rconnect.c

sock protocol ,it is useful!

/*
 * Copyright (c) 1997, 1998, 1999
 *      Inferno Nettverk A/S, Norway.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. The above copyright notice, this list of conditions and the following
 *    disclaimer must appear in all copies of the software, derivative works
 *    or modified versions, and any portions thereof, aswell as in all
 *    supporting documentation.
 * 2. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by
 *      Inferno Nettverk A/S, Norway.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * 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.
 *
 * Inferno Nettverk A/S requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  [e-mail]
 *  Inferno Nettverk A/S
 *  Oslo Research Park
 *  Gaustadal閑n 21
 *  N-0349 Oslo
 *  Norway
 *
 * any improvements or extensions that they make and grant Inferno Nettverk A/S
 * the rights to redistribute these changes.
 *
 */

#include "common.h"

static const char rcsid[] =
"$Id: Rconnect.c,v 1.106 1999/12/22 09:29:21 karls Exp $";

int
Rconnect(s, name, namelen)
	int s;
	const struct sockaddr *name;
	socklen_t namelen;
{
	const char *function = "Rconnect()";
	struct sockshost_t src, dst;
	struct socksfd_t socksfd;
	struct socks_t packet;
	socklen_t len;
	int type, p;

	if (name->sa_family != AF_INET)
		return connect(s, name, namelen);

	if (socks_addrisok((unsigned int)s)) {
		struct socksfd_t *socksfdp;

		socksfdp = socks_getaddr((unsigned int)s);

		switch (socksfdp->state.command) {
			case SOCKS_BIND:
				/*
				 * Our guess; the client has succeeded to bind a specific
				 * address and is now trying to connect out from it.
				 * That also indicates the socksserver is listening on a port
				 * for this client.  Can't accept() on a connected socket so
				 * lets close the connection to the server so it can stop
				 * listening on our behalf and we continue as if this was an
				 * ordinary connect().  Can only hope the server will use
				 * same port as we for connecting out.
				 */
				socks_rmaddr((unsigned int)s);
				break;

			case SOCKS_CONNECT:
				if (socksfdp->state.inprogress)
					if (socksfdp->state.err != 0) /* connect failed. */
						errno = socksfdp->state.err;
					else
						errno = EALREADY;
				else
					errno = EISCONN;	/* socket connected. */
				return -1;

			case SOCKS_UDPASSOCIATE:
				/*
				 * Trying to connect a udp socket (to a new address)?
				 * Just continue as usual, udpsetup() will reuse existing
				 * setup and we just assign the new ("connected") address.
				 */
				break;

			default:
				SERRX(socksfdp->state.command);
		}
	}
	else
		socks_rmaddr((unsigned int)s);

	len = sizeof(type);
	if (getsockopt(s, SOL_SOCKET, SO_TYPE, &type, &len) != 0)
		return -1;

	switch (type) {
		case SOCK_DGRAM: {
			struct socksfd_t *socksfdp;

			if (udpsetup(s, name, SOCKS_SEND) == 0) {
				socksfdp = socks_getaddr((unsigned int)s);
				SASSERTX(socksfdp != NULL);

				if (connect(s, &socksfdp->reply, sizeof(socksfdp->reply)) != 0) {
					socks_rmaddr((unsigned int)s);
					return -1;
				}

				socksfdp->state.udpconnect		= 1;
				socksfdp->connected				= *name;

				return 0;
			}
			else {
				if (errno == 0)
					/* not a network error, try standard connect. */
					return connect(s, name, namelen);
				else
					return -1;
			}
		}
	}


	bzero(&socksfd, sizeof(socksfd));
	len = sizeof(socksfd.local);
	if (getsockname(s, &socksfd.local, &len) != 0)
		return -1;

	src.atype		= SOCKS_ADDR_IPV4;
	/* LINTED pointer casts may be troublesome */
	src.addr.ipv4	= ((const struct sockaddr_in *)&socksfd.local)->sin_addr;
	/* LINTED pointer casts may be troublesome */
	src.port			= ((const struct sockaddr_in *)&socksfd.local)->sin_port;

	fakesockaddr2sockshost(name, &dst);

	bzero(&packet, sizeof(packet));
	packet.req.host		= dst;
	packet.req.version	= SOCKS_V5;
	packet.req.command	= SOCKS_CONNECT;

