libavformat/rdt.c

   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 rdt.c
  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 "rtp_internal.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 <libavcodec/bitstream.h>
  37
  38 struct RDTDemuxContext {
  39     AVFormatContext *ic; /**< the containing (RTSP) demux context */
  40     AVStream *st;
  41     void *dynamic_protocol_context;
  42     DynamicPayloadPacketHandlerProc parse_packet;
  43     uint32_t prev_timestamp;
  44     int prev_set_id;
  45 };
  46
  47 RDTDemuxContext *
  48 ff_rdt_parse_open(AVFormatContext *ic, AVStream *st,
  49                   void *priv_data, RTPDynamicProtocolHandler *handler)
  50 {
  51     RDTDemuxContext *s = av_mallocz(sizeof(RDTDemuxContext));
  52     if (!s)
  53         return NULL;
  54
  55     s->ic = ic;
  56     s->st = st;
  57     s->prev_set_id    = -1;
  58     s->prev_timestamp = -1;
  59     s->parse_packet = handler->parse_packet;
  60     s->dynamic_protocol_context = priv_data;
  61
  62     return s;
  63 }
  64
  65 void
  66 ff_rdt_parse_close(RDTDemuxContext *s)
  67 {
  68     av_free(s);
  69 }
  70
  71 struct PayloadContext {
  72     AVFormatContext *rmctx;
  73     uint8_t *mlti_data;
  74     unsigned int mlti_data_size;
  75     char buffer[RTP_MAX_PACKET_LENGTH + FF_INPUT_BUFFER_PADDING_SIZE];
  76 };
  77
  78 void
  79 ff_rdt_calc_response_and_checksum(char response[41], char chksum[9],
  80                                   const char *challenge)
  81 {
  82     int ch_len = strlen (challenge), i;
  83     unsigned char zres[16],
  84         buf[64] = { 0xa1, 0xe9, 0x14, 0x9d, 0x0e, 0x6b, 0x3b, 0x59 };
  85 #define XOR_TABLE_SIZE 37
  86     const unsigned char xor_table[XOR_TABLE_SIZE] = {
  87         0x05, 0x18, 0x74, 0xd0, 0x0d, 0x09, 0x02, 0x53,
  88         0xc0, 0x01, 0x05, 0x05, 0x67, 0x03, 0x19, 0x70,
  89         0x08, 0x27, 0x66, 0x10, 0x10, 0x72, 0x08, 0x09,
  90         0x63, 0x11, 0x03, 0x71, 0x08, 0x08, 0x70, 0x02,
  91         0x10, 0x57, 0x05, 0x18, 0x54 };
  92
  93     /* some (length) checks */
  94     if (ch_len == 40) /* what a hack... */
  95         ch_len = 32;
  96     else if (ch_len > 56)
  97         ch_len = 56;
  98     memcpy(buf + 8, challenge, ch_len);
  99
 100     /* xor challenge bytewise with xor_table */
 101     for (i = 0; i < XOR_TABLE_SIZE; i++)
 102         buf[8 + i] ^= xor_table[i];
 103
 104     av_md5_sum(zres, buf, 64);
 105     ff_data_to_hex(response, zres, 16);
 106     for (i=0;i<32;i++) response[i] = tolower(response[i]);
 107
 108     /* add tail */
 109     strcpy (response + 32, "01d0a8e3");
 110
 111     /* calculate checksum */
 112     for (i = 0; i < 8; i++)
 113         chksum[i] = response[i * 4];
 114     chksum[8] = 0;
 115 }
 116
 117 static int
 118 rdt_load_mdpr (PayloadContext *rdt, AVStream *st, int rule_nr)
 119 {
 120     ByteIOContext pb;
 121     int size;
 122     uint32_t tag;
 123
 124     /**
 125      * Layout of the MLTI chunk:
 126      * 4:MLTI
 127      * 2:<number of streams>
 128      * Then for each stream ([number_of_streams] times):
 129      *     2:<mdpr index>
 130      * 2:<number of mdpr chunks>
 131      * Then for each mdpr chunk ([number_of_mdpr_chunks] times):
 132      *     4:<size>
 133      *     [size]:<data>
 134      * we skip MDPR chunks until we reach the one of the stream
 135      * we're interested in, and forward that ([size]+[data]) to
 136      * the RM demuxer to parse the stream-specific header data.
