upstream commit

refactor channels.c

Move static state to a "struct ssh_channels" that is allocated at
runtime and tracked as a member of struct ssh.

Explicitly pass "struct ssh" to all channels functions.

Replace use of the legacy packet APIs in channels.c.

Rework sshd_config PermitOpen handling: previously the configuration
parser would call directly into the channels layer. After the refactor
this is not possible, as the channels structures are allocated at
connection time and aren't available when the configuration is parsed.
The server config parser now tracks PermitOpen itself and explicitly
configures the channels code later.

ok markus@

Upstream-ID: 11828f161656b965cc306576422613614bea2d8f

25 files changed, 2441 insertions, 1992 deletions

diff --git a/auth-options.c b/auth-options.c
index 0a191dbba..bed00eef0 100644
--- a/auth-options.c
+++ b/auth-options.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth-options.c,v 1.73 2017/05/31 10:54:00 markus Exp $ */
+/* $OpenBSD: auth-options.c,v 1.74 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -61,9 +61,13 @@ char *authorized_principals = NULL;
 
 extern ServerOptions options;
 
+/* XXX refactor to be stateless */
+
 void
 auth_clear_options(void)
 {
+	struct ssh *ssh = active_state;		/* XXX */
+
 	no_agent_forwarding_flag = 0;
 	no_port_forwarding_flag = 0;
 	no_pty_flag = 0;
@@ -81,7 +85,7 @@ auth_clear_options(void)
 	free(authorized_principals);
 	authorized_principals = NULL;
 	forced_tun_device = -1;
-	channel_clear_permitted_opens();
+	channel_clear_permitted_opens(ssh);
 }
 
 /*
@@ -117,6 +121,7 @@ match_flag(const char *opt, int allow_negate, char **optsp, const char *msg)
 /*
  * return 1 if access is granted, 0 if not.
  * side effect: sets key option flags
+ * XXX remove side effects; fill structure instead.
  */
 int
 auth_parse_options(struct passwd *pw, char *opts, const char *file,
@@ -380,7 +385,7 @@ auth_parse_options(struct passwd *pw, char *opts, const char *file,
 				goto bad_option;
 			}
 			if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0)
-				channel_add_permitted_opens(host, port);
+				channel_add_permitted_opens(ssh, host, port);
 			free(patterns);
 			goto next_option;
 		}
diff --git a/auth.c b/auth.c
index 7f073e0f3..a44906174 100644
--- a/auth.c
+++ b/auth.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth.c,v 1.123 2017/08/18 05:36:45 djm Exp $ */
+/* $OpenBSD: auth.c,v 1.124 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -567,6 +567,7 @@ getpwnamallow(const char *user)
 	ci->user = user;
 	parse_server_match_config(&options, ci);
 	log_change_level(options.log_level);
+	process_permitopen(ssh, &options);
 
 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
 	aix_setauthdb(user);
diff --git a/channels.c b/channels.c
index d9e81b5fa..935625c74 100644
--- a/channels.c
+++ b/channels.c
@@ -55,26 +55,27 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <limits.h>
 #include <netdb.h>
+#include <stdarg.h>
 #ifdef HAVE_STDINT_H
-#include <stdint.h>
+ #include <stdint.h>
 #endif
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <termios.h>
 #include <unistd.h>
-#include <stdarg.h>
 
 #include "openbsd-compat/sys-queue.h"
 #include "xmalloc.h"
 #include "ssh.h"
 #include "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"
@@ -82,28 +83,19 @@
 #include "authfd.h"
 #include "pathnames.h"
 
-/* -- channel core */
-
-/*
- * Pointer to an array containing all allocated channels.  The array is
- * dynamically extended as needed.
- */
-static Channel **channels = NULL;
-
-/*
- * Size of the channel array.  All slots of the array must always be
- * initialized (at least the type field); unused slots set to NULL
- */
-static u_int channels_alloc = 0;
+/* -- agent forwarding */
+#define	NUM_SOCKS	10
 
-/*
- * Maximum file descriptor value used in any of the channels.  This is
- * updated in channel_new.
- */
-static int channel_max_fd = 0;
+/* -- tcp forwarding */
+/* special-case port number meaning allow any port */
+#define FWD_PERMIT_ANY_PORT	0
 
+/* special-case wildcard meaning allow any host */
+#define FWD_PERMIT_ANY_HOST	"*"
 
-/* -- tcp forwarding */
+/* -- X11 forwarding */
+/* Maximum number of fake X11 displays to try. */
+#define MAX_DISPLAYS  1000
 
 /*
  * Data structure for storing which hosts are permitted for forward requests.
@@ -123,100 +115,150 @@ typedef struct {
 	Channel *downstream;		/* Downstream mux*/
 } ForwardPermission;
 
-/* List of all permitted host/port pairs to connect by the user. */
-static ForwardPermission *permitted_opens = NULL;
+typedef void chan_fn(struct ssh *, Channel *c,
+    fd_set *readset, fd_set *writeset);
 
-/* List of all permitted host/port pairs to connect by the admin. */
-static ForwardPermission *permitted_adm_opens = NULL;
-
-/* Number of permitted host/port pairs in the array permitted by the user. */
-static int num_permitted_opens = 0;
+/* Master structure for channels state */
+struct ssh_channels {
+	/*
+	 * Pointer to an array containing all allocated channels.  The array
+	 * is dynamically extended as needed.
+	 */
+	Channel **channels;
 
-/* Number of permitted host/port pair in the array permitted by the admin. */
-static int num_adm_permitted_opens = 0;
+	/*
+	 * Size of the channel array.  All slots of the array must always be
+	 * initialized (at least the type field); unused slots set to NULL
+	 */
+	u_int channels_alloc;
 
-/* special-case port number meaning allow any port */
-#define FWD_PERMIT_ANY_PORT	0
+	/*
+	 * Maximum file descriptor value used in any of the channels.  This is
+	 * updated in channel_new.
+	 */
+	int channel_max_fd;
 
-/* special-case wildcard meaning allow any host */
-#define FWD_PERMIT_ANY_HOST	"*"
+	/*
+	 * 'channel_pre*' are called just before select() to add any bits
+	 * relevant to channels in the select bitmasks.
+	 *
+	 * 'channel_post*': perform any appropriate operations for
+	 * channels which have events pending.
+	 */
+	chan_fn **channel_pre;
+	chan_fn **channel_post;
 
-/*
- * If this is true, all opens are permitted.  This is the case on the server
- * on which we have to trust the client anyway, and the user could do
- * anything after logging in anyway.
- */
-static int all_opens_permitted = 0;
+	/* -- tcp forwarding */
 
+	/* List of all permitted host/port pairs to connect by the user. */
+	ForwardPermission *permitted_opens;
 
-/* -- X11 forwarding */
+	/* List of all permitted host/port pairs to connect by the admin. */
+	ForwardPermission *permitted_adm_opens;
 
-/* Maximum number of fake X11 displays to try. */
-#define MAX_DISPLAYS  1000
+	/*
+	 * Number of permitted host/port pairs in the array permitted by
+	 * the user.
+	 */
+	u_int num_permitted_opens;
 
-/* Saved X11 local (client) display. */
-static char *x11_saved_display = NULL;
+	/*
+	 * Number of permitted host/port pair in the array permitted by
+	 * the admin.
+	 */
+	u_int num_adm_permitted_opens;
 
-/* Saved X11 authentication protocol name. */
-static char *x11_saved_proto = NULL;
+	/*
+	 * If this is true, all opens are permitted.  This is the case on
+	 * the server on which we have to trust the client anyway, and the
+	 * user could do anything after logging in anyway.
+	 */
+	int all_opens_permitted;
 
-/* Saved X11 authentication data.  This is the real data. */
-static char *x11_saved_data = NULL;
-static u_int x11_saved_data_len = 0;
+	/* -- X11 forwarding */
 
-/* Deadline after which all X11 connections are refused */
-static u_int x11_refuse_time;
+	/* Saved X11 local (client) display. */
+	char *x11_saved_display;
 
-/*
- * Fake X11 authentication data.  This is what the server will be sending us;
- * we should replace any occurrences of this by the real data.
- */
-static u_char *x11_fake_data = NULL;
-static u_int x11_fake_data_len;
+	/* Saved X11 authentication protocol name. */
+	char *x11_saved_proto;
 
+	/* Saved X11 authentication data.  This is the real data. */
+	char *x11_saved_data;
+	u_int x11_saved_data_len;
 
-/* -- agent forwarding */
+	/* Deadline after which all X11 connections are refused */
+	u_int x11_refuse_time;
 
-#define	NUM_SOCKS	10
+	/*
+	 * Fake X11 authentication data.  This is what the server will be
+	 * sending us; we should replace any occurrences of this by the
+	 * real data.
+	 */
+	u_char *x11_fake_data;
+	u_int x11_fake_data_len;
 
-/* AF_UNSPEC or AF_INET or AF_INET6 */
-static int IPv4or6 = AF_UNSPEC;
+	/* AF_UNSPEC or AF_INET or AF_INET6 */
+	int IPv4or6;
+};
 
 /* helper */
-static void port_open_helper(Channel *c, char *rtype);
+static void port_open_helper(struct ssh *ssh, Channel *c, char *rtype);
 static const char *channel_rfwd_bind_host(const char *listen_host);
 
 /* non-blocking connect helpers */
 static int connect_next(struct channel_connect *);
 static void channel_connect_ctx_free(struct channel_connect *);
 
+/* Setup helper */
+static void channel_handler_init(struct ssh_channels *sc);
+
 /* -- channel core */
 
+void
+channel_init_channels(struct ssh *ssh)
+{
+	struct ssh_channels *sc;
+
+	if ((sc = calloc(1, sizeof(*sc))) == NULL ||
+	    (sc->channel_pre = calloc(SSH_CHANNEL_MAX_TYPE,
+	    sizeof(*sc->channel_pre))) == NULL ||
+	    (sc->channel_post = calloc(SSH_CHANNEL_MAX_TYPE,
+	    sizeof(*sc->channel_post))) == NULL)
+		fatal("%s: allocation failed", __func__);
+	sc->channels_alloc = 10;
+	sc->channels = xcalloc(sc->channels_alloc, sizeof(*sc->channels));
+	sc->IPv4or6 = AF_UNSPEC;
+	channel_handler_init(sc);
+
+	ssh->chanctxt = sc;
+}
+
 Channel *
-channel_by_id(int id)
+channel_by_id(struct ssh *ssh, int id)
 {
 	Channel *c;
 
-	if (id < 0 || (u_int)id >= channels_alloc) {
-		logit("channel_by_id: %d: bad id", id);
+	if (id < 0 || (u_int)id >= ssh->chanctxt->channels_alloc) {
+		logit("%s: %d: bad id", __func__, id);
 		return NULL;
 	}
-	c = channels[id];
+	c = ssh->chanctxt->channels[id];
 	if (c == NULL) {
-		logit("channel_by_id: %d: bad id: channel free", id);
+		logit("%s: %d: bad id: channel free", __func__, id);
 		return NULL;
 	}
 	return c;
 }
 
 Channel *
-channel_by_remote_id(int remote_id)
+channel_by_remote_id(struct ssh *ssh, int remote_id)
 {
 	Channel *c;
 	u_int i;
 
-	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 && c->remote_id == remote_id)
 			return c;
 	}
@@ -228,12 +270,12 @@ channel_by_remote_id(int remote_id)
  * Private channels, like listening sockets, may not receive messages.
  */
 Channel *
-channel_lookup(int id)
+channel_lookup(struct ssh *ssh, int id)
 {
 	Channel *c;
 
-	if ((c = channel_by_id(id)) == NULL)
-		return (NULL);
+	if ((c = channel_by_id(ssh, id)) == NULL)
+		return NULL;
 
 	switch (c->type) {
 	case SSH_CHANNEL_X11_OPEN:
@@ -244,10 +286,10 @@ channel_lookup(int id)
 	case SSH_CHANNEL_OPEN:
 	case SSH_CHANNEL_ABANDONED:
 	case SSH_CHANNEL_MUX_PROXY:
-		return (c);
+		return c;
 	}
 	logit("Non-public channel %d, type %d.", id, c->type);
-	return (NULL);
+	return NULL;
 }
 
 /*
@@ -255,13 +297,15 @@ channel_lookup(int id)
  * when the channel consumer/producer is ready, e.g. shell exec'd
  */
 static void
-channel_register_fds(Channel *c, int rfd, int wfd, int efd,
+channel_register_fds(struct ssh *ssh, Channel *c, int rfd, int wfd, int efd,
     int extusage, int nonblock, int is_tty)
 {
+	struct ssh_channels *sc = ssh->chanctxt;
+
 	/* Update the maximum file descriptor value. */
-	channel_max_fd = MAXIMUM(channel_max_fd, rfd);
-	channel_max_fd = MAXIMUM(channel_max_fd, wfd);
-	channel_max_fd = MAXIMUM(channel_max_fd, efd);
+	sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, rfd);
+	sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, wfd);
+	sc->channel_max_fd = MAXIMUM(sc->channel_max_fd, efd);
 
 	if (rfd != -1)
 		fcntl(rfd, F_SETFD, FD_CLOEXEC);
@@ -299,190 +343,221 @@ channel_register_fds(Channel *c, int rfd, int wfd, int efd,
  * remote_name to be freed.
  */
 Channel *
-channel_new(char *ctype, int type, int rfd, int wfd, int efd,
+channel_new(struct ssh *ssh, char *ctype, int type, int rfd, int wfd, int efd,
     u_int window, u_int maxpack, int extusage, char *remote_name, int nonblock)
 {
-	int found;
-	u_int i;
+	struct ssh_channels *sc = ssh->chanctxt;
+	u_int i, found;
 	Channel *c;
 
-	/* Do initial allocation if this is the first call. */
-	if (channels_alloc == 0) {
-		channels_alloc = 10;
-		channels = xcalloc(channels_alloc, sizeof(Channel *));
-		for (i = 0; i < channels_alloc; i++)
-			channels[i] = NULL;
-	}
 	/* Try to find a free slot where to put the new channel. */
-	for (found = -1, i = 0; i < channels_alloc; i++)
-		if (channels[i] == NULL) {
+	for (i = 0; i < sc->channels_alloc; i++) {
+		if (sc->channels[i] == NULL) {
 			/* Found a free slot. */
-			found = (int)i;
+			found = i;
 			break;
 		}
-	if (found < 0) {
-		/* There are no free slots.  Take last+1 slot and expand the array.  */
-		found = channels_alloc;
-		if (channels_alloc > 10000)
-			fatal("channel_new: internal error: channels_alloc %d "
-			    "too big.", channels_alloc);
-		channels = xreallocarray(channels, channels_alloc + 10,
-		    sizeof(Channel *));
-		channels_alloc += 10;
-		debug2("channel: expanding %d", channels_alloc);
-		for (i = found; i < channels_alloc; i++)
-			channels[i] = NULL;
+	}
+	if (i >= sc->channels_alloc) {
+		/*
+		 * There are no free slots. Take last+1 slot and expand
+		 * the array.
+		 */
+		found = sc->channels_alloc;
+		if (sc->channels_alloc > CHANNELS_MAX_CHANNELS)
+			fatal("%s: internal error: channels_alloc %d too big",
+			    __func__, sc->channels_alloc);
+		sc->channels = xrecallocarray(sc->channels, sc->channels_alloc,
+		    sc->channels_alloc + 10, sizeof(*sc->channels));
+		sc->channels_alloc += 10;
+		debug2("channel: expanding %d", sc->channels_alloc);
 	}
 	/* Initialize and return new channel. */
-	c = channels[found] = xcalloc(1, sizeof(Channel));
-	buffer_init(&c->input);
-	buffer_init(&c->output);
-	buffer_init(&c->extended);
-	c->path = NULL;
-	c->listening_addr = NULL;
-	c->listening_port = 0;
+	c = sc->channels[found] = xcalloc(1, sizeof(Channel));
+	if ((c->input = sshbuf_new()) == NULL ||
+	    (c->output = sshbuf_new()) == NULL ||
+	    (c->extended = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new failed", __func__);
 	c->ostate = CHAN_OUTPUT_OPEN;
 	c->istate = CHAN_INPUT_OPEN;
-	c->flags = 0;
-	channel_register_fds(c, rfd, wfd, efd, extusage, nonblock, 0);
-	c->notbefore = 0;
+	channel_register_fds(ssh, c, rfd, wfd, efd, extusage, nonblock, 0);
 	c->self = found;
 	c->type = type;
 	c->ctype = ctype;
 	c->local_window = window;
 	c->local_window_max = window;
-	c->local_consumed = 0;
 	c->local_maxpacket = maxpack;
 	c->remote_id = -1;
 	c->remote_name = xstrdup(remote_name);
-	c->remote_window = 0;
-	c->remote_maxpacket = 0;
-	c->force_drain = 0;
-	c->single_connection = 0;
-	c->detach_user = NULL;
-	c->detach_close = 0;
-	c->open_confirm = NULL;
-	c->open_confirm_ctx = NULL;
-	c->input_filter = NULL;
-	c->output_filter = NULL;
-	c->filter_ctx = NULL;
-	c->filter_cleanup = NULL;
 	c->ctl_chan = -1;
-	c->mux_rcb = NULL;
-	c->mux_ctx = NULL;
-	c->mux_pause = 0;
 	c->delayed = 1;		/* prevent call to channel_post handler */
 	TAILQ_INIT(&c->status_confirms);
 	debug("channel %d: new [%s]", found, remote_name);
 	return c;
 }
 
-static int
-channel_find_maxfd(void)
+static void
+channel_find_maxfd(struct ssh_channels *sc)
 {
 	u_int i;
 	int max = 0;
 	Channel *c;
 
-	for (i = 0; i < channels_alloc; i++) {
-		c = channels[i];
+	for (i = 0; i < sc->channels_alloc; i++) {
+		c = sc->channels[i];
 		if (c != NULL) {
 			max = MAXIMUM(max, c->rfd);
 			max = MAXIMUM(max, c->wfd);
 			max = MAXIMUM(max, c->efd);
 		}
 	}
-	return max;
+	sc->channel_max_fd = max;
 }
 
 int
-channel_close_fd(int *fdp)
+channel_close_fd(struct ssh *ssh, int *fdp)
 {
+	struct ssh_channels *sc = ssh->chanctxt;
 	int ret = 0, fd = *fdp;
 
 	if (fd != -1) {
 		ret = close(fd);
 		*fdp = -1;
-		if (fd == channel_max_fd)
-			channel_max_fd = channel_find_maxfd();
+		if (fd == sc->channel_max_fd)
+			channel_find_maxfd(sc);
 	}
 	return ret;
 }
 
 /* Close all channel fd/socket. */
 static void
-channel_close_fds(Channel *c)
+channel_close_fds(struct ssh *ssh, Channel *c)
+{
+	channel_close_fd(ssh, &c->sock);
+	channel_close_fd(ssh, &c->rfd);
+	channel_close_fd(ssh, &c->wfd);
+	channel_close_fd(ssh, &c->efd);
+}
+
+static void
+fwd_perm_clear(ForwardPermission *fp)
+{
+	free(fp->host_to_connect);
+	free(fp->listen_host);
+	free(fp->listen_path);
+	bzero(fp, sizeof(*fp));
+}
+
+enum { FWDPERM_USER, FWDPERM_ADMIN };
+
+static int
+fwd_perm_list_add(struct ssh *ssh, int which,
+    const char *host_to_connect, int port_to_connect,
+    const char *listen_host, const char *listen_path, int listen_port,
+    Channel *downstream)
+{
+	ForwardPermission **fpl;
+	u_int n, *nfpl;
+
+	switch (which) {
+	case FWDPERM_USER:
+		fpl = &ssh->chanctxt->permitted_opens;
+		nfpl = &ssh->chanctxt->num_permitted_opens;
+		break;
+	case FWDPERM_ADMIN:
+		fpl = &ssh->chanctxt->permitted_adm_opens;
+		nfpl = &ssh->chanctxt->num_adm_permitted_opens;
+		break;
+	default:
+		fatal("%s: invalid list %d", __func__, which);
+	}
+
+	if (*nfpl >= INT_MAX)
+		fatal("%s: overflow", __func__);
+
+	*fpl = xrecallocarray(*fpl, *nfpl, *nfpl + 1, sizeof(**fpl));
+	n = (*nfpl)++;
+#define MAYBE_DUP(s) ((s == NULL) ? NULL : xstrdup(s))
+	(*fpl)[n].host_to_connect = MAYBE_DUP(host_to_connect);
+	(*fpl)[n].port_to_connect = port_to_connect;
+	(*fpl)[n].listen_host = MAYBE_DUP(listen_host);
+	(*fpl)[n].listen_path = MAYBE_DUP(listen_path);
+	(*fpl)[n].listen_port = listen_port;
+	(*fpl)[n].downstream = downstream;
+#undef MAYBE_DUP
+	return (int)n;
+}
+
+static void
+mux_remove_remote_forwardings(struct ssh *ssh, Channel *c)
 {
-	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;
+	ForwardPermission *fp;
+	int r;
+	u_int i;
+
+	for (i = 0; i < sc->num_permitted_opens; i++) {
+		fp = &sc->permitted_opens[i];
+		if (fp->downstream != c)
+			continue;
+
+		/* cancel on the server, since mux client is gone */
+		debug("channel %d: cleanup remote forward for %s:%u",
+		    c->self, fp->listen_host, fp->listen_port);
+		if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+		    (r = sshpkt_put_cstring(ssh,
+		    "cancel-tcpip-forward")) != 0 ||
+		    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
+		    (r = sshpkt_put_cstring(ssh,
+		    channel_rfwd_bind_host(fp->listen_host))) != 0 ||
+		    (r = sshpkt_put_u32(ssh, fp->listen_port)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0) {
+			fatal("%s: channel %i: %s", __func__,
+			    c->self, ssh_err(r));
+		}
+		fwd_perm_clear(fp); /* unregister */
+	}
 }
 
 /* Free the channel and close its fd/socket. */
 void
-channel_free(Channel *c)
+channel_free(struct ssh *ssh, Channel *c)
 {
+	struct ssh_channels *sc = ssh->chanctxt;
 	char *s;
 	u_int i, n;
 	Channel *other;
 	struct channel_confirm *cc;
 
-	for (n = 0, i = 0; i < channels_alloc; i++) {
-		if ((other = channels[i]) != NULL) {
-			n++;
-
-			/* detach from mux client and prepare for closing */
-			if (c->type == SSH_CHANNEL_MUX_CLIENT &&
-			    other->type == SSH_CHANNEL_MUX_PROXY &&
-			    other->mux_ctx == c) {
-				other->mux_ctx = NULL;
-				other->type = SSH_CHANNEL_OPEN;
-				other->istate = CHAN_INPUT_CLOSED;
-				other->ostate = CHAN_OUTPUT_CLOSED;
-			}
+	for (n = 0, i = 0; i < sc->channels_alloc; i++) {
+		if ((other = sc->channels[i]) == NULL)
+			continue;
+		n++;
+		/* detach from mux client and prepare for closing */
+		if (c->type == SSH_CHANNEL_MUX_CLIENT &&
+		    other->type == SSH_CHANNEL_MUX_PROXY &&
+		    other->mux_ctx == c) {
+			other->mux_ctx = NULL;
+			other->type = SSH_CHANNEL_OPEN;
+			other->istate = CHAN_INPUT_CLOSED;
+			other->ostate = CHAN_OUTPUT_CLOSED;
 		}
 	}
 	debug("channel %d: free: %s, nchannels %u", c->self,
 	    c->remote_name ? c->remote_name : "???", n);
 
-	/* XXX more MUX cleanup: remove remote forwardings */
-	if (c->type == SSH_CHANNEL_MUX_CLIENT) {
-		for (i = 0; i < (u_int)num_permitted_opens; i++) {
-			if (permitted_opens[i].downstream != c)
-				continue;
-			/* cancel on the server, since mux client is gone */
-			debug("channel %d: cleanup remote forward for %s:%u",
-			    c->self,
-			    permitted_opens[i].listen_host,
-			    permitted_opens[i].listen_port);
-			packet_start(SSH2_MSG_GLOBAL_REQUEST);
-			packet_put_cstring("cancel-tcpip-forward");
-			packet_put_char(0);
-			packet_put_cstring(channel_rfwd_bind_host(
-			    permitted_opens[i].listen_host));
-			packet_put_int(permitted_opens[i].listen_port);
-			packet_send();
-			/* unregister */
-			permitted_opens[i].listen_port = 0;
-			permitted_opens[i].port_to_connect = 0;
-			free(permitted_opens[i].host_to_connect);
-			permitted_opens[i].host_to_connect = NULL;
-			free(permitted_opens[i].listen_host);
-			permitted_opens[i].listen_host = NULL;
-			permitted_opens[i].listen_path = NULL;
-			permitted_opens[i].downstream = NULL;
-		}
-	}
+	if (c->type == SSH_CHANNEL_MUX_CLIENT)
+		mux_remove_remote_forwardings(ssh, c);
 
-	s = channel_open_message();
+	s = channel_open_message(ssh);
 	debug3("channel %d: status: %s", c->self, s);
 	free(s);
 
-	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);
@@ -491,25 +566,26 @@ channel_free(Channel *c)
 	c->listening_addr = NULL;
 	while ((cc = TAILQ_FIRST(&c->status_confirms)) != NULL) {
 		if (cc->abandon_cb != NULL)
-			cc->abandon_cb(c, cc->ctx);
+			cc->abandon_cb(ssh, c, cc->ctx);
 		TAILQ_REMOVE(&c->status_confirms, cc, entry);
 		explicit_bzero(cc, sizeof(*cc));
 		free(cc);
 	}
 	if (c->filter_cleanup != NULL && c->filter_ctx != NULL)
-		c->filter_cleanup(c->self, c->filter_ctx);
-	channels[c->self] = NULL;
+		c->filter_cleanup(ssh, c->self, c->filter_ctx);
+	sc->channels[c->self] = NULL;
+	bzero(c, sizeof(*c));
 	free(c);
 }
 
 void
-channel_free_all(void)
+channel_free_all(struct ssh *ssh)
 {
 	u_int i;
 
-	for (i = 0; i < channels_alloc; i++)
-		if (channels[i] != NULL)
-			channel_free(channels[i]);
+	for (i = 0; i < ssh->chanctxt->channels_alloc; i++)
+		if (ssh->chanctxt->channels[i] != NULL)
+			channel_free(ssh, ssh->chanctxt->channels[i]);
 }
 
 /*
@@ -517,26 +593,26 @@ 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:
@@ -545,8 +621,8 @@ 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;
 			}
 		}
@@ -558,20 +634,20 @@ 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 (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;
@@ -579,13 +655,13 @@ 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) {
@@ -620,13 +696,13 @@ 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];
+	for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+		c = ssh->chanctxt->channels[i];
 		if (c == NULL || c->remote_id < 0)
 			continue;
 		switch (c->type) {
@@ -664,18 +740,21 @@ channel_find_open(void)
  * newlines.
  */
 char *
-channel_open_message(void)
+channel_open_message(struct ssh *ssh)
 {
-	Buffer buffer;
+	struct sshbuf *buf;
 	Channel *c;
-	char buf[1024], *cp;
 	u_int i;
-
-	buffer_init(&buffer);
-	snprintf(buf, sizeof buf, "The following connections are open:\r\n");
-	buffer_append(&buffer, buf, strlen(buf));
-	for (i = 0; i < channels_alloc; i++) {
-		c = channels[i];
+	int r;
+	char *ret;
+
+	if ((buf = sshbuf_new()) == NULL)
+		fatal("%s: sshbuf_new", __func__);
+	if ((r = sshbuf_putf(buf,
+	    "The following connections are open:\r\n")) != 0)
+		fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r));
+	for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+		c = ssh->chanctxt->channels[i];
 		if (c == NULL)
 			continue;
 		switch (c->type) {
@@ -698,69 +777,85 @@ channel_open_message(void)
 		case SSH_CHANNEL_X11_OPEN:
 		case SSH_CHANNEL_MUX_PROXY:
 		case SSH_CHANNEL_MUX_CLIENT:
-			snprintf(buf, sizeof buf,
-			    "  #%d %.300s (t%d r%d i%u/%d o%u/%d fd %d/%d cc %d)\r\n",
+			if ((r = sshbuf_putf(buf, "  #%d %.300s "
+			    "(t%d r%d i%u/%zu o%u/%zu fd %d/%d cc %d)\r\n",
 			    c->self, c->remote_name,
 			    c->type, c->remote_id,
-			    c->istate, buffer_len(&c->input),
-			    c->ostate, buffer_len(&c->output),
-			    c->rfd, c->wfd, c->ctl_chan);
-			buffer_append(&buffer, buf, strlen(buf));
+			    c->istate, sshbuf_len(c->input),
+			    c->ostate, sshbuf_len(c->output),
+			    c->rfd, c->wfd, c->ctl_chan)) != 0)
+				fatal("%s: sshbuf_putf: %s",
+				    __func__, ssh_err(r));
 			continue;
 		default:
-			fatal("channel_open_message: bad channel type %d", c->type);
+			fatal("%s: bad channel type %d", __func__, c->type);
 			/* NOTREACHED */
 		}
 	}
-	buffer_append(&buffer, "\0", 1);
-	cp = xstrdup((char *)buffer_ptr(&buffer));
-	buffer_free(&buffer);
-	return cp;
+	if ((ret = sshbuf_dup_string(buf)) == NULL)
+		fatal("%s: sshbuf_dup_string", __func__);
+	sshbuf_free(buf);
+	return ret;
+}
+
+static void
+open_preamble(struct ssh *ssh, const char *where, Channel *c, const char *type)
+{
+	int r;
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, type)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, c->self)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, c->local_window)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, c->local_maxpacket)) != 0) {
+		fatal("%s: channel %i: open: %s", where, c->self, ssh_err(r));
+	}
 }
 
 void
-channel_send_open(int id)
+channel_send_open(struct ssh *ssh, int id)
 {
-	Channel *c = channel_lookup(id);
+	Channel *c = channel_lookup(ssh, id);
+	int r;
 
 	if (c == NULL) {
 		logit("channel_send_open: %d: bad id", id);
 		return;
 	}
 	debug2("channel %d: send open", id);
-	packet_start(SSH2_MSG_CHANNEL_OPEN);
-	packet_put_cstring(c->ctype);
-	packet_put_int(c->self);
-	packet_put_int(c->local_window);
-	packet_put_int(c->local_maxpacket);
-	packet_send();
+	open_preamble(ssh, __func__, c, c->ctype);
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
 }
 
 void
-channel_request_start(int id, char *service, int wantconfirm)
+channel_request_start(struct ssh *ssh, int id, char *service, int wantconfirm)
 {
-	Channel *c = channel_lookup(id);
+	Channel *c = channel_lookup(ssh, id);
+	int r;
 
 	if (c == NULL) {
-		logit("channel_request_start: %d: unknown channel id", id);
+		logit("%s: %d: unknown channel id", __func__, id);
 		return;
 	}
 	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;
@@ -770,12 +865,13 @@ 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;
@@ -783,12 +879,13 @@ 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;
@@ -796,12 +893,12 @@ 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;
@@ -809,13 +906,13 @@ 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;
@@ -825,79 +922,72 @@ 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);
+	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(Channel *c, fd_set *readset, fd_set *writeset)
+channel_pre_open(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	if (c->istate == CHAN_INPUT_OPEN &&
 	    c->remote_window > 0 &&
-	    buffer_len(&c->input) < c->remote_window &&
-	    buffer_check_alloc(&c->input, CHAN_RBUF))
+	    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 (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? */
@@ -913,24 +1003,26 @@ channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
  * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
  */
 static int
-x11_open_helper(Buffer *b)
+x11_open_helper(struct ssh *ssh, struct sshbuf *b)
 {
+	struct ssh_channels *sc = ssh->chanctxt;
 	u_char *ucp;
 	u_int proto_len, data_len;
 
 	/* Is this being called after the refusal deadline? */
-	if (x11_refuse_time != 0 && (u_int)monotime() >= x11_refuse_time) {
+	if (sc->x11_refuse_time != 0 &&
+	    (u_int)monotime() >= sc->x11_refuse_time) {
 		verbose("Rejected X11 connection after ForwardX11Timeout "
 		    "expired");
 		return -1;
 	}
 
 	/* Check if the fixed size part of the packet is in buffer. */
-	if (buffer_len(b) < 12)
+	if (sshbuf_len(b) < 12)
 		return 0;
 
 	/* Parse the lengths of variable-length fields. */
-	ucp = buffer_ptr(b);
+	ucp = sshbuf_mutable_ptr(b);
 	if (ucp[0] == 0x42) {	/* Byte order MSB first. */
 		proto_len = 256 * ucp[6] + ucp[7];
 		data_len = 256 * ucp[8] + ucp[9];
@@ -944,27 +1036,27 @@ 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;
 	}
 	/*
@@ -973,60 +1065,64 @@ 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(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);
+	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);
-		chan_write_failed(c);
+		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(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
-	char *p, *host;
+	const u_char *p;
+	char *host;
 	u_int len, have, i, found, need;
 	char username[256];
 	struct {
@@ -1035,14 +1131,15 @@ 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(c->input);
 	len = sizeof(s4_req);
 	if (have < len)
 		return 0;
-	p = (char *)buffer_ptr(&c->input);
+	p = sshbuf_ptr(c->input);
 
 	need = 1;
 	/* SOCKS4A uses an invalid IP address 0.0.0.x */
@@ -1067,12 +1164,15 @@ 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 ((r = sshbuf_get(c->input, &s4_req.version, 1)) != 0 ||
+	    (r = sshbuf_get(c->input, &s4_req.command, 1)) != 0 ||
+	    (r = sshbuf_get(c->input, &s4_req.dest_port, 2)) != 0 ||
+	    (r = sshbuf_get(c->input, &s4_req.dest_addr, 4)) != 0) {
+		debug("channels %d: decode socks4: %s", c->self, ssh_err(r));
+		return -1;
+	}
+	have = sshbuf_len(c->input);
+	p = sshbuf_ptr(c->input);
 	if (memchr(p, '\0', have) == NULL) {
 		error("channel %d: decode socks4: user not nul terminated",
 		    c->self);
@@ -1080,21 +1180,20 @@ channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 	}
 	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(c->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(c->input);
+		p = sshbuf_ptr(c->input);
 		if (memchr(p, '\0', have) == NULL) {
 			error("channel %d: decode socks4a: host not nul "
 			    "terminated", c->self);
@@ -1110,7 +1209,10 @@ channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
 			return -1;
 		}
 		c->path = xstrdup(p);
-		buffer_consume(&c->input, len);
+		if ((r = sshbuf_consume(c->input, len)) != 0) {
+			fatal("%s: channel %d: consume: %s", __func__,
+			    c->self, ssh_err(r));
+		}
 	}
 	c->host_port = ntohs(s4_req.dest_port);
 
