Configurable TCP_NODELAY option on network connections
[u/mdw/putty] / ssh.c
diff --git a/ssh.c b/ssh.c
index b3be8e4..2163e21 100644 (file)
--- a/ssh.c
+++ b/ssh.c
                           (s ? sk_close(s), s = NULL : 0), \
                           connection_fatal msg )
 
-#define SSH1_MSG_DISCONNECT                       1    /* 0x1 */
-#define SSH1_SMSG_PUBLIC_KEY                      2    /* 0x2 */
-#define SSH1_CMSG_SESSION_KEY                     3    /* 0x3 */
-#define SSH1_CMSG_USER                            4    /* 0x4 */
-#define SSH1_CMSG_AUTH_RSA                        6    /* 0x6 */
-#define SSH1_SMSG_AUTH_RSA_CHALLENGE              7    /* 0x7 */
-#define SSH1_CMSG_AUTH_RSA_RESPONSE               8    /* 0x8 */
-#define SSH1_CMSG_AUTH_PASSWORD                   9    /* 0x9 */
-#define SSH1_CMSG_REQUEST_PTY                     10   /* 0xa */
-#define SSH1_CMSG_WINDOW_SIZE                     11   /* 0xb */
-#define SSH1_CMSG_EXEC_SHELL                      12   /* 0xc */
-#define SSH1_CMSG_EXEC_CMD                        13   /* 0xd */
-#define SSH1_SMSG_SUCCESS                         14   /* 0xe */
-#define SSH1_SMSG_FAILURE                         15   /* 0xf */
-#define SSH1_CMSG_STDIN_DATA                      16   /* 0x10 */
-#define SSH1_SMSG_STDOUT_DATA                     17   /* 0x11 */
-#define SSH1_SMSG_STDERR_DATA                     18   /* 0x12 */
-#define SSH1_CMSG_EOF                             19   /* 0x13 */
-#define SSH1_SMSG_EXIT_STATUS                     20   /* 0x14 */
-#define SSH1_MSG_CHANNEL_OPEN_CONFIRMATION        21   /* 0x15 */
-#define SSH1_MSG_CHANNEL_OPEN_FAILURE             22   /* 0x16 */
-#define SSH1_MSG_CHANNEL_DATA                     23   /* 0x17 */
-#define SSH1_MSG_CHANNEL_CLOSE                    24   /* 0x18 */
-#define SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION       25   /* 0x19 */
-#define SSH1_SMSG_X11_OPEN                        27   /* 0x1b */
-#define SSH1_CMSG_PORT_FORWARD_REQUEST            28   /* 0x1c */
-#define SSH1_MSG_PORT_OPEN                        29   /* 0x1d */
-#define SSH1_CMSG_AGENT_REQUEST_FORWARDING        30   /* 0x1e */
-#define SSH1_SMSG_AGENT_OPEN                      31   /* 0x1f */
-#define SSH1_MSG_IGNORE                           32   /* 0x20 */
-#define SSH1_CMSG_EXIT_CONFIRMATION               33   /* 0x21 */
-#define SSH1_CMSG_X11_REQUEST_FORWARDING          34   /* 0x22 */
-#define SSH1_CMSG_AUTH_RHOSTS_RSA                 35   /* 0x23 */
-#define SSH1_MSG_DEBUG                            36   /* 0x24 */
-#define SSH1_CMSG_REQUEST_COMPRESSION             37   /* 0x25 */
-#define SSH1_CMSG_AUTH_TIS                        39   /* 0x27 */
-#define SSH1_SMSG_AUTH_TIS_CHALLENGE              40   /* 0x28 */
-#define SSH1_CMSG_AUTH_TIS_RESPONSE               41   /* 0x29 */
-#define SSH1_CMSG_AUTH_CCARD                      70   /* 0x46 */
-#define SSH1_SMSG_AUTH_CCARD_CHALLENGE            71   /* 0x47 */
-#define SSH1_CMSG_AUTH_CCARD_RESPONSE             72   /* 0x48 */
-
-#define SSH1_AUTH_TIS                             5    /* 0x5 */
-#define SSH1_AUTH_CCARD                           16   /* 0x10 */
-
-#define SSH1_PROTOFLAG_SCREEN_NUMBER              1    /* 0x1 */
+#define SSH1_MSG_DISCONNECT                       1    /* 0x1 */
+#define SSH1_SMSG_PUBLIC_KEY                      2    /* 0x2 */
+#define SSH1_CMSG_SESSION_KEY                     3    /* 0x3 */
+#define SSH1_CMSG_USER                            4    /* 0x4 */
+#define SSH1_CMSG_AUTH_RSA                        6    /* 0x6 */
+#define SSH1_SMSG_AUTH_RSA_CHALLENGE              7    /* 0x7 */
+#define SSH1_CMSG_AUTH_RSA_RESPONSE               8    /* 0x8 */
+#define SSH1_CMSG_AUTH_PASSWORD                   9    /* 0x9 */
+#define SSH1_CMSG_REQUEST_PTY                     10   /* 0xa */
+#define SSH1_CMSG_WINDOW_SIZE                     11   /* 0xb */
+#define SSH1_CMSG_EXEC_SHELL                      12   /* 0xc */
+#define SSH1_CMSG_EXEC_CMD                        13   /* 0xd */
+#define SSH1_SMSG_SUCCESS                         14   /* 0xe */
+#define SSH1_SMSG_FAILURE                         15   /* 0xf */
+#define SSH1_CMSG_STDIN_DATA                      16   /* 0x10 */
+#define SSH1_SMSG_STDOUT_DATA                     17   /* 0x11 */
+#define SSH1_SMSG_STDERR_DATA                     18   /* 0x12 */
+#define SSH1_CMSG_EOF                             19   /* 0x13 */
+#define SSH1_SMSG_EXIT_STATUS                     20   /* 0x14 */
+#define SSH1_MSG_CHANNEL_OPEN_CONFIRMATION        21   /* 0x15 */
+#define SSH1_MSG_CHANNEL_OPEN_FAILURE             22   /* 0x16 */
+#define SSH1_MSG_CHANNEL_DATA                     23   /* 0x17 */
+#define SSH1_MSG_CHANNEL_CLOSE                    24   /* 0x18 */
+#define SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION       25   /* 0x19 */
+#define SSH1_SMSG_X11_OPEN                        27   /* 0x1b */
+#define SSH1_CMSG_PORT_FORWARD_REQUEST            28   /* 0x1c */
+#define SSH1_MSG_PORT_OPEN                        29   /* 0x1d */
+#define SSH1_CMSG_AGENT_REQUEST_FORWARDING        30   /* 0x1e */
+#define SSH1_SMSG_AGENT_OPEN                      31   /* 0x1f */
+#define SSH1_MSG_IGNORE                           32   /* 0x20 */
+#define SSH1_CMSG_EXIT_CONFIRMATION               33   /* 0x21 */
+#define SSH1_CMSG_X11_REQUEST_FORWARDING          34   /* 0x22 */
+#define SSH1_CMSG_AUTH_RHOSTS_RSA                 35   /* 0x23 */
+#define SSH1_MSG_DEBUG                            36   /* 0x24 */
+#define SSH1_CMSG_REQUEST_COMPRESSION             37   /* 0x25 */
+#define SSH1_CMSG_AUTH_TIS                        39   /* 0x27 */
+#define SSH1_SMSG_AUTH_TIS_CHALLENGE              40   /* 0x28 */
+#define SSH1_CMSG_AUTH_TIS_RESPONSE               41   /* 0x29 */
+#define SSH1_CMSG_AUTH_CCARD                      70   /* 0x46 */
+#define SSH1_SMSG_AUTH_CCARD_CHALLENGE            71   /* 0x47 */
+#define SSH1_CMSG_AUTH_CCARD_RESPONSE             72   /* 0x48 */
+
+#define SSH1_AUTH_TIS                             5    /* 0x5 */
+#define SSH1_AUTH_CCARD                           16   /* 0x10 */
+
+#define SSH1_PROTOFLAG_SCREEN_NUMBER              1    /* 0x1 */
 /* Mask for protoflags we will echo back to server if seen */
-#define SSH1_PROTOFLAGS_SUPPORTED                 0    /* 0x1 */
-
-#define SSH2_MSG_DISCONNECT                       1    /* 0x1 */
-#define SSH2_MSG_IGNORE                           2    /* 0x2 */
-#define SSH2_MSG_UNIMPLEMENTED                    3    /* 0x3 */
-#define SSH2_MSG_DEBUG                            4    /* 0x4 */
-#define SSH2_MSG_SERVICE_REQUEST                  5    /* 0x5 */
-#define SSH2_MSG_SERVICE_ACCEPT                   6    /* 0x6 */
-#define SSH2_MSG_KEXINIT                          20   /* 0x14 */
-#define SSH2_MSG_NEWKEYS                          21   /* 0x15 */
-#define SSH2_MSG_KEXDH_INIT                       30   /* 0x1e */
-#define SSH2_MSG_KEXDH_REPLY                      31   /* 0x1f */
-#define SSH2_MSG_KEX_DH_GEX_REQUEST               30   /* 0x1e */
-#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_USERAUTH_REQUEST                 50   /* 0x32 */
-#define SSH2_MSG_USERAUTH_FAILURE                 51   /* 0x33 */
-#define SSH2_MSG_USERAUTH_SUCCESS                 52   /* 0x34 */
-#define SSH2_MSG_USERAUTH_BANNER                  53   /* 0x35 */
-#define SSH2_MSG_USERAUTH_PK_OK                   60   /* 0x3c */
-#define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ        60   /* 0x3c */
-#define SSH2_MSG_GLOBAL_REQUEST                   80   /* 0x50 */
-#define SSH2_MSG_REQUEST_SUCCESS                  81   /* 0x51 */
-#define SSH2_MSG_REQUEST_FAILURE                  82   /* 0x52 */
-#define SSH2_MSG_CHANNEL_OPEN                     90   /* 0x5a */
-#define SSH2_MSG_CHANNEL_OPEN_CONFIRMATION        91   /* 0x5b */
-#define SSH2_MSG_CHANNEL_OPEN_FAILURE             92   /* 0x5c */
-#define SSH2_MSG_CHANNEL_WINDOW_ADJUST            93   /* 0x5d */
-#define SSH2_MSG_CHANNEL_DATA                     94   /* 0x5e */
-#define SSH2_MSG_CHANNEL_EXTENDED_DATA            95   /* 0x5f */
-#define SSH2_MSG_CHANNEL_EOF                      96   /* 0x60 */
-#define SSH2_MSG_CHANNEL_CLOSE                    97   /* 0x61 */
-#define SSH2_MSG_CHANNEL_REQUEST                  98   /* 0x62 */
-#define SSH2_MSG_CHANNEL_SUCCESS                  99   /* 0x63 */
-#define SSH2_MSG_CHANNEL_FAILURE                  100  /* 0x64 */
-
-#define SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1  /* 0x1 */
-#define SSH2_DISCONNECT_PROTOCOL_ERROR            2    /* 0x2 */
-#define SSH2_DISCONNECT_KEY_EXCHANGE_FAILED       3    /* 0x3 */
-#define SSH2_DISCONNECT_HOST_AUTHENTICATION_FAILED 4   /* 0x4 */
-#define SSH2_DISCONNECT_MAC_ERROR                 5    /* 0x5 */
-#define SSH2_DISCONNECT_COMPRESSION_ERROR         6    /* 0x6 */
-#define SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE     7    /* 0x7 */
-#define SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8 /* 0x8 */
-#define SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE   9    /* 0x9 */
-#define SSH2_DISCONNECT_CONNECTION_LOST           10   /* 0xa */
-#define SSH2_DISCONNECT_BY_APPLICATION            11   /* 0xb */
-#define SSH2_DISCONNECT_TOO_MANY_CONNECTIONS      12   /* 0xc */
-#define SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER    13   /* 0xd */
-#define SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14 /* 0xe */
-#define SSH2_DISCONNECT_ILLEGAL_USER_NAME         15   /* 0xf */
+#define SSH1_PROTOFLAGS_SUPPORTED                 0    /* 0x1 */
+
+#define SSH2_MSG_DISCONNECT                       1    /* 0x1 */
+#define SSH2_MSG_IGNORE                           2    /* 0x2 */
+#define SSH2_MSG_UNIMPLEMENTED                    3    /* 0x3 */
+#define SSH2_MSG_DEBUG                            4    /* 0x4 */
+#define SSH2_MSG_SERVICE_REQUEST                  5    /* 0x5 */
+#define SSH2_MSG_SERVICE_ACCEPT                   6    /* 0x6 */
+#define SSH2_MSG_KEXINIT                          20   /* 0x14 */
+#define SSH2_MSG_NEWKEYS                          21   /* 0x15 */
+#define SSH2_MSG_KEXDH_INIT                       30   /* 0x1e */
+#define SSH2_MSG_KEXDH_REPLY                      31   /* 0x1f */
+#define SSH2_MSG_KEX_DH_GEX_REQUEST               30   /* 0x1e */
+#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_USERAUTH_REQUEST                 50   /* 0x32 */
+#define SSH2_MSG_USERAUTH_FAILURE                 51   /* 0x33 */
+#define SSH2_MSG_USERAUTH_SUCCESS                 52   /* 0x34 */
+#define SSH2_MSG_USERAUTH_BANNER                  53   /* 0x35 */
+#define SSH2_MSG_USERAUTH_PK_OK                   60   /* 0x3c */
+#define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ        60   /* 0x3c */
+#define SSH2_MSG_USERAUTH_INFO_REQUEST            60   /* 0x3c */
+#define SSH2_MSG_USERAUTH_INFO_RESPONSE           61   /* 0x3d */
+#define SSH2_MSG_GLOBAL_REQUEST                   80   /* 0x50 */
+#define SSH2_MSG_REQUEST_SUCCESS                  81   /* 0x51 */
+#define SSH2_MSG_REQUEST_FAILURE                  82   /* 0x52 */
+#define SSH2_MSG_CHANNEL_OPEN                     90   /* 0x5a */
+#define SSH2_MSG_CHANNEL_OPEN_CONFIRMATION        91   /* 0x5b */
+#define SSH2_MSG_CHANNEL_OPEN_FAILURE             92   /* 0x5c */
+#define SSH2_MSG_CHANNEL_WINDOW_ADJUST            93   /* 0x5d */
+#define SSH2_MSG_CHANNEL_DATA                     94   /* 0x5e */
+#define SSH2_MSG_CHANNEL_EXTENDED_DATA            95   /* 0x5f */
+#define SSH2_MSG_CHANNEL_EOF                      96   /* 0x60 */
+#define SSH2_MSG_CHANNEL_CLOSE                    97   /* 0x61 */
+#define SSH2_MSG_CHANNEL_REQUEST                  98   /* 0x62 */
+#define SSH2_MSG_CHANNEL_SUCCESS                  99   /* 0x63 */
+#define SSH2_MSG_CHANNEL_FAILURE                  100  /* 0x64 */
+
+#define SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1  /* 0x1 */
+#define SSH2_DISCONNECT_PROTOCOL_ERROR            2    /* 0x2 */
+#define SSH2_DISCONNECT_KEY_EXCHANGE_FAILED       3    /* 0x3 */
+#define SSH2_DISCONNECT_HOST_AUTHENTICATION_FAILED 4   /* 0x4 */
+#define SSH2_DISCONNECT_MAC_ERROR                 5    /* 0x5 */
+#define SSH2_DISCONNECT_COMPRESSION_ERROR         6    /* 0x6 */
+#define SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE     7    /* 0x7 */
+#define SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8       /* 0x8 */
+#define SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE   9    /* 0x9 */
+#define SSH2_DISCONNECT_CONNECTION_LOST           10   /* 0xa */
+#define SSH2_DISCONNECT_BY_APPLICATION            11   /* 0xb */
+#define SSH2_DISCONNECT_TOO_MANY_CONNECTIONS      12   /* 0xc */
+#define SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER    13   /* 0xd */
+#define SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14      /* 0xe */
+#define SSH2_DISCONNECT_ILLEGAL_USER_NAME         15   /* 0xf */
 
 static const char *const ssh2_disconnect_reasons[] = {
     NULL,
@@ -145,18 +147,20 @@ static const char *const ssh2_disconnect_reasons[] = {
     "SSH_DISCONNECT_ILLEGAL_USER_NAME",
 };
 
-#define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED     1    /* 0x1 */
-#define SSH2_OPEN_CONNECT_FAILED                  2    /* 0x2 */
-#define SSH2_OPEN_UNKNOWN_CHANNEL_TYPE            3    /* 0x3 */
-#define SSH2_OPEN_RESOURCE_SHORTAGE               4    /* 0x4 */
+#define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED     1    /* 0x1 */
+#define SSH2_OPEN_CONNECT_FAILED                  2    /* 0x2 */
+#define SSH2_OPEN_UNKNOWN_CHANNEL_TYPE            3    /* 0x3 */
+#define SSH2_OPEN_RESOURCE_SHORTAGE               4    /* 0x4 */
 
-#define SSH2_EXTENDED_DATA_STDERR                 1    /* 0x1 */
+#define SSH2_EXTENDED_DATA_STDERR                 1    /* 0x1 */
 
 /*
  * Various remote-bug flags.
  */
 #define BUG_CHOKES_ON_SSH1_IGNORE                 1
 #define BUG_SSH2_HMAC                             2
+#define BUG_NEEDS_SSH1_PLAIN_PASSWORD            4
+
 
 #define GET_32BIT(cp) \
     (((unsigned long)(unsigned char)(cp)[0] << 24) | \
@@ -191,46 +195,96 @@ enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR, PKT_BIGNUM };
 #define crWaitUntil(c) do { crReturn(0); } while (!(c))
 #define crWaitUntilV(c)        do { crReturnV; } while (!(c))
 
-extern char *x11_init (Socket *, char *, void *);
-extern void x11_close (Socket);
-extern void x11_send  (Socket , char *, int);
+extern char *x11_init(Socket *, char *, void *);
+extern void x11_close(Socket);
+extern int x11_send(Socket, char *, int);
 extern void x11_invent_auth(char *, int, char *, int);
+extern void x11_unthrottle(Socket s);
+extern void x11_override_throttle(Socket s, int enable);
+
+extern char *pfd_newconnect(Socket * s, char *hostname, int port, void *c);
+extern char *pfd_addforward(char *desthost, int destport, int port);
+extern void pfd_close(Socket s);
+extern int pfd_send(Socket s, char *data, int len);
+extern void pfd_confirm(Socket s);
+extern void pfd_unthrottle(Socket s);
+extern void pfd_override_throttle(Socket s, int enable);
+
+/*
+ * Buffer management constants. There are several of these for
+ * various different purposes:
+ * 
+ *  - 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
+ *    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
+ *    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
+ *    channels.
+ */
+
+#define SSH1_BUFFER_LIMIT 32768
+#define SSH_MAX_BACKLOG 32768
+#define OUR_V2_WINSIZE 16384
 
 /*
- * Ciphers for SSH2. We miss out single-DES because it isn't
- * supported; also 3DES and Blowfish are both done differently from
- * SSH1. (3DES uses outer chaining; Blowfish has the opposite
- * endianness and different-sized keys.)
+ * Ciphers for SSH2.
  */
 const static struct ssh2_ciphers *ciphers[] = {
     &ssh2_aes,
     &ssh2_blowfish,
     &ssh2_3des,
+    &ssh2_des,
 };
 
 const static struct ssh_kex *kex_algs[] = {
     &ssh_diffiehellman_gex,
-    &ssh_diffiehellman };
+    &ssh_diffiehellman
+};
 
 const static struct ssh_signkey *hostkey_algs[] = { &ssh_rsa, &ssh_dss };
 
-static void nullmac_key(unsigned char *key) { }
-static void nullmac_generate(unsigned char *blk, int len, unsigned long seq) { }
-static int nullmac_verify(unsigned char *blk, int len, unsigned long seq) { return 1; }
+static void nullmac_key(unsigned char *key)
+{
+}
+static void nullmac_generate(unsigned char *blk, int len,
+                            unsigned long seq)
+{
+}
+static int nullmac_verify(unsigned char *blk, int len, unsigned long seq)
+{
+    return 1;
+}
 const static struct ssh_mac ssh_mac_none = {
     nullmac_key, nullmac_key, nullmac_generate, nullmac_verify, "none", 0
 };
 const static struct ssh_mac *macs[] = {
-    &ssh_sha1, &ssh_md5, &ssh_mac_none };
+    &ssh_sha1, &ssh_md5, &ssh_mac_none
+};
 const static struct ssh_mac *buggymacs[] = {
-    &ssh_sha1_buggy, &ssh_md5, &ssh_mac_none };
+    &ssh_sha1_buggy, &ssh_md5, &ssh_mac_none
+};
 
-static void ssh_comp_none_init(void) { }
+static void ssh_comp_none_init(void)
+{
+}
 static int ssh_comp_none_block(unsigned char *block, int len,
-                              unsigned char **outblock, int *outlen) {
+                              unsigned char **outblock, int *outlen)
+{
+    return 0;
+}
+static int ssh_comp_none_disable(void)
+{
     return 0;
 }
-static int ssh_comp_none_disable(void) { return 0; }
 const static struct ssh_compress ssh_comp_none = {
     "none",
     ssh_comp_none_init, ssh_comp_none_block,
@@ -239,12 +293,15 @@ const static struct ssh_compress ssh_comp_none = {
 };
 extern const struct ssh_compress ssh_zlib;
 const static struct ssh_compress *compressions[] = {
-    &ssh_zlib, &ssh_comp_none };
+    &ssh_zlib, &ssh_comp_none
+};
 
-enum {                                 /* channel types */
+enum {                                /* channel types */
     CHAN_MAINSESSION,
     CHAN_X11,
     CHAN_AGENT,
+    CHAN_SOCKDATA,
+    CHAN_SOCKDATA_DORMANT             /* one the remote hasn't confirmed */
 };
 
 /*
@@ -254,23 +311,65 @@ struct ssh_channel {
     unsigned remoteid, localid;
     int type;
     int closes;
-    struct ssh2_data_channel {
-        unsigned char *outbuffer;
-        unsigned outbuflen, outbufsize;
-        unsigned remwindow, remmaxpkt;
-    } v2;
     union {
-        struct ssh_agent_channel {
-            unsigned char *message;
-            unsigned char msglen[4];
-            int lensofar, totallen;
-        } a;
-        struct ssh_x11_channel {
-            Socket s;
-        } x11;
+       struct ssh1_data_channel {
+           int throttling;
+       } v1;
+       struct ssh2_data_channel {
+           bufchain outbuffer;
+           unsigned remwindow, remmaxpkt;
+           unsigned locwindow;
+       } v2;
+    } v;
+    union {
+       struct ssh_agent_channel {
+           unsigned char *message;
+           unsigned char msglen[4];
+           int lensofar, totallen;
+       } a;
+       struct ssh_x11_channel {
+           Socket s;
+       } x11;
+       struct ssh_pfd_channel {
+           Socket s;
+       } pfd;
     } u;
 };
 
+/*
+ * 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
+ * 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
+ * security hole if you're not on the ball: a malicious server
+ * could send you back _any_ host:port pair, so if you trustingly
+ * connect to the address it gives you then you've just opened the
+ * entire inside of your corporate network just by connecting
+ * through it to a dodgy SSH server. Hence, we must store a list of
+ * 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
+ * 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 stores host:port pairs we intend
+ * to allow connections to, and is indexed by those host:port
+ * pairs. In SSH 2 it stores a mapping from source port to
+ * destination host:port pair, and is indexed by source port.
+ */
+struct ssh_rportfwd {
+    unsigned sport, dport;
+    char dhost[256];
+};
+
 struct Packet {
     long length;
     int type;
@@ -301,17 +400,19 @@ static const struct ssh_compress *sccomp = NULL;
 static const struct ssh_kex *kex = NULL;
 static const struct ssh_signkey *hostkey = NULL;
 static unsigned char ssh2_session_id[20];
-int (*ssh_get_line)(const char *prompt, char *str, int maxlen,
-                    int is_pw) = NULL;
+int (*ssh_get_line) (const char *prompt, char *str, int maxlen,
+                    int is_pw) = NULL;
 
 static char *savedhost;
 static int savedport;
 static int ssh_send_ok;
 static int ssh_echoing, ssh_editing;
 
-static tree234 *ssh_channels;           /* indexed by local id */
+static tree234 *ssh_channels;         /* indexed by local id */
 static struct ssh_channel *mainchan;   /* primary session channel */
 
+static tree234 *ssh_rportfwds;
+
 static enum {
     SSH_STATE_PREPACKET,
     SSH_STATE_BEFORE_SIZE,
@@ -327,16 +428,30 @@ static struct Packet pktout = { 0, 0, NULL, NULL, 0 };
 static unsigned char *deferred_send_data = NULL;
 static int deferred_len = 0, deferred_size = 0;
 
+/*
+ * Gross hack: pscp will try to start SFTP but fall back to scp1 if
+ * that fails. This variable is the means by which scp.c can reach
+ * into the SSH code and find out which one it got.
+ */
+int ssh_fallback_cmd = 0;
+
 static int ssh_version;
-static void (*ssh_protocol)(unsigned char *in, int inlen, int ispkt);
+static int ssh1_throttle_count;
+static int ssh_overall_bufsize;
+static int ssh_throttled_all;
+static int ssh1_stdout_throttling;
+static void (*ssh_protocol) (unsigned char *in, int inlen, int ispkt);
 static void ssh1_protocol(unsigned char *in, int inlen, int ispkt);
 static void ssh2_protocol(unsigned char *in, int inlen, int ispkt);
 static void ssh_size(void);
-static void ssh_special (Telnet_Special);
-static void ssh2_try_send(struct ssh_channel *c);
-static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len);
-
-static int (*s_rdpkt)(unsigned char **data, int *datalen);
+static void ssh_special(Telnet_Special);
+static int ssh2_try_send(struct ssh_channel *c);
+static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
+                                 int len);
+static void ssh_throttle_all(int enable, int bufsize);
+static void ssh2_set_window(struct ssh_channel *c, unsigned newwin);
+static int (*s_rdpkt) (unsigned char **data, int *datalen);
+static int ssh_sendbuffer(void);
 
 static struct rdpkt1_state_tag {
     long len, pad, biglen, to_read;
@@ -353,22 +468,55 @@ static struct rdpkt2_state_tag {
     unsigned long incoming_sequence;
 } rdpkt2_state;
 
-static int ssh_channelcmp(void *av, void *bv) {
-    struct ssh_channel *a = (struct ssh_channel *)av;
-    struct ssh_channel *b = (struct ssh_channel *)bv;
-    if (a->localid < b->localid) return -1;
-    if (a->localid > b->localid) return +1;
+static int ssh_channelcmp(void *av, void *bv)
+{
+    struct ssh_channel *a = (struct ssh_channel *) av;
+    struct ssh_channel *b = (struct ssh_channel *) bv;
+    if (a->localid < b->localid)
+       return -1;
+    if (a->localid > b->localid)
+       return +1;
+    return 0;
+}
+static int ssh_channelfind(void *av, void *bv)
+{
+    unsigned *a = (unsigned *) av;
+    struct ssh_channel *b = (struct ssh_channel *) bv;
+    if (*a < b->localid)
+       return -1;
+    if (*a > b->localid)
+       return +1;
+    return 0;
+}
+
+static int ssh_rportcmp_ssh1(void *av, void *bv)
+{
+    struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
+    struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
+    int i;
+    if ( (i = strcmp(a->dhost, b->dhost)) != 0)
+       return i < 0 ? -1 : +1;
+    if (a->dport > b->dport)
+       return +1;
+    if (a->dport < b->dport)
+       return -1;
     return 0;
 }
-static int ssh_channelfind(void *av, void *bv) {
-    unsigned *a = (unsigned *)av;
-    struct ssh_channel *b = (struct ssh_channel *)bv;
-    if (*a < b->localid) return -1;
-    if (*a > b->localid) return +1;
+
+static int ssh_rportcmp_ssh2(void *av, void *bv)
+{
+    struct ssh_rportfwd *a = (struct ssh_rportfwd *) av;
+    struct ssh_rportfwd *b = (struct ssh_rportfwd *) bv;
+
+    if (a->sport > b->sport)
+       return +1;
+    if (a->sport < b->sport)
+       return -1;
     return 0;
 }
 
-static int alloc_channel_id(void) {
+static int alloc_channel_id(void)
+{
     const unsigned CHANNEL_NUMBER_OFFSET = 256;
     unsigned low, high, mid;
     int tsize;
@@ -384,7 +532,8 @@ static int alloc_channel_id(void) {
      */
     tsize = count234(ssh_channels);
 
-    low = -1; high = tsize;
+    low = -1;
+    high = tsize;
     while (high - low > 1) {
        mid = (high + low) / 2;
        c = index234(ssh_channels, mid);
@@ -404,28 +553,31 @@ static int alloc_channel_id(void) {
     return low + 1 + CHANNEL_NUMBER_OFFSET;
 }
 
-static void c_write (char *buf, int len) {
+static void c_write(char *buf, int len)
+{
     if ((flags & FLAG_STDERR)) {
-        int i;
-        for (i = 0; i < len; i++)
-            if (buf[i] != '\r')
-                fputc(buf[i], stderr);
+       int i;
+       for (i = 0; i < len; i++)
+           if (buf[i] != '\r')
+               fputc(buf[i], stderr);
        return;
     }
     from_backend(1, buf, len);
 }
 
-static void c_write_untrusted(char *buf, int len) {
+static void c_write_untrusted(char *buf, int len)
+{
     int i;
     for (i = 0; i < len; i++) {
-        if (buf[i] == '\n')
-            c_write("\r\n", 2);
-        else if ((buf[i] & 0x60) || (buf[i] == '\r'))
-            c_write(buf+i, 1);
+       if (buf[i] == '\n')
+           c_write("\r\n", 2);
+       else if ((buf[i] & 0x60) || (buf[i] == '\r'))
+           c_write(buf + i, 1);
     }
 }
 
-static void c_write_str (char *buf) {
+static void c_write_str(char *buf)
+{
     c_write(buf, strlen(buf));
 }
 
@@ -443,32 +595,26 @@ static int ssh1_rdpkt(unsigned char **data, int *datalen)
 
     crBegin;
 
-next_packet:
+  next_packet:
 
     pktin.type = 0;
     pktin.length = 0;
 
     for (st->i = st->len = 0; st->i < 4; st->i++) {
        while ((*datalen) == 0)
-           crReturn(4-st->i);
+           crReturn(4 - st->i);
        st->len = (st->len << 8) + **data;
        (*data)++, (*datalen)--;
     }
 