 137      */
 138     if (!rdt->mlti_data)
 139         return -1;
 140     init_put_byte(&pb, rdt->mlti_data, rdt->mlti_data_size, 0,
 141                   NULL, NULL, NULL, NULL);
 142     tag = get_le32(&pb);
 143     if (tag == MKTAG('M', 'L', 'T', 'I')) {
 144         int num, chunk_nr;
 145
 146         /* read index of MDPR chunk numbers */
 147         num = get_be16(&pb);
 148         if (rule_nr < 0 || rule_nr >= num)
 149             return -1;
 150         url_fskip(&pb, rule_nr * 2);
 151         chunk_nr = get_be16(&pb);
 152         url_fskip(&pb, (num - 1 - rule_nr) * 2);
 153
 154         /* read MDPR chunks */
 155         num = get_be16(&pb);
 156         if (chunk_nr >= num)
 157             return -1;
 158         while (chunk_nr--)
 159             url_fskip(&pb, get_be32(&pb));
 160         size = get_be32(&pb);
 161     } else {
 162         size = rdt->mlti_data_size;
 163         url_fseek(&pb, 0, SEEK_SET);
 164     }
 165     if (ff_rm_read_mdpr_codecdata(rdt->rmctx, &pb, st, size) < 0)
 166         return -1;
 167
 168     return 0;
 169 }
 170
 171 /**
 172  * Actual data handling.
 173  */
 174
 175 int
 176 ff_rdt_parse_header(const uint8_t *buf, int len,
 177                     int *pset_id, int *pseq_no, int *pstream_id,
 178                     int *pis_keyframe, uint32_t *ptimestamp)
 179 {
 180     GetBitContext gb;
 181     int consumed = 0, set_id, seq_no, stream_id, is_keyframe,
 182         len_included, need_reliable;
 183     uint32_t timestamp;
 184
 185     /* skip status packets */
 186     while (len >= 5 && buf[1] == 0xFF /* status packet */) {
 187         int pkt_len;
 188
 189         if (!(buf[0] & 0x80))
 190             return -1; /* not followed by a data packet */
 191
 192         pkt_len = AV_RB16(buf+3);
 193         buf += pkt_len;
 194         len -= pkt_len;
 195         consumed += pkt_len;
 196     }
 197     if (len < 16)
 198         return -1;
 199     /**
 200      * Layout of the header (in bits):
 201      * 1:  len_included
 202      *     Flag indicating whether this header includes a length field;
 203      *     this can be used to concatenate multiple RDT packets in a
 204      *     single UDP/TCP data frame and is used to precede RDT data
 205      *     by stream status packets
 206      * 1:  need_reliable
 207      *     Flag indicating whether this header includes a "reliable
 208      *     sequence number"; these are apparently sequence numbers of
 209      *     data packets alone. For data packets, this flag is always
 210      *     set, according to the Real documentation [1]
 211      * 5:  set_id
 212      *     ID of a set of streams of identical content, possibly with
 213      *     different codecs or bitrates
 214      * 1:  is_reliable
 215      *     Flag set for certain streams deemed less tolerable for packet
 216      *     loss
 217      * 16: seq_no
 218      *     Packet sequence number; if >=0xFF00, this is a non-data packet
 219      *     containing stream status info, the second byte indicates the
 220      *     type of status packet (see wireshark docs / source code [2])
 221      * if (len_included) {
 222      *     16: packet_len
 223      * } else {
 224      *     packet_len = remainder of UDP/TCP frame
 225      * }
 226      * 1:  is_back_to_back
 227      *     Back-to-Back flag; used for timing, set for one in every 10
 228      *     packets, according to the Real documentation [1]
 229      * 1:  is_slow_data
 230      *     Slow-data flag; currently unused, according to Real docs [1]
 231      * 5:  stream_id
 232      *     ID of the stream within this particular set of streams
 233      * 1:  is_no_keyframe
 234      *     Non-keyframe flag (unset if packet belongs to a keyframe)
