[apple/network_cmds.git] / alias / alias_smedia.c

/*
 * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * alias_smedia.c
 *
 * Copyright (c) 2000 Whistle Communications, Inc.
 * All rights reserved.
 *
 * Subject to the following obligations and disclaimer of warranty, use and
 * redistribution of this software, in source or object code forms, with or
 * without modifications are expressly permitted by Whistle Communications;
 * provided, however, that:
 * 1. Any and all reproductions of the source or object code must include the
 *    copyright notice above and the following disclaimer of warranties; and
 * 2. No rights are granted, in any manner or form, to use Whistle
 *    Communications, Inc. trademarks, including the mark "WHISTLE
 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
 *    such appears in the above copyright notice or in the software.
 *
 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * Copyright (c) 2000  Junichi SATOH <junichi@astec.co.jp>
 *                                   <junichi@junichi.org>
 * 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. 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
 *
 * Authors: Erik Salander <erik@whistle.com>
 *          Junichi SATOH <junichi@astec.co.jp>
 *                        <junichi@junichi.org>
 *
 * Based upon:
 * $FreeBSD: src/lib/libalias/alias_smedia.c,v 1.1.2.4 2001/03/05 03:48:00 kris Exp $
 */

/*
   Alias_smedia.c is meant to contain the aliasing code for streaming media
   protocols.  It performs special processing for RSTP sessions under TCP.
   Specifically, when a SETUP request is sent by a client, or a 200 reply
   is sent by a server, it is intercepted and modified.  The address is  
   changed to the gateway machine and an aliasing port is used.

   More specifically, the "client_port" configuration parameter is 
   parsed for SETUP requests.  The "server_port" configuration parameter is 
   parsed for 200 replies eminating from a server.  This is intended to handle
   the unicast case.

   RTSP also allows a redirection of a stream to another client by using the
   "destination" configuration parameter.  The destination config parm would
   indicate a different IP address.  This function is NOT supported by the 
   RTSP translation code below.

   The RTSP multicast functions without any address translation intervention.

   For this routine to work, the SETUP/200 must fit entirely
   into a single TCP packet.  This is typically the case, but exceptions
   can easily be envisioned under the actual specifications.

   Probably the most troubling aspect of the approach taken here is
   that the new SETUP/200 will typically be a different length, and
   this causes a certain amount of bookkeeping to keep track of the
   changes of sequence and acknowledgment numbers, since the client
   machine is totally unaware of the modification to the TCP stream.

   Initial version:  May, 2000 (eds)  
*/


#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>

#include "alias_local.h"

#define RTSP_CONTROL_PORT_NUMBER_1 554 
#define RTSP_CONTROL_PORT_NUMBER_2 7070 
#define RTSP_PORT_GROUP            2

#define ISDIGIT(a) (((a) >= '0') && ((a) <= '9'))

static int
search_string(char *data, int dlen, const char *search_str)
{
    int i, j, k;
    int search_str_len;

    search_str_len = strlen(search_str);
    for (i = 0; i < dlen - search_str_len; i++) {
	for (j = i, k = 0; j < dlen - search_str_len; j++, k++) {
	    if (data[j] != search_str[k] &&
		data[j] != search_str[k] - ('a' - 'A')) {
		break;
	    }
	    if (k == search_str_len - 1) {
		return j + 1;
	    }
	}
    }
    return -1;
}

static int
alias_rtsp_out(struct ip *pip,
		   struct alias_link *link,
		   char *data,
		   const char *port_str)
{
    int     hlen, tlen, dlen;
    struct tcphdr *tc;
    int     i, j, pos, state, port_dlen, new_dlen, delta;
    u_short p[2], new_len;
    u_short sport, eport, base_port;
    u_short salias = 0, ealias = 0, base_alias = 0;
    const char *transport_str = "transport:";
    char    newdata[2048], *port_data, *port_newdata, stemp[80];
    int     links_created = 0, pkt_updated = 0;
    struct alias_link *rtsp_link = NULL;
    struct in_addr null_addr; 
	
