkt);
-			    if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-				unsigned i = ssh_pkt_getuint32(ssh);
-				struct ssh_channel *c;
-				c = find234(ssh->channels, &i, ssh_channelfind);
-				if (!c)
-				    continue;/* nonexistent channel */
-				c->v.v2.remwindow += ssh_pkt_getuint32(ssh);
-			    }
-			} while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-
-			if (ssh->pktin.type != SSH2_MSG_REQUEST_SUCCESS) {
-			    if (ssh->pktin.type != SSH2_MSG_REQUEST_FAILURE) {
-				bombout(("Unexpected response to port "
-					 "forwarding request: packet type %d",
-					 ssh->pktin.type));
-				crStopV;
-			    }
-			    logevent("Server refused this port forwarding");
-			} else {
-			    logevent("Remote port forwarding enabled");
-			}
-		    }
-		}
-		sfree(sportdesc);
-	    }
-	}
-    }
+    ssh_setup_portfwd(ssh, &ssh->cfg);
 
     /*
      * Potentially enable agent forwarding.
      */
     if (ssh->mainchan && ssh->cfg.agentfwd && agent_exists()) {
 	logevent("Requesting OpenSSH-style agent forwarding");
-	ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
-	ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
-	ssh2_pkt_addstring(ssh, "auth-agent-req@openssh.com");
-	ssh2_pkt_addbool(ssh, 1);	       /* want reply */
-	ssh2_pkt_send(ssh);
+	s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+	ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
+	ssh2_pkt_addstring(s->pktout, "auth-agent-req@openssh.com");
+	ssh2_pkt_addbool(s->pktout, 1);	       /* want reply */
+	ssh2_pkt_send(ssh, s->pktout);
 
-	do {
-	    crWaitUntilV(ispkt);
-	    if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c)
-		    continue;	       /* nonexistent channel */
-		c->v.v2.remwindow += ssh_pkt_getuint32(ssh);
-	    }
-	} while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+	crWaitUntilV(pktin);
 
-	if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
-	    if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
+	if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
+	    if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
 		bombout(("Unexpected response to agent forwarding request:"
-			 " packet type %d", ssh->pktin.type));
+			 " packet type %d", pktin->type));
 		crStopV;
 	    }
 	    logevent("Agent forwarding refused");
@@ -5908,40 +6860,30 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
         ssh->ospeed = 38400; ssh->ispeed = 38400; /* last-resort defaults */
 	sscanf(ssh->cfg.termspeed, "%d,%d", &ssh->ospeed, &ssh->ispeed);
 	/* Build the pty request. */
-	ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
-	ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);	/* recipient channel */
-	ssh2_pkt_addstring(ssh, "pty-req");
-	ssh2_pkt_addbool(ssh, 1);	       /* want reply */
-	ssh2_pkt_addstring(ssh, ssh->cfg.termtype);
-	ssh2_pkt_adduint32(ssh, ssh->term_width);
-	ssh2_pkt_adduint32(ssh, ssh->term_height);
-	ssh2_pkt_adduint32(ssh, 0);	       /* pixel width */
-	ssh2_pkt_adduint32(ssh, 0);	       /* pixel height */
-	ssh2_pkt_addstring_start(ssh);
-	ssh2_pkt_addbyte(ssh, 128);	       /* TTY_OP_ISPEED */
-	ssh2_pkt_adduint32(ssh, ssh->ispeed);
-	ssh2_pkt_addbyte(ssh, 129);	       /* TTY_OP_OSPEED */
-	ssh2_pkt_adduint32(ssh, ssh->ospeed);
-	ssh2_pkt_addstring_data(ssh, "\0", 1); /* TTY_OP_END */
-	ssh2_pkt_send(ssh);
+	s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+	ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);	/* recipient channel */
+	ssh2_pkt_addstring(s->pktout, "pty-req");
+	ssh2_pkt_addbool(s->pktout, 1);	       /* want reply */
+	ssh2_pkt_addstring(s->pktout, ssh->cfg.termtype);
+	ssh2_pkt_adduint32(s->pktout, ssh->term_width);
+	ssh2_pkt_adduint32(s->pktout, ssh->term_height);
+	ssh2_pkt_adduint32(s->pktout, 0);	       /* pixel width */
+	ssh2_pkt_adduint32(s->pktout, 0);	       /* pixel height */
+	ssh2_pkt_addstring_start(s->pktout);
+	ssh2_pkt_addbyte(s->pktout, 128);	       /* TTY_OP_ISPEED */
+	ssh2_pkt_adduint32(s->pktout, ssh->ispeed);
+	ssh2_pkt_addbyte(s->pktout, 129);	       /* TTY_OP_OSPEED */
+	ssh2_pkt_adduint32(s->pktout, ssh->ospeed);
+	ssh2_pkt_addstring_data(s->pktout, "\0", 1); /* TTY_OP_END */
+	ssh2_pkt_send(ssh, s->pktout);
 	ssh->state = SSH_STATE_INTERMED;
 
-	do {
-	    crWaitUntilV(ispkt);
-	    if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c)
-		    continue;	       /* nonexistent channel */
-		c->v.v2.remwindow += ssh_pkt_getuint32(ssh);
-	    }
-	} while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+	crWaitUntilV(pktin);
 
-	if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
-	    if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
+	if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
+	    if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
 		bombout(("Unexpected response to pty request:"
-			 " packet type %d", ssh->pktin.type));
+			 " packet type %d", pktin->type));
 		crStopV;
 	    }
 	    c_write_str(ssh, "Server refused to allocate pty\r\n");
@@ -5975,14 +6917,14 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    while (*e) e++;
 	    e++;
 
