Add comment describing the RDT packet header. See discussion in "[PATCH]
[libav.git] / libavformat / 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 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"
ff13ba92 30#include "rtp_internal.h"
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31#include "rdt.h"
32#include "libavutil/base64.h"
33#include "libavutil/md5.h"
34#include "rm.h"
35#include "internal.h"
36
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37struct RDTDemuxContext {
38 AVFormatContext *ic;
39 AVStream *st;
40 void *dynamic_protocol_context;
41 DynamicPayloadPacketHandlerProc parse_packet;
42 uint32_t prev_sn, prev_ts;
43};
44
45RDTDemuxContext *
46ff_rdt_parse_open(AVFormatContext *ic, AVStream *st,
47 void *priv_data, RTPDynamicProtocolHandler *handler)
48{
49 RDTDemuxContext *s = av_mallocz(sizeof(RDTDemuxContext));
50 if (!s)
51 return NULL;
52
53 s->ic = ic;
54 s->st = st;
55 s->prev_sn = -1;
56 s->prev_ts = -1;
57 s->parse_packet = handler->parse_packet;
58 s->dynamic_protocol_context = priv_data;
59
60 return s;
61}
62
63void
64ff_rdt_parse_close(RDTDemuxContext *s)
65{
66 av_free(s);
67}
68
ed0aacc7 69struct PayloadContext {
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70 AVFormatContext *rmctx;
71 uint8_t *mlti_data;
72 unsigned int mlti_data_size;
4fce284c 73 char buffer[RTP_MAX_PACKET_LENGTH + FF_INPUT_BUFFER_PADDING_SIZE];
ed0aacc7 74};
ff13ba92 75
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76void
77ff_rdt_calc_response_and_checksum(char response[41], char chksum[9],
78 const char *challenge)
79{
80 int ch_len = strlen (challenge), i;
81 unsigned char zres[16],
82 buf[64] = { 0xa1, 0xe9, 0x14, 0x9d, 0x0e, 0x6b, 0x3b, 0x59 };
83#define XOR_TABLE_SIZE 37
84 const unsigned char xor_table[XOR_TABLE_SIZE] = {
85 0x05, 0x18, 0x74, 0xd0, 0x0d, 0x09, 0x02, 0x53,
86 0xc0, 0x01, 0x05, 0x05, 0x67, 0x03, 0x19, 0x70,
87 0x08, 0x27, 0x66, 0x10, 0x10, 0x72, 0x08, 0x09,
88 0x63, 0x11, 0x03, 0x71, 0x08, 0x08, 0x70, 0x02,
89 0x10, 0x57, 0x05, 0x18, 0x54 };
90
91 /* some (length) checks */
92 if (ch_len == 40) /* what a hack... */
93 ch_len = 32;
94 else if (ch_len > 56)
95 ch_len = 56;
96 memcpy(buf + 8, challenge, ch_len);
97
98 /* xor challenge bytewise with xor_table */
99 for (i = 0; i < XOR_TABLE_SIZE; i++)
100 buf[8 + i] ^= xor_table[i];
101
102 av_md5_sum(zres, buf, 64);
103 ff_data_to_hex(response, zres, 16);
104 for (i=0;i<32;i++) response[i] = tolower(response[i]);
105
106 /* add tail */
107 strcpy (response + 32, "01d0a8e3");
108
109 /* calculate checksum */
110 for (i = 0; i < 8; i++)
111 chksum[i] = response[i * 4];
112 chksum[8] = 0;
113}
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114
115static int
ed0aacc7 116rdt_load_mdpr (PayloadContext *rdt, AVStream *st, int rule_nr)
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117{
118 ByteIOContext *pb;
119 int size;
120 uint32_t tag;
121
122 /**
123 * Layout of the MLTI chunk:
124 * 4:MLTI
125 * 2:<number of streams>
126 * Then for each stream ([number_of_streams] times):
127 * 2:<mdpr index>
128 * 2:<number of mdpr chunks>
129 * Then for each mdpr chunk ([number_of_mdpr_chunks] times):
130 * 4:<size>
131 * [size]:<data>
132 * we skip MDPR chunks until we reach the one of the stream
133 * we're interested in, and forward that ([size]+[data]) to
134 * the RM demuxer to parse the stream-specific header data.
135 */
136 if (!rdt->mlti_data)
137 return -1;
138 url_open_buf(&pb, rdt->mlti_data, rdt->mlti_data_size, URL_RDONLY);
139 tag = get_le32(pb);
140 if (tag == MKTAG('M', 'L', 'T', 'I')) {
141 int num, chunk_nr;
142
143 /* read index of MDPR chunk numbers */
144 num = get_be16(pb);
145 if (rule_nr < 0 || rule_nr >= num)
146 return -1;
147 url_fskip(pb, rule_nr * 2);
148 chunk_nr = get_be16(pb);
149 url_fskip(pb, (num - 1 - rule_nr) * 2);
150
151 /* read MDPR chunks */
152 num = get_be16(pb);
153 if (chunk_nr >= num)
154 return -1;
155 while (chunk_nr--)
156 url_fskip(pb, get_be32(pb));
157 size = get_be32(pb);
158 } else {
159 size = rdt->mlti_data_size;
160 url_fseek(pb, 0, SEEK_SET);
161 }
162 rdt->rmctx->pb = pb;
163 if (ff_rm_read_mdpr_codecdata(rdt->rmctx, st, size) < 0)
164 return -1;
165
166 url_close_buf(pb);
167 return 0;
168}
169
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170/**
171 * Actual data handling.
