Add support for RFC 4432 RSA key exchange, the patch for which has been
[u/mdw/putty] / ssh.c
diff --git a/ssh.c b/ssh.c
index 51e2518..64a069e 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -1,7 +1,13 @@
+/*
+ * SSH backend.
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #include <assert.h>
+#include <limits.h>
+#include <signal.h>
 
 #include "putty.h"
 #include "tree234.h"
@@ -77,6 +83,9 @@
 #define SSH2_MSG_KEX_DH_GEX_GROUP                 31   /* 0x1f */
 #define SSH2_MSG_KEX_DH_GEX_INIT                  32   /* 0x20 */
 #define SSH2_MSG_KEX_DH_GEX_REPLY                 33   /* 0x21 */
+#define SSH2_MSG_KEXRSA_PUBKEY                    30    /* 0x1e */
+#define SSH2_MSG_KEXRSA_SECRET                    31    /* 0x1f */
+#define SSH2_MSG_KEXRSA_DONE                      32    /* 0x20 */
 #define SSH2_MSG_USERAUTH_REQUEST                 50   /* 0x32 */
 #define SSH2_MSG_USERAUTH_FAILURE                 51   /* 0x33 */
 #define SSH2_MSG_USERAUTH_SUCCESS                 52   /* 0x34 */
  */
 #define SSH2_PKTCTX_DHGROUP          0x0001
 #define SSH2_PKTCTX_DHGEX            0x0002
+#define SSH2_PKTCTX_RSAKEX           0x0004
 #define SSH2_PKTCTX_KEX_MASK         0x000F
 #define SSH2_PKTCTX_PUBLICKEY        0x0010
 #define SSH2_PKTCTX_PASSWORD         0x0020
 
 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 +176,110 @@ 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)
@@ -229,6 +343,9 @@ static char *ssh2_pkt_type(int pkt_ctx, int type)
     translatec(SSH2_MSG_KEX_DH_GEX_GROUP, SSH2_PKTCTX_DHGEX);
     translatec(SSH2_MSG_KEX_DH_GEX_INIT, SSH2_PKTCTX_DHGEX);
     translatec(SSH2_MSG_KEX_DH_GEX_REPLY, SSH2_PKTCTX_DHGEX);
+    translatec(SSH2_MSG_KEXRSA_PUBKEY, SSH2_PKTCTX_RSAKEX);
+    translatec(SSH2_MSG_KEXRSA_SECRET, SSH2_PKTCTX_RSAKEX);
+    translatec(SSH2_MSG_KEXRSA_DONE, SSH2_PKTCTX_RSAKEX);
     translate(SSH2_MSG_USERAUTH_REQUEST);
     translate(SSH2_MSG_USERAUTH_FAILURE);
     translate(SSH2_MSG_USERAUTH_SUCCESS);
@@ -256,18 +373,6 @@ 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 +424,19 @@ 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 +452,18 @@ 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 +472,16 @@ 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 +529,7 @@ 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 +565,11 @@ 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 +581,15 @@ 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 +624,15 @@ 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 +695,8 @@ 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 +721,8 @@ 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;
@@ -645,8 +737,10 @@ struct ssh_tag {
 
     tree234 *channels;                /* indexed by local id */
     struct ssh_channel *mainchan;      /* primary session channel */
+    int ncmode;                               /* is primary channel direct-tcpip? */
     int exitcode;
     int close_expected;
+    int clean_exit;
 
     tree234 *rportfwds, *portfwds;
 
@@ -674,13 +768,7 @@ 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 +798,7 @@ 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 +814,23 @@ 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 +903,29 @@ 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 +1056,28 @@ 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] == '\n' || (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 +1094,7 @@ 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 +1280,8 @@ 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 +1395,9 @@ 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 +1410,10 @@ 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 +1422,106 @@ 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);
+
+    if (offset_p) *offset_p = pktoffs;
+    return biglen + 4;         /* len(length+padding+type+data+CRC) */
+}
 
-    return biglen + 4;
+static int s_write(Ssh ssh, void *data, int len)
+{
+    log_packet(ssh->logctx, PKT_OUTGOING, -1, NULL, data, len, 0, NULL);
+    return sk_write(ssh->s, (char *)data, len);
 }
 
 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 = s_write(ssh, 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;
+       char *sargp;
+       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;
+           sargp = va_arg(ap, char *);
+           ssh_pkt_addstring(pkt, sargp);
            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 +1534,6 @@ 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 +1542,21 @@ 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 +1581,98 @@ 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)
-{
-    ssh2_pkt_adddata(pkt, &byte, 1);
-}
-static struct Packet *ssh2_pkt_init(int pkt_type)
+static void ssh_pkt_addbyte(struct Packet *pkt, unsigned char byte)
 {
-    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, unsigned 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 +1688,42 @@ 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 +1734,7 @@ 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;
@@ -1732,17 +1818,34 @@ 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);
+    backlog = s_write(ssh, pkt->data, len);
     if (backlog > SSH_MAX_BACKLOG)
        ssh_throttle_all(ssh, 1, backlog);
 
