mux.c - security/openssh-library - Rivoreo Source Code Repositories

 /* $OpenBSD: mux.c,v 1.1 2008/05/09 14:18:44 djm Exp $ */
 /*
  * Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */

 /* ssh session multiplexing support */

 #include "includes.h"

 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/stat.h>
 #include <sys/socket.h>
 #include <sys/un.h>

 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <paths.h>

 #ifdef HAVE_UTIL_H
 # include <util.h>
 #endif

 #ifdef HAVE_LIBUTIL_H
 # include <libutil.h>
 #endif

 #include "openbsd-compat/sys-queue.h"
 #include "xmalloc.h"
 #include "log.h"
 #include "ssh.h"
 #include "pathnames.h"
 #include "misc.h"
 #include "match.h"
 #include "buffer.h"
 #include "channels.h"
 #include "msg.h"
 #include "packet.h"
 #include "monitor_fdpass.h"
 #include "sshpty.h"
 #include "key.h"
 #include "readconf.h"
 #include "clientloop.h"

 /* from ssh.c */
 extern int tty_flag;
 extern Options options;
 extern int stdin_null_flag;
 extern char *host;
 int subsystem_flag;
 extern Buffer command;

 /* fd to control socket */
 int muxserver_sock = -1;

 /* Multiplexing control command */
 u_int muxclient_command = 0;

 /* Set when signalled. */
 static volatile sig_atomic_t muxclient_terminate = 0;

 /* PID of multiplex server */
 static u_int muxserver_pid = 0;


 /* ** Multiplexing master support */

 /* Prepare a mux master to listen on a Unix domain socket. */
 void
 muxserver_listen(void)
 {
 	struct sockaddr_un addr;
 	mode_t old_umask;
 	int addr_len;

 	if (options.control_path == NULL ||
 	    options.control_master == SSHCTL_MASTER_NO)
 		return;

 	debug("setting up multiplex master socket");

 	memset(&addr, '\0', sizeof(addr));
 	addr.sun_family = AF_UNIX;
 	addr_len = offsetof(struct sockaddr_un, sun_path) +
 	    strlen(options.control_path) + 1;

 	if (strlcpy(addr.sun_path, options.control_path,
 	    sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
 		fatal("ControlPath too long");

 	if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
 		fatal("%s socket(): %s", __func__, strerror(errno));

 	old_umask = umask(0177);
 	if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) {
 		muxserver_sock = -1;
 		if (errno == EINVAL || errno == EADDRINUSE)
 			fatal("ControlSocket %s already exists",
 			    options.control_path);
 		else
 			fatal("%s bind(): %s", __func__, strerror(errno));
 	}
 	umask(old_umask);

 	if (listen(muxserver_sock, 64) == -1)
 		fatal("%s listen(): %s", __func__, strerror(errno));

 	set_nonblock(muxserver_sock);
 }

 /* Callback on open confirmation in mux master for a mux client session. */
 static void
 client_extra_session2_setup(int id, void *arg)
 {
 	struct mux_session_confirm_ctx *cctx = arg;
 	const char *display;
 	Channel *c;
 	int i;

 	if (cctx == NULL)
 		fatal("%s: cctx == NULL", __func__);
 	if ((c = channel_lookup(id)) == NULL)
 		fatal("%s: no channel for id %d", __func__, id);

 	display = getenv("DISPLAY");
 	if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
 		char *proto, *data;
 		/* Get reasonable local authentication information. */
 		client_x11_get_proto(display, options.xauth_location,
 		    options.forward_x11_trusted, &proto, &data);
 		/* Request forwarding with authentication spoofing. */
 		debug("Requesting X11 forwarding with authentication spoofing.");
 		x11_request_forwarding_with_spoofing(id, display, proto, data);
 		/* XXX wait for reply */
 	}

 	if (cctx->want_agent_fwd && options.forward_agent) {
 		debug("Requesting authentication agent forwarding.");
 		channel_request_start(id, "auth-agent-req@openssh.com", 0);
 		packet_send();
 	}

 	client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
 	    cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);

 	c->open_confirm_ctx = NULL;
 	buffer_free(&cctx->cmd);
 	xfree(cctx->term);
 	if (cctx->env != NULL) {
 		for (i = 0; cctx->env[i] != NULL; i++)
 			xfree(cctx->env[i]);
 		xfree(cctx->env);
 	}
 	xfree(cctx);
 }

 /*
  * Accept a connection on the mux master socket and process the
  * client's request. Returns flag indicating whether mux master should
  * begin graceful close.
  */
 int
 muxserver_accept_control(void)
 {
 	Buffer m;
 	Channel *c;
 	int client_fd, new_fd[3], ver, allowed, window, packetmax;
 	socklen_t addrlen;
 	struct sockaddr_storage addr;
 	struct mux_session_confirm_ctx *cctx;
 	char *cmd;
 	u_int i, j, len, env_len, mux_command, flags;
 	uid_t euid;
 	gid_t egid;
 	int start_close = 0;

