X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/2425184bb0dd4cf3924f717c0b07c2ca6e7da4e6..985b644054f5e0d777184c48bfd8a97e824705fd:/ssh.c

diff --git a/ssh.c b/ssh.c
index 7f3748af..e0556a62 100644
--- a/ssh.c
+++ b/ssh.c
@@ -166,6 +166,110 @@ static const char *const ssh2_disconnect_reasons[] = {
 #define BUG_SSH2_REKEY                           64
 #define BUG_SSH2_PK_SESSIONID                   128
 
+/*
+ * Codes for terminal modes.
+ * Most of these are the same in SSH-1 and SSH-2.
+ * This list is derived from draft-ietf-secsh-connect-25 and
+ * SSH-1 RFC-1.2.31.
+ */
+static const struct {
+    const char* const mode;
+    int opcode;
+    enum { TTY_OP_CHAR, TTY_OP_BOOL } type;
+} ssh_ttymodes[] = {
+    /* "V" prefix discarded for special characters relative to SSH specs */
+    { "INTR",	      1, TTY_OP_CHAR },
+    { "QUIT",	      2, TTY_OP_CHAR },
+    { "ERASE",	      3, TTY_OP_CHAR },
+    { "KILL",	      4, TTY_OP_CHAR },
+    { "EOF",	      5, TTY_OP_CHAR },
+    { "EOL",	      6, TTY_OP_CHAR },
+    { "EOL2",	      7, TTY_OP_CHAR },
+    { "START",	      8, TTY_OP_CHAR },
+    { "STOP",	      9, TTY_OP_CHAR },
+    { "SUSP",	     10, TTY_OP_CHAR },
+    { "DSUSP",	     11, TTY_OP_CHAR },
+    { "REPRINT",     12, TTY_OP_CHAR },
+    { "WERASE",	     13, TTY_OP_CHAR },
+    { "LNEXT",	     14, TTY_OP_CHAR },
+    { "FLUSH",	     15, TTY_OP_CHAR },
+    { "SWTCH",	     16, TTY_OP_CHAR },
+    { "STATUS",	     17, TTY_OP_CHAR },
+    { "DISCARD",     18, TTY_OP_CHAR },
+    { "IGNPAR",	     30, TTY_OP_BOOL },
+    { "PARMRK",	     31, TTY_OP_BOOL },
+    { "INPCK",	     32, TTY_OP_BOOL },
+    { "ISTRIP",	     33, TTY_OP_BOOL },
+    { "INLCR",	     34, TTY_OP_BOOL },
+    { "IGNCR",	     35, TTY_OP_BOOL },
+    { "ICRNL",	     36, TTY_OP_BOOL },
+    { "IUCLC",	     37, TTY_OP_BOOL },
+    { "IXON",	     38, TTY_OP_BOOL },
+    { "IXANY",	     39, TTY_OP_BOOL },
+    { "IXOFF",	     40, TTY_OP_BOOL },
+    { "IMAXBEL",     41, TTY_OP_BOOL },
+    { "ISIG",	     50, TTY_OP_BOOL },
+    { "ICANON",	     51, TTY_OP_BOOL },
+    { "XCASE",	     52, TTY_OP_BOOL },
+    { "ECHO",	     53, TTY_OP_BOOL },
+    { "ECHOE",	     54, TTY_OP_BOOL },
+    { "ECHOK",	     55, TTY_OP_BOOL },
+    { "ECHONL",	     56, TTY_OP_BOOL },
+    { "NOFLSH",	     57, TTY_OP_BOOL },
+    { "TOSTOP",	     58, TTY_OP_BOOL },
+    { "IEXTEN",	     59, TTY_OP_BOOL },
+    { "ECHOCTL",     60, TTY_OP_BOOL },
+    { "ECHOKE",	     61, TTY_OP_BOOL },
+    { "PENDIN",	     62, TTY_OP_BOOL }, /* XXX is this a real mode? */
+    { "OPOST",	     70, TTY_OP_BOOL },
+    { "OLCUC",	     71, TTY_OP_BOOL },
+    { "ONLCR",	     72, TTY_OP_BOOL },
+    { "OCRNL",	     73, TTY_OP_BOOL },
+    { "ONOCR",	     74, TTY_OP_BOOL },
+    { "ONLRET",	     75, TTY_OP_BOOL },
+    { "CS7",	     90, TTY_OP_BOOL },
+    { "CS8",	     91, TTY_OP_BOOL },
+    { "PARENB",	     92, TTY_OP_BOOL },
+    { "PARODD",	     93, TTY_OP_BOOL }
+};
+
+/* Miscellaneous other tty-related constants. */
+#define SSH_TTY_OP_END		  0
+/* The opcodes for ISPEED/OSPEED differ between SSH-1 and SSH-2. */
+#define SSH1_TTY_OP_ISPEED	192
+#define SSH1_TTY_OP_OSPEED	193
+#define SSH2_TTY_OP_ISPEED	128
+#define SSH2_TTY_OP_OSPEED	129
+
+/* Helper functions for parsing tty-related config. */
+static unsigned int ssh_tty_parse_specchar(char *s)
+{
+    unsigned int ret;
+    if (*s) {
+	char *next = NULL;
+	ret = ctrlparse(s, &next);
+	if (!next) ret = s[0];
+    } else {
+	ret = 255; /* special value meaning "don't set" */
+    }
+    return ret;
+}
+static unsigned int ssh_tty_parse_boolean(char *s)
+{
+    if (stricmp(s, "yes") == 0 ||
+	stricmp(s, "on") == 0 ||
+	stricmp(s, "true") == 0 ||
+	stricmp(s, "+") == 0)
+	return 1; /* true */
+    else if (stricmp(s, "no") == 0 ||
+	     stricmp(s, "off") == 0 ||
+	     stricmp(s, "false") == 0 ||
+	     stricmp(s, "-") == 0)
+	return 0; /* false */
+    else
+	return (atoi(s) != 0);
+}
+
 #define translate(x) if (type == x) return #x
 #define translatec(x,ctx) if (type == x && (pkt_ctx & ctx)) return #x
 static char *ssh1_pkt_type(int type)
@@ -256,18 +360,6 @@ static char *ssh2_pkt_type(int pkt_ctx, int type)
 #undef translate
 #undef translatec
 
-#define GET_32BIT(cp) \
-    (((unsigned long)(unsigned char)(cp)[0] << 24) | \
-    ((unsigned long)(unsigned char)(cp)[1] << 16) | \
-    ((unsigned long)(unsigned char)(cp)[2] << 8) | \
-    ((unsigned long)(unsigned char)(cp)[3]))
-
-#define PUT_32BIT(cp, value) { \
-    (cp)[0] = (unsigned char)((value) >> 24); \
-    (cp)[1] = (unsigned char)((value) >> 16); \
-    (cp)[2] = (unsigned char)((value) >> 8); \
-    (cp)[3] = (unsigned char)(value); }
-
 /* Enumeration values for fields in SSH-1 packets */
 enum {
     PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM,
@@ -319,14 +411,19 @@ enum {
 typedef struct ssh_tag *Ssh;
 struct Packet;
 
+static struct Packet *ssh1_pkt_init(int pkt_type);
 static struct Packet *ssh2_pkt_init(int pkt_type);
+static void ssh_pkt_ensure(struct Packet *, int length);
+static void ssh_pkt_adddata(struct Packet *, void *data, int len);
+static void ssh_pkt_addbyte(struct Packet *, unsigned char value);
 static void ssh2_pkt_addbool(struct Packet *, unsigned char value);
-static void ssh2_pkt_adduint32(struct Packet *, unsigned long value);
-static void ssh2_pkt_addstring_start(struct Packet *);
-static void ssh2_pkt_addstring_str(struct Packet *, char *data);
-static void ssh2_pkt_addstring_data(struct Packet *, char *data, int len);
-static void ssh2_pkt_addstring(struct Packet *, char *data);
+static void ssh_pkt_adduint32(struct Packet *, unsigned long value);
+static void ssh_pkt_addstring_start(struct Packet *);
+static void ssh_pkt_addstring_str(struct Packet *, char *data);
+static void ssh_pkt_addstring_data(struct Packet *, char *data, int len);
+static void ssh_pkt_addstring(struct Packet *, char *data);
 static unsigned char *ssh2_mpint_fmt(Bignum b, int *len);
+static void ssh1_pkt_addmp(struct Packet *, Bignum b);
 static void ssh2_pkt_addmp(struct Packet *, Bignum b);
 static int ssh2_pkt_construct(Ssh, struct Packet *);
 static void ssh2_pkt_send(Ssh, struct Packet *);
@@ -342,18 +439,18 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
  * 
  *  - SSH1_BUFFER_LIMIT is the amount of backlog that must build up
  *    on a local data stream before we throttle the whole SSH
- *    connection (in SSH1 only). Throttling the whole connection is
+ *    connection (in SSH-1 only). Throttling the whole connection is
  *    pretty drastic so we set this high in the hope it won't
  *    happen very often.
  * 
  *  - SSH_MAX_BACKLOG is the amount of backlog that must build up
  *    on the SSH connection itself before we defensively throttle
  *    _all_ local data streams. This is pretty drastic too (though
- *    thankfully unlikely in SSH2 since the window mechanism should
+ *    thankfully unlikely in SSH-2 since the window mechanism should
  *    ensure that the server never has any need to throttle its end
  *    of the connection), so we set this high as well.
  * 
- *  - OUR_V2_WINSIZE is the maximum window size we present on SSH2
+ *  - OUR_V2_WINSIZE is the maximum window size we present on SSH-2
  *    channels.
  */
 
@@ -364,34 +461,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 
 const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
 
-static void *nullmac_make_context(void)
-{
-    return NULL;
-}
-static void nullmac_free_context(void *handle)
-{
-}
-static void nullmac_key(void *handle, unsigned char *key)
-{
-}
-static void nullmac_generate(void *handle, unsigned char *blk, int len,
-			     unsigned long seq)
-{
-}
-static int nullmac_verify(void *handle, unsigned char *blk, int len,
-			  unsigned long seq)
-{
-    return 1;
-}
-const static struct ssh_mac ssh_mac_none = {
-    nullmac_make_context, nullmac_free_context, nullmac_key,
-    nullmac_generate, nullmac_verify, "none", 0
-};
 const static struct ssh_mac *macs[] = {
-    &ssh_sha1, &ssh_md5, &ssh_mac_none
+    &ssh_sha1, &ssh_md5
 };
 const static struct ssh_mac *buggymacs[] = {
-    &ssh_sha1_buggy, &ssh_md5, &ssh_mac_none
+    &ssh_sha1_buggy, &ssh_md5
 };
 
 static void *ssh_comp_none_init(void)
@@ -439,7 +513,7 @@ struct ssh_channel {
     /* True if we opened this channel but server hasn't confirmed. */
     int halfopen;
     /*
-     * In SSH1, this value contains four bits:
+     * In SSH-1, this value contains four bits:
      * 
      *   1   We have sent SSH1_MSG_CHANNEL_CLOSE.
      *   2   We have sent SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION.
@@ -475,11 +549,11 @@ struct ssh_channel {
 };
 
