/*

* Author: Tatu Ylonen <ylo@cs.hut.fi>

* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland

* All rights reserved

* Ssh client program. This program can be used to log into a remote machine.

* The software supports strong authentication, encryption, and forwarding

* of X11, TCP/IP, and authentication connections.

*

* As far as I am concerned, the code I have written for this software

* can be used freely for any purpose. Any derived versions of this

* software must be clearly marked as such, and if the derived work is

* incompatible with the protocol description in the RFC file, it must be

* called by a name other than "ssh" or "Secure Shell".

*

* Copyright (c) 1999 Niels Provos. All rights reserved.

* Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.

*

* Modified to work with SSL by Niels Provos <provos@citi.umich.edu>

* in Canada (German citizen).

*

* Redistribution and use in source and binary forms, with or without

* modification, are permitted provided that the following conditions

* are met:

* 1. Redistributions of source code must retain the above copyright

* notice, this list of conditions and the following disclaimer.

* 2. Redistributions in binary form must reproduce the above copyright

* notice, this list of conditions and the following disclaimer in the

* documentation and/or other materials provided with the distribution.

*

* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

#include "includes.h"

RCSID("$OpenBSD: ssh.c,v 1.190 2003/02/06 09:27:29 markus Exp $");

#include <openssl/evp.h>

#include <openssl/err.h>

#include "ssh.h"

#include "ssh1.h"

#include "ssh2.h"

#include "compat.h"

#include "cipher.h"

#include "xmalloc.h"

#include "packet.h"

#include "buffer.h"

#include "channels.h"

#include "key.h"

#include "authfd.h"

#include "authfile.h"

#include "pathnames.h"

#include "clientloop.h"

#include "log.h"

#include "readconf.h"

#include "sshconnect.h"

#include "tildexpand.h"

#include "dispatch.h"

#include "misc.h"

#include "kex.h"

#include "mac.h"

#include "sshtty.h"

#ifdef SMARTCARD

#include "scard.h"

#endif

#ifdef HAVE___PROGNAME

extern char *__progname;

#else

char *__progname;

#endif

/* Flag indicating whether IPv4 or IPv6. This can be set on the command line.

Default value is AF_UNSPEC means both IPv4 and IPv6. */

#ifdef IPV4_DEFAULT

int IPv4or6 = AF_INET;

#else

int IPv4or6 = AF_UNSPEC;

#endif

/* Flag indicating whether debug mode is on. This can be set on the command line. */

int debug_flag = 0;

/* Flag indicating whether a tty should be allocated */

int tty_flag = 0;

int no_tty_flag = 0;

int force_tty_flag = 0;

/* don't exec a shell */

int no_shell_flag = 0;

/*

* Flag indicating that nothing should be read from stdin. This can be set

* on the command line.

*/

int stdin_null_flag = 0;

/*

* Flag indicating that ssh should fork after authentication. This is useful

* so that the passphrase can be entered manually, and then ssh goes to the

* background.

*/

int fork_after_authentication_flag = 0;

/*

* General data structure for command line options and options configurable

* in configuration files. See readconf.h.

*/

Options options;

/* optional user configfile */

char *config = NULL;

/*

* Name of the host we are connecting to. This is the name given on the

* command line, or the HostName specified for the user-supplied name in a

* configuration file.

*/

char *host;

/* socket address the host resolves to */

struct sockaddr_storage hostaddr;

/* Private host keys. */

Sensitive sensitive_data;

/* Original real UID. */

uid_t original_real_uid;

uid_t original_effective_uid;

/* command to be executed */

Buffer command;

/* Should we execute a command or invoke a subsystem? */

int subsystem_flag = 0;

/* # of replies received for global requests */

static int client_global_request_id = 0;

/* pid of proxycommand child process */

pid_t proxy_command_pid = 0;

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

static void

usage(void)

{

fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);

fprintf(stderr, "Options:\n");

fprintf(stderr, " -l user Log in using this user name.\n");

fprintf(stderr, " -n Redirect input from " _PATH_DEVNULL ".\n");

fprintf(stderr, " -F config Config file (default: ~/%s).\n",

_PATH_SSH_USER_CONFFILE);

fprintf(stderr, " -A Enable authentication agent forwarding.\n");

fprintf(stderr, " -a Disable authentication agent forwarding (default).\n");

