# $Id: bgp.py 76 2011-01-06 15:51:30Z dugsong $ """Border Gateway Protocol.""" import dpkt import struct, socket # Border Gateway Protocol 4 - RFC 4271 # Communities Attribute - RFC 1997 # Capabilities - RFC 3392 # Route Refresh - RFC 2918 # Route Reflection - RFC 4456 # Confederations - RFC 3065 # Cease Subcodes - RFC 4486 # NOPEER Community - RFC 3765 # Multiprotocol Extensions - 2858 # Message Types OPEN = 1 UPDATE = 2 NOTIFICATION = 3 KEEPALIVE = 4 ROUTE_REFRESH = 5 # Attribute Types ORIGIN = 1 AS_PATH = 2 NEXT_HOP = 3 MULTI_EXIT_DISC = 4 LOCAL_PREF = 5 ATOMIC_AGGREGATE = 6 AGGREGATOR = 7 COMMUNITIES = 8 ORIGINATOR_ID = 9 CLUSTER_LIST = 10 MP_REACH_NLRI = 14 MP_UNREACH_NLRI = 15 # Origin Types ORIGIN_IGP = 0 ORIGIN_EGP = 1 INCOMPLETE = 2 # AS Path Types AS_SET = 1 AS_SEQUENCE = 2 AS_CONFED_SEQUENCE = 3 AS_CONFED_SET = 4 # Reserved Communities Types NO_EXPORT = 0xffffff01L NO_ADVERTISE = 0xffffff02L NO_EXPORT_SUBCONFED = 0xffffff03L NO_PEER = 0xffffff04L # Common AFI types AFI_IPV4 = 1 AFI_IPV6 = 2 # Multiprotocol SAFI types SAFI_UNICAST = 1 SAFI_MULTICAST = 2 SAFI_UNICAST_MULTICAST = 3 # OPEN Message Optional Parameters AUTHENTICATION = 1 CAPABILITY = 2 # Capability Types CAP_MULTIPROTOCOL = 1 CAP_ROUTE_REFRESH = 2 # NOTIFICATION Error Codes MESSAGE_HEADER_ERROR = 1 OPEN_MESSAGE_ERROR = 2 UPDATE_MESSAGE_ERROR = 3 HOLD_TIMER_EXPIRED = 4 FSM_ERROR = 5 CEASE = 6 # Message Header Error Subcodes CONNECTION_NOT_SYNCHRONIZED = 1 BAD_MESSAGE_LENGTH = 2 BAD_MESSAGE_TYPE = 3 # OPEN Message Error Subcodes UNSUPPORTED_VERSION_NUMBER = 1 BAD_PEER_AS = 2 BAD_BGP_IDENTIFIER = 3 UNSUPPORTED_OPTIONAL_PARAMETER = 4 AUTHENTICATION_FAILURE = 5 UNACCEPTABLE_HOLD_TIME = 6 UNSUPPORTED_CAPABILITY = 7 # UPDATE Message Error Subcodes MALFORMED_ATTRIBUTE_LIST = 1 UNRECOGNIZED_ATTRIBUTE = 2 MISSING_ATTRIBUTE = 3 ATTRIBUTE_FLAGS_ERROR = 4 ATTRIBUTE_LENGTH_ERROR = 5 INVALID_ORIGIN_ATTRIBUTE = 6 AS_ROUTING_LOOP = 7 INVALID_NEXT_HOP_ATTRIBUTE = 8 OPTIONAL_ATTRIBUTE_ERROR = 9 INVALID_NETWORK_FIELD = 10 MALFORMED_AS_PATH = 11 # Cease Error Subcodes MAX_NUMBER_OF_PREFIXES_REACHED = 1 ADMINISTRATIVE_SHUTDOWN = 2 PEER_DECONFIGURED = 3 ADMINISTRATIVE_RESET = 4 CONNECTION_REJECTED = 5 OTHER_CONFIGURATION_CHANGE = 6 CONNECTION_COLLISION_RESOLUTION = 7 OUT_OF_RESOURCES = 8 class BGP(dpkt.Packet): __hdr__ = ( ('marker', '16s', '\xff' * 16), ('len', 'H', 0), ('type', 'B', OPEN) ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) self.data = self.data[:self.len - self.__hdr_len__] if self.type == OPEN: self.data = self.open = self.Open(self.data) elif self.type == UPDATE: self.data = self.update = self.Update(self.data) elif self.type == NOTIFICATION: self.data = self.notifiation = self.Notification(self.data) elif self.type == KEEPALIVE: self.data = self.keepalive = self.Keepalive(self.data) elif self.type == ROUTE_REFRESH: self.data = self.route_refresh = self.RouteRefresh(self.data) class Open(dpkt.Packet): __hdr__ = ( ('v', 'B', 4), ('asn', 'H', 0), ('holdtime', 'H', 0), ('identifier', 'I', 0), ('param_len', 'B', 0) ) __hdr_defaults__ = { 'parameters': [] } def unpack(self, buf): dpkt.Packet.unpack(self, buf) l = [] plen = self.param_len while plen > 0: param = self.Parameter(self.data) self.data = self.data[len(param):] plen -= len(param) l.append(param) self.data = self.parameters = l def __len__(self): return self.