 /*
- * 2-3-4 tree storing remote->local port forwardings. SSH 1 and SSH
- * 2 use this structure in different ways, reflecting SSH 2's
+ * 2-3-4 tree storing remote->local port forwardings. SSH-1 and SSH-2
+ * use this structure in different ways, reflecting SSH-2's
  * altogether saner approach to port forwarding.
  * 
- * In SSH 1, you arrange a remote forwarding by sending the server
+ * In SSH-1, you arrange a remote forwarding by sending the server
  * the remote port number, and the local destination host:port.
  * When a connection comes in, the server sends you back that
  * host:port pair, and you connect to it. This is a ready-made
@@ -491,15 +565,15 @@ struct ssh_channel {
  * host:port pairs we _are_ trying to forward to, and reject a
  * connection request from the server if it's not in the list.
  * 
- * In SSH 2, each side of the connection minds its own business and
+ * In SSH-2, each side of the connection minds its own business and
  * doesn't send unnecessary information to the other. You arrange a
  * remote forwarding by sending the server just the remote port
  * number. When a connection comes in, the server tells you which
  * of its ports was connected to; and _you_ have to remember what
  * local host:port pair went with that port number.
  * 
- * Hence, in SSH 1 this structure is indexed by destination
- * host:port pair, whereas in SSH 2 it is indexed by source port.
+ * Hence, in SSH-1 this structure is indexed by destination
+ * host:port pair, whereas in SSH-2 it is indexed by source port.
  */
 struct ssh_portfwd; /* forward declaration */
 
@@ -534,15 +608,15 @@ struct ssh_portfwd {
 	     sfree((pf)->sserv), sfree((pf)->dserv)) : (void)0 ), sfree(pf) )
 
 struct Packet {
-    long length;
-    long forcepad; /* Force padding to at least this length */
-    int type;
-    unsigned long sequence;
-    unsigned char *data;
-    unsigned char *body;
-    long savedpos;
-    long maxlen;
-    long encrypted_len;		       /* for SSH2 total-size counting */
+    long length;	    /* length of `data' actually used */
+    long forcepad;	    /* SSH-2: force padding to at least this length */
+    int type;		    /* only used for incoming packets */
+    unsigned long sequence; /* SSH-2 incoming sequence number */
+    unsigned char *data;    /* allocated storage */
+    unsigned char *body;    /* offset of payload within `data' */
+    long savedpos;	    /* temporary index into `data' (for strings) */
+    long maxlen;	    /* amount of storage allocated for `data' */
+    long encrypted_len;	    /* for SSH-2 total-size counting */
 
     /*
      * State associated with packet logging
@@ -647,6 +721,7 @@ struct ssh_tag {
     struct ssh_channel *mainchan;      /* primary session channel */
     int exitcode;
     int close_expected;
+    int clean_exit;
 
     tree234 *rportfwds, *portfwds;
 
@@ -674,6 +749,7 @@ struct ssh_tag {
      */
     int fallback_cmd;
 
+    bufchain banner;	/* accumulates banners during do_ssh2_authconn */
     /*
      * Used for username and password input.
      */
@@ -710,7 +786,7 @@ struct ssh_tag {
     struct rdpkt1_state_tag rdpkt1_state;
     struct rdpkt2_state_tag rdpkt2_state;
 
-    /* ssh1 and ssh2 use this for different things, but both use it */
+    /* SSH-1 and SSH-2 use this for different things, but both use it */
     int protocol_initial_phase_done;
 
     void (*protocol) (Ssh ssh, void *vin, int inlen,
@@ -815,6 +891,29 @@ static void end_log_omission(Ssh ssh, struct Packet *pkt)
     pkt->logmode = PKTLOG_EMIT;
 }
 
+/* Helper function for common bits of parsing cfg.ttymodes. */
+static void parse_ttymodes(Ssh ssh, char *modes,
+			   void (*do_mode)(void *data, char *mode, char *val),
+			   void *data)
+{
+    while (*modes) {
+	char *t = strchr(modes, '\t');
+	char *m = snewn(t-modes+1, char);
+	char *val;
+	strncpy(m, modes, t-modes);
+	m[t-modes] = '\0';
+	if (*(t+1) == 'A')
+	    val = get_ttymode(ssh->frontend, m);
+	else
+	    val = dupstr(t+2);
+	if (val)
+	    do_mode(data, m, val);
+	sfree(m);
+	sfree(val);
+	modes += strlen(modes) + 1;
+    }
+}
+
 static int ssh_channelcmp(void *av, void *bv)
 {
     struct ssh_channel *a = (struct ssh_channel *) av;
@@ -982,7 +1081,7 @@ static struct Packet *ssh_new_packet(void)
 {
     struct Packet *pkt = snew(struct Packet);
 
-    pkt->data = NULL;
+    pkt->body = pkt->data = NULL;
     pkt->maxlen = 0;
     pkt->logmode = PKTLOG_EMIT;
     pkt->nblanks = 0;
@@ -1168,7 +1267,8 @@ static struct Packet *ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
      * _Completely_ silly lengths should be stomped on before they
      * do us any more damage.
      */
-    if (st->len < 0 || st->pad < 0 || st->len + st->pad < 0) {
+    if (st->len < 0 || st->len > 35000 || st->pad < 4 ||
+	st->len - st->pad < 1 || (st->len + 4) % st->cipherblk != 0) {
 	bombout(("Incoming packet was garbled on decryption"));
 	ssh_free_packet(st->pktin);
 	crStop(NULL);
@@ -1282,36 +1382,9 @@ static struct Packet *ssh2_rdpkt(Ssh ssh, unsigned char **data, int *datalen)
     crFinish(st->pktin);
 }
 
-static void ssh1_pktout_size(struct Packet *pkt, int len)
-{
-    int pad, biglen;
-
-    len += 5;			       /* type and CRC */
-    pad = 8 - (len % 8);
-    biglen = len + pad;
-
-    pkt->length = len - 5;
-    if (pkt->maxlen < biglen) {
-	pkt->maxlen = biglen;
-	pkt->data = sresize(pkt->data, biglen + 4 + APIEXTRA, unsigned char);
-    }
-    pkt->body = pkt->data + 4 + pad + 1;
-}
-
-static struct Packet *s_wrpkt_start(int type, int len)
-{
-    struct Packet *pkt = ssh_new_packet();
-    ssh1_pktout_size(pkt, len);
-    pkt->type = type;
-    /* Initialise log omission state */
-    pkt->nblanks = 0;
-    pkt->blanks = NULL;
-    return pkt;
-}
-
-static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt)
+static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt, int *offset_p)
 {
-    int pad, biglen, i;
+    int pad, biglen, i, pktoffs;
     unsigned long crc;
 #ifdef __SC__
     /*
@@ -1324,12 +1397,10 @@ static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt)
 #endif
     int len;
 
-    pkt->body[-1] = pkt->type;
-
     if (ssh->logctx)
-	log_packet(ssh->logctx, PKT_OUTGOING, pkt->type,
-		   ssh1_pkt_type(pkt->type),
-		   pkt->body, pkt->length,
+	log_packet(ssh->logctx, PKT_OUTGOING, pkt->data[12],
+		   ssh1_pkt_type(pkt->data[12]),
+		   pkt->body, pkt->length - (pkt->body - pkt->data),
 		   pkt->nblanks, pkt->blanks);
     sfree(pkt->blanks); pkt->blanks = NULL;
     pkt->nblanks = 0;
@@ -1338,132 +1409,99 @@ static int s_wrpkt_prepare(Ssh ssh, struct Packet *pkt)
 	unsigned char *compblk;
 	int complen;
 	zlib_compress_block(ssh->cs_comp_ctx,
-			    pkt->body - 1, pkt->length + 1,
+			    pkt->data + 12, pkt->length - 12,
 			    &compblk, &complen);
-	ssh1_pktout_size(pkt, complen - 1);
-	memcpy(pkt->body - 1, compblk, complen);
+	memcpy(pkt->data + 12, compblk, complen);
 	sfree(compblk);
+	pkt->length = complen + 12;
     }
 
-    len = pkt->length + 5;	       /* type and CRC */
+    ssh_pkt_ensure(pkt, pkt->length + 4); /* space for CRC */
+    pkt->length += 4;
+    len = pkt->length - 4 - 8;	/* len(type+data+CRC) */
     pad = 8 - (len % 8);
-    biglen = len + pad;
+    pktoffs = 8 - pad;
+    biglen = len + pad;		/* len(padding+type+data+CRC) */
 
-    for (i = 0; i < pad; i++)
-	pkt->data[i + 4] = random_byte();
-    crc = crc32_compute(pkt->data + 4, biglen - 4);
-    PUT_32BIT(pkt->data + biglen, crc);
-    PUT_32BIT(pkt->data, len);
+    for (i = pktoffs; i < 4+8; i++)
+	pkt->data[i] = random_byte();
+    crc = crc32_compute(pkt->data + pktoffs + 4, biglen - 4); /* all ex len */
+    PUT_32BIT(pkt->data + pktoffs + 4 + biglen - 4, crc);
+    PUT_32BIT(pkt->data + pktoffs, len);
 
     if (ssh->cipher)
-	ssh->cipher->encrypt(ssh->v1_cipher_ctx, pkt->data + 4, biglen);
+	ssh->cipher->encrypt(ssh->v1_cipher_ctx,
+			     pkt->data + pktoffs + 4, biglen);
 
-    return biglen + 4;
+    if (offset_p) *offset_p = pktoffs;
+    return biglen + 4;		/* len(length+padding+type+data+CRC) */
 }
 
 static void s_wrpkt(Ssh ssh, struct Packet *pkt)
 {
-    int len, backlog;
-    len = s_wrpkt_prepare(ssh, pkt);
-    backlog = sk_write(ssh->s, (char *)pkt->data, len);
+    int len, backlog, offset;
+    len = s_wrpkt_prepare(ssh, pkt, &offset);
+    backlog = sk_write(ssh->s, (char *)pkt->data + offset, len);
     if (backlog > SSH_MAX_BACKLOG)
 	ssh_throttle_all(ssh, 1, backlog);
+    ssh_free_packet(pkt);
 }
 
 static void s_wrpkt_defer(Ssh ssh, struct Packet *pkt)
 {
-    int len;
-    len = s_wrpkt_prepare(ssh, pkt);
+    int len, offset;
+    len = s_wrpkt_prepare(ssh, pkt, &offset);
     if (ssh->deferred_len + len > ssh->deferred_size) {
 	ssh->deferred_size = ssh->deferred_len + len + 128;
 	ssh->deferred_send_data = sresize(ssh->deferred_send_data,
 					  ssh->deferred_size,
 					  unsigned char);
     }
-    memcpy(ssh->deferred_send_data + ssh->deferred_len, pkt->data, len);
+    memcpy(ssh->deferred_send_data + ssh->deferred_len,
+	   pkt->data + offset, len);
     ssh->deferred_len += len;
+    ssh_free_packet(pkt);
 }
 