@@ -1756,11 +1859,22 @@ 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_addstring_start(ipkt);
+       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 +1888,7 @@ 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)
 {
@@ -1800,7 +1914,6 @@ static void ssh2_pkt_send(Ssh ssh, struct Packet *pkt)
        ssh2_pkt_send_noqueue(ssh, pkt);
 }
 
-#if 0 /* disused */
 /*
  * Either queue or defer a packet, depending on whether queueing is
  * set.
@@ -1810,13 +1923,12 @@ 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
@@ -1830,8 +1942,7 @@ static void ssh2_pkt_defer(Ssh ssh, struct Packet *pkt)
 static void ssh_pkt_defersend(Ssh ssh)
 {
     int backlog;
-    backlog = sk_write(ssh->s, (char *)ssh->deferred_send_data,
-                      ssh->deferred_len);
+    backlog = s_write(ssh, ssh->deferred_send_data, ssh->deferred_len);
     ssh->deferred_len = ssh->deferred_size = 0;
     sfree(ssh->deferred_send_data);
     ssh->deferred_send_data = NULL;
@@ -1847,7 +1958,75 @@ static void ssh_pkt_defersend(Ssh ssh)
 }
 
 /*
- * Send all queued SSH2 packets. We send them by means of
+ * Send a packet whose length needs to be disguised (typically
+ * passwords or keyboard-interactive responses).
+ */
+static void ssh2_pkt_send_with_padding(Ssh ssh, struct Packet *pkt,
+                                      int padsize)
+{
+#if 0
+    if (0) {
+       /*
+        * The simplest way to do this is to adjust the
+        * variable-length padding field in the outgoing packet.
+        * 
+        * Currently compiled out, because some Cisco SSH servers
+        * don't like excessively padded packets (bah, why's it
+        * always Cisco?)
+        */
+       pkt->forcepad = padsize;
+       ssh2_pkt_send(ssh, pkt);
+    } else
+#endif
+    {
+       /*
+        * If we can't do that, however, an alternative approach is
+        * to use the pkt_defer mechanism to bundle the packet
+        * tightly together with an SSH_MSG_IGNORE such that their
+        * combined length is a constant. So first we construct the
+        * final form of this packet and defer its sending.
+        */
+       ssh2_pkt_defer(ssh, pkt);
+
+       /*
+        * Now construct an SSH_MSG_IGNORE which includes a string
+        * that's an exact multiple of the cipher block size. (If
+        * the cipher is NULL so that the block size is
+        * unavailable, we don't do this trick at all, because we
+        * gain nothing by it.)
+        */
+       if (ssh->cscipher) {
+           int stringlen, i;
+
+           stringlen = (256 - ssh->deferred_len);
+           stringlen += ssh->cscipher->blksize - 1;
+           stringlen -= (stringlen % ssh->cscipher->blksize);
+           if (ssh->cscomp) {
+               /*
+                * Temporarily disable actual compression, so we
+                * can guarantee to get this string exactly the
+                * length we want it. The compression-disabling
+                * routine should return an integer indicating how
+                * many bytes we should adjust our string length
+                * by.
+                */
+               stringlen -=
+                   ssh->cscomp->disable_compression(ssh->cs_comp_ctx);
+           }
+           pkt = ssh2_pkt_init(SSH2_MSG_IGNORE);
+           ssh2_pkt_addstring_start(pkt);
+           for (i = 0; i < stringlen; i++) {
+               char c = (char) random_byte();
+               ssh2_pkt_addstring_data(pkt, &c, 1);
+           }
+           ssh2_pkt_defer(ssh, pkt);
+       }
+       ssh_pkt_defersend(ssh);
+    }
+}
+
+/*
+ * 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 +2037,7 @@ 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 +2057,17 @@ 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 +2158,7 @@ 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
@@ -2063,6 +2242,13 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
 
     ssh->remote_bugs = 0;
 
