dnsforward: client id priority

internal/dnsforward/stats.go

@@ -29,7 +29,12 @@ func (s *Server) processQueryLogsAndStats(dctx *dnsContext) (rc resultCode) {
 
 	log.Debug("dnsforward: client ip for stats and querylog: %s", ipStr)
 
-	ids := []string{ipStr, dctx.clientID}
+	ids := []string{ipStr}
+	if dctx.clientID != "" {
+		// Use the ClientID first because it has a higher priority.
+		ids = []string{dctx.clientID, ipStr}
+	}
+
 	qt, cl := q.Qtype, q.Qclass
 
 	// Synchronize access to s.queryLog and s.stats so they won't be suddenly