[JarryShaw]

• Searched for similar pull requests

• Followed the coding style (mypy and isort clean on both files; pylint adds no new message class)

• make test passes, and a test case covers the change — ran the modules listed below, not the full suite

• Added a changelog entry — N/A, added centrally

• fix — corrects a defect

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Closes #1190. _make_opt_smf_dpd (HOPOPT and IPv6-Opts) now lets the parsed DPD mode win, as #1187 did for the MPL seed_type. The TaggerID type had the same problem: it was inferred from the Tagger ID length, so a 4-octet DEFAULT Tagger ID rebuilt as IPv4. It is now taken from the parsed option, or from a new tid_type keyword. A Tagger ID that does not fit its type, or is over 16 octets, raises ProtocolError.

Case	Before	After
H-DPD 3b00080481020304	3b00080100010100	byte-exact
I-DPD DEFAULT 4-octet …0807130a0b0c0d…	…0807230a0b0c0d…	byte-exact

Tests: the new tests/protocols/internet/test_smf_dpd_mode_rebuild_unit.py passes 4/4. With the fix reverted, 3 of its tests fail (14 subtests). test_ipv6_extension_unit (61), test_ipv6_extension_runtime, test_mpl_seed_rebuild_unit, test_option_roundtrip_unit and tests/project (389 passed, 1 skipped) all pass. util/run_unittest_leg.py protocols/internet reports 488 tests, 0 failures.

[github-actions]

Coverage: 88.90% (unit tier, Python 3.14, 45d815f70, Unit Tests run success)

Package	Statements	Missed	Branches	Partial	Cover
pcapkit (top level)	104	4	20	4	93.55%
pcapkit/const	18757	1034	2342	845	90.24%
pcapkit/corekit	1878	91	580	22	94.34%
pcapkit/dumpkit	142	0	42	0	100.00%
pcapkit/foundation	2442	102	852	39	94.38%
pcapkit/interface	112	7	40	5	92.11%
pcapkit/protocols	15753	190	4022	165	98.17%
pcapkit/toolkit	487	65	144	1	85.42%
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.

[JarryShaw]

Cross-review verdict on 45d815f70: GOOD TO GO (ran on Sonnet; the author ran on Opus).

• Fixed: H-DPD 3b00080481020304 and I-DPD DEFAULT with a 4-octet tagger ID now rebuild byte-exactly in both HOPOPT and IPv6_Opts. On main they rebuild as I-DPD/null and as IPv4. I re-ran the H-DPD case myself.
• No regressions: NULL, IPv4 and DEFAULT 2-octet were already exact and still are. The two SMF_DPD headers in options-ipv6.pcap round-trip on both sides.
• No behaviour change without tid_type: a 114-cell grid with no tid_type builds byte-identically on both sides for valid input. Two inputs differ:
  • tid=b'' raised ValueError on main (not TidLen -1, as the PR body says) and now builds NULL.
  • 17 octets raised FieldValueError and now raises ProtocolError.
• Tests: without the fix, the new module has 14 failing subtests; test_mode_keyword_selects_h_dpd passes on both sides by design. run_unittest_leg.py protocols/internet: 488 tests, 0 failures.
• UNVERIFIED: the RFC 6621 TidLen/TidTy semantics were checked against the parser and enum, not against the RFC text.
• Out of scope: H-DPD with an empty hav raises IndexError on both sides (hopopt.py:1678 on main). Filed separately.