Better handling of outstanding CHANNEL_REQUESTS on channel destruction.
[sgt/putty] / ssh.c
diff --git a/ssh.c b/ssh.c
index 439f115..a1cb34b 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -572,6 +572,20 @@ enum {                                    /* channel types */
     CHAN_ZOMBIE
 };
 
+typedef void (*handler_fn_t)(Ssh ssh, struct Packet *pktin);
+typedef void (*chandler_fn_t)(Ssh ssh, struct Packet *pktin, void *ctx);
+typedef void (*cchandler_fn_t)(struct ssh_channel *, struct Packet *, void *);
+
+/*
+ * Each channel has a queue of outstanding CHANNEL_REQUESTS and their
+ * handlers.
+ */
+struct outstanding_channel_request {
+    cchandler_fn_t handler;
+    void *ctx;
+    struct outstanding_channel_request *next;
+};
+
 /*
  * little structure to keep track of outstanding WINDOW_ADJUSTs
  */
@@ -646,10 +660,10 @@ struct ssh_channel {
             */
            int remlocwin;
            /*
-            * These store the list of window adjusts that haven't
+            * These store the list of channel requests that haven't
             * been acked.
             */
-           struct winadj *winadj_head, *winadj_tail;
+           struct outstanding_channel_request *chanreq_head, *chanreq_tail;
            enum { THROTTLED, UNTHROTTLING, UNTHROTTLED } throttle_state;
        } v2;
     } v;
@@ -766,6 +780,7 @@ static void ssh_pkt_getstring(struct Packet *pkt, char **p, int *length);
 static void ssh2_timer(void *ctx, long now);
 static int do_ssh2_transport(Ssh ssh, void *vin, int inlen,
                             struct Packet *pktin);
+static void ssh2_msg_unexpected(Ssh ssh, struct Packet *pktin);
 
 struct rdpkt1_state_tag {
     long len, pad, biglen, to_read;
@@ -784,9 +799,6 @@ struct rdpkt2_state_tag {
     struct Packet *pktin;
 };
 
-typedef void (*handler_fn_t)(Ssh ssh, struct Packet *pktin);
-typedef void (*chandler_fn_t)(Ssh ssh, struct Packet *pktin, void *ctx);
-
 struct queued_handler;
 struct queued_handler {
     int msg1, msg2;
@@ -4232,6 +4244,7 @@ static void ssh_channel_try_eof(struct ssh_channel *c)
     if (ssh->version == 2 && bufchain_size(&c->v.v2.outbuffer) > 0)
         return;              /* can't send EOF: pending outgoing data */
 
+    c->pending_eof = FALSE;            /* we're about to send it */
     if (ssh->version == 1) {
         send_packet(ssh, SSH1_MSG_CHANNEL_CLOSE, PKT_INT, c->remoteid,
                     PKT_END);
@@ -4242,17 +4255,8 @@ static void ssh_channel_try_eof(struct ssh_channel *c)
         ssh2_pkt_adduint32(pktout, c->remoteid);
         ssh2_pkt_send(ssh, pktout);
         c->closes |= CLOSES_SENT_EOF;
-        if (!((CLOSES_SENT_EOF | CLOSES_RCVD_EOF) & ~c->closes)) {
-            /*
-             * Also send MSG_CLOSE.
-             */
-            pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_CLOSE);
-            ssh2_pkt_adduint32(pktout, c->remoteid);
-            ssh2_pkt_send(ssh, pktout);
-            c->closes |= CLOSES_SENT_CLOSE;
-        }
+       ssh2_channel_check_close(c);
     }
-    c->pending_eof = FALSE;            /* we've sent it now */
 }
 
 void sshfwd_write_eof(struct ssh_channel *c)
@@ -6571,14 +6575,65 @@ static void ssh2_channel_init(struct ssh_channel *c)
     c->throttling_conn = FALSE;
     c->v.v2.locwindow = c->v.v2.locmaxwin = c->v.v2.remlocwin =
        conf_get_int(ssh->conf, CONF_ssh_simple) ? OUR_V2_BIGWIN : OUR_V2_WINSIZE;
-    c->v.v2.winadj_head = c->v.v2.winadj_tail = NULL;
+    c->v.v2.chanreq_head = NULL;
     c->v.v2.throttle_state = UNTHROTTLED;
     bufchain_init(&c->v.v2.outbuffer);
 }
 