@@ -1126,7 +1228,10 @@ 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(c->output, &s4_rsp, sizeof(s4_rsp))) != 0) {
+		fatal("%s: channel %d: append reply: %s", __func__,
+		    c->self, ssh_err(r));
+	}
 	return 1;
 }
 
@@ -1139,10 +1244,11 @@ 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(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
+	/* XXX use get/put_u8 instead of trusting struct padding */
 	struct {
 		u_int8_t version;
 		u_int8_t command;
@@ -1151,14 +1257,15 @@ 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(c->input);
 	if (p[0] != 0x05)
 		return -1;
-	have = buffer_len(&c->input);
+	have = sshbuf_len(c->input);
 	if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
 		/* format: ver | nmethods | methods */
 		if (have < 2)
@@ -1178,9 +1285,16 @@ 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 */
+		if ((r = sshbuf_consume(c->input, nmethods + 2)) != 0) {
+			fatal("%s: channel %d: consume: %s", __func__,
+			    c->self, ssh_err(r));
+		}
+		/* version, method */
+		if ((r = sshbuf_put_u8(c->output, 0x05)) != 0 ||
+		    (r = sshbuf_put_u8(c->output, SSH_SOCKS5_NOAUTH)) != 0) {
+			fatal("%s: channel %d: append reply: %s", __func__,
+			    c->self, ssh_err(r));
+		}
 		FD_SET(c->sock, writeset);
 		c->flags |= SSH_SOCKS5_AUTHDONE;
 		debug2("channel %d: socks5 auth done", c->self);
@@ -1218,11 +1332,22 @@ 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(c->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(c->input, 1)) != 0) {
+			fatal("%s: channel %d: consume: %s", __func__,
+			    c->self, ssh_err(r));
+		}
+	}
+	if ((r = sshbuf_get(c->input, &dest_addr, addrlen)) != 0 ||
+	    (r = sshbuf_get(c->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;
@@ -1249,22 +1374,23 @@ 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(c->output, &s5_rsp, sizeof(s5_rsp))) != 0 ||
+	    (r = sshbuf_put_u32(c->output, ntohl(INADDR_ANY))) != 0 ||
+	    (r = sshbuf_put(c->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);
 
@@ -1273,23 +1399,24 @@ 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 */
@@ -1297,20 +1424,21 @@ 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(ssh, c, readset, writeset);
 		break;
 	case 0x05:
-		ret = channel_decode_socks5(c, readset, writeset);
+		ret = channel_decode_socks5(ssh, c, readset, writeset);
 		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 */
@@ -1318,75 +1446,75 @@ channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *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");
 	}
 }
 
 /* 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);
-		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();
-		free(remote_ipaddr);
+
+	if (!FD_ISSET(c->sock, readset))
+		return;
+
+	debug("X11 connection requested.");
+	addrlen = sizeof(addr);
+	newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
+	if (c->single_connection) {
+		oerrno = errno;
+		debug2("single_connection: closing X11 listener.");
+		channel_close_fd(ssh, &c->sock);
+		chan_mark_dead(ssh, c);
+		errno = oerrno;
+	}
+	if (newsock < 0) {
+		if (errno != EINTR && errno != EWOULDBLOCK &&
+		    errno != ECONNABORTED)
+			error("accept: %.100s", strerror(errno));
+		if (errno == EMFILE || errno == ENFILE)
+			c->notbefore = monotime() + 1;
+		return;
 	}
+	set_nodelay(newsock);
+	remote_ipaddr = get_peer_ipaddr(newsock);
+	remote_port = get_peer_port(newsock);
+	snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
+	    remote_ipaddr, remote_port);
+
+	nc = channel_new(ssh, "accepted x11 socket",
+	    SSH_CHANNEL_OPENING, newsock, newsock, -1,
+	    c->local_window_max, c->local_maxpacket, 0, buf, 1);
+	open_preamble(ssh, __func__, nc, "x11");
+	if ((r = sshpkt_put_cstring(ssh, remote_ipaddr)) != 0) {
+		fatal("%s: channel %i: reply %s", __func__,
+		    c->self, ssh_err(r));
+	}
+	if ((datafellows & SSH_BUG_X11FWD) != 0)
+		debug2("channel %d: ssh2 x11 bug compat mode", nc->self);
+	else if ((r = sshpkt_put_u32(ssh, remote_port)) != 0) {
+		fatal("%s: channel %i: reply %s", __func__,
+		    c->self, ssh_err(r));
+	}
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal("%s: channel %i: send %s", __func__, c->self, ssh_err(r));
+	free(remote_ipaddr);
 }
 
 static void
-port_open_helper(Channel *c, char *rtype)
+port_open_helper(struct ssh *ssh, Channel *c, char *rtype)
 {
-	char buf[1024];
 	char *local_ipaddr = get_local_ipaddr(c->sock);
 	int local_port = c->sock == -1 ? 65536 : get_local_port(c->sock);
 	char *remote_ipaddr = get_peer_ipaddr(c->sock);
 	int remote_port = get_peer_port(c->sock);
+	int r;
 
 	if (remote_port == -1) {
 		/* Fake addr/port to appease peers that validate it (Tectia) */
@@ -1395,44 +1523,57 @@ port_open_helper(Channel *c, char *rtype)
 		remote_port = 65535;
 	}
 
-	snprintf(buf, sizeof buf,
+	free(c->remote_name);
+	xasprintf(&c->remote_name,
 	    "%s: listening port %d for %.100s port %d, "
 	    "connect from %.200s port %d to %.100s port %d",
 	    rtype, c->listening_port, c->path, c->host_port,
 	    remote_ipaddr, remote_port, local_ipaddr, local_port);
 
-	free(c->remote_name);
-	c->remote_name = xstrdup(buf);
-
-	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);
+	open_preamble(ssh, __func__, c, rtype);
 	if (strcmp(rtype, "direct-tcpip") == 0) {
 		/* target host, port */
-		packet_put_cstring(c->path);
-		packet_put_int(c->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));
+		}
 	} else if (strcmp(rtype, "direct-streamlocal@openssh.com") == 0) {
 		/* target path */
-		packet_put_cstring(c->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 */
-		packet_put_cstring(c->path);
+		if ((r = sshpkt_put_cstring(ssh, c->path)) != 0) {
+			fatal("%s: channel %i: reply %s", __func__,
+			    c->self, ssh_err(r));
+		}
 	} else {
 		/* listen address, port */
-		packet_put_cstring(c->path);
-		packet_put_int(local_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 */
-		packet_put_cstring("");
+		if ((r = sshpkt_put_cstring(ssh, "")) != 0) {
+			fatal("%s: channel %i: reply %s", __func__,
+			    c->self, ssh_err(r));
+		}
 	} else {
 		/* originator host and port */
-		packet_put_cstring(remote_ipaddr);
-		packet_put_int((u_int)remote_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));
+		}
 	}
-	packet_send();
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal("%s: channel %i: send %s", __func__, c->self, ssh_err(r));
 	free(remote_ipaddr);
 	free(local_ipaddr);
 }
@@ -1451,17 +1592,17 @@ channel_set_reuseaddr(int fd)
 }
 
 void
-channel_set_x11_refuse_time(u_int refuse_time)
+channel_set_x11_refuse_time(struct ssh *ssh, u_int refuse_time)
 {
-	x11_refuse_time = refuse_time;
+	ssh->chanctxt->x11_refuse_time = refuse_time;
 }
 
 /*
  * This socket is listening for connections to a forwarded TCP/IP port.
  */
-/* ARGSUSED */
 static void
-channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_port_listener(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	Channel *nc;
 	struct sockaddr_storage addr;
@@ -1469,336 +1610,387 @@ channel_post_port_listener(Channel *c, fd_set *readset, fd_set *writeset)
 	socklen_t addrlen;
 	char *rtype;
 
-	if (FD_ISSET(c->sock, readset)) {
-		debug("Connection to port %d forwarding "
-		    "to %.100s port %d requested.",
-		    c->listening_port, c->path, c->host_port);
-
-		if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
-			nextstate = SSH_CHANNEL_OPENING;
-			rtype = "forwarded-tcpip";
-		} else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) {
-			nextstate = SSH_CHANNEL_OPENING;
-			rtype = "forwarded-streamlocal@openssh.com";
-		} else if (c->host_port == PORT_STREAMLOCAL) {
-			nextstate = SSH_CHANNEL_OPENING;
-			rtype = "direct-streamlocal@openssh.com";
-		} else if (c->host_port == 0) {
-			nextstate = SSH_CHANNEL_DYNAMIC;
-			rtype = "dynamic-tcpip";
-		} else {
-			nextstate = SSH_CHANNEL_OPENING;
-			rtype = "direct-tcpip";
-		}
+	if (!FD_ISSET(c->sock, readset))
+		return;
 
-		addrlen = sizeof(addr);
-		newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
-		if (newsock < 0) {
-			if (errno != EINTR && errno != EWOULDBLOCK &&
-			    errno != ECONNABORTED)
-				error("accept: %.100s", strerror(errno));
-			if (errno == EMFILE || errno == ENFILE)
-				c->notbefore = monotime() + 1;
-			return;
-		}
-		if (c->host_port != PORT_STREAMLOCAL)
-			set_nodelay(newsock);
-		nc = channel_new(rtype, nextstate, newsock, newsock, -1,
-		    c->local_window_max, c->local_maxpacket, 0, rtype, 1);
-		nc->listening_port = c->listening_port;
-		nc->host_port = c->host_port;
-		if (c->path != NULL)
-			nc->path = xstrdup(c->path);
-
-		if (nextstate != SSH_CHANNEL_DYNAMIC)
-			port_open_helper(nc, rtype);
+	debug("Connection to port %d forwarding to %.100s port %d requested.",
+	    c->listening_port, c->path, c->host_port);
+
+	if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
+		nextstate = SSH_CHANNEL_OPENING;
+		rtype = "forwarded-tcpip";
+	} else if (c->type == SSH_CHANNEL_RUNIX_LISTENER) {
+		nextstate = SSH_CHANNEL_OPENING;
+		rtype = "forwarded-streamlocal@openssh.com";
+	} else if (c->host_port == PORT_STREAMLOCAL) {
+		nextstate = SSH_CHANNEL_OPENING;
+		rtype = "direct-streamlocal@openssh.com";
+	} else if (c->host_port == 0) {
+		nextstate = SSH_CHANNEL_DYNAMIC;
+		rtype = "dynamic-tcpip";
+	} else {
+		nextstate = SSH_CHANNEL_OPENING;
+		rtype = "direct-tcpip";
+	}
+
+	addrlen = sizeof(addr);
+	newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
+	if (newsock < 0) {
+		if (errno != EINTR && errno != EWOULDBLOCK &&
+		    errno != ECONNABORTED)
+			error("accept: %.100s", strerror(errno));
+		if (errno == EMFILE || errno == ENFILE)
+			c->notbefore = monotime() + 1;
+		return;
 	}
+	if (c->host_port != PORT_STREAMLOCAL)
+		set_nodelay(newsock);
+	nc = channel_new(ssh, rtype, nextstate, newsock, newsock, -1,
+	    c->local_window_max, c->local_maxpacket, 0, rtype, 1);
+	nc->listening_port = c->listening_port;
+	nc->host_port = c->host_port;
+	if (c->path != NULL)
+		nc->path = xstrdup(c->path);
+
+	if (nextstate != SSH_CHANNEL_DYNAMIC)
+		port_open_helper(ssh, nc, rtype);
 }
 
 /*
  * This is the authentication agent socket listening for connections from
  * clients.
  */
-/* ARGSUSED */
 static void
-channel_post_auth_listener(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_auth_listener(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	Channel *nc;
-	int newsock;
+	int r, newsock;
 	struct sockaddr_storage addr;
 	socklen_t addrlen;
 
-	if (FD_ISSET(c->sock, readset)) {
-		addrlen = sizeof(addr);
-		newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
-		if (newsock < 0) {
-			error("accept from auth socket: %.100s",
-			    strerror(errno));
-			if (errno == EMFILE || errno == ENFILE)
-				c->notbefore = monotime() + 1;
-			return;
-		}
-		nc = channel_new("accepted auth socket",
-		    SSH_CHANNEL_OPENING, newsock, newsock, -1,
-		    c->local_window_max, c->local_maxpacket,
-		    0, "accepted auth socket", 1);
-		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);
-		packet_send();
+	if (!FD_ISSET(c->sock, readset))
+		return;
+
+	addrlen = sizeof(addr);
+	newsock = accept(c->sock, (struct sockaddr *)&addr, &addrlen);
+	if (newsock < 0) {
+		error("accept from auth socket: %.100s", strerror(errno));
+		if (errno == EMFILE || errno == ENFILE)
+			c->notbefore = monotime() + 1;
+		return;
 	}
+	nc = channel_new(ssh, "accepted auth socket",
+	    SSH_CHANNEL_OPENING, newsock, newsock, -1,
+	    c->local_window_max, c->local_maxpacket,
+	    0, "accepted auth socket", 1);
+	open_preamble(ssh, __func__, nc, "auth-agent@openssh.com");
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
 }
 
-/* ARGSUSED */
 static void
-channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_connecting(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
-	int err = 0, sock;
+	int err = 0, sock, 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 (getsockopt(c->sock, SOL_SOCKET, SO_ERROR, &err, &sz) < 0) {
+		err = errno;
+		error("getsockopt SO_ERROR failed");
+	}
+	if (err == 0) {
+		debug("channel %d: connected to %s port %d",
+		    c->self, c->connect_ctx.host, c->connect_ctx.port);
+		channel_connect_ctx_free(&c->connect_ctx);
+		c->type = SSH_CHANNEL_OPEN;
+		if ((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 (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;
-			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 {
-			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);
-			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("");
-			}
-			chan_mark_dead(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_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 ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_OPEN_FAILURE)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, SSH2_OPEN_CONNECT_FAILED)) != 0) {
+			fatal("%s: channel %i: failure: %s", __func__,
+			    c->self, ssh_err(r));
+		}
+		if ((datafellows & SSH_BUG_OPENFAILURE) == 0 &&
+		    ((r = sshpkt_put_cstring(ssh, strerror(err))) != 0 ||
+		    (r = sshpkt_put_cstring(ssh, "")) != 0)) {
+			fatal("%s: channel %i: failure: %s", __func__,
+			    c->self, ssh_err(r));
 		}
-		packet_send();
+		chan_mark_dead(ssh, c);
 	}
+	if ((r = sshpkt_send(ssh)) != 0)
+		fatal("%s: channel %i: %s", __func__, c->self, ssh_err(r));
 }
 
-/* ARGSUSED */
 static int
-channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
+channel_handle_rfd(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	char buf[CHAN_RBUF];
-	int len, force;
+	ssize_t len;
+	int r, force;
 
 	force = c->isatty && c->detach_close && c->istate != CHAN_INPUT_CLOSED;
-	if (c->rfd != -1 && (force || FD_ISSET(c->rfd, readset))) {
-		errno = 0;
-		len = read(c->rfd, buf, sizeof(buf));
-		if (len < 0 && (errno == EINTR ||
-		    ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
-			return 1;
+
+	if (c->rfd == -1 || (!force && !FD_ISSET(c->rfd, readset)))
+		return 1;
+
+	errno = 0;
+	len = read(c->rfd, buf, sizeof(buf));
+	if (len < 0 && (errno == EINTR ||
+	    ((errno == EAGAIN || errno == EWOULDBLOCK) && !force)))
+		return 1;
 #ifndef PTY_ZEROREAD
-		if (len <= 0) {
+ 	if (len <= 0) {
 #else
-		if ((!c->isatty && len <= 0) ||
-		    (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
+	if ((!c->isatty && len <= 0) ||
+	    (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
 #endif
-			debug2("channel %d: read<=0 rfd %d len %d",
-			    c->self, c->rfd, len);
-			if (c->type != SSH_CHANNEL_OPEN) {
-				debug2("channel %d: not open", c->self);
-				chan_mark_dead(c);
-				return -1;
-			} else {
-				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));
+	} 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, data, dlen);
+		free(data);
+		if (len < 0 && (errno == EINTR || errno == EAGAIN ||
+		    errno == EWOULDBLOCK))
+			return 1;
+		if (len <= 0)
+			goto write_fail;
+		goto out;
+	}
 
-		if (c->datagram) {
-			/* ignore truncated writes, datagrams might get lost */
-			len = write(c->wfd, buf, dlen);
-			free(data);
-			if (len < 0 && (errno == EINTR || errno == EAGAIN ||
-			    errno == EWOULDBLOCK))
-				return 1;
-			if (len <= 0) {
-				if (c->type != SSH_CHANNEL_OPEN)
-					chan_mark_dead(c);
-				else
-					chan_write_failed(c);
-				return -1;
-			}
-			goto out;
-		}
 #ifdef _AIX
-		/* XXX: Later AIX versions can't push as much data to tty */
-		if (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 {
-				chan_write_failed(c);
-			}
+	len = write(c->wfd, buf, dlen);
+	if (len < 0 &&
+	    (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK))
+		return 1;
+	if (len <= 0) {
+ write_fail:
+		if (c->type != SSH_CHANNEL_OPEN) {
+			debug2("channel %d: not open", c->self);
+			chan_mark_dead(ssh, c);
 			return -1;
+		} else {
+			chan_write_failed(ssh, c);
 		}
+		return -1;
+	}
 #ifndef BROKEN_TCGETATTR_ICANON
-		if (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 (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 < 0 && (errno == EINTR || errno == EAGAIN ||
+	    errno == EWOULDBLOCK))
+		return 1;
+	if (len <= 0) {
+		debug2("channel %d: closing write-efd %d", c->self, c->efd);
+		channel_close_fd(ssh, &c->efd);
+	} else {
+		if ((r = sshbuf_consume(c->extended, len)) != 0) {
+			fatal("%s: channel %d: consume: %s",
+			    __func__, c->self, ssh_err(r));
+		}
+		c->local_consumed += len;
+	}
 	return 1;
 }
 
 static int
-channel_handle_efd(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;
+	int r;
+	ssize_t len;
 
-/** XXX handle drain efd, too */
-	if (c->efd != -1) {
-		if (c->extended_usage == CHAN_EXTENDED_WRITE &&
-		    FD_ISSET(c->efd, writeset) &&
-		    buffer_len(&c->extended) > 0) {
-			len = write(c->efd, buffer_ptr(&c->extended),
-			    buffer_len(&c->extended));
-			debug2("channel %d: written %d to efd %d",
-			    c->self, len, c->efd);
-			if (len < 0 && (errno == EINTR || errno == EAGAIN ||
-			    errno == EWOULDBLOCK))
-				return 1;
-			if (len <= 0) {
-				debug2("channel %d: closing write-efd %d",
-				    c->self, c->efd);
-				channel_close_fd(&c->efd);
-			} else {
-				buffer_consume(&c->extended, len);
-				c->local_consumed += len;
-			}
-		} else if (c->efd != -1 &&
-		    (c->extended_usage == CHAN_EXTENDED_READ ||
-		    c->extended_usage == CHAN_EXTENDED_IGNORE) &&
-		    (c->detach_close || FD_ISSET(c->efd, readset))) {
-			len = read(c->efd, buf, sizeof(buf));
-			debug2("channel %d: read %d from efd %d",
-			    c->self, len, c->efd);
-			if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
-			    errno == EWOULDBLOCK) && !c->detach_close)))
-				return 1;
-			if (len <= 0) {
-				debug2("channel %d: closing read-efd %d",
-				    c->self, c->efd);
-				channel_close_fd(&c->efd);
-			} else {
-				if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
-					debug3("channel %d: discard efd",
-					    c->self);
-				} else
-					buffer_append(&c->extended, buf, len);
-			}
+	if (!c->detach_close && !FD_ISSET(c->efd, readset))
+		return 1;
+
+	len = read(c->efd, buf, sizeof(buf));
+	debug2("channel %d: read %zd from efd %d", c->self, len, c->efd);
+	if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
+	    errno == EWOULDBLOCK) && !c->detach_close)))
+		return 1;
+	if (len <= 0) {
+		debug2("channel %d: closing read-efd %d",
+		    c->self, c->efd);
+		channel_close_fd(ssh, &c->efd);
+	} else {
+		if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
+			debug3("channel %d: discard efd",
+			    c->self);
+		} else if ((r = sshbuf_put(c->extended, buf, len)) != 0) {
+			fatal("%s: channel %d: append: %s",
+			    __func__, c->self, ssh_err(r));
 		}
 	}
 	return 1;
 }
 
 static int
-channel_check_window(Channel *c)
+channel_handle_efd(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
+{
+	if (c->efd == -1)
+		return 1;
+
+	/** XXX handle drain efd, too */
+
+	if (c->extended_usage == CHAN_EXTENDED_WRITE)
+		return channel_handle_efd_write(ssh, c, readset, writeset);
+	else if (c->extended_usage == CHAN_EXTENDED_READ ||
+	    c->extended_usage == CHAN_EXTENDED_IGNORE)
+		return channel_handle_efd_read(ssh, c, readset, writeset);
+
+	return 1;
+}
+
+static int
+channel_check_window(struct ssh *ssh, Channel *c)
 {
+	int r;
+
 	if (c->type == SSH_CHANNEL_OPEN &&
 	    !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
 	    ((c->local_window_max - c->local_window >
 	    c->local_maxpacket*3) ||
 	    c->local_window < c->local_window_max/2) &&
 	    c->local_consumed > 0) {
-		packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-		packet_put_int(c->remote_id);
-		packet_put_int(c->local_consumed);
-		packet_send();
+		if ((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);
@@ -1809,85 +2001,112 @@ 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);
-	channel_handle_efd(c, readset, writeset);
-	channel_check_window(c);
+	channel_handle_rfd(ssh, c, readset, writeset);
+	channel_handle_wfd(ssh, c, readset, writeset);
+	channel_handle_efd(ssh, c, readset, writeset);
+	channel_check_window(ssh, c);
 }
 
 static u_int
-read_mux(Channel *c, u_int need)
+read_mux(struct ssh *ssh, Channel *c, u_int need)
 {
 	char buf[CHAN_RBUF];
-	int len;
+	ssize_t len;
 	u_int rlen;
+	int r;
 
-	if (buffer_len(&c->input) < need) {
-		rlen = need - buffer_len(&c->input);
+	if (sshbuf_len(c->input) < need) {
+		rlen = need - sshbuf_len(c->input);
 		len = read(c->rfd, buf, MINIMUM(rlen, CHAN_RBUF));
 		if (len < 0 && (errno == EINTR || errno == EAGAIN))
-			return buffer_len(&c->input);
+			return sshbuf_len(c->input);
 		if (len <= 0) {
-			debug2("channel %d: ctl read<=0 rfd %d len %d",
+			debug2("channel %d: ctl read<=0 rfd %d len %zd",
 			    c->self, c->rfd, len);
-			chan_read_failed(c);
+			chan_read_failed(ssh, c);
 			return 0;
-		} else
-			buffer_append(&c->input, buf, len);
+		} else if ((r = sshbuf_put(c->input, buf, len)) != 0) {
+			fatal("%s: channel %d: append: %s",
+			    __func__, c->self, ssh_err(r));
+		}
 	}
-	return buffer_len(&c->input);
+	return sshbuf_len(c->input);
 }
 
 static void
-channel_post_mux_client(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_mux_client_read(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	u_int need;
-	ssize_t len;
 
-	if (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));
+	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;
+
+	/*
+	 * Don't not read past the precise end of packets to
+	 * avoid disrupting fd passing.
+	 */
+	if (read_mux(ssh, c, 4) < 4) /* read header */
+		return;
+	/* XXX sshbuf_peek_u32 */
+	need = PEEK_U32(sshbuf_ptr(c->input));
 #define CHANNEL_MUX_MAX_PACKET	(256 * 1024)
-		if (need > CHANNEL_MUX_MAX_PACKET) {
-			debug2("channel %d: packet too big %u > %u",
-			    c->self, CHANNEL_MUX_MAX_PACKET, need);
-			chan_rcvd_oclose(c);
-			return;
-		}
-		if (read_mux(c, need + 4) < need + 4) /* read body */
-			return;
-		if (c->mux_rcb(c) != 0) {
-			debug("channel %d: mux_rcb failed", c->self);
-			chan_mark_dead(c);
-			return;
-		}
+	if (need > CHANNEL_MUX_MAX_PACKET) {
+		debug2("channel %d: packet too big %u > %u",
+		    c->self, CHANNEL_MUX_MAX_PACKET, need);
+		chan_rcvd_oclose(ssh, c);
+		return;
 	}
+	if (read_mux(ssh, c, need + 4) < need + 4) /* read body */
+		return;
+	if (c->mux_rcb(ssh, c) != 0) {
+		debug("channel %d: mux_rcb failed", c->self);
+		chan_mark_dead(ssh, c);
+		return;
+	}
+}
 
-	if (c->wfd != -1 && FD_ISSET(c->wfd, writeset) &&
-	    buffer_len(&c->output) > 0) {
-		len = write(c->wfd, buffer_ptr(&c->output),
-		    buffer_len(&c->output));
-		if (len < 0 && (errno == EINTR || errno == EAGAIN))
-			return;
-		if (len <= 0) {
-			chan_mark_dead(c);
-			return;
-		}
-		buffer_consume(&c->output, len);
+static void
+channel_post_mux_client_write(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
+{
+	ssize_t len;
+	int r;
+
+	if (c->wfd == -1 || !FD_ISSET(c->wfd, writeset) ||
+	    sshbuf_len(c->output) == 0)
+		return;
+
+	len = write(c->wfd, sshbuf_ptr(c->output), sshbuf_len(c->output));
+	if (len < 0 && (errno == EINTR || errno == EAGAIN))
+		return;
+	if (len <= 0) {
+		chan_mark_dead(ssh, c);
+		return;
 	}
+	if ((r = sshbuf_consume(c->output, len)) != 0)
+		fatal("%s: channel %d: consume: %s", __func__,
+		    c->self, ssh_err(r));
+}
+
+static void
+channel_post_mux_client(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
+{
+	channel_post_mux_client_read(ssh, c, readset, writeset);
+	channel_post_mux_client_write(ssh, c, readset, writeset);
 }
 
 static void
-channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
+channel_post_mux_listener(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	Channel *nc;
 	struct sockaddr_storage addr;
@@ -1926,97 +2145,98 @@ 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;
 }
 
 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;
-	}
-	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;
+	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_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_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(struct ssh *ssh, chan_fn *ftab[],
+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;
@@ -2026,7 +2246,7 @@ channel_handler(struct ssh *ssh, chan_fn *ftab[],
 			 * 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
@@ -2040,7 +2260,7 @@ channel_handler(struct ssh *ssh, chan_fn *ftab[],
 					*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",
@@ -2057,7 +2277,7 @@ channel_prepare_select(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp,
 {
 	u_int n, sz, nfdset;
 
-	n = MAXIMUM(*maxfdp, 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 */
@@ -2076,7 +2296,7 @@ channel_prepare_select(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp,
 	memset(*writesetp, 0, sz);
 
 	if (!ssh_packet_is_rekeying(ssh))
-		channel_handler(ssh, channel_pre, *readsetp, *writesetp,
+		channel_handler(ssh, CHAN_PRE, *readsetp, *writesetp,
 		    minwait_secs);
 }
 
@@ -2087,19 +2307,128 @@ channel_prepare_select(struct ssh *ssh, fd_set **readsetp, fd_set **writesetp,
 void
 channel_after_select(struct ssh *ssh, fd_set *readset, fd_set *writeset)
 {
-	channel_handler(ssh, channel_post, readset, writeset, NULL);
+	channel_handler(ssh, CHAN_POST, readset, writeset, NULL);
+}
+
+/*
+ * Enqueue data for channels with open or draining c->input.
+ */
+static void
+channel_output_poll_input_open(struct ssh *ssh, Channel *c)
+{
+	size_t len, dlen;
+	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->datagram) {
+		/* Check datagram will fit; drop if not */
+		if ((r = sshbuf_peek_string_direct(c->input, NULL, &dlen)) != 0)
+			fatal("%s: channel %d: peek 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 (dlen > c->remote_window || dlen > 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_stringb(ssh, c->input)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0) {
+			fatal("%s: channel %i: datagram: %s", __func__,
+			    c->self, ssh_err(r));
+		}
+		c->remote_window -= dlen;
+		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 ((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;
 
@@ -2111,87 +2440,19 @@ channel_output_poll(void)
 			continue;
 		if ((c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
 			/* XXX is this true? */
-			debug3("channel %d: will not send data after close", c->self);
+			debug3("channel %d: will not send data after close",
+			    c->self);
 			continue;
 		}
 
 		/* Get the amount of buffered data for this channel. */
-		if ((c->istate == CHAN_INPUT_OPEN ||
-		    c->istate == CHAN_INPUT_WAIT_DRAIN) &&
-		    (len = buffer_len(&c->input)) > 0) {
-			if (c->datagram) {
-				if (len > 0) {
-					u_char *data;
-					u_int dlen;
-
-					data = buffer_get_string(&c->input,
-					    &dlen);
-					if (dlen > c->remote_window ||
-					    dlen > c->remote_maxpacket) {
-						debug("channel %d: datagram "
-						    "too big for channel",
-						    c->self);
-						free(data);
-						continue;
-					}
-					packet_start(SSH2_MSG_CHANNEL_DATA);
-					packet_put_int(c->remote_id);
-					packet_put_string(data, dlen);
-					packet_send();
-					c->remote_window -= dlen;
-					free(data);
-				}
-				continue;
-			}
-			/*
-			 * Send some data for the other side over the secure
-			 * connection.
-			 */
-			if (len > c->remote_window)
-				len = c->remote_window;
-			if (len > c->remote_maxpacket)
-				len = c->remote_maxpacket;
-			if (len > 0) {
-				packet_start(SSH2_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) {
-			/*
-			 * input-buffer is empty and read-socket shutdown:
-			 * tell peer, that we will not send more data: send IEOF.
-			 * hack for extended data: delay EOF if EFD still in use.
-			 */
-			if (CHANNEL_EFD_INPUT_ACTIVE(c))
-				debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
-				    c->self, c->efd, buffer_len(&c->extended));
-			else
-				chan_ibuf_empty(c);
-		}
+		if (c->istate == CHAN_INPUT_OPEN ||
+		    c->istate == CHAN_INPUT_WAIT_DRAIN)
+			channel_output_poll_input_open(ssh, c);
 		/* Send extended data, i.e. stderr */
 		if (!(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);
-		}
+		    c->extended_usage == CHAN_EXTENDED_READ)
+			channel_output_poll_extended_read(ssh, c);
 	}
 }
 
@@ -2236,10 +2497,9 @@ channel_output_poll(void)
  * on channel creation.
  */
 int
-channel_proxy_downstream(Channel *downstream)
+channel_proxy_downstream(struct ssh *ssh, Channel *downstream)
 {
 	Channel *c = NULL;
-	struct ssh *ssh = active_state;
 	struct sshbuf *original = NULL, *modified = NULL;
 	const u_char *cp;
 	char *ctype = NULL, *listen_host = NULL;
@@ -2248,8 +2508,8 @@ channel_proxy_downstream(Channel *downstream)
 	int ret = -1, r, idx;
 	u_int id, remote_id, listen_port;
 
