]> git.ipfire.org Git - thirdparty/wireguard-go.git/commitdiff
wintun: wait for interface registry key on device creation
authorSimon Rozman <simon@rozman.si>
Thu, 9 May 2019 08:11:15 +0000 (10:11 +0200)
committerJason A. Donenfeld <Jason@zx2c4.com>
Fri, 10 May 2019 14:43:58 +0000 (16:43 +0200)
By using RegNotifyChangeKeyValue(). Also disable dead gateway detection.

Signed-off-by: Simon Rozman <simon@rozman.si>
tun/tun_windows.go
tun/wintun/registry/mksyscall.go [new file with mode: 0644]
tun/wintun/registry/registry_windows.go [new file with mode: 0644]
tun/wintun/registry/registry_windows_test.go [new file with mode: 0644]
tun/wintun/registry/zregistry_windows.go [new file with mode: 0644]
tun/wintun/registryhacks_windows.go [deleted file]
tun/wintun/wintun_windows.go

index b319c2723946b8ff8668b20b4abff615315e2263..8218fc3645e3500deffe9b0f8cb5731aa451acea 100644 (file)
@@ -62,35 +62,27 @@ func packetAlign(size uint32) uint32 {
 func CreateTUN(ifname string) (TUNDevice, error) {
        var err error
        var wt *wintun.Wintun
-       for i := 0; i < 3; i++ {
-               // Does an interface with this name already exist?
-               wt, err = wintun.GetInterface(ifname, 0)
-               if wt == nil {
-                       // Interface does not exist or an error occured. Create one.
-                       wt, _, err = wintun.CreateInterface("WireGuard Tunnel Adapter", 0)
-                       if err != nil {
-                               err = fmt.Errorf("wintun.CreateInterface: %v", err)
-                               continue
-                       }
-               } else if err != nil {
-                       // Foreign interface with the same name found.
-                       // We could create a Wintun interface under a temporary name. But, should our
-                       // process die without deleting this interface first, the interface would remain
-                       // orphaned.
-                       err = fmt.Errorf("wintun.GetInterface: %v", err)
-                       continue
-               }
 
-               err = wt.SetInterfaceName(ifname) //TODO: This is the function that most often fails
+       // Does an interface with this name already exist?
+       wt, err = wintun.GetInterface(ifname, 0)
+       if wt == nil {
+               // Interface does not exist or an error occurred. Create one.
+               wt, _, err = wintun.CreateInterface("WireGuard Tunnel Adapter", 0)
                if err != nil {
-                       wt.DeleteInterface(0)
-                       wt = nil
-                       err = fmt.Errorf("wintun.SetInterfaceName: %v", err)
-                       continue
+                       return nil, fmt.Errorf("wintun.CreateInterface: %v", err)
                }
+       } else if err != nil {
+               // Foreign interface with the same name found.
+               // We could create a Wintun interface under a temporary name. But, should our
+               // process die without deleting this interface first, the interface would remain
+               // orphaned.
+               return nil, fmt.Errorf("wintun.GetInterface: %v", err)
        }
+
+       err = wt.SetInterfaceName(ifname)
        if err != nil {
-               return nil, err
+               wt.DeleteInterface(0)
+               return nil, fmt.Errorf("wintun.SetInterfaceName: %v", err)
        }
 
