4 * Copyright (c) 2000 Whistle Communications, Inc.
7 * Subject to the following obligations and disclaimer of warranty, use and
8 * redistribution of this software, in source or object code forms, with or
9 * without modifications are expressly permitted by Whistle Communications;
10 * provided, however, that:
11 * 1. Any and all reproductions of the source or object code must include the
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13 * 2. No rights are granted, in any manner or form, to use Whistle
14 * Communications, Inc. trademarks, including the mark "WHISTLE
15 * COMMUNICATIONS" on advertising, endorsements, or otherwise except as
16 * such appears in the above copyright notice or in the software.
18 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
19 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
20 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
21 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
22 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
23 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
24 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
25 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
26 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
27 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
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29 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
30 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
31 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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33 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
36 * Copyright (c) 2000 Junichi SATOH <junichi@astec.co.jp>
37 * <junichi@junichi.org>
38 * All rights reserved.
40 * Redistribution and use in source and binary forms, with or without
41 * modification, are permitted provided that the following conditions
43 * 1. Redistributions of source code must retain the above copyright
44 * notice, this list of conditions and the following disclaimer.
45 * 2. Redistributions in binary form must reproduce the above copyright
46 * notice, this list of conditions and the following disclaimer in the
47 * documentation and/or other materials provided with the distribution.
49 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
50 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
53 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
61 * Authors: Erik Salander <erik@whistle.com>
62 * Junichi SATOH <junichi@astec.co.jp>
63 * <junichi@junichi.org>
66 #include <sys/cdefs.h>
67 __FBSDID("$FreeBSD$");
70 Alias_smedia.c is meant to contain the aliasing code for streaming media
71 protocols. It performs special processing for RSTP sessions under TCP.
72 Specifically, when a SETUP request is sent by a client, or a 200 reply
73 is sent by a server, it is intercepted and modified. The address is
74 changed to the gateway machine and an aliasing port is used.
76 More specifically, the "client_port" configuration parameter is
77 parsed for SETUP requests. The "server_port" configuration parameter is
78 parsed for 200 replies eminating from a server. This is intended to handle
81 RTSP also allows a redirection of a stream to another client by using the
82 "destination" configuration parameter. The destination config parm would
83 indicate a different IP address. This function is NOT supported by the
84 RTSP translation code below.
86 The RTSP multicast functions without any address translation intervention.
88 For this routine to work, the SETUP/200 must fit entirely
89 into a single TCP packet. This is typically the case, but exceptions
90 can easily be envisioned under the actual specifications.
92 Probably the most troubling aspect of the approach taken here is
93 that the new SETUP/200 will typically be a different length, and
94 this causes a certain amount of bookkeeping to keep track of the
95 changes of sequence and acknowledgment numbers, since the client
96 machine is totally unaware of the modification to the TCP stream.
98 Initial version: May, 2000 (eds)
102 #include <sys/param.h>
103 #include <sys/libkern.h>
105 #include <sys/types.h>
110 #include <netinet/in_systm.h>
111 #include <netinet/in.h>
112 #include <netinet/ip.h>
113 #include <netinet/tcp.h>
114 #include <netinet/udp.h>
117 #include <netinet/libalias/alias.h>
118 #include <netinet/libalias/alias_local.h>
120 #include "alias_local.h"
123 #define RTSP_CONTROL_PORT_NUMBER_1 554
124 #define RTSP_CONTROL_PORT_NUMBER_2 7070
125 #define RTSP_PORT_GROUP 2
127 #define ISDIGIT(a) (((a) >= '0') && ((a) <= '9'))
130 search_string(char *data, int dlen, const char *search_str)
135 search_str_len = strlen(search_str);
136 for (i = 0; i < dlen - search_str_len; i++) {
137 for (j = i, k = 0; j < dlen - search_str_len; j++, k++) {
138 if (data[j] != search_str[k] &&
139 data[j] != search_str[k] - ('a' - 'A')) {
142 if (k == search_str_len - 1) {
151 alias_rtsp_out(struct libalias *la, struct ip *pip,
152 struct alias_link *lnk,
154 const char *port_str)
156 int hlen, tlen, dlen;