+    /*
+     * General notes on server version strings:
+     *  - Not all servers reporting "Cisco-1.25" have all the bugs listed
+     *    here -- in particular, we've heard of one that's perfectly happy
+     *    with SSH1_MSG_IGNOREs -- but this string never seems to change,
+     *    so we can't distinguish them.
+     */
     if (ssh->cfg.sshbug_ignore1 == FORCE_ON ||
        (ssh->cfg.sshbug_ignore1 == AUTO &&
         (!strcmp(imp, "1.2.18") || !strcmp(imp, "1.2.19") ||
@@ -2075,7 +2261,7 @@ 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 +2273,7 @@ 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 +2285,7 @@ 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 +2298,7 @@ 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 +2311,7 @@ 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 +2319,37 @@ 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 +2390,20 @@ 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 +2433,7 @@ 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 +2477,28 @@ 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);
@@ -2322,8 +2506,10 @@ static int do_ssh_init(Ssh ssh, unsigned char c)
         }
         logeventf(ssh, "We claim version: %.*s",
                   strcspn(verstring, "\015\012"), verstring);
-       sk_write(ssh->s, verstring, strlen(verstring));
+       s_write(ssh, 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);
@@ -2337,8 +2523,57 @@ 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;
+
+    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)
 {
+    /* Log raw data, if we're in that mode. */
+    log_packet(ssh->logctx, PKT_INCOMING, -1, NULL, data, datalen, 0, NULL);
+
     crBegin(ssh->ssh_gotdata_crstate);
 
     /*
@@ -2364,18 +2599,29 @@ 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 +2629,11 @@ 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 +2643,11 @@ 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 +2656,26 @@ 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 +2694,7 @@ 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 +2703,23 @@ 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 (ssh->close_expected && ssh->clean_exit && ssh->exitcode < 0)
+       ssh->exitcode = 0;
+
     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 +2766,6 @@ 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 +2809,9 @@ 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 +2850,35 @@ 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)
@@ -2699,9 +2909,42 @@ static void ssh_agentf_callback(void *cv, void *reply, int replylen)
 }
 
 /*
- * Handle the key exchange and user authentication phases.
+ * Client-initiated disconnection. Send a DISCONNECT if `wire_reason'
+ * non-NULL, otherwise just close the connection. `client_reason' == NULL
+ * => log `wire_reason'.
  */
-static int do_ssh1_login(Ssh ssh, unsigned char *in, int inlen,
+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,
                         struct Packet *pktin)
 {
     int i, j, ret;
@@ -2719,9 +2962,9 @@ 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 +2975,7 @@ 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 +2993,14 @@ 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 +3039,13 @@ 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 +3057,33 @@ 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 +3102,7 @@ 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 +3119,7 @@ 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 +3135,7 @@ 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 +3145,26 @@ 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 +3226,33 @@ 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 +3260,14 @@ 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 +3280,51 @@ 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 +3356,9 @@ 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 +3391,17 @@ 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 +3492,156 @@ 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()");
+                   got_passphrase = FALSE;   /* placate optimisers */
+               }
+           }
+
+           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 +3659,7 @@ 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 +3667,23 @@ 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 +3701,7 @@ 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 +3709,32 @@ 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 +3742,153 @@ 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 can't deal with SSH1_MSG_IGNORE, at
+            * least in this context. 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.
+            * 
+            * A few servers can deal with neither SSH1_MSG_IGNORE
+            * here _nor_ a padded password string.
+            * For these servers 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) &&
+               !(ssh->remote_bugs & BUG_NEEDS_SSH1_PLAIN_PASSWORD)) {
                /*
-                * 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 is believed unable to cope with
+                * any of our password camouflage methods.
+                */
+               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 +3900,12 @@ 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 +3915,8 @@ 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 +3953,8 @@ 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 +3963,7 @@ 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 +3980,8 @@ 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 +4133,13 @@ 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 +4147,14 @@ 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 +4170,8 @@ 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 +4254,7 @@ 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 +4267,9 @@ 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 +4316,7 @@ 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 +4328,7 @@ 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 +4384,7 @@ 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 +4499,7 @@ 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 +4516,17 @@ 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);
@@ -4304,7 +4654,7 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
            /* Data for an agent message. Buffer it. */
            while (len > 0) {
                if (c->u.a.lensofar < 4) {
-                   unsigned int l = min(4 - c->u.a.lensofar, len);
+                   unsigned int l = min(4 - c->u.a.lensofar, (unsigned)len);
                    memcpy(c->u.a.msglen + c->u.a.lensofar, p,
                           l);
                    p += l;
@@ -4321,7 +4671,7 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
                if (c->u.a.lensofar >= 4 && len > 0) {
                    unsigned int l =
                        min(c->u.a.totallen - c->u.a.lensofar,
-                           len);
+                           (unsigned)len);
                    memcpy(c->u.a.message + c->u.a.lensofar, p,
                           l);
                    p += l;
@@ -4352,11 +4702,8 @@ 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 +4712,30 @@ 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 +4780,23 @@ 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 +4818,26 @@ 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 +4879,14 @@ 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 +4944,15 @@ 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)
@@ -4582,7 +4965,7 @@ static void ssh1_msg_disconnect(Ssh ssh, struct Packet *pktin)
     bombout(("Server sent disconnect message:\n\"%.*s\"", msglen, msg));
 }
 
