wintun: Introduce new package for obscuring Windows bits

tun/wintun/guid/guid_windows.go

@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package guid
+
+import (
+	"fmt"
+	"syscall"
+
+	"golang.org/x/sys/windows"
+)
+
+//sys	clsidFromString(lpsz *uint16, pclsid *windows.GUID) (hr int32) = ole32.CLSIDFromString
+
+//
+// FromString parses "{XXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}" string to GUID.
+//
+func FromString(str string) (*windows.GUID, error) {
+	strUTF16, err := syscall.UTF16PtrFromString(str)
+	if err != nil {
+		return nil, err
+	}
+
+	guid := &windows.GUID{}
+
+	hr := clsidFromString(strUTF16, guid)
+	if hr < 0 {
+		return nil, syscall.Errno(hr)
+	}
+
+	return guid, nil
+}
+
+//
+// ToString function converts GUID to string
+// "{XXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}".
+//
+// The resulting string is uppercase.
+//
+func ToString(guid *windows.GUID) string {
+	return fmt.Sprintf("{%06X-%04X-%04X-%04X-%012X}", guid.Data1, guid.Data2, guid.Data3, guid.Data4[:2], guid.Data4[2:])
+}