X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/409bfa77661282152dc3d434d8107296f6af4ebc..eaf1e20af0294d79a176d2ac3b35fd4143163051:/ssh.c

diff --git a/ssh.c b/ssh.c
index ea4771cd..38eb2bbd 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,3 +1,7 @@
+/*
+ * SSH backend.
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
@@ -130,21 +134,21 @@
 
 static const char *const ssh2_disconnect_reasons[] = {
     NULL,
-    "SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT",
-    "SSH_DISCONNECT_PROTOCOL_ERROR",
-    "SSH_DISCONNECT_KEY_EXCHANGE_FAILED",
-    "SSH_DISCONNECT_HOST_AUTHENTICATION_FAILED",
-    "SSH_DISCONNECT_MAC_ERROR",
-    "SSH_DISCONNECT_COMPRESSION_ERROR",
-    "SSH_DISCONNECT_SERVICE_NOT_AVAILABLE",
-    "SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED",
-    "SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE",
-    "SSH_DISCONNECT_CONNECTION_LOST",
-    "SSH_DISCONNECT_BY_APPLICATION",
-    "SSH_DISCONNECT_TOO_MANY_CONNECTIONS",
-    "SSH_DISCONNECT_AUTH_CANCELLED_BY_USER",
-    "SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE",
-    "SSH_DISCONNECT_ILLEGAL_USER_NAME",
+    "host not allowed to connect",
+    "protocol error",
+    "key exchange failed",
+    "host authentication failed",
+    "MAC error",
+    "compression error",
+    "service not available",
+    "protocol version not supported",
+    "host key not verifiable",
+    "connection lost",
+    "by application",
+    "too many connections",
+    "auth cancelled by user",
+    "no more auth methods available",
+    "illegal user name",
 };
 
 #define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED     1	/* 0x1 */
@@ -166,6 +170,110 @@ 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 +364,6 @@ 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 +415,19 @@ 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 +443,18 @@ 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.
  */
 
@@ -362,36 +463,16 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 #define OUR_V2_WINSIZE 16384
 #define OUR_V2_MAXPKT 0x4000UL
 
+/* Maximum length of passwords/passphrases (arbitrary) */
+#define SSH_MAX_PASSWORD_LEN 100
+
 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_hmac_sha1, &ssh_hmac_sha1_96, &ssh_hmac_md5
 };
 const static struct ssh_mac *buggymacs[] = {
-    &ssh_sha1_buggy, &ssh_md5, &ssh_mac_none
+    &ssh_hmac_sha1_buggy, &ssh_hmac_sha1_96_buggy, &ssh_hmac_md5
 };
 
 static void *ssh_comp_none_init(void)
@@ -439,7 +520,7 @@ 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 +556,11 @@ 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 +572,15 @@ 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 +615,15 @@ 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
@@ -605,7 +686,8 @@ struct ssh_tag {
     const struct plug_function_table *fn;
     /* the above field _must_ be first in the structure */
 
-    SHA_State exhash, exhashbase;
+    char *v_c, *v_s;
+    void *exhash;
 
     Socket s;
 
@@ -630,7 +712,8 @@ struct ssh_tag {
     void *cs_comp_ctx, *sc_comp_ctx;
     const struct ssh_kex *kex;
     const struct ssh_signkey *hostkey;
-    unsigned char v2_session_id[20];
+    unsigned char v2_session_id[SSH2_KEX_MAX_HASH_LEN];
+    int v2_session_id_len;
     void *kex_ctx;
 
     char *savedhost;
@@ -647,6 +730,7 @@ struct ssh_tag {
     struct ssh_channel *mainchan;      /* primary session channel */
     int exitcode;
     int close_expected;
+    int clean_exit;
 
     tree234 *rportfwds, *portfwds;
 
@@ -674,13 +758,7 @@ struct ssh_tag {
      */
     int fallback_cmd;
 
-    /*
-     * Used for username and password input.
-     */
-    char *userpass_input_buffer;
-    int userpass_input_buflen;
-    int userpass_input_bufpos;
-    int userpass_input_echo;
+    bufchain banner;	/* accumulates banners during do_ssh2_authconn */
 
     int pkt_ctx;
 
@@ -710,7 +788,7 @@ 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,
@@ -726,10 +804,23 @@ struct ssh_tag {
     Config cfg;
 
     /*
-     * Used to transfer data back from async agent callbacks.
+     * Used to transfer data back from async callbacks.
      */
     void *agent_response;
     int agent_response_len;
+    int user_response;
+
+    /*
+     * The SSH connection can be set as `frozen', meaning we are
+     * not currently accepting incoming data from the network. This
+     * is slightly more serious than setting the _socket_ as
+     * frozen, because we may already have had data passed to us
+     * from the network which we need to delay processing until
+     * after the freeze is lifted, so we also need a bufchain to
+     * store that data.
+     */
+    int frozen;
+    bufchain queued_incoming_data;
 
     /*
      * Dispatch table for packet types that we may have to deal
@@ -802,6 +893,29 @@ 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;
@@ -932,27 +1046,28 @@ static int alloc_channel_id(Ssh ssh)
     return low + 1 + CHANNEL_NUMBER_OFFSET;
 }
 
+static void c_write_stderr(int trusted, const char *buf, int len)
+{
+    int i;
+    for (i = 0; i < len; i++)
+	if (buf[i] != '\r' && (trusted || buf[i] & 0x60))
+	    fputc(buf[i], stderr);
+}
+
 static void c_write(Ssh ssh, const char *buf, int len)
 {
-    if ((flags & FLAG_STDERR)) {
-	int i;
-	for (i = 0; i < len; i++)
-	    if (buf[i] != '\r')
-		fputc(buf[i], stderr);
-	return;
-    }
-    from_backend(ssh->frontend, 1, buf, len);
+    if (flags & FLAG_STDERR)
+	c_write_stderr(1, buf, len);
+    else
+	from_backend(ssh->frontend, 1, buf, len);
 }
 
 static void c_write_untrusted(Ssh ssh, const char *buf, int len)
 {
-    int i;
-    for (i = 0; i < len; i++) {
-	if (buf[i] == '\n')
-	    c_write(ssh, "\r\n", 2);
-	else if ((buf[i] & 0x60) || (buf[i] == '\r'))
-	    c_write(ssh, buf + i, 1);
-    }
+    if (flags & FLAG_STDERR)
+	c_write_stderr(0, buf, len);
+    else
+	from_backend_untrusted(ssh->frontend, buf, len);
 }
 
 static void c_write_str(Ssh ssh, const char *buf)
@@ -969,7 +1084,7 @@ 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;
@@ -1155,7 +1270,8 @@ 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);
@@ -1269,36 +1385,9 @@ 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__
     /*
@@ -1311,12 +1400,10 @@ 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;
@@ -1325,132 +1412,99 @@ 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:
@@ -1463,16 +1517,6 @@ 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;
@@ -1481,27 +1525,21 @@ 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)
@@ -1526,96 +1564,98 @@ static int ssh_versioncmp(char *a, char *b)
 
 /*
  * Utility routines for putting an SSH-protocol `string' and
- * `uint32' into a SHA state.
+ * `uint32' into a hash state.
  */
-#include <stdio.h>
-static void sha_string(SHA_State * s, void *str, int len)
+static void hash_string(const struct ssh_hash *h, void *s, void *str, int len)
 {
     unsigned char lenblk[4];
     PUT_32BIT(lenblk, len);
-    SHA_Bytes(s, lenblk, 4);
-    SHA_Bytes(s, str, len);
+    h->bytes(s, lenblk, 4);
+    h->bytes(s, str, len);
 }
 
-static void sha_uint32(SHA_State * s, unsigned i)
+static void hash_uint32(const struct ssh_hash *h, void *s, unsigned i)
 {
     unsigned char intblk[4];
     PUT_32BIT(intblk, i);
-    SHA_Bytes(s, intblk, 4);
+    h->bytes(s, intblk, 4);
 }
 
 /*
- * 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 ? body - pkt->data : 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);
@@ -1631,13 +1671,42 @@ 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; /* space for packet length + padding length */
+    pkt->forcepad = 0;
+    ssh_pkt_addbyte(pkt, (unsigned char) pkt_type);
+    pkt->body = pkt->data + pkt->length; /* after packet type */
+    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.
  */
@@ -1648,7 +1717,7 @@ 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;
@@ -1732,15 +1801,32 @@ 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)
@@ -1756,11 +1842,21 @@ 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,
@@ -1774,7 +1870,7 @@ 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)
 {
@@ -1810,13 +1906,13 @@ 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
@@ -1847,7 +1943,7 @@ 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.
  */
@@ -1858,7 +1954,7 @@ 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);
@@ -1878,17 +1974,17 @@ void bndebug(char *string, Bignum b)
 }
 #endif
 
-static void sha_mpint(SHA_State * s, Bignum b)
+static void hash_mpint(const struct ssh_hash *h, void *s, Bignum b)
 {
     unsigned char *p;
     int len;
     p = ssh2_mpint_fmt(b, &len);
-    sha_string(s, p, len);
+    hash_string(h, s, p, len);
     sfree(p);
 }
 
 /*
- * 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)
 {
@@ -1979,7 +2075,7 @@ 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
@@ -2075,7 +2171,7 @@ 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 ||
@@ -2087,7 +2183,7 @@ 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 ||
@@ -2099,7 +2195,7 @@ 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 ||
@@ -2112,7 +2208,7 @@ 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 ||
@@ -2125,7 +2221,7 @@ 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 ||
@@ -2133,34 +2229,37 @@ 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) ||
+	  /* All versions <= 1.2.6 (they changed their format in 1.2.7) */
+	  wc_match("WeOnlyDo-*", 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");
     }
 }
 
@@ -2201,23 +2300,20 @@ 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;
@@ -2247,13 +2343,7 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
 
     s->vstring[s->vslen] = 0;
     s->vstring[strcspn(s->vstring, "\015\012")] = '\0';/* remove EOL chars */
-    {
-	char *vlog;
-	vlog = snewn(20 + s->vslen, char);
-	sprintf(vlog, "Server version: %s", s->vstring);
-	logevent(vlog);
-	sfree(vlog);
-    }
+    logeventf(ssh, "Server version: %s", s->vstring);
     ssh_detect_bugs(ssh, s->vstring);
 
     /*
@@ -2297,24 +2387,28 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
         ssh_fix_verstring(verstring);
 
         if (ssh->version == 2) {
+	    size_t len;
             /*
              * Hash our version string and their version string.
              */
-            SHA_Init(&ssh->exhashbase);
-            sha_string(&ssh->exhashbase, verstring,
-                       strcspn(verstring, "\015\012"));
-            sha_string(&ssh->exhashbase, s->vstring,
-                       strcspn(s->vstring, "\015\012"));
-
+	    len = strcspn(verstring, "\015\012");
+	    ssh->v_c = snewn(len + 1, char);
+	    memcpy(ssh->v_c, verstring, len);
+	    ssh->v_c[len] = 0;
+	    len = strcspn(s->vstring, "\015\012");
+	    ssh->v_s = snewn(len + 1, char);
+	    memcpy(ssh->v_s, s->vstring, len);
+	    ssh->v_s[len] = 0;
+	    
             /*
-             * 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);
@@ -2324,6 +2418,8 @@ 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);
@@ -2337,6 +2433,50 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
     crFinish(0);
 }
 
+static void ssh_process_incoming_data(Ssh ssh,
+				      unsigned char **data, int *datalen)
+{
+    struct Packet *pktin = ssh->s_rdpkt(ssh, data, datalen);
+    if (pktin) {
+	ssh->protocol(ssh, NULL, 0, pktin);
+	ssh_free_packet(pktin);
+    }
+}
+
+static void ssh_queue_incoming_data(Ssh ssh,
+				    unsigned char **data, int *datalen)
+{
+    bufchain_add(&ssh->queued_incoming_data, *data, *datalen);
+    *data += *datalen;
+    *datalen = 0;
+}
+
+static void ssh_process_queued_incoming_data(Ssh ssh)
+{
+    void *vdata;
+    unsigned char *data;
+    int len, origlen;
+
+    while (!ssh->frozen && bufchain_size(&ssh->queued_incoming_data)) {
+	bufchain_prefix(&ssh->queued_incoming_data, &vdata, &len);
+	data = vdata;
+	origlen = len;
+
+	while (!ssh->frozen && len > 0)
+	    ssh_process_incoming_data(ssh, &data, &len);
+
+	if (origlen > len)
+	    bufchain_consume(&ssh->queued_incoming_data, origlen - len);
+    }
+}
+
+static void ssh_set_frozen(Ssh ssh, int frozen)
+{
+    if (ssh->s)
+	sk_set_frozen(ssh->s, frozen);
+    ssh->frozen = frozen;
+}
+
 static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
 {
     crBegin(ssh->ssh_gotdata_crstate);
@@ -2364,18 +2504,29 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
      * everything to s_rdpkt, and then pass the resulting packets
      * to the proper protocol handler.
      */
-    if (datalen == 0)
-	crReturnV;
+
     while (1) {
-	while (datalen > 0) {
-	    struct Packet *pktin = ssh->s_rdpkt(ssh, &data, &datalen);
-	    if (pktin) {
-		ssh->protocol(ssh, NULL, 0, pktin);
-		ssh_free_packet(pktin);
+	while (bufchain_size(&ssh->queued_incoming_data) > 0 || datalen > 0) {
+	    if (ssh->frozen) {
+		ssh_queue_incoming_data(ssh, &data, &datalen);
+		/* This uses up all data and cannot cause anything interesting
+		 * to happen; indeed, for anything to happen at all, we must
+		 * return, so break out. */
+		break;
+	    } else if (bufchain_size(&ssh->queued_incoming_data) > 0) {
+		/* This uses up some or all data, and may freeze the
+		 * session. */
+		ssh_process_queued_incoming_data(ssh);
+	    } else {
+		/* This uses up some or all data, and may freeze the
+		 * session. */
+		ssh_process_incoming_data(ssh, &data, &datalen);
 	    }
+	    /* FIXME this is probably EBW. */
 	    if (ssh->state == SSH_STATE_CLOSED)
 		return;
 	}
+	/* We're out of data. Go and get some more. */
 	crReturnV;
     }
     crFinishV;
@@ -2383,10 +2534,11 @@ static void ssh_gotdata(Ssh ssh, unsigned char *data, int datalen)
 
 static int ssh_do_close(Ssh ssh, int notify_exit)
 {
-    int i, ret = 0;
+    int ret = 0;
     struct ssh_channel *c;
 
     ssh->state = SSH_STATE_CLOSED;
+    expire_timer_context(ssh);
     if (ssh->s) {
         sk_close(ssh->s);
         ssh->s = NULL;
@@ -2396,11 +2548,11 @@ static int ssh_do_close(Ssh ssh, int notify_exit)
             ret = 1;
     }
     /*
-     * Now we must shut down any port and X forwardings going
+     * Now we must shut down any port- and X-forwarded channels going
      * through this connection.
      */
     if (ssh->channels) {
-	for (i = 0; NULL != (c = index234(ssh->channels, i)); i++) {
+	while (NULL != (c = index234(ssh->channels, 0))) {
 	    switch (c->type) {
 	      case CHAN_X11:
 		x11_close(c->u.x11.s);
@@ -2409,12 +2561,26 @@ static int ssh_do_close(Ssh ssh, int notify_exit)
 		pfd_close(c->u.pfd.s);
 		break;
 	    }
-	    del234(ssh->channels, c);
+	    del234(ssh->channels, c); /* moving next one to index 0 */
 	    if (ssh->version == 2)
 		bufchain_clear(&c->v.v2.outbuffer);
 	    sfree(c);
 	}
     }
+    /*
+     * Go through port-forwardings, and close any associated
+     * listening sockets.
+     */
+    if (ssh->portfwds) {
+	struct ssh_portfwd *pf;
+	while (NULL != (pf = index234(ssh->portfwds, 0))) {
+	    /* Dispose of any listening socket. */
+	    if (pf->local)
+		pfd_terminate(pf->local);
+	    del234(ssh->portfwds, pf); /* moving next one to index 0 */
+	    free_portfwd(pf);
+	}
+    }
 
     return ret;
 }
@@ -2433,6 +2599,7 @@ static void ssh_log(Plug plug, int type, SockAddr addr, int port,
 	msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);
 
     logevent(msg);
+    sfree(msg);
 }
 
 static int ssh_closing(Plug plug, const char *error_msg, int error_code,
@@ -2441,19 +2608,20 @@ 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 (error_msg) {
-	/* A socket error has occurred. */
-	logevent(error_msg);
-	connection_fatal(ssh->frontend, "%s", error_msg);
-    } else {
-        logevent("Server closed network connection");
-    }
     if (need_notify)
         notify_remote_exit(ssh->frontend);
+
+    if (error_msg)
+	logevent(error_msg);
+    if (!ssh->close_expected || !ssh->clean_exit)
+	connection_fatal(ssh->frontend, "%s", error_msg);
     return 0;
 }
 
@@ -2500,8 +2668,6 @@ 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)
@@ -2545,9 +2711,9 @@ static void ssh1_throttle(Ssh ssh, int adjust)
     ssh->v1_throttle_count += adjust;
     assert(ssh->v1_throttle_count >= 0);
     if (ssh->v1_throttle_count && !old_count) {
-	sk_set_frozen(ssh->s, 1);
+	ssh_set_frozen(ssh, 1);
     } else if (!ssh->v1_throttle_count && old_count) {
-	sk_set_frozen(ssh->s, 0);
+	ssh_set_frozen(ssh, 0);
     }
 }
 
