text: /*
   * 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 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 "includes.h"
  RCSID("$OpenBSD: ssh.c,v 1.201 2003/09/01 18:15:50 markus Exp $");
  
  #include <openssl/evp.h>
  #include <openssl/err.h>
  
  #include "ssh.h"
  #include "ssh1.h"
  #include "ssh2.h"
  #include "compat.h"
  #include "cipher.h"
  #include "xmalloc.h"
  #include "packet.h"
  #include "buffer.h"
  #include "channels.h"
  #include "key.h"
  #include "authfd.h"
  #include "authfile.h"
  #include "pathnames.h"
  #include "clientloop.h"
  #include "log.h"
  #include "readconf.h"
  #include "sshconnect.h"
  #include "tildexpand.h"
  #include "dispatch.h"
  #include "misc.h"
  #include "kex.h"
  #include "mac.h"
  #include "sshtty.h"
  
  #ifdef SMARTCARD
  #include "scard.h"
  #endif
  
  #ifdef HAVE___PROGNAME
  extern char *__progname;
  #else
  char *__progname;
  #endif
  
  /* 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;
  
  /* Prints a help message to the user.  This function never returns. */
  
  static void
  usage(void)
  {
  	fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
  	fprintf(stderr, "Options:\n");
  	fprintf(stderr, "  -l user     Log in using this user name.\n");
  	fprintf(stderr, "  -n          Redirect input from " _PATH_DEVNULL ".\n");
  	fprintf(stderr, "  -F config   Config file (default: ~/%s).\n",
  	     _PATH_SSH_USER_CONFFILE);
  	fprintf(stderr, "  -A          Enable authentication agent forwarding.\n");
  	fprintf(stderr, "  -a          Disable authentication agent forwarding (default).\n");
  	fprintf(stderr, "  -X          Enable X11 connection forwarding.\n");
  	fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
  	fprintf(stderr, "  -i file     Identity for public key authentication "
  	    "(default: ~/.ssh/identity)\n");
  #ifdef SMARTCARD
  	fprintf(stderr, "  -I reader   Set smartcard reader.\n");
  #endif
  	fprintf(stderr, "  -t          Tty; allocate a tty even if command is given.\n");
  	fprintf(stderr, "  -T          Do not allocate a tty.\n");
  	fprintf(stderr, "  -v          Verbose; display verbose debugging messages.\n");
  	fprintf(stderr, "              Multiple -v increases verbosity.\n");
  	fprintf(stderr, "  -V          Display version number only.\n");
  	fprintf(stderr, "  -q          Quiet; don't display any warning messages.\n");
  	fprintf(stderr, "  -f          Fork into background after authentication.\n");
  	fprintf(stderr, "  -e char     Set escape character; ``none'' = disable (default: ~).\n");
  
  	fprintf(stderr, "  -c cipher   Select encryption algorithm\n");
  	fprintf(stderr, "  -m macs     Specify MAC algorithms for protocol version 2.\n");
  	fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
  	fprintf(stderr, "  -L listen-port:host:port   Forward local port to remote address\n");
  	fprintf(stderr, "  -R listen-port:host:port   Forward remote port to local address\n");
  	fprintf(stderr, "              These cause %s to listen for connections on a port, and\n", __progname);
  	fprintf(stderr, "              forward them to the other side by connecting to host:port.\n");
  	fprintf(stderr, "  -D port     Enable dynamic application-level port forwarding.\n");
  	fprintf(stderr, "  -C          Enable compression.\n");
  	fprintf(stderr, "  -N          Do not execute a shell or command.\n");
  	fprintf(stderr, "  -g          Allow remote hosts to connect to forwarded ports.\n");
  	fprintf(stderr, "  -1          Force protocol version 1.\n");
  	fprintf(stderr, "  -2          Force protocol version 2.\n");
  	fprintf(stderr, "  -4          Use IPv4 only.\n");
  	fprintf(stderr, "  -6          Use IPv6 only.\n");
  	fprintf(stderr, "  -o 'option' Process the option as if it was read from a configuration file.\n");
  	fprintf(stderr, "  -s          Invoke command (mandatory) as SSH2 subsystem.\n");
  	fprintf(stderr, "  -b addr     Local IP address.\n");
  	exit(1);
  }
  
  static int ssh_session(void);
  static int ssh_session2(void);
  static void load_public_identity_files(void);
  
