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# Copyright (C) 2013 Nippon Telegraph and Telephone Corporation.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import struct
from os_ken.lib.packet import packet_base
class itag(packet_base.PacketBase):
"""I-TAG (IEEE 802.1ah-2008) header encoder/decoder class.
An instance has the following attributes at least.
Most of them are same to the on-wire counterparts but in host byte order.
__init__ takes the corresponding args in this order.
============== ====================
Attribute Description
============== ====================
pcp Priority Code Point
dei Drop Eligible Indication
uca Use Customer Address
sid Service Instance ID
============== ====================
"""
_PACK_STR = "!I"
_MIN_LEN = struct.calcsize(_PACK_STR)
def __init__(self, pcp=0, dei=0, uca=0, sid=0):
super(itag, self).__init__()
self.pcp = pcp
self.dei = dei
self.uca = uca
self.sid = sid
@classmethod
def parser(cls, buf):
(data, ) = struct.unpack_from(cls._PACK_STR, buf)
pcp = data >> 29
dei = data >> 28 & 1
uca = data >> 27 & 1
sid = data & 0x00ffffff
# circular import: ethernet -> vlan -> pbb
from os_ken.lib.packet import ethernet
return (cls(pcp, dei, uca, sid), ethernet.ethernet,
buf[cls._MIN_LEN:])
def serialize(self, payload, prev):
data = self.pcp << 29 | self.dei << 28 | self.uca << 27 | self.sid
return struct.pack(self._PACK_STR, data)
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