 /*
- * Construct a packet with the specified contents.
+ * Construct a SSH-1 packet with the specified contents.
+ * (This all-at-once interface used to be the only one, but now SSH-1
+ * packets can also be constructed incrementally.)
  */
-static struct Packet *construct_packet(Ssh ssh, int pkttype,
-				       va_list ap1, va_list ap2)
+static struct Packet *construct_packet(Ssh ssh, int pkttype, va_list ap)
 {
-    unsigned char *p, *argp, argchar;
-    unsigned long argint;
-    int pktlen, argtype, arglen;
+    int argtype;
     Bignum bn;
     struct Packet *pkt;
 
-    pktlen = 0;
-    while ((argtype = va_arg(ap1, int)) != PKT_END) {
-	switch (argtype) {
-	  case PKT_INT:
-	    (void) va_arg(ap1, int);
-	    pktlen += 4;
-	    break;
-	  case PKT_CHAR:
-	    (void) va_arg(ap1, int);
-	    pktlen++;
-	    break;
-	  case PKT_DATA:
-	    (void) va_arg(ap1, unsigned char *);
-	    arglen = va_arg(ap1, int);
-	    pktlen += arglen;
-	    break;
-	  case PKT_STR:
-	    argp = va_arg(ap1, unsigned char *);
-	    arglen = strlen((char *)argp);
-	    pktlen += 4 + arglen;
-	    break;
-	  case PKT_BIGNUM:
-	    bn = va_arg(ap1, Bignum);
-	    pktlen += ssh1_bignum_length(bn);
-	    break;
-	  case PKTT_PASSWORD:
-	  case PKTT_DATA:
-	  case PKTT_OTHER:
-	    /* ignore this pass */
-	    break;
-	  default:
-	    assert(0);
-	}
-    }
-
-    pkt = s_wrpkt_start(pkttype, pktlen);
-    p = pkt->body;
+    pkt = ssh1_pkt_init(pkttype);
 
-    while ((argtype = va_arg(ap2, int)) != PKT_END) {
-	int offset = p - pkt->body, len = 0;
+    while ((argtype = va_arg(ap, int)) != PKT_END) {
+	unsigned char *argp, argchar;
+	unsigned long argint;
+	int arglen;
 	switch (argtype) {
 	  /* Actual fields in the packet */
 	  case PKT_INT:
-	    argint = va_arg(ap2, int);
-	    PUT_32BIT(p, argint);
-	    len = 4;
+	    argint = va_arg(ap, int);
+	    ssh_pkt_adduint32(pkt, argint);
 	    break;
 	  case PKT_CHAR:
-	    argchar = (unsigned char) va_arg(ap2, int);
-	    *p = argchar;
-	    len = 1;
+	    argchar = (unsigned char) va_arg(ap, int);
+	    ssh_pkt_addbyte(pkt, argchar);
 	    break;
 	  case PKT_DATA:
-	    argp = va_arg(ap2, unsigned char *);
-	    arglen = va_arg(ap2, int);
-	    memcpy(p, argp, arglen);
-	    len = arglen;
+	    argp = va_arg(ap, unsigned char *);
+	    arglen = va_arg(ap, int);
+	    ssh_pkt_adddata(pkt, argp, arglen);
 	    break;
 	  case PKT_STR:
-	    argp = va_arg(ap2, unsigned char *);
-	    arglen = strlen((char *)argp);
-	    PUT_32BIT(p, arglen);
-	    memcpy(p + 4, argp, arglen);
-	    len = arglen + 4;
+	    argp = va_arg(ap, unsigned char *);
+	    ssh_pkt_addstring(pkt, argp);
 	    break;
 	  case PKT_BIGNUM:
-	    bn = va_arg(ap2, Bignum);
-	    len = ssh1_write_bignum(p, bn);
+	    bn = va_arg(ap, Bignum);
+	    ssh1_pkt_addmp(pkt, bn);
 	    break;
 	  /* Tokens for modifications to packet logging */
 	  case PKTT_PASSWORD:
@@ -1476,16 +1514,6 @@ static struct Packet *construct_packet(Ssh ssh, int pkttype,
 	    end_log_omission(ssh, pkt);
 	    break;
 	}
-	p += len;
-	/* Deal with logfile omission, if required. */
-	if (len && (pkt->logmode != PKTLOG_EMIT)) {
-	    pkt->nblanks++;
-	    pkt->blanks = sresize(pkt->blanks, pkt->nblanks,
-				  struct logblank_t);
-	    pkt->blanks[pkt->nblanks-1].offset = offset;
-	    pkt->blanks[pkt->nblanks-1].len    = len;
-	    pkt->blanks[pkt->nblanks-1].type   = pkt->logmode;
-	}
     }
 
     return pkt;
@@ -1494,27 +1522,21 @@ static struct Packet *construct_packet(Ssh ssh, int pkttype,
 static void send_packet(Ssh ssh, int pkttype, ...)
 {
     struct Packet *pkt;
-    va_list ap1, ap2;
-    va_start(ap1, pkttype);
-    va_start(ap2, pkttype);
-    pkt = construct_packet(ssh, pkttype, ap1, ap2);
-    va_end(ap2);
-    va_end(ap1);
+    va_list ap;
+    va_start(ap, pkttype);
+    pkt = construct_packet(ssh, pkttype, ap);
+    va_end(ap);
     s_wrpkt(ssh, pkt);
-    ssh_free_packet(pkt);
 }
 
 static void defer_packet(Ssh ssh, int pkttype, ...)
 {
     struct Packet *pkt;
-    va_list ap1, ap2;
-    va_start(ap1, pkttype);
-    va_start(ap2, pkttype);
-    pkt = construct_packet(ssh, pkttype, ap1, ap2);
-    va_end(ap2);
-    va_end(ap1);
+    va_list ap;
+    va_start(ap, pkttype);
+    pkt = construct_packet(ssh, pkttype, ap);
+    va_end(ap);
     s_wrpkt_defer(ssh, pkt);
-    ssh_free_packet(pkt);
 }
 
 static int ssh_versioncmp(char *a, char *b)
@@ -1541,7 +1563,6 @@ static int ssh_versioncmp(char *a, char *b)
  * Utility routines for putting an SSH-protocol `string' and
  * `uint32' into a SHA state.
  */
-#include <stdio.h>
 static void sha_string(SHA_State * s, void *str, int len)
 {
     unsigned char lenblk[4];
@@ -1558,77 +1579,80 @@ static void sha_uint32(SHA_State * s, unsigned i)
 }
 
 /*
- * SSH2 packet construction functions.
+ * Packet construction functions. Mostly shared between SSH-1 and SSH-2.
  */
-static void ssh2_pkt_ensure(struct Packet *pkt, int length)
+static void ssh_pkt_ensure(struct Packet *pkt, int length)
 {
     if (pkt->maxlen < length) {
+	unsigned char *body = pkt->body;
+	int offset = body ? pkt->data - body : 0;
 	pkt->maxlen = length + 256;
 	pkt->data = sresize(pkt->data, pkt->maxlen + APIEXTRA, unsigned char);
+	if (body) pkt->body = pkt->data + offset;
     }
 }
-static void ssh2_pkt_adddata(struct Packet *pkt, void *data, int len)
+static void ssh_pkt_adddata(struct Packet *pkt, void *data, int len)
 {
     if (pkt->logmode != PKTLOG_EMIT) {
 	pkt->nblanks++;
 	pkt->blanks = sresize(pkt->blanks, pkt->nblanks, struct logblank_t);
-	pkt->blanks[pkt->nblanks-1].offset = pkt->length - 6;
+	assert(pkt->body);
+	pkt->blanks[pkt->nblanks-1].offset = pkt->length -
+					     (pkt->body - pkt->data);
 	pkt->blanks[pkt->nblanks-1].len = len;
 	pkt->blanks[pkt->nblanks-1].type = pkt->logmode;
     }
     pkt->length += len;
-    ssh2_pkt_ensure(pkt, pkt->length);
+    ssh_pkt_ensure(pkt, pkt->length);
     memcpy(pkt->data + pkt->length - len, data, len);
 }
-static void ssh2_pkt_addbyte(struct Packet *pkt, unsigned char byte)
+static void ssh_pkt_addbyte(struct Packet *pkt, unsigned char byte)
 {
-    ssh2_pkt_adddata(pkt, &byte, 1);
-}
-static struct Packet *ssh2_pkt_init(int pkt_type)
-{
-    struct Packet *pkt = ssh_new_packet();
-    pkt->length = 5;
-    pkt->forcepad = 0;
-    ssh2_pkt_addbyte(pkt, (unsigned char) pkt_type);
-    return pkt;
+    ssh_pkt_adddata(pkt, &byte, 1);
 }
 static void ssh2_pkt_addbool(struct Packet *pkt, unsigned char value)
 {
-    ssh2_pkt_adddata(pkt, &value, 1);
+    ssh_pkt_adddata(pkt, &value, 1);
 }
-static void ssh2_pkt_adduint32(struct Packet *pkt, unsigned long value)
+static void ssh_pkt_adduint32(struct Packet *pkt, unsigned long value)
 {
     unsigned char x[4];
     PUT_32BIT(x, value);
-    ssh2_pkt_adddata(pkt, x, 4);
+    ssh_pkt_adddata(pkt, x, 4);
 }
-static void ssh2_pkt_addstring_start(struct Packet *pkt)
+static void ssh_pkt_addstring_start(struct Packet *pkt)
 {
-    ssh2_pkt_adduint32(pkt, 0);
+    ssh_pkt_adduint32(pkt, 0);
     pkt->savedpos = pkt->length;
 }
-static void ssh2_pkt_addstring_str(struct Packet *pkt, char *data)
+static void ssh_pkt_addstring_str(struct Packet *pkt, char *data)
 {
-    ssh2_pkt_adddata(pkt, data, strlen(data));
+    ssh_pkt_adddata(pkt, data, strlen(data));
     PUT_32BIT(pkt->data + pkt->savedpos - 4, pkt->length - pkt->savedpos);
 }
-static void ssh2_pkt_addstring_data(struct Packet *pkt, char *data, int len)
+static void ssh_pkt_addstring_data(struct Packet *pkt, char *data, int len)
 {
-    ssh2_pkt_adddata(pkt, data, len);
+    ssh_pkt_adddata(pkt, data, len);
     PUT_32BIT(pkt->data + pkt->savedpos - 4, pkt->length - pkt->savedpos);
 }
-static void ssh2_pkt_addstring(struct Packet *pkt, char *data)
+static void ssh_pkt_addstring(struct Packet *pkt, char *data)
 {
-    ssh2_pkt_addstring_start(pkt);
-    ssh2_pkt_addstring_str(pkt, data);
+    ssh_pkt_addstring_start(pkt);
+    ssh_pkt_addstring_str(pkt, data);
+}
+static void ssh1_pkt_addmp(struct Packet *pkt, Bignum b)
+{
+    int len = ssh1_bignum_length(b);
+    unsigned char *data = snewn(len, char);
+    (void) ssh1_write_bignum(data, b);
+    ssh_pkt_adddata(pkt, data, len);
+    sfree(data);
 }
 static unsigned char *ssh2_mpint_fmt(Bignum b, int *len)
 {
     unsigned char *p;
     int i, n = (bignum_bitcount(b) + 7) / 8;
     p = snewn(n + 1, unsigned char);
-    if (!p)
-	fatalbox("out of memory");
     p[0] = 0;
     for (i = 1; i <= n; i++)
 	p[i] = bignum_byte(b, n - i);
@@ -1644,13 +1668,42 @@ static void ssh2_pkt_addmp(struct Packet *pkt, Bignum b)
     unsigned char *p;
     int len;
     p = ssh2_mpint_fmt(b, &len);
-    ssh2_pkt_addstring_start(pkt);
-    ssh2_pkt_addstring_data(pkt, (char *)p, len);
+    ssh_pkt_addstring_start(pkt);
+    ssh_pkt_addstring_data(pkt, (char *)p, len);
     sfree(p);
 }
 