 /*
+ * CHANNEL_FAILURE doesn't come with any indication of what message
+ * caused it, so we have to keep track of the outstanding
+ * CHANNEL_REQUESTs ourselves.
+ */
+static void ssh2_queue_chanreq_handler(struct ssh_channel *c,
+                                      cchandler_fn_t handler, void *ctx)
+{
+    struct outstanding_channel_request *ocr =
+       snew(struct outstanding_channel_request);
+
+    assert(!(c->closes & (CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE)));
+    ocr->handler = handler;
+    ocr->ctx = ctx;
+    ocr->next = NULL;
+    if (!c->v.v2.chanreq_head)
+       c->v.v2.chanreq_head = ocr;
+    else
+       c->v.v2.chanreq_tail->next = ocr;
+    c->v.v2.chanreq_tail = ocr;
+}
+
+/*
+ * Construct the common parts of a CHANNEL_REQUEST.  If handler is not
+ * NULL then a reply will be requested and the handler will be called
+ * when it arrives.  The returned packet is ready to have any
+ * request-specific data added and be sent.  Note that if a handler is
+ * provided, it's essential that the request actually be sent.
+ *
+ * The handler will usually be passed the response packet in pktin.
+ * If pktin is NULL, this means that no reply will ever be forthcoming
+ * (e.g. because the entire connection is being destroyed) and the
+ * handler should free any storage it's holding.
+ */
+static struct Packet *ssh2_chanreq_init(struct ssh_channel *c, char *type,
+                                       cchandler_fn_t handler, void *ctx)
+{
+    struct Packet *pktout;
+
+    assert(!(c->closes & (CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE)));
+    pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
+    ssh2_pkt_adduint32(pktout, c->remoteid);
+    ssh2_pkt_addstring(pktout, type);
+    ssh2_pkt_addbool(pktout, handler != NULL);
+    if (handler != NULL)
+       ssh2_queue_chanreq_handler(c, handler, ctx);
+    return pktout;
+}
+
+/*
  * Potentially enlarge the window on an SSH-2 channel.
  */
+static void ssh2_handle_winadj_response(struct ssh_channel *, struct Packet *,
+                                       void *);
 static void ssh2_set_window(struct ssh_channel *c, int newwin)
 {
     Ssh ssh = c->ssh;
@@ -6609,7 +6664,7 @@ static void ssh2_set_window(struct ssh_channel *c, int newwin)
      */
     if (newwin / 2 >= c->v.v2.locwindow) {
        struct Packet *pktout;
-       struct winadj *wa;
+       unsigned *up;
 
        /*
         * In order to keep track of how much window the client
@@ -6620,34 +6675,15 @@ static void ssh2_set_window(struct ssh_channel *c, int newwin)
         * This is only necessary if we're opening the window wide.
         * If we're not, then throughput is being constrained by
         * something other than the maximum window size anyway.
-        *
-        * We also only send this if the main channel has finished its
-        * initial CHANNEL_REQUESTs and installed the default
-        * CHANNEL_FAILURE handler, so as not to risk giving it
-        * unexpected CHANNEL_FAILUREs.
         */
        if (newwin == c->v.v2.locmaxwin &&
-           ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] &&
             !(ssh->remote_bugs & BUG_CHOKES_ON_WINADJ)) {
-           pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-           ssh2_pkt_adduint32(pktout, c->remoteid);
-           ssh2_pkt_addstring(pktout, "winadj@putty.projects.tartarus.org");
-           ssh2_pkt_addbool(pktout, TRUE);
+           up = snew(unsigned);
+           *up = newwin - c->v.v2.locwindow;
+           pktout = ssh2_chanreq_init(c, "winadj@putty.projects.tartarus.org",
+                                      ssh2_handle_winadj_response, up);
            ssh2_pkt_send(ssh, pktout);
 
-           /*
-            * CHANNEL_FAILURE doesn't come with any indication of
-            * what message caused it, so we have to keep track of the
-            * outstanding CHANNEL_REQUESTs ourselves.
-            */
-           wa = snew(struct winadj);
-           wa->size = newwin - c->v.v2.locwindow;
-           wa->next = NULL;
-           if (!c->v.v2.winadj_head)
-               c->v.v2.winadj_head = wa;
-           else
-               c->v.v2.winadj_tail->next = wa;
-           c->v.v2.winadj_tail = wa;
            if (c->v.v2.throttle_state != UNTHROTTLED)
                c->v.v2.throttle_state = UNTHROTTLING;
        } else {
@@ -6687,14 +6723,21 @@ static struct ssh_channel *ssh2_channel_msg(Ssh ssh, struct Packet *pktin)
     return c;
 }
 
