FFmpeg
sapdec.c
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1 /*
2  * Session Announcement Protocol (RFC 2974) demuxer
3  * Copyright (c) 2010 Martin Storsjo
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 #include "avformat.h"
23 #include "demux.h"
24 #include "libavutil/avstring.h"
25 #include "libavutil/intreadwrite.h"
26 #include "network.h"
27 #include "os_support.h"
28 #include "internal.h"
29 #include "avio_internal.h"
30 #include "url.h"
31 #include "rtpdec.h"
32 #if HAVE_POLL_H
33 #include <poll.h>
34 #endif
35 
36 struct SAPState {
37  URLContext *ann_fd;
38  AVFormatContext *sdp_ctx;
39  FFIOContext sdp_pb;
40  uint16_t hash;
41  char *sdp;
42  int eof;
43 };
44 
45 static int sap_probe(const AVProbeData *p)
46 {
47  if (av_strstart(p->filename, "sap:", NULL))
48  return AVPROBE_SCORE_MAX;
49  return 0;
50 }
51 
52 static int sap_read_close(AVFormatContext *s)
53 {
54  struct SAPState *sap = s->priv_data;
55  if (sap->sdp_ctx)
56  avformat_close_input(&sap->sdp_ctx);
57  ffurl_closep(&sap->ann_fd);
58  av_freep(&sap->sdp);
59  ff_network_close();
60  return 0;
61 }
62 
63 static int sap_read_header(AVFormatContext *s)
64 {
65  struct SAPState *sap = s->priv_data;
66  char host[1024], path[1024], url[1024];
67  uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
68  const AVInputFormat *infmt;
69  int port;
70  int ret, i;
71 
72  if (!ff_network_init())
73  return AVERROR(EIO);
74 
75  av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &port,
76  path, sizeof(path), s->url);
77  if (port < 0)
78  port = 9875;
79 
80  if (!host[0]) {
81  /* Listen for announcements on sap.mcast.net if no host was specified */
82  av_strlcpy(host, "224.2.127.254", sizeof(host));
83  }
84 
85  ff_url_join(url, sizeof(url), "udp", NULL, host, port, "?localport=%d",
86  port);
87  ret = ffurl_open_whitelist(&sap->ann_fd, url, AVIO_FLAG_READ,
88  &s->interrupt_callback, NULL,
89  s->protocol_whitelist, s->protocol_blacklist, NULL);
90  if (ret)
91  goto fail;
92 
93  while (1) {
94  int addr_type, auth_len;
95  int pos;
96 
97  ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf) - 1);
98  if (ret == AVERROR(EAGAIN))
99  continue;
100  if (ret < 0)
101  goto fail;
102  recvbuf[ret] = '\0'; /* Null terminate for easier parsing */
103  if (ret < 8) {
104  av_log(s, AV_LOG_WARNING, "Received too short packet\n");
105  continue;
106  }
107 
108  if ((recvbuf[0] & 0xe0) != 0x20) {
109  av_log(s, AV_LOG_WARNING, "Unsupported SAP version packet "
110  "received\n");
111  continue;
112  }
113 
114  if (recvbuf[0] & 0x04) {
115  av_log(s, AV_LOG_WARNING, "Received stream deletion "
116  "announcement\n");
117  continue;
118  }
119  addr_type = recvbuf[0] & 0x10;
120  auth_len = recvbuf[1];
121  sap->hash = AV_RB16(&recvbuf[2]);
122  pos = 4;
123  if (addr_type)
124  pos += 16; /* IPv6 */
125  else
126  pos += 4; /* IPv4 */
127  pos += auth_len * 4;
128  if (pos + 4 >= ret) {
129  av_log(s, AV_LOG_WARNING, "Received too short packet\n");
130  continue;
131  }
132 #define MIME "application/sdp"
133  if (strcmp(&recvbuf[pos], MIME) == 0) {
134  pos += strlen(MIME) + 1;
135  } else if (strncmp(&recvbuf[pos], "v=0\r\n", 5) == 0) {
136  // Direct SDP without a mime type
137  } else {
138  av_log(s, AV_LOG_WARNING, "Unsupported mime type %s\n",
139  &recvbuf[pos]);
140  continue;
141  }
142 
143  sap->sdp = av_strdup(&recvbuf[pos]);
144  if (!sap->sdp) {
145  ret = AVERROR(ENOMEM);
146  goto fail;
147  }
148  break;
149  }
150 
151  av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sap->sdp);
152  ffio_init_read_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp));
153 
154  infmt = av_find_input_format("sdp");
155  if (!infmt)
156  goto fail;
157  sap->sdp_ctx = avformat_alloc_context();
158  if (!sap->sdp_ctx) {
159  ret = AVERROR(ENOMEM);
160  goto fail;
161  }
162  sap->sdp_ctx->max_delay = s->max_delay;
163  sap->sdp_ctx->pb = &sap->sdp_pb.pub;
164  sap->sdp_ctx->interrupt_callback = s->interrupt_callback;
165 
166  if ((ret = ff_copy_whiteblacklists(sap->sdp_ctx, s)) < 0)
167  goto fail;
168 