+static struct Packet *ssh1_pkt_init(int pkt_type)
+{
+    struct Packet *pkt = ssh_new_packet();
+    pkt->length = 4 + 8;	    /* space for length + max padding */
+    ssh_pkt_addbyte(pkt, pkt_type);
+    pkt->body = pkt->data + pkt->length;
+    return pkt;
+}
+
+/* For legacy code (SSH-1 and -2 packet construction used to be separate) */
+#define ssh2_pkt_ensure(pkt, length) ssh_pkt_ensure(pkt, length)
+#define ssh2_pkt_adddata(pkt, data, len) ssh_pkt_adddata(pkt, data, len)
+#define ssh2_pkt_addbyte(pkt, byte) ssh_pkt_addbyte(pkt, byte)
+#define ssh2_pkt_adduint32(pkt, value) ssh_pkt_adduint32(pkt, value)
+#define ssh2_pkt_addstring_start(pkt) ssh_pkt_addstring_start(pkt)
+#define ssh2_pkt_addstring_str(pkt, data) ssh_pkt_addstring_str(pkt, data)
+#define ssh2_pkt_addstring_data(pkt, data, len) ssh_pkt_addstring_data(pkt, data, len)
+#define ssh2_pkt_addstring(pkt, data) ssh_pkt_addstring(pkt, data)
+
+static struct Packet *ssh2_pkt_init(int pkt_type)
+{
+    struct Packet *pkt = ssh_new_packet();
+    pkt->length = 5;
+    pkt->forcepad = 0;
+    ssh_pkt_addbyte(pkt, (unsigned char) pkt_type);
+    pkt->body = pkt->data + pkt->length;
+    return pkt;
+}
+
 /*
- * Construct an SSH2 final-form packet: compress it, encrypt it,
+ * Construct an SSH-2 final-form packet: compress it, encrypt it,
  * put the MAC on it. Final packet, ready to be sent, is stored in
  * pkt->data. Total length is returned.
  */
@@ -1661,7 +1714,7 @@ static int ssh2_pkt_construct(Ssh ssh, struct Packet *pkt)
     if (ssh->logctx)
 	log_packet(ssh->logctx, PKT_OUTGOING, pkt->data[5],
 		   ssh2_pkt_type(ssh->pkt_ctx, pkt->data[5]),
-		   pkt->data + 6, pkt->length - 6,
+		   pkt->body, pkt->length - (pkt->body - pkt->data),
 		   pkt->nblanks, pkt->blanks);
     sfree(pkt->blanks); pkt->blanks = NULL;
     pkt->nblanks = 0;
@@ -1745,15 +1798,32 @@ static int ssh2_pkt_construct(Ssh ssh, struct Packet *pkt)
  * ssh2_pkt_send() or ssh2_pkt_defer() either go straight to one of
  * these or get queued, and then when the queue is later emptied
  * the packets are all passed to defer_noqueue().
+ *
+ * When using a CBC-mode cipher, it's necessary to ensure that an
+ * attacker can't provide data to be encrypted using an IV that they
+ * know.  We ensure this by prefixing each packet that might contain
+ * user data with an SSH_MSG_IGNORE.  This is done using the deferral
+ * mechanism, so in this case send_noqueue() ends up redirecting to
+ * defer_noqueue().  If you don't like this inefficiency, don't use
+ * CBC.
  */
 
+static void ssh2_pkt_defer_noqueue(Ssh, struct Packet *, int);
+static void ssh_pkt_defersend(Ssh);
+
 /*
- * Send an SSH2 packet immediately, without queuing or deferring.
+ * Send an SSH-2 packet immediately, without queuing or deferring.
  */
 static void ssh2_pkt_send_noqueue(Ssh ssh, struct Packet *pkt)
 {
     int len;
     int backlog;
+    if (ssh->cscipher != NULL && (ssh->cscipher->flags & SSH_CIPHER_IS_CBC)) {
+	/* We need to send two packets, so use the deferral mechanism. */
+	ssh2_pkt_defer_noqueue(ssh, pkt, FALSE);
+	ssh_pkt_defersend(ssh);
+	return;
+    }
     len = ssh2_pkt_construct(ssh, pkt);
     backlog = sk_write(ssh->s, (char *)pkt->data, len);
     if (backlog > SSH_MAX_BACKLOG)
@@ -1769,11 +1839,21 @@ static void ssh2_pkt_send_noqueue(Ssh ssh, struct Packet *pkt)
 }
 
 /*
- * Defer an SSH2 packet.
+ * Defer an SSH-2 packet.
  */
-static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt)
+static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt, int noignore)
 {
-    int len = ssh2_pkt_construct(ssh, pkt);
+    int len;
+    if (ssh->cscipher != NULL && (ssh->cscipher->flags & SSH_CIPHER_IS_CBC) &&
+	ssh->deferred_len == 0 && !noignore) {
+	/*
+	 * Interpose an SSH_MSG_IGNORE to ensure that user data don't
+	 * get encrypted with a known IV.
+	 */
+	struct Packet *ipkt = ssh2_pkt_init(SSH2_MSG_IGNORE);
+	ssh2_pkt_defer_noqueue(ssh, ipkt, TRUE);
+    }
+    len = ssh2_pkt_construct(ssh, pkt);
     if (ssh->deferred_len + len > ssh->deferred_size) {
 	ssh->deferred_size = ssh->deferred_len + len + 128;
 	ssh->deferred_send_data = sresize(ssh->deferred_send_data,
@@ -1787,7 +1867,7 @@ static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt)
 }
 
 /*
- * Queue an SSH2 packet.
+ * Queue an SSH-2 packet.
  */
 static void ssh2_pkt_queue(Ssh ssh, struct Packet *pkt)
 {
@@ -1823,13 +1903,13 @@ static void ssh2_pkt_defer(Ssh ssh, struct Packet *pkt)
     if (ssh->queueing)
 	ssh2_pkt_queue(ssh, pkt);
     else
-	ssh2_pkt_defer_noqueue(ssh, pkt);
+	ssh2_pkt_defer_noqueue(ssh, pkt, FALSE);
 }
 #endif
 
 /*
  * Send the whole deferred data block constructed by
- * ssh2_pkt_defer() or SSH1's defer_packet().
+ * ssh2_pkt_defer() or SSH-1's defer_packet().
  * 
  * The expected use of the defer mechanism is that you call
  * ssh2_pkt_defer() a few times, then call ssh_pkt_defersend(). If
@@ -1860,7 +1940,7 @@ static void ssh_pkt_defersend(Ssh ssh)
 }
 
 /*
- * Send all queued SSH2 packets. We send them by means of
+ * Send all queued SSH-2 packets. We send them by means of
  * ssh2_pkt_defer_noqueue(), in case they included a pair of
  * packets that needed to be lumped together.
  */
@@ -1871,7 +1951,7 @@ static void ssh2_pkt_queuesend(Ssh ssh)
     assert(!ssh->queueing);
 
     for (i = 0; i < ssh->queuelen; i++)
-	ssh2_pkt_defer_noqueue(ssh, ssh->queue[i]);
+	ssh2_pkt_defer_noqueue(ssh, ssh->queue[i], FALSE);
     ssh->queuelen = 0;
 
     ssh_pkt_defersend(ssh);
@@ -1901,7 +1981,7 @@ static void sha_mpint(SHA_State * s, Bignum b)
 }
 
 /*
- * Packet decode functions for both SSH1 and SSH2.
+ * Packet decode functions for both SSH-1 and SSH-2.
  */
 static unsigned long ssh_pkt_getuint32(struct Packet *pkt)
 {
@@ -1992,7 +2072,7 @@ static Bignum ssh2_pkt_getmp(struct Packet *pkt)
 }
 
 /*
- * Helper function to add an SSH2 signature blob to a packet.
+ * Helper function to add an SSH-2 signature blob to a packet.
  * Expects to be shown the public key blob as well as the signature
  * blob. Normally works just like ssh2_pkt_addstring, but will
  * fiddle with the signature packet if necessary for
@@ -2088,7 +2168,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 	 * sniffing.
 	 */
 	ssh->remote_bugs |= BUG_CHOKES_ON_SSH1_IGNORE;
-	logevent("We believe remote version has SSH1 ignore bug");
+	logevent("We believe remote version has SSH-1 ignore bug");
     }
 
     if (ssh->cfg.sshbug_plainpw1 == FORCE_ON ||
@@ -2100,7 +2180,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 	 * the password.
 	 */
 	ssh->remote_bugs |= BUG_NEEDS_SSH1_PLAIN_PASSWORD;
-	logevent("We believe remote version needs a plain SSH1 password");
+	logevent("We believe remote version needs a plain SSH-1 password");
     }
 
     if (ssh->cfg.sshbug_rsa1 == FORCE_ON ||
@@ -2112,7 +2192,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 	 * an AUTH_RSA message.
 	 */
 	ssh->remote_bugs |= BUG_CHOKES_ON_RSA;
-	logevent("We believe remote version can't handle RSA authentication");
+	logevent("We believe remote version can't handle SSH-1 RSA authentication");
     }
 
     if (ssh->cfg.sshbug_hmac2 == FORCE_ON ||
@@ -2125,7 +2205,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 	 * These versions have the HMAC bug.
 	 */
 	ssh->remote_bugs |= BUG_SSH2_HMAC;
-	logevent("We believe remote version has SSH2 HMAC bug");
+	logevent("We believe remote version has SSH-2 HMAC bug");
     }
 
     if (ssh->cfg.sshbug_derivekey2 == FORCE_ON ||
@@ -2138,7 +2218,7 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 	 * generate the keys).
 	 */
 	ssh->remote_bugs |= BUG_SSH2_DERIVEKEY;
-	logevent("We believe remote version has SSH2 key-derivation bug");
+	logevent("We believe remote version has SSH-2 key-derivation bug");
     }
 
