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/*
File: file_evt.c
Copyright (C) 2007-2008 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_evt)
#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"
/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_evt(file_stat_t *file_stat);
const file_hint_t file_hint_evt= {
.extension="evt",
.description="Windows Event Log",
.max_filesize=PHOTOREC_MAX_FILE_SIZE,
.recover=1,
.enable_by_default=1,
.register_header_check=®ister_header_check_evt
};
struct evt_chunk {
uint32_t size;
uint32_t id;
} __attribute__ ((gcc_struct, __packed__));
/*@
@ requires file_recovery->data_check==&data_check_evt;
@ requires valid_data_check_param(buffer, buffer_size, file_recovery);
@ terminates \true;
@ ensures valid_data_check_result(\result, file_recovery);
@ assigns file_recovery->calculated_file_size;
@*/
static data_check_t data_check_evt(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
{
/*@ assert file_recovery->calculated_file_size <= PHOTOREC_MAX_FILE_SIZE; */
/*@ assert file_recovery->file_size <= PHOTOREC_MAX_FILE_SIZE; */
/*@
@ loop assigns file_recovery->calculated_file_size;
@ loop variant file_recovery->file_size + buffer_size/2 - (file_recovery->calculated_file_size + 8);
@*/
while(file_recovery->calculated_file_size + buffer_size/2 >= file_recovery->file_size &&
file_recovery->calculated_file_size + 8 < 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 - 8; */
const struct evt_chunk *chunk=(const struct evt_chunk *)&buffer[i];
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))
{
const unsigned int length=le32(chunk->size);
if(length<8)
{
return DC_STOP;
}
file_recovery->calculated_file_size+=length;
}
else
{
return DC_STOP;
}
}
/*
log_trace("data_check_evt record_offset=0x%x\n\n",record_offset);
*/
return DC_CONTINUE;
}
/*@
@ requires buffer_size >= 8;
@ requires separation: \separated(&file_hint_evt, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ terminates \true;
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
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)
{
const struct evt_chunk *chunk=(const struct evt_chunk *)buffer;
const struct evt_chunk *chunk2;
if(le32(chunk->size) != 0x30)
return 0;
chunk2=(const struct evt_chunk *)&buffer[le32(chunk->size)];
if(le32(chunk2->size) < 8)
return 0;
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_evt.extension;
if(file_recovery_new->blocksize >= 8)
{
file_recovery_new->calculated_file_size=le32(chunk->size);
file_recovery_new->data_check=&data_check_evt;
file_recovery_new->file_check=&file_check_size;
}
return 1;
}
static void register_header_check_evt(file_stat_t *file_stat)
{
static const unsigned char evt_header[8]= {0x30, 0x00, 0x00, 0x00, 'L', 'f', 'L', 'e'};
register_header_check(0, evt_header,sizeof(evt_header), &header_check_evt, file_stat);
}
#endif
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