net: Allow binding of unspecified address without address existance

[dragonfly.git] / crypto / openssh / ssh.c

/* $OpenBSD: ssh.c,v 1.569 2021/09/20 04:02:13 dtucker 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 SSLeay 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"

#include <sys/types.h>
#ifdef HAVE_SYS_STAT_H
# include <sys/stat.h>
#endif
#include <sys/resource.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/wait.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <limits.h>
#include <locale.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#ifdef WITH_OPENSSL
#include <openssl/evp.h>
#include <openssl/err.h>
#endif
#include "openbsd-compat/openssl-compat.h"
#include "openbsd-compat/sys-queue.h"

#include "xmalloc.h"
#include "ssh.h"
#include "ssh2.h"
#include "canohost.h"
#include "compat.h"
#include "cipher.h"
#include "packet.h"
#include "sshbuf.h"
#include "channels.h"
#include "sshkey.h"
#include "authfd.h"
#include "authfile.h"
#include "pathnames.h"
#include "dispatch.h"
#include "clientloop.h"
#include "log.h"
#include "misc.h"
#include "readconf.h"
#include "sshconnect.h"
#include "kex.h"
#include "mac.h"
#include "sshpty.h"
#include "match.h"
#include "msg.h"
#include "version.h"
#include "ssherr.h"
#include "myproposal.h"
#include "utf8.h"

#ifdef ENABLE_PKCS11
#include "ssh-pkcs11.h"
#endif

extern char *__progname;

/* Saves a copy of argv for setproctitle emulation */
#ifndef HAVE_SETPROCTITLE
static char **saved_av;
#endif

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

/* Flag indicating whether a tty should be requested */
int tty_flag = 0;

/*
 * Flag indicating that the current process should be backgrounded and
 * a new mux-client launched in the foreground for ControlPersist.
 */
int need_controlpersist_detach = 0;

/* Copies of flags for ControlPersist foreground mux-client */
int ostdin_null_flag, osession_type, otty_flag, orequest_tty;

/*
 * 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;

/*
 * A config can specify a path to forward, overriding SSH_AUTH_SOCK. If this is
 * not NULL, forward the socket at this path instead.
 */
char *forward_agent_sock_path = NULL;

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

/* Private host keys. */
Sensitive sensitive_data;

/* command to be executed */
struct sshbuf *command;

/* # of replies received for global requests */
static int forward_confirms_pending = -1;

/* mux.c */
extern int muxserver_sock;
extern u_int muxclient_command;

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

static void
usage(void)
{
        fprintf(stderr,
"usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]\n"
"           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]\n"
"           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]\n"
"           [-i identity_file] [-J [user@]host[:port]] [-L address]\n"
"           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
"           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]\n"
"           [-w local_tun[:remote_tun]] destination [command [argument ...]]\n"
        );
        exit(255);
}

static int ssh_session2(struct ssh *, const struct ssh_conn_info *);
static void load_public_identity_files(const struct ssh_conn_info *);
static void main_sigchld_handler(int);

/* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
static void
tilde_expand_paths(char **paths, u_int num_paths)
{
        u_int i;
        char *cp;

        for (i = 0; i < num_paths; i++) {
                cp = tilde_expand_filename(paths[i], getuid());
                free(paths[i]);
                paths[i] = cp;
        }
}

/*
 * Expands the set of percent_expand options used by the majority of keywords
 * in the client that support percent expansion.
 * Caller must free returned string.
 */
static char *
default_client_percent_expand(const char *str,
    const struct ssh_conn_info *cinfo)
{
        return percent_expand(str,
            DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(cinfo),
            (char *)NULL);
}

/*
 * Expands the set of percent_expand options used by the majority of keywords
 * AND perform environment variable substitution.
 * Caller must free returned string.
 */
static char *
default_client_percent_dollar_expand(const char *str,
    const struct ssh_conn_info *cinfo)
{
        char *ret;

        ret = percent_dollar_expand(str,
            DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(cinfo),
            (char *)NULL);
        if (ret == NULL)
                fatal("invalid environment variable expansion");
        return ret;
}

/*
 * Attempt to resolve a host name / port to a set of addresses and
 * optionally return any CNAMEs encountered along the way.
 * Returns NULL on failure.
 * NB. this function must operate with a options having undefined members.
 */
static struct addrinfo *
resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
{
        char strport[NI_MAXSERV];
        struct addrinfo hints, *res;
        int gaierr;
        LogLevel loglevel = SYSLOG_LEVEL_DEBUG1;

        if (port <= 0)
                port = default_ssh_port();
        if (cname != NULL)
                *cname = '\0';
        debug3_f("lookup %s:%d", name, port);

        snprintf(strport, sizeof strport, "%d", port);
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = options.address_family == -1 ?
            AF_UNSPEC : options.address_family;
        hints.ai_socktype = SOCK_STREAM;
        if (cname != NULL)
                hints.ai_flags = AI_CANONNAME;
        if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
                if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
                        loglevel = SYSLOG_LEVEL_ERROR;
                do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
                    __progname, name, ssh_gai_strerror(gaierr));
                return NULL;
        }
        if (cname != NULL && res->ai_canonname != NULL) {
                if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
                        error_f("host \"%s\" cname \"%s\" too long (max %lu)",
                            name,  res->ai_canonname, (u_long)clen);
                        if (clen > 0)
                                *cname = '\0';
                }
        }
        return res;
}

/* Returns non-zero if name can only be an address and not a hostname */
static int
is_addr_fast(const char *name)
{
        return (strchr(name, '%') != NULL || strchr(name, ':') != NULL ||
            strspn(name, "0123456789.") == strlen(name));
}

/* Returns non-zero if name represents a valid, single address */
static int
is_addr(const char *name)
{
        char strport[NI_MAXSERV];
        struct addrinfo hints, *res;

        if (is_addr_fast(name))
                return 1;

        snprintf(strport, sizeof strport, "%u", default_ssh_port());
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = options.address_family == -1 ?
            AF_UNSPEC : options.address_family;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
        if (getaddrinfo(name, strport, &hints, &res) != 0)
                return 0;
        if (res == NULL || res->ai_next != NULL) {
                freeaddrinfo(res);
                return 0;
        }
        freeaddrinfo(res);
        return 1;
}

/*
 * Attempt to resolve a numeric host address / port to a single address.
 * Returns a canonical address string.
 * Returns NULL on failure.
 * NB. this function must operate with a options having undefined members.
 */
static struct addrinfo *
resolve_addr(const char *name, int port, char *caddr, size_t clen)
{
        char addr[NI_MAXHOST], strport[NI_MAXSERV];
        struct addrinfo hints, *res;
        int gaierr;

        if (port <= 0)
                port = default_ssh_port();
        snprintf(strport, sizeof strport, "%u", port);
        memset(&hints, 0, sizeof(hints));
        hints.ai_family = options.address_family == -1 ?
            AF_UNSPEC : options.address_family;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
        if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
                debug2_f("could not resolve name %.100s as address: %s",
                    name, ssh_gai_strerror(gaierr));
                return NULL;
        }
        if (res == NULL) {
                debug_f("getaddrinfo %.100s returned no addresses", name);
                return NULL;
        }
        if (res->ai_next != NULL) {
                debug_f("getaddrinfo %.100s returned multiple addresses", name);
                goto fail;
        }
        if ((gaierr = getnameinfo(res->ai_addr, res->ai_addrlen,
            addr, sizeof(addr), NULL, 0, NI_NUMERICHOST)) != 0) {
                debug_f("Could not format address for name %.100s: %s",
                    name, ssh_gai_strerror(gaierr));
                goto fail;
        }
        if (strlcpy(caddr, addr, clen) >= clen) {
                error_f("host \"%s\" addr \"%s\" too long (max %lu)",
                    name,  addr, (u_long)clen);
                if (clen > 0)
                        *caddr = '\0';
 fail:
                freeaddrinfo(res);
                return NULL;
        }
        return res;
}

/*
 * Check whether the cname is a permitted replacement for the hostname
 * and perform the replacement if it is.
 * NB. this function must operate with a options having undefined members.
 */
static int
check_follow_cname(int direct, char **namep, const char *cname)
{
        int i;
        struct allowed_cname *rule;

        if (*cname == '\0' || !config_has_permitted_cnames(&options) ||
            strcmp(*namep, cname) == 0)
                return 0;
        if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
                return 0;
        /*
         * Don't attempt to canonicalize names that will be interpreted by
         * a proxy or jump host unless the user specifically requests so.
         */
        if (!direct &&
            options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
                return 0;
        debug3_f("check \"%s\" CNAME \"%s\"", *namep, cname);
        for (i = 0; i < options.num_permitted_cnames; i++) {
                rule = options.permitted_cnames + i;
                if (match_pattern_list(*namep, rule->source_list, 1) != 1 ||
                    match_pattern_list(cname, rule->target_list, 1) != 1)
                        continue;
                verbose("Canonicalized DNS aliased hostname "
                    "\"%s\" => \"%s\"", *namep, cname);
                free(*namep);
                *namep = xstrdup(cname);
                return 1;
        }
        return 0;
}