     if (ssh->cfg.sshbug_rsapad2 == FORCE_ON ||
@@ -2146,34 +2226,36 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 	 (wc_match("OpenSSH_2.[5-9]*", imp) ||
 	  wc_match("OpenSSH_3.[0-2]*", imp)))) {
 	/*
-	 * These versions have the SSH2 RSA padding bug.
+	 * These versions have the SSH-2 RSA padding bug.
 	 */
 	ssh->remote_bugs |= BUG_SSH2_RSA_PADDING;
-	logevent("We believe remote version has SSH2 RSA padding bug");
+	logevent("We believe remote version has SSH-2 RSA padding bug");
     }
 
     if (ssh->cfg.sshbug_pksessid2 == FORCE_ON ||
 	(ssh->cfg.sshbug_pksessid2 == AUTO &&
 	 wc_match("OpenSSH_2.[0-2]*", imp))) {
 	/*
-	 * These versions have the SSH2 session-ID bug in
+	 * These versions have the SSH-2 session-ID bug in
 	 * public-key authentication.
 	 */
 	ssh->remote_bugs |= BUG_SSH2_PK_SESSIONID;
-	logevent("We believe remote version has SSH2 public-key-session-ID bug");
+	logevent("We believe remote version has SSH-2 public-key-session-ID bug");
     }
 
     if (ssh->cfg.sshbug_rekey2 == FORCE_ON ||
 	(ssh->cfg.sshbug_rekey2 == AUTO &&
-	 (wc_match("OpenSSH_2.[0-4]*", imp) ||
+	 (wc_match("DigiSSH_2.0", imp) ||
+	  wc_match("OpenSSH_2.[0-4]*", imp) ||
 	  wc_match("OpenSSH_2.5.[0-3]*", imp) ||
 	  wc_match("Sun_SSH_1.0", imp) ||
-	  wc_match("Sun_SSH_1.0.1", imp)))) {
+	  wc_match("Sun_SSH_1.0.1", imp) ||
+	  wc_match("WeOnlyDo-1.2.6", imp)))) {
 	/*
-	 * These versions have the SSH2 rekey bug.
+	 * These versions have the SSH-2 rekey bug.
 	 */
 	ssh->remote_bugs |= BUG_SSH2_REKEY;
-	logevent("We believe remote version has SSH2 rekey bug");
+	logevent("We believe remote version has SSH-2 rekey bug");
     }
 }
 
@@ -2214,23 +2296,20 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
 
     crBegin(ssh->do_ssh_init_crstate);
 
-    /* Search for the string "SSH-" in the input. */
-    s->i = 0;
-    while (1) {
-	static const int transS[] = { 1, 2, 2, 1 };
-	static const int transH[] = { 0, 0, 3, 0 };
-	static const int transminus[] = { 0, 0, 0, -1 };
-	if (c == 'S')
-	    s->i = transS[s->i];
-	else if (c == 'H')
-	    s->i = transH[s->i];
-	else if (c == '-')
-	    s->i = transminus[s->i];
-	else
-	    s->i = 0;
-	if (s->i < 0)
-	    break;
-	crReturn(1);		       /* get another character */
+    /* Search for a line beginning with the string "SSH-" in the input. */
+    for (;;) {
+	if (c != 'S') goto no;
+	crReturn(1);
+	if (c != 'S') goto no;
+	crReturn(1);
+	if (c != 'H') goto no;
+	crReturn(1);
+	if (c != '-') goto no;
+	break;
+      no:
+	while (c != '\012')
+	    crReturn(1);
+	crReturn(1);
     }
 
     s->vstrsize = 16;
@@ -2314,14 +2393,14 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
                        strcspn(s->vstring, "\015\012"));
 
             /*
-             * Initialise SSHv2 protocol.
+             * Initialise SSH-2 protocol.
              */
             ssh->protocol = ssh2_protocol;
             ssh2_protocol_setup(ssh);
             ssh->s_rdpkt = ssh2_rdpkt;
         } else {
             /*
-             * Initialise SSHv1 protocol.
+             * Initialise SSH-1 protocol.
              */
             ssh->protocol = ssh1_protocol;
             ssh1_protocol_setup(ssh);
@@ -2331,6 +2410,8 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
                   strcspn(verstring, "\015\012"), verstring);
 	sk_write(ssh->s, verstring, strlen(verstring));
         sfree(verstring);
+	if (ssh->version == 2)
+	    do_ssh2_transport(ssh, NULL, -1, NULL);
     }
 
     logeventf(ssh, "Using SSH protocol version %d", ssh->version);
@@ -2444,6 +2525,7 @@ static int ssh_do_close(Ssh ssh, int notify_exit)
     struct ssh_channel *c;
 
     ssh->state = SSH_STATE_CLOSED;
+    expire_timer_context(ssh);
     if (ssh->s) {
         sk_close(ssh->s);
         ssh->s = NULL;
@@ -2513,20 +2595,20 @@ static int ssh_closing(Plug plug, const char *error_msg, int error_code,
     Ssh ssh = (Ssh) plug;
     int need_notify = ssh_do_close(ssh, FALSE);
 
-    if (!error_msg && !ssh->close_expected) {
-        error_msg = "Server unexpectedly closed network connection";
+    if (!error_msg) {
+	if (!ssh->close_expected)
+	    error_msg = "Server unexpectedly closed network connection";
+	else
+	    error_msg = "Server closed network connection";
     }
 
     if (need_notify)
         notify_remote_exit(ssh->frontend);
 
-    if (error_msg) {
-	/* A socket error has occurred. */
+    if (error_msg)
 	logevent(error_msg);
+    if (!ssh->close_expected || !ssh->clean_exit)
 	connection_fatal(ssh->frontend, "%s", error_msg);
-    } else {
-        logevent("Server closed network connection");
-    }
     return 0;
 }
 
@@ -2573,8 +2655,6 @@ static const char *connect_to_host(Ssh ssh, char *host, int port,
     const char *err;
 
     ssh->savedhost = snewn(1 + strlen(host), char);
-    if (!ssh->savedhost)
-	fatalbox("Out of memory");
     strcpy(ssh->savedhost, host);
 
     if (port < 0)
@@ -2661,7 +2741,7 @@ static void ssh_throttle_all(Ssh ssh, int enable, int bufsize)
 
 /*
  * Username and password input, abstracted off into routines
- * reusable in several places - even between SSH1 and SSH2.
+ * reusable in several places - even between SSH-1 and SSH-2.
  */
 
 /* Set up a username or password input loop on a given buffer. */
@@ -2790,6 +2870,39 @@ static void ssh_agentf_callback(void *cv, void *reply, int replylen)
 }
 
 /*
+ * Client-initiated disconnection. Send a DISCONNECT if `wire_reason'
+ * non-NULL, otherwise just close the connection. `client_reason' == NULL
+ * => log `wire_reason'.
+ */
+static void ssh_disconnect(Ssh ssh, char *client_reason, char *wire_reason,
+			   int code, int clean_exit)
+{
+    char *error;
+    if (!client_reason)
+	client_reason = wire_reason;
+    if (client_reason)
+	error = dupprintf("Disconnected: %s", client_reason);
+    else
+	error = dupstr("Disconnected");
+    if (wire_reason) {
+	if (ssh->version == 1) {
+	    send_packet(ssh, SSH1_MSG_DISCONNECT, PKT_STR, wire_reason,
+			PKT_END);
+	} else if (ssh->version == 2) {
+	    struct Packet *pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
+	    ssh2_pkt_adduint32(pktout, code);
+	    ssh2_pkt_addstring(pktout, wire_reason);
+	    ssh2_pkt_addstring(pktout, "en");	/* language tag */
+	    ssh2_pkt_send_noqueue(ssh, pktout);
+	}
+    }
+    ssh->close_expected = TRUE;
+    ssh->clean_exit = clean_exit;
+    ssh_closing((Plug)ssh, error, 0, 0);
+    sfree(error);
+}
+
+/*
  * Handle the key exchange and user authentication phases.
  */
 static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
@@ -2841,14 +2954,14 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 
     ptr = ssh_pkt_getdata(pktin, 8);
     if (!ptr) {
-	bombout(("SSH1 public key packet stopped before random cookie"));
+	bombout(("SSH-1 public key packet stopped before random cookie"));
 	crStop(0);
     }
     memcpy(cookie, ptr, 8);
 
     if (!ssh1_pkt_getrsakey(pktin, &servkey, &s->keystr1) ||
 	!ssh1_pkt_getrsakey(pktin, &hostkey, &s->keystr2)) {	
-	bombout(("Failed to read SSH1 public keys from public key packet"));
+	bombout(("Failed to read SSH-1 public keys from public key packet"));
 	crStop(0);
     }
 
@@ -2887,15 +3000,13 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
      */
     if (hostkey.bits > hostkey.bytes * 8 ||
 	servkey.bits > servkey.bytes * 8) {
-	bombout(("SSH1 public keys were badly formatted"));
+	bombout(("SSH-1 public keys were badly formatted"));
 	crStop(0);
     }
 
     s->len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
 
     s->rsabuf = snewn(s->len, unsigned char);
-    if (!s->rsabuf)
-	fatalbox("Out of memory");
 
     /*
      * Verify the host key.
@@ -2907,8 +3018,6 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	int len = rsastr_len(&hostkey);
 	char fingerprint[100];
 	char *keystr = snewn(len, char);
-	if (!keystr)
-	    fatalbox("Out of memory");
 	rsastr_fmt(keystr, &hostkey);
 	rsa_fingerprint(fingerprint, sizeof(fingerprint), &hostkey);
 
@@ -2932,8 +3041,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
         ssh_set_frozen(ssh, 0);
 
         if (s->dlgret == 0) {
-            ssh->close_expected = TRUE;
-            ssh_closing((Plug)ssh, NULL, 0, 0);
+	    ssh_disconnect(ssh, "User aborted at host key verification",
+			   NULL, 0, TRUE);
 	    crStop(0);
         }
     }
@@ -2954,7 +3063,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	    ret = rsaencrypt(s->rsabuf, hostkey.bytes, &servkey);
     }
     if (!ret) {
-	bombout(("SSH1 public key encryptions failed due to bad formatting"));
+	bombout(("SSH-1 public key encryptions failed due to bad formatting"));
 	crStop(0);	
     }
 
