Merge changes I934c73d4,I28cdc9a0,I9e734da9,I3c079d86

* changes:
  UPSTREAM: depend
  UPSTREAM: upstream: avoid possible NULL deref; from Pedro Martelletto
  Revert "upstream: fix compilation with DEBUG_KEXDH; bz#3160 ok dtucker@"
  Merge upstream-master into master

1 files changed, 2615 insertions, 1953 deletions

diff --git a/channels.c b/channels.c
index 9486c1cf..95a51e21 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.341 2015/02/06 23:21:59 millert Exp $ */
+/* $OpenBSD: channels.c,v 1.398 2020/04/25 06:59:36 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -42,7 +42,6 @@
 #include "includes.h"
 
 #include <sys/types.h>
-#include <sys/param.h>	/* MIN MAX */
 #include <sys/stat.h>
 #include <sys/ioctl.h>
 #include <sys/un.h>
@@ -56,55 +55,52 @@
 
 #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"
-#include "key.h"
+#include "sshkey.h"
 #include "authfd.h"
 #include "pathnames.h"
+#include "match.h"
 
-/* -- channel core */
-
-/*
- * Pointer to an array containing all allocated channels.  The array is
- * dynamically extended as needed.
- */
-static Channel **channels = NULL;
+/* -- agent forwarding */
+#define	NUM_SOCKS	10
 
-/*
- * 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;
+/* -- tcp forwarding */
+/* 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.
- */
-static int channel_max_fd = 0;
+/* special-case wildcard meaning allow any host */
+#define FWD_PERMIT_ANY_HOST	"*"
 
+/* -- X11 forwarding */
+/* Maximum number of fake X11 displays to try. */
+#define MAX_DISPLAYS  1000
 
-/* -- tcp forwarding */
+/* Per-channel callback for pre/post select() actions */
+typedef void chan_fn(struct ssh *, Channel *c,
+    fd_set *readset, fd_set *writeset);
 
 /*
  * Data structure for storing which hosts are permitted for forward requests.
@@ -115,119 +111,190 @@ static int channel_max_fd = 0;
 /* XXX: streamlocal wants a path instead of host:port */
 /*      Overload host_to_connect; we could just make this match Forward */
 /*	XXX - can we use listen_host instead of listen_path? */
-typedef struct {
+struct permission {
 	char *host_to_connect;		/* Connect to 'host'. */
 	int port_to_connect;		/* Connect to 'port'. */
 	char *listen_host;		/* Remote side should listen address. */
 	char *listen_path;		/* Remote side should listen path. */
 	int listen_port;		/* Remote side should listen port. */
-} 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;
+	Channel *downstream;		/* Downstream mux*/
+};
 
-/* Number of permitted host/port pairs in the array permitted by the user. */
-static int num_permitted_opens = 0;
+/*
+ * Stores the forwarding permission state for a single direction (local or
+ * remote).
+ */
+struct permission_set {
+	/*
+	 * List of all local permitted host/port pairs to allow for the
+	 * user.
+	 */
+	u_int num_permitted_user;
+	struct permission *permitted_user;
 
-/* Number of permitted host/port pair in the array permitted by the admin. */
-static int num_adm_permitted_opens = 0;
+	/*
+	 * List of all permitted host/port pairs to allow for the admin.
+	 */
+	u_int num_permitted_admin;
+	struct permission *permitted_admin;
 
-/* special-case port number meaning allow any port */
-#define FWD_PERMIT_ANY_PORT	0
+	/*
+	 * If this is true, all opens/listens 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.
+	 */
+	int all_permitted;
+};
 
-/*
- * 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;
+/* 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;
 
+	/*
+	 * 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;
 
-/* -- X11 forwarding */
+	/*
+	 * Maximum file descriptor value used in any of the channels.  This is
+	 * updated in channel_new.
+	 */
+	int channel_max_fd;
 
-/* Maximum number of fake X11 displays to try. */
-#define MAX_DISPLAYS  1000
+	/*
+	 * '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;
 
-/* Saved X11 local (client) display. */
-static char *x11_saved_display = NULL;
+	/* -- tcp forwarding */
+	struct permission_set local_perms;
+	struct permission_set remote_perms;
 
-/* Saved X11 authentication protocol name. */
-static char *x11_saved_proto = NULL;
+	/* -- X11 forwarding */
 
-/* Saved X11 authentication data.  This is the real data. */
-static char *x11_saved_data = NULL;
-static u_int x11_saved_data_len = 0;
+	/* 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)
+		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(struct ssh *ssh, u_int remote_id)
+{
+	Channel *c;
+	u_int i;
+
+	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;
+}
+
 /*
  * Returns the channel if it is allowed to receive protocol messages.
  * 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:
-		return (c);
+	case SSH_CHANNEL_MUX_PROXY:
+		return c;
 	}
 	logit("Non-public channel %d, type %d.", id, c->type);
-	return (NULL);
+	return NULL;
 }
 
 /*
@@ -235,13 +302,15 @@ 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 = MAX(channel_max_fd, rfd);
-	channel_max_fd = MAX(channel_max_fd, wfd);
-	channel_max_fd = MAX(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);
@@ -279,150 +348,273 @@ 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 = xrealloc(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 = MAX(max, c->rfd);
-			max = MAX(max, c->wfd);
-			max = MAX(max, c->efd);
+			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)
+{
+	int sock = c->sock, rfd = c->rfd, wfd = c->wfd, efd = c->efd;
+
+	channel_close_fd(ssh, &c->sock);
+	if (rfd != sock)
+		channel_close_fd(ssh, &c->rfd);
+	if (wfd != sock && wfd != rfd)
+		channel_close_fd(ssh, &c->wfd);
+	if (efd != sock && efd != rfd && efd != wfd)
+		channel_close_fd(ssh, &c->efd);
+}
+
+static void
+fwd_perm_clear(struct permission *perm)
+{
+	free(perm->host_to_connect);
+	free(perm->listen_host);
+	free(perm->listen_path);
+	memset(perm, 0, sizeof(*perm));
+}
+
+/* Returns an printable name for the specified forwarding permission list */
+static const char *
+fwd_ident(int who, int where)
+{
+	if (who == FORWARD_ADM) {
+		if (where == FORWARD_LOCAL)
+			return "admin local";
+		else if (where == FORWARD_REMOTE)
+			return "admin remote";
+	} else if (who == FORWARD_USER) {
+		if (where == FORWARD_LOCAL)
+			return "user local";
+		else if (where == FORWARD_REMOTE)
+			return "user remote";
+	}
+	fatal("Unknown forward permission list %d/%d", who, where);
+}
+
+/* Returns the forwarding permission list for the specified direction */
+static struct permission_set *
+permission_set_get(struct ssh *ssh, int where)
+{
+	struct ssh_channels *sc = ssh->chanctxt;
+
+	switch (where) {
+	case FORWARD_LOCAL:
+		return &sc->local_perms;
+		break;
+	case FORWARD_REMOTE:
+		return &sc->remote_perms;
+		break;
+	default:
+		fatal("%s: invalid forwarding direction %d", __func__, where);
+	}
+}
+
+/* Returns pointers to the specified forwarding list and its element count */
+static void
+permission_set_get_array(struct ssh *ssh, int who, int where,
+    struct permission ***permpp, u_int **npermpp)
+{
+	struct permission_set *pset = permission_set_get(ssh, where);
+
+	switch (who) {
+	case FORWARD_USER:
+		*permpp = &pset->permitted_user;
+		*npermpp = &pset->num_permitted_user;
+		break;
+	case FORWARD_ADM:
+		*permpp = &pset->permitted_admin;
+		*npermpp = &pset->num_permitted_admin;
+		break;
+	default:
+		fatal("%s: invalid forwarding client %d", __func__, who);
+	}
+}
+
+/* Adds an entry to the spcified forwarding list */
+static int
+permission_set_add(struct ssh *ssh, int who, int where,
+    const char *host_to_connect, int port_to_connect,
+    const char *listen_host, const char *listen_path, int listen_port,
+    Channel *downstream)
+{
+	struct permission **permp;
+	u_int n, *npermp;
+
+	permission_set_get_array(ssh, who, where, &permp, &npermp);
+
+	if (*npermp >= INT_MAX)
+		fatal("%s: %s overflow", __func__, fwd_ident(who, where));
+
+	*permp = xrecallocarray(*permp, *npermp, *npermp + 1, sizeof(**permp));
+	n = (*npermp)++;
+#define MAYBE_DUP(s) ((s == NULL) ? NULL : xstrdup(s))
+	(*permp)[n].host_to_connect = MAYBE_DUP(host_to_connect);
+	(*permp)[n].port_to_connect = port_to_connect;
+	(*permp)[n].listen_host = MAYBE_DUP(listen_host);
+	(*permp)[n].listen_path = MAYBE_DUP(listen_path);
+	(*permp)[n].listen_port = listen_port;
+	(*permp)[n].downstream = downstream;
+#undef MAYBE_DUP
+	return (int)n;
+}
+
+static void
+mux_remove_remote_forwardings(struct ssh *ssh, Channel *c)
 {
-	channel_close_fd(&c->sock);
-	channel_close_fd(&c->rfd);
-	channel_close_fd(&c->wfd);
-	channel_close_fd(&c->efd);
+	struct ssh_channels *sc = ssh->chanctxt;
+	struct permission_set *pset = &sc->local_perms;
+	struct permission *perm;
+	int r;
+	u_int i;
+
+	for (i = 0; i < pset->num_permitted_user; i++) {
+		perm = &pset->permitted_user[i];
+		if (perm->downstream != c)
+			continue;
+
+		/* cancel on the server, since mux client is gone */
+		debug("channel %d: cleanup remote forward for %s:%u",
+		    c->self, perm->listen_host, perm->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(perm->listen_host))) != 0 ||
+		    (r = sshpkt_put_u32(ssh, perm->listen_port)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0) {
+			fatal("%s: channel %i: %s", __func__,
+			    c->self, ssh_err(r));
+		}
+		fwd_perm_clear(perm); /* 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 (channels[i])
-			n++;
+	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);
 
