PeerStreamer

/*

 * Realmedia RTSP protocol (RDT) support.

 * Copyright (c) 2007 Ronald S. Bultje

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg 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.

 *

 * FFmpeg 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 FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * @brief Realmedia RTSP protocol (RDT) support

 * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>

 */

#include "avformat.h"

#include "libavutil/avstring.h"

#include "rtpdec.h"

#include "rdt.h"

#include "libavutil/base64.h"

#include "libavutil/md5.h"

#include "rm.h"

#include "internal.h"

#include "avio_internal.h"

#include "libavcodec/get_bits.h"

struct RDTDemuxContext {

    AVFormatContext *ic; /**< the containing (RTSP) demux context */

    /** Each RDT stream-set (represented by one RTSPStream) can contain

     * multiple streams (of the same content, but with possibly different

     * codecs/bitrates). Each such stream is represented by one AVStream

     * in the AVFormatContext, and this variable points to the offset in

     * that array such that the first is the first stream of this set. */

    AVStream **streams;

    int n_streams; /**< streams with identifical content in this set */

    void *dynamic_protocol_context;

    DynamicPayloadPacketHandlerProc parse_packet;

    uint32_t prev_timestamp;

    int prev_set_id, prev_stream_id;

};

RDTDemuxContext *

ff_rdt_parse_open(AVFormatContext *ic, int first_stream_of_set_idx,

                  void *priv_data, RTPDynamicProtocolHandler *handler)

{

    RDTDemuxContext *s = av_mallocz(sizeof(RDTDemuxContext));

    if (!s)

        return NULL;

    s->ic = ic;

    s->streams = &ic->streams[first_stream_of_set_idx];

    do {

        s->n_streams++;

    } while (first_stream_of_set_idx + s->n_streams < ic->nb_streams &&

             s->streams[s->n_streams]->id == s->streams[0]->id);

    s->prev_set_id    = -1;

    s->prev_stream_id = -1;

    s->prev_timestamp = -1;

    s->parse_packet = handler ? handler->parse_packet : NULL;

    s->dynamic_protocol_context = priv_data;

    return s;

}

void

ff_rdt_parse_close(RDTDemuxContext *s)

{

    av_free(s);

}

struct PayloadContext {

    AVFormatContext *rmctx;

    int nb_rmst;

    RMStream **rmst;

    uint8_t *mlti_data;

    unsigned int mlti_data_size;

    char buffer[RTP_MAX_PACKET_LENGTH + FF_INPUT_BUFFER_PADDING_SIZE];

    int audio_pkt_cnt; /**< remaining audio packets in rmdec */

};

void

ff_rdt_calc_response_and_checksum(char response[41], char chksum[9],

                                  const char *challenge)

{

    int ch_len = strlen (challenge), i;

    unsigned char zres[16],

        buf[64] = { 0xa1, 0xe9, 0x14, 0x9d, 0x0e, 0x6b, 0x3b, 0x59 };

#define XOR_TABLE_SIZE 37

    const unsigned char xor_table[XOR_TABLE_SIZE] = {

        0x05, 0x18, 0x74, 0xd0, 0x0d, 0x09, 0x02, 0x53,

        0xc0, 0x01, 0x05, 0x05, 0x67, 0x03, 0x19, 0x70,

        0x08, 0x27, 0x66, 0x10, 0x10, 0x72, 0x08, 0x09,

        0x63, 0x11, 0x03, 0x71, 0x08, 0x08, 0x70, 0x02,

        0x10, 0x57, 0x05, 0x18, 0x54 };

    /* some (length) checks */

    if (ch_len == 40) /* what a hack... */

        ch_len = 32;

    else if (ch_len > 56)

        ch_len = 56;

    memcpy(buf + 8, challenge, ch_len);

    /* xor challenge bytewise with xor_table */

    for (i = 0; i < XOR_TABLE_SIZE; i++)

        buf[8 + i] ^= xor_table[i];

    av_md5_sum(zres, buf, 64);

    ff_data_to_hex(response, zres, 16, 1);

    /* add tail */

    strcpy (response + 32, "01d0a8e3");

