diff --git a/channels.c b/channels.c
index d9e81b5..935625c 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;
-
-/*
- * Maximum file descriptor value used in any of the channels.  This is
- * updated in channel_new.
- */
-static int channel_max_fd = 0;
-
+/* -- agent forwarding */
+#define	NUM_SOCKS	10
 
 /* -- 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	"*"
+
+/* -- 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 @@
 	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;
+/* 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 pairs in the array permitted by the user. */
-static int num_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;
 
-/* Number of permitted host/port pair in the array permitted by the admin. */
-static int num_adm_permitted_opens = 0;
+	/*
+	 * Maximum file descriptor value used in any of the channels.  This is
+	 * updated in channel_new.
+	 */
+	int channel_max_fd;
 
-/* special-case port number meaning allow any port */
-#define FWD_PERMIT_ANY_PORT	0
+	/*
+	 * '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;
 
-/* special-case wildcard meaning allow any host */
-#define FWD_PERMIT_ANY_HOST	"*"
+	/* -- tcp forwarding */
 
-/*
- * 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;
+	/* List of all permitted host/port pairs to connect by the user. */
+	ForwardPermission *permitted_opens;
 
+	/* List of all permitted host/port pairs to connect by the admin. */
+	ForwardPermission *permitted_adm_opens;
 
-/* -- X11 forwarding */
+	/*
+	 * Number of permitted host/port pairs in the array permitted by
+	 * the user.
+	 */
+	u_int num_permitted_opens;
 
-/* Maximum number of fake X11 displays to try. */
-#define MAX_DISPLAYS  1000
+	/*
+	 * Number of permitted host/port pair in the array permitted by
+	 * the admin.
+	 */
+	u_int num_adm_permitted_opens;
 
-/* Saved X11 local (client) display. */
-static char *x11_saved_display = 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 protocol name. */
-static char *x11_saved_proto = NULL;
+	/* -- X11 forwarding */
 
-/* Saved X11 authentication data.  This is the real data. */
-static char *x11_saved_data = NULL;
-static u_int x11_saved_data_len = 0;
+	/* Saved X11 local (client) display. */
+	char *x11_saved_display;
 
-/* Deadline after which all X11 connections are refused */
-static u_int x11_refuse_time;
+	/* Saved X11 authentication protocol name. */
+	char *x11_saved_proto;
 
-/*
- * 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 data.  This is the real data. */
+	char *x11_saved_data;
+	u_int x11_saved_data_len;
 
+	/* Deadline after which all X11 connections are refused */
+	u_int x11_refuse_time;
 
-/* -- agent forwarding */
+	/*
+	 * 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;
 
-#define	NUM_SOCKS	10
-
-/* 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 @@
  * 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 @@
 	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 @@
  * 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 @@
  * 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(&c->sock);
-	channel_close_fd(&c->rfd);
-	channel_close_fd(&c->wfd);
-	channel_close_fd(&c->efd);
+	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)
+{
+	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 @@
 	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 @@
  * 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 @@
 			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 @@
  * 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 @@
 
 /* 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 @@
 
 /* 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 @@
  * 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;
+	int r;
+	char *ret;
 
-	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];
+	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 @@
 		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 @@
 }
 
 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 @@
 }
 
 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 @@
 }
 
 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 @@
 }
 
 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 @@
 }
 
 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();
+
+	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));
 }
 
-/*
- * '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];
-
-/* 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 @@
  * 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 @@
 	}
 
 	/* 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 @@
 	 * 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 @@
 		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 @@
 	}
 	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 @@
 	}
 	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 @@
 			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 @@
 	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 @@
 #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 @@
 	} 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 @@
 			    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 @@
 		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 @@
 	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 @@
 	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 @@
 		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 @@
 	} 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);
+	if (!FD_ISSET(c->sock, readset))
+		return;
 
-		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);
+	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 @@
 		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 @@
 }
 
 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 @@
 	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 (!FD_ISSET(c->sock, readset))
+		return;
 
-		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";
-		}
+	debug("Connection to port %d forwarding to %.100s port %d requested.",
+	    c->listening_port, c->path, c->host_port);
 
