alias_smedia.c@ 28023

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1	/*
2	* alias_smedia.c
3	*
4	* Copyright (c) 2000 Whistle Communications, Inc.
5	* All rights reserved.
6	*
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.
17	*
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
34	* OF SUCH DAMAGE.
35	*
36	* Copyright (c) 2000 Junichi SATOH <[email protected]>
37	* <[email protected]>
38	* All rights reserved.
39	*
40	* Redistribution and use in source and binary forms, with or without
41	* modification, are permitted provided that the following conditions
42	* are met:
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.
48	*
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
59	* SUCH DAMAGE.
60	*
61	* Authors: Erik Salander <[email protected]>
62	* Junichi SATOH <[email protected]>
63	* <[email protected]>
64	*/
65
66	#include <sys/cdefs.h>
67	__FBSDID("$FreeBSD: src/sys/netinet/libalias/alias_smedia.c,v 1.17.8.1 2009/04/15 03:14:26 kensmith Exp $");
68
69	/*
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.
75
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
79	the unicast case.
80
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.
85
86	The RTSP multicast functions without any address translation intervention.
87
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.
91
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.
97
98	Initial version: May, 2000 (eds)
99	*/
100
101	#ifdef _KERNEL
102	#include <sys/param.h>
103	#include <sys/systm.h>
104	#include <sys/kernel.h>
105	#include <sys/module.h>
106	#else
107	#include <errno.h>
108	#include <sys/types.h>
109	#include <stdio.h>
110	#include <string.h>
111	#endif
112
113	#include <netinet/in_systm.h>
114	#include <netinet/in.h>
115	#include <netinet/ip.h>
116	#include <netinet/tcp.h>
117
118	#ifdef _KERNEL
119	#include <netinet/libalias/alias.h>
120	#include <netinet/libalias/alias_local.h>
121	#include <netinet/libalias/alias_mod.h>
122	#else
123	#include "alias_local.h"
124	#include "alias_mod.h"
125	#endif
126
127	#define RTSP_CONTROL_PORT_NUMBER_1 554
128	#define RTSP_CONTROL_PORT_NUMBER_2 7070
129	#define TFTP_PORT_NUMBER 69
130
131	static void
132	AliasHandleRtspOut(struct libalias , struct ip , struct alias_link *,
133	int maxpacketsize);
134	static int
135	fingerprint(struct libalias la, struct ip pip, struct alias_data *ah)
136	{
137
138	if (ah->dport != NULL && ah->aport != NULL && ah->sport != NULL &&
139	ntohs(*ah->dport) == TFTP_PORT_NUMBER)
140	return (0);
141	if (ah->dport == NULL \|\| ah->sport == NULL \|\| ah->lnk == NULL \|\|
142	ah->maxpktsize == 0)
143	return (-1);
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)
148	return (0);
149	return (-1);
150	}
151
152	static int
153	protohandler(struct libalias la, struct ip pip, struct alias_data *ah)
154	{
155
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);
160	return (0);
161	}
162
163	struct proto_handler handlers[] = {
164	{
165	.pri = 100,
166	.dir = OUT,
167	.proto = TCP\|UDP,
168	.fingerprint = &fingerprint,
169	.protohandler = &protohandler
170	},
171	{ EOH }
172	};
173
174	static int
175	mod_handler(module_t mod, int type, void *data)
176	{
177	int error;
178
179	switch (type) {
180	case MOD_LOAD:
181	error = 0;
182	LibAliasAttachHandlers(handlers);
183	break;
184	case MOD_UNLOAD:
185	error = 0;
186	LibAliasDetachHandlers(handlers);
187	break;
188	default:
189	error = EINVAL;
190	}
191	return (error);
192	}
193
194	#ifdef _KERNEL
195	static
196	#endif
197	moduledata_t alias_mod = {
198	"alias_smedia", mod_handler, NULL