/*
 * Attempt to resolve the supplied hostname after applying the user's
 * canonicalization rules. Returns the address list for the host or NULL
 * if no name was found after canonicalization.
 * NB. this function must operate with a options having undefined members.
 */
static struct addrinfo *
resolve_canonicalize(char **hostp, int port)
{
        int i, direct, ndots;
        char *cp, *fullhost, newname[NI_MAXHOST];
        struct addrinfo *addrs;

        /*
         * Attempt to canonicalise addresses, regardless of
         * whether hostname canonicalisation was requested
         */
        if ((addrs = resolve_addr(*hostp, port,
            newname, sizeof(newname))) != NULL) {
                debug2_f("hostname %.100s is address", *hostp);
                if (strcasecmp(*hostp, newname) != 0) {
                        debug2_f("canonicalised address \"%s\" => \"%s\"",
                            *hostp, newname);
                        free(*hostp);
                        *hostp = xstrdup(newname);
                }
                return addrs;
        }

        /*
         * If this looks like an address but didn't parse as one, it might
         * be an address with an invalid interface scope. Skip further
         * attempts at canonicalisation.
         */
        if (is_addr_fast(*hostp)) {
                debug_f("hostname %.100s is an unrecognised address", *hostp);
                return NULL;
        }

        if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
                return NULL;

        /*
         * Don't attempt to canonicalize names that will be interpreted by
         * a proxy unless the user specifically requests so.
         */
        direct = option_clear_or_none(options.proxy_command) &&
            options.jump_host == NULL;
        if (!direct &&
            options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
                return NULL;

        /* If domain name is anchored, then resolve it now */
        if ((*hostp)[strlen(*hostp) - 1] == '.') {
                debug3_f("name is fully qualified");
                fullhost = xstrdup(*hostp);
                if ((addrs = resolve_host(fullhost, port, 0,
                    newname, sizeof(newname))) != NULL)
                        goto found;
                free(fullhost);
                goto notfound;
        }

        /* Don't apply canonicalization to sufficiently-qualified hostnames */
        ndots = 0;
        for (cp = *hostp; *cp != '\0'; cp++) {
                if (*cp == '.')
                        ndots++;
        }
        if (ndots > options.canonicalize_max_dots) {
                debug3_f("not canonicalizing hostname \"%s\" (max dots %d)",
                    *hostp, options.canonicalize_max_dots);
                return NULL;
        }
        /* Attempt each supplied suffix */
        for (i = 0; i < options.num_canonical_domains; i++) {
                if (strcasecmp(options.canonical_domains[i], "none") == 0)
                        break;
                xasprintf(&fullhost, "%s.%s.", *hostp,
                    options.canonical_domains[i]);
                debug3_f("attempting \"%s\" => \"%s\"", *hostp, fullhost);
                if ((addrs = resolve_host(fullhost, port, 0,
                    newname, sizeof(newname))) == NULL) {
                        free(fullhost);
                        continue;
                }
 found:
                /* Remove trailing '.' */
                fullhost[strlen(fullhost) - 1] = '\0';
                /* Follow CNAME if requested */
                if (!check_follow_cname(direct, &fullhost, newname)) {
                        debug("Canonicalized hostname \"%s\" => \"%s\"",
                            *hostp, fullhost);
                }
                free(*hostp);
                *hostp = fullhost;
                return addrs;
        }
 notfound:
        if (!options.canonicalize_fallback_local)
                fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
        debug2_f("host %s not found in any suffix", *hostp);
        return NULL;
}

/*
 * Check the result of hostkey loading, ignoring some errors and
 * fatal()ing for others.
 */
static void
check_load(int r, const char *path, const char *message)
{
        switch (r) {
        case 0:
                break;
        case SSH_ERR_INTERNAL_ERROR:
        case SSH_ERR_ALLOC_FAIL:
                fatal_r(r, "load %s \"%s\"", message, path);
        case SSH_ERR_SYSTEM_ERROR:
                /* Ignore missing files */
                if (errno == ENOENT)
                        break;
                /* FALLTHROUGH */
        default:
                error_r(r, "load %s \"%s\"", message, path);
                break;
        }
}

/*
 * Read per-user configuration file.  Ignore the system wide config
 * file if the user specifies a config file on the command line.
 */
static void
process_config_files(const char *host_name, struct passwd *pw, int final_pass,
    int *want_final_pass)
{
        char buf[PATH_MAX];
        int r;

        if (config != NULL) {
                if (strcasecmp(config, "none") != 0 &&
                    !read_config_file(config, pw, host, host_name, &options,
                    SSHCONF_USERCONF | (final_pass ? SSHCONF_FINAL : 0),
                    want_final_pass))
                        fatal("Can't open user config file %.100s: "
                            "%.100s", config, strerror(errno));
        } else {
                r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
                    _PATH_SSH_USER_CONFFILE);
                if (r > 0 && (size_t)r < sizeof(buf))
                        (void)read_config_file(buf, pw, host, host_name,
                            &options, SSHCONF_CHECKPERM | SSHCONF_USERCONF |
                            (final_pass ? SSHCONF_FINAL : 0), want_final_pass);

                /* Read systemwide configuration file after user config. */
                (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw,
                    host, host_name, &options,
                    final_pass ? SSHCONF_FINAL : 0, want_final_pass);
        }
}

/* Rewrite the port number in an addrinfo list of addresses */
static void
set_addrinfo_port(struct addrinfo *addrs, int port)
{
        struct addrinfo *addr;

        for (addr = addrs; addr != NULL; addr = addr->ai_next) {
                switch (addr->ai_family) {
                case AF_INET:
                        ((struct sockaddr_in *)addr->ai_addr)->
                            sin_port = htons(port);
                        break;
                case AF_INET6:
                        ((struct sockaddr_in6 *)addr->ai_addr)->
                            sin6_port = htons(port);
                        break;
                }
        }
}

static void
ssh_conn_info_free(struct ssh_conn_info *cinfo)
{
        if (cinfo == NULL)
                return;
        free(cinfo->conn_hash_hex);
        free(cinfo->shorthost);
        free(cinfo->uidstr);
        free(cinfo->keyalias);
        free(cinfo->thishost);
        free(cinfo->host_arg);
        free(cinfo->portstr);
        free(cinfo->remhost);
        free(cinfo->remuser);
        free(cinfo->homedir);
        free(cinfo->locuser);
        free(cinfo);
}

/*
 * Main program for the ssh client.
 */
int
main(int ac, char **av)
{
        struct ssh *ssh = NULL;
        int i, r, opt, exit_status, use_syslog, direct, timeout_ms;
        int was_addr, config_test = 0, opt_terminated = 0, want_final_pass = 0;
        char *p, *cp, *line, *argv0, *logfile, *host_arg;
        char cname[NI_MAXHOST], thishost[NI_MAXHOST];
        struct stat st;
        struct passwd *pw;
        extern int optind, optreset;
        extern char *optarg;
        struct Forward fwd;
        struct addrinfo *addrs = NULL;
        size_t n, len;
        u_int j;
        struct ssh_conn_info *cinfo = NULL;

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

        /*
         * Discard other fds that are hanging around. These can cause problem
         * with backgrounded ssh processes started by ControlPersist.
         */
        closefrom(STDERR_FILENO + 1);

        __progname = ssh_get_progname(av[0]);

#ifndef HAVE_SETPROCTITLE
        /* Prepare for later setproctitle emulation */
        /* Save argv so it isn't clobbered by setproctitle() emulation */
        saved_av = xcalloc(ac + 1, sizeof(*saved_av));
        for (i = 0; i < ac; i++)
                saved_av[i] = xstrdup(av[i]);
        saved_av[i] = NULL;
        compat_init_setproctitle(ac, av);
        av = saved_av;
#endif

        seed_rng();

        /* Get user data. */
        pw = getpwuid(getuid());
        if (!pw) {
                logit("No user exists for uid %lu", (u_long)getuid());
                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);

        msetlocale();

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

        /*
         * Prepare main ssh transport/connection structures
         */
        if ((ssh = ssh_alloc_session_state()) == NULL)
                fatal("Couldn't allocate session state");
        channel_init_channels(ssh);

