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Use new channel status confirmation callback system to properly deal
with "important" channel requests that fail, in particular command exec,
shell and subsystem requests. Previously we would optimistically assume
that the requests would always succeed, which could cause hangs if they
did not (e.g. when the server runs out of fds) or were unimplemented by
the server (bz #1384)

Also, properly report failing multiplex channel requests via the mux
client stderr (subject to LogLevel in the mux master) - better than
silently failing.

most bits ok markus@ (as part of a larger diff)

/* $OpenBSD: ssh.c,v 1.311 2008/05/08 13:06:11 djm Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Ssh client program.  This program can be used to log into a remote machine.
 * The software supports strong authentication, encryption, and forwarding
 * of X11, TCP/IP, and authentication connections.
 *
 * 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".
 *
 * Copyright (c) 1999 Niels Provos.  All rights reserved.
 * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
 *
 * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
 * in Canada (German citizen).
 *
 * 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 <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/stat.h>
#include <sys/queue.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <openssl/evp.h>
#include <openssl/err.h>

#include "xmalloc.h"
#include "ssh.h"
#include "ssh1.h"
#include "ssh2.h"
#include "compat.h"
#include "cipher.h"
#include "packet.h"
#include "buffer.h"
#include "channels.h"
#include "key.h"
#include "authfd.h"
#include "authfile.h"
#include "pathnames.h"
#include "dispatch.h"
#include "clientloop.h"
#include "log.h"
#include "readconf.h"
#include "sshconnect.h"
#include "misc.h"
#include "kex.h"
#include "mac.h"
#include "sshpty.h"
#include "match.h"
#include "msg.h"
#include "monitor_fdpass.h"
#include "uidswap.h"
#include "version.h"

#ifdef SMARTCARD
#include "scard.h"
#endif

extern char *__progname;

/* Flag indicating whether debug mode is on.  This can be set on the command line. */
int debug_flag = 0;

/* Flag indicating whether a tty should be allocated */
int tty_flag = 0;
int no_tty_flag = 0;
int force_tty_flag = 0;

/* don't exec a shell */
int no_shell_flag = 0;

/*
 * Flag indicating that nothing should be read from stdin.  This can be set
 * on the command line.
 */
int stdin_null_flag = 0;

/*
 * Flag indicating that ssh should fork after authentication.  This is useful
 * so that the passphrase can be entered manually, and then ssh goes to the
 * background.
 */
int fork_after_authentication_flag = 0;

/*
 * General data structure for command line options and options configurable
 * in configuration files.  See readconf.h.
 */
Options options;

/* optional user configfile */
char *config = NULL;

/*
 * Name of the host we are connecting to.  This is the name given on the
 * command line, or the HostName specified for the user-supplied name in a
 * configuration file.
 */
char *host;

/* socket address the host resolves to */
struct sockaddr_storage hostaddr;

/* Private host keys. */
Sensitive sensitive_data;

/* Original real UID. */
uid_t original_real_uid;
uid_t original_effective_uid;

/* command to be executed */
Buffer command;

/* Should we execute a command or invoke a subsystem? */
int subsystem_flag = 0;

/* # of replies received for global requests */
static int client_global_request_id = 0;

/* pid of proxycommand child process */
pid_t proxy_command_pid = 0;

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

/* Multiplexing control command */
static u_int mux_command = 0;

/* Only used in control client mode */
volatile sig_atomic_t control_client_terminate = 0;
u_int control_server_pid = 0;

/* Prints a help message to the user.  This function never returns. */

static void
usage(void)
{
	fprintf(stderr,
"usage: ssh [-1246AaCfgKkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
"           [-D [bind_address:]port] [-e escape_char] [-F configfile]\n"
"           [-i identity_file] [-L [bind_address:]port:host:hostport]\n"
"           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
"           [-R [bind_address:]port:host:hostport] [-S ctl_path]\n"
"           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
	);
	exit(255);
}

static int ssh_session(void);
static int ssh_session2(void);
static void load_public_identity_files(void);
static void control_client(const char *path);

/*
 * Main program for the ssh client.
 */
int
main(int ac, char **av)
{
	int i, opt, exit_status;
	char *p, *cp, *line, buf[256];
	struct stat st;
	struct passwd *pw;
	int dummy, timeout_ms;
	extern int optind, optreset;
	extern char *optarg;
	struct servent *sp;
	Forward fwd;

	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
	sanitise_stdfd();

