feat(WIP): add pause and resume functionality for Portmaster/SPN

https://github.com/safing/portmaster/issues/2050

service/firewall/interception/interception_linux.go

@@ -34,6 +34,11 @@ func startInterception(packets chan packet.Packet) error {
 
 // stop starts the interception.
 func stopInterception() error {
+	// TODO: stop ebpf workers gracefully
+	// E.g.:
+	// 		module.mgr.Cancel()
+	// 		<-m.Done()
+
 	return StopNfqueueInterception()
 }
 

service/firewall/interception/introspection.go

@@ -12,9 +12,7 @@ import (
 
 var (
 	packetMetricsDestination string
-	metrics                  = &packetMetrics{
-		done: make(chan struct{}),
-	}
+	metrics                  = &packetMetrics{}
 )
 
 func init() {
@@ -40,6 +38,10 @@ func (pm *packetMetrics) record(tp *tracedPacket, verdict string) {
 		pm.l.Lock()
 		defer pm.l.Unlock()
 
+		if pm.done == nil {
+			return
+		}
+
 		pm.records = append(pm.records, &performanceRecord{
 			start:    start,
 			duration: duration,
@@ -48,6 +50,18 @@ func (pm *packetMetrics) record(tp *tracedPacket, verdict string) {
 	}(tp.start.UnixNano(), time.Since(tp.start))
 }
 
+func (pm *packetMetrics) stop() {
+	pm.l.Lock()
+	defer pm.l.Unlock()
+
+	if pm.done == nil {
+		return
+	}
+
+	close(pm.done)
+	pm.done = nil
+}
+
 func (pm *packetMetrics) writeMetrics() {
 	if packetMetricsDestination == "" {
 		return
@@ -62,9 +76,14 @@ func (pm *packetMetrics) writeMetrics() {
 		_ = f.Close()
 	}()
 
+	pm.l.Lock()
+	pm.done = make(chan struct{})
+	done := pm.done
+	pm.l.Unlock()
+
 	for {
 		select {
-		case <-pm.done:
+		case <-done:
 			return
 		case <-time.After(time.Second * 5):
 		}

service/firewall/interception/module.go

@@ -40,6 +40,7 @@ var (
 	BandwidthUpdates = make(chan *packet.BandwidthUpdate, 1000)
 
 	disableInterception bool
+	isStarted           atomic.Bool
 )
 
 func init() {
@@ -53,6 +54,10 @@ func start() error {
 		return nil
 	}
 
+	if !isStarted.CompareAndSwap(false, true) {
+		return nil // already running
+	}
+
 	inputPackets := Packets
 	if packetMetricsDestination != "" {
 		go metrics.writeMetrics()
@@ -64,7 +69,16 @@ func start() error {
 		}()
 	}
 
-	return startInterception(inputPackets)
+	err := startInterception(inputPackets)
+	if err != nil {
+		log.Errorf("interception: failed to start module: %q", err)
+		log.Debug("interception: cleaning up after failed start...")
+		if e := stopInterception(); e != nil {
+			log.Debugf("interception: error cleaning up after failed start: %q", e.Error())
+		}
+		isStarted.Store(false)
+	}
+	return err
 }
 
 // Stop starts the interception.
@@ -73,7 +87,11 @@ func stop() error {
 		return nil
 	}
 
-	close(metrics.done)
+	if !isStarted.CompareAndSwap(true, false) {
+		return nil // not running
+	}
+
+	metrics.stop()
 	if err := stopInterception(); err != nil {
 		log.Errorf("failed to stop interception module: %s", err)
 	}