Unify GET_32BIT()/PUT_32BIT() et al from numerous source files into misc.h.
[u/mdw/putty] / ssh.c
diff --git a/ssh.c b/ssh.c
index 170253b..b5f34a5 100644 (file)
--- a/ssh.c
+++ b/ssh.c
  */
 #define SSH2_PKTCTX_DHGROUP          0x0001
 #define SSH2_PKTCTX_DHGEX            0x0002
+#define SSH2_PKTCTX_KEX_MASK         0x000F
 #define SSH2_PKTCTX_PUBLICKEY        0x0010
 #define SSH2_PKTCTX_PASSWORD         0x0020
 #define SSH2_PKTCTX_KBDINTER         0x0040
@@ -162,7 +163,7 @@ static const char *const ssh2_disconnect_reasons[] = {
 #define BUG_CHOKES_ON_RSA                        8
 #define BUG_SSH2_RSA_PADDING                    16
 #define BUG_SSH2_DERIVEKEY                       32
-/* 64 was BUG_SSH2_DH_GEX, now spare */
+#define BUG_SSH2_REKEY                           64
 #define BUG_SSH2_PK_SESSIONID                   128
 
 #define translate(x) if (type == x) return #x
@@ -255,18 +256,6 @@ static char *ssh2_pkt_type(int pkt_ctx, int type)
 #undef translate
 #undef translatec
 
-#define GET_32BIT(cp) \
-    (((unsigned long)(unsigned char)(cp)[0] << 24) | \
-    ((unsigned long)(unsigned char)(cp)[1] << 16) | \
-    ((unsigned long)(unsigned char)(cp)[2] << 8) | \
-    ((unsigned long)(unsigned char)(cp)[3]))
-
-#define PUT_32BIT(cp, value) { \
-    (cp)[0] = (unsigned char)((value) >> 24); \
-    (cp)[1] = (unsigned char)((value) >> 16); \
-    (cp)[2] = (unsigned char)((value) >> 8); \
-    (cp)[3] = (unsigned char)(value); }
-
 /* Enumeration values for fields in SSH-1 packets */
 enum {
     PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM,
@@ -341,24 +330,25 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
  * 
  *  - SSH1_BUFFER_LIMIT is the amount of backlog that must build up
  *    on a local data stream before we throttle the whole SSH
- *    connection (in SSH1 only). Throttling the whole connection is
+ *    connection (in SSH-1 only). Throttling the whole connection is
  *    pretty drastic so we set this high in the hope it won't
  *    happen very often.
  * 
  *  - SSH_MAX_BACKLOG is the amount of backlog that must build up
  *    on the SSH connection itself before we defensively throttle
  *    _all_ local data streams. This is pretty drastic too (though
- *    thankfully unlikely in SSH2 since the window mechanism should
+ *    thankfully unlikely in SSH-2 since the window mechanism should
  *    ensure that the server never has any need to throttle its end
  *    of the connection), so we set this high as well.
  * 
- *  - OUR_V2_WINSIZE is the maximum window size we present on SSH2
+ *  - OUR_V2_WINSIZE is the maximum window size we present on SSH-2
  *    channels.
  */
 
 #define SSH1_BUFFER_LIMIT 32768
 #define SSH_MAX_BACKLOG 32768
 #define OUR_V2_WINSIZE 16384
+#define OUR_V2_MAXPKT 0x4000UL
 
 const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
 
@@ -434,8 +424,10 @@ struct ssh_channel {
     Ssh ssh;                          /* pointer back to main context */
     unsigned remoteid, localid;
     int type;
+    /* True if we opened this channel but server hasn't confirmed. */
+    int halfopen;
     /*
-     * In SSH1, this value contains four bits:
+     * In SSH-1, this value contains four bits:
      * 
      *   1   We have sent SSH1_MSG_CHANNEL_CLOSE.
      *   2   We have sent SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
@@ -471,11 +463,11 @@ struct ssh_channel {
 };
 
 /*
- * 2-3-4 tree storing remote->local port forwardings. SSH 1 and SSH
- * 2 use this structure in different ways, reflecting SSH 2's
+ * 2-3-4 tree storing remote->local port forwardings. SSH-1 and SSH-2
+ * use this structure in different ways, reflecting SSH-2's
  * altogether saner approach to port forwarding.
  * 
- * In SSH 1, you arrange a remote forwarding by sending the server
+ * In SSH-1, you arrange a remote forwarding by sending the server
  * the remote port number, and the local destination host:port.
  * When a connection comes in, the server sends you back that
  * host:port pair, and you connect to it. This is a ready-made
@@ -487,15 +479,15 @@ struct ssh_channel {
  * host:port pairs we _are_ trying to forward to, and reject a
  * connection request from the server if it's not in the list.
  * 
- * In SSH 2, each side of the connection minds its own business and
+ * In SSH-2, each side of the connection minds its own business and
  * doesn't send unnecessary information to the other. You arrange a
  * remote forwarding by sending the server just the remote port
  * number. When a connection comes in, the server tells you which
  * 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 is indexed by destination
- * host:port pair, whereas in SSH 2 it 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 */
 
@@ -516,26 +508,29 @@ struct ssh_rportfwd {
  * it.
  */
 struct ssh_portfwd {
-    int keep;
+    enum { DESTROY, KEEP, CREATE } status;
     int type;
     unsigned sport, dport;
     char *saddr, *daddr;
+    char *sserv, *dserv;
     struct ssh_rportfwd *remote;
     int addressfamily;
     void *local;
 };
 #define free_portfwd(pf) ( \
-    ((pf) ? (sfree((pf)->saddr), sfree((pf)->daddr)) : (void)0 ), sfree(pf) )
+    ((pf) ? (sfree((pf)->saddr), sfree((pf)->daddr), \
+            sfree((pf)->sserv), sfree((pf)->dserv)) : (void)0 ), sfree(pf) )
 
 struct Packet {
     long length;
+    long forcepad; /* Force padding to at least this length */
     int type;
     unsigned long sequence;
     unsigned char *data;
     unsigned char *body;
     long savedpos;
     long maxlen;
-    long encrypted_len;                       /* for SSH2 total-size counting */
+    long encrypted_len;                       /* for SSH-2 total-size counting */
 
     /*
      * State associated with packet logging
@@ -545,9 +540,9 @@ struct Packet {
     struct logblank_t *blanks;
 };
 
-static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen,
+static void ssh1_protocol(Ssh ssh, void *vin, int inlen,
                          struct Packet *pktin);
-static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen,
+static void ssh2_protocol(Ssh ssh, void *vin, int inlen,
                          struct Packet *pktin);
 static void ssh1_protocol_setup(Ssh ssh);
 static void ssh2_protocol_setup(Ssh ssh);
@@ -558,12 +553,12 @@ static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len);
 static void ssh_throttle_all(Ssh ssh, int enable, int bufsize);
 static void ssh2_set_window(struct ssh_channel *c, unsigned newwin);
 static int ssh_sendbuffer(void *handle);
-static void ssh_do_close(Ssh ssh);
+static int ssh_do_close(Ssh ssh, int notify_exit);
 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,
+static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                             struct Packet *pktin);
 
 struct rdpkt1_state_tag {
@@ -639,6 +634,7 @@ struct ssh_tag {
     tree234 *channels;                /* indexed by local id */
     struct ssh_channel *mainchan;      /* primary session channel */
     int exitcode;
+    int close_expected;
 
     tree234 *rportfwds, *portfwds;
 
@@ -683,7 +679,7 @@ struct ssh_tag {
     int overall_bufsize;
     int throttled_all;
     int v1_stdout_throttling;
-    int v2_outgoing_sequence;
+    unsigned long v2_outgoing_sequence;
 
     int ssh1_rdpkt_crstate;
     int ssh2_rdpkt_crstate;
@@ -702,10 +698,10 @@ struct ssh_tag {
     struct rdpkt1_state_tag rdpkt1_state;
     struct rdpkt2_state_tag rdpkt2_state;
 
-    /* ssh1 and ssh2 use this for different things, but both use it */
+    /* SSH-1 and SSH-2 use this for different things, but both use it */
     int protocol_initial_phase_done;
 
-    void (*protocol) (Ssh ssh, unsigned char *in, int inlen,
+    void (*protocol) (Ssh ssh, void *vin, int inlen,
                      struct Packet *pkt);
     struct Packet *(*s_rdpkt) (Ssh ssh, unsigned char **data, int *datalen);
 
@@ -718,10 +714,23 @@ struct ssh_tag {
     Config cfg;
 
     /*
-     * Used to transfer data back from async agent callbacks.
+     * Used to transfer data back from async callbacks.
      */
     void *agent_response;
     int agent_response_len;
+    int user_response;
+
+    /*
+     * The SSH connection can be set as `frozen', meaning we are
+     * not currently accepting incoming data from the network. This
+     * is slightly more serious than setting the _socket_ as
+     * frozen, because we may already have had data passed to us
+     * from the network which we need to delay processing until
+     * after the freeze is lifted, so we also need a bufchain to
+     * store that data.
+     */
+    int frozen;
+    bufchain queued_incoming_data;
 
     /*
      * Dispatch table for packet types that we may have to deal
@@ -748,6 +757,7 @@ struct ssh_tag {
     unsigned long max_data_size;
     int kex_in_progress;
     long next_rekey, last_rekey;
+    char *deferred_rekey_reason;    /* points to STATIC string; don't free */
 };
 
 #define logevent(s) logevent(ssh->frontend, s)
@@ -768,7 +778,7 @@ static void logeventf(Ssh ssh, const char *fmt, ...)
 #define bombout(msg) \
     do { \
         char *text = dupprintf msg; \
-       ssh_do_close(ssh); \
+       ssh_do_close(ssh, FALSE); \
         logevent(text); \
         connection_fatal(ssh->frontend, "%s", text); \
         sfree(text); \
@@ -864,6 +874,10 @@ static int ssh_portcmp(void *av, void *bv)
        return +1;
     if (a->type < b->type)
        return -1;
+    if (a->addressfamily > b->addressfamily)
+       return +1;
+    if (a->addressfamily < b->addressfamily)
+       return -1;
     if ( (i = nullstrcmp(a->saddr, b->saddr)) != 0)
        return i < 0 ? -1 : +1;
     if (a->sport > b->sport)
@@ -1532,7 +1546,7 @@ static void sha_uint32(SHA_State * s, unsigned i)
 }
 
 /*
- * SSH2 packet construction functions.
+ * SSH-2 packet construction functions.
  */
 static void ssh2_pkt_ensure(struct Packet *pkt, int length)
 {
@@ -1562,6 +1576,7 @@ static struct Packet *ssh2_pkt_init(int pkt_type)
 {
     struct Packet *pkt = ssh_new_packet();
     pkt->length = 5;
+    pkt->forcepad = 0;
     ssh2_pkt_addbyte(pkt, (unsigned char) pkt_type);
     return pkt;
 }
@@ -1623,7 +1638,7 @@ static void ssh2_pkt_addmp(struct Packet *pkt, Bignum b)
 }
 