        /* Parse command-line arguments. */
        host = NULL;
        use_syslog = 0;
        logfile = NULL;
        argv0 = av[0];

 again:
        while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
            "AB:CD:E:F:GI:J:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
                switch (opt) {
                case '1':
                        fatal("SSH protocol v.1 is no longer supported");
                        break;
                case '2':
                        /* Ignored */
                        break;
                case '4':
                        options.address_family = AF_INET;
                        break;
                case '6':
                        options.address_family = AF_INET6;
                        break;
                case 'n':
                        options.stdin_null = 1;
                        break;
                case 'f':
                        options.fork_after_authentication = 1;
                        options.stdin_null = 1;
                        break;
                case 'x':
                        options.forward_x11 = 0;
                        break;
                case 'X':
                        options.forward_x11 = 1;
                        break;
                case 'y':
                        use_syslog = 1;
                        break;
                case 'E':
                        logfile = optarg;
                        break;
                case 'G':
                        config_test = 1;
                        break;
                case 'Y':
                        options.forward_x11 = 1;
                        options.forward_x11_trusted = 1;
                        break;
                case 'g':
                        options.fwd_opts.gateway_ports = 1;
                        break;
                case 'O':
                        if (options.stdio_forward_host != NULL)
                                fatal("Cannot specify multiplexing "
                                    "command with -W");
                        else if (muxclient_command != 0)
                                fatal("Multiplexing command already specified");
                        if (strcmp(optarg, "check") == 0)
                                muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
                        else if (strcmp(optarg, "forward") == 0)
                                muxclient_command = SSHMUX_COMMAND_FORWARD;
                        else if (strcmp(optarg, "exit") == 0)
                                muxclient_command = SSHMUX_COMMAND_TERMINATE;
                        else if (strcmp(optarg, "stop") == 0)
                                muxclient_command = SSHMUX_COMMAND_STOP;
                        else if (strcmp(optarg, "cancel") == 0)
                                muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
                        else if (strcmp(optarg, "proxy") == 0)
                                muxclient_command = SSHMUX_COMMAND_PROXY;
                        else
                                fatal("Invalid multiplex command.");
                        break;
                case 'P':       /* deprecated */
                        break;
                case 'Q':
                        cp = NULL;
                        if (strcmp(optarg, "cipher") == 0 ||
                            strcasecmp(optarg, "Ciphers") == 0)
                                cp = cipher_alg_list('\n', 0);
                        else if (strcmp(optarg, "cipher-auth") == 0)
                                cp = cipher_alg_list('\n', 1);
                        else if (strcmp(optarg, "mac") == 0 ||
                            strcasecmp(optarg, "MACs") == 0)
                                cp = mac_alg_list('\n');
                        else if (strcmp(optarg, "kex") == 0 ||
                            strcasecmp(optarg, "KexAlgorithms") == 0)
                                cp = kex_alg_list('\n');
                        else if (strcmp(optarg, "key") == 0)
                                cp = sshkey_alg_list(0, 0, 0, '\n');
                        else if (strcmp(optarg, "key-cert") == 0)
                                cp = sshkey_alg_list(1, 0, 0, '\n');
                        else if (strcmp(optarg, "key-plain") == 0)
                                cp = sshkey_alg_list(0, 1, 0, '\n');
                        else if (strcmp(optarg, "key-sig") == 0 ||
                            strcasecmp(optarg, "PubkeyAcceptedKeyTypes") == 0 || /* deprecated name */
                            strcasecmp(optarg, "PubkeyAcceptedAlgorithms") == 0 ||
                            strcasecmp(optarg, "HostKeyAlgorithms") == 0 ||
                            strcasecmp(optarg, "HostbasedKeyTypes") == 0 || /* deprecated name */
                            strcasecmp(optarg, "HostbasedAcceptedKeyTypes") == 0 || /* deprecated name */
                            strcasecmp(optarg, "HostbasedAcceptedAlgorithms") == 0)
                                cp = sshkey_alg_list(0, 0, 1, '\n');
                        else if (strcmp(optarg, "sig") == 0)
                                cp = sshkey_alg_list(0, 1, 1, '\n');
                        else if (strcmp(optarg, "protocol-version") == 0)
                                cp = xstrdup("2");
                        else if (strcmp(optarg, "compression") == 0) {
                                cp = xstrdup(compression_alg_list(0));
                                len = strlen(cp);
                                for (n = 0; n < len; n++)
                                        if (cp[n] == ',')
                                                cp[n] = '\n';
                        } else if (strcmp(optarg, "help") == 0) {
                                cp = xstrdup(
                                    "cipher\ncipher-auth\ncompression\nkex\n"
                                    "key\nkey-cert\nkey-plain\nkey-sig\nmac\n"
                                    "protocol-version\nsig");
                        }
                        if (cp == NULL)
                                fatal("Unsupported query \"%s\"", optarg);
                        printf("%s\n", cp);
                        free(cp);
                        exit(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':
                        p = tilde_expand_filename(optarg, getuid());
                        if (stat(p, &st) == -1)
                                fprintf(stderr, "Warning: Identity file %s "
                                    "not accessible: %s.\n", p,
                                    strerror(errno));
                        else
                                add_identity_file(&options, NULL, p, 1);
                        free(p);
                        break;
                case 'I':
#ifdef ENABLE_PKCS11
                        free(options.pkcs11_provider);
                        options.pkcs11_provider = xstrdup(optarg);
#else
                        fprintf(stderr, "no support for PKCS#11.\n");
#endif
                        break;
                case 'J':
                        if (options.jump_host != NULL) {
                                fatal("Only a single -J option is permitted "
                                    "(use commas to separate multiple "
                                    "jump hops)");
                        }
                        if (options.proxy_command != NULL)
                                fatal("Cannot specify -J with ProxyCommand");
                        if (parse_jump(optarg, &options, 1) == -1)
                                fatal("Invalid -J argument");
                        options.proxy_command = xstrdup("none");
                        break;
                case 't':
                        if (options.request_tty == REQUEST_TTY_YES)
                                options.request_tty = REQUEST_TTY_FORCE;
                        else
                                options.request_tty = REQUEST_TTY_YES;
                        break;
                case 'v':
                        if (debug_flag == 0) {
                                debug_flag = 1;
                                options.log_level = SYSLOG_LEVEL_DEBUG1;
                        } else {
                                if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
                                        debug_flag++;
                                        options.log_level++;
                                }
                        }
                        break;
                case 'V':
                        fprintf(stderr, "%s, %s\n",
                            SSH_RELEASE, SSH_OPENSSL_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 'W':
                        if (options.stdio_forward_host != NULL)
                                fatal("stdio forward already specified");
                        if (muxclient_command != 0)
                                fatal("Cannot specify stdio forward with -O");
                        if (parse_forward(&fwd, optarg, 1, 0)) {
                                options.stdio_forward_host = fwd.listen_host;
                                options.stdio_forward_port = fwd.listen_port;
                                free(fwd.connect_host);
                        } else {
                                fprintf(stderr,
                                    "Bad stdio forwarding specification '%s'\n",
                                    optarg);
                                exit(255);
                        }
                        options.request_tty = REQUEST_TTY_NO;
                        options.session_type = SESSION_TYPE_NONE;
                        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 == '+' || *optarg == '^' ?
                            optarg + 1 : optarg)) {
                                fprintf(stderr, "Unknown cipher type '%s'\n",
                                    optarg);
                                exit(255);
                        }
                        free(options.ciphers);
                        options.ciphers = xstrdup(optarg);
                        break;
                case 'm':
                        if (mac_valid(optarg)) {
                                free(options.macs);
                                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':
                        if (options.port == -1) {
                                options.port = a2port(optarg);
                                if (options.port <= 0) {
                                        fprintf(stderr, "Bad port '%s'\n",
                                            optarg);
                                        exit(255);
                                }
                        }
                        break;
                case 'l':
                        if (options.user == NULL)
                                options.user = optarg;
                        break;

                case 'L':
                        if (parse_forward(&fwd, optarg, 0, 0))
                                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, 0, 1) ||
                            parse_forward(&fwd, optarg, 1, 1)) {
                                add_remote_forward(&options, &fwd);
                        } else {
                                fprintf(stderr,
                                    "Bad remote forwarding specification "
                                    "'%s'\n", optarg);
                                exit(255);
                        }
                        break;

                case 'D':
                        if (parse_forward(&fwd, optarg, 1, 0)) {
                                add_local_forward(&options, &fwd);
                        } else {
                                fprintf(stderr,
                                    "Bad dynamic forwarding specification "
                                    "'%s'\n", optarg);
                                exit(255);
                        }
                        break;

