1 files changed, 1971 insertions, 1914 deletions

diff --git a/channels.c b/channels.c
index d030fcdd9..83442be06 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.357 2017/02/01 02:59:09 dtucker Exp $ */
+/* $OpenBSD: channels.c,v 1.375 2017/09/24 13:45:34 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -55,27 +55,27 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <limits.h>
 #include <netdb.h>
+#include <stdarg.h>
 #ifdef HAVE_STDINT_H
-#include <stdint.h>
+ #include <stdint.h>
 #endif
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <termios.h>
 #include <unistd.h>
-#include <stdarg.h>
 
 #include "openbsd-compat/sys-queue.h"
 #include "xmalloc.h"
 #include "ssh.h"
-#include "ssh1.h"
 #include "ssh2.h"
 #include "ssherr.h"
+#include "sshbuf.h"
 #include "packet.h"
 #include "log.h"
 #include "misc.h"
-#include "buffer.h"
 #include "channels.h"
 #include "compat.h"
 #include "canohost.h"
@@ -83,28 +83,19 @@
 #include "authfd.h"
 #include "pathnames.h"
 
-/* -- channel core */
-
-/*
- * Pointer to an array containing all allocated channels.  The array is
- * dynamically extended as needed.
- */
-static Channel **channels = NULL;
-
-/*
- * Size of the channel array.  All slots of the array must always be
- * initialized (at least the type field); unused slots set to NULL
- */
-static u_int channels_alloc = 0;
+/* -- agent forwarding */
+#define NUM_SOCKS       10
 
-/*
- * Maximum file descriptor value used in any of the channels.  This is
- * updated in channel_new.
- */
-static int channel_max_fd = 0;
+/* -- tcp forwarding */
+/* special-case port number meaning allow any port */
+#define FWD_PERMIT_ANY_PORT     0
 
+/* special-case wildcard meaning allow any host */
+#define FWD_PERMIT_ANY_HOST     "*"
 
-/* -- tcp forwarding */
+/* -- X11 forwarding */
+/* Maximum number of fake X11 displays to try. */
+#define MAX_DISPLAYS  1000
 
 /*
  * Data structure for storing which hosts are permitted for forward requests.
@@ -124,101 +115,153 @@ typedef struct {
         Channel *downstream;            /* Downstream mux*/
 } ForwardPermission;
 
-/* List of all permitted host/port pairs to connect by the user. */
-static ForwardPermission *permitted_opens = NULL;
-
-/* List of all permitted host/port pairs to connect by the admin. */
-static ForwardPermission *permitted_adm_opens = NULL;
+typedef void chan_fn(struct ssh *, Channel *c,
+    fd_set *readset, fd_set *writeset);
 
-/* Number of permitted host/port pairs in the array permitted by the user. */
-static int num_permitted_opens = 0;
+/* Master structure for channels state */
+struct ssh_channels {
+        /*
+         * Pointer to an array containing all allocated channels.  The array
+         * is dynamically extended as needed.
+         */
+        Channel **channels;
 
-/* Number of permitted host/port pair in the array permitted by the admin. */
-static int num_adm_permitted_opens = 0;
+        /*
+         * Size of the channel array.  All slots of the array must always be
+         * initialized (at least the type field); unused slots set to NULL
+         */
+        u_int channels_alloc;
 
-/* special-case port number meaning allow any port */
-#define FWD_PERMIT_ANY_PORT     0
+        /*
+         * Maximum file descriptor value used in any of the channels.  This is
+         * updated in channel_new.
+         */
+        int channel_max_fd;
 
-/* special-case wildcard meaning allow any host */
-#define FWD_PERMIT_ANY_HOST     "*"
+        /*
+         * 'channel_pre*' are called just before select() to add any bits
+         * relevant to channels in the select bitmasks.
+         *
+         * 'channel_post*': perform any appropriate operations for
+         * channels which have events pending.
+         */
+        chan_fn **channel_pre;
+        chan_fn **channel_post;
 
-/*
- * If this is true, all opens are permitted.  This is the case on the server
- * on which we have to trust the client anyway, and the user could do
- * anything after logging in anyway.
- */
-static int all_opens_permitted = 0;
+        /* -- tcp forwarding */
 
+        /* List of all permitted host/port pairs to connect by the user. */
+        ForwardPermission *permitted_opens;
 
-/* -- X11 forwarding */
+        /* List of all permitted host/port pairs to connect by the admin. */
+        ForwardPermission *permitted_adm_opens;
 
-/* Maximum number of fake X11 displays to try. */
-#define MAX_DISPLAYS  1000
+        /*
+         * Number of permitted host/port pairs in the array permitted by
+         * the user.
+         */
+        u_int num_permitted_opens;
 
-/* Saved X11 local (client) display. */
-static char *x11_saved_display = NULL;
+        /*
+         * Number of permitted host/port pair in the array permitted by
+         * the admin.
+         */
+        u_int num_adm_permitted_opens;
 
-/* Saved X11 authentication protocol name. */
-static char *x11_saved_proto = NULL;
+        /*
+         * If this is true, all opens are permitted.  This is the case on
+         * the server on which we have to trust the client anyway, and the
+         * user could do anything after logging in anyway.
+         */
+        int all_opens_permitted;
 
-/* Saved X11 authentication data.  This is the real data. */
-static char *x11_saved_data = NULL;
-static u_int x11_saved_data_len = 0;
+        /* -- X11 forwarding */
 
-/* Deadline after which all X11 connections are refused */
-static u_int x11_refuse_time;
+        /* Saved X11 local (client) display. */
+        char *x11_saved_display;
 
-/*
- * Fake X11 authentication data.  This is what the server will be sending us;
- * we should replace any occurrences of this by the real data.
- */
-static u_char *x11_fake_data = NULL;
-static u_int x11_fake_data_len;
+        /* Saved X11 authentication protocol name. */
+        char *x11_saved_proto;
 
+        /* Saved X11 authentication data.  This is the real data. */
+        char *x11_saved_data;
+        u_int x11_saved_data_len;
 
-/* -- agent forwarding */
+        /* Deadline after which all X11 connections are refused */
+        u_int x11_refuse_time;
 
-#define NUM_SOCKS       10
+        /*
+         * Fake X11 authentication data.  This is what the server will be
+         * sending us; we should replace any occurrences of this by the
+         * real data.
+         */
+        u_char *x11_fake_data;
+        u_int x11_fake_data_len;
 
-/* AF_UNSPEC or AF_INET or AF_INET6 */
-static int IPv4or6 = AF_UNSPEC;
+        /* AF_UNSPEC or AF_INET or AF_INET6 */
+        int IPv4or6;
+};
 
 /* helper */
-static void port_open_helper(Channel *c, char *rtype);
+static void port_open_helper(struct ssh *ssh, Channel *c, char *rtype);
 static const char *channel_rfwd_bind_host(const char *listen_host);
 
 /* non-blocking connect helpers */
 static int connect_next(struct channel_connect *);
 static void channel_connect_ctx_free(struct channel_connect *);
+static Channel *rdynamic_connect_prepare(struct ssh *, char *, char *);
+static int rdynamic_connect_finish(struct ssh *, Channel *);
+
+/* Setup helper */
+static void channel_handler_init(struct ssh_channels *sc);
 
 /* -- channel core */
 
+void
+channel_init_channels(struct ssh *ssh)
+{
+        struct ssh_channels *sc;
+
+        if ((sc = calloc(1, sizeof(*sc))) == NULL ||
+            (sc->channel_pre = calloc(SSH_CHANNEL_MAX_TYPE,
+            sizeof(*sc->channel_pre))) == NULL ||
+            (sc->channel_post = calloc(SSH_CHANNEL_MAX_TYPE,
+            sizeof(*sc->channel_post))) == NULL)
+                fatal("%s: allocation failed", __func__);
+        sc->channels_alloc = 10;
+        sc->channels = xcalloc(sc->channels_alloc, sizeof(*sc->channels));
+        sc->IPv4or6 = AF_UNSPEC;
+        channel_handler_init(sc);
+
+        ssh->chanctxt = sc;
+}
+
 Channel *
-channel_by_id(int id)
+channel_by_id(struct ssh *ssh, int id)
 {
         Channel *c;
 
-        if (id < 0 || (u_int)id >= channels_alloc) {
-                logit("channel_by_id: %d: bad id", id);
+        if (id < 0 || (u_int)id >= ssh->chanctxt->channels_alloc) {
+                logit("%s: %d: bad id", __func__, id);
                 return NULL;
         }
-        c = channels[id];
+        c = ssh->chanctxt->channels[id];
         if (c == NULL) {
-                logit("channel_by_id: %d: bad id: channel free", id);
+                logit("%s: %d: bad id: channel free", __func__, id);
                 return NULL;
         }
         return c;
 }
 
 Channel *
-channel_by_remote_id(int remote_id)
+channel_by_remote_id(struct ssh *ssh, u_int remote_id)
 {
         Channel *c;
         u_int i;
 
-        for (i = 0; i < channels_alloc; i++) {
-                c = channels[i];
-                if (c != NULL && c->remote_id == remote_id)
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                c = ssh->chanctxt->channels[i];
+                if (c != NULL && c->have_remote_id && c->remote_id == remote_id)
                         return c;
         }
         return NULL;
@@ -229,28 +272,28 @@ channel_by_remote_id(int remote_id)
  * Private channels, like listening sockets, may not receive messages.
  */
 Channel *
-channel_lookup(int id)
+channel_lookup(struct ssh *ssh, int id)
 {
         Channel *c;
 
-        if ((c = channel_by_id(id)) == NULL)
-                return (NULL);
+        if ((c = channel_by_id(ssh, id)) == NULL)
+                return NULL;
 
         switch (c->type) {
         case SSH_CHANNEL_X11_OPEN:
         case SSH_CHANNEL_LARVAL:
         case SSH_CHANNEL_CONNECTING:
         case SSH_CHANNEL_DYNAMIC:
+        case SSH_CHANNEL_RDYNAMIC_OPEN:
+        case SSH_CHANNEL_RDYNAMIC_FINISH:
         case SSH_CHANNEL_OPENING:
         case SSH_CHANNEL_OPEN:
-        case SSH_CHANNEL_INPUT_DRAINING:
-        case SSH_CHANNEL_OUTPUT_DRAINING:
         case SSH_CHANNEL_ABANDONED:
         case SSH_CHANNEL_MUX_PROXY:
-                return (c);
+                return c;
         }
         logit("Non-public channel %d, type %d.", id, c->type);
-        return (NULL);
+        return NULL;
 }
 
 /*
@@ -258,13 +301,15 @@ channel_lookup(int id)
  * when the channel consumer/producer is ready, e.g. shell exec'd
  */
 static void
-channel_register_fds(Channel *c, int rfd, int wfd, int efd,
+channel_register_fds(struct ssh *ssh, Channel *c, int rfd, int wfd, int efd,
     int extusage, int nonblock, int is_tty)
 {
+        struct ssh_channels *sc = ssh->chanctxt;
+
         /* Update the maximum file descriptor value. */
-        channel_max_fd = MAXIMUM(channel_max_fd, rfd);
-        channel_max_fd = MAXIMUM(channel_max_fd, wfd);
-        channel_max_fd = MAXIMUM(channel_max_fd, efd);
+        sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, rfd);
+        sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, wfd);
+        sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, efd);
 
         if (rfd != -1)
                 fcntl(rfd, F_SETFD, FD_CLOEXEC);
@@ -302,192 +347,220 @@ channel_register_fds(Channel *c, int rfd, int wfd, int efd,
  * remote_name to be freed.
  */
 Channel *
-channel_new(char *ctype, int type, int rfd, int wfd, int efd,
+channel_new(struct ssh *ssh, char *ctype, int type, int rfd, int wfd, int efd,
     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 {
-        int found;
-        u_int i;
+        struct ssh_channels *sc = ssh->chanctxt;
+        u_int i, found;
         Channel *c;
 
-        /* Do initial allocation if this is the first call. */
-        if (channels_alloc == 0) {
-                channels_alloc = 10;
-                channels = xcalloc(channels_alloc, sizeof(Channel *));
-                for (i = 0; i < channels_alloc; i++)
-                        channels[i] = NULL;
-        }
         /* Try to find a free slot where to put the new channel. */
-        for (found = -1, i = 0; i < channels_alloc; i++)
-                if (channels[i] == NULL) {
+        for (i = 0; i < sc->channels_alloc; i++) {
+                if (sc->channels[i] == NULL) {
                         /* Found a free slot. */
-                        found = (int)i;
+                        found = i;
                         break;
                 }
-        if (found < 0) {
-                /* There are no free slots.  Take last+1 slot and expand the array.  */
-                found = channels_alloc;
-                if (channels_alloc > 10000)
-                        fatal("channel_new: internal error: channels_alloc %d "
-                            "too big.", channels_alloc);
-                channels = xreallocarray(channels, channels_alloc + 10,
-                    sizeof(Channel *));
-                channels_alloc += 10;
-                debug2("channel: expanding %d", channels_alloc);
-                for (i = found; i < channels_alloc; i++)
-                        channels[i] = NULL;
+        }
+        if (i >= sc->channels_alloc) {
+                /*
+                 * There are no free slots. Take last+1 slot and expand
+                 * the array.
+                 */
+                found = sc->channels_alloc;
+                if (sc->channels_alloc > CHANNELS_MAX_CHANNELS)
+                        fatal("%s: internal error: channels_alloc %d too big",
+                            __func__, sc->channels_alloc);
+                sc->channels = xrecallocarray(sc->channels, sc->channels_alloc,
+                    sc->channels_alloc + 10, sizeof(*sc->channels));
+                sc->channels_alloc += 10;
+                debug2("channel: expanding %d", sc->channels_alloc);
         }
         /* Initialize and return new channel. */
-        c = channels[found] = xcalloc(1, sizeof(Channel));
-        buffer_init(&c->input);
-        buffer_init(&c->output);
-        buffer_init(&c->extended);
-        c->path = NULL;
-        c->listening_addr = NULL;
-        c->listening_port = 0;
+        c = sc->channels[found] = xcalloc(1, sizeof(Channel));
+        if ((c->input = sshbuf_new()) == NULL ||
+            (c->output = sshbuf_new()) == NULL ||
+            (c->extended = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
         c->ostate = CHAN_OUTPUT_OPEN;
         c->istate = CHAN_INPUT_OPEN;
-        c->flags = 0;
-        channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
-        c->notbefore = 0;
+        channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, 0);
         c->self = found;
         c->type = type;
         c->ctype = ctype;
         c->local_window = window;
         c->local_window_max = window;
-        c->local_consumed = 0;
         c->local_maxpacket = maxpack;
-        c->remote_id = -1;
         c->remote_name = xstrdup(remote_name);
-        c->remote_window = 0;
-        c->remote_maxpacket = 0;
-        c->force_drain = 0;
-        c->single_connection = 0;
-        c->detach_user = NULL;
-        c->detach_close = 0;
-        c->open_confirm = NULL;
-        c->open_confirm_ctx = NULL;
-        c->input_filter = NULL;
-        c->output_filter = NULL;
-        c->filter_ctx = NULL;
-        c->filter_cleanup = NULL;
         c->ctl_chan = -1;
-        c->mux_rcb = NULL;
-        c->mux_ctx = NULL;
-        c->mux_pause = 0;
         c->delayed = 1;         /* prevent call to channel_post handler */
         TAILQ_INIT(&c->status_confirms);
         debug("channel %d: new [%s]", found, remote_name);
         return c;
 }
 
-static int
-channel_find_maxfd(void)
+static void
+channel_find_maxfd(struct ssh_channels *sc)
 {
         u_int i;
         int max = 0;
         Channel *c;
 
-        for (i = 0; i < channels_alloc; i++) {
-                c = channels[i];
+        for (i = 0; i < sc->channels_alloc; i++) {
+                c = sc->channels[i];
                 if (c != NULL) {
                         max = MAXIMUM(max, c->rfd);
                         max = MAXIMUM(max, c->wfd);
                         max = MAXIMUM(max, c->efd);
                 }
         }
-        return max;
+        sc->channel_max_fd = max;
 }
 
 int
-channel_close_fd(int *fdp)
+channel_close_fd(struct ssh *ssh, int *fdp)
 {
+        struct ssh_channels *sc = ssh->chanctxt;
         int ret = 0, fd = *fdp;
 
         if (fd != -1) {
                 ret = close(fd);
                 *fdp = -1;
-                if (fd == channel_max_fd)
-                        channel_max_fd = channel_find_maxfd();
+                if (fd == sc->channel_max_fd)
+                        channel_find_maxfd(sc);
         }
         return ret;
 }
 
 /* Close all channel fd/socket. */
 static void
-channel_close_fds(Channel *c)
+channel_close_fds(struct ssh *ssh, Channel *c)
+{
+        channel_close_fd(ssh, &c->sock);
+        channel_close_fd(ssh, &c->rfd);
+        channel_close_fd(ssh, &c->wfd);
+        channel_close_fd(ssh, &c->efd);
+}
+
+static void
+fwd_perm_clear(ForwardPermission *fp)
 {
-        channel_close_fd(&c->sock);
-        channel_close_fd(&c->rfd);
-        channel_close_fd(&c->wfd);
-        channel_close_fd(&c->efd);
+        free(fp->host_to_connect);
+        free(fp->listen_host);
+        free(fp->listen_path);
+        bzero(fp, sizeof(*fp));
+}
+
+enum { FWDPERM_USER, FWDPERM_ADMIN };
+
+static int
+fwd_perm_list_add(struct ssh *ssh, int which,
+    const char *host_to_connect, int port_to_connect,
+    const char *listen_host, const char *listen_path, int listen_port,
+    Channel *downstream)
+{
+        ForwardPermission **fpl;
+        u_int n, *nfpl;
+
+        switch (which) {
+        case FWDPERM_USER:
+                fpl = &ssh->chanctxt->permitted_opens;
+                nfpl = &ssh->chanctxt->num_permitted_opens;
+                break;
+        case FWDPERM_ADMIN:
+                fpl = &ssh->chanctxt->permitted_adm_opens;
+                nfpl = &ssh->chanctxt->num_adm_permitted_opens;
+                break;
+        default:
+                fatal("%s: invalid list %d", __func__, which);
+        }
+
+        if (*nfpl >= INT_MAX)
+                fatal("%s: overflow", __func__);
+
+        *fpl = xrecallocarray(*fpl, *nfpl, *nfpl + 1, sizeof(**fpl));
+        n = (*nfpl)++;
+#define MAYBE_DUP(s) ((s == NULL) ? NULL : xstrdup(s))
+        (*fpl)[n].host_to_connect = MAYBE_DUP(host_to_connect);
+        (*fpl)[n].port_to_connect = port_to_connect;
+        (*fpl)[n].listen_host = MAYBE_DUP(listen_host);
+        (*fpl)[n].listen_path = MAYBE_DUP(listen_path);
+        (*fpl)[n].listen_port = listen_port;
+        (*fpl)[n].downstream = downstream;
+#undef MAYBE_DUP
+        return (int)n;
+}
+
+static void
+mux_remove_remote_forwardings(struct ssh *ssh, Channel *c)
+{
+        struct ssh_channels *sc = ssh->chanctxt;
+        ForwardPermission *fp;
+        int r;
+        u_int i;
+
+        for (i = 0; i < sc->num_permitted_opens; i++) {
+                fp = &sc->permitted_opens[i];
+                if (fp->downstream != c)
+                        continue;
+
+                /* cancel on the server, since mux client is gone */
+                debug("channel %d: cleanup remote forward for %s:%u",
+                    c->self, fp->listen_host, fp->listen_port);
+                if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh,
+                    "cancel-tcpip-forward")) != 0 ||
+                    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh,
+                    channel_rfwd_bind_host(fp->listen_host))) != 0 ||
+                    (r = sshpkt_put_u32(ssh, fp->listen_port)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0) {
+                        fatal("%s: channel %i: %s", __func__,
+                            c->self, ssh_err(r));
+                }
+                fwd_perm_clear(fp); /* unregister */
+        }
 }
 
 /* Free the channel and close its fd/socket. */
 void
-channel_free(Channel *c)
+channel_free(struct ssh *ssh, Channel *c)
 {
+        struct ssh_channels *sc = ssh->chanctxt;
         char *s;
         u_int i, n;
         Channel *other;
         struct channel_confirm *cc;
 
-        for (n = 0, i = 0; i < channels_alloc; i++) {
-                if ((other = channels[i]) != NULL) {
-                        n++;
-
-                        /* detach from mux client and prepare for closing */
-                        if (c->type == SSH_CHANNEL_MUX_CLIENT &&
-                            other->type == SSH_CHANNEL_MUX_PROXY &&
-                            other->mux_ctx == c) {
-                                other->mux_ctx = NULL;
-                                other->type = SSH_CHANNEL_OPEN;
-                                other->istate = CHAN_INPUT_CLOSED;
-                                other->ostate = CHAN_OUTPUT_CLOSED;
-                        }
+        for (n = 0, i = 0; i < sc->channels_alloc; i++) {
+                if ((other = sc->channels[i]) == NULL)
+                        continue;
+                n++;
+                /* detach from mux client and prepare for closing */
+                if (c->type == SSH_CHANNEL_MUX_CLIENT &&
+                    other->type == SSH_CHANNEL_MUX_PROXY &&
+                    other->mux_ctx == c) {
+                        other->mux_ctx = NULL;
+                        other->type = SSH_CHANNEL_OPEN;
+                        other->istate = CHAN_INPUT_CLOSED;
+                        other->ostate = CHAN_OUTPUT_CLOSED;
                 }
         }
         debug("channel %d: free: %s, nchannels %u", c->self,
             c->remote_name ? c->remote_name : "???", n);
 
-        /* XXX more MUX cleanup: remove remote forwardings */
-        if (c->type == SSH_CHANNEL_MUX_CLIENT) {
-                for (i = 0; i < (u_int)num_permitted_opens; i++) {
-                        if (permitted_opens[i].downstream != c)
-                                continue;
-                        /* cancel on the server, since mux client is gone */
-                        debug("channel %d: cleanup remote forward for %s:%u",
-                            c->self,
-                            permitted_opens[i].listen_host,
-                            permitted_opens[i].listen_port);
-                        packet_start(SSH2_MSG_GLOBAL_REQUEST);
-                        packet_put_cstring("cancel-tcpip-forward");
-                        packet_put_char(0);
-                        packet_put_cstring(channel_rfwd_bind_host(
-                            permitted_opens[i].listen_host));
-                        packet_put_int(permitted_opens[i].listen_port);
-                        packet_send();
-                        /* unregister */
-                        permitted_opens[i].listen_port = 0;
-                        permitted_opens[i].port_to_connect = 0;
-                        free(permitted_opens[i].host_to_connect);
-                        permitted_opens[i].host_to_connect = NULL;
-                        free(permitted_opens[i].listen_host);
-                        permitted_opens[i].listen_host = NULL;
-                        permitted_opens[i].listen_path = NULL;
-                        permitted_opens[i].downstream = NULL;
-                }
-        }
+        if (c->type == SSH_CHANNEL_MUX_CLIENT)
+                mux_remove_remote_forwardings(ssh, c);
 
-        s = channel_open_message();
+        s = channel_open_message(ssh);
         debug3("channel %d: status: %s", c->self, s);
         free(s);
 
-        if (c->sock != -1)
-                shutdown(c->sock, SHUT_RDWR);
-        channel_close_fds(c);
-        buffer_free(&c->input);
-        buffer_free(&c->output);
-        buffer_free(&c->extended);
+        channel_close_fds(ssh, c);
+        sshbuf_free(c->input);
+        sshbuf_free(c->output);
+        sshbuf_free(c->extended);
+        c->input = c->output = c->extended = NULL;
         free(c->remote_name);
         c->remote_name = NULL;
         free(c->path);
@@ -496,25 +569,26 @@ channel_free(Channel *c)
         c->listening_addr = NULL;
         while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
                 if (cc->abandon_cb != NULL)
-                        cc->abandon_cb(c, cc->ctx);
+                        cc->abandon_cb(ssh, c, cc->ctx);
                 TAILQ_REMOVE(&c->status_confirms, cc, entry);
                 explicit_bzero(cc, sizeof(*cc));
                 free(cc);
         }
         if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
-                c->filter_cleanup(c->self, c->filter_ctx);
-        channels[c->self] = NULL;
+                c->filter_cleanup(ssh, c->self, c->filter_ctx);
+        sc->channels[c->self] = NULL;
+        explicit_bzero(c, sizeof(*c));
         free(c);
 }
 
 void
-channel_free_all(void)
+channel_free_all(struct ssh *ssh)
 {
         u_int i;
 
-        for (i = 0; i < channels_alloc; i++)
-                if (channels[i] != NULL)
-                        channel_free(channels[i]);
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++)
+                if (ssh->chanctxt->channels[i] != NULL)
+                        channel_free(ssh, ssh->chanctxt->channels[i]);
 }
 
 /*
@@ -522,26 +596,26 @@ channel_free_all(void)
  * descriptors after a fork.
  */
 void
-channel_close_all(void)
+channel_close_all(struct ssh *ssh)
 {
         u_int i;
 
-        for (i = 0; i < channels_alloc; i++)
-                if (channels[i] != NULL)
-                        channel_close_fds(channels[i]);
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++)
+                if (ssh->chanctxt->channels[i] != NULL)
+                        channel_close_fds(ssh, ssh->chanctxt->channels[i]);
 }
 
