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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"
)
// InterfaceChangeCallback structure allows interface change callback handling.
type InterfaceChangeCallback struct {
cb func(notificationType MibNotificationType, iface *MibIPInterfaceRow)
wait sync.WaitGroup
}
var (
interfaceChangeAddRemoveMutex = sync.Mutex{}
interfaceChangeMutex = sync.Mutex{}
interfaceChangeCallbacks = make(map[*InterfaceChangeCallback]bool)
interfaceChangeHandle = windows.Handle(0)
)
// RegisterInterfaceChangeCallback registers a new InterfaceChangeCallback. If this particular callback is already
// registered, the function will silently return. Returned InterfaceChangeCallback.Unregister method should be used
// to unregister.
func RegisterInterfaceChangeCallback(callback func(notificationType MibNotificationType, iface *MibIPInterfaceRow)) (*InterfaceChangeCallback, error) {
s := &InterfaceChangeCallback{cb: callback}
interfaceChangeAddRemoveMutex.Lock()
defer interfaceChangeAddRemoveMutex.Unlock()
interfaceChangeMutex.Lock()
defer interfaceChangeMutex.Unlock()
interfaceChangeCallbacks[s] = true
if interfaceChangeHandle == 0 {
err := notifyIPInterfaceChange(windows.AF_UNSPEC, windows.NewCallback(interfaceChanged), 0, false, &interfaceChangeHandle)
if err != nil {
delete(interfaceChangeCallbacks, s)
interfaceChangeHandle = 0
return nil, err
}
}
return s, nil
}
// Unregister unregisters the callback.
func (callback *InterfaceChangeCallback) Unregister() error {
interfaceChangeAddRemoveMutex.Lock()
defer interfaceChangeAddRemoveMutex.Unlock()
interfaceChangeMutex.Lock()
delete(interfaceChangeCallbacks, callback)
removeIt := len(interfaceChangeCallbacks) == 0 && interfaceChangeHandle != 0
interfaceChangeMutex.Unlock()
callback.wait.Wait()
if removeIt {
err := cancelMibChangeNotify2(interfaceChangeHandle)
if err != nil {
return err
}
interfaceChangeHandle = 0
}
return nil
}
func interfaceChanged(callerContext uintptr, row *MibIPInterfaceRow, notificationType MibNotificationType) uintptr {
rowCopy := *row
interfaceChangeMutex.Lock()
for cb := range interfaceChangeCallbacks {
cb.wait.Add(1)
go func(cb *InterfaceChangeCallback) {
cb.cb(notificationType, &rowCopy)
cb.wait.Done()
}(cb)
}
interfaceChangeMutex.Unlock()
return 0
}
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