Colin's and my fixes to connection_fatal().
[u/mdw/putty] / ssh.c
diff --git a/ssh.c b/ssh.c
index 072a1b3..11683c0 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,3 @@
-#include <windows.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #define TRUE 1
 #endif
 
-#define logevent(s) { logevent(s); \
-                      if ((flags & FLAG_STDERR) && (flags & FLAG_VERBOSE)) \
-                      { fprintf(stderr, "%s\n", s); fflush(stderr); } }
-
-/* logevent, only printf-formatted. */
-void logeventf(char *fmt, ...)
-{
-    va_list ap;
-    char stuff[200];
-
-    va_start(ap, fmt);
-    vsprintf(stuff, fmt, ap);
-    va_end(ap);
-    logevent(stuff);
-}
-
-#define bombout(msg) ( ssh->state = SSH_STATE_CLOSED, \
-                          (ssh->s ? sk_close(ssh->s), ssh->s = NULL : 0), \
-                          logeventf msg, connection_fatal msg )
-
 #define SSH1_MSG_DISCONNECT                       1    /* 0x1 */
 #define SSH1_SMSG_PUBLIC_KEY                      2    /* 0x2 */
 #define SSH1_CMSG_SESSION_KEY                     3    /* 0x3 */
@@ -184,10 +163,11 @@ static const char *const ssh2_disconnect_reasons[] = {
 #define BUG_SSH2_RSA_PADDING                    16
 #define BUG_SSH2_DERIVEKEY                       32
 #define BUG_SSH2_DH_GEX                          64
+#define BUG_SSH2_PK_SESSIONID                   128
 
 #define translate(x) if (type == x) return #x
 #define translatec(x,ctx) if (type == x && (pkt_ctx & ctx)) return #x
-char *ssh1_pkt_type(int type)
+static char *ssh1_pkt_type(int type)
 {
     translate(SSH1_MSG_DISCONNECT);
     translate(SSH1_SMSG_PUBLIC_KEY);
@@ -232,7 +212,7 @@ char *ssh1_pkt_type(int type)
     translate(SSH1_CMSG_AUTH_CCARD_RESPONSE);
     return "unknown";
 }
-char *ssh2_pkt_type(int pkt_ctx, int type)
+static char *ssh2_pkt_type(int pkt_ctx, int type)
 {
     translate(SSH2_MSG_DISCONNECT);
     translate(SSH2_MSG_IGNORE);
@@ -289,11 +269,30 @@ char *ssh2_pkt_type(int pkt_ctx, int type)
 
 enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM };
 
-/* Coroutine mechanics for the sillier bits of the code */
+/*
+ * Coroutine mechanics for the sillier bits of the code. If these
+ * macros look impenetrable to you, you might find it helpful to
+ * read
+ * 
+ *   http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
+ * 
+ * which explains the theory behind these macros.
+ * 
+ * In particular, if you are getting `case expression not constant'
+ * errors when building with MS Visual Studio, this is because MS's
+ * Edit and Continue debugging feature causes their compiler to
+ * violate ANSI C. To disable Edit and Continue debugging:
+ * 
+ *  - right-click ssh.c in the FileView
+ *  - click Settings
+ *  - select the C/C++ tab and the General category
+ *  - under `Debug info:', select anything _other_ than `Program
+ *    Database for Edit and Continue'.
+ */
 #define crBegin(v)     { int *crLine = &v; switch(v) { case 0:;
 #define crState(t) \
     struct t *s; \
-    if (!ssh->t) ssh->t = smalloc(sizeof(struct t)); \
+    if (!ssh->t) ssh->t = snew(struct t); \
     s = ssh->t;
 #define crFinish(z)    } *crLine = 0; return (z); }
 #define crFinishV      } *crLine = 0; return; }
@@ -312,21 +311,6 @@ enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM };
 
 typedef struct ssh_tag *Ssh;
 
-extern char *x11_init(Socket *, char *, void *);
-extern void x11_close(Socket);
-extern int x11_send(Socket, char *, int);
-extern void x11_invent_auth(char *, int, char *, int);
-extern void x11_unthrottle(Socket s);
-extern void x11_override_throttle(Socket s, int enable);
-
-extern char *pfd_newconnect(Socket * s, char *hostname, int port, void *c);
-extern char *pfd_addforward(char *desthost, int destport, int port);
-extern void pfd_close(Socket s);
-extern int pfd_send(Socket s, char *data, int len);
-extern void pfd_confirm(Socket s);
-extern void pfd_unthrottle(Socket s);
-extern void pfd_override_throttle(Socket s, int enable);
-
 static void ssh2_pkt_init(Ssh, int pkt_type);
 static void ssh2_pkt_addbool(Ssh, unsigned char value);
 static void ssh2_pkt_adduint32(Ssh, unsigned long value);
@@ -334,10 +318,12 @@ static void ssh2_pkt_addstring_start(Ssh);
 static void ssh2_pkt_addstring_str(Ssh, char *data);
 static void ssh2_pkt_addstring_data(Ssh, char *data, int len);
 static void ssh2_pkt_addstring(Ssh, char *data);
-static char *ssh2_mpint_fmt(Bignum b, int *len);
+static unsigned char *ssh2_mpint_fmt(Bignum b, int *len);
 static void ssh2_pkt_addmp(Ssh, Bignum b);
 static int ssh2_pkt_construct(Ssh);
 static void ssh2_pkt_send(Ssh);
+static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt);
+static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt);
 
 /*
  * Buffer management constants. There are several of these for
@@ -531,6 +517,7 @@ static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len);
 static void ssh_throttle_all(Ssh ssh, int enable, int bufsize);
 static void ssh2_set_window(struct ssh_channel *c, unsigned newwin);
 static int ssh_sendbuffer(void *handle);
+static void ssh_do_close(Ssh ssh);
 
 struct rdpkt1_state_tag {
     long len, pad, biglen, to_read;
@@ -555,6 +542,9 @@ struct ssh_tag {
 
     Socket s;
 
+    void *ldisc;
+    void *logctx;
+
     unsigned char session_key[32];
     int v1_compressing;
     int v1_remote_protoflags;
@@ -625,6 +615,8 @@ struct ssh_tag {
     char *portfwd_strptr;
     int pkt_ctx;
 
+    void *x11auth;
+
     int version;
     int v1_throttle_count;
     int overall_bufsize;
@@ -651,8 +643,46 @@ struct ssh_tag {
 
     void (*protocol) (Ssh ssh, unsigned char *in, int inlen, int ispkt);
     int (*s_rdpkt) (Ssh ssh, unsigned char **data, int *datalen);
+
+    /*
+     * We maintain a full _copy_ of a Config structure here, not
+     * merely a pointer to it. That way, when we're passed a new
+     * one for reconfiguration, we can check the differences and
+     * potentially reconfigure port forwardings etc in mid-session.
+     */
+    Config cfg;
+
+    /*
+     * Used to transfer data back from async agent callbacks.
+     */
+    void *agent_response;
+    int agent_response_len;
 };
 
+#define logevent(s) logevent(ssh->frontend, s)
+
+/* logevent, only printf-formatted. */
+static void logeventf(Ssh ssh, char *fmt, ...)
+{
+    va_list ap;
+    char *buf;
+
+    va_start(ap, fmt);
+    buf = dupvprintf(fmt, ap);
+    va_end(ap);
+    logevent(buf);
+    sfree(buf);
+}
+
+#define bombout(msg) \
+    do { \
+        char *text = dupprintf msg; \
+       ssh_do_close(ssh); \
+        logevent(text); \
+        connection_fatal(ssh->frontend, "%s", text); \
+        sfree(text); \
+    } while (0)
+
 static int ssh_channelcmp(void *av, void *bv)
 {
     struct ssh_channel *a = (struct ssh_channel *) av;
@@ -738,7 +768,7 @@ static int alloc_channel_id(Ssh ssh)
     return low + 1 + CHANNEL_NUMBER_OFFSET;
 }
 
-static void c_write(Ssh ssh, char *buf, int len)
+static void c_write(Ssh ssh, const char *buf, int len)
 {
     if ((flags & FLAG_STDERR)) {
        int i;
@@ -750,7 +780,7 @@ static void c_write(Ssh ssh, char *buf, int len)
     from_backend(ssh->frontend, 1, buf, len);
 }
 
-static void c_write_untrusted(Ssh ssh, char *buf, int len)
+static void c_write_untrusted(Ssh ssh, const char *buf, int len)
 {
     int i;
     for (i = 0; i < len; i++) {
@@ -761,7 +791,7 @@ static void c_write_untrusted(Ssh ssh, char *buf, int len)
     }
 }
 
-static void c_write_str(Ssh ssh, char *buf)
+static void c_write_str(Ssh ssh, const char *buf)
 {
     c_write(ssh, buf, strlen(buf));
 }
@@ -798,7 +828,8 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 
     if (ssh->pktin.maxlen < st->biglen) {
        ssh->pktin.maxlen = st->biglen;
-       ssh->pktin.data = srealloc(ssh->pktin.data, st->biglen + APIEXTRA);
+       ssh->pktin.data = sresize(ssh->pktin.data, st->biglen + APIEXTRA,
+                                 unsigned char);
     }
 
     st->to_read = st->biglen;
@@ -819,7 +850,7 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     if (ssh->cipher && detect_attack(ssh->crcda_ctx, ssh->pktin.data,
                                     st->biglen, NULL)) {
         bombout(("Network attack (CRC compensation) detected!"));
-        crReturn(0);
+        crStop(0);
     }
 
     if (ssh->cipher)
@@ -829,7 +860,7 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     st->gotcrc = GET_32BIT(ssh->pktin.data + st->biglen - 4);
     if (st->gotcrc != st->realcrc) {
        bombout(("Incorrect CRC received on packet"));
-       crReturn(0);
+       crStop(0);
     }
 
     ssh->pktin.body = ssh->pktin.data + st->pad + 1;
@@ -843,8 +874,9 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 
        if (ssh->pktin.maxlen < st->pad + decomplen) {
            ssh->pktin.maxlen = st->pad + decomplen;
-           ssh->pktin.data = srealloc(ssh->pktin.data,
-                                      ssh->pktin.maxlen + APIEXTRA);
+           ssh->pktin.data = sresize(ssh->pktin.data,
+                                     ssh->pktin.maxlen + APIEXTRA,
+                                     unsigned char);
            ssh->pktin.body = ssh->pktin.data + st->pad + 1;
        }
 
@@ -855,8 +887,11 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 
     ssh->pktin.type = ssh->pktin.body[-1];
 
-    log_packet(PKT_INCOMING, ssh->pktin.type, ssh1_pkt_type(ssh->pktin.type),
-              ssh->pktin.body, ssh->pktin.length);
+    if (ssh->logctx)
+       log_packet(ssh->logctx,
+                  PKT_INCOMING, ssh->pktin.type,
+                  ssh1_pkt_type(ssh->pktin.type),
+                  ssh->pktin.body, ssh->pktin.length);
 
     if (ssh->pktin.type == SSH1_SMSG_STDOUT_DATA ||
        ssh->pktin.type == SSH1_SMSG_STDERR_DATA ||
@@ -866,7 +901,7 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
        long stringlen = GET_32BIT(ssh->pktin.body);
        if (stringlen + 4 != ssh->pktin.length) {
            bombout(("Received data packet with bogus string length"));
-           crReturn(0);
+           crStop(0);
        }
     }
 
@@ -899,7 +934,7 @@ static int ssh1_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
        buf[nowlen + msglen] = '\0';
        /* logevent(buf); (this is now done within the bombout macro) */
        bombout(("Server sent disconnect message:\n\"%s\"", buf+nowlen));
-       crReturn(0);
+       crStop(0);
     }
 
     crFinish(0);
@@ -923,7 +958,8 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
 
     if (ssh->pktin.maxlen < st->cipherblk) {
        ssh->pktin.maxlen = st->cipherblk;
-       ssh->pktin.data = srealloc(ssh->pktin.data, st->cipherblk + APIEXTRA);
+       ssh->pktin.data = sresize(ssh->pktin.data, st->cipherblk + APIEXTRA,
+                                 unsigned char);
     }
 
     /*
@@ -953,7 +989,7 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      */
     if (st->len < 0 || st->pad < 0 || st->len + st->pad < 0) {
        bombout(("Incoming packet was garbled on decryption"));
-       crReturn(0);
+       crStop(0);
     }
 
     /*
@@ -974,8 +1010,9 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      */
     if (ssh->pktin.maxlen < st->packetlen + st->maclen) {
        ssh->pktin.maxlen = st->packetlen + st->maclen;
-       ssh->pktin.data = srealloc(ssh->pktin.data,
-                                  ssh->pktin.maxlen + APIEXTRA);
+       ssh->pktin.data = sresize(ssh->pktin.data,
+                                 ssh->pktin.maxlen + APIEXTRA,
+                                 unsigned char);
     }
 
     /*
@@ -1001,7 +1038,7 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
        && !ssh->scmac->verify(ssh->sc_mac_ctx, ssh->pktin.data, st->len + 4,
                               st->incoming_sequence)) {
        bombout(("Incorrect MAC received on packet"));
-       crReturn(0);
+       crStop(0);
     }
     st->incoming_sequence++;          /* whether or not we MACed */
 
@@ -1017,8 +1054,9 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
                                    &newpayload, &newlen)) {
            if (ssh->pktin.maxlen < newlen + 5) {
                ssh->pktin.maxlen = newlen + 5;
-               ssh->pktin.data = srealloc(ssh->pktin.data,
-                                          ssh->pktin.maxlen + APIEXTRA);
+               ssh->pktin.data = sresize(ssh->pktin.data,
+                                         ssh->pktin.maxlen + APIEXTRA,
+                                         unsigned char);
            }
            ssh->pktin.length = 5 + newlen;
            memcpy(ssh->pktin.data + 5, newpayload, newlen);
@@ -1029,9 +1067,10 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     ssh->pktin.savedpos = 6;
     ssh->pktin.type = ssh->pktin.data[5];
 