 /*
  * Stop listening to channels.
  */
 void
-channel_stop_listening(void)
+channel_stop_listening(struct ssh *ssh)
 {
         u_int i;
         Channel *c;
 
-        for (i = 0; i < channels_alloc; i++) {
-                c = channels[i];
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                c = ssh->chanctxt->channels[i];
                 if (c != NULL) {
                         switch (c->type) {
                         case SSH_CHANNEL_AUTH_SOCKET:
@@ -550,8 +624,8 @@ channel_stop_listening(void)
                         case SSH_CHANNEL_X11_LISTENER:
                         case SSH_CHANNEL_UNIX_LISTENER:
                         case SSH_CHANNEL_RUNIX_LISTENER:
-                                channel_close_fd(&c->sock);
-                                channel_free(c);
+                                channel_close_fd(ssh, &c->sock);
+                                channel_free(ssh, c);
                                 break;
                         }
                 }
@@ -563,28 +637,20 @@ channel_stop_listening(void)
  * more channel is overfull.
  */
 int
-channel_not_very_much_buffered_data(void)
+channel_not_very_much_buffered_data(struct ssh *ssh)
 {
         u_int i;
+        u_int maxsize = ssh_packet_get_maxsize(ssh);
         Channel *c;
 
-        for (i = 0; i < channels_alloc; i++) {
-                c = channels[i];
-                if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
-#if 0
-                        if (!compat20 &&
-                            buffer_len(&c->input) > packet_get_maxsize()) {
-                                debug2("channel %d: big input buffer %d",
-                                    c->self, buffer_len(&c->input));
-                                return 0;
-                        }
-#endif
-                        if (buffer_len(&c->output) > packet_get_maxsize()) {
-                                debug2("channel %d: big output buffer %u > %u",
-                                    c->self, buffer_len(&c->output),
-                                    packet_get_maxsize());
-                                return 0;
-                        }
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                c = ssh->chanctxt->channels[i];
+                if (c == NULL || c->type != SSH_CHANNEL_OPEN)
+                        continue;
+                if (sshbuf_len(c->output) > maxsize) {
+                        debug2("channel %d: big output buffer %zu > %u",
+                            c->self, sshbuf_len(c->output), maxsize);
+                        return 0;
                 }
         }
         return 1;
@@ -592,13 +658,13 @@ channel_not_very_much_buffered_data(void)
 
 /* Returns true if any channel is still open. */
 int
-channel_still_open(void)
+channel_still_open(struct ssh *ssh)
 {
         u_int i;
         Channel *c;
 
-        for (i = 0; i < channels_alloc; i++) {
-                c = channels[i];
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                c = ssh->chanctxt->channels[i];
                 if (c == NULL)
                         continue;
                 switch (c->type) {
@@ -609,6 +675,7 @@ channel_still_open(void)
                 case SSH_CHANNEL_CLOSED:
                 case SSH_CHANNEL_AUTH_SOCKET:
                 case SSH_CHANNEL_DYNAMIC:
+                case SSH_CHANNEL_RDYNAMIC_OPEN:
                 case SSH_CHANNEL_CONNECTING:
                 case SSH_CHANNEL_ZOMBIE:
                 case SSH_CHANNEL_ABANDONED:
@@ -616,22 +683,16 @@ channel_still_open(void)
                 case SSH_CHANNEL_RUNIX_LISTENER:
                         continue;
                 case SSH_CHANNEL_LARVAL:
-                        if (!compat20)
-                                fatal("cannot happen: SSH_CHANNEL_LARVAL");
                         continue;
                 case SSH_CHANNEL_OPENING:
                 case SSH_CHANNEL_OPEN:
+                case SSH_CHANNEL_RDYNAMIC_FINISH:
                 case SSH_CHANNEL_X11_OPEN:
                 case SSH_CHANNEL_MUX_CLIENT:
                 case SSH_CHANNEL_MUX_PROXY:
                         return 1;
-                case SSH_CHANNEL_INPUT_DRAINING:
-                case SSH_CHANNEL_OUTPUT_DRAINING:
-                        if (!compat13)
-                                fatal("cannot happen: OUT_DRAIN");
-                        return 1;
                 default:
-                        fatal("channel_still_open: bad channel type %d", c->type);
+                        fatal("%s: bad channel type %d", __func__, c->type);
                         /* NOTREACHED */
                 }
         }
@@ -640,18 +701,20 @@ channel_still_open(void)
 
 /* Returns the id of an open channel suitable for keepaliving */
 int
-channel_find_open(void)
+channel_find_open(struct ssh *ssh)
 {
         u_int i;
         Channel *c;
 
-        for (i = 0; i < channels_alloc; i++) {
-                c = channels[i];
-                if (c == NULL || c->remote_id < 0)
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                c = ssh->chanctxt->channels[i];
+                if (c == NULL || !c->have_remote_id)
                         continue;
                 switch (c->type) {
                 case SSH_CHANNEL_CLOSED:
                 case SSH_CHANNEL_DYNAMIC:
+                case SSH_CHANNEL_RDYNAMIC_OPEN:
+                case SSH_CHANNEL_RDYNAMIC_FINISH:
                 case SSH_CHANNEL_X11_LISTENER:
                 case SSH_CHANNEL_PORT_LISTENER:
                 case SSH_CHANNEL_RPORT_LISTENER:
@@ -670,13 +733,8 @@ channel_find_open(void)
                 case SSH_CHANNEL_OPEN:
                 case SSH_CHANNEL_X11_OPEN:
                         return i;
-                case SSH_CHANNEL_INPUT_DRAINING:
-                case SSH_CHANNEL_OUTPUT_DRAINING:
-                        if (!compat13)
-                                fatal("cannot happen: OUT_DRAIN");
-                        return i;
                 default:
-                        fatal("channel_find_open: bad channel type %d", c->type);
+                        fatal("%s: bad channel type %d", __func__, c->type);
                         /* NOTREACHED */
                 }
         }
@@ -689,18 +747,21 @@ channel_find_open(void)
  * newlines.
  */
 char *
-channel_open_message(void)
+channel_open_message(struct ssh *ssh)
 {
-        Buffer buffer;
+        struct sshbuf *buf;
         Channel *c;
-        char buf[1024], *cp;
         u_int i;
-
-        buffer_init(&buffer);
-        snprintf(buf, sizeof buf, "The following connections are open:\r\n");
-        buffer_append(&buffer, buf, strlen(buf));
-        for (i = 0; i < channels_alloc; i++) {
-                c = channels[i];
+        int r;
+        char *ret;
+
+        if ((buf = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new", __func__);
+        if ((r = sshbuf_putf(buf,
+            "The following connections are open:\r\n")) != 0)
+                fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r));
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                c = ssh->chanctxt->channels[i];
                 if (c == NULL)
                         continue;
                 switch (c->type) {
@@ -719,75 +780,95 @@ channel_open_message(void)
                 case SSH_CHANNEL_OPENING:
                 case SSH_CHANNEL_CONNECTING:
                 case SSH_CHANNEL_DYNAMIC:
+                case SSH_CHANNEL_RDYNAMIC_OPEN:
+                case SSH_CHANNEL_RDYNAMIC_FINISH:
                 case SSH_CHANNEL_OPEN:
                 case SSH_CHANNEL_X11_OPEN:
-                case SSH_CHANNEL_INPUT_DRAINING:
-                case SSH_CHANNEL_OUTPUT_DRAINING:
                 case SSH_CHANNEL_MUX_PROXY:
                 case SSH_CHANNEL_MUX_CLIENT:
-                        snprintf(buf, sizeof buf,
-                            "  #%d %.300s (t%d r%d i%u/%d o%u/%d fd %d/%d cc %d)\r\n",
+                        if ((r = sshbuf_putf(buf, "  #%d %.300s "
+                            "(t%d %s%u i%u/%zu o%u/%zu fd %d/%d cc %d)\r\n",
                             c->self, c->remote_name,
-                            c->type, c->remote_id,
-                            c->istate, buffer_len(&c->input),
-                            c->ostate, buffer_len(&c->output),
-                            c->rfd, c->wfd, c->ctl_chan);
-                        buffer_append(&buffer, buf, strlen(buf));
+                            c->type,
+                            c->have_remote_id ? "r" : "nr", c->remote_id,
+                            c->istate, sshbuf_len(c->input),
+                            c->ostate, sshbuf_len(c->output),
+                            c->rfd, c->wfd, c->ctl_chan)) != 0)
+                                fatal("%s: sshbuf_putf: %s",
+                                    __func__, ssh_err(r));
                         continue;
                 default:
-                        fatal("channel_open_message: bad channel type %d", c->type);
+                        fatal("%s: bad channel type %d", __func__, c->type);
                         /* NOTREACHED */
                 }
         }
-        buffer_append(&buffer, "\0", 1);
-        cp = xstrdup((char *)buffer_ptr(&buffer));
-        buffer_free(&buffer);
-        return cp;
+        if ((ret = sshbuf_dup_string(buf)) == NULL)
+                fatal("%s: sshbuf_dup_string", __func__);
+        sshbuf_free(buf);
+        return ret;
+}
+
+static void
+open_preamble(struct ssh *ssh, const char *where, Channel *c, const char *type)
+{
+        int r;
+
+        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
+            (r = sshpkt_put_cstring(ssh, type)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0) {
+                fatal("%s: channel %i: open: %s", where, c->self, ssh_err(r));
+        }
 }
 
 void
-channel_send_open(int id)
+channel_send_open(struct ssh *ssh, int id)
 {
-        Channel *c = channel_lookup(id);
+        Channel *c = channel_lookup(ssh, id);
+        int r;
 
         if (c == NULL) {
                 logit("channel_send_open: %d: bad id", id);
                 return;
         }
         debug2("channel %d: send open", id);
-        packet_start(SSH2_MSG_CHANNEL_OPEN);
-        packet_put_cstring(c->ctype);
-        packet_put_int(c->self);
-        packet_put_int(c->local_window);
-        packet_put_int(c->local_maxpacket);
-        packet_send();
+        open_preamble(ssh, __func__, c, c->ctype);
+        if ((r = sshpkt_send(ssh)) != 0)
+                fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
 }
 
 void
-channel_request_start(int id, char *service, int wantconfirm)
+channel_request_start(struct ssh *ssh, int id, char *service, int wantconfirm)
 {
-        Channel *c = channel_lookup(id);
+        Channel *c = channel_lookup(ssh, id);
+        int r;
 
         if (c == NULL) {
-                logit("channel_request_start: %d: unknown channel id", id);
+                logit("%s: %d: unknown channel id", __func__, id);
                 return;
         }
+        if (!c->have_remote_id)
+                fatal(":%s: channel %d: no remote id", __func__, c->self);
+
         debug2("channel %d: request %s confirm %d", id, service, wantconfirm);
-        packet_start(SSH2_MSG_CHANNEL_REQUEST);
-        packet_put_int(c->remote_id);
-        packet_put_cstring(service);
-        packet_put_char(wantconfirm);
+        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+            (r = sshpkt_put_cstring(ssh, service)) != 0 ||
+            (r = sshpkt_put_u8(ssh, wantconfirm)) != 0) {
+                fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
+        }
 }
 
 void
-channel_register_status_confirm(int id, channel_confirm_cb *cb,
-    channel_confirm_abandon_cb *abandon_cb, void *ctx)
+channel_register_status_confirm(struct ssh *ssh, int id,
+    channel_confirm_cb *cb, channel_confirm_abandon_cb *abandon_cb, void *ctx)
 {
         struct channel_confirm *cc;
         Channel *c;
 
-        if ((c = channel_lookup(id)) == NULL)
-                fatal("channel_register_expect: %d: bad id", id);
+        if ((c = channel_lookup(ssh, id)) == NULL)
+                fatal("%s: %d: bad id", __func__, id);
 
         cc = xcalloc(1, sizeof(*cc));
         cc->cb = cb;
@@ -797,12 +878,13 @@ channel_register_status_confirm(int id, channel_confirm_cb *cb,
 }
 
 void
-channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
+channel_register_open_confirm(struct ssh *ssh, int id,
+    channel_open_fn *fn, void *ctx)
 {
-        Channel *c = channel_lookup(id);
+        Channel *c = channel_lookup(ssh, id);
 
         if (c == NULL) {
-                logit("channel_register_open_confirm: %d: bad id", id);
+                logit("%s: %d: bad id", __func__, id);
                 return;
         }
         c->open_confirm = fn;
@@ -810,12 +892,13 @@ channel_register_open_confirm(int id, channel_open_fn *fn, void *ctx)
 }
 
 void
-channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
+channel_register_cleanup(struct ssh *ssh, int id,
+    channel_callback_fn *fn, int do_close)
 {
-        Channel *c = channel_by_id(id);
+        Channel *c = channel_by_id(ssh, id);
 
         if (c == NULL) {
-                logit("channel_register_cleanup: %d: bad id", id);
+                logit("%s: %d: bad id", __func__, id);
                 return;
         }
         c->detach_user = fn;
@@ -823,12 +906,12 @@ channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
 }
 
 void
-channel_cancel_cleanup(int id)
+channel_cancel_cleanup(struct ssh *ssh, int id)
 {
-        Channel *c = channel_by_id(id);
+        Channel *c = channel_by_id(ssh, id);
 
         if (c == NULL) {
-                logit("channel_cancel_cleanup: %d: bad id", id);
+                logit("%s: %d: bad id", __func__, id);
                 return;
         }
         c->detach_user = NULL;
@@ -836,13 +919,13 @@ channel_cancel_cleanup(int id)
 }
 
 void
-channel_register_filter(int id, channel_infilter_fn *ifn,
+channel_register_filter(struct ssh *ssh, int id, channel_infilter_fn *ifn,
     channel_outfilter_fn *ofn, channel_filter_cleanup_fn *cfn, void *ctx)
 {
-        Channel *c = channel_lookup(id);
+        Channel *c = channel_lookup(ssh, id);
 
         if (c == NULL) {
-                logit("channel_register_filter: %d: bad id", id);
+                logit("%s: %d: bad id", __func__, id);
                 return;
         }
         c->input_filter = ifn;
@@ -852,118 +935,80 @@ channel_register_filter(int id, channel_infilter_fn *ifn,
 }
 
 void
-channel_set_fds(int id, int rfd, int wfd, int efd,
+channel_set_fds(struct ssh *ssh, int id, int rfd, int wfd, int efd,
     int extusage, int nonblock, int is_tty, u_int window_max)
 {
-        Channel *c = channel_lookup(id);
+        Channel *c = channel_lookup(ssh, id);
+        int r;
 
         if (c == NULL || c->type != SSH_CHANNEL_LARVAL)
                 fatal("channel_activate for non-larval channel %d.", id);
-        channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, is_tty);
+        if (!c->have_remote_id)
+                fatal(":%s: channel %d: no remote id", __func__, c->self);
+
+        channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, is_tty);
         c->type = SSH_CHANNEL_OPEN;
         c->local_window = c->local_window_max = window_max;
-        packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-        packet_put_int(c->remote_id);
-        packet_put_int(c->local_window);
-        packet_send();
-}
 
-/*
- * 'channel_pre*' are called just before select() to add any bits relevant to
- * channels in the select bitmasks.
- */
-/*
- * 'channel_post*': perform any appropriate operations for channels which
- * have events pending.
- */
-typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
-chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
-chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
+        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_WINDOW_ADJUST)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0)
+                fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
+}
 
-/* ARGSUSED */
 static void
-channel_pre_listener(Channel *c, fd_set *readset, fd_set *writeset)
+channel_pre_listener(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         FD_SET(c->sock, readset);
 }
 
-/* ARGSUSED */
 static void
-channel_pre_connecting(Channel *c, fd_set *readset, fd_set *writeset)
+channel_pre_connecting(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         debug3("channel %d: waiting for connection", c->self);
         FD_SET(c->sock, writeset);
 }
 
 static void
-channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
+channel_pre_open(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
-        if (buffer_len(&c->input) < packet_get_maxsize())
-                FD_SET(c->sock, readset);
-        if (buffer_len(&c->output) > 0)
-                FD_SET(c->sock, writeset);
-}
-
-static void
-channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
-{
-        u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
-
         if (c->istate == CHAN_INPUT_OPEN &&
-            limit > 0 &&
-            buffer_len(&c->input) < limit &&
-            buffer_check_alloc(&c->input, CHAN_RBUF))
+            c->remote_window > 0 &&
+            sshbuf_len(c->input) < c->remote_window &&
+            sshbuf_check_reserve(c->input, CHAN_RBUF) == 0)
                 FD_SET(c->rfd, readset);
         if (c->ostate == CHAN_OUTPUT_OPEN ||
             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
-                if (buffer_len(&c->output) > 0) {
+                if (sshbuf_len(c->output) > 0) {
                         FD_SET(c->wfd, writeset);
                 } else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
                         if (CHANNEL_EFD_OUTPUT_ACTIVE(c))
-                                debug2("channel %d: obuf_empty delayed efd %d/(%d)",
-                                    c->self, c->efd, buffer_len(&c->extended));
+                                debug2("channel %d: "
+                                    "obuf_empty delayed efd %d/(%zu)", c->self,
+                                    c->efd, sshbuf_len(c->extended));
                         else
-                                chan_obuf_empty(c);
+                                chan_obuf_empty(ssh, c);
                 }
         }
         /** XXX check close conditions, too */
-        if (compat20 && c->efd != -1 && 
-            !(c->istate == CHAN_INPUT_CLOSED && c->ostate == CHAN_OUTPUT_CLOSED)) {
+        if (c->efd != -1 && !(c->istate == CHAN_INPUT_CLOSED &&
+            c->ostate == CHAN_OUTPUT_CLOSED)) {
                 if (c->extended_usage == CHAN_EXTENDED_WRITE &&
-                    buffer_len(&c->extended) > 0)
+                    sshbuf_len(c->extended) > 0)
                         FD_SET(c->efd, writeset);
                 else if (c->efd != -1 && !(c->flags & CHAN_EOF_SENT) &&
                     (c->extended_usage == CHAN_EXTENDED_READ ||
                     c->extended_usage == CHAN_EXTENDED_IGNORE) &&
-                    buffer_len(&c->extended) < c->remote_window)
+                    sshbuf_len(c->extended) < c->remote_window)
                         FD_SET(c->efd, readset);
         }
         /* XXX: What about efd? races? */
 }
 
-/* ARGSUSED */
-static void
-channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
-{
-        if (buffer_len(&c->input) == 0) {
-                packet_start(SSH_MSG_CHANNEL_CLOSE);
-                packet_put_int(c->remote_id);
-                packet_send();
-                c->type = SSH_CHANNEL_CLOSED;
-                debug2("channel %d: closing after input drain.", c->self);
-        }
-}
-
-/* ARGSUSED */
-static void
-channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
-{
-        if (buffer_len(&c->output) == 0)
-                chan_mark_dead(c);
-        else
-                FD_SET(c->sock, writeset);
-}
-
 /*
  * This is a special state for X11 authentication spoofing.  An opened X11
  * connection (when authentication spoofing is being done) remains in this
@@ -974,24 +1019,26 @@ channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
  */
 static int
-x11_open_helper(Buffer *b)
+x11_open_helper(struct ssh *ssh, struct sshbuf *b)
 {
+        struct ssh_channels *sc = ssh->chanctxt;
         u_char *ucp;
         u_int proto_len, data_len;
 
         /* Is this being called after the refusal deadline? */
-        if (x11_refuse_time != 0 && (u_int)monotime() >= x11_refuse_time) {
+        if (sc->x11_refuse_time != 0 &&
+            (u_int)monotime() >= sc->x11_refuse_time) {
                 verbose("Rejected X11 connection after ForwardX11Timeout "
                     "expired");
                 return -1;
         }
 
         /* Check if the fixed size part of the packet is in buffer. */
-        if (buffer_len(b) < 12)
+        if (sshbuf_len(b) < 12)
                 return 0;
 
         /* Parse the lengths of variable-length fields. */
-        ucp = buffer_ptr(b);
+        ucp = sshbuf_mutable_ptr(b);
         if (ucp[0] == 0x42) {   /* Byte order MSB first. */
                 proto_len = 256 * ucp[6] + ucp[7];
                 data_len = 256 * ucp[8] + ucp[9];
@@ -1005,27 +1052,27 @@ x11_open_helper(Buffer *b)
         }
 
         /* Check if the whole packet is in buffer. */
-        if (buffer_len(b) <
+        if (sshbuf_len(b) <
             12 + ((proto_len + 3) & ~3) + ((data_len + 3) & ~3))
                 return 0;
 
         /* Check if authentication protocol matches. */
-        if (proto_len != strlen(x11_saved_proto) ||
-            memcmp(ucp + 12, x11_saved_proto, proto_len) != 0) {
+        if (proto_len != strlen(sc->x11_saved_proto) ||
+            memcmp(ucp + 12, sc->x11_saved_proto, proto_len) != 0) {
                 debug2("X11 connection uses different authentication protocol.");
                 return -1;
         }
         /* Check if authentication data matches our fake data. */
-        if (data_len != x11_fake_data_len ||
+        if (data_len != sc->x11_fake_data_len ||
             timingsafe_bcmp(ucp + 12 + ((proto_len + 3) & ~3),
-                x11_fake_data, x11_fake_data_len) != 0) {
+                sc->x11_fake_data, sc->x11_fake_data_len) != 0) {
                 debug2("X11 auth data does not match fake data.");
                 return -1;
         }
         /* Check fake data length */
-        if (x11_fake_data_len != x11_saved_data_len) {
+        if (sc->x11_fake_data_len != sc->x11_saved_data_len) {
                 error("X11 fake_data_len %d != saved_data_len %d",
-                    x11_fake_data_len, x11_saved_data_len);
+                    sc->x11_fake_data_len, sc->x11_saved_data_len);
                 return -1;
         }
         /*
@@ -1034,90 +1081,63 @@ x11_open_helper(Buffer *b)
          * data.
          */
         memcpy(ucp + 12 + ((proto_len + 3) & ~3),
-            x11_saved_data, x11_saved_data_len);
+            sc->x11_saved_data, sc->x11_saved_data_len);
         return 1;
 }
 
 static void
-channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
+channel_pre_x11_open(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
-        int ret = x11_open_helper(&c->output);
-
-        if (ret == 1) {
-                /* Start normal processing for the channel. */
-                c->type = SSH_CHANNEL_OPEN;
-                channel_pre_open_13(c, readset, writeset);
-        } else if (ret == -1) {
-                /*
-                 * We have received an X11 connection that has bad
-                 * authentication information.
-                 */
-                logit("X11 connection rejected because of wrong authentication.");
-                buffer_clear(&c->input);
-                buffer_clear(&c->output);
-                channel_close_fd(&c->sock);
-                c->sock = -1;
-                c->type = SSH_CHANNEL_CLOSED;
-                packet_start(SSH_MSG_CHANNEL_CLOSE);
-                packet_put_int(c->remote_id);
-                packet_send();
-        }
-}
-
-static void
-channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
-{
-        int ret = x11_open_helper(&c->output);
+        int ret = x11_open_helper(ssh, c->output);
 
         /* c->force_drain = 1; */
 
         if (ret == 1) {
                 c->type = SSH_CHANNEL_OPEN;
-                channel_pre_open(c, readset, writeset);
+                channel_pre_open(ssh, c, readset, writeset);
         } else if (ret == -1) {
                 logit("X11 connection rejected because of wrong authentication.");
-                debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
-                chan_read_failed(c);
-                buffer_clear(&c->input);
-                chan_ibuf_empty(c);
-                buffer_clear(&c->output);
-                /* for proto v1, the peer will send an IEOF */
-                if (compat20)
-                        chan_write_failed(c);
-                else
-                        c->type = SSH_CHANNEL_OPEN;
+                debug2("X11 rejected %d i%d/o%d",
+                    c->self, c->istate, c->ostate);
+                chan_read_failed(ssh, c);
+                sshbuf_reset(c->input);
+                chan_ibuf_empty(ssh, c);
+                sshbuf_reset(c->output);
+                chan_write_failed(ssh, c);
                 debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
         }
 }
 
 static void
-channel_pre_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
+channel_pre_mux_client(struct ssh *ssh,
+    Channel *c, fd_set *readset, fd_set *writeset)
 {
         if (c->istate == CHAN_INPUT_OPEN && !c->mux_pause &&
-            buffer_check_alloc(&c->input, CHAN_RBUF))
+            sshbuf_check_reserve(c->input, CHAN_RBUF) == 0)
                 FD_SET(c->rfd, readset);
         if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
                 /* clear buffer immediately (discard any partial packet) */
-                buffer_clear(&c->input);
-                chan_ibuf_empty(c);
+                sshbuf_reset(c->input);
+                chan_ibuf_empty(ssh, c);
                 /* Start output drain. XXX just kill chan? */
-                chan_rcvd_oclose(c);
+                chan_rcvd_oclose(ssh, c);
         }
         if (c->ostate == CHAN_OUTPUT_OPEN ||
             c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
-                if (buffer_len(&c->output) > 0)
+                if (sshbuf_len(c->output) > 0)
                         FD_SET(c->wfd, writeset);
                 else if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN)
-                        chan_obuf_empty(c);
+                        chan_obuf_empty(ssh, c);
         }
 }
 