                case 'C':
#ifdef WITH_ZLIB
                        options.compression = 1;
#else
                        error("Compression not supported, disabling.");
#endif
                        break;
                case 'N':
                        if (options.session_type != -1 &&
                            options.session_type != SESSION_TYPE_NONE)
                                fatal("Cannot specify -N with -s/SessionType");
                        options.session_type = SESSION_TYPE_NONE;
                        options.request_tty = REQUEST_TTY_NO;
                        break;
                case 'T':
                        options.request_tty = REQUEST_TTY_NO;
                        break;
                case 'o':
                        line = xstrdup(optarg);
                        if (process_config_line(&options, pw,
                            host ? host : "", host ? host : "", line,
                            "command-line", 0, NULL, SSHCONF_USERCONF) != 0)
                                exit(255);
                        free(line);
                        break;
                case 's':
                        if (options.session_type != -1 &&
                            options.session_type != SESSION_TYPE_SUBSYSTEM)
                                fatal("Cannot specify -s with -N/SessionType");
                        options.session_type = SESSION_TYPE_SUBSYSTEM;
                        break;
                case 'S':
                        free(options.control_path);
                        options.control_path = xstrdup(optarg);
                        break;
                case 'b':
                        options.bind_address = optarg;
                        break;
                case 'B':
                        options.bind_interface = optarg;
                        break;
                case 'F':
                        config = optarg;
                        break;
                default:
                        usage();
                }
        }

        if (optind > 1 && strcmp(av[optind - 1], "--") == 0)
                opt_terminated = 1;

        ac -= optind;
        av += optind;

        if (ac > 0 && !host) {
                int tport;
                char *tuser;
                switch (parse_ssh_uri(*av, &tuser, &host, &tport)) {
                case -1:
                        usage();
                        break;
                case 0:
                        if (options.user == NULL) {
                                options.user = tuser;
                                tuser = NULL;
                        }
                        free(tuser);
                        if (options.port == -1 && tport != -1)
                                options.port = tport;
                        break;
                default:
                        p = xstrdup(*av);
                        cp = strrchr(p, '@');
                        if (cp != NULL) {
                                if (cp == p)
                                        usage();
                                if (options.user == NULL) {
                                        options.user = p;
                                        p = NULL;
                                }
                                *cp++ = '\0';
                                host = xstrdup(cp);
                                free(p);
                        } else
                                host = p;
                        break;
                }
                if (ac > 1 && !opt_terminated) {
                        optind = optreset = 1;
                        goto again;
                }
                ac--, av++;
        }

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

        host_arg = xstrdup(host);

        /* Initialize the command to execute on remote host. */
        if ((command = sshbuf_new()) == NULL)
                fatal("sshbuf_new failed");

        /*
         * 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. */
                if (options.session_type == SESSION_TYPE_SUBSYSTEM) {
                        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 ((r = sshbuf_putf(command, "%s%s",
                            i ? " " : "", av[i])) != 0)
                                fatal_fr(r, "buffer error");
                }
        }

        /*
         * Initialize "log" output.  Since we are the client all output
         * goes to stderr unless otherwise specified by -y or -E.
         */
        if (use_syslog && logfile != NULL)
                fatal("Can't specify both -y and -E");
        if (logfile != NULL)
                log_redirect_stderr_to(logfile);
        log_init(argv0,
            options.log_level == SYSLOG_LEVEL_NOT_SET ?
            SYSLOG_LEVEL_INFO : options.log_level,
            options.log_facility == SYSLOG_FACILITY_NOT_SET ?
            SYSLOG_FACILITY_USER : options.log_facility,
            !use_syslog);

        if (debug_flag)
                logit("%s, %s", SSH_RELEASE, SSH_OPENSSL_VERSION);

        /* Parse the configuration files */
        process_config_files(host_arg, pw, 0, &want_final_pass);
        if (want_final_pass)
                debug("configuration requests final Match pass");

        /* Hostname canonicalisation needs a few options filled. */
        fill_default_options_for_canonicalization(&options);

        /* If the user has replaced the hostname then take it into use now */
        if (options.hostname != NULL) {
                /* NB. Please keep in sync with readconf.c:match_cfg_line() */
                cp = percent_expand(options.hostname,
                    "h", host, (char *)NULL);
                free(host);
                host = cp;
                free(options.hostname);
                options.hostname = xstrdup(host);
        }

        /* Don't lowercase addresses, they will be explicitly canonicalised */
        if ((was_addr = is_addr(host)) == 0)
                lowercase(host);

        /*
         * Try to canonicalize if requested by configuration or the
         * hostname is an address.
         */
        if (options.canonicalize_hostname != SSH_CANONICALISE_NO || was_addr)
                addrs = resolve_canonicalize(&host, options.port);

        /*
         * If CanonicalizePermittedCNAMEs have been specified but
         * other canonicalization did not happen (by not being requested
         * or by failing with fallback) then the hostname may still be changed
         * as a result of CNAME following.
         *
         * Try to resolve the bare hostname name using the system resolver's
         * usual search rules and then apply the CNAME follow rules.
         *
         * Skip the lookup if a ProxyCommand is being used unless the user
         * has specifically requested canonicalisation for this case via
         * CanonicalizeHostname=always
         */
        direct = option_clear_or_none(options.proxy_command) &&
            options.jump_host == NULL;
        if (addrs == NULL && config_has_permitted_cnames(&options) && (direct ||
            options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
                if ((addrs = resolve_host(host, options.port,
                    direct, cname, sizeof(cname))) == NULL) {
                        /* Don't fatal proxied host names not in the DNS */
                        if (direct)
                                cleanup_exit(255); /* logged in resolve_host */
                } else
                        check_follow_cname(direct, &host, cname);
        }

        /*
         * If canonicalisation is enabled then re-parse the configuration
         * files as new stanzas may match.
         */
        if (options.canonicalize_hostname != 0 && !want_final_pass) {
                debug("hostname canonicalisation enabled, "
                    "will re-parse configuration");
                want_final_pass = 1;
        }

        if (want_final_pass) {
                debug("re-parsing configuration");
                free(options.hostname);
                options.hostname = xstrdup(host);
                process_config_files(host_arg, pw, 1, NULL);
                /*
                 * Address resolution happens early with canonicalisation
                 * enabled and the port number may have changed since, so
                 * reset it in address list
                 */
                if (addrs != NULL && options.port > 0)
                        set_addrinfo_port(addrs, options.port);
        }

        /* Fill configuration defaults. */
        if (fill_default_options(&options) != 0)
                cleanup_exit(255);

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

        /*
         * If ProxyJump option specified, then construct a ProxyCommand now.
         */
        if (options.jump_host != NULL) {
                char port_s[8];
                const char *jumpuser = options.jump_user, *sshbin = argv0;
                int port = options.port, jumpport = options.jump_port;

                if (port <= 0)
                        port = default_ssh_port();
                if (jumpport <= 0)
                        jumpport = default_ssh_port();
                if (jumpuser == NULL)
                        jumpuser = options.user;
                if (strcmp(options.jump_host, host) == 0 && port == jumpport &&
                    strcmp(options.user, jumpuser) == 0)
                        fatal("jumphost loop via %s", options.jump_host);

                /*
                 * Try to use SSH indicated by argv[0], but fall back to
                 * "ssh" if it appears unavailable.
                 */
                if (strchr(argv0, '/') != NULL && access(argv0, X_OK) != 0)
                        sshbin = "ssh";

                /* Consistency check */
                if (options.proxy_command != NULL)
                        fatal("inconsistent options: ProxyCommand+ProxyJump");
                /* Never use FD passing for ProxyJump */
                options.proxy_use_fdpass = 0;
                snprintf(port_s, sizeof(port_s), "%d", options.jump_port);
                xasprintf(&options.proxy_command,
                    "%s%s%s%s%s%s%s%s%s%s%.*s -W '[%%h]:%%p' %s",
                    sshbin,
                    /* Optional "-l user" argument if jump_user set */
                    options.jump_user == NULL ? "" : " -l ",
                    options.jump_user == NULL ? "" : options.jump_user,
                    /* Optional "-p port" argument if jump_port set */
                    options.jump_port <= 0 ? "" : " -p ",
                    options.jump_port <= 0 ? "" : port_s,
                    /* Optional additional jump hosts ",..." */
                    options.jump_extra == NULL ? "" : " -J ",
                    options.jump_extra == NULL ? "" : options.jump_extra,
                    /* Optional "-F" argumment if -F specified */
                    config == NULL ? "" : " -F ",
                    config == NULL ? "" : config,
                    /* Optional "-v" arguments if -v set */
                    debug_flag ? " -" : "",
                    debug_flag, "vvv",
                    /* Mandatory hostname */
                    options.jump_host);
                debug("Setting implicit ProxyCommand from ProxyJump: %s",
                    options.proxy_command);
        }

        if (options.port == 0)
                options.port = default_ssh_port();
        channel_set_af(ssh, options.address_family);

