Merge pull request #490 from amgadhanafy/#fix-481

Introduce 4 octet ASPathSegment, Extended NLRI Routes

dpkt/bgp.py

@@ -20,6 +20,8 @@
 # Cease Subcodes - RFC 4486
 # NOPEER Community - RFC 3765
 # Multiprotocol Extensions - 2858
+# Advertisement of Multiple Paths in BGP - RFC 7911
+# BGP Support for Four-Octet Autonomous System (AS) Number Spac - RFC 6793
 
 # Message Types
 OPEN = 1
@@ -252,7 +254,10 @@ def unpack(self, buf):
             # Announced Routes
             l = []
             while self.data:
-                route = RouteIPV4(self.data)
+                if len(self.data) % 9 == 0:
+                    route = ExtendedRouteIPV4(self.data)
+                else:
+                    route = RouteIPV4(self.data)
                 self.data = self.data[len(route):]
                 l.append(route)
             self.announced = l
@@ -371,8 +376,12 @@ class ASPath(dpkt.Packet):
                 def unpack(self, buf):
                     self.data = buf
                     l = []
+                    as4 = len(self.data) == 6
                     while self.data:
-                        seg = self.ASPathSegment(self.data)
+                        if as4:
+                            seg = self.ASPathSegment4(self.data)
+                        else:
+                            seg = self.ASPathSegment(self.data)
                         self.data = self.data[len(seg):]
                         l.append(seg)
                     self.data = self.segments = l
@@ -407,6 +416,31 @@ def __bytes__(self):
                             as_str += struct.pack('>H', AS)
                         return self.pack_hdr() + as_str
 
+                class ASPathSegment4(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):
+                            if len(self.data) >= 4:
+                                AS = struct.unpack('>I', self.data[:4])[0]
+                                self.data = self.data[4:]
+                                l.append(AS)
+                        self.path = l
+
+                    def __len__(self):
+                        return self.__hdr_len__ + 4 * len(self.path)
+
+                    def __bytes__(self):
+                        as_str = b''
+                        for AS in self.path:
+                            as_str += struct.pack('>I', AS)
+                        return self.pack_hdr() + as_str
+
             class NextHop(dpkt.Packet):
                 __hdr__ = (
                     ('ip', 'I', 0),
@@ -667,6 +701,16 @@ def __len__(self):
     def __bytes__(self):
         return self.pack_hdr() + self.prefix[:(self.len + 7) // 8]
 
+class ExtendedRouteIPV4(RouteIPV4):
+    __hdr__ = (
+        ('path_id', 'I', 0),
+        ('len', 'B', 0),
+    )
+
+    def __repr__(self):
+        cidr = '%s/%d PathId %d' % (socket.inet_ntoa(self.prefix), self.len, self.path_id)
+        return '%s(%s)' % (self.__class__.__name__, cidr)
+
 
 class RouteIPV6(dpkt.Packet):
     __hdr__ = (
@@ -1018,9 +1062,106 @@ def test_bgp_mp_nlri_20_1_mp_reach_nlri_next_hop():
     assert (socket.inet_ntop(socket.AF_INET6, mp_reach_nlri.next_hops[1]) == 'fe80::c001:bff:fe7e:0')
     assert (mp_reach_nlri.next_hop == b''.join(mp_reach_nlri.next_hops))
 
