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rdt.c
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1 /*
2  * Realmedia RTSP protocol (RDT) support.
3  * Copyright (c) 2007 Ronald S. Bultje
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * @brief Realmedia RTSP protocol (RDT) support
25  * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
26  */
27 
28 #include "avformat.h"
29 #include "libavutil/avstring.h"
30 #include "rtpdec.h"
31 #include "rdt.h"
32 #include "libavutil/base64.h"
33 #include "libavutil/md5.h"
34 #include "rm.h"
35 #include "internal.h"
36 #include "avio_internal.h"
37 #include "libavcodec/get_bits.h"
38 
40  AVFormatContext *ic; /**< the containing (RTSP) demux context */
41  /** Each RDT stream-set (represented by one RTSPStream) can contain
42  * multiple streams (of the same content, but with possibly different
43  * codecs/bitrates). Each such stream is represented by one AVStream
44  * in the AVFormatContext, and this variable points to the offset in
45  * that array such that the first is the first stream of this set. */
47  int n_streams; /**< streams with identifical content in this set */
50  uint32_t prev_timestamp;
52 };
53 
55 ff_rdt_parse_open(AVFormatContext *ic, int first_stream_of_set_idx,
56  void *priv_data, RTPDynamicProtocolHandler *handler)
57 {
59  if (!s)
60  return NULL;
61 
62  s->ic = ic;
63  s->streams = &ic->streams[first_stream_of_set_idx];
64  do {
65  s->n_streams++;
66  } while (first_stream_of_set_idx + s->n_streams < ic->nb_streams &&
67  s->streams[s->n_streams]->id == s->streams[0]->id);
68  s->prev_set_id = -1;
69  s->prev_stream_id = -1;
70  s->prev_timestamp = -1;
71  s->parse_packet = handler ? handler->parse_packet : NULL;
72  s->dynamic_protocol_context = priv_data;
73 
74  return s;
75 }
76 
77 void
79 {
80  av_free(s);
81 }
82 
85  int nb_rmst;
88  unsigned int mlti_data_size;
90  int audio_pkt_cnt; /**< remaining audio packets in rmdec */
91 };
92 
93 void
94 ff_rdt_calc_response_and_checksum(char response[41], char chksum[9],
95  const char *challenge)
96 {
97  int ch_len = strlen (challenge), i;
98  unsigned char zres[16],
99  buf[64] = { 0xa1, 0xe9, 0x14, 0x9d, 0x0e, 0x6b, 0x3b, 0x59 };
100 #define XOR_TABLE_SIZE 37
101  static const unsigned char xor_table[XOR_TABLE_SIZE] = {
102  0x05, 0x18, 0x74, 0xd0, 0x0d, 0x09, 0x02, 0x53,
103  0xc0, 0x01, 0x05, 0x05, 0x67, 0x03, 0x19, 0x70,
104  0x08, 0x27, 0x66, 0x10, 0x10, 0x72, 0x08, 0x09,
105  0x63, 0x11, 0x03, 0x71, 0x08, 0x08, 0x70, 0x02,
106  0x10, 0x57, 0x05, 0x18, 0x54 };
107 
108  /* some (length) checks */
109  if (ch_len == 40) /* what a hack... */
110  ch_len = 32;
111  else if (ch_len > 56)
112  ch_len = 56;
113  memcpy(buf + 8, challenge, ch_len);
114 
115  /* xor challenge bytewise with xor_table */
116  for (i = 0; i < XOR_TABLE_SIZE; i++)
117  buf[8 + i] ^= xor_table[i];
118 
119  av_md5_sum(zres, buf, 64);
120  ff_data_to_hex(response, zres, 16, 1);
121 
122  /* add tail */
123  strcpy (response + 32, "01d0a8e3");
124 
125  /* calculate checksum */
126  for (i = 0; i < 8; i++)
127  chksum[i] = response[i * 4];
128  chksum[8] = 0;
129 }
130 
131 static int
132 rdt_load_mdpr (PayloadContext *rdt, AVStream *st, int rule_nr)
133 {
134  AVIOContext pb;
135  unsigned int size;
136  uint32_t tag;
137 
138  /**
139  * Layout of the MLTI chunk:
140  * 4: MLTI
141  * 2: number of streams
142  * Then for each stream ([number_of_streams] times):
143  * 2: mdpr index
144  * 2: number of mdpr chunks
145  * Then for each mdpr chunk ([number_of_mdpr_chunks] times):
146  * 4: size
147  * [size]: data
148  * we skip MDPR chunks until we reach the one of the stream
149  * we're interested in, and forward that ([size]+[data]) to
150  * the RM demuxer to parse the stream-specific header data.