-    log_packet(PKT_INCOMING, ssh->pktin.type,
-              ssh2_pkt_type(ssh->pkt_ctx, ssh->pktin.type),
-              ssh->pktin.data+6, ssh->pktin.length-6);
+    if (ssh->logctx)
+       log_packet(ssh->logctx, PKT_INCOMING, ssh->pktin.type,
+                  ssh2_pkt_type(ssh->pkt_ctx, ssh->pktin.type),
+                  ssh->pktin.data+6, ssh->pktin.length-6);
 
     switch (ssh->pktin.type) {
         /*
@@ -1040,31 +1079,30 @@ static int ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
       case SSH2_MSG_DISCONNECT:
         {
             /* log reason code in disconnect message */
-            char buf[256];
+            char *buf;
+           int nowlen;
             int reason = GET_32BIT(ssh->pktin.data + 6);
             unsigned msglen = GET_32BIT(ssh->pktin.data + 10);
-            unsigned nowlen;
+
             if (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) {
-                sprintf(buf, "Received disconnect message (%s)",
-                        ssh2_disconnect_reasons[reason]);
+                buf = dupprintf("Received disconnect message (%s)",
+                               ssh2_disconnect_reasons[reason]);
             } else {
-                sprintf(buf, "Received disconnect message (unknown type %d)",
-                        reason);
+                buf = dupprintf("Received disconnect message (unknown"
+                               " type %d)", reason);
             }
             logevent(buf);
-            strcpy(buf, "Disconnection message text: ");
-            nowlen = strlen(buf);
-            if (msglen > sizeof(buf) - nowlen - 1)
-                msglen = sizeof(buf) - nowlen - 1;
-            memcpy(buf + nowlen, ssh->pktin.data + 14, msglen);
-            buf[nowlen + msglen] = '\0';
+           sfree(buf);
+            buf = dupprintf("Disconnection message text: %n%.*s",
+                           &nowlen, msglen, ssh->pktin.data + 14);
             logevent(buf);
             bombout(("Server sent disconnect message\ntype %d (%s):\n\"%s\"",
                      reason,
                      (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) ?
                      ssh2_disconnect_reasons[reason] : "unknown",
                      buf+nowlen));
-            crReturn(0);
+           sfree(buf);
+            crStop(0);
         }
         break;
       case SSH2_MSG_IGNORE:
@@ -1151,9 +1189,11 @@ static void ssh1_pktout_size(Ssh ssh, int len)
 #ifdef MSCRYPTOAPI
        /* Allocate enough buffer space for extra block
         * for MS CryptEncrypt() */
-       ssh->pktout.data = srealloc(ssh->pktout.data, biglen + 12);
+       ssh->pktout.data = sresize(ssh->pktout.data, biglen + 12,
+                                  unsigned char);
 #else
-       ssh->pktout.data = srealloc(ssh->pktout.data, biglen + 4);
+       ssh->pktout.data = sresize(ssh->pktout.data, biglen + 4,
+                                  unsigned char);
 #endif
     }
     ssh->pktout.body = ssh->pktout.data + 4 + pad + 1;
@@ -1167,13 +1207,25 @@ static void s_wrpkt_start(Ssh ssh, int type, int len)
 
 static int s_wrpkt_prepare(Ssh ssh)
 {
-    int pad, len, biglen, i;
+    int pad, biglen, i;
     unsigned long crc;
+#ifdef __SC__
+    /*
+     * XXX various versions of SC (including 8.8.4) screw up the
+     * register allocation in this function and use the same register
+     * (D6) for len and as a temporary, with predictable results.  The
+     * following sledgehammer prevents this.
+     */
+    volatile
+#endif
+    int len;
 
     ssh->pktout.body[-1] = ssh->pktout.type;
 
-    log_packet(PKT_OUTGOING, ssh->pktout.type, ssh1_pkt_type(ssh->pktout.type),
-              ssh->pktout.body, ssh->pktout.length);
+    if (ssh->logctx)
+       log_packet(ssh->logctx, PKT_OUTGOING, ssh->pktout.type,
+                  ssh1_pkt_type(ssh->pktout.type),
+                  ssh->pktout.body, ssh->pktout.length);
 
     if (ssh->v1_compressing) {
        unsigned char *compblk;
@@ -1206,7 +1258,7 @@ static void s_wrpkt(Ssh ssh)
 {
     int len, backlog;
     len = s_wrpkt_prepare(ssh);
-    backlog = sk_write(ssh->s, ssh->pktout.data, len);
+    backlog = sk_write(ssh->s, (char *)ssh->pktout.data, len);
     if (backlog > SSH_MAX_BACKLOG)
        ssh_throttle_all(ssh, 1, backlog);
 }
@@ -1217,8 +1269,9 @@ static void s_wrpkt_defer(Ssh ssh)
     len = s_wrpkt_prepare(ssh);
     if (ssh->deferred_len + len > ssh->deferred_size) {
        ssh->deferred_size = ssh->deferred_len + len + 128;
-       ssh->deferred_send_data = srealloc(ssh->deferred_send_data,
-                                          ssh->deferred_size);
+       ssh->deferred_send_data = sresize(ssh->deferred_send_data,
+                                         ssh->deferred_size,
+                                         unsigned char);
     }
     memcpy(ssh->deferred_send_data + ssh->deferred_len, ssh->pktout.data, len);
     ssh->deferred_len += len;
@@ -1242,7 +1295,7 @@ static void construct_packet(Ssh ssh, int pkttype, va_list ap1, va_list ap2)
            pktlen += 4;
            break;
          case PKT_CHAR:
-           (void) va_arg(ap1, char);
+           (void) va_arg(ap1, int);
            pktlen++;
            break;
          case PKT_DATA:
@@ -1252,7 +1305,7 @@ static void construct_packet(Ssh ssh, int pkttype, va_list ap1, va_list ap2)
            break;
          case PKT_STR:
            argp = va_arg(ap1, unsigned char *);
-           arglen = strlen(argp);
+           arglen = strlen((char *)argp);
            pktlen += 4 + arglen;
            break;
          case PKT_BIGNUM:
@@ -1275,7 +1328,7 @@ static void construct_packet(Ssh ssh, int pkttype, va_list ap1, va_list ap2)
            p += 4;
            break;
          case PKT_CHAR:
-           argchar = va_arg(ap2, unsigned char);
+           argchar = (unsigned char) va_arg(ap2, int);
            *p = argchar;
            p++;
            break;
@@ -1287,7 +1340,7 @@ static void construct_packet(Ssh ssh, int pkttype, va_list ap1, va_list ap2)
            break;
          case PKT_STR:
            argp = va_arg(ap2, unsigned char *);
-           arglen = strlen(argp);
+           arglen = strlen((char *)argp);
            PUT_32BIT(p, arglen);
            memcpy(p + 4, argp, arglen);
            p += 4 + arglen;
@@ -1365,8 +1418,9 @@ static void ssh2_pkt_ensure(Ssh ssh, int length)
 {
     if (ssh->pktout.maxlen < length) {
        ssh->pktout.maxlen = length + 256;
-       ssh->pktout.data = srealloc(ssh->pktout.data,
-                                   ssh->pktout.maxlen + APIEXTRA);
+       ssh->pktout.data = sresize(ssh->pktout.data,
+                                  ssh->pktout.maxlen + APIEXTRA,
+                                  unsigned char);
        if (!ssh->pktout.data)
            fatalbox("Out of memory");
     }
@@ -1418,11 +1472,11 @@ static void ssh2_pkt_addstring(Ssh ssh, char *data)
     ssh2_pkt_addstring_start(ssh);
     ssh2_pkt_addstring_str(ssh, data);
 }
-static char *ssh2_mpint_fmt(Bignum b, int *len)
+static unsigned char *ssh2_mpint_fmt(Bignum b, int *len)
 {
     unsigned char *p;
     int i, n = (bignum_bitcount(b) + 7) / 8;
-    p = smalloc(n + 1);
+    p = snewn(n + 1, unsigned char);
     if (!p)
        fatalbox("out of memory");
     p[0] = 0;
@@ -1441,7 +1495,7 @@ static void ssh2_pkt_addmp(Ssh ssh, Bignum b)
     int len;
     p = ssh2_mpint_fmt(b, &len);
     ssh2_pkt_addstring_start(ssh);
-    ssh2_pkt_addstring_data(ssh, p, len);
+    ssh2_pkt_addstring_data(ssh, (char *)p, len);
     sfree(p);
 }
 
@@ -1454,9 +1508,10 @@ static int ssh2_pkt_construct(Ssh ssh)
 {
     int cipherblk, maclen, padding, i;
 
-    log_packet(PKT_OUTGOING, ssh->pktout.data[5],
-              ssh2_pkt_type(ssh->pkt_ctx, ssh->pktout.data[5]),
-              ssh->pktout.data + 6, ssh->pktout.length - 6);
+    if (ssh->logctx)
+       log_packet(ssh->logctx, PKT_OUTGOING, ssh->pktout.data[5],
+                  ssh2_pkt_type(ssh->pkt_ctx, ssh->pktout.data[5]),
+                  ssh->pktout.data + 6, ssh->pktout.length - 6);
 
     /*
      * Compress packet payload.
@@ -1511,7 +1566,7 @@ static void ssh2_pkt_send(Ssh ssh)
     int len;
     int backlog;
     len = ssh2_pkt_construct(ssh);
-    backlog = sk_write(ssh->s, ssh->pktout.data, len);
+    backlog = sk_write(ssh->s, (char *)ssh->pktout.data, len);
     if (backlog > SSH_MAX_BACKLOG)
        ssh_throttle_all(ssh, 1, backlog);
 }
@@ -1532,8 +1587,9 @@ static void ssh2_pkt_defer(Ssh ssh)
     int len = ssh2_pkt_construct(ssh);
     if (ssh->deferred_len + len > ssh->deferred_size) {
        ssh->deferred_size = ssh->deferred_len + len + 128;
-       ssh->deferred_send_data = srealloc(ssh->deferred_send_data,
-                                          ssh->deferred_size);
+       ssh->deferred_send_data = sresize(ssh->deferred_send_data,
+                                         ssh->deferred_size,
+                                         unsigned char);
     }
     memcpy(ssh->deferred_send_data + ssh->deferred_len, ssh->pktout.data, len);
     ssh->deferred_len += len;
@@ -1546,7 +1602,8 @@ static void ssh2_pkt_defer(Ssh ssh)
 static void ssh_pkt_defersend(Ssh ssh)
 {
     int backlog;
-    backlog = sk_write(ssh->s, ssh->deferred_send_data, ssh->deferred_len);
+    backlog = sk_write(ssh->s, (char *)ssh->deferred_send_data,
+                      ssh->deferred_len);
     ssh->deferred_len = ssh->deferred_size = 0;
     sfree(ssh->deferred_send_data);
     ssh->deferred_send_data = NULL;
@@ -1600,15 +1657,19 @@ static int ssh2_pkt_getbool(Ssh ssh)
 }
 static void ssh2_pkt_getstring(Ssh ssh, char **p, int *length)
 {
+    int len;
     *p = NULL;
     *length = 0;
     if (ssh->pktin.length - ssh->pktin.savedpos < 4)
        return;
-    *length = GET_32BIT(ssh->pktin.data + ssh->pktin.savedpos);
+    len = GET_32BIT(ssh->pktin.data + ssh->pktin.savedpos);
+    if (len < 0)
+       return;
+    *length = len;
     ssh->pktin.savedpos += 4;
     if (ssh->pktin.length - ssh->pktin.savedpos < *length)
        return;
-    *p = ssh->pktin.data + ssh->pktin.savedpos;
+    *p = (char *)(ssh->pktin.data + ssh->pktin.savedpos);
     ssh->pktin.savedpos += *length;
 }
 static Bignum ssh2_pkt_getmp(Ssh ssh)
@@ -1624,7 +1685,7 @@ static Bignum ssh2_pkt_getmp(Ssh ssh)
        bombout(("internal error: Can't handle negative mpints"));
        return NULL;
     }
-    b = bignum_from_bytes(p, length);
+    b = bignum_from_bytes((unsigned char *)p, length);
     return b;
 }
 
@@ -1674,18 +1735,18 @@ static void ssh2_add_sigblob(Ssh ssh, void *pkblob_v, int pkblob_len,
        if (len != siglen) {
            unsigned char newlen[4];
            ssh2_pkt_addstring_start(ssh);
-           ssh2_pkt_addstring_data(ssh, sigblob, pos);
+           ssh2_pkt_addstring_data(ssh, (char *)sigblob, pos);
            /* dmemdump(sigblob, pos); */
            pos += 4;                  /* point to start of actual sig */
            PUT_32BIT(newlen, len);
-           ssh2_pkt_addstring_data(ssh, newlen, 4);
+           ssh2_pkt_addstring_data(ssh, (char *)newlen, 4);
            /* dmemdump(newlen, 4); */
            newlen[0] = 0;
            while (len-- > siglen) {
-               ssh2_pkt_addstring_data(ssh, newlen, 1);
+               ssh2_pkt_addstring_data(ssh, (char *)newlen, 1);
                /* dmemdump(newlen, 1); */
            }
-           ssh2_pkt_addstring_data(ssh, sigblob+pos, siglen);
+           ssh2_pkt_addstring_data(ssh, (char *)(sigblob+pos), siglen);
            /* dmemdump(sigblob+pos, siglen); */
            return;
        }
@@ -1694,7 +1755,7 @@ static void ssh2_add_sigblob(Ssh ssh, void *pkblob_v, int pkblob_len,
     }
 
     ssh2_pkt_addstring_start(ssh);
-    ssh2_pkt_addstring_data(ssh, sigblob, sigblob_len);
+    ssh2_pkt_addstring_data(ssh, (char *)sigblob, sigblob_len);
 }
 
 /*
@@ -1712,8 +1773,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 
     ssh->remote_bugs = 0;
 
-    if (cfg.sshbug_ignore1 == BUG_ON ||
-       (cfg.sshbug_ignore1 == BUG_AUTO &&
+    if (ssh->cfg.sshbug_ignore1 == FORCE_ON ||
+       (ssh->cfg.sshbug_ignore1 == AUTO &&
         (!strcmp(imp, "1.2.18") || !strcmp(imp, "1.2.19") ||
          !strcmp(imp, "1.2.20") || !strcmp(imp, "1.2.21") ||
          !strcmp(imp, "1.2.22") || !strcmp(imp, "Cisco-1.25")))) {
@@ -1726,8 +1787,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH1 ignore bug");
     }
 
-    if (cfg.sshbug_plainpw1 == BUG_ON ||
-       (cfg.sshbug_plainpw1 == BUG_AUTO &&
+    if (ssh->cfg.sshbug_plainpw1 == FORCE_ON ||
+       (ssh->cfg.sshbug_plainpw1 == AUTO &&
         (!strcmp(imp, "Cisco-1.25")))) {
        /*
         * These versions need a plain password sent; they can't
@@ -1738,8 +1799,8 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version needs a plain SSH1 password");
     }
 
-    if (cfg.sshbug_rsa1 == BUG_ON ||
-       (cfg.sshbug_rsa1 == BUG_AUTO &&
+    if (ssh->cfg.sshbug_rsa1 == FORCE_ON ||
+       (ssh->cfg.sshbug_rsa1 == AUTO &&
         (!strcmp(imp, "Cisco-1.25")))) {
        /*
         * These versions apparently have no clue whatever about
@@ -1750,11 +1811,11 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version can't handle RSA authentication");
     }
 
-    if (cfg.sshbug_hmac2 == BUG_ON ||
-       (cfg.sshbug_hmac2 == BUG_AUTO &&
-        (!strncmp(imp, "2.1.0", 5) || !strncmp(imp, "2.0.", 4) ||
-         !strncmp(imp, "2.2.0", 5) || !strncmp(imp, "2.3.0", 5) ||
-         !strncmp(imp, "2.1 ", 4)))) {
+    if (ssh->cfg.sshbug_hmac2 == FORCE_ON ||
+       (ssh->cfg.sshbug_hmac2 == AUTO &&
+        (wc_match("2.1.0*", imp) || wc_match("2.0.*", imp) ||
+         wc_match("2.2.0*", imp) || wc_match("2.3.0*", imp) ||
+         wc_match("2.1 *", imp)))) {
        /*
         * These versions have the HMAC bug.
         */
@@ -1762,9 +1823,9 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH2 HMAC bug");
     }
 
-    if (cfg.sshbug_derivekey2 == BUG_ON ||
-       (cfg.sshbug_derivekey2 == BUG_AUTO &&
-        (!strncmp(imp, "2.0.", 4)))) {
+    if (ssh->cfg.sshbug_derivekey2 == FORCE_ON ||
+       (ssh->cfg.sshbug_derivekey2 == AUTO &&
+        (wc_match("2.0.0*", imp) || wc_match("2.0.10*", imp) ))) {
        /*
         * These versions have the key-derivation bug (failing to
         * include the literal shared secret in the hashes that
@@ -1774,10 +1835,10 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH2 key-derivation bug");
     }
 
-    if (cfg.sshbug_rsapad2 == BUG_ON ||
-       (cfg.sshbug_rsapad2 == BUG_AUTO &&
-        ((!strncmp(imp, "OpenSSH_2.", 10) && imp[10]>='5' && imp[10]<='9') ||
-         (!strncmp(imp, "OpenSSH_3.", 10) && imp[10]>='0' && imp[10]<='2')))){
+    if (ssh->cfg.sshbug_rsapad2 == FORCE_ON ||
+       (ssh->cfg.sshbug_rsapad2 == AUTO &&
+        (wc_match("OpenSSH_2.[5-9]*", imp) ||
+         wc_match("OpenSSH_3.[0-2]*", imp)))) {
        /*
         * These versions have the SSH2 RSA padding bug.
         */
@@ -1785,9 +1846,20 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        logevent("We believe remote version has SSH2 RSA padding bug");
     }
 