	/*
	 * Save the original real uid.  It will be needed later (uid-swapping
	 * may clobber the real uid).
	 */
	original_real_uid = getuid();
	original_effective_uid = geteuid();

	/*
	 * Use uid-swapping to give up root privileges for the duration of
	 * option processing.  We will re-instantiate the rights when we are
	 * ready to create the privileged port, and will permanently drop
	 * them when the port has been created (actually, when the connection
	 * has been made, as we may need to create the port several times).
	 */
	PRIV_END;

	/* If we are installed setuid root be careful to not drop core. */
	if (original_real_uid != original_effective_uid) {
		struct rlimit rlim;
		rlim.rlim_cur = rlim.rlim_max = 0;
		if (setrlimit(RLIMIT_CORE, &rlim) < 0)
			fatal("setrlimit failed: %.100s", strerror(errno));
	}
	/* Get user data. */
	pw = getpwuid(original_real_uid);
	if (!pw) {
		logit("You don't exist, go away!");
		exit(255);
	}
	/* Take a copy of the returned structure. */
	pw = pwcopy(pw);

	/*
	 * Set our umask to something reasonable, as some files are created
	 * with the default umask.  This will make them world-readable but
	 * writable only by the owner, which is ok for all files for which we
	 * don't set the modes explicitly.
	 */
	umask(022);

	/* Initialize option structure to indicate that no values have been set. */
	initialize_options(&options);

	/* Parse command-line arguments. */
	host = NULL;

 again:
	while ((opt = getopt(ac, av,
	    "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:KL:MNO:PR:S:TVw:XY")) != -1) {
		switch (opt) {
		case '1':
			options.protocol = SSH_PROTO_1;
			break;
		case '2':
			options.protocol = SSH_PROTO_2;
			break;
		case '4':
			options.address_family = AF_INET;
			break;
		case '6':
			options.address_family = AF_INET6;
			break;
		case 'n':
			stdin_null_flag = 1;
			break;
		case 'f':
			fork_after_authentication_flag = 1;
			stdin_null_flag = 1;
			break;
		case 'x':
			options.forward_x11 = 0;
			break;
		case 'X':
			options.forward_x11 = 1;
			break;
		case 'Y':
			options.forward_x11 = 1;
			options.forward_x11_trusted = 1;
			break;
		case 'g':
			options.gateway_ports = 1;
			break;
		case 'O':
			if (strcmp(optarg, "check") == 0)
				mux_command = SSHMUX_COMMAND_ALIVE_CHECK;
			else if (strcmp(optarg, "exit") == 0)
				mux_command = SSHMUX_COMMAND_TERMINATE;
			else
				fatal("Invalid multiplex command.");
			break;
		case 'P':	/* deprecated */
			options.use_privileged_port = 0;
			break;
		case 'a':
			options.forward_agent = 0;
			break;
		case 'A':
			options.forward_agent = 1;
			break;
		case 'k':
			options.gss_deleg_creds = 0;
			break;
		case 'K':
			options.gss_authentication = 1;
			options.gss_deleg_creds = 1;
			break;
		case 'i':
			if (stat(optarg, &st) < 0) {
				fprintf(stderr, "Warning: Identity file %s "
				    "not accessible: %s.\n", optarg,
				    strerror(errno));
				break;
			}
			if (options.num_identity_files >=
			    SSH_MAX_IDENTITY_FILES)
				fatal("Too many identity files specified "
				    "(max %d)", SSH_MAX_IDENTITY_FILES);
			options.identity_files[options.num_identity_files++] =
			    xstrdup(optarg);
			break;
		case 'I':
#ifdef SMARTCARD
			options.smartcard_device = xstrdup(optarg);
#else
			fprintf(stderr, "no support for smartcards.\n");
#endif
			break;
		case 't':
			if (tty_flag)
				force_tty_flag = 1;
			tty_flag = 1;
			break;
		case 'v':
			if (debug_flag == 0) {
				debug_flag = 1;
				options.log_level = SYSLOG_LEVEL_DEBUG1;
			} else {
				if (options.log_level < SYSLOG_LEVEL_DEBUG3)
					options.log_level++;
				break;
			}
			/* FALLTHROUGH */
		case 'V':
			fprintf(stderr, "%s, %s\n",
			    SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
			if (opt == 'V')
				exit(0);
			break;
		case 'w':
			if (options.tun_open == -1)
				options.tun_open = SSH_TUNMODE_DEFAULT;
			options.tun_local = a2tun(optarg, &options.tun_remote);
			if (options.tun_local == SSH_TUNID_ERR) {
				fprintf(stderr, "Bad tun device '%s'\n", optarg);
				exit(255);
			}
			break;
		case 'q':
			options.log_level = SYSLOG_LEVEL_QUIET;
			break;
		case 'e':
			if (optarg[0] == '^' && optarg[2] == 0 &&
			    (u_char) optarg[1] >= 64 &&
			    (u_char) optarg[1] < 128)
				options.escape_char = (u_char) optarg[1] & 31;
			else if (strlen(optarg) == 1)
				options.escape_char = (u_char) optarg[0];
			else if (strcmp(optarg, "none") == 0)
				options.escape_char = SSH_ESCAPECHAR_NONE;
			else {
				fprintf(stderr, "Bad escape character '%s'.\n",
				    optarg);
				exit(255);
			}
			break;
		case 'c':
			if (ciphers_valid(optarg)) {
				/* SSH2 only */
				options.ciphers = xstrdup(optarg);
				options.cipher = SSH_CIPHER_INVALID;
			} else {
				/* SSH1 only */
				options.cipher = cipher_number(optarg);
				if (options.cipher == -1) {
					fprintf(stderr,
					    "Unknown cipher type '%s'\n",
					    optarg);
					exit(255);
				}
				if (options.cipher == SSH_CIPHER_3DES)
					options.ciphers = "3des-cbc";
				else if (options.cipher == SSH_CIPHER_BLOWFISH)
					options.ciphers = "blowfish-cbc";
				else
					options.ciphers = (char *)-1;
			}
			break;
		case 'm':
			if (mac_valid(optarg))
				options.macs = xstrdup(optarg);
			else {
				fprintf(stderr, "Unknown mac type '%s'\n",
				    optarg);
				exit(255);
			}
			break;
		case 'M':
			if (options.control_master == SSHCTL_MASTER_YES)
				options.control_master = SSHCTL_MASTER_ASK;
			else
				options.control_master = SSHCTL_MASTER_YES;
			break;
		case 'p':
			options.port = a2port(optarg);
			if (options.port == 0) {
				fprintf(stderr, "Bad port '%s'\n", optarg);
				exit(255);
			}
			break;
		case 'l':
			options.user = optarg;
			break;

