Revert part of 180714 - the intent was to flatten dist, not to nuke it.

1 files changed, 3227 insertions, 0 deletions

diff --git a/crypto/openssh/channels.c b/crypto/openssh/channels.c
new file mode 100644
index 0000000..26b63a1
--- /dev/null
+++ b/crypto/openssh/channels.c
@@ -0,0 +1,3227 @@
+/* $OpenBSD: channels.c,v 1.266 2006/08/29 10:40:18 djm Exp $ */
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * This file contains functions for generic socket connection forwarding.
+ * There is also code for initiating connection forwarding for X11 connections,
+ * arbitrary tcp/ip connections, and the authentication agent connection.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ *
+ * SSH2 support added by Markus Friedl.
+ * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
+ * Copyright (c) 1999 Dug Song.  All rights reserved.
+ * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/un.h>
+#include <sys/socket.h>
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h>
+#endif
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <errno.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+#include <unistd.h>
+#include <stdarg.h>
+
+#include "xmalloc.h"
+#include "ssh.h"
+#include "ssh1.h"
+#include "ssh2.h"
+#include "packet.h"
+#include "log.h"
+#include "misc.h"
+#include "buffer.h"
+#include "channels.h"
+#include "compat.h"
+#include "canohost.h"
+#include "key.h"
+#include "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;
+
+
+/* -- tcp forwarding */
+
+/*
+ * Data structure for storing which hosts are permitted for forward requests.
+ * The local sides of any remote forwards are stored in this array to prevent
+ * a corrupt remote server from accessing arbitrary TCP/IP ports on our local
+ * network (which might be behind a firewall).
+ */
+typedef struct {
+	char *host_to_connect;		/* Connect to 'host'. */
+	u_short port_to_connect;	/* Connect to 'port'. */
+	u_short listen_port;		/* Remote side should listen port number. */
+} ForwardPermission;
+
+/* List of all permitted host/port pairs to connect by the user. */
+static ForwardPermission permitted_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
+
+/* List of all permitted host/port pairs to connect by the admin. */
+static ForwardPermission permitted_adm_opens[SSH_MAX_FORWARDS_PER_DIRECTION];
+
+/* Number of permitted host/port pairs in the array permitted by the user. */
+static int num_permitted_opens = 0;
+
+/* Number of permitted host/port pair in the array permitted by the admin. */
+static int num_adm_permitted_opens = 0;
+
+/*
+ * 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;
+
+
+/* -- X11 forwarding */
+
+/* Maximum number of fake X11 displays to try. */
+#define MAX_DISPLAYS  1000
+
+/* Saved X11 local (client) display. */
+static char *x11_saved_display = NULL;
+
+/* Saved X11 authentication protocol name. */
+static char *x11_saved_proto = NULL;
+
+/* Saved X11 authentication data.  This is the real data. */
+static char *x11_saved_data = NULL;
+static u_int x11_saved_data_len = 0;
+
+/*
+ * 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;
+
+
+/* -- agent forwarding */
+
+#define	NUM_SOCKS	10
+
+/* AF_UNSPEC or AF_INET or AF_INET6 */
+static int IPv4or6 = AF_UNSPEC;
+
+/* helper */
+static void port_open_helper(Channel *c, char *rtype);
+
+/* -- channel core */
+
+Channel *
+channel_by_id(int id)
+{
+	Channel *c;
+
+	if (id < 0 || (u_int)id >= channels_alloc) {
+		logit("channel_by_id: %d: bad id", id);
+		return NULL;
+	}
+	c = channels[id];
+	if (c == NULL) {
+		logit("channel_by_id: %d: bad id: channel free", id);
+		return NULL;
+	}
+	return c;
+}
+
+/*
+ * Returns the channel if it is allowed to receive protocol messages.
+ * Private channels, like listening sockets, may not receive messages.
+ */
+Channel *
+channel_lookup(int id)
+{
+	Channel *c;
+
+	if ((c = channel_by_id(id)) == NULL)
+		return (NULL);
+
+	switch (c->type) {
+	case SSH_CHANNEL_X11_OPEN:
+	case SSH_CHANNEL_LARVAL:
+	case SSH_CHANNEL_CONNECTING:
+	case SSH_CHANNEL_DYNAMIC:
+	case SSH_CHANNEL_OPENING:
+	case SSH_CHANNEL_OPEN:
+	case SSH_CHANNEL_INPUT_DRAINING:
+	case SSH_CHANNEL_OUTPUT_DRAINING:
+		return (c);
+	}
+	logit("Non-public channel %d, type %d.", id, c->type);
+	return (NULL);
+}
+
+/*
+ * Register filedescriptors for a channel, used when allocating a channel or
+ * 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,
+    int extusage, int nonblock)
+{
+	/* Update the maximum file descriptor value. */
+	channel_max_fd = MAX(channel_max_fd, rfd);
+	channel_max_fd = MAX(channel_max_fd, wfd);
+	channel_max_fd = MAX(channel_max_fd, efd);
+
+	/* XXX set close-on-exec -markus */
+
+	c->rfd = rfd;
+	c->wfd = wfd;
+	c->sock = (rfd == wfd) ? rfd : -1;
+	c->ctl_fd = -1; /* XXX: set elsewhere */
+	c->efd = efd;
+	c->extended_usage = extusage;
+
+	/* XXX ugly hack: nonblock is only set by the server */
+	if (nonblock && isatty(c->rfd)) {
+		debug2("channel %d: rfd %d isatty", c->self, c->rfd);
+		c->isatty = 1;
+		if (!isatty(c->wfd)) {
+			error("channel %d: wfd %d is not a tty?",
+			    c->self, c->wfd);
+		}
+	} else {
+		c->isatty = 0;
+	}
+	c->wfd_isatty = isatty(c->wfd);
+
+	/* enable nonblocking mode */
+	if (nonblock) {
+		if (rfd != -1)
+			set_nonblock(rfd);
+		if (wfd != -1)
+			set_nonblock(wfd);
+		if (efd != -1)
+			set_nonblock(efd);
+	}
+}
+
+/*
+ * Allocate a new channel object and set its type and socket. This will cause
+ * remote_name to be freed.
+ */
+Channel *
+channel_new(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;
+	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) {
+			/* Found a free slot. */
+			found = (int)i;
+			break;
+		}
+	if (found < 0) {
+		/* There are no free slots.  Take last+1 slot and expand the array.  */
+		found = channels_alloc;
+		if (channels_alloc > 10000)
+			fatal("channel_new: internal error: channels_alloc %d "
+			    "too big.", channels_alloc);
+		channels = xrealloc(channels, channels_alloc + 10,
+		    sizeof(Channel *));
+		channels_alloc += 10;
+		debug2("channel: expanding %d", channels_alloc);
+		for (i = found; i < channels_alloc; i++)
+			channels[i] = NULL;
+	}
+	/* 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->ostate = CHAN_OUTPUT_OPEN;
+	c->istate = CHAN_INPUT_OPEN;
+	c->flags = 0;
+	channel_register_fds(c, rfd, wfd, efd, extusage, nonblock);
+	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->confirm = NULL;
+	c->confirm_ctx = NULL;
+	c->input_filter = NULL;
+	c->output_filter = NULL;
+	debug("channel %d: new [%s]", found, remote_name);
+	return c;
+}
+
+static int
+channel_find_maxfd(void)
+{
+	u_int i;
+	int max = 0;
+	Channel *c;
+
+	for (i = 0; i < channels_alloc; i++) {
+		c = channels[i];
+		if (c != NULL) {
+			max = MAX(max, c->rfd);
+			max = MAX(max, c->wfd);
+			max = MAX(max, c->efd);
+		}
+	}
+	return max;
+}
+
+int
+channel_close_fd(int *fdp)
+{
+	int ret = 0, fd = *fdp;
+
+	if (fd != -1) {
+		ret = close(fd);
+		*fdp = -1;
+		if (fd == channel_max_fd)
+			channel_max_fd = channel_find_maxfd();
+	}
+	return ret;
+}
+
+/* Close all channel fd/socket. */
+static void
+channel_close_fds(Channel *c)
+{
+	debug3("channel %d: close_fds r %d w %d e %d c %d",
+	    c->self, c->rfd, c->wfd, c->efd, c->ctl_fd);
+
+	channel_close_fd(&c->sock);
+	channel_close_fd(&c->ctl_fd);
+	channel_close_fd(&c->rfd);
+	channel_close_fd(&c->wfd);
+	channel_close_fd(&c->efd);
+}
+
+/* Free the channel and close its fd/socket. */
+void
+channel_free(Channel *c)
+{
+	char *s;
+	u_int i, n;
+
+	for (n = 0, i = 0; i < channels_alloc; i++)
+		if (channels[i])
+			n++;
+	debug("channel %d: free: %s, nchannels %u", c->self,
+	    c->remote_name ? c->remote_name : "???", n);
+
+	s = channel_open_message();
+	debug3("channel %d: status: %s", c->self, s);
+	xfree(s);
+
+	if (c->sock != -1)
+		shutdown(c->sock, SHUT_RDWR);
+	if (c->ctl_fd != -1)
+		shutdown(c->ctl_fd, SHUT_RDWR);
+	channel_close_fds(c);
+	buffer_free(&c->input);
+	buffer_free(&c->output);
+	buffer_free(&c->extended);
+	if (c->remote_name) {
+		xfree(c->remote_name);
+		c->remote_name = NULL;
+	}
+	channels[c->self] = NULL;
+	xfree(c);
+}
+
+void
+channel_free_all(void)
+{
+	u_int i;
+
+	for (i = 0; i < channels_alloc; i++)
+		if (channels[i] != NULL)
+			channel_free(channels[i]);
+}
+
+/*
+ * Closes the sockets/fds of all channels.  This is used to close extra file
+ * descriptors after a fork.
+ */
+void
+channel_close_all(void)
+{
+	u_int i;
+
+	for (i = 0; i < channels_alloc; i++)
+		if (channels[i] != NULL)
+			channel_close_fds(channels[i]);
+}
+
+/*
+ * Stop listening to channels.
+ */
+void
+channel_stop_listening(void)
+{
+	u_int i;
+	Channel *c;
+
+	for (i = 0; i < channels_alloc; i++) {
+		c = channels[i];
+		if (c != NULL) {
+			switch (c->type) {
+			case SSH_CHANNEL_AUTH_SOCKET:
+			case SSH_CHANNEL_PORT_LISTENER:
+			case SSH_CHANNEL_RPORT_LISTENER:
+			case SSH_CHANNEL_X11_LISTENER:
+				channel_close_fd(&c->sock);
+				channel_free(c);
+				break;
+			}
+		}
+	}
+}
+
+/*
+ * Returns true if no channel has too much buffered data, and false if one or
+ * more channel is overfull.