  /*
   * Main program for the ssh client.
   */
  int
  main(int ac, char **av)
  {
  	int i, opt, exit_status;
  	u_short fwd_port, fwd_host_port;
  	char sfwd_port[6], sfwd_host_port[6];
  	char *p, *cp, buf[256];
  	struct stat st;
  	struct passwd *pw;
  	int dummy;
  	extern int optind, optreset;
  	extern char *optarg;
  
  	__progname = ssh_get_progname(av[0]);
  	init_rng();
  
  	/*
  	 * 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;
  
  #ifdef HAVE_SETRLIMIT
  	/* 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));
  	}
  #endif
  	/* Get user data. */
  	pw = getpwuid(original_real_uid);
  	if (!pw) {
  		logit("You don't exist, go away!");
  		exit(1);
  	}
  	/* 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:L:NPR:TVX")) != -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 'g':
  			options.gateway_ports = 1;
  			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':
  			/* ignored for backward compatibility */
  			break;
  		case 'i':
  			if (stat(optarg, &st) < 0) {
  				fprintf(stderr, "Warning: Identity file %s "
  				    "does not exist.\n", optarg);
  				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, SSH protocols %d.%d/%d.%d, %s\n",
  			    SSH_VERSION,
  			    PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
  			    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
  			    SSLeay_version(SSLEAY_VERSION));
  			if (opt == 'V')
  				exit(0);
  			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(1);
  			}
  			break;
  		case 'c':
  			if (ciphers_valid(optarg)) {
  				/* SSH2 only */
  				options.ciphers = xstrdup(optarg);
  				options.cipher = SSH_CIPHER_ILLEGAL;
  			} else {
  				/* SSH1 only */
  				options.cipher = cipher_number(optarg);
  				if (options.cipher == -1) {
  					fprintf(stderr,
  					    "Unknown cipher type '%s'\n",
  					    optarg);
  					exit(1);
  				}
  				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(1);
  			}
  			break;
  		case 'p':
  			options.port = a2port(optarg);
  			if (options.port == 0) {
  				fprintf(stderr, "Bad port '%s'\n", optarg);
  				exit(1);
  			}
  			break;
  		case 'l':
  			options.user = optarg;
  			break;
  
  		case 'L':
  		case 'R':
  			if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
  			    sfwd_port, buf, sfwd_host_port) != 3 &&
  			    sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
  			    sfwd_port, buf, sfwd_host_port) != 3) {
  				fprintf(stderr,
  				    "Bad forwarding specification '%s'\n",
  				    optarg);
  				usage();
  				/* NOTREACHED */
  			}
  			if ((fwd_port = a2port(sfwd_port)) == 0 ||
  			    (fwd_host_port = a2port(sfwd_host_port)) == 0) {
  				fprintf(stderr,
  				    "Bad forwarding port(s) '%s'\n", optarg);
  				exit(1);
  			}
  			if (opt == 'L')
  				add_local_forward(&options, fwd_port, buf,
  				    fwd_host_port);
  			else if (opt == 'R')
  				add_remote_forward(&options, fwd_port, buf,
  				    fwd_host_port);
  			break;
  
  		case 'D':
  			fwd_port = a2port(optarg);
  			if (fwd_port == 0) {
  				fprintf(stderr, "Bad dynamic port '%s'\n",
  				    optarg);
  				exit(1);
  			}
  			add_local_forward(&options, fwd_port, "socks", 0);
  			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;
  			if (process_config_line(&options, host ? host : "",
  			    optarg, "command-line", 0, &dummy) != 0)
  				exit(1);
  			break;
  		case 's':
  			subsystem_flag = 1;
  			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)) && !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))
  			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);
  
  		/* Read systemwide configuration file after use config. */
  		(void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
  	}
  
  	/* 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);
  
  	seed_rng();
  
