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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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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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)
103 #include <sys/types.h>
104 #include <netinet/in_systm.h>
105 #include <netinet/in.h>
106 #include <netinet/ip.h>
107 #include <netinet/tcp.h>
108 #include <netinet/udp.h>
110 #include "alias_local.h"
112 #define RTSP_CONTROL_PORT_NUMBER_1 554
113 #define RTSP_CONTROL_PORT_NUMBER_2 7070
114 #define RTSP_PORT_GROUP 2
116 #define ISDIGIT(a) (((a) >= '0') && ((a) <= '9'))
119 search_string(char *data, int dlen, const char *search_str)
124 search_str_len = strlen(search_str);
125 for (i = 0; i < dlen - search_str_len; i++) {
126 for (j = i, k = 0; j < dlen - search_str_len; j++, k++) {
127 if (data[j] != search_str[k] &&
128 data[j] != search_str[k] - ('a' - 'A')) {
131 if (k == search_str_len - 1) {
140 alias_rtsp_out(struct libalias *la, struct ip *pip,
141 struct alias_link *lnk,
143 const char *port_str)
145 int hlen, tlen, dlen;
147 int i, j, pos, state, port_dlen, new_dlen, delta;
148 u_short p[2], new_len;
149 u_short sport, eport, base_port;
150 u_short salias = 0, ealias = 0, base_alias = 0;
151 const char *transport_str = "transport:";
152 char newdata[2048], *port_data, *port_newdata, stemp[80];
153 int links_created = 0, pkt_updated = 0;
154 struct alias_link *rtsp_lnk = NULL;
155 struct in_addr null_addr;
157 /* Calculate data length of TCP packet */
158 tc = (struct tcphdr *)ip_next(pip);
159 hlen = (pip->ip_hl + tc->th_off) << 2;
160 tlen = ntohs(pip->ip_len);
163 /* Find keyword, "Transport: " */
164 pos = search_string(data, dlen, transport_str);
168 port_data = data + pos;
169 port_dlen = dlen - pos;
171 memcpy(newdata, data, pos);
172 port_newdata = newdata + pos;
174 while (port_dlen > (int)strlen(port_str)) {
175 /* Find keyword, appropriate port string */
176 pos = search_string(port_data, port_dlen, port_str);
180 memcpy(port_newdata, port_data, pos + 1);
181 port_newdata += (pos + 1);
186 for (i = pos; i < port_dlen; i++) {
189 if (port_data[i] == '=') {
194 if (ISDIGIT(port_data[i])) {
195 p[0] = p[0] * 10 + port_data[i] - '0';
197 if (port_data[i] == ';') {
200 if (port_data[i] == '-') {
206 if (ISDIGIT(port_data[i])) {
207 p[1] = p[1] * 10 + port_data[i] - '0';
217 if (!links_created) {
221 * Find an even numbered port
222 * number base that satisfies the
223 * contiguous number of ports we
226 null_addr.s_addr = 0;
227 if (0 == (salias = FindNewPortGroup(la, null_addr,
228 FindAliasAddress(la, pip->ip_src),
234 "PacketAlias/RTSP: Cannot find contiguous RTSP data ports\n");
238 base_alias = ntohs(salias);
239 for (j = 0; j < RTSP_PORT_GROUP; j++) {
245 rtsp_lnk = FindRtspOut(la, GetOriginalAddress(lnk), null_addr,
246 htons(base_port + j), htons(base_alias + j),
248 if (rtsp_lnk != NULL) {
255 PunchFWHole(rtsp_lnk);
260 "PacketAlias/RTSP: Cannot allocate RTSP data ports\n");
266 ealias = htons(base_alias + (RTSP_PORT_GROUP - 1));
268 if (salias && rtsp_lnk) {
272 /* Copy into IP packet */
273 sprintf(stemp, "%d", ntohs(salias));
274 memcpy(port_newdata, stemp, strlen(stemp));
275 port_newdata += strlen(stemp);
281 /* Copy into IP packet */
282 sprintf(stemp, "%d", ntohs(ealias));
283 memcpy(port_newdata, stemp, strlen(stemp));
284 port_newdata += strlen(stemp);
303 memcpy(port_newdata, port_data, port_dlen);
304 port_newdata += port_dlen;
305 *port_newdata = '\0';
307 /* Create new packet */
308 new_dlen = port_newdata - newdata;
309 memcpy(data, newdata, new_dlen);
312 delta = GetDeltaSeqOut(pip, lnk);
313 AddSeq(pip, lnk, delta + new_dlen - dlen);
315 new_len = htons(hlen + new_dlen);
316 DifferentialChecksum(&pip->ip_sum,
320 pip->ip_len = new_len;
323 tc->th_sum = TcpChecksum(pip);
328 /* Support the protocol used by early versions of RealPlayer */
331 alias_pna_out(struct libalias *la, struct ip *pip,
332 struct alias_link *lnk,
336 struct alias_link *pna_links;
337 u_short msg_id, msg_len;
339 u_short alias_port, port;
344 while (work + 4 < data + dlen) {
345 memcpy(&msg_id, work, 2);
347 memcpy(&msg_len, work, 2);
349 if (ntohs(msg_id) == 0) {
353 if ((ntohs(msg_id) == 1) || (ntohs(msg_id) == 7)) {
354 memcpy(&port, work, 2);
355 pna_links = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(lnk),
356 port, 0, IPPROTO_UDP, 1);
357 if (pna_links != NULL) {
359 /* Punch hole in firewall */
360 PunchFWHole(pna_links);
362 tc = (struct tcphdr *)ip_next(pip);
363 alias_port = GetAliasPort(pna_links);
364 memcpy(work, &alias_port, 2);
366 /* Compute TCP checksum for revised packet */
368 tc->th_sum = TcpChecksum(pip);
371 work += ntohs(msg_len);
378 AliasHandleRtspOut(struct libalias *la, struct ip *pip, struct alias_link *lnk, int maxpacketsize)
380 int hlen, tlen, dlen;
383 const char *setup = "SETUP", *pna = "PNA", *str200 = "200";
384 const char *okstr = "OK", *client_port_str = "client_port";
385 const char *server_port_str = "server_port";
390 tc = (struct tcphdr *)ip_next(pip);
391 hlen = (pip->ip_hl + tc->th_off) << 2;
392 tlen = ntohs(pip->ip_len);
398 /* When aliasing a client, check for the SETUP request */
399 if ((ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_1) ||
400 (ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_2)) {
402 if (dlen >= (int)strlen(setup)) {
403 if (memcmp(data, setup, strlen(setup)) == 0) {
404 alias_rtsp_out(la, pip, lnk, data, client_port_str);
408 if (dlen >= (int)strlen(pna)) {
409 if (memcmp(data, pna, strlen(pna)) == 0) {
410 alias_pna_out(la, pip, lnk, data, dlen);
416 * When aliasing a server, check for the 200 reply
417 * Accomodate varying number of blanks between 200 & OK
420 if (dlen >= (int)strlen(str200)) {
422 for (parseOk = 0, i = 0;
423 i <= dlen - (int)strlen(str200);
425 if (memcmp(&data[i], str200, strlen(str200)) == 0) {
432 i += strlen(str200); /* skip string found */
433 while (data[i] == ' ') /* skip blank(s) */
436 if ((dlen - i) >= (int)strlen(okstr)) {
438 if (memcmp(&data[i], okstr, strlen(okstr)) == 0)
439 alias_rtsp_out(la, pip, lnk, data, server_port_str);