fix(dns): inheritance issue with disableCache (#5351)

Author: Meo597

app/dns/config.pb.go

@@ -31,8 +31,8 @@ message NameServer {
   bool actPrior = 8;
   string tag = 9;
   uint64 timeoutMs = 10;
-  bool disableCache = 11;
-  bool serveStale = 15;
+  optional bool disableCache = 11;
+  optional bool serveStale = 15;
   optional uint32 serveExpiredTTL = 16;
   bool finalQuery = 12;
   repeated xray.app.router.GeoIP unexpected_geoip = 13;

app/dns/config.proto

@@ -121,8 +121,16 @@ func New(ctx context.Context, config *Config) (*DNS, error) {
 			myClientIP = net.IP(ns.ClientIp)
 		}
 
-		disableCache := config.DisableCache || ns.DisableCache
-		serveStale := config.ServeStale || ns.ServeStale
+		disableCache := config.DisableCache
+		if ns.DisableCache != nil {
+			disableCache = *ns.DisableCache
+		}
+
+		serveStale := config.ServeStale
+		if ns.ServeStale != nil {
+			serveStale = *ns.ServeStale
+		}
+
 		serveExpiredTTL := config.ServeExpiredTTL
 		if ns.ServeExpiredTTL != nil {
 			serveExpiredTTL = *ns.ServeExpiredTTL