wintun: wait for interface registry key on device creation

By using RegNotifyChangeKeyValue(). Also disable dead gateway detection.

Signed-off-by: Simon Rozman <simon@rozman.si>

tun/tun_windows.go

@@ -62,35 +62,27 @@ func packetAlign(size uint32) uint32 {
 func CreateTUN(ifname string) (TUNDevice, error) {
 	var err error
 	var wt *wintun.Wintun
-	for i := 0; i < 3; i++ {
-		// Does an interface with this name already exist?
-		wt, err = wintun.GetInterface(ifname, 0)
-		if wt == nil {
-			// Interface does not exist or an error occured. Create one.
-			wt, _, err = wintun.CreateInterface("WireGuard Tunnel Adapter", 0)
-			if err != nil {
-				err = fmt.Errorf("wintun.CreateInterface: %v", err)
-				continue
-			}
-		} else if err != nil {
-			// Foreign interface with the same name found.
-			// We could create a Wintun interface under a temporary name. But, should our
-			// process die without deleting this interface first, the interface would remain
-			// orphaned.
-			err = fmt.Errorf("wintun.GetInterface: %v", err)
-			continue
-		}
 
-		err = wt.SetInterfaceName(ifname) //TODO: This is the function that most often fails
+	// Does an interface with this name already exist?
+	wt, err = wintun.GetInterface(ifname, 0)
+	if wt == nil {
+		// Interface does not exist or an error occurred. Create one.
+		wt, _, err = wintun.CreateInterface("WireGuard Tunnel Adapter", 0)
 		if err != nil {
-			wt.DeleteInterface(0)
-			wt = nil
-			err = fmt.Errorf("wintun.SetInterfaceName: %v", err)
-			continue
+			return nil, fmt.Errorf("wintun.CreateInterface: %v", err)
 		}
+	} else if err != nil {
+		// Foreign interface with the same name found.
+		// We could create a Wintun interface under a temporary name. But, should our
+		// process die without deleting this interface first, the interface would remain
+		// orphaned.
+		return nil, fmt.Errorf("wintun.GetInterface: %v", err)
 	}
+
+	err = wt.SetInterfaceName(ifname)
 	if err != nil {
-		return nil, err
+		wt.DeleteInterface(0)
+		return nil, fmt.Errorf("wintun.SetInterfaceName: %v", err)
 	}
 
 	err = wt.FlushInterface()