        err = wt.FlushInterface()
diff --git a/tun/wintun/registry/mksyscall.go b/tun/wintun/registry/mksyscall.go
new file mode 100644 (file)
index 0000000..d0cac6c
--- /dev/null
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package registry
+
+//go:generate go run $GOROOT/src/syscall/mksyscall_windows.go -output zregistry_windows.go registry_windows.go
diff --git a/tun/wintun/registry/registry_windows.go b/tun/wintun/registry/registry_windows.go
new file mode 100644 (file)
index 0000000..65da6bf
--- /dev/null
@@ -0,0 +1,240 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package registry
+
+import (
+       "errors"
+       "fmt"
+       "runtime"
+       "strings"
+       "time"
+
+       "golang.org/x/sys/windows"
+       "golang.org/x/sys/windows/registry"
+)
+
+const (
+       KEY_NOTIFY uint32 = 0x0010 // should be defined upstream as registry.KEY_NOTIFY
+)
+
+const (
+       // REG_NOTIFY_CHANGE_NAME notifies the caller if a subkey is added or deleted.
+       REG_NOTIFY_CHANGE_NAME uint32 = 0x00000001
+
+       // REG_NOTIFY_CHANGE_ATTRIBUTES notifies the caller of changes to the attributes of the key, such as the security descriptor information.
+       REG_NOTIFY_CHANGE_ATTRIBUTES uint32 = 0x00000002
+
+       // REG_NOTIFY_CHANGE_LAST_SET notifies the caller of changes to a value of the key. This can include adding or deleting a value, or changing an existing value.
+       REG_NOTIFY_CHANGE_LAST_SET uint32 = 0x00000004
+
+       // REG_NOTIFY_CHANGE_SECURITY notifies the caller of changes to the security descriptor of the key.
+       REG_NOTIFY_CHANGE_SECURITY uint32 = 0x00000008
+
+       // REG_NOTIFY_THREAD_AGNOSTIC indicates that the lifetime of the registration must not be tied to the lifetime of the thread issuing the RegNotifyChangeKeyValue call. Note: This flag value is only supported in Windows 8 and later.
+       REG_NOTIFY_THREAD_AGNOSTIC uint32 = 0x10000000
+)
+
+//sys  regNotifyChangeKeyValue(key windows.Handle, watchSubtree bool, notifyFilter uint32, event windows.Handle, asynchronous bool) (regerrno error) = advapi32.RegNotifyChangeKeyValue
+
+func OpenKeyWait(k registry.Key, path string, access uint32, timeout time.Duration) (registry.Key, error) {
+       runtime.LockOSThread()
+       defer runtime.UnlockOSThread()
+
+       deadline := time.Now().Add(timeout)
+       pathSpl := strings.Split(path, "\\")
+       for i := 0; ; i++ {
+               keyName := pathSpl[i]
+               isLast := i+1 == len(pathSpl)
+
+               event, err := windows.CreateEvent(nil, 0, 0, nil)
+               if err != nil {
+                       return 0, fmt.Errorf("Error creating event: %v", err)
+               }
+               defer windows.CloseHandle(event)
+
+               var key registry.Key
+               for {
+                       err = regNotifyChangeKeyValue(windows.Handle(k), false, REG_NOTIFY_CHANGE_NAME, windows.Handle(event), true)
+                       if err != nil {
+                               return 0, fmt.Errorf("Setting up change notification on registry key failed: %v", err)
+                       }
+
+                       var accessFlags uint32
+                       if isLast {
+                               accessFlags = access
+                       } else {
+                               accessFlags = KEY_NOTIFY
+                       }
+                       key, err = registry.OpenKey(k, keyName, accessFlags)
+                       if err == windows.ERROR_FILE_NOT_FOUND || err == windows.ERROR_PATH_NOT_FOUND {
+                               timeout := time.Until(deadline) / time.Millisecond
+                               if timeout < 0 {
+                                       timeout = 0
+                               }
+                               s, err := windows.WaitForSingleObject(event, uint32(timeout))
+                               if err != nil {
+                                       return 0, fmt.Errorf("Unable to wait on registry key: %v", err)
+                               }
+                               if s == uint32(windows.WAIT_TIMEOUT) { // windows.WAIT_TIMEOUT status const is misclassified as error in golang.org/x/sys/windows
+                                       return 0, errors.New("Timeout waiting for registry key")
+                               }
+                       } else if err != nil {
+                               return 0, fmt.Errorf("Error opening registry key %v: %v", path, err)
+                       } else {
+                               if isLast {
+                                       return key, nil
+                               }
+                               defer key.Close()
+                               break
+                       }
+               }
+
+               k = key
+       }
+}
+
+func WaitForKey(k registry.Key, path string, timeout time.Duration) error {
+       key, err := OpenKeyWait(k, path, KEY_NOTIFY, timeout)
+       if err != nil {
+               return err
+       }
+       key.Close()
+       return nil
+}
+
+//
+// getStringValueRetry function reads a string value from registry. It waits for
+// the registry value to become available or returns error on timeout.
+//
+// Key must be opened with at least QUERY_VALUE|KEY_NOTIFY access.
+//
+func getStringValueRetry(key registry.Key, name string, timeout time.Duration) (string, uint32, error) {
+       runtime.LockOSThread()
+       defer runtime.UnlockOSThread()
+
+       event, err := windows.CreateEvent(nil, 0, 0, nil)
+       if err != nil {
+               return "", 0, fmt.Errorf("Error creating event: %v", err)
+       }
+       defer windows.CloseHandle(event)
+
+       deadline := time.Now().Add(timeout)
+       for {
