Forward-merge the master-side sans-IO refactor (discovery migration + no_std
reductions, collapsed to one commit) into the next-side branch. The discovery
decision core meets next's FMP profile/LookupRequest delta here: next's four
transit-forward predicates (Leaf no-forward, Full-profile, min_mtu, tree/fallback)
are folded into the pure core planners via an extended RoutingView seam
(node_is_leaf / peer_is_full / peer_meets_mtu, new ForwardOutcome::LeafNoForward),
and next's v2 LookupRequest API delta (origin_coords removed, tlv_entries added)
is reconciled across the discovery test tree, with next's four TLV wire tests
ported into the relocated wire test module.
The master-side branch now also carries the no_std+alloc reductions (BTreeMap,
alloc::sync::Arc, backoff-reset log moved to the shell, extern crate alloc),
which come through cleanly on the pilot-only core files.
Validated: cargo fmt / clippy (-D warnings) / test --lib all green, including
next's own transit MTU-pruning integration tests driving the refactored core
through the full shell path.
Migrate the FMP discovery decision logic out of the async handlers into
synchronous, runtime-agnostic sans-IO state machines owned by the protocol
structs, with I/O pushed to the edges. Pulls the full decision surface into a
pure core (backoff, rate-limit, planners, response routing), consolidates the
tests into a per-module tree with a shared crate testutil, and injects a u64
wall-clock so the core is free of Instant and std time.
Also brings the module toward no_std+alloc: the four discovery maps use
alloc::collections::BTreeMap (HashMap's RandomState is std-only), Arc is spelled
alloc::sync::Arc, the backoff-reset log lives in the shell (the core returns the
cleared count so observability stays out of the pure core), and the crate root
names alloc directly. The one remaining tether is ProtocolError's
std::error::Error coupling in the wire codec.
First subsystem of the broader sans-IO refactor; establishes the extraction
patterns and conventions carried forward to the remaining protocols.
- Borrowed SessionDatagramRef decoder is used in the forwarding
handler so local delivery and coordinate-cache warming no longer
allocate or copy the session payload. The owned SessionDatagram is
materialized only when re-encoding for the next hop.
- Owned SessionDatagram::decode is reimplemented as Ref::decode +
into_owned, so the two decoders cannot drift.
- recvmmsg / recvmsg_x (Linux + macOS) receive loop moves each filled
slot buffer into ReceivedPacket via mem::replace instead of cloning
it; a fresh empty buffer is installed for the next syscall.
- TransportAddr is formatted directly from the SocketAddr without
going through an intermediate String.
Focused decode bench: ref 1.6 ns/op vs owned 34.7 ns/op (21.4x).
End-to-end iperf is neutral as expected for a ~30 ns saving per
packet.
Unit tests added:
- test_session_datagram_ref_decode_borrows_payload (verifies the
payload slice pointer equals the input slice's offset 35, a real
zero-copy invariant guard against accidental future to_vec)
- bench_session_datagram_decode_owned_vs_ref (ignored, run with
--ignored --nocapture)
- test_transport_addr_from_socket_addr
Replace fixed 1KB bloom filters with variable-size filters (512B-32KB)
that adapt to each node's position in the spanning tree.
Core changes:
- Internal storage: Vec<u8> → Vec<u64> for word-level operations
- Delta compression: XOR diff with word-level RLE, sequence-based
NACK protocol for full retransmit recovery
- Size conversion: fold (large→small) and duplicate (small→large)
with auto-converting merge for mixed-size filter combination
- Native-size storage: peer filters stored at advertised size for
full-resolution routing queries, converted only for outgoing filter
- Adaptive sizing: outgoing fill ratio drives step-up/step-down
between size classes with hysteresis (20%/5% thresholds)
- Filter size decoupled from FMP negotiation: announced dynamically
in filter updates, bit 7 and TLV field 1 removed from handshake
Wire format: FilterAnnounce gains flags byte (delta bit), base_seq
field, RLE-compressed payload. New FilterNack message (0x21) for
out-of-sequence delta recovery.
- Delete PROTOCOL_NAME_IK, PROTOCOL_NAME_XK and all IK/XK methods
- Remove Ik/Xk variants from NoisePattern enum
- Rename XX methods to drop xx_ prefix (sole pattern)
- Rename HandshakeMessageType variants from NoiseIKMsg1/NoiseIKMsg2
to Msg1/Msg2, add Msg3 variant (0x03) for XX 3-message flow
- Fix doc comments with correct XX message sizes and descriptions
- Fix stale SessionSetup/SessionAck handshake payload size comments
Replace the 2-message IK handshake with a 3-message XX handshake for
FMP link establishment. XX requires no prior knowledge of the peer's
static key — both identities are revealed during the handshake
(responder in msg2, initiator in msg3). This is the foundation for
the forklift upgrade that enables rolling protocol upgrades.