-	/* sshbuf_dump(&downstream->input, stderr); */
-	if ((r = sshbuf_get_string_direct(&downstream->input, &cp, &have))
+	/* sshbuf_dump(downstream->input, stderr); */
+	if ((r = sshbuf_get_string_direct(downstream->input, &cp, &have))
 	    != 0) {
 		error("%s: malformed message: %s", __func__, ssh_err(r));
 		return -1;
@@ -2278,7 +2538,7 @@ channel_proxy_downstream(Channel *downstream)
 			error("%s: parse error %s", __func__, ssh_err(r));
 			goto out;
 		}
-		c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
+		c = channel_new(ssh, "mux proxy", SSH_CHANNEL_MUX_PROXY,
 		   -1, -1, -1, 0, 0, 0, ctype, 1);
 		c->mux_ctx = downstream;	/* point to mux client */
 		c->mux_downstream_id = id;	/* original downstream id */
@@ -2286,7 +2546,7 @@ channel_proxy_downstream(Channel *downstream)
 		    (r = sshbuf_put_u32(modified, c->self)) != 0 ||
 		    (r = sshbuf_putb(modified, original)) != 0) {
 			error("%s: compose error %s", __func__, ssh_err(r));
-			channel_free(c);
+			channel_free(ssh, c);
 			goto out;
 		}
 		break;
@@ -2305,7 +2565,7 @@ channel_proxy_downstream(Channel *downstream)
 			error("%s: parse error %s", __func__, ssh_err(r));
 			goto out;
 		}
-		c = channel_new("mux proxy", SSH_CHANNEL_MUX_PROXY,
+		c = channel_new(ssh, "mux proxy", SSH_CHANNEL_MUX_PROXY,
 		   -1, -1, -1, 0, 0, 0, "mux-down-connect", 1);
 		c->mux_ctx = downstream;	/* point to mux client */
 		c->mux_downstream_id = id;
@@ -2314,7 +2574,7 @@ channel_proxy_downstream(Channel *downstream)
 		    (r = sshbuf_put_u32(modified, c->self)) != 0 ||
 		    (r = sshbuf_putb(modified, original)) != 0) {
 			error("%s: compose error %s", __func__, ssh_err(r));
-			channel_free(c);
+			channel_free(ssh, c);
 			goto out;
 		}
 		break;
@@ -2343,23 +2603,17 @@ channel_proxy_downstream(Channel *downstream)
 			goto out;
 		}
 		/* Record that connection to this host/port is permitted. */
-		permitted_opens = xreallocarray(permitted_opens,
-		    num_permitted_opens + 1, sizeof(*permitted_opens));
-		idx = num_permitted_opens++;
-		permitted_opens[idx].host_to_connect = xstrdup("<mux>");
-		permitted_opens[idx].port_to_connect = -1;
-		permitted_opens[idx].listen_host = listen_host;
-		permitted_opens[idx].listen_port = (int)listen_port;
-		permitted_opens[idx].downstream = downstream;
+		idx = fwd_perm_list_add(ssh, FWDPERM_USER, "<mux>", -1,
+		    listen_host, NULL, (int)listen_port, downstream);
 		listen_host = NULL;
 		break;
 	case SSH2_MSG_CHANNEL_CLOSE:
 		if (have < 4)
 			break;
 		remote_id = PEEK_U32(cp);
-		if ((c = channel_by_remote_id(remote_id)) != NULL) {
+		if ((c = channel_by_remote_id(ssh, remote_id)) != NULL) {
 			if (c->flags & CHAN_CLOSE_RCVD)
-				channel_free(c);
+				channel_free(ssh, c);
 			else
 				c->flags |= CHAN_CLOSE_SENT;
 		}
@@ -2446,7 +2700,7 @@ channel_proxy_upstream(Channel *c, int type, u_int32_t seq, struct ssh *ssh)
 	    (r = sshbuf_put_u8(b, type)) != 0 ||
 	    (r = sshbuf_put_u32(b, c->mux_downstream_id)) != 0 ||
 	    (r = sshbuf_put(b, cp, len)) != 0 ||
-	    (r = sshbuf_put_stringb(&downstream->output, b)) != 0) {
+	    (r = sshbuf_put_stringb(downstream->output, b)) != 0) {
 		error("%s: compose for muxclient %s", __func__, ssh_err(r));
 		goto out;
 	}
@@ -2464,7 +2718,7 @@ channel_proxy_upstream(Channel *c, int type, u_int32_t seq, struct ssh *ssh)
 		break;
 	case SSH2_MSG_CHANNEL_CLOSE:
 		if (c->flags & CHAN_CLOSE_SENT)
-			channel_free(c);
+			channel_free(ssh, c);
 		else
 			c->flags |= CHAN_CLOSE_RCVD;
 		break;
@@ -2475,20 +2729,46 @@ channel_proxy_upstream(Channel *c, int type, u_int32_t seq, struct ssh *ssh)
 
 /* -- 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, 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;
 
@@ -2498,17 +2778,19 @@ channel_input_data(int type, u_int32_t seq, struct ssh *ssh)
 		return 0;
 
 	/* Get the data. */
-	data = packet_get_string_ptr(&data_len);
+	if ((r = sshpkt_get_string_direct(ssh, &data, &data_len)) != 0)
+		fatal("%s: channel %d: get data: %s", __func__,
+		    c->self, ssh_err(r));
+	ssh_packet_check_eom(ssh);
+
 	win_len = data_len;
 	if (c->datagram)
 		win_len += 4;  /* string length header */
 
 	/*
-	 * Ignore data for protocol > 1.3 if output end is no longer open.
-	 * For protocol 2 the sending side is reducing its window as it sends
-	 * data, so we must 'fake' consumption of the data in order to ensure
-	 * that window updates are sent back.  Otherwise the connection might
-	 * deadlock.
+	 * The sending side reduces its window as it sends data, so we
+	 * must 'fake' consumption of the data in order to ensure that window
+	 * updates are sent back. Otherwise the connection might deadlock.
 	 */
 	if (c->ostate != CHAN_OUTPUT_OPEN) {
 		c->local_window -= win_len;
@@ -2517,149 +2799,148 @@ channel_input_data(int type, u_int32_t seq, struct ssh *ssh)
 	}
 
 	if (win_len > c->local_maxpacket) {
-		logit("channel %d: rcvd big packet %d, maxpack %d",
+		logit("channel %d: rcvd big packet %zu, maxpack %u",
 		    c->self, win_len, c->local_maxpacket);
+		return 0;
 	}
 	if (win_len > c->local_window) {
-		logit("channel %d: rcvd too much data %d, win %d",
+		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)
-		buffer_put_string(&c->output, data, data_len);
-	else
-		buffer_append(&c->output, data, data_len);
-	packet_check_eom();
+	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, 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) {
+		error("%s: parse data: %s", __func__, ssh_err(r));
+		ssh_packet_disconnect(ssh, "Invalid extended_data message");
+	}
+	ssh_packet_check_eom(ssh);
+
 	if (data_len > c->local_window) {
-		logit("channel %d: rcvd too much extended_data %d, win %d",
+		logit("channel %d: rcvd too much extended_data %zu, win %u",
 		    c->self, data_len, c->local_window);
-		free(data);
 		return 0;
 	}
-	debug2("channel %d: rcvd ext data %d", c->self, data_len);
+	debug2("channel %d: rcvd ext data %zu", c->self, data_len);
+	/* XXX sshpkt_getb? */
+	if ((r = sshbuf_put(c->extended, data, data_len)) != 0)
+		error("%s: append: %s", __func__, ssh_err(r));
 	c->local_window -= data_len;
-	buffer_append(&c->extended, data, data_len);
-	free(data);
 	return 0;
 }
 
-/* ARGSUSED */
 int
 channel_input_ieof(int type, u_int32_t seq, struct ssh *ssh)
 {
-	int id;
-	Channel *c;
+	Channel *c = channel_from_packet_id(ssh, __func__, "ieof");
+
+	ssh_packet_check_eom(ssh);
 
-	id = packet_get_int();
-	packet_check_eom();
-	c = channel_lookup(id);
-	if (c == NULL)
-		packet_disconnect("Received ieof for nonexistent channel %d.", id);
 	if (channel_proxy_upstream(c, type, seq, ssh))
 		return 0;
-	chan_rcvd_ieof(c);
+	chan_rcvd_ieof(ssh, c);
 
 	/* XXX force input close */
 	if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
 		debug("channel %d: FORCE input drain", c->self);
 		c->istate = CHAN_INPUT_WAIT_DRAIN;
-		if (buffer_len(&c->input) == 0)
-			chan_ibuf_empty(c);
+		if (sshbuf_len(c->input) == 0)
+			chan_ibuf_empty(ssh, c);
 	}
 	return 0;
 }
 
-/* ARGSUSED */
 int
 channel_input_oclose(int type, u_int32_t seq, struct ssh *ssh)
 {
-	int id = packet_get_int();
-	Channel *c = channel_lookup(id);
+	Channel *c = channel_from_packet_id(ssh, __func__, "oclose");
 
-	if (c == NULL)
-		packet_disconnect("Received oclose for nonexistent channel %d.", id);
 	if (channel_proxy_upstream(c, type, seq, ssh))
 		return 0;
-	packet_check_eom();
-	chan_rcvd_oclose(c);
+	ssh_packet_check_eom(ssh);
+	chan_rcvd_oclose(ssh, c);
 	return 0;
 }
 
-/* ARGSUSED */
 int
 channel_input_open_confirmation(int type, u_int32_t seq, struct ssh *ssh)
 {
-	int id, remote_id;
-	Channel *c;
-
-	id = packet_get_int();
-	c = channel_lookup(id);
+	Channel *c = channel_from_packet_id(ssh, __func__, "open confirmation");
+	u_int32_t remote_window, remote_maxpacket;
+	int r;
 
-	if (c==NULL)
-		packet_disconnect("Received open confirmation for "
-		    "unknown channel %d.", id);
 	if (channel_proxy_upstream(c, type, seq, ssh))
 		return 0;
 	if (c->type != SSH_CHANNEL_OPENING)
 		packet_disconnect("Received open confirmation for "
-		    "non-opening channel %d.", id);
-	remote_id = packet_get_int();
-	/* Record the remote channel number and mark that the channel is now open. */
-	c->remote_id = remote_id;
-	c->type = SSH_CHANNEL_OPEN;
+		    "non-opening channel %d.", c->self);
+	/*
+	 * Record the remote channel number and mark that the channel
+	 * is now open.
+	 */
+	c->remote_id = channel_parse_id(ssh, __func__, "open confirmation");
+	if ((r = sshpkt_get_u32(ssh, &remote_window)) != 0 ||
+	    (r = sshpkt_get_u32(ssh, &remote_maxpacket)) != 0) {
+		error("%s: window/maxpacket: %s", __func__, ssh_err(r));
+		packet_disconnect("Invalid open confirmation message");
+	}
+	ssh_packet_check_eom(ssh);
 
-	c->remote_window = packet_get_int();
-	c->remote_maxpacket = packet_get_int();
+	c->remote_window = remote_window;
+	c->remote_maxpacket = remote_maxpacket;
+	c->type = SSH_CHANNEL_OPEN;
 	if (c->open_confirm) {
-		debug2("callback start");
-		c->open_confirm(c->self, 1, c->open_confirm_ctx);
-		debug2("callback done");
+		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);
 	}
 	debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
 	    c->remote_window, c->remote_maxpacket);
-	packet_check_eom();
 	return 0;
 }
 
@@ -2679,97 +2960,97 @@ reason2txt(int reason)
 	return "unknown reason";
 }
 
-/* ARGSUSED */
 int
 channel_input_open_failure(int type, u_int32_t seq, struct ssh *ssh)
 {
-	int id, reason;
-	char *msg = NULL, *lang = NULL;
-	Channel *c;
-
-	id = packet_get_int();
-	c = channel_lookup(id);
+	Channel *c = channel_from_packet_id(ssh, __func__, "open failure");
+	u_int32_t reason;
+	char *msg = NULL;
+	int r;
 
-	if (c==NULL)
-		packet_disconnect("Received open failure for "
-		    "unknown channel %d.", id);
 	if (channel_proxy_upstream(c, type, seq, ssh))
 		return 0;
 	if (c->type != SSH_CHANNEL_OPENING)
 		packet_disconnect("Received open failure for "
-		    "non-opening channel %d.", id);
-	reason = packet_get_int();
-	if (!(datafellows & SSH_BUG_OPENFAILURE)) {
-		msg  = packet_get_string(NULL);
-		lang = packet_get_string(NULL);
+		    "non-opening channel %d.", c->self);
+	if ((r = sshpkt_get_u32(ssh, &reason)) != 0) {
+		error("%s: reason: %s", __func__, ssh_err(r));
+		packet_disconnect("Invalid open failure message");
+	}
+	if ((datafellows & SSH_BUG_OPENFAILURE) == 0) {
+		/* skip language */
+		if ((r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
+		    (r = sshpkt_get_string_direct(ssh, NULL, NULL)) == 0) {
+			error("%s: message/lang: %s", __func__, ssh_err(r));
+			packet_disconnect("Invalid open failure message");
+		}
 	}
-	logit("channel %d: open failed: %s%s%s", id,
+	ssh_packet_check_eom(ssh);
+	logit("channel %d: open failed: %s%s%s", c->self,
 	    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");
+		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, struct ssh *ssh)
 {
+	int id = channel_parse_id(ssh, __func__, "window adjust");
 	Channel *c;
-	int id;
-	u_int adjust, tmp;
-
-	/* Get the channel number and verify it. */
-	id = packet_get_int();
-	c = channel_lookup(id);
+	u_int32_t adjust;
+	u_int new_rwin;
+	int r;
 
-	if (c == NULL) {
+	if ((c = channel_lookup(ssh, id)) == NULL) {
 		logit("Received window adjust for non-open channel %d.", id);
 		return 0;
-	}
+        }
+
 	if (channel_proxy_upstream(c, type, seq, ssh))
 		return 0;
-	adjust = packet_get_int();
-	packet_check_eom();
-	debug2("channel %d: rcvd adjust %u", id, adjust);
-	if ((tmp = c->remote_window + adjust) < c->remote_window)
+	if ((r = sshpkt_get_u32(ssh, &adjust)) != 0) {
+		error("%s: adjust: %s", __func__, ssh_err(r));
+		packet_disconnect("Invalid window adjust message");
+	}
+	ssh_packet_check_eom(ssh);
+	debug2("channel %d: rcvd adjust %u", c->self, adjust);
+	if ((new_rwin = c->remote_window + adjust) < c->remote_window) {
 		fatal("channel %d: adjust %u overflows remote window %u",
-		    id, adjust, c->remote_window);
-	c->remote_window = tmp;
+		    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, struct ssh *ssh)
 {
+	int id = channel_parse_id(ssh, __func__, "status confirm");
 	Channel *c;
 	struct channel_confirm *cc;
-	int id;
 
 	/* Reset keepalive timeout */
 	packet_set_alive_timeouts(0);
 
-	id = packet_get_int();
-	debug2("channel_input_status_confirm: type %d id %d", type, id);
+	debug2("%s: type %d id %d", __func__, type, id);
 
-	if ((c = channel_lookup(id)) == NULL) {
-		logit("channel_input_status_confirm: %d: unknown", id);
+	if ((c = channel_lookup(ssh, id)) == NULL) {
+		logit("%s: %d: unknown", __func__, id);
 		return 0;
-	}	
+	}
 	if (channel_proxy_upstream(c, type, seq, ssh))
 		return 0;
-	packet_check_eom();
+	ssh_packet_check_eom(ssh);
 	if ((cc = TAILQ_FIRST(&c->status_confirms)) == NULL)
 		return 0;
-	cc->cb(type, c, cc->ctx);
+	cc->cb(ssh, type, c, cc->ctx);
 	TAILQ_REMOVE(&c->status_confirms, cc, entry);
 	explicit_bzero(cc, sizeof(*cc));
 	free(cc);
@@ -2779,9 +3060,9 @@ channel_input_status_confirm(int type, u_int32_t seq, struct ssh *ssh)
 /* -- tcp forwarding */
 
 void
-channel_set_af(int af)
+channel_set_af(struct ssh *ssh, int af)
 {
-	IPv4or6 = af;
+	ssh->chanctxt->IPv4or6 = af;
 }
 
 
@@ -2849,8 +3130,9 @@ 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;
@@ -2887,7 +3169,7 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 	 * set to NULL and hints.ai_flags is not AI_PASSIVE
 	 */
 	memset(&hints, 0, sizeof(hints));
-	hints.ai_family = IPv4or6;
+	hints.ai_family = ssh->chanctxt->IPv4or6;
 	hints.ai_flags = wildcard ? AI_PASSIVE : 0;
 	hints.ai_socktype = SOCK_STREAM;
 	snprintf(strport, sizeof strport, "%d", fwd->listen_port);
@@ -2921,12 +3203,14 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 		 * If allocating a port for -R forwards, then use the
 		 * same port for all address families.
 		 */
-		if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
-		    allocated_listen_port != NULL && *allocated_listen_port > 0)
+		if (type == SSH_CHANNEL_RPORT_LISTENER &&
+		    fwd->listen_port == 0 && allocated_listen_port != NULL &&
+		    *allocated_listen_port > 0)
 			*lport_p = htons(*allocated_listen_port);
 
 		if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
-		    strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
+		    strport, sizeof(strport),
+		    NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
 			error("%s: getnameinfo failed", __func__);
 			continue;
 		}
@@ -2947,7 +3231,10 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 
 		/* Bind the socket to the address. */
 		if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
-			/* address can be in use ipv6 address is already bound */
+			/*
+			 * address can be in if use ipv6 address is
+			 * already bound
+			 */
 			if (!ai->ai_next)
 				error("bind: %.100s", strerror(errno));
 			else
@@ -2967,7 +3254,8 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 		 * fwd->listen_port == 0 requests a dynamically allocated port -
 		 * record what we got.
 		 */
-		if (type == SSH_CHANNEL_RPORT_LISTENER && fwd->listen_port == 0 &&
+		if (type == SSH_CHANNEL_RPORT_LISTENER &&
+		    fwd->listen_port == 0 &&
 		    allocated_listen_port != NULL &&
 		    *allocated_listen_port == 0) {
 			*allocated_listen_port = get_local_port(sock);
@@ -2976,7 +3264,7 @@ channel_setup_fwd_listener_tcpip(int type, struct Forward *fwd,
 		}
 
 		/* Allocate a channel number for the socket. */
-		c = channel_new("port listener", type, sock, sock, -1,
+		c = channel_new(ssh, "port listener", type, sock, sock, -1,
 		    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
 		    0, "port listener", 1);
 		c->path = xstrdup(host);
@@ -2997,8 +3285,8 @@ 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;
@@ -3060,7 +3348,7 @@ 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);
@@ -3071,66 +3359,71 @@ channel_setup_fwd_listener_streamlocal(int type, struct Forward *fwd,
 }
 
 static int
-channel_cancel_rport_listener_tcpip(const char *host, u_short port)
+channel_cancel_rport_listener_tcpip(struct ssh *ssh,
+    const char *host, u_short port)
 {
 	u_int i;
 	int found = 0;
 
-	for (i = 0; i < channels_alloc; i++) {
-		Channel *c = channels[i];
+	for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+		Channel *c = ssh->chanctxt->channels[i];
 		if (c == NULL || c->type != SSH_CHANNEL_RPORT_LISTENER)
 			continue;
 		if (strcmp(c->path, host) == 0 && c->listening_port == port) {
 			debug2("%s: close channel %d", __func__, i);
-			channel_free(c);
+			channel_free(ssh, c);
 			found = 1;
 		}
 	}
 
-	return (found);
+	return found;
 }
 
 static int
-channel_cancel_rport_listener_streamlocal(const char *path)
+channel_cancel_rport_listener_streamlocal(struct ssh *ssh, const char *path)
 {
 	u_int i;
 	int found = 0;
 
-	for (i = 0; i < channels_alloc; i++) {
-		Channel *c = channels[i];
+	for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+		Channel *c = ssh->chanctxt->channels[i];
 		if (c == NULL || c->type != SSH_CHANNEL_RUNIX_LISTENER)
 			continue;
 		if (c->path == NULL)
 			continue;
 		if (strcmp(c->path, path) == 0) {
 			debug2("%s: close channel %d", __func__, i);
-			channel_free(c);
+			channel_free(ssh, c);
 			found = 1;
 		}
 	}
 
-	return (found);
+	return found;
 }
 
 int
-channel_cancel_rport_listener(struct Forward *fwd)
+channel_cancel_rport_listener(struct ssh *ssh, struct Forward *fwd)
 {
-	if (fwd->listen_path != NULL)
-		return channel_cancel_rport_listener_streamlocal(fwd->listen_path);
-	else
-		return channel_cancel_rport_listener_tcpip(fwd->listen_host, fwd->listen_port);
+	if (fwd->listen_path != NULL) {
+		return channel_cancel_rport_listener_streamlocal(ssh,
+		    fwd->listen_path);
+	} else {
+		return channel_cancel_rport_listener_tcpip(ssh,
+		    fwd->listen_host, fwd->listen_port);
+	}
 }
 
 static int
-channel_cancel_lport_listener_tcpip(const char *lhost, u_short lport,
-    int cport, struct ForwardOptions *fwd_opts)
+channel_cancel_lport_listener_tcpip(struct ssh *ssh,
+    const char *lhost, u_short lport, int cport,
+    struct ForwardOptions *fwd_opts)
 {
 	u_int i;
 	int found = 0;
 	const char *addr = channel_fwd_bind_addr(lhost, NULL, 1, fwd_opts);
 
-	for (i = 0; i < channels_alloc; i++) {
-		Channel *c = channels[i];
+	for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+		Channel *c = ssh->chanctxt->channels[i];
 		if (c == NULL || c->type != SSH_CHANNEL_PORT_LISTENER)
 			continue;
 		if (c->listening_port != lport)
@@ -3148,16 +3441,16 @@ 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;
@@ -3167,54 +3460,59 @@ channel_cancel_lport_listener_streamlocal(const char *path)
 		return 0;
 	}
 
-	for (i = 0; i < channels_alloc; i++) {
-		Channel *c = channels[i];
+	for (i = 0; i < ssh->chanctxt->channels_alloc; i++) {
+		Channel *c = ssh->chanctxt->channels[i];
 		if (c == NULL || c->type != SSH_CHANNEL_UNIX_LISTENER)
 			continue;
 		if (c->listening_addr == NULL)
 			continue;
 		if (strcmp(c->listening_addr, path) == 0) {
 			debug2("%s: close channel %d", __func__, i);
-			channel_free(c);
+			channel_free(ssh, c);
 			found = 1;
 		}
 	}
 
-	return (found);
+	return found;
 }
 
 int
-channel_cancel_lport_listener(struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
+channel_cancel_lport_listener(struct ssh *ssh,
+    struct Forward *fwd, int cport, struct ForwardOptions *fwd_opts)
 {
-	if (fwd->listen_path != NULL)
-		return channel_cancel_lport_listener_streamlocal(fwd->listen_path);
-	else
-		return channel_cancel_lport_listener_tcpip(fwd->listen_host, fwd->listen_port, cport, fwd_opts);
+	if (fwd->listen_path != NULL) {
+		return channel_cancel_lport_listener_streamlocal(ssh,
+		    fwd->listen_path);
+	} else {
+		return channel_cancel_lport_listener_tcpip(ssh,
+		    fwd->listen_host, fwd->listen_port, cport, fwd_opts);
+	}
 }
 
 /* protocol local port fwd, used by ssh */
 int
-channel_setup_local_fwd_listener(struct Forward *fwd, struct ForwardOptions *fwd_opts)
+channel_setup_local_fwd_listener(struct ssh *ssh,
+    struct Forward *fwd, struct ForwardOptions *fwd_opts)
 {
 	if (fwd->listen_path != NULL) {
-		return channel_setup_fwd_listener_streamlocal(
+		return channel_setup_fwd_listener_streamlocal(ssh,
 		    SSH_CHANNEL_UNIX_LISTENER, fwd, fwd_opts);
 	} else {
-		return channel_setup_fwd_listener_tcpip(SSH_CHANNEL_PORT_LISTENER,
-		    fwd, NULL, fwd_opts);
+		return channel_setup_fwd_listener_tcpip(ssh,
+		    SSH_CHANNEL_PORT_LISTENER, fwd, NULL, fwd_opts);
 	}
 }
 
 /* protocol v2 remote port fwd, used by sshd */
 int
-channel_setup_remote_fwd_listener(struct Forward *fwd,
+channel_setup_remote_fwd_listener(struct ssh *ssh, struct Forward *fwd,
     int *allocated_listen_port, struct ForwardOptions *fwd_opts)
 {
 	if (fwd->listen_path != NULL) {
-		return channel_setup_fwd_listener_streamlocal(
+		return channel_setup_fwd_listener_streamlocal(ssh,
 		    SSH_CHANNEL_RUNIX_LISTENER, fwd, fwd_opts);
 	} else {
-		return channel_setup_fwd_listener_tcpip(
+		return channel_setup_fwd_listener_tcpip(ssh,
 		    SSH_CHANNEL_RPORT_LISTENER, fwd, allocated_listen_port,
 		    fwd_opts);
 	}
@@ -3248,56 +3546,61 @@ channel_rfwd_bind_host(const char *listen_host)
  * channel_update_permitted_opens().
  */
 int
-channel_request_remote_forwarding(struct Forward *fwd)
+channel_request_remote_forwarding(struct ssh *ssh, struct Forward *fwd)
 {
-	int 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. */
-	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);
+		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 {
-	    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);
+		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));
 	}
-	packet_send();
-	packet_write_wait();
 	/* Assume that server accepts the request */
 	success = 1;
 	if (success) {
 		/* Record that connection to this host/port is permitted. */
-		permitted_opens = xreallocarray(permitted_opens,
-		    num_permitted_opens + 1, sizeof(*permitted_opens));
-		idx = num_permitted_opens++;
+		host_to_connect = listen_host = listen_path = NULL;
+		port_to_connect = listen_port = 0;
 		if (fwd->connect_path != NULL) {
-			permitted_opens[idx].host_to_connect =
-			    xstrdup(fwd->connect_path);
-			permitted_opens[idx].port_to_connect =
-			    PORT_STREAMLOCAL;
+			host_to_connect = xstrdup(fwd->connect_path);
+			port_to_connect = PORT_STREAMLOCAL;
 		} else {
-			permitted_opens[idx].host_to_connect =
-			    xstrdup(fwd->connect_host);
-			permitted_opens[idx].port_to_connect =
-			    fwd->connect_port;
+			host_to_connect = xstrdup(fwd->connect_host);
+			port_to_connect = fwd->connect_port;
 		}
 		if (fwd->listen_path != NULL) {
-			permitted_opens[idx].listen_host = NULL;
-			permitted_opens[idx].listen_path =
-			    xstrdup(fwd->listen_path);
-			permitted_opens[idx].listen_port = PORT_STREAMLOCAL;
+			listen_path = xstrdup(fwd->listen_path);
+			listen_port = PORT_STREAMLOCAL;
 		} else {
-			permitted_opens[idx].listen_host =
-			    fwd->listen_host ? xstrdup(fwd->listen_host) : NULL;
-			permitted_opens[idx].listen_path = NULL;
-			permitted_opens[idx].listen_port = fwd->listen_port;
+			if (fwd->listen_host != NULL)
+				listen_host = xstrdup(fwd->listen_host);
+			listen_port = fwd->listen_port;
 		}
-		permitted_opens[idx].downstream = NULL;
+		idx = fwd_perm_list_add(ssh, FWDPERM_USER,
+		    host_to_connect, port_to_connect,
+		    listen_host, listen_path, listen_port, NULL);
 	}
-	return (idx);
+	return idx;
 }
 
 static int
@@ -3362,33 +3665,33 @@ open_listen_match_streamlocal(ForwardPermission *allowed_open,
  * local side.
  */
 static int
-channel_request_rforward_cancel_tcpip(const char *host, u_short port)
+channel_request_rforward_cancel_tcpip(struct ssh *ssh,
+    const char *host, u_short port)
 {
-	int i;
+	struct ssh_channels *sc = ssh->chanctxt;
+	int r;
+	u_int i;
+	ForwardPermission *fp;
 
-	for (i = 0; i < num_permitted_opens; i++) {
-		if (open_listen_match_tcpip(&permitted_opens[i], host, port, 0))
+	for (i = 0; i < sc->num_permitted_opens; i++) {
+		fp = &sc->permitted_opens[i];
+		if (open_listen_match_tcpip(fp, host, port, 0))
 			break;
+		fp = NULL;
 	}
-	if (i >= num_permitted_opens) {
+	if (fp == NULL) {
 		debug("%s: requested forward not found", __func__);
 		return -1;
 	}
-	packet_start(SSH2_MSG_GLOBAL_REQUEST);
-	packet_put_cstring("cancel-tcpip-forward");
-	packet_put_char(0);
-	packet_put_cstring(channel_rfwd_bind_host(host));
-	packet_put_int(port);
-	packet_send();
-
-	permitted_opens[i].listen_port = 0;
-	permitted_opens[i].port_to_connect = 0;
-	free(permitted_opens[i].host_to_connect);
-	permitted_opens[i].host_to_connect = NULL;
-	free(permitted_opens[i].listen_host);
-	permitted_opens[i].listen_host = NULL;
-	permitted_opens[i].listen_path = NULL;
-	permitted_opens[i].downstream = NULL;
+	if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, "cancel-tcpip-forward")) != 0 ||
+	    (r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */
+	    (r = sshpkt_put_cstring(ssh, channel_rfwd_bind_host(host))) != 0 ||
+	    (r = sshpkt_put_u32(ssh, port)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: send cancel: %s", __func__, ssh_err(r));
+
+	fwd_perm_clear(fp); /* unregister */
 
 	return 0;
 }
@@ -3398,32 +3701,32 @@ channel_request_rforward_cancel_tcpip(const char *host, u_short port)
  * path from local side.
  */
 static int
-channel_request_rforward_cancel_streamlocal(const char *path)
+channel_request_rforward_cancel_streamlocal(struct ssh *ssh, const char *path)
 {
-	int i;
+	struct ssh_channels *sc = ssh->chanctxt;
+	int r;
+	u_int i;
+	ForwardPermission *fp;
 
-	for (i = 0; i < num_permitted_opens; i++) {
-		if (open_listen_match_streamlocal(&permitted_opens[i], path))
+	for (i = 0; i < sc->num_permitted_opens; i++) {
+		fp = &sc->permitted_opens[i];
+		if (open_listen_match_streamlocal(fp, path))
 			break;
+		fp = NULL;
 	}
-	if (i >= num_permitted_opens) {
+	if (fp == NULL) {
 		debug("%s: requested forward not found", __func__);
 		return -1;
 	}
-	packet_start(SSH2_MSG_GLOBAL_REQUEST);
-	packet_put_cstring("cancel-streamlocal-forward@openssh.com");
-	packet_put_char(0);
-	packet_put_cstring(path);
-	packet_send();
-
-	permitted_opens[i].listen_port = 0;
-	permitted_opens[i].port_to_connect = 0;
-	free(permitted_opens[i].host_to_connect);
-	permitted_opens[i].host_to_connect = NULL;
-	permitted_opens[i].listen_host = NULL;
-	free(permitted_opens[i].listen_path);
-	permitted_opens[i].listen_path = NULL;
-	permitted_opens[i].downstream = NULL;
+	if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh,
+	    "cancel-streamlocal-forward@openssh.com")) != 0 ||
+	    (r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */
+	    (r = sshpkt_put_cstring(ssh, path)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: send cancel: %s", __func__, ssh_err(r));
+
+	fwd_perm_clear(fp); /* unregister */
 
 	return 0;
 }
@@ -3432,14 +3735,15 @@ channel_request_rforward_cancel_streamlocal(const char *path)
  * Request cancellation of remote forwarding of a connection from local side.
  */
 int
-channel_request_rforward_cancel(struct Forward *fwd)
+channel_request_rforward_cancel(struct ssh *ssh, struct Forward *fwd)
 {
 	if (fwd->listen_path != NULL) {
-		return (channel_request_rforward_cancel_streamlocal(
-		    fwd->listen_path));
+		return channel_request_rforward_cancel_streamlocal(ssh,
+		    fwd->listen_path);
 	} else {
-		return (channel_request_rforward_cancel_tcpip(fwd->listen_host,
-		    fwd->listen_port ? fwd->listen_port : fwd->allocated_port));
+		return channel_request_rforward_cancel_tcpip(ssh,
+		    fwd->listen_host,
+		    fwd->listen_port ? fwd->listen_port : fwd->allocated_port);
 	}
 }
 
@@ -3449,28 +3753,20 @@ channel_request_rforward_cancel(struct Forward *fwd)
  * anyway, and the server has no way to know but to trust the client anyway.
  */
 void
-channel_permit_all_opens(void)
+channel_permit_all_opens(struct ssh *ssh)
 {
-	if (num_permitted_opens == 0)
-		all_opens_permitted = 1;
+	if (ssh->chanctxt->num_permitted_opens == 0)
+		ssh->chanctxt->all_opens_permitted = 1;
 }
 
 void
-channel_add_permitted_opens(char *host, int port)
+channel_add_permitted_opens(struct ssh *ssh, char *host, int port)
 {
-	debug("allow port forwarding to host %s port %d", host, port);
+	struct ssh_channels *sc = ssh->chanctxt;
 
-	permitted_opens = xreallocarray(permitted_opens,
-	    num_permitted_opens + 1, sizeof(*permitted_opens));
-	permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
-	permitted_opens[num_permitted_opens].port_to_connect = port;
-	permitted_opens[num_permitted_opens].listen_host = NULL;
-	permitted_opens[num_permitted_opens].listen_path = NULL;
-	permitted_opens[num_permitted_opens].listen_port = 0;
-	permitted_opens[num_permitted_opens].downstream = NULL;
-	num_permitted_opens++;
-
-	all_opens_permitted = 0;
+	debug("allow port forwarding to host %s port %d", host, port);
+	fwd_perm_list_add(ssh, FWDPERM_USER, host, port, NULL, NULL, 0, NULL);
+	sc->all_opens_permitted = 0;
 }
 
