view cli-runopts.c @ 1156:a8f4dade70e5

avoid getpass when not used some systems (like android's bionic) do not provide getpass. you can disable ENABLE_CLI_PASSWORD_AUTH & ENABLE_CLI_INTERACT_AUTH to avoid its use (and rely on pubkey auth), but the link still fails because the support file calls getpass. do not define this func if both of those auth methods are not used.
author Mike Frysinger <vapier@gentoo.org>
date Wed, 21 Oct 2015 22:39:55 +0800
parents 67d8a904f5a9
children 1b583b2994ba
line wrap: on
line source

/*
 * Dropbear - a SSH2 server
 * 
 * Copyright (c) 2002,2003 Matt Johnston
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE. */

#include "includes.h"
#include "runopts.h"
#include "signkey.h"
#include "buffer.h"
#include "dbutil.h"
#include "algo.h"
#include "tcpfwd.h"
#include "list.h"

cli_runopts cli_opts; /* GLOBAL */

static void printhelp();
static void parse_hostname(const char* orighostarg);
static void parse_multihop_hostname(const char* orighostarg, const char* argv0);
static void fill_own_user();
#ifdef ENABLE_CLI_PUBKEY_AUTH
static void loadidentityfile(const char* filename, int warnfail);
#endif
#ifdef ENABLE_CLI_ANYTCPFWD
static void addforward(const char* str, m_list *fwdlist);
#endif
#ifdef ENABLE_CLI_NETCAT
static void add_netcat(const char *str);
#endif

static void printhelp() {

	fprintf(stderr, "Dropbear SSH client v%s https://matt.ucc.asn.au/dropbear/dropbear.html\n"
#ifdef ENABLE_CLI_MULTIHOP
					"Usage: %s [options] [user@]host[/port][,[user@]host/port],...] [command]\n"
#else
					"Usage: %s [options] [user@]host[/port] [command]\n"
#endif
					"-p <remoteport>\n"
					"-l <username>\n"
					"-t    Allocate a pty\n"
					"-T    Don't allocate a pty\n"
					"-N    Don't run a remote command\n"
					"-f    Run in background after auth\n"
					"-y    Always accept remote host key if unknown\n"
					"-y -y Don't perform any remote host key checking (caution)\n"
					"-s    Request a subsystem (use by external sftp)\n"
#ifdef ENABLE_CLI_PUBKEY_AUTH
					"-i <identityfile>   (multiple allowed, default %s)\n"
#endif
#ifdef ENABLE_CLI_AGENTFWD
					"-A    Enable agent auth forwarding\n"
#endif
#ifdef ENABLE_CLI_LOCALTCPFWD
					"-L <[listenaddress:]listenport:remotehost:remoteport> Local port forwarding\n"
					"-g    Allow remote hosts to connect to forwarded ports\n"
#endif
#ifdef ENABLE_CLI_REMOTETCPFWD
					"-R <[listenaddress:]listenport:remotehost:remoteport> Remote port forwarding\n"
#endif
					"-W <receive_window_buffer> (default %d, larger may be faster, max 1MB)\n"
					"-K <keepalive>  (0 is never, default %d)\n"
					"-I <idle_timeout>  (0 is never, default %d)\n"
#ifdef ENABLE_CLI_NETCAT
					"-B <endhost:endport> Netcat-alike forwarding\n"
#endif				
#ifdef ENABLE_CLI_PROXYCMD
					"-J <proxy_program> Use program pipe rather than TCP connection\n"
#endif
#ifdef ENABLE_USER_ALGO_LIST
					"-c <cipher list> Specify preferred ciphers ('-c help' to list options)\n"
					"-m <MAC list> Specify preferred MACs for packet verification (or '-m help')\n"
#endif
					"-V    Version\n"
#ifdef DEBUG_TRACE
					"-v    verbose (compiled with DEBUG_TRACE)\n"
#endif
					,DROPBEAR_VERSION, cli_opts.progname,
#ifdef ENABLE_CLI_PUBKEY_AUTH
					DROPBEAR_DEFAULT_CLI_AUTHKEY,
#endif
					DEFAULT_RECV_WINDOW, DEFAULT_KEEPALIVE, DEFAULT_IDLE_TIMEOUT);
					