 	/*
 	 * Accept connection on control socket
 	 */
 	memset(&addr, 0, sizeof(addr));
 	addrlen = sizeof(addr);
 	if ((client_fd = accept(muxserver_sock,
 	    (struct sockaddr*)&addr, &addrlen)) == -1) {
 		error("%s accept: %s", __func__, strerror(errno));
 		return 0;
 	}

 	if (getpeereid(client_fd, &euid, &egid) < 0) {
 		error("%s getpeereid failed: %s", __func__, strerror(errno));
 		close(client_fd);
 		return 0;
 	}
 	if ((euid != 0) && (getuid() != euid)) {
 		error("control mode uid mismatch: peer euid %u != uid %u",
 		    (u_int) euid, (u_int) getuid());
 		close(client_fd);
 		return 0;
 	}

 	/* XXX handle asynchronously */
 	unset_nonblock(client_fd);

 	/* Read command */
 	buffer_init(&m);
 	if (ssh_msg_recv(client_fd, &m) == -1) {
 		error("%s: client msg_recv failed", __func__);
 		close(client_fd);
 		buffer_free(&m);
 		return 0;
 	}
 	if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
 		error("%s: wrong client version %d", __func__, ver);
 		buffer_free(&m);
 		close(client_fd);
 		return 0;
 	}

 	allowed = 1;
 	mux_command = buffer_get_int(&m);
 	flags = buffer_get_int(&m);

 	buffer_clear(&m);

 	switch (mux_command) {
 	case SSHMUX_COMMAND_OPEN:
 		if (options.control_master == SSHCTL_MASTER_ASK ||
 		    options.control_master == SSHCTL_MASTER_AUTO_ASK)
 			allowed = ask_permission("Allow shared connection "
 			    "to %s? ", host);
 		/* continue below */
 		break;
 	case SSHMUX_COMMAND_TERMINATE:
 		if (options.control_master == SSHCTL_MASTER_ASK ||
 		    options.control_master == SSHCTL_MASTER_AUTO_ASK)
 			allowed = ask_permission("Terminate shared connection "
 			    "to %s? ", host);
 		if (allowed)
 			start_close = 1;
 		/* FALLTHROUGH */
 	case SSHMUX_COMMAND_ALIVE_CHECK:
 		/* Reply for SSHMUX_COMMAND_TERMINATE and ALIVE_CHECK */
 		buffer_clear(&m);
 		buffer_put_int(&m, allowed);
 		buffer_put_int(&m, getpid());
 		if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
 			error("%s: client msg_send failed", __func__);
 			close(client_fd);
 			buffer_free(&m);
 			return start_close;
 		}
 		buffer_free(&m);
 		close(client_fd);
 		return start_close;
 	default:
 		error("Unsupported command %d", mux_command);
 		buffer_free(&m);
 		close(client_fd);
 		return 0;
 	}

 	/* Reply for SSHMUX_COMMAND_OPEN */
 	buffer_clear(&m);
 	buffer_put_int(&m, allowed);
 	buffer_put_int(&m, getpid());
 	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
 		error("%s: client msg_send failed", __func__);
 		close(client_fd);
 		buffer_free(&m);
 		return 0;
 	}

 	if (!allowed) {
 		error("Refused control connection");
 		close(client_fd);
 		buffer_free(&m);
 		return 0;
 	}

 	buffer_clear(&m);
 	if (ssh_msg_recv(client_fd, &m) == -1) {
 		error("%s: client msg_recv failed", __func__);
 		close(client_fd);
 		buffer_free(&m);
 		return 0;
 	}
 	if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
 		error("%s: wrong client version %d", __func__, ver);
 		buffer_free(&m);
 		close(client_fd);
 		return 0;
 	}

 	cctx = xcalloc(1, sizeof(*cctx));
 	cctx->want_tty = (flags & SSHMUX_FLAG_TTY) != 0;
 	cctx->want_subsys = (flags & SSHMUX_FLAG_SUBSYS) != 0;
 	cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0;
 	cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0;
 	cctx->term = buffer_get_string(&m, &len);

 	cmd = buffer_get_string(&m, &len);
 	buffer_init(&cctx->cmd);
 	buffer_append(&cctx->cmd, cmd, strlen(cmd));

 	env_len = buffer_get_int(&m);
 	env_len = MIN(env_len, 4096);
 	debug3("%s: receiving %d env vars", __func__, env_len);
 	if (env_len != 0) {
 		cctx->env = xcalloc(env_len + 1, sizeof(*cctx->env));
 		for (i = 0; i < env_len; i++)
 			cctx->env[i] = buffer_get_string(&m, &len);
 		cctx->env[i] = NULL;
 	}

 	debug2("%s: accepted tty %d, subsys %d, cmd %s", __func__,
 	    cctx->want_tty, cctx->want_subsys, cmd);
 	xfree(cmd);

 	/* Gather fds from client */
 	for(i = 0; i < 3; i++) {
 		if ((new_fd[i] = mm_receive_fd(client_fd)) == -1) {
 			error("%s: failed to receive fd %d from slave",
 			    __func__, i);
 			for (j = 0; j < i; j++)
 				close(new_fd[j]);
 			for (j = 0; j < env_len; j++)
 				xfree(cctx->env[j]);
 			if (env_len > 0)
 				xfree(cctx->env);
 			xfree(cctx->term);
 			buffer_free(&cctx->cmd);
 			close(client_fd);
 			xfree(cctx);
 			return 0;
 		}
 	}

 	debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
 	    new_fd[0], new_fd[1], new_fd[2]);