-	    ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
-	    ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
-	    ssh2_pkt_addstring(ssh, "env");
-	    ssh2_pkt_addbool(ssh, 1);	       /* want reply */
-	    ssh2_pkt_addstring_start(ssh);
-	    ssh2_pkt_addstring_data(ssh, var, varend-var);
-	    ssh2_pkt_addstring(ssh, val);
-	    ssh2_pkt_send(ssh);
+	    s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+	    ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
+	    ssh2_pkt_addstring(s->pktout, "env");
+	    ssh2_pkt_addbool(s->pktout, 1);	       /* want reply */
+	    ssh2_pkt_addstring_start(s->pktout);
+	    ssh2_pkt_addstring_data(s->pktout, var, varend-var);
+	    ssh2_pkt_addstring(s->pktout, val);
+	    ssh2_pkt_send(ssh, s->pktout);
 
 	    s->num_env++;
 	}
@@ -5993,22 +6935,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	s->env_left = s->num_env;
 
 	while (s->env_left > 0) {
-	    do {
-		crWaitUntilV(ispkt);
-		if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-		    unsigned i = ssh_pkt_getuint32(ssh);
-		    struct ssh_channel *c;
-		    c = find234(ssh->channels, &i, ssh_channelfind);
-		    if (!c)
-			continue;	       /* nonexistent channel */
-		    c->v.v2.remwindow += ssh_pkt_getuint32(ssh);
-		}
-	    } while (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+	    crWaitUntilV(pktin);
 
-	    if (ssh->pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
-		if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
+	    if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
+		if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
 		    bombout(("Unexpected response to environment request:"
-			     " packet type %d", ssh->pktin.type));
+			     " packet type %d", pktin->type));
 		    crStopV;
 		}
 	    } else {
@@ -6047,36 +6979,28 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 	    cmd = ssh->cfg.remote_cmd_ptr;
 	}
 
