/* Find a file in the FW dumps
**
** -- subdub
*/

#include <sys/mman.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>

#define SEARCH_SIZE (32)

unsigned char *mapfile(const char *path, unsigned long *size)
{
  int fd;
  struct stat s;
  unsigned char *ret;

  if ((fd = open(path, O_RDONLY, 0400)) < 0)
    {
      fprintf(stderr, "[X] %s : %s\n", path, strerror(errno));
      return NULL;
    }

  if (fstat(fd, &s) < 0)
    {
      perror("[X] fstat");
      return NULL;
    }
  *size = (unsigned long) s.st_size;
  if ((ret = (unsigned char *) mmap(0, s.st_size, PROT_READ, MAP_SHARED, fd, 0)) == NULL)
    {
      perror("[X] mmap");
      return NULL;
    }
  printf("[*] File %s mapped at %p, %ld bytes\n", path, ret, *size);
  return ret;
}

int findfile(unsigned char *map_fwA, unsigned long size_fwA,
	     unsigned char *map_fwB, unsigned long size_fwB,
	     unsigned char *map_file, unsigned long size_file)
{
  unsigned char *cur_fwA, *cur_fwB, *cur_file;
  unsigned char *begin, *end, *begin_tmp;
  unsigned long count, total;
  int isA;

  cur_fwA = map_fwA;
  cur_fwB = map_fwB;
  cur_file = map_file;

  total = 0;
  while ((size_fwA > 0 || size_fwB >0) || size_file > 0)
    {
      /* First we try to find SEARCH_SIZE bytes of our file into the fw dumps */
      if ((begin = begin_tmp = memmem(cur_fwA, size_fwA, cur_file, SEARCH_SIZE)) == NULL)
	{
	  if ((begin = begin_tmp = memmem(cur_fwB, size_fwB, cur_file, SEARCH_SIZE)) == NULL)
	    break;
	  else
	    {
	      size_fwB -= ((long) begin - (long) map_fwB);
	      isA = 0;
	    }
	}
      else
	{
	  size_fwA -= ((long) begin - (long) map_fwA);
	  isA = 1;
	}

      size_file -= SEARCH_SIZE;

      if (isA)
	{
	  for (count = SEARCH_SIZE; *begin_tmp++ == *cur_file++; count++, size_fwA--, size_file--);
	  printf("\t-> Found %u bytes @ %#.016lx, in dump A\n", count, (long) begin - (long) cur_fwA);
	}
      else
	{
	  for (count = SEARCH_SIZE; *begin_tmp++ == *cur_file++; count++, size_fwB--, size_file--);
	  printf("\t-> Found %u bytes @ %#.016lx, in dump B\n", count, (long) begin - (long) cur_fwB);
	}
      total += count;
    }
  printf("[*] Matched %u bytes in total\n", total);
  return 0;
}

int main(int argc, const char **argv)
{
  unsigned char *mapped_fwA, *mapped_fwB,  *mapped_file;
  unsigned long size_fwA, size_fwB, size_file;

  if (argc < 4)
    {
      fprintf(stderr, "Usage: %s <FW file A> <FW file B> <file to search>\n", argv[0]);
      return 1;
    }
  if ((mapped_fwA = mapfile(argv[1], &size_fwA)) == NULL)
    return 1;
  if ((mapped_fwB = mapfile(argv[2], &size_fwB)) == NULL)
    return 1;
  if ((mapped_file = mapfile(argv[3], &size_file)) == NULL)
    return 1;
  printf("--------------- STARTING ---------------\n");
  return findfile(mapped_fwA, size_fwA, mapped_fwB, size_fwB, mapped_file, size_file);
}