-#ifdef FWHACK
-    if (st->len == 0x52656d6f) {        /* "Remo"te server has closed ... */
-        st->len = 0x300;                /* big enough to carry to end */
-    }
-#endif
-
     st->pad = 8 - (st->len % 8);
     st->biglen = st->len + st->pad;
     pktin.length = st->len - 5;
 
     if (pktin.maxlen < st->biglen) {
        pktin.maxlen = st->biglen;
-       pktin.data = (pktin.data == NULL ? smalloc(st->biglen+APIEXTRA) :
-                     srealloc(pktin.data, st->biglen+APIEXTRA));
+       pktin.data = (pktin.data == NULL ? smalloc(st->biglen + APIEXTRA) :
+                     srealloc(pktin.data, st->biglen + APIEXTRA));
        if (!pktin.data)
            fatalbox("Out of memory");
     }
@@ -476,7 +622,7 @@ next_packet:
     st->to_read = st->biglen;
     st->p = pktin.data;
     while (st->to_read > 0) {
-        st->chunk = st->to_read;
+       st->chunk = st->to_read;
        while ((*datalen) == 0)
            crReturn(st->to_read);
        if (st->chunk > (*datalen))
@@ -495,11 +641,11 @@ next_packet:
     dmemdump(pktin.data, st->biglen);
 #endif
 
-    st->realcrc = crc32(pktin.data, st->biglen-4);
-    st->gotcrc = GET_32BIT(pktin.data+st->biglen-4);
+    st->realcrc = crc32(pktin.data, st->biglen - 4);
+    st->gotcrc = GET_32BIT(pktin.data + st->biglen - 4);
     if (st->gotcrc != st->realcrc) {
        bombout(("Incorrect CRC received on packet"));
-        crReturn(0);
+       crReturn(0);
     }
 
     pktin.body = pktin.data + st->pad + 1;
@@ -509,38 +655,38 @@ next_packet:
        int decomplen;
 #ifdef DUMP_PACKETS
        debug(("Packet payload pre-decompression:\n"));
-       dmemdump(pktin.body-1, pktin.length+1);
+       dmemdump(pktin.body - 1, pktin.length + 1);
 #endif
-       zlib_decompress_block(pktin.body-1, pktin.length+1,
+       zlib_decompress_block(pktin.body - 1, pktin.length + 1,
                              &decompblk, &decomplen);
 
        if (pktin.maxlen < st->pad + decomplen) {
            pktin.maxlen = st->pad + decomplen;
-           pktin.data = srealloc(pktin.data, pktin.maxlen+APIEXTRA);
-            pktin.body = pktin.data + st->pad + 1;
+           pktin.data = srealloc(pktin.data, pktin.maxlen + APIEXTRA);
+           pktin.body = pktin.data + st->pad + 1;
            if (!pktin.data)
                fatalbox("Out of memory");
        }
 
-       memcpy(pktin.body-1, decompblk, decomplen);
+       memcpy(pktin.body - 1, decompblk, decomplen);
        sfree(decompblk);
-       pktin.length = decomplen-1;
+       pktin.length = decomplen - 1;
 #ifdef DUMP_PACKETS
        debug(("Packet payload post-decompression:\n"));
-       dmemdump(pktin.body-1, pktin.length+1);
+       dmemdump(pktin.body - 1, pktin.length + 1);
 #endif
     }
 
     if (pktin.type == SSH1_SMSG_STDOUT_DATA ||
-        pktin.type == SSH1_SMSG_STDERR_DATA ||
-        pktin.type == SSH1_MSG_DEBUG ||
-        pktin.type == SSH1_SMSG_AUTH_TIS_CHALLENGE ||
-        pktin.type == SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
+       pktin.type == SSH1_SMSG_STDERR_DATA ||
+       pktin.type == SSH1_MSG_DEBUG ||
+       pktin.type == SSH1_SMSG_AUTH_TIS_CHALLENGE ||
+       pktin.type == SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
        long strlen = GET_32BIT(pktin.body);
        if (strlen + 4 != pktin.length) {
            bombout(("Received data packet with bogus string length"));
-            crReturn(0);
-        }
+           crReturn(0);
+       }
     }
 
     pktin.type = pktin.body[-1];
@@ -550,9 +696,10 @@ next_packet:
        char buf[80];
        int strlen = GET_32BIT(pktin.body);
        strcpy(buf, "Remote: ");
-       if (strlen > 70) strlen = 70;
-       memcpy(buf+8, pktin.body+4, strlen);
-       buf[8+strlen] = '\0';
+       if (strlen > 70)
+           strlen = 70;
+       memcpy(buf + 8, pktin.body + 4, strlen);
+       buf[8 + strlen] = '\0';
        logevent(buf);
        goto next_packet;
     } else if (pktin.type == SSH1_MSG_IGNORE) {
@@ -567,11 +714,13 @@ next_packet:
        unsigned nowlen;
        strcpy(buf, "Remote sent disconnect: ");
        nowlen = strlen(buf);
-       if (msglen > sizeof(buf)-nowlen-1)
-           msglen = sizeof(buf)-nowlen-1;
-       memcpy(buf+nowlen, pktin.body+4, msglen);
-       buf[nowlen+msglen] = '\0';
+       if (msglen > sizeof(buf) - nowlen - 1)
+           msglen = sizeof(buf) - nowlen - 1;
+       memcpy(buf + nowlen, pktin.body + 4, msglen);
+       buf[nowlen + msglen] = '\0';
        logevent(buf);
+       bombout(("Server sent disconnect message:\n\"%s\"", buf+nowlen));
+       crReturn(0);
     }
 
     crFinish(0);
@@ -583,20 +732,24 @@ static int ssh2_rdpkt(unsigned char **data, int *datalen)
 
     crBegin;
 
-next_packet:
+  next_packet:
     pktin.type = 0;
     pktin.length = 0;
     if (sccipher)
-        st->cipherblk = sccipher->blksize;
+       st->cipherblk = sccipher->blksize;
     else
-        st->cipherblk = 8;
+       st->cipherblk = 8;
     if (st->cipherblk < 8)
-        st->cipherblk = 8;
+       st->cipherblk = 8;
 
     if (pktin.maxlen < st->cipherblk) {
        pktin.maxlen = st->cipherblk;
-       pktin.data = (pktin.data == NULL ? smalloc(st->cipherblk+APIEXTRA) :
-                     srealloc(pktin.data, st->cipherblk+APIEXTRA));
+       pktin.data =
+           (pktin.data ==
+            NULL ? smalloc(st->cipherblk +
+                           APIEXTRA) : srealloc(pktin.data,
+                                                st->cipherblk +
+                                                APIEXTRA));
        if (!pktin.data)
            fatalbox("Out of memory");
     }
@@ -605,19 +758,15 @@ next_packet:
      * Acquire and decrypt the first block of the packet. This will
      * contain the length and padding details.
      */
-     for (st->i = st->len = 0; st->i < st->cipherblk; st->i++) {
+    for (st->i = st->len = 0; st->i < st->cipherblk; st->i++) {
        while ((*datalen) == 0)
-           crReturn(st->cipherblk-st->i);
+           crReturn(st->cipherblk - st->i);
        pktin.data[st->i] = *(*data)++;
-        (*datalen)--;
-    }
-#ifdef FWHACK
-    if (!memcmp(pktin.data, "Remo", 4)) {/* "Remo"te server has closed ... */
-        /* FIXME */
+       (*datalen)--;
     }
-#endif
+
     if (sccipher)
-        sccipher->decrypt(pktin.data, st->cipherblk);
+       sccipher->decrypt(pktin.data, st->cipherblk);
 
     /*
      * Now get the length and padding figures.
@@ -641,10 +790,14 @@ next_packet:
     /*
      * Adjust memory allocation if packet is too big.
      */
-    if (pktin.maxlen < st->packetlen+st->maclen) {
-       pktin.maxlen = st->packetlen+st->maclen;
-       pktin.data = (pktin.data == NULL ? smalloc(pktin.maxlen+APIEXTRA) :
-                     srealloc(pktin.data, pktin.maxlen+APIEXTRA));
+    if (pktin.maxlen < st->packetlen + st->maclen) {
+       pktin.maxlen = st->packetlen + st->maclen;
+       pktin.data =
+           (pktin.data ==
+            NULL ? smalloc(pktin.maxlen + APIEXTRA) : srealloc(pktin.data,
+                                                               pktin.maxlen
+                                                               +
+                                                               APIEXTRA));
        if (!pktin.data)
            fatalbox("Out of memory");
     }
@@ -652,16 +805,17 @@ next_packet:
     /*
      * Read and decrypt the remainder of the packet.
      */
-    for (st->i = st->cipherblk; st->i < st->packetlen + st->maclen; st->i++) {
+    for (st->i = st->cipherblk; st->i < st->packetlen + st->maclen;
+        st->i++) {
        while ((*datalen) == 0)
            crReturn(st->packetlen + st->maclen - st->i);
        pktin.data[st->i] = *(*data)++;
-        (*datalen)--;
+       (*datalen)--;
     }
     /* Decrypt everything _except_ the MAC. */
     if (sccipher)
-        sccipher->decrypt(pktin.data + st->cipherblk,
-                          st->packetlen - st->cipherblk);
+       sccipher->decrypt(pktin.data + st->cipherblk,
+                         st->packetlen - st->cipherblk);
 
 #ifdef DUMP_PACKETS
     debug(("Got packet len=%d pad=%d\n", st->len, st->pad));
@@ -671,11 +825,13 @@ next_packet:
     /*
      * Check the MAC.
      */
-    if (scmac && !scmac->verify(pktin.data, st->len+4, st->incoming_sequence)) {
+    if (scmac
+       && !scmac->verify(pktin.data, st->len + 4,
+                         st->incoming_sequence)) {
        bombout(("Incorrect MAC received on packet"));
-        crReturn(0);
+       crReturn(0);
     }
-    st->incoming_sequence++;               /* whether or not we MACed */
+    st->incoming_sequence++;          /* whether or not we MACed */
 
     /*
      * Decompress packet payload.
@@ -683,20 +839,24 @@ next_packet:
     {
        unsigned char *newpayload;
        int newlen;
-       if (sccomp && sccomp->decompress(pktin.data+5, pktin.length-5,
+       if (sccomp && sccomp->decompress(pktin.data + 5, pktin.length - 5,
                                         &newpayload, &newlen)) {
-           if (pktin.maxlen < newlen+5) {
-               pktin.maxlen = newlen+5;
-               pktin.data = (pktin.data == NULL ? smalloc(pktin.maxlen+APIEXTRA) :
-                             srealloc(pktin.data, pktin.maxlen+APIEXTRA));
+           if (pktin.maxlen < newlen + 5) {
+               pktin.maxlen = newlen + 5;
+               pktin.data =
+                   (pktin.data ==
+                    NULL ? smalloc(pktin.maxlen +
+                                   APIEXTRA) : srealloc(pktin.data,
+                                                        pktin.maxlen +
+                                                        APIEXTRA));
                if (!pktin.data)
                    fatalbox("Out of memory");
            }
            pktin.length = 5 + newlen;
-           memcpy(pktin.data+5, newpayload, newlen);
+           memcpy(pktin.data + 5, newpayload, newlen);
 #ifdef DUMP_PACKETS
            debug(("Post-decompression payload:\n"));
-           dmemdump(pktin.data+5, newlen);
+           dmemdump(pktin.data + 5, newlen);
 #endif
 
            sfree(newpayload);
@@ -707,122 +867,131 @@ next_packet:
     pktin.type = pktin.data[5];
 
     if (pktin.type == SSH2_MSG_IGNORE || pktin.type == SSH2_MSG_DEBUG)
-        goto next_packet;              /* FIXME: print DEBUG message */
+       goto next_packet;              /* FIXME: print DEBUG message */
 
     if (pktin.type == SSH2_MSG_DISCONNECT) {
        /* log reason code in disconnect message */
        char buf[256];
-       int reason = GET_32BIT(pktin.data+6);
-       unsigned msglen = GET_32BIT(pktin.data+10);
+       int reason = GET_32BIT(pktin.data + 6);
+       unsigned msglen = GET_32BIT(pktin.data + 10);
        unsigned nowlen;
        if (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) {
            sprintf(buf, "Received disconnect message (%s)",
                    ssh2_disconnect_reasons[reason]);
        } else {
-           sprintf(buf, "Received disconnect message (unknown type %d)", reason);
+           sprintf(buf, "Received disconnect message (unknown type %d)",
+                   reason);
        }
        logevent(buf);
        strcpy(buf, "Disconnection message text: ");
        nowlen = strlen(buf);
-       if (msglen > sizeof(buf)-nowlen-1)
-           msglen = sizeof(buf)-nowlen-1;
-       memcpy(buf+nowlen, pktin.data+14, msglen);
-       buf[nowlen+msglen] = '\0';
+       if (msglen > sizeof(buf) - nowlen - 1)
+           msglen = sizeof(buf) - nowlen - 1;
+       memcpy(buf + nowlen, pktin.data + 14, msglen);
+       buf[nowlen + msglen] = '\0';
        logevent(buf);
+       bombout(("Server sent disconnect message\ntype %d (%s):\n\"%s\"",
+                reason,
+                (reason > 0 && reason < lenof(ssh2_disconnect_reasons)) ?
+                ssh2_disconnect_reasons[reason] : "unknown",
+                buf+nowlen));
+       crReturn(0);
     }
 
     crFinish(0);
 }
 
-static void ssh1_pktout_size(int len) {
+static void ssh1_pktout_size(int len)
+{
     int pad, biglen;
 
     len += 5;                         /* type and CRC */
-    pad = 8 - (len%8);
+    pad = 8 - (len % 8);
     biglen = len + pad;
 
-    pktout.length = len-5;
+    pktout.length = len - 5;
     if (pktout.maxlen < biglen) {
        pktout.maxlen = biglen;
 #ifdef MSCRYPTOAPI
        /* Allocate enough buffer space for extra block
         * for MS CryptEncrypt() */
-       pktout.data = (pktout.data == NULL ? smalloc(biglen+12) :
-                      srealloc(pktout.data, biglen+12));
+       pktout.data = (pktout.data == NULL ? smalloc(biglen + 12) :
+                      srealloc(pktout.data, biglen + 12));
 #else
-       pktout.data = (pktout.data == NULL ? smalloc(biglen+4) :
-                      srealloc(pktout.data, biglen+4));
+       pktout.data = (pktout.data == NULL ? smalloc(biglen + 4) :
+                      srealloc(pktout.data, biglen + 4));
 #endif
        if (!pktout.data)
            fatalbox("Out of memory");
     }
-    pktout.body = pktout.data+4+pad+1;
+    pktout.body = pktout.data + 4 + pad + 1;
 }
 
-static void s_wrpkt_start(int type, int len) {
+static void s_wrpkt_start(int type, int len)
+{
     ssh1_pktout_size(len);
     pktout.type = type;
 }
 
-static int s_wrpkt_prepare(void) {
+static int s_wrpkt_prepare(void)
+{
     int pad, len, biglen, i;
     unsigned long crc;
 
     pktout.body[-1] = pktout.type;
 
-#ifdef DUMP_PACKETS
-    debug(("Packet payload pre-compression:\n"));
-    dmemdump(pktout.body-1, pktout.length+1);
-#endif
-
     if (ssh1_compressing) {
        unsigned char *compblk;
        int complen;
-       zlib_compress_block(pktout.body-1, pktout.length+1,
-                           &compblk, &complen);
-       ssh1_pktout_size(complen-1);
-       memcpy(pktout.body-1, compblk, complen);
-       sfree(compblk);
 #ifdef DUMP_PACKETS
-       debug(("Packet payload post-compression:\n"));
-       dmemdump(pktout.body-1, pktout.length+1);
+       debug(("Packet payload pre-compression:\n"));
+       dmemdump(pktout.body - 1, pktout.length + 1);
 #endif
+       zlib_compress_block(pktout.body - 1, pktout.length + 1,
+                           &compblk, &complen);
+       ssh1_pktout_size(complen - 1);
+       memcpy(pktout.body - 1, compblk, complen);
+       sfree(compblk);
     }
 
     len = pktout.length + 5;          /* type and CRC */
-    pad = 8 - (len%8);
+    pad = 8 - (len % 8);
     biglen = len + pad;
 
-    for (i=0; i<pad; i++)
-       pktout.data[i+4] = random_byte();
-    crc = crc32(pktout.data+4, biglen-4);
-    PUT_32BIT(pktout.data+biglen, crc);
+    for (i = 0; i < pad; i++)
+       pktout.data[i + 4] = random_byte();
+    crc = crc32(pktout.data + 4, biglen - 4);
+    PUT_32BIT(pktout.data + biglen, crc);
     PUT_32BIT(pktout.data, len);
 
 #ifdef DUMP_PACKETS
-    debug(("Sending packet len=%d\n", biglen+4));
-    dmemdump(pktout.data, biglen+4);
+    debug(("Sending packet len=%d\n", biglen + 4));
+    dmemdump(pktout.data, biglen + 4);
 #endif
     if (cipher)
-       cipher->encrypt(pktout.data+4, biglen);
+       cipher->encrypt(pktout.data + 4, biglen);
 
-    return biglen+4;
+    return biglen + 4;
 }
 
-static void s_wrpkt(void) {
-    int len;
+static void s_wrpkt(void)
+{
+    int len, backlog;
     len = s_wrpkt_prepare();
-    sk_write(s, pktout.data, len);
+    backlog = sk_write(s, pktout.data, len);
+    if (backlog > SSH_MAX_BACKLOG)
+       ssh_throttle_all(1, backlog);
 }
 
-static void s_wrpkt_defer(void) {
+static void s_wrpkt_defer(void)
+{
     int len;
     len = s_wrpkt_prepare();
     if (deferred_len + len > deferred_size) {
-        deferred_size = deferred_len + len + 128;
-        deferred_send_data = srealloc(deferred_send_data, deferred_size);
+       deferred_size = deferred_len + len + 128;
+       deferred_send_data = srealloc(deferred_send_data, deferred_size);
     }
-    memcpy(deferred_send_data+deferred_len, pktout.data, len);
+    memcpy(deferred_send_data + deferred_len, pktout.data, len);
     deferred_len += len;
 }
 
@@ -859,7 +1028,7 @@ static void construct_packet(int pkttype, va_list ap1, va_list ap2)
            break;
          case PKT_BIGNUM:
            bn = va_arg(ap1, Bignum);
-            pktlen += ssh1_bignum_length(bn);
+           pktlen += ssh1_bignum_length(bn);
            break;
          default:
            assert(0);
@@ -896,13 +1065,14 @@ static void construct_packet(int pkttype, va_list ap1, va_list ap2)
            break;
          case PKT_BIGNUM:
            bn = va_arg(ap2, Bignum);
-            p += ssh1_write_bignum(p, bn);
+           p += ssh1_write_bignum(p, bn);
            break;
        }
     }
 }
 
-static void send_packet(int pkttype, ...) {
+static void send_packet(int pkttype, ...)
+{
     va_list ap1, ap2;
     va_start(ap1, pkttype);
     va_start(ap2, pkttype);
@@ -910,7 +1080,8 @@ static void send_packet(int pkttype, ...) {
     s_wrpkt();
 }
 
-static void defer_packet(int pkttype, ...) {
+static void defer_packet(int pkttype, ...)
+{
     va_list ap1, ap2;
     va_start(ap1, pkttype);
     va_start(ap2, pkttype);
@@ -918,18 +1089,23 @@ static void defer_packet(int pkttype, ...) {
     s_wrpkt_defer();
 }
 
-static int ssh_versioncmp(char *a, char *b) {
+static int ssh_versioncmp(char *a, char *b)
+{
     char *ae, *be;
     unsigned long av, bv;
 
     av = strtoul(a, &ae, 10);
     bv = strtoul(b, &be, 10);
-    if (av != bv) return (av < bv ? -1 : +1);
-    if (*ae == '.') ae++;
-    if (*be == '.') be++;
+    if (av != bv)
+       return (av < bv ? -1 : +1);
+    if (*ae == '.')
+       ae++;
+    if (*be == '.')
+       be++;
     av = strtoul(ae, &ae, 10);
     bv = strtoul(be, &be, 10);
-    if (av != bv) return (av < bv ? -1 : +1);
+    if (av != bv)
+       return (av < bv ? -1 : +1);
     return 0;
 }
 
@@ -939,14 +1115,16 @@ static int ssh_versioncmp(char *a, char *b) {
  * `uint32' into a SHA state.
  */
 #include <stdio.h>
-static void sha_string(SHA_State *s, void *str, int len) {
+static void sha_string(SHA_State * s, void *str, int len)
+{
     unsigned char lenblk[4];
     PUT_32BIT(lenblk, len);
     SHA_Bytes(s, lenblk, 4);
     SHA_Bytes(s, str, len);
 }
 
-static void sha_uint32(SHA_State *s, unsigned i) {
+static void sha_uint32(SHA_State * s, unsigned i)
+{
     unsigned char intblk[4];
     PUT_32BIT(intblk, i);
     SHA_Bytes(s, intblk, 4);
@@ -955,70 +1133,86 @@ static void sha_uint32(SHA_State *s, unsigned i) {
 /*
  * SSH2 packet construction functions.
  */
-static void ssh2_pkt_ensure(int length) {
+static void ssh2_pkt_ensure(int length)
+{
     if (pktout.maxlen < length) {
-        pktout.maxlen = length + 256;
-       pktout.data = (pktout.data == NULL ? smalloc(pktout.maxlen+APIEXTRA) :
-                       srealloc(pktout.data, pktout.maxlen+APIEXTRA));
-        if (!pktout.data)
-            fatalbox("Out of memory");
+       pktout.maxlen = length + 256;
+       pktout.data =
+           (pktout.data ==
+            NULL ? smalloc(pktout.maxlen +
+                           APIEXTRA) : srealloc(pktout.data,
+                                                pktout.maxlen +
+                                                APIEXTRA));
+       if (!pktout.data)
+           fatalbox("Out of memory");
     }
 }
-static void ssh2_pkt_adddata(void *data, int len) {
+static void ssh2_pkt_adddata(void *data, int len)
+{
     pktout.length += len;
     ssh2_pkt_ensure(pktout.length);
-    memcpy(pktout.data+pktout.length-len, data, len);
+    memcpy(pktout.data + pktout.length - len, data, len);
 }
-static void ssh2_pkt_addbyte(unsigned char byte) {
+static void ssh2_pkt_addbyte(unsigned char byte)
+{
     ssh2_pkt_adddata(&byte, 1);
 }
-static void ssh2_pkt_init(int pkt_type) {
+static void ssh2_pkt_init(int pkt_type)
+{
     pktout.length = 5;
-    ssh2_pkt_addbyte((unsigned char)pkt_type);
+    ssh2_pkt_addbyte((unsigned char) pkt_type);
 }
-static void ssh2_pkt_addbool(unsigned char value) {
+static void ssh2_pkt_addbool(unsigned char value)
+{
     ssh2_pkt_adddata(&value, 1);
 }
-static void ssh2_pkt_adduint32(unsigned long value) {
+static void ssh2_pkt_adduint32(unsigned long value)
+{
     unsigned char x[4];
     PUT_32BIT(x, value);
     ssh2_pkt_adddata(x, 4);
 }
-static void ssh2_pkt_addstring_start(void) {
+static void ssh2_pkt_addstring_start(void)
+{
     ssh2_pkt_adduint32(0);
     pktout.savedpos = pktout.length;
 }
-static void ssh2_pkt_addstring_str(char *data) {
+static void ssh2_pkt_addstring_str(char *data)
+{
     ssh2_pkt_adddata(data, strlen(data));
     PUT_32BIT(pktout.data + pktout.savedpos - 4,
-              pktout.length - pktout.savedpos);
+             pktout.length - pktout.savedpos);
 }
-static void ssh2_pkt_addstring_data(char *data, int len) {
+static void ssh2_pkt_addstring_data(char *data, int len)
+{
     ssh2_pkt_adddata(data, len);
     PUT_32BIT(pktout.data + pktout.savedpos - 4,
-              pktout.length - pktout.savedpos);
+             pktout.length - pktout.savedpos);
 }
-static void ssh2_pkt_addstring(char *data) {
+static void ssh2_pkt_addstring(char *data)
+{
     ssh2_pkt_addstring_start();
     ssh2_pkt_addstring_str(data);
 }
-static char *ssh2_mpint_fmt(Bignum b, int *len) {
+static char *ssh2_mpint_fmt(Bignum b, int *len)
+{
     unsigned char *p;
-    int i, n = (bignum_bitcount(b)+7)/8;
+    int i, n = (bignum_bitcount(b) + 7) / 8;
     p = smalloc(n + 1);
     if (!p)
-        fatalbox("out of memory");
+       fatalbox("out of memory");
     p[0] = 0;
     for (i = 1; i <= n; i++)
-        p[i] = bignum_byte(b, n-i);
+       p[i] = bignum_byte(b, n - i);
     i = 0;
-    while (i <= n && p[i] == 0 && (p[i+1] & 0x80) == 0)
-        i++;
-    memmove(p, p+i, n+1-i);
-    *len = n+1-i;
+    while (i <= n && p[i] == 0 && (p[i + 1] & 0x80) == 0)
+       i++;
+    memmove(p, p + i, n + 1 - i);
+    *len = n + 1 - i;
     return p;
 }
-static void ssh2_pkt_addmp(Bignum b) {
+static void ssh2_pkt_addmp(Bignum b)
+{
     unsigned char *p;
     int len;
     p = ssh2_mpint_fmt(b, &len);
@@ -1032,21 +1226,24 @@ static void ssh2_pkt_addmp(Bignum b) {
  * put the MAC on it. Final packet, ready to be sent, is stored in
  * pktout.data. Total length is returned.
  */
-static int ssh2_pkt_construct(void) {
+static int ssh2_pkt_construct(void)
+{
     int cipherblk, maclen, padding, i;
     static unsigned long outgoing_sequence = 0;
 
     /*
      * Compress packet payload.
      */
-#ifdef DUMP_PACKETS
-    debug(("Pre-compression payload:\n"));
-    dmemdump(pktout.data+5, pktout.length-5);
-#endif
     {
        unsigned char *newpayload;
        int newlen;
-       if (cscomp && cscomp->compress(pktout.data+5, pktout.length-5,
+#ifdef DUMP_PACKETS
+       if (cscomp && cscomp != &ssh_comp_none) {
+           debug(("Pre-compression payload:\n"));
+           dmemdump(pktout.data + 5, pktout.length - 5);
+       }
+#endif
+       if (cscomp && cscomp->compress(pktout.data + 5, pktout.length - 5,
                                       &newpayload, &newlen)) {
            pktout.length = 5;
            ssh2_pkt_adddata(newpayload, newlen);
@@ -1058,28 +1255,29 @@ static int ssh2_pkt_construct(void) {
      * Add padding. At least four bytes, and must also bring total
      * length (minus MAC) up to a multiple of the block size.
      */
-    cipherblk = cscipher ? cscipher->blksize : 8;   /* block size */
-    cipherblk = cipherblk < 8 ? 8 : cipherblk;   /* or 8 if blksize < 8 */
+    cipherblk = cscipher ? cscipher->blksize : 8;      /* block size */
+    cipherblk = cipherblk < 8 ? 8 : cipherblk; /* or 8 if blksize < 8 */
     padding = 4;
-    padding += (cipherblk - (pktout.length + padding) % cipherblk) % cipherblk;
+    padding +=
+       (cipherblk - (pktout.length + padding) % cipherblk) % cipherblk;
     maclen = csmac ? csmac->len : 0;
     ssh2_pkt_ensure(pktout.length + padding + maclen);
     pktout.data[4] = padding;
     for (i = 0; i < padding; i++)
-        pktout.data[pktout.length + i] = random_byte();
+       pktout.data[pktout.length + i] = random_byte();
     PUT_32BIT(pktout.data, pktout.length + padding - 4);
     if (csmac)
-        csmac->generate(pktout.data, pktout.length + padding,
-                        outgoing_sequence);
-    outgoing_sequence++;               /* whether or not we MACed */
+       csmac->generate(pktout.data, pktout.length + padding,
+                       outgoing_sequence);
+    outgoing_sequence++;              /* whether or not we MACed */
 
 #ifdef DUMP_PACKETS
-    debug(("Sending packet len=%d\n", pktout.length+padding));
-    dmemdump(pktout.data, pktout.length+padding);
+    debug(("Sending packet len=%d\n", pktout.length + padding));
+    dmemdump(pktout.data, pktout.length + padding);
 #endif
 
     if (cscipher)
-        cscipher->encrypt(pktout.data, pktout.length + padding);
+       cscipher->encrypt(pktout.data, pktout.length + padding);
 
     /* Ready-to-send packet starts at pktout.data. We return length. */
     return pktout.length + padding + maclen;
@@ -1088,9 +1286,14 @@ static int ssh2_pkt_construct(void) {
 /*
  * Construct and send an SSH2 packet immediately.
  */
-static void ssh2_pkt_send(void) {
-    int len = ssh2_pkt_construct();
-    sk_write(s, pktout.data, len);
+static void ssh2_pkt_send(void)
+{
+    int len;
+    int backlog;
+    len = ssh2_pkt_construct();
+    backlog = sk_write(s, pktout.data, len);
+    if (backlog > SSH_MAX_BACKLOG)
+       ssh_throttle_all(1, backlog);
 }
 
 /*
@@ -1104,13 +1307,14 @@ static void ssh2_pkt_send(void) {
  * NOT be used as an m4-style `defer' allowing packets to be
  * constructed in one order and sent in another.
  */
-static void ssh2_pkt_defer(void) {
+static void ssh2_pkt_defer(void)
+{
     int len = ssh2_pkt_construct();
     if (deferred_len + len > deferred_size) {
-        deferred_size = deferred_len + len + 128;
-        deferred_send_data = srealloc(deferred_send_data, deferred_size);
+       deferred_size = deferred_len + len + 128;
+       deferred_send_data = srealloc(deferred_send_data, deferred_size);
     }
-    memcpy(deferred_send_data+deferred_len, pktout.data, len);
+    memcpy(deferred_send_data + deferred_len, pktout.data, len);
     deferred_len += len;
 }
 
@@ -1118,27 +1322,33 @@ static void ssh2_pkt_defer(void) {
  * Send the whole deferred data block constructed by
  * ssh2_pkt_defer() or SSH1's defer_packet().
  */
-static void ssh_pkt_defersend(void) {
-    sk_write(s, deferred_send_data, deferred_len);
+static void ssh_pkt_defersend(void)
+{
+    int backlog;
+    backlog = sk_write(s, deferred_send_data, deferred_len);
     deferred_len = deferred_size = 0;
     sfree(deferred_send_data);
     deferred_send_data = NULL;
+    if (backlog > SSH_MAX_BACKLOG)
+       ssh_throttle_all(1, backlog);
 }
 