-	ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
-	ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);	/* recipient channel */
+	s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+	ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);	/* recipient channel */
 	if (subsys) {
-	    ssh2_pkt_addstring(ssh, "subsystem");
-	    ssh2_pkt_addbool(ssh, 1);	       /* want reply */
-	    ssh2_pkt_addstring(ssh, cmd);
+	    ssh2_pkt_addstring(s->pktout, "subsystem");
+	    ssh2_pkt_addbool(s->pktout, 1);	       /* want reply */
+	    ssh2_pkt_addstring(s->pktout, cmd);
 	} else if (*cmd) {
-	    ssh2_pkt_addstring(ssh, "exec");
-	    ssh2_pkt_addbool(ssh, 1);	       /* want reply */
-	    ssh2_pkt_addstring(ssh, cmd);
+	    ssh2_pkt_addstring(s->pktout, "exec");
+	    ssh2_pkt_addbool(s->pktout, 1);	       /* want reply */
+	    ssh2_pkt_addstring(s->pktout, cmd);
 	} else {
-	    ssh2_pkt_addstring(ssh, "shell");
-	    ssh2_pkt_addbool(ssh, 1);	       /* want reply */
+	    ssh2_pkt_addstring(s->pktout, "shell");
+	    ssh2_pkt_addbool(s->pktout, 1);	       /* want reply */
 	}
-	ssh2_pkt_send(ssh);
-	do {
-	    crWaitUntilV(ispkt);
-	    if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c)
-		    continue;	       /* nonexistent channel */
-		c->v.v2.remwindow += ssh_pkt_getuint32(ssh);
-	    }
-	} 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) {
+	ssh2_pkt_send(ssh, s->pktout);
+
+	crWaitUntilV(pktin);
+
+	if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
+	    if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
 		bombout(("Unexpected response to shell/command request:"
-			 " packet type %d", ssh->pktin.type));
+			 " packet type %d", pktin->type));
 		crStopV;
 	    }
 	    /*
@@ -6114,428 +7038,16 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     while (1) {
 	crReturnV;
 	s->try_send = FALSE;
-	if (ispkt) {
-	    if (ssh->pktin.type == SSH2_MSG_CHANNEL_DATA ||
-		ssh->pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA) {
-		char *data;
-		int length;
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c)
-		    continue;	       /* nonexistent channel */
-		if (ssh->pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA &&
-		    ssh_pkt_getuint32(ssh) != SSH2_EXTENDED_DATA_STDERR)
-		    continue;	       /* extended but not stderr */
-		ssh_pkt_getstring(ssh, &data, &length);
-		if (data) {
-		    int bufsize = 0;
-		    c->v.v2.locwindow -= length;
-		    switch (c->type) {
-		      case CHAN_MAINSESSION:
-			bufsize =
-			    from_backend(ssh->frontend, ssh->pktin.type ==
-					 SSH2_MSG_CHANNEL_EXTENDED_DATA,
-					 data, length);
-			break;
-		      case CHAN_X11:
-			bufsize = x11_send(c->u.x11.s, data, length);
-			break;
-		      case CHAN_SOCKDATA:
-			bufsize = pfd_send(c->u.pfd.s, data, length);
-			break;
-		      case CHAN_AGENT:
-			while (length > 0) {
-			    if (c->u.a.lensofar < 4) {
-				int l = min(4 - c->u.a.lensofar, length);
-				memcpy(c->u.a.msglen + c->u.a.lensofar,
-				       data, l);
-				data += l;
-				length -= l;
-				c->u.a.lensofar += l;
-			    }
-			    if (c->u.a.lensofar == 4) {
-				c->u.a.totallen =
-				    4 + GET_32BIT(c->u.a.msglen);
-				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) {
-				int l =
-				    min(c->u.a.totallen - c->u.a.lensofar,
-					length);
-				memcpy(c->u.a.message + c->u.a.lensofar,
-				       data, l);
-				data += l;
-				length -= l;
-				c->u.a.lensofar += l;
-			    }
-			    if (c->u.a.lensofar == c->u.a.totallen) {
-				void *reply;
-				int replylen;
-				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;
-			    }
-			}
-			bufsize = 0;
-			break;
-		    }
-		    /*
-		     * If we are not buffering too much data,
-		     * enlarge the window again at the remote side.
-		     */
-		    if (bufsize < OUR_V2_WINSIZE)
-			ssh2_set_window(c, OUR_V2_WINSIZE - bufsize);
-		}
-	    } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_EOF) {
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c)
-		    continue;	       /* nonexistent channel */
-
-		if (c->type == CHAN_X11) {
-		    /*
-		     * Remote EOF on an X11 channel means we should
-		     * wrap up and close the channel ourselves.
-		     */
-		    x11_close(c->u.x11.s);
-		    sshfwd_close(c);
-		} else if (c->type == CHAN_AGENT) {
-		    sshfwd_close(c);
-		} else if (c->type == CHAN_SOCKDATA) {
-		    pfd_close(c->u.pfd.s);
-		    sshfwd_close(c);
-		}
-	    } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_CLOSE) {
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c || ((int)c->remoteid) == -1) {
-		    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) {
-		  case CHAN_MAINSESSION:
-		    break;	       /* nothing to see here, move along */
-		  case CHAN_X11:
-		    if (c->u.x11.s != NULL)
-			x11_close(c->u.x11.s);
-		    sshfwd_close(c);
-		    break;
-		  case CHAN_AGENT:
-		    sshfwd_close(c);
-		    break;
-		  case CHAN_SOCKDATA:
-		    if (c->u.pfd.s != NULL)
-			pfd_close(c->u.pfd.s);
-		    sshfwd_close(c);
-		    break;
-		}
-		if (c->closes == 0) {
-		    ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_CLOSE);
-		    ssh2_pkt_adduint32(ssh, c->remoteid);
-		    ssh2_pkt_send(ssh);
-		}
-		del234(ssh->channels, c);
-		bufchain_clear(&c->v.v2.outbuffer);
-		sfree(c);
-
-		/*
-		 * See if that was the last channel left open.
-		 * (This is only our termination condition if we're
-		 * not running in -N mode.)
-		 */
-		if (!ssh->cfg.ssh_no_shell && count234(ssh->channels) == 0) {
-		    logevent("All channels closed. Disconnecting");
-#if 0
-                    /*
-                     * We used to send SSH_MSG_DISCONNECT here,
-                     * because I'd believed that _every_ conforming
-                     * SSH2 connection had to end with a disconnect
-                     * being sent by at least one side; apparently
-                     * I was wrong and it's perfectly OK to
-                     * unceremoniously slam the connection shut
-                     * when you're done, and indeed OpenSSH feels
-                     * this is more polite than sending a
-                     * DISCONNECT. So now we don't.
-                     */
-		    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_closing((Plug)ssh, NULL, 0, 0);
-		    crStopV;
-		}
-		continue;	       /* remote sends close; ignore (FIXME) */
-	    } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c || c->closes)
-		    continue;	       /* nonexistent or closing channel */
-		c->v.v2.remwindow += ssh_pkt_getuint32(ssh);
-		s->try_send = TRUE;
-	    } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
-		unsigned i = ssh_pkt_getuint32(ssh);
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c)
-		    continue;	       /* nonexistent channel */
-		if (c->type != CHAN_SOCKDATA_DORMANT)
-		    continue;	       /* dunno why they're confirming this */
-		c->remoteid = ssh_pkt_getuint32(ssh);
-		c->type = CHAN_SOCKDATA;
-		c->v.v2.remwindow = ssh_pkt_getuint32(ssh);
-		c->v.v2.remmaxpkt = ssh_pkt_getuint32(ssh);
-		if (c->u.pfd.s)
-		    pfd_confirm(c->u.pfd.s);
-		if (c->closes) {
-		    /*
-		     * We have a pending close on this channel,
-		     * which we decided on before the server acked
-		     * the channel open. So now we know the
-		     * remoteid, we can close it again.
-		     */
-		    ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_CLOSE);
-		    ssh2_pkt_adduint32(ssh, c->remoteid);
-		    ssh2_pkt_send(ssh);
-		}
-	    } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_OPEN_FAILURE) {
-                static const char *const reasons[] = {
-                    "<unknown reason code>",
-                    "Administratively prohibited",
-                    "Connect failed",
-                    "Unknown channel type",
-                    "Resource shortage",
-                };
-		unsigned i = ssh_pkt_getuint32(ssh);
-                unsigned reason_code;
-                char *reason_string;
-                int reason_length;
-                char *message;
-		struct ssh_channel *c;
-		c = find234(ssh->channels, &i, ssh_channelfind);
-		if (!c)
-		    continue;	       /* nonexistent channel */
-		if (c->type != CHAN_SOCKDATA_DORMANT)
-		    continue;	       /* dunno why they're failing this */
-
-                reason_code = ssh_pkt_getuint32(ssh);
-                if (reason_code >= lenof(reasons))
-                    reason_code = 0; /* ensure reasons[reason_code] in range */
-                ssh_pkt_getstring(ssh, &reason_string, &reason_length);
-                message = dupprintf("Forwarded connection refused by"
-                                    " server: %s [%.*s]", reasons[reason_code],
-                                    reason_length, reason_string);
-		logevent(message);
-                sfree(message);
-
-		pfd_close(c->u.pfd.s);
-
-		del234(ssh->channels, c);
-		sfree(c);
-	    } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_REQUEST) {
- 		unsigned localid;
-		char *type;
-		int typelen, want_reply;
-		struct ssh_channel *c;
-
-		localid = ssh_pkt_getuint32(ssh);
-		ssh_pkt_getstring(ssh, &type, &typelen);
-		want_reply = ssh2_pkt_getbool(ssh);
-
-		/*
-		 * First, check that the channel exists. Otherwise,
-		 * we can instantly disconnect with a rude message.
-		 */
-		c = find234(ssh->channels, &localid, ssh_channelfind);
-		if (!c) {
-		    char buf[80];
-		    sprintf(buf, "Received channel request for nonexistent"
-			    " channel %d", localid);
-		    logevent(buf);
-		    ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
-		    ssh2_pkt_adduint32(ssh, SSH2_DISCONNECT_BY_APPLICATION);
-		    ssh2_pkt_addstring(ssh, buf);
-		    ssh2_pkt_addstring(ssh, "en");	/* language tag */
-		    ssh2_pkt_send(ssh);
-		    connection_fatal(ssh->frontend, "%s", buf);
-                    ssh_closing((Plug)ssh, NULL, 0, 0);
-		    crStopV;
-		}
-
-		/*
-		 * Having got the channel number, we now look at
-		 * the request type string to see if it's something
-		 * we recognise.
-		 */
-		if (typelen == 11 && !memcmp(type, "exit-status", 11) &&
-		    c == ssh->mainchan) {
-		    /* We recognise "exit-status" on the primary channel. */
-		    char buf[100];
-		    ssh->exitcode = ssh_pkt_getuint32(ssh);
-		    sprintf(buf, "Server sent command exit status %d",
-			    ssh->exitcode);
-		    logevent(buf);
-		    if (want_reply) {
-			ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_SUCCESS);
-			ssh2_pkt_adduint32(ssh, c->remoteid);
-			ssh2_pkt_send(ssh);
-		    }
-		} else {
-		    /*
-		     * This is a channel request we don't know
-		     * about, so we now either ignore the request
-		     * or respond with CHANNEL_FAILURE, depending
-		     * on want_reply.
-		     */
-		    if (want_reply) {
-			ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_FAILURE);
-			ssh2_pkt_adduint32(ssh, c->remoteid);
-			ssh2_pkt_send(ssh);
-		    }
-		}
-	    } else if (ssh->pktin.type == SSH2_MSG_GLOBAL_REQUEST) {
-		char *type;
-		int typelen, want_reply;
-
-		ssh_pkt_getstring(ssh, &type, &typelen);
-		want_reply = ssh2_pkt_getbool(ssh);
-
-                /*
-                 * We currently don't support any global requests
-                 * at all, so we either ignore the request or
-                 * respond with REQUEST_FAILURE, depending on
-                 * want_reply.
-                 */
-                if (want_reply) {
-                    ssh2_pkt_init(ssh, SSH2_MSG_REQUEST_FAILURE);
-                    ssh2_pkt_send(ssh);
-		}
-	    } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_OPEN) {
-		char *type;
-		int typelen;
-		char *peeraddr;
-		int peeraddrlen;
-		int peerport;
-		char *error = NULL;
-		struct ssh_channel *c;
-		unsigned remid, winsize, pktsize;
-		ssh_pkt_getstring(ssh, &type, &typelen);
-		c = snew(struct ssh_channel);
-		c->ssh = ssh;
-
-		remid = ssh_pkt_getuint32(ssh);
-		winsize = ssh_pkt_getuint32(ssh);
-		pktsize = ssh_pkt_getuint32(ssh);
-
-		if (typelen == 3 && !memcmp(type, "x11", 3)) {
-		    char *addrstr;
-
-                    ssh_pkt_getstring(ssh, &peeraddr, &peeraddrlen);
-		    addrstr = snewn(peeraddrlen+1, char);
-		    memcpy(addrstr, peeraddr, peeraddrlen);
-		    addrstr[peeraddrlen] = '\0';
-                    peerport = ssh_pkt_getuint32(ssh);
-
-		    logeventf(ssh, "Received X11 connect request from %s:%d",
-			      addrstr, peerport);
-
-		    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, peerport,
-				      &ssh->cfg) != NULL) {
-			error = "Unable to open an X11 connection";
-		    } else {
-			logevent("Opening X11 forward connection succeeded");
-			c->type = CHAN_X11;
-		    }
+	if (pktin) {
 