#ifdef AFS

fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");

#endif /* AFS */

fprintf(stderr, " -X Enable X11 connection forwarding.\n");

fprintf(stderr, " -x Disable X11 connection forwarding (default).\n");

fprintf(stderr, " -i file Identity for public key authentication "

"(default: ~/.ssh/identity)\n");

#ifdef SMARTCARD

fprintf(stderr, " -I reader Set smartcard reader.\n");

#endif

fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");

fprintf(stderr, " -T Do not allocate a tty.\n");

fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");

fprintf(stderr, " Multiple -v increases verbosity.\n");

fprintf(stderr, " -V Display version number only.\n");

fprintf(stderr, " -q Quiet; don't display any warning messages.\n");

fprintf(stderr, " -f Fork into background after authentication.\n");

fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");

fprintf(stderr, " -c cipher Select encryption algorithm\n");

fprintf(stderr, " -m macs Specify MAC algorithms for protocol version 2.\n");

fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");

fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");

fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");

fprintf(stderr, " These cause %s to listen for connections on a port, and\n", __progname);

fprintf(stderr, " forward them to the other side by connecting to host:port.\n");

fprintf(stderr, " -D port Enable dynamic application-level port forwarding.\n");

fprintf(stderr, " -C Enable compression.\n");

fprintf(stderr, " -N Do not execute a shell or command.\n");

fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");

fprintf(stderr, " -1 Force protocol version 1.\n");

fprintf(stderr, " -2 Force protocol version 2.\n");

fprintf(stderr, " -4 Use IPv4 only.\n");

fprintf(stderr, " -6 Use IPv6 only.\n");

fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");

fprintf(stderr, " -s Invoke command (mandatory) as SSH2 subsystem.\n");

fprintf(stderr, " -b addr Local IP address.\n");

exit(1);

}

static int ssh_session(void);

static int ssh_session2(void);

static void load_public_identity_files(void);

/*

* Main program for the ssh client.

*/

int

main(int ac, char **av)

{

int i, opt, exit_status;

u_short fwd_port, fwd_host_port;

char sfwd_port[6], sfwd_host_port[6];

char *p, *cp, buf[256];

struct stat st;

struct passwd *pw;

int dummy;

extern int optind, optreset;

extern char *optarg;

__progname = get_progname(av[0]);

init_rng();

/*

* Save the original real uid. It will be needed later (uid-swapping

* may clobber the real uid).

*/

original_real_uid = getuid();

original_effective_uid = geteuid();

/*

* Use uid-swapping to give up root privileges for the duration of

* option processing. We will re-instantiate the rights when we are

* ready to create the privileged port, and will permanently drop

* them when the port has been created (actually, when the connection

* has been made, as we may need to create the port several times).

*/

PRIV_END;

#ifdef HAVE_SETRLIMIT

/* If we are installed setuid root be careful to not drop core. */

if (original_real_uid != original_effective_uid) {

struct rlimit rlim;

rlim.rlim_cur = rlim.rlim_max = 0;

if (setrlimit(RLIMIT_CORE, &rlim) < 0)

fatal("setrlimit failed: %.100s", strerror(errno));

}

#endif

/* Get user data. */

pw = getpwuid(original_real_uid);

if (!pw) {

log("You don't exist, go away!");

exit(1);

}

/* Take a copy of the returned structure. */

pw = pwcopy(pw);

/*

* Set our umask to something reasonable, as some files are created

* with the default umask. This will make them world-readable but

* writable only by the owner, which is ok for all files for which we

* don't set the modes explicitly.

