fix(huddle): rewrite localhost LiveKit URLs using relay host#319
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tlongwell-block wants to merge 3 commits intomainfrom
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fix(huddle): rewrite localhost LiveKit URLs using relay host#319tlongwell-block wants to merge 3 commits intomainfrom
tlongwell-block wants to merge 3 commits intomainfrom
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In multi-machine dev setups, the relay hands back its configured LIVEKIT_URL verbatim (typically ws://localhost:7880). A second machine joining the huddle can't reach localhost — it's a different host. The desktop client already knows a reachable relay host (from SPROUT_RELAY_URL). Before connecting to LiveKit, if the LiveKit URL points to localhost/127.0.0.1 and the relay URL doesn't, swap the hostname. No-op when both are localhost (single-machine dev) or when neither is localhost (production).
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WKWebView's networking bypasses Cloudflare WARP, so the browser can't
reach external WebSocket servers behind corporate VPN. The Rust process
IS covered by WARP.
Adds a local WS proxy (ws_proxy.rs, 156 lines) that:
- Binds TcpListener on 127.0.0.1:0 (random port, localhost only)
- Accepts WebSocket from webview via accept_hdr_async
- Captures path+query from the upgrade request (/rtc/v1?access_token=...)
- Connects upstream via tokio-tungstenite (goes through WARP)
- Bidirectional relay via futures-util forward()
Safety:
- wss:// scheme validation (no arbitrary protocol SSRF)
- Mutex-protected init (no TOCTOU race)
- Rejects upstream URL changes after first init (no cross-session routing)
- Semaphore-capped at 16 concurrent connections
- No production unwrap()s (poisoned mutex recovery)
Frontend: getProxiedLivekitUrl() starts the proxy for remote relays,
rewrites LiveKit URL to ws://127.0.0.1:{port}. Local dev (relay on
localhost) connects directly — no proxy needed.
Zero new crate dependencies (tokio-tungstenite + futures-util already
in Cargo.lock via tauri-plugin-websocket).
Codex review: 6/10 round 2 (up from 4/10). Remaining concern is that
wss:// validation doesn't fully close SSRF — acceptable because the
upstream URL comes from the relay token response (server-controlled),
not user input.
WebRTC signaling works through our WS proxy, but the browser can't reach LiveKit's ICE candidates (pod internal IPs) for media. The browser's WebRTC stack bypasses WARP. When connecting to a remote relay (not localhost), set iceTransportPolicy=relay in the RTCConfiguration. This forces the browser to use ONLY TURN relay candidates — no direct ICE connections. Critical: do NOT override iceServers. LiveKit's join response includes the TURN server URL with time-limited HMAC credentials. Overriding iceServers would strip those credentials and break TURN allocation. We only set the transport policy and let LiveKit handle the rest. Local dev (relay on localhost) skips both the proxy and relay mode — direct connections work fine on the same machine.
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Problem
In multi-machine dev setups (e.g. two humans testing huddles), the relay hands back its configured
LIVEKIT_URLverbatim in the token response — typicallyws://localhost:7880. The second machine tries to connect to LiveKit onlocalhost, which is its own machine where no LiveKit server is running. Result:WebSocket connection failed: Could not connect to the server.Fix
Before connecting to LiveKit, the desktop client checks if the LiveKit URL points to
localhostor127.0.0.1. If so, and the relay URL (SPROUT_RELAY_URL) points to a real host, it swaps the hostname. The relay URL is the one thing every client has that is guaranteed reachable — they are already talking to it.Behavior matrix:
ws://localhost:3000ws://localhost:7880ws://10.0.0.201:3000ws://localhost:7880ws://10.0.0.201:7880wss://relay.example.comwss://livekit.example.comNo server-side changes. No config changes needed. Just works.
Testing
Tested with two machines on the same LAN — second machine can now join huddles without any
.envchanges on the relay side.