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libavformat/sapdec.c

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00001 /*
00002  * Session Announcement Protocol (RFC 2974) demuxer
00003  * Copyright (c) 2010 Martin Storsjo
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avformat.h"
00023 #include "libavutil/avstring.h"
00024 #include "libavutil/intreadwrite.h"
00025 #include "network.h"
00026 #include "os_support.h"
00027 #include "internal.h"
00028 #include "avio_internal.h"
00029 #include "url.h"
00030 #if HAVE_POLL_H
00031 #include <poll.h>
00032 #endif
00033 #include <sys/time.h>
00034 
00035 struct SAPState {
00036     URLContext *ann_fd;
00037     AVFormatContext *sdp_ctx;
00038     AVIOContext sdp_pb;
00039     uint16_t hash;
00040     char *sdp;
00041     int eof;
00042 };
00043 
00044 static int sap_probe(AVProbeData *p)
00045 {
00046     if (av_strstart(p->filename, "sap:", NULL))
00047         return AVPROBE_SCORE_MAX;
00048     return 0;
00049 }
00050 
00051 static int sap_read_close(AVFormatContext *s)
00052 {
00053     struct SAPState *sap = s->priv_data;
00054     if (sap->sdp_ctx)
00055         av_close_input_file(sap->sdp_ctx);
00056     if (sap->ann_fd)
00057         ffurl_close(sap->ann_fd);
00058     av_freep(&sap->sdp);
00059     ff_network_close();
00060     return 0;
00061 }
00062 
00063 static int sap_read_header(AVFormatContext *s,
00064                            AVFormatParameters *ap)
00065 {
00066     struct SAPState *sap = s->priv_data;
00067     char host[1024], path[1024], url[1024];
00068     uint8_t recvbuf[1500];
00069     int port;
00070     int ret, i;
00071     AVInputFormat* infmt;
00072 
00073     if (!ff_network_init())
00074         return AVERROR(EIO);
00075 
00076     av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &port,
00077                  path, sizeof(path), s->filename);
00078     if (port < 0)
00079         port = 9875;
00080 
00081     if (!host[0]) {
00082         /* Listen for announcements on sap.mcast.net if no host was specified */
00083         av_strlcpy(host, "224.2.127.254", sizeof(host));
00084     }
00085 
00086     ff_url_join(url, sizeof(url), "udp", NULL, host, port, "?localport=%d",
00087                 port);
00088     ret = ffurl_open(&sap->ann_fd, url, AVIO_RDONLY);
00089     if (ret)
00090         goto fail;
00091 
00092     while (1) {
00093         int addr_type, auth_len;
00094         int pos;
00095 
00096         ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf) - 1);
00097         if (ret == AVERROR(EAGAIN))
00098             continue;
00099         if (ret < 0)
00100             goto fail;
00101         recvbuf[ret] = '\0'; /* Null terminate for easier parsing */
00102         if (ret < 8) {
00103             av_log(s, AV_LOG_WARNING, "Received too short packet\n");
00104             continue;
00105         }
00106 
00107         if ((recvbuf[0] & 0xe0) != 0x20) {
00108             av_log(s, AV_LOG_WARNING, "Unsupported SAP version packet "
00109                                       "received\n");
00110             continue;
00111         }
00112 
00113         if (recvbuf[0] & 0x04) {
00114             av_log(s, AV_LOG_WARNING, "Received stream deletion "
00115                                       "announcement\n");
00116             continue;
00117         }
00118         addr_type = recvbuf[0] & 0x10;
00119         auth_len  = recvbuf[1];
00120         sap->hash = AV_RB16(&recvbuf[2]);
00121         pos = 4;
00122         if (addr_type)
00123             pos += 16; /* IPv6 */
00124         else
00125             pos += 4; /* IPv4 */
00126         pos += auth_len * 4;
00127         if (pos + 4 >= ret) {
00128             av_log(s, AV_LOG_WARNING, "Received too short packet\n");
00129             continue;
