Add windows support

internal/winipcfg/unicast_address_change_handler.go

@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019-2022 WireGuard LLC. All Rights Reserved.
+ */
+
+package winipcfg
+
+import (
+	"sync"
+
+	"golang.org/x/sys/windows"
+)
+
+// UnicastAddressChangeCallback structure allows unicast address change callback handling.
+type UnicastAddressChangeCallback struct {
+	cb   func(notificationType MibNotificationType, unicastAddress *MibUnicastIPAddressRow)
+	wait sync.WaitGroup
+}
+
+var (
+	unicastAddressChangeAddRemoveMutex = sync.Mutex{}
+	unicastAddressChangeMutex          = sync.Mutex{}
+	unicastAddressChangeCallbacks      = make(map[*UnicastAddressChangeCallback]bool)
+	unicastAddressChangeHandle         = windows.Handle(0)
+)
+
+// RegisterUnicastAddressChangeCallback registers a new UnicastAddressChangeCallback. If this particular callback is already
+// registered, the function will silently return. Returned UnicastAddressChangeCallback.Unregister method should be used
+// to unregister.
+func RegisterUnicastAddressChangeCallback(callback func(notificationType MibNotificationType, unicastAddress *MibUnicastIPAddressRow)) (*UnicastAddressChangeCallback, error) {
+	s := &UnicastAddressChangeCallback{cb: callback}
+
+	unicastAddressChangeAddRemoveMutex.Lock()
+	defer unicastAddressChangeAddRemoveMutex.Unlock()
+
+	unicastAddressChangeMutex.Lock()
+	defer unicastAddressChangeMutex.Unlock()
+
+	unicastAddressChangeCallbacks[s] = true
+
+	if unicastAddressChangeHandle == 0 {
+		err := notifyUnicastIPAddressChange(windows.AF_UNSPEC, windows.NewCallback(unicastAddressChanged), 0, false, &unicastAddressChangeHandle)
+		if err != nil {
+			delete(unicastAddressChangeCallbacks, s)
+			unicastAddressChangeHandle = 0
+			return nil, err
+		}
+	}
+
+	return s, nil
+}
+
+// Unregister unregisters the callback.
+func (callback *UnicastAddressChangeCallback) Unregister() error {
+	unicastAddressChangeAddRemoveMutex.Lock()
+	defer unicastAddressChangeAddRemoveMutex.Unlock()
+
+	unicastAddressChangeMutex.Lock()
+	delete(unicastAddressChangeCallbacks, callback)
+	removeIt := len(unicastAddressChangeCallbacks) == 0 && unicastAddressChangeHandle != 0
+	unicastAddressChangeMutex.Unlock()
+
+	callback.wait.Wait()
+
+	if removeIt {
+		err := cancelMibChangeNotify2(unicastAddressChangeHandle)
+		if err != nil {
+			return err
+		}
+		unicastAddressChangeHandle = 0
+	}
+
+	return nil
+}
+
+func unicastAddressChanged(callerContext uintptr, row *MibUnicastIPAddressRow, notificationType MibNotificationType) uintptr {
+	rowCopy := *row
+	unicastAddressChangeMutex.Lock()
+	for cb := range unicastAddressChangeCallbacks {
+		cb.wait.Add(1)
+		go func(cb *UnicastAddressChangeCallback) {
+			cb.cb(notificationType, &rowCopy)
+			cb.wait.Done()
+		}(cb)
+	}
+	unicastAddressChangeMutex.Unlock()
+	return 0
+}