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