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| 8 | """Support for working directly with ethernet frames""" |
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| 9 | |
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| 10 | import struct |
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| 11 | |
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| 12 | |
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| 13 | from twisted.internet import protocol |
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| 14 | from twisted.pair import raw |
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| 15 | from zope.interface import implements, Interface |
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| 16 | |
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| 17 | |
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| 18 | class IEthernetProtocol(Interface): |
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| 19 | """An interface for protocols that handle Ethernet frames""" |
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| 20 | def addProto(): |
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| 21 | """Add an IRawPacketProtocol protocol""" |
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| 22 | |
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| 23 | def datagramReceived(): |
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| 24 | """An Ethernet frame has been received""" |
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| 25 | |
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| 26 | class EthernetHeader: |
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| 27 | def __init__(self, data): |
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| 28 | |
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| 29 | (self.dest, self.source, self.proto) \ |
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| 30 | = struct.unpack("!6s6sH", data[:6+6+2]) |
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| 31 | |
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| 32 | class EthernetProtocol(protocol.AbstractDatagramProtocol): |
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| 33 | |
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| 34 | implements(IEthernetProtocol) |
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| 35 | |
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| 36 | def __init__(self): |
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| 37 | self.etherProtos = {} |
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| 38 | |
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| 39 | def addProto(self, num, proto): |
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| 40 | proto = raw.IRawPacketProtocol(proto) |
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| 41 | if num < 0: |
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| 42 | raise TypeError, 'Added protocol must be positive or zero' |
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| 43 | if num >= 2**16: |
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| 44 | raise TypeError, 'Added protocol must fit in 16 bits' |
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| 45 | if num not in self.etherProtos: |
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| 46 | self.etherProtos[num] = [] |
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| 47 | self.etherProtos[num].append(proto) |
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| 48 | |
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| 49 | def datagramReceived(self, data, partial=0): |
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| 50 | header = EthernetHeader(data[:14]) |
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| 51 | for proto in self.etherProtos.get(header.proto, ()): |
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| 52 | proto.datagramReceived(data=data[14:], |
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| 53 | partial=partial, |
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| 54 | dest=header.dest, |
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| 55 | source=header.source, |
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| 56 | protocol=header.proto) |
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