    /* Calculate data length of TCP packet */
    tc = (struct tcphdr *) ((char *) pip + (pip->ip_hl << 2));
    hlen = (pip->ip_hl + tc->th_off) << 2;
    tlen = ntohs(pip->ip_len);
    dlen = tlen - hlen;
	
	if (dlen > sizeof(newdata)) {
#if DEBUG
		fprintf(stderr, "alias_rtsp_out: data len too big");
#endif
		return -1;
	}
    /* Find keyword, "Transport: " */
    pos = search_string(data, dlen, transport_str);
    if (pos < 0) {
#if DEBUG
		fprintf(stderr, "alias_rtsp_out: Transport not found");
#endif
		return -1;
    }
	if (pos >= sizeof(newdata)) {
#if DEBUG
		fprintf(stderr, "alias_rtsp_out: Transport too far");
#endif
		return -1;
	}
    port_data = data + pos;
    port_dlen = dlen - pos;
	
    memcpy(newdata, data, pos);
    port_newdata = newdata + pos;
	
    while (port_dlen > strlen(port_str)) {
		/* Find keyword, appropriate port string */
		pos = search_string(port_data, port_dlen, port_str);
		if (pos < 0 || port_data + pos + 1 > newdata + sizeof(newdata)) {
#if DEBUG
			fprintf(stderr, "alias_rtsp_out: port_str too far\n");
#endif
			break;
		}
		
		memcpy (port_newdata, port_data, pos + 1);
		port_newdata += (pos + 1);
		
		p[0] = p[1] = 0;
		sport = eport = 0;
		state = 0;
		for (i = pos; i < port_dlen; i++) {
			switch(state) {
			case 0:
				if (port_data[i] == '=') {
					state++;
				}
				break;
			case 1:
				if (ISDIGIT(port_data[i])) {
					p[0] = p[0] * 10 + port_data[i] - '0';
				} else {
					if (port_data[i] == ';') {
						state = 3;
					}
					if (port_data[i] == '-') {
						state++;
					}
				}
				break;
			case 2:
				if (ISDIGIT(port_data[i])) {
					p[1] = p[1] * 10 + port_data[i] - '0';
				} else {
					state++;
				}
				break;
			case 3:
				base_port = p[0];
				sport = htons(p[0]);
				eport = htons(p[1]);
				
				if (!links_created) {
					
					links_created = 1; 
					/* Find an even numbered port number base that
					 satisfies the contiguous number of ports we need  */
					null_addr.s_addr = 0;
					if (0 == (salias = FindNewPortGroup(null_addr,
														FindAliasAddress(pip->ip_src),
														sport, 0, 
														RTSP_PORT_GROUP, 
														IPPROTO_UDP, 1))) {  
#ifdef DEBUG
						fprintf(stderr,
								"PacketAlias/RTSP: Cannot find contiguous RTSP data ports\n");
#endif
					} else {
						
						base_alias = ntohs(salias);
						for (j = 0; j < RTSP_PORT_GROUP; j++) {
							/* Establish link to port found in RTSP packet */
							rtsp_link = FindRtspOut(GetOriginalAddress(link), null_addr,
													htons(base_port + j), htons(base_alias + j),
													IPPROTO_UDP);
							if (rtsp_link != NULL) {
#ifndef NO_FW_PUNCH
								/* Punch hole in firewall */
								PunchFWHole(rtsp_link);
#endif
							} else {
#ifdef DEBUG
								fprintf(stderr,
										"PacketAlias/RTSP: Cannot allocate RTSP data ports\n");
#endif
								break;
							}
						}
					}
					ealias = htons(base_alias + (RTSP_PORT_GROUP - 1));
				}
				
				if (salias && rtsp_link) {
					size_t lentmp;
					