-		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);
+	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 (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);
-		}
-		packet_send();
+	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));
+		}
+	} 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));
+		}
+		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);
-		}
-
-		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);
-#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);
-			}
+	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;
 		}
-#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();
-			}
-		}
+	} 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;
+	}
+
+#ifdef _AIX
+	/* XXX: Later AIX versions can't push as much data to tty */
+	if (c->wfd_isatty)
+		dlen = MIN(dlen, 8*1024);
 #endif
-		buffer_consume(&c->output, len);
+
+	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)
+			 */
+			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 /* 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(Channel *c, fd_set *readset, fd_set *writeset)
+channel_handle_efd_write(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
+{
+	int r;
+	ssize_t len;
+
+	if (!FD_ISSET(c->efd, writeset) || sshbuf_len(c->extended) == 0)
+		return 1;
+
+	len = write(c->efd, sshbuf_ptr(c->extended),
+	    sshbuf_len(c->extended));
+	debug2("channel %d: written %zd to efd %d", c->self, len, c->efd);
+	if (len < 0 && (errno == EINTR || errno == EAGAIN ||
+	    errno == EWOULDBLOCK))
+		return 1;
+	if (len <= 0) {
+		debug2("channel %d: closing write-efd %d", c->self, c->efd);
+		channel_close_fd(ssh, &c->efd);
+	} else {
+		if ((r = sshbuf_consume(c->extended, len)) != 0) {
+			fatal("%s: channel %d: consume: %s",
+			    __func__, c->self, ssh_err(r));
+		}
+		c->local_consumed += len;
+	}
+	return 1;
+}
+
+static int
+channel_handle_efd_read(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	char buf[CHAN_RBUF];
-	int len;
+	int r;
+	ssize_t len;
 
-/** XXX handle drain efd, too */
-	if (c->efd != -1) {
-		if (c->extended_usage == CHAN_EXTENDED_WRITE &&
-		    FD_ISSET(c->efd, writeset) &&
-		    buffer_len(&c->extended) > 0) {
-			len = write(c->efd, buffer_ptr(&c->extended),
-			    buffer_len(&c->extended));
-			debug2("channel %d: written %d to efd %d",
-			    c->self, len, c->efd);
-			if (len < 0 && (errno == EINTR || errno == EAGAIN ||
-			    errno == EWOULDBLOCK))
-				return 1;
-			if (len <= 0) {
-				debug2("channel %d: closing write-efd %d",
-				    c->self, c->efd);
-				channel_close_fd(&c->efd);
-			} else {
-				buffer_consume(&c->extended, len);
-				c->local_consumed += len;
-			}
-		} else if (c->efd != -1 &&
-		    (c->extended_usage == CHAN_EXTENDED_READ ||
-		    c->extended_usage == CHAN_EXTENDED_IGNORE) &&
-		    (c->detach_close || FD_ISSET(c->efd, readset))) {
-			len = read(c->efd, buf, sizeof(buf));
-			debug2("channel %d: read %d from efd %d",
-			    c->self, len, c->efd);
-			if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
-			    errno == EWOULDBLOCK) && !c->detach_close)))
-				return 1;
-			if (len <= 0) {
-				debug2("channel %d: closing read-efd %d",
-				    c->self, c->efd);
-				channel_close_fd(&c->efd);
-			} else {
-				if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
-					debug3("channel %d: discard efd",
-					    c->self);
-				} else
-					buffer_append(&c->extended, buf, len);
-			}
+	if (!c->detach_close && !FD_ISSET(c->efd, readset))
+		return 1;
+
+	len = read(c->efd, buf, sizeof(buf));
+	debug2("channel %d: read %zd from efd %d", c->self, len, c->efd);
+	if (len < 0 && (errno == EINTR || ((errno == EAGAIN ||
+	    errno == EWOULDBLOCK) && !c->detach_close)))
+		return 1;
+	if (len <= 0) {
+		debug2("channel %d: closing read-efd %d",
+		    c->self, c->efd);
+		channel_close_fd(ssh, &c->efd);
+	} else {
+		if (c->extended_usage == CHAN_EXTENDED_IGNORE) {
+			debug3("channel %d: discard efd",
+			    c->self);
+		} else if ((r = sshbuf_put(c->extended, buf, len)) != 0) {
+			fatal("%s: channel %d: append: %s",
+			    __func__, c->self, ssh_err(r));
 		}
 	}
 	return 1;
 }
 
