python socket 解码IP层

import socket
import os
import struct
from ctypes import  *

host="10.10.10.128"

class IP(Structure):
    _fields_=[
    ("ihl",c_ubyte,4),
    ("version",c_ubyte,4),
    ("tos",c_ubyte),
    ("len",c_ushort),
    ("id",c_ushort),
    ("offset",c_ushort),
    ("ttl",c_ubyte),
    ("protocol_num",c_ubyte),
    ("sum",c_ushort),
    ("src",c_ulong),
    ("dst",c_ulong)
    ]

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

    def __init__(self,socket_buffer=None):
        self.protocol_map={1:"ICMP",6:"TCP",17:"UDP"}
        self.src_address=socket.inet_ntoa(struct.pack("         self.dst_address=socket.inet_ntoa(struct.pack("     
        try:
            self.protocol=self.protocol_map[self.protocol_num]
        except:
            self.protocol=str(self.protocol_num)

if os.name=="nt":
    socket_protocol=socket.IPPROTO_IP
else:
    socket_protocol=socket.IPPROTO_ICMP

sniffer=socket.socket(socket.AF_INET,socket.SOCK_RAW,socket_protocol)
sniffer.bind((host,0))
sniffer.setsockopt(socket.IPPROTO_IP,socket.IP_HDRINCL,1)

if os.name=="nt":
    sniffer.ioctl(socket.SIO_RCVALL,socket.RCVALL_ON)
    
try:
    while True:
        raw_buffer=sniffer.recvfrom(65565)[0]
        ip_header=IP(raw_buffer[0:20])
        print  "Protocol:%s %s -> %s" %(ip_header.protocol,ip_header.src_address,ip_header.dst_address)
except KeyboardInterrupt:
    if os.name=="nt":
        sniffer.ioctl(socket.SIO_RCVALL,socket.RCVALL_OFF)