199	};
200
201	#ifdef _KERNEL
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);
205	#endif
206
207	#define RTSP_CONTROL_PORT_NUMBER_1 554
208	#define RTSP_CONTROL_PORT_NUMBER_2 7070
209	#define RTSP_PORT_GROUP 2
210
211	#define ISDIGIT(a) (((a) >= '0') && ((a) <= '9'))
212
213	static int
214	search_string(char data, int dlen, const char search_str)
215	{
216	int i, j, k;
217	int search_str_len;
218
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')) {
224	break;
225	}
226	if (k == search_str_len - 1) {
227	return (j + 1);
228	}
229	}
230	}
231	return (-1);
232	}
233
234	static int
235	alias_rtsp_out(struct libalias la, struct ip pip,
236	struct alias_link *lnk,
237	char *data,
238	const char *port_str)
239	{
240	int hlen, tlen, dlen;
241	struct tcphdr *tc;
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;
251
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);
256	dlen = tlen - hlen;
257
258	/* Find keyword, "Transport: " */
259	pos = search_string(data, dlen, transport_str);
260	if (pos < 0) {
261	return (-1);
262	}
263	port_data = data + pos;
264	port_dlen = dlen - pos;
265
266	memcpy(newdata, data, pos);
267	port_newdata = newdata + pos;
268
269	while (port_dlen > (int)strlen(port_str)) {
270	/* Find keyword, appropriate port string */
271	pos = search_string(port_data, port_dlen, port_str);
272	if (pos < 0) {
273	break;
274	}
275	memcpy(port_newdata, port_data, pos + 1);
276	port_newdata += (pos + 1);
277
278	p[0] = p[1] = 0;
279	sport = eport = 0;
280	state = 0;
281	for (i = pos; i < port_dlen; i++) {
282	switch (state) {
283	case 0:
284	if (port_data[i] == '=') {
285	state++;
286	}
287	break;
288	case 1:
289	if (ISDIGIT(port_data[i])) {
290	p[0] = p[0] * 10 + port_data[i] - '0';
291	} else {
292	if (port_data[i] == ';') {
293	state = 3;
294	}
295	if (port_data[i] == '-') {
296	state++;
297	}
298	}
299	break;
300	case 2:
301	if (ISDIGIT(port_data[i])) {
302	p[1] = p[1] * 10 + port_data[i] - '0';
303	} else {
304	state++;
305	}
306	break;
307	case 3:
308	base_port = p[0];
309	sport = htons(p[0]);
310	eport = htons(p[1]);
311
312	if (!links_created) {
313
314	links_created = 1;
315	/*
316	* Find an even numbered port
317	* number base that satisfies the
318	* contiguous number of ports we
319	* need
320	*/
321	null_addr.s_addr = 0;
322	if (0 == (salias = FindNewPortGroup(la, null_addr,
323	FindAliasAddress(la, pip->ip_src),
324	sport, 0,
325	RTSP_PORT_GROUP,
326	IPPROTO_UDP, 1))) {
327	#ifdef LIBALIAS_DEBUG
328	fprintf(stderr,
329	"PacketAlias/RTSP: Cannot find contiguous RTSP data ports\n");
330	#endif
331	} else {
332
333	base_alias = ntohs(salias);
334	for (j = 0; j < RTSP_PORT_GROUP; j++) {
335	/*
336	* Establish link
337	* to port found in
338	* RTSP packet
339	*/
340	rtsp_lnk = FindRtspOut(la, GetOriginalAddress(lnk), null_addr,
341	htons(base_port + j), htons(base_alias + j),
342	IPPROTO_UDP);
343	if (rtsp_lnk != NULL) {
344	#ifndef NO_FW_PUNCH
345	/*
346	* Punch
347	* hole in
348	* firewall
349	*/
350	PunchFWHole(rtsp_lnk);
351	#endif
352	} else {
353	#ifdef LIBALIAS_DEBUG
354	fprintf(stderr,
355	"PacketAlias/RTSP: Cannot allocate RTSP data ports\n");
356	#endif
357	break;
358	}
359	}
360	}
361	ealias = htons(base_alias + (RTSP_PORT_GROUP - 1));
362	}
363	if (salias && rtsp_lnk) {
364
365	pkt_updated = 1;
366
367	/* Copy into IP packet */
368	sprintf(stemp, "%d", ntohs(salias));
369	memcpy(port_newdata, stemp, strlen(stemp));
370	port_newdata += strlen(stemp);
371
372	if (eport != 0) {
373	*port_newdata = '-';
374	port_newdata++;
375
376	/* Copy into IP packet */