 /*
- * Construct an SSH2 final-form packet: compress it, encrypt it,
+ * Construct an SSH-2 final-form packet: compress it, encrypt it,
  * put the MAC on it. Final packet, ready to be sent, is stored in
  * pkt->data. Total length is returned.
  */
@@ -1658,12 +1673,17 @@ static int ssh2_pkt_construct(Ssh ssh, struct Packet *pkt)
     /*
      * Add padding. At least four bytes, and must also bring total
      * length (minus MAC) up to a multiple of the block size.
+     * If pkt->forcepad is set, make sure the packet is at least that size
+     * after padding.
      */
     cipherblk = ssh->cscipher ? ssh->cscipher->blksize : 8;  /* block size */
     cipherblk = cipherblk < 8 ? 8 : cipherblk; /* or 8 if blksize < 8 */
     padding = 4;
+    if (pkt->length + padding < pkt->forcepad)
+       padding = pkt->forcepad - pkt->length;
     padding +=
        (cipherblk - (pkt->length + padding) % cipherblk) % cipherblk;
+    assert(padding <= 255);
     maclen = ssh->csmac ? ssh->csmac->len : 0;
     ssh2_pkt_ensure(pkt, pkt->length + padding + maclen);
     pkt->data[4] = padding;
@@ -1716,7 +1736,7 @@ static int ssh2_pkt_construct(Ssh ssh, struct Packet *pkt)
  */
 
 /*
- * Send an SSH2 packet immediately, without queuing or deferring.
+ * Send an SSH-2 packet immediately, without queuing or deferring.
  */
 static void ssh2_pkt_send_noqueue(Ssh ssh, struct Packet *pkt)
 {
@@ -1731,14 +1751,13 @@ static void ssh2_pkt_send_noqueue(Ssh ssh, struct Packet *pkt)
     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);
+       do_ssh2_transport(ssh, "too much data sent", -1, NULL);
 
     ssh_free_packet(pkt);
 }
 
 /*
- * Defer an SSH2 packet.
+ * Defer an SSH-2 packet.
  */
 static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt)
 {
@@ -1756,7 +1775,7 @@ static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt)
 }
 
 /*
- * Queue an SSH2 packet.
+ * Queue an SSH-2 packet.
  */
 static void ssh2_pkt_queue(Ssh ssh, struct Packet *pkt)
 {
@@ -1782,6 +1801,7 @@ static void ssh2_pkt_send(Ssh ssh, struct Packet *pkt)
        ssh2_pkt_send_noqueue(ssh, pkt);
 }
 
+#if 0 /* disused */
 /*
  * Either queue or defer a packet, depending on whether queueing is
  * set.
@@ -1793,10 +1813,11 @@ static void ssh2_pkt_defer(Ssh ssh, struct Packet *pkt)
     else
        ssh2_pkt_defer_noqueue(ssh, pkt);
 }
+#endif
 
 /*
  * Send the whole deferred data block constructed by
- * ssh2_pkt_defer() or SSH1's defer_packet().
+ * ssh2_pkt_defer() or SSH-1'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
@@ -1822,13 +1843,12 @@ static void ssh_pkt_defersend(Ssh ssh)
     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);
+       do_ssh2_transport(ssh, "too much data sent", -1, NULL);
     ssh->deferred_data_size = 0;
 }
 
 /*
- * Send all queued SSH2 packets. We send them by means of
+ * Send all queued SSH-2 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.
  */
@@ -1869,7 +1889,7 @@ static void sha_mpint(SHA_State * s, Bignum b)
 }
 
 /*
- * Packet decode functions for both SSH1 and SSH2.
+ * Packet decode functions for both SSH-1 and SSH-2.
  */
 static unsigned long ssh_pkt_getuint32(struct Packet *pkt)
 {
@@ -1960,7 +1980,7 @@ static Bignum ssh2_pkt_getmp(struct Packet *pkt)
 }
 
 /*
- * Helper function to add an SSH2 signature blob to a packet.
+ * Helper function to add an SSH-2 signature blob to a packet.
  * Expects to be shown the public key blob as well as the signature
  * blob. Normally works just like ssh2_pkt_addstring, but will
  * fiddle with the signature packet if necessary for
@@ -2056,7 +2076,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
         * sniffing.
         */
        ssh->remote_bugs |= BUG_CHOKES_ON_SSH1_IGNORE;
-       logevent("We believe remote version has SSH1 ignore bug");
+       logevent("We believe remote version has SSH-1 ignore bug");
     }
 
     if (ssh->cfg.sshbug_plainpw1 == FORCE_ON ||
@@ -2068,7 +2088,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
         * the password.
         */
        ssh->remote_bugs |= BUG_NEEDS_SSH1_PLAIN_PASSWORD;
-       logevent("We believe remote version needs a plain SSH1 password");
+       logevent("We believe remote version needs a plain SSH-1 password");
     }
 
     if (ssh->cfg.sshbug_rsa1 == FORCE_ON ||
@@ -2080,7 +2100,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
         * an AUTH_RSA message.
         */
        ssh->remote_bugs |= BUG_CHOKES_ON_RSA;
-       logevent("We believe remote version can't handle RSA authentication");
+       logevent("We believe remote version can't handle SSH-1 RSA authentication");
     }
 
     if (ssh->cfg.sshbug_hmac2 == FORCE_ON ||
@@ -2093,7 +2113,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
         * These versions have the HMAC bug.
         */
        ssh->remote_bugs |= BUG_SSH2_HMAC;
-       logevent("We believe remote version has SSH2 HMAC bug");
+       logevent("We believe remote version has SSH-2 HMAC bug");
     }
 
     if (ssh->cfg.sshbug_derivekey2 == FORCE_ON ||
@@ -2106,7 +2126,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
         * generate the keys).
         */
        ssh->remote_bugs |= BUG_SSH2_DERIVEKEY;
-       logevent("We believe remote version has SSH2 key-derivation bug");
+       logevent("We believe remote version has SSH-2 key-derivation bug");
     }
 
     if (ssh->cfg.sshbug_rsapad2 == FORCE_ON ||
@@ -2114,21 +2134,34 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
         (wc_match("OpenSSH_2.[5-9]*", imp) ||
          wc_match("OpenSSH_3.[0-2]*", imp)))) {
        /*
-        * These versions have the SSH2 RSA padding bug.
+        * These versions have the SSH-2 RSA padding bug.
         */
        ssh->remote_bugs |= BUG_SSH2_RSA_PADDING;
-       logevent("We believe remote version has SSH2 RSA padding bug");
+       logevent("We believe remote version has SSH-2 RSA padding bug");
     }
 
     if (ssh->cfg.sshbug_pksessid2 == FORCE_ON ||
        (ssh->cfg.sshbug_pksessid2 == AUTO &&
         wc_match("OpenSSH_2.[0-2]*", imp))) {
        /*
-        * These versions have the SSH2 session-ID bug in
+        * These versions have the SSH-2 session-ID bug in
         * public-key authentication.
         */
        ssh->remote_bugs |= BUG_SSH2_PK_SESSIONID;
-       logevent("We believe remote version has SSH2 public-key-session-ID bug");
+       logevent("We believe remote version has SSH-2 public-key-session-ID bug");
+    }
+
+    if (ssh->cfg.sshbug_rekey2 == FORCE_ON ||
+       (ssh->cfg.sshbug_rekey2 == AUTO &&
+        (wc_match("OpenSSH_2.[0-4]*", imp) ||
+         wc_match("OpenSSH_2.5.[0-3]*", imp) ||
+         wc_match("Sun_SSH_1.0", imp) ||
+         wc_match("Sun_SSH_1.0.1", imp)))) {
+       /*
+        * These versions have the SSH-2 rekey bug.
+        */
+       ssh->remote_bugs |= BUG_SSH2_REKEY;
+       logevent("We believe remote version has SSH-2 rekey bug");
     }
 }
 
@@ -2215,13 +2248,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
 
     s->vstring[s->vslen] = 0;
     s->vstring[strcspn(s->vstring, "\015\012")] = '\0';/* remove EOL chars */
-    {
-       char *vlog;
-       vlog = snewn(20 + s->vslen, char);
-       sprintf(vlog, "Server version: %s", s->vstring);
-       logevent(vlog);
-       sfree(vlog);
-    }
+    logeventf(ssh, "Server version: %s", s->vstring);
     ssh_detect_bugs(ssh, s->vstring);
 
     /*
@@ -2275,14 +2302,14 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
                        strcspn(s->vstring, "\015\012"));
 
             /*
-             * Initialise SSHv2 protocol.
+             * Initialise SSH-2 protocol.
              */
             ssh->protocol = ssh2_protocol;
             ssh2_protocol_setup(ssh);
             ssh->s_rdpkt = ssh2_rdpkt;
         } else {
             /*
-             * Initialise SSHv1 protocol.
+             * Initialise SSH-1 protocol.
              */
             ssh->protocol = ssh1_protocol;
             ssh1_protocol_setup(ssh);
@@ -2305,6 +2332,50 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     crFinish(0);
 }
 
+static void ssh_process_incoming_data(Ssh ssh,
+                                     unsigned char **data, int *datalen)
+{
+    struct Packet *pktin = ssh->s_rdpkt(ssh, data, datalen);
+    if (pktin) {
+       ssh->protocol(ssh, NULL, 0, pktin);
+       ssh_free_packet(pktin);
+    }
+}
+
+static void ssh_queue_incoming_data(Ssh ssh,
+                                   unsigned char **data, int *datalen)
+{
+    bufchain_add(&ssh->queued_incoming_data, *data, *datalen);
+    *data += *datalen;
+    *datalen = 0;
+}
+
+static void ssh_process_queued_incoming_data(Ssh ssh)
+{
+    void *vdata;
+    unsigned char *data;
+    int len, origlen;
+
+    while (!ssh->frozen && bufchain_size(&ssh->queued_incoming_data)) {
+       bufchain_prefix(&ssh->queued_incoming_data, &vdata, &len);
+       data = vdata;
+       origlen = len;
+
+       while (!ssh->frozen && len > 0)
+           ssh_process_incoming_data(ssh, &data, &len);
+
+       if (origlen > len)
+           bufchain_consume(&ssh->queued_incoming_data, origlen - len);
+    }
+}
+
+static void ssh_set_frozen(Ssh ssh, int frozen)
+{
+    if (ssh->s)
+       sk_set_frozen(ssh->s, frozen);
+    ssh->frozen = frozen;
+}
+
 static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
 {
     crBegin(ssh->ssh_gotdata_crstate);
@@ -2334,13 +2405,19 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
      */
     if (datalen == 0)
        crReturnV;
+
+    /*
+     * Process queued data if there is any.
+     */
+    ssh_process_queued_incoming_data(ssh);
+
     while (1) {
        while (datalen > 0) {
-           struct Packet *pktin = ssh->s_rdpkt(ssh, &data, &datalen);
-           if (pktin) {
-               ssh->protocol(ssh, NULL, 0, pktin);
-               ssh_free_packet(pktin);
-           }
+           if (ssh->frozen)
+               ssh_queue_incoming_data(ssh, &data, &datalen);
+
+           ssh_process_incoming_data(ssh, &data, &datalen);
+
            if (ssh->state == SSH_STATE_CLOSED)
                return;
        }
@@ -2349,23 +2426,27 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
     crFinishV;
 }
 