 	/* Try to pick up ttymodes from client before it goes raw */
 	if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
 		error("%s: tcgetattr: %s", __func__, strerror(errno));

 	/* This roundtrip is just for synchronisation of ttymodes */
 	buffer_clear(&m);
 	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
 		error("%s: client msg_send failed", __func__);
 		close(client_fd);
 		close(new_fd[0]);
 		close(new_fd[1]);
 		close(new_fd[2]);
 		buffer_free(&m);
 		xfree(cctx->term);
 		if (env_len != 0) {
 			for (i = 0; i < env_len; i++)
 				xfree(cctx->env[i]);
 			xfree(cctx->env);
 		}
 		return 0;
 	}
 	buffer_free(&m);

 	/* enable nonblocking unless tty */
 	if (!isatty(new_fd[0]))
 		set_nonblock(new_fd[0]);
 	if (!isatty(new_fd[1]))
 		set_nonblock(new_fd[1]);
 	if (!isatty(new_fd[2]))
 		set_nonblock(new_fd[2]);

 	set_nonblock(client_fd);

 	window = CHAN_SES_WINDOW_DEFAULT;
 	packetmax = CHAN_SES_PACKET_DEFAULT;
 	if (cctx->want_tty) {
 		window >>= 1;
 		packetmax >>= 1;
 	}

 	c = channel_new("session", SSH_CHANNEL_OPENING,
 	    new_fd[0], new_fd[1], new_fd[2], window, packetmax,
 	    CHAN_EXTENDED_WRITE, "client-session", /*nonblock*/0);

 	/* XXX */
 	c->ctl_fd = client_fd;

 	debug3("%s: channel_new: %d", __func__, c->self);

 	channel_send_open(c->self);
 	channel_register_open_confirm(c->self,
 	    client_extra_session2_setup, cctx);
 	return 0;
 }

 /* ** Multiplexing client support */

 /* Exit signal handler */
 static void
 control_client_sighandler(int signo)
 {
 	muxclient_terminate = signo;
 }

 /*
  * Relay signal handler - used to pass some signals from mux client to
  * mux master.
  */
 static void
 control_client_sigrelay(int signo)
 {
 	int save_errno = errno;

 	if (muxserver_pid > 1)
 		kill(muxserver_pid, signo);

 	errno = save_errno;
 }

 /* Check mux client environment variables before passing them to mux master. */
 static int
 env_permitted(char *env)
 {
 	int i, ret;
 	char name[1024], *cp;

 	if ((cp = strchr(env, '=')) == NULL || cp == env)
 		return (0);
 	ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
 	if (ret <= 0 || (size_t)ret >= sizeof(name))
 		fatal("env_permitted: name '%.100s...' too long", env);

 	for (i = 0; i < options.num_send_env; i++)
 		if (match_pattern(name, options.send_env[i]))
 			return (1);

 	return (0);
 }

 /* Multiplex client main loop. */
 void
 muxclient(const char *path)
 {
 	struct sockaddr_un addr;
 	int i, r, fd, sock, exitval[2], num_env, addr_len;
 	Buffer m;
 	char *term;
 	extern char **environ;
 	u_int  flags;

 	if (muxclient_command == 0)
 		muxclient_command = SSHMUX_COMMAND_OPEN;

 	switch (options.control_master) {
 	case SSHCTL_MASTER_AUTO:
 	case SSHCTL_MASTER_AUTO_ASK:
 		debug("auto-mux: Trying existing master");
 		/* FALLTHROUGH */
 	case SSHCTL_MASTER_NO:
 		break;
 	default:
 		return;
 	}

 	memset(&addr, '\0', sizeof(addr));
 	addr.sun_family = AF_UNIX;
 	addr_len = offsetof(struct sockaddr_un, sun_path) +
 	    strlen(path) + 1;

 	if (strlcpy(addr.sun_path, path,
 	    sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
 		fatal("ControlPath too long");

 	if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
 		fatal("%s socket(): %s", __func__, strerror(errno));

 	if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
 		if (muxclient_command != SSHMUX_COMMAND_OPEN) {
 			fatal("Control socket connect(%.100s): %s", path,
 			    strerror(errno));
 		}
 		if (errno == ENOENT)
 			debug("Control socket \"%.100s\" does not exist", path);
 		else {
 			error("Control socket connect(%.100s): %s", path,
 			    strerror(errno));
 		}
 		close(sock);
 		return;
 	}

 	if (stdin_null_flag) {
 		if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
 			fatal("open(/dev/null): %s", strerror(errno));
 		if (dup2(fd, STDIN_FILENO) == -1)
 			fatal("dup2: %s", strerror(errno));
 		if (fd > STDERR_FILENO)
 			close(fd);
 	}

 	term = getenv("TERM");

 	flags = 0;
 	if (tty_flag)
 		flags |= SSHMUX_FLAG_TTY;
 	if (subsystem_flag)
 		flags |= SSHMUX_FLAG_SUBSYS;
 	if (options.forward_x11)
 		flags |= SSHMUX_FLAG_X11_FWD;
 	if (options.forward_agent)
 		flags |= SSHMUX_FLAG_AGENT_FWD;

 	signal(SIGPIPE, SIG_IGN);

 	buffer_init(&m);

