diff --git a/common/upstream.go b/common/upstream.go
index 0bf7a5b..9af3604 100644
--- a/common/upstream.go
+++ b/common/upstream.go
@@ -31,3 +31,13 @@ func MustCast[T any](obj any) T {
 	}
 	return value
 }
+
+func Top(obj any) any {
+	if u, ok := obj.(WithUpstream); ok {
+		return Top(u.Upstream())
+	}
+	if u, ok := obj.(stdWithUpstreamNetConn); ok {
+		return Top(u.NetConn())
+	}
+	return obj
+}