text: /*
   * Microsoft RTP/ASF support.
   * Copyright (c) 2008 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 Microsoft RTP/ASF support
   * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
   */
  
  #include "libavutil/avassert.h"
  #include "libavutil/base64.h"
  #include "libavutil/avstring.h"
  #include "libavutil/intreadwrite.h"
  #include "rtp.h"
  #include "rtpdec_formats.h"
  #include "rtsp.h"
  #include "asf.h"
  #include "avio_internal.h"
  #include "internal.h"
  
  /**
   * From MSDN 2.2.1.4, we learn that ASF data packets over RTP should not
   * contain any padding. Unfortunately, the header min/max_pktsize are not
   * updated (thus making min_pktsize invalid). Here, we "fix" these faulty
   * min_pktsize values in the ASF file header.
   * @return 0 on success, <0 on failure (currently -1).
   */
  static int rtp_asf_fix_header(uint8_t *buf, int len)
  {
      uint8_t *p = buf, *end = buf + len;
  
      if (len < sizeof(ff_asf_guid) * 2 + 22 ||
          memcmp(p, ff_asf_header, sizeof(ff_asf_guid))) {
          return -1;
      }
      p += sizeof(ff_asf_guid) + 14;
      do {
          uint64_t chunksize = AV_RL64(p + sizeof(ff_asf_guid));
          if (memcmp(p, ff_asf_file_header, sizeof(ff_asf_guid))) {
              if (chunksize > end - p)
                  return -1;
              p += chunksize;
              continue;
          }
  
          /* skip most of the file header, to min_pktsize */
          p += 6 * 8 + 3 * 4 + sizeof(ff_asf_guid) * 2;
          if (p + 8 <= end && AV_RL32(p) == AV_RL32(p + 4)) {
              /* and set that to zero */
              AV_WL32(p, 0);
              return 0;
          }
          break;
      } while (end - p >= sizeof(ff_asf_guid) + 8);
  
      return -1;
  }
  
  /**
   * The following code is basically a buffered AVIOContext,
   * with the added benefit of returning -EAGAIN (instead of 0)
   * on packet boundaries, such that the ASF demuxer can return
   * safely and resume business at the next packet.
   */
  static int packetizer_read(void *opaque, uint8_t *buf, int buf_size)
  {
      return AVERROR(EAGAIN);
  }
  
  static void init_packetizer(AVIOContext *pb, uint8_t *buf, int len)
  {
      ffio_init_context(pb, buf, len, 0, NULL, packetizer_read, NULL, NULL);
  
      /* this "fills" the buffer with its current content */
      pb->pos     = len;
      pb->buf_end = buf + len;
  }
  
  int ff_wms_parse_sdp_a_line(AVFormatContext *s, const char *p)
  {
      int ret = 0;
      if (av_strstart(p, "pgmpu:data:application/vnd.ms.wms-hdr.asfv1;base64,", &p)) {
          AVIOContext pb;
          RTSPState *rt = s->priv_data;
          AVDictionary *opts = NULL;
          int len = strlen(p) * 6 / 8;
          char *buf = av_mallocz(len);
          AVInputFormat *iformat;
  
          av_base64_decode(buf, p, len);
  
          if (rtp_asf_fix_header(buf, len) < 0)
              av_log(s, AV_LOG_ERROR,
                     "Failed to fix invalid RTSP-MS/ASF min_pktsize\n");
          init_packetizer(&pb, buf, len);
          if (rt->asf_ctx) {
              avformat_close_input(&rt->asf_ctx);
          }
          if (!(iformat = av_find_input_format("asf")))
              return AVERROR_DEMUXER_NOT_FOUND;
          if (!(rt->asf_ctx = avformat_alloc_context()))
              return AVERROR(ENOMEM);
          rt->asf_ctx->pb      = &pb;
          av_dict_set(&opts, "no_resync_search", "1", 0);
  
          if ((ret = ff_copy_whitelists(rt->asf_ctx, s)) < 0) {
              av_dict_free(&opts);
              return ret;
          }
  
          ret = avformat_open_input(&rt->asf_ctx, "", iformat, &opts);
          av_dict_free(&opts);
          if (ret < 0)
              return ret;
          av_dict_copy(&s->metadata, rt->asf_ctx->metadata, 0);
          rt->asf_pb_pos = avio_tell(&pb);
          av_free(buf);
          rt->asf_ctx->pb = NULL;
      }
      return ret;
  }
  
  static int asfrtp_parse_sdp_line(AVFormatContext *s, int stream_index,
                                   PayloadContext *asf, const char *line)
  {
      if (stream_index < 0)
          return 0;
      if (av_strstart(line, "stream:", &line)) {
          RTSPState *rt = s->priv_data;
  
          s->streams[stream_index]->id = strtol(line, NULL, 10);
  
          if (rt->asf_ctx) {
              int i;
  
              for (i = 0; i < rt->asf_ctx->nb_streams; i++) {
                  if (s->streams[stream_index]->id == rt->asf_ctx->streams[i]->id) {
                      *s->streams[stream_index]->codec =
                          *rt->asf_ctx->streams[i]->codec;
                      s->streams[stream_index]->need_parsing =
                          rt->asf_ctx->streams[i]->need_parsing;
                      rt->asf_ctx->streams[i]->codec->extradata_size = 0;
                      rt->asf_ctx->streams[i]->codec->extradata = NULL;
                      avpriv_set_pts_info(s->streams[stream_index], 32, 1, 1000);
                  }
             }
          }
      }
  
      return 0;
  }
  
  struct PayloadContext {
      AVIOContext *pktbuf, pb;
      uint8_t *buf;
  };
  