151  */
152  if (!rdt->mlti_data)
153  return -1;
154  ffio_init_context(&pb, rdt->mlti_data, rdt->mlti_data_size, 0,
155  NULL, NULL, NULL, NULL);
156  tag = avio_rl32(&pb);
157  if (tag == MKTAG('M', 'L', 'T', 'I')) {
158  int num, chunk_nr;
159 
160  /* read index of MDPR chunk numbers */
161  num = avio_rb16(&pb);
162  if (rule_nr < 0 || rule_nr >= num)
163  return -1;
164  avio_skip(&pb, rule_nr * 2);
165  chunk_nr = avio_rb16(&pb);
166  avio_skip(&pb, (num - 1 - rule_nr) * 2);
167 
168  /* read MDPR chunks */
169  num = avio_rb16(&pb);
170  if (chunk_nr >= num)
171  return -1;
172  while (chunk_nr--)
173  avio_skip(&pb, avio_rb32(&pb));
174  size = avio_rb32(&pb);
175  } else {
176  size = rdt->mlti_data_size;
177  avio_seek(&pb, 0, SEEK_SET);
178  }
179  if (ff_rm_read_mdpr_codecdata(rdt->rmctx, &pb, st, rdt->rmst[st->index], size, NULL) < 0)
180  return -1;
181 
182  return 0;
183 }
184 
185 /**
186  * Actual data handling.
187  */
188 
189 int
191  int *pset_id, int *pseq_no, int *pstream_id,
192  int *pis_keyframe, uint32_t *ptimestamp)
193 {
194  GetBitContext gb;
195  int consumed = 0, set_id, seq_no, stream_id, is_keyframe,
196  len_included, need_reliable;
197  uint32_t timestamp;
198 
199  /* skip status packets */
200  while (len >= 5 && buf[1] == 0xFF /* status packet */) {
201  int pkt_len;
202 
203  if (!(buf[0] & 0x80))
204  return -1; /* not followed by a data packet */
205 
206  pkt_len = AV_RB16(buf+3);
207  buf += pkt_len;
208  len -= pkt_len;
209  consumed += pkt_len;
210  }
211  if (len < 16)
212  return -1;
213  /**
214  * Layout of the header (in bits):
215  * 1: len_included
216  * Flag indicating whether this header includes a length field;
217  * this can be used to concatenate multiple RDT packets in a
218  * single UDP/TCP data frame and is used to precede RDT data
219  * by stream status packets
220  * 1: need_reliable
221  * Flag indicating whether this header includes a "reliable
222  * sequence number"; these are apparently sequence numbers of
223  * data packets alone. For data packets, this flag is always
224  * set, according to the Real documentation [1]
225  * 5: set_id
226  * ID of a set of streams of identical content, possibly with
227  * different codecs or bitrates
228  * 1: is_reliable
229  * Flag set for certain streams deemed less tolerable for packet
230  * loss
231  * 16: seq_no
232  * Packet sequence number; if >=0xFF00, this is a non-data packet
233  * containing stream status info, the second byte indicates the
234  * type of status packet (see wireshark docs / source code [2])
235  * if (len_included) {
236  * 16: packet_len
237  * } else {
238  * packet_len = remainder of UDP/TCP frame
239  * }
240  * 1: is_back_to_back
241  * Back-to-Back flag; used for timing, set for one in every 10
242  * packets, according to the Real documentation [1]
243  * 1: is_slow_data
244  * Slow-data flag; currently unused, according to Real docs [1]
245  * 5: stream_id
246  * ID of the stream within this particular set of streams
247  * 1: is_no_keyframe
248  * Non-keyframe flag (unset if packet belongs to a keyframe)