 /*
@@ -3479,105 +3775,61 @@ channel_add_permitted_opens(char *host, int port)
  * passed then they entry will be invalidated.
  */
 void
-channel_update_permitted_opens(int idx, int newport)
+channel_update_permitted_opens(struct ssh *ssh, int idx, int newport)
 {
-	if (idx < 0 || idx >= num_permitted_opens) {
-		debug("channel_update_permitted_opens: index out of range:"
-		    " %d num_permitted_opens %d", idx, num_permitted_opens);
+	struct ssh_channels *sc = ssh->chanctxt;
+
+	if (idx < 0 || (u_int)idx >= sc->num_permitted_opens) {
+		debug("%s: index out of range: %d num_permitted_opens %d",
+		    __func__, idx, sc->num_permitted_opens);
 		return;
 	}
 	debug("%s allowed port %d for forwarding to host %s port %d",
 	    newport > 0 ? "Updating" : "Removing",
 	    newport,
-	    permitted_opens[idx].host_to_connect,
-	    permitted_opens[idx].port_to_connect);
-	if (newport >= 0)  {
-		permitted_opens[idx].listen_port = 
+	    sc->permitted_opens[idx].host_to_connect,
+	    sc->permitted_opens[idx].port_to_connect);
+	if (newport <= 0)
+		fwd_perm_clear(&sc->permitted_opens[idx]);
+	else {
+		sc->permitted_opens[idx].listen_port =
 		    (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
-	} else {
-		permitted_opens[idx].listen_port = 0;
-		permitted_opens[idx].port_to_connect = 0;
-		free(permitted_opens[idx].host_to_connect);
-		permitted_opens[idx].host_to_connect = NULL;
-		free(permitted_opens[idx].listen_host);
-		permitted_opens[idx].listen_host = NULL;
-		free(permitted_opens[idx].listen_path);
-		permitted_opens[idx].listen_path = NULL;
 	}
 }
 
 int
-channel_add_adm_permitted_opens(char *host, int port)
+channel_add_adm_permitted_opens(struct ssh *ssh, char *host, int port)
 {
 	debug("config allows port forwarding to host %s port %d", host, port);
-
-	permitted_adm_opens = xreallocarray(permitted_adm_opens,
-	    num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
-	permitted_adm_opens[num_adm_permitted_opens].host_to_connect
-	     = xstrdup(host);
-	permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
-	permitted_adm_opens[num_adm_permitted_opens].listen_host = NULL;
-	permitted_adm_opens[num_adm_permitted_opens].listen_path = NULL;
-	permitted_adm_opens[num_adm_permitted_opens].listen_port = 0;
-	return ++num_adm_permitted_opens;
-}
-
-void
-channel_disable_adm_local_opens(void)
-{
-	channel_clear_adm_permitted_opens();
-	permitted_adm_opens = xcalloc(sizeof(*permitted_adm_opens), 1);
-	permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
-	num_adm_permitted_opens = 1;
+	return fwd_perm_list_add(ssh, FWDPERM_ADMIN, host, port,
+	    NULL, NULL, 0, NULL);
 }
 
 void
-channel_clear_permitted_opens(void)
+channel_disable_adm_local_opens(struct ssh *ssh)
 {
-	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;
+	channel_clear_adm_permitted_opens(ssh);
+	fwd_perm_list_add(ssh, FWDPERM_ADMIN, NULL, 0, NULL, NULL, 0, NULL);
 }
 
 void
-channel_clear_adm_permitted_opens(void)
+channel_clear_permitted_opens(struct ssh *ssh)
 {
-	int i;
+	struct ssh_channels *sc = ssh->chanctxt;
 
-	for (i = 0; i < num_adm_permitted_opens; i++) {
-		free(permitted_adm_opens[i].host_to_connect);
-		free(permitted_adm_opens[i].listen_host);
-		free(permitted_adm_opens[i].listen_path);
-	}
-	free(permitted_adm_opens);
-	permitted_adm_opens = NULL;
-	num_adm_permitted_opens = 0;
+	sc->permitted_opens = xrecallocarray(sc->permitted_opens,
+	    sc->num_permitted_opens, 0, sizeof(*sc->permitted_opens));
+	sc->num_permitted_opens = 0;
 }
 
 void
-channel_print_adm_permitted_opens(void)
+channel_clear_adm_permitted_opens(struct ssh *ssh)
 {
-	int i;
+	struct ssh_channels *sc = ssh->chanctxt;
 
-	printf("permitopen");
-	if (num_adm_permitted_opens == 0) {
-		printf(" any\n");
-		return;
-	}
-	for (i = 0; i < num_adm_permitted_opens; i++)
-		if (permitted_adm_opens[i].host_to_connect == NULL)
-			printf(" none");
-		else
-			printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
-			    permitted_adm_opens[i].port_to_connect);
-	printf("\n");
+	sc->permitted_adm_opens = xrecallocarray(sc->permitted_adm_opens,
+	    sc->num_adm_permitted_opens, 0, sizeof(*sc->permitted_adm_opens));
+	sc->num_adm_permitted_opens = 0;
 }
 
 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
@@ -3599,7 +3851,8 @@ connect_next(struct channel_connect *cctx)
 {
 	int sock, saved_errno;
 	struct sockaddr_un *sunaddr;
-	char ntop[NI_MAXHOST], strport[MAXIMUM(NI_MAXSERV,sizeof(sunaddr->sun_path))];
+	char ntop[NI_MAXHOST];
+	char strport[MAXIMUM(NI_MAXSERV, sizeof(sunaddr->sun_path))];
 
 	for (; cctx->ai; cctx->ai = cctx->ai->ai_next) {
 		switch (cctx->ai->ai_family) {
@@ -3669,8 +3922,8 @@ channel_connect_ctx_free(struct channel_connect *cctx)
  * passing back the failure reason if appropriate.
  */
 static Channel *
-connect_to_reason(const char *name, int port, char *ctype, char *rname,
-     int *reason, const char **errmsg)
+connect_to_reason(struct ssh *ssh, const char *name, int port,
+    char *ctype, char *rname, int *reason, const char **errmsg)
 {
 	struct addrinfo hints;
 	int gaierr;
@@ -3708,7 +3961,7 @@ connect_to_reason(const char *name, int port, char *ctype, char *rname,
 		cctx.aitop = ai;
 	} else {
 		memset(&hints, 0, sizeof(hints));
-		hints.ai_family = IPv4or6;
+		hints.ai_family = ssh->chanctxt->IPv4or6;
 		hints.ai_socktype = SOCK_STREAM;
 		snprintf(strport, sizeof strport, "%d", port);
 		if ((gaierr = getaddrinfo(name, strport, &hints, &cctx.aitop))
@@ -3733,7 +3986,7 @@ connect_to_reason(const char *name, int port, char *ctype, char *rname,
 		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->connect_ctx = cctx;
 	return c;
@@ -3741,9 +3994,10 @@ connect_to_reason(const char *name, int port, char *ctype, char *rname,
 
 /* Return CONNECTING channel to remote host:port or local socket path */
 static Channel *
-connect_to(const char *name, int port, char *ctype, char *rname)
+connect_to(struct ssh *ssh, const char *name, int port,
+    char *ctype, char *rname)
 {
-	return connect_to_reason(name, port, ctype, rname, NULL, NULL);
+	return connect_to_reason(ssh, name, port, ctype, rname, NULL, NULL);
 }
 
 /*
@@ -3751,19 +4005,21 @@ connect_to(const char *name, int port, char *ctype, char *rname)
  * that needs to deal with this connection.
  */
 Channel *
-channel_connect_by_listen_address(const char *listen_host,
+channel_connect_by_listen_address(struct ssh *ssh, const char *listen_host,
     u_short listen_port, char *ctype, char *rname)
 {
-	int i;
-
-	for (i = 0; i < num_permitted_opens; i++) {
-		if (open_listen_match_tcpip(&permitted_opens[i], listen_host,
-		    listen_port, 1)) {
-			if (permitted_opens[i].downstream)
-				return permitted_opens[i].downstream;
-			return connect_to(
-			    permitted_opens[i].host_to_connect,
-			    permitted_opens[i].port_to_connect, ctype, rname);
+	struct ssh_channels *sc = ssh->chanctxt;
+	u_int i;
+	ForwardPermission *fp;
+
+	for (i = 0; i < sc->num_permitted_opens; i++) {
+		fp = &sc->permitted_opens[i];
+		if (open_listen_match_tcpip(fp, listen_host, listen_port, 1)) {
+			if (fp->downstream)
+				return fp->downstream;
+			return connect_to(ssh,
+			    fp->host_to_connect, fp->port_to_connect,
+			    ctype, rname);
 		}
 	}
 	error("WARNING: Server requests forwarding for unknown listen_port %d",
@@ -3772,15 +4028,19 @@ channel_connect_by_listen_address(const char *listen_host,
 }
 
 Channel *
-channel_connect_by_listen_path(const char *path, char *ctype, char *rname)
+channel_connect_by_listen_path(struct ssh *ssh, const char *path,
+    char *ctype, char *rname)
 {
-	int i;
-
-	for (i = 0; i < num_permitted_opens; i++) {
-		if (open_listen_match_streamlocal(&permitted_opens[i], path)) {
-			return connect_to(
-			    permitted_opens[i].host_to_connect,
-			    permitted_opens[i].port_to_connect, ctype, rname);
+	struct ssh_channels *sc = ssh->chanctxt;
+	u_int i;
+	ForwardPermission *fp;
+
+	for (i = 0; i < sc->num_permitted_opens; i++) {
+		fp = &sc->permitted_opens[i];
+		if (open_listen_match_streamlocal(fp, path)) {
+			return connect_to(ssh,
+			    fp->host_to_connect, fp->port_to_connect,
+			    ctype, rname);
 		}
 	}
 	error("WARNING: Server requests forwarding for unknown path %.100s",
@@ -3790,27 +4050,33 @@ channel_connect_by_listen_path(const char *path, char *ctype, char *rname)
 
 /* Check if connecting to that port is permitted and connect. */
 Channel *
-channel_connect_to_port(const char *host, u_short port, char *ctype,
-    char *rname, int *reason, const char **errmsg)
+channel_connect_to_port(struct ssh *ssh, const char *host, u_short port,
+    char *ctype, char *rname, int *reason, const char **errmsg)
 {
-	int i, permit, permit_adm = 1;
+	struct ssh_channels *sc = ssh->chanctxt;
+	u_int i, permit, permit_adm = 1;
+	ForwardPermission *fp;
 
-	permit = all_opens_permitted;
+	permit = sc->all_opens_permitted;
 	if (!permit) {
-		for (i = 0; i < num_permitted_opens; i++)
-			if (open_match(&permitted_opens[i], host, port)) {
+		for (i = 0; i < sc->num_permitted_opens; i++) {
+			fp = &sc->permitted_opens[i];
+			if (open_match(fp, host, port)) {
 				permit = 1;
 				break;
 			}
+		}
 	}
 
-	if (num_adm_permitted_opens > 0) {
+	if (sc->num_adm_permitted_opens > 0) {
 		permit_adm = 0;
-		for (i = 0; i < num_adm_permitted_opens; i++)
-			if (open_match(&permitted_adm_opens[i], host, port)) {
+		for (i = 0; i < sc->num_adm_permitted_opens; i++) {
+			fp = &sc->permitted_adm_opens[i];
+			if (open_match(fp, host, port)) {
 				permit_adm = 1;
 				break;
 			}
+		}
 	}
 
 	if (!permit || !permit_adm) {
@@ -3820,31 +4086,38 @@ channel_connect_to_port(const char *host, u_short port, char *ctype,
 			*reason = SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED;
 		return NULL;
 	}
-	return connect_to_reason(host, port, ctype, rname, reason, errmsg);
+	return connect_to_reason(ssh, host, port, ctype, rname, reason, errmsg);
 }
 
 /* Check if connecting to that path is permitted and connect. */
 Channel *
-channel_connect_to_path(const char *path, char *ctype, char *rname)
+channel_connect_to_path(struct ssh *ssh, const char *path,
+    char *ctype, char *rname)
 {
-	int i, permit, permit_adm = 1;
+	struct ssh_channels *sc = ssh->chanctxt;
+	u_int i, permit, permit_adm = 1;
+	ForwardPermission *fp;
 
-	permit = all_opens_permitted;
+	permit = sc->all_opens_permitted;
 	if (!permit) {
-		for (i = 0; i < num_permitted_opens; i++)
-			if (open_match(&permitted_opens[i], path, PORT_STREAMLOCAL)) {
+		for (i = 0; i < sc->num_permitted_opens; i++) {
+			fp = &sc->permitted_opens[i];
+			if (open_match(fp, path, PORT_STREAMLOCAL)) {
 				permit = 1;
 				break;
 			}
+		}
 	}
 
-	if (num_adm_permitted_opens > 0) {
+	if (sc->num_adm_permitted_opens > 0) {
 		permit_adm = 0;
-		for (i = 0; i < num_adm_permitted_opens; i++)
-			if (open_match(&permitted_adm_opens[i], path, PORT_STREAMLOCAL)) {
+		for (i = 0; i < sc->num_adm_permitted_opens; i++) {
+			fp = &sc->permitted_adm_opens[i];
+			if (open_match(fp, path, PORT_STREAMLOCAL)) {
 				permit_adm = 1;
 				break;
 			}
+		}
 	}
 
 	if (!permit || !permit_adm) {
@@ -3852,27 +4125,31 @@ channel_connect_to_path(const char *path, char *ctype, char *rname)
 		    "but the request was denied.", path);
 		return NULL;
 	}
-	return connect_to(path, PORT_STREAMLOCAL, ctype, rname);
+	return connect_to(ssh, path, PORT_STREAMLOCAL, ctype, rname);
 }
 
 void
-channel_send_window_changes(void)
+channel_send_window_changes(struct ssh *ssh)
 {
-	u_int i;
+	struct ssh_channels *sc = ssh->chanctxt;
 	struct winsize ws;
+	int r;
+	u_int i;
 
-	for (i = 0; i < channels_alloc; i++) {
-		if (channels[i] == NULL || !channels[i]->client_tty ||
-		    channels[i]->type != SSH_CHANNEL_OPEN)
+	for (i = 0; i < sc->channels_alloc; i++) {
+		if (sc->channels[i] == NULL || !sc->channels[i]->client_tty ||
+		    sc->channels[i]->type != SSH_CHANNEL_OPEN)
 			continue;
-		if (ioctl(channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
+		if (ioctl(sc->channels[i]->rfd, TIOCGWINSZ, &ws) < 0)
 			continue;
-		channel_request_start(i, "window-change", 0);
-		packet_put_int((u_int)ws.ws_col);
-		packet_put_int((u_int)ws.ws_row);
-		packet_put_int((u_int)ws.ws_xpixel);
-		packet_put_int((u_int)ws.ws_ypixel);
-		packet_send();
+		channel_request_start(ssh, i, "window-change", 0);
+		if ((r = sshpkt_put_u32(ssh, (u_int)ws.ws_col)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_row)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_xpixel)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, (u_int)ws.ws_ypixel)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0)
+			fatal("%s: channel %u: send window-change: %s",
+			    __func__, i, ssh_err(r));
 	}
 }
 
@@ -3884,8 +4161,9 @@ 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;
@@ -3902,16 +4180,18 @@ x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
 	    display_number++) {
 		port = 6000 + display_number;
 		memset(&hints, 0, sizeof(hints));
-		hints.ai_family = IPv4or6;
+		hints.ai_family = ssh->chanctxt->IPv4or6;
 		hints.ai_flags = x11_use_localhost ? 0: AI_PASSIVE;
 		hints.ai_socktype = SOCK_STREAM;
 		snprintf(strport, sizeof strport, "%d", port);
-		if ((gaierr = getaddrinfo(NULL, strport, &hints, &aitop)) != 0) {
+		if ((gaierr = getaddrinfo(NULL, strport,
+		    &hints, &aitop)) != 0) {
 			error("getaddrinfo: %.100s", ssh_gai_strerror(gaierr));
 			return -1;
 		}
 		for (ai = aitop; ai; ai = ai->ai_next) {
-			if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+			if (ai->ai_family != AF_INET &&
+			    ai->ai_family != AF_INET6)
 				continue;
 			sock = socket(ai->ai_family, ai->ai_socktype,
 			    ai->ai_protocol);
@@ -3935,12 +4215,11 @@ x11_create_display_inet(int x11_display_offset, int x11_use_localhost,
 			if (x11_use_localhost)
 				channel_set_reuseaddr(sock);
 			if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
-				debug2("bind port %d: %.100s", port, strerror(errno));
+				debug2("%s: bind port %d: %.100s", __func__,
+				    port, strerror(errno));
 				close(sock);
-
-				for (n = 0; n < num_socks; n++) {
+				for (n = 0; n < num_socks; n++)
 					close(socks[n]);
-				}
 				num_socks = 0;
 				break;
 			}
@@ -3970,7 +4249,7 @@ 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);
@@ -3981,7 +4260,7 @@ 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
@@ -4039,7 +4318,7 @@ is_path_to_xsocket(const char *display, char *path, size_t pathlen)
 #endif
 
 int
-x11_connect_display(void)
+x11_connect_display(struct ssh *ssh)
 {
 	u_int display_number;
 	const char *display;
@@ -4084,9 +4363,10 @@ 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. */
@@ -4108,7 +4388,10 @@ 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);
@@ -4117,7 +4400,7 @@ 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) {
@@ -4144,8 +4427,8 @@ 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);
@@ -4158,18 +4441,19 @@ x11_connect_display(void)
  * This should be called in the client only.
  */
 void
-x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
-    const char *proto, const char *data, int want_reply)
+x11_request_forwarding_with_spoofing(struct ssh *ssh, int client_session_id,
+    const char *disp, const char *proto, const char *data, int want_reply)
 {
+	struct ssh_channels *sc = ssh->chanctxt;
 	u_int data_len = (u_int) strlen(data) / 2;
 	u_int i, value;
-	char *new_data;
-	int screen_number;
 	const char *cp;
+	char *new_data;
+	int r, screen_number;
 
-	if (x11_saved_display == NULL)
-		x11_saved_display = xstrdup(disp);
-	else if (strcmp(disp, x11_saved_display) != 0) {
+	if (sc->x11_saved_display == NULL)
+		sc->x11_saved_display = xstrdup(disp);
+	else if (strcmp(disp, sc->x11_saved_display) != 0) {
 		error("x11_request_forwarding_with_spoofing: different "
 		    "$DISPLAY already forwarded");
 		return;
@@ -4183,36 +4467,37 @@ x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
 	else
 		screen_number = 0;
 
-	if (x11_saved_proto == NULL) {
+	if (sc->x11_saved_proto == NULL) {
 		/* Save protocol name. */
-		x11_saved_proto = xstrdup(proto);
+		sc->x11_saved_proto = xstrdup(proto);
 
 		/* Extract real authentication data. */
-		x11_saved_data = xmalloc(data_len);
+		sc->x11_saved_data = xmalloc(data_len);
 		for (i = 0; i < data_len; i++) {
 			if (sscanf(data + 2 * i, "%2x", &value) != 1)
 				fatal("x11_request_forwarding: bad "
 				    "authentication data: %.100s", data);
-			x11_saved_data[i] = value;
+			sc->x11_saved_data[i] = value;
 		}
-		x11_saved_data_len = data_len;
+		sc->x11_saved_data_len = data_len;
 
 		/* Generate fake data of the same length. */
-		x11_fake_data = xmalloc(data_len);
-		arc4random_buf(x11_fake_data, data_len);
-		x11_fake_data_len = data_len;
+		sc->x11_fake_data = xmalloc(data_len);
+		arc4random_buf(sc->x11_fake_data, data_len);
+		sc->x11_fake_data_len = data_len;
 	}
 
 	/* Convert the fake data into hex. */
-	new_data = tohex(x11_fake_data, data_len);
+	new_data = tohex(sc->x11_fake_data, data_len);
 
 	/* Send the request packet. */
-	channel_request_start(client_session_id, "x11-req", want_reply);
-	packet_put_char(0);	/* XXX bool single connection */
-	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);
 }
diff --git a/channels.h b/channels.h
index 5ecb4d7c0..f04c43afa 100644
--- a/channels.h
+++ b/channels.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.h,v 1.127 2017/08/30 03:59:08 djm Exp $ */
+/* $OpenBSD: channels.h,v 1.128 2017/09/12 06:32:07 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -64,16 +64,18 @@
 struct ssh;
 struct Channel;
 typedef struct Channel Channel;
+struct fwd_perm_list;
 
-typedef void channel_open_fn(int, int, void *);
-typedef void channel_callback_fn(int, void *);
-typedef int channel_infilter_fn(struct Channel *, char *, int);
-typedef void channel_filter_cleanup_fn(int, void *);
-typedef u_char *channel_outfilter_fn(struct Channel *, u_char **, u_int *);
+typedef void channel_open_fn(struct ssh *, int, int, void *);
+typedef void channel_callback_fn(struct ssh *, int, void *);
+typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int);
+typedef void channel_filter_cleanup_fn(struct ssh *, int, void *);
+typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *,
+    u_char **, size_t *);
 
 /* Channel success/failure callbacks */
-typedef void channel_confirm_cb(int, struct Channel *, void *);
-typedef void channel_confirm_abandon_cb(struct Channel *, void *);
+typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *);
+typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *);
 struct channel_confirm {
 	TAILQ_ENTRY(channel_confirm) entry;
 	channel_confirm_cb *cb;
@@ -90,12 +92,13 @@ struct channel_connect {
 };
 
 /* Callbacks for mux channels back into client-specific code */
-typedef int mux_callback_fn(struct Channel *);
+typedef int mux_callback_fn(struct ssh *, struct Channel *);
 
 struct Channel {
 	int     type;		/* channel type/state */
 	int     self;		/* my own channel identifier */
 	int     remote_id;	/* channel identifier for remote peer */
+				/* XXX should be uint32_t */
 	u_int   istate;		/* input from channel (state of receive half) */
 	u_int   ostate;		/* output to channel  (state of transmit half) */
 	int     flags;		/* close sent/rcvd */
@@ -116,11 +119,12 @@ struct Channel {
 				 * to a matching pre-select handler.
 				 * this way post-select handlers are not
 				 * accidentally called if a FD gets reused */
-	Buffer  input;		/* data read from socket, to be sent over
+	struct sshbuf *input;	/* data read from socket, to be sent over
 				 * encrypted connection */
-	Buffer  output;		/* data received over encrypted connection for
+	struct sshbuf *output;	/* data received over encrypted connection for
 				 * send on socket */
-	Buffer  extended;
+	struct sshbuf *extended;
+
 	char    *path;
 		/* path for unix domain sockets, or host name for forwards */
 	int     listening_port;	/* port being listened for forwards */
@@ -156,6 +160,7 @@ struct Channel {
 	int     		datagram;
 
 	/* non-blocking connect */
+	/* XXX make this a pointer so the structure can be opaque */
 	struct channel_connect	connect_ctx;
 
 	/* multiplexing protocol hook, called for each packet received */
@@ -195,44 +200,55 @@ struct Channel {
 #define CHAN_EOF_RCVD			0x08
 #define CHAN_LOCAL			0x10
 
-#define CHAN_RBUF	16*1024
+/* Read buffer size */
+#define CHAN_RBUF	(16*1024)
+
+/* Hard limit on number of channels */
+#define CHANNELS_MAX_CHANNELS	(16*1024)
 
 /* check whether 'efd' is still in use */
 #define CHANNEL_EFD_INPUT_ACTIVE(c) \
 	(c->extended_usage == CHAN_EXTENDED_READ && \
 	(c->efd != -1 || \
-	buffer_len(&c->extended) > 0))
+	sshbuf_len(c->extended) > 0))
 #define CHANNEL_EFD_OUTPUT_ACTIVE(c) \
 	(c->extended_usage == CHAN_EXTENDED_WRITE && \
 	c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \
-	buffer_len(&c->extended) > 0))
+	sshbuf_len(c->extended) > 0))
+
+/* Add channel management structures to SSH transport instance */
+void channel_init_channels(struct ssh *ssh);
 
 /* channel management */
 
-Channel	*channel_by_id(int);
-Channel	*channel_by_remote_id(int);
-Channel	*channel_lookup(int);
-Channel *channel_new(char *, int, int, int, int, u_int, u_int, int, char *, int);
-void	 channel_set_fds(int, int, int, int, int, int, int, u_int);
-void	 channel_free(Channel *);
-void	 channel_free_all(void);
-void	 channel_stop_listening(void);
-
-void	 channel_send_open(int);
-void	 channel_request_start(int, char *, int);
-void	 channel_register_cleanup(int, channel_callback_fn *, int);
-void	 channel_register_open_confirm(int, channel_open_fn *, void *);
-void	 channel_register_filter(int, channel_infilter_fn *,
-    channel_outfilter_fn *, channel_filter_cleanup_fn *, void *);
-void	 channel_register_status_confirm(int, channel_confirm_cb *,
-    channel_confirm_abandon_cb *, void *);
-void	 channel_cancel_cleanup(int);
-int	 channel_close_fd(int *);
-void	 channel_send_window_changes(void);
+Channel	*channel_by_id(struct ssh *, int);
+Channel	*channel_by_remote_id(struct ssh *, int);
+Channel	*channel_lookup(struct ssh *, int);
+Channel *channel_new(struct ssh *, char *, int, int, int, int,
+	    u_int, u_int, int, char *, int);
+void	 channel_set_fds(struct ssh *, int, int, int, int, int,
+	    int, int, u_int);
+void	 channel_free(struct ssh *, Channel *);
+void	 channel_free_all(struct ssh *);
+void	 channel_stop_listening(struct ssh *);
+
+void	 channel_send_open(struct ssh *, int);
+void	 channel_request_start(struct ssh *, int, char *, int);
+void	 channel_register_cleanup(struct ssh *, int,
+	    channel_callback_fn *, int);
+void	 channel_register_open_confirm(struct ssh *, int,
+	    channel_open_fn *, void *);
+void	 channel_register_filter(struct ssh *, int, channel_infilter_fn *,
+	    channel_outfilter_fn *, channel_filter_cleanup_fn *, void *);
+void	 channel_register_status_confirm(struct ssh *, int,
+	    channel_confirm_cb *, channel_confirm_abandon_cb *, void *);
+void	 channel_cancel_cleanup(struct ssh *, int);
+int	 channel_close_fd(struct ssh *, int *);
+void	 channel_send_window_changes(struct ssh *);
 
 /* mux proxy support */
 
-int	 channel_proxy_downstream(Channel *mc);
+int	 channel_proxy_downstream(struct ssh *, Channel *mc);
 int	 channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *);
 
 /* protocol handler */
@@ -252,63 +268,69 @@ int	 channel_input_status_confirm(int, u_int32_t, struct ssh *);
 void	 channel_prepare_select(struct ssh *, fd_set **, fd_set **, int *,
 	     u_int*, time_t*);
 void     channel_after_select(struct ssh *, fd_set *, fd_set *);
-void     channel_output_poll(void);
+void     channel_output_poll(struct ssh *);
 
-int      channel_not_very_much_buffered_data(void);
-void     channel_close_all(void);
-int      channel_still_open(void);
-char	*channel_open_message(void);
-int	 channel_find_open(void);
+int      channel_not_very_much_buffered_data(struct ssh *);
+void     channel_close_all(struct ssh *);
+int      channel_still_open(struct ssh *);
+char	*channel_open_message(struct ssh *);
+int	 channel_find_open(struct ssh *);
 
 /* tcp forwarding */
 struct Forward;
 struct ForwardOptions;
-void	 channel_set_af(int af);
-void     channel_permit_all_opens(void);
-void	 channel_add_permitted_opens(char *, int);
-int	 channel_add_adm_permitted_opens(char *, int);
-void	 channel_disable_adm_local_opens(void);
-void	 channel_update_permitted_opens(int, int);
-void	 channel_clear_permitted_opens(void);
-void	 channel_clear_adm_permitted_opens(void);
-void 	 channel_print_adm_permitted_opens(void);
-Channel	*channel_connect_to_port(const char *, u_short, char *, char *, int *,
-	     const char **);
-Channel *channel_connect_to_path(const char *, char *, char *);
-Channel	*channel_connect_stdio_fwd(const char*, u_short, int, int);
-Channel	*channel_connect_by_listen_address(const char *, u_short,
-	     char *, char *);
-Channel	*channel_connect_by_listen_path(const char *, char *, char *);
-int	 channel_request_remote_forwarding(struct Forward *);
-int	 channel_setup_local_fwd_listener(struct Forward *, struct ForwardOptions *);
-int	 channel_request_rforward_cancel(struct Forward *);
-int	 channel_setup_remote_fwd_listener(struct Forward *, int *, struct ForwardOptions *);
-int	 channel_cancel_rport_listener(struct Forward *);
-int	 channel_cancel_lport_listener(struct Forward *, int, struct ForwardOptions *);
+void	 channel_set_af(struct ssh *, int af);
+void     channel_permit_all_opens(struct ssh *);
+void	 channel_add_permitted_opens(struct ssh *, char *, int);
+int	 channel_add_adm_permitted_opens(struct ssh *, char *, int);
+void	 channel_copy_adm_permitted_opens(struct ssh *,
+	    const struct fwd_perm_list *);
+void	 channel_disable_adm_local_opens(struct ssh *);
+void	 channel_update_permitted_opens(struct ssh *, int, int);
+void	 channel_clear_permitted_opens(struct ssh *);
+void	 channel_clear_adm_permitted_opens(struct ssh *);
+void 	 channel_print_adm_permitted_opens(struct ssh *);
+Channel	*channel_connect_to_port(struct ssh *, const char *, u_short,
+	    char *, char *, int *, const char **);
+Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *);
+Channel	*channel_connect_stdio_fwd(struct ssh *, const char*,
+	    u_short, int, int);
+Channel	*channel_connect_by_listen_address(struct ssh *, const char *,
+	    u_short, char *, char *);
+Channel	*channel_connect_by_listen_path(struct ssh *, const char *,
+	    char *, char *);
+int	 channel_request_remote_forwarding(struct ssh *, struct Forward *);
+int	 channel_setup_local_fwd_listener(struct ssh *, struct Forward *,
+	    struct ForwardOptions *);
+int	 channel_request_rforward_cancel(struct ssh *, struct Forward *);
+int	 channel_setup_remote_fwd_listener(struct ssh *, struct Forward *,
+	    int *, struct ForwardOptions *);
+int	 channel_cancel_rport_listener(struct ssh *, struct Forward *);
+int	 channel_cancel_lport_listener(struct ssh *, struct Forward *,
+	    int, struct ForwardOptions *);
 int	 permitopen_port(const char *);
 
 /* x11 forwarding */
 
-void	 channel_set_x11_refuse_time(u_int);
-int	 x11_connect_display(void);
-int	 x11_create_display_inet(int, int, int, u_int *, int **);
-void	 x11_request_forwarding_with_spoofing(int, const char *, const char *,
-	     const char *, int);
+void	 channel_set_x11_refuse_time(struct ssh *, u_int);
+int	 x11_connect_display(struct ssh *);
+int	 x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **);
+void	 x11_request_forwarding_with_spoofing(struct ssh *, int,
+	    const char *, const char *, const char *, int);
 
 /* channel close */
 
-int	 chan_is_dead(Channel *, int);
-void	 chan_mark_dead(Channel *);
+int	 chan_is_dead(struct ssh *, Channel *, int);
+void	 chan_mark_dead(struct ssh *, Channel *);
 
 /* channel events */
 
-void	 chan_rcvd_oclose(Channel *);
-void	 chan_rcvd_eow(Channel *);	/* SSH2-only */
-void	 chan_read_failed(Channel *);
-void	 chan_ibuf_empty(Channel *);
-
-void	 chan_rcvd_ieof(Channel *);
-void	 chan_write_failed(Channel *);
-void	 chan_obuf_empty(Channel *);
+void	 chan_rcvd_oclose(struct ssh *, Channel *);
+void	 chan_rcvd_eow(struct ssh *, Channel *);
+void	 chan_read_failed(struct ssh *, Channel *);
+void	 chan_ibuf_empty(struct ssh *, Channel *);
+void	 chan_rcvd_ieof(struct ssh *, Channel *);
+void	 chan_write_failed(struct ssh *, Channel *);
+void	 chan_obuf_empty(struct ssh *, Channel *);
 
 #endif
diff --git a/clientloop.c b/clientloop.c
index 2934c4763..1218b3b71 100644
--- a/clientloop.c
+++ b/clientloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.c,v 1.302 2017/08/30 03:59:08 djm Exp $ */
+/* $OpenBSD: clientloop.c,v 1.303 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -177,6 +177,7 @@ struct channel_reply_ctx {
 };
 
 /* Global request success/failure callbacks */
+/* XXX move to struct ssh? */
 struct global_confirm {
 	TAILQ_ENTRY(global_confirm) entry;
 	global_confirm_cb *cb;
@@ -244,13 +245,13 @@ get_current_time(void)
  * control master process, or if there is no ControlPersist timeout.
  */
 static void
-set_control_persist_exit_time(void)
+set_control_persist_exit_time(struct ssh *ssh)
 {
 	if (muxserver_sock == -1 || !options.control_persist
 	    || options.control_persist_timeout == 0) {
 		/* not using a ControlPersist timeout */
 		control_persist_exit_time = 0;
-	} else if (channel_still_open()) {
+	} else if (channel_still_open(ssh)) {
 		/* some client connections are still open */
 		if (control_persist_exit_time > 0)
 			debug2("%s: cancel scheduled exit", __func__);
@@ -288,8 +289,9 @@ client_x11_display_valid(const char *display)
 #define SSH_X11_PROTO		"MIT-MAGIC-COOKIE-1"
 #define X11_TIMEOUT_SLACK	60
 int
-client_x11_get_proto(const char *display, const char *xauth_path,
-    u_int trusted, u_int timeout, char **_proto, char **_data)
+client_x11_get_proto(struct ssh *ssh, const char *display,
+    const char *xauth_path, u_int trusted, u_int timeout,
+    char **_proto, char **_data)
 {
 	char cmd[1024], line[512], xdisplay[512];
 	char xauthfile[PATH_MAX], xauthdir[PATH_MAX];
@@ -373,7 +375,8 @@ client_x11_get_proto(const char *display, const char *xauth_path,
 					x11_refuse_time = UINT_MAX;
 				else
 					x11_refuse_time = now + timeout;
-				channel_set_x11_refuse_time(x11_refuse_time);
+				channel_set_x11_refuse_time(ssh,
+				    x11_refuse_time);
 			}
 			if (system(cmd) == 0)
 				generated = 1;
@@ -446,7 +449,7 @@ client_x11_get_proto(const char *display, const char *xauth_path,
  */
 
 static void
-client_check_window_change(void)
+client_check_window_change(struct ssh *ssh)
 {
 	if (!received_window_change_signal)
 		return;
@@ -455,7 +458,7 @@ client_check_window_change(void)
 
 	debug2("%s: changed", __func__);
 