}

void cli_getopts(int argc, char ** argv) {
	unsigned int i, j;
	char ** next = 0;
	unsigned int cmdlen;
#ifdef ENABLE_CLI_PUBKEY_AUTH
	int nextiskey = 0; /* A flag if the next argument is a keyfile */
#endif
#ifdef ENABLE_CLI_LOCALTCPFWD
	int nextislocal = 0;
#endif
#ifdef ENABLE_CLI_REMOTETCPFWD
	int nextisremote = 0;
#endif
#ifdef ENABLE_CLI_NETCAT
	int nextisnetcat = 0;
#endif
	char* dummy = NULL; /* Not used for anything real */

	char* recv_window_arg = NULL;
	char* keepalive_arg = NULL;
	char* idle_timeout_arg = NULL;
	char *host_arg = NULL;

	/* see printhelp() for options */
	cli_opts.progname = argv[0];
	cli_opts.remotehost = NULL;
	cli_opts.remoteport = NULL;
	cli_opts.username = NULL;
	cli_opts.cmd = NULL;
	cli_opts.no_cmd = 0;
	cli_opts.backgrounded = 0;
	cli_opts.wantpty = 9; /* 9 means "it hasn't been touched", gets set later */
	cli_opts.always_accept_key = 0;
	cli_opts.no_hostkey_check = 0;
	cli_opts.is_subsystem = 0;
#ifdef ENABLE_CLI_PUBKEY_AUTH
	cli_opts.privkeys = list_new();
#endif
#ifdef ENABLE_CLI_LOCALTCPFWD
	cli_opts.localfwds = list_new();
	opts.listen_fwd_all = 0;
#endif
#ifdef ENABLE_CLI_REMOTETCPFWD
	cli_opts.remotefwds = list_new();
#endif
#ifdef ENABLE_CLI_AGENTFWD
	cli_opts.agent_fwd = 0;
	cli_opts.agent_fd = -1;
	cli_opts.agent_keys_loaded = 0;
#endif
#ifdef ENABLE_CLI_PROXYCMD
	cli_opts.proxycmd = NULL;
#endif
#ifndef DISABLE_ZLIB
	opts.compress_mode = DROPBEAR_COMPRESS_ON;
#endif
#ifdef ENABLE_USER_ALGO_LIST
	opts.cipher_list = NULL;
	opts.mac_list = NULL;
#endif
	/* not yet
	opts.ipv4 = 1;
	opts.ipv6 = 1;
	*/
	opts.recv_window = DEFAULT_RECV_WINDOW;
	opts.keepalive_secs = DEFAULT_KEEPALIVE;
	opts.idle_timeout_secs = DEFAULT_IDLE_TIMEOUT;

	fill_own_user();

	/* Iterate all the arguments */
	for (i = 1; i < (unsigned int)argc; i++) {
#ifdef ENABLE_CLI_PUBKEY_AUTH
		if (nextiskey) {
			/* Load a hostkey since the previous argument was "-i" */
			loadidentityfile(argv[i], 1);
			nextiskey = 0;
			continue;
		}
#endif
#ifdef ENABLE_CLI_REMOTETCPFWD
		if (nextisremote) {
			TRACE(("nextisremote true"))
			addforward(argv[i], cli_opts.remotefwds);
			nextisremote = 0;
			continue;
		}
#endif
#ifdef ENABLE_CLI_LOCALTCPFWD
		if (nextislocal) {
			TRACE(("nextislocal true"))
			addforward(argv[i], cli_opts.localfwds);
			nextislocal = 0;
			continue;
		}
#endif
#ifdef ENABLE_CLI_NETCAT
		if (nextisnetcat) {
			TRACE(("nextisnetcat true"))
			add_netcat(argv[i]);
			nextisnetcat = 0;
			continue;
		}
#endif
		if (next) {
			/* The previous flag set a value to assign */
			*next = argv[i];
			if (*next == NULL) {
				dropbear_exit("Invalid null argument");
			}
			next = NULL;
			continue;
		}