 	/* Send our command to server */
 	buffer_put_int(&m, muxclient_command);
 	buffer_put_int(&m, flags);
 	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
 		fatal("%s: msg_send", __func__);
 	buffer_clear(&m);

 	/* Get authorisation status and PID of controlee */
 	if (ssh_msg_recv(sock, &m) == -1)
 		fatal("%s: msg_recv", __func__);
 	if (buffer_get_char(&m) != SSHMUX_VER)
 		fatal("%s: wrong version", __func__);
 	if (buffer_get_int(&m) != 1)
 		fatal("Connection to master denied");
 	muxserver_pid = buffer_get_int(&m);

 	buffer_clear(&m);

 	switch (muxclient_command) {
 	case SSHMUX_COMMAND_ALIVE_CHECK:
 		fprintf(stderr, "Master running (pid=%d)\r\n",
 		    muxserver_pid);
 		exit(0);
 	case SSHMUX_COMMAND_TERMINATE:
 		fprintf(stderr, "Exit request sent.\r\n");
 		exit(0);
 	case SSHMUX_COMMAND_OPEN:
 		/* continue below */
 		break;
 	default:
 		fatal("silly muxclient_command %d", muxclient_command);
 	}

 	/* SSHMUX_COMMAND_OPEN */
 	buffer_put_cstring(&m, term ? term : "");
 	buffer_append(&command, "\0", 1);
 	buffer_put_cstring(&m, buffer_ptr(&command));

 	if (options.num_send_env == 0 || environ == NULL) {
 		buffer_put_int(&m, 0);
 	} else {
 		/* Pass environment */
 		num_env = 0;
 		for (i = 0; environ[i] != NULL; i++)
 			if (env_permitted(environ[i]))
 				num_env++; /* Count */

 		buffer_put_int(&m, num_env);

 		for (i = 0; environ[i] != NULL && num_env >= 0; i++)
 			if (env_permitted(environ[i])) {
 				num_env--;
 				buffer_put_cstring(&m, environ[i]);
 			}
 	}

 	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
 		fatal("%s: msg_send", __func__);

 	if (mm_send_fd(sock, STDIN_FILENO) == -1 ||
 	    mm_send_fd(sock, STDOUT_FILENO) == -1 ||
 	    mm_send_fd(sock, STDERR_FILENO) == -1)
 		fatal("%s: send fds failed", __func__);

 	/* Wait for reply, so master has a chance to gather ttymodes */
 	buffer_clear(&m);
 	if (ssh_msg_recv(sock, &m) == -1)
 		fatal("%s: msg_recv", __func__);
 	if (buffer_get_char(&m) != SSHMUX_VER)
 		fatal("%s: wrong version", __func__);
 	buffer_free(&m);

 	signal(SIGHUP, control_client_sighandler);
 	signal(SIGINT, control_client_sighandler);
 	signal(SIGTERM, control_client_sighandler);
 	signal(SIGWINCH, control_client_sigrelay);

 	if (tty_flag)
 		enter_raw_mode();

 	/*
 	 * Stick around until the controlee closes the client_fd.
 	 * Before it does, it is expected to write this process' exit
 	 * value (one int). This process must read the value and wait for
 	 * the closure of the client_fd; if this one closes early, the
 	 * multiplex master will terminate early too (possibly losing data).
 	 */
 	exitval[0] = 0;
 	for (i = 0; !muxclient_terminate && i < (int)sizeof(exitval);) {
 		r = read(sock, (char *)exitval + i, sizeof(exitval) - i);
 		if (r == 0) {
 			debug2("Received EOF from master");
 			break;
 		}
 		if (r == -1) {
 			if (errno == EINTR)
 				continue;
 			fatal("%s: read %s", __func__, strerror(errno));
 		}
 		i += r;
 	}

 	close(sock);
 	leave_raw_mode();
 	if (i > (int)sizeof(int))
 		fatal("%s: master returned too much data (%d > %lu)",
 		    __func__, i, sizeof(int));
 	if (muxclient_terminate) {
 		debug2("Exiting on signal %d", muxclient_terminate);
 		exitval[0] = 255;
 	} else if (i < (int)sizeof(int)) {
 		debug2("Control master terminated unexpectedly");
 		exitval[0] = 255;
 	} else
 		debug2("Received exit status from master %d", exitval[0]);

 	if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
 		fprintf(stderr, "Shared connection to %s closed.\r\n", host);

 	exit(exitval[0]);
 }
	/* $OpenBSD: mux.c,v 1.1 2008/05/09 14:18:44 djm Exp $ */
	/*
	* Copyright (c) 2002-2008 Damien Miller <djm@openbsd.org>
	*
	* Permission to use, copy, modify, and distribute this software for any
	* purpose with or without fee is hereby granted, provided that the above
	* copyright notice and this permission notice appear in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	*/