+ */
+int
+channel_not_very_much_buffered_data(void)
+{
+	u_int i;
+	Channel *c;
+
+	for (i = 0; i < channels_alloc; i++) {
+		c = channels[i];
+		if (c != NULL && c->type == SSH_CHANNEL_OPEN) {
+#if 0
+			if (!compat20 &&
+			    buffer_len(&c->input) > packet_get_maxsize()) {
+				debug2("channel %d: big input buffer %d",
+				    c->self, buffer_len(&c->input));
+				return 0;
+			}
+#endif
+			if (buffer_len(&c->output) > packet_get_maxsize()) {
+				debug2("channel %d: big output buffer %u > %u",
+				    c->self, buffer_len(&c->output),
+				    packet_get_maxsize());
+				return 0;
+			}
+		}
+	}
+	return 1;
+}
+
+/* Returns true if any channel is still open. */
+int
+channel_still_open(void)
+{
+	u_int i;
+	Channel *c;
+
+	for (i = 0; i < channels_alloc; i++) {
+		c = channels[i];
+		if (c == NULL)
+			continue;
+		switch (c->type) {
+		case SSH_CHANNEL_X11_LISTENER:
+		case SSH_CHANNEL_PORT_LISTENER:
+		case SSH_CHANNEL_RPORT_LISTENER:
+		case SSH_CHANNEL_CLOSED:
+		case SSH_CHANNEL_AUTH_SOCKET:
+		case SSH_CHANNEL_DYNAMIC:
+		case SSH_CHANNEL_CONNECTING:
+		case SSH_CHANNEL_ZOMBIE:
+			continue;
+		case SSH_CHANNEL_LARVAL:
+			if (!compat20)
+				fatal("cannot happen: SSH_CHANNEL_LARVAL");
+			continue;
+		case SSH_CHANNEL_OPENING:
+		case SSH_CHANNEL_OPEN:
+		case SSH_CHANNEL_X11_OPEN:
+			return 1;
+		case SSH_CHANNEL_INPUT_DRAINING:
+		case SSH_CHANNEL_OUTPUT_DRAINING:
+			if (!compat13)
+				fatal("cannot happen: OUT_DRAIN");
+			return 1;
+		default:
+			fatal("channel_still_open: bad channel type %d", c->type);
+			/* NOTREACHED */
+		}
+	}
+	return 0;
+}
+
+/* Returns the id of an open channel suitable for keepaliving */
+int
+channel_find_open(void)
+{
+	u_int i;
+	Channel *c;
+
+	for (i = 0; i < channels_alloc; i++) {
+		c = channels[i];
+		if (c == NULL || c->remote_id < 0)
+			continue;
+		switch (c->type) {
+		case SSH_CHANNEL_CLOSED:
+		case SSH_CHANNEL_DYNAMIC:
+		case SSH_CHANNEL_X11_LISTENER:
+		case SSH_CHANNEL_PORT_LISTENER:
+		case SSH_CHANNEL_RPORT_LISTENER:
+		case SSH_CHANNEL_OPENING:
+		case SSH_CHANNEL_CONNECTING:
+		case SSH_CHANNEL_ZOMBIE:
+			continue;
+		case SSH_CHANNEL_LARVAL:
+		case SSH_CHANNEL_AUTH_SOCKET:
+		case SSH_CHANNEL_OPEN:
+		case SSH_CHANNEL_X11_OPEN:
+			return i;
+		case SSH_CHANNEL_INPUT_DRAINING:
+		case SSH_CHANNEL_OUTPUT_DRAINING:
+			if (!compat13)
+				fatal("cannot happen: OUT_DRAIN");
+			return i;
+		default:
+			fatal("channel_find_open: bad channel type %d", c->type);
+			/* NOTREACHED */
+		}
+	}
+	return -1;
+}
+
+
+/*
+ * Returns a message describing the currently open forwarded connections,
+ * suitable for sending to the client.  The message contains crlf pairs for
+ * newlines.
+ */
+char *
+channel_open_message(void)
+{
+	Buffer buffer;
+	Channel *c;
+	char buf[1024], *cp;
+	u_int i;
+
+	buffer_init(&buffer);
+	snprintf(buf, sizeof buf, "The following connections are open:\r\n");
+	buffer_append(&buffer, buf, strlen(buf));
+	for (i = 0; i < channels_alloc; i++) {
+		c = channels[i];
+		if (c == NULL)
+			continue;
+		switch (c->type) {
+		case SSH_CHANNEL_X11_LISTENER:
+		case SSH_CHANNEL_PORT_LISTENER:
+		case SSH_CHANNEL_RPORT_LISTENER:
+		case SSH_CHANNEL_CLOSED:
+		case SSH_CHANNEL_AUTH_SOCKET:
+		case SSH_CHANNEL_ZOMBIE:
+			continue;
+		case SSH_CHANNEL_LARVAL:
+		case SSH_CHANNEL_OPENING:
+		case SSH_CHANNEL_CONNECTING:
+		case SSH_CHANNEL_DYNAMIC:
+		case SSH_CHANNEL_OPEN:
+		case SSH_CHANNEL_X11_OPEN:
+		case SSH_CHANNEL_INPUT_DRAINING:
+		case SSH_CHANNEL_OUTPUT_DRAINING:
+			snprintf(buf, sizeof buf,
+			    "  #%d %.300s (t%d r%d i%d/%d o%d/%d fd %d/%d cfd %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_fd);
+			buffer_append(&buffer, buf, strlen(buf));
+			continue;
+		default:
+			fatal("channel_open_message: bad channel type %d", c->type);
+			/* NOTREACHED */
+		}
+	}
+	buffer_append(&buffer, "\0", 1);
+	cp = xstrdup(buffer_ptr(&buffer));
+	buffer_free(&buffer);
+	return cp;
+}
+
+void
+channel_send_open(int id)
+{
+	Channel *c = channel_lookup(id);
+
+	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();
+}
+
+void
+channel_request_start(int id, char *service, int wantconfirm)
+{
+	Channel *c = channel_lookup(id);
+
+	if (c == NULL) {
+		logit("channel_request_start: %d: unknown channel id", 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);
+}
+
+void
+channel_register_confirm(int id, channel_callback_fn *fn, void *ctx)
+{
+	Channel *c = channel_lookup(id);
+
+	if (c == NULL) {
+		logit("channel_register_comfirm: %d: bad id", id);
+		return;
+	}
+	c->confirm = fn;
+	c->confirm_ctx = ctx;
+}
+
+void
+channel_register_cleanup(int id, channel_callback_fn *fn, int do_close)
+{
+	Channel *c = channel_by_id(id);
+
+	if (c == NULL) {
+		logit("channel_register_cleanup: %d: bad id", id);
+		return;
+	}
+	c->detach_user = fn;
+	c->detach_close = do_close;
+}
+
+void
+channel_cancel_cleanup(int id)
+{
+	Channel *c = channel_by_id(id);
+
+	if (c == NULL) {
+		logit("channel_cancel_cleanup: %d: bad id", id);
+		return;
+	}
+	c->detach_user = NULL;
+	c->detach_close = 0;
+}
+
+void
+channel_register_filter(int id, channel_infilter_fn *ifn,
+    channel_outfilter_fn *ofn)
+{
+	Channel *c = channel_lookup(id);
+
+	if (c == NULL) {
+		logit("channel_register_filter: %d: bad id", id);
+		return;
+	}
+	c->input_filter = ifn;
+	c->output_filter = ofn;
+}
+
+void
+channel_set_fds(int id, int rfd, int wfd, int efd,
+    int extusage, int nonblock, u_int window_max)
+{
+	Channel *c = channel_lookup(id);
+
+	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);
+	c->type = SSH_CHANNEL_OPEN;
+	c->local_window = c->local_window_max = window_max;
+	packet_start(SSH2_MSG_CHANNEL_WINDOW_ADJUST);
+	packet_put_int(c->remote_id);
+	packet_put_int(c->local_window);
+	packet_send();
+}
+
+/*
+ * 'channel_pre*' are called just before select() to add any bits relevant to
+ * channels in the select bitmasks.
+ */
+/*
+ * 'channel_post*': perform any appropriate operations for channels which
+ * have events pending.
+ */
+typedef void chan_fn(Channel *c, fd_set *readset, fd_set *writeset);
+chan_fn *channel_pre[SSH_CHANNEL_MAX_TYPE];
+chan_fn *channel_post[SSH_CHANNEL_MAX_TYPE];
+
+/* ARGSUSED */
+static void
+channel_pre_listener(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)
+{
+	debug3("channel %d: waiting for connection", c->self);
+	FD_SET(c->sock, writeset);
+}
+
+static void
+channel_pre_open_13(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	if (buffer_len(&c->input) < packet_get_maxsize())
+		FD_SET(c->sock, readset);
+	if (buffer_len(&c->output) > 0)
+		FD_SET(c->sock, writeset);
+}
+
+static void
+channel_pre_open(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	u_int limit = compat20 ? c->remote_window : packet_get_maxsize();
+
+	if (c->istate == CHAN_INPUT_OPEN &&
+	    limit > 0 &&
+	    buffer_len(&c->input) < limit &&
+	    buffer_check_alloc(&c->input, CHAN_RBUF))
+		FD_SET(c->rfd, readset);
+	if (c->ostate == CHAN_OUTPUT_OPEN ||
+	    c->ostate == CHAN_OUTPUT_WAIT_DRAIN) {
+		if (buffer_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));
+			else
+				chan_obuf_empty(c);
+		}
+	}
+	/** XXX check close conditions, too */
+	if (compat20 && c->efd != -1) {
+		if (c->extended_usage == CHAN_EXTENDED_WRITE &&
+		    buffer_len(&c->extended) > 0)
+			FD_SET(c->efd, writeset);
+		else if (!(c->flags & CHAN_EOF_SENT) &&
+		    c->extended_usage == CHAN_EXTENDED_READ &&
+		    buffer_len(&c->extended) < c->remote_window)
+			FD_SET(c->efd, readset);
+	}
+	/* XXX: What about efd? races? */
+	if (compat20 && c->ctl_fd != -1 &&
+	    c->istate == CHAN_INPUT_OPEN && c->ostate == CHAN_OUTPUT_OPEN)
+		FD_SET(c->ctl_fd, readset);
+}
+
+/* ARGSUSED */
+static void
+channel_pre_input_draining(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	if (buffer_len(&c->input) == 0) {
+		packet_start(SSH_MSG_CHANNEL_CLOSE);
+		packet_put_int(c->remote_id);
+		packet_send();
+		c->type = SSH_CHANNEL_CLOSED;
+		debug2("channel %d: closing after input drain.", c->self);
+	}
+}
+
+/* ARGSUSED */
+static void
+channel_pre_output_draining(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	if (buffer_len(&c->output) == 0)
+		chan_mark_dead(c);
+	else
+		FD_SET(c->sock, writeset);
+}
+
+/*
+ * This is a special state for X11 authentication spoofing.  An opened X11
+ * connection (when authentication spoofing is being done) remains in this
+ * state until the first packet has been completely read.  The authentication
+ * data in that packet is then substituted by the real data if it matches the
+ * fake data, and the channel is put into normal mode.
+ * XXX All this happens at the client side.
+ * Returns: 0 = need more data, -1 = wrong cookie, 1 = ok
+ */
+static int
+x11_open_helper(Buffer *b)
+{
+	u_char *ucp;
+	u_int proto_len, data_len;
+
+	/* Check if the fixed size part of the packet is in buffer. */
+	if (buffer_len(b) < 12)
+		return 0;
+
+	/* Parse the lengths of variable-length fields. */
+	ucp = buffer_ptr(b);
+	if (ucp[0] == 0x42) {	/* Byte order MSB first. */
+		proto_len = 256 * ucp[6] + ucp[7];
+		data_len = 256 * ucp[8] + ucp[9];
+	} else if (ucp[0] == 0x6c) {	/* Byte order LSB first. */
+		proto_len = ucp[6] + 256 * ucp[7];
+		data_len = ucp[8] + 256 * ucp[9];
+	} else {
+		debug2("Initial X11 packet contains bad byte order byte: 0x%x",
+		    ucp[0]);
+		return -1;
+	}
+
+	/* Check if the whole packet is in buffer. */
+	if (buffer_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) {
+		debug2("X11 connection uses different authentication protocol.");
+		return -1;
+	}
+	/* Check if authentication data matches our fake data. */
+	if (data_len != x11_fake_data_len ||
+	    memcmp(ucp + 12 + ((proto_len + 3) & ~3),
+		x11_fake_data, 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) {
+		error("X11 fake_data_len %d != saved_data_len %d",
+		    x11_fake_data_len, x11_saved_data_len);
+		return -1;
+	}
+	/*
+	 * Received authentication protocol and data match
+	 * our fake data. Substitute the fake data with real
+	 * data.
