/* * Session Announcement Protocol (RFC 2974) demuxer * Copyright (c) 2010 Martin Storsjo * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "avformat.h" #include "libavutil/avstring.h" #include "libavutil/intreadwrite.h" #include "network.h" #include "os_support.h" #include "internal.h" #include "avio_internal.h" #if HAVE_POLL_H #include #endif #include struct SAPState { URLContext *ann_fd; AVFormatContext *sdp_ctx; AVIOContext sdp_pb; uint16_t hash; char *sdp; int eof; }; static int sap_probe(AVProbeData *p) { if (av_strstart(p->filename, "sap:", NULL)) return AVPROBE_SCORE_MAX; return 0; } static int sap_read_close(AVFormatContext *s) { struct SAPState *sap = s->priv_data; if (sap->sdp_ctx) av_close_input_stream(sap->sdp_ctx); if (sap->ann_fd) url_close(sap->ann_fd); av_freep(&sap->sdp); ff_network_close(); return 0; } static int sap_read_header(AVFormatContext *s, AVFormatParameters *ap) { struct SAPState *sap = s->priv_data; char host[1024], path[1024], url[1024]; uint8_t recvbuf[1500]; int port; int ret, i; AVInputFormat* infmt; if (!ff_network_init()) return AVERROR(EIO); av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &port, path, sizeof(path), s->filename); if (port < 0) port = 9875; if (!host[0]) { /* Listen for announcements on sap.mcast.net if no host was specified */ av_strlcpy(host, "224.2.127.254", sizeof(host)); } ff_url_join(url, sizeof(url), "udp", NULL, host, port, "?localport=%d", port); ret = url_open(&sap->ann_fd, url, URL_RDONLY); if (ret) goto fail; while (1) { int addr_type, auth_len; int pos; ret = url_read(sap->ann_fd, recvbuf, sizeof(recvbuf) - 1); if (ret == AVERROR(EAGAIN)) continue; if (ret < 0) goto fail; recvbuf[ret] = '\0'; /* Null terminate for easier parsing */ if (ret < 8) { av_log(s, AV_LOG_WARNING, "Received too short packet\n"); continue; } if ((recvbuf[0] & 0xe0) != 0x20) { av_log(s, AV_LOG_WARNING, "Unsupported SAP version packet " "received\n"); continue; } if (recvbuf[0] & 0x04) { av_log(s, AV_LOG_WARNING, "Received stream deletion " "announcement\n"); continue; } addr_type = recvbuf[0] & 0x10; auth_len = recvbuf[1]; sap->hash = AV_RB16(&recvbuf[2]); pos = 4; if (addr_type) pos += 16; /* IPv6 */ else pos += 4; /* IPv4 */ pos += auth_len * 4; if (pos + 4 >= ret) { av_log(s, AV_LOG_WARNING, "Received too short packet\n"); continue; } #define MIME "application/sdp" if (strcmp(&recvbuf[pos], MIME) == 0) { pos += strlen(MIME) + 1; } else if (strncmp(&recvbuf[pos], "v=0\r\n", 5) == 0) { // Direct SDP without a mime type } else { av_log(s, AV_LOG_WARNING, "Unsupported mime type %s\n", &recvbuf[pos]); continue; } sap->sdp = av_strdup(&recvbuf[pos]); break; } av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sap->sdp); ffio_init_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL, NULL, NULL); infmt = av_find_input_format("sdp"); if (!infmt) goto fail; sap->sdp_ctx = avformat_alloc_context(); if (!sap->sdp_ctx) { ret = AVERROR(ENOMEM); goto fail; } sap->sdp_ctx->max_delay = s->max_delay; ap->prealloced_context = 1; ret = av_open_input_stream(&sap->sdp_ctx, &sap->sdp_pb, "temp.sdp", infmt, ap); if (ret < 0) goto fail; if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER) s->ctx_flags |= AVFMTCTX_NOHEADER; for (i = 0; i < sap->sdp_ctx->nb_streams; i++) { AVStream *st = av_new_stream(s, i); if (!st) { ret = AVERROR(ENOMEM); goto fail; } avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec); st->time_base = sap->sdp_ctx->streams[i]->time_base; } return 0; fail: sap_read_close(s); return ret; } static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt) { struct SAPState *sap = s->priv_data; int fd = url_get_file_handle(sap->ann_fd); int n, ret; struct pollfd p = {fd, POLLIN, 0}; uint8_t recvbuf[1500]; if (sap->eof) return AVERROR_EOF; while (1) { n = poll(&p, 1, 0); if (n <= 0 || !(p.revents & POLLIN)) break; ret = url_read(sap->ann_fd, recvbuf, sizeof(recvbuf)); if (ret >= 8) { uint16_t hash = AV_RB16(&recvbuf[2]); /* Should ideally check the source IP address, too */ if (recvbuf[0] & 0x04 && hash == sap->hash) { /* Stream deletion */ sap->eof = 1; return AVERROR_EOF; } } } ret = av_read_frame(sap->sdp_ctx, pkt); if (ret < 0) return ret; if (s->ctx_flags & AVFMTCTX_NOHEADER) { while (sap->sdp_ctx->nb_streams > s->nb_streams) { int i = s->nb_streams; AVStream *st = av_new_stream(s, i); if (!st) { av_free_packet(pkt); return AVERROR(ENOMEM); } avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec); st->time_base = sap->sdp_ctx->streams[i]->time_base; } } return ret; } AVInputFormat ff_sap_demuxer = { "sap", NULL_IF_CONFIG_SMALL("SAP input format"), sizeof(struct SAPState), sap_probe, sap_read_header, sap_fetch_packet, sap_read_close, .flags = AVFMT_NOFILE, };