-void ssh_msg_ignore(Ssh ssh, struct Packet *pktin)
+static void ssh_msg_ignore(Ssh ssh, struct Packet *pktin)
 {
     /* Do nothing, because we're ignoring it! Duhh. */
 }
@@ -4681,40 +5064,45 @@ 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;
@@ -4724,17 +5112,21 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
        const struct ssh_mac *scmac_tobe;
        const struct ssh_compress *cscomp_tobe;
        const struct ssh_compress *sccomp_tobe;
-       char *hostkeydata, *sigdata, *keystr, *fingerprint;
-       int hostkeylen, siglen;
+       char *hostkeydata, *sigdata, *rsakeydata, *keystr, *fingerprint;
+       int hostkeylen, siglen, rsakeylen;
        void *hkey;                    /* actual host key */
-       unsigned char exchange_hash[20];
+       void *rsakey;                  /* for RSA kex */
+       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 +5169,11 @@ 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_RSA:
+               s->preferred_kex[s->n_preferred_kex++] =
+                   &ssh_rsa_kex;
+               break;
+             case KEX_WARN:
                /* Flag for later. Don't bother if it's the last in
                 * the list. */
                if (i < KEX_MAX - 1) {
@@ -4807,6 +5203,9 @@ 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 +5245,14 @@ 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 +5333,22 @@ 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 +5362,27 @@ 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 +5394,7 @@ 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 +5402,13 @@ 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 +5417,8 @@ 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 +5427,10 @@ 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 +5439,8 @@ 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)",
@@ -5097,10 +5482,98 @@ 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 */
-           crWaitUntil(pktin);                /* Ignore packet */
-    }
+       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 */
+    }
+
+    if (ssh->kex->main_type == KEXTYPE_DH) {
+       /* XXX The lines below should be reindented before this is committed.*/
     /*
      * Work out the number of bits of key we will need from the key
      * exchange. We start with the maximum key length of either
@@ -5113,10 +5586,10 @@ 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
@@ -5157,21 +5630,26 @@ 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->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
     s->f = ssh2_pkt_getmp(pktin);
     if (!s->f) {
        bombout(("unable to parse key exchange reply packet"));
@@ -5181,29 +5659,143 @@ 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);
 
     dh_cleanup(ssh->kex_ctx);
+    freebn(s->f);
+    if (!ssh->kex->pdata) {
+        freebn(s->g);
+       freebn(s->p);
+    }
+        /* XXX end incorrectly-indented section */
+    } else {
+       logeventf(ssh, "Doing RSA key exchange with hash %s",
+                 ssh->kex->hash->text_name);
+       ssh->pkt_ctx |= SSH2_PKTCTX_RSAKEX;
+        /*
+         * RSA key exchange. First expect a KEXRSA_PUBKEY packet
+         * from the server.
+         */
+        crWaitUntil(pktin);
+        if (pktin->type != SSH2_MSG_KEXRSA_PUBKEY) {
+            bombout(("expected RSA public key packet from server"));
+            crStop(0);
+        }
+
+        ssh_pkt_getstring(pktin, &s->hostkeydata, &s->hostkeylen);
+        hash_string(ssh->kex->hash, ssh->exhash,
+                   s->hostkeydata, s->hostkeylen);
+       s->hkey = ssh->hostkey->newkey(s->hostkeydata, s->hostkeylen);
+
+        {
+            char *keydata;
+            ssh_pkt_getstring(pktin, &keydata, &s->rsakeylen);
+            s->rsakeydata = snewn(s->rsakeylen, char);
+            memcpy(s->rsakeydata, keydata, s->rsakeylen);
+        }
+
+        s->rsakey = ssh_rsakex_newkey(s->rsakeydata, s->rsakeylen);
+        if (!s->rsakey) {
+            sfree(s->rsakeydata);
+            bombout(("unable to parse RSA public key from server"));
+            crStop(0);
+        }
+
+        hash_string(ssh->kex->hash, ssh->exhash, s->rsakeydata, s->rsakeylen);
+
+        /*
+         * Next, set up a shared secret K, of precisely KLEN -
+         * 2*HLEN - 49 bits, where KLEN is the bit length of the
+         * RSA key modulus and HLEN is the bit length of the hash
+         * we're using.
+         */
+        {
+            int klen = ssh_rsakex_klen(s->rsakey);
+            int nbits = klen - (2*ssh->kex->hash->hlen*8 + 49);
+            int i, byte = 0;
+            unsigned char *kstr1, *kstr2, *outstr;
+            int kstr1len, kstr2len, outstrlen;
+
+            s->K = bn_power_2(nbits - 1);
+
+            for (i = 0; i < nbits; i++) {
+                if ((i & 7) == 0) {
+                    byte = random_byte();
+                }
+                bignum_set_bit(s->K, i, (byte >> (i & 7)) & 1);
+            }
+
+            /*
+             * Encode this as an mpint.
+             */
+            kstr1 = ssh2_mpint_fmt(s->K, &kstr1len);
+            kstr2 = snewn(kstr2len = 4 + kstr1len, unsigned char);
+            PUT_32BIT(kstr2, kstr1len);
+            memcpy(kstr2 + 4, kstr1, kstr1len);
+
+            /*
+             * Encrypt it with the given RSA key.
+             */
+            outstrlen = (klen + 7) / 8;
+            outstr = snewn(outstrlen, unsigned char);
+            ssh_rsakex_encrypt(ssh->kex->hash, kstr2, kstr2len,
+                              outstr, outstrlen, s->rsakey);
+
+            /*
+             * And send it off in a return packet.
+             */
+            s->pktout = ssh2_pkt_init(SSH2_MSG_KEXRSA_SECRET);
+            ssh2_pkt_addstring_start(s->pktout);
+            ssh2_pkt_addstring_data(s->pktout, outstr, outstrlen);
+            ssh2_pkt_send_noqueue(ssh, s->pktout);
+
+           hash_string(ssh->kex->hash, ssh->exhash, outstr, outstrlen);
+
+            sfree(kstr2);
+            sfree(kstr1);
+            sfree(outstr);
+        }
+
+        ssh_rsakex_freekey(s->rsakey);
+
+        crWaitUntil(pktin);
+        if (pktin->type != SSH2_MSG_KEXRSA_DONE) {
+            sfree(s->rsakeydata);
+            bombout(("expected signature packet from server"));
+            crStop(0);
+        }
+
+        ssh_pkt_getstring(pktin, &s->sigdata, &s->siglen);
+
+        sfree(s->rsakeydata);
+    }
+
+    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);
+
     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 +5806,29 @@ 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 +5843,11 @@ 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 +5882,21 @@ 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 +5948,21 @@ 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);
@@ -5344,14 +5973,9 @@ static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                  ssh->sccomp->text_name);
 
