492 lines
21 KiB
Python
492 lines
21 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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"""
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Bridge Protocol Data Unit(BPDU, IEEE 802.1D) parser/serializer
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http://standards.ieee.org/getieee802/download/802.1D-2004.pdf
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Configuration BPDUs format
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+----------------------------------------------+---------+
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| Structure | Octet |
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+==============================================+=========+
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| Protocol Identifier = 0000 0000 0000 0000 | 1 - 2 |
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| | |
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+----------------------------------------------+---------+
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| Protocol Version Identifier = 0000 0000 | 3 |
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+----------------------------------------------+---------+
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| BPDU Type = 0000 0000 | 4 |
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+----------------------------------------------+---------+
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| Flags | 5 |
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+----------------------------------------------+---------+
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| Root Identifier | 6 - 13 |
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| include - priority | |
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| system ID extension | |
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| MAC address | |
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+----------------------------------------------+---------+
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| Root Path Cost | 14 - 17 |
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| | |
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+----------------------------------------------+---------+
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| Bridge Identifier | 18 - 25 |
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| include - priority | |
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| system ID extension | |
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| MAC address | |
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+----------------------------------------------+---------+
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| Port Identifier | 26 - 27 |
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| include - priority | |
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| port number | |
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+----------------------------------------------+---------+
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| Message Age | 28 - 29 |
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| | |
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+----------------------------------------------+---------+
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| Max Age | 30 - 31 |
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+----------------------------------------------+---------+
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| Hello Time | 32 - 33 |
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+----------------------------------------------+---------+
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| Forward Delay | 34 - 35 |
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+----------------------------------------------+---------+
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Topology Change NotificationBPDUs format
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+----------------------------------------------+---------+
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| Structure | Octet |
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+==============================================+=========+
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| Protocol Identifier = 0000 0000 0000 0000 | 1 - 2 |
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| | |
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+----------------------------------------------+---------+
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| Protocol Version Identifier = 0000 0000 | 3 |
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+----------------------------------------------+---------+
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| BPDU Type = 1000 0000 | 4 |
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+----------------------------------------------+---------+
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Rapid Spanning Tree BPDUs(RST BPDUs) format
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+----------------------------------------------+---------+
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| Structure | Octet |
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+==============================================+=========+
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| Protocol Identifier = 0000 0000 0000 0000 | 1 - 2 |
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+----------------------------------------------+---------+
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| Protocol Version Identifier = 0000 0010 | 3 |
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+----------------------------------------------+---------+
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| BPDU Type = 0000 0010 | 4 |
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+----------------------------------------------+---------+
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| Flags | 5 |
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+----------------------------------------------+---------+
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| Root Identifier | 6 - 13 |
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| include - priority | |
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| system ID extension | |
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| MAC address | |
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+----------------------------------------------+---------+
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| Root Path Cost | 14 - 17 |
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| | |
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+----------------------------------------------+---------+
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| Bridge Identifier | 18 - 25 |
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| include - priority | |
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| system ID extension | |
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| MAC address | |
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+----------------------------------------------+---------+
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| Port Identifier | 26 - 27 |
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| include - priority | |
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| port number | |
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+----------------------------------------------+---------+
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| Message Age | 28 - 29 |
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+----------------------------------------------+---------+
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| Max Age | 30 - 31 |
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| | |
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+----------------------------------------------+---------+
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| Hello Time | 32 - 33 |
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+----------------------------------------------+---------+
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| Forward Delay | 34 - 35 |
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+----------------------------------------------+---------+
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| Version 1 Length = 0000 0000 | 36 |
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+----------------------------------------------+---------+
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"""
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import binascii
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import struct
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from . import packet_base
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from os_ken.lib import addrconv
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# BPDU destination
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BRIDGE_GROUP_ADDRESS = '01:80:c2:00:00:00'
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PROTOCOL_IDENTIFIER = 0
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PROTOCOLVERSION_ID_BPDU = 0
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PROTOCOLVERSION_ID_RSTBPDU = 2
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TYPE_CONFIG_BPDU = 0
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TYPE_TOPOLOGY_CHANGE_BPDU = 128
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TYPE_RSTBPDU = 2
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DEFAULT_BRIDGE_PRIORITY = 32768
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DEFAULT_PORT_PRIORITY = 128
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PORT_PATH_COST_100KB = 200000000
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PORT_PATH_COST_1MB = 20000000
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PORT_PATH_COST_10MB = 2000000
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PORT_PATH_COST_100MB = 200000
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PORT_PATH_COST_1GB = 20000
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PORT_PATH_COST_10GB = 2000
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PORT_PATH_COST_100GB = 200
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PORT_PATH_COST_1TB = 20
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PORT_PATH_COST_10TB = 2
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DEFAULT_MAX_AGE = 20
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DEFAULT_HELLO_TIME = 2
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DEFAULT_FORWARD_DELAY = 15
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VERSION_1_LENGTH = 0
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class bpdu(packet_base.PacketBase):
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"""Bridge Protocol Data Unit(BPDU) header encoder/decoder base class.