+	 */
+	memcpy(ucp + 12 + ((proto_len + 3) & ~3),
+	    x11_saved_data, x11_saved_data_len);
+	return 1;
+}
+
+static void
+channel_pre_x11_open_13(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	int ret = x11_open_helper(&c->output);
+
+	if (ret == 1) {
+		/* Start normal processing for the channel. */
+		c->type = SSH_CHANNEL_OPEN;
+		channel_pre_open_13(c, readset, writeset);
+	} else if (ret == -1) {
+		/*
+		 * We have received an X11 connection that has bad
+		 * authentication information.
+		 */
+		logit("X11 connection rejected because of wrong authentication.");
+		buffer_clear(&c->input);
+		buffer_clear(&c->output);
+		channel_close_fd(&c->sock);
+		c->sock = -1;
+		c->type = SSH_CHANNEL_CLOSED;
+		packet_start(SSH_MSG_CHANNEL_CLOSE);
+		packet_put_int(c->remote_id);
+		packet_send();
+	}
+}
+
+static void
+channel_pre_x11_open(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	int ret = x11_open_helper(&c->output);
+
+	/* c->force_drain = 1; */
+
+	if (ret == 1) {
+		c->type = SSH_CHANNEL_OPEN;
+		channel_pre_open(c, readset, writeset);
+	} else if (ret == -1) {
+		logit("X11 connection rejected because of wrong authentication.");
+		debug2("X11 rejected %d i%d/o%d", c->self, c->istate, c->ostate);
+		chan_read_failed(c);
+		buffer_clear(&c->input);
+		chan_ibuf_empty(c);
+		buffer_clear(&c->output);
+		/* for proto v1, the peer will send an IEOF */
+		if (compat20)
+			chan_write_failed(c);
+		else
+			c->type = SSH_CHANNEL_OPEN;
+		debug2("X11 closed %d i%d/o%d", c->self, c->istate, c->ostate);
+	}
+}
+
+/* try to decode a socks4 header */
+/* ARGSUSED */
+static int
+channel_decode_socks4(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	char *p, *host;
+	u_int len, have, i, found;
+	char username[256];
+	struct {
+		u_int8_t version;
+		u_int8_t command;
+		u_int16_t dest_port;
+		struct in_addr dest_addr;
+	} s4_req, s4_rsp;
+
+	debug2("channel %d: decode socks4", c->self);
+
+	have = buffer_len(&c->input);
+	len = sizeof(s4_req);
+	if (have < len)
+		return 0;
+	p = buffer_ptr(&c->input);
+	for (found = 0, i = len; i < have; i++) {
+		if (p[i] == '\0') {
+			found = 1;
+			break;
+		}
+		if (i > 1024) {
+			/* the peer is probably sending garbage */
+			debug("channel %d: decode socks4: too long",
+			    c->self);
+			return -1;
+		}
+	}
+	if (!found)
+		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 = buffer_ptr(&c->input);
+	len = strlen(p);
+	debug2("channel %d: decode socks4: user %s/%d", c->self, p, len);
+	if (len > have)
+		fatal("channel %d: decode socks4: len %d > have %d",
+		    c->self, len, have);
+	strlcpy(username, p, sizeof(username));
+	buffer_consume(&c->input, len);
+	buffer_consume(&c->input, 1);		/* trailing '\0' */
+
+	host = inet_ntoa(s4_req.dest_addr);
+	strlcpy(c->path, host, sizeof(c->path));
+	c->host_port = ntohs(s4_req.dest_port);
+
+	debug2("channel %d: dynamic request: socks4 host %s port %u command %u",
+	    c->self, host, c->host_port, s4_req.command);
+
+	if (s4_req.command != 1) {
+		debug("channel %d: cannot handle: socks4 cn %d",
+		    c->self, s4_req.command);
+		return -1;
+	}
+	s4_rsp.version = 0;			/* vn: 0 for reply */
+	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));
+	return 1;
+}
+
+/* try to decode a socks5 header */
+#define SSH_SOCKS5_AUTHDONE	0x1000
+#define SSH_SOCKS5_NOAUTH	0x00
+#define SSH_SOCKS5_IPV4		0x01
+#define SSH_SOCKS5_DOMAIN	0x03
+#define SSH_SOCKS5_IPV6		0x04
+#define SSH_SOCKS5_CONNECT	0x01
+#define SSH_SOCKS5_SUCCESS	0x00
+
+/* ARGSUSED */
+static int
+channel_decode_socks5(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	struct {
+		u_int8_t version;
+		u_int8_t command;
+		u_int8_t reserved;
+		u_int8_t atyp;
+	} s5_req, s5_rsp;
+	u_int16_t dest_port;
+	u_char *p, dest_addr[255+1];
+	u_int have, need, i, found, nmethods, addrlen, af;
+
+	debug2("channel %d: decode socks5", c->self);
+	p = buffer_ptr(&c->input);
+	if (p[0] != 0x05)
+		return -1;
+	have = buffer_len(&c->input);
+	if (!(c->flags & SSH_SOCKS5_AUTHDONE)) {
+		/* format: ver | nmethods | methods */
+		if (have < 2)
+			return 0;
+		nmethods = p[1];
+		if (have < nmethods + 2)
+			return 0;
+		/* look for method: "NO AUTHENTICATION REQUIRED" */
+		for (found = 0, i = 2 ; i < nmethods + 2; i++) {
+			if (p[i] == SSH_SOCKS5_NOAUTH) {
+				found = 1;
+				break;
+			}
+		}
+		if (!found) {
+			debug("channel %d: method SSH_SOCKS5_NOAUTH not found",
+			    c->self);
+			return -1;
+		}
+		buffer_consume(&c->input, nmethods + 2);
+		buffer_put_char(&c->output, 0x05);		/* version */
+		buffer_put_char(&c->output, SSH_SOCKS5_NOAUTH);	/* method */
+		FD_SET(c->sock, writeset);
+		c->flags |= SSH_SOCKS5_AUTHDONE;
+		debug2("channel %d: socks5 auth done", c->self);
+		return 0;				/* need more */
+	}
+	debug2("channel %d: socks5 post auth", c->self);
+	if (have < sizeof(s5_req)+1)
+		return 0;			/* need more */
+	memcpy(&s5_req, p, sizeof(s5_req));
+	if (s5_req.version != 0x05 ||
+	    s5_req.command != SSH_SOCKS5_CONNECT ||
+	    s5_req.reserved != 0x00) {
+		debug2("channel %d: only socks5 connect supported", c->self);
+		return -1;
+	}
+	switch (s5_req.atyp){
+	case SSH_SOCKS5_IPV4:
+		addrlen = 4;
+		af = AF_INET;
+		break;
+	case SSH_SOCKS5_DOMAIN:
+		addrlen = p[sizeof(s5_req)];
+		af = -1;
+		break;
+	case SSH_SOCKS5_IPV6:
+		addrlen = 16;
+		af = AF_INET6;
+		break;
+	default:
+		debug2("channel %d: bad socks5 atyp %d", c->self, s5_req.atyp);
+		return -1;
+	}
+	need = sizeof(s5_req) + addrlen + 2;
+	if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
+		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, (char *)&dest_addr, addrlen);
+	buffer_get(&c->input, (char *)&dest_port, 2);
+	dest_addr[addrlen] = '\0';
+	if (s5_req.atyp == SSH_SOCKS5_DOMAIN)
+		strlcpy(c->path, (char *)dest_addr, sizeof(c->path));
+	else if (inet_ntop(af, dest_addr, c->path, sizeof(c->path)) == NULL)
+		return -1;
+	c->host_port = ntohs(dest_port);
+
+	debug2("channel %d: dynamic request: socks5 host %s port %u command %u",
+	    c->self, c->path, c->host_port, s5_req.command);
+
+	s5_rsp.version = 0x05;
+	s5_rsp.command = SSH_SOCKS5_SUCCESS;
+	s5_rsp.reserved = 0;			/* ignored */
+	s5_rsp.atyp = SSH_SOCKS5_IPV4;
+	((struct in_addr *)&dest_addr)->s_addr = INADDR_ANY;
+	dest_port = 0;				/* ignored */
+
+	buffer_append(&c->output, &s5_rsp, sizeof(s5_rsp));
+	buffer_append(&c->output, &dest_addr, sizeof(struct in_addr));
+	buffer_append(&c->output, &dest_port, sizeof(dest_port));
+	return 1;
+}
+
+/* dynamic port forwarding */
+static void
+channel_pre_dynamic(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	u_char *p;
+	u_int have;
+	int ret;
+
+	have = buffer_len(&c->input);
+	c->delayed = 0;
+	debug2("channel %d: pre_dynamic: have %d", c->self, have);
+	/* buffer_dump(&c->input); */
+	/* check if the fixed size part of the packet is in buffer. */
+	if (have < 3) {
+		/* need more */
+		FD_SET(c->sock, readset);
+		return;
+	}
+	/* try to guess the protocol */
+	p = buffer_ptr(&c->input);
+	switch (p[0]) {
+	case 0x04:
+		ret = channel_decode_socks4(c, readset, writeset);
+		break;
+	case 0x05:
+		ret = channel_decode_socks5(c, readset, writeset);
+		break;
+	default:
+		ret = -1;
+		break;
+	}
+	if (ret < 0) {
+		chan_mark_dead(c);
+	} else if (ret == 0) {
+		debug2("channel %d: pre_dynamic: need more", c->self);
+		/* need more */
+		FD_SET(c->sock, readset);
+	} else {
+		/* switch to the next state */
+		c->type = SSH_CHANNEL_OPENING;
+		port_open_helper(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 *nc;
+	struct sockaddr addr;
+	int newsock;
+	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, &addr, &addrlen);
+		if (c->single_connection) {
+			debug2("single_connection: closing X11 listener.");
+			channel_close_fd(&c->sock);
+			chan_mark_dead(c);
+		}
+		if (newsock < 0) {
+			error("accept: %.100s", strerror(errno));
+			return;
+		}
+		set_nodelay(newsock);
+		remote_ipaddr = get_peer_ipaddr(newsock);
+		remote_port = get_peer_port(newsock);
+		snprintf(buf, sizeof buf, "X11 connection from %.200s port %d",
+		    remote_ipaddr, remote_port);
+
+		nc = channel_new("accepted x11 socket",
+		    SSH_CHANNEL_OPENING, newsock, newsock, -1,
+		    c->local_window_max, c->local_maxpacket, 0, buf, 1);
+		if (compat20) {
+			packet_start(SSH2_MSG_CHANNEL_OPEN);
+			packet_put_cstring("x11");
+			packet_put_int(nc->self);
+			packet_put_int(nc->local_window_max);
+			packet_put_int(nc->local_maxpacket);
+			/* originator ipaddr and port */
+			packet_put_cstring(remote_ipaddr);
+			if (datafellows & SSH_BUG_X11FWD) {
+				debug2("ssh2 x11 bug compat mode");
+			} else {
+				packet_put_int(remote_port);
+			}
+			packet_send();
+		} else {
+			packet_start(SSH_SMSG_X11_OPEN);
+			packet_put_int(nc->self);
+			if (packet_get_protocol_flags() &
+			    SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
+				packet_put_cstring(buf);
+			packet_send();
+		}
+		xfree(remote_ipaddr);
+	}
+}
+
+static void
+port_open_helper(Channel *c, char *rtype)
+{
+	int direct;
+	char buf[1024];
+	char *remote_ipaddr = get_peer_ipaddr(c->sock);
+	int remote_port = get_peer_port(c->sock);
+
+	direct = (strcmp(rtype, "direct-tcpip") == 0);
+
+	snprintf(buf, sizeof buf,
+	    "%s: listening port %d for %.100s port %d, "
+	    "connect from %.200s port %d",
+	    rtype, c->listening_port, c->path, c->host_port,
+	    remote_ipaddr, remote_port);
+
+	xfree(c->remote_name);
+	c->remote_name = xstrdup(buf);
+
+	if (compat20) {
+		packet_start(SSH2_MSG_CHANNEL_OPEN);
+		packet_put_cstring(rtype);
+		packet_put_int(c->self);
+		packet_put_int(c->local_window_max);
+		packet_put_int(c->local_maxpacket);
+		if (direct) {
+			/* target host, port */
+			packet_put_cstring(c->path);
+			packet_put_int(c->host_port);
+		} else {
+			/* listen address, port */
+			packet_put_cstring(c->path);
+			packet_put_int(c->listening_port);
+		}
+		/* originator host and port */
+		packet_put_cstring(remote_ipaddr);
+		packet_put_int((u_int)remote_port);
+		packet_send();
+	} else {
+		packet_start(SSH_MSG_PORT_OPEN);
+		packet_put_int(c->self);
+		packet_put_cstring(c->path);
+		packet_put_int(c->host_port);
+		if (packet_get_protocol_flags() &
+		    SSH_PROTOFLAG_HOST_IN_FWD_OPEN)
+			packet_put_cstring(c->remote_name);
+		packet_send();
+	}
+	xfree(remote_ipaddr);
+}
+
+static void
+channel_set_reuseaddr(int fd)
+{
+	int on = 1;
+
+	/*
+	 * Set socket options.