					/* Copy into IP packet */
					sprintf(stemp, "%d", ntohs(salias));
					lentmp = strlen(stemp);
					/* account for ending ';' */
					if (port_newdata + lentmp + 1 > newdata + sizeof(newdata)) {
#if DEBUG
						fprintf(stderr, "PacketAlias/RTSP: salias too far\n");
#endif
						break;
					}
					memcpy(port_newdata, stemp, lentmp);
					port_newdata += lentmp;
					
					if (eport != 0) {
						sprintf(stemp, "%d", ntohs(ealias));
						lentmp = strlen(stemp);

						/* account for middle '-' and for ending ';' */
						if (port_newdata + lentmp + 2 > newdata + sizeof(newdata)) {
#if DEBUG
							fprintf(stderr, "PacketAlias/RTSP: ealias too far\n");
#endif
							break;
						}
						*port_newdata = '-';
						port_newdata++;
						
						/* Copy into IP packet */
						memcpy(port_newdata, stemp, lentmp);
						port_newdata += lentmp;
					}
					pkt_updated = 1;
					
					*port_newdata = ';';
					port_newdata++;
				}
				state++;
				break;
			}
			if (state > 3) {
				break;
			}
		}
		port_data += i;
		port_dlen -= i;
    }
	
    if (!pkt_updated) {
#if DEBUG
		fprintf(stderr, "PacketAlias/RTSP: Packet not updated\n");
#endif
		return -1;
	}
	
    memcpy (port_newdata, port_data, port_dlen);
    port_newdata += port_dlen;
    *port_newdata = '\0';
	
    /* Create new packet */
    new_dlen = port_newdata - newdata;
    memcpy (data, newdata, new_dlen);
	
    SetAckModified(link);
    delta = GetDeltaSeqOut(pip, link);
    AddSeq(pip, link, delta + new_dlen - dlen);
	
    new_len = htons(hlen + new_dlen);
    DifferentialChecksum(&pip->ip_sum,
						 &new_len,
						 &pip->ip_len,
						 1);
    pip->ip_len = new_len;
	
    tc->th_sum = 0;
    tc->th_sum = TcpChecksum(pip);
	
    return 0;
}

/* Support the protocol used by early versions of RealPlayer */

static int
alias_pna_out(struct ip *pip,
		  struct alias_link *link,
		  char *data,
		  int dlen)
{
    struct alias_link *pna_links;
    u_short msg_id, msg_len;
    char    *work;
    u_short alias_port, port;
    struct  tcphdr *tc;

    work = data;
    work += 5;
    while (work + 4 < data + dlen) {
	memcpy(&msg_id, work, 2);
	work += 2;
	memcpy(&msg_len, work, 2);
	work += 2;
	if (ntohs(msg_id) == 0) {
	    /* end of options */
	    return 0;
	}
	if ((ntohs(msg_id) == 1) || (ntohs(msg_id) == 7)) {
	    memcpy(&port, work, 2);
	    pna_links = FindUdpTcpOut(pip->ip_src, GetDestAddress(link),
				      port, 0, IPPROTO_UDP, 1);
	    if (pna_links != NULL) {
#ifndef NO_FW_PUNCH
		/* Punch hole in firewall */
		PunchFWHole(pna_links);
#endif
		tc = (struct tcphdr *) ((char *) pip + (pip->ip_hl << 2));
		alias_port = GetAliasPort(pna_links);
		memcpy(work, &alias_port, 2);

		/* Compute TCP checksum for revised packet */
		tc->th_sum = 0;
		tc->th_sum = TcpChecksum(pip);
	    }
	}
	work += ntohs(msg_len);
    }
    
    return 0;
}

void
AliasHandleRtspOut(struct ip *pip, struct alias_link *link, int maxpacketsize)
{
    int    hlen, tlen, dlen;
    struct tcphdr *tc;
    char   *data;
    const  char *setup = "SETUP", *pna = "PNA", *str200 = "200";
    const  char *okstr = "OK", *client_port_str = "client_port";
    const  char *server_port_str = "server_port";
    int    i, parseOk;

    tc = (struct tcphdr *)((char *)pip + (pip->ip_hl << 2));
    hlen = (pip->ip_hl + tc->th_off) << 2;
    tlen = ntohs(pip->ip_len);
    dlen = tlen - hlen;

    data = (char*)pip;
    data += hlen;