	/* ssh session multiplexing support */

	#include "includes.h"

	#include <sys/types.h>
	#include <sys/param.h>
	#include <sys/stat.h>
	#include <sys/socket.h>
	#include <sys/un.h>

	#include <errno.h>
	#include <fcntl.h>
	#include <signal.h>
	#include <stdarg.h>
	#include <stddef.h>
	#include <stdlib.h>
	#include <stdio.h>
	#include <string.h>
	#include <unistd.h>
	#include <paths.h>

	#ifdef HAVE_UTIL_H
	# include <util.h>
	#endif

	#ifdef HAVE_LIBUTIL_H
	# include <libutil.h>
	#endif

	#include "openbsd-compat/sys-queue.h"
	#include "xmalloc.h"
	#include "log.h"
	#include "ssh.h"
	#include "pathnames.h"
	#include "misc.h"
	#include "match.h"
	#include "buffer.h"
	#include "channels.h"
	#include "msg.h"
	#include "packet.h"
	#include "monitor_fdpass.h"
	#include "sshpty.h"
	#include "key.h"
	#include "readconf.h"
	#include "clientloop.h"

	/* from ssh.c */
	extern int tty_flag;
	extern Options options;
	extern int stdin_null_flag;
	extern char *host;
	int subsystem_flag;
	extern Buffer command;

	/* fd to control socket */
	int muxserver_sock = -1;

	/* Multiplexing control command */
	u_int muxclient_command = 0;

	/* Set when signalled. */
	static volatile sig_atomic_t muxclient_terminate = 0;

	/* PID of multiplex server */
	static u_int muxserver_pid = 0;


	/* ** Multiplexing master support */

	/* Prepare a mux master to listen on a Unix domain socket. */
	void
	muxserver_listen(void)
	{
	struct sockaddr_un addr;
	mode_t old_umask;
	int addr_len;

	if (options.control_path == NULL \|\|
	options.control_master == SSHCTL_MASTER_NO)
	return;

	debug("setting up multiplex master socket");

	memset(&addr, '\0', sizeof(addr));
	addr.sun_family = AF_UNIX;
	addr_len = offsetof(struct sockaddr_un, sun_path) +
	strlen(options.control_path) + 1;

	if (strlcpy(addr.sun_path, options.control_path,
	sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
	fatal("ControlPath too long");

	if ((muxserver_sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
	fatal("%s socket(): %s", __func__, strerror(errno));

	old_umask = umask(0177);
	if (bind(muxserver_sock, (struct sockaddr *)&addr, addr_len) == -1) {
	muxserver_sock = -1;
	if (errno == EINVAL \|\| errno == EADDRINUSE)
	fatal("ControlSocket %s already exists",
	options.control_path);
	else
	fatal("%s bind(): %s", __func__, strerror(errno));
	}
	umask(old_umask);

	if (listen(muxserver_sock, 64) == -1)
	fatal("%s listen(): %s", __func__, strerror(errno));

	set_nonblock(muxserver_sock);
	}

	/* Callback on open confirmation in mux master for a mux client session. */
	static void
	client_extra_session2_setup(int id, void *arg)
	{
	struct mux_session_confirm_ctx *cctx = arg;
	const char *display;
	Channel *c;
	int i;

	if (cctx == NULL)
	fatal("%s: cctx == NULL", __func__);
	if ((c = channel_lookup(id)) == NULL)
	fatal("%s: no channel for id %d", __func__, id);

	display = getenv("DISPLAY");
	if (cctx->want_x_fwd && options.forward_x11 && display != NULL) {
	char proto, data;
	/* Get reasonable local authentication information. */
	client_x11_get_proto(display, options.xauth_location,
	options.forward_x11_trusted, &proto, &data);
	/* Request forwarding with authentication spoofing. */
	debug("Requesting X11 forwarding with authentication spoofing.");
	x11_request_forwarding_with_spoofing(id, display, proto, data);
	/* XXX wait for reply */
	}

	if (cctx->want_agent_fwd && options.forward_agent) {
	debug("Requesting authentication agent forwarding.");
	channel_request_start(id, "auth-agent-req@openssh.com", 0);
	packet_send();
	}

	client_session2_setup(id, cctx->want_tty, cctx->want_subsys,
	cctx->term, &cctx->tio, c->rfd, &cctx->cmd, cctx->env);

	c->open_confirm_ctx = NULL;
	buffer_free(&cctx->cmd);
	xfree(cctx->term);
	if (cctx->env != NULL) {
	for (i = 0; cctx->env[i] != NULL; i++)
	xfree(cctx->env[i]);
	xfree(cctx->env);
	}
	xfree(cctx);
	}

	/*
	* Accept a connection on the mux master socket and process the
	* client's request. Returns flag indicating whether mux master should
	* begin graceful close.
	*/
	int
	muxserver_accept_control(void)
	{
	Buffer m;
	Channel *c;
	int client_fd, new_fd[3], ver, allowed, window, packetmax;
	socklen_t addrlen;
	struct sockaddr_storage addr;
	struct mux_session_confirm_ctx *cctx;
	char *cmd;
	u_int i, j, len, env_len, mux_command, flags;
	uid_t euid;
	gid_t egid;
	int start_close = 0;

