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
12 * copyright notice above and the following disclaimer of warranties; and
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
28 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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: src/sys/netinet/libalias/alias_smedia.c,v 1.17.6.1 2008/11/25 02:59:29 kensmith Exp $");
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/systm.h>
104 #include <sys/kernel.h>
105 #include <sys/module.h>
108 #include <sys/types.h>
113 #include <netinet/in_systm.h>
114 #include <netinet/in.h>
115 #include <netinet/ip.h>
116 #include <netinet/tcp.h>
119 #include <netinet/libalias/alias.h>
120 #include <netinet/libalias/alias_local.h>
121 #include <netinet/libalias/alias_mod.h>
123 #include "alias_local.h"
124 #include "alias_mod.h"
127 #define RTSP_CONTROL_PORT_NUMBER_1 554
128 #define RTSP_CONTROL_PORT_NUMBER_2 7070
129 #define TFTP_PORT_NUMBER 69
132 AliasHandleRtspOut(struct libalias *, struct ip *, struct alias_link *,
135 fingerprint(struct libalias *la, struct ip *pip, struct alias_data *ah)
138 if (ah->dport != NULL && ah->aport != NULL && ah->sport != NULL &&
139 ntohs(*ah->dport) == TFTP_PORT_NUMBER)
141 if (ah->dport == NULL || ah->sport == NULL || ah->lnk == NULL ||
144 if (ntohs(*ah->dport) == RTSP_CONTROL_PORT_NUMBER_1
145 || ntohs(*ah->sport) == RTSP_CONTROL_PORT_NUMBER_1
146 || ntohs(*ah->dport) == RTSP_CONTROL_PORT_NUMBER_2
147 || ntohs(*ah->sport) == RTSP_CONTROL_PORT_NUMBER_2)
153 protohandler(struct libalias *la, struct ip *pip, struct alias_data *ah)
156 if (ntohs(*ah->dport) == TFTP_PORT_NUMBER)
157 FindRtspOut(la, pip->ip_src, pip->ip_dst,
158 *ah->sport, *ah->aport, IPPROTO_UDP);
159 else AliasHandleRtspOut(la, pip, ah->lnk, ah->maxpktsize);
163 struct proto_handler handlers[] = {
168 .fingerprint = &fingerprint,
169 .protohandler = &protohandler
175 mod_handler(module_t mod, int type, void *data)
182 LibAliasAttachHandlers(handlers);
186 LibAliasDetachHandlers(handlers);
197 moduledata_t alias_mod = {
198 "alias_smedia", mod_handler, NULL
202 DECLARE_MODULE(alias_smedia, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND);
203 MODULE_VERSION(alias_smedia, 1);
204 MODULE_DEPEND(alias_smedia, libalias, 1, 1, 1);
207 #define RTSP_CONTROL_PORT_NUMBER_1 554
208 #define RTSP_CONTROL_PORT_NUMBER_2 7070
209 #define RTSP_PORT_GROUP 2
211 #define ISDIGIT(a) (((a) >= '0') && ((a) <= '9'))
214 search_string(char *data, int dlen, const char *search_str)
219 search_str_len = strlen(search_str);
220 for (i = 0; i < dlen - search_str_len; i++) {
221 for (j = i, k = 0; j < dlen - search_str_len; j++, k++) {
222 if (data[j] != search_str[k] &&
223 data[j] != search_str[k] - ('a' - 'A')) {
226 if (k == search_str_len - 1) {
235 alias_rtsp_out(struct libalias *la, struct ip *pip,
236 struct alias_link *lnk,
238 const char *port_str)
240 int hlen, tlen, dlen;
242 int i, j, pos, state, port_dlen, new_dlen, delta;
243 u_short p[2], new_len;
244 u_short sport, eport, base_port;
245 u_short salias = 0, ealias = 0, base_alias = 0;
246 const char *transport_str = "transport:";
247 char newdata[2048], *port_data, *port_newdata, stemp[80];
248 int links_created = 0, pkt_updated = 0;
249 struct alias_link *rtsp_lnk = NULL;
250 struct in_addr null_addr;
252 /* Calculate data length of TCP packet */
253 tc = (struct tcphdr *)ip_next(pip);
254 hlen = (pip->ip_hl + tc->th_off) << 2;
255 tlen = ntohs(pip->ip_len);
258 /* Find keyword, "Transport: " */
259 pos = search_string(data, dlen, transport_str);
263 port_data = data + pos;
264 port_dlen = dlen - pos;
266 memcpy(newdata, data, pos);
267 port_newdata = newdata + pos;
269 while (port_dlen > (int)strlen(port_str)) {
270 /* Find keyword, appropriate port string */
271 pos = search_string(port_data, port_dlen, port_str);
275 memcpy(port_newdata, port_data, pos + 1);
276 port_newdata += (pos + 1);
281 for (i = pos; i < port_dlen; i++) {
284 if (port_data[i] == '=') {
