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(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     if (sap->ann_fd)
  58         ffurl_close(sap->ann_fd);
  59     av_freep(&sap->sdp);
  60     ff_network_close();
  61     return 0;
  62 }
  63
  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;
  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_whitelist(&sap->ann_fd, url, AVIO_FLAG_READ,
  89                                &s->interrupt_callback, NULL,
  90                                s->protocol_whitelist, s->protocol_blacklist, NULL);
  91     if (ret)
  92         goto fail;
  93
  94     while (1) {
  95         int addr_type, auth_len;
  96         int pos;
  97
  98         ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf) - 1);
  99         if (ret == AVERROR(EAGAIN))
 100             continue;
 101         if (ret < 0)
 102             goto fail;
 103         recvbuf[ret] = '\0'; /* Null terminate for easier parsing */
 104         if (ret < 8) {
 105             av_log(s, AV_LOG_WARNING, "Received too short packet\n");
 106             continue;
 107         }
 108
 109         if ((recvbuf[0] & 0xe0) != 0x20) {
 110             av_log(s, AV_LOG_WARNING, "Unsupported SAP version packet "
 111                                       "received\n");
 112             continue;
 113         }
 114
 115         if (recvbuf[0] & 0x04) {
 116             av_log(s, AV_LOG_WARNING, "Received stream deletion "
 117                                       "announcement\n");
 118             continue;
 119         }
 120         addr_type = recvbuf[0] & 0x10;
 121         auth_len  = recvbuf[1];
 122         sap->hash = AV_RB16(&recvbuf[2]);
 123         pos = 4;
 124         if (addr_type)
 125             pos += 16; /* IPv6 */
 126         else
 127             pos += 4; /* IPv4 */
 128         pos += auth_len * 4;
 129         if (pos + 4 >= ret) {
 130             av_log(s, AV_LOG_WARNING, "Received too short packet\n");
 131             continue;
 132         }
 133 #define MIME "application/sdp"
 134         if (strcmp(&recvbuf[pos], MIME) == 0) {
 135             pos += strlen(MIME) + 1;
 136         } else if (strncmp(&recvbuf[pos], "v=0\r\n", 5) == 0) {
 137             // Direct SDP without a mime type
 138         } else {
 139             av_log(s, AV_LOG_WARNING, "Unsupported mime type %s\n",
 140                                       &recvbuf[pos]);
 141             continue;
 142         }
 143
 144         sap->sdp = av_strdup(&recvbuf[pos]);
 145         break;
 146     }
 147
 148     av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sap->sdp);
 149     ffio_init_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL,
 150                   NULL, NULL);
 151
 152     infmt = av_find_input_format("sdp");
 153     if (!infmt)
 154         goto fail;
 155     sap->sdp_ctx = avformat_alloc_context();
 156     if (!sap->sdp_ctx) {
 157         ret = AVERROR(ENOMEM);
 158         goto fail;
 159     }
 160     sap->sdp_ctx->max_delay = s->max_delay;
 161     sap->sdp_ctx->pb        = &sap->sdp_pb;
 162     sap->sdp_ctx->interrupt_callback = s->interrupt_callback;
 163
 164     if ((ret = ff_copy_whiteblacklists(sap->sdp_ctx, s)) < 0)
 165         goto fail;
 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)
 171         s->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;
 179         avcodec_parameters_copy(st->codecpar, sap->sdp_ctx->streams[i]->codecpar);
 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
 190 static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt)
 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};
 196     uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
 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_packet_unref(pkt);
 225                 return AVERROR(ENOMEM);
 226             }
 227             st->id = i;
 228             avcodec_parameters_copy(st->codecpar, sap->sdp_ctx->streams[i]->codecpar);
 229             st->time_base = sap->sdp_ctx->streams[i]->time_base;
 230         }
 231     }
 232     return ret;
 233 }
 234
 235 AVInputFormat ff_sap_demuxer = {
 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 };