@@ -2586,89 +2752,35 @@ 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.
- */
-
-/* Set up a username or password input loop on a given buffer. */
-static void setup_userpass_input(Ssh ssh, char *buffer, int buflen, int echo)
+static void ssh_agent_callback(void *sshv, void *reply, int replylen)
 {
-    ssh->userpass_input_buffer = buffer;
-    ssh->userpass_input_buflen = buflen;
-    ssh->userpass_input_bufpos = 0;
-    ssh->userpass_input_echo = echo;
-}
+    Ssh ssh = (Ssh) sshv;
 
-/*
- * Process some terminal data in the course of username/password
- * input. Returns >0 for success (line of input returned in
- * buffer), <0 for failure (user hit ^C/^D, bomb out and exit), 0
- * for inconclusive (keep waiting for more input please).
- */
-static int process_userpass_input(Ssh ssh, unsigned char *in, int inlen)
-{
-    char c;
+    ssh->agent_response = reply;
+    ssh->agent_response_len = replylen;
 
-    while (inlen--) {
-	switch (c = *in++) {
-	  case 10:
-	  case 13:
-	    ssh->userpass_input_buffer[ssh->userpass_input_bufpos] = 0;
-	    ssh->userpass_input_buffer[ssh->userpass_input_buflen-1] = 0;
-	    return +1;
-	    break;
-	  case 8:
-	  case 127:
-	    if (ssh->userpass_input_bufpos > 0) {
-		if (ssh->userpass_input_echo)
-		    c_write_str(ssh, "\b \b");
-		ssh->userpass_input_bufpos--;
-	    }
-	    break;
-	  case 21:
-	  case 27:
-	    while (ssh->userpass_input_bufpos > 0) {
-		if (ssh->userpass_input_echo)
-		    c_write_str(ssh, "\b \b");
-		ssh->userpass_input_bufpos--;
-	    }
-	    break;
-	  case 3:
-	  case 4:
-	    return -1;
-	    break;
-	  default:
-	    /*
-	     * 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;
-		if (ssh->userpass_input_echo)
-		    c_write(ssh, &c, 1);
-	    }
-	    break;
-	}
-    }
-    return 0;
+    if (ssh->version == 1)
+	do_ssh1_login(ssh, NULL, -1, NULL);
+    else
+	do_ssh2_authconn(ssh, NULL, -1, NULL);
 }
 
-static void ssh_agent_callback(void *sshv, void *reply, int replylen)
+static void ssh_dialog_callback(void *sshv, int ret)
 {
     Ssh ssh = (Ssh) sshv;
 
-    ssh->agent_response = reply;
-    ssh->agent_response_len = replylen;
+    ssh->user_response = ret;
 
     if (ssh->version == 1)
 	do_ssh1_login(ssh, NULL, -1, NULL);
     else
-	do_ssh2_authconn(ssh, NULL, -1, NULL);
+	do_ssh2_transport(ssh, NULL, -1, NULL);
+
+    /*
+     * This may have unfrozen the SSH connection, so do a
+     * queued-data run.
+     */
+    ssh_process_queued_incoming_data(ssh);
 }
 
 static void ssh_agentf_callback(void *cv, void *reply, int replylen)
@@ -2699,6 +2811,39 @@ 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,
@@ -2719,9 +2864,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	char username[100];
 	void *publickey_blob;
 	int publickey_bloblen;
-	char password[100];
-	char prompt[200];
-	int pos;
+	char *publickey_comment;
+	int publickey_encrypted;
+	prompts_t *cur_prompt;
 	char c;
 	int pwpkt_type;
 	unsigned char request[5], *response, *p;
@@ -2732,6 +2877,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	Bignum challenge;
 	char *commentp;
 	int commentlen;
+        int dlgret;
     };
     crState(do_ssh1_login_state);
 
@@ -2749,14 +2895,14 @@ 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);
     }
 
@@ -2795,15 +2941,13 @@ 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.
@@ -2815,14 +2959,33 @@ 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);
-	verify_ssh_host_key(ssh->frontend,
-			    ssh->savedhost, ssh->savedport, "rsa", keystr,
-			    fingerprint);
+
+        ssh_set_frozen(ssh, 1);
+	s->dlgret = verify_ssh_host_key(ssh->frontend,
+                                        ssh->savedhost, ssh->savedport,
+                                        "rsa", keystr, fingerprint,
+                                        ssh_dialog_callback, ssh);
 	sfree(keystr);
+        if (s->dlgret < 0) {
+            do {
+                crReturn(0);
+                if (pktin) {
+                    bombout(("Unexpected data from server while waiting"
+                             " for user host key response"));
+                    crStop(0);
+                }
+            } while (pktin || inlen > 0);
+            s->dlgret = ssh->user_response;
+        }
+        ssh_set_frozen(ssh, 0);
+
+        if (s->dlgret == 0) {
+	    ssh_disconnect(ssh, "User aborted at host key verification",
+			   NULL, 0, TRUE);
+	    crStop(0);
+        }
     }
 
     for (i = 0; i < 32; i++) {
@@ -2841,7 +3004,7 @@ 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);	
     }
 
@@ -2858,7 +3021,7 @@ 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;
@@ -2874,7 +3037,7 @@ 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 */
@@ -2884,9 +3047,26 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 
 	/* Warn about chosen cipher if necessary. */
 	if (warn) {
-            sk_set_frozen(ssh->s, 1);
-	    askalg(ssh->frontend, "cipher", cipher_string);
-            sk_set_frozen(ssh->s, 0);
+            ssh_set_frozen(ssh, 1);
+	    s->dlgret = askalg(ssh->frontend, "cipher", cipher_string,
+			       ssh_dialog_callback, ssh);
+	    if (s->dlgret < 0) {
+		do {
+		    crReturn(0);
+		    if (pktin) {
+			bombout(("Unexpected data from server while waiting"
+				 " for user response"));
+			crStop(0);
+		    }
+		} while (pktin || inlen > 0);
+		s->dlgret = ssh->user_response;
+	    }
+            ssh_set_frozen(ssh, 0);
+	    if (s->dlgret == 0) {
+		ssh_disconnect(ssh, "User aborted at cipher warning", NULL,
+			       0, TRUE);
+		crStop(0);
+	    }
         }
     }
 
@@ -2948,35 +3128,33 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 
     logevent("Successfully started encryption");
 
-    fflush(stdout);
+    fflush(stdout); /* FIXME eh? */
     {
 	if (!*ssh->cfg.username) {
-	    if (ssh_get_line && !ssh_getline_pw_only) {
-		if (!ssh_get_line("login as: ",
-				  s->username, sizeof(s->username), FALSE)) {
-		    /*
-		     * 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);
-		    crStop(1);
-		}
-	    } else {
-		int ret;	       /* need not be kept over crReturn */
-		c_write_str(ssh, "login as: ");
+	    int ret; /* need not be kept over crReturn */
+	    s->cur_prompt = new_prompts(ssh->frontend);
+	    s->cur_prompt->to_server = TRUE;
+	    s->cur_prompt->name = dupstr("SSH login name");
+	    add_prompt(s->cur_prompt, dupstr("login as: "), TRUE,
+		       lenof(s->username)); 
+	    ret = get_userpass_input(s->cur_prompt, NULL, 0);
+	    while (ret < 0) {
 		ssh->send_ok = 1;
-
-		setup_userpass_input(ssh, s->username, sizeof(s->username), 1);
-		do {
-		    crWaitUntil(!pktin);
-		    ret = process_userpass_input(ssh, in, inlen);
-		} while (ret == 0);
-		if (ret < 0)
-		    cleanup_exit(0);
-		c_write_str(ssh, "\r\n");
+		crWaitUntil(!pktin);
+		ret = get_userpass_input(s->cur_prompt, in, inlen);
+		ssh->send_ok = 0;
 	    }
+	    if (!ret) {
+		/*
+		 * Failed to get a username. Terminate.
+		 */
+		free_prompts(s->cur_prompt);
+		ssh_disconnect(ssh, "No username provided", NULL, 0, TRUE);
+		crStop(0);
+	    }
+	    memcpy(s->username, s->cur_prompt->prompts[0]->result,
+		   lenof(s->username));
+	    free_prompts(s->cur_prompt);
 	} else {
 	    strncpy(s->username, ssh->cfg.username, sizeof(s->username));
 	    s->username[sizeof(s->username)-1] = '\0';
@@ -2984,14 +3162,14 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 
 	send_packet(ssh, SSH1_CMSG_USER, PKT_STR, s->username, PKT_END);
 	{
-	    char userlog[22 + sizeof(s->username)];
-	    sprintf(userlog, "Sent username \"%s\"", s->username);
+	    char *userlog = dupprintf("Sent username \"%s\"", s->username);
 	    logevent(userlog);
 	    if (flags & FLAG_INTERACTIVE &&
 		(!((flags & FLAG_STDERR) && (flags & FLAG_VERBOSE)))) {
-		strcat(userlog, "\r\n");
 		c_write_str(ssh, userlog);
+		c_write_str(ssh, "\r\n");
 	    }
+	    sfree(userlog);
 	}
     }
 
@@ -3004,18 +3182,51 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	s->tried_publickey = s->tried_agent = 0;
     }
     s->tis_auth_refused = s->ccard_auth_refused = 0;
-    /* Load the public half of ssh->cfg.keyfile so we notice if it's in Pageant */
+    /*
+     * Load the public half of any configured keyfile for later use.
+     */
     if (!filename_is_null(ssh->cfg.keyfile)) {
-	if (!rsakey_pubblob(&ssh->cfg.keyfile,
-			    &s->publickey_blob, &s->publickey_bloblen, NULL))
+	int keytype;
+	logeventf(ssh, "Reading private key file \"%.150s\"",
+		  filename_to_str(&ssh->cfg.keyfile));
+	keytype = key_type(&ssh->cfg.keyfile);
+	if (keytype == SSH_KEYTYPE_SSH1) {
+	    const char *error;
+	    if (rsakey_pubblob(&ssh->cfg.keyfile,
+			       &s->publickey_blob, &s->publickey_bloblen,
+			       &s->publickey_comment, &error)) {
+		s->publickey_encrypted = rsakey_encrypted(&ssh->cfg.keyfile,
+							  NULL);
+	    } else {
+		char *msgbuf;
+		logeventf(ssh, "Unable to load private key (%s)", error);
+		msgbuf = dupprintf("Unable to load private key file "
+				   "\"%.150s\" (%s)\r\n",
+				   filename_to_str(&ssh->cfg.keyfile),
+				   error);
+		c_write_str(ssh, msgbuf);
+		sfree(msgbuf);
+		s->publickey_blob = NULL;
+	    }
+	} else {
+	    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
 	s->publickey_blob = NULL;
 
     while (pktin->type == SSH1_SMSG_FAILURE) {
 	s->pwpkt_type = SSH1_CMSG_AUTH_PASSWORD;
 
-	if (agent_exists() && !s->tried_agent) {
+	if (ssh->cfg.tryagent && agent_exists() && !s->tried_agent) {
 	    /*
 	     * Attempt RSA authentication using Pageant.
 	     */
@@ -3047,23 +3258,9 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		s->p = s->response + 5;
 		s->nkeys = GET_32BIT(s->p);
 		s->p += 4;
-		{
-		    char buf[64];
-		    sprintf(buf, "Pageant has %d SSH1 keys", s->nkeys);
-		    logevent(buf);
-		}
+		logeventf(ssh, "Pageant has %d SSH-1 keys", s->nkeys);
 		for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
-		    {
-			char buf[64];
-			sprintf(buf, "Trying Pageant key #%d", s->keyi);
-			logevent(buf);
-		    }
-		    if (s->publickey_blob &&
-			!memcmp(s->p, s->publickey_blob,
-				s->publickey_bloblen)) {
-			logevent("This key matches configured key file");
-			s->tried_publickey = 1;
-		    }
+		    unsigned char *pkblob = s->p;
 		    s->p += 4;
 		    {
 			int n, ok = FALSE;
@@ -3096,6 +3293,17 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 			    break;
 			}
 		    }
+		    if (s->publickey_blob) {
+			if (!memcmp(pkblob, s->publickey_blob,
+				    s->publickey_bloblen)) {
+			    logeventf(ssh, "Pageant key #%d matches "
+				      "configured key file", s->keyi);
+			    s->tried_publickey = 1;
+			} else
+			    /* Skip non-configured key */
+			    continue;
+		    }
+		    logeventf(ssh, "Trying Pageant key #%d", s->keyi);
 		    send_packet(ssh, SSH1_CMSG_AUTH_RSA,
 				PKT_BIGNUM, s->key.modulus, PKT_END);
 		    crWaitUntil(pktin);
@@ -3186,12 +3394,155 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 			break;
 		}
 		sfree(s->response);
+		if (s->publickey_blob && !s->tried_publickey)
+		    logevent("Configured key file not in Pageant");
 	    }
 	    if (s->authed)
 		break;
 	}
-	if (!filename_is_null(ssh->cfg.keyfile) && !s->tried_publickey)
-	    s->pwpkt_type = SSH1_CMSG_AUTH_RSA;
+	if (s->publickey_blob && !s->tried_publickey) {
+	    /*
+	     * Try public key authentication with the specified
+	     * key file.
+	     */
+	    int got_passphrase; /* need not be kept over crReturn */
+	    if (flags & FLAG_VERBOSE)
+		c_write_str(ssh, "Trying public key authentication.\r\n");
+	    logeventf(ssh, "Trying public key \"%s\"",
+		      filename_to_str(&ssh->cfg.keyfile));
+	    s->tried_publickey = 1;
+	    got_passphrase = FALSE;
+	    while (!got_passphrase) {
+		/*
+		 * Get a passphrase, if necessary.
+		 */
+		char *passphrase = NULL;    /* only written after crReturn */
+		const char *error;
+		if (!s->publickey_encrypted) {
+		    if (flags & FLAG_VERBOSE)
+			c_write_str(ssh, "No passphrase required.\r\n");
+		    passphrase = NULL;
+		} else {
+		    int ret; /* need not be kept over crReturn */
+		    s->cur_prompt = new_prompts(ssh->frontend);
+		    s->cur_prompt->to_server = FALSE;
+		    s->cur_prompt->name = dupstr("SSH key passphrase");
+		    add_prompt(s->cur_prompt,
+			       dupprintf("Passphrase for key \"%.100s\": ",
+					 s->publickey_comment),
+			       FALSE, SSH_MAX_PASSWORD_LEN);
+		    ret = get_userpass_input(s->cur_prompt, NULL, 0);
+		    while (ret < 0) {
+			ssh->send_ok = 1;
+			crWaitUntil(!pktin);
+			ret = get_userpass_input(s->cur_prompt, in, inlen);
+			ssh->send_ok = 0;
+		    }
+		    if (!ret) {
+			/* Failed to get a passphrase. Terminate. */
+			free_prompts(s->cur_prompt);
+			ssh_disconnect(ssh, NULL, "Unable to authenticate",
+				       0, TRUE);
+			crStop(0);
+		    }
+		    passphrase = dupstr(s->cur_prompt->prompts[0]->result);
+		    free_prompts(s->cur_prompt);
+		}
+		/*
+		 * Try decrypting key with passphrase.
+		 */
+		ret = loadrsakey(&ssh->cfg.keyfile, &s->key, passphrase,
+				 &error);
+		if (passphrase) {
+		    memset(passphrase, 0, strlen(passphrase));
+		    sfree(passphrase);
+		}
+		if (ret == 1) {
+		    /* Correct passphrase. */
+		    got_passphrase = TRUE;
+		} else if (ret == 0) {
+		    c_write_str(ssh, "Couldn't load private key from ");
+		    c_write_str(ssh, filename_to_str(&ssh->cfg.keyfile));
+		    c_write_str(ssh, " (");
+		    c_write_str(ssh, error);
+		    c_write_str(ssh, ").\r\n");
+		    got_passphrase = FALSE;
+		    break;	       /* go and try something else */
+		} else if (ret == -1) {
+		    c_write_str(ssh, "Wrong passphrase.\r\n"); /* FIXME */
+		    got_passphrase = FALSE;
+		    /* and try again */
+		} else {
+		    assert(0 && "unexpected return from loadrsakey()");
+		}
+	    }
+
+	    if (got_passphrase) {
+
+		/*
+		 * Send a public key attempt.
+		 */
+		send_packet(ssh, SSH1_CMSG_AUTH_RSA,
+			    PKT_BIGNUM, s->key.modulus, PKT_END);
+
+		crWaitUntil(pktin);
+		if (pktin->type == SSH1_SMSG_FAILURE) {
+		    c_write_str(ssh, "Server refused our public key.\r\n");
+		    continue;	       /* go and try something else */
+		}
+		if (pktin->type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
+		    bombout(("Bizarre response to offer of public key"));
+		    crStop(0);
+		}
+
+		{
+		    int i;
+		    unsigned char buffer[32];
+		    Bignum challenge, response;
+
+		    if ((challenge = ssh1_pkt_getmp(pktin)) == NULL) {
+			bombout(("Server's RSA challenge was badly formatted"));
+			crStop(0);
+		    }
+		    response = rsadecrypt(challenge, &s->key);
+		    freebn(s->key.private_exponent);/* burn the evidence */
+
+		    for (i = 0; i < 32; i++) {
+			buffer[i] = bignum_byte(response, 31 - i);
+		    }
+
+		    MD5Init(&md5c);
+		    MD5Update(&md5c, buffer, 32);
+		    MD5Update(&md5c, s->session_id, 16);
+		    MD5Final(buffer, &md5c);
+
+		    send_packet(ssh, SSH1_CMSG_AUTH_RSA_RESPONSE,
+				PKT_DATA, buffer, 16, PKT_END);
+
+		    freebn(challenge);
+		    freebn(response);
+		}
+
+		crWaitUntil(pktin);
+		if (pktin->type == SSH1_SMSG_FAILURE) {
+		    if (flags & FLAG_VERBOSE)
+			c_write_str(ssh, "Failed to authenticate with"
+				    " our public key.\r\n");
+		    continue;	       /* go and try something else */
+		} else if (pktin->type != SSH1_SMSG_SUCCESS) {
+		    bombout(("Bizarre response to RSA authentication response"));
+		    crStop(0);
+		}
+
+		break;		       /* we're through! */
+	    }
+
+	}
+
+	/*
+	 * Otherwise, try various forms of password-like authentication.
+	 */
+	s->cur_prompt = new_prompts(ssh->frontend);
 