-	channel_send_window_changes();
+	channel_send_window_changes(ssh);
 }
 
 static int
@@ -466,7 +469,7 @@ client_global_request_reply(int type, u_int32_t seq, struct ssh *ssh)
 	if ((gc = TAILQ_FIRST(&global_confirms)) == NULL)
 		return 0;
 	if (gc->cb != NULL)
-		gc->cb(type, seq, gc->ctx);
+		gc->cb(ssh, type, seq, gc->ctx);
 	if (--gc->ref_count <= 0) {
 		TAILQ_REMOVE(&global_confirms, gc, entry);
 		explicit_bzero(gc, sizeof(*gc));
@@ -497,7 +500,8 @@ server_alive_check(void)
  * one of the file descriptors).
  */
 static void
-client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
+client_wait_until_can_do_something(struct ssh *ssh,
+    fd_set **readsetp, fd_set **writesetp,
     int *maxfdp, u_int *nallocp, int rekeying)
 {
 	struct timeval tv, *tvp;
@@ -510,7 +514,7 @@ client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
 	    nallocp, &minwait_secs);
 
 	/* channel_prepare_select could have closed the last channel */
-	if (session_closed && !channel_still_open() &&
+	if (session_closed && !channel_still_open(ssh) &&
 	    !packet_have_data_to_write()) {
 		/* clear mask since we did not call select() */
 		memset(*readsetp, 0, *nallocp);
@@ -537,7 +541,7 @@ client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
 	}
 	if (options.rekey_interval > 0 && !rekeying)
 		timeout_secs = MINIMUM(timeout_secs, packet_get_rekey_timeout());
-	set_control_persist_exit_time();
+	set_control_persist_exit_time(ssh);
 	if (control_persist_exit_time > 0) {
 		timeout_secs = MINIMUM(timeout_secs,
 			control_persist_exit_time - now);
@@ -668,7 +672,7 @@ client_process_net_input(fd_set *readset)
 }
 
 static void
-client_status_confirm(int type, Channel *c, void *ctx)
+client_status_confirm(struct ssh *ssh, int type, Channel *c, void *ctx)
 {
 	struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx;
 	char errmsg[256];
@@ -707,8 +711,7 @@ client_status_confirm(int type, Channel *c, void *ctx)
 		 * their stderr.
 		 */
 		if (tochan) {
-			buffer_append(&c->extended, errmsg,
-			    strlen(errmsg));
+			buffer_append(c->extended, errmsg, strlen(errmsg));
 		} else
 			error("%s", errmsg);
 		if (cr->action == CONFIRM_TTY) {
@@ -719,23 +722,23 @@ client_status_confirm(int type, Channel *c, void *ctx)
 			if (c->self == session_ident)
 				leave_raw_mode(0);
 			else
-				mux_tty_alloc_failed(c);
+				mux_tty_alloc_failed(ssh, c);
 		} else if (cr->action == CONFIRM_CLOSE) {
-			chan_read_failed(c);
-			chan_write_failed(c);
+			chan_read_failed(ssh, c);
+			chan_write_failed(ssh, c);
 		}
 	}
 	free(cr);
 }
 
 static void
-client_abandon_status_confirm(Channel *c, void *ctx)
+client_abandon_status_confirm(struct ssh *ssh, Channel *c, void *ctx)
 {
 	free(ctx);
 }
 
 void
-client_expect_confirm(int id, const char *request,
+client_expect_confirm(struct ssh *ssh, int id, const char *request,
     enum confirm_action action)
 {
 	struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr));
@@ -743,7 +746,7 @@ client_expect_confirm(int id, const char *request,
 	cr->request_type = request;
 	cr->action = action;
 
-	channel_register_status_confirm(id, client_status_confirm,
+	channel_register_status_confirm(ssh, id, client_status_confirm,
 	    client_abandon_status_confirm, cr);
 }
 
@@ -769,7 +772,7 @@ client_register_global_confirm(global_confirm_cb *cb, void *ctx)
 }
 
 static void
-process_cmdline(void)
+process_cmdline(struct ssh *ssh)
 {
 	void (*handler)(int);
 	char *s, *cmd;
@@ -843,12 +846,12 @@ process_cmdline(void)
 			goto out;
 		}
 		if (remote)
-			ok = channel_request_rforward_cancel(&fwd) == 0;
+			ok = channel_request_rforward_cancel(ssh, &fwd) == 0;
 		else if (dynamic)
-			ok = channel_cancel_lport_listener(&fwd,
+			ok = channel_cancel_lport_listener(ssh, &fwd,
 			    0, &options.fwd_opts) > 0;
 		else
-			ok = channel_cancel_lport_listener(&fwd,
+			ok = channel_cancel_lport_listener(ssh, &fwd,
 			    CHANNEL_CANCEL_PORT_STATIC,
 			    &options.fwd_opts) > 0;
 		if (!ok) {
@@ -862,13 +865,13 @@ process_cmdline(void)
 			goto out;
 		}
 		if (local || dynamic) {
-			if (!channel_setup_local_fwd_listener(&fwd,
+			if (!channel_setup_local_fwd_listener(ssh, &fwd,
 			    &options.fwd_opts)) {
 				logit("Port forwarding failed.");
 				goto out;
 			}
 		} else {
-			if (channel_request_remote_forwarding(&fwd) < 0) {
+			if (channel_request_remote_forwarding(ssh, &fwd) < 0) {
 				logit("Port forwarding failed.");
 				goto out;
 			}
@@ -945,7 +948,8 @@ print_escape_help(Buffer *b, int escape_char, int mux_client, int using_stderr)
  * Process the characters one by one.
  */
 static int
-process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
+process_escapes(struct ssh *ssh, Channel *c,
+    Buffer *bin, Buffer *bout, Buffer *berr,
     char *buf, int len)
 {
 	char string[1024];
@@ -981,13 +985,15 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
 				buffer_append(berr, string, strlen(string));
 
 				if (c && c->ctl_chan != -1) {
-					chan_read_failed(c);
-					chan_write_failed(c);
-					if (c->detach_user)
-						c->detach_user(c->self, NULL);
+					chan_read_failed(ssh, c);
+					chan_write_failed(ssh, c);
+					if (c->detach_user) {
+						c->detach_user(ssh,
+						    c->self, NULL);
+					}
 					c->type = SSH_CHANNEL_ABANDONED;
-					buffer_clear(&c->input);
-					chan_ibuf_empty(c);
+					buffer_clear(c->input);
+					chan_ibuf_empty(ssh, c);
 					return 0;
 				} else
 					quit_pending = 1;
@@ -1025,7 +1031,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
 				snprintf(string, sizeof string,
 				    "%cB\r\n", efc->escape_char);
 				buffer_append(berr, string, strlen(string));
-				channel_request_start(c->self, "break", 0);
+				channel_request_start(ssh, c->self, "break", 0);
 				packet_put_int(1000);
 				packet_send();
 				continue;
@@ -1077,7 +1083,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
 				    options.request_tty == REQUEST_TTY_FORCE);
 
 				/* Stop listening for new connections. */
-				channel_stop_listening();
+				channel_stop_listening(ssh);
 
 				snprintf(string, sizeof string,
 				    "%c& [backgrounded]\n", efc->escape_char);
@@ -1107,7 +1113,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
 				snprintf(string, sizeof string, "%c#\r\n",
 				    efc->escape_char);
 				buffer_append(berr, string, strlen(string));
-				s = channel_open_message();
+				s = channel_open_message(ssh);
 				buffer_append(berr, s, strlen(s));
 				free(s);
 				continue;
@@ -1115,7 +1121,7 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
 			case 'C':
 				if (c && c->ctl_chan != -1)
 					goto noescape;
-				process_cmdline();
+				process_cmdline(ssh);
 				continue;
 
 			default:
@@ -1186,25 +1192,25 @@ client_new_escape_filter_ctx(int escape_char)
 
 /* Free the escape filter context on channel free */
 void
-client_filter_cleanup(int cid, void *ctx)
+client_filter_cleanup(struct ssh *ssh, int cid, void *ctx)
 {
 	free(ctx);
 }
 
 int
-client_simple_escape_filter(Channel *c, char *buf, int len)
+client_simple_escape_filter(struct ssh *ssh, Channel *c, char *buf, int len)
 {
 	if (c->extended_usage != CHAN_EXTENDED_WRITE)
 		return 0;
 
-	return process_escapes(c, &c->input, &c->output, &c->extended,
+	return process_escapes(ssh, c, c->input, c->output, c->extended,
 	    buf, len);
 }
 
 static void
-client_channel_closed(int id, void *arg)
+client_channel_closed(struct ssh *ssh, int id, void *arg)
 {
-	channel_cancel_cleanup(id);
+	channel_cancel_cleanup(ssh, id);
 	session_closed = 1;
 	leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
 }
@@ -1215,9 +1221,9 @@ client_channel_closed(int id, void *arg)
  * remote host.  If escape_char != SSH_ESCAPECHAR_NONE, it is the character
  * used as an escape character for terminating or suspending the session.
  */
-
 int
-client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
+client_loop(struct ssh *ssh, int have_pty, int escape_char_arg,
+    int ssh2_chan_id)
 {
 	fd_set *readset = NULL, *writeset = NULL;
 	double start_time, total_time;
@@ -1295,13 +1301,13 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 	session_ident = ssh2_chan_id;
 	if (session_ident != -1) {
 		if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
-			channel_register_filter(session_ident,
+			channel_register_filter(ssh, session_ident,
 			    client_simple_escape_filter, NULL,
 			    client_filter_cleanup,
 			    client_new_escape_filter_ctx(
 			    escape_char_arg));
 		}
-		channel_register_cleanup(session_ident,
+		channel_register_cleanup(ssh, session_ident,
 		    client_channel_closed, 0);
 	}
 
@@ -1311,15 +1317,15 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 		/* Process buffered packets sent by the server. */
 		client_process_buffered_input_packets();
 
-		if (session_closed && !channel_still_open())
+		if (session_closed && !channel_still_open(ssh))
 			break;
 
-		if (ssh_packet_is_rekeying(active_state)) {
+		if (ssh_packet_is_rekeying(ssh)) {
 			debug("rekeying in progress");
 		} else if (need_rekeying) {
 			/* manual rekey request */
 			debug("need rekeying");
-			if ((r = kex_start_rekex(active_state)) != 0)
+			if ((r = kex_start_rekex(ssh)) != 0)
 				fatal("%s: kex_start_rekex: %s", __func__,
 				    ssh_err(r));
 			need_rekeying = 0;
@@ -1329,13 +1335,13 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 			 * enqueue them for sending to the server.
 			 */
 			if (packet_not_very_much_data_to_write())
-				channel_output_poll();
+				channel_output_poll(ssh);
 
 			/*
 			 * Check if the window size has changed, and buffer a
 			 * message about it to the server if so.
 			 */
-			client_check_window_change();
+			client_check_window_change(ssh);
 
 			if (quit_pending)
 				break;
@@ -1345,15 +1351,15 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 		 * available on one of the descriptors).
 		 */
 		max_fd2 = max_fd;
-		client_wait_until_can_do_something(&readset, &writeset,
-		    &max_fd2, &nalloc, ssh_packet_is_rekeying(active_state));
+		client_wait_until_can_do_something(ssh, &readset, &writeset,
+		    &max_fd2, &nalloc, ssh_packet_is_rekeying(ssh));
 
 		if (quit_pending)
 			break;
 
 		/* Do channel operations unless rekeying in progress. */
-		if (!ssh_packet_is_rekeying(active_state))
-			channel_after_select(active_state, readset, writeset);
+		if (!ssh_packet_is_rekeying(ssh))
+			channel_after_select(ssh, readset, writeset);
 
 		/* Buffer input from the connection.  */
 		client_process_net_input(readset);
@@ -1395,7 +1401,7 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 	packet_send();
 	packet_write_wait();
 
-	channel_free_all();
+	channel_free_all(ssh);
 
 	if (have_pty)
 		leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
@@ -1463,8 +1469,8 @@ client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
 /*********/
 
 static Channel *
-client_request_forwarded_tcpip(const char *request_type, int rchan,
-    u_int rwindow, u_int rmaxpack)
+client_request_forwarded_tcpip(struct ssh *ssh, const char *request_type,
+    int rchan, u_int rwindow, u_int rmaxpack)
 {
 	Channel *c = NULL;
 	struct sshbuf *b = NULL;
@@ -1482,7 +1488,7 @@ client_request_forwarded_tcpip(const char *request_type, int rchan,
 	debug("%s: listen %s port %d, originator %s port %d", __func__,
 	    listen_address, listen_port, originator_address, originator_port);
 
-	c = channel_connect_by_listen_address(listen_address, listen_port,
+	c = channel_connect_by_listen_address(ssh, listen_address, listen_port,
 	    "forwarded-tcpip", originator_address);
 
 	if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
@@ -1501,7 +1507,7 @@ client_request_forwarded_tcpip(const char *request_type, int rchan,
 		    (r = sshbuf_put_u32(b, listen_port)) != 0 ||
 		    (r = sshbuf_put_cstring(b, originator_address)) != 0 ||
 		    (r = sshbuf_put_u32(b, originator_port)) != 0 ||
-		    (r = sshbuf_put_stringb(&c->output, b)) != 0) {
+		    (r = sshbuf_put_stringb(c->output, b)) != 0) {
 			error("%s: compose for muxclient %s", __func__,
 			    ssh_err(r));
 			goto out;
@@ -1516,7 +1522,8 @@ client_request_forwarded_tcpip(const char *request_type, int rchan,
 }
 
 static Channel *
-client_request_forwarded_streamlocal(const char *request_type, int rchan)
+client_request_forwarded_streamlocal(struct ssh *ssh,
+    const char *request_type, int rchan)
 {
 	Channel *c = NULL;
 	char *listen_path;
@@ -1530,14 +1537,14 @@ client_request_forwarded_streamlocal(const char *request_type, int rchan)
 
 	debug("%s: %s", __func__, listen_path);
 
-	c = channel_connect_by_listen_path(listen_path,
+	c = channel_connect_by_listen_path(ssh, listen_path,
 	    "forwarded-streamlocal@openssh.com", "forwarded-streamlocal");
 	free(listen_path);
 	return c;
 }
 
 static Channel *
-client_request_x11(const char *request_type, int rchan)
+client_request_x11(struct ssh *ssh, const char *request_type, int rchan)
 {
 	Channel *c = NULL;
 	char *originator;
@@ -1567,10 +1574,10 @@ client_request_x11(const char *request_type, int rchan)
 	debug("client_request_x11: request from %s %d", originator,
 	    originator_port);
 	free(originator);
-	sock = x11_connect_display();
+	sock = x11_connect_display(ssh);
 	if (sock < 0)
 		return NULL;
-	c = channel_new("x11",
+	c = channel_new(ssh, "x11",
 	    SSH_CHANNEL_X11_OPEN, sock, sock, -1,
 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
 	c->force_drain = 1;
@@ -1578,7 +1585,7 @@ client_request_x11(const char *request_type, int rchan)
 }
 
 static Channel *
-client_request_agent(const char *request_type, int rchan)
+client_request_agent(struct ssh *ssh, const char *request_type, int rchan)
 {
 	Channel *c = NULL;
 	int r, sock;
@@ -1595,7 +1602,7 @@ client_request_agent(const char *request_type, int rchan)
 			    __func__, ssh_err(r));
 		return NULL;
 	}
-	c = channel_new("authentication agent connection",
+	c = channel_new(ssh, "authentication agent connection",
 	    SSH_CHANNEL_OPEN, sock, sock, -1,
 	    CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0,
 	    "authentication agent connection", 1);
@@ -1604,7 +1611,8 @@ client_request_agent(const char *request_type, int rchan)
 }
 
 int
-client_request_tun_fwd(int tun_mode, int local_tun, int remote_tun)
+client_request_tun_fwd(struct ssh *ssh, int tun_mode,
+    int local_tun, int remote_tun)
 {
 	Channel *c;
 	int fd;
@@ -1620,7 +1628,7 @@ client_request_tun_fwd(int tun_mode, int local_tun, int remote_tun)
 		return -1;
 	}
 
-	c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
+	c = channel_new(ssh, "tun", SSH_CHANNEL_OPENING, fd, fd, -1,
 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
 	c->datagram = 1;
 
@@ -1660,14 +1668,14 @@ client_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
 	    ctype, rchan, rwindow, rmaxpack);
 
 	if (strcmp(ctype, "forwarded-tcpip") == 0) {
-		c = client_request_forwarded_tcpip(ctype, rchan, rwindow,
+		c = client_request_forwarded_tcpip(ssh, ctype, rchan, rwindow,
 		    rmaxpack);
 	} else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
-		c = client_request_forwarded_streamlocal(ctype, rchan);
+		c = client_request_forwarded_streamlocal(ssh, ctype, rchan);
 	} else if (strcmp(ctype, "x11") == 0) {
-		c = client_request_x11(ctype, rchan);
+		c = client_request_x11(ssh, ctype, rchan);
 	} else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
-		c = client_request_agent(ctype, rchan);
+		c = client_request_agent(ssh, ctype, rchan);
 	}
 	if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
 		debug3("proxied to downstream: %s", ctype);
@@ -1707,7 +1715,7 @@ client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
 	char *rtype;
 
 	id = packet_get_int();
-	c = channel_lookup(id);
+	c = channel_lookup(ssh, id);
 	if (channel_proxy_upstream(c, type, seq, ssh))
 		return 0;
 	rtype = packet_get_string(NULL);
@@ -1723,11 +1731,11 @@ client_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
 		    "unknown channel", id);
 	} else if (strcmp(rtype, "eow@openssh.com") == 0) {
 		packet_check_eom();
-		chan_rcvd_eow(c);
+		chan_rcvd_eow(ssh, c);
 	} else if (strcmp(rtype, "exit-status") == 0) {
 		exitval = packet_get_int();
 		if (c->ctl_chan != -1) {
-			mux_exit_message(c, exitval);
+			mux_exit_message(ssh, c, exitval);
 			success = 1;
 		} else if (id == session_ident) {
 			/* Record exit value of local session */
@@ -1895,9 +1903,9 @@ update_known_hosts(struct hostkeys_update_ctx *ctx)
 }
 
 static void
-client_global_hostkeys_private_confirm(int type, u_int32_t seq, void *_ctx)
+client_global_hostkeys_private_confirm(struct ssh *ssh, int type,
+    u_int32_t seq, void *_ctx)
 {
-	struct ssh *ssh = active_state; /* XXX */
 	struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
 	size_t i, ndone;
 	struct sshbuf *signdata;
@@ -2161,7 +2169,7 @@ client_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
 }
 
 void
-client_session2_setup(int id, int want_tty, int want_subsystem,
+client_session2_setup(struct ssh *ssh, int id, int want_tty, int want_subsystem,
     const char *term, struct termios *tiop, int in_fd, Buffer *cmd, char **env)
 {
 	int len;
@@ -2169,8 +2177,8 @@ client_session2_setup(int id, int want_tty, int want_subsystem,
 
 	debug2("%s: id %d", __func__, id);
 
-	if ((c = channel_lookup(id)) == NULL)
-		fatal("client_session2_setup: channel %d: unknown channel", id);
+	if ((c = channel_lookup(ssh, id)) == NULL)
+		fatal("%s: channel %d: unknown channel", __func__, id);
 
 	packet_set_interactive(want_tty,
 	    options.ip_qos_interactive, options.ip_qos_bulk);
@@ -2182,8 +2190,8 @@ client_session2_setup(int id, int want_tty, int want_subsystem,
 		if (ioctl(in_fd, TIOCGWINSZ, &ws) < 0)
 			memset(&ws, 0, sizeof(ws));
 
-		channel_request_start(id, "pty-req", 1);
-		client_expect_confirm(id, "PTY allocation", CONFIRM_TTY);
+		channel_request_start(ssh, id, "pty-req", 1);
+		client_expect_confirm(ssh, id, "PTY allocation", CONFIRM_TTY);
 		packet_put_cstring(term != NULL ? term : "");
 		packet_put_int((u_int)ws.ws_col);
 		packet_put_int((u_int)ws.ws_row);
@@ -2226,7 +2234,7 @@ client_session2_setup(int id, int want_tty, int want_subsystem,
 			}
 
 			debug("Sending env %s = %s", name, val);
-			channel_request_start(id, "env", 0);
+			channel_request_start(ssh, id, "env", 0);
 			packet_put_cstring(name);
 			packet_put_cstring(val);
 			packet_send();
@@ -2241,19 +2249,20 @@ client_session2_setup(int id, int want_tty, int want_subsystem,
 		if (want_subsystem) {
 			debug("Sending subsystem: %.*s",
 			    len, (u_char*)buffer_ptr(cmd));
-			channel_request_start(id, "subsystem", 1);
-			client_expect_confirm(id, "subsystem", CONFIRM_CLOSE);
+			channel_request_start(ssh, id, "subsystem", 1);
+			client_expect_confirm(ssh, id, "subsystem",
+			    CONFIRM_CLOSE);
 		} else {
 			debug("Sending command: %.*s",
 			    len, (u_char*)buffer_ptr(cmd));
-			channel_request_start(id, "exec", 1);
-			client_expect_confirm(id, "exec", CONFIRM_CLOSE);
+			channel_request_start(ssh, id, "exec", 1);
+			client_expect_confirm(ssh, id, "exec", CONFIRM_CLOSE);
 		}
 		packet_put_string(buffer_ptr(cmd), buffer_len(cmd));
 		packet_send();
 	} else {
-		channel_request_start(id, "shell", 1);
-		client_expect_confirm(id, "shell", CONFIRM_CLOSE);
+		channel_request_start(ssh, id, "shell", 1);
+		client_expect_confirm(ssh, id, "shell", CONFIRM_CLOSE);
 		packet_send();
 	}
 }
diff --git a/clientloop.h b/clientloop.h
index ae83aa8cf..a1975ccc8 100644
--- a/clientloop.h
+++ b/clientloop.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: clientloop.h,v 1.33 2016/09/30 09:19:13 markus Exp $ */
+/* $OpenBSD: clientloop.h,v 1.34 2017/09/12 06:32:07 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -37,28 +37,31 @@
 
 #include <termios.h>
 
+struct ssh;
+
 /* Client side main loop for the interactive session. */
-int	 client_loop(int, int, int);
-int	 client_x11_get_proto(const char *, const char *, u_int, u_int,
-	    char **, char **);
+int	 client_loop(struct ssh *, int, int, int);
+int	 client_x11_get_proto(struct ssh *, const char *, const char *,
+	    u_int, u_int, char **, char **);
 void	 client_global_request_reply_fwd(int, u_int32_t, void *);
-void	 client_session2_setup(int, int, int, const char *, struct termios *,
-	    int, Buffer *, char **);
-int	 client_request_tun_fwd(int, int, int);
+void	 client_session2_setup(struct ssh *, int, int, int,
+	    const char *, struct termios *, int, Buffer *, char **);
+int	 client_request_tun_fwd(struct ssh *, int, int, int);
 void	 client_stop_mux(void);
 
 /* Escape filter for protocol 2 sessions */
 void	*client_new_escape_filter_ctx(int);
-void	 client_filter_cleanup(int, void *);
-int	 client_simple_escape_filter(Channel *, char *, int);
+void	 client_filter_cleanup(struct ssh *, int, void *);
+int	 client_simple_escape_filter(struct ssh *, Channel *, char *, int);
 
 /* Global request confirmation callbacks */
-typedef void global_confirm_cb(int, u_int32_t seq, void *);
+typedef void global_confirm_cb(struct ssh *, int, u_int32_t, void *);
 void	 client_register_global_confirm(global_confirm_cb *, void *);
 
 /* Channel request confirmation callbacks */
 enum confirm_action { CONFIRM_WARN = 0, CONFIRM_CLOSE, CONFIRM_TTY };
-void client_expect_confirm(int, const char *, enum confirm_action);
+void client_expect_confirm(struct ssh *, int, const char *,
+    enum confirm_action);
 
 /* Multiplexing protocol version */
 #define SSHMUX_VER			4
@@ -73,8 +76,8 @@ void client_expect_confirm(int, const char *, enum confirm_action);
 #define SSHMUX_COMMAND_CANCEL_FWD	7	/* Cancel forwarding(s) */
 #define SSHMUX_COMMAND_PROXY		8	/* Open new connection */
 
-void	muxserver_listen(void);
+void	muxserver_listen(struct ssh *);
 int	muxclient(const char *);
-void	mux_exit_message(Channel *, int);
-void	mux_tty_alloc_failed(Channel *);
+void	mux_exit_message(struct ssh *, Channel *, int);
+void	mux_tty_alloc_failed(struct ssh *ssh, Channel *);
 
diff --git a/monitor.c b/monitor.c
index 8a7897bde..bdb4e8552 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.172 2017/06/24 06:34:38 djm Exp $ */
+/* $OpenBSD: monitor.c,v 1.173 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -1519,13 +1519,14 @@ mm_answer_pty_cleanup(int sock, Buffer *m)
 int
 mm_answer_term(int sock, Buffer *req)
 {
+	struct ssh *ssh = active_state;	/* XXX */
 	extern struct monitor *pmonitor;
 	int res, status;
 
 	debug3("%s: tearing down sessions", __func__);
 
 	/* The child is terminating */
-	session_destroy_all(&mm_session_close);
+	session_destroy_all(ssh, &mm_session_close);
 
 #ifdef USE_PAM
 	if (options.use_pam)
diff --git a/monitor_wrap.c b/monitor_wrap.c
index 25f3e9678..287af0667 100644
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.92 2017/05/30 14:10:53 markus Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.93 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -242,6 +242,7 @@ mm_key_sign(struct sshkey *key, u_char **sigp, u_int *lenp,
 struct passwd *
 mm_getpwnamallow(const char *username)
 {
+	struct ssh *ssh = active_state;		/* XXX */
 	Buffer m;
 	struct passwd *pw;
 	u_int len, i;
@@ -296,6 +297,7 @@ out:
 
 	copy_set_server_options(&options, newopts, 1);
 	log_change_level(options.log_level);
+	process_permitopen(ssh, &options);
 	free(newopts);
 
 	buffer_free(&m);
diff --git a/mux.c b/mux.c
index 3dde4da40..9eee287b9 100644
--- a/mux.c
+++ b/mux.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mux.c,v 1.65 2017/06/09 06:47:13 djm Exp $ */
+/* $OpenBSD: mux.c,v 1.66 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
  *
@@ -161,22 +161,32 @@ struct mux_master_state {
 #define MUX_FWD_REMOTE  2
 #define MUX_FWD_DYNAMIC 3
 
-static void mux_session_confirm(int, int, void *);
-static void mux_stdio_confirm(int, int, void *);
-
-static int process_mux_master_hello(u_int, Channel *, Buffer *, Buffer *);
-static int process_mux_new_session(u_int, Channel *, Buffer *, Buffer *);
-static int process_mux_alive_check(u_int, Channel *, Buffer *, Buffer *);
-static int process_mux_terminate(u_int, Channel *, Buffer *, Buffer *);
-static int process_mux_open_fwd(u_int, Channel *, Buffer *, Buffer *);
-static int process_mux_close_fwd(u_int, Channel *, Buffer *, Buffer *);
-static int process_mux_stdio_fwd(u_int, Channel *, Buffer *, Buffer *);
-static int process_mux_stop_listening(u_int, Channel *, Buffer *, Buffer *);
-static int process_mux_proxy(u_int, Channel *, Buffer *, Buffer *);
+static void mux_session_confirm(struct ssh *, int, int, void *);
+static void mux_stdio_confirm(struct ssh *, int, int, void *);
+
+static int process_mux_master_hello(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
+static int process_mux_new_session(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
+static int process_mux_alive_check(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
+static int process_mux_terminate(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
+static int process_mux_open_fwd(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
+static int process_mux_close_fwd(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
+static int process_mux_stdio_fwd(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
+static int process_mux_stop_listening(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
+static int process_mux_proxy(struct ssh *, u_int,
+	    Channel *, struct sshbuf *, struct sshbuf *);
 
 static const struct {
 	u_int type;
-	int (*handler)(u_int, Channel *, Buffer *, Buffer *);
+	int (*handler)(struct ssh *, u_int, Channel *,
+	    struct sshbuf *, struct sshbuf *);
 } mux_master_handlers[] = {
 	{ MUX_MSG_HELLO, process_mux_master_hello },
 	{ MUX_C_NEW_SESSION, process_mux_new_session },
@@ -193,36 +203,36 @@ static const struct {
 /* Cleanup callback fired on closure of mux slave _session_ channel */
 /* ARGSUSED */
 static void
-mux_master_session_cleanup_cb(int cid, void *unused)
+mux_master_session_cleanup_cb(struct ssh *ssh, int cid, void *unused)
 {
-	Channel *cc, *c = channel_by_id(cid);
+	Channel *cc, *c = channel_by_id(ssh, cid);
 
 	debug3("%s: entering for channel %d", __func__, cid);
 	if (c == NULL)
 		fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
 	if (c->ctl_chan != -1) {
-		if ((cc = channel_by_id(c->ctl_chan)) == NULL)
+		if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
 			fatal("%s: channel %d missing control channel %d",
 			    __func__, c->self, c->ctl_chan);
 		c->ctl_chan = -1;
 		cc->remote_id = -1;
-		chan_rcvd_oclose(cc);
+		chan_rcvd_oclose(ssh, cc);
 	}
-	channel_cancel_cleanup(c->self);
+	channel_cancel_cleanup(ssh, c->self);
 }
 
 /* Cleanup callback fired on closure of mux slave _control_ channel */
 /* ARGSUSED */
 static void
-mux_master_control_cleanup_cb(int cid, void *unused)
+mux_master_control_cleanup_cb(struct ssh *ssh, int cid, void *unused)
 {
-	Channel *sc, *c = channel_by_id(cid);
+	Channel *sc, *c = channel_by_id(ssh, cid);
 
 	debug3("%s: entering for channel %d", __func__, cid);
 	if (c == NULL)
 		fatal("%s: channel_by_id(%i) == NULL", __func__, cid);
 	if (c->remote_id != -1) {
-		if ((sc = channel_by_id(c->remote_id)) == NULL)
+		if ((sc = channel_by_id(ssh, c->remote_id)) == NULL)
 			fatal("%s: channel %d missing session channel %d",
 			    __func__, c->self, c->remote_id);
 		c->remote_id = -1;
@@ -230,15 +240,15 @@ mux_master_control_cleanup_cb(int cid, void *unused)
 		if (sc->type != SSH_CHANNEL_OPEN &&
 		    sc->type != SSH_CHANNEL_OPENING) {
 			debug2("%s: channel %d: not open", __func__, sc->self);
-			chan_mark_dead(sc);
+			chan_mark_dead(ssh, sc);
 		} else {
 			if (sc->istate == CHAN_INPUT_OPEN)
-				chan_read_failed(sc);
+				chan_read_failed(ssh, sc);
 			if (sc->ostate == CHAN_OUTPUT_OPEN)
-				chan_write_failed(sc);
+				chan_write_failed(ssh, sc);
 		}
 	}
-	channel_cancel_cleanup(c->self);
+	channel_cancel_cleanup(ssh, c->self);
 }
 
 /* Check mux client environment variables before passing them to mux master. */
@@ -266,7 +276,8 @@ env_permitted(char *env)
 /* Mux master protocol message handlers */
 
 static int
-process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_master_hello(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	u_int ver;
 	struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
@@ -308,7 +319,8 @@ process_mux_master_hello(u_int rid, Channel *c, Buffer *m, Buffer *r)
 }
 
 static int
-process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_new_session(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	Channel *nc;
 	struct mux_session_confirm_ctx *cctx;
@@ -453,7 +465,7 @@ process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
 		packetmax >>= 1;
 	}
 
-	nc = channel_new("session", SSH_CHANNEL_OPENING,
+	nc = channel_new(ssh, "session", SSH_CHANNEL_OPENING,
 	    new_fd[0], new_fd[1], new_fd[2], window, packetmax,
 	    CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);
 
@@ -461,7 +473,7 @@ process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
 	c->remote_id = nc->self; 	/* link control -> session channel */
 
 	if (cctx->want_tty && escape_char != 0xffffffff) {
-		channel_register_filter(nc->self,
+		channel_register_filter(ssh, nc->self,
 		    client_simple_escape_filter, NULL,
 		    client_filter_cleanup,
 		    client_new_escape_filter_ctx((int)escape_char));
@@ -470,17 +482,19 @@ process_mux_new_session(u_int rid, Channel *c, Buffer *m, Buffer *r)
 	debug2("%s: channel_new: %d linked to control channel %d",
 	    __func__, nc->self, nc->ctl_chan);
 
-	channel_send_open(nc->self);
-	channel_register_open_confirm(nc->self, mux_session_confirm, cctx);
+	channel_send_open(ssh, nc->self);
+	channel_register_open_confirm(ssh, nc->self, mux_session_confirm, cctx);
 	c->mux_pause = 1; /* stop handling messages until open_confirm done */
-	channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
+	channel_register_cleanup(ssh, nc->self,
+	    mux_master_session_cleanup_cb, 1);
 
 	/* reply is deferred, sent by mux_session_confirm */
 	return 0;
 }
 
 static int
-process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_alive_check(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	debug2("%s: channel %d: alive check", __func__, c->self);
 