    /* calculate checksum */

    for (i = 0; i < 8; i++)

        chksum[i] = response[i * 4];

    chksum[8] = 0;

}

static int

rdt_load_mdpr (PayloadContext *rdt, AVStream *st, int rule_nr)

{

    AVIOContext pb;

    int size;

    uint32_t tag;

    /**

     * Layout of the MLTI chunk:

     * 4: MLTI

     * 2: number of streams

     * Then for each stream ([number_of_streams] times):

     *     2: mdpr index

     * 2: number of mdpr chunks

     * Then for each mdpr chunk ([number_of_mdpr_chunks] times):

     *     4: size

     *     [size]: data

     * we skip MDPR chunks until we reach the one of the stream

     * we're interested in, and forward that ([size]+[data]) to

     * the RM demuxer to parse the stream-specific header data.

     */

    if (!rdt->mlti_data)

        return -1;

    ffio_init_context(&pb, rdt->mlti_data, rdt->mlti_data_size, 0,

                  NULL, NULL, NULL, NULL);

    tag = avio_rl32(&pb);

    if (tag == MKTAG('M', 'L', 'T', 'I')) {

        int num, chunk_nr;

        /* read index of MDPR chunk numbers */

        num = avio_rb16(&pb);

        if (rule_nr < 0 || rule_nr >= num)

            return -1;

        avio_skip(&pb, rule_nr * 2);

        chunk_nr = avio_rb16(&pb);

        avio_skip(&pb, (num - 1 - rule_nr) * 2);

        /* read MDPR chunks */

        num = avio_rb16(&pb);

        if (chunk_nr >= num)

            return -1;

        while (chunk_nr--)

            avio_skip(&pb, avio_rb32(&pb));

        size = avio_rb32(&pb);

    } else {

        size = rdt->mlti_data_size;

        avio_seek(&pb, 0, SEEK_SET);

    }

    if (ff_rm_read_mdpr_codecdata(rdt->rmctx, &pb, st, rdt->rmst[st->index], size) < 0)

        return -1;

    return 0;

}

/**

 * Actual data handling.

 */

int

ff_rdt_parse_header(const uint8_t *buf, int len,

                    int *pset_id, int *pseq_no, int *pstream_id,

                    int *pis_keyframe, uint32_t *ptimestamp)

{

    GetBitContext gb;

    int consumed = 0, set_id, seq_no, stream_id, is_keyframe,

        len_included, need_reliable;

    uint32_t timestamp;

    /* skip status packets */

    while (len >= 5 && buf[1] == 0xFF /* status packet */) {

        int pkt_len;

        if (!(buf[0] & 0x80))

            return -1; /* not followed by a data packet */

        pkt_len = AV_RB16(buf+3);

        buf += pkt_len;

        len -= pkt_len;

        consumed += pkt_len;

    }

    if (len < 16)

        return -1;

    /**

     * Layout of the header (in bits):

     * 1:  len_included

     *     Flag indicating whether this header includes a length field;

     *     this can be used to concatenate multiple RDT packets in a

     *     single UDP/TCP data frame and is used to precede RDT data

     *     by stream status packets

     * 1:  need_reliable

     *     Flag indicating whether this header includes a "reliable

     *     sequence number"; these are apparently sequence numbers of

     *     data packets alone. For data packets, this flag is always

     *     set, according to the Real documentation [1]

     * 5:  set_id

     *     ID of a set of streams of identical content, possibly with

     *     different codecs or bitrates

     * 1:  is_reliable

     *     Flag set for certain streams deemed less tolerable for packet

     *     loss

     * 16: seq_no

     *     Packet sequence number; if >=0xFF00, this is a non-data packet

     *     containing stream status info, the second byte indicates the

     *     type of status packet (see wireshark docs / source code [2])

     * if (len_included) {

     *     16: packet_len

     * } else {

     *     packet_len = remainder of UDP/TCP frame

     * }

     * 1:  is_back_to_back

     *     Back-to-Back flag; used for timing, set for one in every 10

     *     packets, according to the Real documentation [1]

