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fix(ipv4): word the SEC termination-indicator warning the right way round (#2295) #2372

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Merged
JarryShaw merged 1 commit into from
Oct 27, 2026
Merged

fix(ipv4): word the SEC termination-indicator warning the right way round (#2295) #2372

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3 changes: 2 additions & 1 deletion pcapkit/protocols/internet/ipv4.py
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Original file line number Diff line number Diff line change
Expand Up @@ -887,7 +887,8 @@ def _read_opt_sec(self, schema: 'Schema_SECOption', *, options: 'Option') -> 'Da
warn(f'{self.alias}: [OptNo {schema.type}] invalid format: remaining data', ProtocolWarning)

if schema.data[-1] & 0x01 == 1:
warn(f'{self.alias}: [OptNo {schema.type}] invalid format: field termination indicator not set', ProtocolWarning)
warn(f'{self.alias}: [OptNo {schema.type}] invalid format: '
f'field termination indicator set on the final octet: {schema.data[-1]!r}', ProtocolWarning)
termination = tuple(bool(byte & 0x01) for byte in schema.data)
else:
flags = []
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8 changes: 6 additions & 2 deletions tests/protocols/internet/test_ipv4_roundtrip_unit.py
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Expand Up @@ -156,9 +156,13 @@ def test_sec_termination_indicator_follows_rfc_1108(self) -> None:
option = self.parse(header('8204ab90')).info.options[OptionNumber.SEC]
self.assertEqual(option.flags, (ProtectionAuthority.GENSER, ProtectionAuthority.NSA))

# The low-order bit set on the final octet promises another octet.
with self.assertWarnsRegex(ProtocolWarning, 'field termination indicator not set'):
# The low-order bit set on the final octet promises another octet, and
# the warning names the bit that is set rather than one that is not
# (#2295). ``0x91`` is 145.
with self.assertWarns(ProtocolWarning) as caught:
self.parse(header('8204ab91'))
self.assertEqual(str(caught.warning), 'IPv4: [OptNo 130] invalid format: '
'field termination indicator set on the final octet: 145')

def test_timestamp_keeps_the_high_order_bit(self) -> None:
from pcapkit.const.ipv4.option_number import OptionNumber
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6 changes: 3 additions & 3 deletions tests/protocols/internet/test_ipv4_unit.py
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Expand Up @@ -502,9 +502,9 @@ def test_ipv4_make_opt_sec_sets_the_field_termination_indicator(self) -> None:
:rfc:`1108` section 2.4(a) makes the low-order bit of each protection
authority octet a *field termination indicator*: ``1`` means another
octet follows, ``0`` means this is the last. ``_read_opt_sec`` enforces
it, warning ``field termination indicator not set`` when the final octet
has it set. The writer and the reader agree with each other (#537) and
with the RFC (#1321).
it, warning ``field termination indicator set on the final octet`` when
the final octet has it set. The writer and the reader agree with each
other (#537) and with the RFC (#1321).

The round trip is asserted through a real datagram and with warnings
promoted to errors, because a disagreement's only symptom is a warning.
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