 	if (ssh->cfg.try_tis_auth &&
 	    (s->supported_auths_mask & (1 << SSH1_AUTH_TIS)) &&
@@ -3209,6 +3560,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	    } else {
 		char *challenge;
 		int challengelen;
+		char *instr_suf, *prompt;
 
 		ssh_pkt_getstring(pktin, &challenge, &challengelen);
 		if (!challenge) {
@@ -3216,15 +3568,23 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		    crStop(0);
 		}
 		logevent("Received TIS challenge");
-		if (challengelen > sizeof(s->prompt) - 1)
-		    challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
-		memcpy(s->prompt, challenge, challengelen);
+		s->cur_prompt->to_server = TRUE;
+		s->cur_prompt->name = dupstr("SSH TIS authentication");
 		/* Prompt heuristic comes from OpenSSH */
-		strncpy(s->prompt + challengelen,
-		        memchr(s->prompt, '\n', challengelen) ?
-			"": "\r\nResponse: ",
-			(sizeof s->prompt) - challengelen);
-		s->prompt[(sizeof s->prompt) - 1] = '\0';
+		if (memchr(challenge, '\n', challengelen)) {
+		    instr_suf = dupstr("");
+		    prompt = dupprintf("%.*s", challengelen, challenge);
+		} else {
+		    instr_suf = dupprintf("%.*s", challengelen, challenge);
+		    prompt = dupstr("Response: ");
+		}
+		s->cur_prompt->instruction =
+		    dupprintf("Using TIS authentication.%s%s",
+			      (*instr_suf) ? "\n" : "",
+			      instr_suf);
+		s->cur_prompt->instr_reqd = TRUE;
+		add_prompt(s->cur_prompt, prompt, FALSE, SSH_MAX_PASSWORD_LEN);
+		sfree(instr_suf);
 	    }
 	}
 	if (ssh->cfg.try_tis_auth &&
@@ -3242,6 +3602,7 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	    } else {
 		char *challenge;
 		int challengelen;
+		char *instr_suf, *prompt;
 
 		ssh_pkt_getstring(pktin, &challenge, &challengelen);
 		if (!challenge) {
@@ -3249,45 +3610,32 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 		    crStop(0);
 		}
 		logevent("Received CryptoCard challenge");
-		if (challengelen > sizeof(s->prompt) - 1)
-		    challengelen = sizeof(s->prompt) - 1;/* prevent overrun */
-		memcpy(s->prompt, challenge, challengelen);
-		strncpy(s->prompt + challengelen,
-		        memchr(s->prompt, '\n', challengelen) ?
-			"" : "\r\nResponse: ",
-			sizeof(s->prompt) - challengelen);
-		s->prompt[sizeof(s->prompt) - 1] = '\0';
+		s->cur_prompt->to_server = TRUE;
+		s->cur_prompt->name = dupstr("SSH CryptoCard authentication");
+		s->cur_prompt->name_reqd = FALSE;
+		/* Prompt heuristic comes from OpenSSH */
+		if (memchr(challenge, '\n', challengelen)) {
+		    instr_suf = dupstr("");
+		    prompt = dupprintf("%.*s", challengelen, challenge);
+		} else {
+		    instr_suf = dupprintf("%.*s", challengelen, challenge);
+		    prompt = dupstr("Response: ");
+		}
+		s->cur_prompt->instruction =
+		    dupprintf("Using CryptoCard authentication.%s%s",
+			      (*instr_suf) ? "\n" : "",
+			      instr_suf);
+		s->cur_prompt->instr_reqd = TRUE;
+		add_prompt(s->cur_prompt, prompt, FALSE, SSH_MAX_PASSWORD_LEN);
+		sfree(instr_suf);
 	    }
 	}
 	if (s->pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
-	    sprintf(s->prompt, "%.90s@%.90s's password: ",
-		    s->username, ssh->savedhost);
-	}
-	if (s->pwpkt_type == SSH1_CMSG_AUTH_RSA) {
-	    char *comment = NULL;
-	    int type;
-	    char msgbuf[256];
-	    if (flags & FLAG_VERBOSE)
-		c_write_str(ssh, "Trying public key authentication.\r\n");
-	    logeventf(ssh, "Trying public key \"%s\"",
-		      filename_to_str(&ssh->cfg.keyfile));
-	    type = key_type(&ssh->cfg.keyfile);
-	    if (type != SSH_KEYTYPE_SSH1) {
-		sprintf(msgbuf, "Key is of wrong type (%s)",
-			key_type_to_str(type));
-		logevent(msgbuf);
-		c_write_str(ssh, msgbuf);
-		c_write_str(ssh, "\r\n");
-		s->tried_publickey = 1;
-		continue;
-	    }
-	    if (!rsakey_encrypted(&ssh->cfg.keyfile, &comment)) {
-		if (flags & FLAG_VERBOSE)
-		    c_write_str(ssh, "No passphrase required.\r\n");
-		goto tryauth;
-	    }
-	    sprintf(s->prompt, "Passphrase for key \"%.100s\": ", comment);
-	    sfree(comment);
+	    s->cur_prompt->to_server = TRUE;
+	    s->cur_prompt->name = dupstr("SSH password");
+	    add_prompt(s->cur_prompt, dupprintf("%.90s@%.90s's password: ",
+						s->username, ssh->savedhost),
+		       FALSE, SSH_MAX_PASSWORD_LEN);
 	}
 
 	/*
@@ -3295,251 +3643,155 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	 * or CryptoCard exchange if we're doing TIS or CryptoCard
 	 * authentication.
 	 */
-	if (ssh_get_line) {
-	    if (!ssh_get_line(s->prompt, s->password,
-			      sizeof(s->password), TRUE)) {
+	{
+	    int ret; /* need not be kept over crReturn */
+	    ret = get_userpass_input(s->cur_prompt, NULL, 0);
+	    while (ret < 0) {
+		ssh->send_ok = 1;
+		crWaitUntil(!pktin);
+		ret = get_userpass_input(s->cur_prompt, in, inlen);
+		ssh->send_ok = 0;
+	    }
+	    if (!ret) {
 		/*
-		 * get_line failed to get a password (for example
+		 * Failed to get a password (for example
 		 * 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);
-		crStop(1);
+		free_prompts(s->cur_prompt);
+		ssh_disconnect(ssh, NULL, "Unable to authenticate", 0, TRUE);
+		crStop(0);
 	    }
-	} else {
-	    /* Prompt may have come from server. We've munged it a bit, so
-	     * we know it to be zero-terminated at least once. */
-	    int ret;		       /* need not be saved over crReturn */
-	    c_write_untrusted(ssh, s->prompt, strlen(s->prompt));
-	    s->pos = 0;
-
-	    setup_userpass_input(ssh, s->password, sizeof(s->password), 0);
-	    do {
-		crWaitUntil(!pktin);
-		ret = process_userpass_input(ssh, in, inlen);
-	    } while (ret == 0);
-	    if (ret < 0)
-		cleanup_exit(0);
-	    c_write_str(ssh, "\r\n");
 	}
 
-      tryauth:
-	if (s->pwpkt_type == SSH1_CMSG_AUTH_RSA) {
-	    /*
-	     * Try public key authentication with the specified
-	     * key file.
-	     */
-	    s->tried_publickey = 1;
-	    
-	    {
-		const char *error = NULL;
-		int ret = loadrsakey(&ssh->cfg.keyfile, &s->key, s->password,
-				     &error);
-		if (ret == 0) {
-		    c_write_str(ssh, "Couldn't load private key from ");
-		    c_write_str(ssh, filename_to_str(&ssh->cfg.keyfile));
-		    c_write_str(ssh, " (");
-		    c_write_str(ssh, error);
-		    c_write_str(ssh, ").\r\n");
-		    continue;	       /* go and try password */
-		}
-		if (ret == -1) {
-		    c_write_str(ssh, "Wrong passphrase.\r\n");
-		    s->tried_publickey = 0;
-		    continue;	       /* try again */
-		}
-	    }
-
+	if (s->pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
 	    /*
-	     * Send a public key attempt.
+	     * Defence against traffic analysis: we send a
+	     * whole bunch of packets containing strings of
+	     * different lengths. One of these strings is the
+	     * password, in a SSH1_CMSG_AUTH_PASSWORD packet.
+	     * The others are all random data in
+	     * SSH1_MSG_IGNORE packets. This way a passive
+	     * listener can't tell which is the password, and
+	     * hence can't deduce the password length.
+	     * 
+	     * Anybody with a password length greater than 16
+	     * bytes is going to have enough entropy in their
+	     * password that a listener won't find it _that_
+	     * much help to know how long it is. So what we'll
+	     * do is:
+	     * 
+	     *  - if password length < 16, we send 15 packets
+	     *    containing string lengths 1 through 15
+	     * 
+	     *  - otherwise, we let N be the nearest multiple
+	     *    of 8 below the password length, and send 8
+	     *    packets containing string lengths N through
+	     *    N+7. This won't obscure the order of
+	     *    magnitude of the password length, but it will
+	     *    introduce a bit of extra uncertainty.
+	     * 
+	     * A few servers (the old 1.2.18 through 1.2.22)
+	     * can't deal with SSH1_MSG_IGNORE. For these
+	     * servers, we need an alternative defence. We make
+	     * use of the fact that the password is interpreted
+	     * as a C string: so we can append a NUL, then some
+	     * random data.
+	     * 
+	     * One server (a Cisco one) can deal with neither
+	     * SSH1_MSG_IGNORE _nor_ a padded password string.
+	     * For this server we are left with no defences
+	     * against password length sniffing.
 	     */
-	    send_packet(ssh, SSH1_CMSG_AUTH_RSA,
-			PKT_BIGNUM, s->key.modulus, PKT_END);
-
-	    crWaitUntil(pktin);
-	    if (pktin->type == SSH1_SMSG_FAILURE) {
-		c_write_str(ssh, "Server refused our public key.\r\n");
-		continue;	       /* go and try password */
-	    }
-	    if (pktin->type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
-		bombout(("Bizarre response to offer of public key"));
-		crStop(0);
-	    }
-
-	    {
-		int i;
-		unsigned char buffer[32];
-		Bignum challenge, response;
-
-		if ((challenge = ssh1_pkt_getmp(pktin)) == NULL) {
-		    bombout(("Server's RSA challenge was badly formatted"));
-		    crStop(0);
-		}
-		response = rsadecrypt(challenge, &s->key);
-		freebn(s->key.private_exponent);/* burn the evidence */
-
-		for (i = 0; i < 32; i++) {
-		    buffer[i] = bignum_byte(response, 31 - i);
-		}
-
-		MD5Init(&md5c);
-		MD5Update(&md5c, buffer, 32);
-		MD5Update(&md5c, s->session_id, 16);
-		MD5Final(buffer, &md5c);
-
-		send_packet(ssh, SSH1_CMSG_AUTH_RSA_RESPONSE,
-			    PKT_DATA, buffer, 16, PKT_END);
-
-		freebn(challenge);
-		freebn(response);
-	    }
-
-	    crWaitUntil(pktin);
-	    if (pktin->type == SSH1_SMSG_FAILURE) {
-		if (flags & FLAG_VERBOSE)
-		    c_write_str(ssh, "Failed to authenticate with"
-				" our public key.\r\n");
-		continue;	       /* go and try password */
-	    } else if (pktin->type != SSH1_SMSG_SUCCESS) {
-		bombout(("Bizarre response to RSA authentication response"));
-		crStop(0);
-	    }
-
-	    break;		       /* we're through! */
-	} else {
-	    if (s->pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
+	    if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE)) {
 		/*
-		 * Defence against traffic analysis: we send a
-		 * whole bunch of packets containing strings of
-		 * different lengths. One of these strings is the
-		 * password, in a SSH1_CMSG_AUTH_PASSWORD packet.
-		 * The others are all random data in
-		 * SSH1_MSG_IGNORE packets. This way a passive
-		 * listener can't tell which is the password, and
-		 * hence can't deduce the password length.
-		 * 
-		 * Anybody with a password length greater than 16
-		 * bytes is going to have enough entropy in their
-		 * password that a listener won't find it _that_
-		 * much help to know how long it is. So what we'll
-		 * do is:
-		 * 
-		 *  - if password length < 16, we send 15 packets
-		 *    containing string lengths 1 through 15
-		 * 
-		 *  - otherwise, we let N be the nearest multiple
-		 *    of 8 below the password length, and send 8
-		 *    packets containing string lengths N through
-		 *    N+7. This won't obscure the order of
-		 *    magnitude of the password length, but it will
-		 *    introduce a bit of extra uncertainty.
-		 * 
-		 * A few servers (the old 1.2.18 through 1.2.22)
-		 * can't deal with SSH1_MSG_IGNORE. For these
-		 * servers, we need an alternative defence. We make
-		 * use of the fact that the password is interpreted
-		 * as a C string: so we can append a NUL, then some
-		 * random data.
-		 * 
-		 * One server (a Cisco one) can deal with neither
-		 * SSH1_MSG_IGNORE _nor_ a padded password string.
-		 * For this server we are left with no defences
-		 * against password length sniffing.
+		 * The server can deal with SSH1_MSG_IGNORE, so
+		 * we can use the primary defence.
 		 */
-		if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE)) {
-		    /*
-		     * The server can deal with SSH1_MSG_IGNORE, so
-		     * we can use the primary defence.
-		     */
-		    int bottom, top, pwlen, i;
-		    char *randomstr;
+		int bottom, top, pwlen, i;
+		char *randomstr;
 
-		    pwlen = strlen(s->password);
-		    if (pwlen < 16) {
-			bottom = 0;    /* zero length passwords are OK! :-) */
-			top = 15;
-		    } else {
-			bottom = pwlen & ~7;
-			top = bottom + 7;
-		    }
+		pwlen = strlen(s->cur_prompt->prompts[0]->result);
+		if (pwlen < 16) {
+		    bottom = 0;    /* zero length passwords are OK! :-) */
+		    top = 15;
+		} else {
+		    bottom = pwlen & ~7;
+		    top = bottom + 7;
+		}
 
-		    assert(pwlen >= bottom && pwlen <= top);
+		assert(pwlen >= bottom && pwlen <= top);
 
-		    randomstr = snewn(top + 1, char);
+		randomstr = snewn(top + 1, char);
 
