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refactor: extract duplicated wire-unit arithmetic across mh/ipv6_route/hopopt/ipv6_opts #509

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Merged
JarryShaw merged 2 commits into from
Sep 19, 2026
Merged

refactor: extract duplicated wire-unit arithmetic across mh/ipv6_route/hopopt/ipv6_opts #509

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d9d8520
refactor: extract duplicated wire-unit arithmetic in mh/ipv6_route/ho…
JarryShaw Sep 19, 2026
ba971c5
Merge branch 'main' into refactor/495-extract-wire-arithmetic
JarryShaw Sep 19, 2026
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65 changes: 48 additions & 17 deletions pcapkit/protocols/internet/hopopt.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -449,6 +449,37 @@ def _read_opt_type(self, kind: 'int') -> 'tuple[int, bool]':
bin_ = bin(kind)[2:].zfill(8)
return int(bin_[:2], base=2), bool(int(bin_[2], base=2))

@staticmethod
def _hopopt_option_length(schema_len: 'int') -> 'int':
"""Compute a HOPOPT option's whole-option length from its on-the-wire ``Opt Data Len``.

Per :rfc:`8200#section-4.3`, an option's ``Opt Data Len`` field
(what each ``Schema_*Option.len`` here holds) counts *"the length of
the Option Data field of this option, in octets"* -- i.e. it
excludes the Option Type and Opt Data Len fields themselves, so the
whole option, which is what every ``_read_opt_*`` below reports back
as the parsed option's own ``.length``, is two octets more. This is
the exact ``+2``/``-2`` mismatch #398 fixed independently in six
places (see ``Data_PadOption.length`` vs. ``Schema_PadOption.length``
below, at the surviving explanation of that fix); collecting the
read-side half of it into one helper is so a future fix to this
arithmetic only has to happen once. Do NOT drop the ``+ 2``: that is
precisely the mismatch #398 fixed.

Note that only the *stored-length* read-side call sites are
collected here -- most ``_make_opt_*`` methods recompute the wire
``Opt Data Len`` from ``len(value)`` rather than reading a parsed
``.length`` back, so they have nothing to unify against this helper.

Args:
schema_len: raw ``Opt Data Len`` field value, as read off the wire.

Returns:
Whole-option length, in octets, including the Type and Opt Data Len fields.

"""
return schema_len + 2

def _read_hopopt_options(self, length: 'int') -> 'Option':
"""Read HOPOPT options.

Expand Down Expand Up @@ -509,7 +540,7 @@ def _read_opt_none(self, schema: 'Schema_UnassignedOption', *, options: 'Option'
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
data=schema.data,
)
return opt
Expand Down Expand Up @@ -569,7 +600,7 @@ def _read_opt_pad(self, schema: 'Schema_PadOption', *, options: 'Option') -> 'Da
if code == Enum_Option.Pad1:
_size = 1
else:
_size = schema.len + 2
_size = self._hopopt_option_length(schema.len)