		if (argv[i][0] == '-') {
			/* A flag *waves* */
			char c = argv[i][1];
			if (strlen(argv[i]) != 2) {
				/* Ensure only one flag per hyphen. '?' falls through to print help */
				c = '?';
			}
			switch (c) {
				case 'y': /* always accept the remote hostkey */
					if (cli_opts.always_accept_key) {
						/* twice means no checking at all */
						cli_opts.no_hostkey_check = 1;
					}
					cli_opts.always_accept_key = 1;
					break;
				case 'p': /* remoteport */
					next = &cli_opts.remoteport;
					break;
#ifdef ENABLE_CLI_PUBKEY_AUTH
				case 'i': /* an identityfile */
					/* Keep scp happy when it changes "-i file" to "-ifile" */
					if (strlen(argv[i]) > 2) {
						loadidentityfile(&argv[i][2], 1);
					} else  {
						nextiskey = 1;
					}
					break;
#endif
				case 't': /* we want a pty */
					cli_opts.wantpty = 1;
					break;
				case 'T': /* don't want a pty */
					cli_opts.wantpty = 0;
					break;
				case 'N':
					cli_opts.no_cmd = 1;
					break;
				case 'f':
					cli_opts.backgrounded = 1;
					break;
				case 's':
					cli_opts.is_subsystem = 1;
					break;
#ifdef ENABLE_CLI_LOCALTCPFWD
				case 'L':
					nextislocal = 1;
					break;
				case 'g':
					opts.listen_fwd_all = 1;
					break;
#endif
#ifdef ENABLE_CLI_REMOTETCPFWD
				case 'R':
					nextisremote = 1;
					break;
#endif
#ifdef ENABLE_CLI_NETCAT
				case 'B':
					nextisnetcat = 1;
					break;
#endif
#ifdef ENABLE_CLI_PROXYCMD
				case 'J':
					next = &cli_opts.proxycmd;
					break;
#endif
				case 'l':
					next = &cli_opts.username;
					break;
				case 'h':
					printhelp();
					exit(EXIT_SUCCESS);
					break;
				case 'u':
					/* backwards compatibility with old urandom option */
					break;
				case 'W':
					next = &recv_window_arg;
					break;
				case 'K':
					next = &keepalive_arg;
					break;
				case 'I':
					next = &idle_timeout_arg;
					break;
#ifdef ENABLE_CLI_AGENTFWD
				case 'A':
					cli_opts.agent_fwd = 1;
					break;
#endif
#ifdef ENABLE_USER_ALGO_LIST
				case 'c':
					next = &opts.cipher_list;
					break;
				case 'm':
					next = &opts.mac_list;
					break;
#endif
#ifdef DEBUG_TRACE
				case 'v':
					debug_trace = 1;
					break;
#endif
				case 'F':
				case 'e':
#ifndef ENABLE_USER_ALGO_LIST
				case 'c':
				case 'm':
#endif
				case 'D':
#ifndef ENABLE_CLI_REMOTETCPFWD
				case 'R':
#endif
#ifndef ENABLE_CLI_LOCALTCPFWD
				case 'L':
#endif
				case 'V':
					print_version();
					exit(EXIT_SUCCESS);
					break;
				case 'o':
				case 'b':
					next = &dummy;
				default:
					fprintf(stderr, 
						"WARNING: Ignoring unknown argument '%s'\n", argv[i]);
					break;
			} /* Switch */
			
			/* Now we handle args where they might be "-luser" (no spaces)*/
			if (next && strlen(argv[i]) > 2) {
				*next = &argv[i][2];
				next = NULL;
			}

			continue; /* next argument */

		} else {
			TRACE(("non-flag arg: '%s'", argv[i]))

			/* Either the hostname or commands */

			if (host_arg == NULL) {
				host_arg = argv[i];
			} else {

				/* this is part of the commands to send - after this we
				 * don't parse any more options, and flags are sent as the
				 * command */
				cmdlen = 0;
				for (j = i; j < (unsigned int)argc; j++) {
					cmdlen += strlen(argv[j]) + 1; /* +1 for spaces */
				}
				/* Allocate the space */
				cli_opts.cmd = (char*)m_malloc(cmdlen);
				cli_opts.cmd[0] = '\0';

				/* Append all the bits */
				for (j = i; j < (unsigned int)argc; j++) {
					strlcat(cli_opts.cmd, argv[j], cmdlen);
					strlcat(cli_opts.cmd, " ", cmdlen);
				}
				/* It'll be null-terminated here */