-		    for (i = bottom; i <= top; i++) {
-			if (i == pwlen) {
-			    defer_packet(ssh, s->pwpkt_type,
-					 PKTT_PASSWORD, PKT_STR, s->password,
-					 PKTT_OTHER, PKT_END);
-			} else {
-			    for (j = 0; j < i; j++) {
-				do {
-				    randomstr[j] = random_byte();
-				} while (randomstr[j] == '\0');
-			    }
-			    randomstr[i] = '\0';
-			    defer_packet(ssh, SSH1_MSG_IGNORE,
-					 PKT_STR, randomstr, PKT_END);
+		for (i = bottom; i <= top; i++) {
+		    if (i == pwlen) {
+			defer_packet(ssh, s->pwpkt_type,
+				     PKTT_PASSWORD, PKT_STR,
+				     s->cur_prompt->prompts[0]->result,
+				     PKTT_OTHER, PKT_END);
+		    } else {
+			for (j = 0; j < i; j++) {
+			    do {
+				randomstr[j] = random_byte();
+			    } while (randomstr[j] == '\0');
 			}
+			randomstr[i] = '\0';
+			defer_packet(ssh, SSH1_MSG_IGNORE,
+				     PKT_STR, randomstr, PKT_END);
 		    }
-		    logevent("Sending password with camouflage packets");
-		    ssh_pkt_defersend(ssh);
-		    sfree(randomstr);
-		} 
-		else if (!(ssh->remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) {
-		    /*
-		     * The server can't deal with SSH1_MSG_IGNORE
-		     * but can deal with padded passwords, so we
-		     * can use the secondary defence.
-		     */
-		    char string[64];
-		    char *ss;
-		    int len;
-
-		    len = strlen(s->password);
-		    if (len < sizeof(string)) {
-			ss = string;
-			strcpy(string, s->password);
-			len++;	       /* cover the zero byte */
-			while (len < sizeof(string)) {
-			    string[len++] = (char) random_byte();
-			}
-		    } else {
-			ss = s->password;
+		}
+		logevent("Sending password with camouflage packets");
+		ssh_pkt_defersend(ssh);
+		sfree(randomstr);
+	    } 
+	    else if (!(ssh->remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) {
+		/*
+		 * The server can't deal with SSH1_MSG_IGNORE
+		 * but can deal with padded passwords, so we
+		 * can use the secondary defence.
+		 */
+		char string[64];
+		char *ss;
+		int len;
+
+		len = strlen(s->cur_prompt->prompts[0]->result);
+		if (len < sizeof(string)) {
+		    ss = string;
+		    strcpy(string, s->cur_prompt->prompts[0]->result);
+		    len++;	       /* cover the zero byte */
+		    while (len < sizeof(string)) {
+			string[len++] = (char) random_byte();
 		    }
-		    logevent("Sending length-padded password");
-		    send_packet(ssh, s->pwpkt_type, PKTT_PASSWORD,
-				PKT_INT, len, PKT_DATA, ss, len,
-			       	PKTT_OTHER, PKT_END);
 		} else {
-		    /*
-		     * The server has _both_
-		     * BUG_CHOKES_ON_SSH1_IGNORE and
-		     * BUG_NEEDS_SSH1_PLAIN_PASSWORD. There is
-		     * therefore nothing we can do.
-		     */
-		    int len;
-		    len = strlen(s->password);
-		    logevent("Sending unpadded password");
-		    send_packet(ssh, s->pwpkt_type,
-				PKTT_PASSWORD, PKT_INT, len,
-				PKT_DATA, s->password, len,
-				PKTT_OTHER, PKT_END);
+		    ss = s->cur_prompt->prompts[0]->result;
 		}
-	    } else {
+		logevent("Sending length-padded password");
 		send_packet(ssh, s->pwpkt_type, PKTT_PASSWORD,
-			    PKT_STR, s->password, PKTT_OTHER, PKT_END);
+			    PKT_INT, len, PKT_DATA, ss, len,
+			    PKTT_OTHER, PKT_END);
+	    } else {
+		/*
+		 * The server has _both_
+		 * BUG_CHOKES_ON_SSH1_IGNORE and
+		 * BUG_NEEDS_SSH1_PLAIN_PASSWORD. There is
+		 * therefore nothing we can do.
+		 */
+		int len;
+		len = strlen(s->cur_prompt->prompts[0]->result);
+		logevent("Sending unpadded password");
+		send_packet(ssh, s->pwpkt_type,
+			    PKTT_PASSWORD, PKT_INT, len,
+			    PKT_DATA, s->cur_prompt->prompts[0]->result, len,
+			    PKTT_OTHER, PKT_END);
 	    }
+	} else {
+	    send_packet(ssh, s->pwpkt_type, PKTT_PASSWORD,
+			PKT_STR, s->cur_prompt->prompts[0]->result,
+			PKTT_OTHER, PKT_END);
 	}
 	logevent("Sent password");
-	memset(s->password, 0, strlen(s->password));
+	free_prompts(s->cur_prompt);
 	crWaitUntil(pktin);
 	if (pktin->type == SSH1_SMSG_FAILURE) {
 	    if (flags & FLAG_VERBOSE)
@@ -3551,6 +3803,12 @@ static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
 	}
     }
 
+    /* Clear up */
+    if (s->publickey_blob) {
+	sfree(s->publickey_blob);
+	sfree(s->publickey_comment);
+    }
+
     logevent("Authentication successful");
 
     crFinish(1);
@@ -3560,10 +3818,8 @@ 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) {
 	/*
@@ -3600,10 +3856,8 @@ 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,
@@ -3612,7 +3866,7 @@ 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
@@ -3629,10 +3883,8 @@ 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) {
@@ -3784,13 +4036,13 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 		portfwd_strptr++;
 		sports[n] = '\0';
 		if (ssh->version == 1 && type == 'R') {
-		    logeventf(ssh, "SSH1 cannot handle remote source address "
+		    logeventf(ssh, "SSH-1 cannot handle remote source address "
 			      "spec \"%s\"; ignoring", sports);
 		} else
 		    strcpy(saddr, sports);
 		n = 0;
 	    }
-	    if (n < 255) sports[n++] = *portfwd_strptr++;
+	    if (n < lenof(sports)-1) sports[n++] = *portfwd_strptr++;
 	}
 	sports[n] = 0;
 	if (type != 'D') {
@@ -3798,14 +4050,14 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 		portfwd_strptr++;
 	    n = 0;
 	    while (*portfwd_strptr && *portfwd_strptr != ':') {
-		if (n < 255) host[n++] = *portfwd_strptr++;
+		if (n < lenof(host)-1) host[n++] = *portfwd_strptr++;
 	    }
 	    host[n] = 0;
 	    if (*portfwd_strptr == ':')
 		portfwd_strptr++;
 	    n = 0;
 	    while (*portfwd_strptr) {
-		if (n < 255) dports[n++] = *portfwd_strptr++;
+		if (n < lenof(dports)-1) dports[n++] = *portfwd_strptr++;
 	    }
 	    dports[n] = 0;
 	    portfwd_strptr++;
@@ -3821,6 +4073,8 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 	    }
 	} else {
 	    while (*portfwd_strptr) portfwd_strptr++;
+	    host[0] = 0;
+	    dports[0] = 0;
 	    dport = dserv = -1;
 	    portfwd_strptr++;	       /* eat the NUL and move to next one */
 	}
@@ -3903,7 +4157,7 @@ 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
@@ -3916,6 +4170,9 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 		    if (epf->saddr) {
 			ssh2_pkt_addstring(pktout, epf->saddr);
 		    } else if (ssh->cfg.rport_acceptall) {
+			/* XXX: ssh->cfg.rport_acceptall may not represent
+			 * what was used to open the original connection,
+			 * since it's reconfigurable. */
 			ssh2_pkt_addstring(pktout, "0.0.0.0");
 		    } else {
 			ssh2_pkt_addstring(pktout, "127.0.0.1");
@@ -3962,7 +4219,7 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 	    if (epf->type == 'L') {
 		const char *err = pfd_addforward(epf->daddr, epf->dport,
 						 epf->saddr, epf->sport,
-						 ssh, &ssh->cfg,
+						 ssh, cfg,
 						 &epf->local,
 						 epf->addressfamily);
 
@@ -3974,7 +4231,7 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 	    } else if (epf->type == 'D') {
 		const char *err = pfd_addforward(NULL, -1,
 						 epf->saddr, epf->sport,
-						 ssh, &ssh->cfg,
+						 ssh, cfg,
 						 &epf->local,
 						 epf->addressfamily);
 
@@ -4030,7 +4287,7 @@ static void ssh_setup_portfwd(Ssh ssh, const Config *cfg)
 			ssh2_pkt_addbool(pktout, 1);/* want reply */
 			if (epf->saddr) {
 			    ssh2_pkt_addstring(pktout, epf->saddr);
-			} else if (ssh->cfg.rport_acceptall) {
+			} else if (cfg->rport_acceptall) {
 			    ssh2_pkt_addstring(pktout, "0.0.0.0");
 			} else {
 			    ssh2_pkt_addstring(pktout, "127.0.0.1");
@@ -4145,7 +4402,7 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
     struct ssh_rportfwd pf, *pfp;
     int remoteid;
     int hostsize, port;
-    char *host, buf[1024];
+    char *host;
     const char *e;
     c = snew(struct ssh_channel);
     c->ssh = ssh;
@@ -4162,21 +4419,17 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
     pfp = find234(ssh->rportfwds, &pf, NULL);
 
     if (pfp == NULL) {
-	sprintf(buf, "Rejected remote port open request for %s:%d",
-		pf.dhost, port);
-	logevent(buf);
+	logeventf(ssh, "Rejected remote port open request for %s:%d",
+		  pf.dhost, port);
 	send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
 		    PKT_INT, remoteid, PKT_END);
     } else {
-	sprintf(buf, "Received remote port open request for %s:%d",
-		pf.dhost, port);
-	logevent(buf);
+	logeventf(ssh, "Received remote port open request for %s:%d",
+		  pf.dhost, port);
 	e = pfd_newconnect(&c->u.pfd.s, pf.dhost, port,
 			   c, &ssh->cfg, pfp->pfrec->addressfamily);
 	if (e != NULL) {
-	    char buf[256];
-	    sprintf(buf, "Port open failed: %s", e);
-	    logevent(buf);
+	    logeventf(ssh, "Port open failed: %s", e);
 	    sfree(c);
 	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_FAILURE,
 			PKT_INT, remoteid, PKT_END);
@@ -4352,11 +4605,8 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
 
 static void ssh1_smsg_exit_status(Ssh ssh, struct Packet *pktin)
 {
-    char buf[100];
     ssh->exitcode = ssh_pkt_getuint32(pktin);
-    sprintf(buf, "Server sent command exit status %d",
-	    ssh->exitcode);
-    logevent(buf);
+    logeventf(ssh, "Server sent command exit status %d", ssh->exitcode);
     send_packet(ssh, SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
     /*
      * In case `helpful' firewalls or proxies tack
@@ -4365,10 +4615,30 @@ 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)
 {
@@ -4413,14 +4683,23 @@ 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;
@@ -4442,19 +4721,26 @@ 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;
@@ -4496,12 +4782,14 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Start the shell or command.
      * 
-     * Special case: if the first-choice command is an SSH2
+     * Special case: if the first-choice command is an SSH-2
      * subsystem (hence not usable here) and the second choice
      * exists, we fall straight back to that.
      */
     {
 	char *cmd = ssh->cfg.remote_cmd_ptr;
+
+	if (!cmd) cmd = ssh->cfg.remote_cmd;
 	
 	if (ssh->cfg.ssh_subsys && ssh->cfg.remote_cmd_ptr2) {
 	    cmd = ssh->cfg.remote_cmd_ptr2;
@@ -4559,17 +4847,15 @@ static void do_ssh1_connection(Ssh ssh, unsigned char *in, int inlen,
 }
 
 /*
- * Handle the top-level SSH2 protocol.
+ * Handle the top-level SSH-2 protocol.
  */
 static void ssh1_msg_debug(Ssh ssh, struct Packet *pktin)
 {
-    char *buf, *msg;
+    char *msg;
     int msglen;
 
     ssh_pkt_getstring(pktin, &msg, &msglen);
-    buf = dupprintf("Remote debug message: %.*s", msglen, msg);
-    logevent(buf);
-    sfree(buf);
+    logeventf(ssh, "Remote debug message: %.*s", msglen, msg);
 }
 
 static void ssh1_msg_disconnect(Ssh ssh, struct Packet *pktin)
@@ -4681,40 +4967,45 @@ static int first_in_commasep_string(char *needle, char *haystack, int haylen)
 
 
 /*
- * SSH2 key creation method.
+ * SSH-2 key creation method.
+ * (Currently assumes 2 lots of any hash are sufficient to generate
+ * keys/IVs for any cipher/MAC. SSH2_MKKEY_ITERS documents this assumption.)
  */
-static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H,
-		       unsigned char *sessid, char chr,
+#define SSH2_MKKEY_ITERS (2)
+static void ssh2_mkkey(Ssh ssh, Bignum K, unsigned char *H, char chr,
 		       unsigned char *keyspace)
 {
-    SHA_State s;
-    /* First 20 bytes. */
-    SHA_Init(&s);
+    const struct ssh_hash *h = ssh->kex->hash;
+    void *s;
+    /* First hlen bytes. */
+    s = h->init();
     if (!(ssh->remote_bugs & BUG_SSH2_DERIVEKEY))
-	sha_mpint(&s, K);
-    SHA_Bytes(&s, H, 20);
-    SHA_Bytes(&s, &chr, 1);
-    SHA_Bytes(&s, sessid, 20);
-    SHA_Final(&s, keyspace);
-    /* Next 20 bytes. */
-    SHA_Init(&s);
+	hash_mpint(h, s, K);
+    h->bytes(s, H, h->hlen);
+    h->bytes(s, &chr, 1);
+    h->bytes(s, ssh->v2_session_id, ssh->v2_session_id_len);
+    h->final(s, keyspace);
+    /* Next hlen bytes. */
+    s = h->init();
     if (!(ssh->remote_bugs & BUG_SSH2_DERIVEKEY))
-	sha_mpint(&s, K);
-    SHA_Bytes(&s, H, 20);
-    SHA_Bytes(&s, keyspace, 20);
-    SHA_Final(&s, keyspace + 20);
+	hash_mpint(h, s, K);
+    h->bytes(s, H, h->hlen);
+    h->bytes(s, keyspace, h->hlen);
+    h->final(s, keyspace + h->hlen);
 }
 
 /*
- * 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)
 {
     unsigned char *in = (unsigned char *)vin;
     struct do_ssh2_transport_state {
-	int nbits, pbits, warn;
+	int nbits, pbits, warn_kex, warn_cscipher, warn_sccipher;
 	Bignum p, g, e, f, K;
+	void *our_kexinit;
+	int our_kexinitlen;
 	int kex_init_value, kex_reply_value;
 	const struct ssh_mac **maclist;
 	int nmacs;
@@ -4727,14 +5018,17 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	char *hostkeydata, *sigdata, *keystr, *fingerprint;
 	int hostkeylen, siglen;
 	void *hkey;		       /* actual host key */
-	unsigned char exchange_hash[20];
+	unsigned char exchange_hash[SSH2_KEX_MAX_HASH_LEN];
 	int n_preferred_kex;
-	const struct ssh_kex *preferred_kex[KEX_MAX];
+	const struct ssh_kexes *preferred_kex[KEX_MAX];
 	int n_preferred_ciphers;
 	const struct ssh2_ciphers *preferred_ciphers[CIPHER_MAX];
 	const struct ssh_compress *preferred_comp;
 	int got_session_id, activated_authconn;
 	struct Packet *pktout;
+        int dlgret;
+	int guessok;
+	int ignorepkt;
     };
     crState(do_ssh2_transport_state);
 
@@ -4777,7 +5071,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 		s->preferred_kex[s->n_preferred_kex++] =
 		    &ssh_diffiehellman_group1;
 		break;
-	      case CIPHER_WARN:
+	      case KEX_WARN:
 		/* Flag for later. Don't bother if it's the last in
 		 * the list. */
 		if (i < KEX_MAX - 1) {
@@ -4807,6 +5101,9 @@ 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. */
@@ -4846,12 +5143,14 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	ssh2_pkt_addstring_start(s->pktout);
 	commalist_started = 0;
 	for (i = 0; i < s->n_preferred_kex; i++) {
-	    const struct ssh_kex *k = s->preferred_kex[i];
+	    const struct ssh_kexes *k = s->preferred_kex[i];
 	    if (!k) continue;	       /* warning flag */
-	    if (commalist_started)
-		ssh2_pkt_addstring_str(s->pktout, ",");
-	    ssh2_pkt_addstring_str(s->pktout, s->preferred_kex[i]->name);
-	    commalist_started = 1;
+	    for (j = 0; j < k->nkexes; j++) {
+		if (commalist_started)
+		    ssh2_pkt_addstring_str(s->pktout, ",");
+		ssh2_pkt_addstring_str(s->pktout, k->list[j]->name);
+		commalist_started = 1;
+	    }
 	}
 	/* List server host key algorithms. */
 	ssh2_pkt_addstring_start(s->pktout);
@@ -4932,23 +5231,22 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	ssh2_pkt_adduint32(s->pktout, 0);
     }
 
-    ssh->exhash = ssh->exhashbase;
-    sha_string(&ssh->exhash, s->pktout->data + 5, s->pktout->length - 5);
+    s->our_kexinitlen = s->pktout->length - 5;
+    s->our_kexinit = snewn(s->our_kexinitlen, unsigned char);
+    memcpy(s->our_kexinit, s->pktout->data + 5, s->our_kexinitlen); 
 
     ssh2_pkt_send_noqueue(ssh, s->pktout);
 
     if (!pktin)
 	crWaitUntil(pktin);
-    if (pktin->length > 5)
-	sha_string(&ssh->exhash, pktin->data + 5, pktin->length - 5);
 
