fix(ipv6)!: a CALIPSO option loses its trailing pad and shrinks its length on rebuild (#1403)

pcapkit/protocols/data/internet/hopopt.py

@@ -118,12 +118,14 @@ class CALIPSOOption(Option):
     level: 'int'
     #: Checksum.
     checksum: 'bytes'
+    #: Octets after the compartment bitmap that ``Opt Data Len`` covers.
+    pad: 'bytes'
 
     if TYPE_CHECKING:
         #: Compartment bitmap.
         cmpt_bitmap: 'bytes'
 
-        def __init__(self, type: 'Enum_Option', action: 'int', change: 'bool', length: 'int', domain: 'int', cmpt_len: 'int', level: 'int', checksum: 'bytes') -> 'None': ...  # pylint: disable=super-init-not-called,unused-argument,redefined-builtin,multiple-statements,line-too-long
+        def __init__(self, type: 'Enum_Option', action: 'int', change: 'bool', length: 'int', domain: 'int', cmpt_len: 'int', level: 'int', checksum: 'bytes', pad: 'bytes') -> 'None': ...  # pylint: disable=super-init-not-called,unused-argument,redefined-builtin,multiple-statements,line-too-long
 
 
 class SMFDPDOption(Option):

pcapkit/protocols/data/internet/ipv6_opts.py

@@ -123,13 +123,15 @@ class CALIPSOOption(Option):
     level: 'int'
     #: Checksum.
     checksum: 'bytes'
+    #: Octets after the compartment bitmap that ``Opt Data Len`` covers.
+    pad: 'bytes'
 
     if TYPE_CHECKING:
         #: Compartment bitmap.
         cmpt_bitmap: 'bytes'
 
         def __init__(self, type: 'Enum_Option', action: 'int', change: 'bool', length: 'int', domain: 'int', cmpt_len: 'int', level: 'int',
-                     checksum: 'bytes') -> 'None': ...  # pylint: disable=super-init-not-called,unused-argument,redefined-builtin,multiple-statements,line-too-long
+                     checksum: 'bytes', pad: 'bytes') -> 'None': ...  # pylint: disable=super-init-not-called,unused-argument,redefined-builtin,multiple-statements,line-too-long
 
 
 class SMFDPDOption(Option):

pcapkit/protocols/internet/hopopt.py

@@ -757,6 +757,7 @@ def _read_opt_calipso(self, schema: 'Schema_CALIPSOOption', *, options: 'Option'
             cmpt_len=schema.cmpt_len * 4,
             level=schema.level,
             checksum=schema.checksum,
+            pad=schema.pad,
         )
 
         if schema.cmpt_len > 0:
@@ -1563,6 +1564,7 @@ def _make_opt_calipso(self, code: 'Enum_Option', opt: 'Optional[Data_CALIPSOOpti
                           level: 'int' = 0,
                           checksum: 'bytes' = b'\x00\x00',
                           bitmap: 'Optional[bytes | tuple[int, ...]]' = None,
+                          pad: 'bytes' = b'',
                           **kwargs: 'Any') -> 'Schema_CALIPSOOption':
         """Make HOPOPT calipso option.
 
@@ -1575,6 +1577,7 @@ def _make_opt_calipso(self, code: 'Enum_Option', opt: 'Optional[Data_CALIPSOOpti
             bitmap: compartment bitmap, as :obj:`bytes` or as the
                 :obj:`tuple` of octets the reader stores; its length must be a
                 multiple of 4 octets
+            pad: octets after the compartment bitmap, counted in ``Opt Data Len``
             **kwargs: arbitrary keyword arguments
 
         Returns:
@@ -1593,19 +1596,21 @@ def _make_opt_calipso(self, code: 'Enum_Option', opt: 'Optional[Data_CALIPSOOpti
             level = opt.level
             checksum = opt.checksum
             bitmap = opt.cmpt_bitmap if hasattr(opt, 'cmpt_bitmap') else None
+            pad = opt.pad
         bitmap_bytes = bytes(bitmap) if bitmap is not None else b''
         if len(bitmap_bytes) % 4 != 0:
             raise ProtocolError(f'{self.alias}: [OptNo {code}] invalid CALIPSO bitmap length: '
                                 f'{len(bitmap_bytes)}')
 
         return Schema_CALIPSOOption(
             type=code,
-            len=8 + len(bitmap_bytes),
+            len=8 + len(bitmap_bytes) + len(pad),
             domain=domain,
             cmpt_len=len(bitmap_bytes) // 4,
             level=level,
             checksum=checksum,
             bitmap=bitmap_bytes if bitmap_bytes else None,
+            pad=pad,
         )
 
     def _make_opt_smf_dpd(self, code: 'Enum_Option', opt: 'Optional[Data_SMFIdentificationBasedDPDOption | Data_SMFHashBasedDPDOption]' = None, *,

