#include <libnet.h>
#include <stdio.h>
#include <unistd.h>

void help ();
int
main (int argc, char **argv)
{
  u_long src_ip, dst_ip;
  u_char *packet;
  int socket, pktsize, confirm;
  char err_buff[LIBNET_ERRBUF_SIZE], c;

  if (argc == 1)
    {
      help ();
      exit (-1);
    }

  while ((c = getopt (argc, argv, "d:s:")) != EOF)
    {
      switch (c)
	{
	case 'd':
	  if (!(dst_ip = libnet_name_resolve (optarg, LIBNET_RESOLVE)))
	    {
	      libnet_error (LIBNET_ERR_FATAL,
			    "Bad destination IP Address: %s\n", optarg);
	    }
	  break;
	case 's':
	  if (!(src_ip = libnet_name_resolve (optarg, LIBNET_RESOLVE)))
	    {
	      ibnet_error (LIBNET_ERR_FATAL, "Bad source IP Address: %s\n",optarg);
	    }
	  break;
	}
    }

  if (!src_ip || !dst_ip)
    {
      help ();
      exit (-1);
    }

  pktsize = LIBNET_IP_H + LIBNET_ICMP_ECHO_H;

  libnet_init_packet (pktsize, &packet);

  if (packet == NULL)
    {
      libnet_error (LIBNET_ERR_FATAL, "Cannot allocate memory for packet.\n");
      exit (-1);
    }

  socket = libnet_open_raw_sock (IPPROTO_RAW);
  if (socket == -1)
    {
      libnet_error (LIBNET_ERR_FATAL, "Cannot open network.\n");
      exit (-1);
    }

  libnet_build_ip (ICMP_ECHO_H, IPTOS_LOWDELAY | IPTOS_THROUGHPUT, 242, 0, 48, IPPROTO_ICMP, src_ip, dst_ip, NULL, 0, packet);
  libnet_build_icmp_echo (ICMP_ECHO, 0, 242, 5, NULL, 0, packet + LIBNET_IP_H);

  if (libnet_do_checksum (packet, IPPROTO_ICMP, LIBNET_ICMP_ECHO_H) == -1)
    {
      libnet_error (LIBNET_ERR_FATAL, "Cannot compute checksum.\n");
      exit (-1);
    }

  confirm = libnet_write_ip (socket, packet, pktsize);

  if (confirm < pktsize)
    {
      libnet_error (LIBNET_ERR_FATAL,
		    "libnet_write_ip wrote 0x%x bytes out of 0x%x expected.\n", confirm, pktsize);
    }
  else
    {
      printf ("Sent ICMP_ECHO, wrote 0x%x bytes.\n", pktsize);
    }

  libnet_destroy_packet (&packet);
  return 0;
}

void
help (void)
{
  printf ("ICMP_ECHO Spoofer, written by Javaman.\n");
  printf ("Requires libnet.\n");
  printf ("Options:\n");
  printf ("\t-d\tDestination IP\n");
  printf ("\t-s\tSource IP\n");
}