replace same tag default outbound handler (#1437)

* replace old default handler with same tag

Signed-off-by: Guofan Xu <xuguofan@live.com>

* add warning log when replace outbound

* fix lint

Signed-off-by: Guofan Xu <xuguofan@live.com>

app/proxyman/outbound/outbound.go

@@ -102,13 +102,18 @@ func (m *Manager) GetHandler(tag string) outbound.Handler {
 func (m *Manager) AddHandler(ctx context.Context, handler outbound.Handler) error {
 	m.access.Lock()
 	defer m.access.Unlock()
+	tag := handler.Tag()
 
-	if m.defaultHandler == nil {
+	if m.defaultHandler == nil ||
+		(len(tag) > 0 && tag == m.defaultHandler.Tag()) {
 		m.defaultHandler = handler
 	}
 
-	tag := handler.Tag()
 	if len(tag) > 0 {
+		if oldHandler, found := m.taggedHandler[tag]; found {
+			errors.New("will replace the existed outbound with the tag: " + tag).AtWarning().WriteToLog()
+			_ = oldHandler.Close()
+		}
 		m.taggedHandler[tag] = handler
 	} else {
 		m.untaggedHandlers = append(m.untaggedHandlers, handler)