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source: vbox/trunk/src/VBox/Devices/Network/slirp/libalias/alias_smedia.c

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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 <junichi@astec.co.jp>
37 * <junichi@junichi.org>
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 <erik@whistle.com>
62 * Junichi SATOH <junichi@astec.co.jp>
63 * <junichi@junichi.org>
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
131static void
132AliasHandleRtspOut(struct libalias *, struct ip *, struct alias_link *,
133 int maxpacketsize);
134static int
135fingerprint(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
152static int
153protohandler(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
163struct 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
174static int
175mod_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
195static
196#endif
197moduledata_t alias_mod = {
198 "alias_smedia", mod_handler, NULL
199};
200
201#ifdef _KERNEL
202DECLARE_MODULE(alias_smedia, alias_mod, SI_SUB_DRIVERS, SI_ORDER_SECOND);
203MODULE_VERSION(alias_smedia, 1);
204MODULE_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
213static int
214search_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
234static int
235alias_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
428static int
429alias_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
479static void
480AliasHandleRtspOut(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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