289 if (ISDIGIT(port_data[i])) {
290 p[0] = p[0] * 10 + port_data[i] - '0';
292 if (port_data[i] == ';') {
295 if (port_data[i] == '-') {
301 if (ISDIGIT(port_data[i])) {
302 p[1] = p[1] * 10 + port_data[i] - '0';
312 if (!links_created) {
316 * Find an even numbered port
317 * number base that satisfies the
318 * contiguous number of ports we
321 null_addr.s_addr = 0;
322 if (0 == (salias = FindNewPortGroup(la, null_addr,
323 FindAliasAddress(la, pip->ip_src),
327 #ifdef LIBALIAS_DEBUG
329 "PacketAlias/RTSP: Cannot find contiguous RTSP data ports\n");
333 base_alias = ntohs(salias);
334 for (j = 0; j < RTSP_PORT_GROUP; j++) {
340 rtsp_lnk = FindRtspOut(la, GetOriginalAddress(lnk), null_addr,
341 htons(base_port + j), htons(base_alias + j),
343 if (rtsp_lnk != NULL) {
350 PunchFWHole(rtsp_lnk);
353 #ifdef LIBALIAS_DEBUG
355 "PacketAlias/RTSP: Cannot allocate RTSP data ports\n");
361 ealias = htons(base_alias + (RTSP_PORT_GROUP - 1));
363 if (salias && rtsp_lnk) {
367 /* Copy into IP packet */
368 sprintf(stemp, "%d", ntohs(salias));
369 memcpy(port_newdata, stemp, strlen(stemp));
370 port_newdata += strlen(stemp);
376 /* Copy into IP packet */
377 sprintf(stemp, "%d", ntohs(ealias));
378 memcpy(port_newdata, stemp, strlen(stemp));
379 port_newdata += strlen(stemp);
398 memcpy(port_newdata, port_data, port_dlen);
399 port_newdata += port_dlen;
400 *port_newdata = '\0';
402 /* Create new packet */
403 new_dlen = port_newdata - newdata;
404 memcpy(data, newdata, new_dlen);
407 delta = GetDeltaSeqOut(pip, lnk);
408 AddSeq(pip, lnk, delta + new_dlen - dlen);
410 new_len = htons(hlen + new_dlen);
411 DifferentialChecksum(&pip->ip_sum,
415 pip->ip_len = new_len;
421 tc->th_sum = TcpChecksum(pip);
426 /* Support the protocol used by early versions of RealPlayer */
429 alias_pna_out(struct libalias *la, struct ip *pip,
430 struct alias_link *lnk,
434 struct alias_link *pna_links;
435 u_short msg_id, msg_len;
437 u_short alias_port, port;
442 while (work + 4 < data + dlen) {
443 memcpy(&msg_id, work, 2);
445 memcpy(&msg_len, work, 2);
447 if (ntohs(msg_id) == 0) {
451 if ((ntohs(msg_id) == 1) || (ntohs(msg_id) == 7)) {
452 memcpy(&port, work, 2);
453 pna_links = FindUdpTcpOut(la, pip->ip_src, GetDestAddress(lnk),
454 port, 0, IPPROTO_UDP, 1);
455 if (pna_links != NULL) {
457 /* Punch hole in firewall */
458 PunchFWHole(pna_links);
460 tc = (struct tcphdr *)ip_next(pip);
461 alias_port = GetAliasPort(pna_links);
462 memcpy(work, &alias_port, 2);
464 /* Compute TCP checksum for revised packet */
469 tc->th_sum = TcpChecksum(pip);
473 work += ntohs(msg_len);
480 AliasHandleRtspOut(struct libalias *la, struct ip *pip, struct alias_link *lnk, int maxpacketsize)
482 int hlen, tlen, dlen;
485 const char *setup = "SETUP", *pna = "PNA", *str200 = "200";
486 const char *okstr = "OK", *client_port_str = "client_port";
487 const char *server_port_str = "server_port";
492 tc = (struct tcphdr *)ip_next(pip);
493 hlen = (pip->ip_hl + tc->th_off) << 2;
494 tlen = ntohs(pip->ip_len);
500 /* When aliasing a client, check for the SETUP request */
501 if ((ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_1) ||
502 (ntohs(tc->th_dport) == RTSP_CONTROL_PORT_NUMBER_2)) {
504 if (dlen >= (int)strlen(setup)) {
505 if (memcmp(data, setup, strlen(setup)) == 0) {
506 alias_rtsp_out(la, pip, lnk, data, client_port_str);
510 if (dlen >= (int)strlen(pna)) {
511 if (memcmp(data, pna, strlen(pna)) == 0) {
512 alias_pna_out(la, pip, lnk, data, dlen);
518 * When aliasing a server, check for the 200 reply
519 * Accomodate varying number of blanks between 200 & OK
522 if (dlen >= (int)strlen(str200)) {
524 for (parseOk = 0, i = 0;
525 i <= dlen - (int)strlen(str200);
527 if (memcmp(&data[i], str200, strlen(str200)) == 0) {
534 i += strlen(str200); /* skip string found */
535 while (data[i] == ' ') /* skip blank(s) */
538 if ((dlen - i) >= (int)strlen(okstr)) {
540 if (memcmp(&data[i], okstr, strlen(okstr)) == 0)
541 alias_rtsp_out(la, pip, lnk, data, server_port_str);