     /*
      * Now examine the other side's KEXINIT to see what we're up
      * to.
      */
     {
-	char *str;
-	int i, j, len, guessok;
+	char *str, *preferred;
+	int i, j, len;
 
 	if (pktin->type != SSH2_MSG_KEXINIT) {
 	    bombout(("expected key exchange packet from server"));
@@ -4962,25 +5260,27 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	s->scmac_tobe = NULL;
 	s->cscomp_tobe = NULL;
 	s->sccomp_tobe = NULL;
+	s->warn_kex = s->warn_cscipher = s->warn_sccipher = FALSE;
+
 	pktin->savedpos += 16;	        /* skip garbage cookie */
 	ssh_pkt_getstring(pktin, &str, &len);    /* key exchange algorithms */
-	s->warn = 0;
+
+	preferred = NULL;
 	for (i = 0; i < s->n_preferred_kex; i++) {
-	    const struct ssh_kex *k = s->preferred_kex[i];
+	    const struct ssh_kexes *k = s->preferred_kex[i];
 	    if (!k) {
-		s->warn = 1;
-	    } else if (in_commasep_string(k->name, str, len)) {
-		ssh->kex = k;
+		s->warn_kex = TRUE;
+	    } else {
+		for (j = 0; j < k->nkexes; j++) {
+		    if (!preferred) preferred = k->list[j]->name;
+		    if (in_commasep_string(k->list[j]->name, str, len)) {
+			ssh->kex = k->list[j];
+			break;
+		    }
+		}
 	    }
-	    if (ssh->kex) {
-		if (s->warn) {
-                    sk_set_frozen(ssh->s, 1);
-		    askalg(ssh->frontend, "key-exchange algorithm",
-			   ssh->kex->name);
-                    sk_set_frozen(ssh->s, 0);
-                }
+	    if (ssh->kex)
 		break;
-	    }
 	}
 	if (!ssh->kex) {
 	    bombout(("Couldn't agree a key exchange algorithm (available: %s)",
@@ -4992,8 +5292,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	 * the first algorithm in our list, even if it's still the algorithm
 	 * we end up using.
 	 */
-	guessok =
-	    first_in_commasep_string(s->preferred_kex[0]->name, str, len);
+	s->guessok = first_in_commasep_string(preferred, str, len);
 	ssh_pkt_getstring(pktin, &str, &len);    /* host key algorithms */
 	for (i = 0; i < lenof(hostkey_algs); i++) {
 	    if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
@@ -5001,14 +5300,13 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 		break;
 	    }
 	}
-	guessok = guessok &&
+	s->guessok = s->guessok &&
 	    first_in_commasep_string(hostkey_algs[0]->name, str, len);
 	ssh_pkt_getstring(pktin, &str, &len);    /* client->server cipher */
-	s->warn = 0;
 	for (i = 0; i < s->n_preferred_ciphers; i++) {
 	    const struct ssh2_ciphers *c = s->preferred_ciphers[i];
 	    if (!c) {
-		s->warn = 1;
+		s->warn_cscipher = TRUE;
 	    } else {
 		for (j = 0; j < c->nciphers; j++) {
 		    if (in_commasep_string(c->list[j]->name, str, len)) {
@@ -5017,15 +5315,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 		    }
 		}
 	    }
-	    if (s->cscipher_tobe) {
-		if (s->warn) {
-                    sk_set_frozen(ssh->s, 1);
-		    askalg(ssh->frontend, "client-to-server cipher",
-			   s->cscipher_tobe->name);
-                    sk_set_frozen(ssh->s, 0);
-                }
+	    if (s->cscipher_tobe)
 		break;
-	    }
 	}
 	if (!s->cscipher_tobe) {
 	    bombout(("Couldn't agree a client-to-server cipher (available: %s)",
@@ -5034,11 +5325,10 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	}
 
 	ssh_pkt_getstring(pktin, &str, &len);    /* server->client cipher */
-	s->warn = 0;
 	for (i = 0; i < s->n_preferred_ciphers; i++) {
 	    const struct ssh2_ciphers *c = s->preferred_ciphers[i];
 	    if (!c) {
-		s->warn = 1;
+		s->warn_sccipher = TRUE;
 	    } else {
 		for (j = 0; j < c->nciphers; j++) {
 		    if (in_commasep_string(c->list[j]->name, str, len)) {
@@ -5047,15 +5337,8 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 		    }
 		}
 	    }
-	    if (s->sccipher_tobe) {
-		if (s->warn) {
-                    sk_set_frozen(ssh->s, 1);
-		    askalg(ssh->frontend, "server-to-client cipher",
-			   s->sccipher_tobe->name);
-                    sk_set_frozen(ssh->s, 0);
-                }
+	    if (s->sccipher_tobe)
 		break;
-	    }
 	}
 	if (!s->sccipher_tobe) {
 	    bombout(("Couldn't agree a server-to-client cipher (available: %s)",
@@ -5097,7 +5380,93 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	}
 	ssh_pkt_getstring(pktin, &str, &len);  /* client->server language */
 	ssh_pkt_getstring(pktin, &str, &len);  /* server->client language */
-	if (ssh2_pkt_getbool(pktin) && !guessok) /* first_kex_packet_follows */
+	s->ignorepkt = ssh2_pkt_getbool(pktin) && !s->guessok;
+
+	if (s->warn_kex) {
+	    ssh_set_frozen(ssh, 1);
+	    s->dlgret = askalg(ssh->frontend, "key-exchange algorithm",
+			       ssh->kex->name,
+			       ssh_dialog_callback, ssh);
+	    if (s->dlgret < 0) {
+		do {
+		    crReturn(0);
+		    if (pktin) {
+			bombout(("Unexpected data from server while"
+				 " waiting for user response"));
+			crStop(0);
+		    }
+		} while (pktin || inlen > 0);
+		s->dlgret = ssh->user_response;
+	    }
+	    ssh_set_frozen(ssh, 0);
+	    if (s->dlgret == 0) {
+		ssh_disconnect(ssh, "User aborted at kex warning", NULL,
+			       0, TRUE);
+		crStop(0);
+	    }
+	}
+
+	if (s->warn_cscipher) {
+	    ssh_set_frozen(ssh, 1);
+	    s->dlgret = askalg(ssh->frontend,
+			       "client-to-server cipher",
+			       s->cscipher_tobe->name,
+			       ssh_dialog_callback, ssh);
+	    if (s->dlgret < 0) {
+		do {
+		    crReturn(0);
+		    if (pktin) {
+			bombout(("Unexpected data from server while"
+				 " waiting for user response"));
+			crStop(0);
+		    }
+		} while (pktin || inlen > 0);
+		s->dlgret = ssh->user_response;
+	    }
+	    ssh_set_frozen(ssh, 0);
+	    if (s->dlgret == 0) {
+		ssh_disconnect(ssh, "User aborted at cipher warning", NULL,
+			       0, TRUE);
+		crStop(0);
+	    }
+	}
+
+	if (s->warn_sccipher) {
+	    ssh_set_frozen(ssh, 1);
+	    s->dlgret = askalg(ssh->frontend,
+			       "server-to-client cipher",
+			       s->sccipher_tobe->name,
+			       ssh_dialog_callback, ssh);
+	    if (s->dlgret < 0) {
+		do {
+		    crReturn(0);
+		    if (pktin) {
+			bombout(("Unexpected data from server while"
+				 " waiting for user response"));
+			crStop(0);
+		    }
+		} while (pktin || inlen > 0);
+		s->dlgret = ssh->user_response;
+	    }
+	    ssh_set_frozen(ssh, 0);
+	    if (s->dlgret == 0) {
+		ssh_disconnect(ssh, "User aborted at cipher warning", NULL,
+			       0, TRUE);
+		crStop(0);
+	    }
+	}
+
+	ssh->exhash = ssh->kex->hash->init();
+	hash_string(ssh->kex->hash, ssh->exhash, ssh->v_c, strlen(ssh->v_c));
+	hash_string(ssh->kex->hash, ssh->exhash, ssh->v_s, strlen(ssh->v_s));
+	hash_string(ssh->kex->hash, ssh->exhash,
+	    s->our_kexinit, s->our_kexinitlen);
+	sfree(s->our_kexinit);
+	if (pktin->length > 5)
+	    hash_string(ssh->kex->hash, ssh->exhash,
+		pktin->data + 5, pktin->length - 5);
+
+	if (s->ignorepkt) /* first_kex_packet_follows */
 	    crWaitUntil(pktin);                /* Ignore packet */
     }
 
@@ -5113,10 +5482,10 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 	scbits = s->sccipher_tobe->keylen;
 	s->nbits = (csbits > scbits ? csbits : scbits);
     }
-    /* The keys only have 160-bit entropy, since they're based on
-     * a SHA-1 hash. So cap the key size at 160 bits. */
-    if (s->nbits > 160)
-	s->nbits = 160;
+    /* The keys only have hlen-bit entropy, since they're based on
+     * a hash. So cap the key size at hlen bits. */
+    if (s->nbits > ssh->kex->hash->hlen * 8)
+	s->nbits = ssh->kex->hash->hlen * 8;
 
     /*
      * If we're doing Diffie-Hellman group exchange, start by
@@ -5157,20 +5526,24 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 		  ssh->kex->groupname);
     }
 
-    logevent("Doing Diffie-Hellman key exchange");
+    logeventf(ssh, "Doing Diffie-Hellman key exchange with hash %s",
+             ssh->kex->hash->text_name);
     /*
      * Now generate and send e for Diffie-Hellman.
      */
+    set_busy_status(ssh->frontend, BUSY_CPU); /* this can take a while */
     s->e = dh_create_e(ssh->kex_ctx, s->nbits * 2);
     s->pktout = ssh2_pkt_init(s->kex_init_value);
     ssh2_pkt_addmp(s->pktout, s->e);
     ssh2_pkt_send_noqueue(ssh, s->pktout);
 
+    set_busy_status(ssh->frontend, BUSY_WAITING); /* wait for server */
     crWaitUntil(pktin);
     if (pktin->type != s->kex_reply_value) {
 	bombout(("expected key exchange reply packet from server"));
 	crStop(0);
     }
+    set_busy_status(ssh->frontend, BUSY_CPU); /* cogitate */
     ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
     s->f = ssh2_pkt_getmp(pktin);
     if (!s->f) {
@@ -5181,29 +5554,35 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
 
     s->K = dh_find_K(ssh->kex_ctx, s->f);
 
-    sha_string(&ssh->exhash, s->hostkeydata, s->hostkeylen);
-    if (ssh->kex == &ssh_diffiehellman_gex) {
-	sha_uint32(&ssh->exhash, s->pbits);
-	sha_mpint(&ssh->exhash, s->p);
-	sha_mpint(&ssh->exhash, s->g);
+    /* We assume everything from now on will be quick, and it might
+     * involve user interaction. */
+    set_busy_status(ssh->frontend, BUSY_NOT);
+
+    hash_string(ssh->kex->hash, ssh->exhash, s->hostkeydata, s->hostkeylen);
+    if (!ssh->kex->pdata) {
+	hash_uint32(ssh->kex->hash, ssh->exhash, s->pbits);
+	hash_mpint(ssh->kex->hash, ssh->exhash, s->p);
+	hash_mpint(ssh->kex->hash, ssh->exhash, s->g);
     }
-    sha_mpint(&ssh->exhash, s->e);
-    sha_mpint(&ssh->exhash, s->f);
-    sha_mpint(&ssh->exhash, s->K);
-    SHA_Final(&ssh->exhash, s->exchange_hash);
+    hash_mpint(ssh->kex->hash, ssh->exhash, s->e);
+    hash_mpint(ssh->kex->hash, ssh->exhash, s->f);
+    hash_mpint(ssh->kex->hash, ssh->exhash, s->K);
+    assert(ssh->kex->hash->hlen <= sizeof(s->exchange_hash));
+    ssh->kex->hash->final(ssh->exhash, s->exchange_hash);
 
     dh_cleanup(ssh->kex_ctx);
     ssh->kex_ctx = NULL;
 
 #if 0
     debug(("Exchange hash is:\n"));
-    dmemdump(s->exchange_hash, 20);
+    dmemdump(s->exchange_hash, ssh->kex->hash->hlen);
 #endif
 
     s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
     if (!s->hkey ||
 	!ssh->hostkey->verifysig(s->hkey, s->sigdata, s->siglen,
-				 (char *)s->exchange_hash, 20)) {
+				 (char *)s->exchange_hash,
+				 ssh->kex->hash->hlen)) {
 	bombout(("Server's host key did not match the signature supplied"));
 	crStop(0);
     }
@@ -5214,11 +5593,29 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      */
     s->keystr = ssh->hostkey->fmtkey(s->hkey);
     s->fingerprint = ssh->hostkey->fingerprint(s->hkey);
-    sk_set_frozen(ssh->s, 1);
-    verify_ssh_host_key(ssh->frontend,
-			ssh->savedhost, ssh->savedport, ssh->hostkey->keytype,
-			s->keystr, s->fingerprint);
-    sk_set_frozen(ssh->s, 0);
+    ssh_set_frozen(ssh, 1);
+    s->dlgret = verify_ssh_host_key(ssh->frontend,
+                                    ssh->savedhost, ssh->savedport,
+                                    ssh->hostkey->keytype, s->keystr,
+				    s->fingerprint,
+                                    ssh_dialog_callback, ssh);
+    if (s->dlgret < 0) {
+        do {
+            crReturn(0);
+            if (pktin) {
+                bombout(("Unexpected data from server while waiting"
+                         " for user host key response"));
+                    crStop(0);
+            }
+        } while (pktin || inlen > 0);
+        s->dlgret = ssh->user_response;
+    }
+    ssh_set_frozen(ssh, 0);
+    if (s->dlgret == 0) {
+	ssh_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 */
 	logevent("Host key fingerprint is:");
 	logevent(s->fingerprint);
@@ -5233,8 +5630,11 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      * authentication.
      */
     if (!s->got_session_id) {
+	assert(sizeof(s->exchange_hash) <= sizeof(ssh->v2_session_id));
 	memcpy(ssh->v2_session_id, s->exchange_hash,
 	       sizeof(s->exchange_hash));
+	ssh->v2_session_id_len = ssh->kex->hash->hlen;
+	assert(ssh->v2_session_id_len <= sizeof(ssh->v2_session_id));
 	s->got_session_id = TRUE;
     }
 
@@ -5269,13 +5669,21 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      * hash from the _first_ key exchange.
      */
     {
-	unsigned char keyspace[40];
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'C',keyspace);
+	unsigned char keyspace[SSH2_KEX_MAX_HASH_LEN * SSH2_MKKEY_ITERS];
+	assert(sizeof(keyspace) >= ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,'C',keyspace);
+	assert((ssh->cscipher->keylen+7) / 8 <=
+	       ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
 	ssh->cscipher->setkey(ssh->cs_cipher_ctx, keyspace);
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'A',keyspace);
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,'A',keyspace);
+	assert(ssh->cscipher->blksize <=
+	       ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
 	ssh->cscipher->setiv(ssh->cs_cipher_ctx, keyspace);
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'E',keyspace);
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,'E',keyspace);
+	assert(ssh->csmac->len <=
+	       ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
 	ssh->csmac->setkey(ssh->cs_mac_ctx, keyspace);
+	memset(keyspace, 0, sizeof(keyspace));
     }
 
     logeventf(ssh, "Initialised %.200s client->server encryption",
@@ -5327,13 +5735,21 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      * hash from the _first_ key exchange.
      */
     {
-	unsigned char keyspace[40];
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'D',keyspace);
+	unsigned char keyspace[SSH2_KEX_MAX_HASH_LEN * SSH2_MKKEY_ITERS];
+	assert(sizeof(keyspace) >= ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,'D',keyspace);
+	assert((ssh->sccipher->keylen+7) / 8 <=
+	       ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
 	ssh->sccipher->setkey(ssh->sc_cipher_ctx, keyspace);
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'B',keyspace);
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,'B',keyspace);
+	assert(ssh->sccipher->blksize <=
+	       ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
 	ssh->sccipher->setiv(ssh->sc_cipher_ctx, keyspace);
-	ssh2_mkkey(ssh,s->K,s->exchange_hash,ssh->v2_session_id,'F',keyspace);
+	ssh2_mkkey(ssh,s->K,s->exchange_hash,'F',keyspace);
+	assert(ssh->scmac->len <=
+	       ssh->kex->hash->hlen * SSH2_MKKEY_ITERS);
 	ssh->scmac->setkey(ssh->sc_mac_ctx, keyspace);
+	memset(keyspace, 0, sizeof(keyspace));
     }
     logeventf(ssh, "Initialised %.200s server->client encryption",
 	      ssh->sccipher->text_name);
@@ -5348,7 +5764,7 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
      */
     freebn(s->f);
     freebn(s->K);
-    if (ssh->kex == &ssh_diffiehellman_gex) {
+    if (!ssh->kex->pdata) {
 	freebn(s->g);
 	freebn(s->p);
     }
@@ -5382,7 +5798,7 @@ 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;
 
@@ -5434,7 +5850,7 @@ 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)
@@ -5443,7 +5859,7 @@ 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)
 {
@@ -5476,8 +5892,34 @@ static int ssh2_try_send(struct ssh_channel *c)
     return bufchain_size(&c->v.v2.outbuffer);
 }
 
-/*
- * Potentially enlarge the window on an SSH2 channel.
+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 SSH-2 channel.
  */
 static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
 {
@@ -5514,8 +5956,10 @@ 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)
@@ -5669,12 +6113,10 @@ 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
@@ -5682,14 +6124,7 @@ 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);
     }
 }
 
@@ -5737,7 +6172,6 @@ static void ssh2_msg_channel_open_failure(Ssh ssh, struct Packet *pktin)
     unsigned reason_code;
     char *reason_string;
     int reason_length;
-    char *message;
     struct ssh_channel *c;
     c = find234(ssh->channels, &i, ssh_channelfind);
     if (!c)
@@ -5749,11 +6183,8 @@ static void ssh2_msg_channel_open_failure(Ssh ssh, struct Packet *pktin)
     if (reason_code >= lenof(reasons))
 	reason_code = 0; /* ensure reasons[reason_code] in range */
     ssh_pkt_getstring(pktin, &reason_string, &reason_length);
-    message = dupprintf("Forwarded connection refused by"
-			" server: %s [%.*s]", reasons[reason_code],
-			reason_length, reason_string);
-    logevent(message);
-    sfree(message);
+    logeventf(ssh, "Forwarded connection refused by server: %s [%.*s]",
+	      reasons[reason_code], reason_length, reason_string);
 
     pfd_close(c->u.pfd.s);
 
@@ -5780,18 +6211,10 @@ 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;
     }
 