 static int
-channel_check_window(Channel *c)
+channel_handle_efd(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
+	if (c->efd == -1)
+		return 1;
+
+	/** XXX handle drain efd, too */
+
+	if (c->extended_usage == CHAN_EXTENDED_WRITE)
+		return channel_handle_efd_write(ssh, c, readset, writeset);
+	else if (c->extended_usage == CHAN_EXTENDED_READ ||
+	    c->extended_usage == CHAN_EXTENDED_IGNORE)
+		return channel_handle_efd_read(ssh, c, readset, writeset);
+
+	return 1;
+}
+
+static int
+channel_check_window(struct ssh *ssh, Channel *c)
+{
+	int r;
+
 	if (c->type == SSH_CHANNEL_OPEN &&
 	    !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
 	    ((c->local_window_max - c->local_window >
 	    c->local_maxpacket*3) ||
 	    c->local_window < c->local_window_max/2) &&
 	    c->local_consumed > 0) {
-		packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
-		packet_put_int(c->remote_id);
-		packet_put_int(c->local_consumed);
-		packet_send();
+		if ((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 @@
 }
 
 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 (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);
+	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;
 	}
 }
 
 static void
-channel_post_mux_listener(Channel *c, fd_set *readset, fd_set *writeset)
+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(struct ssh *ssh, Channel *c,
+    fd_set *readset, fd_set *writeset)
 {
 	Channel *nc;
 	struct sockaddr_storage addr;
@@ -1926,97 +2145,98 @@
 		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;
+	chan_fn **pre, **post;
 
-	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;
+	if ((pre = calloc(SSH_CHANNEL_MAX_TYPE, sizeof(*pre))) == NULL ||
+	   (post = calloc(SSH_CHANNEL_MAX_TYPE, sizeof(*post))) == NULL)
+		fatal("%s: allocation failed", __func__);
 
-	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;
+	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 @@
 			 * 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 @@
 					*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 @@
 {
 	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 @@
 	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 @@
 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 @@
 			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 @@
  * 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 @@
 	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 @@
 			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 @@
 		    (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 @@
 			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 @@
 		    (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 @@
 			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 @@
 	    (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 @@
 		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 @@
 
 /* -- 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 @@
 		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 @@
 	}
 
 	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;
+	const u_char *data;
+	size_t data_len;
+	u_int32_t tcode;
+	Channel *c = channel_from_packet_id(ssh, __func__, "extended data");
+	int r;
 
-	/* Get the channel number and verify it. */
-	id = packet_get_int();
-	c = channel_lookup(id);
-
-	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);
 	}
-	tcode = packet_get_int();
+
+	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");
+	}
 	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");
 
-	id = packet_get_int();
-	packet_check_eom();
-	c = channel_lookup(id);
-	if (c == NULL)
-		packet_disconnect("Received ieof for nonexistent channel %d.", id);
+	ssh_packet_check_eom(ssh);
+
 	if (channel_proxy_upstream(c, type, seq, ssh))
 		return 0;
-	chan_rcvd_ieof(c);
+	chan_rcvd_ieof(ssh, c);
 
 	/* XXX force input close */
 	if (c->force_drain && c->istate == CHAN_INPUT_OPEN) {
 		debug("channel %d: FORCE input drain", c->self);
 		c->istate = CHAN_INPUT_WAIT_DRAIN;
-		if (buffer_len(&c->input) == 0)
-			chan_ibuf_empty(c);
+		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;
+	Channel *c = channel_from_packet_id(ssh, __func__, "open confirmation");
+	u_int32_t remote_window, remote_maxpacket;
+	int r;
 
-	id = packet_get_int();
-	c = channel_lookup(id);
-
-	if (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 @@
 	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;
+	Channel *c = channel_from_packet_id(ssh, __func__, "open failure");
+	u_int32_t reason;
+	char *msg = NULL;
+	int r;
 
-	id = packet_get_int();
-	c = channel_lookup(id);
-
-	if (c==NULL)
-		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");
 	}
-	logit("channel %d: open failed: %s%s%s", id,
+	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");
+		}
+	}
+	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;
+	u_int32_t adjust;
+	u_int new_rwin;
+	int r;
 
-	/* Get the channel number and verify it. */
-	id = packet_get_int();
-	c = channel_lookup(id);
-
-	if (c == NULL) {
+	if ((c = channel_lookup(ssh, id)) == NULL) {
 		logit("Received window adjust for non-open channel %d.", id);
 		return 0;
-	}
+        }
+
 	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 @@
 /* -- 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 @@
 }
 
 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 @@
 	 * 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 @@
 		 * 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 @@
 