		case 'L':
			if (parse_forward(&fwd, optarg))
				add_local_forward(&options, &fwd);
			else {
				fprintf(stderr,
				    "Bad local forwarding specification '%s'\n",
				    optarg);
				exit(255);
			}
			break;

		case 'R':
			if (parse_forward(&fwd, optarg)) {
				add_remote_forward(&options, &fwd);
			} else {
				fprintf(stderr,
				    "Bad remote forwarding specification "
				    "'%s'\n", optarg);
				exit(255);
			}
			break;

		case 'D':
			cp = p = xstrdup(optarg);
			memset(&fwd, '\0', sizeof(fwd));
			fwd.connect_host = "socks";
			if ((fwd.listen_host = hpdelim(&cp)) == NULL) {
				fprintf(stderr, "Bad dynamic forwarding "
				    "specification '%.100s'\n", optarg);
				exit(255);
			}
			if (cp != NULL) {
				fwd.listen_port = a2port(cp);
				fwd.listen_host = cleanhostname(fwd.listen_host);
			} else {
				fwd.listen_port = a2port(fwd.listen_host);
				fwd.listen_host = NULL;
			}

			if (fwd.listen_port == 0) {
				fprintf(stderr, "Bad dynamic port '%s'\n",
				    optarg);
				exit(255);
			}
			add_local_forward(&options, &fwd);
			xfree(p);
			break;

		case 'C':
			options.compression = 1;
			break;
		case 'N':
			no_shell_flag = 1;
			no_tty_flag = 1;
			break;
		case 'T':
			no_tty_flag = 1;
			break;
		case 'o':
			dummy = 1;
			line = xstrdup(optarg);
			if (process_config_line(&options, host ? host : "",
			    line, "command-line", 0, &dummy) != 0)
				exit(255);
			xfree(line);
			break;
		case 's':
			subsystem_flag = 1;
			break;
		case 'S':
			if (options.control_path != NULL)
				free(options.control_path);
			options.control_path = xstrdup(optarg);
			break;
		case 'b':
			options.bind_address = optarg;
			break;
		case 'F':
			config = optarg;
			break;
		default:
			usage();
		}
	}

	ac -= optind;
	av += optind;

	if (ac > 0 && !host && **av != '-') {
		if (strrchr(*av, '@')) {
			p = xstrdup(*av);
			cp = strrchr(p, '@');
			if (cp == NULL || cp == p)
				usage();
			options.user = p;
			*cp = '\0';
			host = ++cp;
		} else
			host = *av;
		if (ac > 1) {
			optind = optreset = 1;
			goto again;
		}
		ac--, av++;
	}