-    if (cfg.sshbug_dhgex2 == BUG_ON) {
+    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
+        * public-key authentication.
+        */
+       ssh->remote_bugs |= BUG_SSH2_PK_SESSIONID;
+       logevent("We believe remote version has SSH2 public-key-session-ID bug");
+    }
+
+    if (ssh->cfg.sshbug_dhgex2 == FORCE_ON) {
        /*
-        * These versions have the SSH2 DH GEX bug.
+        * User specified the SSH2 DH GEX bug.
         */
        ssh->remote_bugs |= BUG_SSH2_DH_GEX;
        logevent("We believe remote version has SSH2 DH group exchange bug");
@@ -1828,7 +1900,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     }
 
     s->vstrsize = 16;
-    s->vstring = smalloc(s->vstrsize);
+    s->vstring = snewn(s->vstrsize, char);
     strcpy(s->vstring, "SSH-");
     s->vslen = 4;
     s->i = 0;
@@ -1836,7 +1908,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
        crReturn(1);                   /* get another char */
        if (s->vslen >= s->vstrsize - 1) {
            s->vstrsize += 16;
-           s->vstring = srealloc(s->vstring, s->vstrsize);
+           s->vstring = sresize(s->vstring, s->vstrsize, char);
        }
        s->vstring[s->vslen++] = c;
        if (s->i >= 0) {
@@ -1845,7 +1917,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
                s->i = -1;
            } else if (s->i < sizeof(s->version) - 1)
                s->version[s->i++] = c;
-       } else if (c == '\n')
+       } else if (c == '\012')
            break;
     }
 
@@ -1856,7 +1928,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     s->vstring[strcspn(s->vstring, "\r\n")] = '\0';/* remove EOL chars */
     {
        char *vlog;
-       vlog = smalloc(20 + s->vslen);
+       vlog = snewn(20 + s->vslen, char);
        sprintf(vlog, "Server version: %s", s->vstring);
        logevent(vlog);
        sfree(vlog);
@@ -1872,16 +1944,16 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     /* Anything greater or equal to "1.99" means protocol 2 is supported. */
     s->proto2 = ssh_versioncmp(s->version, "1.99") >= 0;
 
-    if (cfg.sshprot == 0 && !s->proto1) {
+    if (ssh->cfg.sshprot == 0 && !s->proto1) {
        bombout(("SSH protocol version 1 required by user but not provided by server"));
-       crReturn(0);
+       crStop(0);
     }
-    if (cfg.sshprot == 3 && !s->proto2) {
+    if (ssh->cfg.sshprot == 3 && !s->proto2) {
        bombout(("SSH protocol version 2 required by user but not provided by server"));
-       crReturn(0);
+       crStop(0);
     }
 
-    if (s->proto2 && (cfg.sshprot >= 2 || !s->proto1)) {
+    if (s->proto2 && (ssh->cfg.sshprot >= 2 || !s->proto1)) {
        /*
         * Use v2 protocol.
         */
@@ -1895,7 +1967,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
        sha_string(&ssh->exhashbase, s->vstring, strcspn(s->vstring, "\r\n"));
        sprintf(vlog, "We claim version: %s", verstring);
        logevent(vlog);
-       strcat(verstring, "\n");
+       strcat(verstring, "\012");
        logevent("Using SSH protocol version 2");
        sk_write(ssh->s, verstring, strlen(verstring));
        ssh->protocol = ssh2_protocol;
@@ -1911,7 +1983,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
                sshver);
        sprintf(vlog, "We claim version: %s", verstring);
        logevent(vlog);
-       strcat(verstring, "\n");
+       strcat(verstring, "\012");
 
        logevent("Using SSH protocol version 1");
        sk_write(ssh->s, verstring, strlen(verstring));
@@ -1919,6 +1991,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
        ssh->version = 1;
        ssh->s_rdpkt = ssh1_rdpkt;
     }
+    update_specials_menu(ssh->frontend);
     ssh->state = SSH_STATE_BEFORE_SIZE;
 
     sfree(s->vstring);
@@ -1972,19 +2045,47 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
     crFinishV;
 }
 
-static int ssh_closing(Plug plug, char *error_msg, int error_code,
-                      int calling_back)
+static void ssh_do_close(Ssh ssh)
 {
-    Ssh ssh = (Ssh) plug;
+    int i;
+    struct ssh_channel *c;
+
     ssh->state = SSH_STATE_CLOSED;
     if (ssh->s) {
         sk_close(ssh->s);
         ssh->s = NULL;
     }
+    /*
+     * Now we must shut down any port and X forwardings going
+     * through this connection.
+     */
+    if (ssh->channels) {
+       for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
+           switch (c->type) {
+             case CHAN_X11:
+               x11_close(c->u.x11.s);
+               break;
+             case CHAN_SOCKDATA:
+               pfd_close(c->u.pfd.s);
+               break;
+           }
+           del234(ssh->channels, c);
+           if (ssh->version == 2)
+               bufchain_clear(&c->v.v2.outbuffer);
+           sfree(c);
+       }
+    }
+}
+
+static int ssh_closing(Plug plug, char *error_msg, int error_code,
+                      int calling_back)
+{
+    Ssh ssh = (Ssh) plug;
+    ssh_do_close(ssh);
     if (error_msg) {
        /* A socket error has occurred. */
        logevent(error_msg);
-       connection_fatal(error_msg);
+       connection_fatal(ssh->frontend, "%s", error_msg);
     } else {
        /* Otherwise, the remote side closed the connection normally. */
     }
@@ -1994,12 +2095,9 @@ static int ssh_closing(Plug plug, char *error_msg, int error_code,
 static int ssh_receive(Plug plug, int urgent, char *data, int len)
 {
     Ssh ssh = (Ssh) plug;
-    ssh_gotdata(ssh, data, len);
+    ssh_gotdata(ssh, (unsigned char *)data, len);
     if (ssh->state == SSH_STATE_CLOSED) {
-       if (ssh->s) {
-           sk_close(ssh->s);
-           ssh->s = NULL;
-       }
+       ssh_do_close(ssh);
        return 0;
     }
     return 1;
@@ -2035,7 +2133,7 @@ static char *connect_to_host(Ssh ssh, char *host, int port,
     SockAddr addr;
     char *err;
 
-    ssh->savedhost = smalloc(1 + strlen(host));
+    ssh->savedhost = snewn(1 + strlen(host), char);
     if (!ssh->savedhost)
        fatalbox("Out of memory");
     strcpy(ssh->savedhost, host);
@@ -2047,27 +2145,23 @@ static char *connect_to_host(Ssh ssh, char *host, int port,
     /*
      * Try to find host.
      */
-    {
-       char buf[200];
-       sprintf(buf, "Looking up host \"%.170s\"", host);
-       logevent(buf);
-    }
-    addr = sk_namelookup(host, realhost);
-    if ((err = sk_addr_error(addr)))
+    logeventf(ssh, "Looking up host \"%s\"", host);
+    addr = name_lookup(host, port, realhost, &ssh->cfg);
+    if ((err = sk_addr_error(addr)) != NULL)
        return err;
 
     /*
      * Open socket.
      */
     {
-       char buf[200], addrbuf[100];
+       char addrbuf[100];
        sk_getaddr(addr, addrbuf, 100);
-       sprintf(buf, "Connecting to %.100s port %d", addrbuf, port);
-       logevent(buf);
+       logeventf(ssh, "Connecting to %s port %d", addrbuf, port);
     }
     ssh->fn = &fn_table;
-    ssh->s = new_connection(addr, *realhost, port, 0, 1, nodelay, (Plug) ssh);
-    if ((err = sk_socket_error(ssh->s))) {
+    ssh->s = new_connection(addr, *realhost, port,
+                           0, 1, nodelay, (Plug) ssh, &ssh->cfg);
+    if ((err = sk_socket_error(ssh->s)) != NULL) {
        ssh->s = NULL;
        return err;
     }
@@ -2119,7 +2213,7 @@ static void ssh_throttle_all(Ssh ssh, int enable, int bufsize)
            /* Agent channels require no buffer management. */
            break;
          case CHAN_SOCKDATA:
-           pfd_override_throttle(c->u.x11.s, enable);
+           pfd_override_throttle(c->u.pfd.s, enable);
            break;
        }
     }
@@ -2131,7 +2225,7 @@ static void ssh_throttle_all(Ssh ssh, int enable, int bufsize)
  */
 
 /* Set up a username or password input loop on a given buffer. */
-void setup_userpass_input(Ssh ssh, char *buffer, int buflen, int echo)
+static void setup_userpass_input(Ssh ssh, char *buffer, int buflen, int echo)
 {
     ssh->userpass_input_buffer = buffer;
     ssh->userpass_input_buflen = buflen;
@@ -2145,7 +2239,7 @@ void setup_userpass_input(Ssh ssh, char *buffer, int buflen, int echo)
  * buffer), <0 for failure (user hit ^C/^D, bomb out and exit), 0
  * for inconclusive (keep waiting for more input please).
  */
-int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
+static int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
 {
     char c;
 
@@ -2178,7 +2272,13 @@ int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
            return -1;
            break;
          default:
-           if (((c >= ' ' && c <= '~') ||
+           /*
+            * This simplistic check for printability is disabled
+            * when we're doing password input, because some people
+            * have control characters in their passwords.o
+            */
+           if ((!ssh->userpass_input_echo ||
+                (c >= ' ' && c <= '~') ||
                 ((unsigned char) c >= 160))
                && ssh->userpass_input_bufpos < ssh->userpass_input_buflen-1) {
                ssh->userpass_input_buffer[ssh->userpass_input_bufpos++] = c;
@@ -2191,6 +2291,44 @@ int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
     return 0;
 }
 
+void ssh_agent_callback(void *sshv, void *reply, int replylen)
+{
+    Ssh ssh = (Ssh) sshv;
+
+    ssh->agent_response = reply;
+    ssh->agent_response_len = replylen;
+
+    if (ssh->version == 1)
+       do_ssh1_login(ssh, NULL, -1, 0);
+    else
+       do_ssh2_authconn(ssh, NULL, -1, 0);
+}
+
+void ssh_agentf_callback(void *cv, void *reply, int replylen)
+{
+    struct ssh_channel *c = (struct ssh_channel *)cv;
+    Ssh ssh = c->ssh;
+    void *sentreply = reply;
+
+    if (!sentreply) {
+       /* Fake SSH_AGENT_FAILURE. */
+       sentreply = "\0\0\0\1\5";
+       replylen = 5;
+    }
+    if (ssh->version == 2) {
+       ssh2_add_channel_data(c, sentreply, replylen);
+       ssh2_try_send(c);
+    } else {
+       send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
+                   PKT_INT, c->remoteid,
+                   PKT_INT, replylen,
+                   PKT_DATA, sentreply, replylen,
+                   PKT_END);
+    }
+    if (reply)
+       sfree(reply);
+}
+
 /*
  * Handle the key exchange and user authentication phases.
  */
@@ -2234,7 +2372,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     if (ssh->pktin.type != SSH1_SMSG_PUBLIC_KEY) {
        bombout(("Public key packet not received"));
-       crReturn(0);
+       crStop(0);
     }
 
     logevent("Received public keys");
@@ -2276,7 +2414,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     s->len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
 
-    s->rsabuf = smalloc(s->len);
+    s->rsabuf = snewn(s->len, unsigned char);
     if (!s->rsabuf)
        fatalbox("Out of memory");
 
@@ -2289,12 +2427,13 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
         */
        int len = rsastr_len(&hostkey);
        char fingerprint[100];
-       char *keystr = smalloc(len);
+       char *keystr = snewn(len, char);
        if (!keystr)
            fatalbox("Out of memory");
        rsastr_fmt(keystr, &hostkey);
        rsa_fingerprint(fingerprint, sizeof(fingerprint), &hostkey);
-       verify_ssh_host_key(ssh->savedhost, ssh->savedport, "rsa", keystr,
+       verify_ssh_host_key(ssh->frontend,
+                           ssh->savedhost, ssh->savedport, "rsa", keystr,
                            fingerprint);
        sfree(keystr);
     }
@@ -2320,7 +2459,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        char *cipher_string = NULL;
        int i;
        for (i = 0; !cipher_chosen && i < CIPHER_MAX; i++) {
-           int next_cipher = cfg.ssh_cipherlist[i];
+           int next_cipher = ssh->cfg.ssh_cipherlist[i];
            if (next_cipher == CIPHER_WARN) {
                /* If/when we choose a cipher, warn about it */
                warn = 1;
@@ -2347,12 +2486,12 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            else
                /* shouldn't happen */
                bombout(("No supported ciphers found"));
-           crReturn(0);
+           crStop(0);
        }
 
        /* Warn about chosen cipher if necessary. */
        if (warn)
-           askcipher(cipher_string, 0);
+           askcipher(ssh->frontend, cipher_string, 0);
     }
 
     switch (s->cipher_type) {
@@ -2383,11 +2522,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                   &ssh_3des);
     ssh->v1_cipher_ctx = ssh->cipher->make_context();
     ssh->cipher->sesskey(ssh->v1_cipher_ctx, ssh->session_key);
-    {
-       char buf[256];
-       sprintf(buf, "Initialised %.200s encryption", ssh->cipher->text_name);
-       logevent(buf);
-    }
+    logeventf(ssh, "Initialised %s encryption", ssh->cipher->text_name);
 
     ssh->crcda_ctx = crcda_make_context();
     logevent("Installing CRC compensation attack detector");
@@ -2396,14 +2531,14 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
        bombout(("Encryption not successfully enabled"));
-       crReturn(0);
+       crStop(0);
     }
 
     logevent("Successfully started encryption");
 
     fflush(stdout);
     {
-       if ((flags & FLAG_INTERACTIVE) && !*cfg.username) {
+       if ((flags & FLAG_INTERACTIVE) && !*ssh->cfg.username) {
            if (ssh_get_line && !ssh_getline_pw_only) {
                if (!ssh_get_line("login as: ",
                                  s->username, sizeof(s->username), FALSE)) {
@@ -2412,8 +2547,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                     * Terminate.
                     */
                    logevent("No username provided. Abandoning session.");
-                   ssh->state = SSH_STATE_CLOSED;
-                   crReturn(1);
+                    ssh_closing((Plug)ssh, NULL, 0, 0);
+                   crStop(1);
                }
            } else {
                int ret;               /* need not be kept over crReturn */
@@ -2430,7 +2565,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                c_write_str(ssh, "\r\n");
            }
        } else {
-           strncpy(s->username, cfg.username, sizeof(s->username));
+           strncpy(s->username, ssh->cfg.username, sizeof(s->username));
            s->username[sizeof(s->username)-1] = '\0';
        }
 
