openstack/os-ken
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packet lib: add BFD support.

Browse Source 
Signed-off-by: Wei-Li Tang <alextwl@xinguard.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
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Wei-Li Tang 2014-10-08 19:43:33 +08:00 committed by FUJITA Tomonori
parent bcc2c13484
commit d1f9408314
1 changed files with 744 additions and 0 deletions
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ryu/lib/packet/bfd.py Normal file
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# Copyright (C) 2014 Xinguard, Inc.
#
# 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.
"""
BFD Control packet parser/serializer
RFC 5880
BFD Control packet format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers | Diag |Sta|P|F|C|A|D|M| Detect Mult | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Your Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Desired Min TX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Min RX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Min Echo RX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An optional Authentication Section MAY be present in the following
format of types:
1. Format of Simple Password Authentication Section
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Type | Auth Len | Auth Key ID | Password... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2. Format of Keyed MD5 and Meticulous Keyed MD5 Authentication Section
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Type | Auth Len | Auth Key ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Key/Digest... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3. Format of Keyed SHA1 and Meticulous Keyed SHA1 Authentication Section
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Type | Auth Len | Auth Key ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Auth Key/Hash... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
"""
import binascii
import hashlib
import random
import struct
from . import packet_base
from ryu.lib import addrconv
from ryu.lib import stringify
BFD_STATE_ADMIN_DOWN = 0
BFD_STATE_DOWN = 1
BFD_STATE_INIT = 2
BFD_STATE_UP = 3
BFD_STATE_NAME = {0: "AdminDown",
1: "Down",
2: "Init",
3: "Up"}
BFD_FLAG_POLL = 1 << 5
BFD_FLAG_FINAL = 1 << 4
BFD_FLAG_CTRL_PLANE_INDEP = 1 << 3
BFD_FLAG_AUTH_PRESENT = 1 << 2
BFD_FLAG_DEMAND = 1 << 1
BFD_FLAG_MULTIPOINT = 1
BFD_DIAG_NO_DIAG = 0
BFD_DIAG_CTRL_DETECT_TIME_EXPIRED = 1
BFD_DIAG_ECHO_FUNC_FAILED = 2
BFD_DIAG_NEIG_SIG_SESS_DOWN = 3
BFD_DIAG_FWD_PLANE_RESET = 4
BFD_DIAG_PATH_DOWN = 5
BFD_DIAG_CONCAT_PATH_DOWN = 6
BFD_DIAG_ADMIN_DOWN = 7
BFD_DIAG_REV_CONCAT_PATH_DOWN = 8
BFD_DIAG_CODE_NAME = {0: "No Diagnostic",
1: "Control Detection Time Expired",
2: "Echo Function Failed",
3: "Neighbor Signaled Session Down",
4: "Forwarding Plane Reset",
5: "Path Down",
6: "Concatenated Path Down",
7: "Administratively Down",
8: "Reverse Concatenated Path Down"}
BFD_AUTH_RESERVED = 0
BFD_AUTH_SIMPLE_PASS = 1
BFD_AUTH_KEYED_MD5 = 2
BFD_AUTH_METICULOUS_KEYED_MD5 = 3
BFD_AUTH_KEYED_SHA1 = 4
BFD_AUTH_METICULOUS_KEYED_SHA1 = 5
BFD_AUTH_TYPE_NAME = {0: "Reserved",
1: "Simple Password",
2: "Keyed MD5",
3: "Meticulous Keyed MD5",
4: "Keyed SHA1",
5: "Meticulous Keyed SHA1"}
class bfd(packet_base.PacketBase):
"""BFD (RFC 5880) Control packet encoder/decoder class.
The serialized packet would looks like the ones described
in the following sections.
* RFC 5880 Generic BFD Control Packet Format
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
============================== ============================================
ver The version number of the protocol.
This class implements protocol version 1.
diag A diagnostic code specifying the local
system's reason for the last change in
session state.
state The current BFD session state as seen by
the transmitting system.
flags Bitmap of the following flags.
| BFD_FLAG_POLL
| BFD_FLAG_FINAL
| BFD_FLAG_CTRL_PLANE_INDEP
| BFD_FLAG_AUTH_PRESENT
| BFD_FLAG_DEMAND
| BFD_FLAG_MULTIPOINT
detect_mult Detection time multiplier.
my_discr My Discriminator.
your_discr Your Discriminator.
desired_min_tx_interval Desired Min TX Interval. (in microseconds)
required_min_rx_interval Required Min RX Interval. (in microseconds)
required_min_echo_rx_interval Required Min Echo RX Interval.
