95823ad840
Closes Tier 1 #2. Without this, a client can't send any LXMF body larger than LINK_PACKET_MAX_CONTENT ≈ 360 B, can't receive a NomadNet page that doesn't fit in one MTU, and can't transfer files via rncp. SPEC.md §10 (new): full Resource fragmentation protocol with citations to RNS/Resource.py. 13 sub-sections covering preparation pipeline (metadata prefix → optional bz2 → random_hash prefix → SHA-256 over data||random_hash → link.encrypt of the WHOLE blob → part-split into SDU-sized chunks → 4-byte map_hash hashmap with collision guard within COLLISION_GUARD_SIZE = 2*WINDOW_MAX + HASHMAP_MAX_LEN), wire context inventory (RESOURCE_ADV / RESOURCE / RESOURCE_REQ / RESOURCE_HMU / RESOURCE_PRF / RESOURCE_ICL / RESOURCE_RCL), the msgpack dict for the advertisement (t/d/n/h/r/o/i/l/q/f/m), the request payload format with the hashmap_exhausted sentinel, the lazy-hashmap RESOURCE_HMU continuation that lets large hashmaps avoid breaking small-MTU links, the proof body resource_hash(32) || full_proof = SHA256(data||hash) (32) returned in a PROOF-type packet, the sliding window dynamics (WINDOW=4 → WINDOW_MAX_FAST=75 / WINDOW_MAX_VERY_SLOW=4 with rate detection), multi-segment cutover at MAX_EFFICIENT_SIZE = 1 MiB - 1 with the lazy `__prepare_next_segment` pattern, and the encryption-before-split layering that means a missing part can't be decrypted in isolation. flows/send-resource.md: 10-step chronology from RNS.Resource() construction through advertise → req/parts loop → HMU continuation → final RESOURCE_PRF → multi-segment fan-out, with a wire-byte ladder diagram and a per-step source map. Side fixes found while drafting: - SPEC.md §2.5 contexts table was wildly incomplete and had a real bug: KEEPALIVE was listed as 0xFD; upstream is 0xFA per RNS/Packet.py:87. 0xFD is actually LINKPROOF (the regular DATA-receipt context, §6.5). Replaced with the full upstream context inventory: NONE, RESOURCE_*, CACHE_REQUEST, REQUEST, RESPONSE, PATH_RESPONSE, COMMAND, COMMAND_STATUS, CHANNEL, KEEPALIVE, LINKIDENTIFY, LINKCLOSE, LINKPROOF, LRRTT, LRPROOF. - SPEC.md §6.5 reworded: "send back a PROOF packet (no context byte specifics)" → "send back a PROOF-type packet with context = LINKPROOF (0xFD)" for clarity. - The previously-numbered §10 "Test vectors" and §11 "Source map" are renumbered to §11 / §12 so the new Resource section lands in its correct protocol-stack position. agent.md §5 audit table updated accordingly. flows/README.md status table updated; receive-resource.md added as the next pending flow. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> |
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Reticulum Specifications
Byte-level interoperability specifications for the Reticulum Network Stack and LXMF — the parts that aren't in the upstream manuals but are needed to build a working client from scratch.
Upstream Reticulum has excellent operator-facing documentation (config, deployment, design philosophy). What's missing — and what every alternative implementation has had to reverse-engineer from the Python source — is an authoritative wire-level spec: header bit layouts, msgpack field types, signature input formats, the exact behavior of Transport.outbound, and the long list of "would never guess from reading the manual" gotchas that cost hours of debugging each.
This repo collects those findings in one place. The hope is that future client authors (Kotlin, Swift, Rust, Go, embedded C — pick your stack) can read this instead of re-deriving everything from RNS/Transport.py.
Status
Early days, contributions welcome. Current content was bootstrapped from the working notes of two reverse-engineering efforts:
- The web-based Reticulum client at
reticulum-lora-webclient - The native Android client at
reticulum-mobile-app
Each finding is grounded in upstream source citations (file + line) so it can be re-verified as RNS evolves.
What's here
SPEC.md— the single combined spec document, organized by protocol layerflows/— chronological end-to-end narratives (e.g. "send a message"), cross-referencing SPEC.md sectionstools/— self-contained Python verifier scripts that test SPEC.md claims against upstream RNS / LXMFtest-vectors/— known-good byte sequences each implementation should be able to round-trip (intent: grow into a compliance suite)
As content grows, SPEC.md will be split into per-layer files (packet header, identity, announce, token-crypto, LXMF, link, resource, transport).
Scope
In scope:
- Wire formats: byte layouts, field encodings, framing
- Signing inputs and what's hashed where
- Cross-cutting behaviors required for interop (path requests, ratchet rotation, retransmit semantics)
- "Gotchas" — things upstream code does that aren't obvious from the manual or RFC-style sketches
- Test vectors that any implementation must be able to round-trip
Out of scope:
- Operator/user documentation — see the official manual
- API design choices for any specific implementation
- Networking layer config (interfaces, transport modes) — already well documented
Source citations
Where a finding cites upstream Python code, the path is relative to a standard pip install rns lxmf installation, e.g. RNS/Transport.py, LXMF/LXMF.py. Where the bundled umsgpack is referenced, the path is RNS/vendor/umsgpack.py.
When upstream code changes such that a citation no longer matches, file an issue or PR — the goal is to track the de-facto wire spec as it actually behaves, not as it was at any single snapshot.
Contributing
If you've debugged a Reticulum interop problem and the answer wasn't in the upstream docs, please add it. Format:
### N.M Short description of the finding
**Symptom:** what you observed that prompted the investigation.
**What's happening:** the actual mechanism, ideally with upstream source citation (file + line).
**Implication / fix:** what an implementation must do to interop.
**Source:** upstream file paths and approximate line numbers.
Add a worked test vector to test-vectors/ if the finding is byte-level.
License
CC BY 4.0 — use freely, attribution appreciated.