 #if 0
-void bndebug(char *string, Bignum b) {
+void bndebug(char *string, Bignum b)
+{
     unsigned char *p;
     int i, len;
     p = ssh2_mpint_fmt(b, &len);
     debug(("%s", string));
     for (i = 0; i < len; i++)
-        debug((" %02x", p[i]));
+       debug((" %02x", p[i]));
     debug(("\n"));
     sfree(p);
 }
 #endif
 
-static void sha_mpint(SHA_State *s, Bignum b) {
+static void sha_mpint(SHA_State * s, Bignum b)
+{
     unsigned char *p;
     int len;
     p = ssh2_mpint_fmt(b, &len);
@@ -1149,44 +1359,48 @@ static void sha_mpint(SHA_State *s, Bignum b) {
 /*
  * SSH2 packet decode functions.
  */
-static unsigned long ssh2_pkt_getuint32(void) {
+static unsigned long ssh2_pkt_getuint32(void)
+{
     unsigned long value;
     if (pktin.length - pktin.savedpos < 4)
-        return 0;                      /* arrgh, no way to decline (FIXME?) */
-    value = GET_32BIT(pktin.data+pktin.savedpos);
+       return 0;                      /* arrgh, no way to decline (FIXME?) */
+    value = GET_32BIT(pktin.data + pktin.savedpos);
     pktin.savedpos += 4;
     return value;
 }
-static int ssh2_pkt_getbool(void) {
+static int ssh2_pkt_getbool(void)
+{
     unsigned long value;
     if (pktin.length - pktin.savedpos < 1)
-        return 0;                      /* arrgh, no way to decline (FIXME?) */
+       return 0;                      /* arrgh, no way to decline (FIXME?) */
     value = pktin.data[pktin.savedpos] != 0;
     pktin.savedpos++;
     return value;
 }
-static void ssh2_pkt_getstring(char **p, int *length) {
+static void ssh2_pkt_getstring(char **p, int *length)
+{
     *p = NULL;
     if (pktin.length - pktin.savedpos < 4)
-        return;
-    *length = GET_32BIT(pktin.data+pktin.savedpos);
+       return;
+    *length = GET_32BIT(pktin.data + pktin.savedpos);
     pktin.savedpos += 4;
     if (pktin.length - pktin.savedpos < *length)
-        return;
-    *p = pktin.data+pktin.savedpos;
+       return;
+    *p = pktin.data + pktin.savedpos;
     pktin.savedpos += *length;
 }
-static Bignum ssh2_pkt_getmp(void) {
+static Bignum ssh2_pkt_getmp(void)
+{
     char *p;
     int length;
     Bignum b;
 
     ssh2_pkt_getstring(&p, &length);
     if (!p)
-        return NULL;
+       return NULL;
     if (p[0] & 0x80) {
-        bombout(("internal error: Can't handle negative mpints"));
-        return NULL;
+       bombout(("internal error: Can't handle negative mpints"));
+       return NULL;
     }
     b = bignum_from_bytes(p, length);
     return b;
@@ -1196,8 +1410,9 @@ static Bignum ssh2_pkt_getmp(void) {
  * Examine the remote side's version string and compare it against
  * a list of known buggy implementations.
  */
-static void ssh_detect_bugs(char *vstring) {
-    char *imp;                         /* pointer to implementation part */
+static void ssh_detect_bugs(char *vstring)
+{
+    char *imp;                        /* pointer to implementation part */
     imp = vstring;
     imp += strcspn(imp, "-");
     if (*imp) imp++;
@@ -1207,30 +1422,41 @@ static void ssh_detect_bugs(char *vstring) {
     ssh_remote_bugs = 0;
 
     if (!strcmp(imp, "1.2.18") || !strcmp(imp, "1.2.19") ||
-        !strcmp(imp, "1.2.20") || !strcmp(imp, "1.2.21") ||
-        !strcmp(imp, "1.2.22")) {
-        /*
-         * These versions don't support SSH1_MSG_IGNORE, so we have
-         * to use a different defence against password length
-         * sniffing.
-         */
-        ssh_remote_bugs |= BUG_CHOKES_ON_SSH1_IGNORE;
-        logevent("We believe remote version has SSH1 ignore bug");
+       !strcmp(imp, "1.2.20") || !strcmp(imp, "1.2.21") ||
+       !strcmp(imp, "1.2.22") || !strcmp(imp, "Cisco-1.25")) {
+       /*
+        * These versions don't support SSH1_MSG_IGNORE, so we have
+        * to use a different defence against password length
+        * sniffing.
+        */
+       ssh_remote_bugs |= BUG_CHOKES_ON_SSH1_IGNORE;
+       logevent("We believe remote version has SSH1 ignore bug");
+    }
+
+    if (!strcmp(imp, "Cisco-1.25")) {
+       /*
+        * These versions need a plain password sent; they can't
+        * handle having a null and a random length of data after
+        * the password.
+        */
+       ssh_remote_bugs |= BUG_NEEDS_SSH1_PLAIN_PASSWORD;
+       logevent("We believe remote version needs a plain SSH1 password");
     }
 
     if (!strncmp(imp, "2.1.0", 5) || !strncmp(imp, "2.0.", 4) ||
-        !strncmp(imp, "2.2.0", 5) || !strncmp(imp, "2.3.0", 5) ||
-        !strncmp(imp, "2.1 ", 4)) {
-        /*
-         * These versions have the HMAC bug.
-         */
-        ssh_remote_bugs |= BUG_SSH2_HMAC;
-        logevent("We believe remote version has SSH2 HMAC bug");
+       !strncmp(imp, "2.2.0", 5) || !strncmp(imp, "2.3.0", 5) ||
+       !strncmp(imp, "2.1 ", 4)) {
+       /*
+        * These versions have the HMAC bug.
+        */
+       ssh_remote_bugs |= BUG_SSH2_HMAC;
+       logevent("We believe remote version has SSH2 HMAC bug");
     }
 }
 
-static int do_ssh_init(unsigned char c) {
-    static char vslen;
+static int do_ssh_init(unsigned char c)
+{
+    static int vslen;
     static char version[10];
     static char *vstring;
     static int vstrsize;
@@ -1245,35 +1471,38 @@ static int do_ssh_init(unsigned char c) {
        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') i = transS[i];
-       else if (c == 'H') i = transH[i];
-       else if (c == '-') i = transminus[i];
-       else i = 0;
+       if (c == 'S')
+           i = transS[i];
+       else if (c == 'H')
+           i = transH[i];
+       else if (c == '-')
+           i = transminus[i];
+       else
+           i = 0;
        if (i < 0)
            break;
        crReturn(1);                   /* get another character */
     }
 
-    vstring = smalloc(16);
     vstrsize = 16;
+    vstring = smalloc(vstrsize);
     strcpy(vstring, "SSH-");
     vslen = 4;
     i = 0;
     while (1) {
        crReturn(1);                   /* get another char */
-       if (vslen >= vstrsize-1) {
-            vstrsize += 16;
-            vstring = srealloc(vstring, vstrsize);
-        }
-        vstring[vslen++] = c;
+       if (vslen >= vstrsize - 1) {
+           vstrsize += 16;
+           vstring = srealloc(vstring, vstrsize);
+       }
+       vstring[vslen++] = c;
        if (i >= 0) {
            if (c == '-') {
                version[i] = '\0';
                i = -1;
-           } else if (i < sizeof(version)-1)
+           } else if (i < sizeof(version) - 1)
                version[i++] = c;
-       }
-       else if (c == '\n')
+       } else if (c == '\n')
            break;
     }
 
@@ -1282,10 +1511,10 @@ static int do_ssh_init(unsigned char c) {
 
     vstring[vslen] = 0;
     vlog = smalloc(20 + vslen);
+    vstring[strcspn (vstring, "\r\n")] = '\0'; /* remove end-of-line chars */
     sprintf(vlog, "Server version: %s", vstring);
-    ssh_detect_bugs(vstring);
-    vlog[strcspn(vlog, "\r\n")] = '\0';
     logevent(vlog);
+    ssh_detect_bugs(vstring);
     sfree(vlog);
 
     /*
@@ -1293,41 +1522,41 @@ static int do_ssh_init(unsigned char c) {
      * or v2 protocol. Choice is based on cfg.sshprot.
      */
     if (ssh_versioncmp(version, cfg.sshprot == 1 ? "2.0" : "1.99") >= 0) {
-        /*
-         * This is a v2 server. Begin v2 protocol.
-         */
-        char verstring[80], vlog[100];
-        sprintf(verstring, "SSH-2.0-%s", sshver);
-        SHA_Init(&exhashbase);
-        /*
-         * Hash our version string and their version string.
-         */
-        sha_string(&exhashbase, verstring, strlen(verstring));
-        sha_string(&exhashbase, vstring, strcspn(vstring, "\r\n"));
-        sprintf(vlog, "We claim version: %s", verstring);
-        logevent(vlog);
-        strcat(verstring, "\n");
-        logevent("Using SSH protocol version 2");
-        sk_write(s, verstring, strlen(verstring));
-        ssh_protocol = ssh2_protocol;
-        ssh_version = 2;
-        s_rdpkt = ssh2_rdpkt;
+       /*
+        * This is a v2 server. Begin v2 protocol.
+        */
+       char verstring[80], vlog[100];
+       sprintf(verstring, "SSH-2.0-%s", sshver);
+       SHA_Init(&exhashbase);
+       /*
+        * Hash our version string and their version string.
+        */
+       sha_string(&exhashbase, verstring, strlen(verstring));
+       sha_string(&exhashbase, vstring, strcspn(vstring, "\r\n"));
+       sprintf(vlog, "We claim version: %s", verstring);
+       logevent(vlog);
+       strcat(verstring, "\n");
+       logevent("Using SSH protocol version 2");
+       sk_write(s, verstring, strlen(verstring));
+       ssh_protocol = ssh2_protocol;
+       ssh_version = 2;
+       s_rdpkt = ssh2_rdpkt;
     } else {
-        /*
-         * This is a v1 server. Begin v1 protocol.
-         */
-        char verstring[80], vlog[100];
-        sprintf(verstring, "SSH-%s-%s",
-                (ssh_versioncmp(version, "1.5") <= 0 ? version : "1.5"),
-                sshver);
-        sprintf(vlog, "We claim version: %s", verstring);
-        logevent(vlog);
-        strcat(verstring, "\n");
-        logevent("Using SSH protocol version 1");
-        sk_write(s, verstring, strlen(verstring));
-        ssh_protocol = ssh1_protocol;
-        ssh_version = 1;
-        s_rdpkt = ssh1_rdpkt;
+       /*
+        * This is a v1 server. Begin v1 protocol.
+        */
+       char verstring[80], vlog[100];
+       sprintf(verstring, "SSH-%s-%s",
+               (ssh_versioncmp(version, "1.5") <= 0 ? version : "1.5"),
+               sshver);
+       sprintf(vlog, "We claim version: %s", verstring);
+       logevent(vlog);
+       strcat(verstring, "\n");
+       logevent("Using SSH protocol version 1");
+       sk_write(s, verstring, strlen(verstring));
+       ssh_protocol = ssh1_protocol;
+       ssh_version = 1;
+       s_rdpkt = ssh1_rdpkt;
     }
     ssh_state = SSH_STATE_BEFORE_SIZE;
 
@@ -1351,7 +1580,8 @@ static void ssh_gotdata(unsigned char *data, int datalen)
        if (datalen == 0)
            crReturnV;                 /* more data please */
        ret = do_ssh_init(*data);
-       data++; datalen--;
+       data++;
+       datalen--;
        if (ret == 0)
            break;
     }
@@ -1366,7 +1596,10 @@ static void ssh_gotdata(unsigned char *data, int datalen)
        crReturnV;
     while (1) {
        while (datalen > 0) {
-           if ( s_rdpkt(&data, &datalen) == 0 ) {
+           if (s_rdpkt(&data, &datalen) == 0) {
+               if (ssh_state == SSH_STATE_CLOSED) {
+                   return;
+               }
                ssh_protocol(NULL, 0, 1);
                if (ssh_state == SSH_STATE_CLOSED) {
                    return;
@@ -1378,41 +1611,59 @@ static void ssh_gotdata(unsigned char *data, int datalen)
     crFinishV;
 }
 
-static int ssh_closing (Plug plug, char *error_msg, int error_code, int calling_back) {
+static int ssh_closing(Plug plug, char *error_msg, int error_code,
+                      int calling_back)
+{
     ssh_state = SSH_STATE_CLOSED;
-    sk_close(s);
-    s = NULL;
+    if (s) {
+        sk_close(s);
+        s = NULL;
+    }
     if (error_msg) {
-        /* A socket error has occurred. */
-        connection_fatal (error_msg);
+       /* A socket error has occurred. */
+       connection_fatal(error_msg);
     } else {
        /* Otherwise, the remote side closed the connection normally. */
     }
     return 0;
 }
 
-static int ssh_receive(Plug plug, int urgent, char *data, int len) {
-    ssh_gotdata (data, len);
+static int ssh_receive(Plug plug, int urgent, char *data, int len)
+{
+    ssh_gotdata(data, len);
     if (ssh_state == SSH_STATE_CLOSED) {
-        if (s) {
-            sk_close(s);
-            s = NULL;
-        }
-        return 0;
+       if (s) {
+           sk_close(s);
+           s = NULL;
+       }
+       return 0;
     }
     return 1;
 }
 
+static void ssh_sent(Plug plug, int bufsize)
+{
+    /*
+     * If the send backlog on the SSH socket itself clears, we
+     * should unthrottle the whole world if it was throttled.
+     */
+    if (bufsize < SSH_MAX_BACKLOG)
+       ssh_throttle_all(0, bufsize);
+}
+
 /*
  * Connect to specified host and port.
  * Returns an error message, or NULL on success.
- * Also places the canonical host name into `realhost'.
+ * Also places the canonical host name into `realhost'. It must be
+ * freed by the caller.
  */
-static char *connect_to_host(char *host, int port, char **realhost)
+static char *connect_to_host(char *host, int port, char **realhost, int nodelay)
 {
     static struct plug_function_table fn_table = {
        ssh_closing,
-       ssh_receive
+       ssh_receive,
+       ssh_sent,
+       NULL
     }, *fn_table_ptr = &fn_table;
 
     SockAddr addr;
@@ -1422,7 +1673,7 @@ static char *connect_to_host(char *host, int port, char **realhost)
     int FWport;
 #endif
 
-    savedhost = smalloc(1+strlen(host));
+    savedhost = smalloc(1 + strlen(host));
     if (!savedhost)
        fatalbox("Out of memory");
     strcpy(savedhost, host);
@@ -1441,19 +1692,30 @@ static char *connect_to_host(char *host, int port, char **realhost)
     /*
      * Try to find host.
      */
+    {
+       char buf[200];
+       sprintf(buf, "Looking up host \"%.170s\"", host);
+       logevent(buf);
+    }
     addr = sk_namelookup(host, realhost);
-    if ( (err = sk_addr_error(addr)) )
+    if ((err = sk_addr_error(addr)))
        return err;
 
 #ifdef FWHACK
-    *realhost = FWhost;
+    *realhost = strdup(FWhost);
 #endif
 
     /*
      * Open socket.
      */
-    s = sk_new(addr, port, 0, 1, &fn_table_ptr);
-    if ( (err = sk_socket_error(s)) )
+    {
+       char buf[200], addrbuf[100];
+       sk_getaddr(addr, addrbuf, 100);
+       sprintf(buf, "Connecting to %.100s port %d", addrbuf, port);
+       logevent(buf);
+    }
+    s = sk_new(addr, port, 0, 1, nodelay, &fn_table_ptr);
+    if ((err = sk_socket_error(s)))
        return err;
 
 #ifdef FWHACK
@@ -1470,36 +1732,89 @@ static char *connect_to_host(char *host, int port, char **realhost)
 }
 
 /*
+ * Throttle or unthrottle the SSH connection.
+ */
+static void ssh1_throttle(int adjust)
+{
+    int old_count = ssh1_throttle_count;
+    ssh1_throttle_count += adjust;
+    assert(ssh1_throttle_count >= 0);
+    if (ssh1_throttle_count && !old_count) {
+       sk_set_frozen(s, 1);
+    } else if (!ssh1_throttle_count && old_count) {
+       sk_set_frozen(s, 0);
+    }
+}
+
+/*
+ * Throttle or unthrottle _all_ local data streams (for when sends
+ * on the SSH connection itself back up).
+ */
+static void ssh_throttle_all(int enable, int bufsize)
+{
+    int i;
+    struct ssh_channel *c;
+
+    if (enable == ssh_throttled_all)
+       return;
+    ssh_throttled_all = enable;
+    ssh_overall_bufsize = bufsize;
+    if (!ssh_channels)
+       return;
+    for (i = 0; NULL != (c = index234(ssh_channels, i)); i++) {
+       switch (c->type) {
+         case CHAN_MAINSESSION:
+           /*
+            * This is treated separately, outside the switch.
+            */
+           break;
+         case CHAN_X11:
+           x11_override_throttle(c->u.x11.s, enable);
+           break;
+         case CHAN_AGENT:
+           /* Agent channels require no buffer management. */
+           break;
+         case CHAN_SOCKDATA:
+           pfd_override_throttle(c->u.x11.s, enable);
+           break;
+       }
+    }
+}
+
+/*
  * Handle the key exchange and user authentication phases.
  */
 static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
 {
-    int i, j, len;
-    unsigned char *rsabuf, *keystr1, *keystr2;
+    int i, j;
+    static int len;
+    static unsigned char *rsabuf, *keystr1, *keystr2;
     unsigned char cookie[8];
     struct RSAKey servkey, hostkey;
     struct MD5Context md5c;
     static unsigned long supported_ciphers_mask, supported_auths_mask;
     static int tried_publickey;
+    static int tis_auth_refused, ccard_auth_refused;
     static unsigned char session_id[16];
-    int cipher_type;
+    static int cipher_type;
     static char username[100];
 
     crBegin;
 
-    if (!ispkt) crWaitUntil(ispkt);
+    if (!ispkt)
+       crWaitUntil(ispkt);
 
     if (pktin.type != SSH1_SMSG_PUBLIC_KEY) {
        bombout(("Public key packet not received"));
-        crReturn(0);
+       crReturn(0);
     }
 
     logevent("Received public keys");
 
     memcpy(cookie, pktin.body, 8);
 
-    i = makekey(pktin.body+8, &servkey, &keystr1, 0);
-    j = makekey(pktin.body+8+i, &hostkey, &keystr2, 0);
+    i = makekey(pktin.body + 8, &servkey, &keystr1, 0);
+    j = makekey(pktin.body + 8 + i, &hostkey, &keystr2, 0);
 
     /*
      * Log the host key fingerprint.
@@ -1508,17 +1823,18 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
        char logmsg[80];
        logevent("Host key fingerprint is:");
        strcpy(logmsg, "      ");
-        hostkey.comment = NULL;
-        rsa_fingerprint(logmsg+strlen(logmsg), sizeof(logmsg)-strlen(logmsg),
-                        &hostkey);
+       hostkey.comment = NULL;
+       rsa_fingerprint(logmsg + strlen(logmsg),
+                       sizeof(logmsg) - strlen(logmsg), &hostkey);
        logevent(logmsg);
     }
 
-    ssh1_remote_protoflags = GET_32BIT(pktin.body+8+i+j);
-    supported_ciphers_mask = GET_32BIT(pktin.body+12+i+j);
-    supported_auths_mask = GET_32BIT(pktin.body+16+i+j);
+    ssh1_remote_protoflags = GET_32BIT(pktin.body + 8 + i + j);
+    supported_ciphers_mask = GET_32BIT(pktin.body + 12 + i + j);
+    supported_auths_mask = GET_32BIT(pktin.body + 16 + i + j);
 
-    ssh1_local_protoflags = ssh1_remote_protoflags & SSH1_PROTOFLAGS_SUPPORTED;
+    ssh1_local_protoflags =
+       ssh1_remote_protoflags & SSH1_PROTOFLAGS_SUPPORTED;
     ssh1_local_protoflags |= SSH1_PROTOFLAG_SCREEN_NUMBER;
 
     MD5Init(&md5c);
@@ -1527,7 +1843,7 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
     MD5Update(&md5c, pktin.body, 8);
     MD5Final(session_id, &md5c);
 
-    for (i=0; i<32; i++)
+    for (i = 0; i < 32; i++)
        session_key[i] = random_byte();
 
     len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
@@ -1540,21 +1856,22 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
      * Verify the host key.
      */
     {
-        /*
-         * First format the key into a string.
-         */
-        int len = rsastr_len(&hostkey);
-        char fingerprint[100];
-        char *keystr = smalloc(len);
-        if (!keystr)
-            fatalbox("Out of memory");
-        rsastr_fmt(keystr, &hostkey);
-        rsa_fingerprint(fingerprint, sizeof(fingerprint), &hostkey);
-        verify_ssh_host_key(savedhost, savedport, "rsa", keystr, fingerprint);
-        sfree(keystr);
-    }
-
-    for (i=0; i<32; i++) {
+       /*
+        * First format the key into a string.
+        */
+       int len = rsastr_len(&hostkey);
+       char fingerprint[100];
+       char *keystr = smalloc(len);
+       if (!keystr)
+           fatalbox("Out of memory");
+       rsastr_fmt(keystr, &hostkey);
+       rsa_fingerprint(fingerprint, sizeof(fingerprint), &hostkey);
+       verify_ssh_host_key(savedhost, savedport, "rsa", keystr,
+                           fingerprint);
+       sfree(keystr);
+    }
+
+    for (i = 0; i < 32; i++) {
        rsabuf[i] = session_key[i];
        if (i < 16)
            rsabuf[i] ^= session_id[i];
@@ -1570,52 +1887,77 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
 
     logevent("Encrypted session key");
 
-    switch (cfg.cipher) {
-      case CIPHER_BLOWFISH: cipher_type = SSH_CIPHER_BLOWFISH; break;
-      case CIPHER_DES:      cipher_type = SSH_CIPHER_DES;      break;
-      case CIPHER_3DES:     cipher_type = SSH_CIPHER_3DES;     break;
-      case CIPHER_AES:
-        c_write_str("AES not supported in SSH1, falling back to 3DES\r\n");
-        cipher_type = SSH_CIPHER_3DES;
-        break;
-    }
-    if ((supported_ciphers_mask & (1 << cipher_type)) == 0) {
-       c_write_str("Selected cipher not supported, falling back to 3DES\r\n");
-       cipher_type = SSH_CIPHER_3DES;
-       if ((supported_ciphers_mask & (1 << cipher_type)) == 0) {
-           bombout(("Server violates SSH 1 protocol by "
-                    "not supporting 3DES encryption"));
+    {
+       int cipher_chosen = 0, warn = 0;
+       char *cipher_string = NULL;
+       for (i = 0; !cipher_chosen && i < CIPHER_MAX; i++) {
+           int next_cipher = cfg.ssh_cipherlist[i];
+           if (next_cipher == CIPHER_WARN) {
+               /* If/when we choose a cipher, warn about it */
+               warn = 1;
+           } else if (next_cipher == CIPHER_AES) {
+               /* XXX Probably don't need to mention this. */
+               logevent("AES not supported in SSH1, skipping");
+           } else {
+               switch (next_cipher) {
+                 case CIPHER_3DES:     cipher_type = SSH_CIPHER_3DES;
+                                       cipher_string = "3DES"; break;
+                 case CIPHER_BLOWFISH: cipher_type = SSH_CIPHER_BLOWFISH;
+                                       cipher_string = "Blowfish"; break;
+                 case CIPHER_DES:      cipher_type = SSH_CIPHER_DES;
+                                       cipher_string = "single-DES"; break;
+               }
+               if (supported_ciphers_mask & (1 << cipher_type))
+                   cipher_chosen = 1;
+           }
+       }
+       if (!cipher_chosen) {
+           if ((supported_ciphers_mask & (1 << SSH_CIPHER_3DES)) == 0)
+               bombout(("Server violates SSH 1 protocol by not "
+                        "supporting 3DES encryption"));
+           else
+               /* shouldn't happen */
+               bombout(("No supported ciphers found"));
            crReturn(0);
        }
+
+       /* Warn about chosen cipher if necessary. */
+       if (warn)
+           askcipher(cipher_string, 0);
     }
+
     switch (cipher_type) {
-      case SSH_CIPHER_3DES: logevent("Using 3DES encryption"); break;
-      case SSH_CIPHER_DES: logevent("Using single-DES encryption"); break;
-      case SSH_CIPHER_BLOWFISH: logevent("Using Blowfish encryption"); break;
+      case SSH_CIPHER_3DES:
+       logevent("Using 3DES encryption");
+       break;
+      case SSH_CIPHER_DES:
+       logevent("Using single-DES encryption");
+       break;
+      case SSH_CIPHER_BLOWFISH:
+       logevent("Using Blowfish encryption");
+       break;
     }
 
     send_packet(SSH1_CMSG_SESSION_KEY,
-                PKT_CHAR, cipher_type,
-                PKT_DATA, cookie, 8,
-                PKT_CHAR, (len*8) >> 8, PKT_CHAR, (len*8) & 0xFF,
-                PKT_DATA, rsabuf, len,
-                PKT_INT, ssh1_local_protoflags,
-                PKT_END);
+               PKT_CHAR, cipher_type,
+               PKT_DATA, cookie, 8,
+               PKT_CHAR, (len * 8) >> 8, PKT_CHAR, (len * 8) & 0xFF,
+               PKT_DATA, rsabuf, len,
+               PKT_INT, ssh1_local_protoflags, PKT_END);
 
     logevent("Trying to enable encryption...");
 
     sfree(rsabuf);
 
     cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish_ssh1 :
-             cipher_type == SSH_CIPHER_DES ? &ssh_des :
-             &ssh_3des;
+       cipher_type == SSH_CIPHER_DES ? &ssh_des : &ssh_3des;
     cipher->sesskey(session_key);
 
     crWaitUntil(ispkt);
 
     if (pktin.type != SSH1_SMSG_SUCCESS) {
        bombout(("Encryption not successfully enabled"));
-        crReturn(0);
+       crReturn(0);
     }
 
     logevent("Successfully started encryption");
@@ -1625,69 +1967,75 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
        static int pos = 0;
        static char c;
        if ((flags & FLAG_INTERACTIVE) && !*cfg.username) {
-            if (ssh_get_line) {
-                if (!ssh_get_line("login as: ",
-                                  username, sizeof(username), FALSE)) {
-                    /*
-                     * get_line failed to get a username.
-                     * Terminate.
-                     */
-                    logevent("No username provided. Abandoning session.");
-                    ssh_state = SSH_STATE_CLOSED;
-                    crReturn(1);
-                }
-            } else {
-                c_write_str("login as: ");
-                ssh_send_ok = 1;
-                while (pos >= 0) {
-                    crWaitUntil(!ispkt);
-                    while (inlen--) switch (c = *in++) {
-                      case 10: case 13:
-                        username[pos] = 0;
-                        pos = -1;
-                        break;
-                      case 8: case 127:
-                        if (pos > 0) {
-                            c_write_str("\b \b");
-                            pos--;
-                        }
-                        break;
-                      case 21: case 27:
-                        while (pos > 0) {
-                            c_write_str("\b \b");
-                            pos--;
-                        }
-                        break;
-                      case 3: case 4:
-                        random_save_seed();
-                        exit(0);
-                        break;
-                      default:
-                        if (((c >= ' ' && c <= '~') ||
-                             ((unsigned char)c >= 160)) && pos < 40) {
-                            username[pos++] = c;
-                            c_write(&c, 1);
-                        }
-                        break;
-                    }
-                }
-                c_write_str("\r\n");
-                username[strcspn(username, "\n\r")] = '\0';
-            }
-        } else {
+           if (ssh_get_line) {
+               if (!ssh_get_line("login as: ",
+                                 username, sizeof(username), FALSE)) {
+                   /*
+                    * get_line failed to get a username.
+                    * Terminate.
+                    */
+                   logevent("No username provided. Abandoning session.");
+                   ssh_state = SSH_STATE_CLOSED;
+                   crReturn(1);
+               }
+           } else {
+               c_write_str("login as: ");
+               ssh_send_ok = 1;
+               while (pos >= 0) {
+                   crWaitUntil(!ispkt);
+                   while (inlen--)
+                       switch (c = *in++) {
+                         case 10:
+                         case 13:
+                           username[pos] = 0;
+                           pos = -1;
+                           break;
+                         case 8:
+                         case 127:
+                           if (pos > 0) {
+                               c_write_str("\b \b");
+                               pos--;
+                           }
+                           break;
+                         case 21:
+                         case 27:
+                           while (pos > 0) {
+                               c_write_str("\b \b");
+                               pos--;
+                           }
+                           break;
+                         case 3:
+                         case 4:
+                           random_save_seed();
+                           exit(0);
+                           break;
+                         default:
+                           if (((c >= ' ' && c <= '~') ||
+                                ((unsigned char) c >= 160))
+                               && pos < sizeof(username)-1) {
+                               username[pos++] = c;
+                               c_write(&c, 1);
+                           }
+                           break;
+                       }
+               }
+               c_write_str("\r\n");
+               username[strcspn(username, "\n\r")] = '\0';
+           }
+       } else {
            strncpy(username, cfg.username, 99);
            username[99] = '\0';
        }
 
        send_packet(SSH1_CMSG_USER, PKT_STR, username, PKT_END);
        {
-           char userlog[22+sizeof(username)];
+           char userlog[22 + sizeof(username)];
            sprintf(userlog, "Sent username \"%s\"", username);
            logevent(userlog);
-            if (flags & FLAG_INTERACTIVE &&
-                (!((flags & FLAG_STDERR) && (flags & FLAG_VERBOSE)))) {
+           if (flags & FLAG_INTERACTIVE &&
+               (!((flags & FLAG_STDERR) && (flags & FLAG_VERBOSE)))) {
                strcat(userlog, "\r\n");
-                c_write_str(userlog);
+               c_write_str(userlog);
            }
        }
     }
@@ -1695,402 +2043,473 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
     crWaitUntil(ispkt);
 
     tried_publickey = 0;
+    tis_auth_refused = ccard_auth_refused = 0;
 