377	sprintf(stemp, "%d", ntohs(ealias));
378	memcpy(port_newdata, stemp, strlen(stemp));
379	port_newdata += strlen(stemp);
380	}
381	*port_newdata = ';';
382	port_newdata++;
383	}
384	state++;
385	break;
386	}
387	if (state > 3) {
388	break;
389	}
390	}
391	port_data += i;
392	port_dlen -= i;
393	}
394
395	if (!pkt_updated)
396	return (-1);
397
398	memcpy(port_newdata, port_data, port_dlen);
399	port_newdata += port_dlen;
400	*port_newdata = '\0';
401
402	/* Create new packet */
403	new_dlen = port_newdata - newdata;
404	memcpy(data, newdata, new_dlen);
405
406	SetAckModified(lnk);
407	delta = GetDeltaSeqOut(pip, lnk);
408	AddSeq(pip, lnk, delta + new_dlen - dlen);
409
410	new_len = htons(hlen + new_dlen);
411	DifferentialChecksum(&pip->ip_sum,
412	&new_len,
413	&pip->ip_len,
414	1);
415	pip->ip_len = new_len;
416
417	tc->th_sum = 0;
418	#ifdef _KERNEL
419	tc->th_x2 = 1;
420	#else
421	tc->th_sum = TcpChecksum(pip);
422	#endif
423	return (0);
424	}
425
426	/* Support the protocol used by early versions of RealPlayer */
427
428	static int
429	alias_pna_out(struct libalias la, struct ip pip,
430	struct alias_link *lnk,
431	char *data,
432	int dlen)
433	{
434	struct alias_link *pna_links;
435	u_short msg_id, msg_len;
436	char *work;
437	u_short alias_port, port;
438	struct tcphdr *tc;
439
440	work = data;
441	work += 5;
442	while (work + 4 < data + dlen) {
443	memcpy(&msg_id, work, 2);
444	work += 2;
445	memcpy(&msg_len, work, 2);
446	work += 2;
447	if (ntohs(msg_id) == 0) {
448	/* end of options */
449	return (0);
450	}
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) {
456	#ifndef NO_FW_PUNCH
457	/* Punch hole in firewall */
458	PunchFWHole(pna_links);
459	#endif
460	tc = (struct tcphdr *)ip_next(pip);
461	alias_port = GetAliasPort(pna_links);
462	memcpy(work, &alias_port, 2);
463
464	/* Compute TCP checksum for revised packet */
465	tc->th_sum = 0;
466	#ifdef _KERNEL
467	tc->th_x2 = 1;
468	#else
469	tc->th_sum = TcpChecksum(pip);
470	#endif
471	}
472	}
473	work += ntohs(msg_len);
474	}
475
476	return (0);
477	}
478
479	static void
480	AliasHandleRtspOut(struct libalias la, struct ip pip, struct alias_link *lnk, int maxpacketsize)
481	{
482	int hlen, tlen, dlen;
483	struct tcphdr *tc;
484	char *data;
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";
488	int i, parseOk;
489
490	(void)maxpacketsize;
491
492	tc = (struct tcphdr *)ip_next(pip);
493	hlen = (pip->ip_hl + tc->th_off) << 2;
494	tlen = ntohs(pip->ip_len);
495	dlen = tlen - hlen;
496
497	data = (char *)pip;
498	data += hlen;
499
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)) {
503
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);
507	return;
508	}
509	}
510	if (dlen >= (int)strlen(pna)) {
511	if (memcmp(data, pna, strlen(pna)) == 0) {
512	alias_pna_out(la, pip, lnk, data, dlen);
513	}
514	}
515	} else {
516
517	/*
518	* When aliasing a server, check for the 200 reply
519	* Accomodate varying number of blanks between 200 & OK
520	*/
521
522	if (dlen >= (int)strlen(str200)) {
523
524	for (parseOk = 0, i = 0;
525	i <= dlen - (int)strlen(str200);
526	i++) {
527	if (memcmp(&data[i], str200, strlen(str200)) == 0) {
528	parseOk = 1;
529	break;
530	}
531	}
532	if (parseOk) {
533
534	i += strlen(str200); /* skip string found */
535	while (data[i] == ' ') /* skip blank(s) */
536	i++;
537
538	if ((dlen - i) >= (int)strlen(okstr)) {
539
540	if (memcmp(&data[i], okstr, strlen(okstr)) == 0)
541	alias_rtsp_out(la, pip, lnk, data, server_port_str);
542
543	}
544	}
545	}
546	}
547	}

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