#!/usr/bin/env python3

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, PacketListField, BitField
from scapy.layers.inet import _IPOption_HDR

from time import sleep


def get_if():
    ifs=get_if_list()
    iface=None
    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 SwitchTrace(Packet):
    fields_desc = [ BitField("swid", 0, 13),
                    BitField("qdepth", 0,13),
                    BitField("portid",0,6)]
    def extract_padding(self, p):
                return "", p

class IPOption_INT(IPOption):
    name = "INT"
    option = 31
    fields_desc = [ _IPOption_HDR,
                    FieldLenField("length", None, fmt="B",
                                  length_of="int_headers",
                                  adjust=lambda pkt,l:l*2+4),
                    ShortField("count", 0),
                    PacketListField("int_headers",
                                   [],
                                   SwitchTrace,
                                   count_from=lambda pkt:(pkt.count*1)) ]


def main():

    if len(sys.argv)<4:
        print('pass 3 arguments: <destination> "<message>" <number of packets>')
        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, options = IPOption_INT(count=0,
            int_headers=[])) / UDP(
            dport=1234, sport=4321) / sys.argv[2]

    pkt.show2()

    try:
      for i in range(int(sys.argv[3])):
        sendp(pkt, iface=iface)
        sleep(1)
    except KeyboardInterrupt:
        raise


if __name__ == '__main__':
    main()