     /*
-     * Free key exchange data.
+     * Free shared secret.
      */
-    freebn(s->f);
     freebn(s->K);
-    if (ssh->kex == &ssh_diffiehellman_gex) {
-       freebn(s->g);
-       freebn(s->p);
-    }
 
     /*
      * Key exchange is over. Loop straight back round if we have a
@@ -5382,7 +6006,7 @@ 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 +6058,7 @@ 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 +6067,7 @@ 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 +6100,34 @@ static int ssh2_try_send(struct ssh_channel *c)
     return bufchain_size(&c->v.v2.outbuffer);
 }
 
+static void ssh2_try_send_and_unthrottle(struct ssh_channel *c)
+{
+    int bufsize;
+    if (c->closes)
+       return;                        /* don't send on closing channels */
+    bufsize = ssh2_try_send(c);
+    if (bufsize == 0) {
+       switch (c->type) {
+         case CHAN_MAINSESSION:
+           /* stdin need not receive an unthrottle
+            * notification since it will be polled */
+           break;
+         case CHAN_X11:
+           x11_unthrottle(c->u.x11.s);
+           break;
+         case CHAN_AGENT:
+           /* agent sockets are request/response and need no
+            * buffer management */
+           break;
+         case CHAN_SOCKDATA:
+           pfd_unthrottle(c->u.pfd.s);
+           break;
+       }
+    }
+}
+
 /*
- * Potentially enlarge the window on an SSH2 channel.
+ * Potentially enlarge the window on an SSH-2 channel.
  */
 static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
 {
@@ -5514,8 +6164,10 @@ 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)
@@ -5550,7 +6202,8 @@ static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
          case CHAN_AGENT:
            while (length > 0) {
                if (c->u.a.lensofar < 4) {
-                   unsigned int l = min(4 - c->u.a.lensofar, length);
+                   unsigned int l = min(4 - c->u.a.lensofar,
+                                        (unsigned)length);
                    memcpy(c->u.a.msglen + c->u.a.lensofar,
                           data, l);
                    data += l;
@@ -5567,7 +6220,7 @@ static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
                if (c->u.a.lensofar >= 4 && length > 0) {
                    unsigned int l =
                        min(c->u.a.totallen - c->u.a.lensofar,
-                           length);
+                           (unsigned)length);
                    memcpy(c->u.a.message + c->u.a.lensofar,
                           data, l);
                    data += l;
@@ -5669,12 +6322,10 @@ 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 +6333,7 @@ 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 +6381,6 @@ 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 +6392,8 @@ 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 +6420,10 @@ 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;
     }
 