+	 * Allow local port reuse in TIME_WAIT.
+	 */
+	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)
+		error("setsockopt SO_REUSEADDR fd %d: %s", fd, strerror(errno));
+}
+
+/*
+ * 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 *nc;
+	struct sockaddr addr;
+	int newsock, nextstate;
+	socklen_t addrlen;
+	char *rtype;
+
+	if (FD_ISSET(c->sock, readset)) {
+		debug("Connection to port %d forwarding "
+		    "to %.100s port %d requested.",
+		    c->listening_port, c->path, c->host_port);
+
+		if (c->type == SSH_CHANNEL_RPORT_LISTENER) {
+			nextstate = SSH_CHANNEL_OPENING;
+			rtype = "forwarded-tcpip";
+		} else {
+			if (c->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, &addr, &addrlen);
+		if (newsock < 0) {
+			error("accept: %.100s", strerror(errno));
+			return;
+		}
+		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;
+		strlcpy(nc->path, c->path, sizeof(nc->path));
+
+		if (nextstate == SSH_CHANNEL_DYNAMIC) {
+			/*
+			 * do not call the channel_post handler until
+			 * this flag has been reset by a pre-handler.
+			 * otherwise the FD_ISSET calls might overflow
+			 */
+			nc->delayed = 1;
+		} else {
+			port_open_helper(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 *nc;
+	int newsock;
+	struct sockaddr addr;
+	socklen_t addrlen;
+
+	if (FD_ISSET(c->sock, readset)) {
+		addrlen = sizeof(addr);
+		newsock = accept(c->sock, &addr, &addrlen);
+		if (newsock < 0) {
+			error("accept from auth socket: %.100s", strerror(errno));
+			return;
+		}
+		nc = channel_new("accepted auth socket",
+		    SSH_CHANNEL_OPENING, newsock, newsock, -1,
+		    c->local_window_max, c->local_maxpacket,
+		    0, "accepted auth socket", 1);
+		if (compat20) {
+			packet_start(SSH2_MSG_CHANNEL_OPEN);
+			packet_put_cstring("auth-agent@openssh.com");
+			packet_put_int(nc->self);
+			packet_put_int(c->local_window_max);
+			packet_put_int(c->local_maxpacket);
+		} else {
+			packet_start(SSH_SMSG_AGENT_OPEN);
+			packet_put_int(nc->self);
+		}
+		packet_send();
+	}
+}
+
+/* ARGSUSED */
+static void
+channel_post_connecting(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	int err = 0;
+	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", c->self);
+			c->type = SSH_CHANNEL_OPEN;
+			if (compat20) {
+				packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
+				packet_put_int(c->remote_id);
+				packet_put_int(c->self);
+				packet_put_int(c->local_window);
+				packet_put_int(c->local_maxpacket);
+			} else {
+				packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
+				packet_put_int(c->remote_id);
+				packet_put_int(c->self);
+			}
+		} else {
+			debug("channel %d: not connected: %s",
+			    c->self, strerror(err));
+			if (compat20) {
+				packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
+				packet_put_int(c->remote_id);
+				packet_put_int(SSH2_OPEN_CONNECT_FAILED);
+				if (!(datafellows & SSH_BUG_OPENFAILURE)) {
+					packet_put_cstring(strerror(err));
+					packet_put_cstring("");
+				}
+			} else {
+				packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+				packet_put_int(c->remote_id);
+			}
+			chan_mark_dead(c);
+		}
+		packet_send();
+	}
+}
+
+/* ARGSUSED */
+static int
+channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	char buf[CHAN_RBUF];
+	int len;
+
+	if (c->rfd != -1 &&
+	    FD_ISSET(c->rfd, readset)) {
+		errno = 0;
+		len = read(c->rfd, buf, sizeof(buf));
+		if (len < 0 && (errno == EINTR || errno == EAGAIN))
+			return 1;
+#ifndef PTY_ZEROREAD
+		if (len <= 0) {
+#else
+		if ((!c->isatty && len <= 0) ||
+		    (c->isatty && (len < 0 || (len == 0 && errno != 0)))) {
+#endif
+			debug2("channel %d: read<=0 rfd %d len %d",
+			    c->self, c->rfd, len);
+			if (c->type != SSH_CHANNEL_OPEN) {
+				debug2("channel %d: not open", c->self);
+				chan_mark_dead(c);
+				return -1;
+			} else if (compat13) {
+				buffer_clear(&c->output);
+				c->type = SSH_CHANNEL_INPUT_DRAINING;
+				debug2("channel %d: input draining.", c->self);
+			} else {
+				chan_read_failed(c);
+			}
+			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);
+		}
+	}
+	return 1;
+}
+
+/* ARGSUSED */
+static int
+channel_handle_wfd(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	struct termios tio;
+	u_char *data = NULL, *buf;
+	u_int dlen;
+	int len;
+
+	/* Send buffered output data to the socket. */
+	if (c->wfd != -1 &&
+	    FD_ISSET(c->wfd, writeset) &&
+	    buffer_len(&c->output) > 0) {
+		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 */
+			c->local_consumed += dlen + 4;
+			len = write(c->wfd, buf, dlen);
+			xfree(data);
+			if (len < 0 && (errno == EINTR || errno == EAGAIN))
+				return 1;
+			if (len <= 0) {
+				if (c->type != SSH_CHANNEL_OPEN)
+					chan_mark_dead(c);
+				else
+					chan_write_failed(c);
+				return -1;
+			}
+			return 1;
+		}
+#ifdef _AIX
+		/* XXX: Later AIX versions can't push as much data to tty */
+		if (compat20 && c->wfd_isatty)
+			dlen = MIN(dlen, 8*1024);
+#endif
+
+		len = write(c->wfd, buf, dlen);
+		if (len < 0 && (errno == EINTR || errno == EAGAIN))
+			return 1;
+		if (len <= 0) {
+			if (c->type != SSH_CHANNEL_OPEN) {
+				debug2("channel %d: not open", c->self);
+				chan_mark_dead(c);
+				return -1;
+			} else if (compat13) {
+				buffer_clear(&c->output);
+				debug2("channel %d: input draining.", c->self);
+				c->type = SSH_CHANNEL_INPUT_DRAINING;
+			} else {
+				chan_write_failed(c);
+			}
+			return -1;
+		}
+		if (compat20 && c->isatty && dlen >= 1 && buf[0] != '\r') {
+			if (tcgetattr(c->wfd, &tio) == 0 &&
+			    !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
+				/*
+				 * Simulate echo to reduce the impact of
+				 * traffic analysis. We need to match the
+				 * size of a SSH2_MSG_CHANNEL_DATA message
+				 * (4 byte channel id + buf)
+				 */
+				packet_send_ignore(4 + len);
+				packet_send();
+			}
+		}
+		buffer_consume(&c->output, len);
+		if (compat20 && len > 0) {
+			c->local_consumed += len;
+		}
+	}
+	return 1;
+}
+
+static int
+channel_handle_efd(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	char buf[CHAN_RBUF];
+	int 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))
+				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->extended_usage == CHAN_EXTENDED_READ &&
+		    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))
+				return 1;
+			if (len <= 0) {
+				debug2("channel %d: closing read-efd %d",
+				    c->self, c->efd);
+				channel_close_fd(&c->efd);
+			} else {
+				buffer_append(&c->extended, buf, len);
+			}
+		}
+	}
+	return 1;
+}
+
+/* ARGSUSED */
+static int
+channel_handle_ctl(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	char buf[16];
+	int len;
+
+	/* Monitor control fd to detect if the slave client exits */
+	if (c->ctl_fd != -1 && FD_ISSET(c->ctl_fd, readset)) {
+		len = read(c->ctl_fd, buf, sizeof(buf));
+		if (len < 0 && (errno == EINTR || errno == EAGAIN))
+			return 1;
+		if (len <= 0) {
+			debug2("channel %d: ctl read<=0", c->self);
+			if (c->type != SSH_CHANNEL_OPEN) {
+				debug2("channel %d: not open", c->self);
+				chan_mark_dead(c);
+				return -1;
+			} else {
+				chan_read_failed(c);
+				chan_write_failed(c);
+			}
+			return -1;
+		} else
+			fatal("%s: unexpected data on ctl fd", __func__);
+	}
+	return 1;
+}
+
+static int
+channel_check_window(Channel *c)
+{
+	if (c->type == SSH_CHANNEL_OPEN &&
+	    !(c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD)) &&
+	    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();
+		debug2("channel %d: window %d sent adjust %d",
+		    c->self, c->local_window,
+		    c->local_consumed);
+		c->local_window += c->local_consumed;
+		c->local_consumed = 0;
+	}
+	return 1;
+}
+
+static void
+channel_post_open(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	if (c->delayed)
+		return;
+	channel_handle_rfd(c, readset, writeset);
+	channel_handle_wfd(c, readset, writeset);
+	if (!compat20)
+		return;
+	channel_handle_efd(c, readset, writeset);
+	channel_handle_ctl(c, readset, writeset);
+	channel_check_window(c);
+}
+
+/* ARGSUSED */
+static void
+channel_post_output_drain_13(Channel *c, fd_set *readset, fd_set *writeset)
+{
+	int len;
+
+	/* Send buffered output data to the socket. */
+	if (FD_ISSET(c->sock, writeset) && buffer_len(&c->output) > 0) {
+		len = write(c->sock, buffer_ptr(&c->output),
+			    buffer_len(&c->output));
+		if (len <= 0)
+			buffer_clear(&c->output);
