ml_wg_mgr: don't pre-install unvalidated peer endpoints — DERP until DISCO validates - #21
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…DISCO validates At peer-add, the peer's advertised endpoints[0] from the MapResponse was installed as the WireGuard endpoint before any path validation, and wireguardif's output path treats any non-zero endpoint as a working direct path. For a CGNAT peer (e.g. cellular hotspot) that address is unreachable, so the tunnel went one-way: inbound arrived via DERP while every outbound data packet was sent direct-UDP into a black hole. Tailscale semantics: data flows via DERP until a direct path is validated by a DISCO pong. Leave the endpoint blank at peer-add; the only endpoint installs are the already-gated ones (process_disco_pong on a direct pong, and the handshake path gated on best_ip). Same-LAN peers still upgrade to direct within seconds. Verified on ESP32-S3 (ESP-IDF v5.3): a CGNAT peer that previously could never reach a TCP service on the node (ping timeout, connect fail) gets ping replies over DERP, TCP connects, and bulk transfers complete. Same-LAN direct path unaffected. Fixes CamM2325#18
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Absorb upstream #21: don't pre-install unvalidated peer endpoints
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Fixes #18.
At peer-add, the peer's advertised
endpoints[0]from the MapResponse was installed as the WireGuard endpoint before any path validation, andwireguardif's output path treats any non-zero endpoint as a working direct path. For a CGNAT peer (cellular hotspot) that address is unreachable — no hole was ever punched — so the tunnel went one-way: inbound arrived via DERP while every outbound data packet went direct-UDP into a black hole (device trace: inboundvia_derp=1, DERP TX carried zerohdr=04data frames).Fix follows Tailscale's own semantics — data via DERP until a direct path is validated by a DISCO pong: leave the endpoint blank at peer-add. The only endpoint installs are now the already-correctly-gated ones (
process_disco_pongon a direct pong, and the handshake path gated onbest_ip). Same-LAN peers still upgrade to direct within seconds because the direct pong validates immediately.Verified on hardware (ESP32-S3 N16R8, ESP-IDF v5.3): a CGNAT peer that previously could never reach a TCP service on the node (ping timeout, connect fail, despite the node showing active) gets ping replies over DERP, TCP connects, and bulk transfers complete end-to-end. Same-LAN direct path validated unaffected the same day. CRLF line endings preserved.