     while (pktin.type == SSH1_SMSG_FAILURE) {
        static char password[100];
        static char prompt[200];
        static int pos;
        static char c;
-        static int pwpkt_type;
-        /*
-         * Show password prompt, having first obtained it via a TIS
-         * or CryptoCard exchange if we're doing TIS or CryptoCard
-         * authentication.
-         */
-        pwpkt_type = SSH1_CMSG_AUTH_PASSWORD;
-        if (agent_exists()) {
-            /*
-             * Attempt RSA authentication using Pageant.
-             */
-            static unsigned char request[5], *response, *p;
-            static int responselen;
-            static int i, nkeys;
-            static int authed = FALSE;
-            void *r;
-
-            logevent("Pageant is running. Requesting keys.");
-
-            /* Request the keys held by the agent. */
-            PUT_32BIT(request, 1);
-            request[4] = SSH1_AGENTC_REQUEST_RSA_IDENTITIES;
-            agent_query(request, 5, &r, &responselen);
-            response = (unsigned char *)r;
-            if (response && responselen >= 5 &&
-                response[4] == SSH1_AGENT_RSA_IDENTITIES_ANSWER) {
-                p = response + 5;
-                nkeys = GET_32BIT(p); p += 4;
-                { char buf[64]; sprintf(buf, "Pageant has %d SSH1 keys", nkeys);
-                    logevent(buf); }
-                for (i = 0; i < nkeys; i++) {
-                    static struct RSAKey key;
-                    static Bignum challenge;
-                    static char *commentp;
-                    static int commentlen;
-
-                    { char buf[64]; sprintf(buf, "Trying Pageant key #%d", i);
-                        logevent(buf); }
-                    p += 4;
-                    p += ssh1_read_bignum(p, &key.exponent);
-                    p += ssh1_read_bignum(p, &key.modulus);
-                    commentlen = GET_32BIT(p); p += 4;
-                    commentp = p; p += commentlen;
-                    send_packet(SSH1_CMSG_AUTH_RSA,
-                                PKT_BIGNUM, key.modulus, PKT_END);
-                    crWaitUntil(ispkt);
-                    if (pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
-                        logevent("Key refused");
-                        continue;
-                    }
-                    logevent("Received RSA challenge");
-                    ssh1_read_bignum(pktin.body, &challenge);
-                    {
-                        char *agentreq, *q, *ret;
-                        int len, retlen;
-                        len = 1 + 4;   /* message type, bit count */
-                        len += ssh1_bignum_length(key.exponent);
-                        len += ssh1_bignum_length(key.modulus);
-                        len += ssh1_bignum_length(challenge);
-                        len += 16;     /* session id */
-                        len += 4;      /* response format */
-                        agentreq = smalloc(4 + len);
-                        PUT_32BIT(agentreq, len);
-                        q = agentreq + 4;
-                        *q++ = SSH1_AGENTC_RSA_CHALLENGE;
-                        PUT_32BIT(q, bignum_bitcount(key.modulus));
-                        q += 4;
-                        q += ssh1_write_bignum(q, key.exponent);
-                        q += ssh1_write_bignum(q, key.modulus);
-                        q += ssh1_write_bignum(q, challenge);
-                        memcpy(q, session_id, 16); q += 16;
-                        PUT_32BIT(q, 1);   /* response format */
-                        agent_query(agentreq, len+4, &ret, &retlen);
-                        sfree(agentreq);
-                        if (ret) {
-                            if (ret[4] == SSH1_AGENT_RSA_RESPONSE) {
-                                logevent("Sending Pageant's response");
-                                send_packet(SSH1_CMSG_AUTH_RSA_RESPONSE,
-                                            PKT_DATA, ret+5, 16, PKT_END);
-                                sfree(ret);
-                                crWaitUntil(ispkt);
-                                if (pktin.type == SSH1_SMSG_SUCCESS) {
-                                    logevent("Pageant's response accepted");
-                                    if (flags & FLAG_VERBOSE) {
-                                        c_write_str("Authenticated using RSA key \"");
-                                        c_write(commentp, commentlen);
-                                        c_write_str("\" from agent\r\n");
-                                    }
-                                    authed = TRUE;
-                                } else
-                                    logevent("Pageant's response not accepted");
-                            } else {
-                                logevent("Pageant failed to answer challenge");
-                                sfree(ret);
-                            }
-                        } else {
-                            logevent("No reply received from Pageant");
-                        }
-                    }
-                    freebn(key.exponent);
-                    freebn(key.modulus);
-                    freebn(challenge);
-                    if (authed)
-                        break;
-                }
-            }
-            if (authed)
-                break;
-        }
-        if (*cfg.keyfile && !tried_publickey)
-            pwpkt_type = SSH1_CMSG_AUTH_RSA;
-
-        if (pktin.type == SSH1_SMSG_FAILURE &&
-            cfg.try_tis_auth &&
-            (supported_auths_mask & (1<<SSH1_AUTH_TIS))) {
-            pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE;
-            logevent("Requested TIS authentication");
-            send_packet(SSH1_CMSG_AUTH_TIS, PKT_END);
-            crWaitUntil(ispkt);
-            if (pktin.type != SSH1_SMSG_AUTH_TIS_CHALLENGE) {
-                logevent("TIS authentication declined");
-                if (flags & FLAG_INTERACTIVE)
-                    c_write_str("TIS authentication refused.\r\n");
-            } else {
-                int challengelen = ((pktin.body[0] << 24) |
-                                    (pktin.body[1] << 16) |
-                                    (pktin.body[2] << 8) |
-                                    (pktin.body[3]));
-                logevent("Received TIS challenge");
-                if (challengelen > sizeof(prompt)-1)
-                    challengelen = sizeof(prompt)-1;   /* prevent overrun */
-                memcpy(prompt, pktin.body+4, challengelen);
-                prompt[challengelen] = '\0';
-            }
-        }
-        if (pktin.type == SSH1_SMSG_FAILURE &&
-            cfg.try_tis_auth &&
-            (supported_auths_mask & (1<<SSH1_AUTH_CCARD))) {
-            pwpkt_type = SSH1_CMSG_AUTH_CCARD_RESPONSE;
-            logevent("Requested CryptoCard authentication");
-            send_packet(SSH1_CMSG_AUTH_CCARD, PKT_END);
-            crWaitUntil(ispkt);
-            if (pktin.type != SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
-                logevent("CryptoCard authentication declined");
-                c_write_str("CryptoCard authentication refused.\r\n");
-            } else {
-                int challengelen = ((pktin.body[0] << 24) |
-                                    (pktin.body[1] << 16) |
-                                    (pktin.body[2] << 8) |
-                                    (pktin.body[3]));
-                logevent("Received CryptoCard challenge");
-                if (challengelen > sizeof(prompt)-1)
-                    challengelen = sizeof(prompt)-1;   /* prevent overrun */
-                memcpy(prompt, pktin.body+4, challengelen);
-                strncpy(prompt + challengelen, "\r\nResponse : ",
-                        sizeof(prompt)-challengelen);
-                prompt[sizeof(prompt)-1] = '\0';
-            }
-        }
-        if (pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
-            sprintf(prompt, "%.90s@%.90s's password: ",
-                    username, savedhost);
-        }
-        if (pwpkt_type == SSH1_CMSG_AUTH_RSA) {
-            char *comment = NULL;
-            if (flags & FLAG_VERBOSE)
-                c_write_str("Trying public key authentication.\r\n");
-            if (!rsakey_encrypted(cfg.keyfile, &comment)) {
-                if (flags & FLAG_VERBOSE)
-                    c_write_str("No passphrase required.\r\n");
-                goto tryauth;
-            }
-            sprintf(prompt, "Passphrase for key \"%.100s\": ", comment);
-            sfree(comment);
-        }
+       static int pwpkt_type;
+       pwpkt_type = SSH1_CMSG_AUTH_PASSWORD;
+
+       if (agent_exists()) {
+           /*
+            * Attempt RSA authentication using Pageant.
+            */
+           static unsigned char request[5], *response, *p;
+           static int responselen;
+           static int i, nkeys;
+           static int authed = FALSE;
+           void *r;
+
+           logevent("Pageant is running. Requesting keys.");
+
+           /* Request the keys held by the agent. */
+           PUT_32BIT(request, 1);
+           request[4] = SSH1_AGENTC_REQUEST_RSA_IDENTITIES;
+           agent_query(request, 5, &r, &responselen);
+           response = (unsigned char *) r;
+           if (response && responselen >= 5 &&
+               response[4] == SSH1_AGENT_RSA_IDENTITIES_ANSWER) {
+               p = response + 5;
+               nkeys = GET_32BIT(p);
+               p += 4;
+               {
+                   char buf[64];
+                   sprintf(buf, "Pageant has %d SSH1 keys", nkeys);
+                   logevent(buf);
+               }
+               for (i = 0; i < nkeys; i++) {
+                   static struct RSAKey key;
+                   static Bignum challenge;
+                   static char *commentp;
+                   static int commentlen;
+
+                   {
+                       char buf[64];
+                       sprintf(buf, "Trying Pageant key #%d", i);
+                       logevent(buf);
+                   }
+                   p += 4;
+                   p += ssh1_read_bignum(p, &key.exponent);
+                   p += ssh1_read_bignum(p, &key.modulus);
+                   commentlen = GET_32BIT(p);
+                   p += 4;
+                   commentp = p;
+                   p += commentlen;
+                   send_packet(SSH1_CMSG_AUTH_RSA,
+                               PKT_BIGNUM, key.modulus, PKT_END);
+                   crWaitUntil(ispkt);
+                   if (pktin.type != SSH1_SMSG_AUTH_RSA_CHALLENGE) {
+                       logevent("Key refused");
+                       continue;
+                   }
+                   logevent("Received RSA challenge");
+                   ssh1_read_bignum(pktin.body, &challenge);
+                   {
+                       char *agentreq, *q, *ret;
+                       void *vret;
+                       int len, retlen;
+                       len = 1 + 4;   /* message type, bit count */
+                       len += ssh1_bignum_length(key.exponent);
+                       len += ssh1_bignum_length(key.modulus);
+                       len += ssh1_bignum_length(challenge);
+                       len += 16;     /* session id */
+                       len += 4;      /* response format */
+                       agentreq = smalloc(4 + len);
+                       PUT_32BIT(agentreq, len);
+                       q = agentreq + 4;
+                       *q++ = SSH1_AGENTC_RSA_CHALLENGE;
+                       PUT_32BIT(q, bignum_bitcount(key.modulus));
+                       q += 4;
+                       q += ssh1_write_bignum(q, key.exponent);
+                       q += ssh1_write_bignum(q, key.modulus);
+                       q += ssh1_write_bignum(q, challenge);
+                       memcpy(q, session_id, 16);
+                       q += 16;
+                       PUT_32BIT(q, 1);        /* response format */
+                       agent_query(agentreq, len + 4, &vret, &retlen);
+                       ret = vret;
+                       sfree(agentreq);
+                       if (ret) {
+                           if (ret[4] == SSH1_AGENT_RSA_RESPONSE) {
+                               logevent("Sending Pageant's response");
+                               send_packet(SSH1_CMSG_AUTH_RSA_RESPONSE,
+                                           PKT_DATA, ret + 5, 16,
+                                           PKT_END);
+                               sfree(ret);
+                               crWaitUntil(ispkt);
+                               if (pktin.type == SSH1_SMSG_SUCCESS) {
+                                   logevent
+                                       ("Pageant's response accepted");
+                                   if (flags & FLAG_VERBOSE) {
+                                       c_write_str
+                                           ("Authenticated using RSA key \"");
+                                       c_write(commentp, commentlen);
+                                       c_write_str("\" from agent\r\n");
+                                   }
+                                   authed = TRUE;
+                               } else
+                                   logevent
+                                       ("Pageant's response not accepted");
+                           } else {
+                               logevent
+                                   ("Pageant failed to answer challenge");
+                               sfree(ret);
+                           }
+                       } else {
+                           logevent("No reply received from Pageant");
+                       }
+                   }
+                   freebn(key.exponent);
+                   freebn(key.modulus);
+                   freebn(challenge);
+                   if (authed)
+                       break;
+               }
+           }
+           if (authed)
+               break;
+       }
+       if (*cfg.keyfile && !tried_publickey)
+           pwpkt_type = SSH1_CMSG_AUTH_RSA;
+
+       if (cfg.try_tis_auth &&
+           (supported_auths_mask & (1 << SSH1_AUTH_TIS)) &&
+           !tis_auth_refused) {
+           pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE;
+           logevent("Requested TIS authentication");
+           send_packet(SSH1_CMSG_AUTH_TIS, PKT_END);
+           crWaitUntil(ispkt);
+           if (pktin.type != SSH1_SMSG_AUTH_TIS_CHALLENGE) {
+               logevent("TIS authentication declined");
+               if (flags & FLAG_INTERACTIVE)
+                   c_write_str("TIS authentication refused.\r\n");
+               tis_auth_refused = 1;
+               continue;
+           } else {
+               int challengelen = ((pktin.body[0] << 24) |
+                                   (pktin.body[1] << 16) |
+                                   (pktin.body[2] << 8) |
+                                   (pktin.body[3]));
+               logevent("Received TIS challenge");
+               if (challengelen > sizeof(prompt) - 1)
+                   challengelen = sizeof(prompt) - 1;  /* prevent overrun */
+               memcpy(prompt, pktin.body + 4, challengelen);
+               /* Prompt heuristic comes from OpenSSH */
+               strncpy(prompt + challengelen,
+                       memchr(prompt, '\n', challengelen) ?
+                       "": "\r\nResponse: ",
+                       (sizeof prompt) - challengelen);
+               prompt[(sizeof prompt) - 1] = '\0';
+           }
+       }
+       if (cfg.try_tis_auth &&
+           (supported_auths_mask & (1 << SSH1_AUTH_CCARD)) &&
+           !ccard_auth_refused) {
+           pwpkt_type = SSH1_CMSG_AUTH_CCARD_RESPONSE;
+           logevent("Requested CryptoCard authentication");
+           send_packet(SSH1_CMSG_AUTH_CCARD, PKT_END);
+           crWaitUntil(ispkt);
+           if (pktin.type != SSH1_SMSG_AUTH_CCARD_CHALLENGE) {
+               logevent("CryptoCard authentication declined");
+               c_write_str("CryptoCard authentication refused.\r\n");
+               ccard_auth_refused = 1;
+               continue;
+           } else {
+               int challengelen = ((pktin.body[0] << 24) |
+                                   (pktin.body[1] << 16) |
+                                   (pktin.body[2] << 8) |
+                                   (pktin.body[3]));
+               logevent("Received CryptoCard challenge");
+               if (challengelen > sizeof(prompt) - 1)
+                   challengelen = sizeof(prompt) - 1;  /* prevent overrun */
+               memcpy(prompt, pktin.body + 4, challengelen);
+               strncpy(prompt + challengelen,
+                       memchr(prompt, '\n', challengelen) ?
+                       "" : "\r\nResponse: ",
+                       sizeof(prompt) - challengelen);
+               prompt[sizeof(prompt) - 1] = '\0';
+           }
+       }
+       if (pwpkt_type == SSH1_CMSG_AUTH_PASSWORD) {
+           sprintf(prompt, "%.90s@%.90s's password: ",
+                   username, savedhost);
+       }
+       if (pwpkt_type == SSH1_CMSG_AUTH_RSA) {
+           char *comment = NULL;
+           if (flags & FLAG_VERBOSE)
+               c_write_str("Trying public key authentication.\r\n");
+           if (!rsakey_encrypted(cfg.keyfile, &comment)) {
+               if (flags & FLAG_VERBOSE)
+                   c_write_str("No passphrase required.\r\n");
+               goto tryauth;
+           }
+           sprintf(prompt, "Passphrase for key \"%.100s\": ", comment);
+           sfree(comment);
+       }
 
+       /*
+        * Show password prompt, having first obtained it via a TIS
+        * or CryptoCard exchange if we're doing TIS or CryptoCard
+        * authentication.
+        */
        if (ssh_get_line) {
            if (!ssh_get_line(prompt, password, sizeof(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.
-                 */
-                logevent("No more passwords to try");
-                ssh_state = SSH_STATE_CLOSED;
-                crReturn(1);
-            }
+               /*
+                * get_line failed to get a password (for example
+                * because one was supplied on the command line
+                * which has already failed to work). Terminate.
+                */
+               send_packet(SSH1_MSG_DISCONNECT,
+                           PKT_STR, "No more passwords available to try",
+                           PKT_END);
+               connection_fatal("Unable to authenticate");
+               ssh_state = SSH_STATE_CLOSED;
+               crReturn(1);
+           }
        } else {
-            c_write_str(prompt);
-            pos = 0;
-            ssh_send_ok = 1;
-            while (pos >= 0) {
-                crWaitUntil(!ispkt);
-                while (inlen--) switch (c = *in++) {
-                  case 10: case 13:
-                    password[pos] = 0;
-                    pos = -1;
-                    break;
-                  case 8: case 127:
-                    if (pos > 0)
-                        pos--;
-                    break;
-                  case 21: case 27:
-                    pos = 0;
-                    break;
-                  case 3: case 4:
-                    random_save_seed();
-                    exit(0);
-                    break;
-                  default:
-                    if (((c >= ' ' && c <= '~') ||
-                         ((unsigned char)c >= 160)) && pos < sizeof(password))
-                        password[pos++] = c;
-                    break;
-                }
-            }
-            c_write_str("\r\n");
-        }
-
-        tryauth:
+           /* Prompt may have come from server. We've munged it a bit, so
+            * we know it to be zero-terminated at least once. */
+           c_write_untrusted(prompt, strlen(prompt));
+           pos = 0;
+           ssh_send_ok = 1;
+           while (pos >= 0) {
+               crWaitUntil(!ispkt);
+               while (inlen--)
+                   switch (c = *in++) {
+                     case 10:
+                     case 13:
+                       password[pos] = 0;
+                       pos = -1;
+                       break;
+                     case 8:
+                     case 127:
+                       if (pos > 0)
+                           pos--;
+                       break;
+                     case 21:
+                     case 27:
+                       pos = 0;
+                       break;
+                     case 3:
+                     case 4:
+                       random_save_seed();
+                       exit(0);
+                       break;
+                     default:
+                       if (pos < sizeof(password)-1)
+                           password[pos++] = c;
+                       break;
+                   }
+           }
+           c_write_str("\r\n");
+       }
+
+      tryauth:
        if (pwpkt_type == SSH1_CMSG_AUTH_RSA) {
-            /*
-             * Try public key authentication with the specified
-             * key file.
-             */
-            static struct RSAKey pubkey;
-            static Bignum challenge, response;
-            static int i;
-            static unsigned char buffer[32];
-
-            tried_publickey = 1;
-            i = loadrsakey(cfg.keyfile, &pubkey, password);
-            if (i == 0) {
-                c_write_str("Couldn't load public key from ");
-                c_write_str(cfg.keyfile);
-                c_write_str(".\r\n");
-                continue;              /* go and try password */
-            }
-            if (i == -1) {
-                c_write_str("Wrong passphrase.\r\n");
-                tried_publickey = 0;
-                continue;              /* try again */
-            }
-
-            /*
-             * Send a public key attempt.
-             */
-            send_packet(SSH1_CMSG_AUTH_RSA,
-                        PKT_BIGNUM, pubkey.modulus, PKT_END);
-
-            crWaitUntil(ispkt);
-            if (pktin.type == SSH1_SMSG_FAILURE) {
-                c_write_str("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"));
-                crReturn(0);
-            }
-            ssh1_read_bignum(pktin.body, &challenge);
-            response = rsadecrypt(challenge, &pubkey);
-            freebn(pubkey.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, session_id, 16);
-            MD5Final(buffer, &md5c);
-
-            send_packet(SSH1_CMSG_AUTH_RSA_RESPONSE,
-                        PKT_DATA, buffer, 16, PKT_END);
-
-            crWaitUntil(ispkt);
-            if (pktin.type == SSH1_SMSG_FAILURE) {
-                if (flags & FLAG_VERBOSE)
-                    c_write_str("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"));
-                crReturn(0);
-            }
-
-            break;                     /* we're through! */
-        } else {
-            if (pwpkt_type == SSH1_CMSG_AUTH_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.
-                 */
-                if (ssh_remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE) {
-                    char string[64];
-                    char *s;
-                    int len;
-
-                    len = strlen(password);
-                    if (len < sizeof(string)) {
-                        s = string;
-                        strcpy(string, password);
-                        len++;         /* cover the zero byte */
-                        while (len < sizeof(string)) {
-                            string[len++] = (char)random_byte();
-                        }
-                    } else {
-                        s = password;
-                    }
-                    send_packet(pwpkt_type, PKT_INT, len,
-                                PKT_DATA, s, len, PKT_END);
-                } else {
-                    int bottom, top, pwlen, i;
-                    char *randomstr;
-
-                    pwlen = strlen(password);
-                    if (pwlen < 16) {
-                        bottom = 0;    /* zero length passwords are OK! :-) */
-                        top = 15;
-                    } else {
-                        bottom = pwlen &~ 7;
-                        top = bottom + 7;
-                    }
-
-                    assert(pwlen >= bottom && pwlen <= top);
-
-                    randomstr = smalloc(top+1);
-
-                    for (i = bottom; i <= top; i++) {
-                        if (i == pwlen)
-                            defer_packet(pwpkt_type, PKT_STR, password, PKT_END);
-                        else {
-                            for (j = 0; j < i; j++) {
-                                do {
-                                    randomstr[j] = random_byte();
-                                } while (randomstr[j] == '\0');
-                            }
-                            randomstr[i] = '\0';
-                            defer_packet(SSH1_MSG_IGNORE,
-                                         PKT_STR, randomstr, PKT_END);
-                        }
-                    }
-                    ssh_pkt_defersend();
-                }
-            } else {
-                send_packet(pwpkt_type, PKT_STR, password, PKT_END);
-            }
-        }
+           /*
+            * Try public key authentication with the specified
+            * key file.
+            */
+           static struct RSAKey pubkey;
+           static Bignum challenge, response;
+           static int i;
+           static unsigned char buffer[32];
+
+           tried_publickey = 1;
+           i = loadrsakey(cfg.keyfile, &pubkey, password);
+           if (i == 0) {
+               c_write_str("Couldn't load private key from ");
+               c_write_str(cfg.keyfile);
+               c_write_str(".\r\n");
+               continue;              /* go and try password */
+           }
+           if (i == -1) {
+               c_write_str("Wrong passphrase.\r\n");
+               tried_publickey = 0;
+               continue;              /* try again */
+           }
+
+           /*
+            * Send a public key attempt.
+            */
+           send_packet(SSH1_CMSG_AUTH_RSA,
+                       PKT_BIGNUM, pubkey.modulus, PKT_END);
+
+           crWaitUntil(ispkt);
+           if (pktin.type == SSH1_SMSG_FAILURE) {
+               c_write_str("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"));
+               crReturn(0);
+           }
+           ssh1_read_bignum(pktin.body, &challenge);
+           response = rsadecrypt(challenge, &pubkey);
+           freebn(pubkey.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, session_id, 16);
+           MD5Final(buffer, &md5c);
+
+           send_packet(SSH1_CMSG_AUTH_RSA_RESPONSE,
+                       PKT_DATA, buffer, 16, PKT_END);
+
+           crWaitUntil(ispkt);
+           if (pktin.type == SSH1_SMSG_FAILURE) {
+               if (flags & FLAG_VERBOSE)
+                   c_write_str
+                       ("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"));
+               crReturn(0);
+           }
+
+           break;                     /* we're through! */
+       } else {
+           if (pwpkt_type == SSH1_CMSG_AUTH_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.
+                */
+               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;
+
+                   pwlen = strlen(password);
+                   if (pwlen < 16) {
+                       bottom = 0;    /* zero length passwords are OK! :-) */
+                       top = 15;
+                   } else {
+                       bottom = pwlen & ~7;
+                       top = bottom + 7;
+                   }
+
+                   assert(pwlen >= bottom && pwlen <= top);
+
+                   randomstr = smalloc(top + 1);
+
+                   for (i = bottom; i <= top; i++) {
+                       if (i == pwlen)
+                           defer_packet(pwpkt_type, PKT_STR, password,
+                                        PKT_END);
+                       else {
+                           for (j = 0; j < i; j++) {
+                               do {
+                                   randomstr[j] = random_byte();
+                               } while (randomstr[j] == '\0');
+                           }
+                           randomstr[i] = '\0';
+                           defer_packet(SSH1_MSG_IGNORE,
+                                        PKT_STR, randomstr, PKT_END);
+                       }
+                   }
+                   logevent("Sending password with camouflage packets");
+                   ssh_pkt_defersend();
+               } 
+               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 *s;
+                   int len;
+
+                   len = strlen(password);
+                   if (len < sizeof(string)) {
+                       s = string;
+                       strcpy(string, password);
+                       len++;         /* cover the zero byte */
+                       while (len < sizeof(string)) {
+                           string[len++] = (char) random_byte();
+                       }
+                   } else {
+                       s = password;
+                   }
+                   logevent("Sending length-padded password");
+                   send_packet(pwpkt_type, PKT_INT, len,
+                               PKT_DATA, s, len, 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(password);
+                   logevent("Sending unpadded password");
+                   send_packet(pwpkt_type, PKT_INT, len,
+                               PKT_DATA, password, len, PKT_END);
+               }
+           } else {
+               send_packet(pwpkt_type, PKT_STR, password, PKT_END);
+           }
+       }
        logevent("Sent password");
        memset(password, 0, strlen(password));
        crWaitUntil(ispkt);
        if (pktin.type == SSH1_SMSG_FAILURE) {
-            if (flags & FLAG_VERBOSE)
-                c_write_str("Access denied\r\n");
+           if (flags & FLAG_VERBOSE)
+               c_write_str("Access denied\r\n");
            logevent("Authentication refused");
        } else if (pktin.type == SSH1_MSG_DISCONNECT) {
            logevent("Received disconnect request");
-            ssh_state = SSH_STATE_CLOSED;
+           ssh_state = SSH_STATE_CLOSED;
            crReturn(1);
        } else if (pktin.type != SSH1_SMSG_SUCCESS) {
            bombout(("Strange packet received, type %d", pktin.type));
-            crReturn(0);
+           crReturn(0);
        }
     }
 
@@ -2099,37 +2518,72 @@ static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
     crFinish(1);
 }
 
-void sshfwd_close(struct ssh_channel *c) {
+void sshfwd_close(struct ssh_channel *c)
+{
     if (c && !c->closes) {
-        if (ssh_version == 1) {
-            send_packet(SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid, PKT_END);
-        } else {
-            ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
-            ssh2_pkt_adduint32(c->remoteid);
-            ssh2_pkt_send();
-        }
-        c->closes = 1;
-        if (c->type == CHAN_X11) {
-            c->u.x11.s = NULL;
-            logevent("X11 connection terminated");
-        }
-    }
-}
-
-void sshfwd_write(struct ssh_channel *c, char *buf, int len) {
+       /*
+        * If the channel's remoteid is -1, we have sent
+        * CHANNEL_OPEN for this channel, but it hasn't even been
+        * acknowledged by the server. So we must set a close flag
+        * on it now, and then when the server acks the channel
+        * open, we can close it then.
+        */
+       if (c->remoteid != -1) {
+           if (ssh_version == 1) {
+               send_packet(SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
+                           PKT_END);
+           } else {
+               ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
+               ssh2_pkt_adduint32(c->remoteid);
+               ssh2_pkt_send();
+           }
+       }
+       c->closes = 1;
+       if (c->type == CHAN_X11) {
+           c->u.x11.s = NULL;
+           logevent("Forwarded X11 connection terminated");
+       } else if (c->type == CHAN_SOCKDATA ||
+                  c->type == CHAN_SOCKDATA_DORMANT) {
+           c->u.pfd.s = NULL;
+           logevent("Forwarded port closed");
+       }
+    }
+}
+
+int sshfwd_write(struct ssh_channel *c, char *buf, int len)
+{
+    if (ssh_version == 1) {
+       send_packet(SSH1_MSG_CHANNEL_DATA,
+                   PKT_INT, c->remoteid,
+                   PKT_INT, len, PKT_DATA, buf, len, PKT_END);
+       /*
+        * In SSH1 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
+        * _everything_ will be throttled as a whole.
+        */
+       return 0;
+    } else {
+       ssh2_add_channel_data(c, buf, len);
+       return ssh2_try_send(c);
+    }
+}
+
+void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
+{
     if (ssh_version == 1) {
-        send_packet(SSH1_MSG_CHANNEL_DATA,
-                    PKT_INT, c->remoteid,
-                    PKT_INT, len,
-                    PKT_DATA, buf, len,
-                    PKT_END);
+       if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) {
+           c->v.v1.throttling = 0;
+           ssh1_throttle(-1);
+       }
     } else {
-        ssh2_add_channel_data(c, buf, len);
-        ssh2_try_send(c);
+       ssh2_set_window(c, OUR_V2_WINSIZE - bufsize);
     }
 }
 
-static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) {
+static void ssh1_protocol(unsigned char *in, int inlen, int ispkt)
+{
     crBegin;
 
     random_init();
@@ -2138,247 +2592,458 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) {
        crReturnV;
     }
     if (ssh_state == SSH_STATE_CLOSED)
-        crReturnV;
+       crReturnV;
 
     if (cfg.agentfwd && agent_exists()) {
-        logevent("Requesting agent forwarding");
-        send_packet(SSH1_CMSG_AGENT_REQUEST_FORWARDING, PKT_END);
-        do { crReturnV; } while (!ispkt);
-        if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) {
-            bombout(("Protocol confusion"));
-            crReturnV;
-        } else if (pktin.type == SSH1_SMSG_FAILURE) {
-            logevent("Agent forwarding refused");
-        } else {
-            logevent("Agent forwarding enabled");
+       logevent("Requesting agent forwarding");
+       send_packet(SSH1_CMSG_AGENT_REQUEST_FORWARDING, PKT_END);
+       do {
+           crReturnV;
+       } while (!ispkt);
+       if (pktin.type != SSH1_SMSG_SUCCESS
+           && pktin.type != SSH1_SMSG_FAILURE) {
+           bombout(("Protocol confusion"));
+           crReturnV;
+       } else if (pktin.type == SSH1_SMSG_FAILURE) {
+           logevent("Agent forwarding refused");
+       } else {
+           logevent("Agent forwarding enabled");
            ssh_agentfwd_enabled = TRUE;
        }
     }
 
     if (cfg.x11_forward) {
-        char proto[20], data[64];
-        logevent("Requesting X11 forwarding");
-        x11_invent_auth(proto, sizeof(proto), data, sizeof(data));
-        if (ssh1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
-            send_packet(SSH1_CMSG_X11_REQUEST_FORWARDING,
-                        PKT_STR, proto, PKT_STR, data,
-                        PKT_INT, 0,
-                        PKT_END);
-        } else {
-            send_packet(SSH1_CMSG_X11_REQUEST_FORWARDING,
-                        PKT_STR, proto, PKT_STR, data,
-                        PKT_END);
-        }
-        do { crReturnV; } while (!ispkt);
-        if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) {
-            bombout(("Protocol confusion"));
-            crReturnV;
-        } else if (pktin.type == SSH1_SMSG_FAILURE) {
-            logevent("X11 forwarding refused");
-        } else {
-            logevent("X11 forwarding enabled");
+       char proto[20], data[64];
+       logevent("Requesting X11 forwarding");
+       x11_invent_auth(proto, sizeof(proto), data, sizeof(data));
+       if (ssh1_local_protoflags & SSH1_PROTOFLAG_SCREEN_NUMBER) {
+           send_packet(SSH1_CMSG_X11_REQUEST_FORWARDING,
+                       PKT_STR, proto, PKT_STR, data,
+                       PKT_INT, 0, PKT_END);
+       } else {
+           send_packet(SSH1_CMSG_X11_REQUEST_FORWARDING,
+                       PKT_STR, proto, PKT_STR, data, PKT_END);
+       }
+       do {
+           crReturnV;
+       } while (!ispkt);
+       if (pktin.type != SSH1_SMSG_SUCCESS
+           && pktin.type != SSH1_SMSG_FAILURE) {
+           bombout(("Protocol confusion"));
+           crReturnV;
+       } else if (pktin.type == SSH1_SMSG_FAILURE) {
+           logevent("X11 forwarding refused");
+       } else {
+           logevent("X11 forwarding enabled");
            ssh_X11_fwd_enabled = TRUE;
        }
     }
 