@@ -2971,7 +3080,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		warn = 1;
 	    } else if (next_cipher == CIPHER_AES) {
 		/* XXX Probably don't need to mention this. */
-		logevent("AES not supported in SSH1, skipping");
+		logevent("AES not supported in SSH-1, skipping");
 	    } else {
 		switch (next_cipher) {
 		  case CIPHER_3DES:     s->cipher_type = SSH_CIPHER_3DES;
@@ -2987,7 +3096,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	}
 	if (!cipher_chosen) {
 	    if ((s->supported_ciphers_mask & (1 << SSH_CIPHER_3DES)) == 0)
-		bombout(("Server violates SSH 1 protocol by not "
+		bombout(("Server violates SSH-1 protocol by not "
 			 "supporting 3DES encryption"));
 	    else
 		/* shouldn't happen */
@@ -3013,8 +3122,8 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	    }
             ssh_set_frozen(ssh, 0);
 	    if (s->dlgret == 0) {
-		ssh->close_expected = TRUE;
-		ssh_closing((Plug)ssh, NULL, 0, 0);
+		ssh_disconnect(ssh, "User aborted at cipher warning", NULL,
+			       0, TRUE);
 		crStop(0);
 	    }
         }
@@ -3088,9 +3197,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		     * get_line failed to get a username.
 		     * Terminate.
 		     */
-		    logevent("No username provided. Abandoning session.");
-		    ssh->close_expected = TRUE;
-                    ssh_closing((Plug)ssh, NULL, 0, 0);
+		    ssh_disconnect(ssh, "No username provided", NULL, 0, TRUE);
 		    crStop(1);
 		}
 	    } else {
@@ -3177,7 +3284,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		s->p = s->response + 5;
 		s->nkeys = GET_32BIT(s->p);
 		s->p += 4;
-		logeventf(ssh, "Pageant has %d SSH1 keys", s->nkeys);
+		logeventf(ssh, "Pageant has %d SSH-1 keys", s->nkeys);
 		for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
 		    logeventf(ssh, "Trying Pageant key #%d", s->keyi);
 		    if (s->publickey_blob &&
@@ -3337,6 +3444,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		    bombout(("TIS challenge packet was badly formed"));
 		    crStop(0);
 		}
+		c_write_str(ssh, "Using TIS authentication.\r\n");
 		logevent("Received TIS challenge");
 		if (challengelen > sizeof(s->prompt) - 1)
 		    challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
@@ -3370,6 +3478,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		    bombout(("CryptoCard challenge packet was badly formed"));
 		    crStop(0);
 		}
+		c_write_str(ssh, "Using CryptoCard authentication.\r\n");
 		logevent("Received CryptoCard challenge");
 		if (challengelen > sizeof(s->prompt) - 1)
 		    challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
@@ -3425,13 +3534,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		 * because one was supplied on the command line
 		 * which has already failed to work). Terminate.
 		 */
-		send_packet(ssh, SSH1_MSG_DISCONNECT,
-			    PKT_STR, "No more passwords available to try",
-			    PKT_END);
-		logevent("Unable to authenticate");
-		connection_fatal(ssh->frontend, "Unable to authenticate");
-		ssh->close_expected = TRUE;
-                ssh_closing((Plug)ssh, NULL, 0, 0);
+		ssh_disconnect(ssh, NULL, "Unable to authenticate", 0, FALSE);
 		crStop(1);
 	    }
 	} else {
@@ -3682,10 +3785,8 @@ void sshfwd_close(struct ssh_channel *c)
 {
     Ssh ssh = c->ssh;
 
-    if (ssh->state != SSH_STATE_SESSION) {
-	assert(ssh->state == SSH_STATE_CLOSED);
+    if (ssh->state == SSH_STATE_CLOSED)
 	return;
-    }
 
     if (c && !c->closes) {
 	/*
@@ -3722,10 +3823,8 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
 {
     Ssh ssh = c->ssh;
 
-    if (ssh->state != SSH_STATE_SESSION) {
-	assert(ssh->state == SSH_STATE_CLOSED);
+    if (ssh->state == SSH_STATE_CLOSED)
 	return 0;
-    }
 
     if (ssh->version == 1) {
 	send_packet(ssh, SSH1_MSG_CHANNEL_DATA,
@@ -3734,7 +3833,7 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
 		    PKT_INT, len, PKT_DATA, buf, len,
 		    PKTT_OTHER, PKT_END);
 	/*
-	 * In SSH1 we can return 0 here - implying that forwarded
+	 * In SSH-1 we can return 0 here - implying that forwarded
 	 * connections are never individually throttled - because
 	 * the only circumstance that can cause throttling will be
 	 * the whole SSH connection backing up, in which case
@@ -3751,10 +3850,8 @@ void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
 {
     Ssh ssh = c->ssh;
 
-    if (ssh->state != SSH_STATE_SESSION) {
-	assert(ssh->state == SSH_STATE_CLOSED);
+    if (ssh->state == SSH_STATE_CLOSED)
 	return;
-    }
 
     if (ssh->version == 1) {
 	if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) {
@@ -3906,7 +4003,7 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 		portfwd_strptr++;
 		sports[n] = '\0';
 		if (ssh->version == 1 && type == 'R') {
-		    logeventf(ssh, "SSH1 cannot handle remote source address "
+		    logeventf(ssh, "SSH-1 cannot handle remote source address "
 			      "spec \"%s\"; ignoring", sports);
 		} else
 		    strcpy(saddr, sports);
@@ -4027,7 +4124,7 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 		if (ssh->version == 1) {
 		    /*
 		     * We cannot cancel listening ports on the
-		     * server side in SSH1! There's no message
+		     * server side in SSH-1! There's no message
 		     * to support it. Instead, we simply remove
 		     * the rportfwd record from the local end
 		     * so that any connections the server tries
@@ -4485,10 +4582,30 @@ static void ssh1_smsg_exit_status(Ssh ssh, struct Packet *pktin)
      * encrypted packet, we close the session once
      * we've sent EXIT_CONFIRMATION.
      */
-    ssh->close_expected = TRUE;
-    ssh_closing((Plug)ssh, NULL, 0, 0);
+    ssh_disconnect(ssh, NULL, NULL, 0, TRUE);
+}
+
+/* Helper function to deal with sending tty modes for REQUEST_PTY */
+static void ssh1_send_ttymode(void *data, char *mode, char *val)
+{
+    struct Packet *pktout = (struct Packet *)data;
+    int i = 0;
+    unsigned int arg = 0;
+    while (strcmp(mode, ssh_ttymodes[i].mode) != 0) i++;
+    if (i == lenof(ssh_ttymodes)) return;
+    switch (ssh_ttymodes[i].type) {
+      case TTY_OP_CHAR:
+	arg = ssh_tty_parse_specchar(val);
+	break;
+      case TTY_OP_BOOL:
+	arg = ssh_tty_parse_boolean(val);
+	break;
+    }
+    ssh2_pkt_addbyte(pktout, ssh_ttymodes[i].opcode);
+    ssh2_pkt_addbyte(pktout, arg);
 }
 
+
 static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
 			       struct Packet *pktin)
 {
@@ -4533,14 +4650,23 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
 	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);
+	/*
+	 * Note that while we blank the X authentication data here, we don't
+	 * take any special action to blank the start of an X11 channel,
+	 * so using MIT-MAGIC-COOKIE-1 and actually opening an X connection
+	 * without having session blanking enabled is likely to leak your
+	 * cookie into the log.
+	 */
 	if (ssh->v1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
 	    send_packet(ssh, SSH1_CMSG_X11_REQUEST_FORWARDING,
-			PKT_STR, proto, PKT_STR, data,
+			PKT_STR, proto,
+			PKTT_PASSWORD, PKT_STR, data, PKTT_OTHER,
 			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);
+			PKT_STR, proto,
+			PKTT_PASSWORD, PKT_STR, data, PKTT_OTHER, PKT_END);
 	}
 	do {
 	    crReturnV;
@@ -4562,19 +4688,26 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
     ssh->packet_dispatch[SSH1_MSG_PORT_OPEN] = ssh1_msg_port_open;
 
     if (!ssh->cfg.nopty) {
+	struct Packet *pkt;
 	/* Unpick the terminal-speed string. */
 	/* XXX perhaps we should allow no speeds to be sent. */
 	ssh->ospeed = 38400; ssh->ispeed = 38400; /* last-resort defaults */
 	sscanf(ssh->cfg.termspeed, "%d,%d", &ssh->ospeed, &ssh->ispeed);
 	/* Send the pty request. */
-	send_packet(ssh, SSH1_CMSG_REQUEST_PTY,
-		    PKT_STR, ssh->cfg.termtype,
-		    PKT_INT, ssh->term_height,
-		    PKT_INT, ssh->term_width,
-		    PKT_INT, 0, PKT_INT, 0, /* width,height in pixels */
-		    PKT_CHAR, 192, PKT_INT, ssh->ispeed, /* TTY_OP_ISPEED */
-		    PKT_CHAR, 193, PKT_INT, ssh->ospeed, /* TTY_OP_OSPEED */
-		    PKT_CHAR, 0, PKT_END);
+	pkt = ssh1_pkt_init(SSH1_CMSG_REQUEST_PTY);
+	ssh_pkt_addstring(pkt, ssh->cfg.termtype);
+	ssh_pkt_adduint32(pkt, ssh->term_height);
+	ssh_pkt_adduint32(pkt, ssh->term_width);
+	ssh_pkt_adduint32(pkt, 0); /* width in pixels */
+	ssh_pkt_adduint32(pkt, 0); /* height in pixels */
+	parse_ttymodes(ssh, ssh->cfg.ttymodes,
+		       ssh1_send_ttymode, (void *)pkt);
+	ssh_pkt_addbyte(pkt, SSH1_TTY_OP_ISPEED);
+	ssh_pkt_adduint32(pkt, ssh->ispeed);
+	ssh_pkt_addbyte(pkt, SSH1_TTY_OP_OSPEED);
+	ssh_pkt_adduint32(pkt, ssh->ospeed);
+	ssh_pkt_addbyte(pkt, SSH_TTY_OP_END);
+	s_wrpkt(ssh, pkt);
 	ssh->state = SSH_STATE_INTERMED;
 	do {
 	    crReturnV;
@@ -4616,7 +4749,7 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Start the shell or command.
      * 
-     * Special case: if the first-choice command is an SSH2
+     * Special case: if the first-choice command is an SSH-2
      * subsystem (hence not usable here) and the second choice
      * exists, we fall straight back to that.
      */
@@ -4681,7 +4814,7 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
 }
 
 /*
- * Handle the top-level SSH2 protocol.
+ * Handle the top-level SSH-2 protocol.
  */
 static void ssh1_msg_debug(Ssh ssh, struct Packet *pktin)
 {
@@ -4801,7 +4934,7 @@ static int first_in_commasep_string(char *needle, char *haystack, int haylen)
 
 
 /*
- * SSH2 key creation method.
+ * SSH-2 key creation method.
  */
 static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
 		       unsigned char *sessid, char chr,
@@ -4826,7 +4959,7 @@ static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
 }
 
