feat(link): decode radiotap's optional fields #2576

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1. JarryShaw

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   featPull requests that add a new capability (feat: subject prefix)Pull requests that add a new capability (feat: subject prefix)

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   on Nov 1, 2026
2. JarryShaw

   added this to PyPCAPKiton Nov 1, 2026
3. JarryShaw

   moved this to Blocked in PyPCAPKiton Nov 1, 2026
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   added this to the PyPCAPKit v1.6 milestone on Nov 2, 2026
5. JarryShaw commented on Nov 2, 2026

   

   JarryShaw

   on Nov 2, 2026

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   #2607 has merged, so radiotap.py is free. Unblocked. A worker is on it. Optional fields are decoded per the radiotap.org specification and cross-checked against Wireshark or the kernel. Unknown and vendor fields stay raw, with byte-exact round trips.
6. JarryShaw

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   wipWork in flight - a covering PR is open or an agent is actively on itWork in flight - a covering PR is open or an agent is actively on it

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   blockedDeferred pending another issue or decision; see the last comment for what unblocks itDeferred pending another issue or decision; see the last comment for what unblocks it

   on Nov 2, 2026
7. JarryShaw

   added a commit that references this issue on Nov 2, 2026

   docs(pep): correct stale status lines and drop the redundant release …

   ...

   83f05f5
8. JarryShaw

   moved this from Blocked to WIP in PyPCAPKiton Nov 2, 2026
9. JarryShaw commented on Nov 2, 2026

   

   JarryShaw

   on Nov 2, 2026

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   Optional-field decoding is done locally, and a Sonnet review is running.

   • Each defined field is decoded per radiotap.org, with its alignment counted from the header start. Extended presence words, the radiotap/vendor namespace switches and TLV mode are all handled.
   • Unknown and vendor fields stay raw. Captured octets round-trip exactly. Output for existing captures is unchanged.
   • The field types are a new pcapkit.const.radiotap.FieldType, generated by a crawler of radiotap.org.

   Needs deciding. The branch implements both recommendations unless you choose otherwise.

   1. Bits 16 and 17 (RTS retries, data retries). radiotap.org lists them only as unofficial, but Linux mac80211 writes bit 17 on TX-status frames. Decoding currently stops at them.
      • (a) Leave them undecoded.
      • (b) Decode both.
      • (c) Decode only bit 17, since OpenBSD writes RSSI in bit 16.
      • Recommend (c), as a follow-up.
   2. Bitmap fields stay plain integers. This covers Flags, the Channel flags, RX/TX flags and the MCS/VHT/HE known bits.
      • (a) Keep them as integers.
      • (b) Decode them into named flags. Each flag table then needs its own crawler.
      • Recommend (a). A follow-up could use the Flags FCS (0x10) and data-pad (0x20) bits to let IEEE802_11 split off the FCS and padding.
10. JarryShaw

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    needs: decisionWaiting on the maintainer to decide — not blocked by other workWaiting on the maintainer to decide — not blocked by other work

    on Nov 2, 2026
11. JarryShaw commented on Nov 2, 2026

    

    JarryShaw

    on Nov 2, 2026

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    Take (b) on both questions
12. JarryShaw commented on Nov 2, 2026

    

    JarryShaw

    on Nov 2, 2026

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    The owner chose (b) on both, paraphrased.

    1. Bits 16 and 17 are decoded. They are RTS retries and data retries, one octet each, and both are added to FieldType from radiotap.org's unofficial-fields table. The docstring notes that OpenBSD uses bit 16 differently.
    2. Bitmap fields decode into named flags rather than integers. This covers Flags, the Channel flags, RX/TX flags, and the MCS/VHT/HE/EHT/U-SIG known and flag bitmaps. Each flag table is a const registry with its own radiotap.org crawler. Undefined bits still round-trip.

    The branch is being reworked to match.
13. JarryShaw

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    needs: decisionWaiting on the maintainer to decide — not blocked by other workWaiting on the maintainer to decide — not blocked by other work

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14. JarryShaw commented on Nov 2, 2026

    

    JarryShaw

    on Nov 2, 2026

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    The (b)/(b) rework is done locally.

    • Retry fields: bits 16 and 17 decode, sourced from radiotap.org's unofficial-fields page.
    • Named flags: eight IntFlag registries, each with its own crawler of its radiotap.org page: Flags, ChannelFlags, RXFlags, TXFlags, MCSKnown, VHTKnown, VHTFlags and EHTKnown. Undefined bits still round-trip.

    Needs deciding. Each item has a recommendation, and the branch proceeds on it unless you say otherwise.

    1. Mixed bitmaps. MCS flags, HE data1/data2, HE-MU flags1/flags2 and U-SIG common mix value subfields with known bits, so radiotap.org doesn't define them bit by bit. (a) Keep them as integers; (b) split each into value subfields plus a known-bits flag. Recommend (a), with (b) as a follow-up if wanted.
    2. Other bit-by-bit bitmaps. A-MPDU flags, timestamp flags, L-SIG data1, S1G known, HE-MU-other-user per_user_known and VHT coding are defined bit by bit but weren't in the list above. Adding them is one crawler subclass each. Recommend adding them.
    3. Member names. Taken verbatim from radiotap.org, some are very long, e.g. TXFlags.Transmission_includes_a_pre_configured_sequence_number_that_should_not_be_changed_by_the_driver_s_TX_handlers. (a) Keep them verbatim; (b) add a name map in each crawler using Linux's short names (F_FCS, CHAN_2GHZ, …), as vendor/tcp/flags.py already maps TCP's. Recommend (b), for readability and per the TCP precedent.
    4. One generated member keeps radiotap.org's caption, "[Currently unspecified but used]", verbatim as source data. Recommend leaving it as is.
15. JarryShaw

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    needs: decisionWaiting on the maintainer to decide — not blocked by other workWaiting on the maintainer to decide — not blocked by other work

    on Nov 2, 2026
16. JarryShaw

    moved this from WIP to Needs decision in PyPCAPKiton Nov 2, 2026