169  ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);
170  if (ret < 0)
171  goto fail;
172  if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER)
173  s->ctx_flags |= AVFMTCTX_NOHEADER;
174  for (i = 0; i < sap->sdp_ctx->nb_streams; i++) {
175  AVStream *st = avformat_new_stream(s, NULL);
176  if (!st) {
177  ret = AVERROR(ENOMEM);
178  goto fail;
179  }
180  st->id = i;
181  avcodec_parameters_copy(st->codecpar, sap->sdp_ctx->streams[i]->codecpar);
182  st->time_base = sap->sdp_ctx->streams[i]->time_base;
183  }
184 
185  return 0;
186 
187 fail:
188  sap_read_close(s);
189  return ret;
190 }
191 
192 static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt)
193 {
194  struct SAPState *sap = s->priv_data;
195  int fd = ffurl_get_file_handle(sap->ann_fd);
196  int n, ret;
197  struct pollfd p = {fd, POLLIN, 0};
198  uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
199 
200  if (sap->eof)
201  return AVERROR_EOF;
202 
203  while (1) {
204  n = poll(&p, 1, 0);
205  if (n <= 0 || !(p.revents & POLLIN))
206  break;
207  ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf));
208  if (ret >= 8) {
209  uint16_t hash = AV_RB16(&recvbuf[2]);
210  /* Should ideally check the source IP address, too */
211  if (recvbuf[0] & 0x04 && hash == sap->hash) {
212  /* Stream deletion */
213  sap->eof = 1;
214  return AVERROR_EOF;
215  }
216  }
217  }
218  ret = av_read_frame(sap->sdp_ctx, pkt);
219  if (ret < 0)
220  return ret;
221  if (s->ctx_flags & AVFMTCTX_NOHEADER) {
222  while (sap->sdp_ctx->nb_streams > s->nb_streams) {
223  int i = s->nb_streams;
224  AVStream *st = avformat_new_stream(s, NULL);
225  if (!st) {
226  return AVERROR(ENOMEM);
227  }
228  st->id = i;
229  avcodec_parameters_copy(st->codecpar, sap->sdp_ctx->streams[i]->codecpar);
230  st->time_base = sap->sdp_ctx->streams[i]->time_base;
231  }
232  }
233  return ret;
234 }
235 
236 const FFInputFormat ff_sap_demuxer = {
237  .p.name = "sap",
238  .p.long_name = NULL_IF_CONFIG_SMALL("SAP input"),
239  .p.flags = AVFMT_NOFILE,
240  .priv_data_size = sizeof(struct SAPState),
241  .read_probe = sap_probe,
242  .read_header = sap_read_header,
243  .read_packet = sap_fetch_packet,
244  .read_close = sap_read_close,
245 };
SAPState::hash
uint16_t hash
Definition: sapdec.c:40
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:186
sap_read_header
static int sap_read_header(AVFormatContext *s)
Definition: sapdec.c:63
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
SAPState::ann_fd
URLContext * ann_fd
Definition: sapdec.c:37
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const struct AVCodec *c)
Add a new stream to a media file.
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
ff_sap_demuxer
const FFInputFormat ff_sap_demuxer
Definition: sapdec.c:236
AVFormatContext::streams
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1323
SAPState
Definition: sapdec.c:36
AV_LOG_VERBOSE
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:196
MIME
#define MIME
ffio_init_read_context
void ffio_init_read_context(FFIOContext *s, const uint8_t *buffer, int buffer_size)
Wrap a buffer in an AVIOContext for reading.
Definition: aviobuf.c:98
ff_network_close
void ff_network_close(void)
Definition: network.c:116
av_read_frame
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
Definition: demux.c:1525
hash
uint8_t hash[HASH_SIZE]
Definition: movenc.c:57
sap_read_close
static int sap_read_close(AVFormatContext *s)
Definition: sapdec.c:52
os_support.h
FFIOContext
Definition: avio_internal.h:28
ff_network_init
int ff_network_init(void)
Definition: network.c:58
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:463
avformat_close_input
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
Definition: demux.c:362
AVFormatContext::interrupt_callback
AVIOInterruptCB interrupt_callback
Custom interrupt callbacks for the I/O layer.
Definition: avformat.h:1528
fail
#define fail()
Definition: checkasm.h:179
pkt
AVPacket * pkt
Definition: movenc.c:59
AVInputFormat
Definition: avformat.h:548
AVFormatContext::ctx_flags
int ctx_flags
Flags signalling stream properties.
