rtsp.c

rtsp协议的主要实现代码

    RTSPStream *rtsp_st;
    struct in_addr sdp_ip;
    int ttl;

#ifdef DEBUG
    printf("sdp: %c='%s'\n", letter, buf);
#endif

    p = buf;
    switch(letter) {
    case 'c':
        get_word(buf1, sizeof(buf1), &p);
        if (strcmp(buf1, "IN") != 0)
            return;
        get_word(buf1, sizeof(buf1), &p);
        if (strcmp(buf1, "IP4") != 0)
            return;
        get_word_sep(buf1, sizeof(buf1), "/", &p);
        if (inet_aton(buf1, &sdp_ip) == 0)
            return;
        ttl = 16;
        if (*p == '/') {
            p++;
            get_word_sep(buf1, sizeof(buf1), "/", &p);
            ttl = atoi(buf1);
        }
        if (s->nb_streams == 0) {
            s1->default_ip = sdp_ip;
            s1->default_ttl = ttl;
        } else {
            st = s->streams[s->nb_streams - 1];
            rtsp_st = st->priv_data;
            rtsp_st->sdp_ip = sdp_ip;
            rtsp_st->sdp_ttl = ttl;
        }
        break;
    case 's':
        pstrcpy(s->title, sizeof(s->title), p);
        break;
    case 'i':
        if (s->nb_streams == 0) {
            pstrcpy(s->comment, sizeof(s->comment), p);
            break;
        }
        break;
    case 'm':
        /* new stream */
        get_word(st_type, sizeof(st_type), &p);
        if (!strcmp(st_type, "audio")) {
            codec_type = CODEC_TYPE_AUDIO;
        } else if (!strcmp(st_type, "video")) {
            codec_type = CODEC_TYPE_VIDEO;
        } else {
            return;
        }
        rtsp_st = av_mallocz(sizeof(RTSPStream));
        if (!rtsp_st)
            return;
        rtsp_st->stream_index = -1;
        dynarray_add(&rt->rtsp_streams, &rt->nb_rtsp_streams, rtsp_st);

        rtsp_st->sdp_ip = s1->default_ip;
        rtsp_st->sdp_ttl = s1->default_ttl;

        get_word(buf1, sizeof(buf1), &p); /* port */
        rtsp_st->sdp_port = atoi(buf1);

        get_word(buf1, sizeof(buf1), &p); /* protocol (ignored) */

        /* XXX: handle list of formats */
        get_word(buf1, sizeof(buf1), &p); /* format list */
        rtsp_st->sdp_payload_type = atoi(buf1);

        if (!strcmp(AVRtpPayloadTypes[rtsp_st->sdp_payload_type].enc_name, "MP2T")) {
            /* no corresponding stream */
        } else {
            st = av_new_stream(s, 0);
            if (!st)
                return;
            st->priv_data = rtsp_st;
            rtsp_st->stream_index = st->index;
            st->codec->codec_type = codec_type;
            if (rtsp_st->sdp_payload_type < RTP_PT_PRIVATE) {
                /* if standard payload type, we can find the codec right now */
                rtp_get_codec_info(st->codec, rtsp_st->sdp_payload_type);
            }
        }
        /* put a default control url */
        pstrcpy(rtsp_st->control_url, sizeof(rtsp_st->control_url), s->filename);
        break;
    case 'a':
        if (strstart(p, "control:", &p) && s->nb_streams > 0) {
            char proto[32];
            /* get the control url */
            st = s->streams[s->nb_streams - 1];
            rtsp_st = st->priv_data;

