#!/usr/bin/env python

import argparse
import sys
import socket
import random
import struct

from scapy.all import sendp, send, hexdump, get_if_list, get_if_hwaddr
from scapy.all import Packet, IPOption
from scapy.all import Ether, IP, UDP
from scapy.all import IntField, FieldListField, FieldLenField, ShortField
from scapy.layers.inet import _IPOption_HDR

def get_if():
    ifs=get_if_list()
    iface=None # "h1-eth0"
    for i in get_if_list():
        if "eth0" in i:
            iface=i
            break;
    if not iface:
        print "Cannot find eth0 interface"
        exit(1)
    return iface

class IPOption_MRI(IPOption):
    name = "MRI"
    option = 31
    fields_desc = [ _IPOption_HDR,
                    FieldLenField("length", None, fmt="B",
                                  length_of="swids",
                                  adjust=lambda pkt,l:l+4),
                    ShortField("count", 0),
                    FieldListField("swids",
                                   [],
                                   IntField("", 0),
                                   length_from=lambda pkt:pkt.count*4) ]


def main():

    if len(sys.argv)<3:
        print 'pass 2 arguments: <destination> "<message>"'
        exit(1)

    addr = socket.gethostbyname(sys.argv[1])
    iface = get_if()

    pkt = Ether(src=get_if_hwaddr(iface), dst="ff:ff:ff:ff:ff:ff") / IP(dst=addr) / UDP(dport=4321, sport=1234) / sys.argv[2]
    #pkt = Ether(src=get_if_hwaddr(iface), dst="ff:ff:ff:ff:ff:ff") / IP(dst=addr, options = IPOption_MRI(count=2, swids=[3,4])) / UDP(dport=4321, sport=1234) / sys.argv[2]
    pkt.show2()
    #hexdump(pkt)
    sendp(pkt, iface=iface)


if __name__ == '__main__':
    main()