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# encoding: utf-8 |
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""" |
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Copyright (c) 2016 Evelio Vila <[email protected]> |
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Copyright (c) 2009-2017 Exa Networks. All rights reserved. |
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License: 3-clause BSD. (See the COPYRIGHT file) |
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""" |
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import json |
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import binascii |
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import itertools |
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from struct import unpack |
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from exabgp.bgp.message.notification import Notify |
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from exabgp.bgp.message.update.attribute.attribute import Attribute |
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@Attribute.register() |
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class LinkState(Attribute): |
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ID = Attribute.CODE.BGP_LS |
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FLAG = Attribute.Flag.OPTIONAL |
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TLV = -1 |
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# Registered subclasses we know how to decode |
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registered_lsids = dict() |
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# what this implementation knows as LS attributes |
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node_lsids = [] |
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link_lsids = [] |
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prefix_lsids = [] |
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def __init__(self, ls_attrs): |
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self.ls_attrs = ls_attrs |
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@classmethod |
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def register(cls, lsid=None, flag=None): |
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def register_lsid(klass): |
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if not hasattr(klass, 'MERGE'): |
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klass.MERGE = False |
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scode = klass.TLV if lsid is None else lsid |
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if scode in cls.registered_lsids: |
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raise RuntimeError('only one class can be registered per BGP link state attribute type') |
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cls.registered_lsids[scode] = klass |
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return klass |
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return register_lsid |
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@classmethod |
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def klass(cls, code): |
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return cls.registered_lsids.get(code, GenericLSID) |
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@classmethod |
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def registered(cls, lsid, flag=None): |
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return lsid in cls.registered_lsids |
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@classmethod |
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def unpack(cls, data, negotiated): |
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ls_attrs = [] |
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while data: |
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scode, length = unpack('!HH', data[:4]) |
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klass = cls.klass(scode).unpack(data[4: length + 4], length) |
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klass.TLV = scode |
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data = data[length + 4:] |
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if klass.MERGE: |
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for k in ls_attrs: |
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if k.TLV == klass.TLV: |
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k.merge(k) |
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continue |
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ls_attrs.append(klass) |
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return cls(ls_attrs=ls_attrs) |
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def json(self, compact=None): |
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content = ', '.join(d.json() for d in self.ls_attrs) |
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return '{ %s }' % (content) |
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def __str__(self): |
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return ', '.join(str(d) for d in self.ls_attrs) |
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class BaseLS(object): |
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TLV = -1 |
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TLV = -1 |
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JSON = 'json-name-unset' |
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REPR = 'repr name unset' |
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LEN = None |
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def __init__(self, content): |
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self.content = content |
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def json(self, compact=None): |
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return '"{}": {}'.format(self.JSON, json.dumps(self.content)) |
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def __repr__(self): |
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return "%s: %s" % (self.REPR, self.content) |
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@classmethod |
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def check(cls, length): |
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if cls.LEN is not None and length != cls.LEN: |
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raise Notify(3, 5, f'Unable to decode attribute, wrong size for {cls.REPR}') |
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class GenericLSID(BaseLS): |
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def __init__(self, code, content): |
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BaseLS.__init__(self, content) |
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self.code = code |
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def __repr__(self): |
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return "Attribute with code [ %s ] not implemented" % (self.code) |
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def json(self): |
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return '"generic-LSID-{}": {}'.format(self.code, json.dumps(self.content)) |
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@classmethod |
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def unpack(cls, scode, data): |
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return cls(scode, binascii.b2a_uu(data[:])) |
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class FlagLS(BaseLS): |
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def __init__(self, flags): |
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self.flags = flags |
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def __repr__(self): |
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return "%s: %s" % (self.REPR, self.flags) |
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def json(self, compact=None): |
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return '"{}": {}'.format(self.JSON, json.dumps(self.flags)) |
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@classmethod |
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def unpack_flags(cls, data): |
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pad = cls.FLAGS.count('RSV') |
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repeat = len(cls.FLAGS) - pad |
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hex_rep = int(binascii.b2a_hex(data), 16) |
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bits = f'{hex_rep:08b}' |
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valid_flags = [ |
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''.join(item) + '0' * pad |
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for item in itertools.product('01', repeat=repeat) |
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] |
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valid_flags.append('0000') |
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if bits in valid_flags: |
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flags = dict(zip(cls.FLAGS, [0, ] * len(cls.FLAGS))) |
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flags.update(dict((k, int(v)) for k, v in zip(cls.FLAGS, bits))) |
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else: |
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raise Notify(3, 5, "Invalid SR flags mask") |
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return flags |
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@classmethod |
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def unpack(cls, data, length): |
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cls.check(length) |
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# We only support IS-IS for now. |
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return cls(cls.unpack_flags(data[0:1])) |
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Exa-Networks /
exabgp
