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/*

    File: file_flv.c

    Copyright (C) 2007,2014 Christophe GRENIER <grenier@cgsecurity.org>
  
    This software is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
  
    This program 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 General Public License for more details.
  
    You should have received a copy of the GNU General Public License along
    with this program; if not, write the Free Software Foundation, Inc., 51
    Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 */

#if !defined(SINGLE_FORMAT) || defined(SINGLE_FORMAT_flv)
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <stdio.h>
#include "types.h"
#include "filegen.h"
#include "common.h"
#include "log.h"

/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_flv(file_stat_t *file_stat);

const file_hint_t file_hint_flv= {
  .extension="flv",
  .description="Macromedia",
  .max_filesize=PHOTOREC_MAX_FILE_SIZE,
  .recover=1,
  .enable_by_default=1,
  .register_header_check=&register_header_check_flv
};

struct flv_header
{
  char 		signature[3];
  uint8_t	version;
  uint8_t	type_flags;
  uint32_t	data_offset;
} __attribute__ ((gcc_struct, __packed__));

struct flv_tag
{
  uint32_t	prev_tag_size;
  uint8_t	info;
  uint8_t	data_size[3];
  uint8_t	timestamp[3];
  uint8_t	timestamp_ext;
  uint8_t	streamID[3];
} __attribute__ ((gcc_struct, __packed__));

/*@
  @ requires file_recovery->data_check==&data_check_flv;
  @ requires valid_data_check_param(buffer, buffer_size, file_recovery);
  @ ensures  valid_data_check_result(\result, file_recovery);
  @ assigns file_recovery->calculated_file_size, file_recovery->data_check_tmp;
  @*/
static data_check_t data_check_flv(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
{
  /*@
    @ loop assigns file_recovery->calculated_file_size, file_recovery->data_check_tmp;
    @*/
  while(file_recovery->calculated_file_size + buffer_size/2  >= file_recovery->file_size &&
      file_recovery->calculated_file_size + 15 < file_recovery->file_size + buffer_size/2)
  {
    const unsigned int i=file_recovery->calculated_file_size + buffer_size/2 - file_recovery->file_size;
    /*@ assert 0 <= i < buffer_size - 15; */
    const struct flv_tag *tag=(const struct flv_tag *)&buffer[i];
    /*@ assert \valid_read(tag); */
#ifdef DEBUG_FLV
    log_info("cfs=0x%llx file_recovery->data_check_tmp=%u\n", (long long unsigned)file_recovery->calculated_file_size, file_recovery->data_check_tmp);
#endif
    if((be32(tag->prev_tag_size)==0 && file_recovery->calculated_file_size < buffer_size/2) ||
      be32(tag->prev_tag_size)==11+file_recovery->data_check_tmp)
    {
      file_recovery->data_check_tmp=(tag->data_size[0]<<16) | (tag->data_size[1]<<8) | tag->data_size[2];
      if((tag->info&0xc0)!=0 || file_recovery->data_check_tmp==0
	  || tag->streamID[0]!=0 || tag->streamID[1]!=0 || tag->streamID[2]!=0 )
      {
	file_recovery->calculated_file_size+=4;
	return DC_STOP;
      }
      /* 4+11=15*/
      file_recovery->calculated_file_size+=(uint64_t)15+file_recovery->data_check_tmp;
    }
    else
      return DC_ERROR;
  }
  return DC_CONTINUE;
}

/*@
  @ requires buffer_size >= sizeof(struct flv_header);
  @ requires separation: \separated(&file_hint_flv, buffer+(..), file_recovery, file_recovery_new);
  @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
  @ ensures  valid_header_check_result(\result, file_recovery_new);
  @ assigns  *file_recovery_new;
  @*/
static int header_check_flv(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
{
  const struct flv_header *flv=(const struct flv_header *)buffer;
  const unsigned int data_offset=be32(flv->data_offset);
  if((flv->type_flags & 0xfa)==0 && data_offset>=9)
  {
    reset_file_recovery(file_recovery_new);
    file_recovery_new->extension=file_hint_flv.extension;
    if(file_recovery_new->blocksize < 15)
      return 1;
    file_recovery_new->calculated_file_size=data_offset;
    file_recovery_new->data_check=&data_check_flv;
    file_recovery_new->file_check=&file_check_size;
    return 1;
  }
  return 0;
}

static void register_header_check_flv(file_stat_t *file_stat)
{
  static const unsigned char flv_header[4]= {'F', 'L', 'V', 0x01};
  register_header_check(0, flv_header,sizeof(flv_header), &header_check_flv, file_stat);
}
#endif