(in microseconds)
auth_cls (Optional) Authentication Section instance.
It's defined only when the Authentication
Present (A) bit is set in flags.
Assign an instance of the following classes:
``SimplePassword``, ``KeyedMD5``,
``MeticulousKeyedMD5``, ``KeyedSHA1``, and
``MeticulousKeyedSHA1``.
length (Optional) Length of the BFD Control packet,
in bytes.
============================== ============================================
"""
_PACK_STR = '!BBBBIIIII'
_PACK_STR_LEN = struct.calcsize(_PACK_STR)
_TYPE = {
'ascii': []
}
_auth_parsers = {}
def __init__(self, ver=1, diag=0, state=0, flags=0, detect_mult=0,
my_discr=0, your_discr=0, desired_min_tx_interval=0,
required_min_rx_interval=0, required_min_echo_rx_interval=0,
auth_cls=None, length=None):
super(bfd, self).__init__()
self.ver = ver
self.diag = diag
self.state = state
self.flags = flags
self.detect_mult = detect_mult
self.my_discr = my_discr
self.your_discr = your_discr
self.desired_min_tx_interval = desired_min_tx_interval
self.required_min_rx_interval = required_min_rx_interval
self.required_min_echo_rx_interval = required_min_echo_rx_interval
self.auth_cls = auth_cls
if isinstance(length, int):
self.length = length
else:
self.length = len(self)
def __len__(self):
if self.flags & BFD_FLAG_AUTH_PRESENT and self.auth_cls is not None:
return self._PACK_STR_LEN + len(self.auth_cls)
else:
return self._PACK_STR_LEN
@classmethod
def parser(cls, buf):
(diag, flags, detect_mult, length, my_discr, your_discr,
desired_min_tx_interval, required_min_rx_interval,
required_min_echo_rx_interval) = \
struct.unpack_from(cls._PACK_STR, buf[:cls._PACK_STR_LEN])
ver = diag >> 5
diag = diag & 0x1f
state = flags >> 6
flags = flags & 0x3f
if flags & BFD_FLAG_AUTH_PRESENT:
(auth_type,) = struct.unpack_from('!B', buf[cls._PACK_STR_LEN])
auth_cls = cls._auth_parsers[auth_type].\
parser(buf[cls._PACK_STR_LEN:])[0]
else:
auth_cls = None
msg = cls(ver, diag, state, flags, detect_mult,
my_discr, your_discr, desired_min_tx_interval,
required_min_rx_interval, required_min_echo_rx_interval,
auth_cls)
return msg, None, None
def serialize(self, payload, prev):
if self.flags & BFD_FLAG_AUTH_PRESENT and self.auth_cls is not None:
return self.pack() + \
self.auth_cls.serialize(payload=None, prev=self)
else:
return self.pack()
def pack(self):
"""
Encode a BFD Control packet without authentication section.
"""
diag = (self.ver << 5) + self.diag
flags = (self.state << 6) + self.flags
length = len(self)
return struct.pack(self._PACK_STR, diag, flags, self.detect_mult,
length, self.my_discr, self.your_discr,
self.desired_min_tx_interval,
self.required_min_rx_interval,
self.required_min_echo_rx_interval)
def authenticate(self, *args, **kwargs):
"""Authenticate this packet.
Returns a boolean indicates whether the packet can be authenticated
or not.
Returns ``False`` if the Authentication Present (A) is not set in the
flag of this packet.
Returns ``False`` if the Authentication Section for this packet is not
present.
For the description of the arguemnts of this method, refer to the
authentication method of the Authentication Section classes.
"""
if not self.flags & BFD_FLAG_AUTH_PRESENT or \
not issubclass(self.auth_cls.__class__, BFDAuth):
return False
return self.auth_cls.authenticate(self, *args, **kwargs)
@classmethod
def set_auth_parser(cls, auth_cls):
cls._auth_parsers[auth_cls.auth_type] = auth_cls
@classmethod
def register_auth_type(cls, auth_type):
def _set_type(auth_cls):
auth_cls.set_type(auth_cls, auth_type)
cls.set_auth_parser(auth_cls)
return auth_cls
return _set_type
class BFDAuth(stringify.StringifyMixin):
"""Base class of BFD (RFC 5880) Authentication Section
An instance has the following attributes at least.
Most of them are same to the on-wire counterparts but in host byte order.
