Adds real callback setter for PSK on ready

client/internal/engine.go

@@ -577,8 +577,9 @@ func (e *Engine) Start(netbirdConfig *mgmProto.NetbirdConfig, mgmtURL *url.URL)
 
 	if pqkem.Enabled() {
 		log.Infof("ML-KEM post-quantum exchange enabled")
-		// TODO(NET-1406): wire the real tunnel-UDP transport + WG PSK callback handler.
+		// TODO(NET-1406): replace noopPQTransport with the real dedicated UDP transport
-		e.pqkemManager = pqkem.NewManager(publicKey.String(), noopPQTransport{}, noopPQCallbackHandler{}, nil)
+		// bound on the WG overlay IPv4.
+		e.pqkemManager = pqkem.NewManager(publicKey.String(), noopPQTransport{}, pqCallbackHandler{wg: e.wgInterface}, nil)
 	}
 	e.stateManager.Start()
 

client/internal/pqkem_adapter.go

@@ -1,23 +1,41 @@
 package internal
 
-import "github.com/netbirdio/netbird/client/internal/pqkem"
+import (
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 
-// No-op adapters wiring the engine to the ML-KEM manager's two seams. They are
+	"github.com/netbirdio/netbird/client/internal/pqkem"
-// placeholders so the manager can be instantiated and its lifecycle managed while
+)
-// the real integration is built.
-//
-// TODO(NET-1406):
-//   - noopPQTransport -> real tunnel-UDP transport (send over the WG data path,
-//     feed inbound to Manager.OnDataPathMessage), analogue of go-rosenpass's Conn.
-//   - noopPQCallbackHandler -> program the derived PSK via iface/wgctrl on
-//     OnNewPSKReady, and tear the peer down / trigger ICE reconnect on OnRekeyFailed.
 
+// pqPresharedKeySetter is the subset of the WireGuard interface the ML-KEM callback
+// needs: programming a peer's preshared key. *iface.WGIface satisfies it.
+type pqPresharedKeySetter interface {
+	SetPresharedKey(peerKey string, psk wgtypes.Key, updateOnly bool) error
+}
+
+// pqCallbackHandler programs the derived PQ PSK onto the WireGuard peer. It is the
+// engine-side implementation of pqkem.CallbackHandler.
+type pqCallbackHandler struct {
+	wg pqPresharedKeySetter
+}
+
+// OnNewPSKReady programs the freshly derived PSK for the peer (updateOnly: a no-op
+// if the peer is not present, mirroring Rosenpass). remoteID is the peer's WG pubkey.
+func (h pqCallbackHandler) OnNewPSKReady(remoteID string, psk pqkem.PSK) error {
+	return h.wg.SetPresharedKey(remoteID, wgtypes.Key(psk), true)
+}
+
+// OnRekeyFailed reports a failed PQ (re)key convergence.
+// TODO(NET-1406): tear the peer connection down / trigger ICE reconnect.
+func (h pqCallbackHandler) OnRekeyFailed(remoteID string) error {
+	log.Warnf("pqkem: post-quantum rekey failed for peer %s", remoteID)
+	return nil
+}
+
+// noopPQTransport is a placeholder data-path transport for the ML-KEM manager.
+// TODO(NET-1406): replace with the real dedicated UDP transport bound on the WG
+// overlay IPv4 (send over the data path, feed inbound to Manager.OnDataPathMessage),
+// analogue of go-rosenpass's Conn.
 type noopPQTransport struct{}
 
 func (noopPQTransport) SendDataPath(remoteID string, msg []byte) error { return nil }
-
-type noopPQCallbackHandler struct{}
-
-func (noopPQCallbackHandler) OnNewPSKReady(remoteID string, psk pqkem.PSK) error { return nil }
-
-func (noopPQCallbackHandler) OnRekeyFailed(remoteID string) error { return nil }