__hdr_len__ + \ sum(map(len, self.parameters)) def __str__(self): params = ''.join(map(str, self.parameters)) self.param_len = len(params) return self.pack_hdr() + params class Parameter(dpkt.Packet): __hdr__ = ( ('type', 'B', 0), ('len', 'B', 0) ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) self.data = self.data[:self.len] if self.type == AUTHENTICATION: self.data = self.authentication = self.Authentication(self.data) elif self.type == CAPABILITY: self.data = self.capability = self.Capability(self.data) class Authentication(dpkt.Packet): __hdr__ = ( ('code', 'B', 0), ) class Capability(dpkt.Packet): __hdr__ = ( ('code', 'B', 0), ('len', 'B', 0) ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) self.data = self.data[:self.len] class Update(dpkt.Packet): __hdr_defaults__ = { 'withdrawn': [], 'attributes': [], 'announced': [] } def unpack(self, buf): self.data = buf # Withdrawn Routes wlen = struct.unpack('>H', self.data[:2])[0] self.data = self.data[2:] l = [] while wlen > 0: route = RouteIPV4(self.data) self.data = self.data[len(route):] wlen -= len(route) l.append(route) self.withdrawn = l # Path Attributes plen = struct.unpack('>H', self.data[:2])[0] self.data = self.data[2:] l = [] while plen > 0: attr = self.Attribute(self.data) self.data = self.data[len(attr):] plen -= len(attr) l.append(attr) self.attributes = l # Announced Routes l = [] while self.data: route = RouteIPV4(self.data) self.data = self.data[len(route):] l.append(route) self.announced = l def __len__(self): return 2 + sum(map(len, self.withdrawn)) + \ 2 + sum(map(len, self.attributes)) + \ sum(map(len, self.announced)) def __str__(self): return struct.pack('>H', sum(map(len, self.withdrawn))) + \ ''.join(map(str, self.withdrawn)) + \ struct.pack('>H', sum(map(len, self.attributes))) + \ ''.join(map(str, self.attributes)) + \ ''.join(map(str, self.announced)) class Attribute(dpkt.Packet): __hdr__ = ( ('flags', 'B', 0), ('type', 'B', 0) ) def _get_o(self): return (self.flags >> 7) & 0x1 def _set_o(self, o): self.flags = (self.flags & ~0x80) | ((o & 0x1) << 7) optional = property(_get_o, _set_o) def _get_t(self): return (self.flags >> 6) & 0x1 def _set_t(self, t): self.flags = (self.flags & ~0x40) | ((t & 0x1) << 6) transitive = property(_get_t, _set_t) def _get_p(self): return (self.flags >> 5) & 0x1 def _set_p(self, p): self.flags = (self.flags & ~0x20) | ((p & 0x1) << 5) partial = property(_get_p, _set_p) def _get_e(self): return (self.flags >> 4) & 0x1 def _set_e(self, e): self.flags = (self.flags & ~0x10) | ((e & 0x1) << 4) extended_length = property(_get_e, _set_e) def unpack(self, buf): dpkt.Packet.unpack(self, buf) if self.extended_length: self.len = struct.unpack('>H', self.data[:2])[0] self.data = self.data[2:] else: self.len = struct.unpack('B', self.data[:1])[0] self.data = self.data[1:] self.data = self.data[:self.len] if self.type == ORIGIN: self.data = self.origin = self.Origin(self.data) elif self.type == AS_PATH: self.data = self.as_path = self.ASPath(self.data) elif self.type == NEXT_HOP: self.data = self.next_hop = self.NextHop(self.data) elif self.type == MULTI_EXIT_DISC: self.data = self.multi_exit_disc = self.MultiExitDisc(self.data) elif self.type == LOCAL_PREF: self.data = self.local_pref = self.LocalPref(self.data) elif self.type == ATOMIC_AGGREGATE: self.data = self.atomic_aggregate = self.AtomicAggregate(self.data) elif self.type == AGGREGATOR: self.data = self.aggregator = self.Aggregator(self.data) elif self.type == COMMUNITIES: self.data = self.communities = self.Communities(self.data) elif self.type == ORIGINATOR_ID: self.data = self.originator_id = self.OriginatorID(self.data) elif self.type == CLUSTER_LIST: self.data = self.cluster_list = self.ClusterList(self.data) elif self.type == MP_REACH_NLRI: self.data = self.mp_reach_nlri = self.MPReachNLRI(self.data) elif self.type == MP_UNREACH_NLRI: self.data = self.mp_unreach_nlri = self.MPUnreachNLRI(self.data) def __len__(self): if self.extended_length: attr_len = 2 else: attr_len = 1 return self.