*/

umask(022);

/* Initialize option structure to indicate that no values have been set. */

initialize_options(&options);

/* Parse command-line arguments. */

host = NULL;

again:

while ((opt = getopt(ac, av,

"1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVX")) != -1) {

switch (opt) {

case '1':

options.protocol = SSH_PROTO_1;

break;

case '2':

options.protocol = SSH_PROTO_2;

break;

case '4':

IPv4or6 = AF_INET;

break;

case '6':

IPv4or6 = AF_INET6;

break;

case 'n':

stdin_null_flag = 1;

break;

case 'f':

fork_after_authentication_flag = 1;

stdin_null_flag = 1;

break;

case 'x':

options.forward_x11 = 0;

break;

case 'X':

options.forward_x11 = 1;

break;

case 'g':

options.gateway_ports = 1;

break;

case 'P': /* deprecated */

options.use_privileged_port = 0;

break;

case 'a':

options.forward_agent = 0;

break;

case 'A':

options.forward_agent = 1;

break;

#ifdef AFS

case 'k':

options.kerberos_tgt_passing = 0;

options.afs_token_passing = 0;

break;

#endif

case 'i':

if (stat(optarg, &st) < 0) {

fprintf(stderr, "Warning: Identity file %s "

"does not exist.\n", optarg);

break;

}

if (options.num_identity_files >=

SSH_MAX_IDENTITY_FILES)

fatal("Too many identity files specified "

"(max %d)", SSH_MAX_IDENTITY_FILES);

options.identity_files[options.num_identity_files++] =

xstrdup(optarg);

break;

case 'I':

#ifdef SMARTCARD

options.smartcard_device = xstrdup(optarg);

#else

fprintf(stderr, "no support for smartcards.\n");

#endif

break;

case 't':

if (tty_flag)

force_tty_flag = 1;

tty_flag = 1;

break;

case 'v':

if (0 == debug_flag) {

debug_flag = 1;

options.log_level = SYSLOG_LEVEL_DEBUG1;

} else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {

options.log_level++;

break;

} else

fatal("Too high debugging level.");

/* fallthrough */

case 'V':

fprintf(stderr,

"%s, SSH protocols %d.%d/%d.%d, OpenSSL 0x%8.8lx\n",

SSH_VERSION,

PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,

PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,

SSLeay());

if (opt == 'V')

exit(0);

break;

case 'q':

options.log_level = SYSLOG_LEVEL_QUIET;

break;

case 'e':

if (optarg[0] == '^' && optarg[2] == 0 &&

(u_char) optarg[1] >= 64 &&

(u_char) optarg[1] < 128)

options.escape_char = (u_char) optarg[1] & 31;

else if (strlen(optarg) == 1)

options.escape_char = (u_char) optarg[0];

else if (strcmp(optarg, "none") == 0)

options.escape_char = SSH_ESCAPECHAR_NONE;

else {

fprintf(stderr, "Bad escape character '%s'.\n",

optarg);

exit(1);

}

break;

case 'c':

if (ciphers_valid(optarg)) {

/* SSH2 only */

options.ciphers = xstrdup(optarg);

options.cipher = SSH_CIPHER_ILLEGAL;

} else {

/* SSH1 only */

options.cipher = cipher_number(optarg);

if (options.cipher == -1) {

fprintf(stderr,

"Unknown cipher type '%s'\n",

optarg);

exit(1);

}

if (options.cipher == SSH_CIPHER_3DES)

options.ciphers = "3des-cbc";

else if (options.cipher == SSH_CIPHER_BLOWFISH)

options.ciphers = "blowfish-cbc";

else

options.ciphers = (char *)-1;

}

break;

case 'm':

if (mac_valid(optarg))

options.macs = xstrdup(optarg);

else {

fprintf(stderr, "Unknown mac type '%s'\n",

optarg);

exit(1);

}

break;

case 'p':

options.port = a2port(optarg);

if (options.port == 0) {

fprintf(stderr, "Bad port '%s'\n", optarg);

exit(1);

}

break;

case 'l':

options.user = optarg;

break;

case 'L':

case 'R':

if (sscanf(optarg, "%5[0-9]:%255[^:]:%5[0-9]",

sfwd_port, buf, sfwd_host_port) != 3 &&

sscanf(optarg, "%5[0-9]/%255[^/]/%5[0-9]",

sfwd_port, buf, sfwd_host_port) != 3) {

fprintf(stderr,

"Bad forwarding specification '%s'\n",

optarg);

usage();