 		/* 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 @@
 		 * 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 @@
 		}
 
 		/* 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 @@
 }
 
 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 @@
 	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 @@
 }
 
 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 @@
 			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 @@
 		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_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 @@
  * 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();
+	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));
 
-	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;
+	fwd_perm_clear(fp); /* unregister */
 
 	return 0;
 }
@@ -3398,32 +3701,32 @@
  * 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();
+	if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
+	    (r = sshpkt_put_cstring(ssh,
+	    "cancel-streamlocal-forward@openssh.com")) != 0 ||
+	    (r = sshpkt_put_u8(ssh, 0)) != 0 || /* want reply */
+	    (r = sshpkt_put_cstring(ssh, path)) != 0 ||
+	    (r = sshpkt_send(ssh)) != 0)
+		fatal("%s: send cancel: %s", __func__, ssh_err(r));
 
-	permitted_opens[i].listen_port = 0;
-	permitted_opens[i].port_to_connect = 0;
-	free(permitted_opens[i].host_to_connect);
-	permitted_opens[i].host_to_connect = NULL;
-	permitted_opens[i].listen_host = NULL;
-	free(permitted_opens[i].listen_path);
-	permitted_opens[i].listen_path = NULL;
-	permitted_opens[i].downstream = NULL;
+	fwd_perm_clear(fp); /* unregister */
 
 	return 0;
 }
@@ -3432,14 +3735,15 @@
  * 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 @@
  * 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)
 {
+	struct ssh_channels *sc = ssh->chanctxt;
+
 	debug("allow port forwarding to host %s port %d", host, port);
-
-	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;
+	fwd_perm_list_add(ssh, FWDPERM_USER, host, port, NULL, NULL, 0, NULL);
+	sc->all_opens_permitted = 0;
 }
 
 /*
@@ -3479,105 +3775,61 @@
  * passed then they entry will be invalidated.
  */
 void
-channel_update_permitted_opens(int idx, int newport)
+channel_update_permitted_opens(struct ssh *ssh, int idx, int newport)
 {
-	if (idx < 0 || idx >= num_permitted_opens) {
-		debug("channel_update_permitted_opens: index out of range:"
-		    " %d num_permitted_opens %d", idx, num_permitted_opens);
+	struct ssh_channels *sc = ssh->chanctxt;
+
+	if (idx < 0 || (u_int)idx >= sc->num_permitted_opens) {
+		debug("%s: index out of range: %d num_permitted_opens %d",
+		    __func__, idx, sc->num_permitted_opens);
 		return;
 	}
 	debug("%s allowed port %d for forwarding to host %s port %d",
 	    newport > 0 ? "Updating" : "Removing",
 	    newport,
-	    permitted_opens[idx].host_to_connect,
-	    permitted_opens[idx].port_to_connect);
-	if (newport >= 0)  {
-		permitted_opens[idx].listen_port = 
+	    sc->permitted_opens[idx].host_to_connect,
+	    sc->permitted_opens[idx].port_to_connect);
+	if (newport <= 0)
+		fwd_perm_clear(&sc->permitted_opens[idx]);
+	else {
+		sc->permitted_opens[idx].listen_port =
 		    (datafellows & SSH_BUG_DYNAMIC_RPORT) ? 0 : newport;
-	} else {
-		permitted_opens[idx].listen_port = 0;
-		permitted_opens[idx].port_to_connect = 0;
-		free(permitted_opens[idx].host_to_connect);
-		permitted_opens[idx].host_to_connect = NULL;
-		free(permitted_opens[idx].listen_host);
-		permitted_opens[idx].listen_host = NULL;
-		free(permitted_opens[idx].listen_path);
-		permitted_opens[idx].listen_path = NULL;
 	}
 }
 
 int
-channel_add_adm_permitted_opens(char *host, int port)
+channel_add_adm_permitted_opens(struct ssh *ssh, char *host, int port)
 {
 	debug("config allows port forwarding to host %s port %d", host, port);
-
-	permitted_adm_opens = xreallocarray(permitted_adm_opens,
-	    num_adm_permitted_opens + 1, sizeof(*permitted_adm_opens));
-	permitted_adm_opens[num_adm_permitted_opens].host_to_connect
-	     = xstrdup(host);
-	permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
-	permitted_adm_opens[num_adm_permitted_opens].listen_host = NULL;
-	permitted_adm_opens[num_adm_permitted_opens].listen_path = NULL;
-	permitted_adm_opens[num_adm_permitted_opens].listen_port = 0;
-	return ++num_adm_permitted_opens;
+	return fwd_perm_list_add(ssh, FWDPERM_ADMIN, host, port,
+	    NULL, NULL, 0, NULL);
 }
 