        /* Tidy and check options */
        if (options.host_key_alias != NULL)
                lowercase(options.host_key_alias);
        if (options.proxy_command != NULL &&
            strcmp(options.proxy_command, "-") == 0 &&
            options.proxy_use_fdpass)
                fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
        if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
                if (options.control_persist && options.control_path != NULL) {
                        debug("UpdateHostKeys=ask is incompatible with "
                            "ControlPersist; disabling");
                        options.update_hostkeys = 0;
                } else if (sshbuf_len(command) != 0 ||
                    options.remote_command != NULL ||
                    options.request_tty == REQUEST_TTY_NO) {
                        debug("UpdateHostKeys=ask is incompatible with "
                            "remote command execution; disabling");
                        options.update_hostkeys = 0;
                } else if (options.log_level < SYSLOG_LEVEL_INFO) {
                        /* no point logging anything; user won't see it */
                        options.update_hostkeys = 0;
                }
        }
        if (options.connection_attempts <= 0)
                fatal("Invalid number of ConnectionAttempts");

        if (sshbuf_len(command) != 0 && options.remote_command != NULL)
                fatal("Cannot execute command-line and remote command.");

        /* Cannot fork to background if no command. */
        if (options.fork_after_authentication && sshbuf_len(command) == 0 &&
            options.remote_command == NULL &&
            options.session_type != SESSION_TYPE_NONE)
                fatal("Cannot fork into background without a command "
                    "to execute.");

        /* reinit */
        log_init(argv0, options.log_level, options.log_facility, !use_syslog);
        for (j = 0; j < options.num_log_verbose; j++) {
                if (strcasecmp(options.log_verbose[j], "none") == 0)
                        break;
                log_verbose_add(options.log_verbose[j]);
        }

        if (options.request_tty == REQUEST_TTY_YES ||
            options.request_tty == REQUEST_TTY_FORCE)
                tty_flag = 1;

        /* Allocate a tty by default if no command specified. */
        if (sshbuf_len(command) == 0 && options.remote_command == NULL)
                tty_flag = options.request_tty != REQUEST_TTY_NO;

        /* Force no tty */
        if (options.request_tty == REQUEST_TTY_NO ||
            (muxclient_command && muxclient_command != SSHMUX_COMMAND_PROXY))
                tty_flag = 0;
        /* Do not allocate a tty if stdin is not a tty. */
        if ((!isatty(fileno(stdin)) || options.stdin_null) &&
            options.request_tty != REQUEST_TTY_FORCE) {
                if (tty_flag)
                        logit("Pseudo-terminal will not be allocated because "
                            "stdin is not a terminal.");
                tty_flag = 0;
        }

        /* Set up strings used to percent_expand() arguments */
        cinfo = xcalloc(1, sizeof(*cinfo));
        if (gethostname(thishost, sizeof(thishost)) == -1)
                fatal("gethostname: %s", strerror(errno));
        cinfo->thishost = xstrdup(thishost);
        thishost[strcspn(thishost, ".")] = '\0';
        cinfo->shorthost = xstrdup(thishost);
        xasprintf(&cinfo->portstr, "%d", options.port);
        xasprintf(&cinfo->uidstr, "%llu",
            (unsigned long long)pw->pw_uid);
        cinfo->keyalias = xstrdup(options.host_key_alias ?
            options.host_key_alias : host_arg);
        cinfo->conn_hash_hex = ssh_connection_hash(cinfo->thishost, host,
            cinfo->portstr, options.user);
        cinfo->host_arg = xstrdup(host_arg);
        cinfo->remhost = xstrdup(host);
        cinfo->remuser = xstrdup(options.user);
        cinfo->homedir = xstrdup(pw->pw_dir);
        cinfo->locuser = xstrdup(pw->pw_name);

        /*
         * Expand tokens in arguments. NB. LocalCommand is expanded later,
         * after port-forwarding is set up, so it may pick up any local
         * tunnel interface name allocated.
         */
        if (options.remote_command != NULL) {
                debug3("expanding RemoteCommand: %s", options.remote_command);
                cp = options.remote_command;
                options.remote_command = default_client_percent_expand(cp,
                    cinfo);
                debug3("expanded RemoteCommand: %s", options.remote_command);
                free(cp);
                if ((r = sshbuf_put(command, options.remote_command,
                    strlen(options.remote_command))) != 0)
                        fatal_fr(r, "buffer error");
        }

        if (options.control_path != NULL) {
                cp = tilde_expand_filename(options.control_path, getuid());
                free(options.control_path);
                options.control_path = default_client_percent_dollar_expand(cp,
                    cinfo);
                free(cp);
        }

        if (options.identity_agent != NULL) {
                p = tilde_expand_filename(options.identity_agent, getuid());
                cp = default_client_percent_dollar_expand(p, cinfo);
                free(p);
                free(options.identity_agent);
                options.identity_agent = cp;
        }

        if (options.forward_agent_sock_path != NULL) {
                p = tilde_expand_filename(options.forward_agent_sock_path,
                    getuid());
                cp = default_client_percent_dollar_expand(p, cinfo);
                free(p);
                free(options.forward_agent_sock_path);
                options.forward_agent_sock_path = cp;
                if (stat(options.forward_agent_sock_path, &st) != 0) {
                        error("Cannot forward agent socket path \"%s\": %s",
                            options.forward_agent_sock_path, strerror(errno));
                        if (options.exit_on_forward_failure)
                                cleanup_exit(255);
                }
        }

        if (options.num_system_hostfiles > 0 &&
            strcasecmp(options.system_hostfiles[0], "none") == 0) {
                if (options.num_system_hostfiles > 1)
                        fatal("Invalid GlobalKnownHostsFiles: \"none\" "
                            "appears with other entries");
                free(options.system_hostfiles[0]);
                options.system_hostfiles[0] = NULL;
                options.num_system_hostfiles = 0;
        }

        if (options.num_user_hostfiles > 0 &&
            strcasecmp(options.user_hostfiles[0], "none") == 0) {
                if (options.num_user_hostfiles > 1)
                        fatal("Invalid UserKnownHostsFiles: \"none\" "
                            "appears with other entries");
                free(options.user_hostfiles[0]);
                options.user_hostfiles[0] = NULL;
                options.num_user_hostfiles = 0;
        }
        for (j = 0; j < options.num_user_hostfiles; j++) {
                if (options.user_hostfiles[j] == NULL)
                        continue;
                cp = tilde_expand_filename(options.user_hostfiles[j], getuid());
                p = default_client_percent_dollar_expand(cp, cinfo);
                if (strcmp(options.user_hostfiles[j], p) != 0)
                        debug3("expanded UserKnownHostsFile '%s' -> "
                            "'%s'", options.user_hostfiles[j], p);
                free(options.user_hostfiles[j]);
                free(cp);
                options.user_hostfiles[j] = p;
        }

        for (i = 0; i < options.num_local_forwards; i++) {
                if (options.local_forwards[i].listen_path != NULL) {
                        cp = options.local_forwards[i].listen_path;
                        p = options.local_forwards[i].listen_path =
                            default_client_percent_expand(cp, cinfo);
                        if (strcmp(cp, p) != 0)
                                debug3("expanded LocalForward listen path "
                                    "'%s' -> '%s'", cp, p);
                        free(cp);
                }
                if (options.local_forwards[i].connect_path != NULL) {
                        cp = options.local_forwards[i].connect_path;
                        p = options.local_forwards[i].connect_path =
                            default_client_percent_expand(cp, cinfo);
                        if (strcmp(cp, p) != 0)
                                debug3("expanded LocalForward connect path "
                                    "'%s' -> '%s'", cp, p);
                        free(cp);
                }
        }

        for (i = 0; i < options.num_remote_forwards; i++) {
                if (options.remote_forwards[i].listen_path != NULL) {
                        cp = options.remote_forwards[i].listen_path;
                        p = options.remote_forwards[i].listen_path =
                            default_client_percent_expand(cp, cinfo);
                        if (strcmp(cp, p) != 0)
                                debug3("expanded RemoteForward listen path "
                                    "'%s' -> '%s'", cp, p);
                        free(cp);
                }
                if (options.remote_forwards[i].connect_path != NULL) {
                        cp = options.remote_forwards[i].connect_path;
                        p = options.remote_forwards[i].connect_path =
                            default_client_percent_expand(cp, cinfo);
                        if (strcmp(cp, p) != 0)
                                debug3("expanded RemoteForward connect path "
                                    "'%s' -> '%s'", cp, p);
                        free(cp);
                }
        }

        if (config_test) {
                dump_client_config(&options, host);
                exit(0);
        }

        /* Expand SecurityKeyProvider if it refers to an environment variable */
        if (options.sk_provider != NULL && *options.sk_provider == '$' &&
            strlen(options.sk_provider) > 1) {
                if ((cp = getenv(options.sk_provider + 1)) == NULL) {
                        debug("Authenticator provider %s did not resolve; "
                            "disabling", options.sk_provider);
                        free(options.sk_provider);
                        options.sk_provider = NULL;
                } else {
                        debug2("resolved SecurityKeyProvider %s => %s",
                            options.sk_provider, cp);
                        free(options.sk_provider);
                        options.sk_provider = xstrdup(cp);
                }
        }

        if (muxclient_command != 0 && options.control_path == NULL)
                fatal("No ControlPath specified for \"-O\" command");
        if (options.control_path != NULL) {
                int sock;
                if ((sock = muxclient(options.control_path)) >= 0) {
                        ssh_packet_set_connection(ssh, sock, sock);
                        ssh_packet_set_mux(ssh);
                        goto skip_connect;
                }
        }

