fix(protocols): Quick-Start option readers use schema.func, which exists only under TYPE_CHECKING

[JarryShaw]

• Searched for similar pull requests
• Followed the coding style (make pylint, make mypy, make isort) — run on the 5 touched pcapkit/ files with the Makefile flags; no findings on changed lines (2 mypy unused-ignore at hopopt.py:1634/ipv6_opts.py:1623 predate this PR)
• make test passes, and a test case covers the change — the modules listed below, not the full suite
• Added a changelog entry under docs/source/changelog/ and regenerated CHANGELOG.md, if the change is user-visible — N/A, added centrally after the wave

What is the purpose of your pull request?

• fix — corrects a defect

---

Description of your pull request and other information

Closes #1091. _read_opt_qs (IPv4, HOPOPT, IPv6-Opts) now reads flags['func'], matching how it already reads flags['rate']; schema.func is set only by _QSOption.post_process, so maker-built schemas raised AttributeError. HOPOPT/IPv6-Opts quick_start_data_selector also used SchemaField(length=5) for an 8-octet option (the second defect the EXPECTED_FAILURES entries recorded), now 8.

Probe (make_samples.py): before, 8 left out incl. hopopt-option/Quick_Start, ipv4-option/QS, ipv6-opts-option/Quick_Start (no attribute 'func'). After, 5 left out, none Quick-Start; 256 → 259 capturable. A built HOPOPT/IPv6-Opts option with nonce 19088743 decoded as 16777216 with packet length < 0: -3; now 19088743, no warning.

New tests/protocols/internet/test_quick_start_func_unit.py (round trip ×3 families ×2 functions, plus HOPOPT/IPv6-Opts wire nonce). Reverting the reader fix: 6 subtests fail (AttributeError); reverting the length fix: 6 fail (SchemaWarning: packet length < 0: -3). With both: 2 passed, 8 subtests passed. Removed the three Quick-Start EXPECTED_FAILURES entries; test_ipv4_unit and test_ipv6_extension_unit injected schema.func to reach the unknown-function branch, now set flags['func'].

Passing: test_option_roundtrip_unit (6), test_ipv4_unit (26), test_ipv6_extension_unit (61), test_ipv6_ext_unit (30), test_ipv6_extension_runtime (3), test_option_coverage_runtime (3), test_tcp_udp_unit (18), tests/project (379 passed, 1 skipped).

[JarryShaw]

Cross-review verdict on c2f928879: GOOD TO GO (ran on Sonnet; author Opus)

• Length fix. Checked against RFC 4782 §3.2. The IPv6 Quick-Start format matches IPv4's, except that the Length field excludes type and length (6, against 8 for IPv4). Both the Request and Report schemas cover the full 8-octet option, so length=8 is right for HOPOPT and IPv6-Opts. IPv4 already derives 8.
• func is read from flags['func']. An unknown function value still reaches the ProtocolError branch.
• Fails without either fix.
  • Reverting the reader change raises the original AttributeError.
  • Reverting the schema length change fails exactly 6 subtests.
• Tests.
  • test_option_roundtrip_unit passes 360 subtests after removing the three Quick-Start entries.
  • test_ipv4_unit passes 26 and test_ipv6_extension_unit passes 61.
  • make_samples.py against this tree now leaves out 5 cases, none of them the IP-layer Quick-Start options. Those 5 are filed as fix(hip): HOST_ID packs DI-Type/DI-Length as 4 octets where RFC 7401 has one 16-bit word #1118–test(generators): HIP_TRANSFORM is generated into a HIPv2 packet although it is HIPv1-only #1122.

[github-actions]

Coverage: 88.74% (unit tier, Python 3.14, c2f928879, Unit Tests run success)

Package	Statements	Missed	Branches	Partial	Cover
pcapkit (top level)	104	4	20	4	93.55%
pcapkit/const	18757	1035	2342	846	90.23%
pcapkit/corekit	1874	91	578	22	94.33%
pcapkit/dumpkit	136	0	40	0	100.00%
pcapkit/foundation	2422	143	842	34	92.62%
pcapkit/interface	112	7	40	5	92.11%
pcapkit/protocols	15653	187	3942	162	98.19%
pcapkit/toolkit	487	71	144	3	84.15%
pcapkit/utilities	429	4	122	4	98.55%
pcapkit/vendor	4409	2359	1006	158	42.84%

Per-file detail: the coverage-html artifact of this run.