 /* try to decode a socks4 header */
-/* ARGSUSED */
 static int
-channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
+channel_decode_socks4(Channel *c, struct sshbuf *input, struct sshbuf *output)
 {
-        char *p, *host;
+        const u_char *p;
+        char *host;
         u_int len, have, i, found, need;
         char username[256];
         struct {
@@ -1126,14 +1146,15 @@ channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
                 u_int16_t dest_port;
                 struct in_addr dest_addr;
         } s4_req, s4_rsp;
+        int r;
 
         debug2("channel %d: decode socks4", c->self);
 
-        have = buffer_len(&c->input);
+        have = sshbuf_len(input);
         len = sizeof(s4_req);
         if (have < len)
                 return 0;
-        p = (char *)buffer_ptr(&c->input);
+        p = sshbuf_ptr(input);
 
         need = 1;
         /* SOCKS4A uses an invalid IP address 0.0.0.x */
@@ -1158,46 +1179,55 @@ channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
         }
         if (found < need)
                 return 0;
-        buffer_get(&c->input, (char *)&s4_req.version, 1);
-        buffer_get(&c->input, (char *)&s4_req.command, 1);
-        buffer_get(&c->input, (char *)&s4_req.dest_port, 2);
-        buffer_get(&c->input, (char *)&s4_req.dest_addr, 4);
-        have = buffer_len(&c->input);
-        p = (char *)buffer_ptr(&c->input);
-        if (memchr(p, '\0', have) == NULL)
-                fatal("channel %d: decode socks4: user not nul terminated",
+        if ((r = sshbuf_get(input, &s4_req.version, 1)) != 0 ||
+            (r = sshbuf_get(input, &s4_req.command, 1)) != 0 ||
+            (r = sshbuf_get(input, &s4_req.dest_port, 2)) != 0 ||
+            (r = sshbuf_get(input, &s4_req.dest_addr, 4)) != 0) {
+                debug("channels %d: decode socks4: %s", c->self, ssh_err(r));
+                return -1;
+        }
+        have = sshbuf_len(input);
+        p = sshbuf_ptr(input);
+        if (memchr(p, '\0', have) == NULL) {
+                error("channel %d: decode socks4: user not nul terminated",
                     c->self);
+                return -1;
+        }
         len = strlen(p);
         debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
-        len++;                                  /* trailing '\0' */
-        if (len > have)
-                fatal("channel %d: decode socks4: len %d > have %d",
-                    c->self, len, have);
+        len++; /* trailing '\0' */
         strlcpy(username, p, sizeof(username));
-        buffer_consume(&c->input, len);
-
+        if ((r = sshbuf_consume(input, len)) != 0) {
+                fatal("%s: channel %d: consume: %s", __func__,
+                    c->self, ssh_err(r));
+        }
         free(c->path);
         c->path = NULL;
         if (need == 1) {                        /* SOCKS4: one string */
                 host = inet_ntoa(s4_req.dest_addr);
                 c->path = xstrdup(host);
         } else {                                /* SOCKS4A: two strings */
-                have = buffer_len(&c->input);
-                p = (char *)buffer_ptr(&c->input);
+                have = sshbuf_len(input);
+                p = sshbuf_ptr(input);
+                if (memchr(p, '\0', have) == NULL) {
+                        error("channel %d: decode socks4a: host not nul "
+                            "terminated", c->self);
+                        return -1;
+                }
                 len = strlen(p);
                 debug2("channel %d: decode socks4a: host %s/%d",
                     c->self, p, len);
                 len++;                          /* trailing '\0' */
-                if (len > have)
-                        fatal("channel %d: decode socks4a: len %d > have %d",
-                            c->self, len, have);
                 if (len > NI_MAXHOST) {
                         error("channel %d: hostname \"%.100s\" too long",
                             c->self, p);
                         return -1;
                 }
                 c->path = xstrdup(p);
-                buffer_consume(&c->input, len);
+                if ((r = sshbuf_consume(input, len)) != 0) {
+                        fatal("%s: channel %d: consume: %s", __func__,
+                            c->self, ssh_err(r));
+                }
         }
         c->host_port = ntohs(s4_req.dest_port);
 
@@ -1213,7 +1243,10 @@ channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
         s4_rsp.command = 90;                    /* cd: req granted */
         s4_rsp.dest_port = 0;                   /* ignored */
         s4_rsp.dest_addr.s_addr = INADDR_ANY;   /* ignored */
-        buffer_append(&c->output, &s4_rsp, sizeof(s4_rsp));
+        if ((r = sshbuf_put(output, &s4_rsp, sizeof(s4_rsp))) != 0) {
+                fatal("%s: channel %d: append reply: %s", __func__,
+                    c->self, ssh_err(r));
+        }
         return 1;
 }
 
@@ -1226,10 +1259,10 @@ channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 #define SSH_SOCKS5_CONNECT      0x01
 #define SSH_SOCKS5_SUCCESS      0x00
 
-/* ARGSUSED */
 static int
-channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
+channel_decode_socks5(Channel *c, struct sshbuf *input, struct sshbuf *output)
 {
+        /* XXX use get/put_u8 instead of trusting struct padding */
         struct {
                 u_int8_t version;
                 u_int8_t command;
@@ -1238,14 +1271,15 @@ channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
         } s5_req, s5_rsp;
         u_int16_t dest_port;
         char dest_addr[255+1], ntop[INET6_ADDRSTRLEN];
-        u_char *p;
+        const u_char *p;
         u_int have, need, i, found, nmethods, addrlen, af;
+        int r;
 
         debug2("channel %d: decode socks5", c->self);
-        p = buffer_ptr(&c->input);
+        p = sshbuf_ptr(input);
         if (p[0] != 0x05)
                 return -1;
-        have = buffer_len(&c->input);
+        have = sshbuf_len(input);
         if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
                 /* format: ver | nmethods | methods */
                 if (have < 2)
@@ -1265,10 +1299,16 @@ channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
                             c->self);
                         return -1;
                 }
-                buffer_consume(&c->input, nmethods + 2);
-                buffer_put_char(&c->output, 0x05);              /* version */
-                buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH); /* method */
-                FD_SET(c->sock, writeset);
+                if ((r = sshbuf_consume(input, nmethods + 2)) != 0) {
+                        fatal("%s: channel %d: consume: %s", __func__,
+                            c->self, ssh_err(r));
+                }
+                /* version, method */
+                if ((r = sshbuf_put_u8(output, 0x05)) != 0 ||
+                    (r = sshbuf_put_u8(output, SSH_SOCKS5_NOAUTH)) != 0) {
+                        fatal("%s: channel %d: append reply: %s", __func__,
+                            c->self, ssh_err(r));
+                }
                 c->flags |= SSH_SOCKS5_AUTHDONE;
                 debug2("channel %d: socks5 auth done", c->self);
                 return 0;                               /* need more */
@@ -1305,11 +1345,22 @@ channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
                 need++;
         if (have < need)
                 return 0;
-        buffer_consume(&c->input, sizeof(s5_req));
-        if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
-                buffer_consume(&c->input, 1);    /* host string length */
-        buffer_get(&c->input, &dest_addr, addrlen);
-        buffer_get(&c->input, (char *)&dest_port, 2);
+        if ((r = sshbuf_consume(input, sizeof(s5_req))) != 0) {
+                fatal("%s: channel %d: consume: %s", __func__,
+                    c->self, ssh_err(r));
+        }
+        if (s5_req.atyp == SSH_SOCKS5_DOMAIN) {
+                /* host string length */
+                if ((r = sshbuf_consume(input, 1)) != 0) {
+                        fatal("%s: channel %d: consume: %s", __func__,
+                            c->self, ssh_err(r));
+                }
+        }
+        if ((r = sshbuf_get(input, &dest_addr, addrlen)) != 0 ||
+            (r = sshbuf_get(input, &dest_port, 2)) != 0) {
+                debug("channel %d: parse addr/port: %s", c->self, ssh_err(r));
+                return -1;
+        }
         dest_addr[addrlen] = '\0';
         free(c->path);
         c->path = NULL;
@@ -1336,22 +1387,23 @@ channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
         s5_rsp.atyp = SSH_SOCKS5_IPV4;
         dest_port = 0;                          /* ignored */
 
-        buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
-        buffer_put_int(&c->output, ntohl(INADDR_ANY)); /* bind address */
-        buffer_append(&c->output, &dest_port, sizeof(dest_port));
+        if ((r = sshbuf_put(output, &s5_rsp, sizeof(s5_rsp))) != 0 ||
+            (r = sshbuf_put_u32(output, ntohl(INADDR_ANY))) != 0 ||
+            (r = sshbuf_put(output, &dest_port, sizeof(dest_port))) != 0)
+                fatal("%s: channel %d: append reply: %s", __func__,
+                    c->self, ssh_err(r));
         return 1;
 }
 
 Channel *
-channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
-    int in, int out)
+channel_connect_stdio_fwd(struct ssh *ssh,
+    const char *host_to_connect, u_short port_to_connect, int in, int out)
 {
         Channel *c;
 
-        debug("channel_connect_stdio_fwd %s:%d", host_to_connect,
-            port_to_connect);
+        debug("%s %s:%d", __func__, host_to_connect, port_to_connect);
 
-        c = channel_new("stdio-forward", SSH_CHANNEL_OPENING, in, out,
+        c = channel_new(ssh, "stdio-forward", SSH_CHANNEL_OPENING, in, out,
             -1, CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
             0, "stdio-forward", /*nonblock*/0);
 
@@ -1360,23 +1412,24 @@ channel_connect_stdio_fwd(const char *host_to_connect, u_short port_to_connect,
         c->listening_port = 0;
         c->force_drain = 1;
 
-        channel_register_fds(c, in, out, -1, 0, 1, 0);
-        port_open_helper(c, "direct-tcpip");
+        channel_register_fds(ssh, c, in, out, -1, 0, 1, 0);
+        port_open_helper(ssh, c, "direct-tcpip");
 
         return c;
 }
 
 /* dynamic port forwarding */
 static void
-channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
+channel_pre_dynamic(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
-        u_char *p;
+        const u_char *p;
         u_int have;
         int ret;
 
-        have = buffer_len(&c->input);
+        have = sshbuf_len(c->input);
         debug2("channel %d: pre_dynamic: have %d", c->self, have);
-        /* buffer_dump(&c->input); */
+        /* sshbuf_dump(c->input, stderr); */
         /* check if the fixed size part of the packet is in buffer. */
         if (have < 3) {
                 /* need more */
@@ -1384,105 +1437,174 @@ channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
                 return;
         }
         /* try to guess the protocol */
-        p = buffer_ptr(&c->input);
+        p = sshbuf_ptr(c->input);
+        /* XXX sshbuf_peek_u8? */
         switch (p[0]) {
         case 0x04:
-                ret = channel_decode_socks4(c, readset, writeset);
+                ret = channel_decode_socks4(c, c->input, c->output);
                 break;
         case 0x05:
-                ret = channel_decode_socks5(c, readset, writeset);
+                ret = channel_decode_socks5(c, c->input, c->output);
                 break;
         default:
                 ret = -1;
                 break;
         }
         if (ret < 0) {
-                chan_mark_dead(c);
+                chan_mark_dead(ssh, c);
         } else if (ret == 0) {
                 debug2("channel %d: pre_dynamic: need more", c->self);
                 /* need more */
                 FD_SET(c->sock, readset);
+                if (sshbuf_len(c->output))
+                        FD_SET(c->sock, writeset);
         } else {
                 /* switch to the next state */
                 c->type = SSH_CHANNEL_OPENING;
-                port_open_helper(c, "direct-tcpip");
+                port_open_helper(ssh, c, "direct-tcpip");
+        }
+}
+
+/* simulate read-error */
+static void
+rdynamic_close(struct ssh *ssh, Channel *c)
+{
+        c->type = SSH_CHANNEL_OPEN;
+        chan_read_failed(ssh, c);
+        sshbuf_reset(c->input);
+        chan_ibuf_empty(ssh, c);
+        sshbuf_reset(c->output);
+        chan_write_failed(ssh, c);
+}
+
+/* reverse dynamic port forwarding */
+static void
+channel_before_prepare_select_rdynamic(struct ssh *ssh, Channel *c)
+{
+        const u_char *p;
+        u_int have, len;
+        int r, ret;
+
+        have = sshbuf_len(c->output);
+        debug2("channel %d: pre_rdynamic: have %d", c->self, have);
+        /* sshbuf_dump(c->output, stderr); */
+        /* EOF received */
+        if (c->flags & CHAN_EOF_RCVD) {
+                if ((r = sshbuf_consume(c->output, have)) != 0) {
+                        fatal("%s: channel %d: consume: %s",
+                            __func__, c->self, ssh_err(r));
+                }
+                rdynamic_close(ssh, c);
+                return;
+        }
+        /* check if the fixed size part of the packet is in buffer. */
+        if (have < 3)
+                return;
+        /* try to guess the protocol */
+        p = sshbuf_ptr(c->output);
+        switch (p[0]) {
+        case 0x04:
+                /* switch input/output for reverse forwarding */
+                ret = channel_decode_socks4(c, c->output, c->input);
+                break;
+        case 0x05:
+                ret = channel_decode_socks5(c, c->output, c->input);
+                break;
+        default:
+                ret = -1;
+                break;
+        }
+        if (ret < 0) {
+                rdynamic_close(ssh, c);
+        } else if (ret == 0) {
+                debug2("channel %d: pre_rdynamic: need more", c->self);
+                /* send socks request to peer */
+                len = sshbuf_len(c->input);
+                if (len > 0 && len < c->remote_window) {
+                        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 ||
+                            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+                            (r = sshpkt_put_stringb(ssh, c->input)) != 0 ||
+                            (r = sshpkt_send(ssh)) != 0) {
+                                fatal("%s: channel %i: rdynamic: %s", __func__,
+                                    c->self, ssh_err(r));
+                        }
+                        if ((r = sshbuf_consume(c->input, len)) != 0) {
+                                fatal("%s: channel %d: consume: %s",
+                                    __func__, c->self, ssh_err(r));
+                        }
+                        c->remote_window -= len;
+                }
+        } else if (rdynamic_connect_finish(ssh, c) < 0) {
+                /* the connect failed */
+                rdynamic_close(ssh, c);
         }
 }
 
 /* This is our fake X11 server socket. */
-/* ARGSUSED */
 static void
-channel_post_x11_listener(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_x11_listener(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         Channel *nc;
         struct sockaddr_storage addr;
-        int newsock, oerrno;
+        int r, newsock, oerrno, remote_port;
         socklen_t addrlen;
         char buf[16384], *remote_ipaddr;
-        int remote_port;
-
-        if (FD_ISSET(c->sock, readset)) {
-                debug("X11 connection requested.");
-                addrlen = sizeof(addr);
-                newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
-                if (c->single_connection) {
-                        oerrno = errno;
-                        debug2("single_connection: closing X11 listener.");
-                        channel_close_fd(&c->sock);
-                        chan_mark_dead(c);
-                        errno = oerrno;
-                }
-                if (newsock < 0) {
-                        if (errno != EINTR && errno != EWOULDBLOCK &&
-                            errno != ECONNABORTED)
-                                error("accept: %.100s", strerror(errno));
-                        if (errno == EMFILE || errno == ENFILE)
-                                c->notbefore = monotime() + 1;
-                        return;
-                }
-                set_nodelay(newsock);
-                remote_ipaddr = get_peer_ipaddr(newsock);
-                remote_port = get_peer_port(newsock);
-                snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
-                    remote_ipaddr, remote_port);
-
-                nc = channel_new("accepted x11 socket",
-                    SSH_CHANNEL_OPENING, newsock, newsock, -1,
-                    c->local_window_max, c->local_maxpacket, 0, buf, 1);
-                if (compat20) {
-                        packet_start(SSH2_MSG_CHANNEL_OPEN);
-                        packet_put_cstring("x11");
-                        packet_put_int(nc->self);
-                        packet_put_int(nc->local_window_max);
-                        packet_put_int(nc->local_maxpacket);
-                        /* originator ipaddr and port */
-                        packet_put_cstring(remote_ipaddr);
-                        if (datafellows & SSH_BUG_X11FWD) {
-                                debug2("ssh2 x11 bug compat mode");
-                        } else {
-                                packet_put_int(remote_port);
-                        }
-                        packet_send();
-                } else {
-                        packet_start(SSH_SMSG_X11_OPEN);
-                        packet_put_int(nc->self);
-                        if (packet_get_protocol_flags() &
-                            SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
-                                packet_put_cstring(buf);
-                        packet_send();
-                }
-                free(remote_ipaddr);
+
+        if (!FD_ISSET(c->sock, readset))
+                return;
+
+        debug("X11 connection requested.");
+        addrlen = sizeof(addr);
+        newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
+        if (c->single_connection) {
+                oerrno = errno;
+                debug2("single_connection: closing X11 listener.");
+                channel_close_fd(ssh, &c->sock);
+                chan_mark_dead(ssh, c);
+                errno = oerrno;
+        }
+        if (newsock < 0) {
+                if (errno != EINTR && errno != EWOULDBLOCK &&
+                    errno != ECONNABORTED)
+                        error("accept: %.100s", strerror(errno));
+                if (errno == EMFILE || errno == ENFILE)
+                        c->notbefore = monotime() + 1;
+                return;
         }
+        set_nodelay(newsock);
+        remote_ipaddr = get_peer_ipaddr(newsock);
+        remote_port = get_peer_port(newsock);
+        snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
+            remote_ipaddr, remote_port);
+
+        nc = channel_new(ssh, "accepted x11 socket",
+            SSH_CHANNEL_OPENING, newsock, newsock, -1,
+            c->local_window_max, c->local_maxpacket, 0, buf, 1);
+        open_preamble(ssh, __func__, nc, "x11");
+        if ((r = sshpkt_put_cstring(ssh, remote_ipaddr)) != 0) {
+                fatal("%s: channel %i: reply %s", __func__,
+                    c->self, ssh_err(r));
+        }
+        if ((datafellows & SSH_BUG_X11FWD) != 0)
+                debug2("channel %d: ssh2 x11 bug compat mode", nc->self);
+        else if ((r = sshpkt_put_u32(ssh, remote_port)) != 0) {
+                fatal("%s: channel %i: reply %s", __func__,
+                    c->self, ssh_err(r));
+        }
+        if ((r = sshpkt_send(ssh)) != 0)
+                fatal("%s: channel %i: send %s", __func__, c->self, ssh_err(r));
+        free(remote_ipaddr);
 }
 
 static void
-port_open_helper(Channel *c, char *rtype)
+port_open_helper(struct ssh *ssh, Channel *c, char *rtype)
 {
-        char buf[1024];
         char *local_ipaddr = get_local_ipaddr(c->sock);
         int local_port = c->sock == -1 ? 65536 : get_local_port(c->sock);
         char *remote_ipaddr = get_peer_ipaddr(c->sock);
         int remote_port = get_peer_port(c->sock);
+        int r;
 
         if (remote_port == -1) {
                 /* Fake addr/port to appease peers that validate it (Tectia) */
@@ -1491,55 +1613,57 @@ port_open_helper(Channel *c, char *rtype)
                 remote_port = 65535;
         }
 
-        snprintf(buf, sizeof buf,
+        free(c->remote_name);
+        xasprintf(&c->remote_name,
             "%s: listening port %d for %.100s port %d, "
             "connect from %.200s port %d to %.100s port %d",
             rtype, c->listening_port, c->path, c->host_port,
             remote_ipaddr, remote_port, local_ipaddr, local_port);
 
-        free(c->remote_name);
-        c->remote_name = xstrdup(buf);
-
-        if (compat20) {
-                packet_start(SSH2_MSG_CHANNEL_OPEN);
-                packet_put_cstring(rtype);
-                packet_put_int(c->self);
-                packet_put_int(c->local_window_max);
-                packet_put_int(c->local_maxpacket);
-                if (strcmp(rtype, "direct-tcpip") == 0) {
-                        /* target host, port */
-                        packet_put_cstring(c->path);
-                        packet_put_int(c->host_port);
-                } else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) {
-                        /* target path */
-                        packet_put_cstring(c->path);
-                } else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
-                        /* listen path */
-                        packet_put_cstring(c->path);
-                } else {
-                        /* listen address, port */
-                        packet_put_cstring(c->path);
-                        packet_put_int(local_port);
+        open_preamble(ssh, __func__, c, rtype);
+        if (strcmp(rtype, "direct-tcpip") == 0) {
+                /* target host, port */
+                if ((r = sshpkt_put_cstring(ssh, c->path)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, c->host_port)) != 0) {
+                        fatal("%s: channel %i: reply %s", __func__,
+                            c->self, ssh_err(r));
                 }
-                if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
-                        /* reserved for future owner/mode info */
-                        packet_put_cstring("");
-                } else {
-                        /* originator host and port */
-                        packet_put_cstring(remote_ipaddr);
-                        packet_put_int((u_int)remote_port);
+        } else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) {
+                /* target path */
+                if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) {
+                        fatal("%s: channel %i: reply %s", __func__,
+                            c->self, ssh_err(r));
+                }
+        } else if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
+                /* listen path */
+                if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) {
+                        fatal("%s: channel %i: reply %s", __func__,
+                            c->self, ssh_err(r));
                 }
-                packet_send();
         } else {
-                packet_start(SSH_MSG_PORT_OPEN);
-                packet_put_int(c->self);
-                packet_put_cstring(c->path);
-                packet_put_int(c->host_port);
-                if (packet_get_protocol_flags() &
-                    SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
-                        packet_put_cstring(c->remote_name);
-                packet_send();
+                /* listen address, port */
+                if ((r = sshpkt_put_cstring(ssh, c->path)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, local_port)) != 0) {
+                        fatal("%s: channel %i: reply %s", __func__,
+                            c->self, ssh_err(r));
+                }
         }
+        if (strcmp(rtype, "forwarded-streamlocal@openssh.com") == 0) {
+                /* reserved for future owner/mode info */
+                if ((r = sshpkt_put_cstring(ssh, "")) != 0) {
+                        fatal("%s: channel %i: reply %s", __func__,
+                            c->self, ssh_err(r));
+                }
+        } else {
+                /* originator host and port */
+                if ((r = sshpkt_put_cstring(ssh, remote_ipaddr)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, (u_int)remote_port)) != 0) {
+                        fatal("%s: channel %i: reply %s", __func__,
+                            c->self, ssh_err(r));
+                }
+        }
+        if ((r = sshpkt_send(ssh)) != 0)
+                fatal("%s: channel %i: send %s", __func__, c->self, ssh_err(r));
         free(remote_ipaddr);
         free(local_ipaddr);
 }
@@ -1558,17 +1682,17 @@ channel_set_reuseaddr(int fd)
 }
 
 void
-channel_set_x11_refuse_time(u_int refuse_time)
+channel_set_x11_refuse_time(struct ssh *ssh, u_int refuse_time)
 {
-        x11_refuse_time = refuse_time;
+        ssh->chanctxt->x11_refuse_time = refuse_time;
 }
 
 /*
  * This socket is listening for connections to a forwarded TCP/IP port.
  */
-/* ARGSUSED */
 static void
-channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_port_listener(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         Channel *nc;
         struct sockaddr_storage addr;
@@ -1576,360 +1700,406 @@ channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
         socklen_t addrlen;
         char *rtype;
 
-        if (FD_ISSET(c->sock, readset)) {
-                debug("Connection to port %d forwarding "
-                    "to %.100s port %d requested.",
-                    c->listening_port, c->path, c->host_port);
-
-                if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
-                        nextstate = SSH_CHANNEL_OPENING;
-                        rtype = "forwarded-tcpip";
-                } else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) {
-                        nextstate = SSH_CHANNEL_OPENING;
-                        rtype = "forwarded-streamlocal@openssh.com";
-                } else if (c->host_port == PORT_STREAMLOCAL) {
-                        nextstate = SSH_CHANNEL_OPENING;
-                        rtype = "direct-streamlocal@openssh.com";
-                } else if (c->host_port == 0) {
-                        nextstate = SSH_CHANNEL_DYNAMIC;
-                        rtype = "dynamic-tcpip";
-                } else {
-                        nextstate = SSH_CHANNEL_OPENING;
-                        rtype = "direct-tcpip";
-                }
+        if (!FD_ISSET(c->sock, readset))
+                return;
 