-static int ssh2_handle_winadj_response(struct ssh_channel *c)
+static void ssh2_handle_winadj_response(struct ssh_channel *c,
+                                       struct Packet *pktin, void *ctx)
 {
-    struct winadj *wa = c->v.v2.winadj_head;
-    if (!wa)
-       return FALSE;
-    c->v.v2.winadj_head = wa->next;
-    c->v.v2.remlocwin += wa->size;
-    sfree(wa);
+    unsigned *sizep = ctx;
+
+    /*
+     * Winadj responses should always be failures. However, at least
+     * one server ("boks_sshd") is known to return SUCCESS for channel
+     * requests it's never heard of, such as "winadj@putty". Raised
+     * with foxt.com as bug 090916-090424, but for the sake of a quiet
+     * life, we don't worry about what kind of response we got.
+     */
+
+    c->v.v2.remlocwin += *sizep;
+    sfree(sizep);
     /*
      * winadj messages are only sent when the window is fully open, so
      * if we get an ack of one, we know any pending unthrottle is
@@ -6702,56 +6745,28 @@ static int ssh2_handle_winadj_response(struct ssh_channel *c)
      */
     if (c->v.v2.throttle_state == UNTHROTTLING)
        c->v.v2.throttle_state = UNTHROTTLED;
-    /*
-     * We may now initiate channel-closing procedures, if that winadj
-     * was the last thing outstanding before we send CHANNEL_CLOSE.
-     */
-    ssh2_channel_check_close(c);
-    return TRUE;
 }
 
-static void ssh2_msg_channel_success(Ssh ssh, struct Packet *pktin)
+static void ssh2_msg_channel_response(Ssh ssh, struct Packet *pktin)
 {
-    /*
-     * This should never get called.  All channel requests are either
-     * sent with want_reply false, are sent before this handler gets
-     * installed, or are "winadj@putty" requests, which servers should
-     * never respond to with success.
-     *
-     * However, at least one server ("boks_sshd") is known to return
-     * SUCCESS for channel requests it's never heard of, such as
-     * "winadj@putty". Raised with foxt.com as bug 090916-090424, but
-     * for the sake of a quiet life, we handle it just the same as the
-     * expected FAILURE.
-     */
-    struct ssh_channel *c;
+    struct ssh_channel *c = ssh2_channel_msg(ssh, pktin);
+    struct outstanding_channel_request *ocr;
 
-    c = ssh2_channel_msg(ssh, pktin);
-    if (!c)
+    if (!c) return;
+    ocr = c->v.v2.chanreq_head;
+    if (!ocr) {
+       ssh2_msg_unexpected(ssh, pktin);
        return;
-    if (!ssh2_handle_winadj_response(c))
-       ssh_disconnect(ssh, NULL,
-                      "Received unsolicited SSH_MSG_CHANNEL_SUCCESS",
-                      SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
-}
-
-static void ssh2_msg_channel_failure(Ssh ssh, struct Packet *pktin)
-{
+    }
+    ocr->handler(c, pktin, ocr->ctx);
+    c->v.v2.chanreq_head = ocr->next;
+    sfree(ocr);
     /*
-     * The only time this should get called is for "winadj@putty"
-     * messages sent above.  All other channel requests are either
-     * sent with want_reply false or are sent before this handler gets
-     * installed.
+     * We may now initiate channel-closing procedures, if that
+     * CHANNEL_REQUEST was the last thing outstanding before we send
+     * CHANNEL_CLOSE.
      */
-    struct ssh_channel *c;
-
-    c = ssh2_channel_msg(ssh, pktin);
-    if (!c)
-       return;
-    if (!ssh2_handle_winadj_response(c))
-       ssh_disconnect(ssh, NULL,
-                      "Received unsolicited SSH_MSG_CHANNEL_FAILURE",
-                      SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
+    ssh2_channel_check_close(c);
 }
 
 static void ssh2_msg_channel_window_adjust(Ssh ssh, struct Packet *pktin)
@@ -6895,8 +6910,10 @@ static void ssh_channel_destroy(struct ssh_channel *c)
     }
 
     del234(ssh->channels, c);
-    if (ssh->version == 2)
+    if (ssh->version == 2) {
         bufchain_clear(&c->v.v2.outbuffer);
+       assert(c->v.v2.chanreq_head == NULL);
+    }
     sfree(c);
 
     /*
@@ -6928,10 +6945,10 @@ static void ssh2_channel_check_close(struct ssh_channel *c)
     struct Packet *pktout;
 
     if ((c->closes & (CLOSES_SENT_EOF | CLOSES_RCVD_EOF | CLOSES_SENT_CLOSE))
-        == (CLOSES_SENT_EOF | CLOSES_RCVD_EOF) && !c->v.v2.winadj_head) {
+        == (CLOSES_SENT_EOF | CLOSES_RCVD_EOF) && !c->v.v2.chanreq_head) {
         /*
          * We have both sent and received EOF, and we have no
-         * outstanding winadj channel requests, which means the
+         * outstanding channel requests, which means the
          * channel is in final wind-up. But we haven't sent CLOSE, so
          * let's do so now.
          */
@@ -6942,6 +6959,7 @@ static void ssh2_channel_check_close(struct ssh_channel *c)
     }
 
     if (!((CLOSES_SENT_CLOSE | CLOSES_RCVD_CLOSE) & ~c->closes)) {
+       assert(c->v.v2.chanreq_head == NULL);
         /*
          * We have both sent and received CLOSE, which means we're
          * completely done with the channel.
@@ -7449,6 +7467,207 @@ static void ssh2_send_ttymode(void *data, char *mode, char *val)
     ssh2_pkt_adduint32(pktout, arg);
 }
 