-	s = channel_open_message();
-	debug3("channel %d: status: %s", c->self, s);
-	free(s);
+	if (c->type == SSH_CHANNEL_MUX_CLIENT)
+		mux_remove_remote_forwardings(ssh, c);
+
+	if (log_level_get() >= SYSLOG_LEVEL_DEBUG3) {
+		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);
@@ -431,25 +623,44 @@ 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);
+		freezero(cc, sizeof(*cc));
 	}
 	if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
-		c->filter_cleanup(c->self, c->filter_ctx);
-	channels[c->self] = NULL;
-	free(c);
+		c->filter_cleanup(ssh, c->self, c->filter_ctx);
+	sc->channels[c->self] = NULL;
+	freezero(c, sizeof(*c));
 }
 
 void
-channel_free_all(void)
+channel_free_all(struct ssh *ssh)
 {
 	u_int i;
+	struct ssh_channels *sc = ssh->chanctxt;
+
+	for (i = 0; i < sc->channels_alloc; i++)
+		if (sc->channels[i] != NULL)
+			channel_free(ssh, sc->channels[i]);
+
+	free(sc->channels);
+	sc->channels = NULL;
+	sc->channels_alloc = 0;
+	sc->channel_max_fd = 0;
+
+	free(sc->x11_saved_display);
+	sc->x11_saved_display = NULL;
+
+	free(sc->x11_saved_proto);
+	sc->x11_saved_proto = NULL;
 
-	for (i = 0; i < channels_alloc; i++)
-		if (channels[i] != NULL)
-			channel_free(channels[i]);
+	free(sc->x11_saved_data);
+	sc->x11_saved_data = NULL;
+	sc->x11_saved_data_len = 0;
+
+	free(sc->x11_fake_data);
+	sc->x11_fake_data = NULL;
+	sc->x11_fake_data_len = 0;
 }
 
 /*
@@ -457,26 +668,26 @@ 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:
@@ -485,8 +696,8 @@ 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;
 			}
 		}
@@ -498,28 +709,20 @@ 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;
@@ -527,13 +730,13 @@ 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) {
@@ -544,6 +747,7 @@ 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:
@@ -551,21 +755,16 @@ 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:
-			return 1;
-		case SSH_CHANNEL_INPUT_DRAINING:
-		case SSH_CHANNEL_OUTPUT_DRAINING:
-			if (!compat13)
-				fatal("cannot happen: OUT_DRAIN");
+		case SSH_CHANNEL_MUX_PROXY:
 			return 1;
 		default:
-			fatal("channel_still_open: bad channel type %d", c->type);
+			fatal("%s: bad channel type %d", __func__, c->type);
 			/* NOTREACHED */
 		}
 	}
@@ -574,23 +773,26 @@ 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:
 		case SSH_CHANNEL_MUX_LISTENER:
 		case SSH_CHANNEL_MUX_CLIENT:
+		case SSH_CHANNEL_MUX_PROXY:
 		case SSH_CHANNEL_OPENING:
 		case SSH_CHANNEL_CONNECTING:
 		case SSH_CHANNEL_ZOMBIE:
@@ -603,19 +805,48 @@ 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 */
 		}
 	}
 	return -1;
 }
 
+/* Returns the state of the channel's extended usage flag */
+const char *
+channel_format_extended_usage(const Channel *c)
+{
+	if (c->efd == -1)
+		return "closed";
+
+	switch (c->extended_usage) {
+	case CHAN_EXTENDED_WRITE:
+		return "write";
+	case CHAN_EXTENDED_READ:
+		return "read";
+	case CHAN_EXTENDED_IGNORE:
+		return "ignore";
+	default:
+		return "UNKNOWN";
+	}
+}
+
+static char *
+channel_format_status(const Channel *c)
+{
+	char *ret = NULL;
+
+	xasprintf(&ret, "t%d %s%u i%u/%zu o%u/%zu e[%s]/%zu "
+	    "fd %d/%d/%d sock %d cc %d",
+	    c->type,
+	    c->have_remote_id ? "r" : "nr", c->remote_id,
+	    c->istate, sshbuf_len(c->input),
+	    c->ostate, sshbuf_len(c->output),
+	    channel_format_extended_usage(c), sshbuf_len(c->extended),
+	    c->rfd, c->wfd, c->efd, c->sock, c->ctl_chan);
+	return ret;
+}
 
 /*
  * Returns a message describing the currently open forwarded connections,
@@ -623,18 +854,21 @@ 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 *cp, *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) {
@@ -645,7 +879,6 @@ channel_open_message(void)
 		case SSH_CHANNEL_AUTH_SOCKET:
 		case SSH_CHANNEL_ZOMBIE:
 		case SSH_CHANNEL_ABANDONED:
-		case SSH_CHANNEL_MUX_CLIENT:
 		case SSH_CHANNEL_MUX_LISTENER:
 		case SSH_CHANNEL_UNIX_LISTENER:
 		case SSH_CHANNEL_RUNIX_LISTENER:
@@ -654,73 +887,93 @@ 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:
-			snprintf(buf, sizeof buf,
-			    "  #%d %.300s (t%d r%d i%d/%d o%d/%d 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));
+		case SSH_CHANNEL_MUX_PROXY:
+		case SSH_CHANNEL_MUX_CLIENT:
+			cp = channel_format_status(c);
+			if ((r = sshbuf_putf(buf, "  #%d %.300s (%s)\r\n",
+			    c->self, c->remote_name, cp)) != 0) {
+				free(cp);
+				fatal("%s: sshbuf_putf: %s",
+				    __func__, ssh_err(r));
+			}
+			free(cp);
 			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;
@@ -730,12 +983,13 @@ 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;
@@ -743,12 +997,13 @@ 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;
@@ -756,12 +1011,12 @@ 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;
@@ -769,13 +1024,13 @@ 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;
@@ -785,118 +1040,80 @@ 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)
-{
-	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)
+channel_pre_open(struct ssh *ssh, 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
@@ -907,17 +1124,26 @@ 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 (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];
@@ -931,27 +1157,27 @@ 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;
 	}
 	/*
@@ -960,90 +1186,63 @@ 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 {
@@ -1052,14 +1251,15 @@ 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 */
@@ -1084,46 +1284,55 @@ 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);
 