 /*
- * Handle the SSH2 transport layer.
+ * Handle the SSH-2 transport layer.
  */
 static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 			     struct Packet *pktin)
@@ -4930,6 +5063,9 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	      case CIPHER_AES:
 		s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_aes;
 		break;
+	      case CIPHER_ARCFOUR:
+		s->preferred_ciphers[s->n_preferred_ciphers++] = &ssh2_arcfour;
+		break;
 	      case CIPHER_WARN:
 		/* Flag for later. Don't bother if it's the last in
 		 * the list. */
@@ -5221,8 +5357,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	    }
 	    ssh_set_frozen(ssh, 0);
 	    if (s->dlgret == 0) {
-		ssh->close_expected = TRUE;
-		ssh_closing((Plug)ssh, NULL, 0, 0);
+		ssh_disconnect(ssh, "User aborted at kex warning", NULL,
+			       0, TRUE);
 		crStop(0);
 	    }
 	}
@@ -5246,8 +5382,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	    }
 	    ssh_set_frozen(ssh, 0);
 	    if (s->dlgret == 0) {
-		ssh->close_expected = TRUE;
-		ssh_closing((Plug)ssh, NULL, 0, 0);
+		ssh_disconnect(ssh, "User aborted at cipher warning", NULL,
+			       0, TRUE);
 		crStop(0);
 	    }
 	}
@@ -5271,8 +5407,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	    }
 	    ssh_set_frozen(ssh, 0);
 	    if (s->dlgret == 0) {
-		ssh->close_expected = TRUE;
-		ssh_closing((Plug)ssh, NULL, 0, 0);
+		ssh_disconnect(ssh, "User aborted at cipher warning", NULL,
+			       0, TRUE);
 		crStop(0);
 	    }
 	}
@@ -5420,8 +5556,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
     }
     ssh_set_frozen(ssh, 0);
     if (s->dlgret == 0) {
-        ssh->close_expected = TRUE;
-        ssh_closing((Plug)ssh, NULL, 0, 0);
+	ssh_disconnect(ssh, "User aborted at host key verification", NULL,
+		       0, TRUE);
         crStop(0);
     }
     if (!s->got_session_id) {     /* don't bother logging this in rekeys */
@@ -5587,7 +5723,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      * it would only confuse the layer above.
      */
     if (s->activated_authconn) {
-	crReturn(1);
+	crReturn(0);
     }
     s->activated_authconn = TRUE;
 
@@ -5639,7 +5775,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 }
 
 /*
- * Add data to an SSH2 channel output buffer.
+ * Add data to an SSH-2 channel output buffer.
  */
 static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
 				  int len)
@@ -5648,7 +5784,7 @@ static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
 }
 
 /*
- * Attempt to send data on an SSH2 channel.
+ * Attempt to send data on an SSH-2 channel.
  */
 static int ssh2_try_send(struct ssh_channel *c)
 {
@@ -5681,8 +5817,34 @@ static int ssh2_try_send(struct ssh_channel *c)
     return bufchain_size(&c->v.v2.outbuffer);
 }
 
+static void ssh2_try_send_and_unthrottle(struct ssh_channel *c)
+{
+    int bufsize;
+    if (c->closes)
+	return;			       /* don't send on closing channels */
+    bufsize = ssh2_try_send(c);
+    if (bufsize == 0) {
+	switch (c->type) {
+	  case CHAN_MAINSESSION:
+	    /* stdin need not receive an unthrottle
+	     * notification since it will be polled */
+	    break;
+	  case CHAN_X11:
+	    x11_unthrottle(c->u.x11.s);
+	    break;
+	  case CHAN_AGENT:
+	    /* agent sockets are request/response and need no
+	     * buffer management */
+	    break;
+	  case CHAN_SOCKDATA:
+	    pfd_unthrottle(c->u.pfd.s);
+	    break;
+	}
+    }
+}
+
 /*
- * Potentially enlarge the window on an SSH2 channel.
+ * Potentially enlarge the window on an SSH-2 channel.
  */
 static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
 {
@@ -5719,8 +5881,10 @@ static void ssh2_msg_channel_window_adjust(Ssh ssh, struct Packet *pktin)
     unsigned i = ssh_pkt_getuint32(pktin);
     struct ssh_channel *c;
     c = find234(ssh->channels, &i, ssh_channelfind);
-    if (c && !c->closes)
+    if (c && !c->closes) {
 	c->v.v2.remwindow += ssh_pkt_getuint32(pktin);
+	ssh2_try_send_and_unthrottle(c);
+    }
 }
 
 static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
@@ -5874,12 +6038,10 @@ static void ssh2_msg_channel_close(Ssh ssh, struct Packet *pktin)
      * not running in -N mode.)
      */
     if (!ssh->cfg.ssh_no_shell && count234(ssh->channels) == 0) {
-	logevent("All channels closed. Disconnecting");
-#if 0
 	/*
 	 * We used to send SSH_MSG_DISCONNECT here,
 	 * because I'd believed that _every_ conforming
-	 * SSH2 connection had to end with a disconnect
+	 * SSH-2 connection had to end with a disconnect
 	 * being sent by at least one side; apparently
 	 * I was wrong and it's perfectly OK to
 	 * unceremoniously slam the connection shut
@@ -5887,14 +6049,7 @@ static void ssh2_msg_channel_close(Ssh ssh, struct Packet *pktin)
 	 * this is more polite than sending a
 	 * DISCONNECT. So now we don't.
 	 */
-	s->pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
-	ssh2_pkt_adduint32(s->pktout, SSH2_DISCONNECT_BY_APPLICATION);
-	ssh2_pkt_addstring(s->pktout, "All open channels closed");
-	ssh2_pkt_addstring(s->pktout, "en");	/* language tag */
-	ssh2_pkt_send_noqueue(ssh, s->pktout);
-#endif
-	ssh->close_expected = TRUE;
-	ssh_closing((Plug)ssh, NULL, 0, 0);
+	ssh_disconnect(ssh, "All channels closed", NULL, 0, TRUE);
     }
 }
 
@@ -5981,18 +6136,10 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
      */
     c = find234(ssh->channels, &localid, ssh_channelfind);
     if (!c) {
-	char buf[80];
-	sprintf(buf, "Received channel request for nonexistent"
-		" channel %d", localid);
-	logevent(buf);
-	pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
-	ssh2_pkt_adduint32(pktout, SSH2_DISCONNECT_BY_APPLICATION);
-	ssh2_pkt_addstring(pktout, buf);
-	ssh2_pkt_addstring(pktout, "en");	/* language tag */
-	ssh2_pkt_send_noqueue(ssh, pktout);
-	connection_fatal(ssh->frontend, "%s", buf);
-	ssh->close_expected = TRUE;
-	ssh_closing((Plug)ssh, NULL, 0, 0);
+	char *buf = dupprintf("Received channel request for nonexistent"
+			      " channel %d", localid);
+	ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
+	sfree(buf);
 	return;
     }
 
@@ -6202,7 +6349,7 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
 	    }
 	}
     } else if (typelen == 22 &&
-	       !memcmp(type, "auth-agent@openssh.com", 3)) {
+	       !memcmp(type, "auth-agent@openssh.com", 22)) {
 	if (!ssh->agentfwd_enabled)
 	    error = "Agent forwarding is not enabled";
 	else {
@@ -6242,7 +6389,42 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
 }
 
 /*
- * Handle the SSH2 userauth and connection layers.
+ * Buffer banner messages for later display at some convenient point.
+ */
+static void ssh2_msg_userauth_banner(Ssh ssh, struct Packet *pktin)
+{
+    /* Arbitrary limit to prevent unbounded inflation of buffer */
+    if (bufchain_size(&ssh->banner) <= 131072) {
+	char *banner = NULL;
+	int size = 0;
+	ssh_pkt_getstring(pktin, &banner, &size);
+	if (banner)
+	    bufchain_add(&ssh->banner, banner, size);
+    }
+}
+
+/* Helper function to deal with sending tty modes for "pty-req" */
+static void ssh2_send_ttymode(void *data, char *mode, char *val)
+{
+    struct Packet *pktout = (struct Packet *)data;
+    int i = 0;
+    unsigned int arg = 0;
+    while (strcmp(mode, ssh_ttymodes[i].mode) != 0) i++;
+    if (i == lenof(ssh_ttymodes)) return;
+    switch (ssh_ttymodes[i].type) {
+      case TTY_OP_CHAR:
+	arg = ssh_tty_parse_specchar(val);
+	break;
+      case TTY_OP_BOOL:
+	arg = ssh_tty_parse_boolean(val);
+	break;
+    }
+    ssh2_pkt_addbyte(pktout, ssh_ttymodes[i].opcode);
+    ssh2_pkt_adduint32(pktout, arg);
+}
+
+/*
+ * Handle the SSH-2 userauth and connection layers.
  */
 static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 			     struct Packet *pktin)
@@ -6262,6 +6444,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		AUTH_TYPE_KEYBOARD_INTERACTIVE,
 		AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET
 	} type;
+	int done_service_req;
 	int gotit, need_pw, can_pubkey, can_passwd, can_keyb_inter;
 	int tried_pubkey_config, tried_agent;
 	int kbd_inter_running, kbd_inter_refused;
@@ -6289,16 +6472,33 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 
     crBegin(ssh->do_ssh2_authconn_crstate);
 
-    /*
-     * Request userauth protocol, and await a response to it.
-     */
-    s->pktout = ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
-    ssh2_pkt_addstring(s->pktout, "ssh-userauth");
-    ssh2_pkt_send(ssh, s->pktout);
-    crWaitUntilV(pktin);
-    if (pktin->type != SSH2_MSG_SERVICE_ACCEPT) {
-	bombout(("Server refused user authentication protocol"));
-	crStopV;
+    s->done_service_req = FALSE;
+    s->we_are_in = FALSE;
+    if (!ssh->cfg.ssh_no_userauth) {
+	/*
+	 * Request userauth protocol, and await a response to it.
+	 */
+	s->pktout = ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
+	ssh2_pkt_addstring(s->pktout, "ssh-userauth");
+	ssh2_pkt_send(ssh, s->pktout);
+	crWaitUntilV(pktin);
+	if (pktin->type == SSH2_MSG_SERVICE_ACCEPT)
+	    s->done_service_req = TRUE;
+    }
+    if (!s->done_service_req) {
+	/*
+	 * Request connection protocol directly, without authentication.
+	 */
+	s->pktout = ssh2_pkt_init(SSH2_MSG_SERVICE_REQUEST);
+	ssh2_pkt_addstring(s->pktout, "ssh-connection");
+	ssh2_pkt_send(ssh, s->pktout);
+	crWaitUntilV(pktin);
+	if (pktin->type == SSH2_MSG_SERVICE_ACCEPT) {
+	    s->we_are_in = TRUE; /* no auth required */
+	} else {
+	    bombout(("Server refused service request"));
+	    crStopV;
+	}
     }
 
