Add src_addr to SessionDatagram envelope (34-byte header: msg_type +
src_addr + dest_addr + hop_limit) so transit routers can route error
signals back to the packet's originator.
Reclassify CoordsRequired/PathBroken as link-layer error signals
(plaintext inside SessionDatagram) rather than e2e encrypted session
messages. Transit routers generate these when forwarding fails and
route them to src_addr; if source is also unreachable, drop silently.
Remove redundant src_addr/dest_addr/hop_limit from SessionSetup,
SessionAck, and DataPacket (now in envelope). DataPacket header
reduced from 36 to 4 bytes. Remove PathBroken.original_src.
Fix routing loop vulnerability: gate bloom filter path on having
cached dest_coords to prevent blind forwarding between peers.
Simplify select_best_candidate() to require coordinates.
Fix gossip protocol type codes (0x11->0x20, 0x12->0x30, 0x13->0x31)
for consistency across all design docs.
All 5 design docs updated and cross-checked for consistency.
335 tests pass, zero warnings.
Add the full next-hop routing algorithm to Node::find_next_hop():
- Local delivery, direct peer, bloom filter candidates, greedy tree
routing fallback, with (link_cost, tree_distance, node_addr) ordering
- select_best_candidate() scores by peer→dest distance (not us→peer)
with self-distance check to prevent routing loops
- TreeState::find_next_hop() for greedy tree routing with progress
guarantee
- ActivePeer::link_cost() placeholder (constant 1.0) for future link
quality metrics
Add routing tests including 100-node all-pairs reachability simulation
(9900/9900 delivered, 0 loops, avg 4.0 hops, max 8).
Update fips-routing.md to reflect bloom filter routing as the primary
forwarding mechanism, with greedy tree routing as fallback during
convergence windows.
Rename NodeId to NodeAddr and npub to pubkey throughout documentation
and source code for consistency with the established identity model.
Add FIPS API vs IPv6 adapter overview to session protocol document.
Add transport address terminology note to wire protocol document.
Documents the tradeoff between metadata privacy and route error feedback:
- Intermediate routers see src_addr/dest_addr (traffic analysis possible)
- Source address needed for CoordsRequired/PathBroken error messages
- Deliberate choice: explicit feedback over silent drops + app timeouts
- Partial mitigation: addresses are SHA-256(npub), not npubs themselves
- Notes onion routing as alternative with different tradeoffs
Add comprehensive wire format diagrams with byte offsets, field sizes,
and concrete examples to three protocol documents:
fips-wire-protocol.md (Appendix A):
- Encrypted frame (0x00) with plaintext structure breakdown
- Noise IK msg1/msg2 with payload breakdown
- Complete handshake flow diagram
fips-gossip-protocol.md (Appendix A):
- TreeAnnounce with ancestry entry structure and size table
- FilterAnnounce with bloom filter layout
- LookupRequest/LookupResponse with examples
- Message flow showing packet nesting
fips-session-protocol.md (§8):
- SessionSetup, SessionAck, DataPacket, CoordsRequired, PathBroken
- Full nested packet example showing link + session layers
fips-routing.md:
- Refactored Part 4 to "Route Cache Management"
- Moved wire format content to fips-session-protocol.md
Session protocol (fips-session-protocol.md):
- Clarified DNS entry point applies to IP-based apps; native FIPS uses npub
- Updated transport failover examples (UDP → WiFi, WiFi → LTE)
- Added roaming description to session independence section
- Expanded §5 with coords-on-demand mechanism for route cache recovery
- Added Noise IK vs XK privacy tradeoff note to §6
Routing (fips-routing.md):
- DataPacket now has optional coordinates (COORDS_PRESENT flag)
- Updated handle_data_packet to cache coords from packets
- Sender state machine: WARM/COLD based on CoordsRequired errors
- Updated packet type summary table
Architecture (fips-architecture.md):
- Fixed cross-references to session protocol sections
Design change: Session layer now uses Noise IK pattern (previously KK),
matching the link layer. Rationale: initiator knows destination npub,
responder learns initiator identity from handshake - same asymmetry as
link connections.
Document consistency fixes:
- Auth* events → Noise IK msg1/msg2 terminology in state machines
- PeerId → NodeId in routing code examples
- BloomUpdate → FilterAnnounce terminology
- Updated cross-references and tables
Align terminology and cross-references across all FIPS design documents
based on decisions made in fips-protocol-flow.md (Session 39).
Key changes:
- Distinguish "Routing Session" (hop-by-hop cache) from "Crypto Session"
(end-to-end Noise KK encryption) throughout all docs
- Add handshake_payload field to SessionSetup/SessionAck for combined
establishment of routing and crypto sessions
- Update fips-design.md encryption section to reference Noise KK
- Add SessionSetup (0x06), SessionAck (0x07), CoordsRequired (0x08)
message types
- Add Crypto Session Management config section to fips-architecture.md
- Add cross-references to fips-protocol-flow.md in all design docs
- Update reconciliation tracking in protocol-flow.md §7
Create fips-routing.md covering the complete routing architecture:
- Bloom filter design: 4KB filters, K=2 scope, event-driven updates
- Discovery protocol: LookupRequest/Response with signed proofs
- Greedy tree routing using coordinates from discovery
- Session establishment model for minimal data packet overhead
- Router coordinate caching with LRU eviction
Key design decisions:
- Leaf-only mode for constrained devices (single peer handles routing)
- Separation of discovery (find destination) from routing (deliver packets)
- Session setup pays coordinate cost once; data packets carry only addresses
- 36-byte data packet header comparable to IPv6
Update design docs README to include new document.
Johnathan Corgan