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# -*- test-case-name: twisted.pair.test.test_ip -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
#
"""Support for working directly with IP packets"""
import struct
import socket
from twisted.internet import protocol
from twisted.pair import raw
from zope.interface import implementer
class IPHeader:
def __init__(self, data):
(ihlversion, self.tos, self.tot_len, self.fragment_id, frag_off,
self.ttl, self.protocol, self.check, saddr, daddr) \
= struct.unpack("!BBHHHBBH4s4s", data[:20])
self.saddr = socket.inet_ntoa(saddr)
self.daddr = socket.inet_ntoa(daddr)
self.version = ihlversion & 0x0F
self.ihl = ((ihlversion & 0xF0) >> 4) << 2
self.fragment_offset = frag_off & 0x1FFF
self.dont_fragment = (frag_off & 0x4000 != 0)
self.more_fragments = (frag_off & 0x2000 != 0)
MAX_SIZE = 2**32
@implementer(raw.IRawPacketProtocol)
class IPProtocol(protocol.AbstractDatagramProtocol):
def __init__(self):
self.ipProtos = {}
def addProto(self, num, proto):
proto = raw.IRawDatagramProtocol(proto)
if num < 0:
raise TypeError('Added protocol must be positive or zero')
if num >= MAX_SIZE:
raise TypeError('Added protocol must fit in 32 bits')
if num not in self.ipProtos:
self.ipProtos[num] = []
self.ipProtos[num].append(proto)
def datagramReceived(self,
data,
partial,
dest,
source,
protocol):
header = IPHeader(data)
for proto in self.ipProtos.get(header.protocol, ()):
proto.datagramReceived(data=data[20:],
partial=partial,
source=header.saddr,
dest=header.daddr,
protocol=header.protocol,
version=header.version,
ihl=header.ihl,
tos=header.tos,
tot_len=header.tot_len,
fragment_id=header.fragment_id,
fragment_offset=header.fragment_offset,
dont_fragment=header.dont_fragment,
more_fragments=header.more_fragments,
ttl=header.ttl,
)
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