     /*
@@ -6327,7 +6527,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
      */
     s->username[0] = '\0';
     s->got_username = FALSE;
-    do {
+    bufchain_init(&ssh->banner);
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] =
+	ssh2_msg_userauth_banner;
+    while (!s->we_are_in) {
 	/*
 	 * Get a username.
 	 */
@@ -6345,9 +6548,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		     * get_line failed to get a username.
 		     * Terminate.
 		     */
-		    logevent("No username provided. Abandoning session.");
-		    ssh->close_expected = TRUE;
-                    ssh_closing((Plug)ssh, NULL, 0, 0);
+		    ssh_disconnect(ssh, "No username provided", NULL, 0, TRUE);
 		    crStopV;
 		}
 	    } else {
@@ -6427,9 +6628,14 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	     */
 	    if (!s->gotit)
 		crWaitUntilV(pktin);
-	    while (pktin->type == SSH2_MSG_USERAUTH_BANNER) {
-		char *banner;
-		int size;
+	    /*
+	     * Now is a convenient point to spew any banner material
+	     * that we've accumulated. (This should ensure that when
+	     * we exit the auth loop, we haven't any left to deal
+	     * with.)
+	     */
+	    {
+		int size = bufchain_size(&ssh->banner);
 		/*
 		 * Don't show the banner if we're operating in
 		 * non-verbose non-interactive mode. (It's probably
@@ -6438,12 +6644,13 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		 * the banner will screw up processing on the
 		 * output of (say) plink.)
 		 */
-		if (flags & (FLAG_VERBOSE | FLAG_INTERACTIVE)) {
-		    ssh_pkt_getstring(pktin, &banner, &size);
-		    if (banner)
-			c_write_untrusted(ssh, banner, size);
+		if (size && (flags & (FLAG_VERBOSE | FLAG_INTERACTIVE))) {
+		    char *banner = snewn(size, char);
+		    bufchain_fetch(&ssh->banner, banner, size);
+		    c_write_untrusted(ssh, banner, size);
+		    sfree(banner);
 		}
-		crWaitUntilV(pktin);
+		bufchain_clear(&ssh->banner);
 	    }
 	    if (pktin->type == SSH2_MSG_USERAUTH_SUCCESS) {
 		logevent("Access granted");
@@ -6589,7 +6796,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		    s->p = s->response + 5;
 		    s->nkeys = GET_32BIT(s->p);
 		    s->p += 4;
-		    logeventf(ssh, "Pageant has %d SSH2 keys", s->nkeys);
+		    logeventf(ssh, "Pageant has %d SSH-2 keys", s->nkeys);
 		    for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
 			void *vret;
 
@@ -6808,6 +7015,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		    continue;
 		}
 
+		c_write_str(ssh, "Using keyboard-interactive authentication.\r\n");
 		s->kbd_inter_running = TRUE;
 		s->curr_prompt = 0;
 	    }
@@ -6891,17 +7099,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 			 * command line which has already failed to
 			 * work). Terminate.
 			 */
-			s->pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
-			ssh2_pkt_adduint32(s->pktout,SSH2_DISCONNECT_BY_APPLICATION);
-			ssh2_pkt_addstring(s->pktout, "No more passwords available"
-					   " to try");
-			ssh2_pkt_addstring(s->pktout, "en");	/* language tag */
-			ssh2_pkt_send_noqueue(ssh, s->pktout);
-			logevent("Unable to authenticate");
-			connection_fatal(ssh->frontend,
-					 "Unable to authenticate");
-			ssh->close_expected = TRUE;
-                        ssh_closing((Plug)ssh, NULL, 0, 0);
+			ssh_disconnect(ssh, NULL, "Unable to authenticate",
+				       SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+				       FALSE);
 			crStopV;
 		    }
 		} else {
@@ -7052,27 +7252,18 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		}
 		s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
 	    } else {
-		c_write_str(ssh, "No supported authentication methods"
-			    " left to try!\r\n");
-		logevent("No supported authentications offered."
-			 " Disconnecting");
-		s->pktout = ssh2_pkt_init(SSH2_MSG_DISCONNECT);
-		ssh2_pkt_adduint32(s->pktout, SSH2_DISCONNECT_BY_APPLICATION);
-		ssh2_pkt_addstring(s->pktout, "No supported authentication"
-				   " methods available");
-		ssh2_pkt_addstring(s->pktout, "en");	/* language tag */
-		ssh2_pkt_send_noqueue(ssh, s->pktout);
-		ssh->close_expected = TRUE;
-                ssh_closing((Plug)ssh, NULL, 0, 0);
+		ssh_disconnect(ssh, NULL,
+			       "No supported authentication methods available",
+			       SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE,
+			       FALSE);
 		crStopV;
 	    }
 	}
-    } while (!s->we_are_in);
+    }
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] = NULL;
 
     /*
-     * Now we're authenticated for the connection protocol. The
-     * connection protocol will automatically have started at this
-     * point; there's no need to send SERVICE_REQUEST.
+     * Now the connection protocol has started, one way or another.
      */
 
     ssh->channels = newtree234(ssh_channelcmp);
@@ -7156,7 +7347,16 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	ssh2_pkt_addbool(s->pktout, 1);	       /* want reply */
 	ssh2_pkt_addbool(s->pktout, 0);	       /* many connections */
 	ssh2_pkt_addstring(s->pktout, proto);
+	/*
+	 * Note that while we blank the X authentication data here, we don't
+	 * take any special action to blank the start of an X11 channel,
+	 * so using MIT-MAGIC-COOKIE-1 and actually opening an X connection
+	 * without having session blanking enabled is likely to leak your
+	 * cookie into the log.
+	 */
+	dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
 	ssh2_pkt_addstring(s->pktout, data);
+	end_log_omission(ssh, s->pktout);
 	ssh2_pkt_adduint32(s->pktout, x11_get_screen_number(ssh->cfg.x11_display));
 	ssh2_pkt_send(ssh, s->pktout);
 
@@ -7225,9 +7425,11 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	ssh2_pkt_adduint32(s->pktout, 0);	       /* pixel width */
 	ssh2_pkt_adduint32(s->pktout, 0);	       /* pixel height */
 	ssh2_pkt_addstring_start(s->pktout);
-	ssh2_pkt_addbyte(s->pktout, 128);	       /* TTY_OP_ISPEED */
+	parse_ttymodes(ssh, ssh->cfg.ttymodes,
+		       ssh2_send_ttymode, (void *)s->pktout);
+	ssh2_pkt_addbyte(s->pktout, SSH2_TTY_OP_ISPEED);
 	ssh2_pkt_adduint32(s->pktout, ssh->ispeed);
-	ssh2_pkt_addbyte(s->pktout, 129);	       /* TTY_OP_OSPEED */
+	ssh2_pkt_addbyte(s->pktout, SSH2_TTY_OP_OSPEED);
 	ssh2_pkt_adduint32(s->pktout, ssh->ospeed);
 	ssh2_pkt_addstring_data(s->pktout, "\0", 1); /* TTY_OP_END */
 	ssh2_pkt_send(ssh, s->pktout);
@@ -7417,30 +7619,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	    /*
 	     * Try to send data on all channels if we can.
 	     */
-	    for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
-		int bufsize;
-		if (c->closes)
-		    continue;	       /* don't send on closing channels */
-		bufsize = ssh2_try_send(c);
-		if (bufsize == 0) {
-		    switch (c->type) {
-		      case CHAN_MAINSESSION:
-			/* stdin need not receive an unthrottle
-			 * notification since it will be polled */
-			break;
-		      case CHAN_X11:
-			x11_unthrottle(c->u.x11.s);
-			break;
-		      case CHAN_AGENT:
-			/* agent sockets are request/response and need no
-			 * buffer management */
-			break;
-		      case CHAN_SOCKDATA:
-			pfd_unthrottle(c->u.pfd.s);
-			break;
-		    }
-		}
-	    }
+	    for (i = 0; NULL != (c = index234(ssh->channels, i)); i++)
+		ssh2_try_send_and_unthrottle(c);
 	}
     }
 
@@ -7448,7 +7628,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 }
 
 /*
- * Handlers for SSH2 messages that might arrive at any moment.
+ * Handlers for SSH-2 messages that might arrive at any moment.
  */
 static void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
 {
@@ -7506,7 +7686,7 @@ static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
 }
 
 /*
- * Handle the top-level SSH2 protocol.
+ * Handle the top-level SSH-2 protocol.
  */
 static void ssh2_protocol_setup(Ssh ssh)
 {
@@ -7560,7 +7740,7 @@ static void ssh2_protocol_setup(Ssh ssh)
      * These special message types we install handlers for.
      */
     ssh->packet_dispatch[SSH2_MSG_DISCONNECT] = ssh2_msg_disconnect;
-    ssh->packet_dispatch[SSH2_MSG_IGNORE] = ssh_msg_ignore; /* shared with ssh1 */
+    ssh->packet_dispatch[SSH2_MSG_IGNORE] = ssh_msg_ignore; /* shared with SSH-1 */
     ssh->packet_dispatch[SSH2_MSG_DEBUG] = ssh2_msg_debug;
 }
 
@@ -7568,6 +7748,9 @@ static void ssh2_timer(void *ctx, long now)
 {
     Ssh ssh = (Ssh)ctx;
 
+    if (ssh->state == SSH_STATE_CLOSED)
+	return;
+
     if (!ssh->kex_in_progress && ssh->cfg.ssh_rekey_time != 0 &&
 	now - ssh->next_rekey >= 0) {
 	do_ssh2_transport(ssh, "timeout", -1, NULL);
@@ -7646,6 +7829,7 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->hostkey = NULL;
     ssh->exitcode = -1;
     ssh->close_expected = FALSE;
+    ssh->clean_exit = FALSE;
     ssh->state = SSH_STATE_PREPACKET;
     ssh->size_needed = FALSE;
     ssh->eof_needed = FALSE;
@@ -7823,7 +8007,8 @@ static void ssh_reconfig(void *handle, Config *cfg)
     unsigned long old_max_data_size;
 
     pinger_reconfig(ssh->pinger, &ssh->cfg, cfg);
-    ssh_setup_portfwd(ssh, cfg);
+    if (ssh->portfwds)
+	ssh_setup_portfwd(ssh, cfg);
 
     if (ssh->cfg.ssh_rekey_time != cfg->ssh_rekey_time &&
 	cfg->ssh_rekey_time != 0) {
@@ -7870,7 +8055,7 @@ static void ssh_reconfig(void *handle, Config *cfg)
 }
 
 /*
- * Called to send data down the Telnet connection.
+ * Called to send data down the SSH connection.
  */
 static int ssh_send(void *handle, char *buf, int len)
 {
@@ -8027,7 +8212,7 @@ static const struct telnet_special *ssh_get_specials(void *handle)
 }
 
 /*
- * Send Telnet special codes. TS_EOF is useful for `plink', so you
+ * Send special codes. TS_EOF is useful for `plink', so you
  * can send an EOF and collect resulting output (e.g. `plink
  * hostname sort').
  */
@@ -8052,6 +8237,7 @@ static void ssh_special(void *handle, Telnet_Special code)
 	    struct Packet *pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_EOF);
 	    ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
 	    ssh2_pkt_send(ssh, pktout);
+            ssh->send_ok = 0;          /* now stop trying to read from stdin */
 	}
 	logevent("Sent EOF message");
     } else if (code == TS_PING || code == TS_NOP) {
@@ -8073,7 +8259,7 @@ static void ssh_special(void *handle, Telnet_Special code)
 	if (ssh->state == SSH_STATE_CLOSED
 	    || ssh->state == SSH_STATE_PREPACKET) return;
 	if (ssh->version == 1) {
-	    logevent("Unable to send BREAK signal in SSH1");
+	    logevent("Unable to send BREAK signal in SSH-1");
 	} else if (ssh->mainchan) {
 	    pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
 	    ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);