+static void ssh2_maybe_setup_x11(struct ssh_channel *c, struct Packet *pktin,
+                                void *ctx)
+{
+    struct ssh2_maybe_setup_x11_state {
+       int crLine;
+    };
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+    crStateP(ssh2_maybe_setup_x11_state, ctx);
+
+    crBeginState;
+
+    /*
+     * Potentially enable X11 forwarding.
+     */
+    if (ssh->mainchan && !ssh->ncmode && conf_get_int(ssh->conf, CONF_x11_forward) &&
+       (ssh->x11disp = x11_setup_display(conf_get_str(ssh->conf, CONF_x11_display),
+                                         conf_get_int(ssh->conf, CONF_x11_auth), ssh->conf))) {
+       logevent("Requesting X11 forwarding");
+       pktout = ssh2_chanreq_init(ssh->mainchan, "x11-req",
+                                  ssh2_maybe_setup_x11, s);
+       ssh2_pkt_addbool(pktout, 0);           /* many connections */
+       ssh2_pkt_addstring(pktout, ssh->x11disp->remoteauthprotoname);
+       /*
+        * Note that while we blank the X authentication data here, we don't
+        * take any special action to blank the start of an X11 channel,
+        * so using MIT-MAGIC-COOKIE-1 and actually opening an X connection
+        * without having session blanking enabled is likely to leak your
+        * cookie into the log.
+        */
+       dont_log_password(ssh, pktout, PKTLOG_BLANK);
+       ssh2_pkt_addstring(pktout, ssh->x11disp->remoteauthdatastring);
+       end_log_omission(ssh, pktout);
+       ssh2_pkt_adduint32(pktout, ssh->x11disp->screennum);
+       ssh2_pkt_send(ssh, pktout);
+
+       crWaitUntilV(pktin);
+
+       if (pktin) {
+           if (pktin->type == SSH2_MSG_CHANNEL_SUCCESS) {
+               logevent("X11 forwarding enabled");
+               ssh->X11_fwd_enabled = TRUE;
+           } else
+               logevent("X11 forwarding refused");
+       }
+    }
+    sfree(s);
+    crFinishV;
+}
+
+static void ssh2_maybe_setup_agent(struct ssh_channel *c, struct Packet *pktin,
+                                  void *ctx)
+{
+    struct ssh2_maybe_setup_agent_state {
+       int crLine;
+    };
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+    crStateP(ssh2_maybe_setup_agent_state, ctx);
+
+    crBeginState;
+
+    if (ssh->mainchan && !ssh->ncmode && conf_get_int(ssh->conf, CONF_agentfwd) && agent_exists()) {
+       logevent("Requesting OpenSSH-style agent forwarding");
+       pktout = ssh2_chanreq_init(ssh->mainchan, "auth-agent-req@openssh.com",
+                                  ssh2_maybe_setup_agent, s);
+       ssh2_pkt_send(ssh, pktout);
+
+       crWaitUntilV(pktin);
+
+       if (pktin) {
+           if (pktin->type == SSH2_MSG_CHANNEL_SUCCESS) {
+               logevent("Agent forwarding enabled");
+               ssh->agentfwd_enabled = TRUE;
+           } else
+               logevent("Agent forwarding refused");
+       }
+    }
+    sfree(s);
+    crFinishV;
+}
+
+static void ssh2_maybe_setup_pty(struct ssh_channel *c, struct Packet *pktin,
+                                void *ctx)
+{
+    struct ssh2_maybe_setup_pty_state {
+       int crLine;
+    };
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+    crStateP(ssh2_maybe_setup_pty_state, ctx);
+
+    crBeginState;
+
+    if (ssh->mainchan && !ssh->ncmode && !conf_get_int(ssh->conf, CONF_nopty)) {
+       /* Unpick the terminal-speed string. */
+       /* XXX perhaps we should allow no speeds to be sent. */
+        ssh->ospeed = 38400; ssh->ispeed = 38400; /* last-resort defaults */
+       sscanf(conf_get_str(ssh->conf, CONF_termspeed), "%d,%d", &ssh->ospeed, &ssh->ispeed);
+       /* Build the pty request. */