 235      * 32: timestamp (PTS)
 236      * if (set_id == 0x1F) {
 237      *     16: set_id (extended set-of-streams ID; see set_id)
 238      * }
 239      * if (need_reliable) {
 240      *     16: reliable_seq_no
 241      *         Reliable sequence number (see need_reliable)
 242      * }
 243      * if (stream_id == 0x3F) {
 244      *     16: stream_id (extended stream ID; see stream_id)
 245      * }
 246      * [1] https://protocol.helixcommunity.org/files/2005/devdocs/RDT_Feature_Level_20.txt
 247      * [2] http://www.wireshark.org/docs/dfref/r/rdt.html and
 248      *     http://anonsvn.wireshark.org/viewvc/trunk/epan/dissectors/packet-rdt.c
 249      */
 250     init_get_bits(&gb, buf, len << 3);
 251     len_included  = get_bits1(&gb);
 252     need_reliable = get_bits1(&gb);
 253     set_id        = get_bits(&gb, 5);
 254     skip_bits(&gb, 1);
 255     seq_no        = get_bits(&gb, 16);
 256     if (len_included)
 257         skip_bits(&gb, 16);
 258     skip_bits(&gb, 2);
 259     stream_id     = get_bits(&gb, 5);
 260     is_keyframe   = !get_bits1(&gb);
 261     timestamp     = get_bits_long(&gb, 32);
 262     if (set_id == 0x1f)
 263         set_id    = get_bits(&gb, 16);
 264     if (need_reliable)
 265         skip_bits(&gb, 16);
 266     if (stream_id == 0x1f)
 267         stream_id = get_bits(&gb, 16);
 268
 269     if (pset_id)      *pset_id      = set_id;
 270     if (pseq_no)      *pseq_no      = seq_no;
 271     if (pstream_id)   *pstream_id   = stream_id;
 272     if (pis_keyframe) *pis_keyframe = is_keyframe;
 273     if (ptimestamp)   *ptimestamp   = timestamp;
 274
 275     return consumed + (get_bits_count(&gb) >> 3);
 276 }
 277
 278 /**< return 0 on packet, no more left, 1 on packet, 1 on partial packet... */
 279 static int
 280 rdt_parse_packet (PayloadContext *rdt, AVStream *st,
 281                   AVPacket *pkt, uint32_t *timestamp,
 282                   const uint8_t *buf, int len, int flags)
 283 {
 284     int seq = 1, res;
 285     ByteIOContext pb;
 286     RMContext *rm = rdt->rmctx->priv_data;
 287
 288     if (rm->audio_pkt_cnt == 0) {
 289         int pos;
 290
 291         init_put_byte(&pb, buf, len, 0, NULL, NULL, NULL, NULL);
 292         flags = (flags & PKT_FLAG_KEY) ? 2 : 0;
 293         res = ff_rm_parse_packet (rdt->rmctx, &pb, st, len, pkt,
 294                                   &seq, &flags, timestamp);
 295         pos = url_ftell(&pb);
 296         if (res < 0)
 297             return res;
 298         if (rm->audio_pkt_cnt > 0 &&
 299             st->codec->codec_id == CODEC_ID_AAC) {
 300             memcpy (rdt->buffer, buf + pos, len - pos);
 301             rdt->rmctx->pb = av_alloc_put_byte (rdt->buffer, len - pos, 0,
 302                                                 NULL, NULL, NULL, NULL);
 303         }
 304     } else {
 305         ff_rm_retrieve_cache (rdt->rmctx, rdt->rmctx->pb, st, pkt);
 306         if (rm->audio_pkt_cnt == 0 &&
 307             st->codec->codec_id == CODEC_ID_AAC)
 308             av_freep(&rdt->rmctx->pb);
 309     }
 310     pkt->stream_index = st->index;
 311     pkt->pts = *timestamp;
 312
 313     return rm->audio_pkt_cnt > 0;
 314 }
 315
 316 int
 317 ff_rdt_parse_packet(RDTDemuxContext *s, AVPacket *pkt,
 318                     const uint8_t *buf, int len)
 319 {
 320     int seq_no, flags = 0, stream_id, set_id, is_keyframe;
 321     uint32_t timestamp;
 322     int rv= 0;
 323
 324     if (!s->parse_packet)
 325         return -1;
 326
 327     if (!buf) {
 328         /* return the next packets, if any */
 329         timestamp= 0; ///< Should not be used if buf is NULL, but should be set to the timestamp of the packet returned....
