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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
* Copyright (C) 2021 Mullvad VPN AB. All Rights Reserved.
*/
package interfacewatcher
import (
"sync"
"time"
"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
)
type Event struct {
Luid winipcfg.LUID
Family winipcfg.AddressFamily
}
type interfaceWatcher struct {
ready chan bool
processingMutex sync.Mutex
interfaceChangeCallback *winipcfg.InterfaceChangeCallback
seenEvents []Event
wantedEvents []Event
expired bool
}
func NewWatcher() (*interfaceWatcher, error) {
iw := &interfaceWatcher{
ready: make(chan bool, 1),
expired: false,
}
var err error
iw.interfaceChangeCallback, err = winipcfg.RegisterInterfaceChangeCallback(func(notificationType winipcfg.MibNotificationType, iface *winipcfg.MibIPInterfaceRow) {
if notificationType != winipcfg.MibAddInstance {
return
}
iw.processingMutex.Lock()
defer iw.processingMutex.Unlock()
if iw.expired {
return
}
iw.seenEvents = append(iw.seenEvents, Event{iface.InterfaceLUID, iface.Family})
if len(iw.wantedEvents) != 0 {
iw.evaluateEvents()
}
})
if err != nil {
return nil, err
}
return iw, nil
}
func (iw *interfaceWatcher) evaluateEvents() {
matched := 0
// This is n*n, but typically very few items in both slices :-)
for _, wanted := range iw.wantedEvents {
for _, seen := range iw.seenEvents {
if seen == wanted {
matched += 1
break
}
}
}
if len(iw.wantedEvents) != matched {
return
}
iw.expired = true
iw.ready <- true
}
// You can only join() once after which the watcher becomes expired.
func (iw *interfaceWatcher) Join(wantedEvents []Event, timeoutSeconds int) bool {
{
iw.processingMutex.Lock()
if iw.expired || len(wantedEvents) == 0 {
iw.processingMutex.Unlock()
return false
}
iw.wantedEvents = wantedEvents
iw.evaluateEvents()
iw.processingMutex.Unlock()
}
result := false
select {
case <- iw.ready:
result = true
case <- time.After(time.Duration(timeoutSeconds) * time.Second):
result = false
}
{
iw.processingMutex.Lock()
iw.wantedEvents = nil
iw.expired = true
iw.processingMutex.Unlock()
}
return result
}
func (iw *interfaceWatcher) Destroy() {
if iw.interfaceChangeCallback != nil {
iw.interfaceChangeCallback.Unregister()
iw.interfaceChangeCallback = nil
}
}
|