@@ -2456,9 +2591,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        s->tried_publickey = s->tried_agent = 0;
     }
     s->tis_auth_refused = s->ccard_auth_refused = 0;
-    /* Load the public half of cfg.keyfile so we notice if it's in Pageant */
-    if (*cfg.keyfile) {
-       if (!rsakey_pubblob(cfg.keyfile,
+    /* Load the public half of ssh->cfg.keyfile so we notice if it's in Pageant */
+    if (!filename_is_null(ssh->cfg.keyfile)) {
+       if (!rsakey_pubblob(&ssh->cfg.keyfile,
                            &s->publickey_blob, &s->publickey_bloblen))
            s->publickey_blob = NULL;
     } else
@@ -2480,7 +2615,19 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            /* Request the keys held by the agent. */
            PUT_32BIT(s->request, 1);
            s->request[4] = SSH1_AGENTC_REQUEST_RSA_IDENTITIES;
-           agent_query(s->request, 5, &r, &s->responselen);
+           if (!agent_query(s->request, 5, &r, &s->responselen,
+                            ssh_agent_callback, ssh)) {
+               do {
+                   crReturn(0);
+                   if (ispkt) {
+                       bombout(("Unexpected data from server while waiting"
+                                " for agent response"));
+                       crStop(0);
+                   }
+               } while (ispkt || inlen > 0);
+               r = ssh->agent_response;
+               s->responselen = ssh->agent_response_len;
+           }
            s->response = (unsigned char *) r;
            if (s->response && s->responselen >= 5 &&
                s->response[4] == SSH1_AGENT_RSA_IDENTITIES_ANSWER) {
@@ -2509,7 +2656,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    s->p += ssh1_read_bignum(s->p, &s->key.modulus);
                    s->commentlen = GET_32BIT(s->p);
                    s->p += 4;
-                   s->commentp = s->p;
+                   s->commentp = (char *)s->p;
                    s->p += s->commentlen;
                    send_packet(ssh, SSH1_CMSG_AUTH_RSA,
                                PKT_BIGNUM, s->key.modulus, PKT_END);
@@ -2530,7 +2677,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        len += ssh1_bignum_length(s->challenge);
                        len += 16;     /* session id */
                        len += 4;      /* response format */
-                       agentreq = smalloc(4 + len);
+                       agentreq = snewn(4 + len, char);
                        PUT_32BIT(agentreq, len);
                        q = agentreq + 4;
                        *q++ = SSH1_AGENTC_RSA_CHALLENGE;
@@ -2542,9 +2689,23 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        memcpy(q, s->session_id, 16);
                        q += 16;
                        PUT_32BIT(q, 1);        /* response format */
-                       agent_query(agentreq, len + 4, &vret, &retlen);
+                       if (!agent_query(agentreq, len + 4, &vret, &retlen,
+                                        ssh_agent_callback, ssh)) {
+                           sfree(agentreq);
+                           do {
+                               crReturn(0);
+                               if (ispkt) {
+                                   bombout(("Unexpected data from server"
+                                            " while waiting for agent"
+                                            " response"));
+                                   crStop(0);
+                               }
+                           } while (ispkt || inlen > 0);
+                           vret = ssh->agent_response;
+                           retlen = ssh->agent_response_len;
+                       } else
+                           sfree(agentreq);
                        ret = vret;
-                       sfree(agentreq);
                        if (ret) {
                            if (ret[4] == SSH1_AGENT_RSA_RESPONSE) {
                                logevent("Sending Pageant's response");
@@ -2586,10 +2747,10 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            if (s->authed)
                break;
        }
-       if (*cfg.keyfile && !s->tried_publickey)
+       if (!filename_is_null(ssh->cfg.keyfile) && !s->tried_publickey)
            s->pwpkt_type = SSH1_CMSG_AUTH_RSA;
 
-       if (cfg.try_tis_auth &&
+       if (ssh->cfg.try_tis_auth &&
            (s->supported_auths_mask & (1 << SSH1_AUTH_TIS)) &&
            !s->tis_auth_refused) {
            s->pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE;
@@ -2616,7 +2777,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                s->prompt[(sizeof s->prompt) - 1] = '\0';
            }
        }
-       if (cfg.try_tis_auth &&
+       if (ssh->cfg.try_tis_auth &&
            (s->supported_auths_mask & (1 << SSH1_AUTH_CCARD)) &&
            !s->ccard_auth_refused) {
            s->pwpkt_type = SSH1_CMSG_AUTH_CCARD_RESPONSE;
@@ -2651,9 +2812,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            char msgbuf[256];
            if (flags & FLAG_VERBOSE)
                c_write_str(ssh, "Trying public key authentication.\r\n");
-           sprintf(msgbuf, "Trying public key \"%.200s\"", cfg.keyfile);
-           logevent(msgbuf);
-           type = key_type(cfg.keyfile);
+           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));
@@ -2663,7 +2824,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                s->tried_publickey = 1;
                continue;
            }
-           if (!rsakey_encrypted(cfg.keyfile, &comment)) {
+           if (!rsakey_encrypted(&ssh->cfg.keyfile, &comment)) {
                if (flags & FLAG_VERBOSE)
                    c_write_str(ssh, "No passphrase required.\r\n");
                goto tryauth;
@@ -2689,9 +2850,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                            PKT_STR, "No more passwords available to try",
                            PKT_END);
                logevent("Unable to authenticate");
-               connection_fatal("Unable to authenticate");
-               ssh->state = SSH_STATE_CLOSED;
-               crReturn(1);
+               connection_fatal(ssh->frontend, "Unable to authenticate");
+                ssh_closing((Plug)ssh, NULL, 0, 0);
+               crStop(1);
            }
        } else {
            /* Prompt may have come from server. We've munged it a bit, so
@@ -2719,10 +2880,10 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            s->tried_publickey = 1;
            
            {
-               int ret = loadrsakey(cfg.keyfile, &s->key, s->password);
+               int ret = loadrsakey(&ssh->cfg.keyfile, &s->key, s->password);
                if (ret == 0) {
                    c_write_str(ssh, "Couldn't load private key from ");
-                   c_write_str(ssh, cfg.keyfile);
+                   c_write_str(ssh, filename_to_str(&ssh->cfg.keyfile));
                    c_write_str(ssh, ".\r\n");
                    continue;          /* go and try password */
                }
@@ -2746,7 +2907,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            }
            if (ssh->pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
                bombout(("Bizarre response to offer of public key"));
-               crReturn(0);
+               crStop(0);
            }
 
            {
@@ -2782,7 +2943,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                continue;              /* go and try password */
            } else if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
                bombout(("Bizarre response to RSA authentication response"));
-               crReturn(0);
+               crStop(0);
            }
 
            break;                     /* we're through! */
@@ -2845,7 +3006,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
                    assert(pwlen >= bottom && pwlen <= top);
 
-                   randomstr = smalloc(top + 1);
+                   randomstr = snewn(top + 1, char);
 
                    for (i = bottom; i <= top; i++) {
                        if (i == pwlen)
@@ -2915,7 +3076,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            logevent("Authentication refused");
        } else if (ssh->pktin.type != SSH1_SMSG_SUCCESS) {
            bombout(("Strange packet received, type %d", ssh->pktin.type));
-           crReturn(0);
+           crStop(0);
        }
     }
 
@@ -2928,6 +3089,11 @@ void sshfwd_close(struct ssh_channel *c)
 {
     Ssh ssh = c->ssh;
 
+    if (ssh->state != SSH_STATE_SESSION) {
+       assert(ssh->state == SSH_STATE_CLOSED);
+       return;
+    }
+
     if (c && !c->closes) {
        /*
         * If the channel's remoteid is -1, we have sent
@@ -2962,6 +3128,11 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
 {
     Ssh ssh = c->ssh;
 
+    if (ssh->state != SSH_STATE_SESSION) {
+       assert(ssh->state == SSH_STATE_CLOSED);
+       return 0;
+    }
+
     if (ssh->version == 1) {
        send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
                    PKT_INT, c->remoteid,
@@ -2984,6 +3155,11 @@ void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
 {
     Ssh ssh = c->ssh;
 
+    if (ssh->state != SSH_STATE_SESSION) {
+       assert(ssh->state == SSH_STATE_CLOSED);
+       return;
+    }
+
     if (ssh->version == 1) {
        if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) {
            c->v.v1.throttling = 0;
@@ -3006,7 +3182,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     if (ssh->state == SSH_STATE_CLOSED)
        crReturnV;
 
-    if (cfg.agentfwd && agent_exists()) {
+    if (ssh->cfg.agentfwd && agent_exists()) {
        logevent("Requesting agent forwarding");
        send_packet(ssh, SSH1_CMSG_AGENT_REQUEST_FORWARDING, PKT_END);
        do {
@@ -3015,7 +3191,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
            bombout(("Protocol confusion"));
-           crReturnV;
+           crStopV;
        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
            logevent("Agent forwarding refused");
        } else {
@@ -3024,14 +3200,17 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        }
     }
 
-    if (cfg.x11_forward) {
+    if (ssh->cfg.x11_forward) {
        char proto[20], data[64];
        logevent("Requesting X11 forwarding");
-       x11_invent_auth(proto, sizeof(proto), data, sizeof(data));
+       ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
+                                      data, sizeof(data), ssh->cfg.x11_auth);
+        x11_get_real_auth(ssh->x11auth, ssh->cfg.x11_display);
        if (ssh->v1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
            send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
                        PKT_STR, proto, PKT_STR, data,
-                       PKT_INT, 0, PKT_END);
+                       PKT_INT, x11_get_screen_number(ssh->cfg.x11_display),
+                       PKT_END);
        } else {
            send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
                        PKT_STR, proto, PKT_STR, data, PKT_END);
@@ -3042,7 +3221,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
            bombout(("Protocol confusion"));
-           crReturnV;
+           crStopV;
        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
            logevent("X11 forwarding refused");
        } else {
@@ -3055,91 +3234,118 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        char type;
        int n;
        int sport,dport,sserv,dserv;
-       char sports[256], dports[256], host[256];
-       char buf[1024];
-       struct servent *se;
+       char sports[256], dports[256], saddr[256], host[256];
 
        ssh->rportfwds = newtree234(ssh_rportcmp_ssh1);
         /* Add port forwardings. */
-       ssh->portfwd_strptr = cfg.portfwd;
+       ssh->portfwd_strptr = ssh->cfg.portfwd;
        while (*ssh->portfwd_strptr) {
            type = *ssh->portfwd_strptr++;
+           saddr[0] = '\0';
            n = 0;
-           while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != '\t')
-               sports[n++] = *ssh->portfwd_strptr++;
+           while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != '\t') {
+               if (*ssh->portfwd_strptr == ':') {
+                   /*
+                    * We've seen a colon in the middle of the
+                    * source port number. This means that
+                    * everything we've seen until now is the
+                    * source _address_, so we'll move it into
+                    * saddr and start sports from the beginning
+                    * again.
+                    */
+                   ssh->portfwd_strptr++;
+                   sports[n] = '\0';
+                   strcpy(saddr, sports);
+                   n = 0;
+               }
+               if (n < 255) sports[n++] = *ssh->portfwd_strptr++;
+           }
            sports[n] = 0;
-           if (*ssh->portfwd_strptr == '\t')
-               ssh->portfwd_strptr++;
-           n = 0;
-           while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':')
-               host[n++] = *ssh->portfwd_strptr++;
-           host[n] = 0;
-           if (*ssh->portfwd_strptr == ':')
+           if (type != 'D') {
+               if (*ssh->portfwd_strptr == '\t')
+                   ssh->portfwd_strptr++;
+               n = 0;
+               while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':') {
+                   if (n < 255) host[n++] = *ssh->portfwd_strptr++;
+               }
+               host[n] = 0;
+               if (*ssh->portfwd_strptr == ':')
+                   ssh->portfwd_strptr++;
+               n = 0;
+               while (*ssh->portfwd_strptr) {
+                   if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
+               }
+               dports[n] = 0;
                ssh->portfwd_strptr++;
-           n = 0;
-           while (*ssh->portfwd_strptr)
-               dports[n++] = *ssh->portfwd_strptr++;
-           dports[n] = 0;
-           ssh->portfwd_strptr++;
-           dport = atoi(dports);
-           dserv = 0;
-           if (dport == 0) {
-               dserv = 1;
-               se = getservbyname(dports, NULL);
-               if (se != NULL) {
-                   dport = ntohs(se->s_port);
-               } else {
-                   sprintf(buf,
-                           "Service lookup failed for destination port \"%s\"",
-                           dports);
-                   logevent(buf);
+               dport = atoi(dports);
+               dserv = 0;
+               if (dport == 0) {
+                   dserv = 1;
+                   dport = net_service_lookup(dports);
+                   if (!dport) {
+                       logeventf(ssh, "Service lookup failed for"
+                                 " destination port \"%s\"", dports);
+                   }
                }
+           } else {
+               while (*ssh->portfwd_strptr) ssh->portfwd_strptr++;
+               dport = dserv = -1;
            }
            sport = atoi(sports);
            sserv = 0;
            if (sport == 0) {
                sserv = 1;
-               se = getservbyname(sports, NULL);
-               if (se != NULL) {
-                   sport = ntohs(se->s_port);
-               } else {
-                   sprintf(buf,
-                           "Service lookup failed for source port \"%s\"",
-                           sports);
-                   logevent(buf);
+               sport = net_service_lookup(sports);
+               if (!sport) {
+                   logeventf(ssh, "Service lookup failed for source"
+                             " port \"%s\"", sports);
                }
            }
            if (sport && dport) {
                if (type == 'L') {
-                   pfd_addforward(host, dport, sport);
-                   sprintf(buf, "Local port %.*s%.*s%d%.*s forwarding to"
-                           " %s:%.*s%.*s%d%.*s",
-                           sserv ? strlen(sports) : 0, sports,
-                           sserv, "(", sport, sserv, ")",
-                           host,
-                           dserv ? strlen(dports) : 0, dports,
-                           dserv, "(", dport, dserv, ")");
-                   logevent(buf);
+                   pfd_addforward(host, dport, *saddr ? saddr : NULL,
+                                  sport, ssh, &ssh->cfg);
+                   logeventf(ssh, "Local port %.*s%.*s%.*s%.*s%d%.*s"
+                             " forwarding to %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, ")",
+                             host,
+                             (int)(dserv ? strlen(dports) : 0), dports,
+                             dserv, "(", dport, dserv, ")");
+               } else if (type == 'D') {
+                   pfd_addforward(NULL, -1, *saddr ? saddr : NULL,
+                                  sport, ssh, &ssh->cfg);
+                   logeventf(ssh, "Local port %.*s%.*s%.*s%.*s%d%.*s"
+                             " doing SOCKS dynamic forwarding",
+                             (int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
+                             (int)(*saddr?1:0), ":",
+                             (int)(sserv ? strlen(sports) : 0), sports,
+                             sserv, "(", sport, sserv, ")");
                } else {
                    struct ssh_rportfwd *pf;
-                   pf = smalloc(sizeof(*pf));
+                   pf = snew(struct ssh_rportfwd);
                    strcpy(pf->dhost, host);
                    pf->dport = dport;
+                   if (saddr) {
+                       logeventf(ssh,
+                                 "SSH1 cannot handle source address spec \"%s:%d\"; ignoring",
+                                 saddr, sport);
+                   }
                    if (add234(ssh->rportfwds, pf) != pf) {
-                       sprintf(buf, 
-                               "Duplicate remote port forwarding to %s:%d",
-                               host, dport);
-                       logevent(buf);
+                       logeventf(ssh, 
+                                 "Duplicate remote port forwarding to %s:%d",
+                                 host, dport);
                        sfree(pf);
                    } else {
-                       sprintf(buf, "Requesting remote port %.*s%.*s%d%.*s"
-                               " forward to %s:%.*s%.*s%d%.*s",
-                           sserv ? strlen(sports) : 0, sports,
-                           sserv, "(", sport, sserv, ")",
-                           host,
-                           dserv ? strlen(dports) : 0, dports,
-                           dserv, "(", dport, dserv, ")");
-                       logevent(buf);
+                       logeventf(ssh, "Requesting remote port %.*s%.*s%d%.*s"
+                                 " forward to %s:%.*s%.*s%d%.*s",
+                                 (int)(sserv ? strlen(sports) : 0), sports,
+                                 sserv, "(", sport, sserv, ")",
+                                 host,
+                                 (int)(dserv ? strlen(dports) : 0), dports,
+                                 dserv, "(", dport, dserv, ")");
                        send_packet(ssh, SSH1_CMSG_PORT_FORWARD_REQUEST,
                                    PKT_INT, sport,
                                    PKT_STR, host,
@@ -3151,7 +3357,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
                            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
                            bombout(("Protocol confusion"));
-                           crReturnV;
+                           crStopV;
                        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
                            c_write_str(ssh, "Server refused port"
                                        " forwarding\r\n");
@@ -3163,9 +3369,9 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        }
     }
 
