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Revision 1.559, Tue Jun 8 07:07:15 2021 UTC (2 years, 11 months ago) by djm
Branch: MAIN
Changes since 1.558: +7 -2 lines

Switch ssh_config parsing to use argv_split()

This fixes a couple of problems with the previous tokeniser,
strdelim()

1. strdelim() is permissive wrt accepting '=' characters. This is
   intended to allow it to tokenise "Option=value" but because it
   cannot keep state, it will incorrectly split "Opt=val=val2".
2. strdelim() has rudimentry handling of quoted strings, but it
   is incomplete and inconsistent. E.g. it doesn't handle escaped
   quotes inside a quoted string.
3. It has no support for stopping on a (unquoted) comment. Because
   of this readconf.c r1.343 added chopping of lines at '#', but
   this caused a regression because these characters may legitimately
   appear inside quoted strings.

The new tokeniser is stricter is a number of cases, including #1 above
but previously it was also possible for some directives to appear
without arguments. AFAIK these were nonsensical in all cases, and the
new tokeniser refuses to accept them.

The new code handles quotes much better, permitting quoted space as
well as escaped closing quotes. Finally, comment handling should be
fixed - the tokeniser will terminate only on unquoted # characters.

feedback & ok markus@

tested in snaps for the last five or so days - thanks Theo and those who
caught bugs

/* $OpenBSD: ssh.c,v 1.559 2021/06/08 07:07:15 djm Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Ssh client program.  This program can be used to log into a remote machine.
 * The software supports strong authentication, encryption, and forwarding
 * of X11, TCP/IP, and authentication connections.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 *
 * Copyright (c) 1999 Niels Provos.  All rights reserved.
 * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
 *
 * Modified to work with 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 <sys/types.h>
#include <sys/ioctl.h>
#include <sys/queue.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>

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

#ifdef WITH_OPENSSL
#include <openssl/evp.h>
#include <openssl/err.h>
#endif

#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"

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

extern char *__progname;

/* 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;

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

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

/*
 * Flag indicating that 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, ono_shell_flag, otty_flag, orequest_tty;

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

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

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

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

/*
 * 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;

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

/* # 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]\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';

	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' || options.num_permitted_cnames == 0 ||
	    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);

	if (getuid() != geteuid())
		fatal("ssh setuid not supported.");
	if (getgid() != getegid())
		fatal("ssh setgid not supported.");

	/* 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);

	setlocale(LC_CTYPE, "");

	/*
	 * 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':
			stdin_null_flag = 1;
			break;
		case 'f':
			fork_after_authentication_flag = 1;
			stdin_null_flag = 1;
			break;
		case 'x':
			options.forward_x11 = 0;
			break;
		case 'X':
			options.forward_x11 = 1;
			break;
		case 'y':
			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_VERSION, 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;
			no_shell_flag = 1;
			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':
			no_shell_flag = 1;
			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':
			subsystem_flag = 1;
			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);

#ifdef WITH_OPENSSL
	OpenSSL_add_all_algorithms();
	ERR_load_crypto_strings();
#endif

	/* 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 (subsystem_flag) {
			fprintf(stderr,
			    "You must specify a subsystem to invoke.\n");
			usage();
		}
	} else {
		/* A command has been specified.  Store it into the buffer. */
		for (i = 0; i < ac; i++) {
			if ((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_VERSION, 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 && options.num_permitted_cnames != 0 && (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 (fork_after_authentication_flag && sshbuf_len(command) == 0 &&
	    options.remote_command == NULL && !no_shell_flag)
		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)) || stdin_null_flag) &&
	    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 = 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);

	if (ssh_packet_connection_is_on_socket(ssh)) {
		verbose("Authenticated to %s ([%s]:%d).", host,
		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
	} else {
		verbose("Authenticated to %s (via proxy).", host);
	}

	/* 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);
		stdin_null_flag = ostdin_null_flag;
		options.request_tty = orequest_tty;
		tty_flag = otty_flag;
		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");
	fork_after_authentication_flag = 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 (fork_after_authentication_flag)
			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_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, subsystem_flag, 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 (stdin_null_flag) {
		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 (!no_shell_flag)
		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 = stdin_null_flag;
		ono_shell_flag = no_shell_flag;
		orequest_tty = options.request_tty;
		otty_flag = tty_flag;
		stdin_null_flag = 1;
		no_shell_flag = 1;
		tty_flag = 0;
		if (!fork_after_authentication_flag &&
		    (!ono_shell_flag || options.stdio_forward_host != NULL))
			need_controlpersist_detach = 1;
		fork_after_authentication_flag = 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 (!no_shell_flag)
		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 (fork_after_authentication_flag) {
		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;
}