pcapkit/protocols/internet/ipv6_opts.py

@@ -746,6 +746,7 @@ def _read_opt_calipso(self, schema: 'Schema_CALIPSOOption', *, options: 'Option'
             cmpt_len=schema.cmpt_len * 4,
             level=schema.level,
             checksum=schema.checksum,
+            pad=schema.pad,
         )
 
         if schema.cmpt_len > 0:
@@ -1552,6 +1553,7 @@ def _make_opt_calipso(self, code: 'Enum_Option', opt: 'Optional[Data_CALIPSOOpti
                           level: 'int' = 0,
                           checksum: 'bytes' = b'\x00\x00',
                           bitmap: 'Optional[bytes | tuple[int, ...]]' = None,
+                          pad: 'bytes' = b'',
                           **kwargs: 'Any') -> 'Schema_CALIPSOOption':
         """Make IPv6-Opts calipso option.
 
@@ -1564,6 +1566,7 @@ def _make_opt_calipso(self, code: 'Enum_Option', opt: 'Optional[Data_CALIPSOOpti
             bitmap: compartment bitmap, as :obj:`bytes` or as the
                 :obj:`tuple` of octets the reader stores; its length must be a
                 multiple of 4 octets
+            pad: octets after the compartment bitmap, counted in ``Opt Data Len``
             **kwargs: arbitrary keyword arguments
 
         Returns:
@@ -1582,19 +1585,21 @@ def _make_opt_calipso(self, code: 'Enum_Option', opt: 'Optional[Data_CALIPSOOpti
             level = opt.level
             checksum = opt.checksum
             bitmap = opt.cmpt_bitmap if hasattr(opt, 'cmpt_bitmap') else None
+            pad = opt.pad
         bitmap_bytes = bytes(bitmap) if bitmap is not None else b''
         if len(bitmap_bytes) % 4 != 0:
             raise ProtocolError(f'{self.alias}: [OptNo {code}] invalid CALIPSO bitmap length: '
                                 f'{len(bitmap_bytes)}')
 
         return Schema_CALIPSOOption(
             type=code,
-            len=8 + len(bitmap_bytes),
+            len=8 + len(bitmap_bytes) + len(pad),
             domain=domain,
             cmpt_len=len(bitmap_bytes) // 4,
             level=level,
             checksum=checksum,
             bitmap=bitmap_bytes if bitmap_bytes else None,
+            pad=pad,
         )
 
     def _make_opt_smf_dpd(self, code: 'Enum_Option', opt: 'Optional[Data_SMFIdentificationBasedDPDOption | Data_SMFHashBasedDPDOption]' = None, *,

pcapkit/protocols/schema/internet/hopopt.py

@@ -469,12 +469,13 @@ class CALIPSOOption(Option, code=Enum_Option.CALIPSO):
         BytesField(length=lambda pkt: pkt['cmpt_len'] * 4),
         lambda pkt: pkt['cmpt_len'] > 0,
     )
-    #: Padding.
-    pad: 'bytes' = PaddingField(length=calipso_pad_len)
+    #: Octets that ``Opt Data Len`` covers past the compartment bitmap, kept as
+    #: read rather than packed as zeros.
+    pad: 'bytes' = BytesField(length=calipso_pad_len, default=b'')
 
     if TYPE_CHECKING:
         def __init__(self, type: 'Enum_Option', len: 'int', domain: 'int', cmpt_len: 'int',
-                     level: 'int', checksum: 'bytes', bitmap: 'Optional[bytes]') -> 'None': ...
+                     level: 'int', checksum: 'bytes', bitmap: 'Optional[bytes]', pad: 'bytes' = ...) -> 'None': ...
 
 
 @schema_final

pcapkit/protocols/schema/internet/ipv6_opts.py

@@ -469,12 +469,13 @@ class CALIPSOOption(Option, code=Enum_Option.CALIPSO):
         BytesField(length=lambda pkt: pkt['cmpt_len'] * 4),
         lambda pkt: pkt['cmpt_len'] > 0,
     )
-    #: Padding.
-    pad: 'bytes' = PaddingField(length=calipso_pad_len)
+    #: Octets that ``Opt Data Len`` covers past the compartment bitmap, kept as
+    #: read rather than packed as zeros.
+    pad: 'bytes' = BytesField(length=calipso_pad_len, default=b'')
 
     if TYPE_CHECKING:
         def __init__(self, type: 'Enum_Option', len: 'int', domain: 'int', cmpt_len: 'int',
-                     level: 'int', checksum: 'bytes', bitmap: 'Optional[bytes]') -> 'None': ...
+                     level: 'int', checksum: 'bytes', bitmap: 'Optional[bytes]', pad: 'bytes' = ...) -> 'None': ...
 