@@ -493,7 +507,8 @@ process_mux_alive_check(u_int rid, Channel *c, Buffer *m, Buffer *r)
 }
 
 static int
-process_mux_terminate(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_terminate(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	debug2("%s: channel %d: terminate request", __func__, c->self);
 
@@ -582,7 +597,7 @@ compare_forward(struct Forward *a, struct Forward *b)
 }
 
 static void
-mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
+mux_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
 {
 	struct mux_channel_confirm_ctx *fctx = ctxt;
 	char *failmsg = NULL;
@@ -590,7 +605,7 @@ mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 	Channel *c;
 	Buffer out;
 
-	if ((c = channel_by_id(fctx->cid)) == NULL) {
+	if ((c = channel_by_id(ssh, fctx->cid)) == NULL) {
 		/* no channel for reply */
 		error("%s: unknown channel", __func__);
 		return;
@@ -616,7 +631,7 @@ mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 			buffer_put_int(&out, MUX_S_REMOTE_PORT);
 			buffer_put_int(&out, fctx->rid);
 			buffer_put_int(&out, rfwd->allocated_port);
-			channel_update_permitted_opens(rfwd->handle,
+			channel_update_permitted_opens(ssh, rfwd->handle,
 			   rfwd->allocated_port);
 		} else {
 			buffer_put_int(&out, MUX_S_OK);
@@ -625,7 +640,7 @@ mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 		goto out;
 	} else {
 		if (rfwd->listen_port == 0)
-			channel_update_permitted_opens(rfwd->handle, -1);
+			channel_update_permitted_opens(ssh, rfwd->handle, -1);
 		if (rfwd->listen_path != NULL)
 			xasprintf(&failmsg, "remote port forwarding failed for "
 			    "listen path %s", rfwd->listen_path);
@@ -651,7 +666,7 @@ mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 	buffer_put_cstring(&out, failmsg);
 	free(failmsg);
  out:
-	buffer_put_string(&c->output, buffer_ptr(&out), buffer_len(&out));
+	buffer_put_string(c->output, buffer_ptr(&out), buffer_len(&out));
 	buffer_free(&out);
 	if (c->mux_pause <= 0)
 		fatal("%s: mux_pause %d", __func__, c->mux_pause);
@@ -659,7 +674,8 @@ mux_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 }
 
 static int
-process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_open_fwd(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	struct Forward fwd;
 	char *fwd_desc = NULL;
@@ -727,13 +743,16 @@ process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 		    fwd.listen_port);
 		goto invalid;
 	}
-	if ((fwd.connect_port != PORT_STREAMLOCAL && fwd.connect_port >= 65536)
-	    || (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE && fwd.connect_port == 0)) {
+	if ((fwd.connect_port != PORT_STREAMLOCAL &&
+	    fwd.connect_port >= 65536) ||
+	    (ftype != MUX_FWD_DYNAMIC && ftype != MUX_FWD_REMOTE &&
+	    fwd.connect_port == 0)) {
 		logit("%s: invalid connect port %u", __func__,
 		    fwd.connect_port);
 		goto invalid;
 	}
-	if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL && fwd.connect_path == NULL) {
+	if (ftype != MUX_FWD_DYNAMIC && fwd.connect_host == NULL &&
+	    fwd.connect_path == NULL) {
 		logit("%s: missing connect host", __func__);
 		goto invalid;
 	}
@@ -784,7 +803,7 @@ process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 	}
 
 	if (ftype == MUX_FWD_LOCAL || ftype == MUX_FWD_DYNAMIC) {
-		if (!channel_setup_local_fwd_listener(&fwd,
+		if (!channel_setup_local_fwd_listener(ssh, &fwd,
 		    &options.fwd_opts)) {
  fail:
 			logit("slave-requested %s failed", fwd_desc);
@@ -798,7 +817,7 @@ process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 	} else {
 		struct mux_channel_confirm_ctx *fctx;
 
-		fwd.handle = channel_request_remote_forwarding(&fwd);
+		fwd.handle = channel_request_remote_forwarding(ssh, &fwd);
 		if (fwd.handle < 0)
 			goto fail;
 		add_remote_forward(&options, &fwd);
@@ -827,7 +846,8 @@ process_mux_open_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 }
 
 static int
-process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_close_fwd(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	struct Forward fwd, *found_fwd;
 	char *fwd_desc = NULL;
@@ -908,11 +928,11 @@ process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 		 * However, for dynamic allocated listen ports we need
 		 * to use the actual listen port.
 		 */
-		if (channel_request_rforward_cancel(found_fwd) == -1)
+		if (channel_request_rforward_cancel(ssh, found_fwd) == -1)
 			error_reason = "port not in permitted opens";
 	} else {	/* local and dynamic forwards */
 		/* Ditto */
-		if (channel_cancel_lport_listener(&fwd, fwd.connect_port,
+		if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port,
 		    &options.fwd_opts) == -1)
 			error_reason = "port not found";
 	}
@@ -942,7 +962,8 @@ process_mux_close_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 }
 
 static int
-process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_stdio_fwd(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	Channel *nc;
 	char *reserved, *chost;
@@ -1018,7 +1039,7 @@ process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 	if (!isatty(new_fd[1]))
 		set_nonblock(new_fd[1]);
 
-	nc = channel_connect_stdio_fwd(chost, cport, new_fd[0], new_fd[1]);
+	nc = channel_connect_stdio_fwd(ssh, chost, cport, new_fd[0], new_fd[1]);
 
 	nc->ctl_chan = c->self;		/* link session -> control channel */
 	c->remote_id = nc->self; 	/* link control -> session channel */
@@ -1026,11 +1047,12 @@ process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 	debug2("%s: channel_new: %d linked to control channel %d",
 	    __func__, nc->self, nc->ctl_chan);
 
-	channel_register_cleanup(nc->self, mux_master_session_cleanup_cb, 1);
+	channel_register_cleanup(ssh, nc->self,
+	    mux_master_session_cleanup_cb, 1);
 
 	cctx = xcalloc(1, sizeof(*cctx));
 	cctx->rid = rid;
-	channel_register_open_confirm(nc->self, mux_stdio_confirm, cctx);
+	channel_register_open_confirm(ssh, nc->self, mux_stdio_confirm, cctx);
 	c->mux_pause = 1; /* stop handling messages until open_confirm done */
 
 	/* reply is deferred, sent by mux_session_confirm */
@@ -1039,7 +1061,7 @@ process_mux_stdio_fwd(u_int rid, Channel *c, Buffer *m, Buffer *r)
 
 /* Callback on open confirmation in mux master for a mux stdio fwd session. */
 static void
-mux_stdio_confirm(int id, int success, void *arg)
+mux_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
 {
 	struct mux_stdio_confirm_ctx *cctx = arg;
 	Channel *c, *cc;
@@ -1047,9 +1069,9 @@ mux_stdio_confirm(int id, int success, void *arg)
 
 	if (cctx == NULL)
 		fatal("%s: cctx == NULL", __func__);
-	if ((c = channel_by_id(id)) == NULL)
+	if ((c = channel_by_id(ssh, id)) == NULL)
 		fatal("%s: no channel for id %d", __func__, id);
-	if ((cc = channel_by_id(c->ctl_chan)) == NULL)
+	if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
 		fatal("%s: channel %d lacks control channel %d", __func__,
 		    id, c->ctl_chan);
 
@@ -1072,7 +1094,7 @@ mux_stdio_confirm(int id, int success, void *arg)
 
  done:
 	/* Send reply */
-	buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply));
+	buffer_put_string(cc->output, buffer_ptr(&reply), buffer_len(&reply));
 	buffer_free(&reply);
 
 	if (cc->mux_pause <= 0)
@@ -1083,7 +1105,8 @@ mux_stdio_confirm(int id, int success, void *arg)
 }
 
 static int
-process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_stop_listening(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	debug("%s: channel %d: stop listening", __func__, c->self);
 
@@ -1100,7 +1123,7 @@ process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r)
 	}
 
 	if (mux_listener_channel != NULL) {
-		channel_free(mux_listener_channel);
+		channel_free(ssh, mux_listener_channel);
 		client_stop_mux();
 		free(options.control_path);
 		options.control_path = NULL;
@@ -1116,7 +1139,8 @@ process_mux_stop_listening(u_int rid, Channel *c, Buffer *m, Buffer *r)
 }
 
 static int
-process_mux_proxy(u_int rid, Channel *c, Buffer *m, Buffer *r)
+process_mux_proxy(struct ssh *ssh, u_int rid,
+    Channel *c, Buffer *m, Buffer *r)
 {
 	debug("%s: channel %d: proxy request", __func__, c->self);
 
@@ -1129,7 +1153,7 @@ process_mux_proxy(u_int rid, Channel *c, Buffer *m, Buffer *r)
 
 /* Channel callbacks fired on read/write from mux slave fd */
 static int
-mux_master_read_cb(Channel *c)
+mux_master_read_cb(struct ssh *ssh, Channel *c)
 {
 	struct mux_master_state *state = (struct mux_master_state *)c->mux_ctx;
 	Buffer in, out;
@@ -1141,7 +1165,7 @@ mux_master_read_cb(Channel *c)
 	if (c->mux_ctx == NULL) {
 		state = xcalloc(1, sizeof(*state));
 		c->mux_ctx = state;
-		channel_register_cleanup(c->self,
+		channel_register_cleanup(ssh, c->self,
 		    mux_master_control_cleanup_cb, 0);
 
 		/* Send hello */
@@ -1149,7 +1173,7 @@ mux_master_read_cb(Channel *c)
 		buffer_put_int(&out, MUX_MSG_HELLO);
 		buffer_put_int(&out, SSHMUX_VER);
 		/* no extensions */
-		buffer_put_string(&c->output, buffer_ptr(&out),
+		buffer_put_string(c->output, buffer_ptr(&out),
 		    buffer_len(&out));
 		buffer_free(&out);
 		debug3("%s: channel %d: hello sent", __func__, c->self);
@@ -1160,7 +1184,7 @@ mux_master_read_cb(Channel *c)
 	buffer_init(&out);
 
 	/* Channel code ensures that we receive whole packets */
-	if ((ptr = buffer_get_string_ptr_ret(&c->input, &have)) == NULL) {
+	if ((ptr = buffer_get_string_ptr_ret(c->input, &have)) == NULL) {
  malf:
 		error("%s: malformed message", __func__);
 		goto out;
@@ -1186,7 +1210,8 @@ mux_master_read_cb(Channel *c)
 
 	for (i = 0; mux_master_handlers[i].handler != NULL; i++) {
 		if (type == mux_master_handlers[i].type) {
-			ret = mux_master_handlers[i].handler(rid, c, &in, &out);
+			ret = mux_master_handlers[i].handler(ssh, rid,
+			    c, &in, &out);
 			break;
 		}
 	}
@@ -1199,7 +1224,7 @@ mux_master_read_cb(Channel *c)
 	}
 	/* Enqueue reply packet */
 	if (buffer_len(&out) != 0) {
-		buffer_put_string(&c->output, buffer_ptr(&out),
+		buffer_put_string(c->output, buffer_ptr(&out),
 		    buffer_len(&out));
 	}
  out:
@@ -1209,7 +1234,7 @@ mux_master_read_cb(Channel *c)
 }
 
 void
-mux_exit_message(Channel *c, int exitval)
+mux_exit_message(struct ssh *ssh, Channel *c, int exitval)
 {
 	Buffer m;
 	Channel *mux_chan;
@@ -1217,7 +1242,7 @@ mux_exit_message(Channel *c, int exitval)
 	debug3("%s: channel %d: exit message, exitval %d", __func__, c->self,
 	    exitval);
 
-	if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
+	if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
 		fatal("%s: channel %d missing mux channel %d",
 		    __func__, c->self, c->ctl_chan);
 
@@ -1227,19 +1252,19 @@ mux_exit_message(Channel *c, int exitval)
 	buffer_put_int(&m, c->self);
 	buffer_put_int(&m, exitval);
 
-	buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
+	buffer_put_string(mux_chan->output, buffer_ptr(&m), buffer_len(&m));
 	buffer_free(&m);
 }
 
 void
-mux_tty_alloc_failed(Channel *c)
+mux_tty_alloc_failed(struct ssh *ssh, Channel *c)
 {
 	Buffer m;
 	Channel *mux_chan;
 
 	debug3("%s: channel %d: TTY alloc failed", __func__, c->self);
 
-	if ((mux_chan = channel_by_id(c->ctl_chan)) == NULL)
+	if ((mux_chan = channel_by_id(ssh, c->ctl_chan)) == NULL)
 		fatal("%s: channel %d missing mux channel %d",
 		    __func__, c->self, c->ctl_chan);
 
@@ -1248,13 +1273,13 @@ mux_tty_alloc_failed(Channel *c)
 	buffer_put_int(&m, MUX_S_TTY_ALLOC_FAIL);
 	buffer_put_int(&m, c->self);
 
-	buffer_put_string(&mux_chan->output, buffer_ptr(&m), buffer_len(&m));
+	buffer_put_string(mux_chan->output, buffer_ptr(&m), buffer_len(&m));
 	buffer_free(&m);
 }
 
 /* Prepare a mux master to listen on a Unix domain socket. */
 void
-muxserver_listen(void)
+muxserver_listen(struct ssh *ssh)
 {
 	mode_t old_umask;
 	char *orig_control_path = options.control_path;
@@ -1327,7 +1352,7 @@ muxserver_listen(void)
 
 	set_nonblock(muxserver_sock);
 
-	mux_listener_channel = channel_new("mux listener",
+	mux_listener_channel = channel_new(ssh, "mux listener",
 	    SSH_CHANNEL_MUX_LISTENER, muxserver_sock, muxserver_sock, -1,
 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
 	    0, options.control_path, 1);
@@ -1338,7 +1363,7 @@ muxserver_listen(void)
 
 /* Callback on open confirmation in mux master for a mux client session. */
 static void
-mux_session_confirm(int id, int success, void *arg)
+mux_session_confirm(struct ssh *ssh, int id, int success, void *arg)
 {
 	struct mux_session_confirm_ctx *cctx = arg;
 	const char *display;
@@ -1348,9 +1373,9 @@ mux_session_confirm(int id, int success, void *arg)
 
 	if (cctx == NULL)
 		fatal("%s: cctx == NULL", __func__);
-	if ((c = channel_by_id(id)) == NULL)
+	if ((c = channel_by_id(ssh, id)) == NULL)
 		fatal("%s: no channel for id %d", __func__, id);
-	if ((cc = channel_by_id(c->ctl_chan)) == NULL)
+	if ((cc = channel_by_id(ssh, c->ctl_chan)) == NULL)
 		fatal("%s: channel %d lacks control channel %d", __func__,
 		    id, c->ctl_chan);
 
@@ -1369,27 +1394,27 @@ mux_session_confirm(int id, int success, void *arg)
 		char *proto, *data;
 
 		/* Get reasonable local authentication information. */
-		if (client_x11_get_proto(display, options.xauth_location,
+		if (client_x11_get_proto(ssh, display, options.xauth_location,
 		    options.forward_x11_trusted, options.forward_x11_timeout,
 		    &proto, &data) == 0) {
 			/* Request forwarding with authentication spoofing. */
 			debug("Requesting X11 forwarding with authentication "
 			    "spoofing.");
-			x11_request_forwarding_with_spoofing(id, display, proto,
-			    data, 1);
+			x11_request_forwarding_with_spoofing(ssh, id,
+			    display, proto, data, 1);
 			/* XXX exit_on_forward_failure */
-			client_expect_confirm(id, "X11 forwarding",
+			client_expect_confirm(ssh, id, "X11 forwarding",
 			    CONFIRM_WARN);
 		}
 	}
 
 	if (cctx->want_agent_fwd && options.forward_agent) {
 		debug("Requesting authentication agent forwarding.");
-		channel_request_start(id, "auth-agent-req@openssh.com", 0);
+		channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
 		packet_send();
 	}
 
-	client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
+	client_session2_setup(ssh, id, cctx->want_tty, cctx->want_subsys,
 	    cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);
 
 	debug3("%s: sending success reply", __func__);
@@ -1401,7 +1426,7 @@ mux_session_confirm(int id, int success, void *arg)
 
  done:
 	/* Send reply */
-	buffer_put_string(&cc->output, buffer_ptr(&reply), buffer_len(&reply));
+	buffer_put_string(cc->output, buffer_ptr(&reply), buffer_len(&reply));
 	buffer_free(&reply);
 
 	if (cc->mux_pause <= 0)
diff --git a/nchan.c b/nchan.c
index 36da8904a..74c855c90 100644
--- a/nchan.c
+++ b/nchan.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: nchan.c,v 1.65 2017/04/30 23:28:42 djm Exp $ */
+/* $OpenBSD: nchan.c,v 1.66 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
  *
@@ -34,7 +34,8 @@
 
 #include "openbsd-compat/sys-queue.h"
 #include "ssh2.h"
-#include "buffer.h"
+#include "sshbuf.h"
+#include "ssherr.h"
 #include "packet.h"
 #include "channels.h"
 #include "compat.h"
@@ -73,15 +74,15 @@
 /*
  * ACTIONS: should never update the channel states
  */
-static void	chan_send_eof2(Channel *);
-static void	chan_send_eow2(Channel *);
+static void	chan_send_eof2(struct ssh *, Channel *);
+static void	chan_send_eow2(struct ssh *, Channel *);
 
 /* helper */
-static void	chan_shutdown_write(Channel *);
-static void	chan_shutdown_read(Channel *);
+static void	chan_shutdown_write(struct ssh *, Channel *);
+static void	chan_shutdown_read(struct ssh *, Channel *);
 
-static char *ostates[] = { "open", "drain", "wait_ieof", "closed" };
-static char *istates[] = { "open", "drain", "wait_oclose", "closed" };
+static const char *ostates[] = { "open", "drain", "wait_ieof", "closed" };
+static const char *istates[] = { "open", "drain", "wait_oclose", "closed" };
 
 static void
 chan_set_istate(Channel *c, u_int next)
@@ -104,12 +105,12 @@ chan_set_ostate(Channel *c, u_int next)
 }
 
 void
-chan_read_failed(Channel *c)
+chan_read_failed(struct ssh *ssh, Channel *c)
 {
 	debug2("channel %d: read failed", c->self);
 	switch (c->istate) {
 	case CHAN_INPUT_OPEN:
-		chan_shutdown_read(c);
+		chan_shutdown_read(ssh, c);
 		chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN);
 		break;
 	default:
@@ -120,10 +121,10 @@ chan_read_failed(Channel *c)
 }
 
 void
-chan_ibuf_empty(Channel *c)
+chan_ibuf_empty(struct ssh *ssh, Channel *c)
 {
 	debug2("channel %d: ibuf empty", c->self);
-	if (buffer_len(&c->input)) {
+	if (sshbuf_len(c->input)) {
 		error("channel %d: chan_ibuf_empty for non empty buffer",
 		    c->self);
 		return;
@@ -131,7 +132,7 @@ chan_ibuf_empty(Channel *c)
 	switch (c->istate) {
 	case CHAN_INPUT_WAIT_DRAIN:
 		if (!(c->flags & (CHAN_CLOSE_SENT|CHAN_LOCAL)))
-			chan_send_eof2(c);
+			chan_send_eof2(ssh, c);
 		chan_set_istate(c, CHAN_INPUT_CLOSED);
 		break;
 	default:
@@ -142,17 +143,17 @@ chan_ibuf_empty(Channel *c)
 }
 
 void
-chan_obuf_empty(Channel *c)
+chan_obuf_empty(struct ssh *ssh, Channel *c)
 {
 	debug2("channel %d: obuf empty", c->self);
-	if (buffer_len(&c->output)) {
+	if (sshbuf_len(c->output)) {
 		error("channel %d: chan_obuf_empty for non empty buffer",
 		    c->self);
 		return;
 	}
 	switch (c->ostate) {
 	case CHAN_OUTPUT_WAIT_DRAIN:
-		chan_shutdown_write(c);
+		chan_shutdown_write(ssh, c);
 		chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 		break;
 	default:
@@ -163,26 +164,29 @@ chan_obuf_empty(Channel *c)
 }
 
 void
-chan_rcvd_eow(Channel *c)
+chan_rcvd_eow(struct ssh *ssh, Channel *c)
 {
 	debug2("channel %d: rcvd eow", c->self);
 	switch (c->istate) {
 	case CHAN_INPUT_OPEN:
-		chan_shutdown_read(c);
+		chan_shutdown_read(ssh, c);
 		chan_set_istate(c, CHAN_INPUT_CLOSED);
 		break;
 	}
 }
 
 static void
-chan_send_eof2(Channel *c)
+chan_send_eof2(struct ssh *ssh, Channel *c)
 {
+	int r;
+
 	debug2("channel %d: send eof", c->self);
 	switch (c->istate) {
 	case CHAN_INPUT_WAIT_DRAIN:
-		packet_start(SSH2_MSG_CHANNEL_EOF);
-		packet_put_int(c->remote_id);
-		packet_send();
+		if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_EOF)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0)
+			fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r));
 		c->flags |= CHAN_EOF_SENT;
 		break;
 	default:
@@ -193,8 +197,10 @@ chan_send_eof2(Channel *c)
 }
 
 static void
-chan_send_close2(Channel *c)
+chan_send_close2(struct ssh *ssh, Channel *c)
 {
+	int r;
+
 	debug2("channel %d: send close", c->self);
 	if (c->ostate != CHAN_OUTPUT_CLOSED ||
 	    c->istate != CHAN_INPUT_CLOSED) {
@@ -203,16 +209,19 @@ chan_send_close2(Channel *c)
 	} else if (c->flags & CHAN_CLOSE_SENT) {
 		error("channel %d: already sent close", c->self);
 	} else {
-		packet_start(SSH2_MSG_CHANNEL_CLOSE);
-		packet_put_int(c->remote_id);
-		packet_send();
+		if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_CLOSE)) != 0 ||
+		    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+		    (r = sshpkt_send(ssh)) != 0)
+			fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r));
 		c->flags |= CHAN_CLOSE_SENT;
 	}
 }
 
 static void
-chan_send_eow2(Channel *c)
+chan_send_eow2(struct ssh *ssh, Channel *c)
 {
+	int r;
+
 	debug2("channel %d: send eow", c->self);
 	if (c->ostate == CHAN_OUTPUT_CLOSED) {
 		error("channel %d: must not sent eow on closed output",
@@ -221,30 +230,31 @@ chan_send_eow2(Channel *c)
 	}
 	if (!(datafellows & SSH_NEW_OPENSSH))
 		return;
-	packet_start(SSH2_MSG_CHANNEL_REQUEST);
-	packet_put_int(c->remote_id);
-	packet_put_cstring("eow@openssh.com");
-	packet_put_char(0);
-	packet_send();
+	if ((r = sshpkt_start(ssh, SSH2_MSG_CHANNEL_REQUEST)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, c->remote_id)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh, "eow@openssh.com")) != 0 ||
+	    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: send CHANNEL_EOF: %s", __func__, ssh_err(r));
 }
 
 /* shared */
 
 void
-chan_rcvd_ieof(Channel *c)
+chan_rcvd_ieof(struct ssh *ssh, Channel *c)
 {
 	debug2("channel %d: rcvd eof", c->self);
 	c->flags |= CHAN_EOF_RCVD;
 	if (c->ostate == CHAN_OUTPUT_OPEN)
 		chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
 	if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN &&
-	    buffer_len(&c->output) == 0 &&
+	    sshbuf_len(c->output) == 0 &&
 	    !CHANNEL_EFD_OUTPUT_ACTIVE(c))
-		chan_obuf_empty(c);
+		chan_obuf_empty(ssh, c);
 }
 
 void
-chan_rcvd_oclose(Channel *c)
+chan_rcvd_oclose(struct ssh *ssh, Channel *c)
 {
 	debug2("channel %d: rcvd close", c->self);
 	if (!(c->flags & CHAN_LOCAL)) {
@@ -270,27 +280,27 @@ chan_rcvd_oclose(Channel *c)
 	}
 	switch (c->istate) {
 	case CHAN_INPUT_OPEN:
-		chan_shutdown_read(c);
+		chan_shutdown_read(ssh, c);
 		chan_set_istate(c, CHAN_INPUT_CLOSED);
 		break;
 	case CHAN_INPUT_WAIT_DRAIN:
 		if (!(c->flags & CHAN_LOCAL))
-			chan_send_eof2(c);
+			chan_send_eof2(ssh, c);
 		chan_set_istate(c, CHAN_INPUT_CLOSED);
 		break;
 	}
 }
 
 void
-chan_write_failed(Channel *c)
+chan_write_failed(struct ssh *ssh, Channel *c)
 {
 	debug2("channel %d: write failed", c->self);
 	switch (c->ostate) {
 	case CHAN_OUTPUT_OPEN:
 	case CHAN_OUTPUT_WAIT_DRAIN:
-		chan_shutdown_write(c);
+		chan_shutdown_write(ssh, c);
 		if (strcmp(c->ctype, "session") == 0)
-			chan_send_eow2(c);
+			chan_send_eow2(ssh, c);
 		chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 		break;
 	default:
@@ -301,13 +311,13 @@ chan_write_failed(Channel *c)
 }
 
 void
-chan_mark_dead(Channel *c)
+chan_mark_dead(struct ssh *ssh, Channel *c)
 {
 	c->type = SSH_CHANNEL_ZOMBIE;
 }
 
 int
-chan_is_dead(Channel *c, int do_send)
+chan_is_dead(struct ssh *ssh, Channel *c, int do_send)
 {
 	if (c->type == SSH_CHANNEL_ZOMBIE) {
 		debug2("channel %d: zombie", c->self);
@@ -318,9 +328,9 @@ chan_is_dead(Channel *c, int do_send)
 	if ((datafellows & SSH_BUG_EXTEOF) &&
 	    c->extended_usage == CHAN_EXTENDED_WRITE &&
 	    c->efd != -1 &&
-	    buffer_len(&c->extended) > 0) {
-		debug2("channel %d: active efd: %d len %d",
-		    c->self, c->efd, buffer_len(&c->extended));
+	    sshbuf_len(c->extended) > 0) {
+		debug2("channel %d: active efd: %d len %zu",
+		    c->self, c->efd, sshbuf_len(c->extended));
 		return 0;
 	}
 	if (c->flags & CHAN_LOCAL) {
@@ -329,7 +339,7 @@ chan_is_dead(Channel *c, int do_send)
 	}		
 	if (!(c->flags & CHAN_CLOSE_SENT)) {
 		if (do_send) {
-			chan_send_close2(c);
+			chan_send_close2(ssh, c);
 		} else {
 			/* channel would be dead if we sent a close */
 			if (c->flags & CHAN_CLOSE_RCVD) {
@@ -349,9 +359,9 @@ chan_is_dead(Channel *c, int do_send)
 
 /* helper */
 static void
-chan_shutdown_write(Channel *c)
+chan_shutdown_write(struct ssh *ssh, Channel *c)
 {
-	buffer_clear(&c->output);
+	sshbuf_reset(c->output);
 	if (c->type == SSH_CHANNEL_LARVAL)
 		return;
 	/* shutdown failure is allowed if write failed already */
@@ -362,7 +372,7 @@ chan_shutdown_write(Channel *c)
 			    "shutdown() failed for fd %d: %.100s",
 			    c->self, c->sock, strerror(errno));
 	} else {
-		if (channel_close_fd(&c->wfd) < 0)
+		if (channel_close_fd(ssh, &c->wfd) < 0)
 			logit("channel %d: chan_shutdown_write: "
 			    "close() failed for fd %d: %.100s",
 			    c->self, c->wfd, strerror(errno));
@@ -370,7 +380,7 @@ chan_shutdown_write(Channel *c)
 }
 
 static void
-chan_shutdown_read(Channel *c)
+chan_shutdown_read(struct ssh *ssh, Channel *c)
 {
 	if (c->type == SSH_CHANNEL_LARVAL)
 		return;
@@ -388,7 +398,7 @@ chan_shutdown_read(Channel *c)
 			    c->self, c->sock, c->istate, c->ostate,
 			    strerror(errno));
 	} else {
-		if (channel_close_fd(&c->rfd) < 0)
+		if (channel_close_fd(ssh, &c->rfd) < 0)
 			logit("channel %d: chan_shutdown_read: "
 			    "close() failed for fd %d: %.100s",
 			    c->self, c->rfd, strerror(errno));
diff --git a/packet.c b/packet.c
index ff69b6601..f114ea52c 100644
--- a/packet.c
+++ b/packet.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.c,v 1.263 2017/07/23 23:37:02 djm Exp $ */
+/* $OpenBSD: packet.c,v 1.264 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2090,35 +2090,6 @@ ssh_packet_get_maxsize(struct ssh *ssh)
 	return ssh->state->max_packet_size;
 }
 
-/*
- * 9.2.  Ignored Data Message
- *
- *   byte      SSH_MSG_IGNORE
- *   string    data
- *
- * All implementations MUST understand (and ignore) this message at any
- * time (after receiving the protocol version). No implementation is
- * required to send them. This message can be used as an additional
- * protection measure against advanced traffic analysis techniques.
- */
-void
-ssh_packet_send_ignore(struct ssh *ssh, int nbytes)
-{
-	u_int32_t rnd = 0;
-	int r, i;
-
-	if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
-	    (r = sshpkt_put_u32(ssh, nbytes)) != 0)
-		fatal("%s: %s", __func__, ssh_err(r));
-	for (i = 0; i < nbytes; i++) {
-		if (i % 4 == 0)
-			rnd = arc4random();
-		if ((r = sshpkt_put_u8(ssh, (u_char)rnd & 0xff)) != 0)
-			fatal("%s: %s", __func__, ssh_err(r));
-		rnd >>= 8;
-	}
-}
-
 void
 ssh_packet_set_rekey_limits(struct ssh *ssh, u_int64_t bytes, u_int32_t seconds)
 {
@@ -2539,6 +2510,12 @@ sshpkt_get_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp)
 }
 
 int
+sshpkt_peek_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp)
+{
+	return sshbuf_peek_string_direct(ssh->state->incoming_packet, valp, lenp);
+}
+
+int
 sshpkt_get_cstring(struct ssh *ssh, char **valp, size_t *lenp)
 {
 	return sshbuf_get_cstring(ssh->state->incoming_packet, valp, lenp);
@@ -2621,6 +2598,37 @@ ssh_packet_send_mux(struct ssh *ssh)
 	return 0;
 }
 
+/*
+ * 9.2.  Ignored Data Message
+ *
+ *   byte      SSH_MSG_IGNORE
+ *   string    data
+ *
+ * All implementations MUST understand (and ignore) this message at any
+ * time (after receiving the protocol version). No implementation is
+ * required to send them. This message can be used as an additional
+ * protection measure against advanced traffic analysis techniques.
+ */
+int
+sshpkt_msg_ignore(struct ssh *ssh, u_int nbytes)
+{
+	u_int32_t rnd = 0;
+	int r;
+	u_int i;
+
+	if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
+	    (r = sshpkt_put_u32(ssh, nbytes)) != 0)
+		return r;
+	for (i = 0; i < nbytes; i++) {
+		if (i % 4 == 0)
+			rnd = arc4random();
+		if ((r = sshpkt_put_u8(ssh, (u_char)rnd & 0xff)) != 0)
+			return r;
+		rnd >>= 8;
+	}
+	return 0;
+}
+
 /* send it */
 
 int
diff --git a/packet.h b/packet.h
index 6ce6dd560..40837e9db 100644
--- a/packet.h
+++ b/packet.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: packet.h,v 1.81 2017/05/31 08:09:45 markus Exp $ */
+/* $OpenBSD: packet.h,v 1.82 2017/09/12 06:32:07 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -80,6 +80,9 @@ struct ssh {
 	/* Client/Server authentication context */
 	void *authctxt;
 
+	/* Channels context */
+	struct ssh_channels *chanctxt;
+
 	/* APP data */
 	void *app_data;
 };
@@ -143,7 +146,6 @@ int      ssh_packet_not_very_much_data_to_write(struct ssh *);
 
 int	 ssh_packet_connection_is_on_socket(struct ssh *);
 int	 ssh_packet_remaining(struct ssh *);
-void	 ssh_packet_send_ignore(struct ssh *, int);
 
 void	 tty_make_modes(int, struct termios *);
 void	 tty_parse_modes(int, int *);
@@ -174,6 +176,7 @@ int     sshpkt_disconnect(struct ssh *, const char *fmt, ...)
 	    __attribute__((format(printf, 2, 3)));
 int	sshpkt_add_padding(struct ssh *, u_char);
 void	sshpkt_fatal(struct ssh *ssh, const char *tag, int r);
+int	sshpkt_msg_ignore(struct ssh *, u_int);
 
 int	sshpkt_put(struct ssh *ssh, const void *v, size_t len);
 int	sshpkt_putb(struct ssh *ssh, const struct sshbuf *b);
@@ -192,6 +195,7 @@ int	sshpkt_get_u32(struct ssh *ssh, u_int32_t *valp);
 int	sshpkt_get_u64(struct ssh *ssh, u_int64_t *valp);
 int	sshpkt_get_string(struct ssh *ssh, u_char **valp, size_t *lenp);
 int	sshpkt_get_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp);
+int	sshpkt_peek_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp);
 int	sshpkt_get_cstring(struct ssh *ssh, char **valp, size_t *lenp);
 int	sshpkt_get_ec(struct ssh *ssh, EC_POINT *v, const EC_GROUP *g);
 int	sshpkt_get_bignum2(struct ssh *ssh, BIGNUM *v);
diff --git a/servconf.c b/servconf.c
index ed1fc71cf..e0e43c3dd 100644
--- a/servconf.c
+++ b/servconf.c
@@ -1,5 +1,5 @@
 
