fix(portforward): different validation when vpn is up or not

internal/portforward/loop.go

@@ -85,7 +85,7 @@ func (l *Loop) run(runCtx context.Context, runDone chan<- struct{},
 			// Stop call takes care of stopping the service
 			return
 		case partialUpdate := <-updateTrigger:
-			updatedSettings, err := l.settings.updateWith(partialUpdate)
+			updatedSettings, err := l.settings.updateWith(partialUpdate, *l.settings.VPNIsUp)
 			if err != nil {
 				updateResult <- err
 				continue

internal/portforward/service/settings.go

@@ -34,17 +34,28 @@ func (s *Settings) OverrideWith(update Settings) {
 }
 
 var (
-	ErrServerNameNotSet = errors.New("server name not set")
-	ErrFilepathNotSet   = errors.New("file path not set")
-	ErrInterfaceNotSet  = errors.New("interface not set")
+	ErrPortForwarderNotSet = errors.New("port forwarder not set")
+	ErrServerNameNotSet    = errors.New("server name not set")
+	ErrFilepathNotSet      = errors.New("file path not set")
+	ErrInterfaceNotSet     = errors.New("interface not set")
 )
 
-func (s *Settings) Validate() (err error) {
-	switch {
-	// Port forwarder can be nil when the loop updates
-	// to stop the service.
-	case s.Filepath == "":
+func (s *Settings) Validate(forStartup bool) (err error) {
+	// Minimal validation
+	if s.Filepath == "" {
 		return fmt.Errorf("%w", ErrFilepathNotSet)
+	}
+
+	if !forStartup {
+		// No additional validation needed if the service
+		// is not to be started with the given settings.
+		return nil
+	}
+
+	// Startup validation requires additional fields set.
+	switch {
+	case s.PortForwarder == nil:
+		return fmt.Errorf("%w", ErrPortForwarderNotSet)
 	case s.Interface == "":
 		return fmt.Errorf("%w", ErrInterfaceNotSet)
 	case s.PortForwarder.Name() == providers.PrivateInternetAccess && s.ServerName == "":

internal/portforward/settings.go

@@ -17,10 +17,11 @@ type Settings struct {
 // fields set in the partialUpdate argument, validates the new settings
 // and returns them if they are valid, or returns an error otherwise.
 // In all cases, the receiving settings are unmodified.
-func (s Settings) updateWith(partialUpdate Settings) (updated Settings, err error) {
+func (s Settings) updateWith(partialUpdate Settings,
+	forStartup bool) (updated Settings, err error) {
 	updated = s.copy()
 	updated.overrideWith(partialUpdate)
-	err = updated.validate()
+	err = updated.validate(forStartup)
 	if err != nil {
 		return updated, err
 	}
@@ -38,6 +39,6 @@ func (s *Settings) overrideWith(update Settings) {
 	s.Service.OverrideWith(update.Service)
 }
 
-func (s Settings) validate() (err error) {
-	return s.Service.Validate()
+func (s Settings) validate(forStartup bool) (err error) {
+	return s.Service.Validate(forStartup)
 }