        /*
         * If hostname canonicalisation was not enabled, then we may not
         * have yet resolved the hostname. Do so now.
         */
        if (addrs == NULL && options.proxy_command == NULL) {
                debug2("resolving \"%s\" port %d", host, options.port);
                if ((addrs = resolve_host(host, options.port, 1,
                    cname, sizeof(cname))) == NULL)
                        cleanup_exit(255); /* resolve_host logs the error */
        }

        if (options.connection_timeout >= INT_MAX/1000)
                timeout_ms = INT_MAX;
        else
                timeout_ms = options.connection_timeout * 1000;

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

        if (addrs != NULL)
                freeaddrinfo(addrs);

        ssh_packet_set_timeout(ssh, options.server_alive_interval,
            options.server_alive_count_max);

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

        /*
         * If we successfully made the connection and we have hostbased auth
         * enabled, load the public keys so we can later use the ssh-keysign
         * helper to sign challenges.
         */
        sensitive_data.nkeys = 0;
        sensitive_data.keys = NULL;
        if (options.hostbased_authentication) {
                sensitive_data.nkeys = 10;
                sensitive_data.keys = xcalloc(sensitive_data.nkeys,
                    sizeof(struct sshkey));

                /* XXX check errors? */
#define L_PUBKEY(p,o) do { \
        if ((o) >= sensitive_data.nkeys) \
                fatal_f("pubkey out of array bounds"); \
        check_load(sshkey_load_public(p, &(sensitive_data.keys[o]), NULL), \
            p, "pubkey"); \
} while (0)
#define L_CERT(p,o) do { \
        if ((o) >= sensitive_data.nkeys) \
                fatal_f("cert out of array bounds"); \
        check_load(sshkey_load_cert(p, &(sensitive_data.keys[o])), p, "cert"); \
} while (0)

                if (options.hostbased_authentication == 1) {
                        L_CERT(_PATH_HOST_ECDSA_KEY_FILE, 0);
                        L_CERT(_PATH_HOST_ED25519_KEY_FILE, 1);
                        L_CERT(_PATH_HOST_RSA_KEY_FILE, 2);
                        L_CERT(_PATH_HOST_DSA_KEY_FILE, 3);
                        L_PUBKEY(_PATH_HOST_ECDSA_KEY_FILE, 4);
                        L_PUBKEY(_PATH_HOST_ED25519_KEY_FILE, 5);
                        L_PUBKEY(_PATH_HOST_RSA_KEY_FILE, 6);
                        L_PUBKEY(_PATH_HOST_DSA_KEY_FILE, 7);
                        L_CERT(_PATH_HOST_XMSS_KEY_FILE, 8);
                        L_PUBKEY(_PATH_HOST_XMSS_KEY_FILE, 9);
                }
        }

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

        /* optionally set the SSH_AUTHSOCKET_ENV_NAME variable */
        if (options.identity_agent &&
            strcmp(options.identity_agent, SSH_AUTHSOCKET_ENV_NAME) != 0) {
                if (strcmp(options.identity_agent, "none") == 0) {
                        unsetenv(SSH_AUTHSOCKET_ENV_NAME);
                } else {
                        cp = options.identity_agent;
                        /* legacy (limited) format */
                        if (cp[0] == '$' && cp[1] != '{') {
                                if (!valid_env_name(cp + 1)) {
                                        fatal("Invalid IdentityAgent "
                                            "environment variable name %s", cp);
                                }
                                if ((p = getenv(cp + 1)) == NULL)
                                        unsetenv(SSH_AUTHSOCKET_ENV_NAME);
                                else
                                        setenv(SSH_AUTHSOCKET_ENV_NAME, p, 1);
                        } else {
                                /* identity_agent specifies a path directly */
                                setenv(SSH_AUTHSOCKET_ENV_NAME, cp, 1);
                        }
                }
        }

        if (options.forward_agent && options.forward_agent_sock_path != NULL) {
                cp = options.forward_agent_sock_path;
                if (cp[0] == '$') {
                        if (!valid_env_name(cp + 1)) {
                                fatal("Invalid ForwardAgent environment variable name %s", cp);
                        }
                        if ((p = getenv(cp + 1)) != NULL)
                                forward_agent_sock_path = xstrdup(p);
                        else
                                options.forward_agent = 0;
                        free(cp);
                } else {
                        forward_agent_sock_path = cp;
                }
        }

        /* Expand ~ in known host file names. */
        tilde_expand_paths(options.system_hostfiles,
            options.num_system_hostfiles);
        tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);

        ssh_signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
        ssh_signal(SIGCHLD, main_sigchld_handler);

        /* Log into the remote system.  Never returns if the login fails. */
        ssh_login(ssh, &sensitive_data, host, (struct sockaddr *)&hostaddr,
            options.port, pw, timeout_ms, cinfo);

        /* 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);
                                sshkey_free(sensitive_data.keys[i]);
                                sensitive_data.keys[i] = NULL;
                        }
                }
                free(sensitive_data.keys);
        }
        for (i = 0; i < options.num_identity_files; i++) {
                free(options.identity_files[i]);
                options.identity_files[i] = NULL;
                if (options.identity_keys[i]) {
                        sshkey_free(options.identity_keys[i]);
                        options.identity_keys[i] = NULL;
                }
        }
        for (i = 0; i < options.num_certificate_files; i++) {
                free(options.certificate_files[i]);
                options.certificate_files[i] = NULL;
        }

#ifdef ENABLE_PKCS11
        (void)pkcs11_del_provider(options.pkcs11_provider);
#endif

 skip_connect:
        exit_status = ssh_session2(ssh, cinfo);
        ssh_conn_info_free(cinfo);
        ssh_packet_close(ssh);

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

        /* Kill ProxyCommand if it is running. */
        ssh_kill_proxy_command();

        return exit_status;
}

static void
control_persist_detach(void)
{
        pid_t pid;

        debug_f("backgrounding master process");

        /*
         * master (current process) into the background, and make the
         * foreground process a client of the backgrounded master.
         */
        switch ((pid = fork())) {
        case -1:
                fatal_f("fork: %s", strerror(errno));
        case 0:
                /* Child: master process continues mainloop */
                break;
        default:
                /* Parent: set up mux client to connect to backgrounded master */
                debug2_f("background process is %ld", (long)pid);
                options.stdin_null = ostdin_null_flag;
                options.request_tty = orequest_tty;
                tty_flag = otty_flag;
                options.session_type = osession_type;
                close(muxserver_sock);
                muxserver_sock = -1;
                options.control_master = SSHCTL_MASTER_NO;
                muxclient(options.control_path);
                /* muxclient() doesn't return on success. */
                fatal("Failed to connect to new control master");
        }
        if (stdfd_devnull(1, 1, !(log_is_on_stderr() && debug_flag)) == -1)
                error_f("stdfd_devnull failed");
        daemon(1, 1);
        setproctitle("%s [mux]", options.control_path);
}

/* Do fork() after authentication. Used by "ssh -f" */
static void
fork_postauth(void)
{
        if (need_controlpersist_detach)
                control_persist_detach();
        debug("forking to background");
        options.fork_after_authentication = 0;
        if (daemon(1, 1) == -1)
                fatal("daemon() failed: %.200s", strerror(errno));
        if (stdfd_devnull(1, 1, !(log_is_on_stderr() && debug_flag)) == -1)
                error_f("stdfd_devnull failed");
}

static void
forwarding_success(void)
{
        if (forward_confirms_pending == -1)
                return;
        if (--forward_confirms_pending == 0) {
                debug_f("all expected forwarding replies received");
                if (options.fork_after_authentication)
                        fork_postauth();
        } else {
                debug2_f("%d expected forwarding replies remaining",
                    forward_confirms_pending);
        }
}

/* Callback for remote forward global requests */
static void
ssh_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
{
        struct Forward *rfwd = (struct Forward *)ctxt;
        u_int port;
        int r;