            /* XXX: may need to add full url resolution */
            url_split(proto, sizeof(proto), NULL, 0, NULL, 0, NULL, NULL, 0, p);
            if (proto[0] == '\0') {
                /* relative control URL */
                pstrcat(rtsp_st->control_url, sizeof(rtsp_st->control_url), "/");
                pstrcat(rtsp_st->control_url, sizeof(rtsp_st->control_url), p);
            } else {
                pstrcpy(rtsp_st->control_url, sizeof(rtsp_st->control_url), p);
            }
        } else if (strstart(p, "rtpmap:", &p)) {
            /* NOTE: rtpmap is only supported AFTER the 'm=' tag */
            get_word(buf1, sizeof(buf1), &p);
            payload_type = atoi(buf1);
            for(i = 0; i < s->nb_streams;i++) {
                st = s->streams[i];
                rtsp_st = st->priv_data;
                if (rtsp_st->sdp_payload_type == payload_type) {
                    sdp_parse_rtpmap(st->codec, rtsp_st, payload_type, p);
                }
            }
        } else if (strstart(p, "fmtp:", &p)) {
            /* NOTE: fmtp is only supported AFTER the 'a=rtpmap:xxx' tag */
            get_word(buf1, sizeof(buf1), &p);
            payload_type = atoi(buf1);
            for(i = 0; i < s->nb_streams;i++) {
                st = s->streams[i];
                rtsp_st = st->priv_data;
                if (rtsp_st->sdp_payload_type == payload_type) {
                    if(rtsp_st->dynamic_handler && rtsp_st->dynamic_handler->parse_sdp_a_line) {
                        if(!rtsp_st->dynamic_handler->parse_sdp_a_line(st, rtsp_st->dynamic_protocol_context, buf)) {
                            sdp_parse_fmtp(st, p);
                        }
                    } else {
                        sdp_parse_fmtp(st, p);
                    }
                }
            }
        } else if(strstart(p, "framesize:", &p)) {
            // let dynamic protocol handlers have a stab at the line.
            get_word(buf1, sizeof(buf1), &p);
            payload_type = atoi(buf1);
            for(i = 0; i < s->nb_streams;i++) {
                st = s->streams[i];
                rtsp_st = st->priv_data;
                if (rtsp_st->sdp_payload_type == payload_type) {
                    if(rtsp_st->dynamic_handler && rtsp_st->dynamic_handler->parse_sdp_a_line) {
                        rtsp_st->dynamic_handler->parse_sdp_a_line(st, rtsp_st->dynamic_protocol_context, buf);
                    }
                }
            }
        } else if(strstart(p, "range:", &p)) {
            int64_t start, end;

            // this is so that seeking on a streamed file can work.
            rtsp_parse_range_npt(p, &start, &end);
            s->start_time= start;
            s->duration= (end==AV_NOPTS_VALUE)?AV_NOPTS_VALUE:end-start; // AV_NOPTS_VALUE means live broadcast (and can't seek)
        }
        break;
    }
}

static int sdp_parse(AVFormatContext *s, const char *content)
{
    const char *p;
    int letter;
    char buf[1024], *q;
    SDPParseState sdp_parse_state, *s1 = &sdp_parse_state;

    memset(s1, 0, sizeof(SDPParseState));
    p = content;
    for(;;) {
        skip_spaces(&p);
        letter = *p;
        if (letter == '\0')
            break;
        p++;
        if (*p != '=')
            goto next_line;
        p++;
        /* get the content */
        q = buf;
        while (*p != '\n' && *p != '\r' && *p != '\0') {
            if ((q - buf) < sizeof(buf) - 1)
                *q++ = *p;
            p++;
        }
        *q = '\0';
        sdp_parse_line(s, s1, letter, buf);
    next_line:
        while (*p != '\n' && *p != '\0')
            p++;
        if (*p == '\n')
            p++;
    }
    return 0;
}

static void rtsp_parse_range(int *min_ptr, int *max_ptr, const char **pp)
{
    const char *p;
    int v;

    p = *pp;
    skip_spaces(&p);
    v = strtol(p, (char **)&p, 10);
    if (*p == '-') {
        p++;
        *min_ptr = v;
        v = strtol(p, (char **)&p, 10);
        *max_ptr = v;
    } else {
        *min_ptr = v;
        *max_ptr = v;
    }
    *pp = p;
}

/* XXX: only one transport specification is parsed */
static void rtsp_parse_transport(RTSPHeader *reply, const char *p)
{
    char transport_protocol[16];
    char profile[16];
    char lower_transport[16];
    char parameter[16];
    RTSPTransportField *th;
    char buf[256];

    reply->nb_transports = 0;

    for(;;) {
        skip_spaces(&p);
        if (*p == '\0')
            break;

        th = &reply->transports[reply->nb_transports];

