0bf03d924d
Closes Tier 1 #5. The previous §7.2 was four bullet points naming the "answer with an announce" rule but missing every wire detail — implementation-time the SF mobile client got steps 4 (dedup) and 5 (local-destination check) wrong on its first cut and the bug only surfaced as "I can message my own destination but no one else can reply". §7.2 is now six sub-sections: §7.2.1 Path-request packet parse rules. The handler's slice recipe with branching on payload length (32B = leaf form target||tag; 48B+ = transport form target||transport_id|| tag); tag cap at 16B; tagless-request rejection. §7.2.2 Tag-based dedup via Transport.discovery_pr_tags. The unique_tag = dest_hash || tag construction, the 32000- entry cap, why missing this turns a leaf into a broadcast- storm amplifier on retransmits. §7.2.3 The five-way dispatch in Transport.path_request: local-destination / transit-knows-path / local-client- forward / discovery-recursive / drop. Branches 1 and 5 are the only ones a leaf needs. §7.2.4 Path-response announce wire format. Body byte-identical to a regular announce (§4.1); only the outer packet context byte differs (NONE → PATH_RESPONSE 0x0B). PR_TAG_WINDOW=30s body-cache that serves identical wire bytes to racing relays so transit dedup converges. §7.2.5 Timing constants: PATH_REQUEST_GRACE = 0.4s, + PATH_REQUEST_RG = 1.5s for roaming-mode interfaces. Local-destination and local-client originator branches bypass the grace. §7.2.6 Minimum responsibility for a non-transport leaf — the six-step protocol-level recipe. flows/path-discovery.md: 9-step chronology covering both single-hop leaf-owns-target and two-hop transit-relay-knows-path cases. Wire-byte ladder diagrams for both. Notes the ingress-limit bypass for path-responses (Transport.py:1632-1639), the receive_path_responses opt-in for handler dispatch (Transport.py:1989-1991), and the timeout/escalation path through LXMRouter.process_outbound's MAX_PATHLESS_TRIES retry counter. flows/README.md status table updated. 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.