FFmpeg: libavformat/sapdec.c Source File

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libavformat

sapdec.c

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1 /*

2 * Session Announcement Protocol (RFC 2974) demuxer

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 */

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

36 struct SAPState {

37 URLContext *ann_fd;

38 AVFormatContext *sdp_ctx;

39 AVIOContext sdp_pb;

40 uint16_t hash;

41 char *sdp;

42 int eof;

43 };

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 }

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 if (sap->ann_fd)

58 ffurl_close(sap->ann_fd);

59 av_freep(&sap->sdp);

60 ff_network_close();

61 return 0;

62 }

64 static int sap_read_header(AVFormatContext *s)

65 {

66 struct SAPState *sap = s->priv_data;

67 char host[1024], path[1024], url[1024];

68 uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];

69 int port;

70 int ret, i;

71 AVInputFormat* infmt;

73 if (!ff_network_init())

74 return AVERROR(EIO);

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;

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 }

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;

93 while (1) {

94 int addr_type, auth_len;

95 int pos;

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円'; /* 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;

154 sap->sdp_ctx = avformat_alloc_context();

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;

161 sap->sdp_ctx->interrupt_callback = s->interrupt_callback;

162

163 if ((ret = ff_copy_whitelists(sap->sdp_ctx, s)) < 0)

164 goto fail;

165

166 ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);

167 if (ret < 0)

168 goto fail;

169 if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER)

170 s->ctx_flags |= AVFMTCTX_NOHEADER;

171 for (i = 0; i < sap->sdp_ctx->nb_streams; i++) {

172 AVStream *st = avformat_new_stream(s, NULL);

173 if (!st) {

174 ret = AVERROR(ENOMEM);

175 goto fail;

176 }

177 st->id = i;

178 avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec);

179 st->time_base = sap->sdp_ctx->streams[i]->time_base;

180 }

181

182 return 0;

183

184 fail:

185 sap_read_close(s);

186 return ret;

187 }

188

189 static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt)

190 {

191 struct SAPState *sap = s->priv_data;

192 int fd = ffurl_get_file_handle(sap->ann_fd);

193 int n, ret;

194 struct pollfd p = {fd, POLLIN, 0};

195 uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];

196

197 if (sap->eof)

198 return AVERROR_EOF;

199

200 while (1) {

201 n = poll(&p, 1, 0);

202 if (n <= 0 || !(p.revents & POLLIN))

203 break;

204 ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf));

205 if (ret >= 8) {

206 uint16_t hash = AV_RB16(&recvbuf[2]);

207 /* Should ideally check the source IP address, too */

208 if (recvbuf[0] & 0x04 && hash == sap->hash) {

209 /* Stream deletion */

210 sap->eof = 1;

211 return AVERROR_EOF;

212 }

213 }

214 }

215 ret = av_read_frame(sap->sdp_ctx, pkt);

216 if (ret < 0)

217 return ret;

218 if (s->ctx_flags & AVFMTCTX_NOHEADER) {

219 while (sap->sdp_ctx->nb_streams > s->nb_streams) {

220 int i = s->nb_streams;

221 AVStream *st = avformat_new_stream(s, NULL);

222 if (!st) {

223 av_free_packet(pkt);

224 return AVERROR(ENOMEM);

225 }

226 st->id = i;

227 avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec);

228 st->time_base = sap->sdp_ctx->streams[i]->time_base;

229 }

230 }

231 return ret;

232 }

233

234 AVInputFormat ff_sap_demuxer = {

235 .name = "sap",

236 .long_name = NULL_IF_CONFIG_SMALL("SAP input"),

237 .priv_data_size = sizeof(struct SAPState),

238 .read_probe = sap_probe,

239 .read_header = sap_read_header,

240 .read_packet = sap_fetch_packet,

241 .read_close = sap_read_close,

242 .flags = AVFMT_NOFILE,

243 };

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