-static void ssh_do_close(Ssh ssh)
+static int ssh_do_close(Ssh ssh, int notify_exit)
 {
-    int i;
+    int ret = 0;
     struct ssh_channel *c;
 
     ssh->state = SSH_STATE_CLOSED;
+    expire_timer_context(ssh);
     if (ssh->s) {
         sk_close(ssh->s);
         ssh->s = NULL;
-       notify_remote_exit(ssh->frontend);
+        if (notify_exit)
+            notify_remote_exit(ssh->frontend);
+        else
+            ret = 1;
     }
     /*
-     * Now we must shut down any port and X forwardings going
+     * Now we must shut down any port- and X-forwarded channels going
      * through this connection.
      */
     if (ssh->channels) {
-       for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
+       while (NULL != (c = index234(ssh->channels, 0))) {
            switch (c->type) {
              case CHAN_X11:
                x11_close(c->u.x11.s);
@@ -2374,25 +2455,66 @@ static void ssh_do_close(Ssh ssh)
                pfd_close(c->u.pfd.s);
                break;
            }
-           del234(ssh->channels, c);
+           del234(ssh->channels, c); /* moving next one to index 0 */
            if (ssh->version == 2)
                bufchain_clear(&c->v.v2.outbuffer);
            sfree(c);
        }
     }
+    /*
+     * Go through port-forwardings, and close any associated
+     * listening sockets.
+     */
+    if (ssh->portfwds) {
+       struct ssh_portfwd *pf;
+       while (NULL != (pf = index234(ssh->portfwds, 0))) {
+           /* Dispose of any listening socket. */
+           if (pf->local)
+               pfd_terminate(pf->local);
+           del234(ssh->portfwds, pf); /* moving next one to index 0 */
+           free_portfwd(pf);
+       }
+    }
+
+    return ret;
+}
+
+static void ssh_log(Plug plug, int type, SockAddr addr, int port,
+                   const char *error_msg, int error_code)
+{
+    Ssh ssh = (Ssh) plug;
+    char addrbuf[256], *msg;
+
+    sk_getaddr(addr, addrbuf, lenof(addrbuf));
+
+    if (type == 0)
+       msg = dupprintf("Connecting to %s port %d", addrbuf, port);
+    else
+       msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
+
+    logevent(msg);
+    sfree(msg);
 }
 
 static int ssh_closing(Plug plug, const char *error_msg, int error_code,
                       int calling_back)
 {
     Ssh ssh = (Ssh) plug;
-    ssh_do_close(ssh);
+    int need_notify = ssh_do_close(ssh, FALSE);
+
+    if (!error_msg && !ssh->close_expected) {
+        error_msg = "Server unexpectedly closed network connection";
+    }
+
+    if (need_notify)
+        notify_remote_exit(ssh->frontend);
+
     if (error_msg) {
        /* A socket error has occurred. */
        logevent(error_msg);
        connection_fatal(ssh->frontend, "%s", error_msg);
     } else {
-       /* Otherwise, the remote side closed the connection normally. */
+        logevent("Server closed network connection");
     }
     return 0;
 }
@@ -2402,7 +2524,7 @@ static int ssh_receive(Plug plug, int urgent, char *data, int len)
     Ssh ssh = (Ssh) plug;
     ssh_gotdata(ssh, (unsigned char *)data, len);
     if (ssh->state == SSH_STATE_CLOSED) {
-       ssh_do_close(ssh);
+       ssh_do_close(ssh, TRUE);
        return 0;
     }
     return 1;
@@ -2429,6 +2551,7 @@ static const char *connect_to_host(Ssh ssh, char *host, int port,
                                   char **realhost, int nodelay, int keepalive)
 {
     static const struct plug_function_table fn_table = {
+       ssh_log,
        ssh_closing,
        ssh_receive,
        ssh_sent,
@@ -2463,11 +2586,6 @@ static const char *connect_to_host(Ssh ssh, char *host, int port,
     /*
      * Open socket.
      */
-    {
-       char addrbuf[100];
-       sk_getaddr(addr, addrbuf, 100);
-       logeventf(ssh, "Connecting to %s port %d", addrbuf, port);
-    }
     ssh->fn = &fn_table;
     ssh->s = new_connection(addr, *realhost, port,
                            0, 1, nodelay, keepalive, (Plug) ssh, &ssh->cfg);
@@ -2489,9 +2607,9 @@ static void ssh1_throttle(Ssh ssh, int adjust)
     ssh->v1_throttle_count += adjust;
     assert(ssh->v1_throttle_count >= 0);
     if (ssh->v1_throttle_count && !old_count) {
-       sk_set_frozen(ssh->s, 1);
+       ssh_set_frozen(ssh, 1);
     } else if (!ssh->v1_throttle_count && old_count) {
-       sk_set_frozen(ssh->s, 0);
+       ssh_set_frozen(ssh, 0);
     }
 }
 
@@ -2532,7 +2650,7 @@ static void ssh_throttle_all(Ssh ssh, int enable, int bufsize)
 
 /*
  * Username and password input, abstracted off into routines
- * reusable in several places - even between SSH1 and SSH2.
+ * reusable in several places - even between SSH-1 and SSH-2.
  */
 
 /* Set up a username or password input loop on a given buffer. */
@@ -2615,6 +2733,24 @@ static void ssh_agent_callback(void *sshv, void *reply, int replylen)
        do_ssh2_authconn(ssh, NULL, -1, NULL);
 }
 
+static void ssh_dialog_callback(void *sshv, int ret)
+{
+    Ssh ssh = (Ssh) sshv;
+
+    ssh->user_response = ret;
+
+    if (ssh->version == 1)
+       do_ssh1_login(ssh, NULL, -1, NULL);
+    else
+       do_ssh2_transport(ssh, NULL, -1, NULL);
+
+    /*
+     * This may have unfrozen the SSH connection, so do a
+     * queued-data run.
+     */
+    ssh_process_queued_incoming_data(ssh);
+}
+
 static void ssh_agentf_callback(void *cv, void *reply, int replylen)
 {
     struct ssh_channel *c = (struct ssh_channel *)cv;
@@ -2676,6 +2812,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        Bignum challenge;
        char *commentp;
        int commentlen;
+        int dlgret;
     };
     crState(do_ssh1_login_state);
 
@@ -2693,14 +2830,14 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 
     ptr = ssh_pkt_getdata(pktin, 8);
     if (!ptr) {
-       bombout(("SSH1 public key packet stopped before random cookie"));
+       bombout(("SSH-1 public key packet stopped before random cookie"));
        crStop(0);
     }
     memcpy(cookie, ptr, 8);
 
     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"));
+       bombout(("Failed to read SSH-1 public keys from public key packet"));
        crStop(0);
     }
 
@@ -2739,7 +2876,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
      */
     if (hostkey.bits > hostkey.bytes * 8 ||
        servkey.bits > servkey.bytes * 8) {
-       bombout(("SSH1 public keys were badly formatted"));
+       bombout(("SSH-1 public keys were badly formatted"));
        crStop(0);
     }
 
@@ -2763,10 +2900,31 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
            fatalbox("Out of memory");
        rsastr_fmt(keystr, &hostkey);
        rsa_fingerprint(fingerprint, sizeof(fingerprint), &hostkey);
-       verify_ssh_host_key(ssh->frontend,
-                           ssh->savedhost, ssh->savedport, "rsa", keystr,
-                           fingerprint);
+
+        ssh_set_frozen(ssh, 1);
+       s->dlgret = verify_ssh_host_key(ssh->frontend,
+                                        ssh->savedhost, ssh->savedport,
+                                        "rsa", keystr, fingerprint,
+                                        ssh_dialog_callback, ssh);
        sfree(keystr);
+        if (s->dlgret < 0) {
+            do {
+                crReturn(0);
+                if (pktin) {
+                    bombout(("Unexpected data from server while waiting"
+                             " for user host key response"));
+                    crStop(0);
+                }
+            } while (pktin || inlen > 0);
+            s->dlgret = ssh->user_response;
+        }
+        ssh_set_frozen(ssh, 0);
+
+        if (s->dlgret == 0) {
+            ssh->close_expected = TRUE;
+            ssh_closing((Plug)ssh, NULL, 0, 0);
+           crStop(0);
+        }
     }
 
     for (i = 0; i < 32; i++) {
@@ -2785,7 +2943,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
            ret = rsaencrypt(s->rsabuf, hostkey.bytes, &servkey);
     }
     if (!ret) {
-       bombout(("SSH1 public key encryptions failed due to bad formatting"));
+       bombout(("SSH-1 public key encryptions failed due to bad formatting"));
        crStop(0);      
     }
 
@@ -2802,7 +2960,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                warn = 1;
            } else if (next_cipher == CIPHER_AES) {
                /* XXX Probably don't need to mention this. */
-               logevent("AES not supported in SSH1, skipping");
+               logevent("AES not supported in SSH-1, skipping");
            } else {
                switch (next_cipher) {
                  case CIPHER_3DES:     s->cipher_type = SSH_CIPHER_3DES;
@@ -2818,7 +2976,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        }
        if (!cipher_chosen) {
            if ((s->supported_ciphers_mask & (1 << SSH_CIPHER_3DES)) == 0)
-               bombout(("Server violates SSH 1 protocol by not "
+               bombout(("Server violates SSH-1 protocol by not "
                         "supporting 3DES encryption"));
            else
                /* shouldn't happen */
@@ -2827,8 +2985,28 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        }
 
        /* Warn about chosen cipher if necessary. */
-       if (warn)
-           askalg(ssh->frontend, "cipher", cipher_string);
+       if (warn) {
+            ssh_set_frozen(ssh, 1);
+           s->dlgret = askalg(ssh->frontend, "cipher", cipher_string,
+                              ssh_dialog_callback, ssh);
+           if (s->dlgret < 0) {
+               do {
+                   crReturn(0);
+                   if (pktin) {
+                       bombout(("Unexpected data from server while waiting"
+                                " for user response"));
+                       crStop(0);
+                   }
+               } while (pktin || inlen > 0);
+               s->dlgret = ssh->user_response;
+           }
+            ssh_set_frozen(ssh, 0);
+           if (s->dlgret == 0) {
+               ssh->close_expected = TRUE;
+               ssh_closing((Plug)ssh, NULL, 0, 0);
+               crStop(0);
+           }
+        }
     }
 
     switch (s->cipher_type) {
@@ -2900,6 +3078,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                     * Terminate.
                     */
                    logevent("No username provided. Abandoning session.");
+                   ssh->close_expected = TRUE;
                     ssh_closing((Plug)ssh, NULL, 0, 0);
                    crStop(1);
                }
@@ -2987,17 +3166,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                s->p = s->response + 5;
                s->nkeys = GET_32BIT(s->p);
                s->p += 4;
-               {
-                   char buf[64];
-                   sprintf(buf, "Pageant has %d SSH1 keys", s->nkeys);
-                   logevent(buf);
-               }
+               logeventf(ssh, "Pageant has %d SSH-1 keys", s->nkeys);
                for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
-                   {
-                       char buf[64];
-                       sprintf(buf, "Trying Pageant key #%d", s->keyi);
-                       logevent(buf);
-                   }
+                   logeventf(ssh, "Trying Pageant key #%d", s->keyi);
                    if (s->publickey_blob &&
                        !memcmp(s->p, s->publickey_blob,
                                s->publickey_bloblen)) {
@@ -3155,6 +3326,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                    bombout(("TIS challenge packet was badly formed"));
                    crStop(0);
                }
+               c_write_str(ssh, "Using TIS authentication.\r\n");
                logevent("Received TIS challenge");
                if (challengelen > sizeof(s->prompt) - 1)
                    challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
@@ -3188,6 +3360,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                    bombout(("CryptoCard challenge packet was badly formed"));
                    crStop(0);
                }
+               c_write_str(ssh, "Using CryptoCard authentication.\r\n");
                logevent("Received CryptoCard challenge");
                if (challengelen > sizeof(s->prompt) - 1)
                    challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
@@ -3206,18 +3379,18 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
        if (s->pwpkt_type == SSH1_CMSG_AUTH_RSA) {
            char *comment = NULL;
            int type;
-           char msgbuf[256];
            if (flags & FLAG_VERBOSE)
                c_write_str(ssh, "Trying public key authentication.\r\n");
            logeventf(ssh, "Trying public key \"%s\"",
                      filename_to_str(&ssh->cfg.keyfile));
            type = key_type(&ssh->cfg.keyfile);
            if (type != SSH_KEYTYPE_SSH1) {
-               sprintf(msgbuf, "Key is of wrong type (%s)",
-                       key_type_to_str(type));
-               logevent(msgbuf);
-               c_write_str(ssh, msgbuf);
+               char *msg = dupprintf("Key is of wrong type (%s)",
+                                     key_type_to_str(type));
+               logevent(msg);
+               c_write_str(ssh, msg);
                c_write_str(ssh, "\r\n");
+               sfree(msg);
                s->tried_publickey = 1;
                continue;
            }
@@ -3248,6 +3421,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
                            PKT_END);
                logevent("Unable to authenticate");
                connection_fatal(ssh->frontend, "Unable to authenticate");
+               ssh->close_expected = TRUE;
                 ssh_closing((Plug)ssh, NULL, 0, 0);
                crStop(1);
            }
@@ -3499,20 +3673,18 @@ void sshfwd_close(struct ssh_channel *c)
 {
     Ssh ssh = c->ssh;
 
