def bgp_announce(self, asn4, local_asn, peer_asn):
ibgp = (local_asn == peer_asn)
# we do not store or send MED
message = ''
if AttributeID.ORIGIN in self:
message += self[AttributeID.ORIGIN].pack()
elif self.autocomplete:
message += Origin(Origin.IGP).pack()
if AttributeID.AS_PATH in self:
asp = self[AttributeID.AS_PATH]
message += self._as_path(asn4, asp)
elif self.autocomplete:
if ibgp:
asp = ASPath(asn4, ASPath.AS_SEQUENCE, [])
else:
asp = ASPath(asn4, ASPath.AS_SEQUENCE, [local_asn])
message += self._as_path(asn4, asp)
else:
raise RuntimeError('Generated routes must always have an AS_PATH ')
if AttributeID.NEXT_HOP in self:
afi = self[AttributeID.NEXT_HOP].next_hop.afi
safi = self[AttributeID.NEXT_HOP].next_hop.safi
if afi == AFI.ipv4 and safi in [SAFI.unicast, SAFI.multicast]:
message += self[AttributeID.NEXT_HOP].pack()
if ibgp:
if AttributeID.LOCAL_PREF in self:
message += self[AttributeID.LOCAL_PREF].pack()
else:
message += LocalPreference(100).pack()
if AttributeID.MED in self:
if local_asn != peer_asn:
message += self[AttributeID.MED].pack()
if AttributeID.PMSI_TUNNEL in self:
message += self[AttributeID.PMSI_TUNNEL].pack()
for attribute in [
AttributeID.COMMUNITY, AttributeID.EXTENDED_COMMUNITY
]:
if attribute in self:
message += self[attribute].pack()
return message
def __new_ASPath(self, data, asn4=False):
if len(data) == 0:
return ASPath(asn4)
if asn4:
size = 4
decoder = 'L' # could it be 'I' as well ?
else:
size = 2
decoder = 'H'
stype = ord(data[0])
slen = ord(data[1])
sdata = data[2:2 + (slen * size)]
ASPS = ASPath(asn4, stype)
format = '!' + (decoder * slen)
for c in unpack(format, sdata):
ASPS.add(c)
return ASPS
def __new_ASPath (self,data,asn4=False): if len(data) == 0: return ASPath(asn4) if asn4: size = 4 decoder = 'L' # could it be 'I' as well ? else: size = 2 decoder = 'H' stype = ord(data[0]) slen = ord(data[1]) sdata = data[2:2+(slen*size)] ASPS = ASPath(asn4,stype) format = '!'+(decoder*slen) for c in unpack(format,sdata): ASPS.add(c) return ASPS
def _route_aspath (self,scope,tokens): aspath = ASPath() asn = tokens.pop(0) try: if asn == '[': while True: try: asn = tokens.pop(0) except IndexError: self._error = self._str_route_error if self.debug: raise return False if asn == ']': break aspath.add(self._newASN(asn)) else: aspath.add(self._newASN(asn)) except ValueError: self._error = self._str_route_error if self.debug: raise return False scope[-1]['routes'][-1].attributes.add(aspath) return True
def __merge_attributes(self):
as2path = self.attributes[AttributeID.AS_PATH]
as4path = self.attributes[AttributeID.AS4_PATH]
newASPS = ASPath(True, as2path.asptype)
len2 = len(as2path.aspsegment)
len4 = len(as4path.aspsegment)
if len2 < len4:
for asn in as4path.aspsegment:
newASPS.add(asn)
else:
for asn in as2path.aspsegment[:-len4]:
newASPS.add(asn)
for asn in as4path.aspsegment:
newASPS.add(asn)
self.attributes.remove(AttributeID.AS_PATH)
self.attributes.remove(AttributeID.AS4_PATH)
self.attributes.add(newASPS)
def _as_path(self, asn4, asp):
message = ''
# if the peer does not understand ASN4, we need to build a transitive AS4_PATH
if not asn4:
has_asn4 = False
aspath = ASPath(False, asp.asptype)
as4path = AS4Path(asp.asptype)
for segment in asp.aspsegment:
if segment.asn4():
has_asn4 = True
aspath.add(AS_TRANS)
as4path.add(segment)
else:
aspath.add(segment)
as4path.add(segment)
message += aspath.pack()
if has_asn4:
message += as4path.pack()
else:
message += ASPath(True, asp.asptype, asp.aspsegment).pack()
return message
def __merge_attributes (self): as2path = self.attributes[AttributeID.AS_PATH] as4path = self.attributes[AttributeID.AS4_PATH] newASPS = ASPath(True,as2path.asptype) len2 = len(as2path.aspsegment) len4 = len(as4path.aspsegment) if len2 < len4: for asn in as4path.aspsegment: newASPS.add(asn) else: for asn in as2path.aspsegment[:-len4]: newASPS.add(asn) for asn in as4path.aspsegment: newASPS.add(asn) self.attributes.remove(AttributeID.AS_PATH) self.attributes.remove(AttributeID.AS4_PATH) self.attributes.add(newASPS)