Definition: avformat.h:1304
avformat_open_input
int avformat_open_input(AVFormatContext **ps, const char *url, const AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
Definition: demux.c:214
ffurl_open_whitelist
int ffurl_open_whitelist(URLContext **puc, const char *filename, int flags, const AVIOInterruptCB *int_cb, AVDictionary **options, const char *whitelist, const char *blacklist, URLContext *parent)
Create an URLContext for accessing to the resource indicated by url, and open it.
Definition: avio.c:361
SAPState::sdp
char * sdp
Definition: sapdec.c:41
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:198
SAPState::eof
int eof
Definition: sapdec.c:42
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:553
AVProbeData::filename
const char * filename
Definition: avformat.h:452
ff_url_join
int ff_url_join(char *str, int size, const char *proto, const char *authorization, const char *hostname, int port, const char *fmt,...)
Definition: url.c:40
SAPState::sdp_pb
FFIOContext sdp_pb
Definition: sapdec.c:39
AVFormatContext
Format I/O context.
Definition: avformat.h:1255
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:766
AVStream::time_base
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented.
Definition: avformat.h:782
NULL
#define NULL
Definition: coverity.c:32
AVFMTCTX_NOHEADER
#define AVFMTCTX_NOHEADER
signal that no header is present (streams are added dynamically)
Definition: avformat.h:1206
ff_copy_whiteblacklists
int ff_copy_whiteblacklists(AVFormatContext *dst, const AVFormatContext *src)
Copies the whilelists from one context to the other.
Definition: avformat.c:898
AVFormatContext::pb
AVIOContext * pb
I/O context.
Definition: avformat.h:1297
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:451
rtpdec.h
AVFormatContext::nb_streams
unsigned int nb_streams
Number of elements in AVFormatContext.streams.
Definition: avformat.h:1311
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:106
avformat_alloc_context
AVFormatContext * avformat_alloc_context(void)
Allocate an AVFormatContext.
Definition: options.c:160
FFIOContext::pub
AVIOContext pub
Definition: avio_internal.h:29
AVFMT_NOFILE
#define AVFMT_NOFILE
Demuxer will use avio_open, no opened file should be provided by the caller.
Definition: avformat.h:468
SAPState::sdp_ctx
AVFormatContext * sdp_ctx
Definition: sapdec.c:38
FFInputFormat::p
AVInputFormat p
The public AVInputFormat.
Definition: demux.h:41
av_strstart
int av_strstart(const char *str, const char *pfx, const char **ptr)
Return non-zero if pfx is a prefix of str.
Definition: avstring.c:36
URLContext
Definition: url.h:35
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:255
avio_internal.h
av_url_split
void av_url_split(char *proto, int proto_size, char *authorization, int authorization_size, char *hostname, int hostname_size, int *port_ptr, char *path, int path_size, const char *url)
Split a URL string into components.
Definition: utils.c:358
url.h
AVFormatContext::max_delay
int max_delay
Definition: avformat.h:1400
demux.h
ffurl_closep
int ffurl_closep(URLContext **hh)
Close the resource accessed by the URLContext h, and free the memory used by it.
Definition: avio.c:587
sap_probe
static int sap_probe(const AVProbeData *p)
Definition: sapdec.c:45
AVStream::id
int id
Format-specific stream ID.
Definition: avformat.h:755
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:743
pos
unsigned int pos
Definition: spdifenc.c:413
avformat.h
network.h
RTP_MAX_PACKET_LENGTH
#define RTP_MAX_PACKET_LENGTH
Definition: rtpdec.h:37
sap_fetch_packet
static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt)
Definition: sapdec.c:192
av_find_input_format
const AVInputFormat * av_find_input_format(const char *short_name)
Find AVInputFormat based on the short name of the input format.
Definition: format.c:145
AVIO_FLAG_READ
#define AVIO_FLAG_READ
read-only
Definition: avio.h:617
av_strdup
char * av_strdup(const char *s)
Duplicate a string.
Definition: mem.c:270
read_probe
static int read_probe(const AVProbeData *p)
Definition: cdg.c:30
AVPacket
This structure stores compressed data.
Definition: packet.h:499
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
FFInputFormat
Definition: demux.h:37
av_strlcpy
size_t av_strlcpy(char *dst, const char *src, size_t size)
Copy the string src to dst, but no more than size - 1 bytes, and null-terminate dst.
Definition: avstring.c:85
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
avstring.h
ffurl_get_file_handle
int ffurl_get_file_handle(URLContext *h)
Return the file descriptor associated with this URL.
Definition: avio.c:813
avcodec_parameters_copy
int avcodec_parameters_copy(AVCodecParameters *dst, const AVCodecParameters *src)
Copy the contents of src to dst.
Definition: codec_par.c:106
AV_RB16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:98
ffurl_read
static int ffurl_read(URLContext *h, uint8_t *buf, int size)
Read up to size bytes from the resource accessed by h, and store the read bytes in buf.
Definition: url.h:181
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