yading@11: /*
yading@11:  * Session Announcement Protocol (RFC 2974) demuxer
yading@11:  * Copyright (c) 2010 Martin Storsjo
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "avformat.h"
yading@11: #include "libavutil/avstring.h"
yading@11: #include "libavutil/intreadwrite.h"
yading@11: #include "network.h"
yading@11: #include "os_support.h"
yading@11: #include "internal.h"
yading@11: #include "avio_internal.h"
yading@11: #include "url.h"
yading@11: #include "rtpdec.h"
yading@11: #if HAVE_POLL_H
yading@11: #include <poll.h>
yading@11: #endif
yading@11: 
yading@11: struct SAPState {
yading@11:     URLContext *ann_fd;
yading@11:     AVFormatContext *sdp_ctx;
yading@11:     AVIOContext sdp_pb;
yading@11:     uint16_t hash;
yading@11:     char *sdp;
yading@11:     int eof;
yading@11: };
yading@11: 
yading@11: static int sap_probe(AVProbeData *p)
yading@11: {
yading@11:     if (av_strstart(p->filename, "sap:", NULL))
yading@11:         return AVPROBE_SCORE_MAX;
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int sap_read_close(AVFormatContext *s)
yading@11: {
yading@11:     struct SAPState *sap = s->priv_data;
yading@11:     if (sap->sdp_ctx)
yading@11:         avformat_close_input(&sap->sdp_ctx);
yading@11:     if (sap->ann_fd)
yading@11:         ffurl_close(sap->ann_fd);
yading@11:     av_freep(&sap->sdp);
yading@11:     ff_network_close();
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int sap_read_header(AVFormatContext *s)
yading@11: {
yading@11:     struct SAPState *sap = s->priv_data;
yading@11:     char host[1024], path[1024], url[1024];
yading@11:     uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
yading@11:     int port;
yading@11:     int ret, i;
yading@11:     AVInputFormat* infmt;
yading@11: 
yading@11:     if (!ff_network_init())
yading@11:         return AVERROR(EIO);
yading@11: 
yading@11:     av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &port,
yading@11:                  path, sizeof(path), s->filename);
yading@11:     if (port < 0)
yading@11:         port = 9875;
yading@11: 
yading@11:     if (!host[0]) {
yading@11:         /* Listen for announcements on sap.mcast.net if no host was specified */
yading@11:         av_strlcpy(host, "224.2.127.254", sizeof(host));
yading@11:     }
yading@11: 
yading@11:     ff_url_join(url, sizeof(url), "udp", NULL, host, port, "?localport=%d",
yading@11:                 port);
yading@11:     ret = ffurl_open(&sap->ann_fd, url, AVIO_FLAG_READ,
yading@11:                      &s->interrupt_callback, NULL);
yading@11:     if (ret)
yading@11:         goto fail;
yading@11: 
yading@11:     while (1) {
yading@11:         int addr_type, auth_len;
yading@11:         int pos;
yading@11: 
yading@11:         ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf) - 1);
yading@11:         if (ret == AVERROR(EAGAIN))
yading@11:             continue;
yading@11:         if (ret < 0)
yading@11:             goto fail;
yading@11:         recvbuf[ret] = '\0'; /* Null terminate for easier parsing */
yading@11:         if (ret < 8) {
yading@11:             av_log(s, AV_LOG_WARNING, "Received too short packet\n");
yading@11:             continue;
yading@11:         }
yading@11: 
yading@11:         if ((recvbuf[0] & 0xe0) != 0x20) {
yading@11:             av_log(s, AV_LOG_WARNING, "Unsupported SAP version packet "
yading@11:                                       "received\n");
yading@11:             continue;
yading@11:         }
yading@11: 
yading@11:         if (recvbuf[0] & 0x04) {
yading@11:             av_log(s, AV_LOG_WARNING, "Received stream deletion "
yading@11:                                       "announcement\n");
yading@11:             continue;
yading@11:         }
yading@11:         addr_type = recvbuf[0] & 0x10;
yading@11:         auth_len  = recvbuf[1];
yading@11:         sap->hash = AV_RB16(&recvbuf[2]);
yading@11:         pos = 4;
yading@11:         if (addr_type)
yading@11:             pos += 16; /* IPv6 */
yading@11:         else
yading@11:             pos += 4; /* IPv4 */
yading@11:         pos += auth_len * 4;
yading@11:         if (pos + 4 >= ret) {
yading@11:             av_log(s, AV_LOG_WARNING, "Received too short packet\n");
yading@11:             continue;
yading@11:         }
yading@11: #define MIME "application/sdp"
yading@11:         if (strcmp(&recvbuf[pos], MIME) == 0) {
yading@11:             pos += strlen(MIME) + 1;
