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/*
* 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"
#include "url.h"
#include "rtpdec.h"
#if HAVE_POLL_H
#include <poll.h>
#endif
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)
avformat_close_input(&sap->sdp_ctx);
if (sap->ann_fd)
ffurl_close(sap->ann_fd);
av_freep(&sap->sdp);
ff_network_close();
return 0;
}
static int sap_read_header(AVFormatContext *s)
{
struct SAPState *sap = s->priv_data;
char host[1024], path[1024], url[1024];
uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
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 = ffurl_open(&sap->ann_fd, url, AVIO_FLAG_READ,
&s->interrupt_callback, NULL);
if (ret)
goto fail;
while (1) {
int addr_type, auth_len;
int pos;
ret = ffurl_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;
sap->sdp_ctx->pb = &sap->sdp_pb;
sap->sdp_ctx->interrupt_callback = s->interrupt_callback;
ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);
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 = avformat_new_stream(s, NULL);
if (!st) {
ret = AVERROR(ENOMEM);
goto fail;
}
st->id = i;
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 = ffurl_get_file_handle(sap->ann_fd);
int n, ret;
struct pollfd p = {fd, POLLIN, 0};
uint8_t recvbuf[RTP_MAX_PACKET_LENGTH];
if (sap->eof)
return AVERROR_EOF;
while (1) {
n = poll(&p, 1, 0);
if (n <= 0 || !(p.revents & POLLIN))
break;
ret = ffurl_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 = avformat_new_stream(s, NULL);
if (!st) {
av_free_packet(pkt);
return AVERROR(ENOMEM);
}
st->id = i;
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 = {
.name = "sap",
.long_name = NULL_IF_CONFIG_SMALL("SAP input"),
.priv_data_size = sizeof(struct SAPState),
.read_probe = sap_probe,
.read_header = sap_read_header,
.read_packet = sap_fetch_packet,
.read_close = sap_read_close,
.flags = AVFMT_NOFILE,
};
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