    /* When aliasing a client, check for the SETUP request */
    if ((ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_1) || 
      (ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_2)) { 

      if (dlen >= strlen(setup)) {
        if (memcmp(data, setup, strlen(setup)) == 0) {
	    alias_rtsp_out(pip, link, data, client_port_str);
	    return;
	}
      }
      if (dlen >= strlen(pna)) {
	if (memcmp(data, pna, strlen(pna)) == 0) {
	    alias_pna_out(pip, link, data, dlen);
	}
      }

    } else {

      /* When aliasing a server, check for the 200 reply
         Accomodate varying number of blanks between 200 & OK */

      if (dlen >= strlen(str200)) {

        for (parseOk = 0, i = 0;         
             i <= dlen - strlen(str200);          
             i++) {
          if (memcmp(&data[i], str200, strlen(str200)) == 0) { 
            parseOk = 1; 
            break;
          }
        }
        if (parseOk) { 

          i += strlen(str200);        /* skip string found */ 
          while(data[i] == ' ')       /* skip blank(s) */
	    i++;
	
          if ((dlen - i) >= strlen(okstr)) {

            if (memcmp(&data[i], okstr, strlen(okstr)) == 0) 
              alias_rtsp_out(pip, link, data, server_port_str);

          }
        }
      }
    }
}
Commit	Line	Data
7ba0088d A	1	/*
	2	* Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
a2c93a76 A	6	* The contents of this file constitute Original Code as defined in and
	7	* are subject to the Apple Public Source License Version 1.1 (the
	8	* "License"). You may not use this file except in compliance with the
	9	* License. Please obtain a copy of the License at
	10	* http://www.apple.com/publicsource and read it before using this file.
7ba0088d	11	*
a2c93a76 A	12	* This Original Code and all software distributed under the License are
a2c93a76 A	13	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
7ba0088d A	14	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
7ba0088d A	15	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
a2c93a76 A	16	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	17	* License for the specific language governing rights and limitations
	18	* under the License.
7ba0088d A	19	*
	20	* @APPLE_LICENSE_HEADER_END@
	21	*/
	22	/*
	23	* alias_smedia.c
	24	*
	25	* Copyright (c) 2000 Whistle Communications, Inc.
	26	* All rights reserved.
	27	*
	28	* Subject to the following obligations and disclaimer of warranty, use and
	29	* redistribution of this software, in source or object code forms, with or
	30	* without modifications are expressly permitted by Whistle Communications;
	31	* provided, however, that:
	32	* 1. Any and all reproductions of the source or object code must include the
	33	* copyright notice above and the following disclaimer of warranties; and
	34	* 2. No rights are granted, in any manner or form, to use Whistle
	35	* Communications, Inc. trademarks, including the mark "WHISTLE
	36	* COMMUNICATIONS" on advertising, endorsements, or otherwise except as
	37	* such appears in the above copyright notice or in the software.
	38	*
	39	* THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
	40	* TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
	41	* REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
	42	* INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
	43	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