+       pktout = ssh2_chanreq_init(ssh->mainchan, "pty-req",
+                                  ssh2_maybe_setup_pty, s);
+       ssh2_pkt_addstring(pktout, conf_get_str(ssh->conf, CONF_termtype));
+       ssh2_pkt_adduint32(pktout, ssh->term_width);
+       ssh2_pkt_adduint32(pktout, ssh->term_height);
+       ssh2_pkt_adduint32(pktout, 0);         /* pixel width */
+       ssh2_pkt_adduint32(pktout, 0);         /* pixel height */
+       ssh2_pkt_addstring_start(pktout);
+       parse_ttymodes(ssh, ssh2_send_ttymode, (void *)pktout);
+       ssh2_pkt_addbyte(pktout, SSH2_TTY_OP_ISPEED);
+       ssh2_pkt_adduint32(pktout, ssh->ispeed);
+       ssh2_pkt_addbyte(pktout, SSH2_TTY_OP_OSPEED);
+       ssh2_pkt_adduint32(pktout, ssh->ospeed);
+       ssh2_pkt_addstring_data(pktout, "\0", 1); /* TTY_OP_END */
+       ssh2_pkt_send(ssh, pktout);
+       ssh->state = SSH_STATE_INTERMED;
+
+       crWaitUntilV(pktin);
+
+       if (pktin) {
+           if (pktin->type == SSH2_MSG_CHANNEL_SUCCESS) {
+               logeventf(ssh, "Allocated pty (ospeed %dbps, ispeed %dbps)",
+                         ssh->ospeed, ssh->ispeed);
+               ssh->got_pty = TRUE;
+           } else {
+               c_write_str(ssh, "Server refused to allocate pty\r\n");
+               ssh->editing = ssh->echoing = 1;
+           }
+       }
+    } else {
+       ssh->editing = ssh->echoing = 1;
+    }
+    sfree(s);
+    crFinishV;
+}
+
+static void ssh2_setup_env(struct ssh_channel *c, struct Packet *pktin,
+                          void *ctx)
+{
+    struct ssh2_setup_env_state {
+       int crLine;
+       int num_env, env_left, env_ok;
+    };
+    Ssh ssh = c->ssh;
+    struct Packet *pktout;
+    crStateP(ssh2_setup_env_state, ctx);
+
+    crBeginState;
+
+    /*
+     * Send environment variables.
+     * 
+     * Simplest thing here is to send all the requests at once, and
+     * then wait for a whole bunch of successes or failures.
+     */
+    s->num_env = 0;
+    if (ssh->mainchan && !ssh->ncmode) {
+       char *key, *val;
+
+       for (val = conf_get_str_strs(ssh->conf, CONF_environmt, NULL, &key);
+            val != NULL;
+            val = conf_get_str_strs(ssh->conf, CONF_environmt, key, &key)) {
+           pktout = ssh2_chanreq_init(ssh->mainchan, "env", ssh2_setup_env, s);
+           ssh2_pkt_addstring(pktout, key);
+           ssh2_pkt_addstring(pktout, val);
+           ssh2_pkt_send(ssh, pktout);
+
+           s->num_env++;
+       }
+       if (s->num_env)
+           logeventf(ssh, "Sent %d environment variables", s->num_env);
+    }
+
+    if (s->num_env) {
+       s->env_ok = 0;
+       s->env_left = s->num_env;
+
+       while (s->env_left > 0) {
+           crWaitUntilV(pktin);
+           if (!pktin) goto out;
+           if (pktin->type == SSH2_MSG_CHANNEL_SUCCESS)
+               s->env_ok++;
+           s->env_left--;
+       }
+
+       if (s->env_ok == s->num_env) {
+           logevent("All environment variables successfully set");
+       } else if (s->env_ok == 0) {
+           logevent("All environment variables refused");
+           c_write_str(ssh, "Server refused to set environment variables\r\n");
+       } else {
+           logeventf(ssh, "%d environment variables refused",
+                     s->num_env - s->env_ok);
+           c_write_str(ssh, "Server refused to set all environment variables\r\n");
+       }
+    }
+out:
+    sfree(s);
+    crFinishV;
+}
+
 /*
  * Handle the SSH-2 userauth and connection layers.
  */
@@ -7457,6 +7676,12 @@ static void ssh2_msg_authconn(Ssh ssh, struct Packet *pktin)
     do_ssh2_authconn(ssh, NULL, 0, pktin);
 }
 
