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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 "libavutil/avassert.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 {
40  uint16_t hash;
41  char *sdp;
42  int eof;
43 };
44 
45 static int sap_probe(AVProbeData *p)
46 {
47  if (av_strstart(p->filename, "sap:", NULL))
48  return AVPROBE_SCORE_MAX;
49  return 0;
50 }
51 
53 {
54  struct SAPState *sap = s->priv_data;
55  if (sap->sdp_ctx)
57  if (sap->ann_fd)
58  ffurl_close(sap->ann_fd);
59  av_freep(&sap->sdp);
61  return 0;
62 }
63 
65 {
66  struct SAPState *sap = s->priv_data;
67  char host[1024], path[1024], url[1024];
69  int port;
70  int ret, i;
71  AVInputFormat* infmt;
72 
73  if (!ff_network_init())
74  return AVERROR(EIO);
75 
76  av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &port,
77  path, sizeof(path), s->filename);
78  if (port < 0)
79  port = 9875;
80 
81  if (!host[0]) {
82  /* Listen for announcements on sap.mcast.net if no host was specified */
83  av_strlcpy(host, "224.2.127.254", sizeof(host));
84  }
85 
86  ff_url_join(url, sizeof(url), "udp", NULL, host, port, "?localport=%d",
87  port);
88  ret = ffurl_open(&sap->ann_fd, url, AVIO_FLAG_READ,
89  &s->interrupt_callback, 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  break;
145  }
146 
147  av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sap->sdp);
148  ffio_init_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL,
149  NULL, NULL);
150 
151  infmt = av_find_input_format("sdp");
152  if (!infmt)
153  goto fail;
155  if (!sap->sdp_ctx) {
156  ret = AVERROR(ENOMEM);
157  goto fail;
158  }
159  sap->sdp_ctx->max_delay = s->max_delay;
160  sap->sdp_ctx->pb = &sap->sdp_pb;
162 
164  sap->sdp_ctx-> codec_whitelist = av_strdup(s->codec_whitelist);
166 
167  ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);
168  if (ret < 0)
169  goto fail;
170  if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER)
172  for (i = 0; i < sap->sdp_ctx->nb_streams; i++) {
173  AVStream *st = avformat_new_stream(s, NULL);
174  if (!st) {
175  ret = AVERROR(ENOMEM);
176  goto fail;
177  }
178  st->id = i;
180  st->time_base = sap->sdp_ctx->streams[i]->time_base;
181  }
182 
183  return 0;
184 
185 fail:
186  sap_read_close(s);
187  return ret;
188 }
189 
191 {
192  struct SAPState *sap = s->priv_data;
193  int fd = ffurl_get_file_handle(sap->ann_fd);
194  int n, ret;
195  struct pollfd p = {fd, POLLIN, 0};
197 
198  if (sap->eof)
199  return AVERROR_EOF;
200 
201  while (1) {
202  n = poll(&p, 1, 0);
203  if (n <= 0 || !(p.revents & POLLIN))
204  break;
205  ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf));
206  if (ret >= 8) {
207  uint16_t hash = AV_RB16(&recvbuf[2]);
208  /* Should ideally check the source IP address, too */
209  if (recvbuf[0] & 0x04 && hash == sap->hash) {
210  /* Stream deletion */
211  sap->eof = 1;
212  return AVERROR_EOF;
213  }
214  }
215  }
216  ret = av_read_frame(sap->sdp_ctx, pkt);
217  if (ret < 0)
218  return ret;
219  if (s->ctx_flags & AVFMTCTX_NOHEADER) {
220  while (sap->sdp_ctx->nb_streams > s->nb_streams) {
221  int i = s->nb_streams;
222  AVStream *st = avformat_new_stream(s, NULL);
223  if (!st) {
224  av_free_packet(pkt);
225  return AVERROR(ENOMEM);
226  }
227  st->id = i;
229  st->time_base = sap->sdp_ctx->streams[i]->time_base;
230  }
231  }
232  return ret;
233 }
234 
236  .name = "sap",
237  .long_name = NULL_IF_CONFIG_SMALL("SAP input"),
238  .priv_data_size = sizeof(struct SAPState),
239  .read_probe = sap_probe,
240  .read_header = sap_read_header,
241  .read_packet = sap_fetch_packet,
242  .read_close = sap_read_close,
243  .flags = AVFMT_NOFILE,
244 };