-		    sfree(addrstr);
-		} else if (typelen == 15 &&
-			   !memcmp(type, "forwarded-tcpip", 15)) {
-		    struct ssh_rportfwd pf, *realpf;
-		    char *dummy;
-		    int dummylen;
-		    ssh_pkt_getstring(ssh, &dummy, &dummylen);/* skip address */
-		    pf.sport = ssh_pkt_getuint32(ssh);
-                    ssh_pkt_getstring(ssh, &peeraddr, &peeraddrlen);
-                    peerport = ssh_pkt_getuint32(ssh);
-		    realpf = find234(ssh->rportfwds, &pf, NULL);
-		    logeventf(ssh, "Received remote port %d open request "
-			      "from %s:%d", pf.sport, peeraddr, peerport);
-		    if (realpf == NULL) {
-			error = "Remote port is not recognised";
-		    } else {
-			const char *e = pfd_newconnect(&c->u.pfd.s,
-						       realpf->dhost,
-						       realpf->dport, c,
-						       &ssh->cfg);
-			logeventf(ssh, "Attempting to forward remote port to "
-				  "%s:%d", realpf->dhost, realpf->dport);
-			if (e != NULL) {
-			    logeventf(ssh, "Port open failed: %s", e);
-			    error = "Port open failed";
-			} else {
-			    logevent("Forwarded port opened successfully");
-			    c->type = CHAN_SOCKDATA;
-			}
-		    }
-		} else if (typelen == 22 &&
-			   !memcmp(type, "auth-agent@openssh.com", 3)) {
-		    if (!ssh->agentfwd_enabled)
-			error = "Agent forwarding is not enabled";
-		    else {
-			c->type = CHAN_AGENT;	/* identify channel type */
-			c->u.a.lensofar = 0;
-		    }
-		} else {
-		    error = "Unsupported channel type requested";
-		}
+	    /*
+	     * _All_ the connection-layer packets we expect to
+	     * receive are now handled by the dispatch table.
+	     * Anything that reaches here must be bogus.
+	     */
 