+static void ssh2_response_authconn(struct ssh_channel *c, struct Packet *pktin,
+                                  void *ctx)
+{
+    do_ssh2_authconn(c->ssh, NULL, 0, pktin);
+}
+
 static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
                             struct Packet *pktin)
 {
@@ -7500,10 +7725,6 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        int siglen, retlen, len;
        char *q, *agentreq, *ret;
        int try_send;
-       int requested_x11;
-       int requested_agent;
-       int requested_tty;
-       int num_env, env_left, env_ok;
        struct Packet *pktout;
        Filename *keyfile;
 #ifndef NO_GSSAPI
@@ -7540,9 +7761,6 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     ssh->packet_dispatch[SSH2_MSG_CHANNEL_EXTENDED_DATA] = ssh2_msg_authconn;
     ssh->packet_dispatch[SSH2_MSG_CHANNEL_EOF] = ssh2_msg_authconn;
     ssh->packet_dispatch[SSH2_MSG_CHANNEL_CLOSE] = ssh2_msg_authconn;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_REQUEST] = ssh2_msg_authconn;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_authconn;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_authconn;
     
     s->done_service_req = FALSE;
     s->we_are_in = s->userauth_success = FALSE;
@@ -8999,6 +9217,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
        ssh2_msg_channel_request;
     ssh->packet_dispatch[SSH2_MSG_CHANNEL_OPEN] =
        ssh2_msg_channel_open;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_channel_response;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_channel_response;
+
 
     if (ssh->mainchan && conf_get_int(ssh->conf, CONF_ssh_simple)) {
        /*
@@ -9007,10 +9228,9 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
         * this one, so it's safe for it to advertise a very large
         * window and leave the flow control to TCP.
         */
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
-       ssh2_pkt_addstring(s->pktout, "simple@putty.projects.tartarus.org");
-       ssh2_pkt_addbool(s->pktout, 0); /* no reply */
+       s->pktout = ssh2_chanreq_init(ssh->mainchan,
+                                     "simple@putty.projects.tartarus.org",
+                                     NULL, NULL);
        ssh2_pkt_send(ssh, s->pktout);
     }
 
@@ -9020,200 +9240,29 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
     ssh_setup_portfwd(ssh, ssh->conf);
 
     /*
-     * Send the CHANNEL_REQUESTS for the main channel.  We send them all
-     * and then start looking for responses, so it's important that the
-     * sending and receiving code below it is kept in sync.
+     * Send the CHANNEL_REQUESTS for the main channel.  Each one is
+     * handled by its own little asynchronous co-routine.
      */
 
     /*
      * Potentially enable X11 forwarding.
      */
-    if (ssh->mainchan && !ssh->ncmode && conf_get_int(ssh->conf, CONF_x11_forward) &&
-       (ssh->x11disp = x11_setup_display(conf_get_str(ssh->conf, CONF_x11_display),
-                                         conf_get_int(ssh->conf, CONF_x11_auth), ssh->conf))) {
-       logevent("Requesting X11 forwarding");
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
-       ssh2_pkt_addstring(s->pktout, "x11-req");
-       ssh2_pkt_addbool(s->pktout, 1);        /* want reply */
-       ssh2_pkt_addbool(s->pktout, 0);        /* many connections */
-       ssh2_pkt_addstring(s->pktout, ssh->x11disp->remoteauthprotoname);
-       /*
-        * Note that while we blank the X authentication data here, we don't
-        * take any special action to blank the start of an X11 channel,
-        * so using MIT-MAGIC-COOKIE-1 and actually opening an X connection
-        * without having session blanking enabled is likely to leak your
-        * cookie into the log.
-        */
-       dont_log_password(ssh, s->pktout, PKTLOG_BLANK);
-       ssh2_pkt_addstring(s->pktout, ssh->x11disp->remoteauthdatastring);
-       end_log_omission(ssh, s->pktout);
-       ssh2_pkt_adduint32(s->pktout, ssh->x11disp->screennum);
-       ssh2_pkt_send(ssh, s->pktout);
-       s->requested_x11 = TRUE;
-    } else
-       s->requested_x11 = FALSE;
+    ssh2_maybe_setup_x11(ssh->mainchan, NULL, NULL);
 
     /*
      * Potentially enable agent forwarding.
      */
-    if (ssh->mainchan && !ssh->ncmode && conf_get_int(ssh->conf, CONF_agentfwd) && agent_exists()) {
-       logevent("Requesting OpenSSH-style agent forwarding");
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
-       ssh2_pkt_addstring(s->pktout, "auth-agent-req@openssh.com");
-       ssh2_pkt_addbool(s->pktout, 1);        /* want reply */
-       ssh2_pkt_send(ssh, s->pktout);
-       s->requested_agent = TRUE;
-    } else
-       s->requested_agent = FALSE;
+    ssh2_maybe_setup_agent(ssh->mainchan, NULL, NULL);
 