@@ -1139,7 +1348,10 @@ 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;
 }
 
@@ -1152,10 +1364,10 @@ 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;
@@ -1164,14 +1376,15 @@ 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)
@@ -1191,10 +1404,16 @@ 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 */
@@ -1231,11 +1450,22 @@ 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;
@@ -1262,22 +1492,23 @@ 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);
 
@@ -1286,23 +1517,24 @@ 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 */
@@ -1310,105 +1542,169 @@ 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 == -1) {
+		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 ||
+	    (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_sock_port(c->sock, 1);
+	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) */
@@ -1417,78 +1713,73 @@ 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);
 }
 
-static void
-channel_set_reuseaddr(int fd)
+void
+channel_set_x11_refuse_time(struct ssh *ssh, u_int refuse_time)
 {
-	int on = 1;
-
-	/*
-	 * Set socket options.
-	 * Allow local port reuse in TIME_WAIT.
-	 */
-	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
-		error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
+	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;
@@ -1496,360 +1787,406 @@ 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);
+	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 (nextstate != SSH_CHANNEL_DYNAMIC)
-			port_open_helper(nc, rtype);
+	addrlen = sizeof(addr);
+	newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
+	if (newsock == -1) {
+		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 == -1) {
+		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) == -1) {
+		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);
+			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 ||
+			    (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));
 			}
-			chan_mark_dead(c);
+			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 == -1 && (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 == -1 && (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 == -1 &&
+	    (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_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 == -1 && (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(Channel *c, fd_set *readset, fd_set *writeset)
+channel_handle_efd_read(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	char buf[CHAN_RBUF];
-	int len;
+	ssize_t len;
+	int r, force;
 
-/** 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);
-			}
+	force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
+
+	if (c->efd == -1 || (!force && !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 == -1 && (errno == EINTR || ((errno == EAGAIN ||
+	    errno == EWOULDBLOCK) && !force)))
+		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);
@@ -1860,90 +2197,112 @@ 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);
-		len = read(c->rfd, buf, MIN(rlen, CHAN_RBUF));
+	if (sshbuf_len(c->input) < need) {
+		rlen = need - sshbuf_len(c->input);
+		len = read(c->rfd, buf, MINIMUM(rlen, CHAN_RBUF));
+		if (len == -1 && (errno == EINTR || errno == EAGAIN))
+			return sshbuf_len(c->input);
 		if (len <= 0) {
-			if (errno != EINTR && errno != EAGAIN) {
-				debug2("channel %d: ctl read<=0 rfd %d len %d",
-				    c->self, c->rfd, len);
-				chan_read_failed(c);
-				return 0;
-			}
-		} else
-			buffer_append(&c->input, buf, len);
+			debug2("channel %d: ctl read<=0 rfd %d len %zd",
+			    c->self, c->rfd, len);
+			chan_read_failed(ssh, c);
+			return 0;
+		} 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 == -1 && (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;
@@ -1970,7 +2329,7 @@ channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
 		return;
 	}
 
-	if (getpeereid(newsock, &euid, &egid) < 0) {
+	if (getpeereid(newsock, &euid, &egid) == -1) {
 		error("%s getpeereid failed: %s", __func__,
 		    strerror(errno));
 		close(newsock);
@@ -1982,166 +2341,101 @@ 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)
-{
-	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)
+channel_handler_init(struct ssh_channels *sc)
 {
-	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;
@@ -2151,7 +2445,7 @@ 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
@@ -2165,7 +2459,7 @@ 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",
@@ -2173,16 +2467,39 @@ 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 = MAX(*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 */
@@ -2192,16 +2509,16 @@ channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
 
 	/* perhaps check sz < nalloc/2 and shrink? */
 	if (*readsetp == NULL || sz > *nallocp) {
-		*readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
-		*writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
+		*readsetp = xreallocarray(*readsetp, nfdset, sizeof(fd_mask));
+		*writesetp = xreallocarray(*writesetp, nfdset, sizeof(fd_mask));
 		*nallocp = sz;
 	}
 	*maxfdp = n;
 	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);
 }
 
@@ -2210,21 +2527,136 @@ 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(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)
 {
-	channel_handler(channel_post, readset, writeset, NULL);
+	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;
 
@@ -2232,354 +2664,525 @@ 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 + 4;
-					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));
+		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 (!(c->flags & CHAN_EOF_SENT) &&
+		    c->extended_usage == CHAN_EXTENDED_READ)
+			channel_output_poll_extended_read(ssh, c);
+	}
+}
+
+/* -- mux proxy support  */
+
+/*
+ * When multiplexing channel messages for mux clients we have to deal
+ * with downstream messages from the mux client and upstream messages
+ * from the ssh server:
+ * 1) Handling downstream messages is straightforward and happens
+ *    in channel_proxy_downstream():
+ *    - We forward all messages (mostly) unmodified to the server.
+ *    - However, in order to route messages from upstream to the correct
+ *      downstream client, we have to replace the channel IDs used by the
+ *      mux clients with a unique channel ID because the mux clients might
+ *      use conflicting channel IDs.
+ *    - so we inspect and change both SSH2_MSG_CHANNEL_OPEN and
+ *      SSH2_MSG_CHANNEL_OPEN_CONFIRMATION messages, create a local
+ *      SSH_CHANNEL_MUX_PROXY channel and replace the mux clients ID
+ *      with the newly allocated channel ID.
+ * 2) Upstream messages are received by matching SSH_CHANNEL_MUX_PROXY
+ *    channels and processed by channel_proxy_upstream(). The local channel ID
+ *    is then translated back to the original mux client ID.
+ * 3) In both cases we need to keep track of matching SSH2_MSG_CHANNEL_CLOSE
+ *    messages so we can clean up SSH_CHANNEL_MUX_PROXY channels.
+ * 4) The SSH_CHANNEL_MUX_PROXY channels also need to closed when the
+ *    downstream mux client are removed.
+ * 5) Handling SSH2_MSG_CHANNEL_OPEN messages from the upstream server
+ *    requires more work, because they are not addressed to a specific
+ *    channel. E.g. client_request_forwarded_tcpip() needs to figure
+ *    out whether the request is addressed to the local client or a
+ *    specific downstream client based on the listen-address/port.
+ * 6) Agent and X11-Forwarding have a similar problem and are currently
+ *    not supported as the matching session/channel cannot be identified
+ *    easily.
+ */
+
+/*
+ * receive packets from downstream mux clients:
+ * channel callback fired on read from mux client, creates
+ * SSH_CHANNEL_MUX_PROXY channels and translates channel IDs
+ * on channel creation.
+ */
+int
+channel_proxy_downstream(struct ssh *ssh, Channel *downstream)
+{
+	Channel *c = NULL;
+	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;
+	u_int id, remote_id, listen_port;
+
+	/* 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;
+	}
+	if (have < 2) {
+		error("%s: short message", __func__);
+		return -1;
+	}
+	type = cp[1];
+	/* skip padlen + type */
+	cp += 2;
+	have -= 2;
+	if (ssh_packet_log_type(type))
+		debug3("%s: channel %u: down->up: type %u", __func__,
+		    downstream->self, type);
+
+	switch (type) {
+	case SSH2_MSG_CHANNEL_OPEN:
+		if ((original = sshbuf_from(cp, have)) == NULL ||
+		    (modified = sshbuf_new()) == NULL) {
+			error("%s: alloc", __func__);
+			goto out;
+		}
+		if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0 ||
+		    (r = sshbuf_get_u32(original, &id)) != 0) {
+			error("%s: parse error %s", __func__, ssh_err(r));
+			goto out;
+		}
+		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 */
+		if ((r = sshbuf_put_cstring(modified, ctype)) != 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(ssh, c);
+			goto out;
+		}
+		break;
+	case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
+		/*
+		 * Almost the same as SSH2_MSG_CHANNEL_OPEN, except then we
+		 * need to parse 'remote_id' instead of 'ctype'.
+		 */
+		if ((original = sshbuf_from(cp, have)) == NULL ||
+		    (modified = sshbuf_new()) == NULL) {
+			error("%s: alloc", __func__);
+			goto out;
+		}
+		if ((r = sshbuf_get_u32(original, &remote_id)) != 0 ||
+		    (r = sshbuf_get_u32(original, &id)) != 0) {
+			error("%s: parse error %s", __func__, ssh_err(r));
+			goto out;
+		}
+		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(ssh, c);
+			goto out;
+		}
+		break;
+	case SSH2_MSG_GLOBAL_REQUEST:
+		if ((original = sshbuf_from(cp, have)) == NULL) {
+			error("%s: alloc", __func__);
+			goto out;
+		}
+		if ((r = sshbuf_get_cstring(original, &ctype, NULL)) != 0) {
+			error("%s: parse error %s", __func__, ssh_err(r));
+			goto out;
+		}
+		if (strcmp(ctype, "tcpip-forward") != 0) {
+			error("%s: unsupported request %s", __func__, ctype);
+			goto out;
+		}
+		if ((r = sshbuf_get_u8(original, NULL)) != 0 ||
+		    (r = sshbuf_get_cstring(original, &listen_host, NULL)) != 0 ||
+		    (r = sshbuf_get_u32(original, &listen_port)) != 0) {
+			error("%s: parse error %s", __func__, ssh_err(r));
+			goto out;
+		}
+		if (listen_port > 65535) {
+			error("%s: tcpip-forward for %s: bad port %u",
+			    __func__, listen_host, listen_port);
+			goto out;
+		}
+		/* Record that connection to this host/port is permitted. */
+		permission_set_add(ssh, FORWARD_USER, FORWARD_LOCAL, "<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(ssh, remote_id)) != NULL) {
+			if (c->flags & CHAN_CLOSE_RCVD)
+				channel_free(ssh, c);
 			else
-				chan_ibuf_empty(c);
+				c->flags |= CHAN_CLOSE_SENT;
 		}
-		/* 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);
+		break;
+	}
+	if (modified) {
+		if ((r = sshpkt_start(ssh, type)) != 0 ||
+		    (r = sshpkt_putb(ssh, modified)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0) {
+			error("%s: send %s", __func__, ssh_err(r));
+			goto out;
+		}
+	} else {
+		if ((r = sshpkt_start(ssh, type)) != 0 ||
+		    (r = sshpkt_put(ssh, cp, have)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0) {
+			error("%s: send %s", __func__, ssh_err(r));
+			goto out;
 		}
 	}
+	ret = 0;
+ out:
+	free(ctype);
+	free(listen_host);
+	sshbuf_free(original);
+	sshbuf_free(modified);
+	return ret;
 }
 
