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Add a relay tunnel WebSocket bridge to proxy binary frames to the Gerbil TCP relay and wire it into the WS upgrade flow. Introduce tcp_relay_port (default 4430) in the config schema. Add relayEndpointWss and relayPort to OLM token responses and relay messages (helpers added to build the WSS relay endpoint). Implement relayTunnelBridge.ts to validate OLM tokens, resolve Gerbil targets, frame/parse length-prefixed packets, connect to Gerbil over TCP, and forward framed binary data between WebSocket and TCP. Integrate the upgrade handler into the existing ws upgrade path (ws.ts). Files changed: server/lib/readConfigFile.ts, server/routers/olm/getOlmToken.ts, server/routers/olm/handleOlmRelayMessage.ts, server/routers/ws/ws.ts and new server/routers/ws/relayTunnelBridge.ts.
Refactor the configuration schema to include an optional wss_relay_port with a default value of 4430. Update the relayTunnelBridge to use wss_relay_port for connection targeting, ensuring proper fallback handling. This change enhances the WebSocket relay functionality and improves configuration flexibility.
nicholasliverett
requested review from
miloschwartz and
oschwartz10612
as code owners
This was referenced Apr 11, 2026
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What does this PR do?
You can read about the discussion related to this topic here: Transport flexiblity
As discussed, in more restrictive networks UDP connections may be completely blocked and clients are unable to connect to resources. To get around this we use a commonly allowed protocol: HTTPS, or more specifically websockets.
Description
OLM will try its normal direct UDP/hole punch and UDP relay. If OLM receives a relayEndpointWss (sent with relay info) it starts an 8s timer. Once that timer is up it switches from the shared UDP bind to a websocket bind. Traffic then flows OLM-(wss)->Pangolin-(tcp relay port)->Gerbil->Newt. Now since we are using a websocket the RTT is more than just raw wireguard, and it might be something to look into.
Note: the only thing changed is olm's connection to the gerbil relay, to newt nothing changes.
How to test?
Setup Pangolin, Gerbil, and Olm from companion PRs mentioned below and regular newt. Have to spin up pangolin, gerbil, newt, and olm to test this. Ideally checking, regular connections, restricted networks, and the force relay flag
Companion PRs
Gerbil: fosrl/gerbil#77
Olm: fosrl/olm#112