     /*
      * Now allocate a pty for the session.
      */
-    if (ssh->mainchan && !ssh->ncmode && !conf_get_int(ssh->conf, CONF_nopty)) {
-       /* Unpick the terminal-speed string. */
-       /* XXX perhaps we should allow no speeds to be sent. */
-        ssh->ospeed = 38400; ssh->ispeed = 38400; /* last-resort defaults */
-       sscanf(conf_get_str(ssh->conf, CONF_termspeed), "%d,%d", &ssh->ospeed, &ssh->ispeed);
-       /* Build the pty request. */
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid); /* recipient channel */
-       ssh2_pkt_addstring(s->pktout, "pty-req");
-       ssh2_pkt_addbool(s->pktout, 1);        /* want reply */
-       ssh2_pkt_addstring(s->pktout, conf_get_str(ssh->conf, CONF_termtype));
-       ssh2_pkt_adduint32(s->pktout, ssh->term_width);
-       ssh2_pkt_adduint32(s->pktout, ssh->term_height);
-       ssh2_pkt_adduint32(s->pktout, 0);              /* pixel width */
-       ssh2_pkt_adduint32(s->pktout, 0);              /* pixel height */
-       ssh2_pkt_addstring_start(s->pktout);
-       parse_ttymodes(ssh, ssh2_send_ttymode, (void *)s->pktout);
-       ssh2_pkt_addbyte(s->pktout, SSH2_TTY_OP_ISPEED);
-       ssh2_pkt_adduint32(s->pktout, ssh->ispeed);
-       ssh2_pkt_addbyte(s->pktout, SSH2_TTY_OP_OSPEED);
-       ssh2_pkt_adduint32(s->pktout, ssh->ospeed);
-       ssh2_pkt_addstring_data(s->pktout, "\0", 1); /* TTY_OP_END */
-       ssh2_pkt_send(ssh, s->pktout);
-       ssh->state = SSH_STATE_INTERMED;
-       s->requested_tty = TRUE;
-    } else
-       s->requested_tty = FALSE;
+    ssh2_maybe_setup_pty(ssh->mainchan, NULL, NULL);
 
     /*
      * Send environment variables.
-     * 
-     * Simplest thing here is to send all the requests at once, and
-     * then wait for a whole bunch of successes or failures.
-     */
-    s->num_env = 0;
-    if (ssh->mainchan && !ssh->ncmode) {
-       char *key, *val;
-
-       for (val = conf_get_str_strs(ssh->conf, CONF_environmt, NULL, &key);
-            val != NULL;
-            val = conf_get_str_strs(ssh->conf, CONF_environmt, key, &key)) {
-           s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-           ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid);
-           ssh2_pkt_addstring(s->pktout, "env");
-           ssh2_pkt_addbool(s->pktout, 1);            /* want reply */
-           ssh2_pkt_addstring(s->pktout, key);
-           ssh2_pkt_addstring(s->pktout, val);
-           ssh2_pkt_send(ssh, s->pktout);
-
-           s->num_env++;
-       }
-       if (s->num_env)
-           logeventf(ssh, "Sent %d environment variables", s->num_env);
-    }
-
-    /*
-     * All CHANNEL_REQUESTs sent.  Now collect up the replies.  These
-     * must be in precisely the same order as the requests.
      */
-
-    if (s->requested_x11) {
-       crWaitUntilV(pktin);
-
-       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));
-               crStopV;
-           }
-           logevent("X11 forwarding refused");
-       } else {
-           logevent("X11 forwarding enabled");
-           ssh->X11_fwd_enabled = TRUE;
-       }
-    }
-
-    if (s->requested_agent) {
-       crWaitUntilV(pktin);
-
-       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));
-               crStopV;
-           }
-           logevent("Agent forwarding refused");
-       } else {
-           logevent("Agent forwarding enabled");
-           ssh->agentfwd_enabled = TRUE;
-       }
-    }
-
-    if (s->requested_tty) {
-       crWaitUntilV(pktin);
-
-       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));
-               crStopV;
-           }
-           c_write_str(ssh, "Server refused to allocate pty\r\n");
-           ssh->editing = ssh->echoing = 1;
-       } else {
-           logeventf(ssh, "Allocated pty (ospeed %dbps, ispeed %dbps)",
-                     ssh->ospeed, ssh->ispeed);
-            ssh->got_pty = TRUE;
-       }
-    } else {
-       ssh->editing = ssh->echoing = 1;
-    }
-
-    if (s->num_env) {
-       s->env_ok = 0;
-       s->env_left = s->num_env;
-
-       while (s->env_left > 0) {
-           crWaitUntilV(pktin);
-
-           if (pktin->type != SSH2_MSG_CHANNEL_SUCCESS) {
-               if (pktin->type != SSH2_MSG_CHANNEL_FAILURE) {
-                   bombout(("Unexpected response to environment request:"
-                            " packet type %d", pktin->type));
-                   crStopV;
-               }
-           } else {
-               s->env_ok++;
-           }
-
-           s->env_left--;
-       }
-
-       if (s->env_ok == s->num_env) {
-           logevent("All environment variables successfully set");
-       } else if (s->env_ok == 0) {
-           logevent("All environment variables refused");
-           c_write_str(ssh, "Server refused to set environment variables\r\n");
-       } else {
-           logeventf(ssh, "%d environment variables refused",
-                     s->num_env - s->env_ok);
-           c_write_str(ssh, "Server refused to set all environment variables\r\n");
-       }
-    }
+    ssh2_setup_env(ssh->mainchan, NULL, NULL);
 
     /*
      * Start a shell or a remote command. We may have to attempt
@@ -9232,19 +9281,17 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
            cmd = conf_get_str(ssh->conf, CONF_remote_cmd);
        }
 