				/* We've eaten all the options and flags */
				break;
			}
		}
	}

	/* And now a few sanity checks and setup */

#ifdef ENABLE_USER_ALGO_LIST
	parse_ciphers_macs();
#endif

	if (host_arg == NULL) {
		printhelp();
		exit(EXIT_FAILURE);
	}

#ifdef ENABLE_CLI_PROXYCMD                                                                                                                                   
	if (cli_opts.proxycmd) {
		/* To match the common path of m_freeing it */
		cli_opts.proxycmd = m_strdup(cli_opts.proxycmd);
	}
#endif

	if (cli_opts.remoteport == NULL) {
		cli_opts.remoteport = "22";
	}

	/* If not explicitly specified with -t or -T, we don't want a pty if
	 * there's a command, but we do otherwise */
	if (cli_opts.wantpty == 9) {
		if (cli_opts.cmd == NULL) {
			cli_opts.wantpty = 1;
		} else {
			cli_opts.wantpty = 0;
		}
	}

	if (cli_opts.backgrounded && cli_opts.cmd == NULL
			&& cli_opts.no_cmd == 0) {
		dropbear_exit("Command required for -f");
	}
	
	if (recv_window_arg) {
		opts.recv_window = atol(recv_window_arg);
		if (opts.recv_window == 0 || opts.recv_window > MAX_RECV_WINDOW) {
			dropbear_exit("Bad recv window '%s'", recv_window_arg);
		}
	}
	if (keepalive_arg) {
		unsigned int val;
		if (m_str_to_uint(keepalive_arg, &val) == DROPBEAR_FAILURE) {
			dropbear_exit("Bad keepalive '%s'", keepalive_arg);
		}
		opts.keepalive_secs = val;
	}

	if (idle_timeout_arg) {
		unsigned int val;
		if (m_str_to_uint(idle_timeout_arg, &val) == DROPBEAR_FAILURE) {
			dropbear_exit("Bad idle_timeout '%s'", idle_timeout_arg);
		}
		opts.idle_timeout_secs = val;
	}

#ifdef ENABLE_CLI_NETCAT
	if (cli_opts.cmd && cli_opts.netcat_host) {
		dropbear_log(LOG_INFO, "Ignoring command '%s' in netcat mode", cli_opts.cmd);
	}
#endif

#if defined(DROPBEAR_DEFAULT_CLI_AUTHKEY) && defined(ENABLE_CLI_PUBKEY_AUTH)
	{
		char *expand_path = expand_homedir_path(DROPBEAR_DEFAULT_CLI_AUTHKEY);
		loadidentityfile(expand_path, 0);
		m_free(expand_path);
	}
#endif

	/* The hostname gets set up last, since
	 * in multi-hop mode it will require knowledge
	 * of other flags such as -i */
#ifdef ENABLE_CLI_MULTIHOP
	parse_multihop_hostname(host_arg, argv[0]);
#else
	parse_hostname(host_arg);
#endif
}

#ifdef ENABLE_CLI_PUBKEY_AUTH
static void loadidentityfile(const char* filename, int warnfail) {
	sign_key *key;
	enum signkey_type keytype;

	TRACE(("loadidentityfile %s", filename))

	key = new_sign_key();
	keytype = DROPBEAR_SIGNKEY_ANY;
	if ( readhostkey(filename, key, &keytype) != DROPBEAR_SUCCESS ) {
		if (warnfail) {
			fprintf(stderr, "Failed loading keyfile '%s'\n", filename);
		}
		sign_key_free(key);
	} else {
		key->type = keytype;
		key->source = SIGNKEY_SOURCE_RAW_FILE;
		key->filename = m_strdup(filename);
		list_append(cli_opts.privkeys, key);
	}
}
#endif

#ifdef ENABLE_CLI_MULTIHOP

static char*
multihop_passthrough_args() {
	char *ret;
	int total;
	unsigned int len = 0;
	m_list_elem *iter;
	/* Fill out -i, -y, -W options that make sense for all
	 * the intermediate processes */
#ifdef ENABLE_CLI_PUBKEY_AUTH
	for (iter = cli_opts.privkeys->first; iter; iter = iter->next)
	{
		sign_key * key = (sign_key*)iter->item;
		len += 3 + strlen(key->filename);
	}
#endif /* ENABLE_CLI_PUBKEY_AUTH */

	len += 30; /* space for -W <size>, terminator. */
	ret = m_malloc(len);
	total = 0;

	if (cli_opts.no_hostkey_check)
	{
		int written = snprintf(ret+total, len-total, "-y -y ");
		total += written;
	}
	else if (cli_opts.always_accept_key)
	{
		int written = snprintf(ret+total, len-total, "-y ");
		total += written;
	}

	if (opts.recv_window != DEFAULT_RECV_WINDOW)
	{
		int written = snprintf(ret+total, len-total, "-W %d ", opts.recv_window);
		total += written;
	}