172 */
173
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174int
175ff_rdt_parse_header(const uint8_t *buf, int len,
176 int *sn, int *seq, int *rn, uint32_t *ts)
4fce284c 177{
985b05d3 178 int consumed = 10;
4fce284c 179
985b05d3 180 if (len > 0 && (buf[0] < 0x40 || buf[0] > 0x42)) {
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181 buf += 9;
182 len -= 9;
183 consumed += 9;
184 }
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185 if (len < 10)
186 return -1;
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187 /**
188 * Layout of the header (in bits):
189 * 1: len_included
190 * Flag indicating whether this header includes a length field;
191 * this can be used to concatenate multiple RDT packets in a
192 * single UDP/TCP data frame and is used to precede RDT data
193 * by stream status packets
194 * 1: need_reliable
195 * Flag indicating whether this header includes a "reliable
196 * sequence number"; these are apparently sequence numbers of
197 * data packets alone. For data packets, this flag is always
198 * set, according to the Real documentation [1]
199 * 5: set_id
200 * ID of a set of streams of identical content, possibly with
201 * different codecs or bitrates
202 * 1: is_reliable
203 * Flag set for certain streams deemed less tolerable for packet
204 * loss
205 * 16: seq_no
206 * Packet sequence number; if >=0xFF00, this is a non-data packet
207 * containing stream status info, the second byte indicates the
208 * type of status packet (see wireshark docs / source code [2])
209 * if (len_included) {
210 * 16: packet_len
211 * } else {
212 * packet_len = remainder of UDP/TCP frame
213 * }
214 * 1: is_back_to_back
215 * Back-to-Back flag; used for timing, set for one in every 10
216 * packets, according to the Real documentation [1]
217 * 1: is_slow_data
218 * Slow-data flag; currently unused, according to Real docs [1]
219 * 5: stream_id
220 * ID of the stream within this particular set of streams
221 * 1: is_no_keyframe
222 * Non-keyframe flag (unset if packet belongs to a keyframe)
223 * 32: timestamp (PTS)
224 * if (set_id == 0x1F) {
225 * 16: set_id (extended set-of-streams ID; see set_id)
226 * }
227 * if (need_reliable) {
228 * 16: reliable_seq_no
229 * Reliable sequence number (see need_reliable)
230 * }
231 * if (stream_id == 0x3F) {
232 * 16: stream_id (extended stream ID; see stream_id)
233 * }
234 * [1] https://protocol.helixcommunity.org/files/2005/devdocs/RDT_Feature_Level_20.txt
235 * [2] http://www.wireshark.org/docs/dfref/r/rdt.html and
236 * http://anonsvn.wireshark.org/viewvc/trunk/epan/dissectors/packet-rdt.c
237 */
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238 if (sn) *sn = (buf[0]>>1) & 0x1f;
239 if (seq) *seq = AV_RB16(buf+1);
240 if (ts) *ts = AV_RB32(buf+4);
241 if (rn) *rn = buf[3] & 0x3f;
4fce284c 242
985b05d3 243 return consumed;
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244}
245
246/**< return 0 on packet, no more left, 1 on packet, 1 on partial packet... */
247static int
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248rdt_parse_packet (PayloadContext *rdt, AVStream *st,
249 AVPacket *pkt, uint32_t *timestamp,
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250 const uint8_t *buf, int len, int flags)
251{
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252 int seq = 1, res;
253 ByteIOContext *pb = rdt->rmctx->pb;
254 RMContext *rm = rdt->rmctx->priv_data;
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255
256 if (rm->audio_pkt_cnt == 0) {
257 int pos;
258
259 url_open_buf (&pb, buf, len, URL_RDONLY);
260 flags = (flags & PKT_FLAG_KEY) ? 2 : 0;
261 rdt->rmctx->pb = pb;
262 res = ff_rm_parse_packet (rdt->rmctx, st, len, pkt,
263 &seq, &flags, timestamp);
264 pos = url_ftell(pb);
265 url_close_buf (pb);
266 if (res < 0)
267 return res;
268 if (rm->audio_pkt_cnt > 0 &&
269 st->codec->codec_id == CODEC_ID_AAC) {
270 memcpy (rdt->buffer, buf + pos, len - pos);
271 url_open_buf (&pb, rdt->buffer, len - pos, URL_RDONLY);
272 rdt->rmctx->pb = pb;
273 }
274 } else {
275 ff_rm_retrieve_cache (rdt->rmctx, st, pkt);
276 if (rm->audio_pkt_cnt == 0 &&
277 st->codec->codec_id == CODEC_ID_AAC)
278 url_close_buf (pb);
279 }
280 pkt->stream_index = st->index;
281 pkt->pts = *timestamp;
282
283 return rm->audio_pkt_cnt > 0;
284}
285
286int
accc248f 287ff_rdt_parse_packet(RDTDemuxContext *s, AVPacket *pkt,
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288 const uint8_t *buf, int len)
289{
985b05d3 290 int seq, flags = 0, rule, sn;
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291 uint32_t timestamp;
292 int rv= 0;
293
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294 if (!s->parse_packet)
295 return -1;
296
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297 if (!buf) {
298 /* return the next packets, if any */
299 timestamp= 0; ///< Should not be used if buf is NULL, but should be set to the timestamp of the packet returned....