	44	* WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
	45	* REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
	46	* SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
	47	* IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
	48	* RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
	49	* WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
	50	* PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
	51	* SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
	52	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	53	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	54	* THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
	55	* OF SUCH DAMAGE.
	56	*
	57	* Copyright (c) 2000 Junichi SATOH <junichi@astec.co.jp>
	58	* <junichi@junichi.org>
	59	* All rights reserved.
	60	*
	61	* Redistribution and use in source and binary forms, with or without
	62	* modification, are permitted provided that the following conditions
	63	* are met:
	64	* 1. Redistributions of source code must retain the above copyright
	65	* notice, this list of conditions and the following disclaimer.
	66	* 2. Redistributions in binary form must reproduce the above copyright
	67	* notice, this list of conditions and the following disclaimer in the
	68	* documentation and/or other materials provided with the distribution.
	69	*
	70	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
	71	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	72	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	73	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	74	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	75	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	76	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	77	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	78	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	79	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	80	* SUCH DAMAGE.
	81	*
	82	* Authors: Erik Salander <erik@whistle.com>
83	* Junichi SATOH <junichi@astec.co.jp>
84	* <junichi@junichi.org>
85	*
86	* Based upon:
87	* $FreeBSD: src/lib/libalias/alias_smedia.c,v 1.1.2.4 2001/03/05 03:48:00 kris Exp $
88	*/
89
90	/*
91	Alias_smedia.c is meant to contain the aliasing code for streaming media
92	protocols. It performs special processing for RSTP sessions under TCP.
93	Specifically, when a SETUP request is sent by a client, or a 200 reply
94	is sent by a server, it is intercepted and modified. The address is
95	changed to the gateway machine and an aliasing port is used.
96
97	More specifically, the "client_port" configuration parameter is
98	parsed for SETUP requests. The "server_port" configuration parameter is
99	parsed for 200 replies eminating from a server. This is intended to handle
100	the unicast case.
101
102	RTSP also allows a redirection of a stream to another client by using the
103	"destination" configuration parameter. The destination config parm would
104	indicate a different IP address. This function is NOT supported by the
105	RTSP translation code below.
106
107	The RTSP multicast functions without any address translation intervention.
108
109	For this routine to work, the SETUP/200 must fit entirely
110	into a single TCP packet. This is typically the case, but exceptions
111	can easily be envisioned under the actual specifications.
112
113	Probably the most troubling aspect of the approach taken here is