opt = Data_PadOption(
type=schema.type,
Expand Down Expand Up @@ -610,7 +641,7 @@ def _read_opt_tun(self, schema: 'Schema_TunnelEncapsulationLimitOption', *, opti
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
limit=schema.limit,
)
return opt
Expand Down Expand Up @@ -644,7 +675,7 @@ def _read_opt_ra(self, schema: 'Schema_RouterAlertOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
value=schema.alert,
)
return opt
Expand Down Expand Up @@ -686,7 +717,7 @@ def _read_opt_calipso(self, schema: 'Schema_CALIPSOOption', *, options: 'Option'
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
domain=schema.domain,
cmpt_len=schema.cmpt_len * 4,
level=schema.level,
Expand Down Expand Up @@ -753,7 +784,7 @@ def _read_opt_smf_dpd(self, schema: 'Schema_SMFDPDOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
dpd_type=mode,
tid_type=tid_type,
tid_len=tid_len,
Expand All @@ -768,7 +799,7 @@ def _read_opt_smf_dpd(self, schema: 'Schema_SMFDPDOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
dpd_type=mode,
hav=schema.hav,
)
Expand Down Expand Up @@ -811,7 +842,7 @@ def _read_opt_pdm(self, schema: 'Schema_PDMOption', *, options: 'Option') -> 'Da
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
scaledtlr=schema.scaledtlr,
scaledtls=schema.scaledtls,
psntp=schema.psntp,
Expand Down Expand Up @@ -875,7 +906,7 @@ def _read_opt_qs(self, schema: 'Schema_QuickStartOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema_req.len + 2,
length=self._hopopt_option_length(schema_req.len),
func=func,
rate=40000 * (2 ** rate) / 1000 if rate > 0 else 0,
ttl=datetime.timedelta(seconds=schema_req.ttl),
Expand All @@ -889,7 +920,7 @@ def _read_opt_qs(self, schema: 'Schema_QuickStartOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema_rep.len + 2,
length=self._hopopt_option_length(schema_rep.len),
func=func,
rate=40000 * (2 ** rate) / 1000 if rate > 0 else 0,
nonce=schema_rep.nonce['nonce'],
Expand Down Expand Up @@ -933,7 +964,7 @@ def _read_opt_rpl(self, schema: 'Schema_RPLOption', *, options: 'Option') -> 'Da
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
flags=Data_RPLFlags(
down=bool(schema.flags['down']),
rank_err=bool(schema.flags['rank_err']),
Expand Down Expand Up @@ -994,7 +1025,7 @@ def _read_opt_mpl(self, schema: 'Schema_MPLOption', *, options: 'Option') -> 'Da
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
seed_type=kind,
flags=Data_MPLFlags(
max=bool(schema.flags['max']),
Expand Down Expand Up @@ -1032,7 +1063,7 @@ def _read_opt_ilnp(self, schema: 'Schema_ILNPOption', *, options: 'Option') -> '
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
nonce=schema.nonce,
)
return opt
Expand Down Expand Up @@ -1064,7 +1095,7 @@ def _read_opt_lio(self, schema: 'Schema_LineIdentificationOption', *, options: '
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
line_id_len=schema.id_len,
line_id=schema.id,
)
Expand Down Expand Up @@ -1101,7 +1132,7 @@ def _read_opt_jumbo(self, schema: 'Schema_JumboPayloadOption', *, options: 'Opti
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
jumbo_len=schema.jumbo_len,
)
return opt
Expand Down Expand Up @@ -1145,7 +1176,7 @@ def _read_opt_home(self, schema: 'Schema_HomeAddressOption', *, options: 'Option
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
address=schema.addr,
)
return opt
Expand Down Expand Up @@ -1183,7 +1214,7 @@ def _read_opt_ip_dff(self, schema: 'Schema_IPDFFOption', *, options: 'Option') -
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._hopopt_option_length(schema.len),
version=schema.flags['ver'],
flags=Data_DFFFlags(
dup=bool(schema.flags['dup']),
Expand Down
65 changes: 48 additions & 17 deletions pcapkit/protocols/internet/ipv6_opts.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -460,6 +460,37 @@ def _read_opt_type(self, kind: 'int') -> 'tuple[int, bool]':
bin_ = bin(kind)[2:].zfill(8)
return int(bin_[:2], base=2), bool(int(bin_[2], base=2))

@staticmethod
def _ipv6_opts_option_length(schema_len: 'int') -> 'int':
"""Compute an IPv6-Opts option's whole-option length from its on-the-wire ``Opt Data Len``.

Per :rfc:`8200#section-4.3`, an option's ``Opt Data Len`` field
(what each ``Schema_*Option.len`` here holds) counts *"the length of
the Option Data field of this option, in octets"* -- i.e. it
excludes the Option Type and Opt Data Len fields themselves, so the
whole option, which is what every ``_read_opt_*`` below reports back
as the parsed option's own ``.length``, is two octets more. This is
the exact ``+2``/``-2`` mismatch #398 fixed independently in six
places (see ``Data_PadOption.length`` vs. ``Schema_PadOption.length``
below, at the surviving explanation of that fix); collecting the
read-side half of it into one helper is so a future fix to this
arithmetic only has to happen once. Do NOT drop the ``+ 2``: that is
precisely the mismatch #398 fixed.

Note that only the *stored-length* read-side call sites are
collected here -- most ``_make_opt_*`` methods recompute the wire
``Opt Data Len`` from ``len(value)`` rather than reading a parsed
``.length`` back, so they have nothing to unify against this helper.

Args:
schema_len: raw ``Opt Data Len`` field value, as read off the wire.

Returns:
Whole-option length, in octets, including the Type and Opt Data Len fields.

"""
return schema_len + 2

def _read_ipv6_opts(self, length: 'int') -> 'Option':
"""Read IPv6-Opts options.

