from ctypes import *
import socket
import struct 
import ipaddress
import os

class IP_ctype(Structure):
    _fields_ = [
        ("version",      c_ubyte,    4),
        ("ihl",          c_ubyte,    4),
        ("tos",          c_ubyte,    8),
        ("len",          c_ushort,  16),
        ("id",           c_ushort,  16),
        ("offset",       c_ushort,  16),
        ("ttl",          c_ubyte,    8),
        ("protocol_num", c_ubyte,    8),
        ("sum",          c_ushort,  16),
        ("src",          c_uint32,  32),
        ("dst",          c_uint32,  32)
    ]

    def __new__(cls, socket_buffer=None):
        return cls.from_buffer_copy(socket_buffer)
    
    def __init__(self, socket_buffer=None):
        self.src_address = socket.inet_ntoa(struct.pack("<L",self.src))
        self.dst_address = socket.inet_ntoa(struct.pack("<L",self.dst))
        self.protocol_map = {1:"ICMP", 2:"IGMP", 6:"TCP", 17: "UDP"}
        try:
            self.protocol = self.protocol_map[self.protocol_num]
        except Exception as e:
            print(f'{e} No known protocol for {self.protocol_num}')




# ICMP response packet
class ICMP_ctype(Structure):
    _fields_ = [
        ("type",    c_ubyte,    8),
        ("code",    c_ubyte,    8),
        ("sum",     c_ushort,  16),
        ("id",      c_ushort,  16),
        ("seq",     c_ushort,  16)
    ]

    def __new__(cls, socket_buffer=None):
        return cls.from_buffer_copy(socket_buffer)