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# -*- test-case-name: twisted.pair.test.test_ethernet -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
#
"""Support for working directly with ethernet frames"""
import struct
from zope.interface import Interface, implementer
from twisted.internet import protocol
from twisted.pair import raw
class IEthernetProtocol(Interface):
"""An interface for protocols that handle Ethernet frames"""
def addProto(num, proto):
"""Add an IRawPacketProtocol protocol"""
def datagramReceived(data, partial):
"""An Ethernet frame has been received"""
class EthernetHeader:
def __init__(self, data):
(self.dest, self.source, self.proto) = struct.unpack(
"!6s6sH", data[: 6 + 6 + 2]
)
@implementer(IEthernetProtocol)
class EthernetProtocol(protocol.AbstractDatagramProtocol):
def __init__(self):
self.etherProtos = {}
def addProto(self, num, proto):
proto = raw.IRawPacketProtocol(proto)
if num < 0:
raise TypeError("Added protocol must be positive or zero")
if num >= 2 ** 16:
raise TypeError("Added protocol must fit in 16 bits")
if num not in self.etherProtos:
self.etherProtos[num] = []
self.etherProtos[num].append(proto)
def datagramReceived(self, data, partial=0):
header = EthernetHeader(data[:14])
for proto in self.etherProtos.get(header.proto, ()):
proto.datagramReceived(
data=data[14:],
partial=partial,
dest=header.dest,
source=header.source,
protocol=header.proto,
)
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