+/*
+ * receive packets from upstream server and de-multiplex packets
+ * to correct downstream:
+ * implemented as a helper for channel input handlers,
+ * replaces local (proxy) channel ID with downstream channel ID.
+ */
+int
+channel_proxy_upstream(Channel *c, int type, u_int32_t seq, struct ssh *ssh)
+{
+	struct sshbuf *b = NULL;
+	Channel *downstream;
+	const u_char *cp = NULL;
+	size_t len;
+	int r;
+
+	/*
+	 * When receiving packets from the peer we need to check whether we
+	 * need to forward the packets to the mux client. In this case we
+	 * restore the original channel id and keep track of CLOSE messages,
+	 * so we can cleanup the channel.
+	 */
+	if (c == NULL || c->type != SSH_CHANNEL_MUX_PROXY)
+		return 0;
+	if ((downstream = c->mux_ctx) == NULL)
+		return 0;
+	switch (type) {
+	case SSH2_MSG_CHANNEL_CLOSE:
+	case SSH2_MSG_CHANNEL_DATA:
+	case SSH2_MSG_CHANNEL_EOF:
+	case SSH2_MSG_CHANNEL_EXTENDED_DATA:
+	case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
+	case SSH2_MSG_CHANNEL_OPEN_FAILURE:
+	case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
+	case SSH2_MSG_CHANNEL_SUCCESS:
+	case SSH2_MSG_CHANNEL_FAILURE:
+	case SSH2_MSG_CHANNEL_REQUEST:
+		break;
+	default:
+		debug2("%s: channel %u: unsupported type %u", __func__,
+		    c->self, type);
+		return 0;
+	}
+	if ((b = sshbuf_new()) == NULL) {
+		error("%s: alloc reply", __func__);
+		goto out;
+	}
+	/* get remaining payload (after id) */
+	cp = sshpkt_ptr(ssh, &len);
+	if (cp == NULL) {
+		error("%s: no packet", __func__);
+		goto out;
+	}
+	/* translate id and send to muxclient */
+	if ((r = sshbuf_put_u8(b, 0)) != 0 ||	/* padlen */
+	    (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) {
+		error("%s: compose for muxclient %s", __func__, ssh_err(r));
+		goto out;
+	}
+	/* sshbuf_dump(b, stderr); */
+	if (ssh_packet_log_type(type))
+		debug3("%s: channel %u: up->down: type %u", __func__, c->self,
+		    type);
+ out:
+	/* update state */
+	switch (type) {
+	case SSH2_MSG_CHANNEL_OPEN_CONFIRMATION:
+		/* record remote_id for SSH2_MSG_CHANNEL_CLOSE */
+		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(ssh, c);
+		else
+			c->flags |= CHAN_CLOSE_RCVD;
+		break;
+	}
+	sshbuf_free(b);
+	return 1;
+}
 
 /* -- 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, 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 ||
+            (r = sshpkt_get_end(ssh)) != 0)
+		fatal("%s: channel %d: get data: %s", __func__,
+		    c->self, ssh_err(r));
+
 	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, 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 ||
+            (r = sshpkt_get_end(ssh)) != 0) {
+		error("%s: parse data: %s", __func__, ssh_err(r));
+		ssh_packet_disconnect(ssh, "Invalid extended_data message");
+	}
+
 	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");
+	int r;
 
-	id = packet_get_int();
-	packet_check_eom();
-	c = channel_lookup(id);
-	if (c == NULL)
-		packet_disconnect("Received ieof for nonexistent channel %d.", id);
-	chan_rcvd_ieof(c);
+        if ((r = sshpkt_get_end(ssh)) != 0) {
+		error("%s: parse data: %s", __func__, ssh_err(r));
+		ssh_packet_disconnect(ssh, "Invalid ieof message");
+	}
+
+	if (channel_proxy_upstream(c, type, seq, ssh))
+		return 0;
+	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);
+		if (sshbuf_len(c->input) == 0)
+			chan_ibuf_empty(ssh, c);
 	}
 	return 0;
 }
 
-/* ARGSUSED */
 int
-channel_input_close(int type, u_int32_t seq, void *ctxt)
+channel_input_oclose(int type, u_int32_t seq, struct ssh *ssh)
 {
-	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);
-
-	/*
-	 * 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();
+	Channel *c = channel_from_packet_id(ssh, __func__, "oclose");
+	int r;
 
-	/*
-	 * 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 (channel_proxy_upstream(c, type, seq, ssh))
+		return 0;
+        if ((r = sshpkt_get_end(ssh)) != 0) {
+		error("%s: parse data: %s", __func__, ssh_err(r));
+		ssh_packet_disconnect(ssh, "Invalid oclose message");
 	}
+	chan_rcvd_oclose(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)
-{
-	int id = packet_get_int();
-	Channel *c = channel_lookup(id);
-
-	packet_check_eom();
-	if (c == NULL)
-		packet_disconnect("Received oclose for nonexistent channel %d.", id);
-	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);
-
-	packet_check_eom();
-	if (c == NULL)
-		packet_disconnect("Received close confirmation for "
-		    "out-of-range channel %d.", id);
-	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);
-	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;
+	Channel *c = channel_from_packet_id(ssh, __func__, "open confirmation");
+	u_int32_t remote_window, remote_maxpacket;
+	int r;
 