#ifdef ENABLE_CLI_PUBKEY_AUTH
	for (iter = cli_opts.privkeys->first; iter; iter = iter->next)
	{
		sign_key * key = (sign_key*)iter->item;
		const size_t size = len - total;
		int written = snprintf(ret+total, size, "-i %s ", key->filename);
		dropbear_assert((unsigned int)written < size);
		total += written;
	}
#endif /* ENABLE_CLI_PUBKEY_AUTH */

	/* if args were passed, total will be not zero, and it will have a space at the end, so remove that */
	if (total > 0) 
	{
		total--;
	}

	return ret;
}

/* Sets up 'onion-forwarding' connections. This will spawn
 * a separate dbclient process for each hop.
 * As an example, if the cmdline is
 *   dbclient wrt,madako,canyons
 * then we want to run:
 *   dbclient -J "dbclient -B canyons:22 wrt,madako" canyons
 * and then the inner dbclient will recursively run:
 *   dbclient -J "dbclient -B madako:22 wrt" madako
 * etc for as many hosts as we want.
 *
 * Ports for hosts can be specified as host/port.
 */
static void parse_multihop_hostname(const char* orighostarg, const char* argv0) {
	char *userhostarg = NULL;
	char *hostbuf = NULL;
	char *last_hop = NULL;
	char *remainder = NULL;

	/* both scp and rsync parse a user@host argument
	 * and turn it into "-l user host". This breaks
	 * for our multihop syntax, so we suture it back together.
	 * This will break usernames that have both '@' and ',' in them,
	 * though that should be fairly uncommon. */
	if (cli_opts.username 
			&& strchr(cli_opts.username, ',') 
			&& strchr(cli_opts.username, '@')) {
		unsigned int len = strlen(orighostarg) + strlen(cli_opts.username) + 2;
		hostbuf = m_malloc(len);
		snprintf(hostbuf, len, "%s@%s", cli_opts.username, orighostarg);
	} else {
		hostbuf = m_strdup(orighostarg);
	}
	userhostarg = hostbuf;

	last_hop = strrchr(userhostarg, ',');
	if (last_hop) {
		if (last_hop == userhostarg) {
			dropbear_exit("Bad multi-hop hostnames");
		}
		*last_hop = '\0';
		last_hop++;
		remainder = userhostarg;
		userhostarg = last_hop;
	}

	parse_hostname(userhostarg);

	if (last_hop) {
		/* Set up the proxycmd */
		unsigned int cmd_len = 0;
		char *passthrough_args = multihop_passthrough_args();
		if (cli_opts.proxycmd) {
			dropbear_exit("-J can't be used with multihop mode");
		}
		if (cli_opts.remoteport == NULL) {
			cli_opts.remoteport = "22";
		}
		cmd_len = strlen(argv0) + strlen(remainder) 
			+ strlen(cli_opts.remotehost) + strlen(cli_opts.remoteport)
			+ strlen(passthrough_args)
			+ 30;
		cli_opts.proxycmd = m_malloc(cmd_len);
		snprintf(cli_opts.proxycmd, cmd_len, "%s -B %s:%s %s %s", 
				argv0, cli_opts.remotehost, cli_opts.remoteport, 
				passthrough_args, remainder);
#ifndef DISABLE_ZLIB
		/* The stream will be incompressible since it's encrypted. */
		opts.compress_mode = DROPBEAR_COMPRESS_OFF;
#endif
		m_free(passthrough_args);
	}
	m_free(hostbuf);
}
#endif /* !ENABLE_CLI_MULTIHOP */

/* Parses a [user@]hostname[/port] argument. */
static void parse_hostname(const char* orighostarg) {
	char *userhostarg = NULL;
	char *port = NULL;

	userhostarg = m_strdup(orighostarg);

	cli_opts.remotehost = strchr(userhostarg, '@');
	if (cli_opts.remotehost == NULL) {
		/* no username portion, the cli-auth.c code can figure the
		 * local user's name */
		cli_opts.remotehost = userhostarg;
	} else {
		cli_opts.remotehost[0] = '\0'; /* Split the user/host */
		cli_opts.remotehost++;
		cli_opts.username = userhostarg;
	}

	if (cli_opts.username == NULL) {
		cli_opts.username = m_strdup(cli_opts.own_user);
	}