__hdr_len__ + \ attr_len + \ len(self.data) def __str__(self): if self.extended_length: attr_len_str = struct.pack('>H', self.len) else: attr_len_str = struct.pack('B', self.len) return self.pack_hdr() + \ attr_len_str + \ str(self.data) class Origin(dpkt.Packet): __hdr__ = ( ('type', 'B', ORIGIN_IGP), ) class ASPath(dpkt.Packet): __hdr_defaults__ = { 'segments': [] } def unpack(self, buf): self.data = buf l = [] while self.data: seg = self.ASPathSegment(self.data) self.data = self.data[len(seg):] l.append(seg) self.data = self.segments = l def __len__(self): return sum(map(len, self.data)) def __str__(self): return ''.join(map(str, self.data)) class ASPathSegment(dpkt.Packet): __hdr__ = ( ('type', 'B', 0), ('len', 'B', 0) ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) l = [] for i in range(self.len): AS = struct.unpack('>H', self.data[:2])[0] self.data = self.data[2:] l.append(AS) self.data = self.path = l def __len__(self): return self.__hdr_len__ + \ 2 * len(self.path) def __str__(self): as_str = '' for AS in self.path: as_str += struct.pack('>H', AS) return self.pack_hdr() + \ as_str class NextHop(dpkt.Packet): __hdr__ = ( ('ip', 'I', 0), ) class MultiExitDisc(dpkt.Packet): __hdr__ = ( ('value', 'I', 0), ) class LocalPref(dpkt.Packet): __hdr__ = ( ('value', 'I', 0), ) class AtomicAggregate(dpkt.Packet): def unpack(self, buf): pass def __len__(self): return 0 def __str__(self): return '' class Aggregator(dpkt.Packet): __hdr__ = ( ('asn', 'H', 0), ('ip', 'I', 0) ) class Communities(dpkt.Packet): __hdr_defaults__ = { 'list': [] } def unpack(self, buf): self.data = buf l = [] while self.data: val = struct.unpack('>I', self.data[:4])[0] if (val >= 0x00000000L and val <= 0x0000ffffL) or \ (val >= 0xffff0000L and val <= 0xffffffffL): comm = self.ReservedCommunity(self.data[:4]) else: comm = self.Community(self.data[:4]) self.data = self.data[len(comm):] l.append(comm) self.data = self.list = l def __len__(self): return sum(map(len, self.data)) def __str__(self): return ''.join(map(str, self.data)) class Community(dpkt.Packet): __hdr__ = ( ('asn', 'H', 0), ('value', 'H', 0) ) class ReservedCommunity(dpkt.Packet): __hdr__ = ( ('value', 'I', 0), ) class OriginatorID(dpkt.Packet): __hdr__ = ( ('value', 'I', 0), ) class ClusterList(dpkt.Packet): __hdr_defaults__ = { 'list': [] } def unpack(self, buf): self.data = buf l = [] while self.data: id = struct.unpack('>I', self.data[:4])[0] self.data = self.data[4:] l.append(id) self.data = self.list = l def __len__(self): return 4 * len(self.list) def __str__(self): cluster_str = '' for val in self.list: cluster_str += struct.pack('>I', val) return cluster_str class MPReachNLRI(dpkt.Packet): __hdr__ = ( ('afi', 'H', AFI_IPV4), ('safi', 'B', SAFI_UNICAST), ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) # Next Hop nlen = struct.unpack('B', self.data[:1])[0] self.data = self.data[1:] self.next_hop = self.data[:nlen] self.data = self.data[nlen:] # SNPAs l = [] num_snpas = struct.unpack('B', self.data[:1])[0] self.data = self.data[1:] for i in range(num_snpas): snpa = self.SNPA(self.data) self.data = self.data[len(snpa):] l.append(snpa) self.snpas = l if self.afi == AFI_IPV4: Route = RouteIPV4 elif self.afi == AFI_IPV6: Route = RouteIPV6 else: Route = RouteGeneric # Announced Routes l = [] while self.data: route = Route(self.data) self.data = self.data[len(route):] l.append(route) self.data = self.announced = l def __len__(self): return self.