Previously, because UDP is connectionless, when a pure WireGuard tunnel
encountered handshake or rekey failures (e.g. boringtun logging
`WARN HANDSHAKE(REKEY_TIMEOUT)` and `CONNECTION_EXPIRED`), the
`WireguardLink` never closed. It remained active in `agent.links` and
as a direct hop in `RelayHub.raw`. Consequently, outgoing packets
continued to be blackholed over the dead direct path, preventing
`RelayHub` from using working multihop relay routes and preventing
the agent from falling back to alternative protocols (`tcp-tls` or
`wg-quic`).
Key changes:
- In `crates/tsunagi-wireguard/src/device.rs`:
- In `FlowTunnel`, track active handshake and rekey attempts via
`handshake_started_at`. If an active handshake attempt remains
unanswered beyond `HANDSHAKE_TIMEOUT` (15s) or boringtun reports
`ConnectionExpired`, declare the tunnel dead.
- Reset timeout timers upon successful handshake reception in
`decapsulate`.
- In `drive_timers`, when tunnel failure is detected, trigger
`inner.on_tunnel_failed(peer)`, which closes the direct transport
link and notifies the agent via `PluginContext::report_peer_protocol_failure`.
- In `crates/tsunagi-wireguard/src/transport.rs`:
- Add `WireguardLink::close` to transition `is_closed` to true and
notify `closed_notify`.
- In `WireguardLink::recv`, select on `closed_notify` so readers
unblock and return `None` immediately on close.
- Add `WireguardTransport::close_link` to close active links by
network and peer.
- In `crates/tsunagi/src/dataplane/mod.rs`:
- Add `PluginRequest::ProtocolFailure` and public helper
`PluginContext::report_peer_protocol_failure`.
- In `crates/tsunagi/src/agent/mod.rs` and `crates/tsunagi/src/agent/network.rs`:
- Add `NetCommand::ProtocolFailure` to runtime command handling.
- On protocol failure: remove dead direct link from `self.links`,
clear it from `RelayHub.raw` (so `RelayHub` immediately routes
over available multihop relays), record failure on `wg` for that
peer with exponential backoff cooldown, emit `DataLinkDown`, and
immediately call `ensure_links()` to dial the next mutually supported
protocol (`tcp-tls` or `wg-quic`).
- Tests:
- Add `test_flow_tunnel_rekey_timeout_triggers_failure` and
`test_flow_tunnel_reset_on_handshake` unit tests in `device.rs`.
- Add `test_wireguard_link_close_and_transport_close_link` in
`transport_tests.rs`.
- Add `test_protocol_dial_state_cooldown_and_fallback_selection` in
`network.rs`.
Validation on Linux:
- cargo fmt --all -- --check passed.
- cargo clippy --locked --workspace --all-targets -- -D warnings passed.
- cargo test --locked --workspace --all-targets passed (350+ tests passed).
- Built release binary: target/release/tsunagi.
Aleksandr Bogomiakov
3930dff2dc