Function sap_read_header

libavformat/sapdec.c:64–193

}

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];
    const AVInputFormat *infmt;
    int port;
    int ret, i;

    if (!ff_network_init())
        return AVERROR(EIO);

    av_url_split(NULL, 0, NULL, 0, host, sizeof(host), &port,
                 path, sizeof(path), s->url);
    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_whitelist(&sap->ann_fd, url, AVIO_FLAG_READ,
                               &s->interrupt_callback, NULL,
                               s->protocol_whitelist, s->protocol_blacklist, 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];