+               err := regNotifyChangeKeyValue(windows.Handle(key), false, REG_NOTIFY_CHANGE_LAST_SET, windows.Handle(event), true)
+               if err != nil {
+                       return "", 0, fmt.Errorf("Setting up change notification on registry value failed: %v", err)
+               }
+
+               value, valueType, err := key.GetStringValue(name)
+               if err == windows.ERROR_FILE_NOT_FOUND || err == windows.ERROR_PATH_NOT_FOUND {
+                       timeout := time.Until(deadline) / time.Millisecond
+                       if timeout < 0 {
+                               timeout = 0
+                       }
+                       s, err := windows.WaitForSingleObject(event, uint32(timeout))
+                       if err != nil {
+                               return "", 0, fmt.Errorf("Unable to wait on registry value: %v", err)
+                       }
+                       if s == uint32(windows.WAIT_TIMEOUT) { // windows.WAIT_TIMEOUT status const is misclassified as error in golang.org/x/sys/windows
+                               return "", 0, errors.New("Timeout waiting for registry value")
+                       }
+               } else if err != nil {
+                       return "", 0, fmt.Errorf("Error reading registry value %v: %v", name, err)
+               } else {
+                       return value, valueType, nil
+               }
+       }
+}
+
+func expandString(value string, valueType uint32, err error) (string, error) {
+       if err != nil {
+               return "", err
+       }
+
+       if valueType != registry.EXPAND_SZ {
+               // Value does not require expansion.
+               return value, nil
+       }
+
+       valueExp, err := registry.ExpandString(value)
+       if err != nil {
+               // Expanding failed: return original sting value.
+               return value, nil
+       }
+
+       // Return expanded value.
+       return valueExp, nil
+}
+
+//
+// GetStringValueWait function reads a string value from registry. It waits
+// for the registry value to become available or returns error on timeout.
+//
+// Key must be opened with at least QUERY_VALUE|KEY_NOTIFY access.
+//
+// If the value type is REG_EXPAND_SZ the environment variables are expanded.
+// Should expanding fail, original string value and nil error are returned.
+//
+func GetStringValueWait(key registry.Key, name string, timeout time.Duration) (string, error) {
+       return expandString(getStringValueRetry(key, name, timeout))
+}
+
+//
+// GetStringValue function reads a string value from registry.
+//
+// Key must be opened with at least QUERY_VALUE access.
+//
+// If the value type is REG_EXPAND_SZ the environment variables are expanded.
+// Should expanding fail, original string value and nil error are returned.
+//
+func GetStringValue(key registry.Key, name string) (string, error) {
+       return expandString(key.GetStringValue(name))
+}
+
+//
+// GetIntegerValueWait function reads a DWORD32 or QWORD value from registry.
+// It waits for the registry value to become available or returns error on
+// timeout.
+//
+// Key must be opened with at least QUERY_VALUE|KEY_NOTIFY access.
+//
+func GetIntegerValueWait(key registry.Key, name string, timeout time.Duration) (uint64, error) {
+       runtime.LockOSThread()
+       defer runtime.UnlockOSThread()
+
+       event, err := windows.CreateEvent(nil, 0, 0, nil)
+       if err != nil {
+               return 0, fmt.Errorf("Error creating event: %v", err)
+       }
+       defer windows.CloseHandle(event)
+
+       deadline := time.Now().Add(timeout)
+       for {
+               err := regNotifyChangeKeyValue(windows.Handle(key), false, REG_NOTIFY_CHANGE_LAST_SET, windows.Handle(event), true)
+               if err != nil {
+                       return 0, fmt.Errorf("Setting up change notification on registry value failed: %v", err)
+               }
+
+               value, _, err := key.GetIntegerValue(name)
+               if err == windows.ERROR_FILE_NOT_FOUND || err == windows.ERROR_PATH_NOT_FOUND {
+                       timeout := time.Until(deadline) / time.Millisecond
+                       if timeout < 0 {
+                               timeout = 0
+                       }
+                       s, err := windows.WaitForSingleObject(event, uint32(timeout))
+                       if err != nil {
+                               return 0, fmt.Errorf("Unable to wait on registry value: %v", err)
+                       }
+                       if s == uint32(windows.WAIT_TIMEOUT) { // windows.WAIT_TIMEOUT status const is misclassified as error in golang.org/x/sys/windows
+                               return 0, errors.New("Timeout waiting for registry value")
+                       }
+               } else if err != nil {
+                       return 0, fmt.Errorf("Error reading registry value %v: %v", name, err)
+               } else {
+                       return value, nil
+               }
+       }
+}
diff --git a/tun/wintun/registry/registry_windows_test.go b/tun/wintun/registry/registry_windows_test.go
new file mode 100644 (file)
index 0000000..c5a6e28
--- /dev/null
@@ -0,0 +1,103 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package registry
+
+import (
+       "testing"
+       "time"
+
+       "golang.org/x/sys/windows/registry"
+)
+
+const keyRoot = registry.CURRENT_USER
+const pathRoot = "Software\\WireGuardRegistryTest"
+const path = pathRoot + "\\foobar"
+const pathFake = pathRoot + "\\raboof"
+
+func Test_WaitForKey(t *testing.T) {
+       registry.DeleteKey(keyRoot, path)
+       registry.DeleteKey(keyRoot, pathRoot)
+       go func() {
+               time.Sleep(time.Second * 1)
+               key, _, err := registry.CreateKey(keyRoot, pathFake, registry.QUERY_VALUE)