	/* Check that we got a host name. */
	if (!host)
		usage();

	SSLeay_add_all_algorithms();
	ERR_load_crypto_strings();

	/* Initialize the command to execute on remote host. */
	buffer_init(&command);

	/*
	 * Save the command to execute on the remote host in a buffer. There
	 * is no limit on the length of the command, except by the maximum
	 * packet size.  Also sets the tty flag if there is no command.
	 */
	if (!ac) {
		/* No command specified - execute shell on a tty. */
		tty_flag = 1;
		if (subsystem_flag) {
			fprintf(stderr,
			    "You must specify a subsystem to invoke.\n");
			usage();
		}
	} else {
		/* A command has been specified.  Store it into the buffer. */
		for (i = 0; i < ac; i++) {
			if (i)
				buffer_append(&command, " ", 1);
			buffer_append(&command, av[i], strlen(av[i]));
		}
	}

	/* Cannot fork to background if no command. */
	if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
		fatal("Cannot fork into background without a command to execute.");

	/* Allocate a tty by default if no command specified. */
	if (buffer_len(&command) == 0)
		tty_flag = 1;

	/* Force no tty */
	if (no_tty_flag)
		tty_flag = 0;
	/* Do not allocate a tty if stdin is not a tty. */
	if ((!isatty(fileno(stdin)) || stdin_null_flag) && !force_tty_flag) {
		if (tty_flag)
			logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
		tty_flag = 0;
	}

	/*
	 * Initialize "log" output.  Since we are the client all output
	 * actually goes to stderr.
	 */
	log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
	    SYSLOG_FACILITY_USER, 1);

	/*
	 * Read per-user configuration file.  Ignore the system wide config
	 * file if the user specifies a config file on the command line.
	 */
	if (config != NULL) {
		if (!read_config_file(config, host, &options, 0))
			fatal("Can't open user config file %.100s: "
			    "%.100s", config, strerror(errno));
	} else {
		snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
		    _PATH_SSH_USER_CONFFILE);
		(void)read_config_file(buf, host, &options, 1);

		/* Read systemwide configuration file after use config. */
		(void)read_config_file(_PATH_HOST_CONFIG_FILE, host,
		    &options, 0);
	}

	/* Fill configuration defaults. */
	fill_default_options(&options);

	channel_set_af(options.address_family);

	/* reinit */
	log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);

	if (options.user == NULL)
		options.user = xstrdup(pw->pw_name);

	if (options.hostname != NULL)
		host = options.hostname;

	/* force lowercase for hostkey matching */
	if (options.host_key_alias != NULL) {
		for (p = options.host_key_alias; *p; p++)
			if (isupper(*p))
				*p = (char)tolower(*p);
	}

	/* Get default port if port has not been set. */
	if (options.port == 0) {
		sp = getservbyname(SSH_SERVICE_NAME, "tcp");
		options.port = sp ? ntohs(sp->s_port) : SSH_DEFAULT_PORT;
	}

	if (options.proxy_command != NULL &&
	    strcmp(options.proxy_command, "none") == 0) {
		xfree(options.proxy_command);
		options.proxy_command = NULL;
	}
	if (options.control_path != NULL &&
	    strcmp(options.control_path, "none") == 0) {
		xfree(options.control_path);
		options.control_path = NULL;
	}

	if (options.control_path != NULL) {
		char thishost[NI_MAXHOST];

		if (gethostname(thishost, sizeof(thishost)) == -1)
			fatal("gethostname: %s", strerror(errno));
		snprintf(buf, sizeof(buf), "%d", options.port);
		cp = tilde_expand_filename(options.control_path,
		    original_real_uid);
		xfree(options.control_path);
		options.control_path = percent_expand(cp, "p", buf, "h", host,
		    "r", options.user, "l", thishost, (char *)NULL);
		xfree(cp);
	}
	if (mux_command != 0 && options.control_path == NULL)
		fatal("No ControlPath specified for \"-O\" command");
	if (options.control_path != NULL)
		control_client(options.control_path);

	timeout_ms = options.connection_timeout * 1000;