+def test_bgp_add_path_6_1_as_path():
+    # test for https://github.com/kbandla/dpkt/issues/481
+    # Error processing BGP data: packet 6 : message 1 of bgp-add-path.cap https://packetlife.net/media/captures/bgp-add-path.cap
+    __bgp = b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x00\x59\x02\x00\x00\x00\x30\x40\x01\x01\x00\x40\x02\x06\x02\x01\x00\x00\xfb\xff\x40\x03\x04\x0a\x00\x0e\x01\x80\x04\x04\x00\x00\x00\x00\x40\x05\x04\x00\x00\x00\x64\x80\x0a\x04\x0a\x00\x22\x04\x80\x09\x04\x0a\x00\x0f\x01\x00\x00\x00\x01\x20\x05\x05\x05\x05\x00\x00\x00\x01\x20\xc0\xa8\x01\x05'
+    bgp = BGP(__bgp)
+    assert (__bgp == bytes(bgp))
+    assert (len(bgp) == 89)
+    assert (bgp.type == UPDATE)
+    assert (len(bgp.update.withdrawn) == 0)
+    announced = bgp.update.announced
+    assert (len(announced) == 2)
+    assert (announced[0].len == 32)
+    assert (announced[0].path_id == 1)
+    assert (socket.inet_ntop(socket.AF_INET, bytes(announced[0].prefix)) == '5.5.5.5')
+    assert (announced[1].len == 32)
+    assert (announced[1].path_id == 1)
+    assert (socket.inet_ntop(socket.AF_INET, bytes(announced[1].prefix)) == '192.168.1.5')
+
+    assert (len(bgp.update.attributes) == 7)
+
+    attribute = bgp.update.attributes[0]
+    assert (attribute.type == ORIGIN)
+    assert (attribute.optional == False)
+    assert (attribute.transitive == True)
+    assert (attribute.partial == False)
+    assert (attribute.extended_length == False)
+    assert (attribute.flags == 0x40)
+    assert (attribute.len == 1)
+    assert (attribute.origin.type == ORIGIN_IGP)
+
+    attribute = bgp.update.attributes[1]
+    assert (attribute.type == AS_PATH)
+    assert (attribute.optional == False)
+    assert (attribute.transitive == True)
+    assert (attribute.partial == False)
+    assert (attribute.extended_length == False)
+    assert (attribute.flags == 0x40)
+    assert (attribute.len == 6)
+    assert (len(attribute.as_path.segments) == 1)
+    segment = attribute.as_path.segments[0]
+    assert (segment.type == AS_SEQUENCE)
+    assert (segment.len == 1)
+    assert (len(segment.path) == 1)
+    assert (segment.path[0] == 64511)
+
+    attribute = bgp.update.attributes[2]
+    assert (attribute.type == NEXT_HOP)
+    assert (attribute.optional == False)
+    assert (attribute.transitive == True)
+    assert (attribute.partial == False)
+    assert (attribute.extended_length == False)
+    assert (attribute.flags == 0x40)
+    assert (attribute.len == 4)
+    assert (socket.inet_ntop(socket.AF_INET, bytes(attribute.next_hop)) == '10.0.14.1')
+
+    attribute = bgp.update.attributes[3]
+    assert (attribute.type == MULTI_EXIT_DISC)
+    assert (attribute.optional == True)
+    assert (attribute.transitive == False)
+    assert (attribute.partial == False)
+    assert (attribute.extended_length == False)
+    assert (attribute.flags == 0x80)
+    assert (attribute.len == 4)
+    assert (attribute.multi_exit_disc.value == 0)
+
+    attribute = bgp.update.attributes[4]
+    assert (attribute.type == LOCAL_PREF)
+    assert (attribute.optional == False)
+    assert (attribute.transitive == True)
+    assert (attribute.partial == False)
+    assert (attribute.extended_length == False)
+    assert (attribute.flags == 0x40)
+    assert (attribute.len == 4)
+    assert (attribute.local_pref.value == 100)
+
+    attribute = bgp.update.attributes[5]
+    assert (attribute.type == CLUSTER_LIST)
+    assert (attribute.optional == True)
+    assert (attribute.transitive == False)
+    assert (attribute.partial == False)
+    assert (attribute.extended_length == False)
+    assert (attribute.flags == 0x80)
+    assert (attribute.len == 4)
+    assert (socket.inet_ntop(socket.AF_INET, bytes(attribute.cluster_list)) == '10.0.34.4')
+
+    attribute = bgp.update.attributes[6]
+    assert (attribute.type == ORIGINATOR_ID)
+    assert (attribute.optional == True)
+    assert (attribute.transitive == False)
+    assert (attribute.partial == False)
+    assert (attribute.extended_length == False)
+    assert (attribute.flags == 0x80)
+    assert (attribute.len == 4)
+    assert (socket.inet_ntop(socket.AF_INET, bytes(attribute.originator_id)) == '10.0.15.1')
+
+
 if __name__ == '__main__':
     test_pack()
     test_unpack()
     test_bgp_mp_nlri_20_1_mp_reach_nlri_next_hop()
+    test_bgp_add_path_6_1_as_path()
     print('Tests Successful...')