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# Copyright (C) 2012 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 abc
import struct
from . import packet_base
from . import arp
from . import ipv4
from . import ipv6
from . import lldp
from . import slow
from . import llc
from . import pbb
from . import cfm
from . import ether_types as ether
class _vlan(packet_base.PacketBase, metaclass=abc.ABCMeta):
_PACK_STR = "!HH"
_MIN_LEN = struct.calcsize(_PACK_STR)
@abc.abstractmethod
def __init__(self, pcp, cfi, vid, ethertype):
super(_vlan, self).__init__()
self.pcp = pcp
self.cfi = cfi
self.vid = vid
self.ethertype = ethertype
@classmethod
def parser(cls, buf):
tci, ethertype = struct.unpack_from(cls._PACK_STR, buf)
pcp = tci >> 13
cfi = (tci >> 12) & 1
vid = tci & ((1 << 12) - 1)
return (cls(pcp, cfi, vid, ethertype),
vlan.get_packet_type(ethertype), buf[vlan._MIN_LEN:])
def serialize(self, payload, prev):
tci = self.pcp << 13 | self.cfi << 12 | self.vid
return struct.pack(vlan._PACK_STR, tci, self.ethertype)
class vlan(_vlan):
"""VLAN (IEEE 802.1Q) 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
cfi Canonical Format Indicator
vid VLAN Identifier
ethertype EtherType
============== ====================
"""
def __init__(self, pcp=0, cfi=0, vid=0, ethertype=ether.ETH_TYPE_IP):
super(vlan, self).__init__(pcp, cfi, vid, ethertype)
@classmethod
def get_packet_type(cls, type_):
"""Override method for the Length/Type field (self.ethertype).
The Length/Type field means Length or Type interpretation,
same as ethernet IEEE802.3.
If the value of Length/Type field is less than or equal to
1500 decimal(05DC hexadecimal), it means Length interpretation
and be passed to the LLC sublayer."""
if type_ <= ether.ETH_TYPE_IEEE802_3:
type_ = ether.ETH_TYPE_IEEE802_3
return cls._TYPES.get(type_)
class svlan(_vlan):
"""S-VLAN (IEEE 802.1ad) 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.
.. tabularcolumns:: |l|L|
============== ====================
Attribute Description
============== ====================
pcp Priority Code Point
cfi Canonical Format Indicator.
In a case to be used as B-TAG,
this field means DEI(Drop Eligible Indication).
vid VLAN Identifier
ethertype EtherType
============== ====================
"""
def __init__(self, pcp=0, cfi=0, vid=0, ethertype=ether.ETH_TYPE_8021Q):
super(svlan, self).__init__(pcp, cfi, vid, ethertype)
@classmethod
def get_packet_type(cls, type_):
return cls._TYPES.get(type_)
vlan.register_packet_type(arp.arp, ether.ETH_TYPE_ARP)
vlan.register_packet_type(ipv4.ipv4, ether.ETH_TYPE_IP)
vlan.register_packet_type(ipv6.ipv6, ether.ETH_TYPE_IPV6)
vlan.register_packet_type(lldp.lldp, ether.ETH_TYPE_LLDP)
vlan.register_packet_type(slow.slow, ether.ETH_TYPE_SLOW)
vlan.register_packet_type(llc.llc, ether.ETH_TYPE_IEEE802_3)
vlan.register_packet_type(cfm.cfm, ether.ETH_TYPE_CFM)
svlan.register_packet_type(vlan, ether.ETH_TYPE_8021Q)
svlan.register_packet_type(pbb.itag, ether.ETH_TYPE_8021AH)
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