89 lines
2.6 KiB
Python
89 lines
2.6 KiB
Python
# Copyright (C) 2012 Nippon Telegraph and Telephone Corporation.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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# implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import abc
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import six
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from os_ken.lib import stringify
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@six.add_metaclass(abc.ABCMeta)
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class PacketBase(stringify.StringifyMixin):
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"""A base class for a protocol (ethernet, ipv4, ...) header."""
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_TYPES = {}
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@classmethod
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def get_packet_type(cls, type_):
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"""Per-protocol dict-like get method.
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Provided for convenience of protocol implementers.
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Internal use only."""
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return cls._TYPES.get(type_)
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@classmethod
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def register_packet_type(cls, cls_, type_):
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"""Per-protocol dict-like set method.
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Provided for convenience of protocol implementers.
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Internal use only."""
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cls._TYPES[type_] = cls_
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def __init__(self):
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super(PacketBase, self).__init__()
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def __len__(self):
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return self._MIN_LEN
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@property
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def protocol_name(self):
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return self.__class__.__name__
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@classmethod
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@abc.abstractmethod
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def parser(cls, buf):
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"""Decode a protocol header.
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This method is used only when decoding a packet.
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Decode a protocol header at offset 0 in bytearray *buf*.
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Returns the following three objects.
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* An object to describe the decoded header.
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* A packet_base.PacketBase subclass appropriate for the rest of
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the packet. None when the rest of the packet should be considered
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as raw payload.
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* The rest of packet.
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"""
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pass
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def serialize(self, payload, prev):
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"""Encode a protocol header.
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This method is used only when encoding a packet.
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Encode a protocol header.
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Returns a bytearray which contains the header.
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*payload* is the rest of the packet which will immediately follow
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this header.
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*prev* is a packet_base.PacketBase subclass for the outer protocol
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header. *prev* is None if the current header is the outer-most.
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For example, *prev* is ipv4 or ipv6 for tcp.serialize.
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"""
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pass
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