	/*
	* Accept connection on control socket
	*/
	memset(&addr, 0, sizeof(addr));
	addrlen = sizeof(addr);
	if ((client_fd = accept(muxserver_sock,
	(struct sockaddr*)&addr, &addrlen)) == -1) {
	error("%s accept: %s", __func__, strerror(errno));
	return 0;
	}

	if (getpeereid(client_fd, &euid, &egid) < 0) {
	error("%s getpeereid failed: %s", __func__, strerror(errno));
	close(client_fd);
	return 0;
	}
	if ((euid != 0) && (getuid() != euid)) {
	error("control mode uid mismatch: peer euid %u != uid %u",
	(u_int) euid, (u_int) getuid());
	close(client_fd);
	return 0;
	}

	/* XXX handle asynchronously */
	unset_nonblock(client_fd);

	/* Read command */
	buffer_init(&m);
	if (ssh_msg_recv(client_fd, &m) == -1) {
	error("%s: client msg_recv failed", __func__);
	close(client_fd);
	buffer_free(&m);
	return 0;
	}
	if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
	error("%s: wrong client version %d", __func__, ver);
	buffer_free(&m);
	close(client_fd);
	return 0;
	}

	allowed = 1;
	mux_command = buffer_get_int(&m);
	flags = buffer_get_int(&m);

	buffer_clear(&m);

	switch (mux_command) {
	case SSHMUX_COMMAND_OPEN:
	if (options.control_master == SSHCTL_MASTER_ASK \|\|
	options.control_master == SSHCTL_MASTER_AUTO_ASK)
	allowed = ask_permission("Allow shared connection "
	"to %s? ", host);
	/* continue below */
	break;
	case SSHMUX_COMMAND_TERMINATE:
	if (options.control_master == SSHCTL_MASTER_ASK \|\|
	options.control_master == SSHCTL_MASTER_AUTO_ASK)
	allowed = ask_permission("Terminate shared connection "
	"to %s? ", host);
	if (allowed)
	start_close = 1;
	/* FALLTHROUGH */
	case SSHMUX_COMMAND_ALIVE_CHECK:
	/* Reply for SSHMUX_COMMAND_TERMINATE and ALIVE_CHECK */
	buffer_clear(&m);
	buffer_put_int(&m, allowed);
	buffer_put_int(&m, getpid());
	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
	error("%s: client msg_send failed", __func__);
	close(client_fd);
	buffer_free(&m);
	return start_close;
	}
	buffer_free(&m);
	close(client_fd);
	return start_close;
	default:
	error("Unsupported command %d", mux_command);
	buffer_free(&m);
	close(client_fd);
	return 0;
	}

	/* Reply for SSHMUX_COMMAND_OPEN */
	buffer_clear(&m);
	buffer_put_int(&m, allowed);
	buffer_put_int(&m, getpid());
	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
	error("%s: client msg_send failed", __func__);
	close(client_fd);
	buffer_free(&m);
	return 0;
	}

	if (!allowed) {
	error("Refused control connection");
	close(client_fd);
	buffer_free(&m);
	return 0;
	}

	buffer_clear(&m);
	if (ssh_msg_recv(client_fd, &m) == -1) {
	error("%s: client msg_recv failed", __func__);
	close(client_fd);
	buffer_free(&m);
	return 0;
	}
	if ((ver = buffer_get_char(&m)) != SSHMUX_VER) {
	error("%s: wrong client version %d", __func__, ver);
	buffer_free(&m);
	close(client_fd);
	return 0;
	}

	cctx = xcalloc(1, sizeof(*cctx));
	cctx->want_tty = (flags & SSHMUX_FLAG_TTY) != 0;
	cctx->want_subsys = (flags & SSHMUX_FLAG_SUBSYS) != 0;
	cctx->want_x_fwd = (flags & SSHMUX_FLAG_X11_FWD) != 0;
	cctx->want_agent_fwd = (flags & SSHMUX_FLAG_AGENT_FWD) != 0;
	cctx->term = buffer_get_string(&m, &len);

	cmd = buffer_get_string(&m, &len);
	buffer_init(&cctx->cmd);
	buffer_append(&cctx->cmd, cmd, strlen(cmd));

	env_len = buffer_get_int(&m);
	env_len = MIN(env_len, 4096);
	debug3("%s: receiving %d env vars", __func__, env_len);
	if (env_len != 0) {
	cctx->env = xcalloc(env_len + 1, sizeof(*cctx->env));
	for (i = 0; i < env_len; i++)
	cctx->env[i] = buffer_get_string(&m, &len);
	cctx->env[i] = NULL;
	}

	debug2("%s: accepted tty %d, subsys %d, cmd %s", __func__,
	cctx->want_tty, cctx->want_subsys, cmd);
	xfree(cmd);