-/* $OpenBSD: servconf.c,v 1.309 2017/06/24 06:34:38 djm Exp $ */
+/* $OpenBSD: servconf.c,v 1.310 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -149,7 +149,7 @@ initialize_server_options(ServerOptions *options)
 	options->num_authkeys_files = 0;
 	options->num_accept_env = 0;
 	options->permit_tun = -1;
-	options->num_permitted_opens = -1;
+	options->permitted_opens = NULL;
 	options->adm_forced_command = NULL;
 	options->chroot_directory = NULL;
 	options->authorized_keys_command = NULL;
@@ -697,6 +697,44 @@ process_queued_listen_addrs(ServerOptions *options)
 	options->num_queued_listens = 0;
 }
 
+/*
+ * Inform channels layer of permitopen options from configuration.
+ */
+void
+process_permitopen(struct ssh *ssh, ServerOptions *options)
+{
+	u_int i;
+	int port;
+	char *host, *arg, *oarg;
+
+	channel_clear_adm_permitted_opens(ssh);
+	if (options->num_permitted_opens == 0)
+		return; /* permit any */
+
+	/* handle keywords: "any" / "none" */
+	if (options->num_permitted_opens == 1 &&
+	    strcmp(options->permitted_opens[0], "any") == 0)
+		return;
+	if (options->num_permitted_opens == 1 &&
+	    strcmp(options->permitted_opens[0], "none") == 0) {
+		channel_disable_adm_local_opens(ssh);
+		return;
+	}
+	/* Otherwise treat it as a list of permitted host:port */
+	for (i = 0; i < options->num_permitted_opens; i++) {
+		oarg = arg = xstrdup(options->permitted_opens[i]);
+		host = hpdelim(&arg);
+		if (host == NULL)
+			fatal("%s: missing host in PermitOpen", __func__);
+		host = cleanhostname(host);
+		if (arg == NULL || ((port = permitopen_port(arg)) < 0))
+			fatal("%s: bad port number in PermitOpen", __func__);
+		/* Send it to channels layer */
+		channel_add_adm_permitted_opens(ssh, host, port);
+		free(oarg);
+	}
+}
+
 struct connection_info *
 get_connection_info(int populate, int use_dns)
 {
@@ -954,7 +992,7 @@ process_server_config_line(ServerOptions *options, char *line,
     const char *filename, int linenum, int *activep,
     struct connection_info *connectinfo)
 {
-	char *cp, **charptr, *arg, *p;
+	char *cp, **charptr, *arg, *arg2, *p;
 	int cmdline = 0, *intptr, value, value2, n, port;
 	SyslogFacility *log_facility_ptr;
 	LogLevel *log_level_ptr;
@@ -1625,24 +1663,17 @@ process_server_config_line(ServerOptions *options, char *line,
 		if (!arg || *arg == '\0')
 			fatal("%s line %d: missing PermitOpen specification",
 			    filename, linenum);
-		n = options->num_permitted_opens;	/* modified later */
-		if (strcmp(arg, "any") == 0) {
-			if (*activep && n == -1) {
-				channel_clear_adm_permitted_opens();
-				options->num_permitted_opens = 0;
-			}
-			break;
-		}
-		if (strcmp(arg, "none") == 0) {
-			if (*activep && n == -1) {
+		i = options->num_permitted_opens;	/* modified later */
+		if (strcmp(arg, "any") == 0 || strcmp(arg, "none") == 0) {
+			if (*activep && i == 0)
 				options->num_permitted_opens = 1;
-				channel_disable_adm_local_opens();
-			}
+				options->permitted_opens = xcalloc(1,
+				    sizeof(*options->permitted_opens));
+				options->permitted_opens[0] = xstrdup(arg);
 			break;
 		}
-		if (*activep && n == -1)
-			channel_clear_adm_permitted_opens();
 		for (; arg != NULL && *arg != '\0'; arg = strdelim(&cp)) {
+			arg2 = xstrdup(arg);
 			p = hpdelim(&arg);
 			if (p == NULL)
 				fatal("%s line %d: missing host in PermitOpen",
@@ -1651,9 +1682,16 @@ process_server_config_line(ServerOptions *options, char *line,
 			if (arg == NULL || ((port = permitopen_port(arg)) < 0))
 				fatal("%s line %d: bad port number in "
 				    "PermitOpen", filename, linenum);
-			if (*activep && n == -1)
-				options->num_permitted_opens =
-				    channel_add_adm_permitted_opens(p, port);
+			if (*activep && i == 0) {
+				options->permitted_opens = xrecallocarray(
+				    options->permitted_opens,
+				    options->num_permitted_opens,
+				    options->num_permitted_opens + 1,
+				    sizeof(*options->permitted_opens));
+				i = options->num_permitted_opens++;
+				options->permitted_opens[i] = arg2;
+			} else
+				free(arg2);
 		}
 		break;
 
@@ -2352,5 +2390,12 @@ dump_config(ServerOptions *o)
 	printf("rekeylimit %llu %d\n", (unsigned long long)o->rekey_limit,
 	    o->rekey_interval);
 
-	channel_print_adm_permitted_opens();
+	printf("permitopen");
+	if (o->num_permitted_opens == 0)
+		printf(" any");
+	else {
+		for (i = 0; i < o->num_permitted_opens; i++)
+			printf(" %s", o->permitted_opens[i]);
+	}
+	printf("\n");
 }
diff --git a/servconf.h b/servconf.h
index c2848a765..ffcbc3319 100644
--- a/servconf.h
+++ b/servconf.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: servconf.h,v 1.124 2017/06/24 06:34:38 djm Exp $ */
+/* $OpenBSD: servconf.h,v 1.125 2017/09/12 06:32:07 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -48,12 +48,19 @@
 #define FORWARD_LOCAL		(1<<1)
 #define FORWARD_ALLOW		(FORWARD_REMOTE|FORWARD_LOCAL)
 
+/* PermitOpen */
+#define PERMITOPEN_ANY		0
+#define PERMITOPEN_NONE		-2
+
 #define DEFAULT_AUTH_FAIL_MAX	6	/* Default for MaxAuthTries */
 #define DEFAULT_SESSIONS_MAX	10	/* Default for MaxSessions */
 
 /* Magic name for internal sftp-server */
 #define INTERNAL_SFTP_NAME	"internal-sftp"
 
+struct ssh;
+struct fwd_perm_list;
+
 typedef struct {
 	u_int	num_ports;
 	u_int	ports_from_cmdline;
@@ -169,7 +176,8 @@ typedef struct {
 
 	int	permit_tun;
 
-	int	num_permitted_opens;
+	char   **permitted_opens;
+	u_int   num_permitted_opens; /* May also be one of PERMITOPEN_* */
 
 	char   *chroot_directory;
 	char   *revoked_keys_file;
@@ -229,6 +237,7 @@ struct connection_info {
 		M_CP_STRARRAYOPT(deny_groups, num_deny_groups); \
 		M_CP_STRARRAYOPT(accept_env, num_accept_env); \
 		M_CP_STRARRAYOPT(auth_methods, num_auth_methods); \
+		M_CP_STRARRAYOPT(permitted_opens, num_permitted_opens); \
 	} while (0)
 
 struct connection_info *get_connection_info(int, int);
@@ -236,6 +245,7 @@ void	 initialize_server_options(ServerOptions *);
 void	 fill_default_server_options(ServerOptions *);
 int	 process_server_config_line(ServerOptions *, char *, const char *, int,
 	     int *, struct connection_info *);
+void	 process_permitopen(struct ssh *ssh, ServerOptions *options);
 void	 load_server_config(const char *, Buffer *);
 void	 parse_server_config(ServerOptions *, const char *, Buffer *,
 	     struct connection_info *);
diff --git a/serverloop.c b/serverloop.c
index bc56709b1..567159410 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.c,v 1.196 2017/08/30 03:59:08 djm Exp $ */
+/* $OpenBSD: serverloop.c,v 1.197 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -165,7 +165,7 @@ sigterm_handler(int sig)
 }
 
 static void
-client_alive_check(void)
+client_alive_check(struct ssh *ssh)
 {
 	int channel_id;
 
@@ -179,12 +179,13 @@ client_alive_check(void)
 	 * send a bogus global/channel request with "wantreply",
 	 * we should get back a failure
 	 */
-	if ((channel_id = channel_find_open()) == -1) {
+	if ((channel_id = channel_find_open(ssh)) == -1) {
 		packet_start(SSH2_MSG_GLOBAL_REQUEST);
 		packet_put_cstring("keepalive@openssh.com");
 		packet_put_char(1);	/* boolean: want reply */
 	} else {
-		channel_request_start(channel_id, "keepalive@openssh.com", 1);
+		channel_request_start(ssh, channel_id,
+		    "keepalive@openssh.com", 1);
 	}
 	packet_send();
 }
@@ -196,7 +197,8 @@ client_alive_check(void)
  * for the duration of the wait (0 = infinite).
  */
 static void
-wait_until_can_do_something(int connection_in, int connection_out,
+wait_until_can_do_something(struct ssh *ssh,
+    int connection_in, int connection_out,
     fd_set **readsetp, fd_set **writesetp, int *maxfdp,
     u_int *nallocp, u_int64_t max_time_ms)
 {
@@ -207,7 +209,7 @@ wait_until_can_do_something(int connection_in, int connection_out,
 	static time_t last_client_time;
 
 	/* Allocate and update select() masks for channel descriptors. */
-	channel_prepare_select(active_state, readsetp, writesetp, maxfdp,
+	channel_prepare_select(ssh, readsetp, writesetp, maxfdp,
 	    nallocp, &minwait_secs);
 
 	/* XXX need proper deadline system for rekey/client alive */
@@ -273,12 +275,12 @@ wait_until_can_do_something(int connection_in, int connection_out,
 		time_t now = monotime();
 
 		if (ret == 0) { /* timeout */
-			client_alive_check();
+			client_alive_check(ssh);
 		} else if (FD_ISSET(connection_in, *readsetp)) {
 			last_client_time = now;
 		} else if (last_client_time != 0 && last_client_time +
 		    options.client_alive_interval <= now) {
-			client_alive_check();
+			client_alive_check(ssh);
 			last_client_time = now;
 		}
 	}
@@ -291,9 +293,8 @@ wait_until_can_do_something(int connection_in, int connection_out,
  * in buffers and processed later.
  */
 static int
-process_input(fd_set *readset, int connection_in)
+process_input(struct ssh *ssh, fd_set *readset, int connection_in)
 {
-	struct ssh *ssh = active_state; /* XXX */
 	int len;
 	char buf[16384];
 
@@ -333,13 +334,13 @@ process_output(fd_set *writeset, int connection_out)
 }
 
 static void
-process_buffered_input_packets(void)
+process_buffered_input_packets(struct ssh *ssh)
 {
-	ssh_dispatch_run_fatal(active_state, DISPATCH_NONBLOCK, NULL);
+	ssh_dispatch_run_fatal(ssh, DISPATCH_NONBLOCK, NULL);
 }
 
 static void
-collect_children(void)
+collect_children(struct ssh *ssh)
 {
 	pid_t pid;
 	sigset_t oset, nset;
@@ -354,14 +355,14 @@ collect_children(void)
 		while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
 		    (pid < 0 && errno == EINTR))
 			if (pid > 0)
-				session_close_by_pid(pid, status);
+				session_close_by_pid(ssh, pid, status);
 		child_terminated = 0;
 	}
 	sigprocmask(SIG_SETMASK, &oset, NULL);
 }
 
 void
-server_loop2(Authctxt *authctxt)
+server_loop2(struct ssh *ssh, Authctxt *authctxt)
 {
 	fd_set *readset = NULL, *writeset = NULL;
 	int max_fd;
@@ -389,18 +390,17 @@ server_loop2(Authctxt *authctxt)
 	server_init_dispatch();
 
 	for (;;) {
-		process_buffered_input_packets();
+		process_buffered_input_packets(ssh);
 
-		if (!ssh_packet_is_rekeying(active_state) &&
+		if (!ssh_packet_is_rekeying(ssh) &&
 		    packet_not_very_much_data_to_write())
-			channel_output_poll();
-		if (options.rekey_interval > 0 &&
-		    !ssh_packet_is_rekeying(active_state))
+			channel_output_poll(ssh);
+		if (options.rekey_interval > 0 && !ssh_packet_is_rekeying(ssh))
 			rekey_timeout_ms = packet_get_rekey_timeout() * 1000;
 		else
 			rekey_timeout_ms = 0;
 
-		wait_until_can_do_something(connection_in, connection_out,
+		wait_until_can_do_something(ssh, connection_in, connection_out,
 		    &readset, &writeset, &max_fd, &nalloc, rekey_timeout_ms);
 
 		if (received_sigterm) {
@@ -409,23 +409,23 @@ server_loop2(Authctxt *authctxt)
 			cleanup_exit(255);
 		}
 
-		collect_children();
-		if (!ssh_packet_is_rekeying(active_state))
-			channel_after_select(active_state, readset, writeset);
-		if (process_input(readset, connection_in) < 0)
+		collect_children(ssh);
+		if (!ssh_packet_is_rekeying(ssh))
+			channel_after_select(ssh, readset, writeset);
+		if (process_input(ssh, readset, connection_in) < 0)
 			break;
 		process_output(writeset, connection_out);
 	}
-	collect_children();
+	collect_children(ssh);
 
 	free(readset);
 	free(writeset);
 
 	/* free all channels, no more reads and writes */
-	channel_free_all();
+	channel_free_all(ssh);
 
 	/* free remaining sessions, e.g. remove wtmp entries */
-	session_destroy_all(NULL);
+	session_destroy_all(ssh, NULL);
 }
 
 static int
@@ -442,7 +442,7 @@ server_input_keep_alive(int type, u_int32_t seq, struct ssh *ssh)
 }
 
 static Channel *
-server_request_direct_tcpip(int *reason, const char **errmsg)
+server_request_direct_tcpip(struct ssh *ssh, int *reason, const char **errmsg)
 {
 	Channel *c = NULL;
 	char *target, *originator;
@@ -460,7 +460,7 @@ server_request_direct_tcpip(int *reason, const char **errmsg)
 	/* XXX fine grained permissions */
 	if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0 &&
 	    !no_port_forwarding_flag && !options.disable_forwarding) {
-		c = channel_connect_to_port(target, target_port,
+		c = channel_connect_to_port(ssh, target, target_port,
 		    "direct-tcpip", "direct-tcpip", reason, errmsg);
 	} else {
 		logit("refused local port forward: "
@@ -477,7 +477,7 @@ server_request_direct_tcpip(int *reason, const char **errmsg)
 }
 
 static Channel *
-server_request_direct_streamlocal(void)
+server_request_direct_streamlocal(struct ssh *ssh)
 {
 	Channel *c = NULL;
 	char *target, *originator;
@@ -499,7 +499,7 @@ server_request_direct_streamlocal(void)
 	if ((options.allow_streamlocal_forwarding & FORWARD_LOCAL) != 0 &&
 	    !no_port_forwarding_flag && !options.disable_forwarding &&
 	    (pw->pw_uid == 0 || use_privsep)) {
-		c = channel_connect_to_path(target,
+		c = channel_connect_to_path(ssh, target,
 		    "direct-streamlocal@openssh.com", "direct-streamlocal");
 	} else {
 		logit("refused streamlocal port forward: "
@@ -514,7 +514,7 @@ server_request_direct_streamlocal(void)
 }
 
 static Channel *
-server_request_tun(void)
+server_request_tun(struct ssh *ssh)
 {
 	Channel *c = NULL;
 	int mode, tun;
@@ -544,7 +544,7 @@ server_request_tun(void)
 	sock = tun_open(tun, mode);
 	if (sock < 0)
 		goto done;
-	c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
+	c = channel_new(ssh, "tun", SSH_CHANNEL_OPEN, sock, sock, -1,
 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
 	c->datagram = 1;
 #if defined(SSH_TUN_FILTER)
@@ -560,7 +560,7 @@ server_request_tun(void)
 }
 
 static Channel *
-server_request_session(void)
+server_request_session(struct ssh *ssh)
 {
 	Channel *c;
 
@@ -578,15 +578,15 @@ server_request_session(void)
 	 * SSH_CHANNEL_LARVAL.  Additionally, a callback for handling all
 	 * CHANNEL_REQUEST messages is registered.
 	 */
-	c = channel_new("session", SSH_CHANNEL_LARVAL,
+	c = channel_new(ssh, "session", SSH_CHANNEL_LARVAL,
 	    -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
 	    0, "server-session", 1);
 	if (session_open(the_authctxt, c->self) != 1) {
 		debug("session open failed, free channel %d", c->self);
-		channel_free(c);
+		channel_free(ssh, c);
 		return NULL;
 	}
-	channel_register_cleanup(c->self, session_close_by_channel, 0);
+	channel_register_cleanup(ssh, c->self, session_close_by_channel, 0);
 	return c;
 }
 
@@ -608,13 +608,13 @@ server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
 	    ctype, rchan, rwindow, rmaxpack);
 
 	if (strcmp(ctype, "session") == 0) {
-		c = server_request_session();
+		c = server_request_session(ssh);
 	} else if (strcmp(ctype, "direct-tcpip") == 0) {
-		c = server_request_direct_tcpip(&reason, &errmsg);
+		c = server_request_direct_tcpip(ssh, &reason, &errmsg);
 	} else if (strcmp(ctype, "direct-streamlocal@openssh.com") == 0) {
-		c = server_request_direct_streamlocal();
+		c = server_request_direct_streamlocal(ssh);
 	} else if (strcmp(ctype, "tun@openssh.com") == 0) {
-		c = server_request_tun();
+		c = server_request_tun(ssh);
 	}
 	if (c != NULL) {
 		debug("server_input_channel_open: confirm %s", ctype);
@@ -645,9 +645,8 @@ server_input_channel_open(int type, u_int32_t seq, struct ssh *ssh)
 }
 
 static int
-server_input_hostkeys_prove(struct sshbuf **respp)
+server_input_hostkeys_prove(struct ssh *ssh, struct sshbuf **respp)
 {
-	struct ssh *ssh = active_state; /* XXX */
 	struct sshbuf *resp = NULL;
 	struct sshbuf *sigbuf = NULL;
 	struct sshkey *key = NULL, *key_pub = NULL, *key_prv = NULL;
@@ -750,7 +749,7 @@ server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
 			packet_send_debug("Server has disabled port forwarding.");
 		} else {
 			/* Start listening on the port */
-			success = channel_setup_remote_fwd_listener(&fwd,
+			success = channel_setup_remote_fwd_listener(ssh, &fwd,
 			    &allocated_listen_port, &options.fwd_opts);
 		}
 		free(fwd.listen_host);
@@ -768,7 +767,7 @@ server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
 		debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
 		    fwd.listen_host, fwd.listen_port);
 
-		success = channel_cancel_rport_listener(&fwd);
+		success = channel_cancel_rport_listener(ssh, &fwd);
 		free(fwd.listen_host);
 	} else if (strcmp(rtype, "streamlocal-forward@openssh.com") == 0) {
 		struct Forward fwd;
@@ -787,7 +786,7 @@ server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
 			    "streamlocal forwarding.");
 		} else {
 			/* Start listening on the socket */
-			success = channel_setup_remote_fwd_listener(
+			success = channel_setup_remote_fwd_listener(ssh,
 			    &fwd, NULL, &options.fwd_opts);
 		}
 		free(fwd.listen_path);
@@ -799,19 +798,19 @@ server_input_global_request(int type, u_int32_t seq, struct ssh *ssh)
 		debug("%s: cancel-streamlocal-forward path %s", __func__,
 		    fwd.listen_path);
 
-		success = channel_cancel_rport_listener(&fwd);
+		success = channel_cancel_rport_listener(ssh, &fwd);
 		free(fwd.listen_path);
 	} else if (strcmp(rtype, "no-more-sessions@openssh.com") == 0) {
 		no_more_sessions = 1;
 		success = 1;
 	} else if (strcmp(rtype, "hostkeys-prove-00@openssh.com") == 0) {
-		success = server_input_hostkeys_prove(&resp);
+		success = server_input_hostkeys_prove(ssh, &resp);
 	}
 	if (want_reply) {
 		packet_start(success ?
 		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
 		if (success && resp != NULL)
-			ssh_packet_put_raw(active_state, sshbuf_ptr(resp),
+			ssh_packet_put_raw(ssh, sshbuf_ptr(resp),
 			    sshbuf_len(resp));
 		packet_send();
 		packet_write_wait();
@@ -835,15 +834,15 @@ server_input_channel_req(int type, u_int32_t seq, struct ssh *ssh)
 	debug("server_input_channel_req: channel %d request %s reply %d",
 	    id, rtype, reply);
 
-	if ((c = channel_lookup(id)) == NULL)
+	if ((c = channel_lookup(ssh, id)) == NULL)
 		packet_disconnect("server_input_channel_req: "
 		    "unknown channel %d", id);
 	if (!strcmp(rtype, "eow@openssh.com")) {
 		packet_check_eom();
-		chan_rcvd_eow(c);
+		chan_rcvd_eow(ssh, c);
 	} else if ((c->type == SSH_CHANNEL_LARVAL ||
 	    c->type == SSH_CHANNEL_OPEN) && strcmp(c->ctype, "session") == 0)
-		success = session_input_channel_req(c, rtype);
+		success = session_input_channel_req(ssh, c, rtype);
 	if (reply && !(c->flags & CHAN_CLOSE_SENT)) {
 		packet_start(success ?
 		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
diff --git a/serverloop.h b/serverloop.h
index d5fbda16f..fd2cf63f7 100644
--- a/serverloop.h
+++ b/serverloop.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: serverloop.h,v 1.7 2016/08/13 17:47:41 markus Exp $ */
+/* $OpenBSD: serverloop.h,v 1.8 2017/09/12 06:32:07 djm Exp $ */
 
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
@@ -21,6 +21,8 @@
 #ifndef SERVERLOOP_H
 #define SERVERLOOP_H
 
-void    server_loop2(Authctxt *);
+struct ssh;
+
+void    server_loop2(struct ssh *, Authctxt *);
 
 #endif
diff --git a/session.c b/session.c
index cd03fd423..4bccb62d1 100644
--- a/session.c
+++ b/session.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: session.c,v 1.291 2017/08/18 05:36:45 djm Exp $ */
+/* $OpenBSD: session.c,v 1.292 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
  *                    All rights reserved
@@ -113,24 +113,24 @@
 /* func */
 
 Session *session_new(void);
-void	session_set_fds(Session *, int, int, int, int, int);
+void	session_set_fds(struct ssh *, Session *, int, int, int, int, int);
 void	session_pty_cleanup(Session *);
 void	session_proctitle(Session *);
-int	session_setup_x11fwd(Session *);
-int	do_exec_pty(Session *, const char *);
-int	do_exec_no_pty(Session *, const char *);
-int	do_exec(Session *, const char *);
-void	do_login(Session *, const char *);
+int	session_setup_x11fwd(struct ssh *, Session *);
+int	do_exec_pty(struct ssh *, Session *, const char *);
+int	do_exec_no_pty(struct ssh *, Session *, const char *);
+int	do_exec(struct ssh *, Session *, const char *);
+void	do_login(struct ssh *, Session *, const char *);
+void	do_child(struct ssh *, Session *, const char *);
 #ifdef LOGIN_NEEDS_UTMPX
 static void	do_pre_login(Session *s);
 #endif
-void	do_child(Session *, const char *);
 void	do_motd(void);
 int	check_quietlogin(Session *, const char *);
 
-static void do_authenticated2(Authctxt *);
+static void do_authenticated2(struct ssh *, Authctxt *);
 
-static int session_pty_req(Session *);
+static int session_pty_req(struct ssh *, Session *);
 
 /* import */
 extern ServerOptions options;
@@ -183,7 +183,7 @@ auth_sock_cleanup_proc(struct passwd *pw)
 }
 
 static int
-auth_input_request_forwarding(struct passwd * pw)
+auth_input_request_forwarding(struct ssh *ssh, struct passwd * pw)
 {
 	Channel *nc;
 	int sock = -1;
@@ -223,7 +223,7 @@ auth_input_request_forwarding(struct passwd * pw)
 		goto authsock_err;
 
 	/* Allocate a channel for the authentication agent socket. */
-	nc = channel_new("auth socket",
+	nc = channel_new(ssh, "auth socket",
 	    SSH_CHANNEL_AUTH_SOCKET, sock, sock, -1,
 	    CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
 	    0, "auth socket", 1);
@@ -288,7 +288,7 @@ prepare_auth_info_file(struct passwd *pw, struct sshbuf *info)
 }
 
 void
-do_authenticated(Authctxt *authctxt)
+do_authenticated(struct ssh *ssh, Authctxt *authctxt)
 {
 	setproctitle("%s", authctxt->pw->pw_name);
 
@@ -296,17 +296,17 @@ do_authenticated(Authctxt *authctxt)
 	/* XXX - streamlocal? */
 	if (no_port_forwarding_flag || options.disable_forwarding ||
 	    (options.allow_tcp_forwarding & FORWARD_LOCAL) == 0)
-		channel_disable_adm_local_opens();
+		channel_disable_adm_local_opens(ssh);
 	else
-		channel_permit_all_opens();
+		channel_permit_all_opens(ssh);
 
 	auth_debug_send();
 
 	prepare_auth_info_file(authctxt->pw, authctxt->session_info);
 
-	do_authenticated2(authctxt);
+	do_authenticated2(ssh, authctxt);
 
-	do_cleanup(authctxt);
+	do_cleanup(ssh, authctxt);
 }
 
 /* Check untrusted xauth strings for metacharacters */
@@ -331,7 +331,7 @@ xauth_valid_string(const char *s)
  * setting up file descriptors and such.
  */
 int
-do_exec_no_pty(Session *s, const char *command)
+do_exec_no_pty(struct ssh *ssh, Session *s, const char *command)
 {
 	pid_t pid;
 
@@ -456,7 +456,7 @@ do_exec_no_pty(Session *s, const char *command)
 #endif
 
 		/* Do processing for the child (exec command etc). */
-		do_child(s, command);
+		do_child(ssh, s, command);
 		/* NOTREACHED */
 	default:
 		break;
@@ -487,7 +487,7 @@ do_exec_no_pty(Session *s, const char *command)
 	close(pout[1]);
 	close(perr[1]);
 
-	session_set_fds(s, pin[1], pout[0], perr[0],
+	session_set_fds(ssh, s, pin[1], pout[0], perr[0],
 	    s->is_subsystem, 0);
 #else
 	/* We are the parent.  Close the child sides of the socket pairs. */
@@ -511,7 +511,7 @@ do_exec_no_pty(Session *s, const char *command)
  * lastlog, and other such operations.
  */
 int
-do_exec_pty(Session *s, const char *command)
+do_exec_pty(struct ssh *ssh, Session *s, const char *command)
 {
 	int fdout, ptyfd, ttyfd, ptymaster;
 	pid_t pid;
@@ -580,13 +580,13 @@ do_exec_pty(Session *s, const char *command)
 		cray_init_job(s->pw); /* set up cray jid and tmpdir */
 #endif /* _UNICOS */
 #ifndef HAVE_OSF_SIA
-		do_login(s, command);
+		do_login(ssh, s, command);
 #endif
 		/*
 		 * Do common processing for the child, such as execing
 		 * the command.
 		 */
-		do_child(s, command);
+		do_child(ssh, s, command);
 		/* NOTREACHED */
 	default:
 		break;
@@ -608,7 +608,7 @@ do_exec_pty(Session *s, const char *command)
 	s->ptymaster = ptymaster;
 	packet_set_interactive(1, 
 	    options.ip_qos_interactive, options.ip_qos_bulk);
-	session_set_fds(s, ptyfd, fdout, -1, 1, 1);
+	session_set_fds(ssh, s, ptyfd, fdout, -1, 1, 1);
 	return 0;
 }
 
@@ -646,9 +646,8 @@ do_pre_login(Session *s)
  * to be forced, execute that instead.
  */
 int
-do_exec(Session *s, const char *command)
+do_exec(struct ssh *ssh, Session *s, const char *command)
 {
-	struct ssh *ssh = active_state; /* XXX */
 	int ret;
 	const char *forced = NULL, *tty = NULL;
 	char session_type[1024];
@@ -707,9 +706,9 @@ do_exec(Session *s, const char *command)
 	}
 #endif
 	if (s->ttyfd != -1)
-		ret = do_exec_pty(s, command);
+		ret = do_exec_pty(ssh, s, command);
 	else
-		ret = do_exec_no_pty(s, command);
+		ret = do_exec_no_pty(ssh, s, command);
 
 	original_command = NULL;
 
@@ -725,9 +724,8 @@ do_exec(Session *s, const char *command)
 
 /* administrative, login(1)-like work */
 void
-do_login(Session *s, const char *command)
+do_login(struct ssh *ssh, Session *s, const char *command)
 {
-	struct ssh *ssh = active_state;	/* XXX */
 	socklen_t fromlen;
 	struct sockaddr_storage from;
 	struct passwd * pw = s->pw;
@@ -960,9 +958,8 @@ copy_environment(char **source, char ***env, u_int *envsize)
 }
 
 static char **
-do_setup_env(Session *s, const char *shell)
+do_setup_env(struct ssh *ssh, Session *s, const char *shell)
 {
-	struct ssh *ssh = active_state; /* XXX */
 	char buf[256];
 	u_int i, envsize;
 	char **env, *laddr;
@@ -1421,7 +1418,7 @@ do_pwchange(Session *s)
 }
 
 static void
-child_close_fds(void)
+child_close_fds(struct ssh *ssh)
 {
 	extern int auth_sock;
 
@@ -1441,7 +1438,7 @@ child_close_fds(void)
 	 * open in the parent.
 	 */
 	/* XXX better use close-on-exec? -markus */
-	channel_close_all();
+	channel_close_all(ssh);
 
 	/*
 	 * Close any extra file descriptors.  Note that there may still be
@@ -1465,7 +1462,7 @@ child_close_fds(void)
  */
 #define ARGV_MAX 10
 void
-do_child(Session *s, const char *command)
+do_child(struct ssh *ssh, Session *s, const char *command)
 {
 	extern char **environ;
 	char **env;
@@ -1481,7 +1478,7 @@ do_child(Session *s, const char *command)
 	/* Force a password change */
 	if (s->authctxt->force_pwchange) {
 		do_setusercontext(pw);
-		child_close_fds();
+		child_close_fds(ssh);
 		do_pwchange(s);
 		exit(1);
 	}
@@ -1530,7 +1527,7 @@ do_child(Session *s, const char *command)
 	 * Make sure $SHELL points to the shell from the password file,
 	 * even if shell is overridden from login.conf
 	 */
-	env = do_setup_env(s, shell);
+	env = do_setup_env(ssh, s, shell);
 
 #ifdef HAVE_LOGIN_CAP
 	shell = login_getcapstr(lc, "shell", (char *)shell, (char *)shell);
@@ -1543,7 +1540,7 @@ do_child(Session *s, const char *command)
 	 * closed before building the environment, as we call
 	 * ssh_remote_ipaddr there.
 	 */
-	child_close_fds();
+	child_close_fds(ssh);
 
 	/*
 	 * Must take new environment into use so that .ssh/rc,
@@ -1840,7 +1837,7 @@ session_by_pid(pid_t pid)
 }
 
 static int
-session_window_change_req(Session *s)
+session_window_change_req(struct ssh *ssh, Session *s)
 {
 	s->col = packet_get_int();
 	s->row = packet_get_int();
@@ -1852,7 +1849,7 @@ session_window_change_req(Session *s)
 }
 
 static int
-session_pty_req(Session *s)
+session_pty_req(struct ssh *ssh, Session *s)
 {
 	u_int len;
 	int n_bytes;
@@ -1905,7 +1902,7 @@ session_pty_req(Session *s)
 }
 
 static int
-session_subsystem_req(Session *s)
+session_subsystem_req(struct ssh *ssh, Session *s)
 {
 	struct stat st;
 	u_int len;
@@ -1932,7 +1929,7 @@ session_subsystem_req(Session *s)
 				s->is_subsystem = SUBSYSTEM_EXT;
 				debug("subsystem: exec() %s", cmd);
 			}
-			success = do_exec(s, cmd) == 0;
+			success = do_exec(ssh, s, cmd) == 0;
 			break;
 		}
 	}
@@ -1945,7 +1942,7 @@ session_subsystem_req(Session *s)
 }
 
 static int
-session_x11_req(Session *s)
+session_x11_req(struct ssh *ssh, Session *s)
 {
 	int success;
 