-    if (!cfg.nopty) {
+    if (!ssh->cfg.nopty) {
        send_packet(ssh, SSH1_CMSG_REQUEST_PTY,
-                   PKT_STR, cfg.termtype,
+                   PKT_STR, ssh->cfg.termtype,
                    PKT_INT, ssh->term_height,
                    PKT_INT, ssh->term_width,
                    PKT_INT, 0, PKT_INT, 0, PKT_CHAR, 0, PKT_END);
@@ -3176,7 +3382,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
            bombout(("Protocol confusion"));
-           crReturnV;
+           crStopV;
        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
            c_write_str(ssh, "Server refused to allocate pty\r\n");
            ssh->editing = ssh->echoing = 1;
@@ -3186,7 +3392,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        ssh->editing = ssh->echoing = 1;
     }
 
-    if (cfg.compression) {
+    if (ssh->cfg.compression) {
        send_packet(ssh, SSH1_CMSG_REQUEST_COMPRESSION, PKT_INT, 6, PKT_END);
        do {
            crReturnV;
@@ -3194,7 +3400,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        if (ssh->pktin.type != SSH1_SMSG_SUCCESS
            && ssh->pktin.type != SSH1_SMSG_FAILURE) {
            bombout(("Protocol confusion"));
-           crReturnV;
+           crStopV;
        } else if (ssh->pktin.type == SSH1_SMSG_FAILURE) {
            c_write_str(ssh, "Server refused to compress\r\n");
        }
@@ -3214,10 +3420,10 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * exists, we fall straight back to that.
      */
     {
-       char *cmd = cfg.remote_cmd_ptr;
+       char *cmd = ssh->cfg.remote_cmd_ptr;
        
-       if (cfg.ssh_subsys && cfg.remote_cmd_ptr2) {
-           cmd = cfg.remote_cmd_ptr2;
+       if (ssh->cfg.ssh_subsys && ssh->cfg.remote_cmd_ptr2) {
+           cmd = ssh->cfg.remote_cmd_ptr2;
            ssh->fallback_cmd = TRUE;
        }
        if (*cmd)
@@ -3233,7 +3439,8 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     if (ssh->eof_needed)
        ssh_special(ssh, TS_EOF);
 
-    ldisc_send(NULL, 0, 0);           /* cause ldisc to notice changes */
+    if (ssh->ldisc)
+       ldisc_send(ssh->ldisc, NULL, 0, 0);/* cause ldisc to notice changes */
     ssh->send_ok = 1;
     ssh->channels = newtree234(ssh_channelcmp);
     while (1) {
@@ -3245,15 +3452,15 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                int bufsize =
                    from_backend(ssh->frontend,
                                 ssh->pktin.type == SSH1_SMSG_STDERR_DATA,
-                                ssh->pktin.body + 4, len);
+                                (char *)(ssh->pktin.body) + 4, len);
                if (!ssh->v1_stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) {
                    ssh->v1_stdout_throttling = 1;
                    ssh1_throttle(ssh, +1);
                }
            } else if (ssh->pktin.type == SSH1_MSG_DISCONNECT) {
-               ssh->state = SSH_STATE_CLOSED;
+                ssh_closing((Plug)ssh, NULL, 0, 0);
                logevent("Received disconnect request");
-               crReturnV;
+               crStopV;
            } else if (ssh->pktin.type == SSH1_SMSG_X11_OPEN) {
                /* Remote side is trying to open a channel to talk to our
                 * X-Server. Give them back a local channel number. */
@@ -3266,10 +3473,11 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                PKT_INT, GET_32BIT(ssh->pktin.body), PKT_END);
                    logevent("Rejected X11 connect request");
                } else {
-                   c = smalloc(sizeof(struct ssh_channel));
+                   c = snew(struct ssh_channel);
                    c->ssh = ssh;
 
-                   if (x11_init(&c->u.x11.s, cfg.x11_display, c) != NULL) {
+                   if (x11_init(&c->u.x11.s, ssh->cfg.x11_display, c,
+                                ssh->x11auth, NULL, -1, &ssh->cfg) != NULL) {
                        logevent("opening X11 forward connection failed");
                        sfree(c);
                        send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
@@ -3300,7 +3508,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
                                PKT_INT, GET_32BIT(ssh->pktin.body), PKT_END);
                } else {
-                   c = smalloc(sizeof(struct ssh_channel));
+                   c = snew(struct ssh_channel);
                    c->ssh = ssh;
                    c->remoteid = GET_32BIT(ssh->pktin.body);
                    c->localid = alloc_channel_id(ssh);
@@ -3321,11 +3529,12 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                int hostsize, port;
                char host[256], buf[1024];
                char *p, *h, *e;
-               c = smalloc(sizeof(struct ssh_channel));
+               c = snew(struct ssh_channel);
                c->ssh = ssh;
 
                hostsize = GET_32BIT(ssh->pktin.body+4);
-               for(h = host, p = ssh->pktin.body+8; hostsize != 0; hostsize--) {
+               for (h = host, p = (char *)(ssh->pktin.body+8);
+                    hostsize != 0; hostsize--) {
                    if (h+1 < host+sizeof(host))
                        *h++ = *p;
                    p++;
@@ -3346,7 +3555,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    sprintf(buf, "Received remote port open request for %s:%d",
                            host, port);
                    logevent(buf);
-                   e = pfd_newconnect(&c->u.pfd.s, host, port, c);
+                   e = pfd_newconnect(&c->u.pfd.s, host, port, c, &ssh->cfg);
                    if (e != NULL) {
                        char buf[256];
                        sprintf(buf, "Port open failed: %s", e);
@@ -3395,7 +3604,6 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
            } else if (ssh->pktin.type == SSH1_MSG_CHANNEL_OPEN_FAILURE) {
                unsigned int remoteid = GET_32BIT(ssh->pktin.body);
-               unsigned int localid = GET_32BIT(ssh->pktin.body+4);
                struct ssh_channel *c;
 
                c = find234(ssh->channels, &remoteid, ssh_channelfind);
@@ -3446,6 +3654,7 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                             ssh->pktin.type == SSH1_MSG_CHANNEL_CLOSE ? "" :
                             "_CONFIRMATION", c ? "half-open" : "nonexistent",
                             i));
+                   crStopV;
                }
            } else if (ssh->pktin.type == SSH1_MSG_CHANNEL_DATA) {
                /* Data sent down one of our channels. */
@@ -3455,13 +3664,13 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                struct ssh_channel *c;
                c = find234(ssh->channels, &i, ssh_channelfind);
                if (c) {
-                   int bufsize;
+                   int bufsize = 0;
                    switch (c->type) {
                      case CHAN_X11:
-                       bufsize = x11_send(c->u.x11.s, p, len);
+                       bufsize = x11_send(c->u.x11.s, (char *)p, len);
                        break;
                      case CHAN_SOCKDATA:
-                       bufsize = pfd_send(c->u.pfd.s, p, len);
+                       bufsize = pfd_send(c->u.pfd.s, (char *)p, len);
                        break;
                      case CHAN_AGENT:
                        /* Data for an agent message. Buffer it. */
@@ -3477,7 +3686,8 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                            if (c->u.a.lensofar == 4) {
                                c->u.a.totallen =
                                    4 + GET_32BIT(c->u.a.msglen);
-                               c->u.a.message = smalloc(c->u.a.totallen);
+                               c->u.a.message = snewn(c->u.a.totallen,
+                                                      unsigned char);
                                memcpy(c->u.a.message, c->u.a.msglen, 4);
                            }
                            if (c->u.a.lensofar >= 4 && len > 0) {
@@ -3491,25 +3701,13 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                c->u.a.lensofar += l;
                            }
                            if (c->u.a.lensofar == c->u.a.totallen) {
-                               void *reply, *sentreply;
+                               void *reply;
                                int replylen;
-                               agent_query(c->u.a.message,
-                                           c->u.a.totallen, &reply,
-                                           &replylen);
-                               if (reply)
-                                   sentreply = reply;
-                               else {
-                                   /* Fake SSH_AGENT_FAILURE. */
-                                   sentreply = "\0\0\0\1\5";
-                                   replylen = 5;
-                               }
-                               send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
-                                           PKT_INT, c->remoteid,
-                                           PKT_INT, replylen,
-                                           PKT_DATA, sentreply, replylen,
-                                           PKT_END);
-                               if (reply)
-                                   sfree(reply);
+                               if (agent_query(c->u.a.message,
+                                               c->u.a.totallen,
+                                               &reply, &replylen,
+                                               ssh_agentf_callback, c))
+                                   ssh_agentf_callback(c, reply, replylen);
                                sfree(c->u.a.message);
                                c->u.a.lensofar = 0;
                            }
@@ -3541,11 +3739,11 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                  * encrypted packet, we close the session once
                  * we've sent EXIT_CONFIRMATION.
                  */
-                ssh->state = SSH_STATE_CLOSED;
-                crReturnV;
+                ssh_closing((Plug)ssh, NULL, 0, 0);
+                crStopV;
            } else {
                bombout(("Strange packet received: type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
        } else {
            while (inlen > 0) {
@@ -3566,7 +3764,10 @@ static void ssh1_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
  */
 static int in_commasep_string(char *needle, char *haystack, int haylen)
 {
-    int needlen = strlen(needle);
+    int needlen;
+    if (!needle || !haystack)         /* protect against null pointers */
+       return 0;
+    needlen = strlen(needle);
     while (1) {
        /*
         * Is it at the start of the string?
@@ -3592,8 +3793,9 @@ static int in_commasep_string(char *needle, char *haystack, int haylen)
 /*
  * SSH2 key creation method.
  */
-static void ssh2_mkkey(Ssh ssh, Bignum K, char *H, char *sessid, char chr,
-                      char *keyspace)
+static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
+                      unsigned char *sessid, char chr,
+                      unsigned char *keyspace)
 {
     SHA_State s;
     /* First 20 bytes. */
@@ -3657,12 +3859,12 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
         */
        s->n_preferred_ciphers = 0;
        for (i = 0; i < CIPHER_MAX; i++) {
-           switch (cfg.ssh_cipherlist[i]) {
+           switch (ssh->cfg.ssh_cipherlist[i]) {
              case CIPHER_BLOWFISH:
                s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_blowfish;
                break;
              case CIPHER_DES:
-               if (cfg.ssh2_des_cbc) {
+               if (ssh->cfg.ssh2_des_cbc) {
                    s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_des;
                }
                break;
@@ -3686,7 +3888,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Set up preferred compression.
      */
-    if (cfg.compression)
+    if (ssh->cfg.compression)
        s->preferred_comp = &ssh_zlib;
     else
        s->preferred_comp = &ssh_comp_none;
@@ -3801,7 +4003,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
     if (!ispkt)
        crWaitUntil(ispkt);
-    sha_string(&ssh->exhash, ssh->pktin.data + 5, ssh->pktin.length - 5);
+    if (ssh->pktin.length > 5)
+       sha_string(&ssh->exhash, ssh->pktin.data + 5, ssh->pktin.length - 5);
 
     /*
      * Now examine the other side's KEXINIT to see what we're up
@@ -3813,7 +4016,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
 
        if (ssh->pktin.type != SSH2_MSG_KEXINIT) {
            bombout(("expected key exchange packet from server"));
-           crReturn(0);
+           crStop(0);
        }
        ssh->kex = NULL;
        ssh->hostkey = NULL;
@@ -3857,13 +4060,14 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            }
            if (s->cscipher_tobe) {
                if (s->warn)
-                   askcipher(s->cscipher_tobe->name, 1);
+                   askcipher(ssh->frontend, s->cscipher_tobe->name, 1);
                break;
            }
        }
        if (!s->cscipher_tobe) {
-           bombout(("Couldn't agree a client-to-server cipher (available: %s)", str));
-           crReturn(0);
+           bombout(("Couldn't agree a client-to-server cipher (available: %s)",
+                    str ? str : "(null)"));
+           crStop(0);
        }
 
        ssh2_pkt_getstring(ssh, &str, &len);    /* server->client cipher */
@@ -3882,13 +4086,14 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            }
            if (s->sccipher_tobe) {
                if (s->warn)
-                   askcipher(s->sccipher_tobe->name, 2);
+                   askcipher(ssh->frontend, s->sccipher_tobe->name, 2);
                break;
            }
        }
        if (!s->sccipher_tobe) {
-           bombout(("Couldn't agree a server-to-client cipher (available: %s)", str));
-           crReturn(0);
+           bombout(("Couldn't agree a server-to-client cipher (available: %s)",
+                    str ? str : "(null)"));
+           crStop(0);
        }
 
        ssh2_pkt_getstring(ssh, &str, &len);    /* client->server mac */
@@ -3961,7 +4166,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        crWaitUntil(ispkt);
        if (ssh->pktin.type != SSH2_MSG_KEX_DH_GEX_GROUP) {
            bombout(("expected key exchange group packet from server"));
-           crReturn(0);
+           crStop(0);
        }
        s->p = ssh2_pkt_getmp(ssh);
        s->g = ssh2_pkt_getmp(ssh);
@@ -3987,7 +4192,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     crWaitUntil(ispkt);
     if (ssh->pktin.type != s->kex_reply_value) {
        bombout(("expected key exchange reply packet from server"));
-       crReturn(0);
+       crStop(0);
     }
     ssh2_pkt_getstring(ssh, &s->hostkeydata, &s->hostkeylen);
     s->f = ssh2_pkt_getmp(ssh);
@@ -4007,6 +4212,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     SHA_Final(&ssh->exhash, s->exchange_hash);
 
     dh_cleanup(ssh->kex_ctx);
+    ssh->kex_ctx = NULL;
 
 #if 0
     debug(("Exchange hash is:\n"));
@@ -4016,9 +4222,9 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
     if (!s->hkey ||
        !ssh->hostkey->verifysig(s->hkey, s->sigdata, s->siglen,
-                                s->exchange_hash, 20)) {
+                                (char *)s->exchange_hash, 20)) {
        bombout(("Server's host key did not match the signature supplied"));
-       crReturn(0);
+       crStop(0);
     }
 
     /*
@@ -4027,7 +4233,8 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      */
     s->keystr = ssh->hostkey->fmtkey(s->hkey);
     s->fingerprint = ssh->hostkey->fingerprint(s->hkey);
-    verify_ssh_host_key(ssh->savedhost, ssh->savedport, ssh->hostkey->keytype,
+    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 */
        logevent("Host key fingerprint is:");
@@ -4049,7 +4256,7 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     crWaitUntil(ispkt);
     if (ssh->pktin.type != SSH2_MSG_NEWKEYS) {
        bombout(("expected new-keys packet from server"));
-       crReturn(0);
+       crStop(0);
     }
 
