sapdec.c 6.78 KB
Newer Older
Martin Storsjö's avatar
Martin Storsjö committed
1 2 3 4
/*
 * Session Announcement Protocol (RFC 2974) demuxer
 * Copyright (c) 2010 Martin Storsjo
 *
5
 * This file is part of Libav.
Martin Storsjö's avatar
Martin Storsjö committed
6
 *
7
 * Libav is free software; you can redistribute it and/or
Martin Storsjö's avatar
Martin Storsjö committed
8 9 10 11
 * 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.
 *
12
 * Libav is distributed in the hope that it will be useful,
Martin Storsjö's avatar
Martin Storsjö committed
13 14 15 16 17
 * 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
18
 * License along with Libav; if not, write to the Free Software
Martin Storsjö's avatar
Martin Storsjö committed
19 20 21 22 23 24 25 26 27
 * 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"
28
#include "avio_internal.h"
29
#include "url.h"
30 31
#if HAVE_POLL_H
#include <poll.h>
Martin Storsjö's avatar
Martin Storsjö committed
32
#endif
33
#include <sys/time.h>
Martin Storsjö's avatar
Martin Storsjö committed
34 35 36 37

struct SAPState {
    URLContext *ann_fd;
    AVFormatContext *sdp_ctx;
38
    AVIOContext sdp_pb;
Martin Storsjö's avatar
Martin Storsjö committed
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
    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)
55
        av_close_input_file(sap->sdp_ctx);
Martin Storsjö's avatar
Martin Storsjö committed
56
    if (sap->ann_fd)
57
        ffurl_close(sap->ann_fd);
Martin Storsjö's avatar
Martin Storsjö committed
58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87
    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);
88
    ret = ffurl_open(&sap->ann_fd, url, AVIO_FLAG_READ);
Martin Storsjö's avatar
Martin Storsjö committed
89 90 91 92 93 94 95
    if (ret)
        goto fail;

    while (1) {
        int addr_type, auth_len;
        int pos;

96
        ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf) - 1);
Martin Storsjö's avatar
Martin Storsjö committed
97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146
        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);
147
    ffio_init_context(&sap->sdp_pb, sap->sdp, strlen(sap->sdp), 0, NULL, NULL,
Martin Storsjö's avatar
Martin Storsjö committed
148 149 150 151 152 153 154 155 156 157 158
                  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;
159 160
    sap->sdp_ctx->pb        = &sap->sdp_pb;
    ret = avformat_open_input(&sap->sdp_ctx, "temp.sdp", infmt, NULL);
Martin Storsjö's avatar
Martin Storsjö committed
161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184
    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;
185
    int fd = ffurl_get_file_handle(sap->ann_fd);
Martin Storsjö's avatar
Martin Storsjö committed
186
    int n, ret;
187
    struct pollfd p = {fd, POLLIN, 0};
Martin Storsjö's avatar
Martin Storsjö committed
188 189 190 191 192 193
    uint8_t recvbuf[1500];

    if (sap->eof)
        return AVERROR_EOF;

    while (1) {
194 195
        n = poll(&p, 1, 0);
        if (n <= 0 || !(p.revents & POLLIN))
Martin Storsjö's avatar
Martin Storsjö committed
196
            break;
197
        ret = ffurl_read(sap->ann_fd, recvbuf, sizeof(recvbuf));
Martin Storsjö's avatar
Martin Storsjö committed
198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225
        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;
}

226
AVInputFormat ff_sap_demuxer = {
227 228 229 230 231 232 233
    .name           = "sap",
    .long_name      = NULL_IF_CONFIG_SMALL("SAP input format"),
    .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,
Martin Storsjö's avatar
Martin Storsjö committed
234 235 236
    .flags = AVFMT_NOFILE,
};