+               if err != nil {
+                       t.Errorf("Error creating registry key: %v", err)
+               }
+               key.Close()
+               registry.DeleteKey(keyRoot, pathFake)
+
+               key, _, err = registry.CreateKey(keyRoot, path, registry.QUERY_VALUE)
+               if err != nil {
+                       t.Errorf("Error creating registry key: %v", err)
+               }
+               key.Close()
+       }()
+       err := WaitForKey(keyRoot, path, time.Second*2)
+       if err != nil {
+               t.Errorf("Error waiting for registry key: %v", err)
+       }
+       registry.DeleteKey(keyRoot, path)
+       registry.DeleteKey(keyRoot, pathRoot)
+
+       err = WaitForKey(keyRoot, path, time.Second*1)
+       if err == nil {
+               t.Error("Registry key notification expected to timeout but it succeeded.")
+       }
+}
+
+func Test_GetValueWait(t *testing.T) {
+       registry.DeleteKey(keyRoot, path)
+       registry.DeleteKey(keyRoot, pathRoot)
+       go func() {
+               time.Sleep(time.Second * 1)
+               key, _, err := registry.CreateKey(keyRoot, path, registry.SET_VALUE)
+               if err != nil {
+                       t.Errorf("Error creating registry key: %v", err)
+               }
+               time.Sleep(time.Second * 1)
+               key.SetStringValue("name1", "eulav")
+               key.SetExpandStringValue("name2", "value")
+               time.Sleep(time.Second * 1)
+               key.SetDWordValue("name3", ^uint32(123))
+               key.SetDWordValue("name4", 123)
+               key.Close()
+       }()
+
+       key, err := OpenKeyWait(keyRoot, path, registry.QUERY_VALUE|KEY_NOTIFY, time.Second*2)
+       if err != nil {
+               t.Errorf("Error waiting for registry key: %v", err)
+       }
+
+       valueStr, err := GetStringValueWait(key, "name2", time.Second*2)
+       if err != nil {
+               t.Errorf("Error waiting for registry value: %v", err)
+       }
+       if valueStr != "value" {
+               t.Errorf("Wrong value read: %v", valueStr)
+       }
+
+       _, err = GetStringValueWait(key, "nonexisting", time.Second*1)
+       if err == nil {
+               t.Error("Registry value notification expected to timeout but it succeeded.")
+       }
+
+       valueInt, err := GetIntegerValueWait(key, "name4", time.Second*2)
+       if err != nil {
+               t.Errorf("Error waiting for registry value: %v", err)
+       }
+       if valueInt != 123 {
+               t.Errorf("Wrong value read: %v", valueInt)
+       }
+
+       _, err = GetIntegerValueWait(key, "nonexisting", time.Second*1)
+       if err == nil {
+               t.Error("Registry value notification expected to timeout but it succeeded.")
+       }
+
+       key.Close()
+       registry.DeleteKey(keyRoot, path)
+       registry.DeleteKey(keyRoot, pathRoot)
+}
diff --git a/tun/wintun/registry/zregistry_windows.go b/tun/wintun/registry/zregistry_windows.go
new file mode 100644 (file)
index 0000000..f7ac33b
--- /dev/null
@@ -0,0 +1,63 @@
+// Code generated by 'go generate'; DO NOT EDIT.
+
+package registry
+
+import (
+       "syscall"
+       "unsafe"
+
+       "golang.org/x/sys/windows"
+)
+
+var _ unsafe.Pointer
+
+// Do the interface allocations only once for common
+// Errno values.
+const (
+       errnoERROR_IO_PENDING = 997
+)
+
+var (
+       errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
+)
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+       switch e {
+       case 0:
+               return nil
+       case errnoERROR_IO_PENDING:
+               return errERROR_IO_PENDING
+       }
+       // TODO: add more here, after collecting data on the common
+       // error values see on Windows. (perhaps when running
+       // all.bat?)
+       return e
+}
+
+var (
+       modadvapi32 = windows.NewLazySystemDLL("advapi32.dll")
+
+       procRegNotifyChangeKeyValue = modadvapi32.NewProc("RegNotifyChangeKeyValue")
+)
+
+func regNotifyChangeKeyValue(key windows.Handle, watchSubtree bool, notifyFilter uint32, event windows.Handle, asynchronous bool) (regerrno error) {
+       var _p0 uint32
+       if watchSubtree {
+               _p0 = 1
+       } else {
+               _p0 = 0
+       }
+       var _p1 uint32
+       if asynchronous {
+               _p1 = 1
+       } else {
+               _p1 = 0
+       }
+       r0, _, _ := syscall.Syscall6(procRegNotifyChangeKeyValue.Addr(), 5, uintptr(key), uintptr(_p0), uintptr(notifyFilter), uintptr(event), uintptr(_p1), 0)
+       if r0 != 0 {
+               regerrno = syscall.Errno(r0)
+       }
+       return
+}
diff --git a/tun/wintun/registryhacks_windows.go b/tun/wintun/registryhacks_windows.go
deleted file mode 100644 (file)
index bf72f92..0000000
+++ /dev/null
@@ -1,42 +0,0 @@
-/* SPDX-License-Identifier: MIT
- *
- * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
- */
-
-package wintun
-
-import (
-       "golang.org/x/sys/windows/registry"
-       "time"
-)
-
-const (
-       numRetries   = 50
-       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
-}
index 69f6eb61ffdb735d1596dc2aae1db44731122c71..fb2cc2281110e7a578bd0dd6ea9c73fd4def3c4b 100644 (file)
@@ -8,7 +8,6 @@ package wintun
 import (
        "errors"
        "fmt"
-       "golang.zx2c4.com/wireguard/tun/wintun/netshell"
        "strings"
        "syscall"
        "time"
@@ -17,6 +16,8 @@ import (
        "golang.org/x/sys/windows"
        "golang.org/x/sys/windows/registry"
        "golang.zx2c4.com/wireguard/tun/wintun/guid"
+       "golang.zx2c4.com/wireguard/tun/wintun/netshell"
+       registryEx "golang.zx2c4.com/wireguard/tun/wintun/registry"
        "golang.zx2c4.com/wireguard/tun/wintun/setupapi"
 )
 