__hdr_len__ + \ 1 + len(self.next_hop) + \ 1 + sum(map(len, self.snpas)) + \ sum(map(len, self.announced)) def __str__(self): return self.pack_hdr() + \ struct.pack('B', len(self.next_hop)) + \ str(self.next_hop) + \ struct.pack('B', len(self.snpas)) + \ ''.join(map(str, self.snpas)) + \ ''.join(map(str, self.announced)) class SNPA: __hdr__ = ( ('len', 'B', 0), ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) self.data = self.data[:(self.len + 1) / 2] class MPUnreachNLRI(dpkt.Packet): __hdr__ = ( ('afi', 'H', AFI_IPV4), ('safi', 'B', SAFI_UNICAST), ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) if self.afi == AFI_IPV4: Route = RouteIPV4 elif self.afi == AFI_IPV6: Route = RouteIPV6 else: Route = RouteGeneric # Withdrawn Routes l = [] while self.data: route = Route(self.data) self.data = self.data[len(route):] l.append(route) self.data = self.withdrawn = l def __len__(self): return self.__hdr_len__ + \ sum(map(len, self.data)) def __str__(self): return self.pack_hdr() + \ ''.join(map(str, self.data)) class Notification(dpkt.Packet): __hdr__ = ( ('code', 'B', 0), ('subcode', 'B', 0), ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) self.error = self.data class Keepalive(dpkt.Packet): def unpack(self, buf): pass def __len__(self): return 0 def __str__(self): return '' class RouteRefresh(dpkt.Packet): __hdr__ = ( ('afi', 'H', AFI_IPV4), ('rsvd', 'B', 0), ('safi', 'B', SAFI_UNICAST) ) class RouteGeneric(dpkt.Packet): __hdr__ = ( ('len', 'B', 0), ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) self.data = self.prefix = self.data[:(self.len + 7) / 8] class RouteIPV4(dpkt.Packet): __hdr__ = ( ('len', 'B', 0), ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) tmp = self.data[:(self.len + 7) / 8] tmp += (4 - len(tmp)) * '\x00' self.data = self.prefix = tmp def __repr__(self): cidr = '%s/%d' % (socket.inet_ntoa(self.prefix), self.len) return '%s(%s)' % (self.__class__.__name__, cidr) def __len__(self): return self.__hdr_len__ + \ (self.len + 7) / 8 def __str__(self): return self.pack_hdr() + \ self.prefix[:(self.len + 7) / 8] class RouteIPV6(dpkt.Packet): __hdr__ = ( ('len', 'B', 0), ) def unpack(self, buf): dpkt.Packet.unpack(self, buf) tmp = self.data[:(self.len + 7) / 8] tmp += (16 - len(tmp)) * '\x00' self.data = self.prefix = tmp def __len__(self): return self.__hdr_len__ + \ (self.len + 7) / 8 def __str__(self): return self.pack_hdr() + \ self.prefix[:(self.len + 7) / 8] if __name__ == '__main__': import unittest class BGPTestCase(unittest.TestCase): def testPack(self): b1 = BGP(self.bgp1) self.failUnless(self.bgp1 == str(b1)) b2 = BGP(self.bgp2) self.failUnless(self.bgp2 == str(b2)) b3 = BGP(self.bgp3) self.failUnless(self.bgp3 == str(b3)) b4 = BGP(self.bgp4) self.failUnless(self.bgp4 == str(b4)) def testUnpack(self): b1 = BGP(self.bgp1) self.failUnless(b1.len == 19) self.failUnless(b1.type == KEEPALIVE) self.failUnless(b1.keepalive is not