-	id = packet_get_int();
-	c = channel_lookup(id);
+	if (channel_proxy_upstream(c, type, seq, ssh))
+		return 0;
+	if (c->type != SSH_CHANNEL_OPENING)
+		ssh_packet_disconnect(ssh, "Received open confirmation for "
+		    "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 ||
+            (r = sshpkt_get_end(ssh)) != 0) {
+		error("%s: window/maxpacket: %s", __func__, ssh_err(r));
+		ssh_packet_disconnect(ssh, "Invalid open confirmation message");
+	}
 
-	if (c==NULL || 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->have_remote_id = 1;
+	c->remote_window = remote_window;
+	c->remote_maxpacket = remote_maxpacket;
 	c->type = SSH_CHANNEL_OPEN;
-
-	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);
+	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;
 }
 
@@ -2599,135 +3202,107 @@ 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;
+	Channel *c = channel_from_packet_id(ssh, __func__, "open failure");
+	u_int32_t reason;
+	char *msg = NULL;
+	int r;
 
-	id = packet_get_int();
-	c = channel_lookup(id);
-
-	if (c==NULL || 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");
-		}
+	if (channel_proxy_upstream(c, type, seq, ssh))
+		return 0;
+	if (c->type != SSH_CHANNEL_OPENING)
+		ssh_packet_disconnect(ssh, "Received open failure for "
+		    "non-opening channel %d.", c->self);
+	if ((r = sshpkt_get_u32(ssh, &reason)) != 0) {
+		error("%s: reason: %s", __func__, ssh_err(r));
+		ssh_packet_disconnect(ssh, "Invalid open failure message");
+	}
+	/* skip language */
+	if ((r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
+	    (r = sshpkt_get_string_direct(ssh, NULL, NULL)) != 0 ||
+            (r = sshpkt_get_end(ssh)) != 0) {
+		error("%s: message/lang: %s", __func__, ssh_err(r));
+		ssh_packet_disconnect(ssh, "Invalid open failure message");
+	}
+	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);
 	}
-	packet_check_eom();
 	/* 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;
+	u_int32_t adjust;
+	u_int new_rwin;
+	int r;
 
-	if (!compat20)
-		return 0;
-
-	/* Get the channel number and verify it. */
-	id = packet_get_int();
-	c = channel_lookup(id);
-
-	if (c == NULL) {
+	if ((c = channel_lookup(ssh, id)) == NULL) {
 		logit("Received window adjust for non-open channel %d.", id);
 		return 0;
 	}
-	adjust = packet_get_int();
-	packet_check_eom();
-	debug2("channel %d: rcvd adjust %u", id, adjust);
-	c->remote_window += adjust;
-	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)");
+	if (channel_proxy_upstream(c, type, seq, ssh))
+		return 0;
+	if ((r = sshpkt_get_u32(ssh, &adjust)) != 0 ||
+            (r = sshpkt_get_end(ssh)) != 0) {
+		error("%s: adjust: %s", __func__, ssh_err(r));
+		ssh_packet_disconnect(ssh, "Invalid window adjust message");
 	}
-	packet_check_eom();
-	c = channel_connect_to_port(host, host_port,
-	    "connected socket", originator_string);
-	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;
+	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",
+		    c->self, adjust, c->remote_window);
+	}
+	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();
-	packet_check_eom();
+	ssh_packet_set_alive_timeouts(ssh, 0);
 
-	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, ssh))
 		return 0;
-	}	
+        if (sshpkt_get_end(ssh) != 0)
+		ssh_packet_disconnect(ssh, "Invalid status confirm message");
 	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);
+	freezero(cc, sizeof(*cc));
 	return 0;
 }
 
 /* -- tcp forwarding */
 
 void
-channel_set_af(int af)
+channel_set_af(struct ssh *ssh, int af)
 {
-	IPv4or6 = af;
+	ssh->chanctxt->IPv4or6 = af;
 }
 
 
@@ -2747,7 +3322,7 @@ channel_set_af(int af)
  * "127.0.0.1" / "::1"     -> accepted even if gateway_ports isn't set
  */
 static const char *
-channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
+channel_fwd_bind_addr(struct ssh *ssh, const char *listen_addr, int *wildcardp,
     int is_client, struct ForwardOptions *fwd_opts)
 {
 	const char *addr = NULL;
@@ -2770,14 +3345,20 @@ channel_fwd_bind_addr(const char *listen_addr, int *wildcardp,
 			if (*listen_addr != '\0' &&
 			    strcmp(listen_addr, "0.0.0.0") != 0 &&
 			    strcmp(listen_addr, "*") != 0) {
-				packet_send_debug("Forwarding listen address "
+				ssh_packet_send_debug(ssh,
+				    "Forwarding listen address "
 				    "\"%s\" overridden by server "
 				    "GatewayPorts", listen_addr);
 			}
 		} else if (strcmp(listen_addr, "localhost") != 0 ||
 		    strcmp(listen_addr, "127.0.0.1") == 0 ||
 		    strcmp(listen_addr, "::1") == 0) {
-			/* Accept localhost address when GatewayPorts=yes */
+			/*
+			 * Accept explicit localhost address when
+			 * GatewayPorts=yes. The "localhost" hostname is
+			 * deliberately skipped here so it will listen on all
+			 * available local address families.
+			 */
 			addr = listen_addr;
 		}
 	} else if (strcmp(listen_addr, "127.0.0.1") == 0 ||
@@ -2795,8 +3376,9 @@ 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;
@@ -2805,21 +3387,25 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 	char ntop[NI_MAXHOST], strport[NI_MAXSERV];
 	in_port_t *lport_p;
 
-	host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
-	    fwd->listen_host : fwd->connect_host;
 	is_client = (type == SSH_CHANNEL_PORT_LISTENER);
 
-	if (host == NULL) {
-		error("No forward host name.");
-		return 0;
-	}
-	if (strlen(host) >= NI_MAXHOST) {
-		error("Forward host name too long.");
-		return 0;
+	if (is_client && fwd->connect_path != NULL) {
+		host = fwd->connect_path;
+	} else {
+		host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
+		    fwd->listen_host : fwd->connect_host;
+		if (host == NULL) {
+			error("No forward host name.");
+			return 0;
+		}
+		if (strlen(host) >= NI_MAXHOST) {
+			error("Forward host name too long.");
+			return 0;
+		}
 	}
 
 	/* Determine the bind address, cf. channel_fwd_bind_addr() comment */
-	addr = channel_fwd_bind_addr(fwd->listen_host, &wildcard,
+	addr = channel_fwd_bind_addr(ssh, fwd->listen_host, &wildcard,
 	    is_client, fwd_opts);
 	debug3("%s: type %d wildcard %d addr %s", __func__,
 	    type, wildcard, (addr == NULL) ? "NULL" : addr);
@@ -2829,14 +3415,14 @@ 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);
 	if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
 		if (addr == NULL) {
 			/* This really shouldn't happen */
-			packet_disconnect("getaddrinfo: fatal error: %s",
+			ssh_packet_disconnect(ssh, "getaddrinfo: fatal error: %s",
 			    ssh_gai_strerror(r));
 		} else {
 			error("%s: getaddrinfo(%.64s): %s", __func__, addr,
@@ -2863,24 +3449,27 @@ 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;
 		}
 		/* Create a port to listen for the host. */
 		sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
-		if (sock < 0) {
+		if (sock == -1) {
 			/* this is no error since kernel may not support ipv6 */
-			verbose("socket: %.100s", strerror(errno));
+			verbose("socket [%s]:%s: %.100s", ntop, strport,
+			    strerror(errno));
 			continue;
 		}
 
-		channel_set_reuseaddr(sock);
+		set_reuseaddr(sock);
 		if (ai->ai_family == AF_INET6)
 			sock_set_v6only(sock);
 
@@ -2888,19 +3477,26 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 		    ntop, strport);
 