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300 rv= s->parse_packet(s->dynamic_protocol_context,
301 s->st, pkt, &timestamp, NULL, 0, flags);
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302 return rv;
303 }
304
305 if (len < 12)
306 return -1;
985b05d3 307 rv = ff_rdt_parse_header(buf, len, &sn, &seq, &rule, &timestamp);
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308 if (rv < 0)
309 return rv;
accc248f 310 if (!(rule & 1) && (sn != s->prev_sn || timestamp != s->prev_ts)) {
985b05d3 311 flags |= PKT_FLAG_KEY;
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312 s->prev_sn = sn;
313 s->prev_ts = timestamp;
985b05d3 314 }
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315 buf += rv;
316 len -= rv;
4fce284c 317
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318 rv = s->parse_packet(s->dynamic_protocol_context,
319 s->st, pkt, &timestamp, buf, len, flags);
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320
321 return rv;
322}
323
1256d16b 324void
ab63fb03 325ff_rdt_subscribe_rule (char *cmd, int size,
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326 int stream_nr, int rule_nr)
327{
1256d16b 328 av_strlcatf(cmd, size, "stream=%d;rule=%d,stream=%d;rule=%d",
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329 stream_nr, rule_nr * 2, stream_nr, rule_nr * 2 + 1);
330}
331
332void
accc248f 333ff_rdt_subscribe_rule2 (RDTDemuxContext *s, char *cmd, int size,
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334 int stream_nr, int rule_nr)
335{
ed0aacc7 336 PayloadContext *rdt = s->dynamic_protocol_context;
1256d16b 337
ab63fb03 338 rdt_load_mdpr(rdt, s->st, rule_nr * 2);
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339}
340
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341static unsigned char *
342rdt_parse_b64buf (unsigned int *target_len, const char *p)
343{
344 unsigned char *target;
345 int len = strlen(p);
346 if (*p == '\"') {
347 p++;
348 len -= 2; /* skip embracing " at start/end */
349 }
350 *target_len = len * 3 / 4;
351 target = av_mallocz(*target_len + FF_INPUT_BUFFER_PADDING_SIZE);
352 av_base64_decode(target, p, *target_len);
353 return target;
354}
355
356static int
ed0aacc7 357rdt_parse_sdp_line (AVStream *stream, PayloadContext *rdt, const char *line)
ff13ba92 358{
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359 const char *p = line;
360
361 if (av_strstart(p, "OpaqueData:buffer;", &p)) {
362 rdt->mlti_data = rdt_parse_b64buf(&rdt->mlti_data_size, p);
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363 } else if (av_strstart(p, "StartTime:integer;", &p))
364 stream->first_dts = atoi(p);
365
366 return 0;
367}
368
ed0aacc7 369static PayloadContext *
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370rdt_new_extradata (void)
371{
ed0aacc7 372 PayloadContext *rdt = av_mallocz(sizeof(PayloadContext));
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373
374 av_open_input_stream(&rdt->rmctx, NULL, "", &rdt_demuxer, NULL);
375
376 return rdt;
377}
378
379static void
ed0aacc7 380rdt_free_extradata (PayloadContext *rdt)
ff13ba92 381{
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382 if (rdt->rmctx)
383 av_close_input_stream(rdt->rmctx);
384 av_freep(&rdt->mlti_data);
385 av_free(rdt);
386}
387
388#define RDT_HANDLER(n, s, t) \
389static RTPDynamicProtocolHandler ff_rdt_ ## n ## _handler = { \
390 s, \
391 t, \
392 CODEC_ID_NONE, \
393 rdt_parse_sdp_line, \
394 rdt_new_extradata, \
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395 rdt_free_extradata, \
396 rdt_parse_packet \
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397};
398
399RDT_HANDLER(live_video, "x-pn-multirate-realvideo-live", CODEC_TYPE_VIDEO);
400RDT_HANDLER(live_audio, "x-pn-multirate-realaudio-live", CODEC_TYPE_AUDIO);
401RDT_HANDLER(video, "x-pn-realvideo", CODEC_TYPE_VIDEO);
402RDT_HANDLER(audio, "x-pn-realaudio", CODEC_TYPE_AUDIO);
403
404void av_register_rdt_dynamic_payload_handlers(void)
405{
406 ff_register_dynamic_payload_handler(&ff_rdt_video_handler);
407 ff_register_dynamic_payload_handler(&ff_rdt_audio_handler);
408 ff_register_dynamic_payload_handler(&ff_rdt_live_video_handler);
409 ff_register_dynamic_payload_handler(&ff_rdt_live_audio_handler);
410}