class Path(object):
"""Represents a way of reaching an IP destination.
Also contains other meta-data given to us by a specific source (such as a
peer).
"""
__metaclass__ = ABCMeta
__slots__ = ('_source', '_path_attr_map', '_nlri', '_source_version_num',
'_exported_from', '_nexthop', 'next_path', 'prev_path',
'_is_withdraw', 'med_set_by_target_neighbor')
ROUTE_FAMILY = RF_IPv4_UC
def __init__(self, source, nlri, src_ver_num, pattrs=None, nexthop=None,
is_withdraw=False, med_set_by_target_neighbor=False):
"""Initializes Ipv4 path.
If this path is not a withdraw, then path attribute and nexthop both
should be provided.
Parameters:
- `source`: (Peer/str) source of this path.
- `nlri`: (Vpnv4) Nlri instance for Vpnv4 route family.
- `src_ver_num`: (int) version number of *source* when this path
was learned.
- `pattrs`: (OrderedDict) various path attributes for this path.
- `nexthop`: (str) nexthop advertised for this path.
- `is_withdraw`: (bool) True if this represents a withdrawal.
"""
self.med_set_by_target_neighbor = med_set_by_target_neighbor
if nlri.ROUTE_FAMILY != self.__class__.ROUTE_FAMILY:
raise ValueError('NLRI and Path route families do not'
' match (%s, %s).' %
(nlri.ROUTE_FAMILY, self.__class__.ROUTE_FAMILY))
# Currently paths injected directly into VRF has only one source
# src_peer can be None to denote NC else has to be instance of Peer.
# Paths can be exported from one VRF and then imported into another
# VRF, in such cases it source is denoted as string VPN_TABLE.
if not (source is None or
hasattr(source, 'version_num') or
source in (VRF_TABLE, VPN_TABLE)):
raise ValueError('Invalid or Unsupported source for path: %s' %
source)
# If this path is not a withdraw path, than it should have path-
# attributes and nexthop.
if not is_withdraw and not (pattrs and nexthop):
raise ValueError('Need to provide nexthop and patattrs '
'for path that is not a withdraw.')
# The entity (peer) that gave us this path.
self._source = source
# Path attribute of this path.
if pattrs:
self._path_attr_map = copy(pattrs)
else:
self._path_attr_map = OrderedDict()
# NLRI that this path represents.
self._nlri = nlri
# If given nlri is withdrawn.
self._is_withdraw = is_withdraw
# @see Source.version_num
self._source_version_num = src_ver_num
self._nexthop = nexthop
# Automatically generated.
#
# self.next_path
# self.prev_path
# The Destination from which this path was exported, if any.
self._exported_from = None
@property
def source_version_num(self):
return self._source_version_num
@property
def source(self):
return self._source
@property
def route_family(self):
return self.__class__.ROUTE_FAMILY
@property
def nlri(self):
return self._nlri
@property
def is_withdraw(self):
return self._is_withdraw
@property
def pathattr_map(self):
return copy(self._path_attr_map)
@property
def nexthop(self):
return self._nexthop
def get_pattr(self, pattr_type, default=None):
"""Returns path attribute of given type.
Returns None if we do not attribute of type *pattr_type*.
"""
return self._path_attr_map.get(pattr_type, default)
def clone(self, for_withdrawal=False):
pathattrs = None
if not for_withdrawal:
pathattrs = self.pathattr_map
clone = self.__class__(
self.source,
self.nlri,
self.source_version_num,
pattrs=pathattrs,
nexthop=self.nexthop,
is_withdraw=for_withdrawal
)
return clone
def get_rts(self):
extcomm_attr = self._path_attr_map.get(
BGP_ATTR_TYPE_EXTENDED_COMMUNITIES)
if extcomm_attr is None:
rts = []
else:
rts = extcomm_attr.rt_list
return rts
def has_rts_in(self, interested_rts):
"""Returns True if this `Path` has any `ExtCommunity` attribute
route target common with `interested_rts`.
"""
assert isinstance(interested_rts, set)
curr_rts = self.get_rts()
# Add default RT to path RTs so that we match interest for peers who
# advertised default RT
curr_rts.append(RouteTargetMembershipNLRI.DEFAULT_RT)
return not interested_rts.isdisjoint(curr_rts)
def __str__(self):
return (
'Path(source: %s, nlri: %s, source ver#: %s, '
'path attrs.: %s, nexthop: %s, is_withdraw: %s)' %
(
self._source, self._nlri, self._source_version_num,
self._path_attr_map, self._nexthop, self._is_withdraw
)
)
def __repr__(self):
return ('Path(%s, %s, %s, %s, %s, %s)' % (
self._source, self._nlri, self._source_version_num,
self._path_attr_map, self._nexthop, self._is_withdraw))