00130         }
00131 #define MIME "application/sdp"
00132         if (strcmp(&recvbuf[pos], MIME) == 0) {
00133             pos += strlen(MIME) + 1;
00134         } else if (strncmp(&recvbuf[pos], "v=0\r\n", 5) == 0) {
00135             // Direct SDP without a mime type
00136         } else {
00137             av_log(s, AV_LOG_WARNING, "Unsupported mime type %s\n",
00138                                       &recvbuf[pos]);
00139             continue;
00140         }
00141 
00142         sap->sdp = av_strdup(&recvbuf[pos]);
00143         break;
00144     }
00145 
00146     av_log(s, AV_LOG_VERBOSE, "SDP:\n%s\n", sap->sdp);
00147     ffio_init_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL,
00148                   NULL, NULL);
00149 
00150     infmt = av_find_input_format("sdp");
00151     if (!infmt)
00152         goto fail;
00153     sap->sdp_ctx = avformat_alloc_context();
00154     if (!sap->sdp_ctx) {
00155         ret = AVERROR(ENOMEM);
00156         goto fail;
00157     }
00158     sap->sdp_ctx->max_delay = s->max_delay;
00159     sap->sdp_ctx->pb        = &sap->sdp_pb;
00160     ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);
00161     if (ret < 0)
00162         goto fail;
00163     if (sap->sdp_ctx->ctx_flags & AVFMTCTX_NOHEADER)
00164         s->ctx_flags |= AVFMTCTX_NOHEADER;
00165     for (i = 0; i < sap->sdp_ctx->nb_streams; i++) {
00166         AVStream *st = av_new_stream(s, i);
00167         if (!st) {
00168             ret = AVERROR(ENOMEM);
00169             goto fail;
00170         }
00171         avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec);
00172         st->time_base = sap->sdp_ctx->streams[i]->time_base;
00173     }
00174 
00175     return 0;
00176 
00177 fail:
00178     sap_read_close(s);
00179     return ret;
00180 }
00181 
00182 static int sap_fetch_packet(AVFormatContext *s, AVPacket *pkt)
00183 {
00184     struct SAPState *sap = s->priv_data;
00185     int fd = ffurl_get_file_handle(sap->ann_fd);
00186     int n, ret;
00187     struct pollfd p = {fd, POLLIN, 0};
00188     uint8_t recvbuf[1500];
00189 
00190     if (sap->eof)
00191         return AVERROR_EOF;
00192 
00193     while (1) {
00194         n = poll(&p, 1, 0);
00195         if (n <= 0 || !(p.revents & POLLIN))
00196             break;
00197         ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf));
00198         if (ret >= 8) {
00199             uint16_t hash = AV_RB16(&recvbuf[2]);
00200             /* Should ideally check the source IP address, too */
00201             if (recvbuf[0] & 0x04 && hash == sap->hash) {
00202                 /* Stream deletion */
00203                 sap->eof = 1;
00204                 return AVERROR_EOF;
00205             }
00206         }
00207     }
00208     ret = av_read_frame(sap->sdp_ctx, pkt);
00209     if (ret < 0)
00210         return ret;
00211     if (s->ctx_flags & AVFMTCTX_NOHEADER) {
00212         while (sap->sdp_ctx->nb_streams > s->nb_streams) {
00213             int i = s->nb_streams;
00214             AVStream *st = av_new_stream(s, i);
00215             if (!st) {
00216                 av_free_packet(pkt);
00217                 return AVERROR(ENOMEM);
00218             }
00219             avcodec_copy_context(st->codec, sap->sdp_ctx->streams[i]->codec);
00220             st->time_base = sap->sdp_ctx->streams[i]->time_base;
00221         }
00222     }
00223     return ret;
00224 }
00225 
00226 AVInputFormat ff_sap_demuxer = {
00227     "sap",
00228     NULL_IF_CONFIG_SMALL("SAP input format"),
00229     sizeof(struct SAPState),
00230     sap_probe,
00231     sap_read_header,
00232     sap_fetch_packet,
00233     sap_read_close,
00234     .flags = AVFMT_NOFILE,
00235 };
00236 

Generated on Wed Apr 11 2012 07:31:37 for FFmpeg by  doxygen 1.7.1