@@ -34,33 +35,24 @@ var deviceClassNetGUID = windows.GUID{Data1: 0x4d36e972, Data2: 0xe325, Data3: 0
 const hardwareID = "Wintun"
 const enumerator = ""
 const machineName = ""
+const waitForRegistryTimeout = time.Second * 5
 
 //
 // MakeWintun creates interface handle and populates it from device registry key
 //
-func makeWintun(deviceInfoSet setupapi.DevInfo, deviceInfoData *setupapi.DevInfoData, wait bool) (*Wintun, error) {
+func makeWintun(deviceInfoSet setupapi.DevInfo, deviceInfoData *setupapi.DevInfoData) (*Wintun, error) {
        // Open HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\<class>\<id> registry key.
-       key, err := deviceInfoSet.OpenDevRegKey(deviceInfoData, setupapi.DICS_FLAG_GLOBAL, 0, setupapi.DIREG_DRV, registry.READ)
+       key, err := deviceInfoSet.OpenDevRegKey(deviceInfoData, setupapi.DICS_FLAG_GLOBAL, 0, setupapi.DIREG_DRV, registry.QUERY_VALUE)
        if err != nil {
                return nil, errors.New("Device-specific registry key open failed: " + err.Error())
        }
        defer key.Close()
 
-       var valueStr string
-       var valueType uint32
-
        // Read the NetCfgInstanceId value.
-       if wait {
-               valueStr, valueType, err = keyGetStringValueRetry(key, "NetCfgInstanceId")
-       } else {
-               valueStr, valueType, err = key.GetStringValue("NetCfgInstanceId")
-       }
+       valueStr, err := registryEx.GetStringValue(key, "NetCfgInstanceId")
        if err != nil {
                return nil, errors.New("RegQueryStringValue(\"NetCfgInstanceId\") failed: " + err.Error())
        }
-       if valueType != registry.SZ {
-               return nil, fmt.Errorf("NetCfgInstanceId registry value is not REG_SZ (expected: %v, provided: %v)", registry.SZ, valueType)
-       }
 