/* NOTREACHED */

}

if ((fwd_port = a2port(sfwd_port)) == 0 ||

(fwd_host_port = a2port(sfwd_host_port)) == 0) {

fprintf(stderr,

"Bad forwarding port(s) '%s'\n", optarg);

exit(1);

}

if (opt == 'L')

add_local_forward(&options, fwd_port, buf,

fwd_host_port);

else if (opt == 'R')

add_remote_forward(&options, fwd_port, buf,

fwd_host_port);

break;

case 'D':

fwd_port = a2port(optarg);

if (fwd_port == 0) {

fprintf(stderr, "Bad dynamic port '%s'\n",

optarg);

exit(1);

}

add_local_forward(&options, fwd_port, "socks4", 0);

break;

case 'C':

options.compression = 1;

break;

case 'N':

no_shell_flag = 1;

no_tty_flag = 1;

break;

case 'T':

no_tty_flag = 1;

break;

case 'o':

dummy = 1;

if (process_config_line(&options, host ? host : "",

optarg, "command-line", 0, &dummy) != 0)

exit(1);

break;

case 's':

subsystem_flag = 1;

break;

case 'b':

options.bind_address = optarg;

break;

case 'F':

config = optarg;

break;

default:

usage();

}

}

ac -= optind;

av += optind;

if (ac > 0 && !host && **av != '-') {

if (strrchr(*av, '@')) {

p = xstrdup(*av);

cp = strrchr(p, '@');

if (cp == NULL || cp == p)

usage();

options.user = p;

*cp = '\0';

host = ++cp;

} else

host = *av;

if (ac > 1) {

optind = optreset = 1;

goto again;

}

ac--, av++;

}

/* Check that we got a host name. */

if (!host)

usage();

SSLeay_add_all_algorithms();

ERR_load_crypto_strings();

channel_set_af(IPv4or6);

/* Initialize the command to execute on remote host. */

buffer_init(&command);

/*

* Save the command to execute on the remote host in a buffer. There

* is no limit on the length of the command, except by the maximum

* packet size. Also sets the tty flag if there is no command.

*/

if (!ac) {

/* No command specified - execute shell on a tty. */

tty_flag = 1;

if (subsystem_flag) {

fprintf(stderr,

"You must specify a subsystem to invoke.\n");

usage();

}

} else {

/* A command has been specified. Store it into the buffer. */

for (i = 0; i < ac; i++) {

if (i)

buffer_append(&command, " ", 1);

buffer_append(&command, av[i], strlen(av[i]));

}

}

/* Cannot fork to background if no command. */

if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)

fatal("Cannot fork into background without a command to execute.");

/* Allocate a tty by default if no command specified. */

if (buffer_len(&command) == 0)

tty_flag = 1;

/* Force no tty */

if (no_tty_flag)

tty_flag = 0;

/* Do not allocate a tty if stdin is not a tty. */

if (!isatty(fileno(stdin)) && !force_tty_flag) {

if (tty_flag)

log("Pseudo-terminal will not be allocated because stdin is not a terminal.");

tty_flag = 0;

}

/*

* Initialize "log" output. Since we are the client all output

* actually goes to stderr.

*/

log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,

SYSLOG_FACILITY_USER, 1);

/*

* Read per-user configuration file. Ignore the system wide config

* file if the user specifies a config file on the command line.

*/

if (config != NULL) {

if (!read_config_file(config, host, &options))

fatal("Can't open user config file %.100s: "

"%.100s", config, strerror(errno));

} else {

snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,

_PATH_SSH_USER_CONFFILE);

(void)read_config_file(buf, host, &options);

/* Read systemwide configuration file after use config. */

(void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);

}

/* Fill configuration defaults. */

fill_default_options(&options);

/* reinit */

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

seed_rng();

if (options.user == NULL)

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

if (options.hostname != NULL)

host = options.hostname;

if (options.proxy_command != NULL &&

strcmp(options.proxy_command, "none") == 0)

options.proxy_command = NULL;