@@ -5857,11 +6489,13 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
                        is_plausible = FALSE;
                }
            }
+           ssh->exitcode = 128;       /* means `unknown signal' */
            if (is_plausible) {
                if (is_int) {
                    /* Old non-standard OpenSSH. */
                    int signum = ssh_pkt_getuint32(pktin);
                    fmt_sig = dupprintf(" %d", signum);
+                   ssh->exitcode = 128 + signum;
                } else {
                    /* As per the drafts. */
                    char *sig;
@@ -5873,6 +6507,60 @@ static void ssh2_msg_channel_request(Ssh ssh, struct Packet *pktin)
                        fmt_sig = dupprintf(" \"%.*s\"",
                                            siglen, sig);
                    }
+
+                   /*
+                    * Really hideous method of translating the
+                    * signal description back into a locally
+                    * meaningful number.
+                    */
+
+                   if (0)
+                       ;
+#define TRANSLATE_SIGNAL(s) \
+    else if (siglen == lenof(#s)-1 && !memcmp(sig, #s, siglen)) \
+        ssh->exitcode = 128 + SIG ## s
+#ifdef SIGABRT
+                   TRANSLATE_SIGNAL(ABRT);
+#endif
+#ifdef SIGALRM
+                   TRANSLATE_SIGNAL(ALRM);
+#endif
+#ifdef SIGFPE
+                   TRANSLATE_SIGNAL(FPE);
+#endif
+#ifdef SIGHUP
+                   TRANSLATE_SIGNAL(HUP);
+#endif
+#ifdef SIGILL
+                   TRANSLATE_SIGNAL(ILL);
+#endif
+#ifdef SIGINT
+                   TRANSLATE_SIGNAL(INT);
+#endif
+#ifdef SIGKILL
+                   TRANSLATE_SIGNAL(KILL);
+#endif
+#ifdef SIGPIPE
+                   TRANSLATE_SIGNAL(PIPE);
+#endif
+#ifdef SIGQUIT
+                   TRANSLATE_SIGNAL(QUIT);
+#endif
+#ifdef SIGSEGV
+                   TRANSLATE_SIGNAL(SEGV);
+#endif
+#ifdef SIGTERM
+                   TRANSLATE_SIGNAL(TERM);
+#endif
+#ifdef SIGUSR1
+                   TRANSLATE_SIGNAL(USR1);
+#endif
+#ifdef SIGUSR2
+                   TRANSLATE_SIGNAL(USR2);
+#endif
+#undef TRANSLATE_SIGNAL
+                   else
+                       ssh->exitcode = 128;
                }
                core = ssh2_pkt_getbool(pktin);
                ssh_pkt_getstring(pktin, &msg, &msglen);
@@ -6001,7 +6689,7 @@ 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 +6729,48 @@ 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 +6779,25 @@ 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 +6810,153 @@ 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 +6985,7 @@ 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 +6996,31 @@ 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;
+           }
+           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;
            }
-           s->username[strcspn(s->username, "\n\r")] = '\0';
+           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 +7050,18 @@ 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 +7069,14 @@ 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 +7085,13 @@ 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 +7099,9 @@ 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 +7116,6 @@ 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 +7172,275 @@ 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;
+               }
+
+           } else if (s->can_pubkey && s->publickey_blob &&
+                      !s->tried_pubkey_config) {
 
