Add Parse for LinkState TLV Types 263

yabgp/message/attribute/linkstate/__init__.py

@@ -15,6 +15,7 @@
 
 from .linkstate import LinkState  # noqa
 from .node.local_router_id import LocalRouterID  # noqa
+from .node.mt_id import MultiTopologyIdentifier  # noqa
 from .node.name import NodeName  # noqa
 from .node.flex_algo_define import FlexAlgorithmDefine  # noqa
 from .node.isisarea import ISISArea  # noqa

yabgp/message/attribute/linkstate/node/mt_id.py

@@ -0,0 +1,51 @@
+# Copyright 2025 Cisco Systems, Inc.
+# All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import struct
+from yabgp.tlv import TLV
+from ..linkstate import LinkState
+
+
+@LinkState.register()
+class MultiTopologyIdentifier(TLV):
+    """MultiTopologyIdentifier TLV (Type 263)
+
+    RFC 7752 Section 3.2.1.5:
+    https://datatracker.ietf.org/doc/html/rfc7752#section-3.2.1.5
+
+    Format:
+      0                   1                   2                   3
+      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+     |              Type             |          Length=2*n           |
+     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+     |R R R R|  Multi-Topology ID 1  |             ....             //
+     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+     //             ....             |R R R R|  Multi-Topology ID n  |
+     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+    The MT-ID field is a 12-bit field (with 4 reserved bits).
+    Multiple MT-IDs can be present in the TLV (each 2 bytes).
+    """
+    TYPE = 263
+    TYPE_STR = 'mt_id'
+
+    @classmethod
+    def unpack(cls, data):
+        mt_id = []
+        while data:
+            mt_id.append(struct.unpack('!H', data[:2])[0])
+            data = data[2:]
+        return cls(value=mt_id)

yabgp/message/attribute/nlri/linkstate.py

@@ -21,6 +21,7 @@
 
 import netaddr
 
+from yabgp.message.attribute.linkstate.node.mt_id import MultiTopologyIdentifier
 from yabgp.message.attribute.nlri import NLRI
 
 
@@ -144,12 +145,8 @@ def parse_nlri(cls, data, nlri_type):
                 ipv6_neighbor_addr = str(netaddr.IPAddress(int(binascii.b2a_hex(value), 16)))
                 descriptor['type'] = 'link_remote_ipv6'
                 descriptor['value'] = ipv6_neighbor_addr
-            elif _type == 263:  # Multi-Topology Identifier
-                descriptor['type'] = 'mt_id'
-                descriptor['value'] = []
-                while value:
-                    descriptor['value'].append(struct.unpack('!H', value[:2])[0])
-                    value = value[2:]
+            elif _type == MultiTopologyIdentifier.TYPE:  # Multi-Topology Identifier
+                descriptor = MultiTopologyIdentifier.unpack(value).dict()
             elif _type == 264:  # OSPF Route Type
                 descriptor['type'] = 'prefix_ospf_route_type'
                 descriptor['value'] = ord(value[0:1])