114	that the new SETUP/200 will typically be a different length, and
115	this causes a certain amount of bookkeeping to keep track of the
116	changes of sequence and acknowledgment numbers, since the client
117	machine is totally unaware of the modification to the TCP stream.
118
119	Initial version: May, 2000 (eds)
120	*/
121
cc98826e	122
7ba0088d A	123	#include <stdio.h>
	124	#include <string.h>
	125	#include <sys/types.h>
	126	#include <netinet/in_systm.h>
	127	#include <netinet/in.h>
	128	#include <netinet/ip.h>
	129	#include <netinet/tcp.h>
	130	#include <netinet/udp.h>
	131
	132	#include "alias_local.h"
	133
	134	#define RTSP_CONTROL_PORT_NUMBER_1 554
	135	#define RTSP_CONTROL_PORT_NUMBER_2 7070
	136	#define RTSP_PORT_GROUP 2
	137
	138	#define ISDIGIT(a) (((a) >= '0') && ((a) <= '9'))
	139
	140	static int
	141	search_string(char data, int dlen, const char search_str)
	142	{
	143	int i, j, k;
	144	int search_str_len;
	145
	146	search_str_len = strlen(search_str);
	147	for (i = 0; i < dlen - search_str_len; i++) {
	148	for (j = i, k = 0; j < dlen - search_str_len; j++, k++) {
	149	if (data[j] != search_str[k] &&
	150	data[j] != search_str[k] - ('a' - 'A')) {
	151	break;
	152	}
	153	if (k == search_str_len - 1) {
	154	return j + 1;
	155	}
	156	}
	157	}
	158	return -1;
	159	}
	160
	161	static int
	162	alias_rtsp_out(struct ip *pip,
	163	struct alias_link *link,
	164	char *data,
	165	const char *port_str)
	166	{
	167	int hlen, tlen, dlen;
	168	struct tcphdr *tc;
	169	int i, j, pos, state, port_dlen, new_dlen, delta;
	170	u_short p[2], new_len;
	171	u_short sport, eport, base_port;
	172	u_short salias = 0, ealias = 0, base_alias = 0;
	173	const char *transport_str = "transport:";
	174	char newdata[2048], port_data, port_newdata, stemp[80];
	175	int links_created = 0, pkt_updated = 0;
	176	struct alias_link *rtsp_link = NULL;
	177	struct in_addr null_addr;
cc98826e	178
7ba0088d A	179	/* Calculate data length of TCP packet */
	180	tc = (struct tcphdr ) ((char ) pip + (pip->ip_hl << 2));
	181	hlen = (pip->ip_hl + tc->th_off) << 2;
	182	tlen = ntohs(pip->ip_len);
	183	dlen = tlen - hlen;
cc98826e A	184
	185	if (dlen > sizeof(newdata)) {
	186	#if DEBUG
	187	fprintf(stderr, "alias_rtsp_out: data len too big");
	188	#endif
	189	return -1;
	190	}
7ba0088d A	191	/* Find keyword, "Transport: " */
	192	pos = search_string(data, dlen, transport_str);
	193	if (pos < 0) {
cc98826e A	194	#if DEBUG
	195	fprintf(stderr, "alias_rtsp_out: Transport not found");
	196	#endif
	197	return -1;
7ba0088d	198	}
cc98826e A	199	if (pos >= sizeof(newdata)) {
	200	#if DEBUG
	201	fprintf(stderr, "alias_rtsp_out: Transport too far");
	202	#endif
	203	return -1;
	204	}
7ba0088d A	205	port_data = data + pos;
7ba0088d A	206	port_dlen = dlen - pos;
cc98826e	207
7ba0088d A	208	memcpy(newdata, data, pos);
7ba0088d A	209	port_newdata = newdata + pos;
cc98826e	210
7ba0088d	211	while (port_dlen > strlen(port_str)) {
cc98826e A	212	/* Find keyword, appropriate port string */
	213	pos = search_string(port_data, port_dlen, port_str);
	214	if (pos < 0 \|\| port_data + pos + 1 > newdata + sizeof(newdata)) {
	215	#if DEBUG
	216	fprintf(stderr, "alias_rtsp_out: port_str too far\n");
	217	#endif
	218	break;
7ba0088d	219	}
cc98826e A	220
	221	memcpy (port_newdata, port_data, pos + 1);
	222	port_newdata += (pos + 1);
	223
	224	p[0] = p[1] = 0;
	225	sport = eport = 0;
	226	state = 0;
	227	for (i = pos; i < port_dlen; i++) {