Changes:
- Noise XX state machine alongside IK/XK (8 unit tests)
- Protocol negotiation payload codec: format byte, packed version
min/max, 64-bit feature bitfield, TLV extensions (11 unit tests)
- FMP wire format version 0→1, msg3 header/builder, TCP stream framing
- FMP handshake switched to XX: PeerConnection 3-message flow,
handle_msg1 simplified (no identity), handle_msg2 sends msg3 and
promotes initiator, new handle_msg3 promotes responder with
restart/rekey/cross-connection detection
- Rekey handshake switched to XX with negotiation payload hash chain
fix (decrypt-and-discard in complete_rekey_msg2/msg3)
- Negotiation payload in msg2/msg3 (FMP version [1,1], features=0)
- Debug logging for handshake promotion paths
- Integration test convergence timeouts adjusted for extra round-trip
Squashed commits:
- Add Noise XX state machine alongside IK/XK
- Add protocol negotiation payload codec
- FMP wire format prep: version 1, msg3 header support
- Switch FMP handshake from Noise IK to XX
- Increase convergence timeouts for XX 3-message handshake
- Fix negotiation hash chain desync in rekey handshake
The session-layer handshake now uses the 3-message XK pattern instead
of the 2-message IK pattern, providing stronger initiator identity
hiding. The initiator static key is deferred to msg3 and encrypted
under the es+ee DH chain, so eavesdroppers cannot identify the
initiator from the handshake.
XK pattern: -> e, es (msg1) / <- e, ee + epoch (msg2) / -> s, se + epoch (msg3)
Key changes:
- Add XK handshake methods alongside existing IK methods in noise module
- Add SessionMsg3 wire format and FSP_PHASE_MSG3 (0x03) prefix
- Replace Responding state with AwaitingMsg3 in session state machine
- Rewrite session handlers: handle_session_setup defers identity to msg3,
handle_session_ack processes msg2 and sends msg3, new handle_session_msg3
completes the responder handshake and registers identity
- Link-layer (FMP) continues to use Noise IK unchanged
- Add comprehensive XK unit tests and update all integration tests
Add a new session-layer error signal that transit routers send back to
the source when a forwarded packet exceeds the next-hop transport MTU.
This complements the existing proactive path MTU discovery (min'd at
each hop) by providing immediate feedback when oversized packets are
dropped, closing the transient window before the proactive mechanism
converges.
Wire format: 36-byte payload (msg_type + flags + dest_addr + reporter +
mtu) with FSP phase=0x0 and U flag set, matching the existing
CoordsRequired/PathBroken pattern.
Changes:
- Add SessionMessageType::MtuExceeded (0x22) and MtuExceeded struct with
encode/decode methods to protocol/session.rs
- Add NodeError::MtuExceeded variant to propagate structured MTU info
from TransportError through send_encrypted_link_message()
- Catch MtuExceeded in the forwarding path and send error signal back to
the datagram source via send_mtu_exceeded_error(), rate-limited by the
existing routing_error_rate_limiter
- Handle incoming MtuExceeded at the source by calling
PathMtuState::apply_notification() for immediate MTU decrease
- Add unit tests for encode/decode roundtrip, boundary MTU values, and
too-short payload rejection
FIPS_OVERHEAD was 150 but had two bugs: the session AEAD tag (16 bytes)
was listed in the comment but missing from the arithmetic, and the
coordinate budget (~60 bytes) was undersized and didn't belong in a
constant representing fixed data path overhead.
Corrected to 106 bytes (the actual fixed overhead without coordinates).
This increases effective_ipv6_mtu from 1322 to 1366 for standard
Ethernet, well above the IPv6 minimum of 1280.
Added a guard in send_session_data() that computes the total wire size
with coordinates before committing to include them. If adding coords
would exceed the transport MTU, the CP flag is skipped and the warmup
counter is not decremented. This prevents silently producing oversized
packets at tree depth 2+.
Updated design docs (ipv6-adapter, wire-formats, mesh-operation) with
corrected overhead values.
Johnathan Corgan
Martti MalmiandJohnathan Corgan