-		c->remoteid = remid;
-		if (error) {
-		    ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE);
-		    ssh2_pkt_adduint32(ssh, c->remoteid);
-		    ssh2_pkt_adduint32(ssh, SSH2_OPEN_CONNECT_FAILED);
-		    ssh2_pkt_addstring(ssh, error);
-		    ssh2_pkt_addstring(ssh, "en");	/* language tag */
-		    ssh2_pkt_send(ssh);
-		    logeventf(ssh, "Rejected channel open: %s", error);
-		    sfree(c);
-		} else {
-		    c->localid = alloc_channel_id(ssh);
-		    c->closes = 0;
-		    c->v.v2.locwindow = OUR_V2_WINSIZE;
-		    c->v.v2.remwindow = winsize;
-		    c->v.v2.remmaxpkt = pktsize;
-		    bufchain_init(&c->v.v2.outbuffer);
-		    add234(ssh->channels, c);
-		    ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
-		    ssh2_pkt_adduint32(ssh, c->remoteid);
-		    ssh2_pkt_adduint32(ssh, c->localid);
-		    ssh2_pkt_adduint32(ssh, c->v.v2.locwindow);
-		    ssh2_pkt_adduint32(ssh, 0x4000UL);	/* our max pkt size */
-		    ssh2_pkt_send(ssh);
-		}
-	    } else {
-		bombout(("Strange packet received: type %d", ssh->pktin.type));
-		crStopV;
-	    }
+	    bombout(("Strange packet received: type %d", pktin->type));
+	    crStopV;
 	} else if (ssh->mainchan) {
 	    /*
 	     * We have spare data. Add it to the channel buffer.
@@ -6580,13 +7092,168 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 }
 
 /*
+ * Handlers for SSH2 messages that might arrive at any moment.
+ */
+void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
+{
+    /* log reason code in disconnect message */
+    char *buf, *msg;
+    int nowlen, reason, msglen;
+
+    reason = ssh_pkt_getuint32(pktin);
+    ssh_pkt_getstring(pktin, &msg, &msglen);
+
+    if (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) {
+	buf = dupprintf("Received disconnect message (%s)",
+			ssh2_disconnect_reasons[reason]);
+    } else {
+	buf = dupprintf("Received disconnect message (unknown"
+			" type %d)", reason);
+    }
+    logevent(buf);
+    sfree(buf);
+    buf = dupprintf("Disconnection message text: %n%.*s",
+		    &nowlen, msglen, msg);
+    logevent(buf);
+    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);
+}
+
+void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
+{
+    /* log the debug message */
+    char *buf, *msg;
+    int msglen;
+    int always_display;
+
+    /* XXX maybe we should actually take notice of this */
+    always_display = ssh2_pkt_getbool(pktin);
+    ssh_pkt_getstring(pktin, &msg, &msglen);
+
+    buf = dupprintf("Remote debug message: %.*s", msglen, msg);
+    logevent(buf);
+    sfree(buf);
+}
+
+void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
+{
+    struct Packet *pktout;
+    pktout = ssh2_pkt_init(SSH2_MSG_UNIMPLEMENTED);
+    ssh2_pkt_adduint32(pktout, pktin->sequence);
+    /*
+     * UNIMPLEMENTED messages MUST appear in the same order as the
+     * messages they respond to. Hence, never queue them.
+     */
+    ssh2_pkt_send_noqueue(ssh, pktout);
+}
+
+/*
  * Handle the top-level SSH2 protocol.
  */
-static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
+static void ssh2_protocol_setup(Ssh ssh)
+{
+    int i;
+
+    /*
+     * Most messages cause SSH2_MSG_UNIMPLEMENTED.
+     */
+    for (i = 0; i < 256; i++)
+	ssh->packet_dispatch[i] = ssh2_msg_something_unimplemented;
+
+    /*
+     * Any message we actually understand, we set to NULL so that
+     * the coroutines will get it.
+     */
+    ssh->packet_dispatch[SSH2_MSG_UNIMPLEMENTED] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_SERVICE_REQUEST] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_SERVICE_ACCEPT] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_KEXINIT] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_NEWKEYS] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_KEXDH_INIT] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_KEXDH_REPLY] = NULL;
+    /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REQUEST] = NULL; duplicate case value */
+    /* ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_GROUP] = NULL; duplicate case value */
+    ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_INIT] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_KEX_DH_GEX_REPLY] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_REQUEST] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_FAILURE] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_SUCCESS] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_PK_OK] = NULL;
+    /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ] = NULL; duplicate case value */
+    /* ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_REQUEST] = NULL; duplicate case value */
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_INFO_RESPONSE] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_GLOBAL_REQUEST] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_REQUEST_SUCCESS] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_REQUEST_FAILURE] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_CONFIRMATION] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN_FAILURE] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_WINDOW_ADJUST] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_DATA] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = NULL;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = NULL;
+
+    /*
+     * These special message types we install handlers for.
+     */
+    ssh->packet_dispatch[SSH2_MSG_DISCONNECT] = ssh2_msg_disconnect;
+    ssh->packet_dispatch[SSH2_MSG_IGNORE] = ssh_msg_ignore; /* shared with ssh1 */
+    ssh->packet_dispatch[SSH2_MSG_DEBUG] = ssh2_msg_debug;
+}
+
+static void ssh2_timer(void *ctx, long now)
+{
+    Ssh ssh = (Ssh)ctx;
+
+    if (!ssh->kex_in_progress && ssh->cfg.ssh_rekey_time != 0 &&
+	now - ssh->next_rekey >= 0) {
+	do_ssh2_transport(ssh, "Initiating key re-exchange (timeout)",
+			  -1, NULL);
+    }
+}
+
+static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen,
+			  struct Packet *pktin)
 {
-    if (do_ssh2_transport(ssh, in, inlen, ispkt) == 0)
+    if (ssh->state == SSH_STATE_CLOSED)
+	return;
+
+    if (pktin) {
+	ssh->incoming_data_size += pktin->encrypted_len;
+	if (!ssh->kex_in_progress &&
+	    ssh->max_data_size != 0 &&
+	    ssh->incoming_data_size > ssh->max_data_size)
+	    do_ssh2_transport(ssh, "Initiating key re-exchange "
+			      "(too much data received)", -1, NULL);
+    }
+
+    if (pktin && ssh->packet_dispatch[pktin->type]) {
+	ssh->packet_dispatch[pktin->type](ssh, pktin);
 	return;
-    do_ssh2_authconn(ssh, in, inlen, ispkt);
+    }
+
+    if (!ssh->protocol_initial_phase_done ||
+	(pktin && pktin->type >= 20 && pktin->type < 50)) {
+	if (do_ssh2_transport(ssh, in, inlen, pktin) &&
+	    !ssh->protocol_initial_phase_done) {
+	    ssh->protocol_initial_phase_done = TRUE;
+	    /*
+	     * Allow authconn to initialise itself.
+	     */
+	    do_ssh2_authconn(ssh, NULL, 0, NULL);
+	}
+    } else {
+	do_ssh2_authconn(ssh, in, inlen, pktin);
+    }
 }
 
