62 lines
2.1 KiB
Python
62 lines
2.1 KiB
Python
# Copyright (C) 2013 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 struct
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from os_ken.lib.packet import packet_base
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class itag(packet_base.PacketBase):
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"""I-TAG (IEEE 802.1ah-2008) header encoder/decoder class.
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An instance has the following attributes at least.
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Most of them are same to the on-wire counterparts but in host byte order.
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__init__ takes the corresponding args in this order.
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============== ====================
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Attribute Description
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============== ====================
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pcp Priority Code Point
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dei Drop Eligible Indication
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uca Use Customer Address
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sid Service Instance ID
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============== ====================
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"""
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_PACK_STR = "!I"
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_MIN_LEN = struct.calcsize(_PACK_STR)
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def __init__(self, pcp=0, dei=0, uca=0, sid=0):
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super(itag, self).__init__()
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self.pcp = pcp
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self.dei = dei
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self.uca = uca
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self.sid = sid
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@classmethod
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def parser(cls, buf):
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(data, ) = struct.unpack_from(cls._PACK_STR, buf)
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pcp = data >> 29
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dei = data >> 28 & 1
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uca = data >> 27 & 1
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sid = data & 0x00ffffff
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# circular import: ethernet -> vlan -> pbb
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from os_ken.lib.packet import ethernet
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return (cls(pcp, dei, uca, sid), ethernet.ethernet,
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buf[cls._MIN_LEN:])
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def serialize(self, payload, prev):
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data = self.pcp << 29 | self.dei << 28 | self.uca << 27 | self.sid
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return struct.pack(self._PACK_STR, data)
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