-    if (ssh->state != SSH_STATE_SESSION) {
-       assert(ssh->state == SSH_STATE_CLOSED);
+    if (ssh->state == SSH_STATE_CLOSED)
        return;
-    }
 
     if (c && !c->closes) {
        /*
-        * If the channel's remoteid is -1, we have sent
+        * If halfopen is true, we have sent
         * CHANNEL_OPEN for this channel, but it hasn't even been
         * acknowledged by the server. So we must set a close flag
         * on it now, and then when the server acks the channel
         * open, we can close it then.
         */
-       if (((int)c->remoteid) != -1) {
+       if (!c->halfopen) {
            if (ssh->version == 1) {
                send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
                            PKT_END);
@@ -3539,10 +3711,8 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
 {
     Ssh ssh = c->ssh;
 
-    if (ssh->state != SSH_STATE_SESSION) {
-       assert(ssh->state == SSH_STATE_CLOSED);
+    if (ssh->state == SSH_STATE_CLOSED)
        return 0;
-    }
 
     if (ssh->version == 1) {
        send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
@@ -3551,7 +3721,7 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
                    PKT_INT, len, PKT_DATA, buf, len,
                    PKTT_OTHER, PKT_END);
        /*
-        * In SSH1 we can return 0 here - implying that forwarded
+        * In SSH-1 we can return 0 here - implying that forwarded
         * connections are never individually throttled - because
         * the only circumstance that can cause throttling will be
         * the whole SSH connection backing up, in which case
@@ -3568,10 +3738,8 @@ void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
 {
     Ssh ssh = c->ssh;
 
-    if (ssh->state != SSH_STATE_SESSION) {
-       assert(ssh->state == SSH_STATE_CLOSED);
+    if (ssh->state == SSH_STATE_CLOSED)
        return;
-    }
 
     if (ssh->version == 1) {
        if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) {
@@ -3670,43 +3838,42 @@ static void ssh_rportfwd_succfail(Ssh ssh, struct Packet *pktin, void *ctx)
 
 static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 {
-    char address_family, 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;
+    const char *portfwd_strptr = cfg->portfwd;
+    struct ssh_portfwd *epf;
+    int i;
 
     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.
+        * with status==DESTROY. Any that we want to keep will be
+        * re-enabled (status==KEEP) 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;
+           epf->status = DESTROY;
     }
 
     while (*portfwd_strptr) {
+       char address_family, type;
+       int sport,dport,sserv,dserv;
+       char sports[256], dports[256], saddr[256], host[256];
+       int n;
+
        address_family = 'A';
        type = 'L';
-       while (*portfwd_strptr && *portfwd_strptr != '\t') {
-           if (*portfwd_strptr == 'A' ||
-               *portfwd_strptr == '4' ||
-               *portfwd_strptr == '6')
-               address_family = *portfwd_strptr;
-           else if (*portfwd_strptr == 'L' ||
-               *portfwd_strptr == 'R' ||
-               *portfwd_strptr == 'D')
-               type = *portfwd_strptr;
-           portfwd_strptr++;
-       }
+       if (*portfwd_strptr == 'A' ||
+           *portfwd_strptr == '4' ||
+           *portfwd_strptr == '6')
+           address_family = *portfwd_strptr++;
+       if (*portfwd_strptr == 'L' ||
+           *portfwd_strptr == 'R' ||
+           *portfwd_strptr == 'D')
+           type = *portfwd_strptr++;
 
        saddr[0] = '\0';
 
@@ -3724,13 +3891,13 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                portfwd_strptr++;
                sports[n] = '\0';
                if (ssh->version == 1 && type == 'R') {
-                   logeventf(ssh, "SSH1 cannot handle remote source address "
+                   logeventf(ssh, "SSH-1 cannot handle remote source address "
                              "spec \"%s\"; ignoring", sports);
                } else
                    strcpy(saddr, sports);
                n = 0;
            }
-           if (n < 255) sports[n++] = *portfwd_strptr++;
+           if (n < lenof(sports)-1) sports[n++] = *portfwd_strptr++;
        }
        sports[n] = 0;
        if (type != 'D') {
@@ -3738,14 +3905,14 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                portfwd_strptr++;
            n = 0;
            while (*portfwd_strptr && *portfwd_strptr != ':') {
-               if (n < 255) host[n++] = *portfwd_strptr++;
+               if (n < lenof(host)-1) host[n++] = *portfwd_strptr++;
            }
            host[n] = 0;
            if (*portfwd_strptr == ':')
                portfwd_strptr++;
            n = 0;
            while (*portfwd_strptr) {
-               if (n < 255) dports[n++] = *portfwd_strptr++;
+               if (n < lenof(dports)-1) dports[n++] = *portfwd_strptr++;
            }
            dports[n] = 0;
            portfwd_strptr++;
@@ -3761,6 +3928,8 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
            }
        } else {
            while (*portfwd_strptr) portfwd_strptr++;
+           host[0] = 0;
+           dports[0] = 0;
            dport = dserv = -1;
            portfwd_strptr++;          /* eat the NUL and move to next one */
        }
@@ -3777,18 +3946,14 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
        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->sserv = sserv ? dupstr(sports) : NULL;
            pfrec->sport = sport;
-           pfrec->daddr = dupstr(host);
+           pfrec->daddr = *host ? dupstr(host) : NULL;
+           pfrec->dserv = dserv ? dupstr(dports) : NULL;
            pfrec->dport = dport;
            pfrec->local = NULL;
            pfrec->remote = NULL;
@@ -3801,41 +3966,135 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                /*
                 * We already have a port forwarding with precisely
                 * these parameters. Hence, no need to do anything;
-                * simply tag the existing one as `keep'.
+                * simply tag the existing one as KEEP.
                 */
-               epfrec->keep = TRUE;
+               epfrec->status = KEEP;
                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,
-                                                pfrec->addressfamily);
-
-               logeventf(ssh, "Local %sport %s forward to %s%s%s",
-                         pfrec->addressfamily == ADDRTYPE_IPV4 ? "IPv4 " :
-                         pfrec->addressfamily == ADDRTYPE_IPV6 ? "IPv6 " : "",
-                         sportdesc, dportdesc,
-                         err ? " failed: " : "", err);
+           } else {
+               pfrec->status = CREATE;
+           }
+       }
+    }
 
-               sfree(dportdesc);
-           } else if (type == 'D') {
+    /*
+     * Now go through and destroy any port forwardings which were
+     * not re-enabled.
+     */
+    for (i = 0; (epf = index234(ssh->portfwds, i)) != NULL; i++)
+       if (epf->status == DESTROY) {
+           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 SSH-1! 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) {
+                       /* XXX: ssh->cfg.rport_acceptall may not represent
+                        * what was used to open the original connection,
+                        * since it's reconfigurable. */
+                       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 */
+       }
+
+    /*
+     * And finally, set up any new port forwardings (status==CREATE).
+     */
+    for (i = 0; (epf = index234(ssh->portfwds, i)) != NULL; i++)
+       if (epf->status == CREATE) {
+           char *sportdesc, *dportdesc;
+           sportdesc = dupprintf("%s%s%s%s%d%s",
+                                 epf->saddr ? epf->saddr : "",
+                                 epf->saddr ? ":" : "",
+                                 epf->sserv ? epf->sserv : "",
+                                 epf->sserv ? "(" : "",
+                                 epf->sport,
+                                 epf->sserv ? ")" : "");
+           if (epf->type == 'D') {
+               dportdesc = NULL;
+           } else {
+               dportdesc = dupprintf("%s:%s%s%d%s",
+                                     epf->daddr,
+                                     epf->dserv ? epf->dserv : "",
+                                     epf->dserv ? "(" : "",
+                                     epf->dport,
+                                     epf->dserv ? ")" : "");
+           }
+
+           if (epf->type == 'L') {
+               const char *err = pfd_addforward(epf->daddr, epf->dport,
+                                                epf->saddr, epf->sport,
+                                                ssh, cfg,
+                                                &epf->local,
+                                                epf->addressfamily);
+
+               logeventf(ssh, "Local %sport %s forwarding to %s%s%s",
+                         epf->addressfamily == ADDRTYPE_IPV4 ? "IPv4 " :
+                         epf->addressfamily == ADDRTYPE_IPV6 ? "IPv6 " : "",
+                         sportdesc, dportdesc,
+                         err ? " failed: " : "", err ? err : "");
+           } else if (epf->type == 'D') {
                const char *err = pfd_addforward(NULL, -1,
-                                                *saddr ? saddr : NULL,
-                                                sport, ssh, &ssh->cfg,
-                                                &pfrec->local,
-                                                pfrec->addressfamily);
-
-                       logeventf(ssh, "Local %sport %s SOCKS dynamic forward%s%s",
-                                 pfrec->addressfamily == ADDRTYPE_IPV4 ? "IPv4 " :
-                                 pfrec->addressfamily == ADDRTYPE_IPV6 ? "IPv6 " : "",
-                                 sportdesc,
-                                 err ? " setup failed: " : "", err);
+                                                epf->saddr, epf->sport,
+                                                ssh, cfg,
+                                                &epf->local,
+                                                epf->addressfamily);
+
+               logeventf(ssh, "Local %sport %s SOCKS dynamic forwarding%s%s",
+                         epf->addressfamily == ADDRTYPE_IPV4 ? "IPv4 " :
+                         epf->addressfamily == ADDRTYPE_IPV6 ? "IPv6 " : "",
+                         sportdesc,
+                         err ? " failed: " : "", err ? err : "");
            } else {
                struct ssh_rportfwd *pf;
 