@@ -6001,7 +6424,7 @@ 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 {
@@ -6041,18 +6464,48 @@ 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)
 {
     struct do_ssh2_authconn_state {
 	enum {
-	    AUTH_INVALID, AUTH_PUBLICKEY_AGENT, AUTH_PUBLICKEY_FILE,
-		AUTH_PASSWORD,
-		AUTH_KEYBOARD_INTERACTIVE
-	} method;
-	enum {
 	    AUTH_TYPE_NONE,
 		AUTH_TYPE_PUBLICKEY,
 		AUTH_TYPE_PUBLICKEY_OFFER_LOUD,
@@ -6061,21 +6514,25 @@ 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;
+	int tried_pubkey_config, done_agent;
+	int kbd_inter_refused;
 	int we_are_in;
-	int num_prompts, curr_prompt, echo;
+	prompts_t *cur_prompt;
+	int num_prompts;
 	char username[100];
+	char *password;
 	int got_username;
-	char pwprompt[512];
-	char password[100];
 	void *publickey_blob;
 	int publickey_bloblen;
-	unsigned char request[5], *response, *p;
-	int responselen;
+	int publickey_encrypted;
+	char *publickey_algorithm;
+	char *publickey_comment;
+	unsigned char agent_request[5], *agent_response, *agentp;
+	int agent_responselen;
+	unsigned char *pkblob_in_agent;
 	int keyi, nkeys;
-	int authed;
 	char *pkblob, *alg, *commentp;
 	int pklen, alglen, commentlen;
 	int siglen, retlen, len;
@@ -6088,16 +6545,153 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 
     crBegin(ssh->do_ssh2_authconn_crstate);
 
+    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;
+	}
+    }
+
+    /* Arrange to be able to deal with any BANNERs that come in.
+     * (We do this now as packets may come in during the next bit.) */
+    bufchain_init(&ssh->banner);
+    ssh->packet_dispatch[SSH2_MSG_USERAUTH_BANNER] =
+	ssh2_msg_userauth_banner;
+
     /*
-     * Request userauth protocol, and await a response to it.
+     * Misc one-time setup for authentication.
      */
-    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->publickey_blob = NULL;
+    if (!s->we_are_in) {
+
+	/*
+	 * Load the public half of any configured public key file
+	 * for later use.
+	 */
+	if (!filename_is_null(ssh->cfg.keyfile)) {
+	    int keytype;
+	    logeventf(ssh, "Reading private key file \"%.150s\"",
+		      filename_to_str(&ssh->cfg.keyfile));
+	    keytype = key_type(&ssh->cfg.keyfile);
+	    if (keytype == SSH_KEYTYPE_SSH2) {
+		const char *error;
+		s->publickey_blob =
+		    ssh2_userkey_loadpub(&ssh->cfg.keyfile,
+					 &s->publickey_algorithm,
+					 &s->publickey_bloblen, 
+					 &s->publickey_comment, &error);
+		if (s->publickey_blob) {
+		    s->publickey_encrypted =
+			ssh2_userkey_encrypted(&ssh->cfg.keyfile, NULL);
+		} else {
+		    char *msgbuf;
+		    logeventf(ssh, "Unable to load private key (%s)", 
+			      error);
+		    msgbuf = dupprintf("Unable to load private key file "
+				       "\"%.150s\" (%s)\r\n",
+				       filename_to_str(&ssh->cfg.keyfile),
+				       error);
+		    c_write_str(ssh, msgbuf);
+		    sfree(msgbuf);
+		}
+	    } else {
+		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;
+	    }
+	}
+
+	/*
+	 * Find out about any keys Pageant has (but if there's a
+	 * public key configured, filter out all others).
+	 */
+	s->nkeys = 0;
+	s->agent_response = NULL;
+	s->pkblob_in_agent = NULL;
+	if (ssh->cfg.tryagent && agent_exists()) {
+
+	    void *r;
+
+	    logevent("Pageant is running. Requesting keys.");
+
+	    /* Request the keys held by the agent. */
+	    PUT_32BIT(s->agent_request, 1);
+	    s->agent_request[4] = SSH2_AGENTC_REQUEST_IDENTITIES;
+	    if (!agent_query(s->agent_request, 5, &r, &s->agent_responselen,
+			     ssh_agent_callback, ssh)) {
+		do {
+		    crReturnV;
+		    if (pktin) {
+			bombout(("Unexpected data from server while"
+				 " waiting for agent response"));
+			crStopV;
+		    }
+		} while (pktin || inlen > 0);
+		r = ssh->agent_response;
+		s->agent_responselen = ssh->agent_response_len;
+	    }
+	    s->agent_response = (unsigned char *) r;
+	    if (s->agent_response && s->agent_responselen >= 5 &&
+		s->agent_response[4] == SSH2_AGENT_IDENTITIES_ANSWER) {
+		int keyi;
+		unsigned char *p;
+		p = s->agent_response + 5;
+		s->nkeys = GET_32BIT(p);
+		p += 4;
+		logeventf(ssh, "Pageant has %d SSH-2 keys", s->nkeys);
+		if (s->publickey_blob) {
+		    /* See if configured key is in agent. */
+		    for (keyi = 0; keyi < s->nkeys; keyi++) {
+			s->pklen = GET_32BIT(p);
+			if (s->pklen == s->publickey_bloblen &&
+			    !memcmp(p+4, s->publickey_blob,
+				    s->publickey_bloblen)) {
+			    logeventf(ssh, "Pageant key #%d matches "
+				      "configured key file", keyi);
+			    s->keyi = keyi;
+			    s->pkblob_in_agent = p;
+			    break;
+			}
+			p += 4 + s->pklen;
+			p += GET_32BIT(p) + 4; /* comment */
+		    }
+		    if (!s->pkblob_in_agent) {
+			logevent("Configured key file not in Pageant");
+			s->nkeys = 0;
+		    }
+		}
+	    }
+	}
+
     }
 
     /*
@@ -6126,7 +6720,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
      */
     s->username[0] = '\0';
     s->got_username = FALSE;
-    do {
+    while (!s->we_are_in) {
 	/*
 	 * Get a username.
 	 */
@@ -6137,32 +6731,31 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	     * it again.
 	     */
 	} else if (!*ssh->cfg.username) {
-	    if (ssh_get_line && !ssh_getline_pw_only) {
-		if (!ssh_get_line("login as: ",
-				  s->username, sizeof(s->username), FALSE)) {
-		    /*
-		     * 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);
-		    crStopV;
-		}
-	    } else {
-		int ret;	       /* need not be saved across crReturn */
-		c_write_str(ssh, "login as: ");
+	    int ret; /* need not be kept over crReturn */
+	    s->cur_prompt = new_prompts(ssh->frontend);
+	    s->cur_prompt->to_server = TRUE;
+	    s->cur_prompt->name = dupstr("SSH login name");
+	    add_prompt(s->cur_prompt, dupstr("login as: "), TRUE,
+		       lenof(s->username)); 
+	    ret = get_userpass_input(s->cur_prompt, NULL, 0);
+	    while (ret < 0) {
 		ssh->send_ok = 1;
-		setup_userpass_input(ssh, s->username, sizeof(s->username), 1);
-		do {
-		    crWaitUntilV(!pktin);
-		    ret = process_userpass_input(ssh, in, inlen);
-		} while (ret == 0);
-		if (ret < 0)
-		    cleanup_exit(0);
-		c_write_str(ssh, "\r\n");
+		crWaitUntilV(!pktin);
+		ret = get_userpass_input(s->cur_prompt, in, inlen);
+		ssh->send_ok = 0;
 	    }
-	    s->username[strcspn(s->username, "\n\r")] = '\0';
+	    if (!ret) {
+		/*
+		 * get_userpass_input() failed to get a username.
+		 * Terminate.
+		 */
+		free_prompts(s->cur_prompt);
+		ssh_disconnect(ssh, "No username provided", NULL, 0, TRUE);
+		crStopV;
+	    }
+	    memcpy(s->username, s->cur_prompt->prompts[0]->result,
+		   lenof(s->username));
+	    free_prompts(s->cur_prompt);
 	} else {
 	    char *stuff;
 	    strncpy(s->username, ssh->cfg.username, sizeof(s->username));
@@ -6192,33 +6785,18 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	s->we_are_in = FALSE;
 
 	s->tried_pubkey_config = FALSE;
-	s->tried_agent = FALSE;
-	s->kbd_inter_running = FALSE;
 	s->kbd_inter_refused = FALSE;
-	/* Load the pub half of ssh->cfg.keyfile so we notice if it's in Pageant */
-	if (!filename_is_null(ssh->cfg.keyfile)) {
-	    int keytype;
-	    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(&ssh->cfg.keyfile, NULL,
-					 &s->publickey_bloblen, NULL);
+
+	/* Reset agent request state. */
+	s->done_agent = FALSE;
+	if (s->agent_response) {
+	    if (s->pkblob_in_agent) {
+		s->agentp = s->pkblob_in_agent;
 	    } else {
-		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;
+		s->agentp = s->agent_response + 5 + 4;
+		s->keyi = 0;
 	    }
-	} else
-	    s->publickey_blob = NULL;
+	}
 
 	while (1) {
 	    /*
@@ -6226,9 +6804,14 @@ 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
@@ -6237,12 +6820,13 @@ 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");
@@ -6250,24 +6834,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		break;
 	    }
 
-	    if (s->kbd_inter_running &&
-		pktin->type == SSH2_MSG_USERAUTH_INFO_REQUEST) {
-		/*
-		 * This is either a further set-of-prompts packet
-		 * in keyboard-interactive authentication, or it's
-		 * the same one and we came back here with `gotit'
-		 * set. In the former case, we must reset the
-		 * curr_prompt variable.
-		 */
-		if (!s->gotit)
-		    s->curr_prompt = 0;
-	    } else if (pktin->type == SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ) {
-		/* FIXME: perhaps we should support this? */
-		bombout(("PASSWD_CHANGEREQ not yet supported"));
-		crStopV;
-	    } else if (pktin->type != SSH2_MSG_USERAUTH_FAILURE) {
-		bombout(("Strange packet received during authentication: type %d",
-			 pktin->type));
+	    if (pktin->type != SSH2_MSG_USERAUTH_FAILURE) {
+		bombout(("Strange packet received during authentication: "
+			 "type %d", pktin->type));
 		crStopV;
 	    }
 
@@ -6282,7 +6851,6 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		char *methods;
 		int methlen;
 		ssh_pkt_getstring(pktin, &methods, &methlen);
-		s->kbd_inter_running = FALSE;
 		if (!ssh2_pkt_getbool(pktin)) {
 		    /*
 		     * We have received an unequivocal Access
@@ -6339,425 +6907,275 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		    in_commasep_string("keyboard-interactive", methods, methlen);
 	    }
 
-	    s->method = 0;
 	    ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-	    s->need_pw = FALSE;
 
-	    /*
-	     * Most password/passphrase prompts will be
-	     * non-echoing, so we set this to 0 by default.
-	     * Exception is that some keyboard-interactive prompts
-	     * can be echoing, in which case we'll set this to 1.
-	     */
-	    s->echo = 0;
+	    if (s->can_pubkey && !s->done_agent && s->nkeys) {
 
-	    if (!s->method && s->can_pubkey &&
-		agent_exists() && !s->tried_agent) {
 		/*
-		 * Attempt public-key authentication using Pageant.
+		 * Attempt public-key authentication using a key from Pageant.
 		 */
-		void *r;
-		s->authed = FALSE;
 
 		ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
 		ssh->pkt_ctx |= SSH2_PKTCTX_PUBLICKEY;
 
-		s->tried_agent = TRUE;
+		logeventf(ssh, "Trying Pageant key #%d", s->keyi);
+
+		/* Unpack key from agent response */
+		s->pklen = GET_32BIT(s->agentp);
+		s->agentp += 4;
+		s->pkblob = (char *)s->agentp;
+		s->agentp += s->pklen;
+		s->alglen = GET_32BIT(s->pkblob);
+		s->alg = s->pkblob + 4;
+		s->commentlen = GET_32BIT(s->agentp);
+		s->agentp += 4;
+		s->commentp = (char *)s->agentp;
+		s->agentp += s->commentlen;
+		/* s->agentp now points at next key, if any */
+
+		/* See if server will accept it */
+		s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+		ssh2_pkt_addstring(s->pktout, s->username);
+		ssh2_pkt_addstring(s->pktout, "ssh-connection");
+						    /* service requested */
+		ssh2_pkt_addstring(s->pktout, "publickey");
+						    /* method */
+		ssh2_pkt_addbool(s->pktout, FALSE); /* no signature included */
+		ssh2_pkt_addstring_start(s->pktout);
+		ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
+		ssh2_pkt_addstring_start(s->pktout);
+		ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
+		ssh2_pkt_send(ssh, s->pktout);
+		s->type = AUTH_TYPE_PUBLICKEY_OFFER_QUIET;
 
-		logevent("Pageant is running. Requesting keys.");
+		crWaitUntilV(pktin);
+		if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
 
-		/* Request the keys held by the agent. */
-		PUT_32BIT(s->request, 1);
-		s->request[4] = SSH2_AGENTC_REQUEST_IDENTITIES;
-		if (!agent_query(s->request, 5, &r, &s->responselen,
-				 ssh_agent_callback, ssh)) {
-		    do {
-			crReturnV;
-			if (pktin) {
-			    bombout(("Unexpected data from server while"
-				     " waiting for agent response"));
-			    crStopV;
-			}
-		    } while (pktin || 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) {
-		    s->p = s->response + 5;
-		    s->nkeys = GET_32BIT(s->p);
-		    s->p += 4;
-		    {
-			char buf[64];
-			sprintf(buf, "Pageant has %d SSH2 keys", s->nkeys);
-			logevent(buf);
-		    }
-		    for (s->keyi = 0; s->keyi < s->nkeys; s->keyi++) {
-			void *vret;
+		    /* Offer of key refused. */
+		    s->gotit = TRUE;
 
-			{
-			    char buf[64];
-			    sprintf(buf, "Trying Pageant key #%d", s->keyi);
-			    logevent(buf);
-			}
-			s->pklen = GET_32BIT(s->p);
-			s->p += 4;
-			if (s->publickey_blob &&
-			    s->pklen == s->publickey_bloblen &&
-			    !memcmp(s->p, s->publickey_blob,
-				    s->publickey_bloblen)) {
-			    logevent("This key matches configured key file");
-			    s->tried_pubkey_config = 1;
-			}
-			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 = (char *)s->p;
-			s->p += s->commentlen;
-			s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-			ssh2_pkt_addstring(s->pktout, s->username);
-			ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
-			ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
-			ssh2_pkt_addbool(s->pktout, FALSE);	/* no signature included */
-			ssh2_pkt_addstring_start(s->pktout);
-			ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
-			ssh2_pkt_addstring_start(s->pktout);
-			ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
-			ssh2_pkt_send(ssh, s->pktout);
-
-			crWaitUntilV(pktin);
-			if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
-			    logevent("Key refused");
-			    continue;
-			}
+		} else {
+		    
+		    void *vret;
 
-			if (flags & FLAG_VERBOSE) {
-			    c_write_str(ssh, "Authenticating with "
-					"public key \"");
-			    c_write(ssh, s->commentp, s->commentlen);
-			    c_write_str(ssh, "\" from agent\r\n");
-			}
+		    if (flags & FLAG_VERBOSE) {
+			c_write_str(ssh, "Authenticating with "
+				    "public key \"");
+			c_write(ssh, s->commentp, s->commentlen);
+			c_write_str(ssh, "\" from agent\r\n");
+		    }
 