-               s->tried_pubkey_config = TRUE;
+               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 +7449,18 @@ 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 +7470,23 @@ 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 +7499,196 @@ 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);
+                   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_with_padding(ssh, s->pktout, 256);
+
+                   /*
+                    * 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.
@@ -6819,67 +7698,205 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                 * people who find out how long their password is!
                 */
                s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
-               s->pktout->forcepad = 256;
                ssh2_pkt_addstring(s->pktout, s->username);
-               ssh2_pkt_addstring(s->pktout, "ssh-connection");        /* service requested */
+               ssh2_pkt_addstring(s->pktout, "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);
+               ssh2_pkt_send_with_padding(ssh, s->pktout, 256);
                logevent("Sent password");
                s->type = AUTH_TYPE_PASSWORD;
-           } else if (s->method == AUTH_KEYBOARD_INTERACTIVE) {
-               if (s->curr_prompt == 0) {
-                   s->pktout = ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
-                   s->pktout->forcepad = 256;
-                   ssh2_pkt_adduint32(s->pktout, s->num_prompts);
-               }
-               if (s->need_pw) {      /* only add pw if we just got one! */
+
+               /*
+                * 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;
+                   /*
+                    * There's no explicit requirement in the protocol
+                    * for the "old" passwords in the original and
+                    * password-change messages to be the same, and
+                    * apparently some Cisco kit supports password change
+                    * by the user entering a blank password originally
+                    * and the real password subsequently, so,
+                    * reluctantly, we prompt for the old password again.
+                    *
+                    * (On the other hand, some servers don't even bother
+                    * to check this field.)
+                    */
+                   add_prompt(s->cur_prompt,
+                              dupstr("Current password (blank for previously entered password): "),
+                              FALSE, SSH_MAX_PASSWORD_LEN);
+                   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;
+                       }
+
+                       /*
+                        * If the user specified a new original password
+                        * (IYSWIM), overwrite any previously specified
+                        * one.
+                        * (A side effect is that the user doesn't have to
+                        * re-enter it if they louse up the new password.)
+                        */
+                       if (s->cur_prompt->prompts[0]->result[0]) {
+                           memset(s->password, 0, strlen(s->password));
+                               /* burn the evidence */
+                           sfree(s->password);
+                           s->password =
+                               dupstr(s->cur_prompt->prompts[0]->result);
+                       }
+
+                       /*
+                        * Check the two new passwords match.
+                        */
+                       got_new = (strcmp(s->cur_prompt->prompts[1]->result,
+                                         s->cur_prompt->prompts[2]->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);
+                   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[1]->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 {
+                   ssh2_pkt_send_with_padding(ssh, s->pktout, 256);
+                   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);
@@ -6896,7 +7913,58 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Create the main session channel.
      */
-    if (!ssh->cfg.ssh_no_shell) {
+    if (ssh->cfg.ssh_no_shell) {
+       ssh->mainchan = NULL;
+    } else if (*ssh->cfg.ssh_nc_host) {
+       /*
+        * Just start a direct-tcpip channel and use it as the main
+        * channel.
+        */
+       ssh->mainchan = snew(struct ssh_channel);
+       ssh->mainchan->ssh = ssh;
+       ssh->mainchan->localid = alloc_channel_id(ssh);
+       logeventf(ssh,
+                 "Opening direct-tcpip channel to %s:%d in place of session",
+                 ssh->cfg.ssh_nc_host, ssh->cfg.ssh_nc_port);
+       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
+       ssh2_pkt_addstring(s->pktout, "direct-tcpip");
+       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->localid);
+       ssh->mainchan->v.v2.locwindow = OUR_V2_WINSIZE;
+       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->v.v2.locwindow);/* our window size */
+       ssh2_pkt_adduint32(s->pktout, OUR_V2_MAXPKT);      /* our max pkt size */
+       ssh2_pkt_addstring(s->pktout, ssh->cfg.ssh_nc_host);
+       ssh2_pkt_adduint32(s->pktout, ssh->cfg.ssh_nc_port);
+       /*
+        * There's nothing meaningful to put in the originator
+        * fields, but some servers insist on syntactically correct
+        * information.
+        */
+       ssh2_pkt_addstring(s->pktout, "0.0.0.0");
+       ssh2_pkt_adduint32(s->pktout, 0);
+       ssh2_pkt_send(ssh, s->pktout);
+
+       crWaitUntilV(pktin);
+       if (pktin->type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
+           bombout(("Server refused to open a direct-tcpip channel"));
+           crStopV;
+           /* FIXME: error data comes back in FAILURE packet */
+       }
+       if (ssh_pkt_getuint32(pktin) != ssh->mainchan->localid) {
+           bombout(("Server's channel confirmation cited wrong channel"));
+           crStopV;
+       }
+       ssh->mainchan->remoteid = ssh_pkt_getuint32(pktin);
+       ssh->mainchan->halfopen = FALSE;
+       ssh->mainchan->type = CHAN_MAINSESSION;
+       ssh->mainchan->closes = 0;
+       ssh->mainchan->v.v2.remwindow = ssh_pkt_getuint32(pktin);
+       ssh->mainchan->v.v2.remmaxpkt = ssh_pkt_getuint32(pktin);
+       bufchain_init(&ssh->mainchan->v.v2.outbuffer);
+       add234(ssh->channels, ssh->mainchan);
+       update_specials_menu(ssh->frontend);
+       logevent("Opened direct-tcpip channel");
+       ssh->ncmode = TRUE;
+    } else {
        ssh->mainchan = snew(struct ssh_channel);
        ssh->mainchan->ssh = ssh;
        ssh->mainchan->localid = alloc_channel_id(ssh);
@@ -6927,8 +7995,8 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        add234(ssh->channels, ssh->mainchan);
        update_specials_menu(ssh->frontend);
        logevent("Opened channel for session");
-    } else
-       ssh->mainchan = NULL;
+       ssh->ncmode = FALSE;
+    }
 
     /*
      * Now we have a channel, make dispatch table entries for
@@ -6951,7 +8019,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Potentially enable X11 forwarding.
      */
-    if (ssh->mainchan && ssh->cfg.x11_forward) {
+    if (ssh->mainchan && !ssh->ncmode && ssh->cfg.x11_forward) {
        char proto[20], data[64];
        logevent("Requesting X11 forwarding");
        ssh->x11auth = x11_invent_auth(proto, sizeof(proto),
@@ -6963,7 +8031,16 @@ 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);
 