  	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 = tolower(*p);
  	}
  
  	if (options.proxy_command != NULL &&
  	    strcmp(options.proxy_command, "none") == 0)
  		options.proxy_command = NULL;
  
  	/* Open a connection to the remote host. */
  	if (ssh_connect(host, &hostaddr, options.port,
  	    options.address_family, options.connection_attempts,
  #ifdef HAVE_CYGWIN
  	    options.use_privileged_port,
  #else
  	    original_effective_uid == 0 && options.use_privileged_port,
  #endif
  	    options.proxy_command) != 0)
  		exit(1);
  
  	/*
  	 * 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 = xmalloc(sensitive_data.nkeys *
  		    sizeof(Key));
  
  		PRIV_START;
  		sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
  		    _PATH_HOST_KEY_FILE, "", NULL);
  		sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
  		    _PATH_HOST_DSA_KEY_FILE, "", NULL);
  		sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
  		    _PATH_HOST_RSA_KEY_FILE, "", 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.
  	 */
  	seteuid(original_real_uid);
  	setuid(original_real_uid);
  
  	/*
  	 * 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);
  
  	/* 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();
  
  	/*
  	 * 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
  x11_get_proto(char **_proto, char **_data)
  {
  	char line[512];
  	static char proto[512], data[512];
  	FILE *f;
  	int got_data = 0, i;
  	char *display;
  	struct stat st;
  
  	*_proto = proto;
  	*_data = data;
  	proto[0] = data[0] = '\0';
  	if (!options.xauth_location ||
  	    (stat(options.xauth_location, &st) == -1)) {
  		debug("No xauth program.");
  	} else {
  		if ((display = getenv("DISPLAY")) == NULL) {
  			debug("x11_get_proto: DISPLAY not set");
  			return;
  		}
  		/* Try to get Xauthority information for the display. */
  		if (strncmp(display, "localhost:", 10) == 0)
  			/*
  			 * Handle FamilyLocal case where $DISPLAY does
  			 * not match an authorization entry.  For this we
  			 * just try "xauth list unix:displaynum.screennum".
  			 * XXX: "localhost" match to determine FamilyLocal
  			 *      is not perfect.
  			 */
  			snprintf(line, sizeof line, "%s list unix:%s 2>"
  			    _PATH_DEVNULL, options.xauth_location, display+10);
  		else
  			snprintf(line, sizeof line, "%s list %.200s 2>"
  			    _PATH_DEVNULL, options.xauth_location, display);
  		debug2("x11_get_proto: %s", line);
  		f = popen(line, "r");
  		if (f && fgets(line, sizeof(line), f) &&
  		    sscanf(line, "%*s %511s %511s", proto, data) == 2)
  			got_data = 1;
  		if (f)
  			pclose(f);
  	}
  	/*
  	 * If we didn't get authentication data, just make up some
  	 * data.  The forwarding code will check the validity of the
  	 * response anyway, and substitute this data.  The X11
  	 * server, however, will ignore this fake data and use
  	 * whatever authentication mechanisms it was using otherwise
  	 * for the local connection.
  	 */
  	if (!got_data) {
  		u_int32_t rand = 0;
  
  		logit("Warning: No xauth data; using fake authentication data for X11 forwarding.");
  		strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);
  		for (i = 0; i < 16; i++) {
  			if (i % 4 == 0)
  				rand = arc4random();
  			snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);
  			rand >>= 8;
  		}
  	}
  }
  
  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("Connections to local port %d forwarded to remote address %.200s:%d",
  		    options.local_forwards[i].port,
  		    options.local_forwards[i].host,
  		    options.local_forwards[i].host_port);
  		success += channel_setup_local_fwd_listener(
  		    options.local_forwards[i].port,
  		    options.local_forwards[i].host,
  		    options.local_forwards[i].host_port,
  		    options.gateway_ports);
  	}
  	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("Connections to remote port %d forwarded to local address %.200s:%d",
  		    options.remote_forwards[i].port,
  		    options.remote_forwards[i].host,
  		    options.remote_forwards[i].host_port);
  		channel_request_remote_forwarding(
  		    options.remote_forwards[i].port,
  		    options.remote_forwards[i].host,
  		    options.remote_forwards[i].host_port);
  	}
  }
  