  /**
   * @return 0 when a packet was written into /p pkt, and no more data is left;
   *         1 when a packet was written into /p pkt, and more packets might be left;
   *        <0 when not enough data was provided to return a full packet, or on error.
   */
  static int asfrtp_parse_packet(AVFormatContext *s, PayloadContext *asf,
                                 AVStream *st, AVPacket *pkt,
                                 uint32_t *timestamp,
                                 const uint8_t *buf, int len, uint16_t seq,
                                 int flags)
  {
      AVIOContext *pb = &asf->pb;
      int res, mflags, len_off;
      RTSPState *rt = s->priv_data;
  
      if (!rt->asf_ctx)
          return -1;
  
      if (len > 0) {
          int off, out_len = 0;
  
          if (len < 4)
              return -1;
  
          av_freep(&asf->buf);
  
          ffio_init_context(pb, (uint8_t *)buf, len, 0, NULL, NULL, NULL, NULL);
  
          while (avio_tell(pb) + 4 < len) {
              int start_off = avio_tell(pb);
  
              mflags = avio_r8(pb);
              if (mflags & 0x80)
                  flags |= RTP_FLAG_KEY;
              len_off = avio_rb24(pb);
              if (mflags & 0x20)   /**< relative timestamp */
                  avio_skip(pb, 4);
              if (mflags & 0x10)   /**< has duration */
                  avio_skip(pb, 4);
              if (mflags & 0x8)    /**< has location ID */
                  avio_skip(pb, 4);
              off = avio_tell(pb);
  
              if (!(mflags & 0x40)) {
                  /**
                   * If 0x40 is not set, the len_off field specifies an offset
                   * of this packet's payload data in the complete (reassembled)
                   * ASF packet. This is used to spread one ASF packet over
                   * multiple RTP packets.
                   */
                  if (asf->pktbuf && len_off != avio_tell(asf->pktbuf)) {
                      uint8_t *p;
                      avio_close_dyn_buf(asf->pktbuf, &p);
                      asf->pktbuf = NULL;
                      av_free(p);
                  }
                  if (!len_off && !asf->pktbuf &&
                      (res = avio_open_dyn_buf(&asf->pktbuf)) < 0)
                      return res;
                  if (!asf->pktbuf)
                      return AVERROR(EIO);
  
                  avio_write(asf->pktbuf, buf + off, len - off);
                  avio_skip(pb, len - off);
                  if (!(flags & RTP_FLAG_MARKER))
                      return -1;
                  out_len     = avio_close_dyn_buf(asf->pktbuf, &asf->buf);
                  asf->pktbuf = NULL;
              } else {
                  /**
                   * If 0x40 is set, the len_off field specifies the length of
                   * the next ASF packet that can be read from this payload
                   * data alone. This is commonly the same as the payload size,
                   * but could be less in case of packet splitting (i.e.
                   * multiple ASF packets in one RTP packet).
                   */
  
                  int cur_len = start_off + len_off - off;
                  int prev_len = out_len;
                  out_len += cur_len;
                  if (FFMIN(cur_len, len - off) < 0)
                      return -1;
                  if ((res = av_reallocp(&asf->buf, out_len)) < 0)
                      return res;
                  memcpy(asf->buf + prev_len, buf + off,
                         FFMIN(cur_len, len - off));
                  avio_skip(pb, cur_len);
              }
          }
  
          init_packetizer(pb, asf->buf, out_len);
          pb->pos += rt->asf_pb_pos;
          pb->eof_reached = 0;
          rt->asf_ctx->pb = pb;
      }
  
      for (;;) {
          int i;
  
          res = ff_read_packet(rt->asf_ctx, pkt);
          rt->asf_pb_pos = avio_tell(pb);
          if (res != 0)
              break;
          for (i = 0; i < s->nb_streams; i++) {
              if (s->streams[i]->id == rt->asf_ctx->streams[pkt->stream_index]->id) {
                  pkt->stream_index = i;
                  return 1; // FIXME: return 0 if last packet
              }
          }
          av_free_packet(pkt);
      }
  
      return res == 1 ? -1 : res;
  }
  
  static PayloadContext *asfrtp_new_context(void)
  {
      return av_mallocz(sizeof(PayloadContext));
  }
  
  static void asfrtp_free_context(PayloadContext *asf)
  {
      if (asf->pktbuf) {
          uint8_t *p = NULL;
          avio_close_dyn_buf(asf->pktbuf, &p);
          asf->pktbuf = NULL;
          av_free(p);
      }
      av_freep(&asf->buf);
      av_free(asf);
  }
  
  #define RTP_ASF_HANDLER(n, s, t) \
  RTPDynamicProtocolHandler ff_ms_rtp_ ## n ## _handler = { \
      .enc_name         = s, \
      .codec_type       = t, \
      .codec_id         = AV_CODEC_ID_NONE, \
      .parse_sdp_a_line = asfrtp_parse_sdp_line, \
      .alloc            = asfrtp_new_context, \
      .free             = asfrtp_free_context, \
      .parse_packet     = asfrtp_parse_packet,   \
  }
  
  RTP_ASF_HANDLER(asf_pfv, "x-asf-pf",  AVMEDIA_TYPE_VIDEO);
  RTP_ASF_HANDLER(asf_pfa, "x-asf-pf",  AVMEDIA_TYPE_AUDIO);
  