-                addrlen = sizeof(addr);
-                newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
-                if (newsock < 0) {
-                        if (errno != EINTR && errno != EWOULDBLOCK &&
-                            errno != ECONNABORTED)
-                                error("accept: %.100s", strerror(errno));
-                        if (errno == EMFILE || errno == ENFILE)
-                                c->notbefore = monotime() + 1;
-                        return;
-                }
-                if (c->host_port != PORT_STREAMLOCAL)
-                        set_nodelay(newsock);
-                nc = channel_new(rtype, nextstate, newsock, newsock, -1,
-                    c->local_window_max, c->local_maxpacket, 0, rtype, 1);
-                nc->listening_port = c->listening_port;
-                nc->host_port = c->host_port;
-                if (c->path != NULL)
-                        nc->path = xstrdup(c->path);
-
-                if (nextstate != SSH_CHANNEL_DYNAMIC)
-                        port_open_helper(nc, rtype);
+        debug("Connection to port %d forwarding to %.100s port %d requested.",
+            c->listening_port, c->path, c->host_port);
+
+        if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
+                nextstate = SSH_CHANNEL_OPENING;
+                rtype = "forwarded-tcpip";
+        } else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) {
+                nextstate = SSH_CHANNEL_OPENING;
+                rtype = "forwarded-streamlocal@openssh.com";
+        } else if (c->host_port == PORT_STREAMLOCAL) {
+                nextstate = SSH_CHANNEL_OPENING;
+                rtype = "direct-streamlocal@openssh.com";
+        } else if (c->host_port == 0) {
+                nextstate = SSH_CHANNEL_DYNAMIC;
+                rtype = "dynamic-tcpip";
+        } else {
+                nextstate = SSH_CHANNEL_OPENING;
+                rtype = "direct-tcpip";
+        }
+
+        addrlen = sizeof(addr);
+        newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
+        if (newsock < 0) {
+                if (errno != EINTR && errno != EWOULDBLOCK &&
+                    errno != ECONNABORTED)
+                        error("accept: %.100s", strerror(errno));
+                if (errno == EMFILE || errno == ENFILE)
+                        c->notbefore = monotime() + 1;
+                return;
         }
+        if (c->host_port != PORT_STREAMLOCAL)
+                set_nodelay(newsock);
+        nc = channel_new(ssh, rtype, nextstate, newsock, newsock, -1,
+            c->local_window_max, c->local_maxpacket, 0, rtype, 1);
+        nc->listening_port = c->listening_port;
+        nc->host_port = c->host_port;
+        if (c->path != NULL)
+                nc->path = xstrdup(c->path);
+
+        if (nextstate != SSH_CHANNEL_DYNAMIC)
+                port_open_helper(ssh, nc, rtype);
 }
 
 /*
  * This is the authentication agent socket listening for connections from
  * clients.
  */
-/* ARGSUSED */
 static void
-channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_auth_listener(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         Channel *nc;
-        int newsock;
+        int r, newsock;
         struct sockaddr_storage addr;
         socklen_t addrlen;
 
-        if (FD_ISSET(c->sock, readset)) {
-                addrlen = sizeof(addr);
-                newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
-                if (newsock < 0) {
-                        error("accept from auth socket: %.100s",
-                            strerror(errno));
-                        if (errno == EMFILE || errno == ENFILE)
-                                c->notbefore = monotime() + 1;
-                        return;
-                }
-                nc = channel_new("accepted auth socket",
-                    SSH_CHANNEL_OPENING, newsock, newsock, -1,
-                    c->local_window_max, c->local_maxpacket,
-                    0, "accepted auth socket", 1);
-                if (compat20) {
-                        packet_start(SSH2_MSG_CHANNEL_OPEN);
-                        packet_put_cstring("auth-agent@openssh.com");
-                        packet_put_int(nc->self);
-                        packet_put_int(c->local_window_max);
-                        packet_put_int(c->local_maxpacket);
-                } else {
-                        packet_start(SSH_SMSG_AGENT_OPEN);
-                        packet_put_int(nc->self);
-                }
-                packet_send();
+        if (!FD_ISSET(c->sock, readset))
+                return;
+
+        addrlen = sizeof(addr);
+        newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
+        if (newsock < 0) {
+                error("accept from auth socket: %.100s", strerror(errno));
+                if (errno == EMFILE || errno == ENFILE)
+                        c->notbefore = monotime() + 1;
+                return;
         }
+        nc = channel_new(ssh, "accepted auth socket",
+            SSH_CHANNEL_OPENING, newsock, newsock, -1,
+            c->local_window_max, c->local_maxpacket,
+            0, "accepted auth socket", 1);
+        open_preamble(ssh, __func__, nc, "auth-agent@openssh.com");
+        if ((r = sshpkt_send(ssh)) != 0)
+                fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
 }
 
-/* ARGSUSED */
 static void
-channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_connecting(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
-        int err = 0, sock;
+        int err = 0, sock, isopen, r;
         socklen_t sz = sizeof(err);
 
-        if (FD_ISSET(c->sock, writeset)) {
-                if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
-                        err = errno;
-                        error("getsockopt SO_ERROR failed");
+        if (!FD_ISSET(c->sock, writeset))
+                return;
+        if (!c->have_remote_id)
+                fatal(":%s: channel %d: no remote id", __func__, c->self);
+        /* for rdynamic the OPEN_CONFIRMATION has been sent already */
+        isopen = (c->type == SSH_CHANNEL_RDYNAMIC_FINISH);
+        if (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
+                err = errno;
+                error("getsockopt SO_ERROR failed");
+        }
+        if (err == 0) {
+                debug("channel %d: connected to %s port %d",
+                    c->self, c->connect_ctx.host, c->connect_ctx.port);
+                channel_connect_ctx_free(&c->connect_ctx);
+                c->type = SSH_CHANNEL_OPEN;
+                if (isopen) {
+                        /* no message necessary */
+                } else {
+                        if ((r = sshpkt_start(ssh,
+                            SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
+                            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+                            (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
+                            (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
+                            (r = sshpkt_put_u32(ssh, c->local_maxpacket))
+                            != 0)
+                                fatal("%s: channel %i: confirm: %s", __func__,
+                                    c->self, ssh_err(r));
+                        if ((r = sshpkt_send(ssh)) != 0)
+                                fatal("%s: channel %i: %s", __func__, c->self,
+                                    ssh_err(r));
                 }
-                if (err == 0) {
-                        debug("channel %d: connected to %s port %d",
-                            c->self, c->connect_ctx.host, c->connect_ctx.port);
-                        channel_connect_ctx_free(&c->connect_ctx);
-                        c->type = SSH_CHANNEL_OPEN;
-                        if (compat20) {
-                                packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
-                                packet_put_int(c->remote_id);
-                                packet_put_int(c->self);
-                                packet_put_int(c->local_window);
-                                packet_put_int(c->local_maxpacket);
-                        } else {
-                                packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
-                                packet_put_int(c->remote_id);
-                                packet_put_int(c->self);
-                        }
+        } else {
+                debug("channel %d: connection failed: %s",
+                    c->self, strerror(err));
+                /* Try next address, if any */
+                if ((sock = connect_next(&c->connect_ctx)) > 0) {
+                        close(c->sock);
+                        c->sock = c->rfd = c->wfd = sock;
+                        channel_find_maxfd(ssh->chanctxt);
+                        return;
+                }
+                /* Exhausted all addresses */
+                error("connect_to %.100s port %d: failed.",
+                    c->connect_ctx.host, c->connect_ctx.port);
+                channel_connect_ctx_free(&c->connect_ctx);
+                if (isopen) {
+                        rdynamic_close(ssh, c);
                 } else {
-                        debug("channel %d: connection failed: %s",
-                            c->self, strerror(err));
-                        /* Try next address, if any */
-                        if ((sock = connect_next(&c->connect_ctx)) > 0) {
-                                close(c->sock);
-                                c->sock = c->rfd = c->wfd = sock;
-                                channel_max_fd = channel_find_maxfd();
-                                return;
-                        }
-                        /* Exhausted all addresses */
-                        error("connect_to %.100s port %d: failed.",
-                            c->connect_ctx.host, c->connect_ctx.port);
-                        channel_connect_ctx_free(&c->connect_ctx);
-                        if (compat20) {
-                                packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
-                                packet_put_int(c->remote_id);
-                                packet_put_int(SSH2_OPEN_CONNECT_FAILED);
-                                if (!(datafellows & SSH_BUG_OPENFAILURE)) {
-                                        packet_put_cstring(strerror(err));
-                                        packet_put_cstring("");
-                                }
-                        } else {
-                                packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
-                                packet_put_int(c->remote_id);
-                        }
-                        chan_mark_dead(c);
+                        if ((r = sshpkt_start(ssh,
+                            SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
+                            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+                            (r = sshpkt_put_u32(ssh, SSH2_OPEN_CONNECT_FAILED))
+                            != 0)
+                                fatal("%s: channel %i: failure: %s", __func__,
+                                    c->self, ssh_err(r));
+                        if ((datafellows & SSH_BUG_OPENFAILURE) == 0 &&
+                            ((r = sshpkt_put_cstring(ssh, strerror(err))) != 0 ||
+                            (r = sshpkt_put_cstring(ssh, "")) != 0))
+                                fatal("%s: channel %i: failure: %s", __func__,
+                                    c->self, ssh_err(r));
+                        if ((r = sshpkt_send(ssh)) != 0)
+                                fatal("%s: channel %i: %s", __func__, c->self,
+                                    ssh_err(r));
+                        chan_mark_dead(ssh, c);
                 }
-                packet_send();
         }
 }
 
-/* ARGSUSED */
 static int
-channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
+channel_handle_rfd(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         char buf[CHAN_RBUF];
-        int len, force;
+        ssize_t len;
+        int r, force;
 
         force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
-        if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
-                errno = 0;
-                len = read(c->rfd, buf, sizeof(buf));
-                if (len < 0 && (errno == EINTR ||
-                    ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
-                        return 1;
+
+        if (c->rfd == -1 || (!force && !FD_ISSET(c->rfd, readset)))
+                return 1;
+
+        errno = 0;
+        len = read(c->rfd, buf, sizeof(buf));
+        if (len < 0 && (errno == EINTR ||
+            ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
+                return 1;
 #ifndef PTY_ZEROREAD
-                if (len <= 0) {
+        if (len <= 0) {
 #else
-                if ((!c->isatty && len <= 0) ||
-                    (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
+        if ((!c->isatty && len <= 0) ||
+            (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
 #endif
-                        debug2("channel %d: read<=0 rfd %d len %d",
-                            c->self, c->rfd, len);
-                        if (c->type != SSH_CHANNEL_OPEN) {
-                                debug2("channel %d: not open", c->self);
-                                chan_mark_dead(c);
-                                return -1;
-                        } else if (compat13) {
-                                buffer_clear(&c->output);
-                                c->type = SSH_CHANNEL_INPUT_DRAINING;
-                                debug2("channel %d: input draining.", c->self);
-                        } else {
-                                chan_read_failed(c);
-                        }
+                debug2("channel %d: read<=0 rfd %d len %zd",
+                    c->self, c->rfd, len);
+                if (c->type != SSH_CHANNEL_OPEN) {
+                        debug2("channel %d: not open", c->self);
+                        chan_mark_dead(ssh, c);
                         return -1;
-                }
-                if (c->input_filter != NULL) {
-                        if (c->input_filter(c, buf, len) == -1) {
-                                debug2("channel %d: filter stops", c->self);
-                                chan_read_failed(c);
-                        }
-                } else if (c->datagram) {
-                        buffer_put_string(&c->input, buf, len);
                 } else {
-                        buffer_append(&c->input, buf, len);
+                        chan_read_failed(ssh, c);
+                }
+                return -1;
+        }
+        if (c->input_filter != NULL) {
+                if (c->input_filter(ssh, c, buf, len) == -1) {
+                        debug2("channel %d: filter stops", c->self);
+                        chan_read_failed(ssh, c);
                 }
+        } else if (c->datagram) {
+                if ((r = sshbuf_put_string(c->input, buf, len)) != 0)
+                        fatal("%s: channel %d: put datagram: %s", __func__,
+                            c->self, ssh_err(r));
+        } else if ((r = sshbuf_put(c->input, buf, len)) != 0) {
+                fatal("%s: channel %d: put data: %s", __func__,
+                    c->self, ssh_err(r));
         }
         return 1;
 }
 
-/* ARGSUSED */
 static int
-channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
+channel_handle_wfd(struct ssh *ssh, Channel *c,
+   fd_set *readset, fd_set *writeset)
 {
         struct termios tio;
-        u_char *data = NULL, *buf;
-        u_int dlen, olen = 0;
-        int len;
+        u_char *data = NULL, *buf; /* XXX const; need filter API change */
+        size_t dlen, olen = 0;
+        int r, len;
+
+        if (c->wfd == -1 || !FD_ISSET(c->wfd, writeset) ||
+            sshbuf_len(c->output) == 0)
+                return 1;
 
         /* Send buffered output data to the socket. */
-        if (c->wfd != -1 &&
-            FD_ISSET(c->wfd, writeset) &&
-            buffer_len(&c->output) > 0) {
-                olen = buffer_len(&c->output);
-                if (c->output_filter != NULL) {
-                        if ((buf = c->output_filter(c, &data, &dlen)) == NULL) {
-                                debug2("channel %d: filter stops", c->self);
-                                if (c->type != SSH_CHANNEL_OPEN)
-                                        chan_mark_dead(c);
-                                else
-                                        chan_write_failed(c);
-                                return -1;
-                        }
-                } else if (c->datagram) {
-                        buf = data = buffer_get_string(&c->output, &dlen);
-                } else {
-                        buf = data = buffer_ptr(&c->output);
-                        dlen = buffer_len(&c->output);
+        olen = sshbuf_len(c->output);
+        if (c->output_filter != NULL) {
+                if ((buf = c->output_filter(ssh, c, &data, &dlen)) == NULL) {
+                        debug2("channel %d: filter stops", c->self);
+                        if (c->type != SSH_CHANNEL_OPEN)
+                                chan_mark_dead(ssh, c);
+                        else
+                                chan_write_failed(ssh, c);
+                        return -1;
                 }
+        } else if (c->datagram) {
+                if ((r = sshbuf_get_string(c->output, &data, &dlen)) != 0)
+                        fatal("%s: channel %d: get datagram: %s", __func__,
+                            c->self, ssh_err(r));
+                buf = data;
+        } else {
+                buf = data = sshbuf_mutable_ptr(c->output);
+                dlen = sshbuf_len(c->output);
+        }
+
+        if (c->datagram) {
+                /* ignore truncated writes, datagrams might get lost */
+                len = write(c->wfd, buf, dlen);
+                free(data);
+                if (len < 0 && (errno == EINTR || errno == EAGAIN ||
+                    errno == EWOULDBLOCK))
+                        return 1;
+                if (len <= 0)
+                        goto write_fail;
+                goto out;
+        }
 
-                if (c->datagram) {
-                        /* ignore truncated writes, datagrams might get lost */
-                        len = write(c->wfd, buf, dlen);
-                        free(data);
-                        if (len < 0 && (errno == EINTR || errno == EAGAIN ||
-                            errno == EWOULDBLOCK))
-                                return 1;
-                        if (len <= 0) {
-                                if (c->type != SSH_CHANNEL_OPEN)
-                                        chan_mark_dead(c);
-                                else
-                                        chan_write_failed(c);
-                                return -1;
-                        }
-                        goto out;
-                }
 #ifdef _AIX
-                /* XXX: Later AIX versions can't push as much data to tty */
-                if (compat20 && c->wfd_isatty)
-                        dlen = MIN(dlen, 8*1024);
+        /* XXX: Later AIX versions can't push as much data to tty */
+        if (c->wfd_isatty)
+                dlen = MIN(dlen, 8*1024);
 #endif
 
-                len = write(c->wfd, buf, dlen);
-                if (len < 0 &&
-                    (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
-                        return 1;
-                if (len <= 0) {
-                        if (c->type != SSH_CHANNEL_OPEN) {
-                                debug2("channel %d: not open", c->self);
-                                chan_mark_dead(c);
-                                return -1;
-                        } else if (compat13) {
-                                buffer_clear(&c->output);
-                                debug2("channel %d: input draining.", c->self);
-                                c->type = SSH_CHANNEL_INPUT_DRAINING;
-                        } else {
-                                chan_write_failed(c);
-                        }
+        len = write(c->wfd, buf, dlen);
+        if (len < 0 &&
+            (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
+                return 1;
+        if (len <= 0) {
+ write_fail:
+                if (c->type != SSH_CHANNEL_OPEN) {
+                        debug2("channel %d: not open", c->self);
+                        chan_mark_dead(ssh, c);
                         return -1;
+                } else {
+                        chan_write_failed(ssh, c);
                 }
+                return -1;
+        }
 #ifndef BROKEN_TCGETATTR_ICANON
-                if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
-                        if (tcgetattr(c->wfd, &tio) == 0 &&
-                            !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
-                                /*
-                                 * Simulate echo to reduce the impact of
-                                 * traffic analysis. We need to match the
-                                 * size of a SSH2_MSG_CHANNEL_DATA message
-                                 * (4 byte channel id + buf)
-                                 */
-                                packet_send_ignore(4 + len);
-                                packet_send();
-                        }
+        if (c->isatty && dlen >= 1 && buf[0] != '\r') {
+                if (tcgetattr(c->wfd, &tio) == 0 &&
+                    !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
+                        /*
+                         * Simulate echo to reduce the impact of
+                         * traffic analysis. We need to match the
+                         * size of a SSH2_MSG_CHANNEL_DATA message
+                         * (4 byte channel id + buf)
+                         */
+                        if ((r = sshpkt_msg_ignore(ssh, 4+len)) != 0 ||
+                            (r = sshpkt_send(ssh)) != 0)
+                                fatal("%s: channel %d: ignore: %s",
+                                    __func__, c->self, ssh_err(r));
                 }
-#endif
-                buffer_consume(&c->output, len);
+        }
+#endif /* BROKEN_TCGETATTR_ICANON */
+        if ((r = sshbuf_consume(c->output, len)) != 0) {
+                fatal("%s: channel %d: consume: %s",
+                    __func__, c->self, ssh_err(r));
         }
  out:
-        if (compat20 && olen > 0)
-                c->local_consumed += olen - buffer_len(&c->output);
+        c->local_consumed += olen - sshbuf_len(c->output);
+
         return 1;
 }
 
 static int
-channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
+channel_handle_efd_write(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
+{
+        int r;
+        ssize_t len;
+
+        if (!FD_ISSET(c->efd, writeset) || sshbuf_len(c->extended) == 0)
+                return 1;
+
+        len = write(c->efd, sshbuf_ptr(c->extended),
+            sshbuf_len(c->extended));
+        debug2("channel %d: written %zd to efd %d", c->self, len, c->efd);
+        if (len < 0 && (errno == EINTR || errno == EAGAIN ||
+            errno == EWOULDBLOCK))
+                return 1;
+        if (len <= 0) {
+                debug2("channel %d: closing write-efd %d", c->self, c->efd);
+                channel_close_fd(ssh, &c->efd);
+        } else {
+                if ((r = sshbuf_consume(c->extended, len)) != 0) {
+                        fatal("%s: channel %d: consume: %s",
+                            __func__, c->self, ssh_err(r));
+                }
+                c->local_consumed += len;
+        }
+        return 1;
+}
+
+static int
+channel_handle_efd_read(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         char buf[CHAN_RBUF];
-        int len;
+        int r;
+        ssize_t len;
 
-/** XXX handle drain efd, too */
-        if (c->efd != -1) {
-                if (c->extended_usage == CHAN_EXTENDED_WRITE &&
-                    FD_ISSET(c->efd, writeset) &&
-                    buffer_len(&c->extended) > 0) {
-                        len = write(c->efd, buffer_ptr(&c->extended),
-                            buffer_len(&c->extended));
-                        debug2("channel %d: written %d to efd %d",
-                            c->self, len, c->efd);
-                        if (len < 0 && (errno == EINTR || errno == EAGAIN ||
-                            errno == EWOULDBLOCK))
-                                return 1;
-                        if (len <= 0) {
-                                debug2("channel %d: closing write-efd %d",
-                                    c->self, c->efd);
-                                channel_close_fd(&c->efd);
-                        } else {
-                                buffer_consume(&c->extended, len);
-                                c->local_consumed += len;
-                        }
-                } else if (c->efd != -1 &&
-                    (c->extended_usage == CHAN_EXTENDED_READ ||
-                    c->extended_usage == CHAN_EXTENDED_IGNORE) &&
-                    (c->detach_close || FD_ISSET(c->efd, readset))) {
-                        len = read(c->efd, buf, sizeof(buf));
-                        debug2("channel %d: read %d from efd %d",
-                            c->self, len, c->efd);
-                        if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
-                            errno == EWOULDBLOCK) && !c->detach_close)))
-                                return 1;
-                        if (len <= 0) {
-                                debug2("channel %d: closing read-efd %d",
-                                    c->self, c->efd);
-                                channel_close_fd(&c->efd);
-                        } else {
-                                if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
-                                        debug3("channel %d: discard efd",
-                                            c->self);
-                                } else
-                                        buffer_append(&c->extended, buf, len);
-                        }
+        if (!c->detach_close && !FD_ISSET(c->efd, readset))
+                return 1;
+
+        len = read(c->efd, buf, sizeof(buf));
+        debug2("channel %d: read %zd from efd %d", c->self, len, c->efd);
+        if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
+            errno == EWOULDBLOCK) && !c->detach_close)))
+                return 1;
+        if (len <= 0) {
+                debug2("channel %d: closing read-efd %d",
+                    c->self, c->efd);
+                channel_close_fd(ssh, &c->efd);
+        } else {
+                if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
+                        debug3("channel %d: discard efd",
+                            c->self);
+                } else if ((r = sshbuf_put(c->extended, buf, len)) != 0) {
+                        fatal("%s: channel %d: append: %s",
+                            __func__, c->self, ssh_err(r));
                 }
         }
         return 1;
 }
 
 static int
-channel_check_window(Channel *c)
+channel_handle_efd(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
+        if (c->efd == -1)
+                return 1;
+
+        /** XXX handle drain efd, too */
+
+        if (c->extended_usage == CHAN_EXTENDED_WRITE)
+                return channel_handle_efd_write(ssh, c, readset, writeset);
+        else if (c->extended_usage == CHAN_EXTENDED_READ ||
+            c->extended_usage == CHAN_EXTENDED_IGNORE)
+                return channel_handle_efd_read(ssh, c, readset, writeset);
+
+        return 1;
+}
+
+static int
+channel_check_window(struct ssh *ssh, Channel *c)
+{
+        int r;
+
         if (c->type == SSH_CHANNEL_OPEN &&
             !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
             ((c->local_window_max - c->local_window >
             c->local_maxpacket*3) ||
             c->local_window < c->local_window_max/2) &&
             c->local_consumed > 0) {
-                packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-                packet_put_int(c->remote_id);
-                packet_put_int(c->local_consumed);
-                packet_send();
+                if (!c->have_remote_id)
+                        fatal(":%s: channel %d: no remote id",
+                            __func__, c->self);
+                if ((r = sshpkt_start(ssh,
+                    SSH2_MSG_CHANNEL_WINDOW_ADJUST)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, c->local_consumed)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0) {
+                        fatal("%s: channel %i: %s", __func__,
+                            c->self, ssh_err(r));
+                }
                 debug2("channel %d: window %d sent adjust %d",
                     c->self, c->local_window,
                     c->local_consumed);
@@ -1940,90 +2110,112 @@ channel_check_window(Channel *c)
 }
 
 static void
-channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_open(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
-        channel_handle_rfd(c, readset, writeset);
-        channel_handle_wfd(c, readset, writeset);
-        if (!compat20)
-                return;
-        channel_handle_efd(c, readset, writeset);
-        channel_check_window(c);
+        channel_handle_rfd(ssh, c, readset, writeset);
+        channel_handle_wfd(ssh, c, readset, writeset);
+        channel_handle_efd(ssh, c, readset, writeset);
+        channel_check_window(ssh, c);
 }
 
 static u_int
-read_mux(Channel *c, u_int need)
+read_mux(struct ssh *ssh, Channel *c, u_int need)
 {
         char buf[CHAN_RBUF];
-        int len;
+        ssize_t len;
         u_int rlen;
+        int r;
 
-        if (buffer_len(&c->input) < need) {
-                rlen = need - buffer_len(&c->input);
+        if (sshbuf_len(c->input) < need) {
+                rlen = need - sshbuf_len(c->input);
                 len = read(c->rfd, buf, MINIMUM(rlen, CHAN_RBUF));
                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
-                        return buffer_len(&c->input);
+                        return sshbuf_len(c->input);
                 if (len <= 0) {
-                        debug2("channel %d: ctl read<=0 rfd %d len %d",
+                        debug2("channel %d: ctl read<=0 rfd %d len %zd",
                             c->self, c->rfd, len);
-                        chan_read_failed(c);
+                        chan_read_failed(ssh, c);
                         return 0;
-                } else
-                        buffer_append(&c->input, buf, len);
+                } else if ((r = sshbuf_put(c->input, buf, len)) != 0) {
+                        fatal("%s: channel %d: append: %s",
+                            __func__, c->self, ssh_err(r));
+                }
         }
-        return buffer_len(&c->input);
+        return sshbuf_len(c->input);
 }
 
 static void
-channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_mux_client_read(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         u_int need;
-        ssize_t len;
 
-        if (!compat20)
-                fatal("%s: entered with !compat20", __func__);
+        if (c->rfd == -1 || !FD_ISSET(c->rfd, readset))
+                return;
+        if (c->istate != CHAN_INPUT_OPEN && c->istate != CHAN_INPUT_WAIT_DRAIN)
+                return;
+        if (c->mux_pause)
+                return;
 