	/* Gather fds from client */
	for(i = 0; i < 3; i++) {
	if ((new_fd[i] = mm_receive_fd(client_fd)) == -1) {
	error("%s: failed to receive fd %d from slave",
	__func__, i);
	for (j = 0; j < i; j++)
	close(new_fd[j]);
	for (j = 0; j < env_len; j++)
	xfree(cctx->env[j]);
	if (env_len > 0)
	xfree(cctx->env);
	xfree(cctx->term);
	buffer_free(&cctx->cmd);
	close(client_fd);
	xfree(cctx);
	return 0;
	}
	}

	debug2("%s: got fds stdin %d, stdout %d, stderr %d", __func__,
	new_fd[0], new_fd[1], new_fd[2]);

	/* Try to pick up ttymodes from client before it goes raw */
	if (cctx->want_tty && tcgetattr(new_fd[0], &cctx->tio) == -1)
	error("%s: tcgetattr: %s", __func__, strerror(errno));

	/* This roundtrip is just for synchronisation of ttymodes */
	buffer_clear(&m);
	if (ssh_msg_send(client_fd, SSHMUX_VER, &m) == -1) {
	error("%s: client msg_send failed", __func__);
	close(client_fd);
	close(new_fd[0]);
	close(new_fd[1]);
	close(new_fd[2]);
	buffer_free(&m);
	xfree(cctx->term);
	if (env_len != 0) {
	for (i = 0; i < env_len; i++)
	xfree(cctx->env[i]);
	xfree(cctx->env);
	}
	return 0;
	}
	buffer_free(&m);

	/* enable nonblocking unless tty */
	if (!isatty(new_fd[0]))
	set_nonblock(new_fd[0]);
	if (!isatty(new_fd[1]))
	set_nonblock(new_fd[1]);
	if (!isatty(new_fd[2]))
	set_nonblock(new_fd[2]);

	set_nonblock(client_fd);

	window = CHAN_SES_WINDOW_DEFAULT;
	packetmax = CHAN_SES_PACKET_DEFAULT;
	if (cctx->want_tty) {
	window >>= 1;
	packetmax >>= 1;
	}

	c = channel_new("session", SSH_CHANNEL_OPENING,
	new_fd[0], new_fd[1], new_fd[2], window, packetmax,
	CHAN_EXTENDED_WRITE, "client-session", /nonblock/0);

	/* XXX */
	c->ctl_fd = client_fd;

	debug3("%s: channel_new: %d", __func__, c->self);

	channel_send_open(c->self);
	channel_register_open_confirm(c->self,
	client_extra_session2_setup, cctx);
	return 0;
	}

	/* ** Multiplexing client support */

	/* Exit signal handler */
	static void
	control_client_sighandler(int signo)
	{
	muxclient_terminate = signo;
	}

	/*
	* Relay signal handler - used to pass some signals from mux client to
	* mux master.
	*/
	static void
	control_client_sigrelay(int signo)
	{
	int save_errno = errno;

	if (muxserver_pid > 1)
	kill(muxserver_pid, signo);

	errno = save_errno;
	}

	/* Check mux client environment variables before passing them to mux master. */
	static int
	env_permitted(char *env)
	{
	int i, ret;
	char name[1024], *cp;

	if ((cp = strchr(env, '=')) == NULL \|\| cp == env)
	return (0);
	ret = snprintf(name, sizeof(name), "%.*s", (int)(cp - env), env);
	if (ret <= 0 \|\| (size_t)ret >= sizeof(name))
	fatal("env_permitted: name '%.100s...' too long", env);

	for (i = 0; i < options.num_send_env; i++)
	if (match_pattern(name, options.send_env[i]))
	return (1);

	return (0);
	}

	/* Multiplex client main loop. */
	void
	muxclient(const char *path)
	{
	struct sockaddr_un addr;
	int i, r, fd, sock, exitval[2], num_env, addr_len;
	Buffer m;
	char *term;
	extern char **environ;
	u_int flags;

	if (muxclient_command == 0)
	muxclient_command = SSHMUX_COMMAND_OPEN;

	switch (options.control_master) {
	case SSHCTL_MASTER_AUTO:
	case SSHCTL_MASTER_AUTO_ASK:
	debug("auto-mux: Trying existing master");
	/* FALLTHROUGH */
	case SSHCTL_MASTER_NO:
	break;
	default:
	return;
	}

	memset(&addr, '\0', sizeof(addr));
	addr.sun_family = AF_UNIX;
	addr_len = offsetof(struct sockaddr_un, sun_path) +
	strlen(path) + 1;

	if (strlcpy(addr.sun_path, path,
	sizeof(addr.sun_path)) >= sizeof(addr.sun_path))
	fatal("ControlPath too long");

	if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
	fatal("%s socket(): %s", __func__, strerror(errno));

	if (connect(sock, (struct sockaddr *)&addr, addr_len) == -1) {
	if (muxclient_command != SSHMUX_COMMAND_OPEN) {
	fatal("Control socket connect(%.100s): %s", path,
	strerror(errno));
	}
	if (errno == ENOENT)
	debug("Control socket \"%.100s\" does not exist", path);
	else {
	error("Control socket connect(%.100s): %s", path,
	strerror(errno));
	}
	close(sock);
	return;
	}