	/* Open a connection to the remote host. */
	if (ssh_connect(host, &hostaddr, options.port,
	    options.address_family, options.connection_attempts, &timeout_ms,
	    options.tcp_keep_alive, 
	    original_effective_uid == 0 && options.use_privileged_port,
	    options.proxy_command) != 0)
		exit(255);

	if (timeout_ms > 0)
		debug3("timeout: %d ms remain after connect", timeout_ms);

	/*
	 * If we successfully made the connection, load the host private key
	 * in case we will need it later for combined rsa-rhosts
	 * authentication. This must be done before releasing extra
	 * privileges, because the file is only readable by root.
	 * If we cannot access the private keys, load the public keys
	 * instead and try to execute the ssh-keysign helper instead.
	 */
	sensitive_data.nkeys = 0;
	sensitive_data.keys = NULL;
	sensitive_data.external_keysign = 0;
	if (options.rhosts_rsa_authentication ||
	    options.hostbased_authentication) {
		sensitive_data.nkeys = 3;
		sensitive_data.keys = xcalloc(sensitive_data.nkeys,
		    sizeof(Key));

		PRIV_START;
		sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
		    _PATH_HOST_KEY_FILE, "", NULL, NULL);
		sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
		    _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
		sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
		    _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
		PRIV_END;

		if (options.hostbased_authentication == 1 &&
		    sensitive_data.keys[0] == NULL &&
		    sensitive_data.keys[1] == NULL &&
		    sensitive_data.keys[2] == NULL) {
			sensitive_data.keys[1] = key_load_public(
			    _PATH_HOST_DSA_KEY_FILE, NULL);
			sensitive_data.keys[2] = key_load_public(
			    _PATH_HOST_RSA_KEY_FILE, NULL);
			sensitive_data.external_keysign = 1;
		}
	}
	/*
	 * Get rid of any extra privileges that we may have.  We will no
	 * longer need them.  Also, extra privileges could make it very hard
	 * to read identity files and other non-world-readable files from the
	 * user's home directory if it happens to be on a NFS volume where
	 * root is mapped to nobody.
	 */
	if (original_effective_uid == 0) {
		PRIV_START;
		permanently_set_uid(pw);
	}

	/*
	 * Now that we are back to our own permissions, create ~/.ssh
	 * directory if it doesn't already exist.
	 */
	snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
	if (stat(buf, &st) < 0)
		if (mkdir(buf, 0700) < 0)
			error("Could not create directory '%.200s'.", buf);

	/* load options.identity_files */
	load_public_identity_files();

	/* Expand ~ in known host file names. */
	/* XXX mem-leaks: */
	options.system_hostfile =
	    tilde_expand_filename(options.system_hostfile, original_real_uid);
	options.user_hostfile =
	    tilde_expand_filename(options.user_hostfile, original_real_uid);
	options.system_hostfile2 =
	    tilde_expand_filename(options.system_hostfile2, original_real_uid);
	options.user_hostfile2 =
	    tilde_expand_filename(options.user_hostfile2, original_real_uid);

	signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */

	/* Log into the remote system.  This never returns if the login fails. */
	ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
	    pw, timeout_ms);

	/* We no longer need the private host keys.  Clear them now. */
	if (sensitive_data.nkeys != 0) {
		for (i = 0; i < sensitive_data.nkeys; i++) {
			if (sensitive_data.keys[i] != NULL) {
				/* Destroys contents safely */
				debug3("clear hostkey %d", i);
				key_free(sensitive_data.keys[i]);
				sensitive_data.keys[i] = NULL;
			}
		}
		xfree(sensitive_data.keys);
	}
	for (i = 0; i < options.num_identity_files; i++) {
		if (options.identity_files[i]) {
			xfree(options.identity_files[i]);
			options.identity_files[i] = NULL;
		}
		if (options.identity_keys[i]) {
			key_free(options.identity_keys[i]);
			options.identity_keys[i] = NULL;
		}
	}

	exit_status = compat20 ? ssh_session2() : ssh_session();
	packet_close();

	if (options.control_path != NULL && control_fd != -1)
		unlink(options.control_path);

	/*
	 * Send SIGHUP to proxy command if used. We don't wait() in
	 * case it hangs and instead rely on init to reap the child
	 */
	if (proxy_command_pid > 1)
		kill(proxy_command_pid, SIGHUP);

	return exit_status;
}

static void
ssh_init_forwarding(void)
{
	int success = 0;
	int i;