-        if (c->rfd != -1 && !c->mux_pause && FD_ISSET(c->rfd, readset) &&
-            (c->istate == CHAN_INPUT_OPEN ||
-            c->istate == CHAN_INPUT_WAIT_DRAIN)) {
-                /*
-                 * Don't not read past the precise end of packets to
-                 * avoid disrupting fd passing.
-                 */
-                if (read_mux(c, 4) < 4) /* read header */
-                        return;
-                need = get_u32(buffer_ptr(&c->input));
+        /*
+         * Don't not read past the precise end of packets to
+         * avoid disrupting fd passing.
+         */
+        if (read_mux(ssh, c, 4) < 4) /* read header */
+                return;
+        /* XXX sshbuf_peek_u32 */
+        need = PEEK_U32(sshbuf_ptr(c->input));
 #define CHANNEL_MUX_MAX_PACKET  (256 * 1024)
-                if (need > CHANNEL_MUX_MAX_PACKET) {
-                        debug2("channel %d: packet too big %u > %u",
-                            c->self, CHANNEL_MUX_MAX_PACKET, need);
-                        chan_rcvd_oclose(c);
-                        return;
-                }
-                if (read_mux(c, need + 4) < need + 4) /* read body */
-                        return;
-                if (c->mux_rcb(c) != 0) {
-                        debug("channel %d: mux_rcb failed", c->self);
-                        chan_mark_dead(c);
-                        return;
-                }
+        if (need > CHANNEL_MUX_MAX_PACKET) {
+                debug2("channel %d: packet too big %u > %u",
+                    c->self, CHANNEL_MUX_MAX_PACKET, need);
+                chan_rcvd_oclose(ssh, c);
+                return;
+        }
+        if (read_mux(ssh, c, need + 4) < need + 4) /* read body */
+                return;
+        if (c->mux_rcb(ssh, c) != 0) {
+                debug("channel %d: mux_rcb failed", c->self);
+                chan_mark_dead(ssh, c);
+                return;
         }
+}
 
-        if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
-            buffer_len(&c->output) > 0) {
-                len = write(c->wfd, buffer_ptr(&c->output),
-                    buffer_len(&c->output));
-                if (len < 0 && (errno == EINTR || errno == EAGAIN))
-                        return;
-                if (len <= 0) {
-                        chan_mark_dead(c);
-                        return;
-                }
-                buffer_consume(&c->output, len);
+static void
+channel_post_mux_client_write(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
+{
+        ssize_t len;
+        int r;
+
+        if (c->wfd == -1 || !FD_ISSET(c->wfd, writeset) ||
+            sshbuf_len(c->output) == 0)
+                return;
+
+        len = write(c->wfd, sshbuf_ptr(c->output), sshbuf_len(c->output));
+        if (len < 0 && (errno == EINTR || errno == EAGAIN))
+                return;
+        if (len <= 0) {
+                chan_mark_dead(ssh, c);
+                return;
         }
+        if ((r = sshbuf_consume(c->output, len)) != 0)
+                fatal("%s: channel %d: consume: %s", __func__,
+                    c->self, ssh_err(r));
+}
+
+static void
+channel_post_mux_client(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
+{
+        channel_post_mux_client_read(ssh, c, readset, writeset);
+        channel_post_mux_client_write(ssh, c, readset, writeset);
 }
 
 static void
-channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_mux_listener(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
         Channel *nc;
         struct sockaddr_storage addr;
@@ -2062,166 +2254,100 @@ channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
                 close(newsock);
                 return;
         }
-        nc = channel_new("multiplex client", SSH_CHANNEL_MUX_CLIENT,
+        nc = channel_new(ssh, "multiplex client", SSH_CHANNEL_MUX_CLIENT,
             newsock, newsock, -1, c->local_window_max,
             c->local_maxpacket, 0, "mux-control", 1);
         nc->mux_rcb = c->mux_rcb;
-        debug3("%s: new mux channel %d fd %d", __func__,
-            nc->self, nc->sock);
+        debug3("%s: new mux channel %d fd %d", __func__, nc->self, nc->sock);
         /* establish state */
-        nc->mux_rcb(nc);
+        nc->mux_rcb(ssh, nc);
         /* mux state transitions must not elicit protocol messages */
         nc->flags |= CHAN_LOCAL;
 }
 
-/* ARGSUSED */
 static void
-channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
+channel_handler_init(struct ssh_channels *sc)
 {
-        int len;
-
-        /* Send buffered output data to the socket. */
-        if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
-                len = write(c->sock, buffer_ptr(&c->output),
-                            buffer_len(&c->output));
-                if (len <= 0)
-                        buffer_clear(&c->output);
-                else
-                        buffer_consume(&c->output, len);
-        }
-}
-
-static void
-channel_handler_init_20(void)
-{
-        channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
-        channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
-        channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_UNIX_LISTENER] =        &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_RUNIX_LISTENER] =       &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
-        channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
-        channel_pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
-
-        channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
-        channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
-        channel_post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
-        channel_post[SSH_CHANNEL_UNIX_LISTENER] =       &channel_post_port_listener;
-        channel_post[SSH_CHANNEL_RUNIX_LISTENER] =      &channel_post_port_listener;
-        channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
-        channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
-        channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
-        channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
-        channel_post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
-        channel_post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
-}
-
-static void
-channel_handler_init_13(void)
-{
-        channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open_13;
-        channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open_13;
-        channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_INPUT_DRAINING] =       &channel_pre_input_draining;
-        channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =      &channel_pre_output_draining;
-        channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
-        channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
-
-        channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
-        channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
-        channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
-        channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
-        channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =     &channel_post_output_drain_13;
-        channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
-        channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
-}
-
-static void
-channel_handler_init_15(void)
-{
-        channel_pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
-        channel_pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
-        channel_pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
-        channel_pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
-        channel_pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
-
-        channel_post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
-        channel_post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
-        channel_post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
-        channel_post[SSH_CHANNEL_OPEN] =                &channel_post_open;
-        channel_post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
-        channel_post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
-}
-
-static void
-channel_handler_init(void)
-{
-        int i;
-
-        for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
-                channel_pre[i] = NULL;
-                channel_post[i] = NULL;
-        }
-        if (compat20)
-                channel_handler_init_20();
-        else if (compat13)
-                channel_handler_init_13();
-        else
-                channel_handler_init_15();
+        chan_fn **pre, **post;
+
+        if ((pre = calloc(SSH_CHANNEL_MAX_TYPE, sizeof(*pre))) == NULL ||
+           (post = calloc(SSH_CHANNEL_MAX_TYPE, sizeof(*post))) == NULL)
+                fatal("%s: allocation failed", __func__);
+
+        pre[SSH_CHANNEL_OPEN] =                 &channel_pre_open;
+        pre[SSH_CHANNEL_X11_OPEN] =             &channel_pre_x11_open;
+        pre[SSH_CHANNEL_PORT_LISTENER] =        &channel_pre_listener;
+        pre[SSH_CHANNEL_RPORT_LISTENER] =       &channel_pre_listener;
+        pre[SSH_CHANNEL_UNIX_LISTENER] =        &channel_pre_listener;
+        pre[SSH_CHANNEL_RUNIX_LISTENER] =       &channel_pre_listener;
+        pre[SSH_CHANNEL_X11_LISTENER] =         &channel_pre_listener;
+        pre[SSH_CHANNEL_AUTH_SOCKET] =          &channel_pre_listener;
+        pre[SSH_CHANNEL_CONNECTING] =           &channel_pre_connecting;
+        pre[SSH_CHANNEL_DYNAMIC] =              &channel_pre_dynamic;
+        pre[SSH_CHANNEL_RDYNAMIC_FINISH] =      &channel_pre_connecting;
+        pre[SSH_CHANNEL_MUX_LISTENER] =         &channel_pre_listener;
+        pre[SSH_CHANNEL_MUX_CLIENT] =           &channel_pre_mux_client;
+
+        post[SSH_CHANNEL_OPEN] =                &channel_post_open;
+        post[SSH_CHANNEL_PORT_LISTENER] =       &channel_post_port_listener;
+        post[SSH_CHANNEL_RPORT_LISTENER] =      &channel_post_port_listener;
+        post[SSH_CHANNEL_UNIX_LISTENER] =       &channel_post_port_listener;
+        post[SSH_CHANNEL_RUNIX_LISTENER] =      &channel_post_port_listener;
+        post[SSH_CHANNEL_X11_LISTENER] =        &channel_post_x11_listener;
+        post[SSH_CHANNEL_AUTH_SOCKET] =         &channel_post_auth_listener;
+        post[SSH_CHANNEL_CONNECTING] =          &channel_post_connecting;
+        post[SSH_CHANNEL_DYNAMIC] =             &channel_post_open;
+        post[SSH_CHANNEL_RDYNAMIC_FINISH] =     &channel_post_connecting;
+        post[SSH_CHANNEL_MUX_LISTENER] =        &channel_post_mux_listener;
+        post[SSH_CHANNEL_MUX_CLIENT] =          &channel_post_mux_client;
+
+        sc->channel_pre = pre;
+        sc->channel_post = post;
 }
 
 /* gc dead channels */
 static void
-channel_garbage_collect(Channel *c)
+channel_garbage_collect(struct ssh *ssh, Channel *c)
 {
         if (c == NULL)
                 return;
         if (c->detach_user != NULL) {
-                if (!chan_is_dead(c, c->detach_close))
+                if (!chan_is_dead(ssh, c, c->detach_close))
                         return;
                 debug2("channel %d: gc: notify user", c->self);
-                c->detach_user(c->self, NULL);
+                c->detach_user(ssh, c->self, NULL);
                 /* if we still have a callback */
                 if (c->detach_user != NULL)
                         return;
                 debug2("channel %d: gc: user detached", c->self);
         }
-        if (!chan_is_dead(c, 1))
+        if (!chan_is_dead(ssh, c, 1))
                 return;
         debug2("channel %d: garbage collecting", c->self);
-        channel_free(c);
+        channel_free(ssh, c);
 }
 
+enum channel_table { CHAN_PRE, CHAN_POST };
+
 static void
-channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
-    time_t *unpause_secs)
+channel_handler(struct ssh *ssh, int table,
+    fd_set *readset, fd_set *writeset, time_t *unpause_secs)
 {
-        static int did_init = 0;
+        struct ssh_channels *sc = ssh->chanctxt;
+        chan_fn **ftab = table == CHAN_PRE ? sc->channel_pre : sc->channel_post;
         u_int i, oalloc;
         Channel *c;
         time_t now;
 
-        if (!did_init) {
-                channel_handler_init();
-                did_init = 1;
-        }
         now = monotime();
         if (unpause_secs != NULL)
                 *unpause_secs = 0;
-        for (i = 0, oalloc = channels_alloc; i < oalloc; i++) {
-                c = channels[i];
+        for (i = 0, oalloc = sc->channels_alloc; i < oalloc; i++) {
+                c = sc->channels[i];
                 if (c == NULL)
                         continue;
                 if (c->delayed) {
-                        if (ftab == channel_pre)
+                        if (table == CHAN_PRE)
                                 c->delayed = 0;
                         else
                                 continue;
@@ -2231,7 +2357,7 @@ channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
                          * Run handlers that are not paused.
                          */
                         if (c->notbefore <= now)
-                                (*ftab[c->type])(c, readset, writeset);
+                                (*ftab[c->type])(ssh, c, readset, writeset);
                         else if (unpause_secs != NULL) {
                                 /*
                                  * Collect the time that the earliest
@@ -2245,7 +2371,7 @@ channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
                                         *unpause_secs = c->notbefore - now;
                         }
                 }
-                channel_garbage_collect(c);
+                channel_garbage_collect(ssh, c);
         }
         if (unpause_secs != NULL && *unpause_secs != 0)
                 debug3("%s: first channel unpauses in %d seconds",
@@ -2253,16 +2379,39 @@ channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset,
 }
 
 /*
+ * Create sockets before allocating the select bitmasks.
+ * This is necessary for things that need to happen after reading
+ * the network-input but before channel_prepare_select().
+ */
+static void
+channel_before_prepare_select(struct ssh *ssh)
+{
+        struct ssh_channels *sc = ssh->chanctxt;
+        Channel *c;
+        u_int i, oalloc;
+
+        for (i = 0, oalloc = sc->channels_alloc; i < oalloc; i++) {
+                c = sc->channels[i];
+                if (c == NULL)
+                        continue;
+                if (c->type == SSH_CHANNEL_RDYNAMIC_OPEN)
+                        channel_before_prepare_select_rdynamic(ssh, c);
+        }
+}
+
+/*
  * Allocate/update select bitmasks and add any bits relevant to channels in
  * select bitmasks.
  */
 void
-channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
-    u_int *nallocp, time_t *minwait_secs, int rekeying)
+channel_prepare_select(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp,
+    int *maxfdp, u_int *nallocp, time_t *minwait_secs)
 {
         u_int n, sz, nfdset;
 
-        n = MAXIMUM(*maxfdp, channel_max_fd);
+        channel_before_prepare_select(ssh); /* might update channel_max_fd */
+
+        n = MAXIMUM(*maxfdp, ssh->chanctxt->channel_max_fd);
 
         nfdset = howmany(n+1, NFDBITS);
         /* Explicitly test here, because xrealloc isn't always called */
@@ -2280,8 +2429,8 @@ channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
         memset(*readsetp, 0, sz);
         memset(*writesetp, 0, sz);
 
-        if (!rekeying)
-                channel_handler(channel_pre, *readsetp, *writesetp,
+        if (!ssh_packet_is_rekeying(ssh))
+                channel_handler(ssh, CHAN_PRE, *readsetp, *writesetp,
                     minwait_secs);
 }
 
@@ -2290,21 +2439,136 @@ channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
  * events pending.
  */
 void
-channel_after_select(fd_set *readset, fd_set *writeset)
+channel_after_select(struct ssh *ssh, fd_set *readset, fd_set *writeset)
 {
-        channel_handler(channel_post, readset, writeset, NULL);
+        channel_handler(ssh, CHAN_POST, readset, writeset, NULL);
 }
 
+/*
+ * Enqueue data for channels with open or draining c->input.
+ */
+static void
+channel_output_poll_input_open(struct ssh *ssh, Channel *c)
+{
+        size_t len, plen;
+        const u_char *pkt;
+        int r;
+
+        if ((len = sshbuf_len(c->input)) == 0) {
+                if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
+                        /*
+                         * input-buffer is empty and read-socket shutdown:
+                         * tell peer, that we will not send more data:
+                         * send IEOF.
+                         * hack for extended data: delay EOF if EFD still
+                         * in use.
+                         */
+                        if (CHANNEL_EFD_INPUT_ACTIVE(c))
+                                debug2("channel %d: "
+                                    "ibuf_empty delayed efd %d/(%zu)",
+                                    c->self, c->efd, sshbuf_len(c->extended));
+                        else
+                                chan_ibuf_empty(ssh, c);
+                }
+                return;
+        }
+
+        if (!c->have_remote_id)
+                fatal(":%s: channel %d: no remote id", __func__, c->self);
+
+        if (c->datagram) {
+                /* Check datagram will fit; drop if not */
+                if ((r = sshbuf_get_string_direct(c->input, &pkt, &plen)) != 0)
+                        fatal("%s: channel %d: get datagram: %s", __func__,
+                            c->self, ssh_err(r));
+                /*
+                 * XXX this does tail-drop on the datagram queue which is
+                 * usually suboptimal compared to head-drop. Better to have
+                 * backpressure at read time? (i.e. read + discard)
+                 */
+                if (plen > c->remote_window || plen > c->remote_maxpacket) {
+                        debug("channel %d: datagram too big", c->self);
+                        return;
+                }
+                /* Enqueue it */
+                if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+                    (r = sshpkt_put_string(ssh, pkt, plen)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0) {
+                        fatal("%s: channel %i: datagram: %s", __func__,
+                            c->self, ssh_err(r));
+                }
+                c->remote_window -= plen;
+                return;
+        }
+
+        /* Enqueue packet for buffered data. */
+        if (len > c->remote_window)
+                len = c->remote_window;
+        if (len > c->remote_maxpacket)
+                len = c->remote_maxpacket;
+        if (len == 0)
+                return;
+        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_DATA)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+            (r = sshpkt_put_string(ssh, sshbuf_ptr(c->input), len)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0) {
+                fatal("%s: channel %i: data: %s", __func__,
+                    c->self, ssh_err(r));
+        }
+        if ((r = sshbuf_consume(c->input, len)) != 0)
+                fatal("%s: channel %i: consume: %s", __func__,
+                    c->self, ssh_err(r));
+        c->remote_window -= len;
+}
+
+/*
+ * Enqueue data for channels with open c->extended in read mode.
+ */
+static void
+channel_output_poll_extended_read(struct ssh *ssh, Channel *c)
+{
+        size_t len;
+        int r;
+
+        if ((len = sshbuf_len(c->extended)) == 0)
+                return;
+
+        debug2("channel %d: rwin %u elen %zu euse %d", c->self,
+            c->remote_window, sshbuf_len(c->extended), c->extended_usage);
+        if (len > c->remote_window)
+                len = c->remote_window;
+        if (len > c->remote_maxpacket)
+                len = c->remote_maxpacket;
+        if (len == 0)
+                return;
+        if (!c->have_remote_id)
+                fatal(":%s: channel %d: no remote id", __func__, c->self);
+        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EXTENDED_DATA)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+            (r = sshpkt_put_u32(ssh, SSH2_EXTENDED_DATA_STDERR)) != 0 ||
+            (r = sshpkt_put_string(ssh, sshbuf_ptr(c->extended), len)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0) {
+                fatal("%s: channel %i: data: %s", __func__,
+                    c->self, ssh_err(r));
+        }
+        if ((r = sshbuf_consume(c->extended, len)) != 0)
+                fatal("%s: channel %i: consume: %s", __func__,
+                    c->self, ssh_err(r));
+        c->remote_window -= len;
+        debug2("channel %d: sent ext data %zu", c->self, len);
+}
 
 /* If there is data to send to the connection, enqueue some of it now. */
 void
-channel_output_poll(void)
+channel_output_poll(struct ssh *ssh)
 {
+        struct ssh_channels *sc = ssh->chanctxt;
         Channel *c;
-        u_int i, len;
+        u_int i;
 
-        for (i = 0; i < channels_alloc; i++) {
-                c = channels[i];
+        for (i = 0; i < sc->channels_alloc; i++) {
+                c = sc->channels[i];
                 if (c == NULL)
                         continue;
 
@@ -2312,113 +2576,23 @@ channel_output_poll(void)
                  * We are only interested in channels that can have buffered
                  * incoming data.
                  */
-                if (compat13) {
-                        if (c->type != SSH_CHANNEL_OPEN &&
-                            c->type != SSH_CHANNEL_INPUT_DRAINING)
-                                continue;
-                } else {
-                        if (c->type != SSH_CHANNEL_OPEN)
-                                continue;
-                }
-                if (compat20 &&
-                    (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
+                if (c->type != SSH_CHANNEL_OPEN)
+                        continue;
+                if ((c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
                         /* XXX is this true? */
-                        debug3("channel %d: will not send data after close", c->self);
+                        debug3("channel %d: will not send data after close",
+                            c->self);
                         continue;
                 }
 
                 /* Get the amount of buffered data for this channel. */
-                if ((c->istate == CHAN_INPUT_OPEN ||
-                    c->istate == CHAN_INPUT_WAIT_DRAIN) &&
-                    (len = buffer_len(&c->input)) > 0) {
-                        if (c->datagram) {
-                                if (len > 0) {
-                                        u_char *data;
-                                        u_int dlen;
-
-                                        data = buffer_get_string(&c->input,
-                                            &dlen);
-                                        if (dlen > c->remote_window ||
-                                            dlen > c->remote_maxpacket) {
-                                                debug("channel %d: datagram "
-                                                    "too big for channel",
-                                                    c->self);
-                                                free(data);
-                                                continue;
-                                        }
-                                        packet_start(SSH2_MSG_CHANNEL_DATA);
-                                        packet_put_int(c->remote_id);
-                                        packet_put_string(data, dlen);
-                                        packet_send();
-                                        c->remote_window -= dlen;
-                                        free(data);
-                                }
-                                continue;
-                        }
-                        /*
-                         * Send some data for the other side over the secure
-                         * connection.
-                         */
-                        if (compat20) {
-                                if (len > c->remote_window)
-                                        len = c->remote_window;
-                                if (len > c->remote_maxpacket)
-                                        len = c->remote_maxpacket;
-                        } else {
-                                if (packet_is_interactive()) {
-                                        if (len > 1024)
-                                                len = 512;
-                                } else {
-                                        /* Keep the packets at reasonable size. */
-                                        if (len > packet_get_maxsize()/2)
-                                                len = packet_get_maxsize()/2;
-                                }
-                        }
-                        if (len > 0) {
-                                packet_start(compat20 ?
-                                    SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
-                                packet_put_int(c->remote_id);
-                                packet_put_string(buffer_ptr(&c->input), len);
-                                packet_send();
-                                buffer_consume(&c->input, len);
-                                c->remote_window -= len;
-                        }
-                } else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
-                        if (compat13)
-                                fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
-                        /*
-                         * input-buffer is empty and read-socket shutdown:
-                         * tell peer, that we will not send more data: send IEOF.
-                         * hack for extended data: delay EOF if EFD still in use.
-                         */
-                        if (CHANNEL_EFD_INPUT_ACTIVE(c))
-                                debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
-                                    c->self, c->efd, buffer_len(&c->extended));
-                        else
-                                chan_ibuf_empty(c);
-                }
+                if (c->istate == CHAN_INPUT_OPEN ||
+                    c->istate == CHAN_INPUT_WAIT_DRAIN)
+                        channel_output_poll_input_open(ssh, c);
                 /* Send extended data, i.e. stderr */
-                if (compat20 &&
-                    !(c->flags & CHAN_EOF_SENT) &&
-                    c->remote_window > 0 &&
-                    (len = buffer_len(&c->extended)) > 0 &&
-                    c->extended_usage == CHAN_EXTENDED_READ) {
-                        debug2("channel %d: rwin %u elen %u euse %d",
-                            c->self, c->remote_window, buffer_len(&c->extended),
-                            c->extended_usage);
-                        if (len > c->remote_window)
-                                len = c->remote_window;
-                        if (len > c->remote_maxpacket)
-                                len = c->remote_maxpacket;
-                        packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
-                        packet_put_int(c->remote_id);
-                        packet_put_int(SSH2_EXTENDED_DATA_STDERR);
-                        packet_put_string(buffer_ptr(&c->extended), len);
-                        packet_send();
-                        buffer_consume(&c->extended, len);
-                        c->remote_window -= len;
-                        debug2("channel %d: sent ext data %d", c->self, len);
-                }
+                if (!(c->flags & CHAN_EOF_SENT) &&
+                    c->extended_usage == CHAN_EXTENDED_READ)
+                        channel_output_poll_extended_read(ssh, c);
         }
 }
 
@@ -2463,20 +2637,19 @@ channel_output_poll(void)
  * on channel creation.
  */
 int
-channel_proxy_downstream(Channel *downstream)
+channel_proxy_downstream(struct ssh *ssh, Channel *downstream)
 {
         Channel *c = NULL;
-        struct ssh *ssh = active_state;
         struct sshbuf *original = NULL, *modified = NULL;
         const u_char *cp;
         char *ctype = NULL, *listen_host = NULL;
         u_char type;
         size_t have;
-        int ret = -1, r, idx;
+        int ret = -1, r;
         u_int id, remote_id, listen_port;
 