 /*
@@ -6630,16 +7297,9 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->eof_needed = FALSE;
     ssh->ldisc = NULL;
     ssh->logctx = NULL;
-    {
-	static const struct Packet empty = { 0, 0, NULL, NULL, 0 };
-	ssh->pktin = ssh->pktout = empty;
-    }
     ssh->deferred_send_data = NULL;
     ssh->deferred_len = 0;
     ssh->deferred_size = 0;
-    ssh->pktout_logmode = PKTLOG_EMIT;
-    ssh->pktout_nblanks = 0;
-    ssh->pktout_blanks = NULL;
     ssh->fallback_cmd = 0;
     ssh->pkt_ctx = 0;
     ssh->x11auth = NULL;
@@ -6649,7 +7309,7 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->ssh2_rdpkt_crstate = 0;
     ssh->do_ssh_init_crstate = 0;
     ssh->ssh_gotdata_crstate = 0;
-    ssh->ssh1_protocol_crstate = 0;
+    ssh->do_ssh1_connection_crstate = 0;
     ssh->do_ssh1_login_crstate = 0;
     ssh->do_ssh2_transport_crstate = 0;
     ssh->do_ssh2_authconn_crstate = 0;
@@ -6660,6 +7320,10 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->mainchan = NULL;
     ssh->throttled_all = 0;
     ssh->v1_stdout_throttling = 0;
+    ssh->queue = NULL;
+    ssh->queuelen = ssh->queuesize = 0;
+    ssh->queueing = FALSE;
+    ssh->qhead = ssh->qtail = NULL;
 
     *backend_handle = ssh;
 
@@ -6674,6 +7338,7 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
 
     ssh->channels = NULL;
     ssh->rportfwds = NULL;
+    ssh->portfwds = NULL;
 
     ssh->send_ok = 0;
     ssh->editing = 0;
@@ -6684,10 +7349,21 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
 
     ssh->protocol = NULL;
 
+    ssh->protocol_initial_phase_done = FALSE;
+
+    ssh->pinger = NULL;
+
+    ssh->incoming_data_size = ssh->outgoing_data_size =
+	ssh->deferred_data_size = 0L;
+    ssh->max_data_size = parse_blocksize(ssh->cfg.ssh_rekey_data);
+    ssh->kex_in_progress = FALSE;
+
     p = connect_to_host(ssh, host, port, realhost, nodelay, keepalive);
     if (p != NULL)
 	return p;
 
+    random_ref();
+
     return NULL;
 }
 
@@ -6723,6 +7399,17 @@ static void ssh_free(void *handle)
 	dh_cleanup(ssh->kex_ctx);
     sfree(ssh->savedhost);
 
+    while (ssh->queuelen-- > 0)
+	ssh_free_packet(ssh->queue[ssh->queuelen]);
+    sfree(ssh->queue);
+
+    while (ssh->qhead) {
+	struct queued_handler *qh = ssh->qhead;
+	ssh->qhead = qh->next;
+	sfree(ssh->qhead);
+    }
+    ssh->qhead = ssh->qtail = NULL;
+
     if (ssh->channels) {
 	while ((c = delpos234(ssh->channels, 0)) != NULL) {
 	    switch (c->type) {
@@ -6738,12 +7425,14 @@ static void ssh_free(void *handle)
 	    sfree(c);
 	}
 	freetree234(ssh->channels);
+	ssh->channels = NULL;
     }
 
     if (ssh->rportfwds) {
 	while ((pf = delpos234(ssh->rportfwds, 0)) != NULL)
 	    sfree(pf);
 	freetree234(ssh->rportfwds);
+	ssh->rportfwds = NULL;
     }
     sfree(ssh->deferred_send_data);
     if (ssh->x11auth)
@@ -6752,35 +7441,57 @@ 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->s)
 	ssh_do_close(ssh);
+    expire_timer_context(ssh);
+    if (ssh->pinger)
+	pinger_free(ssh->pinger);
     sfree(ssh);
+
+    random_unref();
 }
 
 /*
  * Reconfigure the SSH backend.
- * 
- * Currently, this function does nothing very useful. In future,
- * however, we could do some handy things with it. For example, we
- * could make the port forwarding configurer active in the Change
- * Settings box, and this routine could close down existing
- * forwardings and open up new ones in response to changes.
  */
 static void ssh_reconfig(void *handle, Config *cfg)
 {
     Ssh ssh = (Ssh) handle;
+    char *rekeying = NULL;
+    unsigned long old_max_data_size;
+
+    pinger_reconfig(ssh->pinger, &ssh->cfg, cfg);
+    ssh_setup_portfwd(ssh, cfg);
+
+    if (ssh->cfg.ssh_rekey_time != cfg->ssh_rekey_time &&
+	cfg->ssh_rekey_time != 0) {
+	long new_next = ssh->last_rekey + cfg->ssh_rekey_time*60*TICKSPERSEC;
+	long now = GETTICKCOUNT();
+
+	if (new_next - now < 0) {
+	    rekeying = "Initiating key re-exchange (timeout shortened)";
+	} else {
+	    ssh->next_rekey = schedule_timer(new_next - now, ssh2_timer, ssh);
+	}
+    }
+
+    old_max_data_size = ssh->max_data_size;
+    ssh->max_data_size = parse_blocksize(cfg->ssh_rekey_data);
+    if (old_max_data_size != ssh->max_data_size &&
+	ssh->max_data_size != 0) {
+	if (ssh->outgoing_data_size > ssh->max_data_size ||
+	    ssh->incoming_data_size > ssh->max_data_size)
+	    rekeying = "Initiating key re-exchange (data limit lowered)";
+    }
+
+    if (rekeying && !ssh->kex_in_progress) {
+	do_ssh2_transport(ssh, rekeying, -1, NULL);
+    }
+
     ssh->cfg = *cfg;		       /* STRUCTURE COPY */
 }
 