@@ -3850,30 +4109,28 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                }
 
                pf = snew(struct ssh_rportfwd);
-               strcpy(pf->dhost, host);
-               pf->dport = dport;
-               pf->sport = sport;
+               strncpy(pf->dhost, epf->daddr, lenof(pf->dhost)-1);
+               pf->dhost[lenof(pf->dhost)-1] = '\0';
+               pf->dport = epf->dport;
+               pf->sport = epf->sport;
                if (add234(ssh->rportfwds, pf) != pf) {
                    logeventf(ssh, "Duplicate remote port forwarding to %s:%d",
-                             host, dport);
+                             epf->daddr, epf->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, ")");
+                             " forward to %s", sportdesc, dportdesc);
 
                    pf->sportdesc = sportdesc;
                    sportdesc = NULL;
-                   pfrec->remote = pf;
-                   pf->pfrec = pfrec;
+                   epf->remote = pf;
+                   pf->pfrec = epf;
 
                    if (ssh->version == 1) {
                        send_packet(ssh, SSH1_CMSG_PORT_FORWARD_REQUEST,
-                                   PKT_INT, sport,
-                                   PKT_STR, host,
-                                   PKT_INT, dport,
+                                   PKT_INT, epf->sport,
+                                   PKT_STR, epf->daddr,
+                                   PKT_INT, epf->dport,
                                    PKT_END);
                        ssh_queue_handler(ssh, SSH1_SMSG_SUCCESS,
                                          SSH1_SMSG_FAILURE,
@@ -3883,14 +4140,14 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                        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) {
+                       if (epf->saddr) {
+                           ssh2_pkt_addstring(pktout, epf->saddr);
+                       } else if (cfg->rport_acceptall) {
                            ssh2_pkt_addstring(pktout, "0.0.0.0");
                        } else {
                            ssh2_pkt_addstring(pktout, "127.0.0.1");
                        }
-                       ssh2_pkt_adduint32(pktout, sport);
+                       ssh2_pkt_adduint32(pktout, epf->sport);
                        ssh2_pkt_send(ssh, pktout);
 
                        ssh_queue_handler(ssh, SSH2_MSG_REQUEST_SUCCESS,
@@ -3900,80 +4157,8 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
                }
            }
            sfree(sportdesc);
+           sfree(dportdesc);
        }
-    }
-
-    /*
-     * 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)
@@ -4022,6 +4207,7 @@ static void ssh1_smsg_x11_open(Ssh ssh, struct Packet *pktin)
            logevent
                ("Opening X11 forward connection succeeded");
            c->remoteid = remoteid;
+           c->halfopen = FALSE;
            c->localid = alloc_channel_id(ssh);
            c->closes = 0;
            c->v.v1.throttling = 0;
@@ -4050,6 +4236,7 @@ static void ssh1_smsg_agent_open(Ssh ssh, struct Packet *pktin)
        c = snew(struct ssh_channel);
        c->ssh = ssh;
        c->remoteid = remoteid;
+       c->halfopen = FALSE;
        c->localid = alloc_channel_id(ssh);
        c->closes = 0;
        c->v.v1.throttling = 0;
@@ -4070,7 +4257,7 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
     struct ssh_rportfwd pf, *pfp;
     int remoteid;
     int hostsize, port;
-    char *host, buf[1024];
+    char *host;
     const char *e;
     c = snew(struct ssh_channel);
     c->ssh = ssh;
@@ -4087,26 +4274,23 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
     pfp = find234(ssh->rportfwds, &pf, NULL);
 
     if (pfp == NULL) {
-       sprintf(buf, "Rejected remote port open request for %s:%d",
-               pf.dhost, port);
-       logevent(buf);
+       logeventf(ssh, "Rejected remote port open request for %s:%d",
+                 pf.dhost, port);
        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);
+       logeventf(ssh, "Received remote port open request for %s:%d",
+                 pf.dhost, port);
        e = pfd_newconnect(&c->u.pfd.s, pf.dhost, port,
                           c, &ssh->cfg, pfp->pfrec->addressfamily);
        if (e != NULL) {
-           char buf[256];
-           sprintf(buf, "Port open failed: %s", e);
-           logevent(buf);
+           logeventf(ssh, "Port open failed: %s", e);
            sfree(c);
            send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
                        PKT_INT, remoteid, PKT_END);
        } else {
            c->remoteid = remoteid;
+           c->halfopen = FALSE;
            c->localid = alloc_channel_id(ssh);
            c->closes = 0;
            c->v.v1.throttling = 0;
@@ -4129,6 +4313,7 @@ static void ssh1_msg_channel_open_confirmation(Ssh ssh, struct Packet *pktin)
     c = find234(ssh->channels, &remoteid, ssh_channelfind);
     if (c && c->type == CHAN_SOCKDATA_DORMANT) {
        c->remoteid = localid;
+       c->halfopen = FALSE;
        c->type = CHAN_SOCKDATA;
        c->v.v1.throttling = 0;
        pfd_confirm(c->u.pfd.s);
@@ -4166,7 +4351,7 @@ static void ssh1_msg_channel_close(Ssh ssh, struct Packet *pktin)
     unsigned i = ssh_pkt_getuint32(pktin);
     struct ssh_channel *c;
     c = find234(ssh->channels, &i, ssh_channelfind);
-    if (c && ((int)c->remoteid) != -1) {
+    if (c && !c->halfopen) {
        int closetype;
        closetype =
            (pktin->type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2);
@@ -4208,7 +4393,7 @@ 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;
+    int len;
     struct ssh_channel *c;
 
     ssh_pkt_getstring(pktin, &p, &len);
@@ -4275,11 +4460,8 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
 
 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);
+    logeventf(ssh, "Server sent command exit status %d", ssh->exitcode);
     send_packet(ssh, SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
     /*
      * In case `helpful' firewalls or proxies tack
@@ -4288,6 +4470,7 @@ static void ssh1_smsg_exit_status(Ssh ssh, struct Packet *pktin)
      * encrypted packet, we close the session once
      * we've sent EXIT_CONFIRMATION.
      */
+    ssh->close_expected = TRUE;
     ssh_closing((Plug)ssh, NULL, 0, 0);
 }
 
@@ -4418,12 +4601,14 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Start the shell or command.
      * 
-     * Special case: if the first-choice command is an SSH2
+     * Special case: if the first-choice command is an SSH-2
      * subsystem (hence not usable here) and the second choice
      * exists, we fall straight back to that.
      */
     {
        char *cmd = ssh->cfg.remote_cmd_ptr;
+
+       if (!cmd) cmd = ssh->cfg.remote_cmd;
        
        if (ssh->cfg.ssh_subsys && ssh->cfg.remote_cmd_ptr2) {
            cmd = ssh->cfg.remote_cmd_ptr2;
@@ -4481,17 +4666,15 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
 }
 
 /*
- * Handle the top-level SSH2 protocol.
+ * Handle the top-level SSH-2 protocol.
  */
 static void ssh1_msg_debug(Ssh ssh, struct Packet *pktin)
 {
-    char *buf, *msg;
+    char *msg;
     int msglen;
 
     ssh_pkt_getstring(pktin, &msg, &msglen);
-    buf = dupprintf("Remote debug message: %.*s", msglen, msg);
-    logevent(buf);
-    sfree(buf);
+    logeventf(ssh, "Remote debug message: %.*s", msglen, msg);
 }
 
 static void ssh1_msg_disconnect(Ssh ssh, struct Packet *pktin)
@@ -4504,7 +4687,7 @@ static void ssh1_msg_disconnect(Ssh ssh, struct Packet *pktin)
     bombout(("Server sent disconnect message:\n\"%.*s\"", msglen, msg));
 }
 
-void ssh_msg_ignore(Ssh ssh, struct Packet *pktin)
+static void ssh_msg_ignore(Ssh ssh, struct Packet *pktin)
 {
     /* Do nothing, because we're ignoring it! Duhh. */
 }
@@ -4527,9 +4710,10 @@ static void ssh1_protocol_setup(Ssh ssh)
     ssh->packet_dispatch[SSH1_MSG_DEBUG] = ssh1_msg_debug;
 }
 
-static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen,
+static void ssh1_protocol(Ssh ssh, void *vin, int inlen,
                          struct Packet *pktin)
 {
+    unsigned char *in=(unsigned char*)vin;
     if (ssh->state == SSH_STATE_CLOSED)
        return;
 
@@ -4580,7 +4764,29 @@ static int in_commasep_string(char *needle, char *haystack, int haylen)
 }
 
 /*
- * SSH2 key creation method.
+ * Similar routine for checking whether we have the first string in a list.
+ */
+static int first_in_commasep_string(char *needle, char *haystack, int haylen)
+{
+    int needlen;
+    if (!needle || !haystack)         /* protect against null pointers */
+       return 0;
+    needlen = strlen(needle);
+    /*
+     * Is it at the start of the string?
+     */
+    if (haylen >= needlen &&       /* haystack is long enough */
+       !memcmp(needle, haystack, needlen) &&   /* initial match */
+       (haylen == needlen || haystack[needlen] == ',')
+       /* either , or EOS follows */
+       )
+       return 1;
+    return 0;
+}
+
+
+/*
+ * SSH-2 key creation method.
  */
 static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
                       unsigned char *sessid, char chr,
@@ -4605,13 +4811,14 @@ static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
 }
 
 /*
- * Handle the SSH2 transport layer.
+ * Handle the SSH-2 transport layer.
  */
-static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
+static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                             struct Packet *pktin)
 {
+    unsigned char *in = (unsigned char *)vin;
     struct do_ssh2_transport_state {
-       int nbits, pbits, warn;
+       int nbits, pbits, warn_kex, warn_cscipher, warn_sccipher;
        Bignum p, g, e, f, K;
        int kex_init_value, kex_reply_value;
        const struct ssh_mac **maclist;
@@ -4631,8 +4838,11 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
        int n_preferred_ciphers;
        const struct ssh2_ciphers *preferred_ciphers[CIPHER_MAX];
        const struct ssh_compress *preferred_comp;
-       int first_kex;
+       int got_session_id, activated_authconn;
        struct Packet *pktout;
+        int dlgret;
+       int guessok;
+       int ignorepkt;
     };
     crState(do_ssh2_transport_state);
 
@@ -4642,10 +4852,21 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
     s->csmac_tobe = s->scmac_tobe = NULL;
     s->cscomp_tobe = s->sccomp_tobe = NULL;
 
-    s->first_kex = 1;
+    s->got_session_id = s->activated_authconn = FALSE;
 
+    /*
+     * Be prepared to work around the buggy MAC problem.
+     */
+    if (ssh->remote_bugs & BUG_SSH2_HMAC)
+       s->maclist = buggymacs, s->nmacs = lenof(buggymacs);
+    else
+       s->maclist = macs, s->nmacs = lenof(macs);
+
+  begin_key_exchange:
+    ssh->pkt_ctx &= ~SSH2_PKTCTX_KEX_MASK;
     {
-       int i;
+       int i, j, commalist_started;
+
        /*
         * Set up the preferred key exchange. (NULL => warn below here)
         */
@@ -4673,10 +4894,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
                break;
            }
        }
-    }
 
-    {
-       int i;
        /*
         * Set up the preferred ciphers. (NULL => warn below here)
         */
@@ -4706,27 +4924,14 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
                break;
            }
        }
-    }
 
