/*
  * MMS protocol common definitions.
  * Copyright (c) 2006,2007 Ryan Martell

  * Copyright (c) 2007 Björn Axelsson

  * Copyright (c) 2010 Zhentan Feng <spyfeng at gmail dot com>
  *
  * 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
  */
 #include "mms.h"
 #include "asf.h"
 #include "libavutil/intreadwrite.h"
 

 #define MMS_MAX_STREAMS 256    /**< arbitrary sanity check value */
 

 int ff_mms_read_header(MMSContext *mms, uint8_t *buf, const int size)
 {
     char *pos;
     int size_to_copy;
     int remaining_size = mms->asf_header_size - mms->asf_header_read_size;
     size_to_copy = FFMIN(size, remaining_size);
     pos = mms->asf_header + mms->asf_header_read_size;
     memcpy(buf, pos, size_to_copy);
     if (mms->asf_header_read_size == mms->asf_header_size) {
         av_freep(&mms->asf_header); // which contains asf header
     }
     mms->asf_header_read_size += size_to_copy;
     return size_to_copy;
 }
 
 int ff_mms_read_data(MMSContext *mms, uint8_t *buf, const int size)
 {
     int read_size;
     read_size = FFMIN(size, mms->remaining_in_len);
     memcpy(buf, mms->read_in_ptr, read_size);
     mms->remaining_in_len -= read_size;
     mms->read_in_ptr      += read_size;
     return read_size;
 }
 
 int ff_mms_asf_header_parser(MMSContext *mms)
 {
     uint8_t *p = mms->asf_header;
     uint8_t *end;
     int flags, stream_id;
     mms->stream_num = 0;
 
     if (mms->asf_header_size < sizeof(ff_asf_guid) * 2 + 22 ||
         memcmp(p, ff_asf_header, sizeof(ff_asf_guid))) {
         av_log(NULL, AV_LOG_ERROR,
                "Corrupt stream (invalid ASF header, size=%d)\n",
                mms->asf_header_size);
         return AVERROR_INVALIDDATA;
     }
 
     end = mms->asf_header + mms->asf_header_size;
 
     p += sizeof(ff_asf_guid) + 14;
     while(end - p >= sizeof(ff_asf_guid) + 8) {

         uint64_t chunksize;
         if (!memcmp(p, ff_asf_data_header, sizeof(ff_asf_guid))) {
             chunksize = 50; // see Reference [2] section 5.1
         } else {
             chunksize = AV_RL64(p + sizeof(ff_asf_guid));
         }

         if (!chunksize || chunksize > end - p) {
             av_log(NULL, AV_LOG_ERROR,
                    "Corrupt stream (header chunksize %"PRId64" is invalid)\n",
                    chunksize);
             return AVERROR_INVALIDDATA;
         }
         if (!memcmp(p, ff_asf_file_header, sizeof(ff_asf_guid))) {
             /* read packet size */
             if (end - p > sizeof(ff_asf_guid) * 2 + 68) {
                 mms->asf_packet_len = AV_RL32(p + sizeof(ff_asf_guid) * 2 + 64);
                 if (mms->asf_packet_len <= 0 || mms->asf_packet_len > sizeof(mms->in_buffer)) {
                     av_log(NULL, AV_LOG_ERROR,
                            "Corrupt stream (too large pkt_len %d)\n",
                            mms->asf_packet_len);
                     return AVERROR_INVALIDDATA;
                 }
             }
         } else if (!memcmp(p, ff_asf_stream_header, sizeof(ff_asf_guid))) {
             flags     = AV_RL16(p + sizeof(ff_asf_guid)*3 + 24);
             stream_id = flags & 0x7F;
             //The second condition is for checking CS_PKT_STREAM_ID_REQUEST packet size,
             //we can calcuate the packet size by stream_num.
             //Please see function send_stream_selection_request().

             if (mms->stream_num < MMS_MAX_STREAMS &&

                     46 + mms->stream_num * 6 < sizeof(mms->out_buffer)) {

                 mms->streams = av_fast_realloc(mms->streams,
                                    &mms->nb_streams_allocated,
                                    (mms->stream_num + 1) * sizeof(MMSStream));

                 mms->streams[mms->stream_num].id = stream_id;
                 mms->stream_num++;
             } else {
                 av_log(NULL, AV_LOG_ERROR,
                        "Corrupt stream (too many A/V streams)\n");
                 return AVERROR_INVALIDDATA;
             }

         } else if (!memcmp(p, ff_asf_ext_stream_header, sizeof(ff_asf_guid))) {
             if (end - p >= 88) {
                 int stream_count = AV_RL16(p + 84), ext_len_count = AV_RL16(p + 86);
                 uint64_t skip_bytes = 88;
                 while (stream_count--) {
                     if (end - p < skip_bytes + 4) {
                         av_log(NULL, AV_LOG_ERROR,
                                "Corrupt stream (next stream name length is not in the buffer)\n");
                         return AVERROR_INVALIDDATA;
                     }
                     skip_bytes += 4 + AV_RL16(p + skip_bytes + 2);
                 }
                 while (ext_len_count--) {
                     if (end - p < skip_bytes + 22) {
                         av_log(NULL, AV_LOG_ERROR,
                                "Corrupt stream (next extension system info length is not in the buffer)\n");
                         return AVERROR_INVALIDDATA;
                     }
                     skip_bytes += 22 + AV_RL32(p + skip_bytes + 18);
                 }
                 if (end - p < skip_bytes) {
                     av_log(NULL, AV_LOG_ERROR,
                            "Corrupt stream (the last extension system info length is invalid)\n");
                     return AVERROR_INVALIDDATA;
                 }
                 if (chunksize - skip_bytes > 24)
                     chunksize = skip_bytes;
             }

         } else if (!memcmp(p, ff_asf_head1_guid, sizeof(ff_asf_guid))) {
             chunksize = 46; // see references [2] section 3.4. This should be set 46.
         }
         p += chunksize;
     }
 
     return 0;
 }