tun: windows: get rid of retry logic

Things work fine on Windows 8.

1 files changed, 9 insertions, 5 deletions

diff --git a/tun/wintun/wintun_windows.go b/tun/wintun/wintun_windows.go
index e8eadf5..88d565d 100644
--- a/tun/wintun/wintun_windows.go
+++ b/tun/wintun/wintun_windows.go
@@ -612,21 +612,25 @@ func (wintun *Wintun) deviceData() (setupapi.DevInfo, *setupapi.DevInfoData, err
 	return 0, nil, windows.ERROR_OBJECT_NOT_FOUND
 }
 
-// NdisFileName returns the Wintun NDIS device object name.
-func (wintun *Wintun) NdisFileName() (string, error) {
+// AdapterHandle returns a handle to the adapter device object.
+func (wintun *Wintun) AdapterHandle() (windows.Handle, error) {
 	key, err := registry.OpenKey(registry.LOCAL_MACHINE, wintun.netRegKeyName(), registry.QUERY_VALUE)
 	if err != nil {
-		return "", fmt.Errorf("Network-specific registry key open failed: %v", err)
+		return windows.InvalidHandle, fmt.Errorf("Network-specific registry key open failed: %v", err)
 	}
 	defer key.Close()
 
 	// Get the interface name.
 	pnpInstanceID, err := registryEx.GetStringValue(key, "PnPInstanceId")
 	if err != nil {
-		return "", fmt.Errorf("PnpInstanceId registry key read failed: %v", err)
+		return windows.InvalidHandle, fmt.Errorf("PnPInstanceId registry key read failed: %v", err)
 	}
 	mangledPnpNode := strings.ReplaceAll(fmt.Sprintf("%s\\{cac88484-7515-4c03-82e6-71a87abac361}", pnpInstanceID), "\\", "#")
-	return fmt.Sprintf("\\\\.\\Global\\%s", mangledPnpNode), nil
+	handle, err := windows.CreateFile(windows.StringToUTF16Ptr(fmt.Sprintf("\\\\.\\Global\\%s", mangledPnpNode)), windows.GENERIC_READ|windows.GENERIC_WRITE, 0, nil, windows.OPEN_EXISTING, 0, 0)
+	if err != nil {
+		return windows.InvalidHandle, fmt.Errorf("CreateFile on mangled PnPInstanceId path failed: %v", err)
+	}
+	return handle, nil
 }
 
 // GUID returns the GUID of the interface.