✨ Feat(bgpprefixsid.py): add support for parsing the Path Attribute: …

…BGP Prefix-SID (Type 40)

Refer:
https://github.com/Exa-Networks/exabgp/blob/main/src/exabgp/bgp/message/update/attribute/sr/prefixsid.py

yabgp/common/constants.py

@@ -89,6 +89,7 @@
 BGPTYPE_TUNNEL_ENCAPS_ATTR = 23  # RFC5512
 BGPTYPE_LINK_STATE = 29
 BGPTYPE_LARGE_COMMUNITY = 32
+BGPTYPE_BGP_PREFIX_SID = 40  # RFC8669 & RFC9252
 BGPTYPE_ATTRIBUTE_SET = 128
 
 # BGP Tunnel Encapsulation Attribute Tunnel Types

yabgp/message/attribute/__init__.py

@@ -46,6 +46,7 @@ class AttributeFlag(int):
     PARTIAL = 0x20  # 32  RFC 4271
     TRANSITIVE = 0x40  # 64  RFC 4271
     OPTIONAL = 0x80  # 128 RFC 4271
+
     # OPTIONAL_TRANSITIVE = 0xc0  # 192 RFC 4271
 
     def __str_(self):
@@ -110,6 +111,7 @@ class AttributeID(int):
     Traffic_Engineering = 0x18  # 24  [RFC5543]
     IPv6_Address_Specific_Extended_Community = 0x19  # 25  [RFC5701]
     LARGE_COMMUNITY = 0x20  # 32  [8092]
+    BGP_PREFIX_SID = 0x28  # 40 [RFC8669 & RFC9252]
     LINKSTATE = 0x1d
     ATTR_SET = 0x80  # 128 [RFC6368]
 

yabgp/message/attribute/sr/__init__.py

@@ -0,0 +1,19 @@
+# Copyright 2024 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.
+
+from .bgpprefixsid import BGPPrefixSID  # noqa
+from .srv6.l3service import SRv6L3Service  # noqa
+from .srv6.sidinformation import SRv6SIDInformation  # noqa
+from .srv6.sidstructure import SRv6SIDStructure  # noqa

yabgp/message/attribute/sr/bgpprefixsid.py

@@ -0,0 +1,90 @@
+# Copyright 2024 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
+
+import binascii
+
+from yabgp.message.attribute import Attribute, AttributeFlag, AttributeID
+
+
+class BGPPrefixSID(Attribute):
+    """
+    BGP Prefix SID
+
+    Original: https://datatracker.ietf.org/doc/html/rfc8669#section-3
+    Extend: https://datatracker.ietf.org/doc/html/rfc9252#section-2
+    """
+
+    ID = AttributeID.BGP_PREFIX_SID
+    FLAG = AttributeFlag.OPTIONAL + AttributeFlag.TRANSITIVE
+
+    registered_tlvs = dict()
+
+    def __init__(self, value, hex_value=None):
+        self.value = value
+        self.hex_value = hex_value
+
+    @classmethod
+    def register(cls, _type=None):
+        """
+
+        :param _type:
+        :return:
+        """
+
+        def decorator(klass):
+            """
+
+            :param klass:
+            :return:
+            """
+            _id = klass.TYPE if _type is None else _type
+            if _id in cls.registered_tlvs:
+                raise RuntimeError('Duplicated attribute type')
+            cls.registered_tlvs[_id] = klass
+            return klass
+
+        return decorator
+
+    def dict(self):
+        """
+
+        :return:
+        """
+        return {self.ID: self.value}
+
+    @classmethod
+    def unpack(cls, data):
+        """
+
+        :param data:
+        :return:
+        """
+        tlvs = []
+        while data:
+            type_code = data[0]  # Note: Type = 1 octet
+            length = struct.unpack('!H', data[1:3])[0]  # Note: Length = 2 octet
+            value = data[3: 3 + length]
+
+            if type_code in cls.registered_tlvs:
+                tlvs.append(cls.registered_tlvs[type_code].unpack(value).dict())
+            else:
+                tlvs.append({
+                    'type': type_code,
+                    'value': str(binascii.b2a_hex(value))
+                })
+            data = data[3 + length:]
+        return cls(value=tlvs)

yabgp/message/attribute/sr/srv6/__init__.py

@@ -0,0 +1,8 @@
+#    +---------------+---------------------------------+----------+-----------------+
+#    |    TLV Code   | Description                     | Length   | Reference       |
+#    |     Point     |                                 |          |                 |
+#    +---------------+---------------------------------+----------+-----------------+
+#    |      5        | SRv6 L3 Service TLV             | variable | Section 2       |
+#    |      1        | SRv6 SID Information Sub-TLV    | variable | Section 3.1     |
+#    |      1        | SRv6 SID Structure Sub-Sub-TLV  |    6     | Section 3.2.1   |
+#    +---------------+---------------------------------+----------+-----------------+