 void
-channel_disable_adm_local_opens(void)
+channel_disable_adm_local_opens(struct ssh *ssh)
 {
-	channel_clear_adm_permitted_opens();
-	permitted_adm_opens = xcalloc(sizeof(*permitted_adm_opens), 1);
-	permitted_adm_opens[num_adm_permitted_opens].host_to_connect = NULL;
-	num_adm_permitted_opens = 1;
+	channel_clear_adm_permitted_opens(ssh);
+	fwd_perm_list_add(ssh, FWDPERM_ADMIN, NULL, 0, NULL, NULL, 0, NULL);
 }
 
 void
-channel_clear_permitted_opens(void)
+channel_clear_permitted_opens(struct ssh *ssh)
 {
-	int i;
+	struct ssh_channels *sc = ssh->chanctxt;
 
-	for (i = 0; i < num_permitted_opens; i++) {
-		free(permitted_opens[i].host_to_connect);
-		free(permitted_opens[i].listen_host);
-		free(permitted_opens[i].listen_path);
-	}
-	free(permitted_opens);
-	permitted_opens = NULL;
-	num_permitted_opens = 0;
+	sc->permitted_opens = xrecallocarray(sc->permitted_opens,
+	    sc->num_permitted_opens, 0, sizeof(*sc->permitted_opens));
+	sc->num_permitted_opens = 0;
 }
 
 void
-channel_clear_adm_permitted_opens(void)
+channel_clear_adm_permitted_opens(struct ssh *ssh)
 {
-	int i;
+	struct ssh_channels *sc = ssh->chanctxt;
 
-	for (i = 0; i < num_adm_permitted_opens; i++) {
-		free(permitted_adm_opens[i].host_to_connect);
-		free(permitted_adm_opens[i].listen_host);
-		free(permitted_adm_opens[i].listen_path);
-	}
-	free(permitted_adm_opens);
-	permitted_adm_opens = NULL;
-	num_adm_permitted_opens = 0;
-}
-
-void
-channel_print_adm_permitted_opens(void)
-{
-	int i;
-
-	printf("permitopen");
-	if (num_adm_permitted_opens == 0) {
-		printf(" any\n");
-		return;
-	}
-	for (i = 0; i < num_adm_permitted_opens; i++)
-		if (permitted_adm_opens[i].host_to_connect == NULL)
-			printf(" none");
-		else
-			printf(" %s:%d", permitted_adm_opens[i].host_to_connect,
-			    permitted_adm_opens[i].port_to_connect);
-	printf("\n");
+	sc->permitted_adm_opens = xrecallocarray(sc->permitted_adm_opens,
+	    sc->num_adm_permitted_opens, 0, sizeof(*sc->permitted_adm_opens));
+	sc->num_adm_permitted_opens = 0;
 }
 
 /* returns port number, FWD_PERMIT_ANY_PORT or -1 on error */
@@ -3599,7 +3851,8 @@
 {
 	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 @@
  * 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 @@
 		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 @@
 		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 @@
 
 /* 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 @@
  * 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;
+	struct ssh_channels *sc = ssh->chanctxt;
+	u_int i;
+	ForwardPermission *fp;
 
-	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);
+	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 *
-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;
+	struct ssh_channels *sc = ssh->chanctxt;
+	u_int i;
+	ForwardPermission *fp;
 
-	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);
+	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 @@
 
 /* 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 @@
 			*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 @@
 		    "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 @@
  * 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 @@
 	    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 @@
 			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 @@
 	*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 @@
 
 	/* Return the display number for the DISPLAY environment variable. */
 	*display_numberp = display_number;
-	return (0);
+	return 0;
 }
 
 static int
@@ -4039,7 +4318,7 @@
 #endif
 
 int
-x11_connect_display(void)
+x11_connect_display(struct ssh *ssh)
 {
 	u_int display_number;
 	const char *display;
@@ -4084,9 +4363,10 @@
 	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 @@
 		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 @@
 
 	/* 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 @@
 	}
 	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 @@
  * 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 @@
 	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);
 }