[FEAT] added connect option noResolve which disables name resolutio…

…n on the client

FIX #625

README.md

@@ -791,6 +791,7 @@ The following is the list of connection options and default values.
 | `noAsyncTraces`         | `false`            | When `true` the client will not add additional context to errors associated with request operations. Setting this option to `true` will greatly improve performance of request/reply and JetStream publishers.                                                                                                                                                                           |
 | `noEcho`                | `false`            | Subscriptions receive messages published by the client. Requires server support (1.2.0). If set to true, and the server does not support the feature, an error with code `NO_ECHO_NOT_SUPPORTED` is emitted, and the connection is aborted. Note that it is possible for this error to be emitted on reconnect when the server reconnects to a server that does not support the feature. |
 | `noRandomize`           | `false`            | If set, the order of user-specified servers is randomized.                                                                                                                                                                                                                                                                                                                               |
+| `noResolve`             | none               | If true, client will not resolve host names.                                                                                                                                                                                                                                                                                                                                             |
 | `pass`                  |                    | Sets the password for a connection.                                                                                                                                                                                                                                                                                                                                                      |
 | `pedantic`              | `false`            | Turns on strict subject format checks.                                                                                                                                                                                                                                                                                                                                                   |
 | `pingInterval`          | `120000`           | Number of milliseconds between client-sent pings.                                                                                                                                                                                                                                                                                                                                        |

nats-base-client/core.ts

@@ -1402,6 +1402,12 @@ export interface ConnectionOptions {
    * additional context as to where the operation was started.
    */
   noAsyncTraces?: boolean;
+
+  /**
+   * When true, the connect function will remove any name resolution provided by
+   * the transport. In some environments (browsers) this is a no-op option.
+   */
+  noResolve?: boolean;
 }
 
 /**

nats-base-client/internal_mod.ts

@@ -4,7 +4,7 @@ export { Nuid, nuid } from "./nuid.ts";
 export type { ServiceClient, TypedSubscriptionOptions } from "./types.ts";
 
 export { MsgImpl } from "./msg.ts";
-export { setTransportFactory } from "./transport.ts";
+export { getResolveFn, setTransportFactory } from "./transport.ts";
 export type { Transport, TransportFactory } from "./transport.ts";
 export { Connect, INFO, ProtocolHandler } from "./protocol.ts";
 export type { Backoff, Deferred, Delay, Perf, Timeout } from "./util.ts";

src/connect.ts

@@ -27,7 +27,7 @@ export function connect(opts: ConnectionOptions = {}): Promise<NatsConnection> {
     factory: (): Transport => {
       return new DenoTransport();
     },
-    dnsResolveFn: denoResolveHost,
+    dnsResolveFn: opts.noResolve === true ? undefined : denoResolveHost,
   } as TransportFactory);
 
   return NatsConnectionImpl.connect(opts);

tests/basics_test.ts

@@ -48,6 +48,7 @@ import {
   collect,
   deferred,
   delay,
+  getResolveFn,
   headers,
   isIP,
   NatsConnectionImpl,
@@ -1425,6 +1426,12 @@ Deno.test("basics - respond message", async () => {
   await cleanup(ns, nc);
 });
 
+Deno.test("basics - noResolve", async () => {
+  const { ns, nc } = await setup({}, { noResolve: true });
+  assertEquals(getResolveFn(), undefined);
+  await cleanup(ns, nc);
+});
+
 class MM implements Msg {
   data!: Uint8Array;
   sid: number;