	228	switch(state) {
	229	case 0:
	230	if (port_data[i] == '=') {
	231	state++;
	232	}
	233	break;
	234	case 1:
	235	if (ISDIGIT(port_data[i])) {
	236	p[0] = p[0] * 10 + port_data[i] - '0';
	237	} else {
	238	if (port_data[i] == ';') {
	239	state = 3;
	240	}
	241	if (port_data[i] == '-') {
	242	state++;
	243	}
	244	}
	245	break;
	246	case 2:
	247	if (ISDIGIT(port_data[i])) {
	248	p[1] = p[1] * 10 + port_data[i] - '0';
	249	} else {
	250	state++;
	251	}
	252	break;
	253	case 3:
	254	base_port = p[0];
	255	sport = htons(p[0]);
	256	eport = htons(p[1]);
	257
	258	if (!links_created) {
	259
	260	links_created = 1;
	261	/* Find an even numbered port number base that
	262	satisfies the contiguous number of ports we need */
	263	null_addr.s_addr = 0;
	264	if (0 == (salias = FindNewPortGroup(null_addr,
	265	FindAliasAddress(pip->ip_src),
	266	sport, 0,
	267	RTSP_PORT_GROUP,
	268	IPPROTO_UDP, 1))) {
7ba0088d	269	#ifdef DEBUG
cc98826e A	270	fprintf(stderr,
cc98826e A	271	"PacketAlias/RTSP: Cannot find contiguous RTSP data ports\n");
7ba0088d	272	#endif
cc98826e A	273	} else {
	274
	275	base_alias = ntohs(salias);
	276	for (j = 0; j < RTSP_PORT_GROUP; j++) {
	277	/* Establish link to port found in RTSP packet */
	278	rtsp_link = FindRtspOut(GetOriginalAddress(link), null_addr,
	279	htons(base_port + j), htons(base_alias + j),
	280	IPPROTO_UDP);
	281	if (rtsp_link != NULL) {
7ba0088d	282	#ifndef NO_FW_PUNCH
cc98826e A	283	/* Punch hole in firewall */
cc98826e A	284	PunchFWHole(rtsp_link);
7ba0088d	285	#endif
cc98826e	286	} else {
7ba0088d	287	#ifdef DEBUG
cc98826e A	288	fprintf(stderr,
cc98826e A	289	"PacketAlias/RTSP: Cannot allocate RTSP data ports\n");
7ba0088d	290	#endif
cc98826e A	291	break;
	292	}
	293	}
	294	}
	295	ealias = htons(base_alias + (RTSP_PORT_GROUP - 1));
	296	}
	297
	298	if (salias && rtsp_link) {
	299	size_t lentmp;
	300
	301	/* Copy into IP packet */
	302	sprintf(stemp, "%d", ntohs(salias));
	303	lentmp = strlen(stemp);
	304	/* account for ending ';' */
	305	if (port_newdata + lentmp + 1 > newdata + sizeof(newdata)) {
	306	#if DEBUG
	307	fprintf(stderr, "PacketAlias/RTSP: salias too far\n");
	308	#endif
	309	break;
	310	}
	311	memcpy(port_newdata, stemp, lentmp);
	312	port_newdata += lentmp;
	313
	314	if (eport != 0) {
	315	sprintf(stemp, "%d", ntohs(ealias));
	316	lentmp = strlen(stemp);
	317
	318	/* account for middle '-' and for ending ';' */
	319	if (port_newdata + lentmp + 2 > newdata + sizeof(newdata)) {
	320	#if DEBUG
	321	fprintf(stderr, "PacketAlias/RTSP: ealias too far\n");
	322	#endif
	323	break;
	324	}
	325	*port_newdata = '-';
	326	port_newdata++;
	327
	328	/* Copy into IP packet */
	329	memcpy(port_newdata, stemp, lentmp);
	330	port_newdata += lentmp;
	331	}
	332	pkt_updated = 1;
	333
	334	*port_newdata = ';';
	335	port_newdata++;
	336	}
	337	state++;
	338	break;
	339	}
	340	if (state > 3) {
	341	break;
	342	}
7ba0088d	343	}
cc98826e A	344	port_data += i;
cc98826e A	345	port_dlen -= i;
7ba0088d	346	}
cc98826e A	347
	348	if (!pkt_updated) {
	349	#if DEBUG
	350	fprintf(stderr, "PacketAlias/RTSP: Packet not updated\n");
	351	#endif
	352	return -1;
	353	}
	354
7ba0088d A	355	memcpy (port_newdata, port_data, port_dlen);
	356	port_newdata += port_dlen;
	357	*port_newdata = '\0';
cc98826e	358
7ba0088d A	359	/* Create new packet */
	360	new_dlen = port_newdata - newdata;
	361	memcpy (data, newdata, new_dlen);
cc98826e	362