-        /* sshbuf_dump(&downstream->input, stderr); */
-        if ((r = sshbuf_get_string_direct(&downstream->input, &cp, &have))
+        /* sshbuf_dump(downstream->input, stderr); */
+        if ((r = sshbuf_get_string_direct(downstream->input, &cp, &have))
             != 0) {
                 error("%s: malformed message: %s", __func__, ssh_err(r));
                 return -1;
@@ -2505,7 +2678,7 @@ channel_proxy_downstream(Channel *downstream)
                         error("%s: parse error %s", __func__, ssh_err(r));
                         goto out;
                 }
-                c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
+                c = channel_new(ssh, "mux proxy", SSH_CHANNEL_MUX_PROXY,
                    -1, -1, -1, 0, 0, 0, ctype, 1);
                 c->mux_ctx = downstream;        /* point to mux client */
                 c->mux_downstream_id = id;      /* original downstream id */
@@ -2513,7 +2686,7 @@ channel_proxy_downstream(Channel *downstream)
                     (r = sshbuf_put_u32(modified, c->self)) != 0 ||
                     (r = sshbuf_putb(modified, original)) != 0) {
                         error("%s: compose error %s", __func__, ssh_err(r));
-                        channel_free(c);
+                        channel_free(ssh, c);
                         goto out;
                 }
                 break;
@@ -2532,16 +2705,17 @@ channel_proxy_downstream(Channel *downstream)
                         error("%s: parse error %s", __func__, ssh_err(r));
                         goto out;
                 }
-                c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
+                c = channel_new(ssh, "mux proxy", SSH_CHANNEL_MUX_PROXY,
                    -1, -1, -1, 0, 0, 0, "mux-down-connect", 1);
                 c->mux_ctx = downstream;        /* point to mux client */
                 c->mux_downstream_id = id;
                 c->remote_id = remote_id;
+                c->have_remote_id = 1;
                 if ((r = sshbuf_put_u32(modified, remote_id)) != 0 ||
                     (r = sshbuf_put_u32(modified, c->self)) != 0 ||
                     (r = sshbuf_putb(modified, original)) != 0) {
                         error("%s: compose error %s", __func__, ssh_err(r));
-                        channel_free(c);
+                        channel_free(ssh, c);
                         goto out;
                 }
                 break;
@@ -2570,23 +2744,17 @@ channel_proxy_downstream(Channel *downstream)
                         goto out;
                 }
                 /* Record that connection to this host/port is permitted. */
-                permitted_opens = xreallocarray(permitted_opens,
-                    num_permitted_opens + 1, sizeof(*permitted_opens));
-                idx = num_permitted_opens++;
-                permitted_opens[idx].host_to_connect = xstrdup("<mux>");
-                permitted_opens[idx].port_to_connect = -1;
-                permitted_opens[idx].listen_host = listen_host;
-                permitted_opens[idx].listen_port = (int)listen_port;
-                permitted_opens[idx].downstream = downstream;
+                fwd_perm_list_add(ssh, FWDPERM_USER, "<mux>", -1,
+                    listen_host, NULL, (int)listen_port, downstream);
                 listen_host = NULL;
                 break;
         case SSH2_MSG_CHANNEL_CLOSE:
                 if (have < 4)
                         break;
                 remote_id = PEEK_U32(cp);
-                if ((c = channel_by_remote_id(remote_id)) != NULL) {
+                if ((c = channel_by_remote_id(ssh, remote_id)) != NULL) {
                         if (c->flags & CHAN_CLOSE_RCVD)
-                                channel_free(c);
+                                channel_free(ssh, c);
                         else
                                 c->flags |= CHAN_CLOSE_SENT;
                 }
@@ -2623,9 +2791,8 @@ channel_proxy_downstream(Channel *downstream)
  * replaces local (proxy) channel ID with downstream channel ID.
  */
 int
-channel_proxy_upstream(Channel *c, int type, u_int32_t seq, void *ctxt)
+channel_proxy_upstream(Channel *c, int type, u_int32_t seq, struct ssh *ssh)
 {
-        struct ssh *ssh = active_state;
         struct sshbuf *b = NULL;
         Channel *downstream;
         const u_char *cp = NULL;
@@ -2674,7 +2841,7 @@ channel_proxy_upstream(Channel *c, int type, u_int32_t seq, void *ctxt)
             (r = sshbuf_put_u8(b, type)) != 0 ||
             (r = sshbuf_put_u32(b, c->mux_downstream_id)) != 0 ||
             (r = sshbuf_put(b, cp, len)) != 0 ||
-            (r = sshbuf_put_stringb(&downstream->output, b)) != 0) {
+            (r = sshbuf_put_stringb(downstream->output, b)) != 0) {
                 error("%s: compose for muxclient %s", __func__, ssh_err(r));
                 goto out;
         }
@@ -2687,12 +2854,14 @@ channel_proxy_upstream(Channel *c, int type, u_int32_t seq, void *ctxt)
         switch (type) {
         case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
                 /* record remote_id for SSH2_MSG_CHANNEL_CLOSE */
-                if (cp && len > 4)
+                if (cp && len > 4) {
                         c->remote_id = PEEK_U32(cp);
+                        c->have_remote_id = 1;
+                }
                 break;
         case SSH2_MSG_CHANNEL_CLOSE:
                 if (c->flags & CHAN_CLOSE_SENT)
-                        channel_free(c);
+                        channel_free(ssh, c);
                 else
                         c->flags |= CHAN_CLOSE_RCVD;
                 break;
@@ -2703,257 +2872,221 @@ channel_proxy_upstream(Channel *c, int type, u_int32_t seq, void *ctxt)
 
 /* -- protocol input */
 
-/* ARGSUSED */
+/* Parse a channel ID from the current packet */
+static int
+channel_parse_id(struct ssh *ssh, const char *where, const char *what)
+{
+        u_int32_t id;
+        int r;
+
+        if ((r = sshpkt_get_u32(ssh, &id)) != 0) {
+                error("%s: parse id: %s", where, ssh_err(r));
+                ssh_packet_disconnect(ssh, "Invalid %s message", what);
+        }
+        if (id > INT_MAX) {
+                error("%s: bad channel id %u: %s", where, id, ssh_err(r));
+                ssh_packet_disconnect(ssh, "Invalid %s channel id", what);
+        }
+        return (int)id;
+}
+
+/* Lookup a channel from an ID in the current packet */
+static Channel *
+channel_from_packet_id(struct ssh *ssh, const char *where, const char *what)
+{
+        int id = channel_parse_id(ssh, where, what);
+        Channel *c;
+
+        if ((c = channel_lookup(ssh, id)) == NULL) {
+                ssh_packet_disconnect(ssh,
+                    "%s packet referred to nonexistent channel %d", what, id);
+        }
+        return c;
+}
+
 int
-channel_input_data(int type, u_int32_t seq, void *ctxt)
+channel_input_data(int type, u_int32_t seq, struct ssh *ssh)
 {
-        int id;
         const u_char *data;
-        u_int data_len, win_len;
-        Channel *c;
+        size_t data_len, win_len;
+        Channel *c = channel_from_packet_id(ssh, __func__, "data");
+        int r;
 
-        /* Get the channel number and verify it. */
-        id = packet_get_int();
-        c = channel_lookup(id);
-        if (c == NULL)
-                packet_disconnect("Received data for nonexistent channel %d.", id);
-        if (channel_proxy_upstream(c, type, seq, ctxt))
+        if (channel_proxy_upstream(c, type, seq, ssh))
                 return 0;
 
         /* Ignore any data for non-open channels (might happen on close) */
         if (c->type != SSH_CHANNEL_OPEN &&
+            c->type != SSH_CHANNEL_RDYNAMIC_OPEN &&
+            c->type != SSH_CHANNEL_RDYNAMIC_FINISH &&
             c->type != SSH_CHANNEL_X11_OPEN)
                 return 0;
 
         /* Get the data. */
-        data = packet_get_string_ptr(&data_len);
+        if ((r = sshpkt_get_string_direct(ssh, &data, &data_len)) != 0)
+                fatal("%s: channel %d: get data: %s", __func__,
+                    c->self, ssh_err(r));
+        ssh_packet_check_eom(ssh);
+
         win_len = data_len;
         if (c->datagram)
                 win_len += 4;  /* string length header */
 
         /*
-         * Ignore data for protocol > 1.3 if output end is no longer open.
-         * For protocol 2 the sending side is reducing its window as it sends
-         * data, so we must 'fake' consumption of the data in order to ensure
-         * that window updates are sent back.  Otherwise the connection might
-         * deadlock.
+         * The sending side reduces its window as it sends data, so we
+         * must 'fake' consumption of the data in order to ensure that window
+         * updates are sent back. Otherwise the connection might deadlock.
          */
-        if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
-                if (compat20) {
-                        c->local_window -= win_len;
-                        c->local_consumed += win_len;
-                }
+        if (c->ostate != CHAN_OUTPUT_OPEN) {
+                c->local_window -= win_len;
+                c->local_consumed += win_len;
                 return 0;
         }
 
-        if (compat20) {
-                if (win_len > c->local_maxpacket) {
-                        logit("channel %d: rcvd big packet %d, maxpack %d",
-                            c->self, win_len, c->local_maxpacket);
-                }
-                if (win_len > c->local_window) {
-                        logit("channel %d: rcvd too much data %d, win %d",
-                            c->self, win_len, c->local_window);
-                        return 0;
-                }
-                c->local_window -= win_len;
+        if (win_len > c->local_maxpacket) {
+                logit("channel %d: rcvd big packet %zu, maxpack %u",
+                    c->self, win_len, c->local_maxpacket);
+                return 0;
         }
-        if (c->datagram)
-                buffer_put_string(&c->output, data, data_len);
-        else
-                buffer_append(&c->output, data, data_len);
-        packet_check_eom();
+        if (win_len > c->local_window) {
+                logit("channel %d: rcvd too much data %zu, win %u",
+                    c->self, win_len, c->local_window);
+                return 0;
+        }
+        c->local_window -= win_len;
+
+        if (c->datagram) {
+                if ((r = sshbuf_put_string(c->output, data, data_len)) != 0)
+                        fatal("%s: channel %d: append datagram: %s",
+                            __func__, c->self, ssh_err(r));
+        } else if ((r = sshbuf_put(c->output, data, data_len)) != 0)
+                fatal("%s: channel %d: append data: %s",
+                    __func__, c->self, ssh_err(r));
+
         return 0;
 }
 
-/* ARGSUSED */
 int
-channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
+channel_input_extended_data(int type, u_int32_t seq, struct ssh *ssh)
 {
-        int id;
-        char *data;
-        u_int data_len, tcode;
-        Channel *c;
-
-        /* Get the channel number and verify it. */
-        id = packet_get_int();
-        c = channel_lookup(id);
+        const u_char *data;
+        size_t data_len;
+        u_int32_t tcode;
+        Channel *c = channel_from_packet_id(ssh, __func__, "extended data");
+        int r;
 
-        if (c == NULL)
-                packet_disconnect("Received extended_data for bad channel %d.", id);
-        if (channel_proxy_upstream(c, type, seq, ctxt))
+        if (channel_proxy_upstream(c, type, seq, ssh))
                 return 0;
         if (c->type != SSH_CHANNEL_OPEN) {
-                logit("channel %d: ext data for non open", id);
+                logit("channel %d: ext data for non open", c->self);
                 return 0;
         }
         if (c->flags & CHAN_EOF_RCVD) {
                 if (datafellows & SSH_BUG_EXTEOF)
-                        debug("channel %d: accepting ext data after eof", id);
+                        debug("channel %d: accepting ext data after eof",
+                            c->self);
                 else
-                        packet_disconnect("Received extended_data after EOF "
-                            "on channel %d.", id);
+                        ssh_packet_disconnect(ssh, "Received extended_data "
+                            "after EOF on channel %d.", c->self);
+        }
+
+        if ((r = sshpkt_get_u32(ssh, &tcode)) != 0) {
+                error("%s: parse tcode: %s", __func__, ssh_err(r));
+                ssh_packet_disconnect(ssh, "Invalid extended_data message");
         }
-        tcode = packet_get_int();
         if (c->efd == -1 ||
             c->extended_usage != CHAN_EXTENDED_WRITE ||
             tcode != SSH2_EXTENDED_DATA_STDERR) {
                 logit("channel %d: bad ext data", c->self);
                 return 0;
         }
-        data = packet_get_string(&data_len);
-        packet_check_eom();
+        if ((r = sshpkt_get_string_direct(ssh, &data, &data_len)) != 0) {
+                error("%s: parse data: %s", __func__, ssh_err(r));
+                ssh_packet_disconnect(ssh, "Invalid extended_data message");
+        }
+        ssh_packet_check_eom(ssh);
+
         if (data_len > c->local_window) {
-                logit("channel %d: rcvd too much extended_data %d, win %d",
+                logit("channel %d: rcvd too much extended_data %zu, win %u",
                     c->self, data_len, c->local_window);
-                free(data);
                 return 0;
         }
-        debug2("channel %d: rcvd ext data %d", c->self, data_len);
+        debug2("channel %d: rcvd ext data %zu", c->self, data_len);
+        /* XXX sshpkt_getb? */
+        if ((r = sshbuf_put(c->extended, data, data_len)) != 0)
+                error("%s: append: %s", __func__, ssh_err(r));
         c->local_window -= data_len;
-        buffer_append(&c->extended, data, data_len);
-        free(data);
         return 0;
 }
 
-/* ARGSUSED */
 int
-channel_input_ieof(int type, u_int32_t seq, void *ctxt)
+channel_input_ieof(int type, u_int32_t seq, struct ssh *ssh)
 {
-        int id;
-        Channel *c;
+        Channel *c = channel_from_packet_id(ssh, __func__, "ieof");
 
-        id = packet_get_int();
-        packet_check_eom();
-        c = channel_lookup(id);
-        if (c == NULL)
-                packet_disconnect("Received ieof for nonexistent channel %d.", id);
-        if (channel_proxy_upstream(c, type, seq, ctxt))
+        ssh_packet_check_eom(ssh);
+
+        if (channel_proxy_upstream(c, type, seq, ssh))
                 return 0;
-        chan_rcvd_ieof(c);
+        chan_rcvd_ieof(ssh, c);
 
         /* XXX force input close */
         if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
                 debug("channel %d: FORCE input drain", c->self);
                 c->istate = CHAN_INPUT_WAIT_DRAIN;
-                if (buffer_len(&c->input) == 0)
-                        chan_ibuf_empty(c);
-        }
-        return 0;
-}
-
-/* ARGSUSED */
-int
-channel_input_close(int type, u_int32_t seq, void *ctxt)
-{
-        int id;
-        Channel *c;
-
-        id = packet_get_int();
-        packet_check_eom();
-        c = channel_lookup(id);
-        if (c == NULL)
-                packet_disconnect("Received close for nonexistent channel %d.", id);
-        if (channel_proxy_upstream(c, type, seq, ctxt))
-                return 0;
-        /*
-         * Send a confirmation that we have closed the channel and no more
-         * data is coming for it.
-         */
-        packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
-        packet_put_int(c->remote_id);
-        packet_send();
-
-        /*
-         * If the channel is in closed state, we have sent a close request,
-         * and the other side will eventually respond with a confirmation.
-         * Thus, we cannot free the channel here, because then there would be
-         * no-one to receive the confirmation.  The channel gets freed when
-         * the confirmation arrives.
-         */
-        if (c->type != SSH_CHANNEL_CLOSED) {
-                /*
-                 * Not a closed channel - mark it as draining, which will
-                 * cause it to be freed later.
-                 */
-                buffer_clear(&c->input);
-                c->type = SSH_CHANNEL_OUTPUT_DRAINING;
+                if (sshbuf_len(c->input) == 0)
+                        chan_ibuf_empty(ssh, c);
         }
         return 0;
 }
 
-/* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
-/* ARGSUSED */
 int
-channel_input_oclose(int type, u_int32_t seq, void *ctxt)
+channel_input_oclose(int type, u_int32_t seq, struct ssh *ssh)
 {
-        int id = packet_get_int();
-        Channel *c = channel_lookup(id);
+        Channel *c = channel_from_packet_id(ssh, __func__, "oclose");
 
-        if (c == NULL)
-                packet_disconnect("Received oclose for nonexistent channel %d.", id);
-        if (channel_proxy_upstream(c, type, seq, ctxt))
-                return 0;
-        packet_check_eom();
-        chan_rcvd_oclose(c);
-        return 0;
-}
-
-/* ARGSUSED */
-int
-channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
-{
-        int id = packet_get_int();
-        Channel *c = channel_lookup(id);
-
-        if (c == NULL)
-                packet_disconnect("Received close confirmation for "
-                    "out-of-range channel %d.", id);
-        if (channel_proxy_upstream(c, type, seq, ctxt))
+        if (channel_proxy_upstream(c, type, seq, ssh))
                 return 0;
-        packet_check_eom();
-        if (c->type != SSH_CHANNEL_CLOSED && c->type != SSH_CHANNEL_ABANDONED)
-                packet_disconnect("Received close confirmation for "
-                    "non-closed channel %d (type %d).", id, c->type);
-        channel_free(c);
+        ssh_packet_check_eom(ssh);
+        chan_rcvd_oclose(ssh, c);
         return 0;
 }
 
-/* ARGSUSED */
 int
-channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
+channel_input_open_confirmation(int type, u_int32_t seq, struct ssh *ssh)
 {
-        int id, remote_id;
-        Channel *c;
-
-        id = packet_get_int();
-        c = channel_lookup(id);
+        Channel *c = channel_from_packet_id(ssh, __func__, "open confirmation");
+        u_int32_t remote_window, remote_maxpacket;
+        int r;
 
-        if (c==NULL)
-                packet_disconnect("Received open confirmation for "
-                    "unknown channel %d.", id);
-        if (channel_proxy_upstream(c, type, seq, ctxt))
+        if (channel_proxy_upstream(c, type, seq, ssh))
                 return 0;
         if (c->type != SSH_CHANNEL_OPENING)
                 packet_disconnect("Received open confirmation for "
-                    "non-opening channel %d.", id);
-        remote_id = packet_get_int();
-        /* Record the remote channel number and mark that the channel is now open. */
-        c->remote_id = remote_id;
-        c->type = SSH_CHANNEL_OPEN;
+                    "non-opening channel %d.", c->self);
+        /*
+         * Record the remote channel number and mark that the channel
+         * is now open.
+         */
+        if ((r = sshpkt_get_u32(ssh, &c->remote_id)) != 0 ||
+            (r = sshpkt_get_u32(ssh, &remote_window)) != 0 ||
+            (r = sshpkt_get_u32(ssh, &remote_maxpacket)) != 0) {
+                error("%s: window/maxpacket: %s", __func__, ssh_err(r));
+                packet_disconnect("Invalid open confirmation message");
+        }
+        ssh_packet_check_eom(ssh);
 
-        if (compat20) {
-                c->remote_window = packet_get_int();
-                c->remote_maxpacket = packet_get_int();
-                if (c->open_confirm) {
-                        debug2("callback start");
-                        c->open_confirm(c->self, 1, c->open_confirm_ctx);
-                        debug2("callback done");
-                }
-                debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
-                    c->remote_window, c->remote_maxpacket);
+        c->have_remote_id = 1;
+        c->remote_window = remote_window;
+        c->remote_maxpacket = remote_maxpacket;
+        c->type = SSH_CHANNEL_OPEN;
+        if (c->open_confirm) {
+                debug2("%s: channel %d: callback start", __func__, c->self);
+                c->open_confirm(ssh, c->self, 1, c->open_confirm_ctx);
+                debug2("%s: channel %d: callback done", __func__, c->self);
         }
-        packet_check_eom();
+        debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
+            c->remote_window, c->remote_maxpacket);
         return 0;
 }
 
@@ -2973,134 +3106,97 @@ reason2txt(int reason)
         return "unknown reason";
 }
 
-/* ARGSUSED */
 int
-channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
+channel_input_open_failure(int type, u_int32_t seq, struct ssh *ssh)
 {
-        int id, reason;
-        char *msg = NULL, *lang = NULL;
-        Channel *c;
-
-        id = packet_get_int();
-        c = channel_lookup(id);
+        Channel *c = channel_from_packet_id(ssh, __func__, "open failure");
+        u_int32_t reason;
+        char *msg = NULL;
+        int r;
 
-        if (c==NULL)
-                packet_disconnect("Received open failure for "
-                    "unknown channel %d.", id);
-        if (channel_proxy_upstream(c, type, seq, ctxt))
+        if (channel_proxy_upstream(c, type, seq, ssh))
                 return 0;
         if (c->type != SSH_CHANNEL_OPENING)
                 packet_disconnect("Received open failure for "
-                    "non-opening channel %d.", id);
-        if (compat20) {
-                reason = packet_get_int();
-                if (!(datafellows & SSH_BUG_OPENFAILURE)) {
-                        msg  = packet_get_string(NULL);
-                        lang = packet_get_string(NULL);
-                }
-                logit("channel %d: open failed: %s%s%s", id,
-                    reason2txt(reason), msg ? ": ": "", msg ? msg : "");
-                free(msg);
-                free(lang);
-                if (c->open_confirm) {
-                        debug2("callback start");
-                        c->open_confirm(c->self, 0, c->open_confirm_ctx);
-                        debug2("callback done");
+                    "non-opening channel %d.", c->self);
+        if ((r = sshpkt_get_u32(ssh, &reason)) != 0) {
+                error("%s: reason: %s", __func__, ssh_err(r));
+                packet_disconnect("Invalid open failure message");
+        }
+        if ((datafellows & SSH_BUG_OPENFAILURE) == 0) {
+                /* skip language */
+                if ((r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
+                    (r = sshpkt_get_string_direct(ssh, NULL, NULL)) != 0) {
+                        error("%s: message/lang: %s", __func__, ssh_err(r));
+                        packet_disconnect("Invalid open failure message");
                 }
         }
-        packet_check_eom();
+        ssh_packet_check_eom(ssh);
+        logit("channel %d: open failed: %s%s%s", c->self,
+            reason2txt(reason), msg ? ": ": "", msg ? msg : "");
+        free(msg);
+        if (c->open_confirm) {
+                debug2("%s: channel %d: callback start", __func__, c->self);
+                c->open_confirm(ssh, c->self, 0, c->open_confirm_ctx);
+                debug2("%s: channel %d: callback done", __func__, c->self);
+        }
         /* Schedule the channel for cleanup/deletion. */
-        chan_mark_dead(c);
+        chan_mark_dead(ssh, c);
         return 0;
 }
 
-/* ARGSUSED */
 int
-channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
+channel_input_window_adjust(int type, u_int32_t seq, struct ssh *ssh)
 {
+        int id = channel_parse_id(ssh, __func__, "window adjust");
         Channel *c;
-        int id;
-        u_int adjust, tmp;
-
-        if (!compat20)
-                return 0;
-
-        /* Get the channel number and verify it. */
-        id = packet_get_int();
-        c = channel_lookup(id);
+        u_int32_t adjust;
+        u_int new_rwin;
+        int r;
 
-        if (c == NULL) {
+        if ((c = channel_lookup(ssh, id)) == NULL) {
                 logit("Received window adjust for non-open channel %d.", id);
                 return 0;
         }
-        if (channel_proxy_upstream(c, type, seq, ctxt))
+
+        if (channel_proxy_upstream(c, type, seq, ssh))
                 return 0;
-        adjust = packet_get_int();
-        packet_check_eom();
-        debug2("channel %d: rcvd adjust %u", id, adjust);
-        if ((tmp = c->remote_window + adjust) < c->remote_window)
+        if ((r = sshpkt_get_u32(ssh, &adjust)) != 0) {
+                error("%s: adjust: %s", __func__, ssh_err(r));
+                packet_disconnect("Invalid window adjust message");
+        }
+        ssh_packet_check_eom(ssh);
+        debug2("channel %d: rcvd adjust %u", c->self, adjust);
+        if ((new_rwin = c->remote_window + adjust) < c->remote_window) {
                 fatal("channel %d: adjust %u overflows remote window %u",
-                    id, adjust, c->remote_window);
-        c->remote_window = tmp;
-        return 0;
-}
-
-/* ARGSUSED */
-int
-channel_input_port_open(int type, u_int32_t seq, void *ctxt)
-{
-        Channel *c = NULL;
-        u_short host_port;
-        char *host, *originator_string;
-        int remote_id;
-
-        remote_id = packet_get_int();
-        host = packet_get_string(NULL);
-        host_port = packet_get_int();
-
-        if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
-                originator_string = packet_get_string(NULL);
-        } else {
-                originator_string = xstrdup("unknown (remote did not supply name)");
+                    c->self, adjust, c->remote_window);
         }
-        packet_check_eom();
-        c = channel_connect_to_port(host, host_port,
-            "connected socket", originator_string, NULL, NULL);
-        free(originator_string);
-        free(host);
-        if (c == NULL) {
-                packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
-                packet_put_int(remote_id);
-                packet_send();
-        } else
-                c->remote_id = remote_id;
+        c->remote_window = new_rwin;
         return 0;
 }
 
-/* ARGSUSED */
 int
-channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
+channel_input_status_confirm(int type, u_int32_t seq, struct ssh *ssh)
 {
+        int id = channel_parse_id(ssh, __func__, "status confirm");
         Channel *c;
         struct channel_confirm *cc;
-        int id;
 
         /* Reset keepalive timeout */
         packet_set_alive_timeouts(0);
 
-        id = packet_get_int();
-        debug2("channel_input_status_confirm: type %d id %d", type, id);
+        debug2("%s: type %d id %d", __func__, type, id);
 
-        if ((c = channel_lookup(id)) == NULL) {
-                logit("channel_input_status_confirm: %d: unknown", id);
+        if ((c = channel_lookup(ssh, id)) == NULL) {
+                logit("%s: %d: unknown", __func__, id);
                 return 0;
-        }       
-        if (channel_proxy_upstream(c, type, seq, ctxt))
+        }
+        if (channel_proxy_upstream(c, type, seq, ssh))
                 return 0;
-        packet_check_eom();
+        ssh_packet_check_eom(ssh);
         if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
                 return 0;
-        cc->cb(type, c, cc->ctx);
+        cc->cb(ssh, type, c, cc->ctx);
         TAILQ_REMOVE(&c->status_confirms, cc, entry);
         explicit_bzero(cc, sizeof(*cc));
         free(cc);
@@ -3110,9 +3206,9 @@ channel_input_status_confirm(int type, u_int32_t seq, void *ctxt)
 /* -- tcp forwarding */
 
 void
-channel_set_af(int af)
+channel_set_af(struct ssh *ssh, int af)
 {
-        IPv4or6 = af;
+        ssh->chanctxt->IPv4or6 = af;
 }
 
 
@@ -3180,8 +3276,9 @@ channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
 }
 
 static int
-channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
-    int *allocated_listen_port, struct ForwardOptions *fwd_opts)
+channel_setup_fwd_listener_tcpip(struct ssh *ssh, int type,
+    struct Forward *fwd, int *allocated_listen_port,
+    struct ForwardOptions *fwd_opts)
 {
         Channel *c;
         int sock, r, success = 0, wildcard = 0, is_client;
@@ -3218,7 +3315,7 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
          * set to NULL and hints.ai_flags is not AI_PASSIVE
          */
         memset(&hints, 0, sizeof(hints));
-        hints.ai_family = IPv4or6;
+        hints.ai_family = ssh->chanctxt->IPv4or6;
         hints.ai_flags = wildcard ? AI_PASSIVE : 0;
         hints.ai_socktype = SOCK_STREAM;
         snprintf(strport, sizeof strport, "%d", fwd->listen_port);
@@ -3252,12 +3349,14 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
                  * If allocating a port for -R forwards, then use the
                  * same port for all address families.
                  */
-                if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
-                    allocated_listen_port != NULL && *allocated_listen_port > 0)
+                if (type == SSH_CHANNEL_RPORT_LISTENER &&
+                    fwd->listen_port == 0 && allocated_listen_port != NULL &&
+                    *allocated_listen_port > 0)
                         *lport_p = htons(*allocated_listen_port);
 
