Enhanced monitoring for changes or removal of the V2Ray route, restor…

…ing it if necessary.

ivpn/desktop-app-shadow#146

daemon/netchange/net_change_detector.go

@@ -106,11 +106,14 @@ func (d *Detector) DelayBeforeNotify() time.Duration {
 	return d.delayBeforeNotify
 }
 
-// must be called when routing change detected (called from platform-specific sources)
+// Must be called when routing change detected (called from platform-specific sources)
+// It notifies about routing change with delay 'd.DelayBeforeNotify()'. This reduces amount of multiple consecutive notifications
 func (d *Detector) routingChangeDetected() {
 	d.timerNotifyAfterDelay.Reset(d.DelayBeforeNotify())
 }
 
+// Immediately notify about routing change.
+// Consider using routingChangeDetected() instead
 func (d *Detector) notifyRoutingChange() {
 	if d.routingChangeNotifyChan == nil {
 		return

daemon/netchange/net_change_detector_windows.go

@@ -116,7 +116,7 @@ func (d *Detector) doStart() {
 		}
 
 		// notify about routing change
-		d.notifyRoutingChange()
+		d.routingChangeDetected()
 	}
 }
 

daemon/v2r/v2ray.go

@@ -46,6 +46,21 @@ func init() {
 	implInit() // platform-specific initialisation
 }
 
+// IMPORTANT: Hardcoded string constants! The may be changed after update V2Ray version!!!
+// In use for checking V2Ray console output: for connectivity issues detectin to V2Ray server
+// IMPORTANT: Hardcoded string constants!
+// Used to check the V2Ray process console output for detecting connectivity issues with the V2Ray server.
+// Output examples:
+//
+//	2023/11/15 13:34:45 [Info] transport/internet/quic: dialing QUIC to udp:185.246.211.184:2049
+//	2023/11/15 13:41:17 [Info] [2879864986] transport/internet/tcp: dialing TCP to tcp:185.246.211.184:80
+//
+// Two 'dialing' attempts during a short period (20s) may indicate a problem with connecting to the V2Ray server.
+// Therefore, it is necessary to check the consistency of the route to the V2Ray server.
+var detectDialingRegexp = regexp.MustCompile(".* transport/internet.* dialing .*")
+
+const detectDialingInterval = time.Second * 20
+
 type V2RayTransportType int
 
 const (
@@ -80,16 +95,32 @@ type V2RayWrapper struct {
 	// IP address of local interface which is in use for communication with V2Ray server
 	// (we use use it to detect changes of the route to V2Ray server)
 	localInterfaceIp net.IP
+	// The time of last 'dialing' detected
+	// Two 'dialing' attempts during a short period (20s) may indicate a problem with connecting to the V2Ray server.
+	// Therefore, it is necessary to check the consistency of the route to the V2Ray server.
+	timeLastDialingDetected time.Time
+	updateRouteDelayTimer   *time.Timer
 }
 
 // CreateV2RayWrapper - creates new V2RayWrapper object
 // Please refer to the v2r.V2RayConfig (in v2r/config.go) struct for more information about the V2Ray data flow and configuration
 func CreateV2RayWrapper(binary string, tmpConfigFile string, cfg *V2RayConfig) *V2RayWrapper {
-	return &V2RayWrapper{
+	wrapper := &V2RayWrapper{
 		binary:         binary,
 		tempConfigFile: tmpConfigFile,
 		config:         cfg,
 	}
+
+	// initialize 'delay'-timer for calling UpdateMainRoute() function
+	timer := time.AfterFunc(detectDialingInterval, func() {
+		if err := wrapper.UpdateMainRoute(); err != nil {
+			log.Error(err)
+		}
+	})
+	timer.Stop()                          // ensure timer is stopped (no changes detected for now)
+	wrapper.updateRouteDelayTimer = timer // save timer
+
+	return wrapper
 }
 
 func (v *V2RayWrapper) GetLocalPort() (port int, isTcp bool, err error) {
@@ -172,7 +203,7 @@ func (v *V2RayWrapper) UpdateMainRoute() error {
 	isGatewayChanged := false
 	gwIp, err := netinfo.DefaultGatewayIP()
 	if err != nil {
-		return fmt.Errorf("getting default gateway ip error : %w", err)
+		return fmt.Errorf("failed to check V2Ray route consistency: %w", err)
 	}
 	if v.defaultGeteway != nil && !v.defaultGeteway.Equal(gwIp) {
 		isGatewayChanged = true
@@ -275,6 +306,24 @@ func (v *V2RayWrapper) start() (retError error) {
 	// regexp to parse output and get local port number from it (if any)
 	portRegExp := regexp.MustCompile(`^.+\s+\[Info\]\s+transport/internet/((udp)|(tcp)):\s+listening\s+((UDP)|(TCP))\s+on\s+0\.0\.0\.0:([0-9]+)\s*$`)
 	outputParseFunc := func(text string, isError bool) {
+		// Checking inconsistency with route to V2Ray server
+		// Two 'dialing' attempts during a short period (20s) may indicate a problem with connecting to the V2Ray server.
+		// Therefore, it is necessary to check the consistency of the route to the V2Ray server.
+		//
+		// Note: This is typically necessary only for Linux implementation.
+		// The function UpdateMainRoute() is usually called externally by the service when changes in the routing table are detected.
+		// However, the Linux implementation currently lacks route-change detection functionality.
+		if detectDialingRegexp.FindStringSubmatchIndex(text) != nil {
+			now := time.Now()
+			if v.timeLastDialingDetected.Add(detectDialingInterval).After(now) {
+				v.timeLastDialingDetected = time.Time{}
+				// check route not ofthen than once per 5 seconds
+				// (do not use here long delays >= 8sec, since delay before V2Ray try to make new dial attempt for QUIC protocol is 8 sec)
+				v.updateRouteDelayTimer.Reset(time.Second * 5)
+			}
+			v.timeLastDialingDetected = now
+		}
+
 		if isError {
 			log.Info("[ERR] ", text)