7ba0088d A	363	SetAckModified(link);
	364	delta = GetDeltaSeqOut(pip, link);
	365	AddSeq(pip, link, delta + new_dlen - dlen);
cc98826e	366
7ba0088d A	367	new_len = htons(hlen + new_dlen);
7ba0088d A	368	DifferentialChecksum(&pip->ip_sum,
cc98826e A	369	&new_len,
	370	&pip->ip_len,
	371	1);
7ba0088d	372	pip->ip_len = new_len;
cc98826e	373
7ba0088d A	374	tc->th_sum = 0;
7ba0088d A	375	tc->th_sum = TcpChecksum(pip);
cc98826e	376
7ba0088d A	377	return 0;
	378	}
	379
	380	/* Support the protocol used by early versions of RealPlayer */
	381
	382	static int
	383	alias_pna_out(struct ip *pip,
	384	struct alias_link *link,
	385	char *data,
	386	int dlen)
	387	{
	388	struct alias_link *pna_links;
	389	u_short msg_id, msg_len;
	390	char *work;
	391	u_short alias_port, port;
	392	struct tcphdr *tc;
	393
	394	work = data;
	395	work += 5;
	396	while (work + 4 < data + dlen) {
	397	memcpy(&msg_id, work, 2);
	398	work += 2;
	399	memcpy(&msg_len, work, 2);
	400	work += 2;
	401	if (ntohs(msg_id) == 0) {
	402	/* end of options */
	403	return 0;
	404	}
	405	if ((ntohs(msg_id) == 1) \|\| (ntohs(msg_id) == 7)) {
	406	memcpy(&port, work, 2);
	407	pna_links = FindUdpTcpOut(pip->ip_src, GetDestAddress(link),
	408	port, 0, IPPROTO_UDP, 1);
	409	if (pna_links != NULL) {
	410	#ifndef NO_FW_PUNCH
	411	/* Punch hole in firewall */
	412	PunchFWHole(pna_links);
	413	#endif
	414	tc = (struct tcphdr ) ((char ) pip + (pip->ip_hl << 2));
	415	alias_port = GetAliasPort(pna_links);
	416	memcpy(work, &alias_port, 2);
	417
	418	/* Compute TCP checksum for revised packet */
	419	tc->th_sum = 0;
	420	tc->th_sum = TcpChecksum(pip);
	421	}
	422	}
	423	work += ntohs(msg_len);
	424	}
	425
	426	return 0;
	427	}
	428
	429	void
	430	AliasHandleRtspOut(struct ip pip, struct alias_link link, int maxpacketsize)
	431	{
	432	int hlen, tlen, dlen;
	433	struct tcphdr *tc;
	434	char *data;
	435	const char setup = "SETUP", pna = "PNA", *str200 = "200";
	436	const char okstr = "OK", client_port_str = "client_port";
	437	const char *server_port_str = "server_port";
	438	int i, parseOk;
	439
	440	tc = (struct tcphdr )((char )pip + (pip->ip_hl << 2));
441	hlen = (pip->ip_hl + tc->th_off) << 2;
442	tlen = ntohs(pip->ip_len);
443	dlen = tlen - hlen;
444
445	data = (char*)pip;
446	data += hlen;
447
448	/* When aliasing a client, check for the SETUP request */
449	if ((ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_1) \|\|
450	(ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_2)) {
451
452	if (dlen >= strlen(setup)) {
453	if (memcmp(data, setup, strlen(setup)) == 0) {
454	alias_rtsp_out(pip, link, data, client_port_str);
455	return;
456	}
457	}
458	if (dlen >= strlen(pna)) {
459	if (memcmp(data, pna, strlen(pna)) == 0) {
460	alias_pna_out(pip, link, data, dlen);
461	}
462	}
463
464	} else {
465
466	/* When aliasing a server, check for the 200 reply
467	Accomodate varying number of blanks between 200 & OK */
468
469	if (dlen >= strlen(str200)) {
470
471	for (parseOk = 0, i = 0;
472	i <= dlen - strlen(str200);
473	i++) {
474	if (memcmp(&data[i], str200, strlen(str200)) == 0) {
475	parseOk = 1;
476	break;
477	}
478	}
479	if (parseOk) {
480
481	i += strlen(str200); /* skip string found */
482	while(data[i] == ' ') /* skip blank(s) */
483	i++;
484
485	if ((dlen - i) >= strlen(okstr)) {
486
487	if (memcmp(&data[i], okstr, strlen(okstr)) == 0)
488	alias_rtsp_out(pip, link, data, server_port_str);
489
490	}
491	}
492	}
493	}
494	}