/*
  * 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 + AV_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

     static 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;

     unsigned 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, NULL) < 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, uint16_t rtp_seq, int flags)

 {
     int seq = 1, res;

     AVIOContext pb;

     if (rdt->audio_pkt_cnt == 0) {

         int pos, rmflags;

         ffio_init_context(&pb, (uint8_t *)buf, len, 0, NULL, NULL, NULL, NULL);

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

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

                                   &seq, rmflags, *timestamp);

         pos = avio_tell(&pb);

         if (res < 0)
             return res;

         if (res > 0) {

             if (st->codec->codec_id == AV_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 == AV_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, 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, 0, 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 + AV_INPUT_BUFFER_PADDING_SIZE);

     if (!target)
         return NULL;

     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, err;

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

                 if (rdt->nb_rmst < count) {

                     if ((err = av_reallocp(&rdt->rmst,

                                            count * sizeof(*rdt->rmst))) < 0) {
                         rdt->nb_rmst = 0;

                         return err;

                     }

                     memset(rdt->rmst + rdt->nb_rmst, 0,
                            (count - rdt->nb_rmst) * sizeof(*rdt->rmst));

                     rdt->nb_rmst = count;
                 }

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

                 if (!rdt->rmst[s->streams[n]->index])
                     return AVERROR(ENOMEM);

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

 
     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 = avformat_new_stream(s, NULL)))

         return NULL;

     st->id = orig_st->id;

     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

      * preceded 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 av_cold int rdt_init(AVFormatContext *s, int st_index, PayloadContext *rdt)

 {
     int ret;
 

     rdt->rmctx = avformat_alloc_context();
     if (!rdt->rmctx)
         return AVERROR(ENOMEM);
 

     if ((ret = ff_copy_whitelists(rdt->rmctx, s)) < 0)
         return ret;
 
     return avformat_open_input(&rdt->rmctx, "", &ff_rdt_demuxer, NULL);
 }
 

 static void

 rdt_close_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)

         avformat_close_input(&rdt->rmctx);

     av_freep(&rdt->mlti_data);

     av_freep(&rdt->rmst);

 }
 
 #define RDT_HANDLER(n, s, t) \

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

     .enc_name         = s, \
     .codec_type       = t, \

     .codec_id         = AV_CODEC_ID_NONE, \

     .priv_data_size   = sizeof(PayloadContext), \
     .init             = rdt_init, \

     .parse_sdp_a_line = rdt_parse_sdp_line, \

     .close            = rdt_close_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 ff_register_rdt_dynamic_payload_handlers(void)

 {

     ff_register_dynamic_payload_handler(&rdt_video_handler);
     ff_register_dynamic_payload_handler(&rdt_audio_handler);
     ff_register_dynamic_payload_handler(&rdt_live_video_handler);
     ff_register_dynamic_payload_handler(&rdt_live_audio_handler);

 }