        // Convert to windows.GUID.
        ifid, err := guid.FromString(valueStr)
@@ -69,13 +61,13 @@ func makeWintun(deviceInfoSet setupapi.DevInfo, deviceInfoData *setupapi.DevInfo
        }
 
        // Read the NetLuidIndex value.
-       luidIdx, valueType, err := key.GetIntegerValue("NetLuidIndex")
+       luidIdx, _, err := key.GetIntegerValue("NetLuidIndex")
        if err != nil {
                return nil, errors.New("RegQueryValue(\"NetLuidIndex\") failed: " + err.Error())
        }
 
        // Read the NetLuidIndex value.
-       ifType, valueType, err := key.GetIntegerValue("*IfType")
+       ifType, _, err := key.GetIntegerValue("*IfType")
        if err != nil {
                return nil, errors.New("RegQueryValue(\"*IfType\") failed: " + err.Error())
        }
@@ -125,14 +117,14 @@ func GetInterface(ifname string, hwndParent uintptr) (*Wintun, error) {
                }
 
                // Get interface ID.
-               wintun, err := makeWintun(devInfoList, deviceData, false)
+               wintun, err := makeWintun(devInfoList, deviceData)
                if err != nil {
                        continue
                }
 
                //TODO: is there a better way than comparing ifnames?
                // Get interface name.
-               ifname2, err := wintun.getInterfaceNameNoRetry()
+               ifname2, err := wintun.GetInterfaceName()
                if err != nil {
                        continue
                }
@@ -298,24 +290,85 @@ func CreateInterface(description string, hwndParent uintptr) (*Wintun, bool, err
                        rebootRequired = true
                }
 