@@ -6837,6 +7548,7 @@ static int ssh_sendbuffer(void *handle)
 static void ssh_size(void *handle, int width, int height)
 {
     Ssh ssh = (Ssh) handle;
+    struct Packet *pktout;
 
     ssh->term_width = width;
     ssh->term_height = height;
@@ -6857,15 +7569,15 @@ static void ssh_size(void *handle, int width, int height)
 			    PKT_INT, ssh->term_width,
 			    PKT_INT, 0, PKT_INT, 0, PKT_END);
 	    } else if (ssh->mainchan) {
-		ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
-		ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
-		ssh2_pkt_addstring(ssh, "window-change");
-		ssh2_pkt_addbool(ssh, 0);
-		ssh2_pkt_adduint32(ssh, ssh->term_width);
-		ssh2_pkt_adduint32(ssh, ssh->term_height);
-		ssh2_pkt_adduint32(ssh, 0);
-		ssh2_pkt_adduint32(ssh, 0);
-		ssh2_pkt_send(ssh);
+		pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+		ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
+		ssh2_pkt_addstring(pktout, "window-change");
+		ssh2_pkt_addbool(pktout, 0);
+		ssh2_pkt_adduint32(pktout, ssh->term_width);
+		ssh2_pkt_adduint32(pktout, ssh->term_height);
+		ssh2_pkt_adduint32(pktout, 0);
+		ssh2_pkt_adduint32(pktout, 0);
+		ssh2_pkt_send(ssh, pktout);
 	    }
 	}
 	break;
@@ -6878,23 +7590,66 @@ static void ssh_size(void *handle, int width, int height)
  */
 static const struct telnet_special *ssh_get_specials(void *handle)
 {
+    static const struct telnet_special ssh1_ignore_special[] = {
+	{"IGNORE message", TS_NOP}
+    };
+    static const struct telnet_special ssh2_transport_specials[] = {
+	{"IGNORE message", TS_NOP},
+	{"Repeat key exchange", TS_REKEY},
+    };
+    static const struct telnet_special ssh2_session_specials[] = {
+	{NULL, TS_SEP},
+	{"Break", TS_BRK},
+	/* These are the signal names defined by draft-ietf-secsh-connect-23.
+	 * They include all the ISO C signals, but are a subset of the POSIX
+	 * required signals. */
+	{"SIGINT (Interrupt)", TS_SIGINT},
+	{"SIGTERM (Terminate)", TS_SIGTERM},
+	{"SIGKILL (Kill)", TS_SIGKILL},
+	{"SIGQUIT (Quit)", TS_SIGQUIT},
+	{"SIGHUP (Hangup)", TS_SIGHUP},
+	{"More signals", TS_SUBMENU},
+	  {"SIGABRT", TS_SIGABRT}, {"SIGALRM", TS_SIGALRM},
+	  {"SIGFPE",  TS_SIGFPE},  {"SIGILL",  TS_SIGILL},
+	  {"SIGPIPE", TS_SIGPIPE}, {"SIGSEGV", TS_SIGSEGV},
+	  {"SIGUSR1", TS_SIGUSR1}, {"SIGUSR2", TS_SIGUSR2},
+	{NULL, TS_EXITMENU}
+    };
+    static const struct telnet_special specials_end[] = {
+	{NULL, TS_EXITMENU}
+    };
+    /* XXX review this length for any changes: */
+    static struct telnet_special ssh_specials[lenof(ssh2_transport_specials) +
+					      lenof(ssh2_session_specials) +
+					      lenof(specials_end)];
     Ssh ssh = (Ssh) handle;
+    int i = 0;
+#define ADD_SPECIALS(name) \
+    do { \
+	assert((i + lenof(name)) <= lenof(ssh_specials)); \
+	memcpy(&ssh_specials[i], name, sizeof name); \
+	i += lenof(name); \
+    } while(0)
 
     if (ssh->version == 1) {
-	static const struct telnet_special ssh1_specials[] = {
-	    {"IGNORE message", TS_NOP},
-	    {NULL, 0}
-	};
-	return ssh1_specials;
+	/* Don't bother offering IGNORE if we've decided the remote
+	 * won't cope with it, since we wouldn't bother sending it if
+	 * asked anyway. */
+	if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE))
+	    ADD_SPECIALS(ssh1_ignore_special);
     } 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
+	ADD_SPECIALS(ssh2_transport_specials);
+	if (ssh->mainchan)
+	    ADD_SPECIALS(ssh2_session_specials);
+    } /* else we're not ready yet */
+
+    if (i) {
+	ADD_SPECIALS(specials_end);
+	return ssh_specials;
+    } else {
 	return NULL;
+    }
+#undef ADD_SPECIALS
 }
 
 /*
@@ -6905,6 +7660,7 @@ static const struct telnet_special *ssh_get_specials(void *handle)
 static void ssh_special(void *handle, Telnet_Special code)
 {
     Ssh ssh = (Ssh) handle;
+    struct Packet *pktout;
 