-    /*
-     * Set up preferred compression.
-     */
-    if (ssh->cfg.compression)
-       s->preferred_comp = &ssh_zlib;
-    else
-       s->preferred_comp = &ssh_comp_none;
-
-    /*
-     * Be prepared to work around the buggy MAC problem.
-     */
-    if (ssh->remote_bugs & BUG_SSH2_HMAC)
-       s->maclist = buggymacs, s->nmacs = lenof(buggymacs);
-    else
-       s->maclist = macs, s->nmacs = lenof(macs);
-
-  begin_key_exchange:
-    {
-       int i, j, commalist_started;
+       /*
+        * Set up preferred compression.
+        */
+       if (ssh->cfg.compression)
+           s->preferred_comp = &ssh_zlib;
+       else
+           s->preferred_comp = &ssh_comp_none;
 
        /*
         * Enable queueing of outgoing auth- or connection-layer
@@ -4850,7 +5055,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
      * to.
      */
     {
-       char *str;
+       char *str, *preferred;
        int i, j, len;
 
        if (pktin->type != SSH2_MSG_KEXINIT) {
@@ -4865,28 +5070,35 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
        s->scmac_tobe = NULL;
        s->cscomp_tobe = NULL;
        s->sccomp_tobe = NULL;
+       s->warn_kex = s->warn_cscipher = s->warn_sccipher = FALSE;
+
        pktin->savedpos += 16;          /* skip garbage cookie */
        ssh_pkt_getstring(pktin, &str, &len);    /* key exchange algorithms */
-       s->warn = 0;
+
+       preferred = NULL;
        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;
+               s->warn_kex = TRUE;
+           } else {
+               if (!preferred) preferred = k->name;
+               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);
+           if (ssh->kex)
                break;
-           }
        }
        if (!ssh->kex) {
            bombout(("Couldn't agree a key exchange algorithm (available: %s)",
                     str ? str : "(null)"));
            crStop(0);
        }
+       /*
+        * Note that the server's guess is considered wrong if it doesn't match
+        * the first algorithm in our list, even if it's still the algorithm
+        * we end up using.
+        */
+       s->guessok = first_in_commasep_string(preferred, str, len);
        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)) {
@@ -4894,12 +5106,13 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
                break;
            }
        }
+       s->guessok = s->guessok &&
+           first_in_commasep_string(hostkey_algs[0]->name, str, len);
        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];
            if (!c) {
-               s->warn = 1;
+               s->warn_cscipher = TRUE;
            } else {
                for (j = 0; j < c->nciphers; j++) {
                    if (in_commasep_string(c->list[j]->name, str, len)) {
@@ -4908,12 +5121,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
                    }
                }
            }
-           if (s->cscipher_tobe) {
-               if (s->warn)
-                   askalg(ssh->frontend, "client-to-server cipher",
-                          s->cscipher_tobe->name);
+           if (s->cscipher_tobe)
                break;
-           }
        }
        if (!s->cscipher_tobe) {
            bombout(("Couldn't agree a client-to-server cipher (available: %s)",
@@ -4922,11 +5131,10 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
        }
 
        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];
            if (!c) {
-               s->warn = 1;
+               s->warn_sccipher = TRUE;
            } else {
                for (j = 0; j < c->nciphers; j++) {
                    if (in_commasep_string(c->list[j]->name, str, len)) {
@@ -4935,12 +5143,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
                    }
                }
            }
-           if (s->sccipher_tobe) {
-               if (s->warn)
-                   askalg(ssh->frontend, "server-to-client cipher",
-                          s->sccipher_tobe->name);
+           if (s->sccipher_tobe)
                break;
-           }
        }
        if (!s->sccipher_tobe) {
            bombout(("Couldn't agree a server-to-client cipher (available: %s)",
@@ -4980,6 +5184,86 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
                break;
            }
        }
+       ssh_pkt_getstring(pktin, &str, &len);  /* client->server language */
+       ssh_pkt_getstring(pktin, &str, &len);  /* server->client language */
+       s->ignorepkt = ssh2_pkt_getbool(pktin) && !s->guessok;
+
+       if (s->warn_kex) {
+           ssh_set_frozen(ssh, 1);
+           s->dlgret = askalg(ssh->frontend, "key-exchange algorithm",
+                              ssh->kex->name,
+                              ssh_dialog_callback, ssh);
+           if (s->dlgret < 0) {
+               do {
+                   crReturn(0);
+                   if (pktin) {
+                       bombout(("Unexpected data from server while"
+                                " waiting for user response"));
+                       crStop(0);
+                   }
+               } while (pktin || inlen > 0);
+               s->dlgret = ssh->user_response;
+           }
+           ssh_set_frozen(ssh, 0);
+           if (s->dlgret == 0) {
+               ssh->close_expected = TRUE;
+               ssh_closing((Plug)ssh, NULL, 0, 0);
+               crStop(0);
+           }
+       }
+
+       if (s->warn_cscipher) {
+           ssh_set_frozen(ssh, 1);
+           s->dlgret = askalg(ssh->frontend,
+                              "client-to-server cipher",
+                              s->cscipher_tobe->name,
+                              ssh_dialog_callback, ssh);
+           if (s->dlgret < 0) {
+               do {
+                   crReturn(0);
+                   if (pktin) {
+                       bombout(("Unexpected data from server while"
+                                " waiting for user response"));
+                       crStop(0);
+                   }
+               } while (pktin || inlen > 0);
+               s->dlgret = ssh->user_response;
+           }
+           ssh_set_frozen(ssh, 0);
+           if (s->dlgret == 0) {
+               ssh->close_expected = TRUE;
+               ssh_closing((Plug)ssh, NULL, 0, 0);
+               crStop(0);
+           }
+       }
+
+       if (s->warn_sccipher) {
+           ssh_set_frozen(ssh, 1);
+           s->dlgret = askalg(ssh->frontend,
+                              "server-to-client cipher",
+                              s->sccipher_tobe->name,
+                              ssh_dialog_callback, ssh);
+           if (s->dlgret < 0) {
+               do {
+                   crReturn(0);
+                   if (pktin) {
+                       bombout(("Unexpected data from server while"
+                                " waiting for user response"));
+                       crStop(0);
+                   }
+               } while (pktin || inlen > 0);
+               s->dlgret = ssh->user_response;
+           }
+           ssh_set_frozen(ssh, 0);
+           if (s->dlgret == 0) {
+               ssh->close_expected = TRUE;
+               ssh_closing((Plug)ssh, NULL, 0, 0);
+               crStop(0);
+           }
+       }
+
+       if (s->ignorepkt) /* first_kex_packet_follows */
+           crWaitUntil(pktin);                /* Ignore packet */
     }
 
     /*
@@ -5042,16 +5326,19 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Now generate and send e for Diffie-Hellman.
      */
+    set_busy_status(ssh->frontend, BUSY_CPU); /* this can take a while */
     s->e = dh_create_e(ssh->kex_ctx, s->nbits * 2);
     s->pktout = ssh2_pkt_init(s->kex_init_value);
     ssh2_pkt_addmp(s->pktout, s->e);
     ssh2_pkt_send_noqueue(ssh, s->pktout);
 
+    set_busy_status(ssh->frontend, BUSY_WAITING); /* wait for server */
     crWaitUntil(pktin);
     if (pktin->type != s->kex_reply_value) {
        bombout(("expected key exchange reply packet from server"));
        crStop(0);
     }
+    set_busy_status(ssh->frontend, BUSY_CPU); /* cogitate */
     ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
     s->f = ssh2_pkt_getmp(pktin);
     if (!s->f) {
@@ -5062,6 +5349,10 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
 
     s->K = dh_find_K(ssh->kex_ctx, s->f);
 
+    /* We assume everything from now on will be quick, and it might
+     * involve user interaction. */
+    set_busy_status(ssh->frontend, BUSY_NOT);
+
     sha_string(&ssh->exhash, s->hostkeydata, s->hostkeylen);
     if (ssh->kex == &ssh_diffiehellman_gex) {
        sha_uint32(&ssh->exhash, s->pbits);
@@ -5095,10 +5386,30 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
      */
     s->keystr = ssh->hostkey->fmtkey(s->hkey);
     s->fingerprint = ssh->hostkey->fingerprint(s->hkey);
-    verify_ssh_host_key(ssh->frontend,
-                       ssh->savedhost, ssh->savedport, ssh->hostkey->keytype,
-                       s->keystr, s->fingerprint);
-    if (s->first_kex) {                       /* don't bother logging this in rekeys */
+    ssh_set_frozen(ssh, 1);
+    s->dlgret = verify_ssh_host_key(ssh->frontend,
+                                    ssh->savedhost, ssh->savedport,
+                                    ssh->hostkey->keytype, s->keystr,
+                                   s->fingerprint,
+                                    ssh_dialog_callback, ssh);
+    if (s->dlgret < 0) {
+        do {
+            crReturn(0);
+            if (pktin) {
+                bombout(("Unexpected data from server while waiting"
+                         " for user host key response"));
+                    crStop(0);
+            }
+        } while (pktin || inlen > 0);
+        s->dlgret = ssh->user_response;
+    }
+    ssh_set_frozen(ssh, 0);
+    if (s->dlgret == 0) {
+        ssh->close_expected = TRUE;
+        ssh_closing((Plug)ssh, NULL, 0, 0);
+        crStop(0);
+    }
+    if (!s->got_session_id) {     /* don't bother logging this in rekeys */
        logevent("Host key fingerprint is:");
        logevent(s->fingerprint);
     }
@@ -5111,9 +5422,11 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
      * the session id, used in session key construction and
      * authentication.
      */
-    if (s->first_kex)
+    if (!s->got_session_id) {
        memcpy(ssh->v2_session_id, s->exchange_hash,
               sizeof(s->exchange_hash));
+       s->got_session_id = TRUE;
+    }
 
     /*
      * Send SSH2_MSG_NEWKEYS.
@@ -5231,14 +5544,25 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
     }
 
     /*
-     * Key exchange is over. Schedule a timer for our next rekey.
+     * Key exchange is over. Loop straight back round if we have a
+     * deferred rekey reason.
+     */
+    if (ssh->deferred_rekey_reason) {
+       logevent(ssh->deferred_rekey_reason);
+       pktin = NULL;
+       ssh->deferred_rekey_reason = NULL;
+       goto begin_key_exchange;
+    }
+
+    /*
+     * Otherwise, 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
@@ -5247,10 +5571,10 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
      * exchange phases, we don't pass SSH2_MSG_NEWKEYS on, because
      * it would only confuse the layer above.
      */
-    if (!s->first_kex) {
+    if (s->activated_authconn) {
        crReturn(1);
     }
-    s->first_kex = 0;
+    s->activated_authconn = TRUE;
 
     /*
      * Now we're encrypting. Begin returning 1 to the protocol main
@@ -5265,12 +5589,34 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
      */
     while (!((pktin && pktin->type == SSH2_MSG_KEXINIT) ||
             (!pktin && inlen == -1))) {
+        wait_for_rekey:
        crReturn(1);
     }
     if (pktin) {
        logevent("Server initiated key re-exchange");
     } else {
-       logevent((char *)in);
+        /*
+         * Special case: if the server bug is set that doesn't
+         * allow rekeying, we give a different log message and
+         * continue waiting. (If such a server _initiates_ a rekey,
+         * we process it anyway!)
+         */
+        if ((ssh->remote_bugs & BUG_SSH2_REKEY)) {
+            logeventf(ssh, "Server bug prevents key re-exchange (%s)",
+                      (char *)in);
+            /* Reset the counters, so that at least this message doesn't
+             * hit the event log _too_ often. */
+            ssh->outgoing_data_size = 0;
+            ssh->incoming_data_size = 0;
+            if (ssh->cfg.ssh_rekey_time != 0) {
+                ssh->next_rekey =
+                    schedule_timer(ssh->cfg.ssh_rekey_time*60*TICKSPERSEC,
+                                   ssh2_timer, ssh);
+            }
+            goto wait_for_rekey;       /* this is utterly horrid */
+        } else {
+            logeventf(ssh, "Initiating key re-exchange (%s)", (char *)in);
+        }
     }
     goto begin_key_exchange;
 