+		else
+			buffer_consume(&c->output, len);
+	}
+}
+
+static void
+channel_handler_init_20(void)
+{
+	channel_pre[SSH_CHANNEL_OPEN] =			&channel_pre_open;
+	channel_pre[SSH_CHANNEL_X11_OPEN] =		&channel_pre_x11_open;
+	channel_pre[SSH_CHANNEL_PORT_LISTENER] =	&channel_pre_listener;
+	channel_pre[SSH_CHANNEL_RPORT_LISTENER] =	&channel_pre_listener;
+	channel_pre[SSH_CHANNEL_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_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_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;
+}
+
+static void
+channel_handler_init_13(void)
+{
+	channel_pre[SSH_CHANNEL_OPEN] =			&channel_pre_open_13;
+	channel_pre[SSH_CHANNEL_X11_OPEN] =		&channel_pre_x11_open_13;
+	channel_pre[SSH_CHANNEL_X11_LISTENER] =		&channel_pre_listener;
+	channel_pre[SSH_CHANNEL_PORT_LISTENER] =	&channel_pre_listener;
+	channel_pre[SSH_CHANNEL_AUTH_SOCKET] =		&channel_pre_listener;
+	channel_pre[SSH_CHANNEL_INPUT_DRAINING] =	&channel_pre_input_draining;
+	channel_pre[SSH_CHANNEL_OUTPUT_DRAINING] =	&channel_pre_output_draining;
+	channel_pre[SSH_CHANNEL_CONNECTING] =		&channel_pre_connecting;
+	channel_pre[SSH_CHANNEL_DYNAMIC] =		&channel_pre_dynamic;
+
+	channel_post[SSH_CHANNEL_OPEN] =		&channel_post_open;
+	channel_post[SSH_CHANNEL_X11_LISTENER] =	&channel_post_x11_listener;
+	channel_post[SSH_CHANNEL_PORT_LISTENER] =	&channel_post_port_listener;
+	channel_post[SSH_CHANNEL_AUTH_SOCKET] =		&channel_post_auth_listener;
+	channel_post[SSH_CHANNEL_OUTPUT_DRAINING] =	&channel_post_output_drain_13;
+	channel_post[SSH_CHANNEL_CONNECTING] =		&channel_post_connecting;
+	channel_post[SSH_CHANNEL_DYNAMIC] =		&channel_post_open;
+}
+
+static void
+channel_handler_init_15(void)
+{
+	channel_pre[SSH_CHANNEL_OPEN] =			&channel_pre_open;
+	channel_pre[SSH_CHANNEL_X11_OPEN] =		&channel_pre_x11_open;
+	channel_pre[SSH_CHANNEL_X11_LISTENER] =		&channel_pre_listener;
+	channel_pre[SSH_CHANNEL_PORT_LISTENER] =	&channel_pre_listener;
+	channel_pre[SSH_CHANNEL_AUTH_SOCKET] =		&channel_pre_listener;
+	channel_pre[SSH_CHANNEL_CONNECTING] =		&channel_pre_connecting;
+	channel_pre[SSH_CHANNEL_DYNAMIC] =		&channel_pre_dynamic;
+
+	channel_post[SSH_CHANNEL_X11_LISTENER] =	&channel_post_x11_listener;
+	channel_post[SSH_CHANNEL_PORT_LISTENER] =	&channel_post_port_listener;
+	channel_post[SSH_CHANNEL_AUTH_SOCKET] =		&channel_post_auth_listener;
+	channel_post[SSH_CHANNEL_OPEN] =		&channel_post_open;
+	channel_post[SSH_CHANNEL_CONNECTING] =		&channel_post_connecting;
+	channel_post[SSH_CHANNEL_DYNAMIC] =		&channel_post_open;
+}
+
+static void
+channel_handler_init(void)
+{
+	int i;
+
+	for (i = 0; i < SSH_CHANNEL_MAX_TYPE; i++) {
+		channel_pre[i] = NULL;
+		channel_post[i] = NULL;
+	}
+	if (compat20)
+		channel_handler_init_20();
+	else if (compat13)
+		channel_handler_init_13();
+	else
+		channel_handler_init_15();
+}
+
+/* gc dead channels */
+static void
+channel_garbage_collect(Channel *c)
+{
+	if (c == NULL)
+		return;
+	if (c->detach_user != NULL) {
+		if (!chan_is_dead(c, c->detach_close))
+			return;
+		debug2("channel %d: gc: notify user", c->self);
+		c->detach_user(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))
+		return;
+	debug2("channel %d: garbage collecting", c->self);
+	channel_free(c);
+}
+
+static void
+channel_handler(chan_fn *ftab[], fd_set *readset, fd_set *writeset)
+{
+	static int did_init = 0;
+	u_int i;
+	Channel *c;
+
+	if (!did_init) {
+		channel_handler_init();
+		did_init = 1;
+	}
+	for (i = 0; i < channels_alloc; i++) {
+		c = channels[i];
+		if (c == NULL)
+			continue;
+		if (ftab[c->type] != NULL)
+			(*ftab[c->type])(c, readset, writeset);
+		channel_garbage_collect(c);
+	}
+}
+
+/*
+ * Allocate/update select bitmasks and add any bits relevant to channels in
+ * select bitmasks.
+ */
+void
+channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
+    u_int *nallocp, int rekeying)
+{
+	u_int n, sz, nfdset;
+
+	n = MAX(*maxfdp, channel_max_fd);
+
+	nfdset = howmany(n+1, NFDBITS);
+	/* Explicitly test here, because xrealloc isn't always called */
+	if (nfdset && SIZE_T_MAX / nfdset < sizeof(fd_mask))
+		fatal("channel_prepare_select: max_fd (%d) is too large", n);
+	sz = nfdset * sizeof(fd_mask);
+
+	/* perhaps check sz < nalloc/2 and shrink? */
+	if (*readsetp == NULL || sz > *nallocp) {
+		*readsetp = xrealloc(*readsetp, nfdset, sizeof(fd_mask));
+		*writesetp = xrealloc(*writesetp, nfdset, sizeof(fd_mask));
+		*nallocp = sz;
+	}
+	*maxfdp = n;
+	memset(*readsetp, 0, sz);
+	memset(*writesetp, 0, sz);
+
+	if (!rekeying)
+		channel_handler(channel_pre, *readsetp, *writesetp);
+}
+
+/*
+ * After select, perform any appropriate operations for channels which have
+ * events pending.
+ */
+void
+channel_after_select(fd_set *readset, fd_set *writeset)
+{
+	channel_handler(channel_post, readset, writeset);
+}
+
+
+/* If there is data to send to the connection, enqueue some of it now. */
+void
+channel_output_poll(void)
+{
+	Channel *c;
+	u_int i, len;
+
+	for (i = 0; i < channels_alloc; i++) {
+		c = channels[i];
+		if (c == NULL)
+			continue;
+
+		/*
+		 * We are only interested in channels that can have buffered
+		 * incoming data.
+		 */
+		if (compat13) {
+			if (c->type != SSH_CHANNEL_OPEN &&
+			    c->type != SSH_CHANNEL_INPUT_DRAINING)
+				continue;
+		} else {
+			if (c->type != SSH_CHANNEL_OPEN)
+				continue;
+		}
+		if (compat20 &&
+		    (c->flags & (CHAN_CLOSE_SENT|CHAN_CLOSE_RCVD))) {
+			/* XXX is this true? */
+			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);
+					packet_start(SSH2_MSG_CHANNEL_DATA);
+					packet_put_int(c->remote_id);
+					packet_put_string(data, dlen);
+					packet_send();
+					c->remote_window -= dlen + 4;
+					xfree(data);
+				}
+				continue;
+			}
+			/*
+			 * Send some data for the other side over the secure
+			 * connection.
+			 */
+			if (compat20) {
+				if (len > c->remote_window)
+					len = c->remote_window;
+				if (len > c->remote_maxpacket)
+					len = c->remote_maxpacket;
+			} else {
+				if (packet_is_interactive()) {
+					if (len > 1024)
+						len = 512;
+				} else {
+					/* Keep the packets at reasonable size. */
+					if (len > packet_get_maxsize()/2)
+						len = packet_get_maxsize()/2;
+				}
+			}
+			if (len > 0) {
+				packet_start(compat20 ?
+				    SSH2_MSG_CHANNEL_DATA : SSH_MSG_CHANNEL_DATA);
+				packet_put_int(c->remote_id);
+				packet_put_string(buffer_ptr(&c->input), len);
+				packet_send();
+				buffer_consume(&c->input, len);
+				c->remote_window -= len;
+			}
+		} else if (c->istate == CHAN_INPUT_WAIT_DRAIN) {
+			if (compat13)
+				fatal("cannot happen: istate == INPUT_WAIT_DRAIN for proto 1.3");
+			/*
+			 * input-buffer is empty and read-socket shutdown:
+			 * tell peer, that we will not send more data: send IEOF.
+			 * hack for extended data: delay EOF if EFD still in use.
+			 */
+			if (CHANNEL_EFD_INPUT_ACTIVE(c))
+				debug2("channel %d: ibuf_empty delayed efd %d/(%d)",
+				    c->self, c->efd, buffer_len(&c->extended));
+			else
+				chan_ibuf_empty(c);
+		}
+		/* Send extended data, i.e. stderr */
+		if (compat20 &&
+		    !(c->flags & CHAN_EOF_SENT) &&
+		    c->remote_window > 0 &&
+		    (len = buffer_len(&c->extended)) > 0 &&
+		    c->extended_usage == CHAN_EXTENDED_READ) {
+			debug2("channel %d: rwin %u elen %u euse %d",
+			    c->self, c->remote_window, buffer_len(&c->extended),
+			    c->extended_usage);
+			if (len > c->remote_window)
+				len = c->remote_window;
+			if (len > c->remote_maxpacket)
+				len = c->remote_maxpacket;
+			packet_start(SSH2_MSG_CHANNEL_EXTENDED_DATA);
+			packet_put_int(c->remote_id);
+			packet_put_int(SSH2_EXTENDED_DATA_STDERR);
+			packet_put_string(buffer_ptr(&c->extended), len);
+			packet_send();
+			buffer_consume(&c->extended, len);
+			c->remote_window -= len;
+			debug2("channel %d: sent ext data %d", c->self, len);
+		}
+	}
+}
+
+
+/* -- protocol input */
+
+/* ARGSUSED */
+void
+channel_input_data(int type, u_int32_t seq, void *ctxt)
+{
+	int id;
+	char *data;
+	u_int data_len;
+	Channel *c;
+
+	/* 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);
+
+	/* Ignore any data for non-open channels (might happen on close) */
+	if (c->type != SSH_CHANNEL_OPEN &&
+	    c->type != SSH_CHANNEL_X11_OPEN)
+		return;
+
+	/* Get the data. */
+	data = packet_get_string(&data_len);
+
+	/*
+	 * 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.