 
 @schema_final

tests/protocols/internet/test_ipv6_calipso_pad_unit.py

@@ -0,0 +1,86 @@
+# -*- coding: utf-8 -*-
+"""A CALIPSO option keeps the octets ``Opt Data Len`` covers past its bitmap.
+
+GitHub issue #1403: those octets were a zero-packing padding field missing from
+the data model, so :meth:`~pcapkit.protocols.protocol.ProtocolBase.from_data`
+dropped them, shrank ``Opt Data Len`` and padded the header with a ``PadN``
+instead. They are now the ``pad`` data field, written back on rebuild.
+
+Every case builds its own octets in memory and reads no capture. The classes
+are imported inside each test, after
+:func:`~tests._support.reimport_once_per_class`, so that they belong to the
+:mod:`pcapkit` import that is live when the test runs.
+
+"""
+
+import importlib
+import io
+import unittest
+
+from tests._support import reimport_once_per_class
+
+#: The protocol classes sharing the option code, by module and class name.
+PROTOCOLS = (
+    ('pcapkit.protocols.internet.hopopt', 'HOPOPT'),
+    ('pcapkit.protocols.internet.ipv6_opts', 'IPv6_Opts'),
+)
+
+#: Parsed headers which have to rebuild unchanged, with the pad each carries.
+HEADERS = {
+    'cmpt_len 0, zero pad': ('3b01' '070c' '00000001' '0005' '0000' '00000000', b'\x00' * 4),
+    'cmpt_len 0, non-zero pad': ('3b01' '070c' '00000001' '0005' '0000' 'aabbccdd',
+                                 b'\xaa\xbb\xcc\xdd'),
+    'cmpt_len 2, zero pad': ('3b02' '0714' '00000001' '0205' '0000' '1122334455667788' '00000000',
+                             b'\x00' * 4),
+    'cmpt_len 2, non-zero pad': ('3b02' '0714' '00000001' '0205' '0000' '1122334455667788' 'aabbccdd',
+                                 b'\xaa\xbb\xcc\xdd'),
+    'cmpt_len 0, no pad': ('3b01' '0708' '00000001' '0005' '0000' '01020000', b''),
+}
+
+
+class TestCALIPSOPad(unittest.TestCase):
+    """Pin the CALIPSO pad through read, make and rebuild."""
+
+    def setUp(self) -> None:
+        reimport_once_per_class(self)
+
+    def _protocols(self) -> 'list[type]':
+        return [getattr(importlib.import_module(mod), name) for mod, name in PROTOCOLS]
+
+    def _parse(self, cls: 'type', octets: 'bytes') -> 'object':
+        return cls(io.BytesIO(octets), len(octets), extension=True)
+
+    def test_parsed_headers_rebuild_byte_for_byte(self) -> None:
+        from pcapkit.const.ipv6.option import Option
+
+        for cls in self._protocols():
+            for label, (hexstr, pad) in HEADERS.items():
+                octets = bytes.fromhex(hexstr)
+                with self.subTest(protocol=cls.__name__, header=label):
+                    parsed = self._parse(cls, octets)
+                    self.assertEqual(parsed.info.options[Option.CALIPSO].pad, pad)  # type: ignore[attr-defined]
+                    self.assertEqual(cls.from_data(parsed.info).data, octets)
+
+    def test_make_writes_the_pad_and_counts_it_in_the_length(self) -> None:
+        from pcapkit.const.ipv6.option import Option
+
+        for cls in self._protocols():
+            with self.subTest(protocol=cls.__name__, cmpt_len=0):
+                made = cls(next=59, options=[(Option.CALIPSO, {
+                    'domain': 1, 'level': 5, 'pad': b'\xaa\xbb\xcc\xdd',
+                })])
+                self.assertEqual(made.data, bytes.fromhex(HEADERS['cmpt_len 0, non-zero pad'][0]))
+            with self.subTest(protocol=cls.__name__, cmpt_len=2):
+                made = cls(next=59, options=[(Option.CALIPSO, {
+                    'domain': 1, 'level': 5, 'bitmap': bytes.fromhex('1122334455667788'),
+                    'pad': b'\x00' * 4,
+                })])
+                self.assertEqual(made.data, bytes.fromhex(HEADERS['cmpt_len 2, zero pad'][0]))
+            with self.subTest(protocol=cls.__name__, pad=None):
+                # without a pad the option is the fixed header alone, as before
+                made = cls(next=59, options=[(Option.CALIPSO, {'domain': 1, 'level': 5})])
+                self.assertEqual(made.data, bytes.fromhex(HEADERS['cmpt_len 0, no pad'][0]))
+
+
+if __name__ == '__main__':
+    unittest.main()

tests/protocols/internet/test_ipv6_extension_unit.py

@@ -791,7 +791,7 @@ def _assert_option_data_model_constructor_edges(self, protocol_cls: type) -> Non
 
         calipso = data.CALIPSOOption(type=Option.CALIPSO, length=10, domain=7,
                                      cmpt_len=4, level=3, checksum=b'\x01\x02',
-                                     **base)
+                                     pad=b'', **base)
         calipso.__update__([('cmpt_bitmap', b'\xaa\xbb\xcc\xdd')])
         self.assertEqual(proto._make_opt_calipso(Option.CALIPSO, calipso).bitmap, b'\xaa\xbb\xcc\xdd')