249  * 32: timestamp (PTS)
250  * if (set_id == 0x1F) {
251  * 16: set_id (extended set-of-streams ID; see set_id)
252  * }
253  * if (need_reliable) {
254  * 16: reliable_seq_no
255  * Reliable sequence number (see need_reliable)
256  * }
257  * if (stream_id == 0x3F) {
258  * 16: stream_id (extended stream ID; see stream_id)
259  * }
260  * [1] https://protocol.helixcommunity.org/files/2005/devdocs/RDT_Feature_Level_20.txt
261  * [2] http://www.wireshark.org/docs/dfref/r/rdt.html and
262  * http://anonsvn.wireshark.org/viewvc/trunk/epan/dissectors/packet-rdt.c
263  */
264  init_get_bits(&gb, buf, len << 3);
265  len_included = get_bits1(&gb);
266  need_reliable = get_bits1(&gb);
267  set_id = get_bits(&gb, 5);
268  skip_bits(&gb, 1);
269  seq_no = get_bits(&gb, 16);
270  if (len_included)
271  skip_bits(&gb, 16);
272  skip_bits(&gb, 2);
273  stream_id = get_bits(&gb, 5);
274  is_keyframe = !get_bits1(&gb);
275  timestamp = get_bits_long(&gb, 32);
276  if (set_id == 0x1f)
277  set_id = get_bits(&gb, 16);
278  if (need_reliable)
279  skip_bits(&gb, 16);
280  if (stream_id == 0x1f)
281  stream_id = get_bits(&gb, 16);
282 
283  if (pset_id) *pset_id = set_id;
284  if (pseq_no) *pseq_no = seq_no;
285  if (pstream_id) *pstream_id = stream_id;
286  if (pis_keyframe) *pis_keyframe = is_keyframe;
287  if (ptimestamp) *ptimestamp = timestamp;
288 
289  return consumed + (get_bits_count(&gb) >> 3);
290 }
291 
292 /**< return 0 on packet, no more left, 1 on packet, 1 on partial packet... */
293 static int
295  AVPacket *pkt, uint32_t *timestamp,
296  const uint8_t *buf, int len, uint16_t rtp_seq, int flags)
297 {
298  int seq = 1, res;
299  AVIOContext pb;
300 
301  if (rdt->audio_pkt_cnt == 0) {
302  int pos;
303 
304  ffio_init_context(&pb, (uint8_t *)buf, len, 0, NULL, NULL, NULL, NULL);
305  flags = (flags & RTP_FLAG_KEY) ? 2 : 0;
306  res = ff_rm_parse_packet (rdt->rmctx, &pb, st, rdt->rmst[st->index], len, pkt,
307  &seq, flags, *timestamp);
308  pos = avio_tell(&pb);
309  if (res < 0)
310  return res;
311  if (res > 0) {
312  if (st->codec->codec_id == AV_CODEC_ID_AAC) {
313  memcpy (rdt->buffer, buf + pos, len - pos);
314  rdt->rmctx->pb = avio_alloc_context (rdt->buffer, len - pos, 0,
315  NULL, NULL, NULL, NULL);
316  }
317  goto get_cache;
318  }
319  } else {
320 get_cache:
321  rdt->audio_pkt_cnt =
322  ff_rm_retrieve_cache (rdt->rmctx, rdt->rmctx->pb,
323  st, rdt->rmst[st->index], pkt);
324  if (rdt->audio_pkt_cnt == 0 &&
326  av_freep(&rdt->rmctx->pb);
327  }
328  pkt->stream_index = st->index;
329  pkt->pts = *timestamp;
330 
331  return rdt->audio_pkt_cnt > 0;
332 }
333 
334 int
336  uint8_t **bufptr, int len)
337 {
338  uint8_t *buf = bufptr ? *bufptr : NULL;
339  int seq_no, flags = 0, stream_id, set_id, is_keyframe;
340  uint32_t timestamp;
341  int rv= 0;
342 
343  if (!s->parse_packet)
344  return -1;
345 
346  if (!buf && s->prev_stream_id != -1) {
347  /* return the next packets, if any */
348  timestamp= 0; ///< Should not be used if buf is NULL, but should be set to the timestamp of the packet returned....
