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