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"""
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_PACK_STR = '!HBB'
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_PACK_LEN = struct.calcsize(_PACK_STR)
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_BPDU_TYPES = {}
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_MIN_LEN = _PACK_LEN
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@staticmethod
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def register_bpdu_type(sub_cls):
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bpdu._BPDU_TYPES.setdefault(sub_cls.VERSION_ID, {})
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bpdu._BPDU_TYPES[sub_cls.VERSION_ID][sub_cls.BPDU_TYPE] = sub_cls
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return sub_cls
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def __init__(self):
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super(bpdu, self).__init__()
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assert hasattr(self, 'VERSION_ID')
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assert hasattr(self, 'BPDU_TYPE')
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self._protocol_id = PROTOCOL_IDENTIFIER
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self._version_id = self.VERSION_ID
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self._bpdu_type = self.BPDU_TYPE
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if hasattr(self, 'check_parameters'):
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self.check_parameters()
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@classmethod
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def parser(cls, buf):
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assert len(buf) >= cls._PACK_LEN
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(protocol_id, version_id,
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bpdu_type) = struct.unpack_from(cls._PACK_STR, buf)
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assert protocol_id == PROTOCOL_IDENTIFIER
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if (version_id in cls._BPDU_TYPES
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and bpdu_type in cls._BPDU_TYPES[version_id]):
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bpdu_cls = cls._BPDU_TYPES[version_id][bpdu_type]
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assert len(buf[cls._PACK_LEN:]) >= bpdu_cls.PACK_LEN
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return bpdu_cls.parser(buf[cls._PACK_LEN:])
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else:
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# Unknown bpdu version/type.
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return buf, None, None
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def serialize(self, payload, prev):
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return struct.pack(bpdu._PACK_STR, self._protocol_id,
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self._version_id, self._bpdu_type)
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@bpdu.register_bpdu_type
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class ConfigurationBPDUs(bpdu):
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"""Configuration BPDUs(IEEE 802.1D) 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
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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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flags | Bit 1: Topology Change flag
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| Bits 2 through 7: unused and take the value 0
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| Bit 8: Topology Change Acknowledgment flag
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root_priority Root Identifier priority \
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set 0-61440 in steps of 4096
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root_system_id_extension Root Identifier system ID extension
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root_mac_address Root Identifier MAC address
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root_path_cost Root Path Cost
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bridge_priority Bridge Identifier priority \
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set 0-61440 in steps of 4096
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bridge_system_id_extension Bridge Identifier system ID extension
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bridge_mac_address Bridge Identifier MAC address
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port_priority Port Identifier priority \
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set 0-240 in steps of 16
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port_number Port Identifier number
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message_age Message Age timer value
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max_age Max Age timer value
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hello_time Hello Time timer value
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forward_delay Forward Delay timer value
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========================== ===============================================
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"""
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VERSION_ID = PROTOCOLVERSION_ID_BPDU
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BPDU_TYPE = TYPE_CONFIG_BPDU
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_PACK_STR = '!BQIQHHHHH'
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PACK_LEN = struct.calcsize(_PACK_STR)
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_TYPE = {
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'ascii': [
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'root_mac_address', "bridge_mac_address"
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]
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}
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_BRIDGE_PRIORITY_STEP = 4096
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_PORT_PRIORITY_STEP = 16
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_TIMER_STEP = float(1) / 256
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def __init__(self, flags=0, root_priority=DEFAULT_BRIDGE_PRIORITY,
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root_system_id_extension=0,
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root_mac_address='00:00:00:00:00:00',
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root_path_cost=0, bridge_priority=DEFAULT_BRIDGE_PRIORITY,
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bridge_system_id_extension=0,
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bridge_mac_address='00:00:00:00:00:00',
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port_priority=DEFAULT_PORT_PRIORITY, port_number=0,
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message_age=0, max_age=DEFAULT_MAX_AGE,
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hello_time=DEFAULT_HELLO_TIME,
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forward_delay=DEFAULT_FORWARD_DELAY):
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self.flags = flags
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self.root_priority = root_priority
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self.root_system_id_extension = root_system_id_extension
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self.root_mac_address = root_mac_address
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self.root_path_cost = root_path_cost
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self.bridge_priority = bridge_priority
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self.bridge_system_id_extension = bridge_system_id_extension
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self.bridge_mac_address = bridge_mac_address
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self.port_priority = port_priority