+    {
+       char type, *e;
+       int n;
+       int sport,dport;
+       char sports[256], dports[256], host[256];
+       char buf[1024];
+
+       ssh_rportfwds = newtree234(ssh_rportcmp_ssh1);
+        /* Add port forwardings. */
+       e = cfg.portfwd;
+       while (*e) {
+           type = *e++;
+           n = 0;
+           while (*e && *e != '\t')
+               sports[n++] = *e++;
+           sports[n] = 0;
+           if (*e == '\t')
+               e++;
+           n = 0;
+           while (*e && *e != ':')
+               host[n++] = *e++;
+           host[n] = 0;
+           if (*e == ':')
+               e++;
+           n = 0;
+           while (*e)
+               dports[n++] = *e++;
+           dports[n] = 0;
+           e++;
+           dport = atoi(dports);
+           sport = atoi(sports);
+           if (sport && dport) {
+               if (type == 'L') {
+                   pfd_addforward(host, dport, sport);
+                   sprintf(buf, "Local port %d forwarding to %s:%d",
+                           sport, host, dport);
+                   logevent(buf);
+               } else {
+                   struct ssh_rportfwd *pf;
+                   pf = smalloc(sizeof(*pf));
+                   strcpy(pf->dhost, host);
+                   pf->dport = dport;
+                   if (add234(ssh_rportfwds, pf) != pf) {
+                       sprintf(buf, 
+                               "Duplicate remote port forwarding to %s:%d",
+                               host, dport);
+                       logevent(buf);
+                       sfree(pf);
+                   } else {
+                       sprintf(buf, "Requesting remote port %d forward to %s:%d",
+                               sport, host, dport);
+                       logevent(buf);
+                       send_packet(SSH1_CMSG_PORT_FORWARD_REQUEST,
+                                   PKT_INT, sport,
+                                   PKT_STR, host,
+                                   PKT_INT, dport,
+                                   PKT_END);
+                   }
+               }
+           }
+       }
+    }
+
     if (!cfg.nopty) {
        send_packet(SSH1_CMSG_REQUEST_PTY,
-                   PKT_STR, cfg.termtype,
-                   PKT_INT, rows, PKT_INT, cols,
-                   PKT_INT, 0, PKT_INT, 0,
-                   PKT_CHAR, 0,
-                   PKT_END);
-        ssh_state = SSH_STATE_INTERMED;
-        do { crReturnV; } while (!ispkt);
-        if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) {
-            bombout(("Protocol confusion"));
-            crReturnV;
-        } else if (pktin.type == SSH1_SMSG_FAILURE) {
-            c_write_str("Server refused to allocate pty\r\n");
-            ssh_editing = ssh_echoing = 1;
-        }
+                   PKT_STR, cfg.termtype,
+                   PKT_INT, rows, PKT_INT, cols,
+                   PKT_INT, 0, PKT_INT, 0, PKT_CHAR, 0, PKT_END);
+       ssh_state = SSH_STATE_INTERMED;
+       do {
+           crReturnV;
+       } while (!ispkt);
+       if (pktin.type != SSH1_SMSG_SUCCESS
+           && pktin.type != SSH1_SMSG_FAILURE) {
+           bombout(("Protocol confusion"));
+           crReturnV;
+       } else if (pktin.type == SSH1_SMSG_FAILURE) {
+           c_write_str("Server refused to allocate pty\r\n");
+           ssh_editing = ssh_echoing = 1;
+       }
        logevent("Allocated pty");
     } else {
-        ssh_editing = ssh_echoing = 1;
+       ssh_editing = ssh_echoing = 1;
     }
 
     if (cfg.compression) {
-        send_packet(SSH1_CMSG_REQUEST_COMPRESSION, PKT_INT, 6, PKT_END);
-        do { crReturnV; } while (!ispkt);
-        if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) {
-            bombout(("Protocol confusion"));
-            crReturnV;
-        } else if (pktin.type == SSH1_SMSG_FAILURE) {
-            c_write_str("Server refused to compress\r\n");
-        }
+       send_packet(SSH1_CMSG_REQUEST_COMPRESSION, PKT_INT, 6, PKT_END);
+       do {
+           crReturnV;
+       } while (!ispkt);
+       if (pktin.type != SSH1_SMSG_SUCCESS
+           && pktin.type != SSH1_SMSG_FAILURE) {
+           bombout(("Protocol confusion"));
+           crReturnV;
+       } else if (pktin.type == SSH1_SMSG_FAILURE) {
+           c_write_str("Server refused to compress\r\n");
+       }
        logevent("Started compression");
        ssh1_compressing = TRUE;
        zlib_compress_init();
        zlib_decompress_init();
     }
 
-    if (*cfg.remote_cmd_ptr)
-        send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cfg.remote_cmd_ptr, PKT_END);
-    else
-        send_packet(SSH1_CMSG_EXEC_SHELL, PKT_END);
-    logevent("Started session");
+    /*
+     * Start the shell or command.
+     * 
+     * Special case: if the first-choice command is an SSH2
+     * subsystem (hence not usable here) and the second choice
+     * exists, we fall straight back to that.
+     */
+    {
+       char *cmd = cfg.remote_cmd_ptr;
+       
+       if (cfg.ssh_subsys && cfg.remote_cmd_ptr2) {
+           cmd = cfg.remote_cmd_ptr2;
+           ssh_fallback_cmd = TRUE;
+       }
+       if (*cmd)
+           send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cmd, PKT_END);
+       else
+           send_packet(SSH1_CMSG_EXEC_SHELL, PKT_END);
+       logevent("Started session");
+    }
 
     ssh_state = SSH_STATE_SESSION;
     if (size_needed)
        ssh_size();
     if (eof_needed)
-        ssh_special(TS_EOF);
+       ssh_special(TS_EOF);
 
-    ldisc_send(NULL, 0);               /* cause ldisc to notice changes */
+    ldisc_send(NULL, 0, 0);           /* cause ldisc to notice changes */
     ssh_send_ok = 1;
     ssh_channels = newtree234(ssh_channelcmp);
     while (1) {
        crReturnV;
        if (ispkt) {
            if (pktin.type == SSH1_SMSG_STDOUT_DATA ||
-                pktin.type == SSH1_SMSG_STDERR_DATA) {
+               pktin.type == SSH1_SMSG_STDERR_DATA) {
                long len = GET_32BIT(pktin.body);
-               from_backend(pktin.type == SSH1_SMSG_STDERR_DATA,
-                            pktin.body+4, len);
+               int bufsize =
+                   from_backend(pktin.type == SSH1_SMSG_STDERR_DATA,
+                                pktin.body + 4, len);
+               if (!ssh1_stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) {
+                   ssh1_stdout_throttling = 1;
+                   ssh1_throttle(+1);
+               }
            } else if (pktin.type == SSH1_MSG_DISCONNECT) {
-                ssh_state = SSH_STATE_CLOSED;
+               ssh_state = SSH_STATE_CLOSED;
                logevent("Received disconnect request");
-                crReturnV;
-            } else if (pktin.type == SSH1_SMSG_X11_OPEN) {
-                /* Remote side is trying to open a channel to talk to our
-                 * X-Server. Give them back a local channel number. */
-                struct ssh_channel *c;
+               crReturnV;
+           } else if (pktin.type == SSH1_SMSG_X11_OPEN) {
+               /* Remote side is trying to open a channel to talk to our
+                * X-Server. Give them back a local channel number. */
+               struct ssh_channel *c;
 
                logevent("Received X11 connect request");
                /* Refuse if X11 forwarding is disabled. */
                if (!ssh_X11_fwd_enabled) {
                    send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE,
-                               PKT_INT, GET_32BIT(pktin.body),
-                               PKT_END);
+                               PKT_INT, GET_32BIT(pktin.body), PKT_END);
                    logevent("Rejected X11 connect request");
                } else {
                    c = smalloc(sizeof(struct ssh_channel));
 
-                   if ( x11_init(&c->u.x11.s, cfg.x11_display, c) != NULL ) {
-                     logevent("opening X11 forward connection failed");
-                     sfree(c);
-                     send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE,
-                                 PKT_INT, GET_32BIT(pktin.body),
-                                 PKT_END);
+                   if (x11_init(&c->u.x11.s, cfg.x11_display, c) != NULL) {
+                       logevent("opening X11 forward connection failed");
+                       sfree(c);
+                       send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE,
+                                   PKT_INT, GET_32BIT(pktin.body),
+                                   PKT_END);
                    } else {
-                     logevent("opening X11 forward connection succeeded");
-                     c->remoteid = GET_32BIT(pktin.body);
-                     c->localid = alloc_channel_id();
-                     c->closes = 0;
-                     c->type = CHAN_X11;   /* identify channel type */
-                     add234(ssh_channels, c);
-                     send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
-                                 PKT_INT, c->remoteid, PKT_INT, c->localid,
-                                 PKT_END);
-                     logevent("Opened X11 forward channel");
+                       logevent
+                           ("opening X11 forward connection succeeded");
+                       c->remoteid = GET_32BIT(pktin.body);
+                       c->localid = alloc_channel_id();
+                       c->closes = 0;
+                       c->v.v1.throttling = 0;
+                       c->type = CHAN_X11;     /* identify channel type */
+                       add234(ssh_channels, c);
+                       send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
+                                   PKT_INT, c->remoteid, PKT_INT,
+                                   c->localid, PKT_END);
+                       logevent("Opened X11 forward channel");
                    }
                }
-            } else if (pktin.type == SSH1_SMSG_AGENT_OPEN) {
-                /* Remote side is trying to open a channel to talk to our
-                 * agent. Give them back a local channel number. */
-                struct ssh_channel *c;
+           } else if (pktin.type == SSH1_SMSG_AGENT_OPEN) {
+               /* Remote side is trying to open a channel to talk to our
+                * agent. Give them back a local channel number. */
+               struct ssh_channel *c;
 
                /* Refuse if agent forwarding is disabled. */
                if (!ssh_agentfwd_enabled) {
                    send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE,
-                               PKT_INT, GET_32BIT(pktin.body),
-                               PKT_END);
+                               PKT_INT, GET_32BIT(pktin.body), PKT_END);
                } else {
                    c = smalloc(sizeof(struct ssh_channel));
                    c->remoteid = GET_32BIT(pktin.body);
                    c->localid = alloc_channel_id();
                    c->closes = 0;
-                   c->type = CHAN_AGENT;   /* identify channel type */
+                   c->v.v1.throttling = 0;
+                   c->type = CHAN_AGENT;       /* identify channel type */
                    c->u.a.lensofar = 0;
                    add234(ssh_channels, c);
                    send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
                                PKT_INT, c->remoteid, PKT_INT, c->localid,
                                PKT_END);
                }
+           } else if (pktin.type == SSH1_MSG_PORT_OPEN) {
+               /* Remote side is trying to open a channel to talk to a
+                * forwarded port. Give them back a local channel number. */
+               struct ssh_channel *c;
+               struct ssh_rportfwd pf;
+               int hostsize, port;
+               char host[256], buf[1024];
+               char *p, *h, *e;
+               c = smalloc(sizeof(struct ssh_channel));
+
+               hostsize = GET_32BIT(pktin.body+4);
+               for(h = host, p = pktin.body+8; hostsize != 0; hostsize--) {
+                   if (h+1 < host+sizeof(host))
+                       *h++ = *p;
+                   p++;
+               }
+               *h = 0;
+               port = GET_32BIT(p);
+
+               strcpy(pf.dhost, host);
+               pf.dport = port;
+
+               if (find234(ssh_rportfwds, &pf, NULL) == NULL) {
+                   sprintf(buf, "Rejected remote port open request for %s:%d",
+                           host, port);
+                   logevent(buf);
+                    send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE,
+                                PKT_INT, GET_32BIT(pktin.body), PKT_END);
+               } else {
+                   sprintf(buf, "Received remote port open request for %s:%d",
+                           host, port);
+                   logevent(buf);
+                   e = pfd_newconnect(&c->u.pfd.s, host, port, c);
+                   if (e != NULL) {
+                       char buf[256];
+                       sprintf(buf, "Port open failed: %s", e);
+                       logevent(buf);
+                       sfree(c);
+                       send_packet(SSH1_MSG_CHANNEL_OPEN_FAILURE,
+                                   PKT_INT, GET_32BIT(pktin.body),
+                                   PKT_END);
+                   } else {
+                       c->remoteid = GET_32BIT(pktin.body);
+                       c->localid = alloc_channel_id();
+                       c->closes = 0;
+                       c->v.v1.throttling = 0;
+                       c->type = CHAN_SOCKDATA;        /* identify channel type */
+                       add234(ssh_channels, c);
+                       send_packet(SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
+                                   PKT_INT, c->remoteid, PKT_INT,
+                                   c->localid, PKT_END);
+                       logevent("Forwarded port opened successfully");
+                   }
+               }
+
+           } else if (pktin.type == SSH1_MSG_CHANNEL_OPEN_CONFIRMATION) {
+               unsigned int remoteid = GET_32BIT(pktin.body);
+               unsigned int localid = GET_32BIT(pktin.body+4);
+               struct ssh_channel *c;
+
+               c = find234(ssh_channels, &remoteid, ssh_channelfind);
+               if (c && c->type == CHAN_SOCKDATA_DORMANT) {
+                   c->remoteid = localid;
+                   c->type = CHAN_SOCKDATA;
+                   c->v.v1.throttling = 0;
+                   pfd_confirm(c->u.pfd.s);
+               }
+
+               if (c && c->closes) {
+                   /*
+                    * We have a pending close on this channel,
+                    * which we decided on before the server acked
+                    * the channel open. So now we know the
+                    * remoteid, we can close it again.
+                    */
+                   send_packet(SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
+                               PKT_END);
+               }
+
+           } else if (pktin.type == SSH1_MSG_CHANNEL_OPEN_FAILURE) {
+               unsigned int remoteid = GET_32BIT(pktin.body);
+               unsigned int localid = GET_32BIT(pktin.body+4);
+               struct ssh_channel *c;
+
+               c = find234(ssh_channels, &remoteid, ssh_channelfind);
+               if (c && c->type == CHAN_SOCKDATA_DORMANT) {
+                   logevent("Forwarded connection refused by server");
+                   pfd_close(c->u.pfd.s);
+                   del234(ssh_channels, c);
+                   sfree(c);
+               }
+
            } else if (pktin.type == SSH1_MSG_CHANNEL_CLOSE ||
                       pktin.type == SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION) {
-                /* Remote side closes a channel. */
-                unsigned i = GET_32BIT(pktin.body);
-                struct ssh_channel *c;
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (c) {
-                    int closetype;
-                    closetype = (pktin.type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2);
-                    if (!(c->closes & closetype))
-                        send_packet(pktin.type, PKT_INT, c->remoteid, PKT_END);
+               /* Remote side closes a channel. */
+               unsigned i = GET_32BIT(pktin.body);
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (c) {
+                   int closetype;
+                   closetype =
+                       (pktin.type == SSH1_MSG_CHANNEL_CLOSE ? 1 : 2);
+                   if (!(c->closes & closetype))
+                       send_packet(pktin.type, PKT_INT, c->remoteid,
+                                   PKT_END);
                    if ((c->closes == 0) && (c->type == CHAN_X11)) {
-                       logevent("X11 connection closed");
+                       logevent("Forwarded X11 connection terminated");
                        assert(c->u.x11.s != NULL);
                        x11_close(c->u.x11.s);
                        c->u.x11.s = NULL;
                    }
-                    c->closes |= closetype;
-                    if (c->closes == 3) {
-                        del234(ssh_channels, c);
-                        sfree(c);
-                    }
-                }
-            } else if (pktin.type == SSH1_MSG_CHANNEL_DATA) {
-                /* Data sent down one of our channels. */
-                int i = GET_32BIT(pktin.body);
-                int len = GET_32BIT(pktin.body+4);
-                unsigned char *p = pktin.body+8;
-                struct ssh_channel *c;
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (c) {
-                    switch(c->type) {
-                      case CHAN_X11:
-                       x11_send(c->u.x11.s, p, len);
+                   if ((c->closes == 0) && (c->type == CHAN_SOCKDATA)) {
+                       logevent("Forwarded port closed");
+                       assert(c->u.pfd.s != NULL);
+                       pfd_close(c->u.pfd.s);
+                       c->u.pfd.s = NULL;
+                   }
+                   c->closes |= closetype;
+                   if (c->closes == 3) {
+                       del234(ssh_channels, c);
+                       sfree(c);
+                   }
+               }
+           } else if (pktin.type == SSH1_MSG_CHANNEL_DATA) {
+               /* Data sent down one of our channels. */
+               int i = GET_32BIT(pktin.body);
+               int len = GET_32BIT(pktin.body + 4);
+               unsigned char *p = pktin.body + 8;
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (c) {
+                   int bufsize;
+                   switch (c->type) {
+                     case CHAN_X11:
+                       bufsize = x11_send(c->u.x11.s, p, len);
+                       break;
+                     case CHAN_SOCKDATA:
+                       bufsize = pfd_send(c->u.pfd.s, p, len);
+                       break;
+                     case CHAN_AGENT:
+                       /* Data for an agent message. Buffer it. */
+                       while (len > 0) {
+                           if (c->u.a.lensofar < 4) {
+                               int l = min(4 - c->u.a.lensofar, len);
+                               memcpy(c->u.a.msglen + c->u.a.lensofar, p,
+                                      l);
+                               p += l;
+                               len -= l;
+                               c->u.a.lensofar += l;
+                           }
+                           if (c->u.a.lensofar == 4) {
+                               c->u.a.totallen =
+                                   4 + GET_32BIT(c->u.a.msglen);
+                               c->u.a.message = smalloc(c->u.a.totallen);
+                               memcpy(c->u.a.message, c->u.a.msglen, 4);
+                           }
+                           if (c->u.a.lensofar >= 4 && len > 0) {
+                               int l =
+                                   min(c->u.a.totallen - c->u.a.lensofar,
+                                       len);
+                               memcpy(c->u.a.message + c->u.a.lensofar, p,
+                                      l);
+                               p += l;
+                               len -= l;
+                               c->u.a.lensofar += l;
+                           }
+                           if (c->u.a.lensofar == c->u.a.totallen) {
+                               void *reply, *sentreply;
+                               int replylen;
+                               agent_query(c->u.a.message,
+                                           c->u.a.totallen, &reply,
+                                           &replylen);
+                               if (reply)
+                                   sentreply = reply;
+                               else {
+                                   /* Fake SSH_AGENT_FAILURE. */
+                                   sentreply = "\0\0\0\1\5";
+                                   replylen = 5;
+                               }
+                               send_packet(SSH1_MSG_CHANNEL_DATA,
+                                           PKT_INT, c->remoteid,
+                                           PKT_INT, replylen,
+                                           PKT_DATA, sentreply, replylen,
+                                           PKT_END);
+                               if (reply)
+                                   sfree(reply);
+                               sfree(c->u.a.message);
+                               c->u.a.lensofar = 0;
+                           }
+                       }
+                       bufsize = 0;   /* agent channels never back up */
                        break;
-                      case CHAN_AGENT:
-                        /* Data for an agent message. Buffer it. */
-                        while (len > 0) {
-                            if (c->u.a.lensofar < 4) {
-                                int l = min(4 - c->u.a.lensofar, len);
-                                memcpy(c->u.a.msglen + c->u.a.lensofar, p, l);
-                                p += l; len -= l; c->u.a.lensofar += l;
-                            }
-                            if (c->u.a.lensofar == 4) {
-                                c->u.a.totallen = 4 + GET_32BIT(c->u.a.msglen);
-                                c->u.a.message = smalloc(c->u.a.totallen);
-                                memcpy(c->u.a.message, c->u.a.msglen, 4);
-                            }
-                            if (c->u.a.lensofar >= 4 && len > 0) {
-                                int l = min(c->u.a.totallen - c->u.a.lensofar, len);
-                                memcpy(c->u.a.message + c->u.a.lensofar, p, l);
-                                p += l; len -= l; c->u.a.lensofar += l;
-                            }
-                            if (c->u.a.lensofar == c->u.a.totallen) {
-                                void *reply, *sentreply;
-                                int replylen;
-                                agent_query(c->u.a.message, c->u.a.totallen,
-                                            &reply, &replylen);
-                                if (reply)
-                                    sentreply = reply;
-                                else {
-                                    /* Fake SSH_AGENT_FAILURE. */
-                                    sentreply = "\0\0\0\1\5";
-                                    replylen = 5;
-                                }
-                                send_packet(SSH1_MSG_CHANNEL_DATA,
-                                            PKT_INT, c->remoteid,
-                                            PKT_INT, replylen,
-                                            PKT_DATA, sentreply, replylen,
-                                            PKT_END);
-                                if (reply)
-                                    sfree(reply);
-                                sfree(c->u.a.message);
-                                c->u.a.lensofar = 0;
-                            }
-                        }
-                        break;
-                    }
-                }                
+                   }
+                   if (!c->v.v1.throttling && bufsize > SSH1_BUFFER_LIMIT) {
+                       c->v.v1.throttling = 1;
+                       ssh1_throttle(+1);
+                   }
+               }
            } else if (pktin.type == SSH1_SMSG_SUCCESS) {
                /* may be from EXEC_SHELL on some servers */
            } else if (pktin.type == SSH1_SMSG_FAILURE) {
@@ -2386,9 +3051,18 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) {
                 * if no pty is available or in other odd cases. Ignore */
            } else if (pktin.type == SSH1_SMSG_EXIT_STATUS) {
                send_packet(SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
+                /*
+                 * In case `helpful' firewalls or proxies tack
+                 * extra human-readable text on the end of the
+                 * session which we might mistake for another
+                 * encrypted packet, we close the session once
+                 * we've sent EXIT_CONFIRMATION.
+                 */
+                ssh_state = SSH_STATE_CLOSED;
+                crReturnV;
            } else {
                bombout(("Strange packet received: type %d", pktin.type));
-                crReturnV;
+               crReturnV;
            }
        } else {
            while (inlen > 0) {
@@ -2407,34 +3081,37 @@ static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) {
 /*
  * Utility routine for decoding comma-separated strings in KEXINIT.
  */
-static int in_commasep_string(char *needle, char *haystack, int haylen) {
+static int in_commasep_string(char *needle, char *haystack, int haylen)
+{
     int needlen = strlen(needle);
     while (1) {
-        /*
-         * Is it at the start of the string?
-         */
-        if (haylen >= needlen &&       /* haystack is long enough */
-            !memcmp(needle, haystack, needlen) &&    /* initial match */
-            (haylen == needlen || haystack[needlen] == ',')
-                                       /* either , or EOS follows */
-            )
-            return 1;
-        /*
-         * If not, search for the next comma and resume after that.
-         * If no comma found, terminate.
-         */
-        while (haylen > 0 && *haystack != ',')
-            haylen--, haystack++;
-        if (haylen == 0)
-            return 0;
-        haylen--, haystack++;          /* skip over comma itself */
+       /*
+        * Is it at the start of the string?
+        */
+       if (haylen >= needlen &&       /* haystack is long enough */
+           !memcmp(needle, haystack, needlen) &&       /* initial match */
+           (haylen == needlen || haystack[needlen] == ',')
+           /* either , or EOS follows */
+           )
+           return 1;
+       /*
+        * If not, search for the next comma and resume after that.
+        * If no comma found, terminate.
+        */
+       while (haylen > 0 && *haystack != ',')
+           haylen--, haystack++;
+       if (haylen == 0)
+           return 0;
+       haylen--, haystack++;          /* skip over comma itself */
     }
 }
 
 /*
  * SSH2 key creation method.
  */
-static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr, char *keyspace) {
+static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr,
+                      char *keyspace)
+{
     SHA_State s;
     /* First 20 bytes. */
     SHA_Init(&s);
@@ -2448,7 +3125,7 @@ static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr, char *keyspace
     sha_mpint(&s, K);
     SHA_Bytes(&s, H, 20);
     SHA_Bytes(&s, keyspace, 20);
-    SHA_Final(&s, keyspace+20);
+    SHA_Final(&s, keyspace + 20);
 }
 
 /*
@@ -2456,7 +3133,7 @@ static void ssh2_mkkey(Bignum K, char *H, char *sessid, char chr, char *keyspace
  */
 static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
 {
-    static int i, j, len, nbits, pbits;
+    static int i, j, len, nbits, pbits, warn;
     static char *str;
     static Bignum p, g, e, f, K;
     static int kex_init_value, kex_reply_value;
@@ -2473,7 +3150,8 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
     static void *hkey;                /* actual host key */
     static unsigned char exchange_hash[20];
     static unsigned char keyspace[40];
-    static const struct ssh2_ciphers *preferred_cipher;
+    static int n_preferred_ciphers;
+    static const struct ssh2_ciphers *preferred_ciphers[CIPHER_MAX];
     static const struct ssh_compress *preferred_comp;
     static int first_kex;
 
@@ -2482,21 +3160,41 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
     first_kex = 1;
 
     /*
-     * Set up the preferred cipher and compression.
+     * Set up the preferred ciphers. (NULL => warn below here)
      */
-    if (cfg.cipher == CIPHER_BLOWFISH) {
-        preferred_cipher = &ssh2_blowfish;
-    } else if (cfg.cipher == CIPHER_DES) {
-        logevent("Single DES not supported in SSH2; using 3DES");
-        preferred_cipher = &ssh2_3des;
-    } else if (cfg.cipher == CIPHER_3DES) {
-        preferred_cipher = &ssh2_3des;
-    } else if (cfg.cipher == CIPHER_AES) {
-        preferred_cipher = &ssh2_aes;
-    } else {
-        /* Shouldn't happen, but we do want to initialise to _something_. */
-        preferred_cipher = &ssh2_3des;
+    n_preferred_ciphers = 0;
+    for (i = 0; i < CIPHER_MAX; i++) {
+       switch (cfg.ssh_cipherlist[i]) {
+         case CIPHER_BLOWFISH:
+           preferred_ciphers[n_preferred_ciphers] = &ssh2_blowfish;
+           n_preferred_ciphers++;
+           break;
+         case CIPHER_DES:
+           preferred_ciphers[n_preferred_ciphers] = &ssh2_des;
+           n_preferred_ciphers++;
+           break;
+         case CIPHER_3DES:
+           preferred_ciphers[n_preferred_ciphers] = &ssh2_3des;
+           n_preferred_ciphers++;
+           break;
+         case CIPHER_AES:
+           preferred_ciphers[n_preferred_ciphers] = &ssh2_aes;
+           n_preferred_ciphers++;
+           break;
+         case CIPHER_WARN:
+           /* Flag for later. Don't bother if it's the last in
+            * the list. */
+           if (i < CIPHER_MAX - 1) {
+               preferred_ciphers[n_preferred_ciphers] = NULL;
+               n_preferred_ciphers++;
+           }
+           break;
+       }
     }
+
+    /*
+     * Set up preferred compression.
+     */
     if (cfg.compression)
        preferred_comp = &ssh_zlib;
     else
@@ -2506,80 +3204,84 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
      * Be prepared to work around the buggy MAC problem.
      */
     if (cfg.buggymac || (ssh_remote_bugs & BUG_SSH2_HMAC))
-        maclist = buggymacs, nmacs = lenof(buggymacs);
+       maclist = buggymacs, nmacs = lenof(buggymacs);
     else
-        maclist = macs, nmacs = lenof(macs);
+       maclist = macs, nmacs = lenof(macs);
 