/* Disable rhosts authentication if not running as root. */

#ifdef HAVE_CYGWIN

/* Ignore uid if running under Windows */

if (!options.use_privileged_port) {

#else

if (original_effective_uid != 0 || !options.use_privileged_port) {

#endif

debug("Rhosts Authentication disabled, "

"originating port will not be trusted.");

options.rhosts_authentication = 0;

}

/* Open a connection to the remote host. */

if (ssh_connect(host, &hostaddr, options.port, IPv4or6,

options.connection_attempts,

#ifdef HAVE_CYGWIN

options.use_privileged_port,

#else

original_effective_uid == 0 && options.use_privileged_port,

#endif

options.proxy_command) != 0)

exit(1);

/*

* If we successfully made the connection, load the host private key

* in case we will need it later for combined rsa-rhosts

* authentication. This must be done before releasing extra

* privileges, because the file is only readable by root.

* If we cannot access the private keys, load the public keys

* instead and try to execute the ssh-keysign helper instead.

*/

sensitive_data.nkeys = 0;

sensitive_data.keys = NULL;

sensitive_data.external_keysign = 0;

if (options.rhosts_rsa_authentication ||

options.hostbased_authentication) {

sensitive_data.nkeys = 3;

sensitive_data.keys = xmalloc(sensitive_data.nkeys *

sizeof(Key));

PRIV_START;

sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,

_PATH_HOST_KEY_FILE, "", NULL);

sensitive_data.keys[1] = key_load_private_type(KEY_DSA,

_PATH_HOST_DSA_KEY_FILE, "", NULL);

sensitive_data.keys[2] = key_load_private_type(KEY_RSA,

_PATH_HOST_RSA_KEY_FILE, "", NULL);

PRIV_END;

if (options.hostbased_authentication == 1 &&

sensitive_data.keys[0] == NULL &&

sensitive_data.keys[1] == NULL &&

sensitive_data.keys[2] == NULL) {

sensitive_data.keys[1] = key_load_public(

_PATH_HOST_DSA_KEY_FILE, NULL);

sensitive_data.keys[2] = key_load_public(

_PATH_HOST_RSA_KEY_FILE, NULL);

sensitive_data.external_keysign = 1;

}

}

/*

* Get rid of any extra privileges that we may have. We will no

* longer need them. Also, extra privileges could make it very hard

* to read identity files and other non-world-readable files from the

* user's home directory if it happens to be on a NFS volume where

* root is mapped to nobody.

*/

seteuid(original_real_uid);

setuid(original_real_uid);

/*

* Now that we are back to our own permissions, create ~/.ssh

* directory if it doesn\'t already exist.

*/

snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);

if (stat(buf, &st) < 0)

if (mkdir(buf, 0700) < 0)

error("Could not create directory '%.200s'.", buf);

/* load options.identity_files */

load_public_identity_files();

/* Expand ~ in known host file names. */

/* XXX mem-leaks: */

options.system_hostfile =

tilde_expand_filename(options.system_hostfile, original_real_uid);

options.user_hostfile =

tilde_expand_filename(options.user_hostfile, original_real_uid);

options.system_hostfile2 =

tilde_expand_filename(options.system_hostfile2, original_real_uid);

options.user_hostfile2 =

tilde_expand_filename(options.user_hostfile2, original_real_uid);

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

/* Log into the remote system. This never returns if the login fails. */

ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);

/* We no longer need the private host keys. Clear them now. */

if (sensitive_data.nkeys != 0) {

for (i = 0; i < sensitive_data.nkeys; i++) {

if (sensitive_data.keys[i] != NULL) {

/* Destroys contents safely */

debug3("clear hostkey %d", i);

key_free(sensitive_data.keys[i]);

sensitive_data.keys[i] = NULL;

}

}

xfree(sensitive_data.keys);

}

for (i = 0; i < options.num_identity_files; i++) {

if (options.identity_files[i]) {

xfree(options.identity_files[i]);

options.identity_files[i] = NULL;

}

if (options.identity_keys[i]) {

key_free(options.identity_keys[i]);

options.identity_keys[i] = NULL;