     /*
@@ -4107,26 +4314,16 @@ static int do_ssh2_transport(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'F',keyspace);
        ssh->scmac->setkey(ssh->sc_mac_ctx, keyspace);
     }
-    {
-       char buf[256];
-       sprintf(buf, "Initialised %.200s client->server encryption",
-               ssh->cscipher->text_name);
-       logevent(buf);
-       sprintf(buf, "Initialised %.200s server->client encryption",
-               ssh->sccipher->text_name);
-       logevent(buf);
-       if (ssh->cscomp->text_name) {
-           sprintf(buf, "Initialised %.200s compression",
-                   ssh->cscomp->text_name);
-           logevent(buf);
-       }
-       if (ssh->sccomp->text_name) {
-           sprintf(buf, "Initialised %.200s decompression",
-                   ssh->sccomp->text_name);
-           logevent(buf);
-       }
-    }
-
+    logeventf(ssh, "Initialised %.200s client->server encryption",
+             ssh->cscipher->text_name);
+    logeventf(ssh, "Initialised %.200s server->client encryption",
+             ssh->sccipher->text_name);
+    if (ssh->cscomp->text_name)
+       logeventf(ssh, "Initialised %s compression",
+                 ssh->cscomp->text_name);
+    if (ssh->sccomp->text_name)
+       logeventf(ssh, "Initialised %s decompression",
+                 ssh->sccomp->text_name);
 
     /*
      * If this is the first key exchange phase, we must pass the
@@ -4274,7 +4471,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     crWaitUntilV(ispkt);
     if (ssh->pktin.type != SSH2_MSG_SERVICE_ACCEPT) {
        bombout(("Server refused user authentication protocol"));
-       crReturnV;
+       crStopV;
     }
 
     /*
@@ -4307,13 +4504,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        /*
         * Get a username.
         */
-       if (s->got_username && !cfg.change_username) {
+       if (s->got_username && !ssh->cfg.change_username) {
            /*
             * We got a username last time round this loop, and
             * with change_username turned off we don't try to get
             * it again.
             */
-       } else if ((flags & FLAG_INTERACTIVE) && !*cfg.username) {
+       } else if ((flags & FLAG_INTERACTIVE) && !*ssh->cfg.username) {
            if (ssh_get_line && !ssh_getline_pw_only) {
                if (!ssh_get_line("login as: ",
                                  s->username, sizeof(s->username), FALSE)) {
@@ -4322,8 +4519,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                     * Terminate.
                     */
                    logevent("No username provided. Abandoning session.");
-                   ssh->state = SSH_STATE_CLOSED;
-                   crReturnV;
+                    ssh_closing((Plug)ssh, NULL, 0, 0);
+                   crStopV;
                }
            } else {
                int ret;               /* need not be saved across crReturn */
@@ -4336,16 +4533,17 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                } while (ret == 0);
                if (ret < 0)
                    cleanup_exit(0);
+               c_write_str(ssh, "\r\n");
            }
-           c_write_str(ssh, "\r\n");
            s->username[strcspn(s->username, "\n\r")] = '\0';
        } else {
-           char stuff[200];
-           strncpy(s->username, cfg.username, sizeof(s->username));
+           char *stuff;
+           strncpy(s->username, ssh->cfg.username, sizeof(s->username));
            s->username[sizeof(s->username)-1] = '\0';
            if ((flags & FLAG_VERBOSE) || (flags & FLAG_INTERACTIVE)) {
-               sprintf(stuff, "Using username \"%s\".\r\n", s->username);
+               stuff = dupprintf("Using username \"%s\".\r\n", s->username);
                c_write_str(ssh, stuff);
+               sfree(stuff);
            }
        }
        s->got_username = TRUE;
@@ -4370,22 +4568,26 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        s->tried_agent = FALSE;
        s->tried_keyb_inter = FALSE;
        s->kbd_inter_running = FALSE;
-       /* Load the pub half of cfg.keyfile so we notice if it's in Pageant */
-       if (*cfg.keyfile) {
+       /* 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;
-           logeventf("Reading private key file \"%.150s\"", cfg.keyfile);
-           keytype = key_type(cfg.keyfile);
+           logeventf(ssh, "Reading private key file \"%.150s\"",
+                     filename_to_str(&ssh->cfg.keyfile));
+           keytype = key_type(&ssh->cfg.keyfile);
            if (keytype == SSH_KEYTYPE_SSH2) {
                s->publickey_blob =
-                   ssh2_userkey_loadpub(cfg.keyfile, NULL,
+                   ssh2_userkey_loadpub(&ssh->cfg.keyfile, NULL,
                                         &s->publickey_bloblen);
            } else {
-               char msgbuf[256];
-               logeventf("Unable to use this key file (%s)",
-                       key_type_to_str(keytype));
-               sprintf(msgbuf, "Unable to use key file \"%.150s\" (%s)\r\n",
-                       cfg.keyfile, key_type_to_str(keytype));
+               char *msgbuf;
+               logeventf(ssh, "Unable to use this key file (%s)",
+                         key_type_to_str(keytype));
+               msgbuf = dupprintf("Unable to use key file \"%.150s\""
+                                  " (%s)\r\n",
+                                  filename_to_str(&ssh->cfg.keyfile),
+                                  key_type_to_str(keytype));
                c_write_str(ssh, msgbuf);
+               sfree(msgbuf);
                s->publickey_blob = NULL;
            }
        } else
@@ -4435,7 +4637,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            } else if (ssh->pktin.type != SSH2_MSG_USERAUTH_FAILURE) {
                bombout(("Strange packet received during authentication: type %d",
                         ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
 
            s->gotit = FALSE;
@@ -4498,7 +4700,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    in_commasep_string("publickey", methods, methlen);
                s->can_passwd =
                    in_commasep_string("password", methods, methlen);
-               s->can_keyb_inter = cfg.try_ki_auth &&
+               s->can_keyb_inter = ssh->cfg.try_ki_auth &&
                    in_commasep_string("keyboard-interactive", methods, methlen);
            }
 
@@ -4531,7 +4733,19 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                /* Request the keys held by the agent. */
                PUT_32BIT(s->request, 1);
                s->request[4] = SSH2_AGENTC_REQUEST_IDENTITIES;
-               agent_query(s->request, 5, &r, &s->responselen);
+               if (!agent_query(s->request, 5, &r, &s->responselen,
+                                ssh_agent_callback, ssh)) {
+                   do {
+                       crReturnV;
+                       if (ispkt) {
+                           bombout(("Unexpected data from server while"
+                                    " waiting for agent response"));
+                           crStopV;
+                       }
+                   } while (ispkt || inlen > 0);
+                   r = ssh->agent_response;
+                   s->responselen = ssh->agent_response_len;
+               }
                s->response = (unsigned char *) r;
                if (s->response && s->responselen >= 5 &&
                    s->response[4] == SSH2_AGENT_IDENTITIES_ANSWER) {
@@ -4560,13 +4774,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                            logevent("This key matches configured key file");
                            s->tried_pubkey_config = 1;
                        }
-                       s->pkblob = s->p;
+                       s->pkblob = (char *)s->p;
                        s->p += s->pklen;
                        s->alglen = GET_32BIT(s->pkblob);
                        s->alg = s->pkblob + 4;
                        s->commentlen = GET_32BIT(s->p);
                        s->p += 4;
-                       s->commentp = s->p;
+                       s->commentp = (char *)s->p;
                        s->p += s->commentlen;
                        ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
                        ssh2_pkt_addstring(ssh, s->username);
@@ -4607,11 +4821,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        ssh2_pkt_addstring_data(ssh, s->pkblob, s->pklen);
 
                        s->siglen = ssh->pktout.length - 5 + 4 + 20;
+                        if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
+                            s->siglen -= 4;
                        s->len = 1;       /* message type */
                        s->len += 4 + s->pklen; /* key blob */
                        s->len += 4 + s->siglen;        /* data to sign */
                        s->len += 4;      /* flags */
-                       s->agentreq = smalloc(4 + s->len);
+                       s->agentreq = snewn(4 + s->len, char);
                        PUT_32BIT(s->agentreq, s->len);
                        s->q = s->agentreq + 4;
                        *s->q++ = SSH2_AGENTC_SIGN_REQUEST;
@@ -4622,8 +4838,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        PUT_32BIT(s->q, s->siglen);
                        s->q += 4;
                        /* Now the data to be signed... */
-                       PUT_32BIT(s->q, 20);
-                       s->q += 4;
+                        if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
+                            PUT_32BIT(s->q, 20);
+                            s->q += 4;
+                        }
                        memcpy(s->q, ssh->v2_session_id, 20);
                        s->q += 20;
                        memcpy(s->q, ssh->pktout.data + 5,
@@ -4631,7 +4849,21 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        s->q += ssh->pktout.length - 5;
                        /* And finally the (zero) flags word. */
                        PUT_32BIT(s->q, 0);
-                       agent_query(s->agentreq, s->len + 4, &vret, &s->retlen);
+                       if (!agent_query(s->agentreq, s->len + 4,
+                                        &vret, &s->retlen,
+                                        ssh_agent_callback, ssh)) {
+                           do {
+                               crReturnV;
+                               if (ispkt) {
+                                   bombout(("Unexpected data from server"
+                                            " while waiting for agent"
+                                            " response"));
+                                   crStopV;
+                               }
+                           } while (ispkt || inlen > 0);
+                           vret = ssh->agent_response;
+                           s->retlen = ssh->agent_response_len;
+                       }
                        s->ret = vret;
                        sfree(s->agentreq);
                        if (s->ret) {
@@ -4672,8 +4904,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                 * First, offer the public blob to see if the server is
                 * willing to accept it.
                 */
-               pub_blob = ssh2_userkey_loadpub(cfg.keyfile, &algorithm,
-                                               &pub_blob_len);
+               pub_blob =
+                   (unsigned char *)ssh2_userkey_loadpub(&ssh->cfg.keyfile,
+                                                         &algorithm,
+                                                         &pub_blob_len);
                if (pub_blob) {
                    ssh2_pkt_init(ssh, SSH2_MSG_USERAUTH_REQUEST);
                    ssh2_pkt_addstring(ssh, s->username);
@@ -4682,7 +4916,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    ssh2_pkt_addbool(ssh, FALSE);       /* no signature included */
                    ssh2_pkt_addstring(ssh, algorithm);
                    ssh2_pkt_addstring_start(ssh);
-                   ssh2_pkt_addstring_data(ssh, pub_blob, pub_blob_len);
+                   ssh2_pkt_addstring_data(ssh, (char *)pub_blob,
+                                           pub_blob_len);
                    ssh2_pkt_send(ssh);
                    logevent("Offered public key");     /* FIXME */
 
@@ -4698,7 +4933,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                     * Actually attempt a serious authentication using
                     * the key.
                     */
-                   if (ssh2_userkey_encrypted(cfg.keyfile, &comment)) {
+                   if (ssh2_userkey_encrypted(&ssh->cfg.keyfile, &comment)) {
                        sprintf(s->pwprompt,
                                "Passphrase for key \"%.100s\": ",
                                comment);
@@ -4822,9 +5057,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                        ssh2_pkt_addstring(ssh, "en");  /* language tag */
                        ssh2_pkt_send(ssh);
                        logevent("Unable to authenticate");
-                       connection_fatal("Unable to authenticate");
-                       ssh->state = SSH_STATE_CLOSED;
-                       crReturnV;
+                       connection_fatal(ssh->frontend,
+                                        "Unable to authenticate");
+                        ssh_closing((Plug)ssh, NULL, 0, 0);
+                       crStopV;
                    }
                } else {
                    int ret;           /* need not be saved across crReturn */
@@ -4849,7 +5085,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                 */
                struct ssh2_userkey *key;
 
-               key = ssh2_load_userkey(cfg.keyfile, s->password);
+               key = ssh2_load_userkey(&ssh->cfg.keyfile, s->password);
                if (key == SSH2_WRONG_PASSPHRASE || key == NULL) {
                    if (key == SSH2_WRONG_PASSPHRASE) {
                        c_write_str(ssh, "Wrong passphrase\r\n");
@@ -4868,6 +5104,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                } else {
                    unsigned char *pkblob, *sigblob, *sigdata;
                    int pkblob_len, sigblob_len, sigdata_len;
+                    int p;
 
                    /*
                     * We have loaded the private key and the server
@@ -4882,7 +5119,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    ssh2_pkt_addstring(ssh, key->alg->name);
                    pkblob = key->alg->public_blob(key->data, &pkblob_len);
                    ssh2_pkt_addstring_start(ssh);
-                   ssh2_pkt_addstring_data(ssh, pkblob, pkblob_len);
+                   ssh2_pkt_addstring_data(ssh, (char *)pkblob, pkblob_len);
 
                    /*
                     * The data to be signed is:
@@ -4893,12 +5130,20 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                     * outgoing packet.
                     */
                    sigdata_len = ssh->pktout.length - 5 + 4 + 20;
-                   sigdata = smalloc(sigdata_len);
-                   PUT_32BIT(sigdata, 20);
-                   memcpy(sigdata + 4, ssh->v2_session_id, 20);
-                   memcpy(sigdata + 24, ssh->pktout.data + 5,
+                    if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
+                        sigdata_len -= 4;
+                   sigdata = snewn(sigdata_len, unsigned char);
+                    p = 0;
+                    if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
+                        PUT_32BIT(sigdata+p, 20);
+                        p += 4;
+                    }
+                   memcpy(sigdata+p, ssh->v2_session_id, 20); p += 20;
+                   memcpy(sigdata+p, ssh->pktout.data + 5,
                           ssh->pktout.length - 5);
-                   sigblob = key->alg->sign(key->data, sigdata,
+                    p += ssh->pktout.length - 5;
+                    assert(p == sigdata_len);
+                   sigblob = key->alg->sign(key->data, (char *)sigdata,
                                             sigdata_len, &sigblob_len);
                    ssh2_add_sigblob(ssh, pkblob, pkblob_len,
                                     sigblob, sigblob_len);
@@ -4930,6 +5175,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                ssh2_pkt_addstring(ssh, "password");
                ssh2_pkt_addbool(ssh, FALSE);
                ssh2_pkt_addstring(ssh, s->password);
+               memset(s->password, 0, sizeof(s->password));
                ssh2_pkt_defer(ssh);
                /*
                 * We'll include a string that's an exact multiple of the
@@ -5002,8 +5248,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                   " methods available");
                ssh2_pkt_addstring(ssh, "en");  /* language tag */
                ssh2_pkt_send(ssh);
-               ssh->state = SSH_STATE_CLOSED;
-               crReturnV;
+                ssh_closing((Plug)ssh, NULL, 0, 0);
+               crStopV;
            }
        }
     } while (!s->we_are_in);
@@ -5018,7 +5264,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
      * So now create a channel with a session in it.
      */
     ssh->channels = newtree234(ssh_channelcmp);
-    ssh->mainchan = smalloc(sizeof(struct ssh_channel));
+    ssh->mainchan = snew(struct ssh_channel);
     ssh->mainchan->ssh = ssh;
     ssh->mainchan->localid = alloc_channel_id(ssh);
     ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_OPEN);
@@ -5031,12 +5277,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     crWaitUntilV(ispkt);
     if (ssh->pktin.type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
        bombout(("Server refused to open a session"));
-       crReturnV;
+       crStopV;
        /* FIXME: error data comes back in FAILURE packet */
     }
     if (ssh2_pkt_getuint32(ssh) != ssh->mainchan->localid) {
        bombout(("Server's channel confirmation cited wrong channel"));
-       crReturnV;
+       crStopV;
     }
     ssh->mainchan->remoteid = ssh2_pkt_getuint32(ssh);
     ssh->mainchan->type = CHAN_MAINSESSION;
@@ -5050,10 +5296,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Potentially enable X11 forwarding.
      */
-    if (cfg.x11_forward) {
+    if (ssh->cfg.x11_forward) {
        char proto[20], data[64];
        logevent("Requesting X11 forwarding");
-       x11_invent_auth(proto, sizeof(proto), data, sizeof(data));
+       ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
+                                      data, sizeof(data), ssh->cfg.x11_auth);
+        x11_get_real_auth(ssh->x11auth, ssh->cfg.x11_display);
        ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
        ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
        ssh2_pkt_addstring(ssh, "x11-req");
@@ -5061,7 +5309,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        ssh2_pkt_addbool(ssh, 0);              /* many connections */
        ssh2_pkt_addstring(ssh, proto);
        ssh2_pkt_addstring(ssh, data);
-       ssh2_pkt_adduint32(ssh, 0);            /* screen number */
+       ssh2_pkt_adduint32(ssh, x11_get_screen_number(ssh->cfg.x11_display));
        ssh2_pkt_send(ssh);
 
