WireGuard: Improve config error handling; Prevent panic in case of errors during server initialization (#4566)

https://github.com/XTLS/Xray-core/pull/4566#issuecomment-2764779273

proxy/wireguard/server_test.go

@@ -0,0 +1,52 @@
+package wireguard_test
+
+import (
+	"context"
+	"github.com/stretchr/testify/assert"
+	"runtime/debug"
+	"testing"
+
+	"github.com/xtls/xray-core/core"
+	"github.com/xtls/xray-core/proxy/wireguard"
+)
+
+// TestWireGuardServerInitializationError verifies that an error during TUN initialization
+// (triggered by an empty SecretKey) in the WireGuard server does not cause a panic and returns an error instead.
+func TestWireGuardServerInitializationError(t *testing.T) {
+	// Create a minimal core instance with default features
+	config := &core.Config{}
+	instance, err := core.New(config)
+	if err != nil {
+		t.Fatalf("Failed to create core instance: %v", err)
+	}
+	// Set the Xray instance in the context
+	ctx := context.WithValue(context.Background(), core.XrayKey(1), instance)
+
+	// Define the server configuration with an empty SecretKey to trigger error
+	conf := &wireguard.DeviceConfig{
+		IsClient:  false,
+		Endpoint:  []string{"10.0.0.1/32"},
+		Mtu:       1420,
+		SecretKey: "", // Empty SecretKey to trigger error
+		Peers: []*wireguard.PeerConfig{
+			{
+				PublicKey:  "some_public_key",
+				AllowedIps: []string{"10.0.0.2/32"},
+			},
+		},
+	}
+
+	// Use defer to catch any panic and fail the test explicitly
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("TUN initialization panicked: %v", r)
+			debug.PrintStack()
+		}
+	}()
+
+	// Attempt to initialize the WireGuard server
+	_, err = wireguard.NewServer(ctx, conf)
+
+	// Check that an error is returned
+	assert.ErrorContains(t, err, "failed to set private_key: hex string does not fit the slice")
+}