-    begin_key_exchange:
+  begin_key_exchange:
     /*
      * Construct and send our key exchange packet.
      */
     ssh2_pkt_init(SSH2_MSG_KEXINIT);
     for (i = 0; i < 16; i++)
-        ssh2_pkt_addbyte((unsigned char)random_byte());
+       ssh2_pkt_addbyte((unsigned char) random_byte());
     /* List key exchange algorithms. */
     ssh2_pkt_addstring_start();
     for (i = 0; i < lenof(kex_algs); i++) {
-        ssh2_pkt_addstring_str(kex_algs[i]->name);
-        if (i < lenof(kex_algs)-1)
-            ssh2_pkt_addstring_str(",");
+       ssh2_pkt_addstring_str(kex_algs[i]->name);
+       if (i < lenof(kex_algs) - 1)
+           ssh2_pkt_addstring_str(",");
     }
     /* List server host key algorithms. */
     ssh2_pkt_addstring_start();
     for (i = 0; i < lenof(hostkey_algs); i++) {
-        ssh2_pkt_addstring_str(hostkey_algs[i]->name);
-        if (i < lenof(hostkey_algs)-1)
-            ssh2_pkt_addstring_str(",");
+       ssh2_pkt_addstring_str(hostkey_algs[i]->name);
+       if (i < lenof(hostkey_algs) - 1)
+           ssh2_pkt_addstring_str(",");
     }
     /* List client->server encryption algorithms. */
     ssh2_pkt_addstring_start();
-    for (i = 0; i < lenof(ciphers)+1; i++) {
-        const struct ssh2_ciphers *c = i==0 ? preferred_cipher : ciphers[i-1];
-        for (j = 0; j < c->nciphers; j++) {
-            ssh2_pkt_addstring_str(c->list[j]->name);
-            if (i < lenof(ciphers) || j < c->nciphers-1)
-                ssh2_pkt_addstring_str(",");
-        }
+    for (i = 0; i < n_preferred_ciphers; i++) {
+       const struct ssh2_ciphers *c = preferred_ciphers[i];
+       if (!c) continue;              /* warning flag */
+       for (j = 0; j < c->nciphers; j++) {
+           ssh2_pkt_addstring_str(c->list[j]->name);
+           if (i < n_preferred_ciphers || j < c->nciphers - 1)
+               ssh2_pkt_addstring_str(",");
+       }
     }
     /* List server->client encryption algorithms. */
     ssh2_pkt_addstring_start();
-    for (i = 0; i < lenof(ciphers)+1; i++) {
-        const struct ssh2_ciphers *c = i==0 ? preferred_cipher : ciphers[i-1];
-        for (j = 0; j < c->nciphers; j++) {
-            ssh2_pkt_addstring_str(c->list[j]->name);
-            if (i < lenof(ciphers) || j < c->nciphers-1)
-                ssh2_pkt_addstring_str(",");
-        }
+    for (i = 0; i < n_preferred_ciphers; i++) {
+       const struct ssh2_ciphers *c = preferred_ciphers[i];
+       if (!c) continue; /* warning flag */
+       for (j = 0; j < c->nciphers; j++) {
+           ssh2_pkt_addstring_str(c->list[j]->name);
+           if (i < n_preferred_ciphers || j < c->nciphers - 1)
+               ssh2_pkt_addstring_str(",");
+       }
     }
     /* List client->server MAC algorithms. */
     ssh2_pkt_addstring_start();
     for (i = 0; i < nmacs; i++) {
-        ssh2_pkt_addstring_str(maclist[i]->name);
-        if (i < nmacs-1)
-            ssh2_pkt_addstring_str(",");
+       ssh2_pkt_addstring_str(maclist[i]->name);
+       if (i < nmacs - 1)
+           ssh2_pkt_addstring_str(",");
     }
     /* List server->client MAC algorithms. */
     ssh2_pkt_addstring_start();
     for (i = 0; i < nmacs; i++) {
-        ssh2_pkt_addstring_str(maclist[i]->name);
-        if (i < nmacs-1)
-            ssh2_pkt_addstring_str(",");
+       ssh2_pkt_addstring_str(maclist[i]->name);
+       if (i < nmacs - 1)
+           ssh2_pkt_addstring_str(",");
     }
     /* List client->server compression algorithms. */
     ssh2_pkt_addstring_start();
-    for (i = 0; i < lenof(compressions)+1; i++) {
-        const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1];
-        ssh2_pkt_addstring_str(c->name);
-        if (i < lenof(compressions))
-            ssh2_pkt_addstring_str(",");
+    for (i = 0; i < lenof(compressions) + 1; i++) {
+       const struct ssh_compress *c =
+           i == 0 ? preferred_comp : compressions[i - 1];
+       ssh2_pkt_addstring_str(c->name);
+       if (i < lenof(compressions))
+           ssh2_pkt_addstring_str(",");
     }
     /* List server->client compression algorithms. */
     ssh2_pkt_addstring_start();
-    for (i = 0; i < lenof(compressions)+1; i++) {
-        const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1];
-        ssh2_pkt_addstring_str(c->name);
-        if (i < lenof(compressions))
-            ssh2_pkt_addstring_str(",");
+    for (i = 0; i < lenof(compressions) + 1; i++) {
+       const struct ssh_compress *c =
+           i == 0 ? preferred_comp : compressions[i - 1];
+       ssh2_pkt_addstring_str(c->name);
+       if (i < lenof(compressions))
+           ssh2_pkt_addstring_str(",");
     }
     /* List client->server languages. Empty list. */
     ssh2_pkt_addstring_start();
@@ -2591,91 +3293,126 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
     ssh2_pkt_adduint32(0);
 
     exhash = exhashbase;
-    sha_string(&exhash, pktout.data+5, pktout.length-5);
+    sha_string(&exhash, pktout.data + 5, pktout.length - 5);
 
     ssh2_pkt_send();
 
-    if (!ispkt) crWaitUntil(ispkt);
-    sha_string(&exhash, pktin.data+5, pktin.length-5);
+    if (!ispkt)
+       crWaitUntil(ispkt);
+    sha_string(&exhash, pktin.data + 5, pktin.length - 5);
 
     /*
      * Now examine the other side's KEXINIT to see what we're up
      * to.
      */
     if (pktin.type != SSH2_MSG_KEXINIT) {
-        bombout(("expected key exchange packet from server"));
-        crReturn(0);
+       bombout(("expected key exchange packet from server"));
+       crReturn(0);
     }
-    kex = NULL; hostkey = NULL; cscipher_tobe = NULL; sccipher_tobe = NULL;
-    csmac_tobe = NULL; scmac_tobe = NULL; cscomp_tobe = NULL; sccomp_tobe = NULL;
-    pktin.savedpos += 16;              /* skip garbage cookie */
+    kex = NULL;
+    hostkey = NULL;
+    cscipher_tobe = NULL;
+    sccipher_tobe = NULL;
+    csmac_tobe = NULL;
+    scmac_tobe = NULL;
+    cscomp_tobe = NULL;
+    sccomp_tobe = NULL;
+    pktin.savedpos += 16;             /* skip garbage cookie */
     ssh2_pkt_getstring(&str, &len);    /* key exchange algorithms */
     for (i = 0; i < lenof(kex_algs); i++) {
-        if (in_commasep_string(kex_algs[i]->name, str, len)) {
-            kex = kex_algs[i];
-            break;
-        }
+       if (in_commasep_string(kex_algs[i]->name, str, len)) {
+           kex = kex_algs[i];
+           break;
+       }
     }
     ssh2_pkt_getstring(&str, &len);    /* host key algorithms */
     for (i = 0; i < lenof(hostkey_algs); i++) {
-        if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
-            hostkey = hostkey_algs[i];
-            break;
-        }
+       if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
+           hostkey = hostkey_algs[i];
+           break;
+       }
     }
     ssh2_pkt_getstring(&str, &len);    /* client->server cipher */
-    for (i = 0; i < lenof(ciphers)+1; i++) {
-        const struct ssh2_ciphers *c = i==0 ? preferred_cipher : ciphers[i-1];
-        for (j = 0; j < c->nciphers; j++) {
-            if (in_commasep_string(c->list[j]->name, str, len)) {
-                cscipher_tobe = c->list[j];
-                break;
-            }
-        }
-        if (cscipher_tobe)
-            break;
+    warn = 0;
+    for (i = 0; i < n_preferred_ciphers; i++) {
+       const struct ssh2_ciphers *c = preferred_ciphers[i];
+       if (!c) {
+           warn = 1;
+       } else {
+           for (j = 0; j < c->nciphers; j++) {
+               if (in_commasep_string(c->list[j]->name, str, len)) {
+                   cscipher_tobe = c->list[j];
+                   break;
+               }
+           }
+       }
+       if (cscipher_tobe) {
+           if (warn)
+               askcipher(cscipher_tobe->name, 1);
+           break;
+       }
+    }
+    if (!cscipher_tobe) {
+       bombout(("Couldn't agree a client-to-server cipher (available: %s)", str));
+       crReturn(0);
     }
+
     ssh2_pkt_getstring(&str, &len);    /* server->client cipher */
-    for (i = 0; i < lenof(ciphers)+1; i++) {
-        const struct ssh2_ciphers *c = i==0 ? preferred_cipher : ciphers[i-1];
-        for (j = 0; j < c->nciphers; j++) {
-            if (in_commasep_string(c->list[j]->name, str, len)) {
-                sccipher_tobe = c->list[j];
-                break;
-            }
-        }
-        if (sccipher_tobe)
-            break;
+    warn = 0;
+    for (i = 0; i < n_preferred_ciphers; i++) {
+       const struct ssh2_ciphers *c = preferred_ciphers[i];
+       if (!c) {
+           warn = 1;
+       } else {
+           for (j = 0; j < c->nciphers; j++) {
+               if (in_commasep_string(c->list[j]->name, str, len)) {
+                   sccipher_tobe = c->list[j];
+                   break;
+               }
+           }
+       }
+       if (sccipher_tobe) {
+           if (warn)
+               askcipher(sccipher_tobe->name, 2);
+           break;
+       }
+    }
+    if (!sccipher_tobe) {
+       bombout(("Couldn't agree a server-to-client cipher (available: %s)", str));
+       crReturn(0);
     }
+
     ssh2_pkt_getstring(&str, &len);    /* client->server mac */
     for (i = 0; i < nmacs; i++) {
-        if (in_commasep_string(maclist[i]->name, str, len)) {
-            csmac_tobe = maclist[i];
-            break;
-        }
+       if (in_commasep_string(maclist[i]->name, str, len)) {
+           csmac_tobe = maclist[i];
+           break;
+       }
     }
     ssh2_pkt_getstring(&str, &len);    /* server->client mac */
     for (i = 0; i < nmacs; i++) {
-        if (in_commasep_string(maclist[i]->name, str, len)) {
-            scmac_tobe = maclist[i];
-            break;
-        }
+       if (in_commasep_string(maclist[i]->name, str, len)) {
+           scmac_tobe = maclist[i];
+           break;
+       }
     }
     ssh2_pkt_getstring(&str, &len);    /* client->server compression */
-    for (i = 0; i < lenof(compressions)+1; i++) {
-        const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1];
-        if (in_commasep_string(c->name, str, len)) {
-            cscomp_tobe = c;
-            break;
-        }
+    for (i = 0; i < lenof(compressions) + 1; i++) {
+       const struct ssh_compress *c =
+           i == 0 ? preferred_comp : compressions[i - 1];
+       if (in_commasep_string(c->name, str, len)) {
+           cscomp_tobe = c;
+           break;
+       }
     }
     ssh2_pkt_getstring(&str, &len);    /* server->client compression */
-    for (i = 0; i < lenof(compressions)+1; i++) {
-        const struct ssh_compress *c = i==0 ? preferred_comp : compressions[i-1];
-        if (in_commasep_string(c->name, str, len)) {
-            sccomp_tobe = c;
-            break;
-        }
+    for (i = 0; i < lenof(compressions) + 1; i++) {
+       const struct ssh_compress *c =
+           i == 0 ? preferred_comp : compressions[i - 1];
+       if (in_commasep_string(c->name, str, len)) {
+           sccomp_tobe = c;
+           break;
+       }
     }
 
     /*
@@ -2684,7 +3421,7 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
      * cipher...
      */
     {
-        int csbits, scbits;
+       int csbits, scbits;
 
        csbits = cscipher_tobe->keylen;
        scbits = sccipher_tobe->keylen;
@@ -2692,52 +3429,53 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
     }
     /* 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 (nbits > 160) nbits = 160;
+    if (nbits > 160)
+       nbits = 160;
 
     /*
      * If we're doing Diffie-Hellman group exchange, start by
      * requesting a group.
      */
     if (kex == &ssh_diffiehellman_gex) {
-        logevent("Doing Diffie-Hellman group exchange");
-        /*
-         * Work out how big a DH group we will need to allow that
-         * much data.
+       logevent("Doing Diffie-Hellman group exchange");
+       /*
+        * Work out how big a DH group we will need to allow that
+        * much data.
         */
-        pbits = 512 << ((nbits-1) / 64);
-        ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST);
-        ssh2_pkt_adduint32(pbits);
-        ssh2_pkt_send();
-
-        crWaitUntil(ispkt);
-        if (pktin.type != SSH2_MSG_KEX_DH_GEX_GROUP) {
-            bombout(("expected key exchange group packet from server"));
-            crReturn(0);
-        }
-        p = ssh2_pkt_getmp();
-        g = ssh2_pkt_getmp();
-        dh_setup_group(p, g);
-        kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
-        kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
+       pbits = 512 << ((nbits - 1) / 64);
+       ssh2_pkt_init(SSH2_MSG_KEX_DH_GEX_REQUEST);
+       ssh2_pkt_adduint32(pbits);
+       ssh2_pkt_send();
+
+       crWaitUntil(ispkt);
+       if (pktin.type != SSH2_MSG_KEX_DH_GEX_GROUP) {
+           bombout(("expected key exchange group packet from server"));
+           crReturn(0);
+       }
+       p = ssh2_pkt_getmp();
+       g = ssh2_pkt_getmp();
+       dh_setup_group(p, g);
+       kex_init_value = SSH2_MSG_KEX_DH_GEX_INIT;
+       kex_reply_value = SSH2_MSG_KEX_DH_GEX_REPLY;
     } else {
-        dh_setup_group1();
-        kex_init_value = SSH2_MSG_KEXDH_INIT;
-        kex_reply_value = SSH2_MSG_KEXDH_REPLY;
+       dh_setup_group1();
+       kex_init_value = SSH2_MSG_KEXDH_INIT;
+       kex_reply_value = SSH2_MSG_KEXDH_REPLY;
     }
 
     logevent("Doing Diffie-Hellman key exchange");
     /*
      * Now generate and send e for Diffie-Hellman.
      */
-    e = dh_create_e(nbits*2);
+    e = dh_create_e(nbits * 2);
     ssh2_pkt_init(kex_init_value);
     ssh2_pkt_addmp(e);
     ssh2_pkt_send();
 
     crWaitUntil(ispkt);
     if (pktin.type != kex_reply_value) {
-        bombout(("expected key exchange reply packet from server"));
-        crReturn(0);
+       bombout(("expected key exchange reply packet from server"));
+       crReturn(0);
     }
     ssh2_pkt_getstring(&hostkeydata, &hostkeylen);
     f = ssh2_pkt_getmp();
@@ -2747,9 +3485,9 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
 
     sha_string(&exhash, hostkeydata, hostkeylen);
     if (kex == &ssh_diffiehellman_gex) {
-        sha_uint32(&exhash, pbits);
-        sha_mpint(&exhash, p);
-        sha_mpint(&exhash, g);
+       sha_uint32(&exhash, pbits);
+       sha_mpint(&exhash, p);
+       sha_mpint(&exhash, g);
     }
     sha_mpint(&exhash, e);
     sha_mpint(&exhash, f);
@@ -2764,18 +3502,10 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
 #endif
 
     hkey = hostkey->newkey(hostkeydata, hostkeylen);
-    if (!hostkey->verifysig(hkey, sigdata, siglen, exchange_hash, 20)) {
-        bombout(("Server failed host key check"));
-        crReturn(0);
-    }
-
-    /*
-     * Expect SSH2_MSG_NEWKEYS from server.
-     */
-    crWaitUntil(ispkt);
-    if (pktin.type != SSH2_MSG_NEWKEYS) {
-        bombout(("expected new-keys packet from server"));
-        crReturn(0);
+    if (!hkey ||
+       !hostkey->verifysig(hkey, sigdata, siglen, exchange_hash, 20)) {
+       bombout(("Server's host key did not match the signature supplied"));
+       crReturn(0);
     }
 
     /*
@@ -2785,8 +3515,8 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
     keystr = hostkey->fmtkey(hkey);
     fingerprint = hostkey->fingerprint(hkey);
     verify_ssh_host_key(savedhost, savedport, hostkey->keytype,
-                        keystr, fingerprint);
-    if (first_kex) {                /* don't bother logging this in rekeys */
+                       keystr, fingerprint);
+    if (first_kex) {                  /* don't bother logging this in rekeys */
        logevent("Host key fingerprint is:");
        logevent(fingerprint);
     }
@@ -2801,6 +3531,15 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
     ssh2_pkt_send();
 
     /*
+     * Expect SSH2_MSG_NEWKEYS from server.
+     */
+    crWaitUntil(ispkt);
+    if (pktin.type != SSH2_MSG_NEWKEYS) {
+       bombout(("expected new-keys packet from server"));
+       crReturn(0);
+    }
+
+    /*
      * Create and initialise session keys.
      */
     cscipher = cscipher_tobe;
@@ -2839,7 +3578,7 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
      * it would only confuse the layer above.
      */
     if (!first_kex) {
-        crReturn(0);
+       crReturn(0);
     }
     first_kex = 0;
 
@@ -2850,7 +3589,7 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
      * start.
      */
     while (!(ispkt && pktin.type == SSH2_MSG_KEXINIT)) {
-        crReturn(1);
+       crReturn(1);
     }
     logevent("Server initiated key re-exchange");
     goto begin_key_exchange;
@@ -2861,39 +3600,52 @@ static int do_ssh2_transport(unsigned char *in, int inlen, int ispkt)
 /*
  * Add data to an SSH2 channel output buffer.
  */
-static void ssh2_add_channel_data(struct ssh_channel *c, char *buf, int len) {
-    if (c->v2.outbufsize <
-        c->v2.outbuflen + len) {
-        c->v2.outbufsize =
-            c->v2.outbuflen + len + 1024;
-        c->v2.outbuffer = srealloc(c->v2.outbuffer,
-                                   c->v2.outbufsize);
-    }
-    memcpy(c->v2.outbuffer + c->v2.outbuflen,
-           buf, len);
-    c->v2.outbuflen += len;
+static void ssh2_add_channel_data(struct ssh_channel *c, char *buf,
+                                 int len)
+{
+    bufchain_add(&c->v.v2.outbuffer, buf, len);
 }
 
 /*
  * Attempt to send data on an SSH2 channel.
  */
-static void ssh2_try_send(struct ssh_channel *c) {
-    while (c->v2.remwindow > 0 &&
-           c->v2.outbuflen > 0) {
-        unsigned len = c->v2.remwindow;
-        if (len > c->v2.outbuflen)
-            len = c->v2.outbuflen;
-        if (len > c->v2.remmaxpkt)
-            len = c->v2.remmaxpkt;
-        ssh2_pkt_init(SSH2_MSG_CHANNEL_DATA);
-        ssh2_pkt_adduint32(c->remoteid);
-        ssh2_pkt_addstring_start();
-        ssh2_pkt_addstring_data(c->v2.outbuffer, len);
-        ssh2_pkt_send();
-        c->v2.outbuflen -= len;
-        memmove(c->v2.outbuffer, c->v2.outbuffer+len,
-                c->v2.outbuflen);
-        c->v2.remwindow -= len;
+static int ssh2_try_send(struct ssh_channel *c)
+{
+    while (c->v.v2.remwindow > 0 && bufchain_size(&c->v.v2.outbuffer) > 0) {
+       int len;
+       void *data;
+       bufchain_prefix(&c->v.v2.outbuffer, &data, &len);
+       if ((unsigned)len > c->v.v2.remwindow)
+           len = c->v.v2.remwindow;
+       if ((unsigned)len > c->v.v2.remmaxpkt)
+           len = c->v.v2.remmaxpkt;
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_DATA);
+       ssh2_pkt_adduint32(c->remoteid);
+       ssh2_pkt_addstring_start();
+       ssh2_pkt_addstring_data(data, len);
+       ssh2_pkt_send();
+       bufchain_consume(&c->v.v2.outbuffer, len);
+       c->v.v2.remwindow -= len;
+    }
+
+    /*
+     * After having sent as much data as we can, return the amount
+     * still buffered.
+     */
+    return bufchain_size(&c->v.v2.outbuffer);
+}
+
+/*
+ * Potentially enlarge the window on an SSH2 channel.
+ */
+static void ssh2_set_window(struct ssh_channel *c, unsigned newwin)
+{
+    if (newwin > c->v.v2.locwindow) {
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+       ssh2_pkt_adduint32(c->remoteid);
+       ssh2_pkt_adduint32(newwin - c->v.v2.locwindow);
+       ssh2_pkt_send();
+       c->v.v2.locwindow = newwin;
     }
 }
 
@@ -2902,21 +3654,25 @@ static void ssh2_try_send(struct ssh_channel *c) {
  */
 static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
 {
-    static unsigned long remote_winsize;
-    static unsigned long remote_maxpkt;
     static enum {
-       AUTH_INVALID, AUTH_PUBLICKEY_AGENT, AUTH_PUBLICKEY_FILE, AUTH_PASSWORD
+       AUTH_INVALID, AUTH_PUBLICKEY_AGENT, AUTH_PUBLICKEY_FILE,
+       AUTH_PASSWORD,
+        AUTH_KEYBOARD_INTERACTIVE
     } method;
     static enum {
-        AUTH_TYPE_NONE,
-        AUTH_TYPE_PUBLICKEY,
-        AUTH_TYPE_PUBLICKEY_OFFER_LOUD,
-        AUTH_TYPE_PUBLICKEY_OFFER_QUIET,
-        AUTH_TYPE_PASSWORD
+       AUTH_TYPE_NONE,
+       AUTH_TYPE_PUBLICKEY,
+       AUTH_TYPE_PUBLICKEY_OFFER_LOUD,
+       AUTH_TYPE_PUBLICKEY_OFFER_QUIET,
+       AUTH_TYPE_PASSWORD,
+       AUTH_TYPE_KEYBOARD_INTERACTIVE,
+       AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET
     } type;
-    static int gotit, need_pw, can_pubkey, can_passwd;
-    static int tried_pubkey_config, tried_agent;
+    static int gotit, need_pw, can_pubkey, can_passwd, can_keyb_inter;
+    static int tried_pubkey_config, tried_agent, tried_keyb_inter;
+    static int kbd_inter_running;
     static int we_are_in;
+    static int num_prompts, echo;
     static char username[100];
     static char pwprompt[200];
     static char password[100];
@@ -2931,8 +3687,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
     ssh2_pkt_send();
     crWaitUntilV(ispkt);
     if (pktin.type != SSH2_MSG_SERVICE_ACCEPT) {
-        bombout(("Server refused user authentication protocol"));
-        crReturnV;
+       bombout(("Server refused user authentication protocol"));
+       crReturnV;
     }
 
     /*
@@ -2968,53 +3724,59 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
         */
        pos = 0;
        if ((flags & FLAG_INTERACTIVE) && !*cfg.username) {
-            if (ssh_get_line) {
-                if (!ssh_get_line("login as: ",
-                                  username, sizeof(username), FALSE)) {
-                    /*
-                     * get_line failed to get a username.
-                     * Terminate.
-                     */
-                    logevent("No username provided. Abandoning session.");
-                    ssh_state = SSH_STATE_CLOSED;
-                    crReturnV;
-                }
-            } else {
-                c_write_str("login as: ");
-                ssh_send_ok = 1;
-                while (pos >= 0) {
-                    crWaitUntilV(!ispkt);
-                    while (inlen--) switch (c = *in++) {
-                      case 10: case 13:
-                        username[pos] = 0;
-                        pos = -1;
-                        break;
-                      case 8: case 127:
-                        if (pos > 0) {
-                            c_write_str("\b \b");
-                            pos--;
-                        }
-                        break;
-                      case 21: case 27:
-                        while (pos > 0) {
-                            c_write_str("\b \b");
-                            pos--;
-                        }
-                        break;
-                      case 3: case 4:
-                        random_save_seed();
-                        exit(0);
-                        break;
-                      default:
-                        if (((c >= ' ' && c <= '~') ||
-                             ((unsigned char)c >= 160)) && pos < 40) {
-                            username[pos++] = c;
-                            c_write(&c, 1);
-                        }
-                        break;
-                    }
-                }
-            }
+           if (ssh_get_line) {
+               if (!ssh_get_line("login as: ",
+                                 username, sizeof(username), FALSE)) {
+                   /*
+                    * get_line failed to get a username.
+                    * Terminate.
+                    */
+                   logevent("No username provided. Abandoning session.");
+                   ssh_state = SSH_STATE_CLOSED;
+                   crReturnV;
+               }
+           } else {
+               c_write_str("login as: ");
+               ssh_send_ok = 1;
+               while (pos >= 0) {
+                   crWaitUntilV(!ispkt);
+                   while (inlen--)
+                       switch (c = *in++) {
+                         case 10:
+                         case 13:
+                           username[pos] = 0;
+                           pos = -1;
+                           break;
+                         case 8:
+                         case 127:
+                           if (pos > 0) {
+                               c_write_str("\b \b");
+                               pos--;
+                           }
+                           break;
+                         case 21:
+                         case 27:
+                           while (pos > 0) {
+                               c_write_str("\b \b");
+                               pos--;
+                           }
+                           break;
+                         case 3:
+                         case 4:
+                           random_save_seed();
+                           exit(0);
+                           break;
+                         default:
+                           if (((c >= ' ' && c <= '~') ||
+                                ((unsigned char) c >= 160))
+                               && pos < sizeof(username)-1) {
+                               username[pos++] = c;
+                               c_write(&c, 1);
+                           }
+                           break;
+                       }
+               }
+           }
            c_write_str("\r\n");
            username[strcspn(username, "\n\r")] = '\0';
        } else {
@@ -3034,7 +3796,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
         */
        ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
        ssh2_pkt_addstring(username);
-       ssh2_pkt_addstring("ssh-connection");   /* service requested */
+       ssh2_pkt_addstring("ssh-connection");   /* service requested */
        ssh2_pkt_addstring("none");    /* method */
        ssh2_pkt_send();
        type = AUTH_TYPE_NONE;
@@ -3043,6 +3805,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
 
        tried_pubkey_config = FALSE;
        tried_agent = FALSE;
+       tried_keyb_inter = FALSE;
+       kbd_inter_running = FALSE;
 
        while (1) {
            /*
@@ -3051,21 +3815,21 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
            if (!gotit)
                crWaitUntilV(ispkt);
            while (pktin.type == SSH2_MSG_USERAUTH_BANNER) {
-                char *banner;
-                int size;
-                /*
-                 * Don't show the banner if we're operating in
-                 * non-verbose non-interactive mode. (It's probably
-                 * a script, which means nobody will read the
-                 * banner _anyway_, and moreover the printing of
-                 * the banner will screw up processing on the
-                 * output of (say) plink.)
-                 */
-                if (flags & (FLAG_VERBOSE | FLAG_INTERACTIVE)) {
-                    ssh2_pkt_getstring(&banner, &size);
-                    if (banner)
-                        c_write_untrusted(banner, size);
-                }
+               char *banner;
+               int size;
+               /*
+                * Don't show the banner if we're operating in
+                * non-verbose non-interactive mode. (It's probably
+                * a script, which means nobody will read the
+                * banner _anyway_, and moreover the printing of
+                * the banner will screw up processing on the
+                * output of (say) plink.)
+                */
+               if (flags & (FLAG_VERBOSE | FLAG_INTERACTIVE)) {
+                   ssh2_pkt_getstring(&banner, &size);
+                   if (banner)
+                       c_write_untrusted(banner, size);
+               }
                crWaitUntilV(ispkt);
            }
            if (pktin.type == SSH2_MSG_USERAUTH_SUCCESS) {
@@ -3074,7 +3838,13 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                break;
            }
 
-           if (pktin.type != SSH2_MSG_USERAUTH_FAILURE) {
+           if (kbd_inter_running &&
+               pktin.type == SSH2_MSG_USERAUTH_INFO_REQUEST) {
+               /*
+                * This is a further prompt in keyboard-interactive
+                * authentication. Do nothing.
+                */
+           } else if (pktin.type != SSH2_MSG_USERAUTH_FAILURE) {
                bombout(("Strange packet received during authentication: type %d",
                         pktin.type));
                crReturnV;
@@ -3087,10 +3857,11 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
             * we can look at the string in it and know what we can
             * helpfully try next.
             */
-           {
+           if (pktin.type == SSH2_MSG_USERAUTH_FAILURE) {
                char *methods;
                int methlen;
                ssh2_pkt_getstring(&methods, &methlen);
+               kbd_inter_running = FALSE;
                if (!ssh2_pkt_getbool()) {
                    /*
                     * We have received an unequivocal Access
@@ -3120,6 +3891,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                        if (type == AUTH_TYPE_PUBLICKEY_OFFER_LOUD)
                            c_write_str("Server refused our key\r\n");
                        logevent("Server refused public key");
+                   } else if (type == AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET) {
+                       /* server declined keyboard-interactive; ignore */
                    } else {
                        c_write_str("Access denied\r\n");
                        logevent("Access denied");
@@ -3133,8 +3906,12 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    logevent("Further authentication required");
                }
 
-               can_pubkey = in_commasep_string("publickey", methods, methlen);
-               can_passwd = in_commasep_string("password", methods, methlen);
+               can_pubkey =
+                   in_commasep_string("publickey", methods, methlen);
+               can_passwd =
+                   in_commasep_string("password", methods, methlen);
+               can_keyb_inter = cfg.try_ki_auth &&
+                   in_commasep_string("keyboard-interactive", methods, methlen);
            }
 
            method = 0;
@@ -3157,32 +3934,44 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                PUT_32BIT(request, 1);
                request[4] = SSH2_AGENTC_REQUEST_IDENTITIES;
                agent_query(request, 5, &r, &responselen);
-               response = (unsigned char *)r;
+               response = (unsigned char *) r;
                if (response && responselen >= 5 &&
-                    response[4] == SSH2_AGENT_IDENTITIES_ANSWER) {
+                   response[4] == SSH2_AGENT_IDENTITIES_ANSWER) {
                    p = response + 5;
-                   nkeys = GET_32BIT(p); p += 4;
-                   { char buf[64]; sprintf(buf, "Pageant has %d SSH2 keys", nkeys);
-                       logevent(buf); }
+                   nkeys = GET_32BIT(p);
+                   p += 4;
+                   {
+                       char buf[64];
+                       sprintf(buf, "Pageant has %d SSH2 keys", nkeys);
+                       logevent(buf);
+                   }
                    for (i = 0; i < nkeys; i++) {
                        static char *pkblob, *alg, *commentp;
                        static int pklen, alglen, commentlen;
                        static int siglen, retlen, len;
                        static char *q, *agentreq, *ret;
+                       void *vret;
 
-                       { char buf[64]; sprintf(buf, "Trying Pageant key #%d", i);
-                           logevent(buf); }
-                       pklen = GET_32BIT(p); p += 4;
-                       pkblob = p; p += pklen;
+                       {
+                           char buf[64];
+                           sprintf(buf, "Trying Pageant key #%d", i);
+                           logevent(buf);
+                       }
+                       pklen = GET_32BIT(p);
+                       p += 4;
+                       pkblob = p;
+                       p += pklen;
                        alglen = GET_32BIT(pkblob);
                        alg = pkblob + 4;
-                       commentlen = GET_32BIT(p); p += 4;
-                       commentp = p; p += commentlen;
+                       commentlen = GET_32BIT(p);
+                       p += 4;
+                       commentp = p;
+                       p += commentlen;
                        ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
                        ssh2_pkt_addstring(username);
-                       ssh2_pkt_addstring("ssh-connection");/* service requested */
-                       ssh2_pkt_addstring("publickey");/* method */
-                       ssh2_pkt_addbool(FALSE);   /* no signature included */
+                       ssh2_pkt_addstring("ssh-connection");   /* service requested */
+                       ssh2_pkt_addstring("publickey");        /* method */
+                       ssh2_pkt_addbool(FALSE);        /* no signature included */
                        ssh2_pkt_addstring_start();
                        ssh2_pkt_addstring_data(alg, alglen);
                        ssh2_pkt_addstring_start();
@@ -3195,11 +3984,12 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                            continue;
                        }
 