        do {
@@ -5080,7 +5328,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
                bombout(("Unexpected response to X11 forwarding request:"
                         " packet type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
            logevent("X11 forwarding refused");
        } else {
@@ -5096,96 +5344,123 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        char type;
        int n;
        int sport,dport,sserv,dserv;
-       char sports[256], dports[256], host[256];
-       char buf[1024];
-       struct servent *se;
+       char sports[256], dports[256], saddr[256], host[256];
 
        ssh->rportfwds = newtree234(ssh_rportcmp_ssh2);
         /* Add port forwardings. */
-       ssh->portfwd_strptr = cfg.portfwd;
+       ssh->portfwd_strptr = ssh->cfg.portfwd;
        while (*ssh->portfwd_strptr) {
            type = *ssh->portfwd_strptr++;
+           saddr[0] = '\0';
            n = 0;
-           while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != '\t')
-               sports[n++] = *ssh->portfwd_strptr++;
+           while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != '\t') {
+               if (*ssh->portfwd_strptr == ':') {
+                   /*
+                    * We've seen a colon in the middle of the
+                    * source port number. This means that
+                    * everything we've seen until now is the
+                    * source _address_, so we'll move it into
+                    * saddr and start sports from the beginning
+                    * again.
+                    */
+                   ssh->portfwd_strptr++;
+                   sports[n] = '\0';
+                   strcpy(saddr, sports);
+                   n = 0;
+               }
+               if (n < 255) sports[n++] = *ssh->portfwd_strptr++;
+           }
            sports[n] = 0;
-           if (*ssh->portfwd_strptr == '\t')
-               ssh->portfwd_strptr++;
-           n = 0;
-           while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':')
-               host[n++] = *ssh->portfwd_strptr++;
-           host[n] = 0;
-           if (*ssh->portfwd_strptr == ':')
+           if (type != 'D') {
+               if (*ssh->portfwd_strptr == '\t')
+                   ssh->portfwd_strptr++;
+               n = 0;
+               while (*ssh->portfwd_strptr && *ssh->portfwd_strptr != ':') {
+                   if (n < 255) host[n++] = *ssh->portfwd_strptr++;
+               }
+               host[n] = 0;
+               if (*ssh->portfwd_strptr == ':')
+                   ssh->portfwd_strptr++;
+               n = 0;
+               while (*ssh->portfwd_strptr) {
+                   if (n < 255) dports[n++] = *ssh->portfwd_strptr++;
+               }
+               dports[n] = 0;
                ssh->portfwd_strptr++;
-           n = 0;
-           while (*ssh->portfwd_strptr)
-               dports[n++] = *ssh->portfwd_strptr++;
-           dports[n] = 0;
-           ssh->portfwd_strptr++;
-           dport = atoi(dports);
-           dserv = 0;
-           if (dport == 0) {
-               dserv = 1;
-               se = getservbyname(dports, NULL);
-               if (se != NULL) {
-                   dport = ntohs(se->s_port);
-               } else {
-                   sprintf(buf,
-                           "Service lookup failed for destination port \"%s\"",
-                           dports);
-                   logevent(buf);
+               dport = atoi(dports);
+               dserv = 0;
+               if (dport == 0) {
+                   dserv = 1;
+                   dport = net_service_lookup(dports);
+                   if (!dport) {
+                       logeventf(ssh, "Service lookup failed for destination"
+                                 " port \"%s\"", dports);
+                   }
                }
+           } else {
+               while (*ssh->portfwd_strptr) ssh->portfwd_strptr++;
+               dport = dserv = -1;
            }
            sport = atoi(sports);
            sserv = 0;
            if (sport == 0) {
                sserv = 1;
-               se = getservbyname(sports, NULL);
-               if (se != NULL) {
-                   sport = ntohs(se->s_port);
-               } else {
-                   sprintf(buf,
-                           "Service lookup failed for source port \"%s\"",
-                           sports);
-                   logevent(buf);
+               sport = net_service_lookup(sports);
+               if (!sport) {
+                   logeventf(ssh, "Service lookup failed for source"
+                             " port \"%s\"", sports);
                }
            }
            if (sport && dport) {
                if (type == 'L') {
-                   pfd_addforward(host, dport, sport);
-                   sprintf(buf, "Local port %.*s%.*s%d%.*s forwarding to"
-                           " %s:%.*s%.*s%d%.*s",
-                           sserv ? strlen(sports) : 0, sports,
-                           sserv, "(", sport, sserv, ")",
-                           host,
-                           dserv ? strlen(dports) : 0, dports,
-                           dserv, "(", dport, dserv, ")");
-                   logevent(buf);
+                   pfd_addforward(host, dport, *saddr ? saddr : NULL,
+                                  sport, ssh, &ssh->cfg);
+                   logeventf(ssh, "Local port %.*s%.*s%.*s%.*s%d%.*s"
+                             " forwarding to %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, ")",
+                             host,
+                             (int)(dserv ? strlen(dports) : 0), dports,
+                             dserv, "(", dport, dserv, ")");
+               } else if (type == 'D') {
+                   pfd_addforward(NULL, -1, *saddr ? saddr : NULL,
+                                  sport, ssh, &ssh->cfg);
+                   logeventf(ssh, "Local port %.*s%.*s%.*s%.*s%d%.*s"
+                             " doing SOCKS dynamic forwarding",
+                             (int)(*saddr?strlen(saddr):0), *saddr?saddr:NULL,
+                             (int)(*saddr?1:0), ":",
+                             (int)(sserv ? strlen(sports) : 0), sports,
+                             sserv, "(", sport, sserv, ")");
                } else {
                    struct ssh_rportfwd *pf;
-                   pf = smalloc(sizeof(*pf));
+                   pf = snew(struct ssh_rportfwd);
                    strcpy(pf->dhost, host);
                    pf->dport = dport;
                    pf->sport = sport;
                    if (add234(ssh->rportfwds, pf) != pf) {
-                       sprintf(buf, 
-                               "Duplicate remote port forwarding to %s:%d",
-                               host, dport);
-                       logevent(buf);
+                       logeventf(ssh, "Duplicate remote port forwarding"
+                                 " to %s:%d", host, dport);
                        sfree(pf);
                    } else {
-                       sprintf(buf, "Requesting remote port %.*s%.*s%d%.*s"
-                               " forward to %s:%.*s%.*s%d%.*s",
-                           sserv ? strlen(sports) : 0, sports,
-                           sserv, "(", sport, sserv, ")",
-                           host,
-                           dserv ? strlen(dports) : 0, dports,
-                           dserv, "(", dport, dserv, ")");
-                       logevent(buf);
+                       logeventf(ssh, "Requesting remote port "
+                                 "%.*s%.*s%.*s%.*s%d%.*s"
+                                 " forward to %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, ")",
+                                 host,
+                                 (int)(dserv ? strlen(dports) : 0), dports,
+                                 dserv, "(", dport, dserv, ")");
                        ssh2_pkt_init(ssh, SSH2_MSG_GLOBAL_REQUEST);
                        ssh2_pkt_addstring(ssh, "tcpip-forward");
                        ssh2_pkt_addbool(ssh, 1);/* want reply */
-                       if (cfg.rport_acceptall)
+                       if (*saddr)
+                           ssh2_pkt_addstring(ssh, saddr);
+                       if (ssh->cfg.rport_acceptall)
                            ssh2_pkt_addstring(ssh, "0.0.0.0");
                        else
                            ssh2_pkt_addstring(ssh, "127.0.0.1");
@@ -5209,7 +5484,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                bombout(("Unexpected response to port "
                                         "forwarding request: packet type %d",
                                         ssh->pktin.type));
-                               crReturnV;
+                               crStopV;
                            }
                            logevent("Server refused this port forwarding");
                        } else {
@@ -5224,7 +5499,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Potentially enable agent forwarding.
      */
-    if (cfg.agentfwd && agent_exists()) {
+    if (ssh->cfg.agentfwd && agent_exists()) {
        logevent("Requesting OpenSSH-style agent forwarding");
        ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
        ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
@@ -5248,7 +5523,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
                bombout(("Unexpected response to agent forwarding request:"
                         " packet type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
            logevent("Agent forwarding refused");
        } else {
@@ -5260,12 +5535,12 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Now allocate a pty for the session.
      */
-    if (!cfg.nopty) {
+    if (!ssh->cfg.nopty) {
        ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
        ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);       /* recipient channel */
        ssh2_pkt_addstring(ssh, "pty-req");
        ssh2_pkt_addbool(ssh, 1);              /* want reply */
-       ssh2_pkt_addstring(ssh, cfg.termtype);
+       ssh2_pkt_addstring(ssh, ssh->cfg.termtype);
        ssh2_pkt_adduint32(ssh, ssh->term_width);
        ssh2_pkt_adduint32(ssh, ssh->term_height);
        ssh2_pkt_adduint32(ssh, 0);            /* pixel width */
@@ -5291,7 +5566,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
                bombout(("Unexpected response to pty request:"
                         " packet type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
            c_write_str(ssh, "Server refused to allocate pty\r\n");
            ssh->editing = ssh->echoing = 1;
@@ -5312,11 +5587,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
        char *cmd;
 
        if (ssh->fallback_cmd) {
-           subsys = cfg.ssh_subsys2;
-           cmd = cfg.remote_cmd_ptr2;
+           subsys = ssh->cfg.ssh_subsys2;
+           cmd = ssh->cfg.remote_cmd_ptr2;
        } else {
-           subsys = cfg.ssh_subsys;
-           cmd = cfg.remote_cmd_ptr;
+           subsys = ssh->cfg.ssh_subsys;
+           cmd = ssh->cfg.remote_cmd_ptr;
        }
 
        ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
@@ -5349,7 +5624,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            if (ssh->pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
                bombout(("Unexpected response to shell/command request:"
                         " packet type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
            /*
             * We failed to start the command. If this is the
@@ -5357,13 +5632,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
             * not, and if the fallback command exists, try falling
             * back to it before complaining.
             */
-           if (!ssh->fallback_cmd && cfg.remote_cmd_ptr2 != NULL) {
+           if (!ssh->fallback_cmd && ssh->cfg.remote_cmd_ptr2 != NULL) {
                logevent("Primary command failed; attempting fallback");
                ssh->fallback_cmd = TRUE;
                continue;
            }
            bombout(("Server refused to start a shell/command"));
-           crReturnV;
+           crStopV;
        } else {
            logevent("Started a shell/command");
        }
@@ -5379,7 +5654,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
     /*
      * Transfer data!
      */
-    ldisc_send(NULL, 0, 0);           /* cause ldisc to notice changes */
+    if (ssh->ldisc)
+       ldisc_send(ssh->ldisc, NULL, 0, 0);/* cause ldisc to notice changes */
     ssh->send_ok = 1;
     while (1) {
        crReturnV;
@@ -5399,7 +5675,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    continue;          /* extended but not stderr */
                ssh2_pkt_getstring(ssh, &data, &length);
                if (data) {
-                   int bufsize;
+                   int bufsize = 0;
                    c->v.v2.locwindow -= length;
                    switch (c->type) {
                      case CHAN_MAINSESSION:
@@ -5427,7 +5703,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                            if (c->u.a.lensofar == 4) {
                                c->u.a.totallen =
                                    4 + GET_32BIT(c->u.a.msglen);
-                               c->u.a.message = smalloc(c->u.a.totallen);
+                               c->u.a.message = snewn(c->u.a.totallen,
+                                                      unsigned char);
                                memcpy(c->u.a.message, c->u.a.msglen, 4);
                            }
                            if (c->u.a.lensofar >= 4 && length > 0) {
@@ -5441,22 +5718,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                                c->u.a.lensofar += l;
                            }
                            if (c->u.a.lensofar == c->u.a.totallen) {
-                               void *reply, *sentreply;
+                               void *reply;
                                int replylen;
-                               agent_query(c->u.a.message,
-                                           c->u.a.totallen, &reply,
-                                           &replylen);
-                               if (reply)
-                                   sentreply = reply;
-                               else {
-                                   /* Fake SSH_AGENT_FAILURE. */
-                                   sentreply = "\0\0\0\1\5";
-                                   replylen = 5;
-                               }
-                               ssh2_add_channel_data(c, sentreply, replylen);
-                               s->try_send = TRUE;
-                               if (reply)
-                                   sfree(reply);
+                               if (agent_query(c->u.a.message,
+                                               c->u.a.totallen,
+                                               &reply, &replylen,
+                                               ssh_agentf_callback, c))
+                                   ssh_agentf_callback(c, reply, replylen);
                                sfree(c->u.a.message);
                                c->u.a.lensofar = 0;
                            }
@@ -5500,6 +5768,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                if (!c || ((int)c->remoteid) == -1) {
                    bombout(("Received CHANNEL_CLOSE for %s channel %d\n",
                             c ? "half-open" : "nonexistent", i));
+                   crStopV;
                }
                /* Do pre-close processing on the channel. */
                switch (c->type) {
@@ -5532,6 +5801,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                 * See if that was the last channel left open.
                 */
                if (count234(ssh->channels) == 0) {
+                   logevent("All channels closed. Disconnecting");
 #if 0
                     /*
                      * We used to send SSH_MSG_DISCONNECT here,
@@ -5544,23 +5814,22 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                      * this is more polite than sending a
                      * DISCONNECT. So now we don't.
                      */
-                   logevent("All channels closed. Disconnecting");
                    ssh2_pkt_init(ssh, SSH2_MSG_DISCONNECT);
                    ssh2_pkt_adduint32(ssh, SSH2_DISCONNECT_BY_APPLICATION);
                    ssh2_pkt_addstring(ssh, "All open channels closed");
                    ssh2_pkt_addstring(ssh, "en");      /* language tag */
                    ssh2_pkt_send(ssh);
 #endif
-                   ssh->state = SSH_STATE_CLOSED;
-                   crReturnV;
+                    ssh_closing((Plug)ssh, NULL, 0, 0);
+                   crStopV;
                }
                continue;              /* remote sends close; ignore (FIXME) */
            } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
                unsigned i = ssh2_pkt_getuint32(ssh);
                struct ssh_channel *c;
                c = find234(ssh->channels, &i, ssh_channelfind);
-               if (!c)
-                   continue;          /* nonexistent channel */
+               if (!c || c->closes)
+                   continue;          /* nonexistent or closing channel */
                c->v.v2.remwindow += ssh2_pkt_getuint32(ssh);
                s->try_send = TRUE;
            } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
@@ -5628,9 +5897,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    ssh2_pkt_addstring(ssh, buf);
                    ssh2_pkt_addstring(ssh, "en");      /* language tag */
                    ssh2_pkt_send(ssh);
-                   connection_fatal("%s", buf);
-                   ssh->state = SSH_STATE_CLOSED;
-                   crReturnV;
+                   connection_fatal(ssh->frontend, "%s", buf);
+                    ssh_closing((Plug)ssh, NULL, 0, 0);
+                   crStopV;
                }
 
