feat: add lookup option to Client, Pool and Agent (#2440)

docs/docs/api/Client.md

@@ -42,6 +42,7 @@ Every Tls option, see [here](https://nodejs.org/api/tls.html#tls_tls_connect_opt
 Furthermore, the following options can be passed:
 
 * **socketPath** `string | null` (optional) - Default: `null` - An IPC endpoint, either Unix domain socket or Windows named pipe.
+* **lookup** `Function` (optional) - Custom lookup function. Default: [dns.lookup()](https://nodejs.org/api/dns.html#dnslookuphostname-options-callback).
 * **maxCachedSessions** `number | null` (optional) - Default: `100` - Maximum number of TLS cached sessions. Use 0 to disable TLS session caching. Default: 100.
 * **timeout** `number | null` (optional) -  In milliseconds, Default `10e3`.
 * **servername** `string | null` (optional)

lib/dispatcher/agent.js

@@ -50,6 +50,7 @@ class Agent extends DispatcherBase {
     this[kOptions].interceptors = options.interceptors
       ? { ...options.interceptors }
       : undefined
+    this[kOptions].lookup = options.lookup
     this[kMaxRedirections] = maxRedirections
     this[kFactory] = factory
     this[kClients] = new Map()

lib/dispatcher/client.js

@@ -102,6 +102,7 @@ class Client extends DispatcherBase {
     maxResponseSize,
     autoSelectFamily,
     autoSelectFamilyAttemptTimeout,
+    lookup,
     // h2
     maxConcurrentStreams,
     allowH2
@@ -202,6 +203,7 @@ class Client extends DispatcherBase {
         maxCachedSessions,
         allowH2,
         socketPath,
+        lookup,
         timeout: connectTimeout,
         ...(autoSelectFamily ? { autoSelectFamily, autoSelectFamilyAttemptTimeout } : undefined),
         ...connect

lib/dispatcher/pool.js

@@ -35,6 +35,7 @@ class Pool extends PoolBase {
     autoSelectFamily,
     autoSelectFamilyAttemptTimeout,
     allowH2,
+    lookup,
     ...options
   } = {}) {
     super()
@@ -57,6 +58,7 @@ class Pool extends PoolBase {
         maxCachedSessions,
         allowH2,
         socketPath,
+        lookup,
         timeout: connectTimeout,
         ...(autoSelectFamily ? { autoSelectFamily, autoSelectFamilyAttemptTimeout } : undefined),
         ...connect

test/types/client.test-d.ts

@@ -2,6 +2,7 @@ import { Duplex, Readable, Writable } from 'stream'
 import { expectAssignable } from 'tsd'
 import { Client, Dispatcher } from '../..'
 import { URL } from 'url'
+import * as dns from 'node:dns'
 
 expectAssignable<Client>(new Client(''))
 expectAssignable<Client>(new Client('', {}))
@@ -41,6 +42,9 @@ expectAssignable<Client>(new Client(new URL('http://localhost'), {}))
   expectAssignable<Client>(new Client('', {
     socketPath: '/var/run/docker.sock'
   }))
+  expectAssignable<Client>(new Client('', {
+    lookup: dns.lookup
+  }))
   expectAssignable<Client>(new Client('', {
     pipelining: 1
   }))

types/client.d.ts

@@ -1,3 +1,4 @@
+import * as dns from "node:dns";
 import { URL } from 'url'
 import { TlsOptions } from 'tls'
 import Dispatcher from './dispatcher'
@@ -60,6 +61,8 @@ export declare namespace Client {
     keepAliveTimeoutThreshold?: number;
     /** TODO */
     socketPath?: string;
+    /** Custom DNS lookup function. Default: dns.lookup(). */
+    lookup?: Omit<typeof dns.lookup, '__promisify__'>;
     /** The amount of concurrent requests to be sent over the single TCP/TLS connection according to [RFC7230](https://tools.ietf.org/html/rfc7230#section-6.3.2). Default: `1`. */
     pipelining?: number;
     /** @deprecated use the connect option instead */