 		/* 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 */
+		if (bind(sock, ai->ai_addr, ai->ai_addrlen) == -1) {
+			/*
+			 * address can be in if use ipv6 address is
+			 * already bound
+			 */
 			if (!ai->ai_next)
-				error("bind: %.100s", strerror(errno));
+				error("bind [%s]:%s: %.100s",
+				    ntop, strport, strerror(errno));
 			else
-				verbose("bind: %.100s", strerror(errno));
+				verbose("bind [%s]:%s: %.100s",
+				    ntop, strport, strerror(errno));
 
 			close(sock);
 			continue;
 		}
 		/* Start listening for connections on the socket. */
-		if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
+		if (listen(sock, SSH_LISTEN_BACKLOG) == -1) {
 			error("listen: %.100s", strerror(errno));
+			error("listen [%s]:%s: %.100s", ntop, strport,
+			    strerror(errno));
 			close(sock);
 			continue;
 		}
@@ -2909,16 +3505,17 @@ 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_sock_port(sock, 1);
+			*allocated_listen_port = get_local_port(sock);
 			debug("Allocated listen port %d",
 			    *allocated_listen_port);
 		}
 
 		/* 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);
@@ -2939,8 +3536,8 @@ 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;
@@ -3002,7 +3599,7 @@ 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);
@@ -3013,66 +3610,71 @@ 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);
+	const char *addr = channel_fwd_bind_addr(ssh, 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)
@@ -3090,16 +3692,16 @@ 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;
@@ -3109,54 +3711,143 @@ 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);
 	}
 }
 
+/* Matches a remote forwarding permission against a requested forwarding */
+static int
+remote_open_match(struct permission *allowed_open, struct Forward *fwd)
+{
+	int ret;
+	char *lhost;
+
+	/* XXX add ACLs for streamlocal */
+	if (fwd->listen_path != NULL)
+		return 1;
+
+	if (fwd->listen_host == NULL || allowed_open->listen_host == NULL)
+		return 0;
+
+	if (allowed_open->listen_port != FWD_PERMIT_ANY_PORT &&
+	    allowed_open->listen_port != fwd->listen_port)
+		return 0;
+
+	/* Match hostnames case-insensitively */
+	lhost = xstrdup(fwd->listen_host);
+	lowercase(lhost);
+	ret = match_pattern(lhost, allowed_open->listen_host);
+	free(lhost);
+
+	return ret;
+}
+
+/* Checks whether a requested remote forwarding is permitted */
+static int
+check_rfwd_permission(struct ssh *ssh, struct Forward *fwd)
+{
+	struct ssh_channels *sc = ssh->chanctxt;
+	struct permission_set *pset = &sc->remote_perms;
+	u_int i, permit, permit_adm = 1;
+	struct permission *perm;
+
+	/* XXX apply GatewayPorts override before checking? */
+
+	permit = pset->all_permitted;
+	if (!permit) {
+		for (i = 0; i < pset->num_permitted_user; i++) {
+			perm = &pset->permitted_user[i];
+			if (remote_open_match(perm, fwd)) {
+				permit = 1;
+				break;
+			}
+		}
+	}
+
+	if (pset->num_permitted_admin > 0) {
+		permit_adm = 0;
+		for (i = 0; i < pset->num_permitted_admin; i++) {
+			perm = &pset->permitted_admin[i];
+			if (remote_open_match(perm, fwd)) {
+				permit_adm = 1;
+				break;
+			}
+		}
+	}
+
+	return permit && permit_adm;
+}
+
 /* 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 (!check_rfwd_permission(ssh, fwd)) {
+		ssh_packet_send_debug(ssh, "port forwarding refused");
+		if (fwd->listen_path != NULL)
+			/* XXX always allowed, see remote_open_match() */
+			logit("Received request from %.100s port %d to "
+			    "remote forward to path \"%.100s\", "
+			    "but the request was denied.",
+			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
+			    fwd->listen_path);
+		else if(fwd->listen_host != NULL)
+			logit("Received request from %.100s port %d to "
+			    "remote forward to host %.100s port %d, "
+			    "but the request was denied.",
+			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
+			    fwd->listen_host, fwd->listen_port );
+		else
+			logit("Received request from %.100s port %d to remote "
+			    "forward, but the request was denied.",
+			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
+		return 0;
+	}
 	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);
 	}
@@ -3170,15 +3861,9 @@ static const char *
 channel_rfwd_bind_host(const char *listen_host)
 {
 	if (listen_host == NULL) {
-		if (datafellows & SSH_BUG_RFWD_ADDR)
-			return "127.0.0.1";
-		else
-			return "localhost";
+		return "localhost";
 	} else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0) {
-		if (datafellows & SSH_BUG_RFWD_ADDR)
-			return "0.0.0.0";
-		else
-			return "";
+		return "";
 	} else
 		return listen_host;
 }
@@ -3187,87 +3872,68 @@ channel_rfwd_bind_host(const char *listen_host)
  * Initiate forwarding of connections to port "port" on remote host through
  * the secure channel to host:port from local side.
  * Returns handle (index) for updating the dynamic listen port with
- * channel_update_permitted_opens().
+ * channel_update_permission().
  */
 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 = xrealloc(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;
 		}
+		idx = permission_set_add(ssh, FORWARD_USER, FORWARD_LOCAL,
+		    host_to_connect, port_to_connect,
+		    listen_host, listen_path, listen_port, NULL);
 	}
-	return (idx);
+	return idx;
 }
 
 static int
-open_match(ForwardPermission *allowed_open, const char *requestedhost,
+open_match(struct permission *allowed_open, const char *requestedhost,
     int requestedport)
 {
 	if (allowed_open->host_to_connect == NULL)
@@ -3275,7 +3941,8 @@ open_match(ForwardPermission *allowed_open, const char *requestedhost,
 	if (allowed_open->port_to_connect != FWD_PERMIT_ANY_PORT &&
 	    allowed_open->port_to_connect != requestedport)
 		return 0;
-	if (strcmp(allowed_open->host_to_connect, requestedhost) != 0)
+	if (strcmp(allowed_open->host_to_connect, FWD_PERMIT_ANY_HOST) != 0 &&
+	    strcmp(allowed_open->host_to_connect, requestedhost) != 0)
 		return 0;
 	return 1;
 }
@@ -3287,7 +3954,7 @@ open_match(ForwardPermission *allowed_open, const char *requestedhost,
  * and what we've sent to the remote server (channel_rfwd_bind_host)
  */
 static int
-open_listen_match_tcpip(ForwardPermission *allowed_open,
+open_listen_match_tcpip(struct permission *allowed_open,
     const char *requestedhost, u_short requestedport, int translate)
 {
 	const char *allowed_host;
@@ -3302,14 +3969,14 @@ open_listen_match_tcpip(ForwardPermission *allowed_open,
 	allowed_host = translate ?
 	    channel_rfwd_bind_host(allowed_open->listen_host) :
 	    allowed_open->listen_host;
-	if (allowed_host == NULL ||
+	if (allowed_host == NULL || requestedhost == NULL ||
 	    strcmp(allowed_host, requestedhost) != 0)
 		return 0;
 	return 1;
 }
 
 static int
-open_listen_match_streamlocal(ForwardPermission *allowed_open,
+open_listen_match_streamlocal(struct permission *allowed_open,
     const char *requestedpath)
 {
 	if (allowed_open->host_to_connect == NULL)
@@ -3327,35 +3994,34 @@ 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;
+	struct permission_set *pset = &sc->local_perms;
+	int r;
+	u_int i;
+	struct permission *perm = NULL;
 
-	for (i = 0; i < num_permitted_opens; i++) {
-		if (open_listen_match_tcpip(&permitted_opens[i], host, port, 0))
+	for (i = 0; i < pset->num_permitted_user; i++) {
+		perm = &pset->permitted_user[i];
+		if (open_listen_match_tcpip(perm, host, port, 0))
 			break;
+		perm = NULL;
 	}
-	if (i >= num_permitted_opens) {
+	if (perm == 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;
+	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(perm); /* unregister */
 
 	return 0;
 }
@@ -3365,34 +4031,33 @@ 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;
+	struct permission_set *pset = &sc->local_perms;
+	int r;
+	u_int i;
+	struct permission *perm = NULL;
 