-                        if (flags & FLAG_VERBOSE) {
-                            c_write_str("Authenticating with public key \"");
-                            c_write(commentp, commentlen);
-                            c_write_str("\" from agent\r\n");
-                        }
+                       if (flags & FLAG_VERBOSE) {
+                           c_write_str
+                               ("Authenticating with public key \"");
+                           c_write(commentp, commentlen);
+                           c_write_str("\" from agent\r\n");
+                       }
 
                        /*
                         * Server is willing to accept the key.
@@ -3207,8 +3997,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                         */
                        ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
                        ssh2_pkt_addstring(username);
-                       ssh2_pkt_addstring("ssh-connection");   /* service requested */
-                       ssh2_pkt_addstring("publickey");    /* method */
+                       ssh2_pkt_addstring("ssh-connection");   /* service requested */
+                       ssh2_pkt_addstring("publickey");        /* method */
                        ssh2_pkt_addbool(TRUE);
                        ssh2_pkt_addstring_start();
                        ssh2_pkt_addstring_data(alg, alglen);
@@ -3216,36 +4006,45 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                        ssh2_pkt_addstring_data(pkblob, pklen);
 
                        siglen = pktout.length - 5 + 4 + 20;
-                       len = 1;   /* message type */
-                       len += 4 + pklen;   /* key blob */
-                       len += 4 + siglen;   /* data to sign */
-                       len += 4;  /* flags */
+                       len = 1;       /* message type */
+                       len += 4 + pklen;       /* key blob */
+                       len += 4 + siglen;      /* data to sign */
+                       len += 4;      /* flags */
                        agentreq = smalloc(4 + len);
                        PUT_32BIT(agentreq, len);
                        q = agentreq + 4;
                        *q++ = SSH2_AGENTC_SIGN_REQUEST;
-                       PUT_32BIT(q, pklen); q += 4;
-                       memcpy(q, pkblob, pklen); q += pklen;
-                       PUT_32BIT(q, siglen); q += 4;
+                       PUT_32BIT(q, pklen);
+                       q += 4;
+                       memcpy(q, pkblob, pklen);
+                       q += pklen;
+                       PUT_32BIT(q, siglen);
+                       q += 4;
                        /* Now the data to be signed... */
-                       PUT_32BIT(q, 20); q += 4;
-                       memcpy(q, ssh2_session_id, 20); q += 20;
-                       memcpy(q, pktout.data+5, pktout.length-5);
-                       q += pktout.length-5;
+                       PUT_32BIT(q, 20);
+                       q += 4;
+                       memcpy(q, ssh2_session_id, 20);
+                       q += 20;
+                       memcpy(q, pktout.data + 5, pktout.length - 5);
+                       q += pktout.length - 5;
                        /* And finally the (zero) flags word. */
                        PUT_32BIT(q, 0);
-                       agent_query(agentreq, len+4, &ret, &retlen);
+                       agent_query(agentreq, len + 4, &vret, &retlen);
+                       ret = vret;
                        sfree(agentreq);
                        if (ret) {
                            if (ret[4] == SSH2_AGENT_SIGN_RESPONSE) {
                                logevent("Sending Pageant's response");
                                ssh2_pkt_addstring_start();
-                               ssh2_pkt_addstring_data(ret+9, GET_32BIT(ret+5));
+                               ssh2_pkt_addstring_data(ret + 9,
+                                                       GET_32BIT(ret +
+                                                                 5));
                                ssh2_pkt_send();
                                authed = TRUE;
                                break;
                            } else {
-                               logevent("Pageant failed to answer challenge");
+                               logevent
+                                   ("Pageant failed to answer challenge");
                                sfree(ret);
                            }
                        }
@@ -3255,7 +4054,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                }
            }
 
-           if (!method && can_pubkey && *cfg.keyfile && !tried_pubkey_config) {
+           if (!method && can_pubkey && *cfg.keyfile
+               && !tried_pubkey_config) {
                unsigned char *pub_blob;
                char *algorithm, *comment;
                int pub_blob_len;
@@ -3273,20 +4073,20 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                if (pub_blob) {
                    ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
                    ssh2_pkt_addstring(username);
-                   ssh2_pkt_addstring("ssh-connection");   /* service requested */
-                   ssh2_pkt_addstring("publickey");/* method */
-                   ssh2_pkt_addbool(FALSE);   /* no signature included */
+                   ssh2_pkt_addstring("ssh-connection");       /* service requested */
+                   ssh2_pkt_addstring("publickey");    /* method */
+                   ssh2_pkt_addbool(FALSE);    /* no signature included */
                    ssh2_pkt_addstring(algorithm);
                    ssh2_pkt_addstring_start();
                    ssh2_pkt_addstring_data(pub_blob, pub_blob_len);
                    ssh2_pkt_send();
-                   logevent("Offered public key"); /* FIXME */
+                   logevent("Offered public key");     /* FIXME */
 
                    crWaitUntilV(ispkt);
                    if (pktin.type != SSH2_MSG_USERAUTH_PK_OK) {
                        gotit = TRUE;
                        type = AUTH_TYPE_PUBLICKEY_OFFER_LOUD;
-                       continue;              /* key refused; give up on it */
+                       continue;      /* key refused; give up on it */
                    }
 
                    logevent("Offer of public key accepted");
@@ -3295,7 +4095,9 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                     * the key.
                     */
                    if (ssh2_userkey_encrypted(cfg.keyfile, &comment)) {
-                       sprintf(pwprompt, "Passphrase for key \"%.100s\": ", comment);
+                       sprintf(pwprompt,
+                               "Passphrase for key \"%.100s\": ",
+                               comment);
                        need_pw = TRUE;
                    } else {
                        need_pw = FALSE;
@@ -3307,23 +4109,84 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                }
            }
 
+           if (!method && can_keyb_inter && !tried_keyb_inter) {
+               method = AUTH_KEYBOARD_INTERACTIVE;
+               type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
+               tried_keyb_inter = TRUE;
+
+               ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
+               ssh2_pkt_addstring(username);
+               ssh2_pkt_addstring("ssh-connection");   /* service requested */
+               ssh2_pkt_addstring("keyboard-interactive");     /* method */
+               ssh2_pkt_addstring(""); /* lang */
+               ssh2_pkt_addstring("");
+               ssh2_pkt_send();
+
+               crWaitUntilV(ispkt);
+               if (pktin.type != SSH2_MSG_USERAUTH_INFO_REQUEST) {
+                   if (pktin.type == SSH2_MSG_USERAUTH_FAILURE)
+                       gotit = TRUE;
+                   logevent("Keyboard-interactive authentication refused");
+                   type = AUTH_TYPE_KEYBOARD_INTERACTIVE_QUIET;
+                   continue;
+               }
+
+               kbd_inter_running = TRUE;
+           }
+
+           if (kbd_inter_running) {
+               method = AUTH_KEYBOARD_INTERACTIVE;
+               type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
+               tried_keyb_inter = TRUE;
+
+               /* We've got packet with that "interactive" info
+                  dump banners, and set its prompt as ours */
+               {
+                   char *name, *inst, *lang, *prompt;
+                   int name_len, inst_len, lang_len, prompt_len;
+                   ssh2_pkt_getstring(&name, &name_len);
+                   ssh2_pkt_getstring(&inst, &inst_len);
+                   ssh2_pkt_getstring(&lang, &lang_len);
+                   if (name_len > 0)
+                       c_write_untrusted(name, name_len);
+                   if (inst_len > 0)
+                       c_write_untrusted(inst, inst_len);
+                   num_prompts = ssh2_pkt_getuint32();
+
+                   ssh2_pkt_getstring(&prompt, &prompt_len);
+                   strncpy(pwprompt, prompt, sizeof(pwprompt));
+                   pwprompt[prompt_len < sizeof(pwprompt) ?
+                            prompt_len : sizeof(pwprompt)-1] = '\0';
+                   need_pw = TRUE;
+
+                   echo = ssh2_pkt_getbool();
+               }
+           }
+
            if (!method && can_passwd) {
                method = AUTH_PASSWORD;
-               sprintf(pwprompt, "%.90s@%.90s's password: ", username, savedhost);
+               sprintf(pwprompt, "%.90s@%.90s's password: ", username,
+                       savedhost);
                need_pw = TRUE;
            }
 
            if (need_pw) {
                if (ssh_get_line) {
                    if (!ssh_get_line(pwprompt, password,
-                                      sizeof(password), TRUE)) {
+                                     sizeof(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.
                         */
-                       logevent("No more passwords to try");
+                       ssh2_pkt_init(SSH2_MSG_DISCONNECT);
+                       ssh2_pkt_adduint32(SSH2_DISCONNECT_BY_APPLICATION);
+                       ssh2_pkt_addstring
+                           ("No more passwords available to try");
+                       ssh2_pkt_addstring("en");       /* language tag */
+                       ssh2_pkt_send();
+                       connection_fatal("Unable to authenticate");
                        ssh_state = SSH_STATE_CLOSED;
                        crReturnV;
                    }
@@ -3331,34 +4194,38 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    static int pos = 0;
                    static char c;
 
-                   c_write_str(pwprompt);
+                   c_write_untrusted(pwprompt, strlen(pwprompt));
                    ssh_send_ok = 1;
 
                    pos = 0;
                    while (pos >= 0) {
                        crWaitUntilV(!ispkt);
-                       while (inlen--) switch (c = *in++) {
-                         case 10: case 13:
-                           password[pos] = 0;
-                           pos = -1;
-                           break;
-                         case 8: case 127:
-                           if (pos > 0)
-                               pos--;
-                           break;
-                         case 21: case 27:
-                           pos = 0;
-                           break;
-                         case 3: case 4:
-                           random_save_seed();
-                           exit(0);
-                           break;
-                         default:
-                           if (((c >= ' ' && c <= '~') ||
-                                ((unsigned char)c >= 160)) && pos < 40)
-                               password[pos++] = c;
-                           break;
-                       }
+                       while (inlen--)
+                           switch (c = *in++) {
+                             case 10:
+                             case 13:
+                               password[pos] = 0;
+                               pos = -1;
+                               break;
+                             case 8:
+                             case 127:
+                               if (pos > 0)
+                                   pos--;
+                               break;
+                             case 21:
+                             case 27:
+                               pos = 0;
+                               break;
+                             case 3:
+                             case 4:
+                               random_save_seed();
+                               exit(0);
+                               break;
+                             default:
+                               if (pos < sizeof(password)-1)
+                                   password[pos++] = c;
+                               break;
+                           }
                    }
                    c_write_str("\r\n");
                }
@@ -3382,8 +4249,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    /* Send a spurious AUTH_NONE to return to the top. */
                    ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
                    ssh2_pkt_addstring(username);
-                   ssh2_pkt_addstring("ssh-connection");   /* service requested */
-                   ssh2_pkt_addstring("none");    /* method */
+                   ssh2_pkt_addstring("ssh-connection");       /* service requested */
+                   ssh2_pkt_addstring("none"); /* method */
                    ssh2_pkt_send();
                    type = AUTH_TYPE_NONE;
                } else {
@@ -3397,8 +4264,8 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                     */
                    ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
                    ssh2_pkt_addstring(username);
-                   ssh2_pkt_addstring("ssh-connection");   /* service requested */
-                   ssh2_pkt_addstring("publickey");    /* method */
+                   ssh2_pkt_addstring("ssh-connection");       /* service requested */
+                   ssh2_pkt_addstring("publickey");    /* method */
                    ssh2_pkt_addbool(TRUE);
                    ssh2_pkt_addstring(key->alg->name);
                    blob = key->alg->public_blob(key->data, &blob_len);
@@ -3417,9 +4284,12 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                    sigdata_len = pktout.length - 5 + 4 + 20;
                    sigdata = smalloc(sigdata_len);
                    PUT_32BIT(sigdata, 20);
-                   memcpy(sigdata+4, ssh2_session_id, 20);
-                   memcpy(sigdata+24, pktout.data+5, pktout.length-5);
-                   blob = key->alg->sign(key->data, sigdata, sigdata_len, &blob_len);
+                   memcpy(sigdata + 4, ssh2_session_id, 20);
+                   memcpy(sigdata + 24, pktout.data + 5,
+                          pktout.length - 5);
+                   blob =
+                       key->alg->sign(key->data, sigdata, sigdata_len,
+                                      &blob_len);
                    ssh2_pkt_addstring_start();
                    ssh2_pkt_addstring_data(blob, blob_len);
                    sfree(blob);
@@ -3445,7 +4315,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                 */
                ssh2_pkt_init(SSH2_MSG_USERAUTH_REQUEST);
                ssh2_pkt_addstring(username);
-               ssh2_pkt_addstring("ssh-connection");   /* service requested */
+               ssh2_pkt_addstring("ssh-connection");   /* service requested */
                ssh2_pkt_addstring("password");
                ssh2_pkt_addbool(FALSE);
                ssh2_pkt_addstring(password);
@@ -3456,42 +4326,52 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
                 * reason, we don't do this trick at all because we gain
                 * nothing by it.
                 */
-                if (cscipher) {
-                    int stringlen, i;
-
-                    stringlen = (256 - deferred_len);
-                    stringlen += cscipher->blksize - 1;
-                    stringlen -= (stringlen % cscipher->blksize);
-                    if (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 -= cscomp->disable_compression();
-                    }
+               if (cscipher) {
+                   int stringlen, i;
+
+                   stringlen = (256 - deferred_len);
+                   stringlen += cscipher->blksize - 1;
+                   stringlen -= (stringlen % cscipher->blksize);
+                   if (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 -= cscomp->disable_compression();
+                   }
                    ssh2_pkt_init(SSH2_MSG_IGNORE);
                    ssh2_pkt_addstring_start();
                    for (i = 0; i < stringlen; i++) {
-                        char c = (char)random_byte();
-                        ssh2_pkt_addstring_data(&c, 1);
+                       char c = (char) random_byte();
+                       ssh2_pkt_addstring_data(&c, 1);
                    }
                    ssh2_pkt_defer();
                }
                ssh_pkt_defersend();
                logevent("Sent password");
                type = AUTH_TYPE_PASSWORD;
+           } else if (method == AUTH_KEYBOARD_INTERACTIVE) {
+                ssh2_pkt_init(SSH2_MSG_USERAUTH_INFO_RESPONSE);
+                ssh2_pkt_adduint32(num_prompts);
+                ssh2_pkt_addstring(password);
+                memset(password, 0, sizeof(password));
+                ssh2_pkt_send();
+               type = AUTH_TYPE_KEYBOARD_INTERACTIVE;
            } else {
-               c_write_str("No supported authentication methods left to try!\r\n");
-               logevent("No supported authentications offered. Disconnecting");
+               c_write_str
+                   ("No supported authentication methods left to try!\r\n");
+               logevent
+                   ("No supported authentications offered. Disconnecting");
                ssh2_pkt_init(SSH2_MSG_DISCONNECT);
                ssh2_pkt_adduint32(SSH2_DISCONNECT_BY_APPLICATION);
-               ssh2_pkt_addstring("No supported authentication methods available");
-               ssh2_pkt_addstring("en");   /* language tag */
+               ssh2_pkt_addstring
+                   ("No supported authentication methods available");
+               ssh2_pkt_addstring("en");       /* language tag */
                ssh2_pkt_send();
                ssh_state = SSH_STATE_CLOSED;
                crReturnV;
@@ -3514,26 +4394,26 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
     ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
     ssh2_pkt_addstring("session");
     ssh2_pkt_adduint32(mainchan->localid);
-    ssh2_pkt_adduint32(0x8000UL);  /* our window size */
-    ssh2_pkt_adduint32(0x4000UL);  /* our max pkt size */
+    mainchan->v.v2.locwindow = OUR_V2_WINSIZE;
+    ssh2_pkt_adduint32(mainchan->v.v2.locwindow);      /* our window size */
+    ssh2_pkt_adduint32(0x4000UL);      /* our max pkt size */
     ssh2_pkt_send();
     crWaitUntilV(ispkt);
     if (pktin.type != SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
-        bombout(("Server refused to open a session"));
-        crReturnV;
-        /* FIXME: error data comes back in FAILURE packet */
+       bombout(("Server refused to open a session"));
+       crReturnV;
+       /* FIXME: error data comes back in FAILURE packet */
     }
     if (ssh2_pkt_getuint32() != mainchan->localid) {
-        bombout(("Server's channel confirmation cited wrong channel"));
-        crReturnV;
+       bombout(("Server's channel confirmation cited wrong channel"));
+       crReturnV;
     }
     mainchan->remoteid = ssh2_pkt_getuint32();
     mainchan->type = CHAN_MAINSESSION;
     mainchan->closes = 0;
-    mainchan->v2.remwindow = ssh2_pkt_getuint32();
-    mainchan->v2.remmaxpkt = ssh2_pkt_getuint32();
-    mainchan->v2.outbuffer = NULL;
-    mainchan->v2.outbuflen = mainchan->v2.outbufsize = 0;
+    mainchan->v.v2.remwindow = ssh2_pkt_getuint32();
+    mainchan->v.v2.remmaxpkt = ssh2_pkt_getuint32();
+    bufchain_init(&mainchan->v.v2.outbuffer);
     add234(ssh_channels, mainchan);
     logevent("Opened channel for session");
 
@@ -3541,393 +4421,674 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
      * Potentially enable X11 forwarding.
      */
     if (cfg.x11_forward) {
-        char proto[20], data[64];
-        logevent("Requesting X11 forwarding");
-        x11_invent_auth(proto, sizeof(proto), data, sizeof(data));
-        ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-        ssh2_pkt_adduint32(mainchan->remoteid);
-        ssh2_pkt_addstring("x11-req");
-        ssh2_pkt_addbool(1);           /* want reply */
-        ssh2_pkt_addbool(0);           /* many connections */
-        ssh2_pkt_addstring(proto);
-        ssh2_pkt_addstring(data);
-        ssh2_pkt_adduint32(0);         /* screen number */
-        ssh2_pkt_send();
-
-        do {
-            crWaitUntilV(ispkt);
-            if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-                unsigned i = ssh2_pkt_getuint32();
-                struct ssh_channel *c;
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (!c)
-                    continue;          /* nonexistent channel */
-                c->v2.remwindow += ssh2_pkt_getuint32();
-            }
-        } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-
-        if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
-            if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
-                bombout(("Server got confused by X11 forwarding request"));
-                crReturnV;
-            }
-            logevent("X11 forwarding refused");
-        } else {
-            logevent("X11 forwarding enabled");
+       char proto[20], data[64];
+       logevent("Requesting X11 forwarding");
+       x11_invent_auth(proto, sizeof(proto), data, sizeof(data));
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+       ssh2_pkt_adduint32(mainchan->remoteid);
+       ssh2_pkt_addstring("x11-req");
+       ssh2_pkt_addbool(1);           /* want reply */
+       ssh2_pkt_addbool(0);           /* many connections */
+       ssh2_pkt_addstring(proto);
+       ssh2_pkt_addstring(data);
+       ssh2_pkt_adduint32(0);         /* screen number */
+       ssh2_pkt_send();
+
+       do {
+           crWaitUntilV(ispkt);
+           if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               c->v.v2.remwindow += ssh2_pkt_getuint32();
+           }
+       } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+
+       if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
+           if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
+               bombout(("Unexpected response to X11 forwarding request:"
+                        " packet type %d", pktin.type));
+               crReturnV;
+           }
+           logevent("X11 forwarding refused");
+       } else {
+           logevent("X11 forwarding enabled");
            ssh_X11_fwd_enabled = TRUE;
-        }
+       }
+    }
+
+    /*
+     * Enable port forwardings.
+     */
+    {
+       static char *e;                /* preserve across crReturn */
+       char type;
+       int n;
+       int sport,dport;
+       char sports[256], dports[256], host[256];
+       char buf[1024];
+
+       ssh_rportfwds = newtree234(ssh_rportcmp_ssh2);
+        /* Add port forwardings. */
+       e = cfg.portfwd;
+       while (*e) {
+           type = *e++;
+           n = 0;
+           while (*e && *e != '\t')
+               sports[n++] = *e++;
+           sports[n] = 0;
+           if (*e == '\t')
+               e++;
+           n = 0;
+           while (*e && *e != ':')
+               host[n++] = *e++;
+           host[n] = 0;
+           if (*e == ':')
+               e++;
+           n = 0;
+           while (*e)
+               dports[n++] = *e++;
+           dports[n] = 0;
+           e++;
+           dport = atoi(dports);
+           sport = atoi(sports);
+           if (sport && dport) {
+               if (type == 'L') {
+                   pfd_addforward(host, dport, sport);
+                   sprintf(buf, "Local port %d forwarding to %s:%d",
+                           sport, host, dport);
+                   logevent(buf);
+               } else {
+                   struct ssh_rportfwd *pf;
+                   pf = smalloc(sizeof(*pf));
+                   strcpy(pf->dhost, host);
+                   pf->dport = dport;
+                   pf->sport = sport;
+                   if (add234(ssh_rportfwds, pf) != pf) {
+                       sprintf(buf, 
+                               "Duplicate remote port forwarding to %s:%d",
+                               host, dport);
+                       logevent(buf);
+                       sfree(pf);
+                   } else {
+                       sprintf(buf, "Requesting remote port %d (forwarded to %s:%d)",
+                               sport, host, dport);
+                       logevent(buf);
+                       ssh2_pkt_init(SSH2_MSG_GLOBAL_REQUEST);
+                       ssh2_pkt_addstring("tcpip-forward");
+                       ssh2_pkt_addbool(1);/* want reply */
+                       ssh2_pkt_addstring("127.0.0.1");
+                       ssh2_pkt_adduint32(sport);
+                       ssh2_pkt_send();
+
+                       do {
+                           crWaitUntilV(ispkt);
+                           if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
+                               unsigned i = ssh2_pkt_getuint32();
+                               struct ssh_channel *c;
+                               c = find234(ssh_channels, &i, ssh_channelfind);
+                               if (!c)
+                                   continue;/* nonexistent channel */
+                               c->v.v2.remwindow += ssh2_pkt_getuint32();
+                           }
+                       } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+
+                       if (pktin.type != SSH2_MSG_REQUEST_SUCCESS) {
+                           if (pktin.type != SSH2_MSG_REQUEST_FAILURE) {
+                               bombout(("Unexpected response to port "
+                                        "forwarding request: packet type %d",
+                                        pktin.type));
+                               crReturnV;
+                           }
+                           logevent("Server refused this port forwarding");
+                       } else {
+                           logevent("Remote port forwarding enabled");
+                       }
+                   }
+               }
+           }
+       }
     }
 
     /*
      * Potentially enable agent forwarding.
      */
     if (cfg.agentfwd && agent_exists()) {
-        logevent("Requesting OpenSSH-style agent forwarding");
-        ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-        ssh2_pkt_adduint32(mainchan->remoteid);
-        ssh2_pkt_addstring("auth-agent-req@openssh.com");
-        ssh2_pkt_addbool(1);           /* want reply */
-        ssh2_pkt_send();
-
-        do {
-            crWaitUntilV(ispkt);
-            if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-                unsigned i = ssh2_pkt_getuint32();
-                struct ssh_channel *c;
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (!c)
-                    continue;          /* nonexistent channel */
-                c->v2.remwindow += ssh2_pkt_getuint32();
-            }
-        } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-
-        if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
-            if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
-                bombout(("Server got confused by agent forwarding request"));
-                crReturnV;
-            }
-            logevent("Agent forwarding refused");
-        } else {
-            logevent("Agent forwarding enabled");
+       logevent("Requesting OpenSSH-style agent forwarding");
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+       ssh2_pkt_adduint32(mainchan->remoteid);
+       ssh2_pkt_addstring("auth-agent-req@openssh.com");
+       ssh2_pkt_addbool(1);           /* want reply */
+       ssh2_pkt_send();
+
+       do {
+           crWaitUntilV(ispkt);
+           if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               c->v.v2.remwindow += ssh2_pkt_getuint32();
+           }
+       } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+
+       if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
+           if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
+               bombout(("Unexpected response to agent forwarding request:"
+                        " packet type %d", pktin.type));
+               crReturnV;
+           }
+           logevent("Agent forwarding refused");
+       } else {
+           logevent("Agent forwarding enabled");
            ssh_agentfwd_enabled = TRUE;
-        }
+       }
     }
 
     /*
      * Now allocate a pty for the session.
      */
     if (!cfg.nopty) {
-        ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-        ssh2_pkt_adduint32(mainchan->remoteid); /* recipient channel */
-        ssh2_pkt_addstring("pty-req");
-        ssh2_pkt_addbool(1);           /* want reply */
-        ssh2_pkt_addstring(cfg.termtype);
-        ssh2_pkt_adduint32(cols);
-        ssh2_pkt_adduint32(rows);
-        ssh2_pkt_adduint32(0);         /* pixel width */
-        ssh2_pkt_adduint32(0);         /* pixel height */
-        ssh2_pkt_addstring_start();
-        ssh2_pkt_addstring_data("\0", 1);/* TTY_OP_END, no special options */
-        ssh2_pkt_send();
-        ssh_state = SSH_STATE_INTERMED;
-
-        do {
-            crWaitUntilV(ispkt);
-            if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-                unsigned i = ssh2_pkt_getuint32();
-                struct ssh_channel *c;
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (!c)
-                    continue;          /* nonexistent channel */
-                c->v2.remwindow += ssh2_pkt_getuint32();
-            }
-        } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-
-        if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
-            if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
-                bombout(("Server got confused by pty request"));
-                crReturnV;
-            }
-            c_write_str("Server refused to allocate pty\r\n");
-            ssh_editing = ssh_echoing = 1;
-        } else {
-            logevent("Allocated pty");
-        }
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+       ssh2_pkt_adduint32(mainchan->remoteid); /* recipient channel */
+       ssh2_pkt_addstring("pty-req");
+       ssh2_pkt_addbool(1);           /* want reply */
+       ssh2_pkt_addstring(cfg.termtype);
+       ssh2_pkt_adduint32(cols);
+       ssh2_pkt_adduint32(rows);
+       ssh2_pkt_adduint32(0);         /* pixel width */
+       ssh2_pkt_adduint32(0);         /* pixel height */
+       ssh2_pkt_addstring_start();
+       ssh2_pkt_addstring_data("\0", 1);       /* TTY_OP_END, no special options */
+       ssh2_pkt_send();
+       ssh_state = SSH_STATE_INTERMED;
+
+       do {
+           crWaitUntilV(ispkt);
+           if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               c->v.v2.remwindow += ssh2_pkt_getuint32();
+           }
+       } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+
+       if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
+           if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
+               bombout(("Unexpected response to pty request:"
+                        " packet type %d", pktin.type));
+               crReturnV;
+           }
+           c_write_str("Server refused to allocate pty\r\n");
+           ssh_editing = ssh_echoing = 1;
+       } else {
+           logevent("Allocated pty");
+       }
     } else {
-        ssh_editing = ssh_echoing = 1;
+       ssh_editing = ssh_echoing = 1;
     }
 
     /*
-     * Start a shell or a remote command.
+     * Start a shell or a remote command. We may have to attempt
+     * this twice if the config data has provided a second choice
+     * of command.
      */
-    ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-    ssh2_pkt_adduint32(mainchan->remoteid); /* recipient channel */
-    if (cfg.ssh_subsys) {
-        ssh2_pkt_addstring("subsystem");
-        ssh2_pkt_addbool(1);           /* want reply */
-        ssh2_pkt_addstring(cfg.remote_cmd_ptr);
-    } else if (*cfg.remote_cmd_ptr) {
-        ssh2_pkt_addstring("exec");
-        ssh2_pkt_addbool(1);           /* want reply */
-        ssh2_pkt_addstring(cfg.remote_cmd_ptr);
-    } else {
-        ssh2_pkt_addstring("shell");
-        ssh2_pkt_addbool(1);           /* want reply */
-    }
-    ssh2_pkt_send();
-    do {
-        crWaitUntilV(ispkt);
-        if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-            unsigned i = ssh2_pkt_getuint32();
-            struct ssh_channel *c;
-            c = find234(ssh_channels, &i, ssh_channelfind);
-            if (!c)
-                continue;              /* nonexistent channel */
-            c->v2.remwindow += ssh2_pkt_getuint32();
-        }
-    } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-    if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
-        if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
-            bombout(("Server got confused by shell/command request"));
-            crReturnV;
-        }
-        bombout(("Server refused to start a shell/command"));
-        crReturnV;
-    } else {
-        logevent("Started a shell/command");
+    while (1) {
+       int subsys;
+       char *cmd;
+
+       if (ssh_fallback_cmd) {
+           subsys = cfg.ssh_subsys2;
+           cmd = cfg.remote_cmd_ptr2;
+       } else {
+           subsys = cfg.ssh_subsys;
+           cmd = cfg.remote_cmd_ptr;
+       }
+
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+       ssh2_pkt_adduint32(mainchan->remoteid); /* recipient channel */
+       if (subsys) {
+           ssh2_pkt_addstring("subsystem");
+           ssh2_pkt_addbool(1);               /* want reply */
+           ssh2_pkt_addstring(cmd);
+       } else if (*cmd) {
+           ssh2_pkt_addstring("exec");
+           ssh2_pkt_addbool(1);               /* want reply */
+           ssh2_pkt_addstring(cmd);
+       } else {
+           ssh2_pkt_addstring("shell");
+           ssh2_pkt_addbool(1);               /* want reply */
+       }
+       ssh2_pkt_send();
+       do {
+           crWaitUntilV(ispkt);
+           if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               c->v.v2.remwindow += ssh2_pkt_getuint32();
+           }
+       } while (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+       if (pktin.type != SSH2_MSG_CHANNEL_SUCCESS) {
+           if (pktin.type != SSH2_MSG_CHANNEL_FAILURE) {
+               bombout(("Unexpected response to shell/command request:"
+                        " packet type %d", pktin.type));
+               crReturnV;
+           }
+           /*
+            * We failed to start the command. If this is the
+            * fallback command, we really are finished; if it's
+            * not, and if the fallback command exists, try falling
+            * back to it before complaining.
+            */
+           if (!ssh_fallback_cmd && cfg.remote_cmd_ptr2 != NULL) {
+               logevent("Primary command failed; attempting fallback");
+               ssh_fallback_cmd = TRUE;
+               continue;
+           }
+           bombout(("Server refused to start a shell/command"));
+           crReturnV;
+       } else {
+           logevent("Started a shell/command");
+       }
+       break;
     }
 
     ssh_state = SSH_STATE_SESSION;
     if (size_needed)
        ssh_size();
     if (eof_needed)
-        ssh_special(TS_EOF);
+       ssh_special(TS_EOF);
 