.. tabularcolumns:: |l|L|
=========== ============================================
Attribute Description
=========== ============================================
auth_type The authentication type in use.
auth_len The length, in bytes, of the authentication
section, including the ``auth_type`` and
``auth_len`` fields.
=========== ============================================
"""
_PACK_HDR_STR = '!BB'
_PACK_HDR_STR_LEN = struct.calcsize(_PACK_HDR_STR)
auth_type = None
def __init__(self, auth_len=None):
super(BFDAuth, self).__init__()
if isinstance(auth_len, int):
self.auth_len = auth_len
else:
self.auth_len = len(self)
@staticmethod
def set_type(subcls, auth_type):
assert issubclass(subcls, BFDAuth)
subcls.auth_type = auth_type
@classmethod
def parser_hdr(cls, buf):
"""
Parser for common part of authentication section.
"""
return struct.unpack_from(cls._PACK_HDR_STR,
buf[:cls._PACK_HDR_STR_LEN])
def serialize_hdr(self):
"""
Serialization function for common part of authentication section.
"""
return struct.pack(self._PACK_HDR_STR, self.auth_type, self.auth_len)
@bfd.register_auth_type(BFD_AUTH_SIMPLE_PASS)
class SimplePassword(BFDAuth):
""" BFD (RFC 5880) Simple Password Authentication Section class
An instance has the following attributes.
Most of them are same to the on-wire counterparts but in host byte order.
.. tabularcolumns:: |l|L|
=========== ============================================
Attribute Description
=========== ============================================
auth_type (Fixed) The authentication type in use.
auth_key_id The authentication Key ID in use.
password The simple password in use on this session.
The password is a binary string, and MUST be
from 1 to 16 bytes in length.
auth_len The length, in bytes, of the authentication
section, including the ``auth_type`` and
``auth_len`` fields.
=========== ============================================
"""
_PACK_STR = '!B'
_PACK_STR_LEN = struct.calcsize(_PACK_STR)
def __init__(self, auth_key_id, password, auth_len=None):
assert len(password) >= 1 and len(password) <= 16
self.auth_key_id = auth_key_id
self.password = password
super(SimplePassword, self).__init__(auth_len)
def __len__(self):
return self._PACK_HDR_STR_LEN + self._PACK_STR_LEN + len(self.password)
@classmethod
def parser(cls, buf):
(auth_type, auth_len) = cls.parser_hdr(buf)
assert auth_type == cls.auth_type
(auth_key_id,) = struct.unpack_from(cls._PACK_STR,
buf[cls._PACK_HDR_STR_LEN])
password = buf[cls._PACK_HDR_STR_LEN + cls._PACK_STR_LEN:auth_len]
msg = cls(auth_key_id, password, auth_len)
return msg, None, None
def serialize(self, payload, prev):
"""Encode a Simple Password Authentication Section.
``payload`` is the rest of the packet which will immediately follow
this section.
``prev`` is a ``bfd`` instance for the BFD Control header. It's not
necessary for encoding only the Simple Password section.
"""
return self.serialize_hdr() + \
struct.pack(self._PACK_STR, self.auth_key_id) + self.password
def authenticate(self, prev=None, auth_keys={}):
"""Authenticate the password for this packet.
This method can be invoked only when ``self.password`` is defined.
Returns a boolean indicates whether the password can be authenticated
or not.
``prev`` is a ``bfd`` instance for the BFD Control header. It's not
necessary for authenticating the Simple Password.
``auth_keys`` is a dictionary of authentication key chain which
key is an integer of *Auth Key ID* and value is a string of *Password*.
"""
assert isinstance(prev, bfd)
if self.auth_key_id in auth_keys and \
self.password == auth_keys[self.auth_key_id]:
return True
else:
return False
@bfd.register_auth_type(BFD_AUTH_KEYED_MD5)
class KeyedMD5(BFDAuth):
""" BFD (RFC 5880) Keyed MD5 Authentication Section class
An instance has the following attributes.
Most of them are same to the on-wire counterparts but in host byte order.
.. tabularcolumns:: |l|L|
=========== =================================================
Attribute Description
=========== =================================================
auth_type (Fixed) The authentication type in use.
auth_key_id The authentication Key ID in use.
seq The sequence number for this packet.
This value is incremented occasionally.
auth_key The shared MD5 key for this packet.
digest (Optional) The 16-byte MD5 digest for the packet.
auth_len (Fixed) The length of the authentication section
is 24 bytes.