350  s->streams[s->prev_stream_id],
351  pkt, &timestamp, NULL, 0, 0, flags);
352  return rv;
353  }
354 
355  if (len < 12)
356  return -1;
357  rv = ff_rdt_parse_header(buf, len, &set_id, &seq_no, &stream_id, &is_keyframe, &timestamp);
358  if (rv < 0)
359  return rv;
360  if (is_keyframe &&
361  (set_id != s->prev_set_id || timestamp != s->prev_timestamp ||
362  stream_id != s->prev_stream_id)) {
363  flags |= RTP_FLAG_KEY;
364  s->prev_set_id = set_id;
365  s->prev_timestamp = timestamp;
366  }
367  s->prev_stream_id = stream_id;
368  buf += rv;
369  len -= rv;
370 
371  if (s->prev_stream_id >= s->n_streams) {
372  s->prev_stream_id = -1;
373  return -1;
374  }
375 
377  s->streams[s->prev_stream_id],
378  pkt, &timestamp, buf, len, 0, flags);
379 
380  return rv;
381 }
382 
383 void
384 ff_rdt_subscribe_rule (char *cmd, int size,
385  int stream_nr, int rule_nr)
386 {
387  av_strlcatf(cmd, size, "stream=%d;rule=%d,stream=%d;rule=%d",
388  stream_nr, rule_nr * 2, stream_nr, rule_nr * 2 + 1);
389 }
390 
391 static unsigned char *
392 rdt_parse_b64buf (unsigned int *target_len, const char *p)
393 {
394  unsigned char *target;
395  int len = strlen(p);
396  if (*p == '\"') {
397  p++;
398  len -= 2; /* skip embracing " at start/end */
399  }
400  *target_len = len * 3 / 4;
401  target = av_mallocz(*target_len + FF_INPUT_BUFFER_PADDING_SIZE);
402  if (!target)
403  return NULL;
404  av_base64_decode(target, p, *target_len);
405  return target;
406 }
407 
408 static int
410  PayloadContext *rdt, const char *line)
411 {
412  AVStream *stream = s->streams[st_index];
413  const char *p = line;
414 
415  if (av_strstart(p, "OpaqueData:buffer;", &p)) {
416  rdt->mlti_data = rdt_parse_b64buf(&rdt->mlti_data_size, p);
417  } else if (av_strstart(p, "StartTime:integer;", &p))
418  stream->first_dts = atoi(p);
419  else if (av_strstart(p, "ASMRuleBook:string;", &p)) {
420  int n, first = -1;
421 
422  for (n = 0; n < s->nb_streams; n++)
423  if (s->streams[n]->id == stream->id) {
424  int count = s->streams[n]->index + 1, err;
425  if (first == -1) first = n;
426  if (rdt->nb_rmst < count) {
427  if ((err = av_reallocp(&rdt->rmst,
428  count * sizeof(*rdt->rmst))) < 0) {
429  rdt->nb_rmst = 0;
430  return err;
431  }
432  memset(rdt->rmst + rdt->nb_rmst, 0,
433  (count - rdt->nb_rmst) * sizeof(*rdt->rmst));
434  rdt->nb_rmst = count;
435  }
436  rdt->rmst[s->streams[n]->index] = ff_rm_alloc_rmstream();
437  rdt_load_mdpr(rdt, s->streams[n], (n - first) * 2);
438  }
439  }
440 
441  return 0;
442 }
443 
444 static void
445 real_parse_asm_rule(AVStream *st, const char *p, const char *end)
446 {
447  do {
448  /* can be either averagebandwidth= or AverageBandwidth= */
449  if (sscanf(p, " %*1[Aa]verage%*1[Bb]andwidth=%d", &st->codec->bit_rate) == 1)
450  break;
451  if (!(p = strchr(p, ',')) || p > end)
452  p = end;
453  p++;
454  } while (p < end);
455 }
456 
457 static AVStream *
459 {
460  AVStream *st;
461 
462  if (!(st = avformat_new_stream(s, NULL)))
463  return NULL;
464  st->id = orig_st->id;
465  st->codec->codec_type = orig_st->codec->codec_type;
466  st->first_dts = orig_st->first_dts;
467 
468  return st;
469 }
470 
471 static void
473  const char *p)
474 {
475  const char *end;
476  int n_rules = 0, odd = 0;
477  AVStream *st;
478 
479  /**
480  * The ASMRuleBook contains a list of comma-separated strings per rule,
481  * and each rule is separated by a ;. The last one also has a ; at the
482  * end so we can use it as delimiter.