     /*
      * Transfer data!
      */
-    ldisc_send(NULL, 0);               /* cause ldisc to notice changes */
+    ldisc_send(NULL, 0, 0);           /* cause ldisc to notice changes */
     ssh_send_ok = 1;
     while (1) {
-        static int try_send;
+       static int try_send;
        crReturnV;
-        try_send = FALSE;
+       try_send = FALSE;
        if (ispkt) {
            if (pktin.type == SSH2_MSG_CHANNEL_DATA ||
-                pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA) {
-                char *data;
-                int length;
-                unsigned i = ssh2_pkt_getuint32();
-                struct ssh_channel *c;
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (!c)
-                    continue;          /* nonexistent channel */
-                if (pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA &&
-                    ssh2_pkt_getuint32() != SSH2_EXTENDED_DATA_STDERR)
-                    continue;          /* extended but not stderr */
-                ssh2_pkt_getstring(&data, &length);
-                if (data) {
-                    switch (c->type) {
-                      case CHAN_MAINSESSION:
-                        from_backend(pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA,
-                                     data, length);
-                        break;
-                      case CHAN_X11:
-                        x11_send(c->u.x11.s, data, length);
-                        break;
+               pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA) {
+               char *data;
+               int length;
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               if (pktin.type == SSH2_MSG_CHANNEL_EXTENDED_DATA &&
+                   ssh2_pkt_getuint32() != SSH2_EXTENDED_DATA_STDERR)
+                   continue;          /* extended but not stderr */
+               ssh2_pkt_getstring(&data, &length);
+               if (data) {
+                   int bufsize;
+                   c->v.v2.locwindow -= length;
+                   switch (c->type) {
+                     case CHAN_MAINSESSION:
+                       bufsize =
+                           from_backend(pktin.type ==
+                                        SSH2_MSG_CHANNEL_EXTENDED_DATA,
+                                        data, length);
+                       break;
+                     case CHAN_X11:
+                       bufsize = x11_send(c->u.x11.s, data, length);
+                       break;
+                     case CHAN_SOCKDATA:
+                       bufsize = pfd_send(c->u.pfd.s, data, length);
+                       break;
                      case CHAN_AGENT:
-                        while (length > 0) {
-                            if (c->u.a.lensofar < 4) {
-                                int l = min(4 - c->u.a.lensofar, length);
-                                memcpy(c->u.a.msglen + c->u.a.lensofar, data, l);
-                                data += l; length -= l; c->u.a.lensofar += l;
-                            }
-                            if (c->u.a.lensofar == 4) {
-                                c->u.a.totallen = 4 + GET_32BIT(c->u.a.msglen);
-                                c->u.a.message = smalloc(c->u.a.totallen);
-                                memcpy(c->u.a.message, c->u.a.msglen, 4);
-                            }
-                            if (c->u.a.lensofar >= 4 && length > 0) {
-                                int l = min(c->u.a.totallen - c->u.a.lensofar,
-                                           length);
-                                memcpy(c->u.a.message + c->u.a.lensofar, data, l);
-                                data += l; length -= l; c->u.a.lensofar += l;
-                            }
-                            if (c->u.a.lensofar == c->u.a.totallen) {
-                                void *reply, *sentreply;
-                                int replylen;
-                                agent_query(c->u.a.message, c->u.a.totallen,
-                                            &reply, &replylen);
-                                if (reply)
-                                    sentreply = reply;
-                                else {
-                                    /* Fake SSH_AGENT_FAILURE. */
-                                    sentreply = "\0\0\0\1\5";
-                                    replylen = 5;
-                                }
-                               ssh2_add_channel_data(c, sentreply, replylen);
+                       while (length > 0) {
+                           if (c->u.a.lensofar < 4) {
+                               int l = min(4 - c->u.a.lensofar, length);
+                               memcpy(c->u.a.msglen + c->u.a.lensofar,
+                                      data, l);
+                               data += l;
+                               length -= l;
+                               c->u.a.lensofar += l;
+                           }
+                           if (c->u.a.lensofar == 4) {
+                               c->u.a.totallen =
+                                   4 + GET_32BIT(c->u.a.msglen);
+                               c->u.a.message = smalloc(c->u.a.totallen);
+                               memcpy(c->u.a.message, c->u.a.msglen, 4);
+                           }
+                           if (c->u.a.lensofar >= 4 && length > 0) {
+                               int l =
+                                   min(c->u.a.totallen - c->u.a.lensofar,
+                                       length);
+                               memcpy(c->u.a.message + c->u.a.lensofar,
+                                      data, l);
+                               data += l;
+                               length -= l;
+                               c->u.a.lensofar += l;
+                           }
+                           if (c->u.a.lensofar == c->u.a.totallen) {
+                               void *reply, *sentreply;
+                               int replylen;
+                               agent_query(c->u.a.message,
+                                           c->u.a.totallen, &reply,
+                                           &replylen);
+                               if (reply)
+                                   sentreply = reply;
+                               else {
+                                   /* Fake SSH_AGENT_FAILURE. */
+                                   sentreply = "\0\0\0\1\5";
+                                   replylen = 5;
+                               }
+                               ssh2_add_channel_data(c, sentreply,
+                                                     replylen);
                                try_send = TRUE;
-                                if (reply)
-                                    sfree(reply);
-                                sfree(c->u.a.message);
-                                c->u.a.lensofar = 0;
-                            }
-                        }
-                        break;
-                    }
-                    /*
-                     * Enlarge the window again at the remote
-                     * side, just in case it ever runs down and
-                     * they fail to send us any more data.
-                     */
-                    ssh2_pkt_init(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-                    ssh2_pkt_adduint32(c->remoteid);
-                    ssh2_pkt_adduint32(length);
-                    ssh2_pkt_send();
-                }
+                               if (reply)
+                                   sfree(reply);
+                               sfree(c->u.a.message);
+                               c->u.a.lensofar = 0;
+                           }
+                       }
+                       bufsize = 0;
+                       break;
+                   }
+                   /*
+                    * If we are not buffering too much data,
+                    * enlarge the window again at the remote side.
+                    */
+                   if (bufsize < OUR_V2_WINSIZE)
+                       ssh2_set_window(c, OUR_V2_WINSIZE - bufsize);
+               }
            } else if (pktin.type == SSH2_MSG_DISCONNECT) {
-                ssh_state = SSH_STATE_CLOSED;
+               ssh_state = SSH_STATE_CLOSED;
                logevent("Received disconnect message");
-                crReturnV;
-           } else if (pktin.type == SSH2_MSG_CHANNEL_REQUEST) {
-                continue;              /* exit status et al; ignore (FIXME?) */
+               crReturnV;
            } else if (pktin.type == SSH2_MSG_CHANNEL_EOF) {
-                unsigned i = ssh2_pkt_getuint32();
-                struct ssh_channel *c;
-
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (!c)
-                    continue;          /* nonexistent channel */
-                
-                if (c->type == CHAN_X11) {
-                    /*
-                     * Remote EOF on an X11 channel means we should
-                     * wrap up and close the channel ourselves.
-                     */
-                    x11_close(c->u.x11.s);
-                    sshfwd_close(c);
-                } else if (c->type == CHAN_AGENT) {
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+
+               if (c->type == CHAN_X11) {
+                   /*
+                    * Remote EOF on an X11 channel means we should
+                    * wrap up and close the channel ourselves.
+                    */
+                   x11_close(c->u.x11.s);
+                   sshfwd_close(c);
+               } else if (c->type == CHAN_AGENT) {
+                   sshfwd_close(c);
+               } else if (c->type == CHAN_SOCKDATA) {
+                   pfd_close(c->u.pfd.s);
                    sshfwd_close(c);
                }
            } else if (pktin.type == SSH2_MSG_CHANNEL_CLOSE) {
-                unsigned i = ssh2_pkt_getuint32();
-                struct ssh_channel *c;
-
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (!c)
-                    continue;          /* nonexistent channel */
-                if (c->closes == 0) {
-                    ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
-                    ssh2_pkt_adduint32(c->remoteid);
-                    ssh2_pkt_send();
-                }
-                /* Do pre-close processing on the channel. */
-                switch (c->type) {
-                  case CHAN_MAINSESSION:
-                    break;             /* nothing to see here, move along */
-                  case CHAN_X11:
-                    break;
-                  case CHAN_AGENT:
-                    break;
-                }
-                del234(ssh_channels, c);
-                sfree(c->v2.outbuffer);
-                sfree(c);
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               /* Do pre-close processing on the channel. */
+               switch (c->type) {
+                 case CHAN_MAINSESSION:
+                   break;             /* nothing to see here, move along */
+                 case CHAN_X11:
+                   if (c->u.x11.s != NULL)
+                       x11_close(c->u.x11.s);
+                   sshfwd_close(c);
+                   break;
+                 case CHAN_AGENT:
+                   sshfwd_close(c);
+                   break;
+                 case CHAN_SOCKDATA:
+                   if (c->u.pfd.s != NULL)
+                       pfd_close(c->u.pfd.s);
+                   sshfwd_close(c);
+                   break;
+               }
+               if (c->closes == 0) {
+                   ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
+                   ssh2_pkt_adduint32(c->remoteid);
+                   ssh2_pkt_send();
+               }
+               del234(ssh_channels, c);
+               bufchain_clear(&c->v.v2.outbuffer);
+               sfree(c);
 
-                /*
-                 * See if that was the last channel left open.
-                 */
-                if (count234(ssh_channels) == 0) {
-                    logevent("All channels closed. Disconnecting");
-                    ssh2_pkt_init(SSH2_MSG_DISCONNECT);
-                    ssh2_pkt_adduint32(SSH2_DISCONNECT_BY_APPLICATION);
-                    ssh2_pkt_addstring("All open channels closed");
-                    ssh2_pkt_addstring("en");   /* language tag */
-                    ssh2_pkt_send();
-                    ssh_state = SSH_STATE_CLOSED;
-                    crReturnV;
-                }
-                continue;              /* remote sends close; ignore (FIXME) */
+               /*
+                * See if that was the last channel left open.
+                */
+               if (count234(ssh_channels) == 0) {
+                   logevent("All channels closed. Disconnecting");
+                   ssh2_pkt_init(SSH2_MSG_DISCONNECT);
+                   ssh2_pkt_adduint32(SSH2_DISCONNECT_BY_APPLICATION);
+                   ssh2_pkt_addstring("All open channels closed");
+                   ssh2_pkt_addstring("en");   /* language tag */
+                   ssh2_pkt_send();
+                   ssh_state = SSH_STATE_CLOSED;
+                   crReturnV;
+               }
+               continue;              /* remote sends close; ignore (FIXME) */
            } else if (pktin.type == SSH2_MSG_CHANNEL_WINDOW_ADJUST) {
-                unsigned i = ssh2_pkt_getuint32();
-                struct ssh_channel *c;
-                c = find234(ssh_channels, &i, ssh_channelfind);
-                if (!c)
-                    continue;          /* nonexistent channel */
-                c->v2.remwindow += ssh2_pkt_getuint32();
-                try_send = TRUE;
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               c->v.v2.remwindow += ssh2_pkt_getuint32();
+               try_send = TRUE;
+           } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN_CONFIRMATION) {
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               if (c->type != CHAN_SOCKDATA_DORMANT)
+                   continue;          /* dunno why they're confirming this */
+               c->remoteid = ssh2_pkt_getuint32();
+               c->type = CHAN_SOCKDATA;
+               c->v.v2.remwindow = ssh2_pkt_getuint32();
+               c->v.v2.remmaxpkt = ssh2_pkt_getuint32();
+               bufchain_init(&c->v.v2.outbuffer);
+               if (c->u.pfd.s)
+                   pfd_confirm(c->u.pfd.s);
+               if (c->closes) {
+                   /*
+                    * We have a pending close on this channel,
+                    * which we decided on before the server acked
+                    * the channel open. So now we know the
+                    * remoteid, we can close it again.
+                    */
+                   ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
+                   ssh2_pkt_adduint32(c->remoteid);
+                   ssh2_pkt_send();
+               }
+           } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN_FAILURE) {
+               unsigned i = ssh2_pkt_getuint32();
+               struct ssh_channel *c;
+               c = find234(ssh_channels, &i, ssh_channelfind);
+               if (!c)
+                   continue;          /* nonexistent channel */
+               if (c->type != CHAN_SOCKDATA_DORMANT)
+                   continue;          /* dunno why they're failing this */
+
+               logevent("Forwarded connection refused by server");
+
+               pfd_close(c->u.pfd.s);
+
+               del234(ssh_channels, c);
+               sfree(c);
+           } else if (pktin.type == SSH2_MSG_CHANNEL_REQUEST) {
+               unsigned localid;
+               char *type;
+               int typelen, want_reply;
+               struct ssh_channel *c;
+
+               localid = ssh2_pkt_getuint32();
+               ssh2_pkt_getstring(&type, &typelen);
+               want_reply = ssh2_pkt_getbool();
+
+               /*
+                * First, check that the channel exists. Otherwise,
+                * we can instantly disconnect with a rude message.
+                */
+               c = find234(ssh_channels, &localid, ssh_channelfind);
+               if (!c) {
+                   char buf[80];
+                   sprintf(buf, "Received channel request for nonexistent"
+                           " channel %d", localid);
+                   logevent(buf);
+                   ssh2_pkt_init(SSH2_MSG_DISCONNECT);
+                   ssh2_pkt_adduint32(SSH2_DISCONNECT_BY_APPLICATION);
+                   ssh2_pkt_addstring(buf);
+                   ssh2_pkt_addstring("en");   /* language tag */
+                   ssh2_pkt_send();
+                   connection_fatal(buf);
+                   ssh_state = SSH_STATE_CLOSED;
+                   crReturnV;
+               }
+
+               /*
+                * We don't recognise any form of channel request,
+                * so we now either ignore the request or respond
+                * with CHANNEL_FAILURE, depending on want_reply.
+                */
+               if (want_reply) {
+                   ssh2_pkt_init(SSH2_MSG_CHANNEL_FAILURE);
+                   ssh2_pkt_adduint32(c->remoteid);
+                   ssh2_pkt_send();
+               }
            } else if (pktin.type == SSH2_MSG_CHANNEL_OPEN) {
-                char *type;
-                int typelen;
-                char *error = NULL;
-                struct ssh_channel *c;
-                ssh2_pkt_getstring(&type, &typelen);
-                c = smalloc(sizeof(struct ssh_channel));
-
-                if (typelen == 3 && !memcmp(type, "x11", 3)) {
-                    if (!ssh_X11_fwd_enabled)
-                        error = "X11 forwarding is not enabled";
-                    else if ( x11_init(&c->u.x11.s, cfg.x11_display, c) != NULL ) {
-                        error = "Unable to open an X11 connection";
-                    } else {
-                        c->type = CHAN_X11;
-                    }
-                } else if (typelen == 22 &&
+               char *type;
+               int typelen;
+               char *error = NULL;
+               struct ssh_channel *c;
+               unsigned remid, winsize, pktsize;
+               ssh2_pkt_getstring(&type, &typelen);
+               c = smalloc(sizeof(struct ssh_channel));
+
+               remid = ssh2_pkt_getuint32();
+               winsize = ssh2_pkt_getuint32();
+               pktsize = ssh2_pkt_getuint32();
+
+               if (typelen == 3 && !memcmp(type, "x11", 3)) {
+                   if (!ssh_X11_fwd_enabled)
+                       error = "X11 forwarding is not enabled";
+                   else if (x11_init(&c->u.x11.s, cfg.x11_display, c) !=
+                            NULL) {
+                       error = "Unable to open an X11 connection";
+                   } else {
+                       c->type = CHAN_X11;
+                   }
+               } else if (typelen == 15 &&
+                          !memcmp(type, "forwarded-tcpip", 15)) {
+                   struct ssh_rportfwd pf, *realpf;
+                   char *dummy;
+                   int dummylen;
+                   ssh2_pkt_getstring(&dummy, &dummylen);/* skip address */
+                   pf.sport = ssh2_pkt_getuint32();
+                   realpf = find234(ssh_rportfwds, &pf, NULL);
+                   if (realpf == NULL) {
+                       error = "Remote port is not recognised";
+                   } else {
+                       char *e = pfd_newconnect(&c->u.pfd.s, realpf->dhost,
+                                                realpf->dport, c);
+                       char buf[1024];
+                       sprintf(buf, "Received remote port open request for %s:%d",
+                               realpf->dhost, realpf->dport);
+                       logevent(buf);
+                       if (e != NULL) {
+                           sprintf(buf, "Port open failed: %s", e);
+                           logevent(buf);
+                           error = "Port open failed";
+                       } else {
+                           logevent("Forwarded port opened successfully");
+                           c->type = CHAN_SOCKDATA;
+                       }
+                   }
+               } else if (typelen == 22 &&
                           !memcmp(type, "auth-agent@openssh.com", 3)) {
-                    if (!ssh_agentfwd_enabled)
-                        error = "Agent forwarding is not enabled";
+                   if (!ssh_agentfwd_enabled)
+                       error = "Agent forwarding is not enabled";
                    else {
-                       c->type = CHAN_AGENT;   /* identify channel type */
+                       c->type = CHAN_AGENT;   /* identify channel type */
                        c->u.a.lensofar = 0;
-                    }
-                } else {
-                    error = "Unsupported channel type requested";
-                }
-
-                c->remoteid = ssh2_pkt_getuint32();
-                if (error) {
-                    ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_FAILURE);
-                    ssh2_pkt_adduint32(c->remoteid);
-                    ssh2_pkt_adduint32(SSH2_OPEN_CONNECT_FAILED);
-                    ssh2_pkt_addstring(error);
-                    ssh2_pkt_addstring("en");   /* language tag */
-                    ssh2_pkt_send();
-                    sfree(c);
-                } else {
-                    c->localid = alloc_channel_id();
-                    c->closes = 0;
-                    c->v2.remwindow = ssh2_pkt_getuint32();
-                    c->v2.remmaxpkt = ssh2_pkt_getuint32();
-                    c->v2.outbuffer = NULL;
-                    c->v2.outbuflen = c->v2.outbufsize = 0;
-                    add234(ssh_channels, c);
-                    ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
-                    ssh2_pkt_adduint32(c->remoteid);
-                    ssh2_pkt_adduint32(c->localid);
-                    ssh2_pkt_adduint32(0x8000UL);  /* our window size */
-                    ssh2_pkt_adduint32(0x4000UL);  /* our max pkt size */
-                    ssh2_pkt_send();
-                }
+                   }
+               } else {
+                   error = "Unsupported channel type requested";
+               }
+
+               c->remoteid = remid;
+               if (error) {
+                   ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_FAILURE);
+                   ssh2_pkt_adduint32(c->remoteid);
+                   ssh2_pkt_adduint32(SSH2_OPEN_CONNECT_FAILED);
+                   ssh2_pkt_addstring(error);
+                   ssh2_pkt_addstring("en");   /* language tag */
+                   ssh2_pkt_send();
+                   sfree(c);
+               } else {
+                   c->localid = alloc_channel_id();
+                   c->closes = 0;
+                   c->v.v2.locwindow = OUR_V2_WINSIZE;
+                   c->v.v2.remwindow = winsize;
+                   c->v.v2.remmaxpkt = pktsize;
+                   bufchain_init(&c->v.v2.outbuffer);
+                   add234(ssh_channels, c);
+                   ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
+                   ssh2_pkt_adduint32(c->remoteid);
+                   ssh2_pkt_adduint32(c->localid);
+                   ssh2_pkt_adduint32(c->v.v2.locwindow);
+                   ssh2_pkt_adduint32(0x4000UL);       /* our max pkt size */
+                   ssh2_pkt_send();
+               }
            } else {
                bombout(("Strange packet received: type %d", pktin.type));
-                crReturnV;
+               crReturnV;
            }
        } else {
-            /*
-             * We have spare data. Add it to the channel buffer.
-             */
-            ssh2_add_channel_data(mainchan, in, inlen);
-            try_send = TRUE;
-       }
-        if (try_send) {
-            int i;
-            struct ssh_channel *c;
-            /*
-             * Try to send data on all channels if we can.
-             */
-            for (i = 0; NULL != (c = index234(ssh_channels, i)); i++)
-                ssh2_try_send(c);
-        }
+           /*
+            * We have spare data. Add it to the channel buffer.
+            */
+           ssh2_add_channel_data(mainchan, in, inlen);
+           try_send = TRUE;
+       }
+       if (try_send) {
+           int i;
+           struct ssh_channel *c;
+           /*
+            * Try to send data on all channels if we can.
+            */
+           for (i = 0; NULL != (c = index234(ssh_channels, i)); i++) {
+               int bufsize = ssh2_try_send(c);
+               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;
+                   }
+               }
+           }
+       }
     }
 
     crFinishV;
@@ -3939,7 +5100,7 @@ static void do_ssh2_authconn(unsigned char *in, int inlen, int ispkt)
 static void ssh2_protocol(unsigned char *in, int inlen, int ispkt)
 {
     if (do_ssh2_transport(in, inlen, ispkt) == 0)
-        return;
+       return;
     do_ssh2_authconn(in, inlen, ispkt);
 }
 
@@ -3948,19 +5109,23 @@ static void ssh2_protocol(unsigned char *in, int inlen, int ispkt)
  *
  * Returns an error message, or NULL on success.
  */
-static char *ssh_init (char *host, int port, char **realhost) {
+static char *ssh_init(char *host, int port, char **realhost, int nodelay)
+{
     char *p;
-       
+
 #ifdef MSCRYPTOAPI
-    if(crypto_startup() == 0)
+    if (crypto_startup() == 0)
        return "Microsoft high encryption pack not installed!";
 #endif
 
     ssh_send_ok = 0;
     ssh_editing = 0;
     ssh_echoing = 0;
+    ssh1_throttle_count = 0;
+    ssh_overall_bufsize = 0;
+    ssh_fallback_cmd = 0;
 
-    p = connect_to_host(host, port, realhost);
+    p = connect_to_host(host, port, realhost, nodelay);
     if (p != NULL)
        return p;
 
@@ -3970,17 +5135,51 @@ static char *ssh_init (char *host, int port, char **realhost) {
 /*
  * Called to send data down the Telnet connection.
  */
-static void ssh_send (char *buf, int len) {
+static int ssh_send(char *buf, int len)
+{
     if (s == NULL || ssh_protocol == NULL)
-       return;
+       return 0;
 
     ssh_protocol(buf, len, 0);
+
+    return ssh_sendbuffer();
+}
+
+/*
+ * Called to query the current amount of buffered stdin data.
+ */
+static int ssh_sendbuffer(void)
+{
+    int override_value;
+
+    if (s == NULL || ssh_protocol == NULL)
+       return 0;
+
+    /*
+     * If the SSH socket itself has backed up, add the total backup
+     * size on that to any individual buffer on the stdin channel.
+     */
+    override_value = 0;
+    if (ssh_throttled_all)
+       override_value = ssh_overall_bufsize;
+
+    if (ssh_version == 1) {
+       return override_value;
+    } else if (ssh_version == 2) {
+       if (!mainchan || mainchan->closes > 0)
+           return override_value;
+       else
+           return override_value + bufchain_size(&mainchan->v.v2.outbuffer);
+    }
+
+    return 0;
 }
 
 /*
  * Called to set the size of the window from SSH's POV.
  */
-static void ssh_size(void) {
+static void ssh_size(void)
+{
     switch (ssh_state) {
       case SSH_STATE_BEFORE_SIZE:
       case SSH_STATE_PREPACKET:
@@ -3990,24 +5189,24 @@ static void ssh_size(void) {
        size_needed = TRUE;            /* buffer for later */
        break;
       case SSH_STATE_SESSION:
-        if (!cfg.nopty) {
-            if (ssh_version == 1) {
-                send_packet(SSH1_CMSG_WINDOW_SIZE,
-                            PKT_INT, rows, PKT_INT, cols,
-                            PKT_INT, 0, PKT_INT, 0, PKT_END);
-            } else {
-                ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-                ssh2_pkt_adduint32(mainchan->remoteid);
-                ssh2_pkt_addstring("window-change");
-                ssh2_pkt_addbool(0);
-                ssh2_pkt_adduint32(cols);
-                ssh2_pkt_adduint32(rows);
-                ssh2_pkt_adduint32(0);
-                ssh2_pkt_adduint32(0);
-                ssh2_pkt_send();
-            }
-        }
-        break;
+       if (!cfg.nopty) {
+           if (ssh_version == 1) {
+               send_packet(SSH1_CMSG_WINDOW_SIZE,
+                           PKT_INT, rows, PKT_INT, cols,
+                           PKT_INT, 0, PKT_INT, 0, PKT_END);
+           } else {
+               ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+               ssh2_pkt_adduint32(mainchan->remoteid);
+               ssh2_pkt_addstring("window-change");
+               ssh2_pkt_addbool(0);
+               ssh2_pkt_adduint32(cols);
+               ssh2_pkt_adduint32(rows);
+               ssh2_pkt_adduint32(0);
+               ssh2_pkt_adduint32(0);
+               ssh2_pkt_send();
+           }
+       }
+       break;
     }
 }
 
@@ -4016,57 +5215,139 @@ static void ssh_size(void) {
  * can send an EOF and collect resulting output (e.g. `plink
  * hostname sort').
  */
-static void ssh_special (Telnet_Special code) {
+static void ssh_special(Telnet_Special code)
+{
     if (code == TS_EOF) {
-        if (ssh_state != SSH_STATE_SESSION) {
-            /*
-             * Buffer the EOF in case we are pre-SESSION, so we can
-             * send it as soon as we reach SESSION.
-             */
-            if (code == TS_EOF)
-                eof_needed = TRUE;
-            return;
-        }
-        if (ssh_version == 1) {
-            send_packet(SSH1_CMSG_EOF, PKT_END);
-        } else {
-            ssh2_pkt_init(SSH2_MSG_CHANNEL_EOF);
-            ssh2_pkt_adduint32(mainchan->remoteid);
-            ssh2_pkt_send();
-        }
-        logevent("Sent EOF message");
+       if (ssh_state != SSH_STATE_SESSION) {
+           /*
+            * Buffer the EOF in case we are pre-SESSION, so we can
+            * send it as soon as we reach SESSION.
+            */
+           if (code == TS_EOF)
+               eof_needed = TRUE;
+           return;
+       }
+       if (ssh_version == 1) {
+           send_packet(SSH1_CMSG_EOF, PKT_END);
+       } else {
+           ssh2_pkt_init(SSH2_MSG_CHANNEL_EOF);
+           ssh2_pkt_adduint32(mainchan->remoteid);
+           ssh2_pkt_send();
+       }
+       logevent("Sent EOF message");
     } else if (code == TS_PING) {
-        if (ssh_state == SSH_STATE_CLOSED || ssh_state == SSH_STATE_PREPACKET)
-            return;
-        if (ssh_version == 1) {
-            send_packet(SSH1_MSG_IGNORE, PKT_STR, "", PKT_END);
-        } else {
-            ssh2_pkt_init(SSH2_MSG_IGNORE);
-            ssh2_pkt_addstring_start();
-            ssh2_pkt_send();
-        }
+       if (ssh_state == SSH_STATE_CLOSED
+           || ssh_state == SSH_STATE_PREPACKET) return;
+       if (ssh_version == 1) {
+           send_packet(SSH1_MSG_IGNORE, PKT_STR, "", PKT_END);
+       } else {
+           ssh2_pkt_init(SSH2_MSG_IGNORE);
+           ssh2_pkt_addstring_start();
+           ssh2_pkt_send();
+       }
     } else {
-        /* do nothing */
+       /* do nothing */
     }
 }
 
-static Socket ssh_socket(void) { return s; }
+void *new_sock_channel(Socket s)
+{
+    struct ssh_channel *c;
+    c = smalloc(sizeof(struct ssh_channel));
+
+    if (c) {
+       c->remoteid = -1;              /* to be set when open confirmed */
+       c->localid = alloc_channel_id();
+       c->closes = 0;
+       c->type = CHAN_SOCKDATA_DORMANT;/* identify channel type */
+       c->u.pfd.s = s;
+       add234(ssh_channels, c);
+    }
+    return c;
+}
+
+/*
+ * This is called when stdout/stderr (the entity to which
+ * from_backend sends data) manages to clear some backlog.
+ */
+void ssh_unthrottle(int bufsize)
+{
+    if (ssh_version == 1) {
+       if (ssh1_stdout_throttling && bufsize < SSH1_BUFFER_LIMIT) {
+           ssh1_stdout_throttling = 0;
+           ssh1_throttle(-1);
+       }
+    } else {
+       if (mainchan && mainchan->closes == 0)
+           ssh2_set_window(mainchan, OUR_V2_WINSIZE - bufsize);
+    }
+}
+
+void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
+{
+    struct ssh_channel *c = (struct ssh_channel *)channel;
+    char buf[1024];
 
-static int ssh_sendok(void) { return ssh_send_ok; }
+    sprintf(buf, "Opening forwarded connection to %.512s:%d", hostname, port);
+    logevent(buf);
 
-static int ssh_ldisc(int option) {
-    if (option == LD_ECHO) return ssh_echoing;
-    if (option == LD_EDIT) return ssh_editing;
+    if (ssh_version == 1) {
+       send_packet(SSH1_MSG_PORT_OPEN,
+                   PKT_INT, c->localid,
+                   PKT_STR, hostname,
+                   PKT_INT, port,
+                   //PKT_STR, <org:orgport>,
+                   PKT_END);
+    } else {
+       ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
+       ssh2_pkt_addstring("direct-tcpip");
+       ssh2_pkt_adduint32(c->localid);
+       c->v.v2.locwindow = OUR_V2_WINSIZE;
+       ssh2_pkt_adduint32(c->v.v2.locwindow);/* our window size */
+       ssh2_pkt_adduint32(0x4000UL);      /* our max pkt size */
+       ssh2_pkt_addstring(hostname);
+       ssh2_pkt_adduint32(port);
+       /*
+        * We make up values for the originator data; partly it's
+        * 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.
+        */
+       ssh2_pkt_addstring("client-side-connection");
+       ssh2_pkt_adduint32(0);
+       ssh2_pkt_send();
+    }
+}
+
+
+static Socket ssh_socket(void)
+{
+    return s;
+}
+
+static int ssh_sendok(void)
+{
+    return ssh_send_ok;
+}
+
+static int ssh_ldisc(int option)
+{
+    if (option == LD_ECHO)
+       return ssh_echoing;
+    if (option == LD_EDIT)
+       return ssh_editing;
     return FALSE;
 }
 
 Backend ssh_backend = {
     ssh_init,
     ssh_send,
+    ssh_sendbuffer,
     ssh_size,
     ssh_special,
     ssh_socket,
     ssh_sendok,
     ssh_ldisc,
+    ssh_unthrottle,
     22
 };