+	 */
+	if (!compat13 && c->ostate != CHAN_OUTPUT_OPEN) {
+		if (compat20) {
+			c->local_window -= data_len;
+			c->local_consumed += data_len;
+		}
+		xfree(data);
+		return;
+	}
+
+	if (compat20) {
+		if (data_len > c->local_maxpacket) {
+			logit("channel %d: rcvd big packet %d, maxpack %d",
+			    c->self, data_len, c->local_maxpacket);
+		}
+		if (data_len > c->local_window) {
+			logit("channel %d: rcvd too much data %d, win %d",
+			    c->self, data_len, c->local_window);
+			xfree(data);
+			return;
+		}
+		c->local_window -= data_len;
+	}
+	packet_check_eom();
+	if (c->datagram)
+		buffer_put_string(&c->output, data, data_len);
+	else
+		buffer_append(&c->output, data, data_len);
+	xfree(data);
+}
+
+/* ARGSUSED */
+void
+channel_input_extended_data(int type, u_int32_t seq, void *ctxt)
+{
+	int id;
+	char *data;
+	u_int data_len, tcode;
+	Channel *c;
+
+	/* Get the channel number and verify it. */
+	id = packet_get_int();
+	c = channel_lookup(id);
+
+	if (c == NULL)
+		packet_disconnect("Received extended_data for bad channel %d.", id);
+	if (c->type != SSH_CHANNEL_OPEN) {
+		logit("channel %d: ext data for non open", id);
+		return;
+	}
+	if (c->flags & CHAN_EOF_RCVD) {
+		if (datafellows & SSH_BUG_EXTEOF)
+			debug("channel %d: accepting ext data after eof", id);
+		else
+			packet_disconnect("Received extended_data after EOF "
+			    "on channel %d.", id);
+	}
+	tcode = packet_get_int();
+	if (c->efd == -1 ||
+	    c->extended_usage != CHAN_EXTENDED_WRITE ||
+	    tcode != SSH2_EXTENDED_DATA_STDERR) {
+		logit("channel %d: bad ext data", c->self);
+		return;
+	}
+	data = packet_get_string(&data_len);
+	packet_check_eom();
+	if (data_len > c->local_window) {
+		logit("channel %d: rcvd too much extended_data %d, win %d",
+		    c->self, data_len, c->local_window);
+		xfree(data);
+		return;
+	}
+	debug2("channel %d: rcvd ext data %d", c->self, data_len);
+	c->local_window -= data_len;
+	buffer_append(&c->extended, data, data_len);
+	xfree(data);
+}
+
+/* ARGSUSED */
+void
+channel_input_ieof(int type, u_int32_t seq, void *ctxt)
+{
+	int id;
+	Channel *c;
+
+	id = packet_get_int();
+	packet_check_eom();
+	c = channel_lookup(id);
+	if (c == NULL)
+		packet_disconnect("Received ieof for nonexistent channel %d.", id);
+	chan_rcvd_ieof(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);
+	}
+
+}
+
+/* ARGSUSED */
+void
+channel_input_close(int type, u_int32_t seq, void *ctxt)
+{
+	int id;
+	Channel *c;
+
+	id = packet_get_int();
+	packet_check_eom();
+	c = channel_lookup(id);
+	if (c == NULL)
+		packet_disconnect("Received close for nonexistent channel %d.", id);
+
+	/*
+	 * Send a confirmation that we have closed the channel and no more
+	 * data is coming for it.
+	 */
+	packet_start(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION);
+	packet_put_int(c->remote_id);
+	packet_send();
+
+	/*
+	 * If the channel is in closed state, we have sent a close request,
+	 * and the other side will eventually respond with a confirmation.
+	 * Thus, we cannot free the channel here, because then there would be
+	 * no-one to receive the confirmation.  The channel gets freed when
+	 * the confirmation arrives.
+	 */
+	if (c->type != SSH_CHANNEL_CLOSED) {
+		/*
+		 * Not a closed channel - mark it as draining, which will
+		 * cause it to be freed later.
+		 */
+		buffer_clear(&c->input);
+		c->type = SSH_CHANNEL_OUTPUT_DRAINING;
+	}
+}
+
+/* proto version 1.5 overloads CLOSE_CONFIRMATION with OCLOSE */
+/* ARGSUSED */
+void
+channel_input_oclose(int type, u_int32_t seq, void *ctxt)
+{
+	int id = packet_get_int();
+	Channel *c = channel_lookup(id);
+
+	packet_check_eom();
+	if (c == NULL)
+		packet_disconnect("Received oclose for nonexistent channel %d.", id);
+	chan_rcvd_oclose(c);
+}
+
+/* ARGSUSED */
+void
+channel_input_close_confirmation(int type, u_int32_t seq, void *ctxt)
+{
+	int id = packet_get_int();
+	Channel *c = channel_lookup(id);
+
+	packet_check_eom();
+	if (c == NULL)
+		packet_disconnect("Received close confirmation for "
+		    "out-of-range channel %d.", id);
+	if (c->type != SSH_CHANNEL_CLOSED)
+		packet_disconnect("Received close confirmation for "
+		    "non-closed channel %d (type %d).", id, c->type);
+	channel_free(c);
+}
+
+/* ARGSUSED */
+void
+channel_input_open_confirmation(int type, u_int32_t seq, void *ctxt)
+{
+	int id, remote_id;
+	Channel *c;
+
+	id = packet_get_int();
+	c = channel_lookup(id);
+
+	if (c==NULL || c->type != SSH_CHANNEL_OPENING)
+		packet_disconnect("Received open confirmation for "
+		    "non-opening channel %d.", id);
+	remote_id = packet_get_int();
+	/* Record the remote channel number and mark that the channel is now open. */
+	c->remote_id = remote_id;
+	c->type = SSH_CHANNEL_OPEN;
+
+	if (compat20) {
+		c->remote_window = packet_get_int();
+		c->remote_maxpacket = packet_get_int();
+		if (c->confirm) {
+			debug2("callback start");
+			c->confirm(c->self, c->confirm_ctx);
+			debug2("callback done");
+		}
+		debug2("channel %d: open confirm rwindow %u rmax %u", c->self,
+		    c->remote_window, c->remote_maxpacket);
+	}
+	packet_check_eom();
+}
+
+static char *
+reason2txt(int reason)
+{
+	switch (reason) {
+	case SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED:
+		return "administratively prohibited";
+	case SSH2_OPEN_CONNECT_FAILED:
+		return "connect failed";
+	case SSH2_OPEN_UNKNOWN_CHANNEL_TYPE:
+		return "unknown channel type";
+	case SSH2_OPEN_RESOURCE_SHORTAGE:
+		return "resource shortage";
+	}
+	return "unknown reason";
+}
+
+/* ARGSUSED */
+void
+channel_input_open_failure(int type, u_int32_t seq, void *ctxt)
+{
+	int id, reason;
+	char *msg = NULL, *lang = NULL;
+	Channel *c;
+
+	id = packet_get_int();
+	c = channel_lookup(id);
+
+	if (c==NULL || c->type != SSH_CHANNEL_OPENING)
+		packet_disconnect("Received open failure for "
+		    "non-opening channel %d.", id);
+	if (compat20) {
+		reason = packet_get_int();
+		if (!(datafellows & SSH_BUG_OPENFAILURE)) {
+			msg  = packet_get_string(NULL);
+			lang = packet_get_string(NULL);
+		}
+		logit("channel %d: open failed: %s%s%s", id,
+		    reason2txt(reason), msg ? ": ": "", msg ? msg : "");
+		if (msg != NULL)
+			xfree(msg);
+		if (lang != NULL)
+			xfree(lang);
+	}
+	packet_check_eom();
+	/* Free the channel.  This will also close the socket. */
+	channel_free(c);
+}
+
+/* ARGSUSED */
+void
+channel_input_window_adjust(int type, u_int32_t seq, void *ctxt)
+{
+	Channel *c;
+	int id;
+	u_int adjust;
+
+	if (!compat20)
+		return;
+
+	/* Get the channel number and verify it. */
+	id = packet_get_int();
+	c = channel_lookup(id);
+
+	if (c == NULL) {
+		logit("Received window adjust for non-open channel %d.", id);
+		return;
+	}
+	adjust = packet_get_int();
+	packet_check_eom();
+	debug2("channel %d: rcvd adjust %u", id, adjust);
+	c->remote_window += adjust;
+}
+
+/* ARGSUSED */
+void
+channel_input_port_open(int type, u_int32_t seq, void *ctxt)
+{
+	Channel *c = NULL;
+	u_short host_port;
+	char *host, *originator_string;
+	int remote_id, sock = -1;
+
+	remote_id = packet_get_int();
+	host = packet_get_string(NULL);
+	host_port = packet_get_int();
+
+	if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
+		originator_string = packet_get_string(NULL);
+	} else {
+		originator_string = xstrdup("unknown (remote did not supply name)");
+	}
+	packet_check_eom();
+	sock = channel_connect_to(host, host_port);
+	if (sock != -1) {
+		c = channel_new("connected socket",
+		    SSH_CHANNEL_CONNECTING, sock, sock, -1, 0, 0, 0,
+		    originator_string, 1);
+		c->remote_id = remote_id;
+	}
+	xfree(originator_string);
+	if (c == NULL) {
+		packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+		packet_put_int(remote_id);
+		packet_send();
+	}
+	xfree(host);
+}
+
+
+/* -- tcp forwarding */
+
+void
+channel_set_af(int af)
+{
+	IPv4or6 = af;
+}
+
+static int
+channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
+    const char *host_to_connect, u_short port_to_connect, int gateway_ports)
+{
+	Channel *c;
+	int sock, r, success = 0, wildcard = 0, is_client;
+	struct addrinfo hints, *ai, *aitop;
+	const char *host, *addr;
+	char ntop[NI_MAXHOST], strport[NI_MAXSERV];
+
+	host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
+	    listen_addr : host_to_connect;
+	is_client = (type == SSH_CHANNEL_PORT_LISTENER);
+
+	if (host == NULL) {
+		error("No forward host name.");
+		return 0;
+	}
+	if (strlen(host) > SSH_CHANNEL_PATH_LEN - 1) {
+		error("Forward host name too long.");
+		return 0;
+	}
+
+	/*
+	 * Determine whether or not a port forward listens to loopback,
+	 * specified address or wildcard. On the client, a specified bind
+	 * address will always override gateway_ports. On the server, a
+	 * gateway_ports of 1 (``yes'') will override the client's
+	 * specification and force a wildcard bind, whereas a value of 2
+	 * (``clientspecified'') will bind to whatever address the client
+	 * asked for.
+	 *
+	 * Special-case listen_addrs are:
+	 *
+	 * "0.0.0.0"               -> wildcard v4/v6 if SSH_OLD_FORWARD_ADDR
+	 * "" (empty string), "*"  -> wildcard v4/v6
+	 * "localhost"             -> loopback v4/v6
+	 */
+	addr = NULL;
+	if (listen_addr == NULL) {
+		/* No address specified: default to gateway_ports setting */
+		if (gateway_ports)
+			wildcard = 1;
+	} else if (gateway_ports || is_client) {
+		if (((datafellows & SSH_OLD_FORWARD_ADDR) &&
+		    strcmp(listen_addr, "0.0.0.0") == 0) ||
+		    *listen_addr == '\0' || strcmp(listen_addr, "*") == 0 ||
+		    (!is_client && gateway_ports == 1))
+			wildcard = 1;
+		else if (strcmp(listen_addr, "localhost") != 0)
+			addr = listen_addr;
+	}
+
+	debug3("channel_setup_fwd_listener: type %d wildcard %d addr %s",
+	    type, wildcard, (addr == NULL) ? "NULL" : addr);
+
+	/*
+	 * getaddrinfo returns a loopback address if the hostname is
+	 * set to NULL and hints.ai_flags is not AI_PASSIVE
+	 */
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = IPv4or6;
+	hints.ai_flags = wildcard ? AI_PASSIVE : 0;
+	hints.ai_socktype = SOCK_STREAM;
+	snprintf(strport, sizeof strport, "%d", listen_port);
+	if ((r = getaddrinfo(addr, strport, &hints, &aitop)) != 0) {
+		if (addr == NULL) {
+			/* This really shouldn't happen */
+			packet_disconnect("getaddrinfo: fatal error: %s",
+			    gai_strerror(r));
+		} else {
+			error("channel_setup_fwd_listener: "
+			    "getaddrinfo(%.64s): %s", addr, gai_strerror(r));
+		}
+		return 0;
+	}
+
+	for (ai = aitop; ai; ai = ai->ai_next) {
+		if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+			continue;
+		if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
+		    strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
+			error("channel_setup_fwd_listener: getnameinfo failed");
+			continue;
+		}
+		/* Create a port to listen for the host. */
+		sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
+		if (sock < 0) {
+			/* this is no error since kernel may not support ipv6 */
+			verbose("socket: %.100s", strerror(errno));
+			continue;
+		}
+
+		channel_set_reuseaddr(sock);
+
+		debug("Local forwarding listening on %s port %s.", ntop, strport);
+
+		/* Bind the socket to the address. */
+		if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
+			/* address can be in use ipv6 address is already bound */
+			if (!ai->ai_next)
+				error("bind: %.100s", strerror(errno));
+			else
+				verbose("bind: %.100s", strerror(errno));
+
+			close(sock);
+			continue;
+		}
+		/* Start listening for connections on the socket. */
+		if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
+			error("listen: %.100s", strerror(errno));
+			close(sock);
+			continue;
+		}
+		/* Allocate a channel number for the socket. */
+		c = channel_new("port listener", type, sock, sock, -1,
+		    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
+		    0, "port listener", 1);
+		strlcpy(c->path, host, sizeof(c->path));
+		c->host_port = port_to_connect;
+		c->listening_port = listen_port;
+		success = 1;
+	}
+	if (success == 0)
+		error("channel_setup_fwd_listener: cannot listen to port: %d",
+		    listen_port);
+	freeaddrinfo(aitop);
+	return success;
+}
+
+int
+channel_cancel_rport_listener(const char *host, u_short port)
+{
+	u_int i;
+	int found = 0;
+
+	for (i = 0; i < channels_alloc; i++) {
+		Channel *c = channels[i];
+
+		if (c != NULL && c->type == SSH_CHANNEL_RPORT_LISTENER &&
+		    strncmp(c->path, host, sizeof(c->path)) == 0 &&
+		    c->listening_port == port) {
+			debug2("%s: close channel %d", __func__, i);
+			channel_free(c);
+			found = 1;
+		}
+	}
+
+	return (found);
+}
+
+/* protocol local port fwd, used by ssh (and sshd in v1) */
+int
+channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
+    const char *host_to_connect, u_short port_to_connect, int gateway_ports)
+{
+	return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
+	    listen_host, listen_port, host_to_connect, port_to_connect,
+	    gateway_ports);
+}
+
+/* protocol v2 remote port fwd, used by sshd */
+int
+channel_setup_remote_fwd_listener(const char *listen_address,
+    u_short listen_port, int gateway_ports)
+{
+	return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
+	    listen_address, listen_port, NULL, 0, gateway_ports);
+}
+
+/*
+ * Initiate forwarding of connections to port "port" on remote host through
+ * the secure channel to host:port from local side.