	/* Initiate local TCP/IP port forwardings. */
	for (i = 0; i < options.num_local_forwards; i++) {
		debug("Local connections to %.200s:%d forwarded to remote "
		    "address %.200s:%d",
		    (options.local_forwards[i].listen_host == NULL) ?
		    (options.gateway_ports ? "*" : "LOCALHOST") :
		    options.local_forwards[i].listen_host,
		    options.local_forwards[i].listen_port,
		    options.local_forwards[i].connect_host,
		    options.local_forwards[i].connect_port);
		success += channel_setup_local_fwd_listener(
		    options.local_forwards[i].listen_host,
		    options.local_forwards[i].listen_port,
		    options.local_forwards[i].connect_host,
		    options.local_forwards[i].connect_port,
		    options.gateway_ports);
	}
	if (i > 0 && success != i && options.exit_on_forward_failure)
		fatal("Could not request local forwarding.");
	if (i > 0 && success == 0)
		error("Could not request local forwarding.");

	/* Initiate remote TCP/IP port forwardings. */
	for (i = 0; i < options.num_remote_forwards; i++) {
		debug("Remote connections from %.200s:%d forwarded to "
		    "local address %.200s:%d",
		    (options.remote_forwards[i].listen_host == NULL) ?
		    "LOCALHOST" : options.remote_forwards[i].listen_host,
		    options.remote_forwards[i].listen_port,
		    options.remote_forwards[i].connect_host,
		    options.remote_forwards[i].connect_port);
		if (channel_request_remote_forwarding(
		    options.remote_forwards[i].listen_host,
		    options.remote_forwards[i].listen_port,
		    options.remote_forwards[i].connect_host,
		    options.remote_forwards[i].connect_port) < 0) {
			if (options.exit_on_forward_failure)
				fatal("Could not request remote forwarding.");
			else
				logit("Warning: Could not request remote "
				    "forwarding.");
		}
	}

	/* Initiate tunnel forwarding. */
	if (options.tun_open != SSH_TUNMODE_NO) {
		if (client_request_tun_fwd(options.tun_open,
		    options.tun_local, options.tun_remote) == -1) {
			if (options.exit_on_forward_failure)
				fatal("Could not request tunnel forwarding.");
			else
				error("Could not request tunnel forwarding.");
		}
	}			
}

static void
check_agent_present(void)
{
	if (options.forward_agent) {
		/* Clear agent forwarding if we don't have an agent. */
		if (!ssh_agent_present())
			options.forward_agent = 0;
	}
}

static int
ssh_session(void)
{
	int type;
	int interactive = 0;
	int have_tty = 0;
	struct winsize ws;
	char *cp;
	const char *display;

	/* Enable compression if requested. */
	if (options.compression) {
		debug("Requesting compression at level %d.", options.compression_level);

		if (options.compression_level < 1 || options.compression_level > 9)
			fatal("Compression level must be from 1 (fast) to 9 (slow, best).");

		/* Send the request. */
		packet_start(SSH_CMSG_REQUEST_COMPRESSION);
		packet_put_int(options.compression_level);
		packet_send();
		packet_write_wait();
		type = packet_read();
		if (type == SSH_SMSG_SUCCESS)
			packet_start_compression(options.compression_level);
		else if (type == SSH_SMSG_FAILURE)
			logit("Warning: Remote host refused compression.");
		else
			packet_disconnect("Protocol error waiting for compression response.");
	}
	/* Allocate a pseudo tty if appropriate. */
	if (tty_flag) {
		debug("Requesting pty.");

		/* Start the packet. */
		packet_start(SSH_CMSG_REQUEST_PTY);

		/* Store TERM in the packet.  There is no limit on the
		   length of the string. */
		cp = getenv("TERM");
		if (!cp)
			cp = "";
		packet_put_cstring(cp);

		/* Store window size in the packet. */
		if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
			memset(&ws, 0, sizeof(ws));
		packet_put_int((u_int)ws.ws_row);
		packet_put_int((u_int)ws.ws_col);
		packet_put_int((u_int)ws.ws_xpixel);
		packet_put_int((u_int)ws.ws_ypixel);

		/* Store tty modes in the packet. */
		tty_make_modes(fileno(stdin), NULL);

		/* Send the packet, and wait for it to leave. */
		packet_send();
		packet_write_wait();