}

}

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

packet_close();

/*

* Send SIGHUP to proxy command if used. We don't wait() in

* case it hangs and instead rely on init to reap the child

*/

if (proxy_command_pid > 1)

kill(proxy_command_pid, SIGHUP);

return exit_status;

}

static void

x11_get_proto(char **_proto, char **_data)

{

char line[512];

static char proto[512], data[512];

FILE *f;

int got_data = 0, i;

char *display;

struct stat st;

*_proto = proto;

*_data = data;

proto[0] = data[0] = '\0';

if (!options.xauth_location ||

(stat(options.xauth_location, &st) == -1)) {

debug("No xauth program.");

} else {

if ((display = getenv("DISPLAY")) == NULL) {

debug("x11_get_proto: DISPLAY not set");

return;

}

/* Try to get Xauthority information for the display. */

if (strncmp(display, "localhost:", 10) == 0)

/*

* Handle FamilyLocal case where $DISPLAY does

* not match an authorization entry. For this we

* just try "xauth list unix:displaynum.screennum".

* XXX: "localhost" match to determine FamilyLocal

* is not perfect.

*/

snprintf(line, sizeof line, "%s list unix:%s 2>"

_PATH_DEVNULL, options.xauth_location, display+10);

else

snprintf(line, sizeof line, "%s list %.200s 2>"

_PATH_DEVNULL, options.xauth_location, display);

debug2("x11_get_proto: %s", line);

f = popen(line, "r");

if (f && fgets(line, sizeof(line), f) &&

sscanf(line, "%*s %511s %511s", proto, data) == 2)

got_data = 1;

if (f)

pclose(f);

}

/*

* If we didn't get authentication data, just make up some

* data. The forwarding code will check the validity of the

* response anyway, and substitute this data. The X11

* server, however, will ignore this fake data and use

* whatever authentication mechanisms it was using otherwise

* for the local connection.

*/

if (!got_data) {

u_int32_t rand = 0;

log("Warning: No xauth data; using fake authentication data for X11 forwarding.");

strlcpy(proto, "MIT-MAGIC-COOKIE-1", sizeof proto);

for (i = 0; i < 16; i++) {

if (i % 4 == 0)

rand = arc4random();

snprintf(data + 2 * i, sizeof data - 2 * i, "%02x", rand & 0xff);

rand >>= 8;

}

}

}

static void

ssh_init_forwarding(void)

{

int success = 0;

int i;

/* Initiate local TCP/IP port forwardings. */

for (i = 0; i < options.num_local_forwards; i++) {

debug("Connections to local port %d forwarded to remote address %.200s:%d",

options.local_forwards[i].port,

options.local_forwards[i].host,

options.local_forwards[i].host_port);

success += channel_setup_local_fwd_listener(

options.local_forwards[i].port,

options.local_forwards[i].host,

options.local_forwards[i].host_port,

options.gateway_ports);

}

if (i > 0 && success == 0)

error("Could not request local forwarding.");

/* Initiate remote TCP/IP port forwardings. */

for (i = 0; i < options.num_remote_forwards; i++) {

debug("Connections to remote port %d forwarded to local address %.200s:%d",

options.remote_forwards[i].port,

options.remote_forwards[i].host,

options.remote_forwards[i].host_port);

channel_request_remote_forwarding(

options.remote_forwards[i].port,

options.remote_forwards[i].host,

options.remote_forwards[i].host_port);

}

}

static void

check_agent_present(void)

{

if (options.forward_agent) {

/* Clear agent forwarding if we don\'t have an agent. */

if (!ssh_agent_present())

options.forward_agent = 0;

}

}

static int

ssh_session(void)

{

int type;

int interactive = 0;

int have_tty = 0;

struct winsize ws;

char *cp;

/* Enable compression if requested. */

if (options.compression) {

debug("Requesting compression at level %d.", options.compression_level);

if (options.compression_level < 1 || options.compression_level > 9)

fatal("Compression level must be from 1 (fast) to 9 (slow, best).");

