support multiple network interfaces

pkg/resolver/exchanger/exchanger.go

@@ -102,9 +102,7 @@ func NewExchanger(addr string, opts ...Option) (Exchanger, error) {
 		ex.addr = net.JoinHostPort(ex.addr, "53")
 	}
 	if ex.router == nil {
-		ex.router = &chain.Router{
-			Logger: options.logger,
-		}
+		ex.router = (&chain.Router{}).WithLogger(options.logger)
 	}
 
 	switch ex.network {

pkg/resolver/impl/resolver.go

@@ -64,10 +64,11 @@ func NewResolver(nameservers []NameServer, opts ...ResolverOption) (resolverpkg.
 		}
 		ex, err := exchanger.NewExchanger(
 			addr,
-			exchanger.RouterOption(&chain.Router{
-				Chain:  server.Chain,
-				Logger: options.logger,
-			}),
+			exchanger.RouterOption(
+				(&chain.Router{}).
+					WithChain(server.Chain).
+					WithLogger(options.logger),
+			),
 			exchanger.TimeoutOption(server.Timeout),
 			exchanger.LoggerOption(options.logger),
 		)