 330         rv= s->parse_packet(s->dynamic_protocol_context,
 331                             s->st, pkt, &timestamp, NULL, 0, flags);
 332         return rv;
 333     }
 334
 335     if (len < 12)
 336         return -1;
 337     rv = ff_rdt_parse_header(buf, len, &set_id, &seq_no, &stream_id, &is_keyframe, &timestamp);
 338     if (rv < 0)
 339         return rv;
 340     if (is_keyframe && (set_id != s->prev_set_id || timestamp != s->prev_timestamp)) {
 341         flags |= PKT_FLAG_KEY;
 342         s->prev_set_id    = set_id;
 343         s->prev_timestamp = timestamp;
 344     }
 345     buf += rv;
 346     len -= rv;
 347
 348     rv = s->parse_packet(s->dynamic_protocol_context,
 349                          s->st, pkt, &timestamp, buf, len, flags);
 350
 351     return rv;
 352 }
 353
 354 void
 355 ff_rdt_subscribe_rule (char *cmd, int size,
 356                        int stream_nr, int rule_nr)
 357 {
 358     av_strlcatf(cmd, size, "stream=%d;rule=%d,stream=%d;rule=%d",
 359                 stream_nr, rule_nr * 2, stream_nr, rule_nr * 2 + 1);
 360 }
 361
 362 void
 363 ff_rdt_subscribe_rule2 (RDTDemuxContext *s, char *cmd, int size,
 364                         int stream_nr, int rule_nr)
 365 {
 366     PayloadContext *rdt = s->dynamic_protocol_context;
 367
 368     rdt_load_mdpr(rdt, s->st, rule_nr * 2);
 369 }
 370
 371 static unsigned char *
 372 rdt_parse_b64buf (unsigned int *target_len, const char *p)
 373 {
 374     unsigned char *target;
 375     int len = strlen(p);
 376     if (*p == '\"') {
 377         p++;
 378         len -= 2; /* skip embracing " at start/end */
 379     }
 380     *target_len = len * 3 / 4;
 381     target = av_mallocz(*target_len + FF_INPUT_BUFFER_PADDING_SIZE);
 382     av_base64_decode(target, p, *target_len);
 383     return target;
 384 }
 385
 386 static int
 387 rdt_parse_sdp_line (AVStream *stream, PayloadContext *rdt, const char *line)
 388 {
 389     const char *p = line;
 390
 391     if (av_strstart(p, "OpaqueData:buffer;", &p)) {
 392         rdt->mlti_data = rdt_parse_b64buf(&rdt->mlti_data_size, p);
 393     } else if (av_strstart(p, "StartTime:integer;", &p))
 394         stream->first_dts = atoi(p);
 395
 396     return 0;
 397 }
 398
 399 static PayloadContext *
 400 rdt_new_extradata (void)
 401 {
 402     PayloadContext *rdt = av_mallocz(sizeof(PayloadContext));
 403
 404     av_open_input_stream(&rdt->rmctx, NULL, "", &rdt_demuxer, NULL);
 405
 406     return rdt;
 407 }
 408
 409 static void
 410 rdt_free_extradata (PayloadContext *rdt)
 411 {
 412     if (rdt->rmctx)
 413         av_close_input_stream(rdt->rmctx);
 414     av_freep(&rdt->mlti_data);
 415     av_free(rdt);
 416 }
 417
 418 #define RDT_HANDLER(n, s, t) \
 419 static RTPDynamicProtocolHandler ff_rdt_ ## n ## _handler = { \
 420     s, \
 421     t, \
 422     CODEC_ID_NONE, \
 423     rdt_parse_sdp_line, \
 424     rdt_new_extradata, \
 425     rdt_free_extradata, \
 426     rdt_parse_packet \
 427 };
 428
 429 RDT_HANDLER(live_video, "x-pn-multirate-realvideo-live", CODEC_TYPE_VIDEO);
 430 RDT_HANDLER(live_audio, "x-pn-multirate-realaudio-live", CODEC_TYPE_AUDIO);
 431 RDT_HANDLER(video,      "x-pn-realvideo",                CODEC_TYPE_VIDEO);
 432 RDT_HANDLER(audio,      "x-pn-realaudio",                CODEC_TYPE_AUDIO);
 433
 434 void av_register_rdt_dynamic_payload_handlers(void)
 435 {
 436     ff_register_dynamic_payload_handler(&ff_rdt_video_handler);
 437     ff_register_dynamic_payload_handler(&ff_rdt_audio_handler);
 438     ff_register_dynamic_payload_handler(&ff_rdt_live_video_handler);
 439     ff_register_dynamic_payload_handler(&ff_rdt_live_audio_handler);
 440 }