	port = strchr(cli_opts.remotehost, '^');
	if (!port)  {
		/* legacy separator */
		port = strchr(cli_opts.remotehost, '/');
	}
	if (port) {
		*port = '\0';
		cli_opts.remoteport = port+1;
	}

	if (cli_opts.remotehost[0] == '\0') {
		dropbear_exit("Bad hostname");
	}
}

#ifdef ENABLE_CLI_NETCAT
static void add_netcat(const char* origstr) {
	char *portstr = NULL;
	
	char * str = m_strdup(origstr);
	
	portstr = strchr(str, ':');
	if (portstr == NULL) {
		TRACE(("No netcat port"))
		goto fail;
	}
	*portstr = '\0';
	portstr++;
	
	if (strchr(portstr, ':')) {
		TRACE(("Multiple netcat colons"))
		goto fail;
	}
	
	if (m_str_to_uint(portstr, &cli_opts.netcat_port) == DROPBEAR_FAILURE) {
		TRACE(("bad netcat port"))
		goto fail;
	}
	
	if (cli_opts.netcat_port > 65535) {
		TRACE(("too large netcat port"))
		goto fail;
	}
	
	cli_opts.netcat_host = str;
	return;
	
fail:
	dropbear_exit("Bad netcat endpoint '%s'", origstr);
}
#endif

static void fill_own_user() {
	uid_t uid;
	struct passwd *pw = NULL; 

	uid = getuid();

	pw = getpwuid(uid);
	if (pw && pw->pw_name != NULL) {
		cli_opts.own_user = m_strdup(pw->pw_name);
	} else {
		dropbear_log(LOG_INFO, "Warning: failed to identify current user. Trying anyway.");
		cli_opts.own_user = m_strdup("unknown");
	}

}

#ifdef ENABLE_CLI_ANYTCPFWD
/* Turn a "[listenaddr:]listenport:remoteaddr:remoteport" string into into a forwarding
 * set, and add it to the forwarding list */
static void addforward(const char* origstr, m_list *fwdlist) {

	char *part1 = NULL, *part2 = NULL, *part3 = NULL, *part4 = NULL;
	char * listenaddr = NULL;
	char * listenport = NULL;
	char * connectaddr = NULL;
	char * connectport = NULL;
	struct TCPFwdEntry* newfwd = NULL;
	char * str = NULL;

	TRACE(("enter addforward"))

	/* We need to split the original argument up. This var
	   is never free()d. */ 
	str = m_strdup(origstr);

	part1 = str;

	part2 = strchr(str, ':');
	if (part2 == NULL) {
		TRACE(("part2 == NULL"))
		goto fail;
	}
	*part2 = '\0';
	part2++;

	part3 = strchr(part2, ':');
	if (part3 == NULL) {
		TRACE(("part3 == NULL"))
		goto fail;
	}
	*part3 = '\0';
	part3++;

	part4 = strchr(part3, ':');
	if (part4) {
		*part4 = '\0';
		part4++;
	}

	if (part4) {
		listenaddr = part1;
		listenport = part2;
		connectaddr = part3;
		connectport = part4;
	} else {
		listenaddr = NULL;
		listenport = part1;
		connectaddr = part2;
		connectport = part3;
	}

	newfwd = m_malloc(sizeof(struct TCPFwdEntry));

	/* Now we check the ports - note that the port ints are unsigned,
	 * the check later only checks for >= MAX_PORT */
	if (m_str_to_uint(listenport, &newfwd->listenport) == DROPBEAR_FAILURE) {
		TRACE(("bad listenport strtoul"))
		goto fail;
	}

	if (m_str_to_uint(connectport, &newfwd->connectport) == DROPBEAR_FAILURE) {
		TRACE(("bad connectport strtoul"))
		goto fail;
	}

	newfwd->listenaddr = listenaddr;
	newfwd->connectaddr = connectaddr;

	if (newfwd->listenport > 65535) {
		TRACE(("listenport > 65535"))
		goto badport;
	}
		
	if (newfwd->connectport > 65535) {
		TRACE(("connectport > 65535"))
		goto badport;
	}

	newfwd->have_reply = 0;
	list_append(fwdlist, newfwd);

	TRACE(("leave addforward: done"))
	return;

fail:
	dropbear_exit("Bad TCP forward '%s'", origstr);

badport:
	dropbear_exit("Bad TCP port in '%s'", origstr);
}
#endif