-			/*
-			 * Server is willing to accept the key.
-			 * Construct a SIGN_REQUEST.
-			 */
-			s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-			ssh2_pkt_addstring(s->pktout, s->username);
-			ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
-			ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
-			ssh2_pkt_addbool(s->pktout, TRUE);
-			ssh2_pkt_addstring_start(s->pktout);
-			ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
-			ssh2_pkt_addstring_start(s->pktout);
-			ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
-
-			s->siglen = s->pktout->length - 5 + 4 + 20;
-                        if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
-                            s->siglen -= 4;
-			s->len = 1;       /* message type */
-			s->len += 4 + s->pklen;	/* key blob */
-			s->len += 4 + s->siglen;	/* data to sign */
-			s->len += 4;      /* flags */
-			s->agentreq = snewn(4 + s->len, char);
-			PUT_32BIT(s->agentreq, s->len);
-			s->q = s->agentreq + 4;
-			*s->q++ = SSH2_AGENTC_SIGN_REQUEST;
-			PUT_32BIT(s->q, s->pklen);
-			s->q += 4;
-			memcpy(s->q, s->pkblob, s->pklen);
-			s->q += s->pklen;
-			PUT_32BIT(s->q, s->siglen);
+		    /*
+		     * Server is willing to accept the key.
+		     * Construct a SIGN_REQUEST.
+		     */
+		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+		    ssh2_pkt_addstring(s->pktout, s->username);
+		    ssh2_pkt_addstring(s->pktout, "ssh-connection");
+							/* service requested */
+		    ssh2_pkt_addstring(s->pktout, "publickey");
+							/* method */
+		    ssh2_pkt_addbool(s->pktout, TRUE);  /* signature included */
+		    ssh2_pkt_addstring_start(s->pktout);
+		    ssh2_pkt_addstring_data(s->pktout, s->alg, s->alglen);
+		    ssh2_pkt_addstring_start(s->pktout);
+		    ssh2_pkt_addstring_data(s->pktout, s->pkblob, s->pklen);
+
+		    /* Ask agent for signature. */
+		    s->siglen = s->pktout->length - 5 + 4 +
+			ssh->v2_session_id_len;
+		    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 = snewn(4 + s->len, char);
+		    PUT_32BIT(s->agentreq, s->len);
+		    s->q = s->agentreq + 4;
+		    *s->q++ = SSH2_AGENTC_SIGN_REQUEST;
+		    PUT_32BIT(s->q, s->pklen);
+		    s->q += 4;
+		    memcpy(s->q, s->pkblob, s->pklen);
+		    s->q += s->pklen;
+		    PUT_32BIT(s->q, s->siglen);
+		    s->q += 4;
+		    /* Now the data to be signed... */
+		    if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
+			PUT_32BIT(s->q, ssh->v2_session_id_len);
 			s->q += 4;
-			/* Now the data to be signed... */
-                        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, s->pktout->data + 5,
-			       s->pktout->length - 5);
-			s->q += s->pktout->length - 5;
-			/* And finally the (zero) flags word. */
-			PUT_32BIT(s->q, 0);
-			if (!agent_query(s->agentreq, s->len + 4,
-					 &vret, &s->retlen,
-					 ssh_agent_callback, ssh)) {
-			    do {
-				crReturnV;
-				if (pktin) {
-				    bombout(("Unexpected data from server"
-					     " while waiting for agent"
-					     " response"));
-				    crStopV;
-				}
-			    } while (pktin || inlen > 0);
-			    vret = ssh->agent_response;
-			    s->retlen = ssh->agent_response_len;
-			}
-			s->ret = vret;
-			sfree(s->agentreq);
-			if (s->ret) {
-			    if (s->ret[4] == SSH2_AGENT_SIGN_RESPONSE) {
-				logevent("Sending Pageant's response");
-				ssh2_add_sigblob(ssh, s->pktout,
-						 s->pkblob, s->pklen,
-						 s->ret + 9,
-						 GET_32BIT(s->ret + 5));
-				ssh2_pkt_send(ssh, s->pktout);
-				s->authed = TRUE;
-				break;
-			    } else {
-				logevent
-				    ("Pageant failed to answer challenge");
-				sfree(s->ret);
+		    }
+		    memcpy(s->q, ssh->v2_session_id,
+			   ssh->v2_session_id_len);
+		    s->q += ssh->v2_session_id_len;
+		    memcpy(s->q, s->pktout->data + 5,
+			   s->pktout->length - 5);
+		    s->q += s->pktout->length - 5;
+		    /* And finally the (zero) flags word. */
+		    PUT_32BIT(s->q, 0);
+		    if (!agent_query(s->agentreq, s->len + 4,
+				     &vret, &s->retlen,
+				     ssh_agent_callback, ssh)) {
+			do {
+			    crReturnV;
+			    if (pktin) {
+				bombout(("Unexpected data from server"
+					 " while waiting for agent"
+					 " response"));
+				crStopV;
 			    }
+			} while (pktin || inlen > 0);
+			vret = ssh->agent_response;
+			s->retlen = ssh->agent_response_len;
+		    }
+		    s->ret = vret;
+		    sfree(s->agentreq);
+		    if (s->ret) {
+			if (s->ret[4] == SSH2_AGENT_SIGN_RESPONSE) {
+			    logevent("Sending Pageant's response");
+			    ssh2_add_sigblob(ssh, s->pktout,
+					     s->pkblob, s->pklen,
+					     s->ret + 9,
+					     GET_32BIT(s->ret + 5));
+			    ssh2_pkt_send(ssh, s->pktout);
+			    s->type = AUTH_TYPE_PUBLICKEY;
+			} else {
+			    /* FIXME: less drastic response */
+			    bombout(("Pageant failed to answer challenge"));
+			    crStopV;
 			}
 		    }
-		    if (s->authed)
-			continue;
 		}
-		sfree(s->response);
-	    }
 
-	    if (!s->method && s->can_pubkey && s->publickey_blob
-		&& !s->tried_pubkey_config) {
-		unsigned char *pub_blob;
-		char *algorithm, *comment;
-		int pub_blob_len;
+		/* Do we have any keys left to try? */
+		if (s->pkblob_in_agent) {
+		    s->done_agent = TRUE;
+		    s->tried_pubkey_config = TRUE;
+		} else {
+		    s->keyi++;
+		    if (s->keyi >= s->nkeys)
+			s->done_agent = TRUE;
+		}
 
-		s->tried_pubkey_config = TRUE;
+	    } else if (s->can_pubkey && s->publickey_blob &&
+		       !s->tried_pubkey_config) {
+
+		struct ssh2_userkey *key;   /* not live over crReturn */
+		char *passphrase;	    /* not live over crReturn */
 
 		ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
 		ssh->pkt_ctx |= SSH2_PKTCTX_PUBLICKEY;
 
+		s->tried_pubkey_config = TRUE;
+
 		/*
 		 * Try the public key supplied in the configuration.
 		 *
 		 * First, offer the public blob to see if the server is
 		 * willing to accept it.
 		 */
-		pub_blob =
-		    (unsigned char *)ssh2_userkey_loadpub(&ssh->cfg.keyfile,
-							  &algorithm,
-							  &pub_blob_len,
-							  NULL);
-		if (pub_blob) {
-		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-		    ssh2_pkt_addstring(s->pktout, s->username);
-		    ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
-		    ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
-		    ssh2_pkt_addbool(s->pktout, FALSE);	/* no signature included */
-		    ssh2_pkt_addstring(s->pktout, algorithm);
-		    ssh2_pkt_addstring_start(s->pktout);
-		    ssh2_pkt_addstring_data(s->pktout, (char *)pub_blob,
-					    pub_blob_len);
-		    ssh2_pkt_send(ssh, s->pktout);
-		    logevent("Offered public key");
-
-		    crWaitUntilV(pktin);
-		    if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
-			s->gotit = TRUE;
-			s->type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD;
-			continue;      /* key refused; give up on it */
-		    }
-
-		    logevent("Offer of public key accepted");
-		    /*
-		     * Actually attempt a serious authentication using
-		     * the key.
-		     */
-		    if (ssh2_userkey_encrypted(&ssh->cfg.keyfile, &comment)) {
-			sprintf(s->pwprompt,
-				"Passphrase for key \"%.100s\": ",
-				comment);
-			s->need_pw = TRUE;
-		    } else {
-			s->need_pw = FALSE;
-		    }
-		    if (flags & FLAG_VERBOSE) {
-			c_write_str(ssh, "Authenticating with public key \"");
-			c_write_str(ssh, comment);
-			c_write_str(ssh, "\"\r\n");
-		    }
-		    s->method = AUTH_PUBLICKEY_FILE;
-		}
-	    }
-
-	    if (!s->method && s->can_keyb_inter && !s->kbd_inter_refused &&
-		!s->kbd_inter_running) {
-		s->method = AUTH_KEYBOARD_INTERACTIVE;
-		s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
-
-		ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-		ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
-
 		s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
 		ssh2_pkt_addstring(s->pktout, s->username);
-		ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
-		ssh2_pkt_addstring(s->pktout, "keyboard-interactive");	/* method */
-		ssh2_pkt_addstring(s->pktout, ""); /* lang */
-		ssh2_pkt_addstring(s->pktout, "");
+		ssh2_pkt_addstring(s->pktout, "ssh-connection");
+						/* service requested */
+		ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
+		ssh2_pkt_addbool(s->pktout, FALSE);
+						/* no signature included */
+		ssh2_pkt_addstring(s->pktout, s->publickey_algorithm);
+		ssh2_pkt_addstring_start(s->pktout);
+		ssh2_pkt_addstring_data(s->pktout,
+					(char *)s->publickey_blob,
+					s->publickey_bloblen);
 		ssh2_pkt_send(ssh, s->pktout);
+		logevent("Offered public key");
 
 		crWaitUntilV(pktin);
-		if (pktin->type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
-		    if (pktin->type == SSH2_MSG_USERAUTH_FAILURE)
-			s->gotit = TRUE;
-		    logevent("Keyboard-interactive authentication refused");
-		    s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET;
-		    s->kbd_inter_refused = TRUE; /* don't try it again */
-		    continue;
-		}
-
-		s->kbd_inter_running = TRUE;
-		s->curr_prompt = 0;
-	    }
-
-	    if (s->kbd_inter_running) {
-		s->method = AUTH_KEYBOARD_INTERACTIVE;
-		s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
-
-		ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-		ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
-
-		if (s->curr_prompt == 0) {
-		    /*
-		     * We've got a fresh USERAUTH_INFO_REQUEST.
-		     * Display header data, and start going through
-		     * the prompts.
-		     */
-		    char *name, *inst, *lang;
-		    int name_len, inst_len, lang_len;
-
-		    ssh_pkt_getstring(pktin, &name, &name_len);
-		    ssh_pkt_getstring(pktin, &inst, &inst_len);
-		    ssh_pkt_getstring(pktin, &lang, &lang_len);
-		    if (name_len > 0) {
-			c_write_untrusted(ssh, name, name_len);
-			c_write_str(ssh, "\r\n");
-		    }
-		    if (inst_len > 0) {
-			c_write_untrusted(ssh, inst, inst_len);
-			c_write_str(ssh, "\r\n");
-		    }
-		    s->num_prompts = ssh_pkt_getuint32(pktin);
+		if (pktin->type != SSH2_MSG_USERAUTH_PK_OK) {
+		    /* Key refused. Give up. */
+		    s->gotit = TRUE; /* reconsider message next loop */
+		    s->type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD;
+		    continue; /* process this new message */
 		}
+		logevent("Offer of public key accepted");
 
 		/*
-		 * If there are prompts remaining in the packet,
-		 * display one and get a response.
+		 * Actually attempt a serious authentication using
+		 * the key.
 		 */
-		if (s->curr_prompt < s->num_prompts) {
-		    char *prompt;
-		    int prompt_len;
-
-		    ssh_pkt_getstring(pktin, &prompt, &prompt_len);
-		    if (prompt_len > 0) {
-			static const char trunc[] = "<prompt truncated>: ";
-			static const int prlen = sizeof(s->pwprompt) -
-						 lenof(trunc);
-			if (prompt_len > prlen) {
-			    memcpy(s->pwprompt, prompt, prlen);
-			    strcpy(s->pwprompt + prlen, trunc);
-			} else {
-			    memcpy(s->pwprompt, prompt, prompt_len);
-			    s->pwprompt[prompt_len] = '\0';
+		if (flags & FLAG_VERBOSE) {
+		    c_write_str(ssh, "Authenticating with public key \"");
+		    c_write_str(ssh, s->publickey_comment);
+		    c_write_str(ssh, "\"\r\n");
+		}
+		key = NULL;
+		while (!key) {
+		    const char *error;  /* not live over crReturn */
+		    if (s->publickey_encrypted) {
+			/*
+			 * Get a passphrase from the user.
+			 */
+			int ret; /* need not be kept over crReturn */
+			s->cur_prompt = new_prompts(ssh->frontend);
+			s->cur_prompt->to_server = FALSE;
+			s->cur_prompt->name = dupstr("SSH key passphrase");
+			add_prompt(s->cur_prompt,
+				   dupprintf("Passphrase for key \"%.100s\": ",
+					     s->publickey_comment),
+				   FALSE, SSH_MAX_PASSWORD_LEN);
+			ret = get_userpass_input(s->cur_prompt, NULL, 0);
+			while (ret < 0) {
+			    ssh->send_ok = 1;
+			    crWaitUntilV(!pktin);
+			    ret = get_userpass_input(s->cur_prompt,
+						     in, inlen);
+			    ssh->send_ok = 0;
 			}
+			if (!ret) {
+			    /* Failed to get a passphrase. Terminate. */
+			    free_prompts(s->cur_prompt);
+			    ssh_disconnect(ssh, NULL,
+					   "Unable to authenticate",
+					   SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+					   TRUE);
+			    crStopV;
+			}
+			passphrase =
+			    dupstr(s->cur_prompt->prompts[0]->result);
+			free_prompts(s->cur_prompt);
 		    } else {
-			strcpy(s->pwprompt,
-			       "<server failed to send prompt>: ");
+			passphrase = NULL; /* no passphrase needed */
 		    }
-		    s->echo = ssh2_pkt_getbool(pktin);
-		    s->need_pw = TRUE;
-		} else
-		    s->need_pw = FALSE;
-	    }
 
-	    if (!s->method && s->can_passwd) {
-		s->method = AUTH_PASSWORD;
-		ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
-		ssh->pkt_ctx |= SSH2_PKTCTX_PASSWORD;
-		sprintf(s->pwprompt, "%.90s@%.90s's password: ", s->username,
-			ssh->savedhost);
-		s->need_pw = TRUE;
-	    }
-
-	    if (s->need_pw) {
-		if (ssh_get_line) {
-		    if (!ssh_get_line(s->pwprompt, s->password,
-				      sizeof(s->password), TRUE)) {
-			/*
-			 * get_line failed to get a password (for
-			 * example because one was supplied on the
-			 * 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);
-			crStopV;
+		    /*
+		     * Try decrypting the key.
+		     */
+		    key = ssh2_load_userkey(&ssh->cfg.keyfile, passphrase,
+					    &error);
+		    if (passphrase) {
+			/* burn the evidence */
+			memset(passphrase, 0, strlen(passphrase));
+			sfree(passphrase);
+		    }
+		    if (key == SSH2_WRONG_PASSPHRASE || key == NULL) {
+			if (passphrase &&
+			    (key == SSH2_WRONG_PASSPHRASE)) {
+			    c_write_str(ssh, "Wrong passphrase\r\n");
+			    key = NULL;
+			    /* and loop again */
+			} else {
+			    c_write_str(ssh, "Unable to load private key (");
+			    c_write_str(ssh, error);
+			    c_write_str(ssh, ")\r\n");
+			    key = NULL;
+			    break; /* try something else */
+			}
 		    }
-		} else {
-		    int ret;	       /* need not be saved across crReturn */
-		    c_write_untrusted(ssh, s->pwprompt, strlen(s->pwprompt));
-		    ssh->send_ok = 1;
-
-		    setup_userpass_input(ssh, s->password,
-					 sizeof(s->password), s->echo);
-		    do {
-			crWaitUntilV(!pktin);
-			ret = process_userpass_input(ssh, in, inlen);
-		    } while (ret == 0);
-		    if (ret < 0)
-			cleanup_exit(0);
-		    c_write_str(ssh, "\r\n");
 		}
-	    }
 
-	    if (s->method == AUTH_PUBLICKEY_FILE) {
-		/*
-		 * We have our passphrase. Now try the actual authentication.
-		 */
-		struct ssh2_userkey *key;
-		const char *error = NULL;
-
-		key = ssh2_load_userkey(&ssh->cfg.keyfile, s->password,
-					&error);
-		if (key == SSH2_WRONG_PASSPHRASE || key == NULL) {
-		    if (key == SSH2_WRONG_PASSPHRASE) {
-			c_write_str(ssh, "Wrong passphrase\r\n");
-			s->tried_pubkey_config = FALSE;
-		    } else {
-			c_write_str(ssh, "Unable to load private key (");
-			c_write_str(ssh, error);
-			c_write_str(ssh, ")\r\n");
-			s->tried_pubkey_config = TRUE;
-		    }
-		    /* Send a spurious AUTH_NONE to return to the top. */
-		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-		    ssh2_pkt_addstring(s->pktout, s->username);
-		    ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
-		    ssh2_pkt_addstring(s->pktout, "none");	/* method */
-		    ssh2_pkt_send(ssh, s->pktout);
-		    s->type = AUTH_TYPE_NONE;
-		} else {
+		if (key) {
 		    unsigned char *pkblob, *sigblob, *sigdata;
 		    int pkblob_len, sigblob_len, sigdata_len;
-                    int p;
+		    int p;
 
 		    /*
 		     * We have loaded the private key and the server
@@ -6766,13 +7184,18 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		     */
 		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
 		    ssh2_pkt_addstring(s->pktout, s->username);
-		    ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
-		    ssh2_pkt_addstring(s->pktout, "publickey");	/* method */
+		    ssh2_pkt_addstring(s->pktout, "ssh-connection");
+						    /* service requested */
+		    ssh2_pkt_addstring(s->pktout, "publickey");
+						    /* method */
 		    ssh2_pkt_addbool(s->pktout, TRUE);
+						    /* signature follows */
 		    ssh2_pkt_addstring(s->pktout, key->alg->name);
-		    pkblob = key->alg->public_blob(key->data, &pkblob_len);
+		    pkblob = key->alg->public_blob(key->data,
+						   &pkblob_len);
 		    ssh2_pkt_addstring_start(s->pktout);
-		    ssh2_pkt_addstring_data(s->pktout, (char *)pkblob, pkblob_len);
+		    ssh2_pkt_addstring_data(s->pktout, (char *)pkblob,
+					    pkblob_len);
 