yading@11:         } else if (strncmp(&recvbuf[pos], "v=0\r\n", 5) == 0) {
yading@11:             // Direct SDP without a mime type
yading@11:         } else {
yading@11:             av_log(s, AV_LOG_WARNING, "Unsupported mime type %s\n",
yading@11:                                       &recvbuf[pos]);
yading@11:             continue;
yading@11:         }
yading@11: 
yading@11:         sap->sdp = av_strdup(&recvbuf[pos]);
yading@11:         break;
yading@11:     }
yading@11: 
yading@11:     av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sap->sdp);
yading@11:     ffio_init_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL,
yading@11:                   NULL, NULL);
yading@11: 
yading@11:     infmt = av_find_input_format("sdp");
yading@11:     if (!infmt)
yading@11:         goto fail;
yading@11:     sap->sdp_ctx = avformat_alloc_context();
yading@11:     if (!sap->sdp_ctx) {
yading@11:         ret = AVERROR(ENOMEM);
yading@11:         goto fail;
yading@11:     }
yading@11:     sap->sdp_ctx->max_delay = s->max_delay;
yading@11:     sap->sdp_ctx->pb        = &sap->sdp_pb;
yading@11:     sap->sdp_ctx->interrupt_callback = s->interrupt_callback;
yading@11:     ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);
yading@11:     if (ret < 0)
yading@11:         goto fail;
yading@11:     if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER)
yading@11:         s->ctx_flags |= AVFMTCTX_NOHEADER;
yading@11:     for (i = 0; i < sap->sdp_ctx->nb_streams; i++) {
yading@11:         AVStream *st = avformat_new_stream(s, NULL);
yading@11:         if (!st) {
yading@11:             ret = AVERROR(ENOMEM);
yading@11:             goto fail;
yading@11:         }
yading@11:         st->id = i;
yading@11:         avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec);
yading@11:         st->time_base = sap->sdp_ctx->streams[i]->time_base;
yading@11:     }
yading@11: 
yading@11:     return 0;
yading@11: 
yading@11: fail:
yading@11:     sap_read_close(s);
yading@11:     return ret;
yading@11: }
yading@11: 
yading@11: static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt)
yading@11: {
yading@11:     struct SAPState *sap = s->priv_data;
yading@11:     int fd = ffurl_get_file_handle(sap->ann_fd);
yading@11:     int n, ret;
yading@11:     struct pollfd p = {fd, POLLIN, 0};
yading@11:     uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
yading@11: 
yading@11:     if (sap->eof)
yading@11:         return AVERROR_EOF;
yading@11: 
yading@11:     while (1) {
yading@11:         n = poll(&p, 1, 0);
yading@11:         if (n <= 0 || !(p.revents & POLLIN))
yading@11:             break;
yading@11:         ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf));
yading@11:         if (ret >= 8) {
yading@11:             uint16_t hash = AV_RB16(&recvbuf[2]);
yading@11:             /* Should ideally check the source IP address, too */
yading@11:             if (recvbuf[0] & 0x04 && hash == sap->hash) {
yading@11:                 /* Stream deletion */
yading@11:                 sap->eof = 1;
yading@11:                 return AVERROR_EOF;
yading@11:             }
yading@11:         }
yading@11:     }
yading@11:     ret = av_read_frame(sap->sdp_ctx, pkt);
yading@11:     if (ret < 0)
yading@11:         return ret;
yading@11:     if (s->ctx_flags & AVFMTCTX_NOHEADER) {
yading@11:         while (sap->sdp_ctx->nb_streams > s->nb_streams) {
yading@11:             int i = s->nb_streams;
yading@11:             AVStream *st = avformat_new_stream(s, NULL);
yading@11:             if (!st) {
yading@11:                 av_free_packet(pkt);
yading@11:                 return AVERROR(ENOMEM);
yading@11:             }
yading@11:             st->id = i;
yading@11:             avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec);
yading@11:             st->time_base = sap->sdp_ctx->streams[i]->time_base;
yading@11:         }
yading@11:     }
yading@11:     return ret;
yading@11: }
yading@11: 
yading@11: AVInputFormat ff_sap_demuxer = {
yading@11:     .name           = "sap",
yading@11:     .long_name      = NULL_IF_CONFIG_SMALL("SAP input"),
yading@11:     .priv_data_size = sizeof(struct SAPState),
yading@11:     .read_probe     = sap_probe,
yading@11:     .read_header    = sap_read_header,
yading@11:     .read_packet    = sap_fetch_packet,
yading@11:     .read_close     = sap_read_close,
yading@11:     .flags          = AVFMT_NOFILE,
yading@11: };