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self.port_number = port_number
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self.message_age = message_age
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self.max_age = max_age
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self.hello_time = hello_time
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self.forward_delay = forward_delay
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super(ConfigurationBPDUs, self).__init__()
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def check_parameters(self):
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assert (self.flags >> 1 & 0b111111) == 0
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assert self.root_priority % self._BRIDGE_PRIORITY_STEP == 0
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assert self.bridge_priority % self._BRIDGE_PRIORITY_STEP == 0
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assert self.port_priority % self._PORT_PRIORITY_STEP == 0
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assert self.message_age % self._TIMER_STEP == 0
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assert self.max_age % self._TIMER_STEP == 0
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assert self.hello_time % self._TIMER_STEP == 0
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assert self.forward_delay % self._TIMER_STEP == 0
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@classmethod
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def parser(cls, buf):
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(flags, root_id, root_path_cost, bridge_id,
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port_id, message_age, max_age, hello_time,
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forward_delay) = struct.unpack_from(ConfigurationBPDUs._PACK_STR, buf)
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(root_priority,
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root_system_id_extension,
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root_mac_address) = cls._decode_bridge_id(root_id)
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(bridge_priority,
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bridge_system_id_extension,
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bridge_mac_address) = cls._decode_bridge_id(bridge_id)
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(port_priority,
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port_number) = cls._decode_port_id(port_id)
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return (cls(flags, root_priority, root_system_id_extension,
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root_mac_address, root_path_cost,
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bridge_priority, bridge_system_id_extension,
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bridge_mac_address, port_priority, port_number,
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cls._decode_timer(message_age),
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cls._decode_timer(max_age),
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cls._decode_timer(hello_time),
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cls._decode_timer(forward_delay)),
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None, buf[ConfigurationBPDUs.PACK_LEN:])
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def serialize(self, payload, prev):
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base = super(ConfigurationBPDUs, self).serialize(payload, prev)
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root_id = self.encode_bridge_id(self.root_priority,
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self.root_system_id_extension,
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self.root_mac_address)
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bridge_id = self.encode_bridge_id(self.bridge_priority,
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self.bridge_system_id_extension,
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self.bridge_mac_address)
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port_id = self.encode_port_id(self.port_priority,
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self.port_number)
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sub = struct.pack(ConfigurationBPDUs._PACK_STR,
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self.flags,
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root_id,
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self.root_path_cost,
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bridge_id,
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port_id,
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self._encode_timer(self.message_age),
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self._encode_timer(self.max_age),
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self._encode_timer(self.hello_time),
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self._encode_timer(self.forward_delay))
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return base + sub
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@staticmethod
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def _decode_bridge_id(bridge_id):
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priority = (bridge_id >> 48) & 0xf000
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system_id_extension = (bridge_id >> 48) & 0xfff
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mac_addr = bridge_id & 0xffffffffffff
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mac_addr_list = [format((mac_addr >> (8 * i)) & 0xff, '02x')
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for i in range(0, 6)]
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mac_addr_list.reverse()
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mac_address_bin = binascii.a2b_hex(''.join(mac_addr_list))
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mac_address = addrconv.mac.bin_to_text(mac_address_bin)
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return priority, system_id_extension, mac_address
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@staticmethod
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def encode_bridge_id(priority, system_id_extension, mac_address):
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mac_addr = int(binascii.hexlify(addrconv.mac.text_to_bin(mac_address)),
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16)
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return ((priority + system_id_extension) << 48) + mac_addr
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@staticmethod
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def _decode_port_id(port_id):
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priority = port_id >> 8 & 0xf0
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port_number = port_id & 0xfff
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return priority, port_number
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@staticmethod
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def encode_port_id(priority, port_number):
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return (priority << 8) + port_number
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@staticmethod
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def _decode_timer(timer):
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return timer / float(0x100)
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@staticmethod
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def _encode_timer(timer):
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return int(timer) * 0x100
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@bpdu.register_bpdu_type
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class TopologyChangeNotificationBPDUs(bpdu):
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"""Topology Change Notification BPDUs(IEEE 802.1D)
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header encoder/decoder class.