	if (socks_requestpolish(&packet.req, &src, &dst) == NULL)
		return connect(s, name, namelen);

	switch (packet.req.version) {
		case SOCKS_V4:
		case SOCKS_V5:
			socksfd.control = s;
			break;

		case MSPROXY_V2:
			/* always needs a separate controlchannel. */
			if ((socksfd.control = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
				return -1;
			break;

		default:
			SERRX(packet.req.version);
	}

	if ((p = fcntl(s, F_GETFL, 0)) == -1)
		return -1;

	if (p & NONBLOCKING)
		socksfd.route
		= socks_nbconnectroute(s, socksfd.control, &packet, &src, &dst);
	else
		socksfd.route = socks_connectroute(socksfd.control, &packet, &src, &dst);

	if (socksfd.route == NULL) {
		if (s != socksfd.control)
			close(socksfd.control);

		switch (errno) {
			case EADDRINUSE: {
				/*
				 * This problem can arise when we are socksifying
				 * a serverapplication that does several outbound
				 * connections from the same address (e.g. ftpd) to the
				 * same socksserver.
				 * It has by now successfully bound the address (it thinks)
				 * and is not expecting this error.
				 * Not sure what is best to do, just failing here prevents
				 * ftpd from working for clients using the PORT command.
				 *
				 * For now, lets retry with a new socket.
				 * This means the server no longer has bound the address
				 * it (may) think it has ofcourse, so not sure how smart this
				 * really is.
				 */
				int tmp_s;

				swarn("%s: server socksified?  trying to work around problem...",
				function);

				if ((tmp_s = socketoptdup(s)) == -1)
					break;
				if (dup2(tmp_s, s) == -1)
					break;
				close(tmp_s);

				/*
				 * if s was bound to a privileged port, try to bind the new
				 * s too to a privileged port.
				 */
				/* LINTED pointer casts may be troublesome */
				if (PORTISRESERVED(((struct sockaddr_in *)
				&socksfd.local)->sin_port)) {
					/* LINTED pointer casts may be troublesome */
					((struct sockaddr_in *)&socksfd.local)->sin_port = htons(0);

					/* LINTED pointer casts may be troublesome */
					bindresvport(s, (struct sockaddr_in *)&socksfd.local);
				}
				return Rconnect(s, name, namelen);
			}
		}

		return errno == 0 ? connect(s, name, namelen) : -1;
	}

	if (p & NONBLOCKING)
		return -1; /* got route, nonblocking connect in progress. */

	if (socks_negotiate(s, socksfd.control, &packet, socksfd.route) != 0)
		return -1;

	socksfd.state.auth				= packet.auth;
	socksfd.state.command			= packet.req.command;
	socksfd.state.version			= packet.req.version;
	socksfd.state.protocol.tcp		= 1;
	socksfd.state.msproxy			= packet.state.msproxy;
	sockshost2sockaddr(&packet.res.host, &socksfd.remote);
	socksfd.connected					= *name;

	/* LINTED pointer casts may be troublesome */
	if (((struct sockaddr_in *)&socksfd.local)->sin_port != htons(0)
	&&  ((struct sockaddr_in *)&socksfd.local)->sin_port !=
		 ((struct sockaddr_in *)&socksfd.remote)->sin_port) {
		/*
		 * unfortunate; the client is trying to connect from a specific
		 * port, a port it has successfully bound, but the port is currently
		 * in use on the serverside or the server doesn't care.
		 */

		/* LINTED pointer casts may be troublesome */
		slog(LOG_DEBUG, "failed to get wanted port: %d",
		ntohs(((struct sockaddr_in *)&socksfd.local)->sin_port));
	}

	len = sizeof(socksfd.server);
	if (getpeername(s, &socksfd.server, &len) != 0) {
		if (s != socksfd.control)
			close(socksfd.control);
		return -1;
	}

	len = sizeof(socksfd.local);
	if (getsockname(s, &socksfd.local, &len) != 0) {
		if (s != socksfd.control)
			close(socksfd.control);
		return -1;
	}

	socks_addaddr((unsigned int)s, &socksfd);

	config.state.lastconnect = *name;	/* needed for standard socks bind. */

	return 0;
}