-	for (i = 0; i < num_permitted_opens; i++) {
-		if (open_listen_match_streamlocal(&permitted_opens[i], path))
+	for (i = 0; i < pset->num_permitted_user; i++) {
+		perm = &pset->permitted_user[i];
+		if (open_listen_match_streamlocal(perm, path))
 			break;
+		perm = NULL;
 	}
-	if (i >= num_permitted_opens) {
+	if (perm == 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();
+	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));
 
-	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;
+	fwd_perm_clear(perm); /* unregister */
 
 	return 0;
 }
@@ -3401,83 +4066,77 @@ 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);
 	}
 }
 
 /*
- * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
- * listening for the port, and sends back a success reply (or disconnect
- * message if there was an error).
+ * Permits opening to any host/port if permitted_user[] is empty.  This is
+ * usually called by the server, because the user could connect to any port
+ * anyway, and the server has no way to know but to trust the client anyway.
  */
-int
-channel_input_port_forward_request(int is_root, struct ForwardOptions *fwd_opts)
+void
+channel_permit_all(struct ssh *ssh, int where)
 {
-	int success = 0;
-	struct Forward fwd;
+	struct permission_set *pset = permission_set_get(ssh, where);
 
-	/* Get arguments from the packet. */
-	memset(&fwd, 0, sizeof(fwd));
-	fwd.listen_port = packet_get_int();
-	fwd.connect_host = packet_get_string(NULL);
-	fwd.connect_port = packet_get_int();
+	if (pset->num_permitted_user == 0)
+		pset->all_permitted = 1;
+}
+
+/*
+ * Permit the specified host/port for forwarding.
+ */
+void
+channel_add_permission(struct ssh *ssh, int who, int where,
+    char *host, int port)
+{
+	int local = where == FORWARD_LOCAL;
+	struct permission_set *pset = permission_set_get(ssh, where);
 
-#ifndef HAVE_CYGWIN
+	debug("allow %s forwarding to host %s port %d",
+	    fwd_ident(who, where), host, port);
 	/*
-	 * Check that an unprivileged user is not trying to forward a
-	 * privileged port.
+	 * Remote forwards set listen_host/port, local forwards set
+	 * host/port_to_connect.
 	 */
-	if (fwd.listen_port < IPPORT_RESERVED && !is_root)
-		packet_disconnect(
-		    "Requested forwarding of port %d but user is not root.",
-		    fwd.listen_port);
-	if (fwd.connect_port == 0)
-		packet_disconnect("Dynamic forwarding denied.");
-#endif
-
-	/* Initiate forwarding */
-	success = channel_setup_local_fwd_listener(&fwd, fwd_opts);
-
-	/* Free the argument string. */
-	free(fwd.connect_host);
-
-	return (success ? 0 : -1);
+	permission_set_add(ssh, who, where,
+	    local ? host : 0, local ? port : 0,
+	    local ? NULL : host, NULL, local ? 0 : port, NULL);
+	pset->all_permitted = 0;
 }
 
 /*
- * Permits opening to any host/port if permitted_opens[] is empty.  This is
- * usually called by the server, because the user could connect to any port
- * anyway, and the server has no way to know but to trust the client anyway.
+ * Administratively disable forwarding.
  */
 void
-channel_permit_all_opens(void)
+channel_disable_admin(struct ssh *ssh, int where)
 {
-	if (num_permitted_opens == 0)
-		all_opens_permitted = 1;
+	channel_clear_permission(ssh, FORWARD_ADM, where);
+	permission_set_add(ssh, FORWARD_ADM, where,
+	    NULL, 0, NULL, NULL, 0, NULL);
 }
 
+/*
+ * Clear a list of permitted opens.
+ */
 void
-channel_add_permitted_opens(char *host, int port)
+channel_clear_permission(struct ssh *ssh, int who, int where)
 {
-	debug("allow port forwarding to host %s port %d", host, port);
+	struct permission **permp;
+	u_int *npermp;
 
-	permitted_opens = xrealloc(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;
-	num_permitted_opens++;
-
-	all_opens_permitted = 0;
+	permission_set_get_array(ssh, who, where, &permp, &npermp);
+	*permp = xrecallocarray(*permp, *npermp, 0, sizeof(**permp));
+	*npermp = 0;
 }
 
 /*
@@ -3486,105 +4145,26 @@ 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_permission(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 permission_set *pset = &ssh->chanctxt->local_perms;
+
+	if (idx < 0 || (u_int)idx >= pset->num_permitted_user) {
+		debug("%s: index out of range: %d num_permitted_user %d",
+		    __func__, idx, pset->num_permitted_user);
 		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 = 
+	    pset->permitted_user[idx].host_to_connect,
+	    pset->permitted_user[idx].port_to_connect);
+	if (newport <= 0)
+		fwd_perm_clear(&pset->permitted_user[idx]);
+	else {
+		pset->permitted_user[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)
-{
-	debug("config allows port forwarding to host %s port %d", host, port);
-
-	permitted_adm_opens = xrealloc(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;
-}
-
-void
-channel_disable_adm_local_opens(void)
-{
-	channel_clear_adm_permitted_opens();
-	permitted_adm_opens = xmalloc(sizeof(*permitted_adm_opens));
-	permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
-	num_adm_permitted_opens = 1;
-}
-
-void
-channel_clear_permitted_opens(void)
-{
-	int i;
-
-	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;
-}
-
-void
-channel_clear_adm_permitted_opens(void)
-{
-	int i;
-
-	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");
 }
 
 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
@@ -3606,7 +4186,8 @@ connect_next(struct channel_connect *cctx)
 {
 	int sock, saved_errno;
 	struct sockaddr_un *sunaddr;
-	char ntop[NI_MAXHOST], strport[MAX(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) {
@@ -3671,18 +4252,19 @@ channel_connect_ctx_free(struct channel_connect *cctx)
 	memset(cctx, 0, sizeof(*cctx));
 }
 
-/* Return CONNECTING channel to remote host:port or local socket path */
-static Channel *
-connect_to(const char *name, int port, char *ctype, char *rname)
+/*
+ * Return connecting socket to remote host:port or local socket path,
+ * passing back the failure reason if appropriate.
+ */
+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;
@@ -3690,7 +4272,7 @@ connect_to(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;
 		}
 
 		/*
@@ -3703,52 +4285,92 @@ connect_to(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)) != 0) {
+		if ((gaierr = getaddrinfo(name, strport, &hints, &cctx->aitop))
+		    != 0) {
+			if (errmsg != NULL)
+				*errmsg = ssh_gai_strerror(gaierr);
+			if (reason != NULL)
+				*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));
+		return -1;
+	}
+
+	return sock;
+}
+
+/* Return CONNECTING channel to remote host:port or local socket path */
+static Channel *
+connect_to(struct ssh *ssh, const char *host, int port,
+    char *ctype, char *rname)
+{
+	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(ctype, SSH_CHANNEL_CONNECTING, sock, sock, -1,
+	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;
 }
 
+/*
+ * returns either the newly connected channel or the downstream channel
+ * 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)) {
-			return connect_to(
-			    permitted_opens[i].host_to_connect,
-			    permitted_opens[i].port_to_connect, ctype, rname);
+	struct ssh_channels *sc = ssh->chanctxt;
+	struct permission_set *pset = &sc->local_perms;
+	u_int i;
+	struct permission *perm;
+
+	for (i = 0; i < pset->num_permitted_user; i++) {
+		perm = &pset->permitted_user[i];
+		if (open_listen_match_tcpip(perm,
+		    listen_host, listen_port, 1)) {
+			if (perm->downstream)
+				return perm->downstream;
+			if (perm->port_to_connect == 0)
+				return rdynamic_connect_prepare(ssh,
+				    ctype, rname);
+			return connect_to(ssh,
+			    perm->host_to_connect, perm->port_to_connect,
+			    ctype, rname);
 		}
 	}
 	error("WARNING: Server requests forwarding for unknown listen_port %d",
@@ -3757,15 +4379,20 @@ 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;
+	struct permission_set *pset = &sc->local_perms;
+	u_int i;
+	struct permission *perm;
+
+	for (i = 0; i < pset->num_permitted_user; i++) {
+		perm = &pset->permitted_user[i];
+		if (open_listen_match_streamlocal(perm, path)) {
+			return connect_to(ssh,
+			    perm->host_to_connect, perm->port_to_connect,
+			    ctype, rname);
 		}
 	}
 	error("WARNING: Server requests forwarding for unknown path %.100s",
@@ -3775,58 +4402,95 @@ 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)
+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 permission_set *pset = &sc->local_perms;
+	struct channel_connect cctx;
+	Channel *c;
+	u_int i, permit, permit_adm = 1;
+	int sock;
+	struct permission *perm;
 
