one-file-projects/dhcptest.py

#!/usr/bin/env python

import struct
import socket

class DHCPPack:
    fmt = "BBBBIHH4B4B4B4B8H64s128s"
    def __init__(self,data=None):
        if data is not None:
            info = struct.unpack(DHCPPack.fmt, data)
            self.op = info[0]
            self.htype = info[1]
            self.hlen = info[2]
            self.hops = info[3]
            self.xid = info[4]
            self.secs = info[5]
            self.flags = info[6]
            self.ciaddr = tuple(info[7:10])
            self.yiaddr = tuple(info[11:14])
            self.siaddr = tuple(info[15:18])
            self.giaddr = tuple(info[19:22])
            self.chaddr = tuple(info[23:30])
            self.sname = info[31]
            self.file = info[32]
        else:
            self.op = 1
            self.htype = 1
            self.hlen = 6
            self.hops = 0
            self.xid = 0
            self.secs = 0
            self.flags = 0
            self.ciaddr = (0,0,0,0)
            self.yiaddr = (0,0,0,0)
            self.siaddr = (0,0,0,0)
            self.giaddr = (0,0,0,0)
            self.chaddr = (0xDE,0xAD,0xBE,0xEF,0x13,0x37,0x13,0x37)
            self.sname = ""
            self.file = ""

    def pack(self):
        return struct.pack(DHCPPack.fmt,
                self.op,
                self.htype,
                self.hlen,
                self.hops,
                self.xid,
                self.secs,
                self.flags,
                self.ciaddr[0],
                self.ciaddr[1],
                self.ciaddr[2],
                self.ciaddr[3],
                self.yiaddr[0],
                self.yiaddr[1],
                self.yiaddr[2],
                self.yiaddr[3],
                self.siaddr[0],
                self.siaddr[1],
                self.siaddr[2],
                self.siaddr[3],
                self.giaddr[0],
                self.giaddr[1],
                self.giaddr[2],
                self.giaddr[3],
                self.chaddr[0],
                self.chaddr[1],
                self.chaddr[2],
                self.chaddr[3],
                self.chaddr[4],
                self.chaddr[5],
                self.chaddr[6],
                self.chaddr[7],
                str.encode(self.sname),
                str.encode(self.file))


def main():
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    s.bind(('',67))
    #s.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)

    #packet = DHCPPack();
    #s.sendto(packet.pack(), ('<broadcast>',67))

    data, addr = s.recvfrom(1024)

    packet2 = DHCPPack(data)
    if packet2.op == 2:
        print("Got answer")
    else:
        print("WTF")

main()