#!/usr/bin/python
### doicmp client
### usage example: python client.py 10.0.0.1 10.0.0.5 "Hi there!"
import time
import sys
from impacket import ImpactPacket
from socket import *
import os

DLEN = 56 # specifies the DATA lenght of every packet.

def send_pkt(x, y, a, seq_id):
    """send_pkt(tot num fragmented packets, last_packet, difference, ID"""
    str_send = '@'+string[DLEN*(i-a): DLEN*i] # Packet fragmentation
    icmp.contains(ImpactPacket.Data(str_send)) # fill DATA field
    ip.contains(icmp) # encapsulate ICMP packet in IP packet							 
    seq_id += 1							 
    icmp.set_icmp_id(seq_id) # set ID field
    icmp.set_icmp_cksum(0)						 
    icmp.auto_checksum = 1						 
    s.sendto(ip.get_packet(), (dst, 0)) # send packet		 
    time.sleep(0.05)
    
# parser
if len(sys.argv) < 3:
    print """"Usage: <source IP> <dest IP> "data" """
    sys.exit(1)
src = sys.argv[1]
dst = sys.argv[2]
string = sys.argv[3]+'\n'

# create RAW socket
s = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)
s.setsockopt(IPPROTO_IP, IP_HDRINCL, 1)

# define IP packet
ip = ImpactPacket.IP()
ip.set_ip_src(src)
ip.set_ip_dst(dst)

# define ICMP packet
icmp = ImpactPacket.ICMP()
icmp.set_icmp_type(icmp.ICMP_ECHOREPLY) # define ICMP packet type

# fragmentation for DATA fields > of 54 bytes
seq_id = 0
x = len(string) / DLEN								 
y = len(string) % DLEN
for i in range(1,x+2):
    send_pkt(x,y,1,seq_id)
while y > DLEN: #difference for packet len != DLEN
    send_pkt(x,y,0,seq_id)