yabgp/tests/unit/message/attribute/linkstate/node/test_mt_id.py

@@ -0,0 +1,167 @@
+# Copyright 2025 Cisco Systems, Inc.
+# All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+""" Test Multi-Topology Identifier TLV """
+
+import unittest
+
+from yabgp.message.attribute.linkstate.node.mt_id import MultiTopologyIdentifier
+
+
+class TestMultiTopologyIdentifier(unittest.TestCase):
+    """Test MultiTopologyIdentifier TLV (Type 263)
+    """
+
+    def test_unpack_single_mt_id(self):
+        """Test unpack with single MT-ID
+
+        Data: 00 02
+            - Reserved: 0x0
+            - MT-ID: 0x002 = 2 (IPv6 unicast)
+        """
+        data_bin = bytes.fromhex('0002')
+
+        expected = {
+            'type': 'mt_id',
+            'value': [2]
+        }
+
+        self.assertEqual(expected, MultiTopologyIdentifier.unpack(data_bin).dict())
+
+    def test_unpack_multiple_mt_ids(self):
+        """Test unpack with multiple MT-IDs
+
+        Data: 00 00 00 02 00 03
+            - MT-ID 1: 0x0000 = 0 (default topology)
+            - MT-ID 2: 0x0002 = 2 (IPv6 unicast)
+            - MT-ID 3: 0x0003 = 3 (IPv4 multicast)
+        """
+        data_bin = bytes.fromhex('000000020003')
+
+        expected = {
+            'type': 'mt_id',
+            'value': [0, 2, 3]
+        }
+
+        self.assertEqual(expected, MultiTopologyIdentifier.unpack(data_bin).dict())
+
+    def test_unpack_empty_data(self):
+        """Test unpack with empty data
+
+        Data: (empty)
+        Expected: Empty MT-ID list
+        """
+        data_bin = b''
+
+        expected = {
+            'type': 'mt_id',
+            'value': []
+        }
+
+        self.assertEqual(expected, MultiTopologyIdentifier.unpack(data_bin).dict())
+
+    def test_unpack_default_topology(self):
+        """Test unpack with default topology (MT-ID = 0)
+
+        Data: 00 00
+            - MT-ID: 0x0000 = 0 (default topology)
+        """
+        data_bin = bytes.fromhex('0000')
+
+        expected = {
+            'type': 'mt_id',
+            'value': [0]
+        }
+
+        self.assertEqual(expected, MultiTopologyIdentifier.unpack(data_bin).dict())
+
+    def test_unpack_max_mt_id(self):
+        """Test unpack with maximum MT-ID value (0xFFFF)
+
+        Data: ff ff
+            - MT-ID: 0xFFFF = 65535 (maximum value)
+        """
+        data_bin = bytes.fromhex('ffff')
+
+        expected = {
+            'type': 'mt_id',
+            'value': [65535]
+        }
+
+        self.assertEqual(expected, MultiTopologyIdentifier.unpack(data_bin).dict())
+
+    def test_unpack_common_mt_ids(self):
+        """Test unpack with common MT-ID values
+
+        Common MT-IDs (RFC 5120):
+            - 0: Default topology
+            - 2: IPv6 unicast topology
+            - 3: IPv4 multicast topology
+            - 4: IPv6 multicast topology
+
+        Data: 00 00 00 02 00 03 00 04
+        """
+        data_bin = bytes.fromhex('0000000200030004')
+
+        expected = {
+            'type': 'mt_id',
+            'value': [0, 2, 3, 4]
+        }
+
+        self.assertEqual(expected, MultiTopologyIdentifier.unpack(data_bin).dict())
+
+    # ==================== Exception/Abnormal Packet Tests ====================
+
+    def test_unpack_single_byte(self):
+        """Test unpack with single byte (incomplete MT-ID)
+
+        Data: 00 (only 1 byte, MT-ID requires 2 bytes)
+        Expected: struct.error
+        """
+        data_bin = bytes.fromhex('00')
+
+        with self.assertRaises(Exception):
+            MultiTopologyIdentifier.unpack(data_bin)
+
+    def test_unpack_odd_bytes_3(self):
+        """Test unpack with odd number of bytes (3 bytes)
+
+        Data: 00 02 00 (3 bytes, last byte is incomplete)
+            - MT-ID 1: 0x0002 = 2 (parsed successfully)
+            - Remaining: 0x00 (incomplete, only 1 byte)
+        Expected: struct.error on second iteration
+        """
+        data_bin = bytes.fromhex('000200')
+
+        with self.assertRaises(Exception):
+            MultiTopologyIdentifier.unpack(data_bin)
+
+    def test_unpack_odd_bytes_5(self):
+        """Test unpack with odd number of bytes (5 bytes)
+
+        Data: 00 02 00 03 00 (5 bytes)
+            - MT-ID 1: 0x0002 = 2
+            - MT-ID 2: 0x0003 = 3
+            - Remaining: 0x00 (incomplete)
+        Expected: struct.error on third iteration
+        """
+        data_bin = bytes.fromhex('0002000300')
+
+        with self.assertRaises(Exception):
+            MultiTopologyIdentifier.unpack(data_bin)
+
+
+if __name__ == "__main__":
+    unittest.main()