+ */
+
+int
+channel_request_remote_forwarding(const char *listen_host, u_short listen_port,
+    const char *host_to_connect, u_short port_to_connect)
+{
+	int type, success = 0;
+
+	/* Record locally that connection to this host/port is permitted. */
+	if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
+		fatal("channel_request_remote_forwarding: too many forwards");
+
+	/* Send the forward request to the remote side. */
+	if (compat20) {
+		const char *address_to_bind;
+		if (listen_host == NULL)
+			address_to_bind = "localhost";
+		else if (*listen_host == '\0' || strcmp(listen_host, "*") == 0)
+			address_to_bind = "";
+		else
+			address_to_bind = listen_host;
+
+		packet_start(SSH2_MSG_GLOBAL_REQUEST);
+		packet_put_cstring("tcpip-forward");
+		packet_put_char(1);			/* boolean: want reply */
+		packet_put_cstring(address_to_bind);
+		packet_put_int(listen_port);
+		packet_send();
+		packet_write_wait();
+		/* Assume that server accepts the request */
+		success = 1;
+	} else {
+		packet_start(SSH_CMSG_PORT_FORWARD_REQUEST);
+		packet_put_int(listen_port);
+		packet_put_cstring(host_to_connect);
+		packet_put_int(port_to_connect);
+		packet_send();
+		packet_write_wait();
+
+		/* Wait for response from the remote side. */
+		type = packet_read();
+		switch (type) {
+		case SSH_SMSG_SUCCESS:
+			success = 1;
+			break;
+		case SSH_SMSG_FAILURE:
+			break;
+		default:
+			/* Unknown packet */
+			packet_disconnect("Protocol error for port forward request:"
+			    "received packet type %d.", type);
+		}
+	}
+	if (success) {
+		permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host_to_connect);
+		permitted_opens[num_permitted_opens].port_to_connect = port_to_connect;
+		permitted_opens[num_permitted_opens].listen_port = listen_port;
+		num_permitted_opens++;
+	}
+	return (success ? 0 : -1);
+}
+
+/*
+ * Request cancellation of remote forwarding of connection host:port from
+ * local side.
+ */
+void
+channel_request_rforward_cancel(const char *host, u_short port)
+{
+	int i;
+
+	if (!compat20)
+		return;
+
+	for (i = 0; i < num_permitted_opens; i++) {
+		if (permitted_opens[i].host_to_connect != NULL &&
+		    permitted_opens[i].listen_port == port)
+			break;
+	}
+	if (i >= num_permitted_opens) {
+		debug("%s: requested forward not found", __func__);
+		return;
+	}
+	packet_start(SSH2_MSG_GLOBAL_REQUEST);
+	packet_put_cstring("cancel-tcpip-forward");
+	packet_put_char(0);
+	packet_put_cstring(host == NULL ? "" : host);
+	packet_put_int(port);
+	packet_send();
+
+	permitted_opens[i].listen_port = 0;
+	permitted_opens[i].port_to_connect = 0;
+	xfree(permitted_opens[i].host_to_connect);
+	permitted_opens[i].host_to_connect = NULL;
+}
+
+/*
+ * This is called after receiving CHANNEL_FORWARDING_REQUEST.  This initates
+ * listening for the port, and sends back a success reply (or disconnect
+ * message if there was an error).
+ */
+int
+channel_input_port_forward_request(int is_root, int gateway_ports)
+{
+	u_short port, host_port;
+	int success = 0;
+	char *hostname;
+
+	/* Get arguments from the packet. */
+	port = packet_get_int();
+	hostname = packet_get_string(NULL);
+	host_port = packet_get_int();
+
+#ifndef HAVE_CYGWIN
+	/*
+	 * Check that an unprivileged user is not trying to forward a
+	 * privileged port.
+	 */
+	if (port < IPPORT_RESERVED && !is_root)
+		packet_disconnect(
+		    "Requested forwarding of port %d but user is not root.",
+		    port);
+	if (host_port == 0)
+		packet_disconnect("Dynamic forwarding denied.");
+#endif
+
+	/* Initiate forwarding */
+	success = channel_setup_local_fwd_listener(NULL, port, hostname,
+	    host_port, gateway_ports);
+
+	/* Free the argument string. */
+	xfree(hostname);
+
+	return (success ? 0 : -1);
+}
+
+/*
+ * Permits opening to any host/port if permitted_opens[] is empty.  This is
+ * usually called by the server, because the user could connect to any port
+ * anyway, and the server has no way to know but to trust the client anyway.
+ */
+void
+channel_permit_all_opens(void)
+{
+	if (num_permitted_opens == 0)
+		all_opens_permitted = 1;
+}
+
+void
+channel_add_permitted_opens(char *host, int port)
+{
+	if (num_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
+		fatal("channel_add_permitted_opens: too many forwards");
+	debug("allow port forwarding to host %s port %d", host, port);
+
+	permitted_opens[num_permitted_opens].host_to_connect = xstrdup(host);
+	permitted_opens[num_permitted_opens].port_to_connect = port;
+	num_permitted_opens++;
+
+	all_opens_permitted = 0;
+}
+
+int
+channel_add_adm_permitted_opens(char *host, int port)
+{
+	if (num_adm_permitted_opens >= SSH_MAX_FORWARDS_PER_DIRECTION)
+		fatal("channel_add_adm_permitted_opens: too many forwards");
+	debug("config allows port forwarding to host %s port %d", host, port);
+
+	permitted_adm_opens[num_adm_permitted_opens].host_to_connect
+	     = xstrdup(host);
+	permitted_adm_opens[num_adm_permitted_opens].port_to_connect = port;
+	return ++num_adm_permitted_opens;
+}
+
+void
+channel_clear_permitted_opens(void)
+{
+	int i;
+
+	for (i = 0; i < num_permitted_opens; i++)
+		if (permitted_opens[i].host_to_connect != NULL)
+			xfree(permitted_opens[i].host_to_connect);
+	num_permitted_opens = 0;
+}
+
+void
+channel_clear_adm_permitted_opens(void)
+{
+	int i;
+
+	for (i = 0; i < num_adm_permitted_opens; i++)
+		if (permitted_adm_opens[i].host_to_connect != NULL)
+			xfree(permitted_adm_opens[i].host_to_connect);
+	num_adm_permitted_opens = 0;
+}
+
+/* return socket to remote host, port */
+static int
+connect_to(const char *host, u_short port)
+{
+	struct addrinfo hints, *ai, *aitop;
+	char ntop[NI_MAXHOST], strport[NI_MAXSERV];
+	int gaierr;
+	int sock = -1;
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = IPv4or6;
+	hints.ai_socktype = SOCK_STREAM;
+	snprintf(strport, sizeof strport, "%d", port);
+	if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) {
+		error("connect_to %.100s: unknown host (%s)", host,
+		    gai_strerror(gaierr));
+		return -1;
+	}
+	for (ai = aitop; ai; ai = ai->ai_next) {
+		if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+			continue;
+		if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
+		    strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
+			error("connect_to: getnameinfo failed");
+			continue;
+		}
+		sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
+		if (sock < 0) {
+			if (ai->ai_next == NULL)
+				error("socket: %.100s", strerror(errno));
+			else
+				verbose("socket: %.100s", strerror(errno));
+			continue;
+		}
+		if (set_nonblock(sock) == -1)
+			fatal("%s: set_nonblock(%d)", __func__, sock);
+		if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0 &&
+		    errno != EINPROGRESS) {
+			error("connect_to %.100s port %s: %.100s", ntop, strport,
+			    strerror(errno));
+			close(sock);
+			continue;	/* fail -- try next */
+		}
+		break; /* success */
+
+	}
+	freeaddrinfo(aitop);
+	if (!ai) {
+		error("connect_to %.100s port %d: failed.", host, port);
+		return -1;
+	}
+	/* success */
+	set_nodelay(sock);
+	return sock;
+}
+
+int
+channel_connect_by_listen_address(u_short listen_port)
+{
+	int i;
+
+	for (i = 0; i < num_permitted_opens; i++)
+		if (permitted_opens[i].host_to_connect != NULL &&
+		    permitted_opens[i].listen_port == listen_port)
+			return connect_to(
+			    permitted_opens[i].host_to_connect,
+			    permitted_opens[i].port_to_connect);
+	error("WARNING: Server requests forwarding for unknown listen_port %d",
+	    listen_port);
+	return -1;
+}
+
+/* Check if connecting to that port is permitted and connect. */
+int
+channel_connect_to(const char *host, u_short port)
+{
+	int i, permit, permit_adm = 1;
+
+	permit = all_opens_permitted;
+	if (!permit) {
+		for (i = 0; i < num_permitted_opens; i++)
+			if (permitted_opens[i].host_to_connect != NULL &&
+			    permitted_opens[i].port_to_connect == port &&
+			    strcmp(permitted_opens[i].host_to_connect, host) == 0)
+				permit = 1;
+	}
+
+	if (num_adm_permitted_opens > 0) {
+		permit_adm = 0;
+		for (i = 0; i < num_adm_permitted_opens; i++)
+			if (permitted_adm_opens[i].host_to_connect != NULL &&
+			    permitted_adm_opens[i].port_to_connect == port &&
+			    strcmp(permitted_adm_opens[i].host_to_connect, host)
+			    == 0)
+				permit_adm = 1;
+	}
+
+	if (!permit || !permit_adm) {
+		logit("Received request to connect to host %.100s port %d, "
+		    "but the request was denied.", host, port);
+		return -1;
+	}
+	return connect_to(host, port);
+}
+
+void
+channel_send_window_changes(void)
+{
+	u_int i;
+	struct winsize ws;
+
+	for (i = 0; i < channels_alloc; i++) {
+		if (channels[i] == NULL || !channels[i]->client_tty ||
+		    channels[i]->type != SSH_CHANNEL_OPEN)
+			continue;
+		if (ioctl(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();
+	}
+}
+
+/* -- X11 forwarding */
+
+/*
+ * Creates an internet domain socket for listening for X11 connections.