@@ -6990,7 +8067,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Potentially enable agent forwarding.
      */
-    if (ssh->mainchan && ssh->cfg.agentfwd && agent_exists()) {
+    if (ssh->mainchan && !ssh->ncmode && ssh->cfg.agentfwd && agent_exists()) {
        logevent("Requesting OpenSSH-style agent forwarding");
        s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
        ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
@@ -7016,7 +8093,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     /*
      * Now allocate a pty for the session.
      */
-    if (ssh->mainchan && !ssh->cfg.nopty) {
+    if (ssh->mainchan && !ssh->ncmode && !ssh->cfg.nopty) {
        /* Unpick the terminal-speed string. */
        /* XXX perhaps we should allow no speeds to be sent. */
         ssh->ospeed = 38400; ssh->ispeed = 38400; /* last-resort defaults */
@@ -7032,9 +8109,11 @@ 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);
@@ -7064,7 +8143,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
      * Simplest thing here is to send all the requests at once, and
      * then wait for a whole bunch of successes or failures.
      */
-    if (ssh->mainchan && *ssh->cfg.environmt) {
+    if (ssh->mainchan && !ssh->ncmode && *ssh->cfg.environmt) {
        char *e = ssh->cfg.environmt;
        char *var, *varend, *val;
 
@@ -7129,7 +8208,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
      * this twice if the config data has provided a second choice
      * of command.
      */
-    if (ssh->mainchan) while (1) {
+    if (ssh->mainchan && !ssh->ncmode) while (1) {
        int subsys;
        char *cmd;
 
@@ -7139,6 +8218,7 @@ 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 +8303,8 @@ 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);
        }
     }
 
@@ -7254,9 +8312,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 }
 
 /*
- * Handlers for SSH2 messages that might arrive at any moment.
+ * Handlers for SSH-2 messages that might arrive at any moment.
  */
-void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
+static void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
 {
     /* log reason code in disconnect message */
     char *buf, *msg;
@@ -7285,10 +8343,10 @@ void ssh2_msg_disconnect(Ssh ssh, struct Packet *pktin)
     sfree(buf);
 }
 
-void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
+static void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
 {
     /* log the debug message */
-    char *buf, *msg;
+    char *msg;
     int msglen;
     int always_display;
 
@@ -7296,12 +8354,10 @@ void ssh2_msg_debug(Ssh ssh, struct Packet *pktin)
     always_display = ssh2_pkt_getbool(pktin);
     ssh_pkt_getstring(pktin, &msg, &msglen);
 
-    buf = dupprintf("Remote debug message: %.*s", msglen, msg);
-    logevent(buf);
-    sfree(buf);
+    logeventf(ssh, "Remote debug message: %.*s", msglen, msg);
 }
 
-void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
+static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
 {
     struct Packet *pktout;
     pktout = ssh2_pkt_init(SSH2_MSG_UNIMPLEMENTED);
@@ -7314,7 +8370,7 @@ void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
 }
 
 /*
- * Handle the top-level SSH2 protocol.
+ * Handle the top-level SSH-2 protocol.
  */
 static void ssh2_protocol_setup(Ssh ssh)
 {
@@ -7368,7 +8424,7 @@ 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 +8432,9 @@ 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 +8513,7 @@ 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 +8539,8 @@ 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 +8549,8 @@ 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 +8668,8 @@ 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 +8679,7 @@ 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 +8695,8 @@ 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 +8743,7 @@ 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 +8900,7 @@ 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 +8925,7 @@ 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 +8947,7 @@ 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);
@@ -7954,8 +9023,7 @@ static void ssh_unthrottle(void *handle, int bufsize)
            ssh1_throttle(ssh, -1);
        }
     } else {
-       if (ssh->mainchan && ssh->mainchan->closes == 0)
-           ssh2_set_window(ssh->mainchan, OUR_V2_WINSIZE - bufsize);
+       ssh2_set_window(ssh->mainchan, OUR_V2_WINSIZE - bufsize);
     }
 }
 
@@ -7988,17 +9056,20 @@ 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);
     }
 }
 
-static Socket ssh_socket(void *handle)
+static int ssh_connected(void *handle)
 {
     Ssh ssh = (Ssh) handle;
-    return ssh->s;
+    return ssh->s != NULL;
 }
 
 static int ssh_sendok(void *handle)
@@ -8035,7 +9106,7 @@ static int ssh_return_exitcode(void *handle)
     if (ssh->s != NULL)
         return -1;
     else
-        return (ssh->exitcode >= 0 ? ssh->exitcode : 0);
+        return (ssh->exitcode >= 0 ? ssh->exitcode : INT_MAX);
 }
 
 /*
@@ -8068,7 +9139,7 @@ Backend ssh_backend = {
     ssh_size,
     ssh_special,
     ssh_get_specials,
-    ssh_socket,
+    ssh_connected,
     ssh_return_exitcode,
     ssh_sendok,
     ssh_ldisc,