     * 1:  is_slow_data

     *     Slow-data flag; currently unused, according to Real docs [1]

     * 5:  stream_id

     *     ID of the stream within this particular set of streams

     * 1:  is_no_keyframe

     *     Non-keyframe flag (unset if packet belongs to a keyframe)

     * 32: timestamp (PTS)

     * if (set_id == 0x1F) {

     *     16: set_id (extended set-of-streams ID; see set_id)

     * }

     * if (need_reliable) {

     *     16: reliable_seq_no

     *         Reliable sequence number (see need_reliable)

     * }

     * if (stream_id == 0x3F) {

     *     16: stream_id (extended stream ID; see stream_id)

     * }

     * [1] https://protocol.helixcommunity.org/files/2005/devdocs/RDT_Feature_Level_20.txt

     * [2] http://www.wireshark.org/docs/dfref/r/rdt.html and

     *     http://anonsvn.wireshark.org/viewvc/trunk/epan/dissectors/packet-rdt.c

     */

    init_get_bits(&gb, buf, len << 3);

    len_included  = get_bits1(&gb);

    need_reliable = get_bits1(&gb);

    set_id        = get_bits(&gb, 5);

    skip_bits(&gb, 1);

    seq_no        = get_bits(&gb, 16);

    if (len_included)

        skip_bits(&gb, 16);

    skip_bits(&gb, 2);

    stream_id     = get_bits(&gb, 5);

    is_keyframe   = !get_bits1(&gb);

    timestamp     = get_bits_long(&gb, 32);

    if (set_id == 0x1f)

        set_id    = get_bits(&gb, 16);

    if (need_reliable)

        skip_bits(&gb, 16);

    if (stream_id == 0x1f)

        stream_id = get_bits(&gb, 16);

    if (pset_id)      *pset_id      = set_id;

    if (pseq_no)      *pseq_no      = seq_no;

    if (pstream_id)   *pstream_id   = stream_id;

    if (pis_keyframe) *pis_keyframe = is_keyframe;

    if (ptimestamp)   *ptimestamp   = timestamp;

    return consumed + (get_bits_count(&gb) >> 3);

}

/**< return 0 on packet, no more left, 1 on packet, 1 on partial packet... */

static int

rdt_parse_packet (AVFormatContext *ctx, PayloadContext *rdt, AVStream *st,

                  AVPacket *pkt, uint32_t *timestamp,

                  const uint8_t *buf, int len, int flags)

{

    int seq = 1, res;

    AVIOContext pb;

    if (rdt->audio_pkt_cnt == 0) {

        int pos;

        ffio_init_context(&pb, buf, len, 0, NULL, NULL, NULL, NULL);

        flags = (flags & RTP_FLAG_KEY) ? 2 : 0;

        res = ff_rm_parse_packet (rdt->rmctx, &pb, st, rdt->rmst[st->index], len, pkt,

                                  &seq, flags, *timestamp);

        pos = avio_tell(&pb);

        if (res < 0)

            return res;

        if (res > 0) {

            if (st->codec->codec_id == CODEC_ID_AAC) {

                memcpy (rdt->buffer, buf + pos, len - pos);

                rdt->rmctx->pb = avio_alloc_context (rdt->buffer, len - pos, 0,

                                                    NULL, NULL, NULL, NULL);

            }

            goto get_cache;

        }

    } else {

get_cache:

        rdt->audio_pkt_cnt =

            ff_rm_retrieve_cache (rdt->rmctx, rdt->rmctx->pb,

                                  st, rdt->rmst[st->index], pkt);

        if (rdt->audio_pkt_cnt == 0 &&

            st->codec->codec_id == CODEC_ID_AAC)

            av_freep(&rdt->rmctx->pb);

    }

    pkt->stream_index = st->index;

    pkt->pts = *timestamp;

    return rdt->audio_pkt_cnt > 0;

}

int

ff_rdt_parse_packet(RDTDemuxContext *s, AVPacket *pkt,

                    uint8_t **bufptr, int len)