        /* XXX verbose() on failure? */
        debug("remote forward %s for: listen %s%s%d, connect %s:%d",
            type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
            rfwd->listen_path ? rfwd->listen_path :
            rfwd->listen_host ? rfwd->listen_host : "",
            (rfwd->listen_path || rfwd->listen_host) ? ":" : "",
            rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
            rfwd->connect_host, rfwd->connect_port);
        if (rfwd->listen_path == NULL && rfwd->listen_port == 0) {
                if (type == SSH2_MSG_REQUEST_SUCCESS) {
                        if ((r = sshpkt_get_u32(ssh, &port)) != 0)
                                fatal_fr(r, "parse packet");
                        if (port > 65535) {
                                error("Invalid allocated port %u for remote "
                                    "forward to %s:%d", port,
                                    rfwd->connect_host, rfwd->connect_port);
                                /* Ensure failure processing runs below */
                                type = SSH2_MSG_REQUEST_FAILURE;
                                channel_update_permission(ssh,
                                    rfwd->handle, -1);
                        } else {
                                rfwd->allocated_port = (int)port;
                                logit("Allocated port %u for remote "
                                    "forward to %s:%d",
                                    rfwd->allocated_port, rfwd->connect_path ?
                                    rfwd->connect_path : rfwd->connect_host,
                                    rfwd->connect_port);
                                channel_update_permission(ssh,
                                    rfwd->handle, rfwd->allocated_port);
                        }
                } else {
                        channel_update_permission(ssh, rfwd->handle, -1);
                }
        }

        if (type == SSH2_MSG_REQUEST_FAILURE) {
                if (options.exit_on_forward_failure) {
                        if (rfwd->listen_path != NULL)
                                fatal("Error: remote port forwarding failed "
                                    "for listen path %s", rfwd->listen_path);
                        else
                                fatal("Error: remote port forwarding failed "
                                    "for listen port %d", rfwd->listen_port);
                } else {
                        if (rfwd->listen_path != NULL)
                                logit("Warning: remote port forwarding failed "
                                    "for listen path %s", rfwd->listen_path);
                        else
                                logit("Warning: remote port forwarding failed "
                                    "for listen port %d", rfwd->listen_port);
                }
        }
        forwarding_success();
}

static void
client_cleanup_stdio_fwd(struct ssh *ssh, int id, void *arg)
{
        debug("stdio forwarding: done");
        cleanup_exit(0);
}

static void
ssh_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
{
        if (!success)
                fatal("stdio forwarding failed");
}

static void
ssh_tun_confirm(struct ssh *ssh, int id, int success, void *arg)
{
        if (!success) {
                error("Tunnel forwarding failed");
                if (options.exit_on_forward_failure)
                        cleanup_exit(255);
        }

        debug_f("tunnel forward established, id=%d", id);
        forwarding_success();
}

static void
ssh_init_stdio_forwarding(struct ssh *ssh)
{
        Channel *c;
        int in, out;

        if (options.stdio_forward_host == NULL)
                return;

        debug3_f("%s:%d", options.stdio_forward_host,
            options.stdio_forward_port);

        if ((in = dup(STDIN_FILENO)) == -1 ||
            (out = dup(STDOUT_FILENO)) == -1)
                fatal_f("dup() in/out failed");
        if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
            options.stdio_forward_port, in, out,
            CHANNEL_NONBLOCK_STDIO)) == NULL)
                fatal_f("channel_connect_stdio_fwd failed");
        channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
        channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
}

static void
ssh_init_forward_permissions(struct ssh *ssh, const char *what, char **opens,
    u_int num_opens)
{
        u_int i;
        int port;
        char *addr, *arg, *oarg, ch;
        int where = FORWARD_LOCAL;

        channel_clear_permission(ssh, FORWARD_ADM, where);
        if (num_opens == 0)
                return; /* permit any */

        /* handle keywords: "any" / "none" */
        if (num_opens == 1 && strcmp(opens[0], "any") == 0)
                return;
        if (num_opens == 1 && strcmp(opens[0], "none") == 0) {
                channel_disable_admin(ssh, where);
                return;
        }
        /* Otherwise treat it as a list of permitted host:port */
        for (i = 0; i < num_opens; i++) {
                oarg = arg = xstrdup(opens[i]);
                ch = '\0';
                addr = hpdelim2(&arg, &ch);
                if (addr == NULL || ch == '/')
                        fatal_f("missing host in %s", what);
                addr = cleanhostname(addr);
                if (arg == NULL || ((port = permitopen_port(arg)) < 0))
                        fatal_f("bad port number in %s", what);
                /* Send it to channels layer */
                channel_add_permission(ssh, FORWARD_ADM,
                    where, addr, port);
                free(oarg);
        }
}

static void
ssh_init_forwarding(struct ssh *ssh, char **ifname)
{
        int success = 0;
        int i;

        ssh_init_forward_permissions(ssh, "permitremoteopen",
            options.permitted_remote_opens,
            options.num_permitted_remote_opens);

        if (options.exit_on_forward_failure)
                forward_confirms_pending = 0; /* track pending requests */
        /* 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_path != NULL) ?
                    options.local_forwards[i].listen_path :
                    (options.local_forwards[i].listen_host == NULL) ?
                    (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
                    options.local_forwards[i].listen_host,
                    options.local_forwards[i].listen_port,
                    (options.local_forwards[i].connect_path != NULL) ?
                    options.local_forwards[i].connect_path :
                    options.local_forwards[i].connect_host,
                    options.local_forwards[i].connect_port);
                success += channel_setup_local_fwd_listener(ssh,
                    &options.local_forwards[i], &options.fwd_opts);
        }
        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_path != NULL) ?
                    options.remote_forwards[i].listen_path :
                    (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_path != NULL) ?
                    options.remote_forwards[i].connect_path :
                    options.remote_forwards[i].connect_host,
                    options.remote_forwards[i].connect_port);
                if ((options.remote_forwards[i].handle =
                    channel_request_remote_forwarding(ssh,
                    &options.remote_forwards[i])) >= 0) {
                        client_register_global_confirm(
                            ssh_confirm_remote_forward,
                            &options.remote_forwards[i]);
                        forward_confirms_pending++;
                } else 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 ((*ifname = client_request_tun_fwd(ssh,
                    options.tun_open, options.tun_local,
                    options.tun_remote, ssh_tun_confirm, NULL)) != NULL)
                        forward_confirms_pending++;
                else if (options.exit_on_forward_failure)
                        fatal("Could not request tunnel forwarding.");
                else
                        error("Could not request tunnel forwarding.");
        }
        if (forward_confirms_pending > 0) {
                debug_f("expecting replies for %d forwards",
                    forward_confirms_pending);
        }
}

static void
check_agent_present(void)
{
        int r;

        if (options.forward_agent) {
                /* Clear agent forwarding if we don't have an agent. */
                if ((r = ssh_get_authentication_socket(NULL)) != 0) {
                        options.forward_agent = 0;
                        if (r != SSH_ERR_AGENT_NOT_PRESENT)
                                debug_r(r, "ssh_get_authentication_socket");
                }
        }
}

static void
ssh_session2_setup(struct ssh *ssh, int id, int success, void *arg)
{
        extern char **environ;
        const char *display, *term;
        int r, interactive = tty_flag;
        char *proto = NULL, *data = NULL;

        if (!success)
                return; /* No need for error message, channels code sens one */

        display = getenv("DISPLAY");
        if (display == NULL && options.forward_x11)
                debug("X11 forwarding requested but DISPLAY not set");
        if (options.forward_x11 && client_x11_get_proto(ssh, display,
            options.xauth_location, options.forward_x11_trusted,
            options.forward_x11_timeout, &proto, &data) == 0) {
                /* Request forwarding with authentication spoofing. */
                debug("Requesting X11 forwarding with authentication "
                    "spoofing.");
                x11_request_forwarding_with_spoofing(ssh, id, display, proto,
                    data, 1);
                client_expect_confirm(ssh, id, "X11 forwarding", CONFIRM_WARN);
                /* XXX exit_on_forward_failure */
                interactive = 1;
        }

        check_agent_present();
        if (options.forward_agent) {
                debug("Requesting authentication agent forwarding.");
                channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
                if ((r = sshpkt_send(ssh)) != 0)
                        fatal_fr(r, "send packet");
        }

        /* Tell the packet module whether this is an interactive session. */
        ssh_packet_set_interactive(ssh, interactive,
            options.ip_qos_interactive, options.ip_qos_bulk);

        if ((term = lookup_env_in_list("TERM", options.setenv,
            options.num_setenv)) == NULL || *term == '\0')
                term = getenv("TERM");
        client_session2_setup(ssh, id, tty_flag,
            options.session_type == SESSION_TYPE_SUBSYSTEM, term,
            NULL, fileno(stdin), command, environ);
}

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

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

        if (in == -1 || out == -1 || err == -1)
                fatal("dup() in/out/err failed");

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

        debug3_f("channel_new: %d", c->self);

        channel_send_open(ssh, c->self);
        if (options.session_type != SESSION_TYPE_NONE)
                channel_register_open_confirm(ssh, c->self,
                    ssh_session2_setup, NULL);

        return c->self;
}

static int
ssh_session2(struct ssh *ssh, const struct ssh_conn_info *cinfo)
{
        int r, id = -1;
        char *cp, *tun_fwd_ifname = NULL;