None) b2 = BGP(self.bgp2) self.failUnless(b2.type == UPDATE) self.failUnless(len(b2.update.withdrawn) == 0) self.failUnless(len(b2.update.announced) == 1) self.failUnless(len(b2.update.attributes) == 9) a = b2.update.attributes[1] self.failUnless(a.type == AS_PATH) self.failUnless(a.len == 10) self.failUnless(len(a.as_path.segments) == 2) s = a.as_path.segments[0] self.failUnless(s.type == AS_SET) self.failUnless(s.len == 2) self.failUnless(len(s.path) == 2) self.failUnless(s.path[0] == 500) a = b2.update.attributes[6] self.failUnless(a.type == COMMUNITIES) self.failUnless(a.len == 12) self.failUnless(len(a.communities.list) == 3) c = a.communities.list[0] self.failUnless(c.asn == 65215) self.failUnless(c.value == 1) r = b2.update.announced[0] self.failUnless(r.len == 22) self.failUnless(r.prefix == '\xc0\xa8\x04\x00') b3 = BGP(self.bgp3) self.failUnless(b3.type == UPDATE) self.failUnless(len(b3.update.withdrawn) == 0) self.failUnless(len(b3.update.announced) == 0) self.failUnless(len(b3.update.attributes) == 6) a = b3.update.attributes[0] self.failUnless(a.optional == False) self.failUnless(a.transitive == True) self.failUnless(a.partial == False) self.failUnless(a.extended_length == False) self.failUnless(a.type == ORIGIN) self.failUnless(a.len == 1) o = a.origin self.failUnless(o.type == ORIGIN_IGP) a = b3.update.attributes[5] self.failUnless(a.optional == True) self.failUnless(a.transitive == False) self.failUnless(a.partial == False) self.failUnless(a.extended_length == True) self.failUnless(a.type == MP_REACH_NLRI) self.failUnless(a.len == 30) m = a.mp_reach_nlri self.failUnless(m.afi == AFI_IPV4) self.failUnless(len(m.snpas) == 0) self.failUnless(len(m.announced) == 1) p = m.announced[0] self.failUnless(p.len == 96) b4 = BGP(self.bgp4) self.failUnless(b4.len == 45) self.failUnless(b4.type == OPEN) self.failUnless(b4.open.asn == 237) self.failUnless(b4.open.param_len == 16) self.failUnless(len(b4.open.parameters) == 3) p = b4.open.parameters[0] self.failUnless(p.type == CAPABILITY) self.failUnless(p.len == 6) c = p.capability self.failUnless(c.code == CAP_MULTIPROTOCOL) self.failUnless(c.len == 4) self.failUnless(c.data == '\x00\x01\x00\x01') c = b4.open.parameters[2].capability self.failUnless(c.code == CAP_ROUTE_REFRESH) self.failUnless(c.len == 0) bgp1 = '\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00\x13\x04' bgp2 = '\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00\x63\x02\x00\x00\x00\x48\x40\x01\x01\x00\x40\x02\x0a\x01\x02\x01\xf4\x01\xf4\x02\x01\xfe\xbb\x40\x03\x04\xc0\xa8\x00\x0f\x40\x05\x04\x00\x00\x00\x64\x40\x06\x00\xc0\x07\x06\xfe\xba\xc0\xa8\x00\x0a\xc0\x08\x0c\xfe\xbf\x00\x01\x03\x16\x00\x04\x01\x54\x00\xfa\x80\x09\x04\xc0\xa8\x00\x0f\x80\x0a\x04\xc0\xa8\x00\xfa\x16\xc0\xa8\x04' bgp3 = '\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00\x79\x02\x00\x00\x00\x62\x40\x01\x01\x00\x40\x02\x00\x40\x05\x04\x00\x00\x00\x64\xc0\x10\x08\x00\x02\x01\x2c\x00\x00\x01\x2c\xc0\x80\x24\x00\x00\xfd\xe9\x40\x01\x01\x00\x40\x02\x04\x02\x01\x15\xb3\x40\x05\x04\x00\x00\x00\x2c\x80\x09\x04\x16\x05\x05\x05\x80\x0a\x04\x16\x05\x05\x05\x90\x0e\x00\x1e\x00\x01\x80\x0c\x00\x00\x00\x00\x00\x00\x00\x00\x0c\x04\x04\x04\x00\x60\x18\x77\x01\x00\x00\x01\xf4\x00\x00\x01\xf4\x85' bgp4 = '\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00\x2d\x01\x04\x00\xed\x00\x5a\xc6\x6e\x83\x7d\x10\x02\x06\x01\x04\x00\x01\x00\x01\x02\x02\x80\x00\x02\x02\x02\x00' unittest.main()