Expand Down Expand Up @@ -520,7 +551,7 @@ def _read_opt_none(self, schema: 'Schema_UnassignedOption', *, options: 'Option'
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
data=schema.data,
)
return opt
Expand Down Expand Up @@ -581,7 +612,7 @@ def _read_opt_pad(self, schema: 'Schema_PadOption', *, options: 'Option') -> 'Da
if code == Enum_Option.Pad1:
_size = 1
else:
_size = schema.len + 2
_size = self._ipv6_opts_option_length(schema.len)

opt = Data_PadOption(
type=schema.type,
Expand Down Expand Up @@ -622,7 +653,7 @@ def _read_opt_tun(self, schema: 'Schema_TunnelEncapsulationLimitOption', *, opti
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
limit=schema.limit,
)
return opt
Expand Down Expand Up @@ -656,7 +687,7 @@ def _read_opt_ra(self, schema: 'Schema_RouterAlertOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
value=schema.alert,
)
return opt
Expand Down Expand Up @@ -698,7 +729,7 @@ def _read_opt_calipso(self, schema: 'Schema_CALIPSOOption', *, options: 'Option'
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
domain=schema.domain,
cmpt_len=schema.cmpt_len * 4,
level=schema.level,
Expand Down Expand Up @@ -765,7 +796,7 @@ def _read_opt_smf_dpd(self, schema: 'Schema_SMFDPDOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
dpd_type=mode,
tid_type=tid_type,
tid_len=tid_len,
Expand All @@ -780,7 +811,7 @@ def _read_opt_smf_dpd(self, schema: 'Schema_SMFDPDOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
dpd_type=mode,
hav=schema.hav,
)
Expand Down Expand Up @@ -823,7 +854,7 @@ def _read_opt_pdm(self, schema: 'Schema_PDMOption', *, options: 'Option') -> 'Da
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
scaledtlr=schema.scaledtlr,
scaledtls=schema.scaledtls,
psntp=schema.psntp,
Expand Down Expand Up @@ -887,7 +918,7 @@ def _read_opt_qs(self, schema: 'Schema_QuickStartOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema_req.len + 2,
length=self._ipv6_opts_option_length(schema_req.len),
func=func,
rate=40000 * (2 ** rate) / 1000 if rate > 0 else 0,
ttl=datetime.timedelta(seconds=schema_req.ttl),
Expand All @@ -901,7 +932,7 @@ def _read_opt_qs(self, schema: 'Schema_QuickStartOption', *, options: 'Option')
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema_rep.len + 2,
length=self._ipv6_opts_option_length(schema_rep.len),
func=func,
rate=40000 * (2 ** rate) / 1000 if rate > 0 else 0,
nonce=schema_rep.nonce['nonce'],
Expand Down Expand Up @@ -945,7 +976,7 @@ def _read_opt_rpl(self, schema: 'Schema_RPLOption', *, options: 'Option') -> 'Da
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
flags=Data_RPLFlags(
down=bool(schema.flags['down']),
rank_err=bool(schema.flags['rank_err']),
Expand Down Expand Up @@ -1006,7 +1037,7 @@ def _read_opt_mpl(self, schema: 'Schema_MPLOption', *, options: 'Option') -> 'Da
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
seed_type=kind,
flags=Data_MPLFlags(
max=bool(schema.flags['max']),
Expand Down Expand Up @@ -1044,7 +1075,7 @@ def _read_opt_ilnp(self, schema: 'Schema_ILNPOption', *, options: 'Option') -> '
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
nonce=schema.nonce,
)
return opt
Expand Down Expand Up @@ -1076,7 +1107,7 @@ def _read_opt_lio(self, schema: 'Schema_LineIdentificationOption', *, options: '
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
line_id_len=schema.id_len,
line_id=schema.id,
)
Expand Down Expand Up @@ -1113,7 +1144,7 @@ def _read_opt_jumbo(self, schema: 'Schema_JumboPayloadOption', *, options: 'Opti
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
jumbo_len=schema.jumbo_len,
)
return opt
Expand Down Expand Up @@ -1157,7 +1188,7 @@ def _read_opt_home(self, schema: 'Schema_HomeAddressOption', *, options: 'Option
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
address=schema.addr,
)
return opt
Expand Down Expand Up @@ -1195,7 +1226,7 @@ def _read_opt_ip_dff(self, schema: 'Schema_IPDFFOption', *, options: 'Option') -
type=schema.type,
action=Enum_OptionAction.get(schema.type >> 6),
change=bool(schema.type & 0b00100000),
length=schema.len + 2,
length=self._ipv6_opts_option_length(schema.len),
version=schema.flags['ver'],
flags=Data_DFFFlags(
dup=bool(schema.flags['dup']),
Expand Down
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