		/* Read response from the server. */
		type = packet_read();
		if (type == SSH_SMSG_SUCCESS) {
			interactive = 1;
			have_tty = 1;
		} else if (type == SSH_SMSG_FAILURE)
			logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
		else
			packet_disconnect("Protocol error waiting for pty request response.");
	}
	/* Request X11 forwarding if enabled and DISPLAY is set. */
	display = getenv("DISPLAY");
	if (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(0, display, proto, data);

		/* Read response from the server. */
		type = packet_read();
		if (type == SSH_SMSG_SUCCESS) {
			interactive = 1;
		} else if (type == SSH_SMSG_FAILURE) {
			logit("Warning: Remote host denied X11 forwarding.");
		} else {
			packet_disconnect("Protocol error waiting for X11 forwarding");
		}
	}
	/* Tell the packet module whether this is an interactive session. */
	packet_set_interactive(interactive);

	/* Request authentication agent forwarding if appropriate. */
	check_agent_present();

	if (options.forward_agent) {
		debug("Requesting authentication agent forwarding.");
		auth_request_forwarding();

		/* Read response from the server. */
		type = packet_read();
		packet_check_eom();
		if (type != SSH_SMSG_SUCCESS)
			logit("Warning: Remote host denied authentication agent forwarding.");
	}

	/* Initiate port forwardings. */
	ssh_init_forwarding();

	/* Execute a local command */
	if (options.local_command != NULL &&
	    options.permit_local_command)
		ssh_local_cmd(options.local_command);

	/* If requested, let ssh continue in the background. */
	if (fork_after_authentication_flag)
		if (daemon(1, 1) < 0)
			fatal("daemon() failed: %.200s", strerror(errno));

	/*
	 * If a command was specified on the command line, execute the
	 * command now. Otherwise request the server to start a shell.
	 */
	if (buffer_len(&command) > 0) {
		int len = buffer_len(&command);
		if (len > 900)
			len = 900;
		debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
		packet_start(SSH_CMSG_EXEC_CMD);
		packet_put_string(buffer_ptr(&command), buffer_len(&command));
		packet_send();
		packet_write_wait();
	} else {
		debug("Requesting shell.");
		packet_start(SSH_CMSG_EXEC_SHELL);
		packet_send();
		packet_write_wait();
	}

	/* Enter the interactive session. */
	return client_loop(have_tty, tty_flag ?
	    options.escape_char : SSH_ESCAPECHAR_NONE, 0);
}

void
client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
{
	int i;

	i = client_global_request_id++;
	if (i >= options.num_remote_forwards)
		return;
	debug("remote forward %s for: listen %d, connect %s:%d",
	    type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
	    options.remote_forwards[i].listen_port,
	    options.remote_forwards[i].connect_host,
	    options.remote_forwards[i].connect_port);
	if (type == SSH2_MSG_REQUEST_FAILURE) {
		if (options.exit_on_forward_failure)
			fatal("Error: remote port forwarding failed for "
			    "listen port %d",
			    options.remote_forwards[i].listen_port);
		else
			logit("Warning: remote port forwarding failed for "
			    "listen port %d",
			    options.remote_forwards[i].listen_port);
	}
}

static void
ssh_control_listener(void)
{
	struct sockaddr_un addr;
	mode_t old_umask;

	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.sun_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 ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
		fatal("%s socket(): %s", __func__, strerror(errno));

	old_umask = umask(0177);
	if (bind(control_fd, (struct sockaddr *)&addr, addr.sun_len) == -1) {
		control_fd = -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(control_fd, 64) == -1)
		fatal("%s listen(): %s", __func__, strerror(errno));

	set_nonblock(control_fd);
}

/* request pty/x11/agent/tcpfwd/shell for channel */
static void
ssh_session2_setup(int id, void *arg)
{
	extern char **environ;
	const char *display;
	int interactive = tty_flag;

	display = getenv("DISPLAY");
	if (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);
		interactive = 1;
		/* XXX wait for reply */
	}

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

	client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
	    NULL, fileno(stdin), &command, environ);

	packet_set_interactive(interactive);
}

/* open new channel for a session */
static int
ssh_session2_open(void)
{
	Channel *c;
	int window, packetmax, in, out, err;

	if (stdin_null_flag) {
		in = open(_PATH_DEVNULL, O_RDONLY);
	} else {
		in = dup(STDIN_FILENO);
	}
	out = dup(STDOUT_FILENO);
	err = dup(STDERR_FILENO);

	if (in < 0 || out < 0 || err < 0)
		fatal("dup() in/out/err failed");

