libavformat/sapdec.c

   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 {
  37     URLContext *ann_fd;
  38     AVFormatContext *sdp_ctx;
  39     AVIOContext 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     int port;
  69     int ret, i;
  70     ff_const59 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->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_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL,
 153                   NULL, NULL);
 154
 155     infmt = av_find_input_format("sdp");
 156     if (!infmt)
 157         goto fail;
 158     sap->sdp_ctx = avformat_alloc_context();
 159     if (!sap->sdp_ctx) {
 160         ret = AVERROR(ENOMEM);
 161         goto fail;
 162     }
 163     sap->sdp_ctx->max_delay = s->max_delay;
 164     sap->sdp_ctx->pb        = &sap->sdp_pb;
 165     sap->sdp_ctx->interrupt_callback = s->interrupt_callback;
 166
 167     if ((ret = ff_copy_whiteblacklists(sap->sdp_ctx, s)) < 0)
 168         goto fail;
 169
 170     ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);
 171     if (ret < 0)
 172         goto fail;
 173     if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER)
 174         s->ctx_flags |= AVFMTCTX_NOHEADER;
 175     for (i = 0; i < sap->sdp_ctx->nb_streams; i++) {
 176         AVStream *st = avformat_new_stream(s, NULL);
 177         if (!st) {
 178             ret = AVERROR(ENOMEM);
 179             goto fail;
 180         }
 181         st->id = i;
 182         avcodec_parameters_copy(st->codecpar, sap->sdp_ctx->streams[i]->codecpar);
 183         st->time_base = sap->sdp_ctx->streams[i]->time_base;
 184     }
 185
 186     return 0;
 187
 188 fail:
 189     sap_read_close(s);
 190     return ret;
 191 }
 192
 193 static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt)
 194 {
 195     struct SAPState *sap = s->priv_data;
 196     int fd = ffurl_get_file_handle(sap->ann_fd);
 197     int n, ret;
 198     struct pollfd p = {fd, POLLIN, 0};
 199     uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
 200
 201     if (fd < 0)
 202         return fd;
 203
 204     if (sap->eof)
 205         return AVERROR_EOF;
 206
 207     while (1) {
 208         n = poll(&p, 1, 0);
 209         if (n <= 0 || !(p.revents & POLLIN))
 210             break;
 211         ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf));
 212         if (ret >= 8) {
 213             uint16_t hash = AV_RB16(&recvbuf[2]);
 214             /* Should ideally check the source IP address, too */
 215             if (recvbuf[0] & 0x04 && hash == sap->hash) {
 216                 /* Stream deletion */
 217                 sap->eof = 1;
 218                 return AVERROR_EOF;
 219             }
 220         }
 221     }
 222     ret = av_read_frame(sap->sdp_ctx, pkt);
 223     if (ret < 0)
 224         return ret;
 225     if (s->ctx_flags & AVFMTCTX_NOHEADER) {
 226         while (sap->sdp_ctx->nb_streams > s->nb_streams) {
 227             int i = s->nb_streams;
 228             AVStream *st = avformat_new_stream(s, NULL);
 229             if (!st) {
 230                 return AVERROR(ENOMEM);
 231             }
 232             st->id = i;
 233             avcodec_parameters_copy(st->codecpar, sap->sdp_ctx->streams[i]->codecpar);
 234             st->time_base = sap->sdp_ctx->streams[i]->time_base;
 235         }
 236     }
 237     return ret;
 238 }
 239
 240 AVInputFormat ff_sap_demuxer = {
 241     .name           = "sap",
 242     .long_name      = NULL_IF_CONFIG_SMALL("SAP input"),
 243     .priv_data_size = sizeof(struct SAPState),
 244     .read_probe     = sap_probe,
 245     .read_header    = sap_read_header,
 246     .read_packet    = sap_fetch_packet,
 247     .read_close     = sap_read_close,
 248     .flags          = AVFMT_NOFILE,
 249 };