Add a Loopback variant to TransportHandle backed by an unbounded
in-process channel and a shared address-to-receiver registry, so
node-level multi-node tests deliver packets directly between nodes
instead of over real localhost UDP sockets. This removes the kernel
UDP receive-buffer overflow that dropped handshake packets when many
tests ran in parallel under CPU contention, and lets the large-network
convergence tests run reliably in the default suite again (their
parallel-load ignore markers are removed).
The new transport and its enum variant are cfg(test)-gated, so the
daemon build is unaffected.
Redesign shared-media transport framing now that XX replaces IK:
- Ethernet: unified 4-byte header [type][flags][length:2 LE] for all
frame types, effective MTU now if_mtu - 4
- Beacons: strip 32-byte pubkey (34 → 5 bytes), identity learned from
XX handshake msg2/msg3 instead of beacon
- BLE: remove pre-handshake pubkey_exchange() and cross-probe
tie-breaker, both unnecessary with XX
- Discovery: support anonymous connections (pubkey_hint: None) with
address-based dedup for shared-media transports
- Post-handshake identity hooks in handle_msg2/msg3 for self-detection
and future allow/deny list filtering (IDEA-0047)
- Promote probe connections directly into pool instead of dropping and
reconnecting. Eliminates fragile two-phase connect pattern (probe →
disconnect → reconnect) that caused race conditions on restart.
- send_async fails fast when no connection exists, triggering a
background connect_async instead of blocking the event loop for up
to 10s on inline L2CAP connect. Prevents control socket query
timeouts and MMP processing stalls.
- Add 5-second timeout to pubkey_exchange recv. Without this, a peer
that connects but never sends its pubkey blocks the calling task
forever, killing the scan_probe_loop or accept_loop entirely.
- Add retry timer in scan_probe_loop for addresses that failed probe
but won't get another DeviceAdded from BlueZ (deduplication).
- Clear BlueZ cached devices before starting scan so fresh
advertisements trigger DeviceAdded after daemon restart.
- connect_async now performs pubkey exchange before promoting to pool,
matching the accept_loop's expectation on inbound connections.
- BLE tests updated to pre-establish connections via connect_async
since send_async no longer does inline connect.
BLE transport implementation using L2CAP Connection-Oriented Channels
(SeqPacket mode) via the bluer crate, behind cfg(feature = "ble").
Core transport:
- BleTransport<I> generic over BleIo trait (BluerIo prod, MockBleIo test)
- Connection pool with priority eviction (static > discovered, max 7)
- Connect-on-send via connect_inline() matching TCP behavior
- Per-connection receive loops with pool cleanup on disconnect
Discovery and probing:
- Combined scan_probe_loop using select! over scanner events and a
BinaryHeap delay queue with per-entry random jitter (0-5s) to prevent
herd effects when multiple nodes see the same beacon simultaneously
- Pre-handshake pubkey exchange ([0x00][pubkey:32]) for IK identity
- Cross-probe tie-breaker: smaller NodeAddr's outbound wins (same
convention as FMP/FSP rekey dual-initiation)
- Probed peers reported to DiscoveryBuffer; pool fills through normal
node-layer auto-connect -> send_async -> connect_inline path
Beacon management:
- Periodic advertising: 1s burst every 30s (configurable via
beacon_interval_secs / beacon_duration_secs)
- FIPS service UUID for scan filtering
Configuration (all fields optional with defaults):
- adapter, psm, mtu, max_connections, connect_timeout_ms
- advertise, scan, auto_connect, accept_connections
- beacon_interval_secs (30), beacon_duration_secs (1)
Hardware validated with two BLE nodes:
- 2048-byte MTU, ~60-160ms RTT, zero-config auto-connect
- BLE spike tool at testing/ble/ for standalone adapter validation
42 unit tests + 4 node-level integration tests, all CI-compatible
via MockBleIo (no hardware required). tokio test-util added for
time-dependent scan/probe tests.
Johnathan Corgan