                /*
@@ -5684,11 +5953,14 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
            } else if (ssh->pktin.type == SSH2_MSG_CHANNEL_OPEN) {
                char *type;
                int typelen;
+               char *peeraddr;
+               int peeraddrlen;
+               int peerport;
                char *error = NULL;
                struct ssh_channel *c;
                unsigned remid, winsize, pktsize;
                ssh2_pkt_getstring(ssh, &type, &typelen);
-               c = smalloc(sizeof(struct ssh_channel));
+               c = snew(struct ssh_channel);
                c->ssh = ssh;
 
                remid = ssh2_pkt_getuint32(ssh);
@@ -5696,14 +5968,25 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                pktsize = ssh2_pkt_getuint32(ssh);
 
                if (typelen == 3 && !memcmp(type, "x11", 3)) {
+                   char *addrstr;
+
+                    ssh2_pkt_getstring(ssh, &peeraddr, &peeraddrlen);
+                   addrstr = snewn(peeraddrlen+1, char);
+                   memcpy(addrstr, peeraddr, peeraddrlen);
+                   peeraddr[peeraddrlen] = '\0';
+                    peerport = ssh2_pkt_getuint32(ssh);
+
                    if (!ssh->X11_fwd_enabled)
                        error = "X11 forwarding is not enabled";
-                   else if (x11_init(&c->u.x11.s, cfg.x11_display, c) !=
-                            NULL) {
+                   else if (x11_init(&c->u.x11.s, ssh->cfg.x11_display, c,
+                                     ssh->x11auth, addrstr, peerport,
+                                     &ssh->cfg) != NULL) {
                        error = "Unable to open an X11 connection";
                    } else {
                        c->type = CHAN_X11;
                    }
+
+                   sfree(addrstr);
                } else if (typelen == 15 &&
                           !memcmp(type, "forwarded-tcpip", 15)) {
                    struct ssh_rportfwd pf, *realpf;
@@ -5711,19 +5994,18 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                    int dummylen;
                    ssh2_pkt_getstring(ssh, &dummy, &dummylen);/* skip address */
                    pf.sport = ssh2_pkt_getuint32(ssh);
+                    ssh2_pkt_getstring(ssh, &peeraddr, &peeraddrlen);
+                    peerport = ssh2_pkt_getuint32(ssh);
                    realpf = find234(ssh->rportfwds, &pf, NULL);
                    if (realpf == NULL) {
                        error = "Remote port is not recognised";
                    } else {
                        char *e = pfd_newconnect(&c->u.pfd.s, realpf->dhost,
-                                                realpf->dport, c);
-                       char buf[1024];
-                       sprintf(buf, "Received remote port open request for %s:%d",
-                               realpf->dhost, realpf->dport);
-                       logevent(buf);
+                                                realpf->dport, c, &ssh->cfg);
+                       logeventf(ssh, "Received remote port open request"
+                                 " for %s:%d", realpf->dhost, realpf->dport);
                        if (e != NULL) {
-                           sprintf(buf, "Port open failed: %s", e);
-                           logevent(buf);
+                           logeventf(ssh, "Port open failed: %s", e);
                            error = "Port open failed";
                        } else {
                            logevent("Forwarded port opened successfully");
@@ -5768,13 +6050,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
                }
            } else {
                bombout(("Strange packet received: type %d", ssh->pktin.type));
-               crReturnV;
+               crStopV;
            }
        } else {
            /*
             * We have spare data. Add it to the channel buffer.
             */
-           ssh2_add_channel_data(ssh->mainchan, in, inlen);
+           ssh2_add_channel_data(ssh->mainchan, (char *)in, inlen);
            s->try_send = TRUE;
        }
        if (s->try_send) {
@@ -5784,7 +6066,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen, int ispkt)
             * Try to send data on all channels if we can.
             */
            for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
-               int bufsize = ssh2_try_send(c);
+               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:
@@ -5826,12 +6111,15 @@ static void ssh2_protocol(Ssh ssh, unsigned char *in, int inlen, int ispkt)
  * Returns an error message, or NULL on success.
  */
 static char *ssh_init(void *frontend_handle, void **backend_handle,
+                     Config *cfg,
                      char *host, int port, char **realhost, int nodelay)
 {
     char *p;
     Ssh ssh;
 
-    ssh = smalloc(sizeof(*ssh));
+    ssh = snew(struct ssh_tag);
+    ssh->cfg = *cfg;                  /* STRUCTURE COPY */
+    ssh->version = 0;                 /* when not ready yet */
     ssh->s = NULL;
     ssh->cipher = NULL;
     ssh->v1_cipher_ctx = NULL;
@@ -5841,7 +6129,7 @@ static char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->sccipher = NULL;
     ssh->sc_cipher_ctx = NULL;
     ssh->csmac = NULL;
-    ssh->sc_mac_ctx = NULL;
+    ssh->cs_mac_ctx = NULL;
     ssh->scmac = NULL;
     ssh->sc_mac_ctx = NULL;
     ssh->cscomp = NULL;
@@ -5849,11 +6137,14 @@ static char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->sccomp = NULL;
     ssh->sc_comp_ctx = NULL;
     ssh->kex = NULL;
+    ssh->kex_ctx = NULL;
     ssh->hostkey = NULL;
     ssh->exitcode = -1;
     ssh->state = SSH_STATE_PREPACKET;
     ssh->size_needed = FALSE;
     ssh->eof_needed = FALSE;
+    ssh->ldisc = NULL;
+    ssh->logctx = NULL;
     {
        static const struct Packet empty = { 0, 0, NULL, NULL, 0 };
        ssh->pktin = ssh->pktout = empty;
@@ -5863,6 +6154,8 @@ static char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->deferred_size = 0;
     ssh->fallback_cmd = 0;
     ssh->pkt_ctx = 0;
+    ssh->x11auth = NULL;
+    ssh->v1_compressing = FALSE;
     ssh->v2_outgoing_sequence = 0;
     ssh->ssh1_rdpkt_crstate = 0;
     ssh->ssh2_rdpkt_crstate = 0;
@@ -5876,6 +6169,9 @@ static char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->do_ssh1_login_state = NULL;
     ssh->do_ssh2_transport_state = NULL;
     ssh->do_ssh2_authconn_state = NULL;
+    ssh->mainchan = NULL;
+    ssh->throttled_all = 0;
+    ssh->v1_stdout_throttling = 0;
 
     *backend_handle = ssh;
 
@@ -5885,8 +6181,11 @@ static char *ssh_init(void *frontend_handle, void **backend_handle,
 #endif
 
     ssh->frontend = frontend_handle;
-    ssh->term_width = cfg.width;
-    ssh->term_height = cfg.height;
+    ssh->term_width = ssh->cfg.width;
+    ssh->term_height = ssh->cfg.height;
+
+    ssh->channels = NULL;
+    ssh->rportfwds = NULL;
 
     ssh->send_ok = 0;
     ssh->editing = 0;
@@ -5895,6 +6194,8 @@ static char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->overall_bufsize = 0;
     ssh->fallback_cmd = 0;
 
+    ssh->protocol = NULL;
+
     p = connect_to_host(ssh, host, port, realhost, nodelay);
     if (p != NULL)
        return p;
@@ -5902,6 +6203,80 @@ static char *ssh_init(void *frontend_handle, void **backend_handle,
     return NULL;
 }
 
+static void ssh_free(void *handle)
+{
+    Ssh ssh = (Ssh) handle;
+    struct ssh_channel *c;
+    struct ssh_rportfwd *pf;
+
+    if (ssh->v1_cipher_ctx)
+       ssh->cipher->free_context(ssh->v1_cipher_ctx);
+    if (ssh->cs_cipher_ctx)
+       ssh->cscipher->free_context(ssh->cs_cipher_ctx);
+    if (ssh->sc_cipher_ctx)
+       ssh->sccipher->free_context(ssh->sc_cipher_ctx);
+    if (ssh->cs_mac_ctx)
+       ssh->csmac->free_context(ssh->cs_mac_ctx);
+    if (ssh->sc_mac_ctx)
+       ssh->scmac->free_context(ssh->sc_mac_ctx);
+    if (ssh->cs_comp_ctx)
+       ssh->cscomp->compress_cleanup(ssh->cs_comp_ctx);
+    if (ssh->sc_comp_ctx)
+       ssh->sccomp->compress_cleanup(ssh->sc_comp_ctx);
+    if (ssh->kex_ctx)
+       dh_cleanup(ssh->kex_ctx);
+    sfree(ssh->savedhost);
+
+    if (ssh->channels) {
+       while ((c = delpos234(ssh->channels, 0)) != NULL) {
+           switch (c->type) {
+             case CHAN_X11:
+               if (c->u.x11.s != NULL)
+                   x11_close(c->u.x11.s);
+               break;
+             case CHAN_SOCKDATA:
+               if (c->u.pfd.s != NULL)
+                   pfd_close(c->u.pfd.s);
+               break;
+           }
+           sfree(c);
+       }
+       freetree234(ssh->channels);
+    }
+
+    if (ssh->rportfwds) {
+       while ((pf = delpos234(ssh->rportfwds, 0)) != NULL)
+           sfree(pf);
+       freetree234(ssh->rportfwds);
+    }
+    sfree(ssh->deferred_send_data);
+    if (ssh->x11auth)
+       x11_free_auth(ssh->x11auth);
+    sfree(ssh->do_ssh_init_state);
+    sfree(ssh->do_ssh1_login_state);
+    sfree(ssh->do_ssh2_transport_state);
+    sfree(ssh->do_ssh2_authconn_state);
+    
+    if (ssh->s)
+       ssh_do_close(ssh);
+    sfree(ssh);
+}
+
+/*
+ * Reconfigure the SSH backend.
+ * 
+ * Currently, this function does nothing very useful. In future,
+ * however, we could do some handy things with it. For example, we
+ * could make the port forwarding configurer active in the Change
+ * Settings box, and this routine could close down existing
+ * forwardings and open up new ones in response to changes.
+ */
+static void ssh_reconfig(void *handle, Config *cfg)
+{
+    Ssh ssh = (Ssh) handle;
+    ssh->cfg = *cfg;                  /* STRUCTURE COPY */
+}
+
 /*
  * Called to send data down the Telnet connection.
  */
@@ -5912,7 +6287,7 @@ static int ssh_send(void *handle, char *buf, int len)
     if (ssh == NULL || ssh->s == NULL || ssh->protocol == NULL)
        return 0;
 
-    ssh->protocol(ssh, buf, len, 0);
+    ssh->protocol(ssh, (unsigned char *)buf, len, 0);
 
     return ssh_sendbuffer(ssh);
 }
@@ -5968,9 +6343,7 @@ static void ssh_size(void *handle, int width, int height)
        ssh->size_needed = TRUE;       /* buffer for later */
        break;
       case SSH_STATE_SESSION:
-       if (!cfg.nopty) {
-           if (!term)
-               return;
+       if (!ssh->cfg.nopty) {
            if (ssh->version == 1) {
                send_packet(ssh, SSH1_CMSG_WINDOW_SIZE,
                            PKT_INT, ssh->term_height,
@@ -5993,6 +6366,31 @@ static void ssh_size(void *handle, int width, int height)
 }
 
 /*
+ * Return a list of the special codes that make sense in this
+ * protocol.
+ */
+static const struct telnet_special *ssh_get_specials(void *handle)
+{
+    Ssh ssh = (Ssh) handle;
+
+    if (ssh->version == 1) {
+       static const struct telnet_special ssh1_specials[] = {
+           {"IGNORE message", TS_NOP},
+           {NULL, 0}
+       };
+       return ssh1_specials;
+    } else if (ssh->version == 2) {
+       static const struct telnet_special ssh2_specials[] = {
+           {"Break", TS_BRK},
+           {"IGNORE message", TS_NOP},
+           {NULL, 0}
+       };
+       return ssh2_specials;
+    } else
+       return NULL;
+}
+
+/*
  * Send Telnet special codes. TS_EOF is useful for `plink', so you
  * can send an EOF and collect resulting output (e.g. `plink
  * hostname sort').
@@ -6019,7 +6417,7 @@ static void ssh_special(void *handle, Telnet_Special code)
            ssh2_pkt_send(ssh);
        }
        logevent("Sent EOF message");
-    } else if (code == TS_PING) {
+    } else if (code == TS_PING || code == TS_NOP) {
        if (ssh->state == SSH_STATE_CLOSED
            || ssh->state == SSH_STATE_PREPACKET) return;
        if (ssh->version == 1) {
@@ -6030,6 +6428,19 @@ static void ssh_special(void *handle, Telnet_Special code)
            ssh2_pkt_addstring_start(ssh);
            ssh2_pkt_send(ssh);
        }
+    } else if (code == TS_BRK) {
+       if (ssh->state == SSH_STATE_CLOSED
+           || ssh->state == SSH_STATE_PREPACKET) return;
+       if (ssh->version == 1) {
+           logevent("Unable to send BREAK signal in SSH1");
+       } else {
+           ssh2_pkt_init(ssh, SSH2_MSG_CHANNEL_REQUEST);
+           ssh2_pkt_adduint32(ssh, ssh->mainchan->remoteid);
+           ssh2_pkt_addstring(ssh, "break");
+           ssh2_pkt_addbool(ssh, 0);
+           ssh2_pkt_adduint32(ssh, 0);   /* default break length */
+           ssh2_pkt_send(ssh);
+       }
     } else {
        /* do nothing */
     }
@@ -6039,7 +6450,7 @@ void *new_sock_channel(void *handle, Socket s)
 {
     Ssh ssh = (Ssh) handle;
     struct ssh_channel *c;
-    c = smalloc(sizeof(struct ssh_channel));
+    c = snew(struct ssh_channel);
     c->ssh = ssh;
 
     if (c) {
@@ -6058,7 +6469,7 @@ void *new_sock_channel(void *handle, Socket s)
  * This is called when stdout/stderr (the entity to which
  * from_backend sends data) manages to clear some backlog.
  */
-void ssh_unthrottle(void *handle, int bufsize)
+static void ssh_unthrottle(void *handle, int bufsize)
 {
     Ssh ssh = (Ssh) handle;
     if (ssh->version == 1) {
@@ -6072,15 +6483,12 @@ void ssh_unthrottle(void *handle, int bufsize)
     }
 }
 
-void ssh_send_port_open(void *handle, void *channel, char *hostname,
-                       int port, char *org)
+void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
 {
-    Ssh ssh = (Ssh) handle;
     struct ssh_channel *c = (struct ssh_channel *)channel;
-    char buf[1024];
+    Ssh ssh = c->ssh;
 
-    sprintf(buf, "Opening forwarded connection to %.512s:%d", hostname, port);
-    logevent(buf);
+    logeventf(ssh, "Opening forwarded connection to %s:%d", hostname, port);
 
     if (ssh->version == 1) {
        send_packet(ssh, SSH1_MSG_PORT_OPEN,
@@ -6133,10 +6541,25 @@ static int ssh_ldisc(void *handle, int option)
     return FALSE;
 }
 
+static void ssh_provide_ldisc(void *handle, void *ldisc)
+{
+    Ssh ssh = (Ssh) handle;
+    ssh->ldisc = ldisc;
+}
+
+static void ssh_provide_logctx(void *handle, void *logctx)
+{
+    Ssh ssh = (Ssh) handle;
+    ssh->logctx = logctx;
+}
+
 static int ssh_return_exitcode(void *handle)
 {
     Ssh ssh = (Ssh) handle;
-    return ssh->exitcode;
+    if (ssh->s != NULL)
+        return -1;
+    else
+        return (ssh->exitcode >= 0 ? ssh->exitcode : 0);
 }
 
 /*
@@ -6152,14 +6575,19 @@ extern int ssh_fallback_cmd(void *handle)
 
 Backend ssh_backend = {
     ssh_init,
+    ssh_free,
+    ssh_reconfig,
     ssh_send,
     ssh_sendbuffer,
     ssh_size,
     ssh_special,
+    ssh_get_specials,
     ssh_socket,
     ssh_return_exitcode,
     ssh_sendok,
     ssh_ldisc,
+    ssh_provide_ldisc,
+    ssh_provide_logctx,
     ssh_unthrottle,
     22
 };