@@ -5278,7 +5624,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen,
 }
 
 /*
- * Add data to an SSH2 channel output buffer.
+ * Add data to an SSH-2 channel output buffer.
  */
 static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
                                  int len)
@@ -5287,7 +5633,7 @@ static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
 }
 
 /*
- * Attempt to send data on an SSH2 channel.
+ * Attempt to send data on an SSH-2 channel.
  */
 static int ssh2_try_send(struct ssh_channel *c)
 {
@@ -5320,8 +5666,34 @@ static int ssh2_try_send(struct ssh_channel *c)
     return bufchain_size(&c->v.v2.outbuffer);
 }
 
+static void ssh2_try_send_and_unthrottle(struct ssh_channel *c)
+{
+    int bufsize;
+    if (c->closes)
+       return;                        /* don't send on closing channels */
+    bufsize = ssh2_try_send(c);
+    if (bufsize == 0) {
+       switch (c->type) {
+         case CHAN_MAINSESSION:
+           /* stdin need not receive an unthrottle
+            * notification since it will be polled */
+           break;
+         case CHAN_X11:
+           x11_unthrottle(c->u.x11.s);
+           break;
+         case CHAN_AGENT:
+           /* agent sockets are request/response and need no
+            * buffer management */
+           break;
+         case CHAN_SOCKDATA:
+           pfd_unthrottle(c->u.pfd.s);
+           break;
+       }
+    }
+}
+
 /*
- * Potentially enlarge the window on an SSH2 channel.
+ * Potentially enlarge the window on an SSH-2 channel.
  */
 static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
 {
@@ -5335,7 +5707,14 @@ static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
     if (c->closes != 0)
        return;
 
-    if (newwin > c->v.v2.locwindow) {
+    /*
+     * Only send a WINDOW_ADJUST if there's significantly more window
+     * available than the other end thinks there is.  This saves us
+     * sending a WINDOW_ADJUST for every character in a shell session.
+     *
+     * "Significant" is arbitrarily defined as half the window size.
+     */
+    if (newwin > c->v.v2.locwindow * 2) {
        struct Packet *pktout;
 
        pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
@@ -5351,14 +5730,16 @@ 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)
+    if (c && !c->closes) {
        c->v.v2.remwindow += ssh_pkt_getuint32(pktin);
+       ssh2_try_send_and_unthrottle(c);
+    }
 }
 
 static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
 {
     char *data;
-    unsigned int length;
+    int length;
     unsigned i = ssh_pkt_getuint32(pktin);
     struct ssh_channel *c;
     c = find234(ssh->channels, &i, ssh_channelfind);
@@ -5466,7 +5847,7 @@ static void ssh2_msg_channel_close(Ssh ssh, struct Packet *pktin)
     struct Packet *pktout;
 
     c = find234(ssh->channels, &i, ssh_channelfind);
-    if (!c || ((int)c->remoteid) == -1) {
+    if (!c || c->halfopen) {
        bombout(("Received CHANNEL_CLOSE for %s channel %d\n",
                 c ? "half-open" : "nonexistent", i));
        return;
@@ -5511,7 +5892,7 @@ static void ssh2_msg_channel_close(Ssh ssh, struct Packet *pktin)
        /*
         * We used to send SSH_MSG_DISCONNECT here,
         * because I'd believed that _every_ conforming
-        * SSH2 connection had to end with a disconnect
+        * SSH-2 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
@@ -5525,6 +5906,7 @@ static void ssh2_msg_channel_close(Ssh ssh, struct Packet *pktin)
        ssh2_pkt_addstring(s->pktout, "en");    /* language tag */
        ssh2_pkt_send_noqueue(ssh, s->pktout);
 #endif
+       ssh->close_expected = TRUE;
        ssh_closing((Plug)ssh, NULL, 0, 0);
     }
 }
@@ -5541,6 +5923,7 @@ static void ssh2_msg_channel_open_confirmation(Ssh ssh, struct Packet *pktin)
     if (c->type != CHAN_SOCKDATA_DORMANT)
        return;                        /* dunno why they're confirming this */
     c->remoteid = ssh_pkt_getuint32(pktin);
+    c->halfopen = FALSE;
     c->type = CHAN_SOCKDATA;
     c->v.v2.remwindow = ssh_pkt_getuint32(pktin);
     c->v.v2.remmaxpkt = ssh_pkt_getuint32(pktin);
@@ -5572,7 +5955,6 @@ static void ssh2_msg_channel_open_failure(Ssh ssh, struct Packet *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)
@@ -5584,11 +5966,8 @@ static void ssh2_msg_channel_open_failure(Ssh ssh, struct Packet *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);
+    logeventf(ssh, "Forwarded connection refused by server: %s [%.*s]",
+             reasons[reason_code], reason_length, reason_string);
 
     pfd_close(c->u.pfd.s);
 
@@ -5625,6 +6004,7 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
        ssh2_pkt_addstring(pktout, "en");       /* language tag */
        ssh2_pkt_send_noqueue(ssh, pktout);
        connection_fatal(ssh->frontend, "%s", buf);
+       ssh->close_expected = TRUE;
        ssh_closing((Plug)ssh, NULL, 0, 0);
        return;
     }
@@ -5675,7 +6055,7 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
        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) \
+                   ((q = q + 4 + GET_32BIT(p+q))!= 0) && q == len) \
                result = TRUE; \
        } \
     } while(0)
@@ -5847,6 +6227,7 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
     }
 
     c->remoteid = remid;
+    c->halfopen = FALSE;
     if (error) {
        pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_FAILURE);
        ssh2_pkt_adduint32(pktout, c->remoteid);
@@ -5868,13 +6249,13 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
        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_adduint32(pktout, OUR_V2_MAXPKT);      /* our max pkt size */
        ssh2_pkt_send(ssh, pktout);
     }
 }
 
 /*
- * Handle the SSH2 userauth and connection layers.
+ * Handle the SSH-2 userauth and connection layers.
  */
 static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                             struct Packet *pktin)
@@ -5895,8 +6276,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET
        } type;
        int gotit, need_pw, can_pubkey, can_passwd, can_keyb_inter;
-       int tried_pubkey_config, tried_agent, tried_keyb_inter;
-       int kbd_inter_running;
+       int tried_pubkey_config, tried_agent;
+       int kbd_inter_running, kbd_inter_refused;
        int we_are_in;
        int num_prompts, curr_prompt, echo;
        char username[100];
@@ -5978,6 +6359,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                     * Terminate.
                     */
                    logevent("No username provided. Abandoning session.");
+                   ssh->close_expected = TRUE;
                     ssh_closing((Plug)ssh, NULL, 0, 0);
                    crStopV;
                }
@@ -6025,8 +6407,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 
        s->tried_pubkey_config = FALSE;
        s->tried_agent = FALSE;
-       s->tried_keyb_inter = FALSE;
        s->kbd_inter_running = FALSE;
+       s->kbd_inter_refused = FALSE;
        /* Load the pub half of ssh->cfg.keyfile so we notice if it's in Pageant */
        if (!filename_is_null(ssh->cfg.keyfile)) {
            int keytype;
@@ -6093,6 +6475,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                 */
                if (!s->gotit)
                    s->curr_prompt = 0;
+           } else if (pktin->type == SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ) {
+               /* FIXME: perhaps we should support this? */
+               bombout(("PASSWD_CHANGEREQ not yet supported"));
+               crStopV;
            } else if (pktin->type != SSH2_MSG_USERAUTH_FAILURE) {
                bombout(("Strange packet received during authentication: type %d",
                         pktin->type));
@@ -6216,19 +6602,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                    s->p = s->response + 5;
                    s->nkeys = GET_32BIT(s->p);
                    s->p += 4;
-                   {
-                       char buf[64];
-                       sprintf(buf, "Pageant has %d SSH2 keys", s->nkeys);
-                       logevent(buf);
-                   }
+                   logeventf(ssh, "Pageant has %d SSH-2 keys", s->nkeys);
                    for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
                        void *vret;
 
-                       {
-                           char buf[64];
-                           sprintf(buf, "Trying Pageant key #%d", s->keyi);
-                           logevent(buf);
-                       }
+                       logeventf(ssh, "Trying Pageant key #%d", s->keyi);
                        s->pklen = GET_32BIT(s->p);
                        s->p += 4;
                        if (s->publickey_blob &&
@@ -6417,10 +6795,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                }
            }
 
-           if (!s->method && s->can_keyb_inter && !s->tried_keyb_inter) {
+           if (!s->method && s->can_keyb_inter && !s->kbd_inter_refused &&
+               !s->kbd_inter_running) {
                s->method = AUTH_KEYBOARD_INTERACTIVE;
                s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
-               s->tried_keyb_inter = TRUE;
 
                ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
                ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
@@ -6439,9 +6817,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                        s->gotit = TRUE;
                    logevent("Keyboard-interactive authentication refused");
                    s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET;
+                   s->kbd_inter_refused = TRUE; /* don't try it again */
                    continue;
                }
 
+               c_write_str(ssh, "Using keyboard-interactive authentication.\r\n");
                s->kbd_inter_running = TRUE;
                s->curr_prompt = 0;
            }
@@ -6449,7 +6829,6 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
            if (s->kbd_inter_running) {
                s->method = AUTH_KEYBOARD_INTERACTIVE;
                s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
-               s->tried_keyb_inter = TRUE;
 
                ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
                ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
@@ -6535,6 +6914,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                        logevent("Unable to authenticate");
                        connection_fatal(ssh->frontend,
                                         "Unable to authenticate");
+                       ssh->close_expected = TRUE;
                         ssh_closing((Plug)ssh, NULL, 0, 0);
                        crStopV;
                    }
@@ -6637,20 +7017,16 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                }
            } else if (s->method == AUTH_PASSWORD) {
                /*
-                * We send the password packet lumped tightly together with
-                * an SSH_MSG_IGNORE packet. The IGNORE packet contains a
-                * string long enough to make the total length of the two
-                * packets constant. This should ensure that a passive
-                * listener doing traffic analyis can't work out the length
-                * of the password.
+                * We pad out the password packet to 256 bytes to make
+                * it harder for an attacker to find the length of the
+                * user's password.
                 *
-                * For this to work, we need an assumption about the
-                * maximum length of the password packet. I think 256 is
-                * pretty conservative. Anyone using a password longer than
-                * that probably doesn't have much to worry about from
+                * Anyone using a password longer than 256 bytes
+                * probably doesn't have much to worry about from
                 * people who find out how long their password is!
                 */
                s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+               s->pktout->forcepad = 256;
                ssh2_pkt_addstring(s->pktout, s->username);
                ssh2_pkt_addstring(s->pktout, "ssh-connection");        /* service requested */
                ssh2_pkt_addstring(s->pktout, "password");
@@ -6659,46 +7035,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                ssh2_pkt_addstring(s->pktout, s->password);
                memset(s->password, 0, sizeof(s->password));
                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
-                * reason, we don't do this trick at all because we gain
-                * nothing by it.
-                */
-               if (ssh->cscipher) {
-                   int stringlen, i;
-
-                   stringlen = (256 - ssh->deferred_len);
-                   stringlen += ssh->cscipher->blksize - 1;
-                   stringlen -= (stringlen % ssh->cscipher->blksize);
-                   if (ssh->cscomp) {
-                       /*
-                        * Temporarily disable actual compression,
-                        * so we can guarantee to get this string
-                        * exactly the length we want it. The
-                        * compression-disabling routine should
-                        * return an integer indicating how many
-                        * bytes we should adjust our string length
-                        * by.
-                        */
-                       stringlen -= 
-                           ssh->cscomp->disable_compression(ssh->cs_comp_ctx);
-                   }
-                   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(s->pktout, &c, 1);
-                   }
-                   ssh2_pkt_defer(ssh, s->pktout);
-               }
-               ssh_pkt_defersend(ssh);
+               ssh2_pkt_send(ssh, s->pktout);
                logevent("Sent password");
                s->type = AUTH_TYPE_PASSWORD;
            } else if (s->method == AUTH_KEYBOARD_INTERACTIVE) {
                if (s->curr_prompt == 0) {
                    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
+                   s->pktout->forcepad = 256;
                    ssh2_pkt_adduint32(s->pktout, s->num_prompts);
                }
                if (s->need_pw) {      /* only add pw if we just got one! */
@@ -6733,6 +7076,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                                   " methods available");
                ssh2_pkt_addstring(s->pktout, "en");    /* language tag */
                ssh2_pkt_send_noqueue(ssh, s->pktout);
+               ssh->close_expected = TRUE;
                 ssh_closing((Plug)ssh, NULL, 0, 0);
                crStopV;
            }
@@ -6768,7 +7112,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        ssh2_pkt_adduint32(s->pktout, ssh->mainchan->localid);
        ssh->mainchan->v.v2.locwindow = OUR_V2_WINSIZE;
        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_adduint32(s->pktout, OUR_V2_MAXPKT);    /* our max pkt size */
        ssh2_pkt_send(ssh, s->pktout);
        crWaitUntilV(pktin);
        if (pktin->type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
@@ -6781,6 +7125,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
            crStopV;
        }
        ssh->mainchan->remoteid = ssh_pkt_getuint32(pktin);
+       ssh->mainchan->halfopen = FALSE;
        ssh->mainchan->type = CHAN_MAINSESSION;
        ssh->mainchan->closes = 0;
        ssh->mainchan->v.v2.remwindow = ssh_pkt_getuint32(pktin);
@@ -7001,6 +7346,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        } else {
            subsys = ssh->cfg.ssh_subsys;
            cmd = ssh->cfg.remote_cmd_ptr;
+           if (!cmd) cmd = ssh->cfg.remote_cmd;
        }
 
        s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
@@ -7085,30 +7431,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
            /*
             * Try to send data on all channels if we can.
             */
-           for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
-               int bufsize;
-               if (c->closes)
-                   continue;          /* don't send on closing channels */
-               bufsize = ssh2_try_send(c);
-               if (bufsize == 0) {
-                   switch (c->type) {
-                     case CHAN_MAINSESSION:
-                       /* stdin need not receive an unthrottle
-                        * notification since it will be polled */
-                       break;
-                     case CHAN_X11:
-                       x11_unthrottle(c->u.x11.s);
-                       break;
-                     case CHAN_AGENT:
-                       /* agent sockets are request/response and need no
-                        * buffer management */
-                       break;
-                     case CHAN_SOCKDATA:
-                       pfd_unthrottle(c->u.pfd.s);
-                       break;
-                   }
-               }
-           }
+           for (i = 0; NULL != (c = index234(ssh->channels, i)); i++)
+               ssh2_try_send_and_unthrottle(c);
        }
     }
 
@@ -7116,9 +7440,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 }
 
 /*
- * Handlers for SSH2 messages that might arrive at any moment.
+ * Handlers for SSH-2 messages that might arrive at any moment.
  */
-void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
+static void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
 {
     /* log reason code in disconnect message */
     char *buf, *msg;
@@ -7147,10 +7471,10 @@ void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
     sfree(buf);
 }
 
-void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
+static void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
 {
     /* log the debug message */
-    char *buf, *msg;
+    char *msg;
     int msglen;
     int always_display;
 
@@ -7158,12 +7482,10 @@ void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
     always_display = ssh2_pkt_getbool(pktin);
     ssh_pkt_getstring(pktin, &msg, &msglen);
 
-    buf = dupprintf("Remote debug message: %.*s", msglen, msg);
-    logevent(buf);
-    sfree(buf);
+    logeventf(ssh, "Remote debug message: %.*s", msglen, msg);
 }
 
-void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
+static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
 {
     struct Packet *pktout;
     pktout = ssh2_pkt_init(SSH2_MSG_UNIMPLEMENTED);
@@ -7176,7 +7498,7 @@ void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
 }
 
 /*
- * Handle the top-level SSH2 protocol.
+ * Handle the top-level SSH-2 protocol.
  */
 static void ssh2_protocol_setup(Ssh ssh)
 {
@@ -7230,7 +7552,7 @@ static void ssh2_protocol_setup(Ssh ssh)
      * 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_IGNORE] = ssh_msg_ignore; /* shared with SSH-1 */
     ssh->packet_dispatch[SSH2_MSG_DEBUG] = ssh2_msg_debug;
 }
 
@@ -7238,16 +7560,19 @@ static void ssh2_timer(void *ctx, long now)
 {
     Ssh ssh = (Ssh)ctx;
 
+    if (ssh->state == SSH_STATE_CLOSED)
+       return;
+
     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);
+       do_ssh2_transport(ssh, "timeout", -1, NULL);
     }
 }
 
-static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen,
+static void ssh2_protocol(Ssh ssh, void *vin, int inlen,
                          struct Packet *pktin)
 {
+    unsigned char *in = (unsigned char *)vin;
     if (ssh->state == SSH_STATE_CLOSED)
        return;
 
@@ -7256,8 +7581,7 @@ static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen,
        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);
+           do_ssh2_transport(ssh, "too much data received", -1, NULL);
     }
 
     if (pktin && ssh->packet_dispatch[pktin->type]) {
@@ -7316,6 +7640,7 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->kex_ctx = NULL;
     ssh->hostkey = NULL;
     ssh->exitcode = -1;
+    ssh->close_expected = FALSE;
     ssh->state = SSH_STATE_PREPACKET;
     ssh->size_needed = FALSE;
     ssh->eof_needed = FALSE;
@@ -7348,6 +7673,9 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->queuelen = ssh->queuesize = 0;
     ssh->queueing = FALSE;
     ssh->qhead = ssh->qtail = NULL;
+    ssh->deferred_rekey_reason = NULL;
+    bufchain_init(&ssh->queued_incoming_data);
+    ssh->frozen = FALSE;
 
     *backend_handle = ssh;
 
@@ -7470,10 +7798,11 @@ static void ssh_free(void *handle)
        ssh->crcda_ctx = NULL;
     }
     if (ssh->s)
-       ssh_do_close(ssh);
+       ssh_do_close(ssh, TRUE);
     expire_timer_context(ssh);
     if (ssh->pinger)
        pinger_free(ssh->pinger);
+    bufchain_clear(&ssh->queued_incoming_data);
     sfree(ssh);
 
     random_unref();
@@ -7485,7 +7814,7 @@ static void ssh_free(void *handle)
 static void ssh_reconfig(void *handle, Config *cfg)
 {
     Ssh ssh = (Ssh) handle;
-    char *rekeying = NULL;
+    char *rekeying = NULL, rekey_mandatory = FALSE;
     unsigned long old_max_data_size;
 
     pinger_reconfig(ssh->pinger, &ssh->cfg, cfg);
@@ -7497,7 +7826,7 @@ static void ssh_reconfig(void *handle, Config *cfg)
        long now = GETTICKCOUNT();
 
        if (new_next - now < 0) {
-           rekeying = "Initiating key re-exchange (timeout shortened)";
+           rekeying = "timeout shortened";
        } else {
            ssh->next_rekey = schedule_timer(new_next - now, ssh2_timer, ssh);
        }
@@ -7509,14 +7838,30 @@ static void ssh_reconfig(void *handle, Config *cfg)
        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)";
+           rekeying = "data limit lowered";
     }
 
-    if (rekeying && !ssh->kex_in_progress) {
-       do_ssh2_transport(ssh, rekeying, -1, NULL);
+    if (ssh->cfg.compression != cfg->compression) {
+       rekeying = "compression setting changed";
+       rekey_mandatory = TRUE;
+    }
+
+    if (ssh->cfg.ssh2_des_cbc != cfg->ssh2_des_cbc ||
+       memcmp(ssh->cfg.ssh_cipherlist, cfg->ssh_cipherlist,
+              sizeof(ssh->cfg.ssh_cipherlist))) {
+       rekeying = "cipher settings changed";
+       rekey_mandatory = TRUE;
     }
 
     ssh->cfg = *cfg;                  /* STRUCTURE COPY */
+
+    if (rekeying) {
+       if (!ssh->kex_in_progress) {
+           do_ssh2_transport(ssh, rekeying, -1, NULL);
+       } else if (rekey_mandatory) {
+           ssh->deferred_rekey_reason = rekeying;
+       }
+    }
 }
 
 /*
@@ -7702,6 +8047,7 @@ static void ssh_special(void *handle, Telnet_Special code)
            struct Packet *pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_EOF);
            ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
            ssh2_pkt_send(ssh, pktout);
+            ssh->send_ok = 0;          /* now stop trying to read from stdin */
        }
        logevent("Sent EOF message");
     } else if (code == TS_PING || code == TS_NOP) {
@@ -7717,14 +8063,13 @@ static void ssh_special(void *handle, Telnet_Special code)
        }
     } 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);
+           do_ssh2_transport(ssh, "at user request", -1, NULL);
        }
     } else if (code == TS_BRK) {
        if (ssh->state == SSH_STATE_CLOSED
            || ssh->state == SSH_STATE_PREPACKET) return;
        if (ssh->version == 1) {
-           logevent("Unable to send BREAK signal in SSH1");
+           logevent("Unable to send BREAK signal in SSH-1");
        } else if (ssh->mainchan) {
            pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
            ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
@@ -7776,7 +8121,7 @@ void *new_sock_channel(void *handle, Socket s)
     c->ssh = ssh;
 
     if (c) {
-       c->remoteid = -1;              /* to be set when open confirmed */
+       c->halfopen = TRUE;
        c->localid = alloc_channel_id(ssh);
        c->closes = 0;
        c->type = CHAN_SOCKDATA_DORMANT;/* identify channel type */
@@ -7826,7 +8171,7 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
        ssh2_pkt_adduint32(pktout, c->localid);
        c->v.v2.locwindow = OUR_V2_WINSIZE;
        ssh2_pkt_adduint32(pktout, c->v.v2.locwindow);/* our window size */
-       ssh2_pkt_adduint32(pktout, 0x4000UL);      /* our max pkt size */
+       ssh2_pkt_adduint32(pktout, OUR_V2_MAXPKT);      /* our max pkt size */
        ssh2_pkt_addstring(pktout, hostname);
        ssh2_pkt_adduint32(pktout, port);
        /*