                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
-                    strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
+                    strport, sizeof(strport),
+                    NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
                         error("%s: getnameinfo failed", __func__);
                         continue;
                 }
@@ -3278,7 +3377,10 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 
                 /* Bind the socket to the address. */
                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
-                        /* address can be in use ipv6 address is already bound */
+                        /*
+                         * address can be in if use ipv6 address is
+                         * already bound
+                         */
                         if (!ai->ai_next)
                                 error("bind: %.100s", strerror(errno));
                         else
@@ -3298,7 +3400,8 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
                  * fwd->listen_port == 0 requests a dynamically allocated port -
                  * record what we got.
                  */
-                if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
+                if (type == SSH_CHANNEL_RPORT_LISTENER &&
+                    fwd->listen_port == 0 &&
                     allocated_listen_port != NULL &&
                     *allocated_listen_port == 0) {
                         *allocated_listen_port = get_local_port(sock);
@@ -3307,7 +3410,7 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
                 }
 
                 /* Allocate a channel number for the socket. */
-                c = channel_new("port listener", type, sock, sock, -1,
+                c = channel_new(ssh, "port listener", type, sock, sock, -1,
                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
                     0, "port listener", 1);
                 c->path = xstrdup(host);
@@ -3328,8 +3431,8 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 }
 
 static int
-channel_setup_fwd_listener_streamlocal(int type, struct Forward *fwd,
-    struct ForwardOptions *fwd_opts)
+channel_setup_fwd_listener_streamlocal(struct ssh *ssh, int type,
+    struct Forward *fwd, struct ForwardOptions *fwd_opts)
 {
         struct sockaddr_un sunaddr;
         const char *path;
@@ -3391,7 +3494,7 @@ channel_setup_fwd_listener_streamlocal(int type, struct Forward *fwd,
         debug("Local forwarding listening on path %s.", fwd->listen_path);
 
         /* Allocate a channel number for the socket. */
-        c = channel_new("unix listener", type, sock, sock, -1,
+        c = channel_new(ssh, "unix listener", type, sock, sock, -1,
             CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
             0, "unix listener", 1);
         c->path = xstrdup(path);
@@ -3402,66 +3505,71 @@ channel_setup_fwd_listener_streamlocal(int type, struct Forward *fwd,
 }
 
 static int
-channel_cancel_rport_listener_tcpip(const char *host, u_short port)
+channel_cancel_rport_listener_tcpip(struct ssh *ssh,
+    const char *host, u_short port)
 {
         u_int i;
         int found = 0;
 
-        for (i = 0; i < channels_alloc; i++) {
-                Channel *c = channels[i];
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                Channel *c = ssh->chanctxt->channels[i];
                 if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
                         continue;
                 if (strcmp(c->path, host) == 0 && c->listening_port == port) {
                         debug2("%s: close channel %d", __func__, i);
-                        channel_free(c);
+                        channel_free(ssh, c);
                         found = 1;
                 }
         }
 
-        return (found);
+        return found;
 }
 
 static int
-channel_cancel_rport_listener_streamlocal(const char *path)
+channel_cancel_rport_listener_streamlocal(struct ssh *ssh, const char *path)
 {
         u_int i;
         int found = 0;
 
-        for (i = 0; i < channels_alloc; i++) {
-                Channel *c = channels[i];
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                Channel *c = ssh->chanctxt->channels[i];
                 if (c == NULL || c->type != SSH_CHANNEL_RUNIX_LISTENER)
                         continue;
                 if (c->path == NULL)
                         continue;
                 if (strcmp(c->path, path) == 0) {
                         debug2("%s: close channel %d", __func__, i);
-                        channel_free(c);
+                        channel_free(ssh, c);
                         found = 1;
                 }
         }
 
-        return (found);
+        return found;
 }
 
 int
-channel_cancel_rport_listener(struct Forward *fwd)
+channel_cancel_rport_listener(struct ssh *ssh, struct Forward *fwd)
 {
-        if (fwd->listen_path != NULL)
-                return channel_cancel_rport_listener_streamlocal(fwd->listen_path);
-        else
-                return channel_cancel_rport_listener_tcpip(fwd->listen_host, fwd->listen_port);
+        if (fwd->listen_path != NULL) {
+                return channel_cancel_rport_listener_streamlocal(ssh,
+                    fwd->listen_path);
+        } else {
+                return channel_cancel_rport_listener_tcpip(ssh,
+                    fwd->listen_host, fwd->listen_port);
+        }
 }
 
 static int
-channel_cancel_lport_listener_tcpip(const char *lhost, u_short lport,
-    int cport, struct ForwardOptions *fwd_opts)
+channel_cancel_lport_listener_tcpip(struct ssh *ssh,
+    const char *lhost, u_short lport, int cport,
+    struct ForwardOptions *fwd_opts)
 {
         u_int i;
         int found = 0;
         const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, fwd_opts);
 
-        for (i = 0; i < channels_alloc; i++) {
-                Channel *c = channels[i];
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                Channel *c = ssh->chanctxt->channels[i];
                 if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
                         continue;
                 if (c->listening_port != lport)
@@ -3479,16 +3587,16 @@ channel_cancel_lport_listener_tcpip(const char *lhost, u_short lport,
                         continue;
                 if (addr == NULL || strcmp(c->listening_addr, addr) == 0) {
                         debug2("%s: close channel %d", __func__, i);
-                        channel_free(c);
+                        channel_free(ssh, c);
                         found = 1;
                 }
         }
 
-        return (found);
+        return found;
 }
 
 static int
-channel_cancel_lport_listener_streamlocal(const char *path)
+channel_cancel_lport_listener_streamlocal(struct ssh *ssh, const char *path)
 {
         u_int i;
         int found = 0;
@@ -3498,54 +3606,59 @@ channel_cancel_lport_listener_streamlocal(const char *path)
                 return 0;
         }
 
-        for (i = 0; i < channels_alloc; i++) {
-                Channel *c = channels[i];
+        for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+                Channel *c = ssh->chanctxt->channels[i];
                 if (c == NULL || c->type != SSH_CHANNEL_UNIX_LISTENER)
                         continue;
                 if (c->listening_addr == NULL)
                         continue;
                 if (strcmp(c->listening_addr, path) == 0) {
                         debug2("%s: close channel %d", __func__, i);
-                        channel_free(c);
+                        channel_free(ssh, c);
                         found = 1;
                 }
         }
 
-        return (found);
+        return found;
 }
 
 int
-channel_cancel_lport_listener(struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
+channel_cancel_lport_listener(struct ssh *ssh,
+    struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
 {
-        if (fwd->listen_path != NULL)
-                return channel_cancel_lport_listener_streamlocal(fwd->listen_path);
-        else
-                return channel_cancel_lport_listener_tcpip(fwd->listen_host, fwd->listen_port, cport, fwd_opts);
+        if (fwd->listen_path != NULL) {
+                return channel_cancel_lport_listener_streamlocal(ssh,
+                    fwd->listen_path);
+        } else {
+                return channel_cancel_lport_listener_tcpip(ssh,
+                    fwd->listen_host, fwd->listen_port, cport, fwd_opts);
+        }
 }
 
-/* protocol local port fwd, used by ssh (and sshd in v1) */
+/* protocol local port fwd, used by ssh */
 int
-channel_setup_local_fwd_listener(struct Forward *fwd, struct ForwardOptions *fwd_opts)
+channel_setup_local_fwd_listener(struct ssh *ssh,
+    struct Forward *fwd, struct ForwardOptions *fwd_opts)
 {
         if (fwd->listen_path != NULL) {
-                return channel_setup_fwd_listener_streamlocal(
+                return channel_setup_fwd_listener_streamlocal(ssh,
                     SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts);
         } else {
-                return channel_setup_fwd_listener_tcpip(SSH_CHANNEL_PORT_LISTENER,
-                    fwd, NULL, fwd_opts);
+                return channel_setup_fwd_listener_tcpip(ssh,
+                    SSH_CHANNEL_PORT_LISTENER, fwd, NULL, fwd_opts);
         }
 }
 
 /* protocol v2 remote port fwd, used by sshd */
 int
-channel_setup_remote_fwd_listener(struct Forward *fwd,
+channel_setup_remote_fwd_listener(struct ssh *ssh, struct Forward *fwd,
     int *allocated_listen_port, struct ForwardOptions *fwd_opts)
 {
         if (fwd->listen_path != NULL) {
-                return channel_setup_fwd_listener_streamlocal(
+                return channel_setup_fwd_listener_streamlocal(ssh,
                     SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts);
         } else {
-                return channel_setup_fwd_listener_tcpip(
+                return channel_setup_fwd_listener_tcpip(ssh,
                     SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port,
                     fwd_opts);
         }
@@ -3579,81 +3692,61 @@ channel_rfwd_bind_host(const char *listen_host)
  * channel_update_permitted_opens().
  */
 int
-channel_request_remote_forwarding(struct Forward *fwd)
+channel_request_remote_forwarding(struct ssh *ssh, struct Forward *fwd)
 {
-        int type, success = 0, idx = -1;
+        int r, success = 0, idx = -1;
+        char *host_to_connect, *listen_host, *listen_path;
+        int port_to_connect, listen_port;
 
         /* Send the forward request to the remote side. */
-        if (compat20) {
-                packet_start(SSH2_MSG_GLOBAL_REQUEST);
-                if (fwd->listen_path != NULL) {
-                    packet_put_cstring("streamlocal-forward@openssh.com");
-                    packet_put_char(1);         /* boolean: want reply */
-                    packet_put_cstring(fwd->listen_path);
-                } else {
-                    packet_put_cstring("tcpip-forward");
-                    packet_put_char(1);         /* boolean: want reply */
-                    packet_put_cstring(channel_rfwd_bind_host(fwd->listen_host));
-                    packet_put_int(fwd->listen_port);
-                }
-                packet_send();
-                packet_write_wait();
-                /* Assume that server accepts the request */
-                success = 1;
-        } else if (fwd->listen_path == NULL) {
-                packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
-                packet_put_int(fwd->listen_port);
-                packet_put_cstring(fwd->connect_host);
-                packet_put_int(fwd->connect_port);
-                packet_send();
-                packet_write_wait();
-
-                /* Wait for response from the remote side. */
-                type = packet_read();
-                switch (type) {
-                case SSH_SMSG_SUCCESS:
-                        success = 1;
-                        break;
-                case SSH_SMSG_FAILURE:
-                        break;
-                default:
-                        /* Unknown packet */
-                        packet_disconnect("Protocol error for port forward request:"
-                            "received packet type %d.", type);
-                }
+        if (fwd->listen_path != NULL) {
+                if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh,
+                    "streamlocal-forward@openssh.com")) != 0 ||
+                    (r = sshpkt_put_u8(ssh, 1)) != 0 || /* want reply */
+                    (r = sshpkt_put_cstring(ssh, fwd->listen_path)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0 ||
+                    (r = ssh_packet_write_wait(ssh)) != 0)
+                        fatal("%s: request streamlocal: %s",
+                            __func__, ssh_err(r));
         } else {
-                logit("Warning: Server does not support remote stream local forwarding.");
-        }
+                if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+                    (r = sshpkt_put_cstring(ssh, "tcpip-forward")) != 0 ||
+                    (r = sshpkt_put_u8(ssh, 1)) != 0 || /* want reply */
+                    (r = sshpkt_put_cstring(ssh,
+                    channel_rfwd_bind_host(fwd->listen_host))) != 0 ||
+                    (r = sshpkt_put_u32(ssh, fwd->listen_port)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0 ||
+                    (r = ssh_packet_write_wait(ssh)) != 0)
+                        fatal("%s: request tcpip-forward: %s",
+                            __func__, ssh_err(r));
+        }
+        /* Assume that server accepts the request */
+        success = 1;
         if (success) {
                 /* Record that connection to this host/port is permitted. */
-                permitted_opens = xreallocarray(permitted_opens,
-                    num_permitted_opens + 1, sizeof(*permitted_opens));
-                idx = num_permitted_opens++;
+                host_to_connect = listen_host = listen_path = NULL;
+                port_to_connect = listen_port = 0;
                 if (fwd->connect_path != NULL) {
-                        permitted_opens[idx].host_to_connect =
-                            xstrdup(fwd->connect_path);
-                        permitted_opens[idx].port_to_connect =
-                            PORT_STREAMLOCAL;
+                        host_to_connect = xstrdup(fwd->connect_path);
+                        port_to_connect = PORT_STREAMLOCAL;
                 } else {
-                        permitted_opens[idx].host_to_connect =
-                            xstrdup(fwd->connect_host);
-                        permitted_opens[idx].port_to_connect =
-                            fwd->connect_port;
+                        host_to_connect = xstrdup(fwd->connect_host);
+                        port_to_connect = fwd->connect_port;
                 }
                 if (fwd->listen_path != NULL) {
-                        permitted_opens[idx].listen_host = NULL;
-                        permitted_opens[idx].listen_path =
-                            xstrdup(fwd->listen_path);
-                        permitted_opens[idx].listen_port = PORT_STREAMLOCAL;
+                        listen_path = xstrdup(fwd->listen_path);
+                        listen_port = PORT_STREAMLOCAL;
                 } else {
-                        permitted_opens[idx].listen_host =
-                            fwd->listen_host ? xstrdup(fwd->listen_host) : NULL;
-                        permitted_opens[idx].listen_path = NULL;
-                        permitted_opens[idx].listen_port = fwd->listen_port;
+                        if (fwd->listen_host != NULL)
+                                listen_host = xstrdup(fwd->listen_host);
+                        listen_port = fwd->listen_port;
                 }
-                permitted_opens[idx].downstream = NULL;
+                idx = fwd_perm_list_add(ssh, FWDPERM_USER,
+                    host_to_connect, port_to_connect,
+                    listen_host, listen_path, listen_port, NULL);
         }
-        return (idx);
+        return idx;
 }
 
 static int
@@ -3718,36 +3811,33 @@ open_listen_match_streamlocal(ForwardPermission *allowed_open,
  * local side.
  */
 static int
-channel_request_rforward_cancel_tcpip(const char *host, u_short port)
+channel_request_rforward_cancel_tcpip(struct ssh *ssh,
+    const char *host, u_short port)
 {
-        int i;
-
-        if (!compat20)
-                return -1;
+        struct ssh_channels *sc = ssh->chanctxt;
+        int r;
+        u_int i;
+        ForwardPermission *fp;
 
-        for (i = 0; i < num_permitted_opens; i++) {
-                if (open_listen_match_tcpip(&permitted_opens[i], host, port, 0))
+        for (i = 0; i < sc->num_permitted_opens; i++) {
+                fp = &sc->permitted_opens[i];
+                if (open_listen_match_tcpip(fp, host, port, 0))
                         break;
+                fp = NULL;
         }
-        if (i >= num_permitted_opens) {
+        if (fp == NULL) {
                 debug("%s: requested forward not found", __func__);
                 return -1;
         }
-        packet_start(SSH2_MSG_GLOBAL_REQUEST);
-        packet_put_cstring("cancel-tcpip-forward");
-        packet_put_char(0);
-        packet_put_cstring(channel_rfwd_bind_host(host));
-        packet_put_int(port);
-        packet_send();
-
-        permitted_opens[i].listen_port = 0;
-        permitted_opens[i].port_to_connect = 0;
-        free(permitted_opens[i].host_to_connect);
-        permitted_opens[i].host_to_connect = NULL;
-        free(permitted_opens[i].listen_host);
-        permitted_opens[i].listen_host = NULL;
-        permitted_opens[i].listen_path = NULL;
-        permitted_opens[i].downstream = NULL;
+        if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+            (r = sshpkt_put_cstring(ssh, "cancel-tcpip-forward")) != 0 ||
+            (r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */
+            (r = sshpkt_put_cstring(ssh, channel_rfwd_bind_host(host))) != 0 ||
+            (r = sshpkt_put_u32(ssh, port)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0)
+                fatal("%s: send cancel: %s", __func__, ssh_err(r));
+
+        fwd_perm_clear(fp); /* unregister */
 
         return 0;
 }
@@ -3757,35 +3847,32 @@ channel_request_rforward_cancel_tcpip(const char *host, u_short port)
  * path from local side.
  */
 static int
-channel_request_rforward_cancel_streamlocal(const char *path)
+channel_request_rforward_cancel_streamlocal(struct ssh *ssh, const char *path)
 {
-        int i;
-
-        if (!compat20)
-                return -1;
+        struct ssh_channels *sc = ssh->chanctxt;
+        int r;
+        u_int i;
+        ForwardPermission *fp;
 
-        for (i = 0; i < num_permitted_opens; i++) {
-                if (open_listen_match_streamlocal(&permitted_opens[i], path))
+        for (i = 0; i < sc->num_permitted_opens; i++) {
+                fp = &sc->permitted_opens[i];
+                if (open_listen_match_streamlocal(fp, path))
                         break;
+                fp = NULL;
         }
-        if (i >= num_permitted_opens) {
+        if (fp == NULL) {
                 debug("%s: requested forward not found", __func__);
                 return -1;
         }
-        packet_start(SSH2_MSG_GLOBAL_REQUEST);
-        packet_put_cstring("cancel-streamlocal-forward@openssh.com");
-        packet_put_char(0);
-        packet_put_cstring(path);
-        packet_send();
-
-        permitted_opens[i].listen_port = 0;
-        permitted_opens[i].port_to_connect = 0;
-        free(permitted_opens[i].host_to_connect);
-        permitted_opens[i].host_to_connect = NULL;
-        permitted_opens[i].listen_host = NULL;
-        free(permitted_opens[i].listen_path);
-        permitted_opens[i].listen_path = NULL;
-        permitted_opens[i].downstream = NULL;
+        if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+            (r = sshpkt_put_cstring(ssh,
+            "cancel-streamlocal-forward@openssh.com")) != 0 ||
+            (r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */
+            (r = sshpkt_put_cstring(ssh, path)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0)
+                fatal("%s: send cancel: %s", __func__, ssh_err(r));
+
+        fwd_perm_clear(fp); /* unregister */
 
         return 0;
 }
@@ -3794,14 +3881,15 @@ channel_request_rforward_cancel_streamlocal(const char *path)
  * Request cancellation of remote forwarding of a connection from local side.
  */
 int
-channel_request_rforward_cancel(struct Forward *fwd)
+channel_request_rforward_cancel(struct ssh *ssh, struct Forward *fwd)
 {
         if (fwd->listen_path != NULL) {
-                return (channel_request_rforward_cancel_streamlocal(
-                    fwd->listen_path));
+                return channel_request_rforward_cancel_streamlocal(ssh,
+                    fwd->listen_path);
         } else {
-                return (channel_request_rforward_cancel_tcpip(fwd->listen_host,
-                    fwd->listen_port ? fwd->listen_port : fwd->allocated_port));
+                return channel_request_rforward_cancel_tcpip(ssh,
+                    fwd->listen_host,
+                    fwd->listen_port ? fwd->listen_port : fwd->allocated_port);
         }
 }
 
@@ -3811,28 +3899,20 @@ channel_request_rforward_cancel(struct Forward *fwd)
  * anyway, and the server has no way to know but to trust the client anyway.
  */
 void
-channel_permit_all_opens(void)
+channel_permit_all_opens(struct ssh *ssh)
 {
-        if (num_permitted_opens == 0)
-                all_opens_permitted = 1;
+        if (ssh->chanctxt->num_permitted_opens == 0)
+                ssh->chanctxt->all_opens_permitted = 1;
 }
 
 void
-channel_add_permitted_opens(char *host, int port)
+channel_add_permitted_opens(struct ssh *ssh, char *host, int port)
 {
-        debug("allow port forwarding to host %s port %d", host, port);
+        struct ssh_channels *sc = ssh->chanctxt;
 
-        permitted_opens = xreallocarray(permitted_opens,
-            num_permitted_opens + 1, sizeof(*permitted_opens));
-        permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
-        permitted_opens[num_permitted_opens].port_to_connect = port;
-        permitted_opens[num_permitted_opens].listen_host = NULL;
-        permitted_opens[num_permitted_opens].listen_path = NULL;
-        permitted_opens[num_permitted_opens].listen_port = 0;
-        permitted_opens[num_permitted_opens].downstream = NULL;
-        num_permitted_opens++;
-
-        all_opens_permitted = 0;
+        debug("allow port forwarding to host %s port %d", host, port);
+        fwd_perm_list_add(ssh, FWDPERM_USER, host, port, NULL, NULL, 0, NULL);
+        sc->all_opens_permitted = 0;
 }
 
 /*
@@ -3841,105 +3921,61 @@ channel_add_permitted_opens(char *host, int port)
  * passed then they entry will be invalidated.
  */
 void
-channel_update_permitted_opens(int idx, int newport)
+channel_update_permitted_opens(struct ssh *ssh, int idx, int newport)
 {
-        if (idx < 0 || idx >= num_permitted_opens) {
-                debug("channel_update_permitted_opens: index out of range:"
-                    " %d num_permitted_opens %d", idx, num_permitted_opens);
+        struct ssh_channels *sc = ssh->chanctxt;
+
+        if (idx < 0 || (u_int)idx >= sc->num_permitted_opens) {
+                debug("%s: index out of range: %d num_permitted_opens %d",
+                    __func__, idx, sc->num_permitted_opens);
                 return;
         }
         debug("%s allowed port %d for forwarding to host %s port %d",
             newport > 0 ? "Updating" : "Removing",
             newport,
-            permitted_opens[idx].host_to_connect,
-            permitted_opens[idx].port_to_connect);
-        if (newport >= 0)  {
-                permitted_opens[idx].listen_port = 
+            sc->permitted_opens[idx].host_to_connect,
+            sc->permitted_opens[idx].port_to_connect);
+        if (newport <= 0)
+                fwd_perm_clear(&sc->permitted_opens[idx]);
+        else {
+                sc->permitted_opens[idx].listen_port =
                     (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
-        } else {
-                permitted_opens[idx].listen_port = 0;
-                permitted_opens[idx].port_to_connect = 0;
-                free(permitted_opens[idx].host_to_connect);
-                permitted_opens[idx].host_to_connect = NULL;
-                free(permitted_opens[idx].listen_host);
-                permitted_opens[idx].listen_host = NULL;
-                free(permitted_opens[idx].listen_path);
-                permitted_opens[idx].listen_path = NULL;
         }
 }
 
 int
-channel_add_adm_permitted_opens(char *host, int port)
+channel_add_adm_permitted_opens(struct ssh *ssh, char *host, int port)
 {
         debug("config allows port forwarding to host %s port %d", host, port);
-
-        permitted_adm_opens = xreallocarray(permitted_adm_opens,
-            num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
-        permitted_adm_opens[num_adm_permitted_opens].host_to_connect
-             = xstrdup(host);
-        permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
-        permitted_adm_opens[num_adm_permitted_opens].listen_host = NULL;
-        permitted_adm_opens[num_adm_permitted_opens].listen_path = NULL;
-        permitted_adm_opens[num_adm_permitted_opens].listen_port = 0;
-        return ++num_adm_permitted_opens;
+        return fwd_perm_list_add(ssh, FWDPERM_ADMIN, host, port,
+            NULL, NULL, 0, NULL);
 }
 
 void
-channel_disable_adm_local_opens(void)
+channel_disable_adm_local_opens(struct ssh *ssh)
 {
-        channel_clear_adm_permitted_opens();
-        permitted_adm_opens = xcalloc(sizeof(*permitted_adm_opens), 1);
-        permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
-        num_adm_permitted_opens = 1;
+        channel_clear_adm_permitted_opens(ssh);
+        fwd_perm_list_add(ssh, FWDPERM_ADMIN, NULL, 0, NULL, NULL, 0, NULL);
 }
 
 void
-channel_clear_permitted_opens(void)
+channel_clear_permitted_opens(struct ssh *ssh)
 {
-        int i;
+        struct ssh_channels *sc = ssh->chanctxt;
 
-        for (i = 0; i < num_permitted_opens; i++) {
-                free(permitted_opens[i].host_to_connect);
-                free(permitted_opens[i].listen_host);
-                free(permitted_opens[i].listen_path);
-        }
-        free(permitted_opens);
-        permitted_opens = NULL;
-        num_permitted_opens = 0;
+        sc->permitted_opens = xrecallocarray(sc->permitted_opens,
+            sc->num_permitted_opens, 0, sizeof(*sc->permitted_opens));
+        sc->num_permitted_opens = 0;
 }
 
 void
-channel_clear_adm_permitted_opens(void)
+channel_clear_adm_permitted_opens(struct ssh *ssh)
 {
-        int i;
+        struct ssh_channels *sc = ssh->chanctxt;
 
-        for (i = 0; i < num_adm_permitted_opens; i++) {
-                free(permitted_adm_opens[i].host_to_connect);
-                free(permitted_adm_opens[i].listen_host);
-                free(permitted_adm_opens[i].listen_path);
-        }
-        free(permitted_adm_opens);
-        permitted_adm_opens = NULL;
-        num_adm_permitted_opens = 0;
-}
-
-void
-channel_print_adm_permitted_opens(void)
-{
-        int i;
-
-        printf("permitopen");
-        if (num_adm_permitted_opens == 0) {
-                printf(" any\n");
-                return;
-        }
-        for (i = 0; i < num_adm_permitted_opens; i++)
-                if (permitted_adm_opens[i].host_to_connect == NULL)
-                        printf(" none");
-                else
-                        printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
-                            permitted_adm_opens[i].port_to_connect);
-        printf("\n");
+        sc->permitted_adm_opens = xrecallocarray(sc->permitted_adm_opens,
+            sc->num_adm_permitted_opens, 0, sizeof(*sc->permitted_adm_opens));
+        sc->num_adm_permitted_opens = 0;
 }
 