 		    /*
 		     * The data to be signed is:
@@ -6782,20 +7205,23 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		     * followed by everything so far placed in the
 		     * outgoing packet.
 		     */
-		    sigdata_len = s->pktout->length - 5 + 4 + 20;
-                    if (ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)
-                        sigdata_len -= 4;
+		    sigdata_len = s->pktout->length - 5 + 4 +
+			ssh->v2_session_id_len;
+		    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;
+		    p = 0;
+		    if (!(ssh->remote_bugs & BUG_SSH2_PK_SESSIONID)) {
+			PUT_32BIT(sigdata+p, ssh->v2_session_id_len);
+			p += 4;
+		    }
+		    memcpy(sigdata+p, ssh->v2_session_id,
+			   ssh->v2_session_id_len);
+		    p += ssh->v2_session_id_len;
 		    memcpy(sigdata+p, s->pktout->data + 5,
 			   s->pktout->length - 5);
-                    p += s->pktout->length - 5;
-                    assert(p == sigdata_len);
+		    p += s->pktout->length - 5;
+		    assert(p == sigdata_len);
 		    sigblob = key->alg->sign(key->data, (char *)sigdata,
 					     sigdata_len, &sigblob_len);
 		    ssh2_add_sigblob(ssh, s->pktout, pkblob, pkblob_len,
@@ -6808,8 +7234,197 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		    s->type = AUTH_TYPE_PUBLICKEY;
 		    key->alg->freekey(key->data);
 		}
-	    } else if (s->method == AUTH_PASSWORD) {
+
+	    } else if (s->can_keyb_inter && !s->kbd_inter_refused) {
+
+		/*
+		 * Keyboard-interactive authentication.
+		 */
+
+		s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
+
+		ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
+		ssh->pkt_ctx |= SSH2_PKTCTX_KBDINTER;
+
+		s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+		ssh2_pkt_addstring(s->pktout, s->username);
+		ssh2_pkt_addstring(s->pktout, "ssh-connection");
+							/* service requested */
+		ssh2_pkt_addstring(s->pktout, "keyboard-interactive");
+							/* method */
+		ssh2_pkt_addstring(s->pktout, "");	/* lang */
+		ssh2_pkt_addstring(s->pktout, "");	/* submethods */
+		ssh2_pkt_send(ssh, s->pktout);
+
+		crWaitUntilV(pktin);
+		if (pktin->type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
+		    /* Server is not willing to do keyboard-interactive
+		     * at all (or, bizarrely but legally, accepts the
+		     * user without actually issuing any prompts).
+		     * Give up on it entirely. */
+		    s->gotit = TRUE;
+		    if (pktin->type == SSH2_MSG_USERAUTH_FAILURE)
+			logevent("Keyboard-interactive authentication refused");
+		    s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET;
+		    s->kbd_inter_refused = TRUE; /* don't try it again */
+		    continue;
+		}
+
+		/*
+		 * Loop while the server continues to send INFO_REQUESTs.
+		 */
+		while (pktin->type == SSH2_MSG_USERAUTH_INFO_REQUEST) {
+
+		    char *name, *inst, *lang;
+		    int name_len, inst_len, lang_len;
+		    int i;
+
+		    /*
+		     * We've got a fresh USERAUTH_INFO_REQUEST.
+		     * Get the preamble and start building a prompt.
+		     */
+		    ssh_pkt_getstring(pktin, &name, &name_len);
+		    ssh_pkt_getstring(pktin, &inst, &inst_len);
+		    ssh_pkt_getstring(pktin, &lang, &lang_len);
+		    s->cur_prompt = new_prompts(ssh->frontend);
+		    s->cur_prompt->to_server = TRUE;
+		    if (name_len) {
+			/* FIXME: better prefix to distinguish from
+			 * local prompts? */
+			s->cur_prompt->name =
+			    dupprintf("SSH server: %.*s", name_len, name);
+			s->cur_prompt->name_reqd = TRUE;
+		    } else {
+			s->cur_prompt->name =
+			    dupstr("SSH server authentication");
+			s->cur_prompt->name_reqd = FALSE;
+		    }
+		    /* FIXME: ugly to print "Using..." in prompt _every_
+		     * time round. Can this be done more subtly? */
+		    s->cur_prompt->instruction =
+			dupprintf("Using keyboard-interactive authentication.%s%.*s",
+				  inst_len ? "\n" : "", inst_len, inst);
+		    s->cur_prompt->instr_reqd = TRUE;
+
+		    /*
+		     * Get the prompts from the packet.
+		     */
+		    s->num_prompts = ssh_pkt_getuint32(pktin);
+		    for (i = 0; i < s->num_prompts; i++) {
+			char *prompt;
+			int prompt_len;
+			int echo;
+			static char noprompt[] =
+			    "<server failed to send prompt>: ";
+
+			ssh_pkt_getstring(pktin, &prompt, &prompt_len);
+			echo = ssh2_pkt_getbool(pktin);
+			if (!prompt_len) {
+			    prompt = noprompt;
+			    prompt_len = lenof(noprompt)-1;
+			}
+			add_prompt(s->cur_prompt,
+				   dupprintf("%.*s", prompt_len, prompt),
+				   echo, SSH_MAX_PASSWORD_LEN);
+		    }
+
+		    /*
+		     * Get the user's responses.
+		     */
+		    if (s->num_prompts) {
+			int ret; /* not live over crReturn */
+			ret = get_userpass_input(s->cur_prompt, NULL, 0);
+			while (ret < 0) {
+			    ssh->send_ok = 1;
+			    crWaitUntilV(!pktin);
+			    ret = get_userpass_input(s->cur_prompt, in, inlen);
+			    ssh->send_ok = 0;
+			}
+			if (!ret) {
+			    /*
+			     * Failed to get responses. Terminate.
+			     */
+			    free_prompts(s->cur_prompt);
+			    ssh_disconnect(ssh, NULL, "Unable to authenticate",
+					   SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+					   TRUE);
+			    crStopV;
+			}
+		    }
+
+		    /*
+		     * Send the responses to the server.
+		     */
+		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
+		    s->pktout->forcepad = 256;
+		    ssh2_pkt_adduint32(s->pktout, s->num_prompts);
+		    for (i=0; i < s->num_prompts; i++) {
+			dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
+			ssh2_pkt_addstring(s->pktout,
+					   s->cur_prompt->prompts[i]->result);
+			end_log_omission(ssh, s->pktout);
+		    }
+		    ssh2_pkt_send(ssh, s->pktout);
+
+		    /*
+		     * Get the next packet in case it's another
+		     * INFO_REQUEST.
+		     */
+		    crWaitUntilV(pktin);
+
+		}
+
+		/*
+		 * We should have SUCCESS or FAILURE now.
+		 */
+		s->gotit = TRUE;
+
+	    } else if (s->can_passwd) {
+
+		/*
+		 * Plain old password authentication.
+		 */
+		int ret; /* not live over crReturn */
+		int changereq_first_time; /* not live over crReturn */
+
+		ssh->pkt_ctx &= ~SSH2_PKTCTX_AUTH_MASK;
+		ssh->pkt_ctx |= SSH2_PKTCTX_PASSWORD;
+
+		s->cur_prompt = new_prompts(ssh->frontend);
+		s->cur_prompt->to_server = TRUE;
+		s->cur_prompt->name = dupstr("SSH password");
+		add_prompt(s->cur_prompt, dupprintf("%.90s@%.90s's password: ",
+						    s->username,
+						    ssh->savedhost),
+			   FALSE, SSH_MAX_PASSWORD_LEN);
+
+		ret = get_userpass_input(s->cur_prompt, NULL, 0);
+		while (ret < 0) {
+		    ssh->send_ok = 1;
+		    crWaitUntilV(!pktin);
+		    ret = get_userpass_input(s->cur_prompt, in, inlen);
+		    ssh->send_ok = 0;
+		}
+		if (!ret) {
+		    /*
+		     * Failed to get responses. Terminate.
+		     */
+		    free_prompts(s->cur_prompt);
+		    ssh_disconnect(ssh, NULL, "Unable to authenticate",
+				   SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+				   TRUE);
+		    crStopV;
+		}
 		/*
+		 * Squirrel away the password. (We may need it later if
+		 * asked to change it.)
+		 */
+		s->password = dupstr(s->cur_prompt->prompts[0]->result);
+		free_prompts(s->cur_prompt);
+
+		/*
+		 * Send the password packet.
+		 *
 		 * We pad out the password packet to 256 bytes to make
 		 * it harder for an attacker to find the length of the
 		 * user's password.
@@ -6821,65 +7436,175 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 		s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
 		s->pktout->forcepad = 256;
 		ssh2_pkt_addstring(s->pktout, s->username);
-		ssh2_pkt_addstring(s->pktout, "ssh-connection");	/* service requested */
+		ssh2_pkt_addstring(s->pktout, "ssh-connection");
+							/* service requested */
 		ssh2_pkt_addstring(s->pktout, "password");
 		ssh2_pkt_addbool(s->pktout, FALSE);
 		dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
 		ssh2_pkt_addstring(s->pktout, s->password);
-		memset(s->password, 0, sizeof(s->password));
 		end_log_omission(ssh, s->pktout);
 		ssh2_pkt_send(ssh, s->pktout);
 		logevent("Sent password");
 		s->type = AUTH_TYPE_PASSWORD;
-	    } else if (s->method == AUTH_KEYBOARD_INTERACTIVE) {
-		if (s->curr_prompt == 0) {
-		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
+
+		/*
+		 * Wait for next packet, in case it's a password change
+		 * request.
+		 */
+		crWaitUntilV(pktin);
+		changereq_first_time = TRUE;
+
+		while (pktin->type == SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ) {
+
+		    /* 
+		     * We're being asked for a new password
+		     * (perhaps not for the first time).
+		     * Loop until the server accepts it.
+		     */
+
+		    int got_new = FALSE; /* not live over crReturn */
+		    char *prompt;   /* not live over crReturn */
+		    int prompt_len; /* not live over crReturn */
+		    
+		    {
+			char *msg;
+			if (changereq_first_time)
+			    msg = "Server requested password change";
+			else
+			    msg = "Server rejected new password";
+			logevent(msg);
+			c_write_str(ssh, msg);
+			c_write_str(ssh, "\r\n");
+		    }
+
+		    ssh_pkt_getstring(pktin, &prompt, &prompt_len);
+
+		    s->cur_prompt = new_prompts(ssh->frontend);
+		    s->cur_prompt->to_server = TRUE;
+		    s->cur_prompt->name = dupstr("New SSH password");
+		    s->cur_prompt->instruction =
+			dupprintf("%.*s", prompt_len, prompt);
+		    s->cur_prompt->instr_reqd = TRUE;
+		    add_prompt(s->cur_prompt, dupstr("Enter new password: "),
+			       FALSE, SSH_MAX_PASSWORD_LEN);
+		    add_prompt(s->cur_prompt, dupstr("Confirm new password: "),
+			       FALSE, SSH_MAX_PASSWORD_LEN);
+
+		    /*
+		     * Loop until the user manages to enter the same
+		     * password twice.
+		     */
+		    while (!got_new) {
+
+			ret = get_userpass_input(s->cur_prompt, NULL, 0);
+			while (ret < 0) {
+			    ssh->send_ok = 1;
+			    crWaitUntilV(!pktin);
+			    ret = get_userpass_input(s->cur_prompt, in, inlen);
+			    ssh->send_ok = 0;
+			}
+			if (!ret) {
+			    /*
+			     * Failed to get responses. Terminate.
+			     */
+			    /* burn the evidence */
+			    free_prompts(s->cur_prompt);
+			    memset(s->password, 0, strlen(s->password));
+			    sfree(s->password);
+			    ssh_disconnect(ssh, NULL, "Unable to authenticate",
+					   SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER,
+					   TRUE);
+			    crStopV;
+			}
+
+			/*
+			 * Check the two passwords match.
+			 */
+			got_new = (strcmp(s->cur_prompt->prompts[0]->result,
+					  s->cur_prompt->prompts[1]->result)
+				   == 0);
+			if (!got_new)
+			    /* They don't. Silly user. */
+			    c_write_str(ssh, "Passwords do not match\r\n");
+
+		    }
+
+		    /*
+		     * Send the new password (along with the old one).
+		     * (see above for padding rationale)
+		     */
+		    s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
 		    s->pktout->forcepad = 256;
-		    ssh2_pkt_adduint32(s->pktout, s->num_prompts);
-		}
-		if (s->need_pw) {      /* only add pw if we just got one! */
+		    ssh2_pkt_addstring(s->pktout, s->username);
+		    ssh2_pkt_addstring(s->pktout, "ssh-connection");
+							/* service requested */
+		    ssh2_pkt_addstring(s->pktout, "password");
+		    ssh2_pkt_addbool(s->pktout, TRUE);
 		    dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
 		    ssh2_pkt_addstring(s->pktout, s->password);
-		    memset(s->password, 0, sizeof(s->password));
+		    ssh2_pkt_addstring(s->pktout,
+				       s->cur_prompt->prompts[0]->result);
+		    free_prompts(s->cur_prompt);
 		    end_log_omission(ssh, s->pktout);
-		    s->curr_prompt++;
-		}
-		if (s->curr_prompt >= s->num_prompts) {
 		    ssh2_pkt_send(ssh, s->pktout);
-		} else {
+		    logevent("Sent new password");
+		    
 		    /*
-		     * If there are prompts remaining, we set
-		     * `gotit' so that we won't attempt to get
-		     * another packet. Then we go back round the
-		     * loop and will end up retrieving another
-		     * prompt out of the existing packet. Funky or
-		     * what?
+		     * Now see what the server has to say about it.
+		     * (If it's CHANGEREQ again, it's not happy with the
+		     * new password.)
 		     */
-		    s->gotit = TRUE;
+		    crWaitUntilV(pktin);
+		    changereq_first_time = FALSE;
+
 		}
-		s->type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
+
+		/*
+		 * We need to reexamine the current pktin at the top
+		 * of the loop. Either:
+		 *  - we weren't asked to change password at all, in
+		 *    which case it's a SUCCESS or FAILURE with the
+		 *    usual meaning
+		 *  - we sent a new password, and the server was
+		 *    either OK with it (SUCCESS or FAILURE w/partial
+		 *    success) or unhappy with the _old_ password
+		 *    (FAILURE w/o partial success)
+		 * In any of these cases, we go back to the top of
+		 * the loop and start again.
+		 */
+		s->gotit = TRUE;
+
+		/*
+		 * We don't need the old password any more, in any
+		 * case. Burn the evidence.
+		 */
+		memset(s->password, 0, strlen(s->password));
+		sfree(s->password);
+
 	    } 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;
+
+    /* Clear up various bits and pieces from authentication. */
+    if (s->publickey_blob) {
+	sfree(s->publickey_blob);
+	sfree(s->publickey_comment);
+    }
+    if (s->agent_response)
+	sfree(s->agent_response);
 
     /*
-     * 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);
@@ -6963,7 +7688,16 @@ 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);
 
@@ -7032,9 +7766,11 @@ 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);
@@ -7139,6 +7875,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	} else {
 	    subsys = ssh->cfg.ssh_subsys;
 	    cmd = ssh->cfg.remote_cmd_ptr;
+	    if (!cmd) cmd = ssh->cfg.remote_cmd;
 	}
 
 	s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
@@ -7223,30 +7960,8 @@ 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);
 	}
     }
 
@@ -7254,7 +7969,7 @@ 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)
 {
@@ -7288,7 +8003,7 @@ static void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
 static void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
 {
     /* log the debug message */
-    char *buf, *msg;
+    char *msg;
     int msglen;
     int always_display;
 
@@ -7296,9 +8011,7 @@ static void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
     always_display = ssh2_pkt_getbool(pktin);
     ssh_pkt_getstring(pktin, &msg, &msglen);
 
-    buf = dupprintf("Remote debug message: %.*s", msglen, msg);
-    logevent(buf);
-    sfree(buf);
+    logeventf(ssh, "Remote debug message: %.*s", msglen, msg);
 }
 
 static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
@@ -7314,7 +8027,7 @@ 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)
 {
@@ -7368,7 +8081,7 @@ 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;
 }
 
@@ -7376,6 +8089,9 @@ 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);
@@ -7454,6 +8170,7 @@ 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;
@@ -7479,6 +8196,8 @@ static const 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->v_c = NULL;
+    ssh->v_s = NULL;
     ssh->mainchan = NULL;
     ssh->throttled_all = 0;
     ssh->v1_stdout_throttling = 0;
@@ -7487,6 +8206,8 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->queueing = FALSE;
     ssh->qhead = ssh->qtail = NULL;
     ssh->deferred_rekey_reason = NULL;
+    bufchain_init(&ssh->queued_incoming_data);
+    ssh->frozen = FALSE;
 
     *backend_handle = ssh;
 
@@ -7604,6 +8325,8 @@ static void ssh_free(void *handle)
     sfree(ssh->do_ssh1_login_state);
     sfree(ssh->do_ssh2_transport_state);
     sfree(ssh->do_ssh2_authconn_state);
+    sfree(ssh->v_c);
+    sfree(ssh->v_s);
     if (ssh->crcda_ctx) {
 	crcda_free_context(ssh->crcda_ctx);
 	ssh->crcda_ctx = NULL;
@@ -7613,6 +8336,7 @@ static void ssh_free(void *handle)
     expire_timer_context(ssh);
     if (ssh->pinger)
 	pinger_free(ssh->pinger);
+    bufchain_clear(&ssh->queued_incoming_data);
     sfree(ssh);
 
     random_unref();
@@ -7628,7 +8352,8 @@ 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) {
@@ -7675,7 +8400,7 @@ 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)
 {
@@ -7832,7 +8557,7 @@ 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').
  */
@@ -7857,6 +8582,7 @@ 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) {
@@ -7878,7 +8604,7 @@ 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);
@@ -7988,8 +8714,11 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
 	 * too much hassle to keep track, and partly I'm not
 	 * convinced the server should be told details like that
 	 * about my local network configuration.
+	 * The "originator IP address" is syntactically a numeric
+	 * IP address, and some servers (e.g., Tectia) get upset
+	 * if it doesn't match this syntax.
 	 */
-	ssh2_pkt_addstring(pktout, "client-side-connection");
+	ssh2_pkt_addstring(pktout, "0.0.0.0");
 	ssh2_pkt_adduint32(pktout, 0);
 	ssh2_pkt_send(ssh, pktout);
     }