{

    uint8_t *buf = bufptr ? *bufptr : NULL;

    int seq_no, flags = 0, stream_id, set_id, is_keyframe;

    uint32_t timestamp;

    int rv= 0;

    if (!s->parse_packet)

        return -1;

    if (!buf && s->prev_stream_id != -1) {

        /* return the next packets, if any */

        timestamp= 0; ///< Should not be used if buf is NULL, but should be set to the timestamp of the packet returned....

        rv= s->parse_packet(s->ic, s->dynamic_protocol_context,

                            s->streams[s->prev_stream_id],

                            pkt, &timestamp, NULL, 0, flags);

        return rv;

    }

    if (len < 12)

        return -1;

    rv = ff_rdt_parse_header(buf, len, &set_id, &seq_no, &stream_id, &is_keyframe, &timestamp);

    if (rv < 0)

        return rv;

    if (is_keyframe &&

        (set_id != s->prev_set_id || timestamp != s->prev_timestamp ||

         stream_id != s->prev_stream_id)) {

        flags |= RTP_FLAG_KEY;

        s->prev_set_id    = set_id;

        s->prev_timestamp = timestamp;

    }

    s->prev_stream_id = stream_id;

    buf += rv;

    len -= rv;

     if (s->prev_stream_id >= s->n_streams) {

         s->prev_stream_id = -1;

         return -1;

     }

    rv = s->parse_packet(s->ic, s->dynamic_protocol_context,

                         s->streams[s->prev_stream_id],

                         pkt, &timestamp, buf, len, flags);

    return rv;

}

void

ff_rdt_subscribe_rule (char *cmd, int size,

                       int stream_nr, int rule_nr)

{

    av_strlcatf(cmd, size, "stream=%d;rule=%d,stream=%d;rule=%d",

                stream_nr, rule_nr * 2, stream_nr, rule_nr * 2 + 1);

}

static unsigned char *

rdt_parse_b64buf (unsigned int *target_len, const char *p)

{

    unsigned char *target;

    int len = strlen(p);

    if (*p == '\"') {

        p++;

        len -= 2; /* skip embracing " at start/end */

    }

    *target_len = len * 3 / 4;

    target = av_mallocz(*target_len + FF_INPUT_BUFFER_PADDING_SIZE);

    av_base64_decode(target, p, *target_len);

    return target;

}

static int

rdt_parse_sdp_line (AVFormatContext *s, int st_index,

                    PayloadContext *rdt, const char *line)

{

    AVStream *stream = s->streams[st_index];

    const char *p = line;

    if (av_strstart(p, "OpaqueData:buffer;", &p)) {

        rdt->mlti_data = rdt_parse_b64buf(&rdt->mlti_data_size, p);

    } else if (av_strstart(p, "StartTime:integer;", &p))

        stream->first_dts = atoi(p);

    else if (av_strstart(p, "ASMRuleBook:string;", &p)) {

        int n, first = -1;

        for (n = 0; n < s->nb_streams; n++)

            if (s->streams[n]->id == stream->id) {

                int count = s->streams[n]->index + 1;

                if (first == -1) first = n;

                if (rdt->nb_rmst < count) {

                    RMStream **rmst= av_realloc(rdt->rmst, count*sizeof(*rmst));

                    if (!rmst)

                        return AVERROR(ENOMEM);

                    memset(rmst + rdt->nb_rmst, 0,

                           (count - rdt->nb_rmst) * sizeof(*rmst));

                    rdt->rmst    = rmst;

                    rdt->nb_rmst = count;

                }

                rdt->rmst[s->streams[n]->index] = ff_rm_alloc_rmstream();

                rdt_load_mdpr(rdt, s->streams[n], (n - first) * 2);

                if (s->streams[n]->codec->codec_id == CODEC_ID_AAC)

                    s->streams[n]->codec->frame_size = 1; // FIXME

           }

    }

    return 0;

}

static void

real_parse_asm_rule(AVStream *st, const char *p, const char *end)

{

    do {

        /* can be either averagebandwidth= or AverageBandwidth= */

        if (sscanf(p, " %*1[Aa]verage%*1[Bb]andwidth=%d", &st->codec->bit_rate) == 1)

            break;

        if (!(p = strchr(p, ',')) || p > end)

            p = end;

        p++;