	/* enable nonblocking unless tty */
	if (!isatty(in))
		set_nonblock(in);
	if (!isatty(out))
		set_nonblock(out);
	if (!isatty(err))
		set_nonblock(err);

	window = CHAN_SES_WINDOW_DEFAULT;
	packetmax = CHAN_SES_PACKET_DEFAULT;
	if (tty_flag) {
		window >>= 1;
		packetmax >>= 1;
	}
	c = channel_new(
	    "session", SSH_CHANNEL_OPENING, in, out, err,
	    window, packetmax, CHAN_EXTENDED_WRITE,
	    "client-session", /*nonblock*/0);

	debug3("ssh_session2_open: channel_new: %d", c->self);

	channel_send_open(c->self);
	if (!no_shell_flag)
		channel_register_open_confirm(c->self,
		    ssh_session2_setup, NULL);

	return c->self;
}

static int
ssh_session2(void)
{
	int id = -1;

	/* XXX should be pre-session */
	ssh_init_forwarding();

	if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
		id = ssh_session2_open();

	/* Execute a local command */
	if (options.local_command != NULL &&
	    options.permit_local_command)
		ssh_local_cmd(options.local_command);

	/* Start listening for multiplex clients */
	ssh_control_listener();

	/* If requested, let ssh continue in the background. */
	if (fork_after_authentication_flag)
		if (daemon(1, 1) < 0)
			fatal("daemon() failed: %.200s", strerror(errno));

	return client_loop(tty_flag, tty_flag ?
	    options.escape_char : SSH_ESCAPECHAR_NONE, id);
}

static void
load_public_identity_files(void)
{
	char *filename, *cp, thishost[NI_MAXHOST];
	char *pwdir = NULL, *pwname = NULL;
	int i = 0;
	Key *public;
	struct passwd *pw;
#ifdef SMARTCARD
	Key **keys;

	if (options.smartcard_device != NULL &&
	    options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
	    (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL) {
		int count = 0;
		for (i = 0; keys[i] != NULL; i++) {
			count++;
			memmove(&options.identity_files[1], &options.identity_files[0],
			    sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
			memmove(&options.identity_keys[1], &options.identity_keys[0],
			    sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
			options.num_identity_files++;
			options.identity_keys[0] = keys[i];
			options.identity_files[0] = sc_get_key_label(keys[i]);
		}
		if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
			options.num_identity_files = SSH_MAX_IDENTITY_FILES;
		i = count;
		xfree(keys);
	}
#endif /* SMARTCARD */
	if ((pw = getpwuid(original_real_uid)) == NULL)
		fatal("load_public_identity_files: getpwuid failed");
	pwname = xstrdup(pw->pw_name);
	pwdir = xstrdup(pw->pw_dir);
	if (gethostname(thishost, sizeof(thishost)) == -1)
		fatal("load_public_identity_files: gethostname: %s",
		    strerror(errno));
	for (; i < options.num_identity_files; i++) {
		cp = tilde_expand_filename(options.identity_files[i],
		    original_real_uid);
		filename = percent_expand(cp, "d", pwdir,
		    "u", pwname, "l", thishost, "h", host,
		    "r", options.user, (char *)NULL);
		xfree(cp);
		public = key_load_public(filename, NULL);
		debug("identity file %s type %d", filename,
		    public ? public->type : -1);
		xfree(options.identity_files[i]);
		options.identity_files[i] = filename;
		options.identity_keys[i] = public;
	}
	bzero(pwname, strlen(pwname));
	xfree(pwname);
	bzero(pwdir, strlen(pwdir));
	xfree(pwdir);
}

static void
control_client_sighandler(int signo)
{
	control_client_terminate = signo;
}

static void
control_client_sigrelay(int signo)
{
	int save_errno = errno;

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

	errno = save_errno;
}

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);
}

static void
control_client(const char *path)
{
	struct sockaddr_un addr;
	int i, r, fd, sock, exitval[2], num_env;
	Buffer m;
	char *term;
	extern char **environ;
	u_int  flags;

	if (mux_command == 0)
		mux_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.sun_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.sun_len) == -1) {
		if (mux_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, mux_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");
	control_server_pid = buffer_get_int(&m);

	buffer_clear(&m);

	switch (mux_command) {
	case SSHMUX_COMMAND_ALIVE_CHECK:
		fprintf(stderr, "Master running (pid=%d)\r\n",
		    control_server_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 mux_command %d", mux_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; !control_client_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 (control_client_terminate) {
		debug2("Exiting on signal %d", control_client_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]);
}