=========== =================================================
"""
_PACK_STR = '!BBL16s'
_PACK_STR_LEN = struct.calcsize(_PACK_STR)
def __init__(self, auth_key_id, seq, auth_key=None, digest=None,
auth_len=None):
self.auth_key_id = auth_key_id
self.seq = seq
self.auth_key = auth_key
self.digest = digest
super(KeyedMD5, self).__init__(auth_len)
def __len__(self):
# Defined in RFC5880 Section 4.3.
return 24
@classmethod
def parser(cls, buf):
(auth_type, auth_len) = cls.parser_hdr(buf)
assert auth_type == cls.auth_type
assert auth_len == 24
(auth_key_id, reserved, seq, digest) = \
struct.unpack_from(cls._PACK_STR, buf[cls._PACK_HDR_STR_LEN:])
assert reserved == 0
msg = cls(auth_key_id=auth_key_id, seq=seq, auth_key=None,
digest=digest)
return msg, None, None
def serialize(self, payload, prev):
"""Encode a Keyed MD5 Authentication Section.
This method is used only when encoding an BFD Control packet.
``payload`` is the rest of the packet which will immediately follow
this section.
``prev`` is a ``bfd`` instance for the BFD Control header which this
authentication section belongs to. It's necessary to be assigned
because an MD5 digest must be calculated over the entire BFD Control
packet.
"""
assert self.auth_key is not None and len(self.auth_key) <= 16
assert isinstance(prev, bfd)
bfd_bin = prev.pack()
auth_hdr_bin = self.serialize_hdr()
auth_data_bin = struct.pack(self._PACK_STR, self.auth_key_id, 0,
self.seq, self.auth_key +
''.join(['\x00' *
(len(self.auth_key) - 16)]))
h = hashlib.md5()
h.update(bfd_bin + auth_hdr_bin + auth_data_bin)
self.digest = h.digest()
return auth_hdr_bin + struct.pack(self._PACK_STR, self.auth_key_id, 0,
self.seq, self.digest)
def authenticate(self, prev, auth_keys={}):
"""Authenticate the MD5 digest for this packet.
This method can be invoked only when ``self.digest`` is defined.
Returns a boolean indicates whether the digest can be authenticated
by the correspondent Auth Key or not.
``prev`` is a ``bfd`` instance for the BFD Control header which this
authentication section belongs to. It's necessary to be assigned
because an MD5 digest must be calculated over the entire BFD Control
packet.
``auth_keys`` is a dictionary of authentication key chain which
key is an integer of *Auth Key ID* and value is a string of *Auth Key*.
"""
assert isinstance(prev, bfd)
if self.digest is None:
return False
if self.auth_key_id not in auth_keys:
return False
auth_key = auth_keys[self.auth_key_id]
bfd_bin = prev.pack()
auth_hdr_bin = self.serialize_hdr()
auth_data_bin = struct.pack(self._PACK_STR, self.auth_key_id, 0,
self.seq, auth_key +
''.join(['\x00' * (len(auth_key) - 16)]))
h = hashlib.md5()
h.update(bfd_bin + auth_hdr_bin + auth_data_bin)
if self.digest == h.digest():
return True
else:
return False
@bfd.register_auth_type(BFD_AUTH_METICULOUS_KEYED_MD5)
class MeticulousKeyedMD5(KeyedMD5):
""" BFD (RFC 5880) Meticulous Keyed MD5 Authentication Section class
All methods of this class are inherited from ``KeyedMD5``.
An instance has the following attributes.
Most of them are same to the on-wire counterparts but in host byte order.
.. tabularcolumns:: |l|L|
=========== =================================================
Attribute Description
=========== =================================================
auth_type (Fixed) The authentication type in use.
auth_key_id The authentication Key ID in use.
seq The sequence number for this packet.
This value is incremented for each
successive packet transmitted for a session.
auth_key The shared MD5 key for this packet.
digest (Optional) The 16-byte MD5 digest for the packet.
auth_len (Fixed) The length of the authentication section
is 24 bytes.
=========== =================================================
"""
pass
@bfd.register_auth_type(BFD_AUTH_KEYED_SHA1)
class KeyedSHA1(BFDAuth):
""" BFD (RFC 5880) Keyed SHA1 Authentication Section class
An instance has the following attributes.
Most of them are same to the on-wire counterparts but in host byte order.
.. tabularcolumns:: |l|L|
=========== ================================================
Attribute Description
=========== ================================================
auth_type (Fixed) The authentication type in use.
auth_key_id The authentication Key ID in use.
seq The sequence number for this packet.
