Simplify DNS loop a bit and fixes #199

internal/dns/loop.go

@@ -93,22 +93,58 @@ func (l *looper) logAndWait(ctx context.Context, err error) {
 	<-ctx.Done()
 }
 
+func (l *looper) waitForFirstStart(ctx context.Context) {
+	for {
+		select {
+		case <-l.stop:
+			l.setEnabled(false)
+			l.logger.Info("not started yet")
+		case <-l.restart:
+			if l.isEnabled() {
+				return
+			}
+			l.logger.Info("not restarting because disabled")
+		case <-l.start:
+			l.setEnabled(true)
+			return
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+func (l *looper) waitForSubsequentStart(ctx context.Context, unboundCancel context.CancelFunc) {
+	if l.isEnabled() {
+		return
+	}
+	for {
+		// wait for a signal to re-enable
+		select {
+		case <-l.stop:
+			l.logger.Info("already disabled")
+		case <-l.restart:
+			if !l.isEnabled() {
+				l.logger.Info("not restarting because disabled")
+			} else {
+				return
+			}
+		case <-l.start:
+			l.setEnabled(true)
+			return
+		case <-ctx.Done():
+			unboundCancel()
+			return
+		}
+	}
+}
+
 func (l *looper) Run(ctx context.Context, wg *sync.WaitGroup) {
 	wg.Add(1)
 	defer wg.Done()
 	l.fallbackToUnencryptedDNS()
-	waitForStart := true
-	for waitForStart {
-		select {
-		case <-l.stop:
-			l.logger.Info("not started yet")
-		case <-l.restart:
-			waitForStart = false
-		case <-l.start:
-			waitForStart = false
-		case <-ctx.Done():
-			return
-		}
+	l.waitForFirstStart(ctx)
+	if ctx.Err() != nil {
+		return
 	}
 	defer l.logger.Warn("loop exited")
 
@@ -118,20 +154,7 @@ func (l *looper) Run(ctx context.Context, wg *sync.WaitGroup) {
 	triggeredRestart := false
 	l.setEnabled(true)
 	for ctx.Err() == nil {
-		for !l.isEnabled() {
-			// wait for a signal to re-enable
-			select {
-			case <-l.stop:
-				l.logger.Info("already disabled")
-			case <-l.restart:
-				l.setEnabled(true)
-			case <-l.start:
-				l.setEnabled(true)
-			case <-ctx.Done():
-				unboundCancel()
-				return
-			}
-		}
+		l.waitForSubsequentStart(ctx, unboundCancel)
 
 		settings := l.GetSettings()