	if (stdin_null_flag) {
	if ((fd = open(_PATH_DEVNULL, O_RDONLY)) == -1)
	fatal("open(/dev/null): %s", strerror(errno));
	if (dup2(fd, STDIN_FILENO) == -1)
	fatal("dup2: %s", strerror(errno));
	if (fd > STDERR_FILENO)
	close(fd);
	}

	term = getenv("TERM");

	flags = 0;
	if (tty_flag)
	flags \|= SSHMUX_FLAG_TTY;
	if (subsystem_flag)
	flags \|= SSHMUX_FLAG_SUBSYS;
	if (options.forward_x11)
	flags \|= SSHMUX_FLAG_X11_FWD;
	if (options.forward_agent)
	flags \|= SSHMUX_FLAG_AGENT_FWD;

	signal(SIGPIPE, SIG_IGN);

	buffer_init(&m);

	/* Send our command to server */
	buffer_put_int(&m, muxclient_command);
	buffer_put_int(&m, flags);
	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
	fatal("%s: msg_send", __func__);
	buffer_clear(&m);

	/* Get authorisation status and PID of controlee */
	if (ssh_msg_recv(sock, &m) == -1)
	fatal("%s: msg_recv", __func__);
	if (buffer_get_char(&m) != SSHMUX_VER)
	fatal("%s: wrong version", __func__);
	if (buffer_get_int(&m) != 1)
	fatal("Connection to master denied");
	muxserver_pid = buffer_get_int(&m);

	buffer_clear(&m);

	switch (muxclient_command) {
	case SSHMUX_COMMAND_ALIVE_CHECK:
	fprintf(stderr, "Master running (pid=%d)\r\n",
	muxserver_pid);
	exit(0);
	case SSHMUX_COMMAND_TERMINATE:
	fprintf(stderr, "Exit request sent.\r\n");
	exit(0);
	case SSHMUX_COMMAND_OPEN:
	/* continue below */
	break;
	default:
	fatal("silly muxclient_command %d", muxclient_command);
	}

	/* SSHMUX_COMMAND_OPEN */
	buffer_put_cstring(&m, term ? term : "");
	buffer_append(&command, "\0", 1);
	buffer_put_cstring(&m, buffer_ptr(&command));

	if (options.num_send_env == 0 \|\| environ == NULL) {
	buffer_put_int(&m, 0);
	} else {
	/* Pass environment */
	num_env = 0;
	for (i = 0; environ[i] != NULL; i++)
	if (env_permitted(environ[i]))
	num_env++; /* Count */

	buffer_put_int(&m, num_env);

	for (i = 0; environ[i] != NULL && num_env >= 0; i++)
	if (env_permitted(environ[i])) {
	num_env--;
	buffer_put_cstring(&m, environ[i]);
	}
	}

	if (ssh_msg_send(sock, SSHMUX_VER, &m) == -1)
	fatal("%s: msg_send", __func__);

	if (mm_send_fd(sock, STDIN_FILENO) == -1 \|\|
	mm_send_fd(sock, STDOUT_FILENO) == -1 \|\|
	mm_send_fd(sock, STDERR_FILENO) == -1)
	fatal("%s: send fds failed", __func__);

	/* Wait for reply, so master has a chance to gather ttymodes */
	buffer_clear(&m);
	if (ssh_msg_recv(sock, &m) == -1)
	fatal("%s: msg_recv", __func__);
	if (buffer_get_char(&m) != SSHMUX_VER)
	fatal("%s: wrong version", __func__);
	buffer_free(&m);

	signal(SIGHUP, control_client_sighandler);
	signal(SIGINT, control_client_sighandler);
	signal(SIGTERM, control_client_sighandler);
	signal(SIGWINCH, control_client_sigrelay);

	if (tty_flag)
	enter_raw_mode();

	/*
	* Stick around until the controlee closes the client_fd.
	* Before it does, it is expected to write this process' exit
	* value (one int). This process must read the value and wait for
	* the closure of the client_fd; if this one closes early, the
	* multiplex master will terminate early too (possibly losing data).
	*/
	exitval[0] = 0;
	for (i = 0; !muxclient_terminate && i < (int)sizeof(exitval);) {
	r = read(sock, (char *)exitval + i, sizeof(exitval) - i);
	if (r == 0) {
	debug2("Received EOF from master");
	break;
	}
	if (r == -1) {
	if (errno == EINTR)
	continue;
	fatal("%s: read %s", __func__, strerror(errno));
	}
	i += r;
	}

	close(sock);
	leave_raw_mode();
	if (i > (int)sizeof(int))
	fatal("%s: master returned too much data (%d > %lu)",
	__func__, i, sizeof(int));
	if (muxclient_terminate) {
	debug2("Exiting on signal %d", muxclient_terminate);
	exitval[0] = 255;
	} else if (i < (int)sizeof(int)) {
	debug2("Control master terminated unexpectedly");
	exitval[0] = 255;
	} else
	debug2("Received exit status from master %d", exitval[0]);

	if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
	fprintf(stderr, "Shared connection to %s closed.\r\n", host);

	exit(exitval[0]);
	}