/*

    File: file_evt.c

    Copyright (C) 2007 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.

 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <stdio.h>
#include "types.h"
#include "common.h"
#include "filegen.h"
#include "log.h"

static void register_header_check_evt(file_stat_t *file_stat);
static int header_check_evt(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);
static int data_check_evt(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery);

const file_hint_t file_hint_evt= {
  .extension="evt",
  .description="Windows Event Log",
  .min_header_distance=0,
  .max_filesize=PHOTOREC_MAX_FILE_SIZE,
  .recover=1,
  .header_check=&header_check_evt,
  .register_header_check=&register_header_check_evt
};

static const unsigned char evt_header[8]= {0x30, 0x00, 0x00, 0x00, 'L', 'f', 'L', 'e'};

static void register_header_check_evt(file_stat_t *file_stat)
{
  register_header_check(0, evt_header,sizeof(evt_header), &header_check_evt, file_stat);
}

static int header_check_evt(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)
{
  if(memcmp(buffer,evt_header,sizeof(evt_header))==0)
  {
    reset_file_recovery(file_recovery_new);
    file_recovery_new->calculated_file_size=buffer[0] + (buffer[1]<<8) + (buffer[2]<<16) + (buffer[3]<<24);
    file_recovery_new->data_check=&data_check_evt;
    file_recovery_new->file_check=&file_check_size;
    file_recovery_new->extension=file_hint_evt.extension;
    return 1;
  }
  return 0;
}

static int data_check_evt(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
{
  while(file_recovery->calculated_file_size + 8 < file_recovery->file_size + buffer_size/2)
  {
    unsigned int i=file_recovery->calculated_file_size - file_recovery->file_size + buffer_size/2;
    if((buffer[i+4]=='L' && buffer[i+5]=='f' && buffer[i+6]=='L' && buffer[i+7]=='e') ||
	(buffer[i+4]==0x11 && buffer[i+5]==0x11 && buffer[i+6]==0x11 && buffer[i+7]==0x11) ||
	(buffer[i+4]==0x22 && buffer[i+5]==0x22 && buffer[i+6]==0x22 && buffer[i+7]==0x22) ||
	(buffer[i+4]==0x33 && buffer[i+5]==0x33 && buffer[i+6]==0x33 && buffer[i+7]==0x33) ||
	(buffer[i+4]==0x44 && buffer[i+5]==0x44 && buffer[i+6]==0x44 && buffer[i+7]==0x44))
    {
      unsigned int length=(buffer[i+0] + (buffer[i+1]<<8) + (buffer[i+2]<<16) + (buffer[i+3]<<24));
      if(length<8)
      {
	return 2;
      }
      file_recovery->calculated_file_size+=length;
    }
    else
    {
      return 2;
    }
  }
  /*
  log_trace("data_check_evt record_offset=0x%x\n\n",record_offset);
  */
  return 1;
}