Builds on Phase 1's SignalMessage::Reflect to probe N relays in
parallel through transient QUIC connections and classify the
client's NAT type for the future P2P hole-punching path. No wire
protocol changes — Phase 1's Reflect/ReflectResponse pair is
reused unchanged.
New client-side module (crates/wzp-client/src/reflect.rs):
- probe_reflect_addr(relay, timeout_ms): opens a throwaway
quinn::Endpoint (fresh ephemeral source port per probe,
essential for NAT-type detection — sharing one endpoint would
make a symmetric NAT look like a cone NAT), connects to _signal,
sends RegisterPresence with zero identity, consumes the Ack,
sends Reflect, awaits ReflectResponse, cleanly closes.
- detect_nat_type(relays, timeout_ms): parallel probes via
tokio::task::JoinSet (bounded by slowest probe not sum) and
returns a NatDetection with per-probe results + aggregate
classification.
- classify_nat(probes): pure-function classifier split out for
network-free unit tests. Rules:
* 0-1 successful probes → Unknown
* 2+ successes, same ip same port → Cone (P2P viable)
* 2+ successes, same ip diff ports → SymmetricPort (relay)
* 2+ successes, different ips → Multiple (treat as
symmetric)
Tauri command (desktop/src-tauri/src/lib.rs):
- detect_nat_type({ relays: [{ name, address }] }) -> NatDetection
as JSON. Takes the relay list from JS because localStorage
owns the config. Parse-up-front so a malformed entry fails
clean instead of as a probe error. 1500ms per-probe timeout.
UI (desktop/index.html + src/main.ts):
- New "NAT type" row + "Detect NAT" button in the Network
settings section. Renders per-probe status (name, address,
observed addr, latency, or error) plus the colored verdict:
* green Cone — shows consensus addr
* amber SymmetricPort / Multiple — must relay
* gray Unknown — not enough data
Tests:
- 7 unit tests in wzp-client/src/reflect.rs covering every
classifier branch (empty, 1 success, 2 identical, 2 diff ports,
2 diff ips, success+failure mix, pure-failure).
- 3 integration tests in crates/wzp-relay/tests/multi_reflect.rs:
* probe_reflect_addr_happy_path — single mock relay end-to-end
* detect_nat_type_two_loopback_relays_is_cone — two concurrent
relays, asserts both see 127.0.0.1 and classifier returns
Cone or SymmetricPort (accepted because the test harness
uses fresh ephemeral ports per probe which look like
SymmetricPort on single-host loopback)
* detect_nat_type_dead_relay_is_unknown — alive + dead port
mix, asserts the dead probe surfaces an error string and
the aggregator returns Unknown (only 1 success)
Full workspace test goes from 386 → 396 passing.
PRD: .taskmaster/docs/prd_multi_relay_reflect.txt
Tasks: 47-52 all completed
Next up: hole-punching (Phase 3) — use the reflected address in
DirectCallOffer/Answer and CallSetup so peers attempt a direct
QUIC handshake to each other, with relay fallback on timeout.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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