def construct_attributes(attr_dict, asn4=False):
"""
construts BGP Update attirubte.
:param attr_dict: bgp attribute dictionary
:param asn4: support 4 bytes asn or not
"""
attr_raw_hex = b''
for type_code, value in attr_dict.items():
if type_code == bgp_cons.BGPTYPE_ORIGIN:
origin_hex = Origin.construct(value=value)
attr_raw_hex += origin_hex
elif type_code == bgp_cons.BGPTYPE_AS_PATH:
aspath_hex = ASPath.construct(value=value, asn4=asn4)
attr_raw_hex += aspath_hex
elif type_code == bgp_cons.BGPTYPE_NEXT_HOP:
nexthop_hex = NextHop.construct(value=value)
attr_raw_hex += nexthop_hex
elif type_code == bgp_cons.BGPTYPE_MULTI_EXIT_DISC:
med_hex = MED.construct(value=value)
attr_raw_hex += med_hex
elif type_code == bgp_cons.BGPTYPE_LOCAL_PREF:
localpre_hex = LocalPreference.construct(value=value)
attr_raw_hex += localpre_hex
elif type_code == bgp_cons.BGPTYPE_ATOMIC_AGGREGATE:
atomicaggregate_hex = AtomicAggregate.construct(value=value)
attr_raw_hex += atomicaggregate_hex
elif type_code == bgp_cons.BGPTYPE_AGGREGATOR:
aggregator_hex = Aggregator.construct(value=value, asn4=asn4)
attr_raw_hex += aggregator_hex
elif type_code == bgp_cons.BGPTYPE_COMMUNITIES:
community_hex = Community.construct(value=value)
attr_raw_hex += community_hex
elif type_code == bgp_cons.BGPTYPE_ORIGINATOR_ID:
originatorid_hex = OriginatorID.construct(value=value)
attr_raw_hex += originatorid_hex
elif type_code == bgp_cons.BGPTYPE_CLUSTER_LIST:
clusterlist_hex = ClusterList.construct(value=value)
attr_raw_hex += clusterlist_hex
elif type_code == bgp_cons.BGPTYPE_MP_REACH_NLRI:
mpreach_hex = MpReachNLRI().construct(value=value)
attr_raw_hex += mpreach_hex
elif type_code == bgp_cons.BGPTYPE_MP_UNREACH_NLRI:
mpunreach_hex = MpUnReachNLRI.construct(value=value)
attr_raw_hex += mpunreach_hex
elif type_code == bgp_cons.BGPTYPE_EXTENDED_COMMUNITY:
community_ext_hex = ExtCommunity.construct(value=value)
attr_raw_hex += community_ext_hex
elif type_code == bgp_cons.BGPTYPE_PMSI_TUNNEL:
evpn_overlay = EVPN.signal_evpn_overlay(attr_dict)
attr_raw_hex += PMSITunnel.construct(value=value,
evpn_overlay=evpn_overlay)
elif type_code == bgp_cons.BGPTYPE_TUNNEL_ENCAPS_ATTR:
tunnelencap_hex = TunnelEncaps.construct(value=value)
attr_raw_hex += tunnelencap_hex
elif type_code == bgp_cons.BGPTYPE_LARGE_COMMUNITY:
large_community_ext_hex = LargeCommunity.construct(value=value)
attr_raw_hex += large_community_ext_hex
return attr_raw_hex
def parse_attributes(data, asn4=False):
"""
Parses an RFC4271 encoded blob of BGP attributes into a list
:param data:
:param asn4: support 4 bytes asn or not
:return:
"""
attributes = {}
postfix = data
bgpls_pro_id = None
bgpls_attr = None
while len(postfix) > 0:
try:
flags, type_code = struct.unpack('!BB', postfix[:2])
if flags & AttributeFlag.EXTENDED_LENGTH:
attr_len = struct.unpack('!H', postfix[2:4])[0]
attr_value = postfix[4:4 + attr_len]
postfix = postfix[4 + attr_len:] # Next attribute
else: # standard 1-octet length
if isinstance(postfix[2], int):
attr_len = postfix[2]
else:
attr_len = ord(postfix[2])
attr_value = postfix[3:3 + attr_len]
postfix = postfix[3 + attr_len:] # Next attribute
except Exception as e:
LOG.error(e)
error_str = traceback.format_exc()
LOG.debug(error_str)
raise excep.UpdateMessageError(
sub_error=bgp_cons.ERR_MSG_UPDATE_MALFORMED_ATTR_LIST,
data='')
if type_code == bgp_cons.BGPTYPE_ORIGIN:
decode_value = Origin.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_AS_PATH:
decode_value = ASPath.parse(value=attr_value, asn4=asn4)
elif type_code == bgp_cons.BGPTYPE_NEXT_HOP:
decode_value = NextHop.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_MULTI_EXIT_DISC:
decode_value = MED.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_LOCAL_PREF:
decode_value = LocalPreference.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_ATOMIC_AGGREGATE:
decode_value = AtomicAggregate.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_AGGREGATOR:
decode_value = Aggregator.parse(value=attr_value, asn4=asn4)
elif type_code == bgp_cons.BGPTYPE_COMMUNITIES:
decode_value = Community.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_ORIGINATOR_ID:
decode_value = OriginatorID.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_CLUSTER_LIST:
decode_value = ClusterList.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_NEW_AS_PATH:
decode_value = ASPath.parse(value=attr_value, asn4=True)
elif type_code == bgp_cons.BGPTYPE_NEW_AGGREGATOR:
decode_value = Aggregator.parse(value=attr_value, asn4=True)
elif type_code == bgp_cons.BGPTYPE_LARGE_COMMUNITY:
decode_value = LargeCommunity.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_MP_REACH_NLRI:
decode_value = MpReachNLRI.parse(value=attr_value)
if decode_value['nlri'][0] and type(
decode_value['nlri'][0]) is dict:
if decode_value['nlri'][0].get("protocol_id"):
bgpls_pro_id = decode_value['nlri'][0]["protocol_id"]
elif type_code == bgp_cons.BGPTYPE_MP_UNREACH_NLRI:
decode_value = MpUnReachNLRI.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_EXTENDED_COMMUNITY:
decode_value = ExtCommunity.parse(value=attr_value)
elif type_code == bgp_cons.BGPTYPE_PMSI_TUNNEL:
decode_value = PMSITunnel.parse(value=attr_value)
pmsi_hex = attr_value
elif type_code == bgp_cons.BGPTYPE_LINK_STATE:
if bgpls_pro_id:
attributes.update(
LinkState.unpack(bgpls_pro_id=bgpls_pro_id,
data=attr_value).dict())
else:
bgpls_attr = attr_value
continue
else:
decode_value = binascii.b2a_hex(attr_value)
attributes[type_code] = decode_value
if bgpls_attr:
attributes.update(
LinkState.unpack(bgpls_pro_id=bgpls_pro_id,
data=attr_value).dict())
evpn_overlay = EVPN.signal_evpn_overlay(attributes)
if evpn_overlay['evpn'] and evpn_overlay['encap_ec']:
if bgp_cons.BGPTYPE_PMSI_TUNNEL in attributes:
attributes[bgp_cons.BGPTYPE_PMSI_TUNNEL] = PMSITunnel.parse(
value=pmsi_hex, evpn_overlay=evpn_overlay)
return attributes