1/* 2 * Session Announcement Protocol (RFC 2974) demuxer 3 * Copyright (c) 2010 Martin Storsjo 4 * 5 * This file is part of Libav. 6 * 7 * Libav 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 * Libav 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 Libav; 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#if HAVE_POLL_H 31#include <poll.h> 32#endif 33#include <sys/time.h> 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 AVFormatParameters *ap) 65{ 66 struct SAPState *sap = s->priv_data; 67 char host[1024], path[1024], url[1024]; 68 uint8_t recvbuf[1500]; 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; 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 ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL); 163 if (ret < 0) 164 goto fail; 165 if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER) 166 s->ctx_flags |= AVFMTCTX_NOHEADER; 167 for (i = 0; i < sap->sdp_ctx->nb_streams; i++) { 168 AVStream *st = avformat_new_stream(s, NULL); 169 if (!st) { 170 ret = AVERROR(ENOMEM); 171 goto fail; 172 } 173 st->id = i; 174 avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec); 175 st->time_base = sap->sdp_ctx->streams[i]->time_base; 176 } 177 178 return 0; 179 180fail: 181 sap_read_close(s); 182 return ret; 183} 184 185static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt) 186{ 187 struct SAPState *sap = s->priv_data; 188 int fd = ffurl_get_file_handle(sap->ann_fd); 189 int n, ret; 190 struct pollfd p = {fd, POLLIN, 0}; 191 uint8_t recvbuf[1500]; 192 193 if (sap->eof) 194 return AVERROR_EOF; 195 196 while (1) { 197 n = poll(&p, 1, 0); 198 if (n <= 0 || !(p.revents & POLLIN)) 199 break; 200 ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf)); 201 if (ret >= 8) { 202 uint16_t hash = AV_RB16(&recvbuf[2]); 203 /* Should ideally check the source IP address, too */ 204 if (recvbuf[0] & 0x04 && hash == sap->hash) { 205 /* Stream deletion */ 206 sap->eof = 1; 207 return AVERROR_EOF; 208 } 209 } 210 } 211 ret = av_read_frame(sap->sdp_ctx, pkt); 212 if (ret < 0) 213 return ret; 214 if (s->ctx_flags & AVFMTCTX_NOHEADER) { 215 while (sap->sdp_ctx->nb_streams > s->nb_streams) { 216 int i = s->nb_streams; 217 AVStream *st = avformat_new_stream(s, NULL); 218 if (!st) { 219 av_free_packet(pkt); 220 return AVERROR(ENOMEM); 221 } 222 st->id = i; 223 avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec); 224 st->time_base = sap->sdp_ctx->streams[i]->time_base; 225 } 226 } 227 return ret; 228} 229 230AVInputFormat ff_sap_demuxer = { 231 .name = "sap", 232 .long_name = NULL_IF_CONFIG_SMALL("SAP input format"), 233 .priv_data_size = sizeof(struct SAPState), 234 .read_probe = sap_probe, 235 .read_header = sap_read_header, 236 .read_packet = sap_fetch_packet, 237 .read_close = sap_read_close, 238 .flags = AVFMT_NOFILE, 239}; 240 241