    } while (p < end);

}

static AVStream *

add_dstream(AVFormatContext *s, AVStream *orig_st)

{

    AVStream *st;

    if (!(st = av_new_stream(s, orig_st->id)))

        return NULL;

    st->codec->codec_type = orig_st->codec->codec_type;

    st->first_dts         = orig_st->first_dts;

    return st;

}

static void

real_parse_asm_rulebook(AVFormatContext *s, AVStream *orig_st,

                        const char *p)

{

    const char *end;

    int n_rules = 0, odd = 0;

    AVStream *st;

    /**

     * The ASMRuleBook contains a list of comma-separated strings per rule,

     * and each rule is separated by a ;. The last one also has a ; at the

     * end so we can use it as delimiter.

     * Every rule occurs twice, once for when the RTSP packet header marker

     * is set and once for if it isn't. We only read the first because we

     * don't care much (that's what the "odd" variable is for).

     * Each rule contains a set of one or more statements, optionally

     * preceeded by a single condition. If there's a condition, the rule

     * starts with a '#'. Multiple conditions are merged between brackets,

     * so there are never multiple conditions spread out over separate

     * statements. Generally, these conditions are bitrate limits (min/max)

     * for multi-bitrate streams.

     */

    if (*p == '\"') p++;

    while (1) {

        if (!(end = strchr(p, ';')))

            break;

        if (!odd && end != p) {

            if (n_rules > 0)

                st = add_dstream(s, orig_st);

            else

                st = orig_st;

            if (!st)

                break;

            real_parse_asm_rule(st, p, end);

            n_rules++;

        }

        p = end + 1;

        odd ^= 1;

    }

}

void

ff_real_parse_sdp_a_line (AVFormatContext *s, int stream_index,

                          const char *line)

{

    const char *p = line;

    if (av_strstart(p, "ASMRuleBook:string;", &p))

        real_parse_asm_rulebook(s, s->streams[stream_index], p);

}

static PayloadContext *

rdt_new_context (void)

{

    PayloadContext *rdt = av_mallocz(sizeof(PayloadContext));

    av_open_input_stream(&rdt->rmctx, NULL, "", &ff_rdt_demuxer, NULL);

    return rdt;

}

static void

rdt_free_context (PayloadContext *rdt)

{

    int i;

    for (i = 0; i < rdt->nb_rmst; i++)

        if (rdt->rmst[i]) {

            ff_rm_free_rmstream(rdt->rmst[i]);

            av_freep(&rdt->rmst[i]);

        }

    if (rdt->rmctx)

        av_close_input_stream(rdt->rmctx);

    av_freep(&rdt->mlti_data);

    av_freep(&rdt->rmst);

    av_free(rdt);

}

#define RDT_HANDLER(n, s, t) \

static RTPDynamicProtocolHandler ff_rdt_ ## n ## _handler = { \

    .enc_name         = s, \

    .codec_type       = t, \

    .codec_id         = CODEC_ID_NONE, \

    .parse_sdp_a_line = rdt_parse_sdp_line, \

    .open             = rdt_new_context, \

    .close            = rdt_free_context, \

    .parse_packet     = rdt_parse_packet \

}

RDT_HANDLER(live_video, "x-pn-multirate-realvideo-live", AVMEDIA_TYPE_VIDEO);

RDT_HANDLER(live_audio, "x-pn-multirate-realaudio-live", AVMEDIA_TYPE_AUDIO);

RDT_HANDLER(video,      "x-pn-realvideo",                AVMEDIA_TYPE_VIDEO);

RDT_HANDLER(audio,      "x-pn-realaudio",                AVMEDIA_TYPE_AUDIO);

void av_register_rdt_dynamic_payload_handlers(void)

{

    ff_register_dynamic_payload_handler(&ff_rdt_video_handler);

    ff_register_dynamic_payload_handler(&ff_rdt_audio_handler);

    ff_register_dynamic_payload_handler(&ff_rdt_live_video_handler);

    ff_register_dynamic_payload_handler(&ff_rdt_live_audio_handler);

}