This value is incremented occasionally.
auth_key The shared SHA1 key for this packet.
auth_hash (Optional) The 20-byte SHA1 hash for the packet.
auth_len (Fixed) The length of the authentication section
is 28 bytes.
=========== ================================================
"""
_PACK_STR = '!BBL20s'
_PACK_STR_LEN = struct.calcsize(_PACK_STR)
def __init__(self, auth_key_id, seq, auth_key=None, auth_hash=None,
auth_len=None):
self.auth_key_id = auth_key_id
self.seq = seq
self.auth_key = auth_key
self.auth_hash = auth_hash
super(KeyedSHA1, self).__init__(auth_len)
def __len__(self):
# Defined in RFC5880 Section 4.4.
return 28
@classmethod
def parser(cls, buf):
(auth_type, auth_len) = cls.parser_hdr(buf)
assert auth_type == cls.auth_type
assert auth_len == 28
(auth_key_id, reserved, seq, auth_hash) = \
struct.unpack_from(cls._PACK_STR, buf[cls._PACK_HDR_STR_LEN:])
assert reserved == 0
msg = cls(auth_key_id=auth_key_id, seq=seq, auth_key=None,
auth_hash=auth_hash)
return msg, None, None
def serialize(self, payload, prev):
"""Encode a Keyed SHA1 Authentication Section.
This method is used only when encoding an BFD Control packet.
``payload`` is the rest of the packet which will immediately follow
this section.
``prev`` is a ``bfd`` instance for the BFD Control header which this
authentication section belongs to. It's necessary to be assigned
because an SHA1 hash must be calculated over the entire BFD Control
packet.
"""
assert self.auth_key is not None and len(self.auth_key) <= 20
assert isinstance(prev, bfd)
bfd_bin = prev.pack()
auth_hdr_bin = self.serialize_hdr()
auth_data_bin = struct.pack(self._PACK_STR, self.auth_key_id, 0,
self.seq, self.auth_key +
''.join(['\x00' *
(len(self.auth_key) - 20)]))
h = hashlib.sha1()
h.update(bfd_bin + auth_hdr_bin + auth_data_bin)
self.auth_hash = h.digest()
return auth_hdr_bin + struct.pack(self._PACK_STR, self.auth_key_id, 0,
self.seq, self.auth_hash)
def authenticate(self, prev, auth_keys={}):
"""Authenticate the SHA1 hash for this packet.
This method can be invoked only when ``self.auth_hash`` is defined.
Returns a boolean indicates whether the hash can be authenticated
by the correspondent Auth Key or not.
``prev`` is a ``bfd`` instance for the BFD Control header which this
authentication section belongs to. It's necessary to be assigned
because an SHA1 hash must be calculated over the entire BFD Control
packet.
``auth_keys`` is a dictionary of authentication key chain which
key is an integer of *Auth Key ID* and value is a string of *Auth Key*.
"""
assert isinstance(prev, bfd)
if self.auth_hash is None:
return False
if self.auth_key_id not in auth_keys:
return False
auth_key = auth_keys[self.auth_key_id]
bfd_bin = prev.pack()
auth_hdr_bin = self.serialize_hdr()
auth_data_bin = struct.pack(self._PACK_STR, self.auth_key_id, 0,
self.seq, auth_key +
''.join(['\x00' * (len(auth_key) - 20)]))
h = hashlib.sha1()
h.update(bfd_bin + auth_hdr_bin + auth_data_bin)
if self.auth_hash == h.digest():
return True
else:
return False
@bfd.register_auth_type(BFD_AUTH_METICULOUS_KEYED_SHA1)
class MeticulousKeyedSHA1(KeyedSHA1):
""" BFD (RFC 5880) Meticulous Keyed SHA1 Authentication Section class
All methods of this class are inherited from ``KeyedSHA1``.
An instance has the following attributes.
Most of them are same to the on-wire counterparts but in host byte order.
.. tabularcolumns:: |l|L|
=========== ================================================
Attribute Description
=========== ================================================
auth_type (Fixed) The authentication type in use.
auth_key_id The authentication Key ID in use.
seq The sequence number for this packet.
This value is incremented for each
successive packet transmitted for a session.
auth_key The shared SHA1 key for this packet.
auth_hash (Optional) The 20-byte SHA1 hash for the packet.
auth_len (Fixed) The length of the authentication section
is 28 bytes.
=========== ================================================
"""
pass
bfd.set_classes(bfd._auth_parsers)