wintun: introduce adapter pools

This makes wintun package reusable for non-WireGuard applications.

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

tun/tun_windows.go

@@ -71,6 +71,8 @@ type NativeTun struct {
 	rate      rateJuggler
 }
 
+const WintunPool = wintun.Pool("WireGuard")
+
 //go:linkname procyield runtime.procyield
 func procyield(cycles uint32)
 
@@ -98,22 +100,20 @@ func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID) (Dev
 	var wt *wintun.Wintun
 
 	// Does an interface with this name already exist?
-	wt, err = wintun.GetInterface(ifname)
+	wt, err = WintunPool.GetInterface(ifname)
 	if err == nil {
 		// If so, we delete it, in case it has weird residual configuration.
 		_, err = wt.DeleteInterface()
 		if err != nil {
 			return nil, fmt.Errorf("Unable to delete already existing Wintun interface: %v", err)
 		}
-	} else if err == windows.ERROR_ALREADY_EXISTS {
-		return nil, fmt.Errorf("Foreign network interface with the same name exists")
 	}
-	wt, _, err = wintun.CreateInterface(requestedGUID)
+	wt, _, err = WintunPool.CreateInterface(requestedGUID)
 	if err != nil {
 		return nil, fmt.Errorf("Unable to create Wintun interface: %v", err)
 	}
 
-	err = wt.SetInterfaceName(ifname)
+	err = wt.SetInterfaceName(ifname, WintunPool)
 	if err != nil {
 		wt.DeleteInterface()
 		return nil, fmt.Errorf("Unable to set name of Wintun interface: %v", err)

tun/wintun/wintun_windows.go

@@ -21,6 +21,8 @@ import (
 	"golang.zx2c4.com/wireguard/tun/wintun/setupapi"
 )
 
+type Pool string
+
 // Wintun is a handle of a Wintun adapter.
 type Wintun struct {
 	cfgInstanceID windows.GUID
@@ -33,7 +35,6 @@ var deviceClassNetGUID = windows.GUID{Data1: 0x4d36e972, Data2: 0xe325, Data3: 0
 var deviceInterfaceNetGUID = windows.GUID{Data1: 0xcac88484, Data2: 0x7515, Data3: 0x4c03, Data4: [8]byte{0x82, 0xe6, 0x71, 0xa8, 0x7a, 0xba, 0xc3, 0x61}}
 
 const (
-	deviceTypeName         = "WireGuard Tunnel"
 	hardwareID             = "Wintun"
 	waitForRegistryTimeout = time.Second * 10
 )
@@ -94,9 +95,9 @@ func removeNumberedSuffix(ifname string) string {
 
 // GetInterface finds a Wintun interface by its name. This function returns
 // the interface if found, or windows.ERROR_OBJECT_NOT_FOUND otherwise. If
-// the interface is found but not a Wintun-class, this function returns
+// the interface is found but not a Wintun-class or a member of the pool,
-// windows.ERROR_ALREADY_EXISTS.
+// this function returns windows.ERROR_ALREADY_EXISTS.
-func GetInterface(ifname string) (*Wintun, error) {
+func (pool Pool) GetInterface(ifname string) (*Wintun, error) {
 	// Create a list of network devices.
 	devInfoList, err := setupapi.SetupDiGetClassDevsEx(&deviceClassNetGUID, "", 0, setupapi.DIGCF_PRESENT, setupapi.DevInfo(0), "")
 	if err != nil {
@@ -156,6 +157,14 @@ func GetInterface(ifname string) (*Wintun, error) {
 				}
 
 				if driverDetailData.IsCompatible(hardwareID) {
+					isMember, err := pool.isMember(devInfoList, deviceData)
+					if err != nil {
+						return nil, err
+					}
+					if !isMember {
+						return nil, windows.ERROR_ALREADY_EXISTS
+					}
+
 					return wintun, nil
 				}
 			}
@@ -175,7 +184,7 @@ func GetInterface(ifname string) (*Wintun, error) {
 // called "requested" GUID because the API it uses is completely undocumented,
 // and so there could be minor  interesting complications with its usage. This
 // function returns the network interface ID and a flag if reboot is required.
-func CreateInterface(requestedGUID *windows.GUID) (wintun *Wintun, rebootRequired bool, err error) {
+func (pool Pool) CreateInterface(requestedGUID *windows.GUID) (wintun *Wintun, rebootRequired bool, err error) {
 	// Create an empty device info set for network adapter device class.
 	devInfoList, err := setupapi.SetupDiCreateDeviceInfoListEx(&deviceClassNetGUID, 0, "")
 	if err != nil {
@@ -192,6 +201,7 @@ func CreateInterface(requestedGUID *windows.GUID) (wintun *Wintun, rebootRequire
 	}
 
 	// Create a new device info element and add it to the device info set.
+	deviceTypeName := pool.DeviceTypeName()
 	deviceData, err := devInfoList.CreateDeviceInfo(className, &deviceClassNetGUID, deviceTypeName, 0, setupapi.DICD_GENERATE_ID)
 	if err != nil {
 		err = fmt.Errorf("SetupDiCreateDeviceInfo failed: %v", err)
@@ -432,7 +442,7 @@ func (wintun *Wintun) DeleteInterface() (rebootRequired bool, err error) {
 // DeleteMatchingInterfaces deletes all Wintun interfaces, which match
 // given criteria, and returns which ones it deleted, whether a reboot
 // is required after, and which errors occurred during the process.
-func DeleteMatchingInterfaces(matches func(wintun *Wintun) bool) (deviceInstancesDeleted []uint32, rebootRequired bool, errors []error) {
+func (pool Pool) DeleteMatchingInterfaces(matches func(wintun *Wintun) bool) (deviceInstancesDeleted []uint32, rebootRequired bool, errors []error) {
 	devInfoList, err := setupapi.SetupDiGetClassDevsEx(&deviceClassNetGUID, "", 0, setupapi.DIGCF_PRESENT, setupapi.DevInfo(0), "")
 	if err != nil {
 		return nil, false, []error{fmt.Errorf("SetupDiGetClassDevsEx(%v) failed: %v", deviceClassNetGUID, err.Error())}
@@ -476,20 +486,12 @@ func DeleteMatchingInterfaces(matches func(wintun *Wintun) bool) (deviceInstance
 			continue
 		}
 