483  * Every rule occurs twice, once for when the RTSP packet header marker
484  * is set and once for if it isn't. We only read the first because we
485  * don't care much (that's what the "odd" variable is for).
486  * Each rule contains a set of one or more statements, optionally
487  * preceded by a single condition. If there's a condition, the rule
488  * starts with a '#'. Multiple conditions are merged between brackets,
489  * so there are never multiple conditions spread out over separate
490  * statements. Generally, these conditions are bitrate limits (min/max)
491  * for multi-bitrate streams.
492  */
493  if (*p == '\"') p++;
494  while (1) {
495  if (!(end = strchr(p, ';')))
496  break;
497  if (!odd && end != p) {
498  if (n_rules > 0)
499  st = add_dstream(s, orig_st);
500  else
501  st = orig_st;
502  if (!st)
503  break;
504  real_parse_asm_rule(st, p, end);
505  n_rules++;
506  }
507  p = end + 1;
508  odd ^= 1;
509  }
510 }
511 
512 void
514  const char *line)
515 {
516  const char *p = line;
517 
518  if (av_strstart(p, "ASMRuleBook:string;", &p))
519  real_parse_asm_rulebook(s, s->streams[stream_index], p);
520 }
521 
522 static PayloadContext *
524 {
525  PayloadContext *rdt = av_mallocz(sizeof(PayloadContext));
526  if (!rdt)
527  return NULL;
528 
529  rdt->rmctx = avformat_alloc_context();
530  if (!rdt->rmctx)
531  av_freep(&rdt);
532 
533  return rdt;
534 }
535 
536 static int
538 {
539  int ret;
540 
541  if ((ret = ff_copy_whitelists(rdt->rmctx, s)) < 0)
542  return ret;
543 
544  return avformat_open_input(&rdt->rmctx, "", &ff_rdt_demuxer, NULL);
545 }
546 
547 static void
549 {
550  int i;
551 
552  for (i = 0; i < rdt->nb_rmst; i++)
553  if (rdt->rmst[i]) {
554  ff_rm_free_rmstream(rdt->rmst[i]);
555  av_freep(&rdt->rmst[i]);
556  }
557  if (rdt->rmctx)
559  av_freep(&rdt->mlti_data);
560  av_freep(&rdt->rmst);
561  av_free(rdt);
562 }
563 
564 #define RDT_HANDLER(n, s, t) \
565 static RTPDynamicProtocolHandler rdt_ ## n ## _handler = { \
566  .enc_name = s, \
567  .codec_type = t, \
568  .codec_id = AV_CODEC_ID_NONE, \
569  .parse_sdp_a_line = rdt_parse_sdp_line, \
570  .alloc = rdt_new_context, \
571  .init = rdt_init_context, \
572  .free = rdt_free_context, \
573  .parse_packet = rdt_parse_packet \
574 }
575 
576 RDT_HANDLER(live_video, "x-pn-multirate-realvideo-live", AVMEDIA_TYPE_VIDEO);
577 RDT_HANDLER(live_audio, "x-pn-multirate-realaudio-live", AVMEDIA_TYPE_AUDIO);
578 RDT_HANDLER(video, "x-pn-realvideo", AVMEDIA_TYPE_VIDEO);
579 RDT_HANDLER(audio, "x-pn-realaudio", AVMEDIA_TYPE_AUDIO);
580 
582 {
583  ff_register_dynamic_payload_handler(&rdt_video_handler);
584  ff_register_dynamic_payload_handler(&rdt_audio_handler);
585  ff_register_dynamic_payload_handler(&rdt_live_video_handler);
586  ff_register_dynamic_payload_handler(&rdt_live_audio_handler);
587 }