-               // Get network interface. DIF_INSTALLDEVICE returns almost immediately, while the device
-               // installation continues in the background. It might take a while, before all 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.
-               for numAttempts := 0; numAttempts < 30; numAttempts++ {
-                       wintun, err = makeWintun(devInfoList, deviceData, true)
-                       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.
-                                       err = errors.New("Time-out waiting for adapter to get ready")
-                                       time.Sleep(time.Second / 4)
-                                       continue
-                               }
+
+               // Wait for device registry key to emerge and populate.
+               key, err := registryEx.OpenKeyWait(
+                       registry.LOCAL_MACHINE,
+                       fmt.Sprintf("SYSTEM\\CurrentControlSet\\Control\\Class\\%v\\%04d", guid.ToString(&deviceClassNetGUID), deviceData.DevInst),
+                       registry.QUERY_VALUE|registryEx.KEY_NOTIFY,
+                       waitForRegistryTimeout)
+               if err == nil {
+                       _, err = registryEx.GetStringValueWait(key, "NetCfgInstanceId", waitForRegistryTimeout)
+                       if err == nil {
+                               _, err = registryEx.GetIntegerValueWait(key, "NetLuidIndex", waitForRegistryTimeout)
                        }
+                       if err == nil {
+                               _, err = registryEx.GetIntegerValueWait(key, "*IfType", waitForRegistryTimeout)
+                       }
+                       key.Close()
+               }
+               // Clear error and let makeWintun() open the key using SetupAPI's devInfoList.OpenDevRegKey().
+               err = nil
+       }
 
-                       break
+       if err == nil {
+               // Get network interface.
+               wintun, err = makeWintun(devInfoList, deviceData)
+       }
+
+       if err == nil {
+               // Wait for network registry key to emerge and populate.
+               key, err := registryEx.OpenKeyWait(
+                       registry.LOCAL_MACHINE,
+                       wintun.GetNetRegKeyName(),
+                       registry.QUERY_VALUE|registryEx.KEY_NOTIFY,
+                       waitForRegistryTimeout)
+               if err == nil {
+                       _, err = registryEx.GetStringValueWait(key, "Name", waitForRegistryTimeout)
+                       key.Close()
                }
        }
 
+       if err == nil {
+               // Wait for TCP/IP adapter registry key to emerge and populate.
+               key, err := registryEx.OpenKeyWait(
+                       registry.LOCAL_MACHINE,
+                       wintun.GetTcpipAdapterRegKeyName(), registry.QUERY_VALUE|registryEx.KEY_NOTIFY,
+                       waitForRegistryTimeout)
+               if err == nil {
+                       _, err = registryEx.GetStringValueWait(key, "IpConfig", waitForRegistryTimeout)
+                       key.Close()
+               }
+       }
+
+       if err == nil {
+               // Wait for TCP/IP interface registry key to emerge.
+               key, err := registryEx.OpenKeyWait(
+                       registry.LOCAL_MACHINE,
+                       wintun.GetTcpipInterfaceRegKeyName(), registry.QUERY_VALUE,
+                       waitForRegistryTimeout)
+               if err == nil {
+                       key.Close()
+               }
+       }
+
+       //
+       // All the registry keys and values we're relying on are present now.
+       //
+
+       if err == nil {
+               // Disable dead gateway detection on our interface.
+               key, err := registry.OpenKey(registry.LOCAL_MACHINE, wintun.GetTcpipInterfaceRegKeyName(), registry.SET_VALUE)
+               if err != nil {
+                       err = errors.New("Error opening interface-specific TCP/IP network registry key: " + err.Error())
+               }
+               key.SetDWordValue("EnableDeadGWDetect", 0)
+               key.Close()
+       }
+
        if err == nil {
                return wintun, rebootRequired, nil
        }
@@ -373,7 +426,7 @@ func (wintun *Wintun) DeleteInterface(hwndParent uintptr) (bool, bool, error) {
 
