Reverts the wrong normative claim added in 8c4d550. The official
manual §4.6.3 documents byte 1 as ifac_flag(7) | header_type(6) |
context_flag(5) | propagation_type(4) | dest_type(3-2) | packet_type(1-0).
Upstream confirms:
- RNS/Packet.py:246 — `(self.flags & 0b01000000) >> 6` parses
header_type as a 1-bit field at position 6.
- RNS/Transport.py:1003 — `bytes([raw[0] | 0x80, raw[1]])` sets the
IFAC flag at bit 7 in Transport.transmit when ifac_identity is
attached.
The reporter on issue #4 was correct: bit 7 has always been the IFAC
indicator. The 8c4d550 paragraph telling implementations "MUST NOT
treat bit 7 as a separate flag" is removed and replaced with the
correct layout, the upstream parse masks, and the IFAC sealing snippet
showing where the bit gets set on the wire.
A spec-correction callout in §2.1 documents the prior-version mistake
so anyone who consumed the bad guidance can identify the breakage.
verify_packet_header.py gains verify_ifac_bit_position() which locks
in the bit-7-is-IFAC invariant against future regression: it asserts
header_type's parse mask covers bit 6 only, never bit 7, and that the
IFAC mask 0x80 is disjoint from the header_type mask. The existing
flag-layout cases were always correct (header_type << 6 puts it at
bit 6); only the docstring described the wrong layout.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Adds tools/ verifier scripts that exercise upstream RNS / LXMF and confirm
(or correct) the SPEC.md callouts:
- §2.3 HEADER_1→HEADER_2 conversion: verified by stubbing Transport.transmit
and seeding a multi-hop path_table entry.
- §4.3 app_data 3-element variant: producer in LXMF 0.9.6 actually emits
2 elements only (supported_functionality at LXMRouter.py:999 is dead
code); parser tolerates 1/2/3-element + raw UTF-8.
- §7.1 path? always-precedes claim: actually conditional on
not has_path() AND method==OPPORTUNISTIC.
- §7.4 ratchet ring default 8: actually Destination.RATCHET_COUNT = 512
at RNS/Destination.py:85.
Also fixes a documentation bug in §1.2: the rnstransport.path.request row
of the well-known-hash table had the dest-hash prefix where the name_hash
should be (correct name_hash is 7926bbe7dd7f9aba88b0).
Seeds test-vectors/identities.json (Alice + Bob) with a regenerator
(tools/regen_identities.py) and verifier (tools/verify_destination_hash.py)
covering §1.1 and §1.2.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