yabgp/message/attribute/sr/srv6/l3service.py

@@ -0,0 +1,96 @@
+# Copyright 2024 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
+
+import binascii
+
+from yabgp.tlv import TLV
+from ..bgpprefixsid import BGPPrefixSID
+
+
+# 2.  SRv6 Services TLVs
+#
+#  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
+# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+# |   TLV Type    |         TLV Length            |   RESERVED    |
+# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+# |   SRv6 Service Sub-TLVs                                      //
+# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+#
+#                   Figure 1: SRv6 Service TLVs
+
+
+@BGPPrefixSID.register()
+class SRv6L3Service(TLV):
+    """
+    SRv6 L3 Service
+    """
+    TYPE = 5  # https://datatracker.ietf.org/doc/html/rfc9252.html#section-2
+    TYPE_STR = 'srv6_l3_service'
+
+    registered_tlvs = dict()
+
+    @classmethod
+    def register(cls, _type=None):
+        """
+
+        :param _type:
+        :return:
+        """
+
+        def decorator(klass):
+            """
+
+            :param klass:
+            :return:
+            """
+            _id = klass.TYPE if _type is None else _type
+            if _id in cls.registered_tlvs:
+                raise RuntimeError('Duplicated SRv6 Service Sub-TLV type')
+            cls.registered_tlvs[_id] = klass
+            return klass
+
+        return decorator
+
+    @classmethod
+    def unpack(cls, data):
+        """
+
+        :param data:
+        :return:
+        """
+        tlvs = []
+
+        # reserved = data[0:1]  # Note: First byte is reserved
+        data = data[1:]
+        while data:
+            type_code = data[0]  # Note: Type = 1 octet
+            length = struct.unpack('!H', data[1:3])[0]  # Note: Length = 2 octet
+            value = data[3: 3 + length]
+
+            if type_code in cls.registered_tlvs:
+                tlvs.append(cls.registered_tlvs[type_code].unpack(value).dict())
+            else:
+                tlvs.append({
+                    'type': type_code,
+                    'value': str(binascii.b2a_hex(value))
+                })
+            data = data[3 + length:]
+        value = {
+            'srv6_service_sub_tlvs': tlvs
+        }
+        return cls(value=value)

yabgp/message/attribute/sr/srv6/sidinformation.py

@@ -0,0 +1,111 @@
+# Copyright 2024 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
+
+import binascii
+import netaddr
+
+from yabgp.tlv import TLV
+from .l3service import SRv6L3Service
+
+
+# 3.1.  SRv6 SID Information Sub-TLV
+#
+#  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
+# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+# | SRv6 Service  |    SRv6 Service               |               |
+# | Sub-TLV       |    Sub-TLV                    |               |
+# | Type=1        |    Length                     |  RESERVED1    |
+# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+# |  SRv6 SID Value (16 octets)                                  //
+# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+# | Svc SID Flags |   SRv6 Endpoint Behavior      |   RESERVED2   |
+# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+# |  SRv6 Service Data Sub-Sub-TLVs                              //
+# +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+#            Figure 3: SRv6 SID Information Sub-TLV
+
+
+@SRv6L3Service.register()
+class SRv6SIDInformation(TLV):
+    """
+    SRv6 SID Information
+    """
+    TYPE = 1  # https://datatracker.ietf.org/doc/html/rfc9252.html#section-3.1
+    TYPE_STR = 'srv6_sid_information'
+
+    registered_tlvs = dict()
+
+    @classmethod
+    def register(cls, _type=None):
+        """
+
+        :param _type:
+        :return:
+        """
+
+        def decorator(klass):
+            """
+
+            :param klass:
+            :return:
+            """
+            _id = klass.TYPE if _type is None else _type
+            if _id in cls.registered_tlvs:
+                raise RuntimeError('Duplicated SRv6 Service Data Sub-Sub-TLV type')
+            cls.registered_tlvs[_id] = klass
+            return klass
+
+        return decorator
+
+    @classmethod
+    def unpack(cls, data):
+        """
+
+        :param data:
+        :return:
+        """
+        tlvs = []
+
+        # reserved_1 = data[0:1]  # Note: First byte is reserved
+        srv6_sid_value = str(netaddr.IPAddress(int(binascii.b2a_hex(data[1:17]), 16)))
+        srv6_service_sid_flags = ord(data[17:18])
+        srv6_endpoint_behavior = struct.unpack('!H', data[18:20])[0]
+        # reserved_2 = data[20:21]  # Note: Also reserved
+        data = data[21:]
+        while data:
+            srv6_service_sub_tlv_type_code = data[0]  # Note: Type = 1 octet
+            srv6_service_sub_tlv_length = struct.unpack('!H', data[1:3])[0]  # Note: Length = 2 octet
+            value = data[3: 3 + srv6_service_sub_tlv_length]
+
+            if srv6_service_sub_tlv_type_code in cls.registered_tlvs:
+                tlvs.append(cls.registered_tlvs[srv6_service_sub_tlv_type_code].unpack(value).dict())
+            else:
+                tlvs.append({
+                    'type': srv6_service_sub_tlv_type_code,
+                    'value': str(binascii.b2a_hex(value))
+                })
+            data = data[3 + srv6_service_sub_tlv_length:]
+        value = {
+            'srv6_sid_value': srv6_sid_value,
+            'srv6_service_sid_flags': srv6_service_sid_flags,
+            'srv6_endpoint_behavior': srv6_endpoint_behavior,
+
+            'srv6_service_data_sub_sub_tlvs': tlvs
+        }
+        return cls(value=value)