     if (code == TS_EOF) {
 	if (ssh->state != SSH_STATE_SESSION) {
@@ -6919,9 +7675,9 @@ static void ssh_special(void *handle, Telnet_Special code)
 	if (ssh->version == 1) {
 	    send_packet(ssh, SSH1_CMSG_EOF, PKT_END);
 	} else if (ssh->mainchan) {
-	    ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_EOF);
-	    ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
-	    ssh2_pkt_send(ssh);
+	    struct Packet *pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_EOF);
+	    ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
+	    ssh2_pkt_send(ssh, pktout);
 	}
 	logevent("Sent EOF message");
     } else if (code == TS_PING || code == TS_NOP) {
@@ -6931,9 +7687,14 @@ static void ssh_special(void *handle, Telnet_Special code)
 	    if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE))
 		send_packet(ssh, SSH1_MSG_IGNORE, PKT_STR, "", PKT_END);
 	} else {
-	    ssh2_pkt_init(ssh, SSH2_MSG_IGNORE);
-	    ssh2_pkt_addstring_start(ssh);
-	    ssh2_pkt_send(ssh);
+	    pktout = ssh2_pkt_init(SSH2_MSG_IGNORE);
+	    ssh2_pkt_addstring_start(pktout);
+	    ssh2_pkt_send_noqueue(ssh, pktout);
+	}
+    } else if (code == TS_REKEY) {
+	if (!ssh->kex_in_progress && ssh->version == 2) {
+	    do_ssh2_transport(ssh, "Initiating key re-exchange at"
+			      " user request", -1, NULL);
 	}
     } else if (code == TS_BRK) {
 	if (ssh->state == SSH_STATE_CLOSED
@@ -6941,15 +7702,45 @@ static void ssh_special(void *handle, Telnet_Special code)
 	if (ssh->version == 1) {
 	    logevent("Unable to send BREAK signal in SSH1");
 	} else if (ssh->mainchan) {
-	    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);
+	    pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+	    ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
+	    ssh2_pkt_addstring(pktout, "break");
+	    ssh2_pkt_addbool(pktout, 0);
+	    ssh2_pkt_adduint32(pktout, 0);   /* default break length */
+	    ssh2_pkt_send(ssh, pktout);
 	}
     } else {
-	/* do nothing */
+	/* Is is a POSIX signal? */
+	char *signame = NULL;
+	if (code == TS_SIGABRT) signame = "ABRT";
+	if (code == TS_SIGALRM) signame = "ALRM";
+	if (code == TS_SIGFPE)  signame = "FPE";
+	if (code == TS_SIGHUP)  signame = "HUP";
+	if (code == TS_SIGILL)  signame = "ILL";
+	if (code == TS_SIGINT)  signame = "INT";
+	if (code == TS_SIGKILL) signame = "KILL";
+	if (code == TS_SIGPIPE) signame = "PIPE";
+	if (code == TS_SIGQUIT) signame = "QUIT";
+	if (code == TS_SIGSEGV) signame = "SEGV";
+	if (code == TS_SIGTERM) signame = "TERM";
+	if (code == TS_SIGUSR1) signame = "USR1";
+	if (code == TS_SIGUSR2) signame = "USR2";
+	/* The SSH-2 protocol does in principle support arbitrary named
+	 * signals, including signame@domain, but we don't support those. */
+	if (signame) {
+	    /* It's a signal. */
+	    if (ssh->version == 2 && ssh->mainchan) {
+		pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+		ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
+		ssh2_pkt_addstring(pktout, "signal");
+		ssh2_pkt_addbool(pktout, 0);
+		ssh2_pkt_addstring(pktout, signame);
+		ssh2_pkt_send(ssh, pktout);
+		logeventf(ssh, "Sent signal SIG%s", signame);
+	    }
+	} else {
+	    /* Never heard of it. Do nothing */
+	}
     }
 }
 
@@ -6994,6 +7785,7 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
 {
     struct ssh_channel *c = (struct ssh_channel *)channel;
     Ssh ssh = c->ssh;
+    struct Packet *pktout;
 
     logeventf(ssh, "Opening forwarded connection to %s:%d", hostname, port);
 
@@ -7005,27 +7797,26 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
 		    //PKT_STR, <org:orgport>,
 		    PKT_END);
     } else {
-	ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN);
-	ssh2_pkt_addstring(ssh, "direct-tcpip");
-	ssh2_pkt_adduint32(ssh, c->localid);
+	pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
+	ssh2_pkt_addstring(pktout, "direct-tcpip");
+	ssh2_pkt_adduint32(pktout, c->localid);
 	c->v.v2.locwindow = OUR_V2_WINSIZE;
-	ssh2_pkt_adduint32(ssh, c->v.v2.locwindow);/* our window size */
-	ssh2_pkt_adduint32(ssh, 0x4000UL);      /* our max pkt size */
-	ssh2_pkt_addstring(ssh, hostname);
-	ssh2_pkt_adduint32(ssh, port);
+	ssh2_pkt_adduint32(pktout, c->v.v2.locwindow);/* our window size */
+	ssh2_pkt_adduint32(pktout, 0x4000UL);      /* our max pkt size */
+	ssh2_pkt_addstring(pktout, hostname);
+	ssh2_pkt_adduint32(pktout, port);
 	/*
 	 * We make up values for the originator data; partly it's
 	 * too much hassle to keep track, and partly I'm not
 	 * convinced the server should be told details like that
 	 * about my local network configuration.
 	 */
-	ssh2_pkt_addstring(ssh, "client-side-connection");
-	ssh2_pkt_adduint32(ssh, 0);
-	ssh2_pkt_send(ssh);
+	ssh2_pkt_addstring(pktout, "client-side-connection");
+	ssh2_pkt_adduint32(pktout, 0);
+	ssh2_pkt_send(ssh, pktout);
     }
 }
 
-
 static Socket ssh_socket(void *handle)
 {
     Ssh ssh = (Ssh) handle;
@@ -7070,6 +7861,16 @@ static int ssh_return_exitcode(void *handle)
 }
 
 /*
+ * cfg_info for SSH is the currently running version of the
+ * protocol. (1 for 1; 2 for 2; 0 for not-decided-yet.)
+ */
+static int ssh_cfg_info(void *handle)
+{
+    Ssh ssh = (Ssh) handle;
+    return ssh->version;
+}
+
+/*
  * Gross hack: pscp will try to start SFTP but fall back to scp1 if
  * that fails. This variable is the means by which scp.c can reach
  * into the SSH code and find out which one it got.
@@ -7096,5 +7897,6 @@ Backend ssh_backend = {
     ssh_provide_ldisc,
     ssh_provide_logctx,
     ssh_unthrottle,
+    ssh_cfg_info,
     22
 };