  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;
  
  	/* 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(ws.ws_row);
  		packet_put_int(ws.ws_col);
  		packet_put_int(ws.ws_xpixel);
  		packet_put_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. */
  	if (options.forward_x11 && getenv("DISPLAY") != NULL) {
  		char *proto, *data;
  		/* Get reasonable local authentication information. */
  		x11_get_proto(&proto, &data);
  		/* Request forwarding with authentication spoofing. */
  		debug("Requesting X11 forwarding with authentication spoofing.");
  		x11_request_forwarding_with_spoofing(0, 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();
  
  	/* 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);
  }
  
  static void
  client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
  {
  	int id, len;
  
  	id = packet_get_int();
  	len = buffer_len(&command);
  	if (len > 900)
  		len = 900;
  	packet_check_eom();
  	if (type == SSH2_MSG_CHANNEL_FAILURE)
  		fatal("Request for subsystem '%.*s' failed on channel %d",
  		    len, (u_char *)buffer_ptr(&command), id);
  }
  
  void
  client_global_request_reply(int type, u_int32_t seq, void *ctxt)
  {
  	int i;
  
  	i = client_global_request_id++;
  	if (i >= options.num_remote_forwards) {
  		debug("client_global_request_reply: too many replies %d > %d",
  		    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].port,
  	    options.remote_forwards[i].host,
  	    options.remote_forwards[i].host_port);
  	if (type == SSH2_MSG_REQUEST_FAILURE)
  		logit("Warning: remote port forwarding failed for listen port %d",
  		    options.remote_forwards[i].port);
  }
  
  /* request pty/x11/agent/tcpfwd/shell for channel */
  static void
  ssh_session2_setup(int id, void *arg)
  {
  	int len;
  	int interactive = 0;
  	struct termios tio;
  
  	debug2("ssh_session2_setup: id %d", id);
  
  	if (tty_flag) {
  		struct winsize ws;
  		char *cp;
  		cp = getenv("TERM");
  		if (!cp)
  			cp = "";
  		/* Store window size in the packet. */
  		if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
  			memset(&ws, 0, sizeof(ws));
  
  		channel_request_start(id, "pty-req", 0);
  		packet_put_cstring(cp);
  		packet_put_int(ws.ws_col);
  		packet_put_int(ws.ws_row);
  		packet_put_int(ws.ws_xpixel);
  		packet_put_int(ws.ws_ypixel);
  		tio = get_saved_tio();
  		tty_make_modes(/*ignored*/ 0, &tio);
  		packet_send();
  		interactive = 1;
  		/* XXX wait for reply */
  	}
  	if (options.forward_x11 &&
  	    getenv("DISPLAY") != NULL) {
  		char *proto, *data;
  		/* Get reasonable local authentication information. */
  		x11_get_proto(&proto, &data);
  		/* Request forwarding with authentication spoofing. */
  		debug("Requesting X11 forwarding with authentication spoofing.");
  		x11_request_forwarding_with_spoofing(id, 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();
  	}
  
  	len = buffer_len(&command);
  	if (len > 0) {
  		if (len > 900)
  			len = 900;
  		if (subsystem_flag) {
  			debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
  			channel_request_start(id, "subsystem", /*want reply*/ 1);
  			/* register callback for reply */
  			/* XXX we assume that client_loop has already been called */
  			dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
  			dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
  		} else {
  			debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
  			channel_request_start(id, "exec", 0);
  		}
  		packet_put_string(buffer_ptr(&command), buffer_len(&command));
  		packet_send();
  	} else {
  		channel_request_start(id, "shell", 0);
  		packet_send();
  	}
  
  	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_confirm(c->self, ssh_session2_setup);
  
  	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();
  
  	/* 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;
  	int i = 0;
  	Key *public;
  #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 */
  	for (; i < options.num_identity_files; i++) {
  		filename = tilde_expand_filename(options.identity_files[i],
  		    original_real_uid);
  		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;
  	}
  }
  