 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
@@ -3961,7 +3997,8 @@ connect_next(struct channel_connect *cctx)
 {
         int sock, saved_errno;
         struct sockaddr_un *sunaddr;
-        char ntop[NI_MAXHOST], strport[MAXIMUM(NI_MAXSERV,sizeof(sunaddr->sun_path))];
+        char ntop[NI_MAXHOST];
+        char strport[MAXIMUM(NI_MAXSERV, sizeof(sunaddr->sun_path))];
 
         for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
                 switch (cctx->ai->ai_family) {
@@ -4027,21 +4064,18 @@ channel_connect_ctx_free(struct channel_connect *cctx)
 }
 
 /*
- * Return CONNECTING channel to remote host:port or local socket path,
+ * Return connecting socket to remote host:port or local socket path,
  * passing back the failure reason if appropriate.
  */
-static Channel *
-connect_to_reason(const char *name, int port, char *ctype, char *rname,
-     int *reason, const char **errmsg)
+static int
+connect_to_helper(struct ssh *ssh, const char *name, int port, int socktype,
+    char *ctype, char *rname, struct channel_connect *cctx,
+    int *reason, const char **errmsg)
 {
         struct addrinfo hints;
         int gaierr;
         int sock = -1;
         char strport[NI_MAXSERV];
-        struct channel_connect cctx;
-        Channel *c;
-
-        memset(&cctx, 0, sizeof(cctx));
 
         if (port == PORT_STREAMLOCAL) {
                 struct sockaddr_un *sunaddr;
@@ -4049,7 +4083,7 @@ connect_to_reason(const char *name, int port, char *ctype, char *rname,
 
                 if (strlen(name) > sizeof(sunaddr->sun_path)) {
                         error("%.100s: %.100s", name, strerror(ENAMETOOLONG));
-                        return (NULL);
+                        return -1;
                 }
 
                 /*
@@ -4062,18 +4096,18 @@ connect_to_reason(const char *name, int port, char *ctype, char *rname,
                 ai->ai_addr = (struct sockaddr *)(ai + 1);
                 ai->ai_addrlen = sizeof(*sunaddr);
                 ai->ai_family = AF_UNIX;
-                ai->ai_socktype = SOCK_STREAM;
+                ai->ai_socktype = socktype;
                 ai->ai_protocol = PF_UNSPEC;
                 sunaddr = (struct sockaddr_un *)ai->ai_addr;
                 sunaddr->sun_family = AF_UNIX;
                 strlcpy(sunaddr->sun_path, name, sizeof(sunaddr->sun_path));
-                cctx.aitop = ai;
+                cctx->aitop = ai;
         } else {
                 memset(&hints, 0, sizeof(hints));
-                hints.ai_family = IPv4or6;
-                hints.ai_socktype = SOCK_STREAM;
+                hints.ai_family = ssh->chanctxt->IPv4or6;
+                hints.ai_socktype = socktype;
                 snprintf(strport, sizeof strport, "%d", port);
-                if ((gaierr = getaddrinfo(name, strport, &hints, &cctx.aitop))
+                if ((gaierr = getaddrinfo(name, strport, &hints, &cctx->aitop))
                     != 0) {
                         if (errmsg != NULL)
                                 *errmsg = ssh_gai_strerror(gaierr);
@@ -4081,31 +4115,46 @@ connect_to_reason(const char *name, int port, char *ctype, char *rname,
                                 *reason = SSH2_OPEN_CONNECT_FAILED;
                         error("connect_to %.100s: unknown host (%s)", name,
                             ssh_gai_strerror(gaierr));
-                        return NULL;
+                        return -1;
                 }
         }
 
-        cctx.host = xstrdup(name);
-        cctx.port = port;
-        cctx.ai = cctx.aitop;
+        cctx->host = xstrdup(name);
+        cctx->port = port;
+        cctx->ai = cctx->aitop;
 
-        if ((sock = connect_next(&cctx)) == -1) {
+        if ((sock = connect_next(cctx)) == -1) {
                 error("connect to %.100s port %d failed: %s",
                     name, port, strerror(errno));
-                channel_connect_ctx_free(&cctx);
-                return NULL;
+                return -1;
         }
-        c = channel_new(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
-            CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
-        c->connect_ctx = cctx;
-        return c;
+
+        return sock;
 }
 
 /* Return CONNECTING channel to remote host:port or local socket path */
 static Channel *
-connect_to(const char *name, int port, char *ctype, char *rname)
+connect_to(struct ssh *ssh, const char *host, int port,
+    char *ctype, char *rname)
 {
-        return connect_to_reason(name, port, ctype, rname, NULL, NULL);
+        struct channel_connect cctx;
+        Channel *c;
+        int sock;
+
+        memset(&cctx, 0, sizeof(cctx));
+        sock = connect_to_helper(ssh, host, port, SOCK_STREAM, ctype, rname,
+            &cctx, NULL, NULL);
+        if (sock == -1) {
+                channel_connect_ctx_free(&cctx);
+                return NULL;
+        }
+        c = channel_new(ssh, ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
+            CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
+        c->host_port = port;
+        c->path = xstrdup(host);
+        c->connect_ctx = cctx;
+
+        return c;
 }
 
 /*
@@ -4113,19 +4162,24 @@ connect_to(const char *name, int port, char *ctype, char *rname)
  * that needs to deal with this connection.
  */
 Channel *
-channel_connect_by_listen_address(const char *listen_host,
+channel_connect_by_listen_address(struct ssh *ssh, const char *listen_host,
     u_short listen_port, char *ctype, char *rname)
 {
-        int i;
-
-        for (i = 0; i < num_permitted_opens; i++) {
-                if (open_listen_match_tcpip(&permitted_opens[i], listen_host,
-                    listen_port, 1)) {
-                        if (permitted_opens[i].downstream)
-                                return permitted_opens[i].downstream;
-                        return connect_to(
-                            permitted_opens[i].host_to_connect,
-                            permitted_opens[i].port_to_connect, ctype, rname);
+        struct ssh_channels *sc = ssh->chanctxt;
+        u_int i;
+        ForwardPermission *fp;
+
+        for (i = 0; i < sc->num_permitted_opens; i++) {
+                fp = &sc->permitted_opens[i];
+                if (open_listen_match_tcpip(fp, listen_host, listen_port, 1)) {
+                        if (fp->downstream)
+                                return fp->downstream;
+                        if (fp->port_to_connect == 0)
+                                return rdynamic_connect_prepare(ssh,
+                                    ctype, rname);
+                        return connect_to(ssh,
+                            fp->host_to_connect, fp->port_to_connect,
+                            ctype, rname);
                 }
         }
         error("WARNING: Server requests forwarding for unknown listen_port %d",
@@ -4134,15 +4188,19 @@ channel_connect_by_listen_address(const char *listen_host,
 }
 
 Channel *
-channel_connect_by_listen_path(const char *path, char *ctype, char *rname)
+channel_connect_by_listen_path(struct ssh *ssh, const char *path,
+    char *ctype, char *rname)
 {
-        int i;
-
-        for (i = 0; i < num_permitted_opens; i++) {
-                if (open_listen_match_streamlocal(&permitted_opens[i], path)) {
-                        return connect_to(
-                            permitted_opens[i].host_to_connect,
-                            permitted_opens[i].port_to_connect, ctype, rname);
+        struct ssh_channels *sc = ssh->chanctxt;
+        u_int i;
+        ForwardPermission *fp;
+
+        for (i = 0; i < sc->num_permitted_opens; i++) {
+                fp = &sc->permitted_opens[i];
+                if (open_listen_match_streamlocal(fp, path)) {
+                        return connect_to(ssh,
+                            fp->host_to_connect, fp->port_to_connect,
+                            ctype, rname);
                 }
         }
         error("WARNING: Server requests forwarding for unknown path %.100s",
@@ -4152,27 +4210,36 @@ channel_connect_by_listen_path(const char *path, char *ctype, char *rname)
 
 /* Check if connecting to that port is permitted and connect. */
 Channel *
-channel_connect_to_port(const char *host, u_short port, char *ctype,
-    char *rname, int *reason, const char **errmsg)
+channel_connect_to_port(struct ssh *ssh, const char *host, u_short port,
+    char *ctype, char *rname, int *reason, const char **errmsg)
 {
-        int i, permit, permit_adm = 1;
+        struct ssh_channels *sc = ssh->chanctxt;
+        struct channel_connect cctx;
+        Channel *c;
+        u_int i, permit, permit_adm = 1;
+        int sock;
+        ForwardPermission *fp;
 
-        permit = all_opens_permitted;
+        permit = sc->all_opens_permitted;
         if (!permit) {
-                for (i = 0; i < num_permitted_opens; i++)
-                        if (open_match(&permitted_opens[i], host, port)) {
+                for (i = 0; i < sc->num_permitted_opens; i++) {
+                        fp = &sc->permitted_opens[i];
+                        if (open_match(fp, host, port)) {
                                 permit = 1;
                                 break;
                         }
+                }
         }
 
-        if (num_adm_permitted_opens > 0) {
+        if (sc->num_adm_permitted_opens > 0) {
                 permit_adm = 0;
-                for (i = 0; i < num_adm_permitted_opens; i++)
-                        if (open_match(&permitted_adm_opens[i], host, port)) {
+                for (i = 0; i < sc->num_adm_permitted_opens; i++) {
+                        fp = &sc->permitted_adm_opens[i];
+                        if (open_match(fp, host, port)) {
                                 permit_adm = 1;
                                 break;
                         }
+                }
         }
 
         if (!permit || !permit_adm) {
@@ -4182,31 +4249,53 @@ channel_connect_to_port(const char *host, u_short port, char *ctype,
                         *reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
                 return NULL;
         }
-        return connect_to_reason(host, port, ctype, rname, reason, errmsg);
+
+        memset(&cctx, 0, sizeof(cctx));
+        sock = connect_to_helper(ssh, host, port, SOCK_STREAM, ctype, rname,
+            &cctx, reason, errmsg);
+        if (sock == -1) {
+                channel_connect_ctx_free(&cctx);
+                return NULL;
+        }
+
+        c = channel_new(ssh, ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
+            CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
+        c->host_port = port;
+        c->path = xstrdup(host);
+        c->connect_ctx = cctx;
+
+        return c;
 }
 
 /* Check if connecting to that path is permitted and connect. */
 Channel *
-channel_connect_to_path(const char *path, char *ctype, char *rname)
+channel_connect_to_path(struct ssh *ssh, const char *path,
+    char *ctype, char *rname)
 {
-        int i, permit, permit_adm = 1;
+        struct ssh_channels *sc = ssh->chanctxt;
+        u_int i, permit, permit_adm = 1;
+        ForwardPermission *fp;
 
-        permit = all_opens_permitted;
+        permit = sc->all_opens_permitted;
         if (!permit) {
-                for (i = 0; i < num_permitted_opens; i++)
-                        if (open_match(&permitted_opens[i], path, PORT_STREAMLOCAL)) {
+                for (i = 0; i < sc->num_permitted_opens; i++) {
+                        fp = &sc->permitted_opens[i];
+                        if (open_match(fp, path, PORT_STREAMLOCAL)) {
                                 permit = 1;
                                 break;
                         }
+                }
         }
 
-        if (num_adm_permitted_opens > 0) {
+        if (sc->num_adm_permitted_opens > 0) {
                 permit_adm = 0;
-                for (i = 0; i < num_adm_permitted_opens; i++)
-                        if (open_match(&permitted_adm_opens[i], path, PORT_STREAMLOCAL)) {
+                for (i = 0; i < sc->num_adm_permitted_opens; i++) {
+                        fp = &sc->permitted_adm_opens[i];
+                        if (open_match(fp, path, PORT_STREAMLOCAL)) {
                                 permit_adm = 1;
                                 break;
                         }
+                }
         }
 
         if (!permit || !permit_adm) {
@@ -4214,30 +4303,82 @@ channel_connect_to_path(const char *path, char *ctype, char *rname)
                     "but the request was denied.", path);
                 return NULL;
         }
-        return connect_to(path, PORT_STREAMLOCAL, ctype, rname);
+        return connect_to(ssh, path, PORT_STREAMLOCAL, ctype, rname);
 }
 
 void
-channel_send_window_changes(void)
+channel_send_window_changes(struct ssh *ssh)
 {
-        u_int i;
+        struct ssh_channels *sc = ssh->chanctxt;
         struct winsize ws;
+        int r;
+        u_int i;
 
-        for (i = 0; i < channels_alloc; i++) {
-                if (channels[i] == NULL || !channels[i]->client_tty ||
-                    channels[i]->type != SSH_CHANNEL_OPEN)
+        for (i = 0; i < sc->channels_alloc; i++) {
+                if (sc->channels[i] == NULL || !sc->channels[i]->client_tty ||
+                    sc->channels[i]->type != SSH_CHANNEL_OPEN)
                         continue;
-                if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
+                if (ioctl(sc->channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
                         continue;
-                channel_request_start(i, "window-change", 0);
-                packet_put_int((u_int)ws.ws_col);
-                packet_put_int((u_int)ws.ws_row);
-                packet_put_int((u_int)ws.ws_xpixel);
-                packet_put_int((u_int)ws.ws_ypixel);
-                packet_send();
+                channel_request_start(ssh, i, "window-change", 0);
+                if ((r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 ||
+                    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0 ||
+                    (r = sshpkt_send(ssh)) != 0)
+                        fatal("%s: channel %u: send window-change: %s",
+                            __func__, i, ssh_err(r));
         }
 }
 
+/* Return RDYNAMIC_OPEN channel: channel allows SOCKS, but is not connected */
+static Channel *
+rdynamic_connect_prepare(struct ssh *ssh, char *ctype, char *rname)
+{
+        Channel *c;
+        int r;
+
+        c = channel_new(ssh, ctype, SSH_CHANNEL_RDYNAMIC_OPEN, -1, -1, -1,
+            CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, rname, 1);
+        c->host_port = 0;
+        c->path = NULL;
+
+        /*
+         * We need to open the channel before we have a FD,
+         * so that we can get SOCKS header from peer.
+         */
+        if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
+            (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0) {
+                fatal("%s: channel %i: confirm: %s", __func__,
+                    c->self, ssh_err(r));
+        }
+        return c;
+}
+
+/* Return CONNECTING socket to remote host:port or local socket path */
+static int
+rdynamic_connect_finish(struct ssh *ssh, Channel *c)
+{
+        struct channel_connect cctx;
+        int sock;
+
+        memset(&cctx, 0, sizeof(cctx));
+        sock = connect_to_helper(ssh, c->path, c->host_port, SOCK_STREAM, NULL,
+            NULL, &cctx, NULL, NULL);
+        if (sock == -1)
+                channel_connect_ctx_free(&cctx);
+        else {
+                /* similar to SSH_CHANNEL_CONNECTING but we've already sent the open */
+                c->type = SSH_CHANNEL_RDYNAMIC_FINISH;
+                c->connect_ctx = cctx;
+                channel_register_fds(ssh, c, sock, sock, -1, 0, 1, 0);
+        }
+        return sock;
+}
+
 /* -- X11 forwarding */
 
 /*
@@ -4246,8 +4387,9 @@ channel_send_window_changes(void)
  * stored in display_numberp , or -1 if an error occurs.
  */
 int
-x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
-    int single_connection, u_int *display_numberp, int **chanids)
+x11_create_display_inet(struct ssh *ssh, int x11_display_offset,
+    int x11_use_localhost, int single_connection,
+    u_int *display_numberp, int **chanids)
 {
         Channel *nc = NULL;
         int display_number, sock;
@@ -4264,16 +4406,18 @@ x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
             display_number++) {
                 port = 6000 + display_number;
                 memset(&hints, 0, sizeof(hints));
-                hints.ai_family = IPv4or6;
+                hints.ai_family = ssh->chanctxt->IPv4or6;
                 hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
                 hints.ai_socktype = SOCK_STREAM;
                 snprintf(strport, sizeof strport, "%d", port);
-                if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
+                if ((gaierr = getaddrinfo(NULL, strport,
+                    &hints, &aitop)) != 0) {
                         error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
                         return -1;
                 }
                 for (ai = aitop; ai; ai = ai->ai_next) {
-                        if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+                        if (ai->ai_family != AF_INET &&
+                            ai->ai_family != AF_INET6)
                                 continue;
                         sock = socket(ai->ai_family, ai->ai_socktype,
                             ai->ai_protocol);
@@ -4297,12 +4441,11 @@ x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
                         if (x11_use_localhost)
                                 channel_set_reuseaddr(sock);
                         if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
-                                debug2("bind port %d: %.100s", port, strerror(errno));
+                                debug2("%s: bind port %d: %.100s", __func__,
+                                    port, strerror(errno));
                                 close(sock);
-
-                                for (n = 0; n < num_socks; n++) {
+                                for (n = 0; n < num_socks; n++)
                                         close(socks[n]);
-                                }
                                 num_socks = 0;
                                 break;
                         }
@@ -4332,7 +4475,7 @@ x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
         *chanids = xcalloc(num_socks + 1, sizeof(**chanids));
         for (n = 0; n < num_socks; n++) {
                 sock = socks[n];
-                nc = channel_new("x11 listener",
+                nc = channel_new(ssh, "x11 listener",
                     SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
                     CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
                     0, "X11 inet listener", 1);
@@ -4343,7 +4486,7 @@ x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
 
         /* Return the display number for the DISPLAY environment variable. */
         *display_numberp = display_number;
-        return (0);
+        return 0;
 }
 
 static int
@@ -4401,7 +4544,7 @@ is_path_to_xsocket(const char *display, char *path, size_t pathlen)
 #endif
 
 int
-x11_connect_display(void)
+x11_connect_display(struct ssh *ssh)
 {
         u_int display_number;
         const char *display;
@@ -4446,9 +4589,10 @@ x11_connect_display(void)
         if (strncmp(display, "unix:", 5) == 0 ||
             display[0] == ':') {
                 /* Connect to the unix domain socket. */
-                if (sscanf(strrchr(display, ':') + 1, "%u", &display_number) != 1) {
-                        error("Could not parse display number from DISPLAY: %.100s",
-                            display);
+                if (sscanf(strrchr(display, ':') + 1, "%u",
+                    &display_number) != 1) {
+                        error("Could not parse display number from DISPLAY: "
+                            "%.100s", display);
                         return -1;
                 }
                 /* Create a socket. */
@@ -4470,7 +4614,10 @@ x11_connect_display(void)
                 return -1;
         }
         *cp = 0;
-        /* buf now contains the host name.  But first we parse the display number. */
+        /*
+         * buf now contains the host name.  But first we parse the
+         * display number.
+         */
         if (sscanf(cp + 1, "%u", &display_number) != 1) {
                 error("Could not parse display number from DISPLAY: %.100s",
                     display);
@@ -4479,7 +4626,7 @@ x11_connect_display(void)
 
         /* Look up the host address */
         memset(&hints, 0, sizeof(hints));
-        hints.ai_family = IPv4or6;
+        hints.ai_family = ssh->chanctxt->IPv4or6;
         hints.ai_socktype = SOCK_STREAM;
         snprintf(strport, sizeof strport, "%u", 6000 + display_number);
         if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
@@ -4506,8 +4653,8 @@ x11_connect_display(void)
         }
         freeaddrinfo(aitop);
         if (!ai) {
-                error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
-                    strerror(errno));
+                error("connect %.100s port %u: %.100s", buf,
+                    6000 + display_number, strerror(errno));
                 return -1;
         }
         set_nodelay(sock);
@@ -4515,98 +4662,24 @@ x11_connect_display(void)
 }
 
 /*
- * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
- * the remote channel number.  We should do whatever we want, and respond
- * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
- */
-
-/* ARGSUSED */
-int
-x11_input_open(int type, u_int32_t seq, void *ctxt)
-{
-        Channel *c = NULL;
-        int remote_id, sock = 0;
-        char *remote_host;
-
-        debug("Received X11 open request.");
-
-        remote_id = packet_get_int();
-
-        if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
-                remote_host = packet_get_string(NULL);
-        } else {
-                remote_host = xstrdup("unknown (remote did not supply name)");
-        }
-        packet_check_eom();
-
-        /* Obtain a connection to the real X display. */
-        sock = x11_connect_display();
-        if (sock != -1) {
-                /* Allocate a channel for this connection. */
-                c = channel_new("connected x11 socket",
-                    SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
-                    remote_host, 1);
-                c->remote_id = remote_id;
-                c->force_drain = 1;
-        }
-        free(remote_host);
-        if (c == NULL) {
-                /* Send refusal to the remote host. */
-                packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
-                packet_put_int(remote_id);
-        } else {
-                /* Send a confirmation to the remote host. */
-                packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
-                packet_put_int(remote_id);
-                packet_put_int(c->self);
-        }
-        packet_send();
-        return 0;
-}
-
-/* dummy protocol handler that denies SSH-1 requests (agent/x11) */
-/* ARGSUSED */
-int
-deny_input_open(int type, u_int32_t seq, void *ctxt)
-{
-        int rchan = packet_get_int();
-
-        switch (type) {
-        case SSH_SMSG_AGENT_OPEN:
-                error("Warning: ssh server tried agent forwarding.");
-                break;
-        case SSH_SMSG_X11_OPEN:
-                error("Warning: ssh server tried X11 forwarding.");
-                break;
-        default:
-                error("deny_input_open: type %d", type);
-                break;
-        }
-        error("Warning: this is probably a break-in attempt by a malicious server.");
-        packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
-        packet_put_int(rchan);
-        packet_send();
-        return 0;
-}
-
-/*
  * Requests forwarding of X11 connections, generates fake authentication
  * data, and enables authentication spoofing.
  * This should be called in the client only.
  */
 void
-x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
-    const char *proto, const char *data, int want_reply)
+x11_request_forwarding_with_spoofing(struct ssh *ssh, int client_session_id,
+    const char *disp, const char *proto, const char *data, int want_reply)
 {
+        struct ssh_channels *sc = ssh->chanctxt;
         u_int data_len = (u_int) strlen(data) / 2;
         u_int i, value;
-        char *new_data;
-        int screen_number;
         const char *cp;
+        char *new_data;
+        int r, screen_number;
 
-        if (x11_saved_display == NULL)
-                x11_saved_display = xstrdup(disp);
-        else if (strcmp(disp, x11_saved_display) != 0) {
+        if (sc->x11_saved_display == NULL)
+                sc->x11_saved_display = xstrdup(disp);
+        else if (strcmp(disp, sc->x11_saved_display) != 0) {
                 error("x11_request_forwarding_with_spoofing: different "
                     "$DISPLAY already forwarded");
                 return;
@@ -4620,53 +4693,37 @@ x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
         else
                 screen_number = 0;
 
-        if (x11_saved_proto == NULL) {
+        if (sc->x11_saved_proto == NULL) {
                 /* Save protocol name. */
-                x11_saved_proto = xstrdup(proto);
+                sc->x11_saved_proto = xstrdup(proto);
 
                 /* Extract real authentication data. */
-                x11_saved_data = xmalloc(data_len);
+                sc->x11_saved_data = xmalloc(data_len);
                 for (i = 0; i < data_len; i++) {
                         if (sscanf(data + 2 * i, "%2x", &value) != 1)
                                 fatal("x11_request_forwarding: bad "
                                     "authentication data: %.100s", data);
-                        x11_saved_data[i] = value;
+                        sc->x11_saved_data[i] = value;
                 }
-                x11_saved_data_len = data_len;
+                sc->x11_saved_data_len = data_len;
 
                 /* Generate fake data of the same length. */
-                x11_fake_data = xmalloc(data_len);
-                arc4random_buf(x11_fake_data, data_len);
-                x11_fake_data_len = data_len;
+                sc->x11_fake_data = xmalloc(data_len);
+                arc4random_buf(sc->x11_fake_data, data_len);
+                sc->x11_fake_data_len = data_len;
         }
 
         /* Convert the fake data into hex. */
-        new_data = tohex(x11_fake_data, data_len);
+        new_data = tohex(sc->x11_fake_data, data_len);
 
         /* Send the request packet. */
-        if (compat20) {
-                channel_request_start(client_session_id, "x11-req", want_reply);
-                packet_put_char(0);     /* XXX bool single connection */
-        } else {
-                packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
-        }
-        packet_put_cstring(proto);
-        packet_put_cstring(new_data);
-        packet_put_int(screen_number);
-        packet_send();
-        packet_write_wait();
+        channel_request_start(ssh, client_session_id, "x11-req", want_reply);
+        if ((r = sshpkt_put_u8(ssh, 0)) != 0 || /* bool: single connection */
+            (r = sshpkt_put_cstring(ssh, proto)) != 0 ||
+            (r = sshpkt_put_cstring(ssh, new_data)) != 0 ||
+            (r = sshpkt_put_u32(ssh, screen_number)) != 0 ||
+            (r = sshpkt_send(ssh)) != 0 ||
+            (r = ssh_packet_write_wait(ssh)) != 0)
+                fatal("%s: send x11-req: %s", __func__, ssh_err(r));
         free(new_data);
 }
-
-
-/* -- agent forwarding */
-
-/* Sends a message to the server to request authentication fd forwarding. */
-
-void
-auth_request_forwarding(void)
-{
-        packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
-        packet_send();
-        packet_write_wait();
-}