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"""
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VERSION_ID = PROTOCOLVERSION_ID_BPDU
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BPDU_TYPE = TYPE_TOPOLOGY_CHANGE_BPDU
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_PACK_STR = ''
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PACK_LEN = struct.calcsize(_PACK_STR)
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def __init__(self):
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super(TopologyChangeNotificationBPDUs, self).__init__()
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@classmethod
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def parser(cls, buf):
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return cls(), None, buf[bpdu._PACK_LEN:]
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@bpdu.register_bpdu_type
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class RstBPDUs(ConfigurationBPDUs):
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"""Rapid Spanning Tree BPDUs(RST BPDUs, IEEE 802.1D)
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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
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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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flags | Bit 1: Topology Change flag
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| Bit 2: Proposal flag
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| Bits 3 and 4: Port Role
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| Bit 5: Learning flag
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| Bit 6: Forwarding flag
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| Bit 7: Agreement flag
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| Bit 8: Topology Change Acknowledgment flag
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root_priority Root Identifier priority \
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set 0-61440 in steps of 4096
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root_system_id_extension Root Identifier system ID extension
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root_mac_address Root Identifier MAC address
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root_path_cost Root Path Cost
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bridge_priority Bridge Identifier priority \
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set 0-61440 in steps of 4096
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bridge_system_id_extension Bridge Identifier system ID extension
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bridge_mac_address Bridge Identifier MAC address
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port_priority Port Identifier priority \
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set 0-240 in steps of 16
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port_number Port Identifier number
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message_age Message Age timer value
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max_age Max Age timer value
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hello_time Hello Time timer value
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forward_delay Forward Delay timer value
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========================== ===========================================
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"""
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VERSION_ID = PROTOCOLVERSION_ID_RSTBPDU
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BPDU_TYPE = TYPE_RSTBPDU
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_PACK_STR = '!B'
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PACK_LEN = struct.calcsize(_PACK_STR)
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def __init__(self, flags=0, root_priority=DEFAULT_BRIDGE_PRIORITY,
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root_system_id_extension=0,
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root_mac_address='00:00:00:00:00:00',
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root_path_cost=0, bridge_priority=DEFAULT_BRIDGE_PRIORITY,
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bridge_system_id_extension=0,
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bridge_mac_address='00:00:00:00:00:00',
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port_priority=DEFAULT_PORT_PRIORITY, port_number=0,
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message_age=0, max_age=DEFAULT_MAX_AGE,
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hello_time=DEFAULT_HELLO_TIME,
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forward_delay=DEFAULT_FORWARD_DELAY):
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self._version_1_length = VERSION_1_LENGTH
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super(RstBPDUs, self).__init__(flags, root_priority,
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root_system_id_extension,
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root_mac_address, root_path_cost,
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bridge_priority,
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bridge_system_id_extension,
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bridge_mac_address,
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port_priority, port_number,
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message_age, max_age,
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hello_time, forward_delay)
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def check_parameters(self):
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assert self.root_priority % self._BRIDGE_PRIORITY_STEP == 0
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assert self.bridge_priority % self._BRIDGE_PRIORITY_STEP == 0
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assert self.port_priority % self._PORT_PRIORITY_STEP == 0
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assert self.message_age % self._TIMER_STEP == 0
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assert self.max_age % self._TIMER_STEP == 0
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assert self.hello_time % self._TIMER_STEP == 0
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assert self.forward_delay % self._TIMER_STEP == 0
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@classmethod
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def parser(cls, buf):
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get_cls, next_type, buf = super(RstBPDUs, cls).parser(buf)
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(version_1_length,) = struct.unpack_from(RstBPDUs._PACK_STR, buf)
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assert version_1_length == VERSION_1_LENGTH
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return get_cls, next_type, buf[RstBPDUs.PACK_LEN:]
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def serialize(self, payload, prev):
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base = super(RstBPDUs, self).serialize(payload, prev)
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sub = struct.pack(RstBPDUs._PACK_STR, self._version_1_length)
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return base + sub
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