From 9b22255cadab050a1788d02917907b7a67e4d358 Mon Sep 17 00:00:00 2001
From: Simon Rozman <simon@rozman.si>
Date: Thu, 7 Mar 2019 15:34:34 +0100
Subject: [PATCH] wintun: Refactor network registry key name generation

Signed-off-by: Simon Rozman <simon@rozman.si>
---
 tun/wintun/wintun_windows.go | 40 ++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/tun/wintun/wintun_windows.go b/tun/wintun/wintun_windows.go
index 69fd30c..ab865a9 100644
--- a/tun/wintun/wintun_windows.go
+++ b/tun/wintun/wintun_windows.go
@@ -229,7 +229,7 @@ func CreateInterface(description string, hwndParent uintptr) (*Wintun, bool, err
 	// Install interfaces if any.
 	devInfoList.CallClassInstaller(setupapi.DIF_INSTALLINTERFACES, deviceData)
 
-	var ifid *windows.GUID
+	var wintun *Wintun
 	var rebootRequired bool
 
 	// Install the device.
@@ -240,10 +240,10 @@ func CreateInterface(description string, hwndParent uintptr) (*Wintun, bool, err
 			rebootRequired = true
 		}
 
-		// Get network interface ID from registry. DIF_INSTALLDEVICE returns almost immediately,
-		// while the device installation continues in the background. It might take a while, before
-		// all registry keys and values are populated.
-		getInterfaceID := func() (*windows.GUID, error) {
+		// Get network interface. DIF_INSTALLDEVICE returns almost immediately, while the device
+		// installation continues in the background. It might take a while, before all registry
+		// keys and values are populated.
+		getInterface := func() (*Wintun, error) {
 			// Open HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\<class>\<id> registry key.
 			keyDev, err := devInfoList.OpenDevRegKey(deviceData, setupapi.DICS_FLAG_GLOBAL, 0, setupapi.DIREG_DRV, registry.READ)
 			if err != nil {
@@ -267,7 +267,8 @@ func CreateInterface(description string, hwndParent uintptr) (*Wintun, bool, err
 				return nil, fmt.Errorf("NetCfgInstanceId registry value is not a GUID (expected: \"{...}\", provided: \"%v\")", value)
 			}
 
-			keyNetName := fmt.Sprintf("SYSTEM\\CurrentControlSet\\Control\\Network\\%v\\%v\\Connection", guid.ToString(&deviceClassNetGUID), value)
+			wintun := (*Wintun)(ifid)
+			keyNetName := wintun.GetNetRegKeyName()
 			keyNet, err := registry.OpenKey(registry.LOCAL_MACHINE, keyNetName, registry.QUERY_VALUE)
 			if err != nil {
 				if errWin, ok := err.(syscall.Errno); ok && errWin == windows.ERROR_FILE_NOT_FOUND {
@@ -293,11 +294,11 @@ func CreateInterface(description string, hwndParent uintptr) (*Wintun, bool, err
 				return nil, fmt.Errorf("Interface name registry value is not REG_SZ or REG_EXPAND_SZ (expected: %v or %v, provided: %v)", registry.SZ, registry.EXPAND_SZ, valueType)
 			}
 
-			// TUN interface is ready. (As far as we need it.)
-			return ifid, nil
+			// TUN interface is ready. (As much as we need it.)
+			return wintun, nil
 		}
 		for numAttempts := 0; numAttempts < 30; numAttempts++ {
-			ifid, err = getInterfaceID()
+			wintun, err = getInterface()
 			if err != nil {
 				if errWin, ok := err.(syscall.Errno); ok && errWin == windows.ERROR_FILE_NOT_FOUND {
 					// Wait and retry. TODO: Wait for a cancellable event instead.
@@ -311,7 +312,7 @@ func CreateInterface(description string, hwndParent uintptr) (*Wintun, bool, err
 	}
 
 	if err == nil {
-		return (*Wintun)(ifid), rebootRequired, nil
+		return wintun, rebootRequired, nil
 	}
 
 	// The interface failed to install, or the interface ID was unobtainable. Clean-up.
@@ -432,9 +433,9 @@ func checkReboot(deviceInfoSet setupapi.DevInfo, deviceInfoData *setupapi.DevInf
 // GetInterfaceName returns network interface name.
 //
 func (wintun *Wintun) GetInterfaceName() (string, error) {
-	key, err := wintun.openNetRegKey(registry.QUERY_VALUE)
+	key, err := registry.OpenKey(registry.LOCAL_MACHINE, wintun.GetNetRegKeyName(), registry.QUERY_VALUE)
 	if err != nil {
-		return "", err
+		return "", errors.New("Network-specific registry key open failed: " + err.Error())
 	}
 	defer key.Close()
 
@@ -446,9 +447,9 @@ func (wintun *Wintun) GetInterfaceName() (string, error) {
 // SetInterfaceName sets network interface name.
 //
 func (wintun *Wintun) SetInterfaceName(ifname string) error {
-	key, err := wintun.openNetRegKey(registry.SET_VALUE)
+	key, err := registry.OpenKey(registry.LOCAL_MACHINE, wintun.GetNetRegKeyName(), registry.SET_VALUE)
 	if err != nil {
-		return err
+		return errors.New("Network-specific registry key open failed: " + err.Error())
 	}
 	defer key.Close()
 
@@ -457,16 +458,11 @@ func (wintun *Wintun) SetInterfaceName(ifname string) error {
 }
 
 //
-// openNetRegKey opens interface-specific network registry key.
+// GetNetRegKeyName returns interface-specific network registry key name.
 //
-func (wintun *Wintun) openNetRegKey(access uint32) (registry.Key, error) {
+func (wintun *Wintun) GetNetRegKeyName() string {
 	ifid := (*windows.GUID)(wintun)
-	key, err := registry.OpenKey(registry.LOCAL_MACHINE, fmt.Sprintf("SYSTEM\\CurrentControlSet\\Control\\Network\\%v\\%v\\Connection", guid.ToString(&deviceClassNetGUID), guid.ToString(ifid)), access)
-	if err != nil {
-		return 0, errors.New("Network-specific registry key open failed: " + err.Error())
-	}
-
-	return key, nil
+	return fmt.Sprintf("SYSTEM\\CurrentControlSet\\Control\\Network\\%v\\%v\\Connection", guid.ToString(&deviceClassNetGUID), guid.ToString(ifid))
 }
 
 //