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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019-2020 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
}
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