                // Get interface ID.
                //TODO: Store some ID in the Wintun object such that this call isn't required.
-               wintun2, err := makeWintun(devInfoList, deviceData, false)
+               wintun2, err := makeWintun(devInfoList, deviceData)
                if err != nil {
                        continue
                }
@@ -438,17 +491,6 @@ func checkReboot(deviceInfoSet setupapi.DevInfo, deviceInfoData *setupapi.DevInf
 // GetInterfaceName returns network interface name.
 //
 func (wintun *Wintun) GetInterfaceName() (string, error) {
-       key, err := registryOpenKeyRetry(registry.LOCAL_MACHINE, wintun.GetNetRegKeyName(), registry.QUERY_VALUE)
-       if err != nil {
-               return "", errors.New("Network-specific registry key open failed: " + err.Error())
-       }
-       defer key.Close()
-
-       // Get the interface name.
-       return getRegStringValue(key, "Name")
-}
-
-func (wintun *Wintun) getInterfaceNameNoRetry() (string, error) {
        key, err := registry.OpenKey(registry.LOCAL_MACHINE, wintun.GetNetRegKeyName(), registry.QUERY_VALUE)
        if err != nil {
                return "", errors.New("Network-specific registry key open failed: " + err.Error())
@@ -456,20 +498,13 @@ func (wintun *Wintun) getInterfaceNameNoRetry() (string, error) {
        defer key.Close()
 
        // Get the interface name.
-       return getRegStringValue(key, "Name")
+       return registryEx.GetStringValue(key, "Name")
 }
 
 //
 // SetInterfaceName sets network interface name.
 //
 func (wintun *Wintun) SetInterfaceName(ifname string) error {
-       // We open the registry key before calling HrRename, because the registry open will wait until the key exists.
-       key, err := registryOpenKeyRetry(registry.LOCAL_MACHINE, wintun.GetNetRegKeyName(), registry.SET_VALUE)
-       if err != nil {
-               return errors.New("Network-specific registry key open failed: " + err.Error())
-       }
-       defer key.Close()
-
        // We have to tell the various runtime COM services about the new name too. We ignore the
        // error because netshell isn't available on servercore.
        // TODO: netsh.exe falls back to NciSetConnection in this case. If somebody complains, maybe
@@ -477,6 +512,11 @@ func (wintun *Wintun) SetInterfaceName(ifname string) error {
        _ = netshell.HrRenameConnection(&wintun.CfgInstanceID, windows.StringToUTF16Ptr(ifname))
 
        // Set the interface name. The above line should have done this too, but in case it failed, we force it.
+       key, err := registry.OpenKey(registry.LOCAL_MACHINE, wintun.GetNetRegKeyName(), registry.SET_VALUE)
+       if err != nil {
+               return errors.New("Network-specific registry key open failed: " + err.Error())
+       }
+       defer key.Close()
        return key.SetStringValue("Name", ifname)
 }
 
@@ -488,31 +528,28 @@ func (wintun *Wintun) GetNetRegKeyName() string {
 }
 
 //
-// getRegStringValue function reads a string value from registry.
+// GetTcpipAdapterRegKeyName returns adapter-specific TCP/IP network registry key name.
 //
-// If the value type is REG_EXPAND_SZ the environment variables are expanded.
-// Should expanding fail, original string value and nil error are returned.
+func (wintun *Wintun) GetTcpipAdapterRegKeyName() string {
+       return fmt.Sprintf("SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\Adapters\\%v", guid.ToString(&wintun.CfgInstanceID))
+}
+
+//
+// GetTcpipInterfaceRegKeyName returns interface-specific TCP/IP network registry key name.
 //
-func getRegStringValue(key registry.Key, name string) (string, error) {
-       // Read string value.
-       value, valueType, err := keyGetStringValueRetry(key, name)
+func (wintun *Wintun) GetTcpipInterfaceRegKeyName() string {
+       key, err := registry.OpenKey(registry.LOCAL_MACHINE, wintun.GetTcpipAdapterRegKeyName(), registry.QUERY_VALUE)
        if err != nil {
-               return "", err
-       }
-
-       if valueType != registry.EXPAND_SZ {
-               // Value does not require expansion.
-               return value, nil
+               err = errors.New("Error opening adapter-specific TCP/IP network registry key: " + err.Error())
        }
+       defer key.Close()
 
-       valueExp, err := registry.ExpandString(value)
+       path, err := registryEx.GetStringValue(key, "IpConfig")
        if err != nil {
-               // Expanding failed: return original sting value.
-               return value, nil
+               err = errors.New("Error reading IpConfig: " + err.Error())
        }
 
-       // Return expanded value.
-       return valueExp, nil
+       return "SYSTEM\\CurrentControlSet\\Services\\" + path
 }
 
 //