-		deviceDescVal, err := devInfoList.DeviceRegistryProperty(deviceData, setupapi.SPDRP_DEVICEDESC)
+		isMember, err := pool.isMember(devInfoList, deviceData)
 		if err != nil {
-			errors = append(errors, fmt.Errorf("DeviceRegistryPropertyString(SPDRP_DEVICEDESC) failed: %v", err))
+			errors = append(errors, err)
 			continue
 		}
-		deviceDesc, _ := deviceDescVal.(string)
+		if !isMember {
-		friendlyNameVal, err := devInfoList.DeviceRegistryProperty(deviceData, setupapi.SPDRP_FRIENDLYNAME)
-		if err != nil {
-			errors = append(errors, fmt.Errorf("DeviceRegistryPropertyString(SPDRP_FRIENDLYNAME) failed: %v", err))
-			continue
-		}
-		friendlyName, _ := friendlyNameVal.(string)
-		if friendlyName != deviceTypeName && deviceDesc != deviceTypeName &&
-			removeNumberedSuffix(friendlyName) != deviceTypeName && removeNumberedSuffix(deviceDesc) != deviceTypeName {
 			continue
 		}
 
@@ -532,12 +534,29 @@ func DeleteMatchingInterfaces(matches func(wintun *Wintun) bool) (deviceInstance
 // DeleteAllInterfaces deletes all Wintun interfaces, and returns which
 // ones it deleted, whether a reboot is required after, and which errors
 // occurred during the process.
-func DeleteAllInterfaces() (deviceInstancesDeleted []uint32, rebootRequired bool, errors []error) {
+func (pool Pool) DeleteAllInterfaces() (deviceInstancesDeleted []uint32, rebootRequired bool, errors []error) {
-	return DeleteMatchingInterfaces(func(wintun *Wintun) bool {
+	return pool.DeleteMatchingInterfaces(func(wintun *Wintun) bool {
 		return true
 	})
 }
 
+// isMember checks if SPDRP_DEVICEDESC or SPDRP_FRIENDLYNAME match device type name.
+func (pool Pool) isMember(deviceInfoSet setupapi.DevInfo, deviceInfoData *setupapi.DevInfoData) (bool, error) {
+	deviceDescVal, err := deviceInfoSet.DeviceRegistryProperty(deviceInfoData, setupapi.SPDRP_DEVICEDESC)
+	if err != nil {
+		return false, fmt.Errorf("DeviceRegistryPropertyString(SPDRP_DEVICEDESC) failed: %v", err)
+	}
+	deviceDesc, _ := deviceDescVal.(string)
+	friendlyNameVal, err := deviceInfoSet.DeviceRegistryProperty(deviceInfoData, setupapi.SPDRP_FRIENDLYNAME)
+	if err != nil {
+		return false, fmt.Errorf("DeviceRegistryPropertyString(SPDRP_FRIENDLYNAME) failed: %v", err)
+	}
+	friendlyName, _ := friendlyNameVal.(string)
+	deviceTypeName := pool.DeviceTypeName()
+	return friendlyName == deviceTypeName || deviceDesc == deviceTypeName ||
+		removeNumberedSuffix(friendlyName) == deviceTypeName || removeNumberedSuffix(deviceDesc) == deviceTypeName, nil
+}
+
 // checkReboot checks device install parameters if a system reboot is required.
 func checkReboot(deviceInfoSet setupapi.DevInfo, deviceInfoData *setupapi.DevInfoData) bool {
 	devInstallParams, err := deviceInfoSet.DeviceInstallParams(deviceInfoData)
@@ -559,13 +578,18 @@ func setQuietInstall(deviceInfoSet setupapi.DevInfo, deviceInfoData *setupapi.De
 	return deviceInfoSet.SetDeviceInstallParams(deviceInfoData, devInstallParams)
 }
 
+// DeviceTypeName returns pool-specific device type name.
+func (pool Pool) DeviceTypeName() string {
+	return fmt.Sprintf("%s Tunnel", pool)
+}
+
 // InterfaceName returns the name of the Wintun interface.
 func (wintun *Wintun) InterfaceName() (string, error) {
 	return nci.ConnectionName(&wintun.cfgInstanceID)
 }
 
 // SetInterfaceName sets name of the Wintun interface.
-func (wintun *Wintun) SetInterfaceName(ifname string) error {
+func (wintun *Wintun) SetInterfaceName(ifname string, pool Pool) error {
 	const maxSuffix = 1000
 	availableIfname := ifname
 	for i := 0; ; i++ {
@@ -608,7 +632,7 @@ func (wintun *Wintun) SetInterfaceName(ifname string) error {
 		return fmt.Errorf("Device-level registry key open failed: %v", err)
 	}
 	defer deviceRegKey.Close()
-	err = deviceRegKey.SetStringValue("FriendlyName", deviceTypeName)
+	err = deviceRegKey.SetStringValue("FriendlyName", pool.DeviceTypeName())
 	if err != nil {
 		return fmt.Errorf("SetStringValue(FriendlyName) failed: %v", err)
 	}