wintun: add more retry loops

tun/wintun/registryhacks_windows.go

@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package wintun
+
+import (
+	"golang.org/x/sys/windows/registry"
+	"time"
+)
+
+const (
+	numRetries = 25
+	retryTimeout = 100 * time.Millisecond
+)
+
+func registryOpenKeyRetry(k registry.Key, path string, access uint32) (key registry.Key, err error) {
+	for i := 0; i < numRetries; i++ {
+		key, err = registry.OpenKey(k, path, access)
+		if err == nil {
+			break
+		}
+		if i != numRetries - 1 {
+			time.Sleep(retryTimeout)
+		}
+	}
+	return
+}
+
+func keyGetStringValueRetry(k registry.Key, name string) (val string, valtype uint32, err error) {
+	for i := 0; i < numRetries; i++ {
+		val, valtype, err = k.GetStringValue(name)
+		if err == nil {
+			break
+		}
+		if i != numRetries - 1 {
+			time.Sleep(retryTimeout)
+		}
+	}
+	return
+}