+ * Returns 0 and a suitable display number for the DISPLAY variable
+ * 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)
+{
+	Channel *nc = NULL;
+	int display_number, sock;
+	u_short port;
+	struct addrinfo hints, *ai, *aitop;
+	char strport[NI_MAXSERV];
+	int gaierr, n, num_socks = 0, socks[NUM_SOCKS];
+
+	if (chanids == NULL)
+		return -1;
+
+	for (display_number = x11_display_offset;
+	    display_number < MAX_DISPLAYS;
+	    display_number++) {
+		port = 6000 + display_number;
+		memset(&hints, 0, sizeof(hints));
+		hints.ai_family = 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) {
+			error("getaddrinfo: %.100s", gai_strerror(gaierr));
+			return -1;
+		}
+		for (ai = aitop; ai; ai = ai->ai_next) {
+			if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+				continue;
+			sock = socket(ai->ai_family, ai->ai_socktype,
+			    ai->ai_protocol);
+			if (sock < 0) {
+				if ((errno != EINVAL) && (errno != EAFNOSUPPORT)) {
+					error("socket: %.100s", strerror(errno));
+					freeaddrinfo(aitop);
+					return -1;
+				} else {
+					debug("x11_create_display_inet: Socket family %d not supported",
+						 ai->ai_family);
+					continue;
+				}
+			}
+#ifdef IPV6_V6ONLY
+			if (ai->ai_family == AF_INET6) {
+				int on = 1;
+				if (setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0)
+					error("setsockopt IPV6_V6ONLY: %.100s", strerror(errno));
+			}
+#endif
+			channel_set_reuseaddr(sock);
+			if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
+				debug2("bind port %d: %.100s", port, strerror(errno));
+				close(sock);
+
+				if (ai->ai_next)
+					continue;
+
+				for (n = 0; n < num_socks; n++) {
+					close(socks[n]);
+				}
+				num_socks = 0;
+				break;
+			}
+			socks[num_socks++] = sock;
+#ifndef DONT_TRY_OTHER_AF
+			if (num_socks == NUM_SOCKS)
+				break;
+#else
+			if (x11_use_localhost) {
+				if (num_socks == NUM_SOCKS)
+					break;
+			} else {
+				break;
+			}
+#endif
+		}
+		freeaddrinfo(aitop);
+		if (num_socks > 0)
+			break;
+	}
+	if (display_number >= MAX_DISPLAYS) {
+		error("Failed to allocate internet-domain X11 display socket.");
+		return -1;
+	}
+	/* Start listening for connections on the socket. */
+	for (n = 0; n < num_socks; n++) {
+		sock = socks[n];
+		if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
+			error("listen: %.100s", strerror(errno));
+			close(sock);
+			return -1;
+		}
+	}
+
+	/* Allocate a channel for each socket. */
+	*chanids = xcalloc(num_socks + 1, sizeof(**chanids));
+	for (n = 0; n < num_socks; n++) {
+		sock = socks[n];
+		nc = channel_new("x11 listener",
+		    SSH_CHANNEL_X11_LISTENER, sock, sock, -1,
+		    CHAN_X11_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT,
+		    0, "X11 inet listener", 1);
+		nc->single_connection = single_connection;
+		(*chanids)[n] = nc->self;
+	}
+	(*chanids)[n] = -1;
+
+	/* Return the display number for the DISPLAY environment variable. */
+	*display_numberp = display_number;
+	return (0);
+}
+
+static int
+connect_local_xsocket(u_int dnr)
+{
+	int sock;
+	struct sockaddr_un addr;
+
+	sock = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (sock < 0)
+		error("socket: %.100s", strerror(errno));
+	memset(&addr, 0, sizeof(addr));
+	addr.sun_family = AF_UNIX;
+	snprintf(addr.sun_path, sizeof addr.sun_path, _PATH_UNIX_X, dnr);
+	if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0)
+		return sock;
+	close(sock);
+	error("connect %.100s: %.100s", addr.sun_path, strerror(errno));
+	return -1;
+}
+
+int
+x11_connect_display(void)
+{
+	u_int display_number;
+	const char *display;
+	char buf[1024], *cp;
+	struct addrinfo hints, *ai, *aitop;
+	char strport[NI_MAXSERV];
+	int gaierr, sock = 0;
+
+	/* Try to open a socket for the local X server. */
+	display = getenv("DISPLAY");
+	if (!display) {
+		error("DISPLAY not set.");
+		return -1;
+	}
+	/*
+	 * Now we decode the value of the DISPLAY variable and make a
+	 * connection to the real X server.
+	 */
+
+	/*
+	 * Check if it is a unix domain socket.  Unix domain displays are in
+	 * one of the following formats: unix:d[.s], :d[.s], ::d[.s]
+	 */
+	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);
+			return -1;
+		}
+		/* Create a socket. */
+		sock = connect_local_xsocket(display_number);
+		if (sock < 0)
+			return -1;
+
+		/* OK, we now have a connection to the display. */
+		return sock;
+	}
+	/*
+	 * Connect to an inet socket.  The DISPLAY value is supposedly
+	 * hostname:d[.s], where hostname may also be numeric IP address.
+	 */
+	strlcpy(buf, display, sizeof(buf));
+	cp = strchr(buf, ':');
+	if (!cp) {
+		error("Could not find ':' in DISPLAY: %.100s", display);
+		return -1;
+	}
+	*cp = 0;
+	/* 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);
+		return -1;
+	}
+
+	/* Look up the host address */
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = IPv4or6;
+	hints.ai_socktype = SOCK_STREAM;
+	snprintf(strport, sizeof strport, "%u", 6000 + display_number);
+	if ((gaierr = getaddrinfo(buf, strport, &hints, &aitop)) != 0) {
+		error("%.100s: unknown host. (%s)", buf, gai_strerror(gaierr));
+		return -1;
+	}
+	for (ai = aitop; ai; ai = ai->ai_next) {
+		/* Create a socket. */
+		sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
+		if (sock < 0) {
+			debug2("socket: %.100s", strerror(errno));
+			continue;
+		}
+		/* Connect it to the display. */
+		if (connect(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
+			debug2("connect %.100s port %u: %.100s", buf,
+			    6000 + display_number, strerror(errno));
+			close(sock);
+			continue;
+		}
+		/* Success */
+		break;
+	}
+	freeaddrinfo(aitop);
+	if (!ai) {
+		error("connect %.100s port %u: %.100s", buf, 6000 + display_number,
+		    strerror(errno));
+		return -1;
+	}
+	set_nodelay(sock);
+	return sock;
+}
+
+/*
+ * This is called when SSH_SMSG_X11_OPEN is received.  The packet contains
+ * the remote channel number.  We should do whatever we want, and respond
+ * with either SSH_MSG_OPEN_CONFIRMATION or SSH_MSG_OPEN_FAILURE.
+ */
+
+/* ARGSUSED */
+void
+x11_input_open(int type, u_int32_t seq, void *ctxt)
+{
+	Channel *c = NULL;
+	int remote_id, sock = 0;
+	char *remote_host;
+
+	debug("Received X11 open request.");
+
+	remote_id = packet_get_int();
+
+	if (packet_get_protocol_flags() & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) {
+		remote_host = packet_get_string(NULL);
+	} else {
+		remote_host = xstrdup("unknown (remote did not supply name)");
+	}
+	packet_check_eom();
+
+	/* Obtain a connection to the real X display. */
+	sock = x11_connect_display();
+	if (sock != -1) {
+		/* Allocate a channel for this connection. */
+		c = channel_new("connected x11 socket",
+		    SSH_CHANNEL_X11_OPEN, sock, sock, -1, 0, 0, 0,
+		    remote_host, 1);
+		c->remote_id = remote_id;
+		c->force_drain = 1;
+	}
+	xfree(remote_host);
+	if (c == NULL) {
+		/* Send refusal to the remote host. */
+		packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+		packet_put_int(remote_id);
+	} else {
+		/* Send a confirmation to the remote host. */
+		packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
+		packet_put_int(remote_id);
+		packet_put_int(c->self);
+	}
+	packet_send();
+}
+
+/* dummy protocol handler that denies SSH-1 requests (agent/x11) */
+/* ARGSUSED */
+void
+deny_input_open(int type, u_int32_t seq, void *ctxt)
+{
+	int rchan = packet_get_int();
+
+	switch (type) {
+	case SSH_SMSG_AGENT_OPEN:
+		error("Warning: ssh server tried agent forwarding.");
+		break;
+	case SSH_SMSG_X11_OPEN:
+		error("Warning: ssh server tried X11 forwarding.");
+		break;
+	default:
+		error("deny_input_open: type %d", type);
+		break;
+	}
+	error("Warning: this is probably a break-in attempt by a malicious server.");
+	packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
+	packet_put_int(rchan);
+	packet_send();
+}
+
+/*
+ * Requests forwarding of X11 connections, generates fake authentication
+ * data, and enables authentication spoofing.
+ * This should be called in the client only.
+ */
+void
+x11_request_forwarding_with_spoofing(int client_session_id, const char *disp,
+    const char *proto, const char *data)
+{
+	u_int data_len = (u_int) strlen(data) / 2;
+	u_int i, value;
+	char *new_data;
+	int screen_number;
+	const char *cp;
+	u_int32_t rnd = 0;
+
+	if (x11_saved_display == NULL)
+		x11_saved_display = xstrdup(disp);
+	else if (strcmp(disp, x11_saved_display) != 0) {
+		error("x11_request_forwarding_with_spoofing: different "
+		    "$DISPLAY already forwarded");
+		return;
+	}
+
+	cp = strchr(disp, ':');
+	if (cp)
+		cp = strchr(cp, '.');
+	if (cp)
+		screen_number = (u_int)strtonum(cp + 1, 0, 400, NULL);
+	else
+		screen_number = 0;
+
+	if (x11_saved_proto == NULL) {
+		/* Save protocol name. */
+		x11_saved_proto = xstrdup(proto);
+		/*
+		 * Extract real authentication data and generate fake data
+		 * of the same length.
+		 */
+		x11_saved_data = xmalloc(data_len);
+		x11_fake_data = xmalloc(data_len);
+		for (i = 0; i < data_len; i++) {
+			if (sscanf(data + 2 * i, "%2x", &value) != 1)
+				fatal("x11_request_forwarding: bad "
+				    "authentication data: %.100s", data);
+			if (i % 4 == 0)
+				rnd = arc4random();
+			x11_saved_data[i] = value;
+			x11_fake_data[i] = rnd & 0xff;
+			rnd >>= 8;
+		}
+		x11_saved_data_len = data_len;
+		x11_fake_data_len = data_len;
+	}
+
+	/* Convert the fake data into hex. */
+	new_data = tohex(x11_fake_data, data_len);
+
+	/* Send the request packet. */
+	if (compat20) {
+		channel_request_start(client_session_id, "x11-req", 0);
+		packet_put_char(0);	/* XXX bool single connection */
+	} else {
+		packet_start(SSH_CMSG_X11_REQUEST_FORWARDING);
+	}
+	packet_put_cstring(proto);
+	packet_put_cstring(new_data);
+	packet_put_int(screen_number);
+	packet_send();
+	packet_write_wait();
+	xfree(new_data);
+}
+
+
+/* -- agent forwarding */
+
+/* Sends a message to the server to request authentication fd forwarding. */
+
+void
+auth_request_forwarding(void)
+{
+	packet_start(SSH_CMSG_AGENT_REQUEST_FORWARDING);
+	packet_send();
+	packet_write_wait();
+}