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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.
"""
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
|
