lib/connections: Log errors in relay clients (#5917)

lib/connections/relay_listen.go

@@ -16,6 +16,7 @@ import (
 	"github.com/syncthing/syncthing/lib/dialer"
 	"github.com/syncthing/syncthing/lib/nat"
 	"github.com/syncthing/syncthing/lib/relay/client"
+	"github.com/syncthing/syncthing/lib/util"
 )
 
 func init() {
@@ -26,6 +27,7 @@ func init() {
 }
 
 type relayListener struct {
+	util.ServiceWithError
 	onAddressesChangedNotifier
 
 	uri     *url.URL
@@ -34,30 +36,22 @@ type relayListener struct {
 	conns   chan internalConn
 	factory listenerFactory
 
-	err    error
 	client client.RelayClient
 	mut    sync.RWMutex
 }
 
-func (t *relayListener) Serve() {
-	t.mut.Lock()
-	t.err = nil
-	t.mut.Unlock()
-
+func (t *relayListener) serve(stop chan struct{}) error {
 	clnt, err := client.NewClient(t.uri, t.tlsCfg.Certificates, nil, 10*time.Second)
-	invitations := clnt.Invitations()
 	if err != nil {
-		t.mut.Lock()
-		t.err = err
-		t.mut.Unlock()
-		l.Warnln("Listen (BEP/relay):", err)
-		return
+		l.Infoln("Listen (BEP/relay):", err)
+		return err
 	}
-
-	go clnt.Serve()
+	invitations := clnt.Invitations()
 
 	t.mut.Lock()
 	t.client = clnt
+	go clnt.Serve()
+	defer clnt.Stop()
 	t.mut.Unlock()
 
 	oldURI := clnt.URI()
@@ -69,7 +63,10 @@ func (t *relayListener) Serve() {
 		select {
 		case inv, ok := <-invitations:
 			if !ok {
-				return
+				if err := clnt.Error(); err != nil {
+					l.Infoln("Listen (BEP/relay):", err)
+				}
+				return err
 			}
 
 			conn, err := client.JoinSession(inv)
@@ -114,16 +111,11 @@ func (t *relayListener) Serve() {
 				oldURI = currentURI
 				t.notifyAddressesChanged(t)
 			}
-		}
-	}
-}
 
-func (t *relayListener) Stop() {
-	t.mut.RLock()
-	if t.client != nil {
-		t.client.Stop()
+		case <-stop:
+			return nil
+		}
 	}
-	t.mut.RUnlock()
 }
 
 func (t *relayListener) URI() *url.URL {
@@ -152,18 +144,16 @@ func (t *relayListener) LANAddresses() []*url.URL {
 }
 
 func (t *relayListener) Error() error {
-	t.mut.RLock()
-	err := t.err
-	var cerr error
-	if t.client != nil {
-		cerr = t.client.Error()
-	}
-	t.mut.RUnlock()
-
+	err := t.ServiceWithError.Error()
 	if err != nil {
 		return err
 	}
-	return cerr
+	t.mut.RLock()
+	defer t.mut.RUnlock()
+	if t.client != nil {
+		return t.client.Error()
+	}
+	return nil
 }
 
 func (t *relayListener) Factory() listenerFactory {
@@ -181,13 +171,15 @@ func (t *relayListener) NATType() string {
 type relayListenerFactory struct{}
 
 func (f *relayListenerFactory) New(uri *url.URL, cfg config.Wrapper, tlsCfg *tls.Config, conns chan internalConn, natService *nat.Service) genericListener {
-	return &relayListener{
+	t := &relayListener{
 		uri:     uri,
 		cfg:     cfg,
 		tlsCfg:  tlsCfg,
 		conns:   conns,
 		factory: f,
 	}
+	t.ServiceWithError = util.AsServiceWithError(t.serve)
+	return t
 }
 
 func (relayListenerFactory) Valid(cfg config.Configuration) error {