@@ -1962,7 +1959,7 @@ session_x11_req(Session *s)
 
 	if (xauth_valid_string(s->auth_proto) &&
 	    xauth_valid_string(s->auth_data))
-		success = session_setup_x11fwd(s);
+		success = session_setup_x11fwd(ssh, s);
 	else {
 		success = 0;
 		error("Invalid X11 forwarding data");
@@ -1977,26 +1974,26 @@ session_x11_req(Session *s)
 }
 
 static int
-session_shell_req(Session *s)
+session_shell_req(struct ssh *ssh, Session *s)
 {
 	packet_check_eom();
-	return do_exec(s, NULL) == 0;
+	return do_exec(ssh, s, NULL) == 0;
 }
 
 static int
-session_exec_req(Session *s)
+session_exec_req(struct ssh *ssh, Session *s)
 {
 	u_int len, success;
 
 	char *command = packet_get_string(&len);
 	packet_check_eom();
-	success = do_exec(s, command) == 0;
+	success = do_exec(ssh, s, command) == 0;
 	free(command);
 	return success;
 }
 
 static int
-session_break_req(Session *s)
+session_break_req(struct ssh *ssh, Session *s)
 {
 
 	packet_get_int();	/* ignored */
@@ -2008,7 +2005,7 @@ session_break_req(Session *s)
 }
 
 static int
-session_env_req(Session *s)
+session_env_req(struct ssh *ssh, Session *s)
 {
 	char *name, *val;
 	u_int name_len, val_len, i;
@@ -2043,7 +2040,7 @@ session_env_req(Session *s)
 }
 
 static int
-session_auth_agent_req(Session *s)
+session_auth_agent_req(struct ssh *ssh, Session *s)
 {
 	static int called = 0;
 	packet_check_eom();
@@ -2055,22 +2052,21 @@ session_auth_agent_req(Session *s)
 		return 0;
 	} else {
 		called = 1;
-		return auth_input_request_forwarding(s->pw);
+		return auth_input_request_forwarding(ssh, s->pw);
 	}
 }
 
 int
-session_input_channel_req(Channel *c, const char *rtype)
+session_input_channel_req(struct ssh *ssh, Channel *c, const char *rtype)
 {
 	int success = 0;
 	Session *s;
 
 	if ((s = session_by_channel(c->self)) == NULL) {
-		logit("session_input_channel_req: no session %d req %.100s",
-		    c->self, rtype);
+		logit("%s: no session %d req %.100s", __func__, c->self, rtype);
 		return 0;
 	}
-	debug("session_input_channel_req: session %d req %s", s->self, rtype);
+	debug("%s: session %d req %s", __func__, s->self, rtype);
 
 	/*
 	 * a session is in LARVAL state until a shell, a command
@@ -2078,33 +2074,33 @@ session_input_channel_req(Channel *c, const char *rtype)
 	 */
 	if (c->type == SSH_CHANNEL_LARVAL) {
 		if (strcmp(rtype, "shell") == 0) {
-			success = session_shell_req(s);
+			success = session_shell_req(ssh, s);
 		} else if (strcmp(rtype, "exec") == 0) {
-			success = session_exec_req(s);
+			success = session_exec_req(ssh, s);
 		} else if (strcmp(rtype, "pty-req") == 0) {
-			success = session_pty_req(s);
+			success = session_pty_req(ssh, s);
 		} else if (strcmp(rtype, "x11-req") == 0) {
-			success = session_x11_req(s);
+			success = session_x11_req(ssh, s);
 		} else if (strcmp(rtype, "auth-agent-req@openssh.com") == 0) {
-			success = session_auth_agent_req(s);
+			success = session_auth_agent_req(ssh, s);
 		} else if (strcmp(rtype, "subsystem") == 0) {
-			success = session_subsystem_req(s);
+			success = session_subsystem_req(ssh, s);
 		} else if (strcmp(rtype, "env") == 0) {
-			success = session_env_req(s);
+			success = session_env_req(ssh, s);
 		}
 	}
 	if (strcmp(rtype, "window-change") == 0) {
-		success = session_window_change_req(s);
+		success = session_window_change_req(ssh, s);
 	} else if (strcmp(rtype, "break") == 0) {
-		success = session_break_req(s);
+		success = session_break_req(ssh, s);
 	}
 
 	return success;
 }
 
 void
-session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr,
-    int is_tty)
+session_set_fds(struct ssh *ssh, Session *s,
+    int fdin, int fdout, int fderr, int ignore_fderr, int is_tty)
 {
 	/*
 	 * now that have a child and a pipe to the child,
@@ -2112,7 +2108,7 @@ session_set_fds(Session *s, int fdin, int fdout, int fderr, int ignore_fderr,
 	 */
 	if (s->chanid == -1)
 		fatal("no channel for session %d", s->self);
-	channel_set_fds(s->chanid,
+	channel_set_fds(ssh, s->chanid,
 	    fdout, fdin, fderr,
 	    ignore_fderr ? CHAN_EXTENDED_IGNORE : CHAN_EXTENDED_READ,
 	    1, is_tty, CHAN_SES_WINDOW_DEFAULT);
@@ -2183,40 +2179,40 @@ sig2name(int sig)
 }
 
 static void
-session_close_x11(int id)
+session_close_x11(struct ssh *ssh, int id)
 {
 	Channel *c;
 
-	if ((c = channel_by_id(id)) == NULL) {
-		debug("session_close_x11: x11 channel %d missing", id);
+	if ((c = channel_by_id(ssh, id)) == NULL) {
+		debug("%s: x11 channel %d missing", __func__, id);
 	} else {
 		/* Detach X11 listener */
-		debug("session_close_x11: detach x11 channel %d", id);
-		channel_cancel_cleanup(id);
+		debug("%s: detach x11 channel %d", __func__, id);
+		channel_cancel_cleanup(ssh, id);
 		if (c->ostate != CHAN_OUTPUT_CLOSED)
-			chan_mark_dead(c);
+			chan_mark_dead(ssh, c);
 	}
 }
 
 static void
-session_close_single_x11(int id, void *arg)
+session_close_single_x11(struct ssh *ssh, int id, void *arg)
 {
 	Session *s;
 	u_int i;
 
-	debug3("session_close_single_x11: channel %d", id);
-	channel_cancel_cleanup(id);
+	debug3("%s: channel %d", __func__, id);
+	channel_cancel_cleanup(ssh, id);
 	if ((s = session_by_x11_channel(id)) == NULL)
-		fatal("session_close_single_x11: no x11 channel %d", id);
+		fatal("%s: no x11 channel %d", __func__, id);
 	for (i = 0; s->x11_chanids[i] != -1; i++) {
-		debug("session_close_single_x11: session %d: "
-		    "closing channel %d", s->self, s->x11_chanids[i]);
+		debug("%s: session %d: closing channel %d",
+		    __func__, s->self, s->x11_chanids[i]);
 		/*
 		 * The channel "id" is already closing, but make sure we
 		 * close all of its siblings.
 		 */
 		if (s->x11_chanids[i] != id)
-			session_close_x11(s->x11_chanids[i]);
+			session_close_x11(ssh, s->x11_chanids[i]);
 	}
 	free(s->x11_chanids);
 	s->x11_chanids = NULL;
@@ -2231,22 +2227,22 @@ session_close_single_x11(int id, void *arg)
 }
 
 static void
-session_exit_message(Session *s, int status)
+session_exit_message(struct ssh *ssh, Session *s, int status)
 {
 	Channel *c;
 
-	if ((c = channel_lookup(s->chanid)) == NULL)
-		fatal("session_exit_message: session %d: no channel %d",
-		    s->self, s->chanid);
-	debug("session_exit_message: session %d channel %d pid %ld",
-	    s->self, s->chanid, (long)s->pid);
+	if ((c = channel_lookup(ssh, s->chanid)) == NULL)
+		fatal("%s: session %d: no channel %d",
+		    __func__, s->self, s->chanid);
+	debug("%s: session %d channel %d pid %ld",
+	    __func__, s->self, s->chanid, (long)s->pid);
 
 	if (WIFEXITED(status)) {
-		channel_request_start(s->chanid, "exit-status", 0);
+		channel_request_start(ssh, s->chanid, "exit-status", 0);
 		packet_put_int(WEXITSTATUS(status));
 		packet_send();
 	} else if (WIFSIGNALED(status)) {
-		channel_request_start(s->chanid, "exit-signal", 0);
+		channel_request_start(ssh, s->chanid, "exit-signal", 0);
 		packet_put_cstring(sig2name(WTERMSIG(status)));
 #ifdef WCOREDUMP
 		packet_put_char(WCOREDUMP(status)? 1 : 0);
@@ -2262,14 +2258,14 @@ session_exit_message(Session *s, int status)
 	}
 
 	/* disconnect channel */
-	debug("session_exit_message: release channel %d", s->chanid);
+	debug("%s: release channel %d", __func__, s->chanid);
 
 	/*
 	 * Adjust cleanup callback attachment to send close messages when
 	 * the channel gets EOF. The session will be then be closed
 	 * by session_close_by_channel when the childs close their fds.
 	 */
-	channel_register_cleanup(c->self, session_close_by_channel, 1);
+	channel_register_cleanup(ssh, c->self, session_close_by_channel, 1);
 
 	/*
 	 * emulate a write failure with 'chan_write_failed', nobody will be
@@ -2278,13 +2274,12 @@ session_exit_message(Session *s, int status)
 	 * be some more data waiting in the pipe.
 	 */
 	if (c->ostate != CHAN_OUTPUT_CLOSED)
-		chan_write_failed(c);
+		chan_write_failed(ssh, c);
 }
 
 void
-session_close(Session *s)
+session_close(struct ssh *ssh, Session *s)
 {
-	struct ssh *ssh = active_state; /* XXX */
 	u_int i;
 
 	verbose("Close session: user %s from %.200s port %d id %d",
@@ -2314,16 +2309,15 @@ session_close(Session *s)
 }
 
 void
-session_close_by_pid(pid_t pid, int status)
+session_close_by_pid(struct ssh *ssh, pid_t pid, int status)
 {
 	Session *s = session_by_pid(pid);
 	if (s == NULL) {
-		debug("session_close_by_pid: no session for pid %ld",
-		    (long)pid);
+		debug("%s: no session for pid %ld", __func__, (long)pid);
 		return;
 	}
 	if (s->chanid != -1)
-		session_exit_message(s, status);
+		session_exit_message(ssh, s, status);
 	if (s->ttyfd != -1)
 		session_pty_cleanup(s);
 	s->pid = 0;
@@ -2334,19 +2328,18 @@ session_close_by_pid(pid_t pid, int status)
  * the session 'child' itself dies
  */
 void
-session_close_by_channel(int id, void *arg)
+session_close_by_channel(struct ssh *ssh, int id, void *arg)
 {
 	Session *s = session_by_channel(id);
 	u_int i;
 
 	if (s == NULL) {
-		debug("session_close_by_channel: no session for id %d", id);
+		debug("%s: no session for id %d", __func__, id);
 		return;
 	}
-	debug("session_close_by_channel: channel %d child %ld",
-	    id, (long)s->pid);
+	debug("%s: channel %d child %ld", __func__, id, (long)s->pid);
 	if (s->pid != 0) {
-		debug("session_close_by_channel: channel %d: has child", id);
+		debug("%s: channel %d: has child", __func__, id);
 		/*
 		 * delay detach of session, but release pty, since
 		 * the fd's to the child are already closed
@@ -2356,22 +2349,22 @@ session_close_by_channel(int id, void *arg)
 		return;
 	}
 	/* detach by removing callback */
-	channel_cancel_cleanup(s->chanid);
+	channel_cancel_cleanup(ssh, s->chanid);
 
 	/* Close any X11 listeners associated with this session */
 	if (s->x11_chanids != NULL) {
 		for (i = 0; s->x11_chanids[i] != -1; i++) {
-			session_close_x11(s->x11_chanids[i]);
+			session_close_x11(ssh, s->x11_chanids[i]);
 			s->x11_chanids[i] = -1;
 		}
 	}
 
 	s->chanid = -1;
-	session_close(s);
+	session_close(ssh, s);
 }
 
 void
-session_destroy_all(void (*closefunc)(Session *))
+session_destroy_all(struct ssh *ssh, void (*closefunc)(Session *))
 {
 	int i;
 	for (i = 0; i < sessions_nalloc; i++) {
@@ -2380,7 +2373,7 @@ session_destroy_all(void (*closefunc)(Session *))
 			if (closefunc != NULL)
 				closefunc(s);
 			else
-				session_close(s);
+				session_close(ssh, s);
 		}
 	}
 }
@@ -2423,7 +2416,7 @@ session_proctitle(Session *s)
 }
 
 int
-session_setup_x11fwd(Session *s)
+session_setup_x11fwd(struct ssh *ssh, Session *s)
 {
 	struct stat st;
 	char display[512], auth_display[512];
@@ -2447,14 +2440,14 @@ session_setup_x11fwd(Session *s)
 		debug("X11 display already set.");
 		return 0;
 	}
-	if (x11_create_display_inet(options.x11_display_offset,
+	if (x11_create_display_inet(ssh, options.x11_display_offset,
 	    options.x11_use_localhost, s->single_connection,
 	    &s->display_number, &s->x11_chanids) == -1) {
 		debug("x11_create_display_inet failed.");
 		return 0;
 	}
 	for (i = 0; s->x11_chanids[i] != -1; i++) {
-		channel_register_cleanup(s->x11_chanids[i],
+		channel_register_cleanup(ssh, s->x11_chanids[i],
 		    session_close_single_x11, 0);
 	}
 
@@ -2499,13 +2492,13 @@ session_setup_x11fwd(Session *s)
 }
 
 static void
-do_authenticated2(Authctxt *authctxt)
+do_authenticated2(struct ssh *ssh, Authctxt *authctxt)
 {
-	server_loop2(authctxt);
+	server_loop2(ssh, authctxt);
 }
 
 void
-do_cleanup(Authctxt *authctxt)
+do_cleanup(struct ssh *ssh, Authctxt *authctxt)
 {
 	static int called = 0;
 
@@ -2561,7 +2554,7 @@ do_cleanup(Authctxt *authctxt)
 	 * or if running in monitor.
 	 */
 	if (!use_privsep || mm_is_monitor())
-		session_destroy_all(session_pty_cleanup2);
+		session_destroy_all(ssh, session_pty_cleanup2);
 }
 
 /* Return a name for the remote host that fits inside utmp_size */
diff --git a/session.h b/session.h
index 74c557db6..54dd1f0ca 100644
--- a/session.h
+++ b/session.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: session.h,v 1.34 2017/08/18 05:36:45 djm Exp $ */
+/* $OpenBSD: session.h,v 1.35 2017/09/12 06:32:07 djm Exp $ */
 
 /*
  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
@@ -62,20 +62,20 @@ struct Session {
 	} *env;
 };
 
-void	 do_authenticated(Authctxt *);
-void	 do_cleanup(Authctxt *);
+void	 do_authenticated(struct ssh *, Authctxt *);
+void	 do_cleanup(struct ssh *, Authctxt *);
 
 int	 session_open(Authctxt *, int);
 void	 session_unused(int);
-int	 session_input_channel_req(Channel *, const char *);
-void	 session_close_by_pid(pid_t, int);
-void	 session_close_by_channel(int, void *);
-void	 session_destroy_all(void (*)(Session *));
+int	 session_input_channel_req(struct ssh *, Channel *, const char *);
+void	 session_close_by_pid(struct ssh *ssh, pid_t, int);
+void	 session_close_by_channel(struct ssh *, int, void *);
+void	 session_destroy_all(struct ssh *, void (*)(Session *));
 void	 session_pty_cleanup2(Session *);
 
 Session	*session_new(void);
 Session	*session_by_tty(char *);
-void	 session_close(Session *);
+void	 session_close(struct ssh *, Session *);
 void	 do_setusercontext(struct passwd *);
 
 const char	*session_get_remote_name_or_ip(struct ssh *, u_int, int);
diff --git a/ssh.c b/ssh.c
index 019d1d31c..ecc50f37e 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.462 2017/08/12 06:46:01 djm Exp $ */
+/* $OpenBSD: ssh.c,v 1.463 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -208,7 +208,7 @@ usage(void)
 	exit(255);
 }
 
-static int ssh_session2(void);
+static int ssh_session2(struct ssh *);
 static void load_public_identity_files(void);
 static void main_sigchld_handler(int);
 
@@ -596,6 +596,14 @@ main(int ac, char **av)
 	 */
 	initialize_options(&options);
 
+	/*
+	 * Prepare main ssh transport/connection structures
+	 */
+	if ((ssh = ssh_alloc_session_state()) == NULL)
+		fatal("Couldn't allocate session state");
+	channel_init_channels(ssh);
+	active_state = ssh; /* XXX legacy API compat */
+
 	/* Parse command-line arguments. */
 	host = NULL;
 	use_syslog = 0;
@@ -1108,7 +1116,7 @@ main(int ac, char **av)
 
 	if (options.port == 0)
 		options.port = default_ssh_port();
-	channel_set_af(options.address_family);
+	channel_set_af(ssh, options.address_family);
 
 	/* Tidy and check options */
 	if (options.host_key_alias != NULL)
@@ -1253,8 +1261,7 @@ main(int ac, char **av)
 	if (options.control_path != NULL) {
 		int sock;
 		if ((sock = muxclient(options.control_path)) >= 0) {
-			packet_set_connection(sock, sock);
-			ssh = active_state; /* XXX */
+			ssh_packet_set_connection(ssh, sock, sock);
 			packet_set_mux();
 			goto skip_connect;
 		}
@@ -1274,7 +1281,7 @@ main(int ac, char **av)
 	timeout_ms = options.connection_timeout * 1000;
 
 	/* Open a connection to the remote host. */
-	if (ssh_connect(host, addrs, &hostaddr, options.port,
+	if (ssh_connect(ssh, host, addrs, &hostaddr, options.port,
 	    options.address_family, options.connection_attempts,
 	    &timeout_ms, options.tcp_keep_alive,
 	    options.use_privileged_port) != 0)
@@ -1457,7 +1464,7 @@ main(int ac, char **av)
 	}
 
  skip_connect:
-	exit_status = ssh_session2();
+	exit_status = ssh_session2(ssh);
 	packet_close();
 
 	if (options.control_path != NULL && muxserver_sock != -1)
@@ -1530,7 +1537,7 @@ fork_postauth(void)
 
 /* Callback for remote forward global requests */
 static void
-ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
+ssh_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
 {
 	struct Forward *rfwd = (struct Forward *)ctxt;
 
@@ -1548,10 +1555,10 @@ ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 			logit("Allocated port %u for remote forward to %s:%d",
 			    rfwd->allocated_port,
 			    rfwd->connect_host, rfwd->connect_port);
-			channel_update_permitted_opens(rfwd->handle,
-			    rfwd->allocated_port);
+			channel_update_permitted_opens(ssh,
+			    rfwd->handle, rfwd->allocated_port);
 		} else {
-			channel_update_permitted_opens(rfwd->handle, -1);
+			channel_update_permitted_opens(ssh, rfwd->handle, -1);
 		}
 	}
 	
@@ -1580,21 +1587,21 @@ ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
 }
 
 static void
-client_cleanup_stdio_fwd(int id, void *arg)
+client_cleanup_stdio_fwd(struct ssh *ssh, int id, void *arg)
 {
 	debug("stdio forwarding: done");
 	cleanup_exit(0);
 }
 
 static void
-ssh_stdio_confirm(int id, int success, void *arg)
+ssh_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
 {
 	if (!success)
 		fatal("stdio forwarding failed");
 }
 
 static void
-ssh_init_stdio_forwarding(void)
+ssh_init_stdio_forwarding(struct ssh *ssh)
 {
 	Channel *c;
 	int in, out;
@@ -1608,15 +1615,15 @@ ssh_init_stdio_forwarding(void)
 	if ((in = dup(STDIN_FILENO)) < 0 ||
 	    (out = dup(STDOUT_FILENO)) < 0)
 		fatal("channel_connect_stdio_fwd: dup() in/out failed");
-	if ((c = channel_connect_stdio_fwd(options.stdio_forward_host,
+	if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
 	    options.stdio_forward_port, in, out)) == NULL)
 		fatal("%s: channel_connect_stdio_fwd failed", __func__);
-	channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
-	channel_register_open_confirm(c->self, ssh_stdio_confirm, NULL);
+	channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
+	channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
 }
 
 static void
-ssh_init_forwarding(void)
+ssh_init_forwarding(struct ssh *ssh)
 {
 	int success = 0;
 	int i;
@@ -1635,7 +1642,7 @@ ssh_init_forwarding(void)
 		    options.local_forwards[i].connect_path :
 		    options.local_forwards[i].connect_host,
 		    options.local_forwards[i].connect_port);
-		success += channel_setup_local_fwd_listener(
+		success += channel_setup_local_fwd_listener(ssh,
 		    &options.local_forwards[i], &options.fwd_opts);
 	}
 	if (i > 0 && success != i && options.exit_on_forward_failure)
@@ -1657,7 +1664,7 @@ ssh_init_forwarding(void)
 		    options.remote_forwards[i].connect_host,
 		    options.remote_forwards[i].connect_port);
 		options.remote_forwards[i].handle =
-		    channel_request_remote_forwarding(
+		    channel_request_remote_forwarding(ssh,
 		    &options.remote_forwards[i]);
 		if (options.remote_forwards[i].handle < 0) {
 			if (options.exit_on_forward_failure)
@@ -1666,14 +1673,15 @@ ssh_init_forwarding(void)
 				logit("Warning: Could not request remote "
 				    "forwarding.");
 		} else {
-			client_register_global_confirm(ssh_confirm_remote_forward,
+			client_register_global_confirm(
+			    ssh_confirm_remote_forward,
 			    &options.remote_forwards[i]);
 		}
 	}
 
 	/* Initiate tunnel forwarding. */
 	if (options.tun_open != SSH_TUNMODE_NO) {
-		if (client_request_tun_fwd(options.tun_open,
+		if (client_request_tun_fwd(ssh, options.tun_open,
 		    options.tun_local, options.tun_remote) == -1) {
 			if (options.exit_on_forward_failure)
 				fatal("Could not request tunnel forwarding.");
@@ -1700,7 +1708,7 @@ check_agent_present(void)
 }
 
 static void
-ssh_session2_setup(int id, int success, void *arg)
+ssh_session2_setup(struct ssh *ssh, int id, int success, void *arg)
 {
 	extern char **environ;
 	const char *display;
@@ -1713,15 +1721,15 @@ ssh_session2_setup(int id, int success, void *arg)
 	display = getenv("DISPLAY");
 	if (display == NULL && options.forward_x11)
 		debug("X11 forwarding requested but DISPLAY not set");
-	if (options.forward_x11 && client_x11_get_proto(display,
+	if (options.forward_x11 && client_x11_get_proto(ssh, display,
 	    options.xauth_location, options.forward_x11_trusted,
 	    options.forward_x11_timeout, &proto, &data) == 0) {
 		/* Request forwarding with authentication spoofing. */
 		debug("Requesting X11 forwarding with authentication "
 		    "spoofing.");
-		x11_request_forwarding_with_spoofing(id, display, proto,
+		x11_request_forwarding_with_spoofing(ssh, id, display, proto,
 		    data, 1);
-		client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
+		client_expect_confirm(ssh, id, "X11 forwarding", CONFIRM_WARN);
 		/* XXX exit_on_forward_failure */
 		interactive = 1;
 	}
@@ -1729,7 +1737,7 @@ ssh_session2_setup(int id, int success, void *arg)
 	check_agent_present();
 	if (options.forward_agent) {
 		debug("Requesting authentication agent forwarding.");
-		channel_request_start(id, "auth-agent-req@openssh.com", 0);
+		channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
 		packet_send();
 	}
 
@@ -1737,13 +1745,13 @@ ssh_session2_setup(int id, int success, void *arg)
 	packet_set_interactive(interactive,
 	    options.ip_qos_interactive, options.ip_qos_bulk);
 
-	client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
+	client_session2_setup(ssh, id, tty_flag, subsystem_flag, getenv("TERM"),
 	    NULL, fileno(stdin), &command, environ);
 }
 
 /* open new channel for a session */
 static int
-ssh_session2_open(void)
+ssh_session2_open(struct ssh *ssh)
 {
 	Channel *c;
 	int window, packetmax, in, out, err;
@@ -1773,34 +1781,34 @@ ssh_session2_open(void)
 		window >>= 1;
 		packetmax >>= 1;
 	}
-	c = channel_new(
+	c = channel_new(ssh,
 	    "session", SSH_CHANNEL_OPENING, in, out, err,
 	    window, packetmax, CHAN_EXTENDED_WRITE,
 	    "client-session", /*nonblock*/0);
 
-	debug3("ssh_session2_open: channel_new: %d", c->self);
+	debug3("%s: channel_new: %d", __func__, c->self);
 
-	channel_send_open(c->self);
+	channel_send_open(ssh, c->self);
 	if (!no_shell_flag)
-		channel_register_open_confirm(c->self,
+		channel_register_open_confirm(ssh, c->self,
 		    ssh_session2_setup, NULL);
 
 	return c->self;
 }
 
 static int
-ssh_session2(void)
+ssh_session2(struct ssh *ssh)
 {
 	int id = -1;
 
 	/* XXX should be pre-session */
 	if (!options.control_persist)
-		ssh_init_stdio_forwarding();
-	ssh_init_forwarding();
+		ssh_init_stdio_forwarding(ssh);
+	ssh_init_forwarding(ssh);
 
 	/* Start listening for multiplex clients */
 	if (!packet_get_mux())
-		muxserver_listen();
+		muxserver_listen(ssh);
 
  	/*
 	 * If we are in control persist mode and have a working mux listen
@@ -1828,10 +1836,10 @@ ssh_session2(void)
 	 * stdio forward setup that we skipped earlier.
 	 */
 	if (options.control_persist && muxserver_sock == -1)
-		ssh_init_stdio_forwarding();
+		ssh_init_stdio_forwarding(ssh);
 
 	if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
-		id = ssh_session2_open();
+		id = ssh_session2_open(ssh);
 	else {
 		packet_set_interactive(
 		    options.control_master == SSHCTL_MASTER_NO,
@@ -1866,7 +1874,7 @@ ssh_session2(void)
 			fork_postauth();
 	}
 
-	return client_loop(tty_flag, tty_flag ?
+	return client_loop(ssh, tty_flag, tty_flag ?
 	    options.escape_char : SSH_ESCAPECHAR_NONE, id);
 }
 
diff --git a/sshbuf.h b/sshbuf.h
index 1ac4b8c0a..77f1e9e6d 100644
--- a/sshbuf.h
+++ b/sshbuf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sshbuf.h,v 1.8 2016/11/25 23:22:04 djm Exp $	*/
+/*	$OpenBSD: sshbuf.h,v 1.9 2017/09/12 06:32:07 djm Exp $	*/
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -211,6 +211,7 @@ int	sshbuf_get_string_direct(struct sshbuf *buf, const u_char **valp,
 /* Another variant: "peeks" into the buffer without modifying it */
 int	sshbuf_peek_string_direct(const struct sshbuf *buf, const u_char **valp,
 	    size_t *lenp);
+/* XXX peek_u8 / peek_u32 */
 
 /*
  * Functions to extract or store SSH wire encoded bignums and elliptic
diff --git a/sshconnect.c b/sshconnect.c
index 2842d9e59..608566207 100644
--- a/sshconnect.c
+++ b/sshconnect.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.c,v 1.285 2017/09/03 23:33:13 djm Exp $ */
+/* $OpenBSD: sshconnect.c,v 1.286 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -105,7 +105,7 @@ expand_proxy_command(const char *proxy_command, const char *user,
  * a connected fd back to us.
  */
 static int
-ssh_proxy_fdpass_connect(const char *host, u_short port,
+ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
     const char *proxy_command)
 {
 	char *command_string;
@@ -176,7 +176,8 @@ ssh_proxy_fdpass_connect(const char *host, u_short port,
 			fatal("Couldn't wait for child: %s", strerror(errno));
 
 	/* Set the connection file descriptors. */
-	packet_set_connection(sock, sock);
+	if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
+		return -1; /* ssh_packet_set_connection logs error */
 
 	return 0;
 }
@@ -185,7 +186,8 @@ ssh_proxy_fdpass_connect(const char *host, u_short port,
  * Connect to the given ssh server using a proxy command.
  */
 static int
-ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
+ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
+    const char *proxy_command)
 {
 	char *command_string;
 	int pin[2], pout[2];
@@ -252,9 +254,9 @@ ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
 	free(command_string);
 
 	/* Set the connection file descriptors. */
-	packet_set_connection(pout[0], pin[1]);
+	if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
+		return -1; /* ssh_packet_set_connection logs error */
 
-	/* Indicate OK return */
 	return 0;
 }
 
@@ -410,7 +412,7 @@ timeout_connect(int sockfd, const struct sockaddr *serv_addr,
  * the daemon.
  */
 static int
-ssh_connect_direct(const char *host, struct addrinfo *aitop,
+ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
     struct sockaddr_storage *hostaddr, u_short port, int family,
     int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
 {
@@ -484,27 +486,31 @@ ssh_connect_direct(const char *host, struct addrinfo *aitop,
 		error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
 
 	/* Set the connection. */
-	packet_set_connection(sock, sock);
+	if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
+		return -1; /* ssh_packet_set_connection logs error */
 
-	return 0;
+        return 0;
 }
 
 int
-ssh_connect(const char *host, struct addrinfo *addrs,
+ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
     struct sockaddr_storage *hostaddr, u_short port, int family,
     int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
 {
 	if (options.proxy_command == NULL) {
-		return ssh_connect_direct(host, addrs, hostaddr, port, family,
-		    connection_attempts, timeout_ms, want_keepalive, needpriv);
+		return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
+		    family, connection_attempts, timeout_ms, want_keepalive,
+		    needpriv);
 	} else if (strcmp(options.proxy_command, "-") == 0) {
-		packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
-		return 0; /* Always succeeds */
+		if ((ssh_packet_set_connection(ssh,
+		    STDIN_FILENO, STDOUT_FILENO)) == NULL)
+			return -1; /* ssh_packet_set_connection logs error */
+		return 0;
 	} else if (options.proxy_use_fdpass) {
-		return ssh_proxy_fdpass_connect(host, port,
+		return ssh_proxy_fdpass_connect(ssh, host, port,
 		    options.proxy_command);
 	}
-	return ssh_proxy_connect(host, port, options.proxy_command);
+	return ssh_proxy_connect(ssh, host, port, options.proxy_command);
 }
 
 static void
diff --git a/sshconnect.h b/sshconnect.h
index f4e73f7b1..b5029e234 100644
--- a/sshconnect.h
+++ b/sshconnect.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.h,v 1.30 2017/05/30 08:52:19 markus Exp $ */
+/* $OpenBSD: sshconnect.h,v 1.31 2017/09/12 06:32:07 djm Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -32,8 +32,10 @@ struct Sensitive {
 };
 
 struct addrinfo;
-int	 ssh_connect(const char *, struct addrinfo *, struct sockaddr_storage *,
-    u_short, int, int, int *, int, int);
+struct ssh;
+
+int	 ssh_connect(struct ssh *, const char *, struct addrinfo *,
+	    struct sockaddr_storage *, u_short, int, int, int *, int, int);
 void	 ssh_kill_proxy_command(void);
 
 void	 ssh_login(Sensitive *, const char *, struct sockaddr *, u_short,
diff --git a/sshd.c b/sshd.c
index 1d19ce679..51a1aaf6e 100644
--- a/sshd.c
+++ b/sshd.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshd.c,v 1.491 2017/07/01 13:50:45 djm Exp $ */
+/* $OpenBSD: sshd.c,v 1.492 2017/09/12 06:32:07 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -1621,9 +1621,6 @@ main(int ac, char **av)
 			    "enabled authentication methods");
 	}
 
-	/* set default channel AF */
-	channel_set_af(options.address_family);
-
 	/* Check that there are no remaining arguments. */
 	if (optind < ac) {
 		fprintf(stderr, "Extra argument %s.\n", av[optind]);
@@ -1955,8 +1952,14 @@ main(int ac, char **av)
 	packet_set_connection(sock_in, sock_out);
 	packet_set_server();
 	ssh = active_state; /* XXX */
+
 	check_ip_options(ssh);
 
+	/* Prepare the channels layer */
+	channel_init_channels(ssh);
+	channel_set_af(ssh, options.address_family);
+	process_permitopen(ssh, &options);
+
 	/* Set SO_KEEPALIVE if requested. */
 	if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
 	    setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
@@ -2080,10 +2083,10 @@ main(int ac, char **av)
 	    options.client_alive_count_max);
 
 	/* Try to send all our hostkeys to the client */
-	notify_hostkeys(active_state);
+	notify_hostkeys(ssh);
 
 	/* Start session. */
-	do_authenticated(authctxt);
+	do_authenticated(ssh, authctxt);
 
 	/* The connection has been terminated. */
 	packet_get_bytes(&ibytes, &obytes);
@@ -2211,8 +2214,10 @@ do_ssh2_kex(void)
 void
 cleanup_exit(int i)
 {
+	struct ssh *ssh = active_state; /* XXX */
+
 	if (the_authctxt) {
-		do_cleanup(the_authctxt);
+		do_cleanup(ssh, the_authctxt);
 		if (use_privsep && privsep_is_preauth &&
 		    pmonitor != NULL && pmonitor->m_pid > 1) {
 			debug("Killing privsep child %d", pmonitor->m_pid);
diff --git a/ssherr.c b/ssherr.c
index 4bd5f59cc..3c0009d69 100644
--- a/ssherr.c
+++ b/ssherr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ssherr.c,v 1.6 2017/05/07 23:15:59 djm Exp $	*/
+/*	$OpenBSD: ssherr.c,v 1.7 2017/09/12 06:32:08 djm Exp $	*/
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -137,6 +137,8 @@ ssh_err(int n)
 		return "Protocol error";
 	case SSH_ERR_KEY_LENGTH:
 		return "Invalid key length";
+	case SSH_ERR_NUMBER_TOO_LARGE:
+		return "number is too large";
 	default:
 		return "unknown error";
 	}
diff --git a/ssherr.h b/ssherr.h
index a30781620..c0b59211e 100644
--- a/ssherr.h
+++ b/ssherr.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ssherr.h,v 1.4 2017/05/07 23:15:59 djm Exp $	*/
+/*	$OpenBSD: ssherr.h,v 1.5 2017/09/12 06:32:08 djm Exp $	*/
 /*
  * Copyright (c) 2011 Damien Miller
  *
@@ -78,6 +78,7 @@
 #define SSH_ERR_CONN_CORRUPT			-54
 #define SSH_ERR_PROTOCOL_ERROR			-55
 #define SSH_ERR_KEY_LENGTH			-56
+#define SSH_ERR_NUMBER_TOO_LARGE		-57
 
 /* Translate a numeric error code to a human-readable error string */
 const char *ssh_err(int n);