        get_word_sep(transport_protocol, sizeof(transport_protocol),
                     "/", &p);
        if (*p == '/')
            p++;
        get_word_sep(profile, sizeof(profile), "/;,", &p);
        lower_transport[0] = '\0';
        if (*p == '/') {
            p++;
            get_word_sep(lower_transport, sizeof(lower_transport),
                         ";,", &p);
        }
        if (!strcasecmp(lower_transport, "TCP"))
            th->protocol = RTSP_PROTOCOL_RTP_TCP;
        else
            th->protocol = RTSP_PROTOCOL_RTP_UDP;

        if (*p == ';')
            p++;
        /* get each parameter */
        while (*p != '\0' && *p != ',') {
            get_word_sep(parameter, sizeof(parameter), "=;,", &p);
            if (!strcmp(parameter, "port")) {
                if (*p == '=') {
                    p++;
                    rtsp_parse_range(&th->port_min, &th->port_max, &p);
                }
            } else if (!strcmp(parameter, "client_port")) {
                if (*p == '=') {
                    p++;
                    rtsp_parse_range(&th->client_port_min,
                                     &th->client_port_max, &p);
                }
            } else if (!strcmp(parameter, "server_port")) {
                if (*p == '=') {
                    p++;
                    rtsp_parse_range(&th->server_port_min,
                                     &th->server_port_max, &p);
                }
            } else if (!strcmp(parameter, "interleaved")) {
                if (*p == '=') {
                    p++;
                    rtsp_parse_range(&th->interleaved_min,
                                     &th->interleaved_max, &p);
                }
            } else if (!strcmp(parameter, "multicast")) {
                if (th->protocol == RTSP_PROTOCOL_RTP_UDP)
                    th->protocol = RTSP_PROTOCOL_RTP_UDP_MULTICAST;
            } else if (!strcmp(parameter, "ttl")) {
                if (*p == '=') {
                    p++;
                    th->ttl = strtol(p, (char **)&p, 10);
                }
            } else if (!strcmp(parameter, "destination")) {
                struct in_addr ipaddr;

                if (*p == '=') {
                    p++;
                    get_word_sep(buf, sizeof(buf), ";,", &p);
                    if (inet_aton(buf, &ipaddr))
                        th->destination = ntohl(ipaddr.s_addr);
                }
            }
            while (*p != ';' && *p != '\0' && *p != ',')
                p++;
            if (*p == ';')
                p++;
        }
        if (*p == ',')
            p++;

        reply->nb_transports++;
    }
}

void rtsp_parse_line(RTSPHeader *reply, const char *buf)
{
    const char *p;

    /* NOTE: we do case independent match for broken servers */
    p = buf;
    if (stristart(p, "Session:", &p)) {
        get_word_sep(reply->session_id, sizeof(reply->session_id), ";", &p);
    } else if (stristart(p, "Content-Length:", &p)) {
        reply->content_length = strtol(p, NULL, 10);
    } else if (stristart(p, "Transport:", &p)) {
        rtsp_parse_transport(reply, p);
    } else if (stristart(p, "CSeq:", &p)) {
        reply->seq = strtol(p, NULL, 10);
    } else if (stristart(p, "Range:", &p)) {
        rtsp_parse_range_npt(p, &reply->range_start, &reply->range_end);
    }
}

static int url_readbuf(URLContext *h, unsigned char *buf, int size)
{
    int ret, len;

    len = 0;
    while (len < size) {
        ret = url_read(h, buf+len, size-len);
        if (ret < 1)
            return ret;
        len += ret;
    }
    return len;
}

/* skip a RTP/TCP interleaved packet */
static void rtsp_skip_packet(AVFormatContext *s)
{
    RTSPState *rt = s->priv_data;
    int ret, len, len1;
    uint8_t buf[1024];

    ret = url_readbuf(rt->rtsp_hd, buf, 3);
    if (ret != 3)
        return;
    len = (buf[1] << 8) | buf[2];
#ifdef DEBUG
    printf("skipping RTP packet len=%d\n", len);
#endif
    /* skip payload */
    while (len > 0) {
        len1 = len;
        if (len1 > sizeof(buf))
            len1 = sizeof(buf);
        ret = url_readbuf(rt->rtsp_hd, buf, len1);
        if (ret != len1)
            return;
        len -= len1;
    }
}

static void rtsp_send_cmd(AVFormatContext *s,
                          const char *cmd, RTSPHeader *reply,
                          unsigned char **content_ptr)
{
    RTSPState *rt = s->priv_data;