-       s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-       ssh2_pkt_adduint32(s->pktout, ssh->mainchan->remoteid); /* recipient channel */
        if (subsys) {
-           ssh2_pkt_addstring(s->pktout, "subsystem");
-           ssh2_pkt_addbool(s->pktout, 1);            /* want reply */
+           s->pktout = ssh2_chanreq_init(ssh->mainchan, "subsystem",
+                                         ssh2_response_authconn, NULL);
            ssh2_pkt_addstring(s->pktout, cmd);
        } else if (*cmd) {
-           ssh2_pkt_addstring(s->pktout, "exec");
-           ssh2_pkt_addbool(s->pktout, 1);            /* want reply */
+           s->pktout = ssh2_chanreq_init(ssh->mainchan, "exec",
+                                         ssh2_response_authconn, NULL);
            ssh2_pkt_addstring(s->pktout, cmd);
        } else {
-           ssh2_pkt_addstring(s->pktout, "shell");
-           ssh2_pkt_addbool(s->pktout, 1);            /* want reply */
+           s->pktout = ssh2_chanreq_init(ssh->mainchan, "shell",
+                                         ssh2_response_authconn, NULL);
        }
        ssh2_pkt_send(ssh, s->pktout);
 
@@ -9284,10 +9331,10 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 
     /*
      * All the initial channel requests are done, so install the default
-     * failure handler.
+     * response handler.
      */
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_channel_success;
-    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_channel_failure;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_SUCCESS] = ssh2_msg_channel_response;
+    ssh->packet_dispatch[SSH2_MSG_CHANNEL_FAILURE] = ssh2_msg_channel_response;
 
     /*
      * Transfer data!
@@ -9391,6 +9438,7 @@ static void ssh2_msg_unexpected(Ssh ssh, struct Packet *pktin)
                          ssh2_pkt_type(ssh->pkt_kctx, ssh->pkt_actx,
                                        pktin->type));
     ssh_disconnect(ssh, NULL, buf, SSH2_DISCONNECT_PROTOCOL_ERROR, FALSE);
+    sfree(buf);
 }
 
 static void ssh2_msg_something_unimplemented(Ssh ssh, struct Packet *pktin)
@@ -9686,6 +9734,17 @@ static void ssh_free(void *handle)
                    pfd_close(c->u.pfd.s);
                break;
            }
+           if (ssh->version == 2) {
+               struct outstanding_channel_request *ocr, *nocr;
+               ocr = c->v.v2.chanreq_head;
+               while (ocr) {
+                   ocr->handler(c, NULL, ocr->ctx);
+                   nocr = ocr->next;
+                   sfree(ocr);
+                   ocr = nocr;
+               }
+               bufchain_clear(&c->v.v2.outbuffer);
+           }
            sfree(c);
        }
        freetree234(ssh->channels);
@@ -9871,10 +9930,8 @@ static void ssh_size(void *handle, int width, int height)
                            PKT_INT, ssh->term_width,
                            PKT_INT, 0, PKT_INT, 0, PKT_END);
            } else if (ssh->mainchan) {
-               pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-               ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
-               ssh2_pkt_addstring(pktout, "window-change");
-               ssh2_pkt_addbool(pktout, 0);
+               pktout = ssh2_chanreq_init(ssh->mainchan, "window-change",
+                                          NULL, NULL);
                ssh2_pkt_adduint32(pktout, ssh->term_width);
                ssh2_pkt_adduint32(pktout, ssh->term_height);
                ssh2_pkt_adduint32(pktout, 0);
@@ -10010,10 +10067,7 @@ static void ssh_special(void *handle, Telnet_Special code)
        if (ssh->version == 1) {
            logevent("Unable to send BREAK signal in SSH-1");
        } else if (ssh->mainchan) {
-           pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-           ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
-           ssh2_pkt_addstring(pktout, "break");
-           ssh2_pkt_addbool(pktout, 0);
+           pktout = ssh2_chanreq_init(ssh->mainchan, "break", NULL, NULL);
            ssh2_pkt_adduint32(pktout, 0);   /* default break length */
            ssh2_pkt_send(ssh, pktout);
        }
@@ -10038,10 +10092,7 @@ static void ssh_special(void *handle, Telnet_Special code)
        if (signame) {
            /* It's a signal. */
            if (ssh->version == 2 && ssh->mainchan) {
-               pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_REQUEST);
-               ssh2_pkt_adduint32(pktout, ssh->mainchan->remoteid);
-               ssh2_pkt_addstring(pktout, "signal");
-               ssh2_pkt_addbool(pktout, 0);
+               pktout = ssh2_chanreq_init(ssh->mainchan, "signal", NULL, NULL);
                ssh2_pkt_addstring(pktout, signame);
                ssh2_pkt_send(ssh, pktout);
                logeventf(ssh, "Sent signal SIG%s", signame);