158 int i, j, pos, state, port_dlen, new_dlen, delta;
159 u_short p[2], new_len;
160 u_short sport, eport, base_port;
161 u_short salias = 0, ealias = 0, base_alias = 0;
162 const char *transport_str = "transport:";
163 char newdata[2048], *port_data, *port_newdata, stemp[80];
164 int links_created = 0, pkt_updated = 0;
165 struct alias_link *rtsp_lnk = NULL;
166 struct in_addr null_addr;
168 /* Calculate data length of TCP packet */
169 tc = (struct tcphdr *)ip_next(pip);
170 hlen = (pip->ip_hl + tc->th_off) << 2;
171 tlen = ntohs(pip->ip_len);
174 /* Find keyword, "Transport: " */
175 pos = search_string(data, dlen, transport_str);
179 port_data = data + pos;
180 port_dlen = dlen - pos;
182 memcpy(newdata, data, pos);
183 port_newdata = newdata + pos;
185 while (port_dlen > (int)strlen(port_str)) {
186 /* Find keyword, appropriate port string */
187 pos = search_string(port_data, port_dlen, port_str);
191 memcpy(port_newdata, port_data, pos + 1);
192 port_newdata += (pos + 1);
197 for (i = pos; i < port_dlen; i++) {
200 if (port_data[i] == '=') {
205 if (ISDIGIT(port_data[i])) {
206 p[0] = p[0] * 10 + port_data[i] - '0';
208 if (port_data[i] == ';') {
211 if (port_data[i] == '-') {
217 if (ISDIGIT(port_data[i])) {
218 p[1] = p[1] * 10 + port_data[i] - '0';
228 if (!links_created) {
232 * Find an even numbered port
233 * number base that satisfies the
234 * contiguous number of ports we
237 null_addr.s_addr = 0;
238 if (0 == (salias = FindNewPortGroup(la, null_addr,
239 FindAliasAddress(la, pip->ip_src),
243 #ifdef LIBALIAS_DEBUG
245 "PacketAlias/RTSP: Cannot find contiguous RTSP data ports\n");
249 base_alias = ntohs(salias);
250 for (j = 0; j < RTSP_PORT_GROUP; j++) {
256 rtsp_lnk = FindRtspOut(la, GetOriginalAddress(lnk), null_addr,
257 htons(base_port + j), htons(base_alias + j),
259 if (rtsp_lnk != NULL) {
266 PunchFWHole(rtsp_lnk);
269 #ifdef LIBALIAS_DEBUG
271 "PacketAlias/RTSP: Cannot allocate RTSP data ports\n");
277 ealias = htons(base_alias + (RTSP_PORT_GROUP - 1));
279 if (salias && rtsp_lnk) {
283 /* Copy into IP packet */
284 sprintf(stemp, "%d", ntohs(salias));
285 memcpy(port_newdata, stemp, strlen(stemp));
286 port_newdata += strlen(stemp);
292 /* Copy into IP packet */
293 sprintf(stemp, "%d", ntohs(ealias));
294 memcpy(port_newdata, stemp, strlen(stemp));
295 port_newdata += strlen(stemp);
314 memcpy(port_newdata, port_data, port_dlen);
315 port_newdata += port_dlen;
316 *port_newdata = '\0';
318 /* Create new packet */
319 new_dlen = port_newdata - newdata;
320 memcpy(data, newdata, new_dlen);
323 delta = GetDeltaSeqOut(pip, lnk);
324 AddSeq(pip, lnk, delta + new_dlen - dlen);
326 new_len = htons(hlen + new_dlen);
327 DifferentialChecksum(&pip->ip_sum,
331 pip->ip_len = new_len;
337 tc->th_sum = TcpChecksum(pip);
342 /* Support the protocol used by early versions of RealPlayer */
345 alias_pna_out(struct libalias *la, struct ip *pip,
346 struct alias_link *lnk,
350 struct alias_link *pna_links;
351 u_short msg_id, msg_len;
353 u_short alias_port, port;
358 while (work + 4 < data + dlen) {
359 memcpy(&msg_id, work, 2);
361 memcpy(&msg_len, work, 2);
363 if (ntohs(msg_id) == 0) {
367 if ((ntohs(msg_id) == 1) || (ntohs(msg_id) == 7)) {
368 memcpy(&port, work, 2);
369 pna_links = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(lnk),
370 port, 0, IPPROTO_UDP, 1);
371 if (pna_links != NULL) {
373 /* Punch hole in firewall */
374 PunchFWHole(pna_links);
376 tc = (struct tcphdr *)ip_next(pip);
377 alias_port = GetAliasPort(pna_links);
378 memcpy(work, &alias_port, 2);
380 /* Compute TCP checksum for revised packet */
385 tc->th_sum = TcpChecksum(pip);
389 work += ntohs(msg_len);
396 AliasHandleRtspOut(struct libalias *la, struct ip *pip, struct alias_link *lnk, int maxpacketsize)
398 int hlen, tlen, dlen;
401 const char *setup = "SETUP", *pna = "PNA", *str200 = "200";
402 const char *okstr = "OK", *client_port_str = "client_port";
403 const char *server_port_str = "server_port";
408 tc = (struct tcphdr *)ip_next(pip);
409 hlen = (pip->ip_hl + tc->th_off) << 2;
410 tlen = ntohs(pip->ip_len);
416 /* When aliasing a client, check for the SETUP request */
417 if ((ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_1) ||
418 (ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_2)) {
420 if (dlen >= (int)strlen(setup)) {
421 if (memcmp(data, setup, strlen(setup)) == 0) {
422 alias_rtsp_out(la, pip, lnk, data, client_port_str);
426 if (dlen >= (int)strlen(pna)) {
427 if (memcmp(data, pna, strlen(pna)) == 0) {
428 alias_pna_out(la, pip, lnk, data, dlen);
434 * When aliasing a server, check for the 200 reply
435 * Accomodate varying number of blanks between 200 & OK
438 if (dlen >= (int)strlen(str200)) {
440 for (parseOk = 0, i = 0;
441 i <= dlen - (int)strlen(str200);
443 if (memcmp(&data[i], str200, strlen(str200)) == 0) {
450 i += strlen(str200); /* skip string found */
451 while (data[i] == ' ') /* skip blank(s) */
454 if ((dlen - i) >= (int)strlen(okstr)) {
456 if (memcmp(&data[i], okstr, strlen(okstr)) == 0)
457 alias_rtsp_out(la, pip, lnk, data, server_port_str);