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/avstring.h" 24#include "libavutil/intreadwrite.h" 25#include "network.h" 26#include "os_support.h" 27#include "internal.h" 28#include "avio_internal.h" 29#include "url.h" 30#include "rtpdec.h" 31#if HAVE_POLL_H 32#include <poll.h> 33#endif 34 35struct SAPState { 36 URLContext *ann_fd; 37 AVFormatContext *sdp_ctx; 38 AVIOContext sdp_pb; 39 uint16_t hash; 40 char *sdp; 41 int eof; 42}; 43 44static int sap_probe(AVProbeData *p) 45{ 46 if (av_strstart(p->filename, "sap:", NULL)) 47 return AVPROBE_SCORE_MAX; 48 return 0; 49} 50 51static int sap_read_close(AVFormatContext *s) 52{ 53 struct SAPState *sap = s->priv_data; 54 if (sap->sdp_ctx) 55 avformat_close_input(&sap->sdp_ctx); 56 if (sap->ann_fd) 57 ffurl_close(sap->ann_fd); 58 av_freep(&sap->sdp); 59 ff_network_close(); 60 return 0; 61} 62 63static 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 int port; 69 int ret, i; 70 AVInputFormat* infmt; 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->filename); 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(&sap->ann_fd, url, AVIO_FLAG_READ, 88 &s->interrupt_callback, NULL); 89 if (ret) 90 goto fail; 91 92 while (1) { 93 int addr_type, auth_len; 94 int pos; 95 96 ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf) - 1); 97 if (ret == AVERROR(EAGAIN)) 98 continue; 99 if (ret < 0) 100 goto fail; 101 recvbuf[ret] = '\0'; /* Null terminate for easier parsing */ 102 if (ret < 8) { 103 av_log(s, AV_LOG_WARNING, "Received too short packet\n"); 104 continue; 105 } 106 107 if ((recvbuf[0] & 0xe0) != 0x20) { 108 av_log(s, AV_LOG_WARNING, "Unsupported SAP version packet " 109 "received\n"); 110 continue; 111 } 112 113 if (recvbuf[0] & 0x04) { 114 av_log(s, AV_LOG_WARNING, "Received stream deletion " 115 "announcement\n"); 116 continue; 117 } 118 addr_type = recvbuf[0] & 0x10; 119 auth_len = recvbuf[1]; 120 sap->hash = AV_RB16(&recvbuf[2]); 121 pos = 4; 122 if (addr_type) 123 pos += 16; /* IPv6 */ 124 else 125 pos += 4; /* IPv4 */ 126 pos += auth_len * 4; 127 if (pos + 4 >= ret) { 128 av_log(s, AV_LOG_WARNING, "Received too short packet\n"); 129 continue; 130 } 131#define MIME "application/sdp" 132 if (strcmp(&recvbuf[pos], MIME) == 0) { 133 pos += strlen(MIME) + 1; 134 } else if (strncmp(&recvbuf[pos], "v=0\r\n", 5) == 0) { 135 // Direct SDP without a mime type 136 } else { 137 av_log(s, AV_LOG_WARNING, "Unsupported mime type %s\n", 138 &recvbuf[pos]); 139 continue; 140 } 141 142 sap->sdp = av_strdup(&recvbuf[pos]); 143 break; 144 } 145 146 av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sap->sdp); 147 ffio_init_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL, 148 NULL, NULL); 149 150 infmt = av_find_input_format("sdp"); 151 if (!infmt) 152 goto fail; 153 sap->sdp_ctx = avformat_alloc_context(); 154 if (!sap->sdp_ctx) { 155 ret = AVERROR(ENOMEM); 156 goto fail; 157 } 158 sap->sdp_ctx->max_delay = s->max_delay; 159 sap->sdp_ctx->pb = &sap->sdp_pb; 160 sap->sdp_ctx->interrupt_callback = s->interrupt_callback; 161 ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL); 162 if (ret < 0) 163 goto fail; 164 if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER) 165 s->ctx_flags |= AVFMTCTX_NOHEADER; 166 for (i = 0; i < sap->sdp_ctx->nb_streams; i++) { 167 AVStream *st = avformat_new_stream(s, NULL); 168 if (!st) { 169 ret = AVERROR(ENOMEM); 170 goto fail; 171 } 172 st->id = i; 173 avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec); 174 st->time_base = sap->sdp_ctx->streams[i]->time_base; 175 } 176 177 return 0; 178 179fail: 180 sap_read_close(s); 181 return ret; 182} 183 184static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt) 185{ 186 struct SAPState *sap = s->priv_data; 187 int fd = ffurl_get_file_handle(sap->ann_fd); 188 int n, ret; 189 struct pollfd p = {fd, POLLIN, 0}; 190 uint8_t recvbuf[RTP_MAX_PACKET_LENGTH]; 191 192 if (sap->eof) 193 return AVERROR_EOF; 194 195 while (1) { 196 n = poll(&p, 1, 0); 197 if (n <= 0 || !(p.revents & POLLIN)) 198 break; 199 ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf)); 200 if (ret >= 8) { 201 uint16_t hash = AV_RB16(&recvbuf[2]); 202 /* Should ideally check the source IP address, too */ 203 if (recvbuf[0] & 0x04 && hash == sap->hash) { 204 /* Stream deletion */ 205 sap->eof = 1; 206 return AVERROR_EOF; 207 } 208 } 209 } 210 ret = av_read_frame(sap->sdp_ctx, pkt); 211 if (ret < 0) 212 return ret; 213 if (s->ctx_flags & AVFMTCTX_NOHEADER) { 214 while (sap->sdp_ctx->nb_streams > s->nb_streams) { 215 int i = s->nb_streams; 216 AVStream *st = avformat_new_stream(s, NULL); 217 if (!st) { 218 av_free_packet(pkt); 219 return AVERROR(ENOMEM); 220 } 221 st->id = i; 222 avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec); 223 st->time_base = sap->sdp_ctx->streams[i]->time_base; 224 } 225 } 226 return ret; 227} 228 229AVInputFormat ff_sap_demuxer = { 230 .name = "sap", 231 .long_name = NULL_IF_CONFIG_SMALL("SAP input"), 232 .priv_data_size = sizeof(struct SAPState), 233 .read_probe = sap_probe, 234 .read_header = sap_read_header, 235 .read_packet = sap_fetch_packet, 236 .read_close = sap_read_close, 237 .flags = AVFMT_NOFILE, 238}; 239