/* Send the request. */

packet_start(SSH_CMSG_REQUEST_COMPRESSION);

packet_put_int(options.compression_level);

packet_send();

packet_write_wait();

type = packet_read();

if (type == SSH_SMSG_SUCCESS)

packet_start_compression(options.compression_level);

else if (type == SSH_SMSG_FAILURE)

log("Warning: Remote host refused compression.");

else

packet_disconnect("Protocol error waiting for compression response.");

}

/* Allocate a pseudo tty if appropriate. */

if (tty_flag) {

debug("Requesting pty.");

/* Start the packet. */

packet_start(SSH_CMSG_REQUEST_PTY);

/* Store TERM in the packet. There is no limit on the

length of the string. */

cp = getenv("TERM");

if (!cp)

cp = "";

packet_put_cstring(cp);

/* Store window size in the packet. */

if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)

memset(&ws, 0, sizeof(ws));

packet_put_int(ws.ws_row);

packet_put_int(ws.ws_col);

packet_put_int(ws.ws_xpixel);

packet_put_int(ws.ws_ypixel);

/* Store tty modes in the packet. */

tty_make_modes(fileno(stdin), NULL);

/* Send the packet, and wait for it to leave. */

packet_send();

packet_write_wait();

/* Read response from the server. */

type = packet_read();

if (type == SSH_SMSG_SUCCESS) {

interactive = 1;

have_tty = 1;

} else if (type == SSH_SMSG_FAILURE)

log("Warning: Remote host failed or refused to allocate a pseudo tty.");

else

packet_disconnect("Protocol error waiting for pty request response.");

}

/* Request X11 forwarding if enabled and DISPLAY is set. */

if (options.forward_x11 && getenv("DISPLAY") != NULL) {

char *proto, *data;

/* Get reasonable local authentication information. */

x11_get_proto(&proto, &data);

/* Request forwarding with authentication spoofing. */

debug("Requesting X11 forwarding with authentication spoofing.");

x11_request_forwarding_with_spoofing(0, proto, data);

/* Read response from the server. */

type = packet_read();

if (type == SSH_SMSG_SUCCESS) {

interactive = 1;

} else if (type == SSH_SMSG_FAILURE) {

log("Warning: Remote host denied X11 forwarding.");

} else {

packet_disconnect("Protocol error waiting for X11 forwarding");

}

}

/* Tell the packet module whether this is an interactive session. */

packet_set_interactive(interactive);

/* Request authentication agent forwarding if appropriate. */

check_agent_present();

if (options.forward_agent) {

debug("Requesting authentication agent forwarding.");

auth_request_forwarding();

/* Read response from the server. */

type = packet_read();

packet_check_eom();

if (type != SSH_SMSG_SUCCESS)

log("Warning: Remote host denied authentication agent forwarding.");

}

/* Initiate port forwardings. */

ssh_init_forwarding();

/* If requested, let ssh continue in the background. */

if (fork_after_authentication_flag)

if (daemon(1, 1) < 0)

fatal("daemon() failed: %.200s", strerror(errno));

/*

* If a command was specified on the command line, execute the

* command now. Otherwise request the server to start a shell.

*/

if (buffer_len(&command) > 0) {

int len = buffer_len(&command);

if (len > 900)

len = 900;

debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));

packet_start(SSH_CMSG_EXEC_CMD);

packet_put_string(buffer_ptr(&command), buffer_len(&command));

packet_send();

packet_write_wait();

} else {

debug("Requesting shell.");

packet_start(SSH_CMSG_EXEC_SHELL);

packet_send();

packet_write_wait();

}

/* Enter the interactive session. */

return client_loop(have_tty, tty_flag ?

options.escape_char : SSH_ESCAPECHAR_NONE, 0);

}

static void

client_subsystem_reply(int type, u_int32_t seq, void *ctxt)

{

int id, len;

id = packet_get_int();

len = buffer_len(&command);

if (len > 900)

len = 900;

packet_check_eom();

if (type == SSH2_MSG_CHANNEL_FAILURE)

fatal("Request for subsystem '%.*s' failed on channel %d",

len, (u_char *)buffer_ptr(&command), id);