-	permit = all_opens_permitted;
+	permit = pset->all_permitted;
 	if (!permit) {
-		for (i = 0; i < num_permitted_opens; i++)
-			if (open_match(&permitted_opens[i], host, port)) {
+		for (i = 0; i < pset->num_permitted_user; i++) {
+			perm = &pset->permitted_user[i];
+			if (open_match(perm, host, port)) {
 				permit = 1;
 				break;
 			}
+		}
 	}
 
-	if (num_adm_permitted_opens > 0) {
+	if (pset->num_permitted_admin > 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 < pset->num_permitted_admin; i++) {
+			perm = &pset->permitted_admin[i];
+			if (open_match(perm, host, port)) {
 				permit_adm = 1;
 				break;
 			}
+		}
 	}
 
 	if (!permit || !permit_adm) {
-		logit("Received request to connect to host %.100s port %d, "
-		    "but the request was denied.", host, port);
+		logit("Received request from %.100s port %d to connect to "
+		    "host %.100s port %d, but the request was denied.",
+		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), host, port);
+		if (reason != NULL)
+			*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
+		return NULL;
+	}
+
+	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;
 	}
-	return connect_to(host, port, ctype, rname);
+
+	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;
+	struct permission_set *pset = &sc->local_perms;
+	u_int i, permit, permit_adm = 1;
+	struct permission *perm;
 
-	permit = all_opens_permitted;
+	permit = pset->all_permitted;
 	if (!permit) {
-		for (i = 0; i < num_permitted_opens; i++)
-			if (open_match(&permitted_opens[i], path, PORT_STREAMLOCAL)) {
+		for (i = 0; i < pset->num_permitted_user; i++) {
+			perm = &pset->permitted_user[i];
+			if (open_match(perm, path, PORT_STREAMLOCAL)) {
 				permit = 1;
 				break;
 			}
+		}
 	}
 
-	if (num_adm_permitted_opens > 0) {
+	if (pset->num_permitted_admin > 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 < pset->num_permitted_admin; i++) {
+			perm = &pset->permitted_admin[i];
+			if (open_match(perm, path, PORT_STREAMLOCAL)) {
 				permit_adm = 1;
 				break;
 			}
+		}
 	}
 
 	if (!permit || !permit_adm) {
@@ -3834,28 +4498,80 @@ 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) == -1)
 			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 */
@@ -3866,8 +4582,9 @@ 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;
@@ -3884,20 +4601,22 @@ 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);
-			if (sock < 0) {
+			if (sock == -1) {
 				if ((errno != EINVAL) && (errno != EAFNOSUPPORT)
 #ifdef EPFNOSUPPORT
 				    && (errno != EPFNOSUPPORT)
@@ -3915,14 +4634,13 @@ x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
 			if (ai->ai_family == AF_INET6)
 				sock_set_v6only(sock);
 			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));
+				set_reuseaddr(sock);
+			if (bind(sock, ai->ai_addr, ai->ai_addrlen) == -1) {
+				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;
 			}
@@ -3941,7 +4659,7 @@ x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
 	/* Start listening for connections on the socket. */
 	for (n = 0; n < num_socks; n++) {
 		sock = socks[n];
-		if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
+		if (listen(sock, SSH_LISTEN_BACKLOG) == -1) {
 			error("listen: %.100s", strerror(errno));
 			close(sock);
 			return -1;
@@ -3952,7 +4670,7 @@ 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);
@@ -3963,7 +4681,7 @@ 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
@@ -3973,7 +4691,7 @@ connect_local_xsocket_path(const char *pathname)
 	struct sockaddr_un addr;
 
 	sock = socket(AF_UNIX, SOCK_STREAM, 0);
-	if (sock < 0)
+	if (sock == -1)
 		error("socket: %.100s", strerror(errno));
 	memset(&addr, 0, sizeof(addr));
 	addr.sun_family = AF_UNIX;
@@ -3993,8 +4711,35 @@ connect_local_xsocket(u_int dnr)
 	return connect_local_xsocket_path(buf);
 }
 
+#ifdef __APPLE__
+static int
+is_path_to_xsocket(const char *display, char *path, size_t pathlen)
+{
+	struct stat sbuf;
+
+	if (strlcpy(path, display, pathlen) >= pathlen) {
+		error("%s: display path too long", __func__);
+		return 0;
+	}
+	if (display[0] != '/')
+		return 0;
+	if (stat(path, &sbuf) == 0) {
+		return 1;
+	} else {
+		char *dot = strrchr(path, '.');
+		if (dot != NULL) {
+			*dot = '\0';
+			if (stat(path, &sbuf) == 0) {
+				return 1;
+			}
+		}
+	}
+	return 0;
+}
+#endif
+
 int
-x11_connect_display(void)
+x11_connect_display(struct ssh *ssh)
 {
 	u_int display_number;
 	const char *display;
@@ -4014,15 +4759,22 @@ x11_connect_display(void)
 	 * connection to the real X server.
 	 */
 
-	/* Check if the display is from launchd. */
 #ifdef __APPLE__
-	if (strncmp(display, "/tmp/launch", 11) == 0) {
-		sock = connect_local_xsocket_path(display);
-		if (sock < 0)
-			return -1;
+	/* Check if display is a path to a socket (as set by launchd). */
+	{
+		char path[PATH_MAX];
 
-		/* OK, we now have a connection to the display. */
-		return sock;
+		if (is_path_to_xsocket(display, path, sizeof(path))) {
+			debug("x11_connect_display: $DISPLAY is launchd");
+
+			/* Create a socket. */
+			sock = connect_local_xsocket_path(path);
+			if (sock < 0)
+				return -1;
+
+			/* OK, we now have a connection to the display. */
+			return sock;
+		}
 	}
 #endif
 	/*
@@ -4032,9 +4784,10 @@ 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. */
@@ -4056,7 +4809,10 @@ 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);
@@ -4065,7 +4821,7 @@ 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) {
@@ -4076,12 +4832,12 @@ x11_connect_display(void)
 	for (ai = aitop; ai; ai = ai->ai_next) {
 		/* Create a socket. */
 		sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
-		if (sock < 0) {
+		if (sock == -1) {
 			debug2("socket: %.100s", strerror(errno));
 			continue;
 		}
 		/* Connect it to the display. */
-		if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
+		if (connect(sock, ai->ai_addr, ai->ai_addrlen) == -1) {
 			debug2("connect %.100s port %u: %.100s", buf,
 			    6000 + display_number, strerror(errno));
 			close(sock);
@@ -4092,8 +4848,8 @@ 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);
@@ -4101,99 +4857,24 @@ 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;
-	u_int32_t rnd = 0;
+	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;
@@ -4207,56 +4888,37 @@ 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);
-		/*
-		 * Extract real authentication data and generate fake data
-		 * of the same length.
-		 */
-		x11_saved_data = xmalloc(data_len);
-		x11_fake_data = xmalloc(data_len);
+		sc->x11_saved_proto = xstrdup(proto);
+
+		/* Extract real authentication data. */
+		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);
-			if (i % 4 == 0)
-				rnd = arc4random();
-			x11_saved_data[i] = value;
-			x11_fake_data[i] = rnd & 0xff;
-			rnd >>= 8;
+			sc->x11_saved_data[i] = value;
 		}
-		x11_saved_data_len = data_len;
-		x11_fake_data_len = data_len;
+		sc->x11_saved_data_len = data_len;
+
+		/* Generate fake data of the same length. */
+		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();
-}