oops, that last commit was:

[openssh-git.git] / ssh.c

/*
 * 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 "includes.h"
RCSID("$OpenBSD: ssh.c,v 1.249 2005/07/30 01:26:16 djm 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 "bufaux.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"

#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 [-1246AaCfgkMNnqsTtVvXxY] [-b bind_address] [-c cipher_spec]\n"
"           [-D 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"
"           [user@]hostname [command]\n"
        );
        exit(1);
}

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;
        extern int optind, optreset;
        extern char *optarg;
        struct servent *sp;
        Forward fwd;

        __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:MNO:PR:S:TVXY")) != -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 '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_RELEASE, 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_INVALID;
                        } 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 '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(1);
                        }
                        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(1);
                        }
                        break;

                case 'R':
                        if (parse_forward(&fwd, optarg)) {
                                add_remote_forward(&options, &fwd);
                        } else {
                                fprintf(stderr,
                                    "Bad remote forwarding specification "
                                    "'%s'\n", optarg);
                                exit(1);
                        }
                        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(1);
                        }
                        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(1);
                        }
                        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(1);
                        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);

        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);
        }

        /* 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)
                options.proxy_command = NULL;
        if (options.control_path != NULL &&
            strcmp(options.control_path, "none") == 0)
                options.control_path = NULL;

        if (options.control_path != NULL) {
                snprintf(buf, sizeof(buf), "%d", options.port);
                cp = tilde_expand_filename(options.control_path,
                    original_real_uid);
                options.control_path = percent_expand(cp, "p", buf, "h", host,
                    "r", options.user, (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);

        /* 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.
         */
        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);

        /* 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 == 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) ?
                    (options.gateway_ports ? "*" : "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);
                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);
        }
}

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(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. */
        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();

        /* 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
ssh_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_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)
                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;
        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 ((control_fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
                fatal("%s socket(): %s\n", __func__, strerror(errno));

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

        if (listen(control_fd, 64) == -1)
                fatal("%s listen(): %s\n", __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, &ssh_subsystem_reply);

        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, NULL);

        return c->self;
}

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

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

        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;
        }
}

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

static void
control_client_sigrelay(int signo)
{
        if (control_server_pid > 1)
                kill(control_server_pid, signo);
}

static int
env_permitted(char *env)
{
        int i;
        char name[1024], *cp;

        strlcpy(name, env, sizeof(name));
        if ((cp = strchr(name, '=')) == NULL)
                return (0);

        *cp = '\0';

        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, num_env, addr_len;
        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_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 (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;

        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__);

        mm_send_fd(sock, STDIN_FILENO);
        mm_send_fd(sock, STDOUT_FILENO);
        mm_send_fd(sock, STDERR_FILENO);

        /* 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 */
        exitval = 0;
        for (;!control_client_terminate;) {
                r = read(sock, &exitval, sizeof(exitval));
                if (r == 0) {
                        debug2("Received EOF from master");
                        break;
                }
                if (r > 0)
                        debug2("Received exit status from master %d", exitval);
                if (r == -1 && errno != EINTR)
                        fatal("%s: read %s", __func__, strerror(errno));
        }

        if (control_client_terminate)
                debug2("Exiting on signal %d", control_client_terminate);

        close(sock);

        leave_raw_mode();

        if (tty_flag && options.log_level != SYSLOG_LEVEL_QUIET)
                fprintf(stderr, "Connection to master closed.\r\n");

        exit(exitval);
}