        /* XXX should be pre-session */
        if (!options.control_persist)
                ssh_init_stdio_forwarding(ssh);

        ssh_init_forwarding(ssh, &tun_fwd_ifname);

        if (options.local_command != NULL) {
                debug3("expanding LocalCommand: %s", options.local_command);
                cp = options.local_command;
                options.local_command = percent_expand(cp,
                    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(cinfo),
                    "T", tun_fwd_ifname == NULL ? "NONE" : tun_fwd_ifname,
                    (char *)NULL);
                debug3("expanded LocalCommand: %s", options.local_command);
                free(cp);
        }

        /* Start listening for multiplex clients */
        if (!ssh_packet_get_mux(ssh))
                muxserver_listen(ssh);

        /*
         * If we are in control persist mode and have a working mux listen
         * socket, then prepare to background ourselves and have a foreground
         * client attach as a control client.
         * NB. we must save copies of the flags that we override for
         * the backgrounding, since we defer attachment of the client until
         * after the connection is fully established (in particular,
         * async rfwd replies have been received for ExitOnForwardFailure).
         */
        if (options.control_persist && muxserver_sock != -1) {
                ostdin_null_flag = options.stdin_null;
                osession_type = options.session_type;
                orequest_tty = options.request_tty;
                otty_flag = tty_flag;
                options.stdin_null = 1;
                options.session_type = SESSION_TYPE_NONE;
                tty_flag = 0;
                if (!options.fork_after_authentication &&
                    (osession_type != SESSION_TYPE_NONE ||
                    options.stdio_forward_host != NULL))
                        need_controlpersist_detach = 1;
                options.fork_after_authentication = 1;
        }
        /*
         * ControlPersist mux listen socket setup failed, attempt the
         * stdio forward setup that we skipped earlier.
         */
        if (options.control_persist && muxserver_sock == -1)
                ssh_init_stdio_forwarding(ssh);

        if (options.session_type != SESSION_TYPE_NONE)
                id = ssh_session2_open(ssh);
        else {
                ssh_packet_set_interactive(ssh,
                    options.control_master == SSHCTL_MASTER_NO,
                    options.ip_qos_interactive, options.ip_qos_bulk);
        }

        /* If we don't expect to open a new session, then disallow it */
        if (options.control_master == SSHCTL_MASTER_NO &&
            (ssh->compat & SSH_NEW_OPENSSH)) {
                debug("Requesting no-more-sessions@openssh.com");
                if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
                    (r = sshpkt_put_cstring(ssh,
                    "no-more-sessions@openssh.com")) != 0 ||
                    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
                    (r = sshpkt_send(ssh)) != 0)
                        fatal_fr(r, "send packet");
        }

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

        /*
         * stdout is now owned by the session channel; clobber it here
         * so future channel closes are propagated to the local fd.
         * NB. this can only happen after LocalCommand has completed,
         * as it may want to write to stdout.
         */
        if (!need_controlpersist_detach && stdfd_devnull(0, 1, 0) == -1)
                error_f("stdfd_devnull failed");

        /*
         * If requested and we are not interested in replies to remote
         * forwarding requests, then let ssh continue in the background.
         */
        if (options.fork_after_authentication) {
                if (options.exit_on_forward_failure &&
                    options.num_remote_forwards > 0) {
                        debug("deferring postauth fork until remote forward "
                            "confirmation received");
                } else
                        fork_postauth();
        }

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

/* Loads all IdentityFile and CertificateFile keys */
static void
load_public_identity_files(const struct ssh_conn_info *cinfo)
{
        char *filename, *cp;
        struct sshkey *public;
        int i;
        u_int n_ids, n_certs;
        char *identity_files[SSH_MAX_IDENTITY_FILES];
        struct sshkey *identity_keys[SSH_MAX_IDENTITY_FILES];
        int identity_file_userprovided[SSH_MAX_IDENTITY_FILES];
        char *certificate_files[SSH_MAX_CERTIFICATE_FILES];
        struct sshkey *certificates[SSH_MAX_CERTIFICATE_FILES];
        int certificate_file_userprovided[SSH_MAX_CERTIFICATE_FILES];
#ifdef ENABLE_PKCS11
        struct sshkey **keys = NULL;
        char **comments = NULL;
        int nkeys;
#endif /* PKCS11 */

        n_ids = n_certs = 0;
        memset(identity_files, 0, sizeof(identity_files));
        memset(identity_keys, 0, sizeof(identity_keys));
        memset(identity_file_userprovided, 0,
            sizeof(identity_file_userprovided));
        memset(certificate_files, 0, sizeof(certificate_files));
        memset(certificates, 0, sizeof(certificates));
        memset(certificate_file_userprovided, 0,
            sizeof(certificate_file_userprovided));

#ifdef ENABLE_PKCS11
        if (options.pkcs11_provider != NULL &&
            options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
            (pkcs11_init(!options.batch_mode) == 0) &&
            (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
            &keys, &comments)) > 0) {
                for (i = 0; i < nkeys; i++) {
                        if (n_ids >= SSH_MAX_IDENTITY_FILES) {
                                sshkey_free(keys[i]);
                                free(comments[i]);
                                continue;
                        }
                        identity_keys[n_ids] = keys[i];
                        identity_files[n_ids] = comments[i]; /* transferred */
                        n_ids++;
                }
                free(keys);
                free(comments);
        }
#endif /* ENABLE_PKCS11 */
        for (i = 0; i < options.num_identity_files; i++) {
                if (n_ids >= SSH_MAX_IDENTITY_FILES ||
                    strcasecmp(options.identity_files[i], "none") == 0) {
                        free(options.identity_files[i]);
                        options.identity_files[i] = NULL;
                        continue;
                }
                cp = tilde_expand_filename(options.identity_files[i], getuid());
                filename = default_client_percent_dollar_expand(cp, cinfo);
                free(cp);
                check_load(sshkey_load_public(filename, &public, NULL),
                    filename, "pubkey");
                debug("identity file %s type %d", filename,
                    public ? public->type : -1);
                free(options.identity_files[i]);
                identity_files[n_ids] = filename;
                identity_keys[n_ids] = public;
                identity_file_userprovided[n_ids] =
                    options.identity_file_userprovided[i];
                if (++n_ids >= SSH_MAX_IDENTITY_FILES)
                        continue;

                /*
                 * If no certificates have been explicitly listed then try
                 * to add the default certificate variant too.
                 */
                if (options.num_certificate_files != 0)
                        continue;
                xasprintf(&cp, "%s-cert", filename);
                check_load(sshkey_load_public(cp, &public, NULL),
                    filename, "pubkey");
                debug("identity file %s type %d", cp,
                    public ? public->type : -1);
                if (public == NULL) {
                        free(cp);
                        continue;
                }
                if (!sshkey_is_cert(public)) {
                        debug_f("key %s type %s is not a certificate",
                            cp, sshkey_type(public));
                        sshkey_free(public);
                        free(cp);
                        continue;
                }
                /* NB. leave filename pointing to private key */
                identity_files[n_ids] = xstrdup(filename);
                identity_keys[n_ids] = public;
                identity_file_userprovided[n_ids] =
                    options.identity_file_userprovided[i];
                n_ids++;
        }

        if (options.num_certificate_files > SSH_MAX_CERTIFICATE_FILES)
                fatal_f("too many certificates");
        for (i = 0; i < options.num_certificate_files; i++) {
                cp = tilde_expand_filename(options.certificate_files[i],
                    getuid());
                filename = default_client_percent_dollar_expand(cp, cinfo);
                free(cp);

                check_load(sshkey_load_public(filename, &public, NULL),
                    filename, "certificate");
                debug("certificate file %s type %d", filename,
                    public ? public->type : -1);
                free(options.certificate_files[i]);
                options.certificate_files[i] = NULL;
                if (public == NULL) {
                        free(filename);
                        continue;
                }
                if (!sshkey_is_cert(public)) {
                        debug_f("key %s type %s is not a certificate",
                            filename, sshkey_type(public));
                        sshkey_free(public);
                        free(filename);
                        continue;
                }
                certificate_files[n_certs] = filename;
                certificates[n_certs] = public;
                certificate_file_userprovided[n_certs] =
                    options.certificate_file_userprovided[i];
                ++n_certs;
        }

        options.num_identity_files = n_ids;
        memcpy(options.identity_files, identity_files, sizeof(identity_files));
        memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
        memcpy(options.identity_file_userprovided,
            identity_file_userprovided, sizeof(identity_file_userprovided));

        options.num_certificate_files = n_certs;
        memcpy(options.certificate_files,
            certificate_files, sizeof(certificate_files));
        memcpy(options.certificates, certificates, sizeof(certificates));
        memcpy(options.certificate_file_userprovided,
            certificate_file_userprovided,
            sizeof(certificate_file_userprovided));
}

static void
main_sigchld_handler(int sig)
{
        int save_errno = errno;
        pid_t pid;
        int status;

        while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
            (pid == -1 && errno == EINTR))
                ;
        errno = save_errno;
}