feat: add lookup method

src/node/index.js

@@ -165,6 +165,7 @@ function Request(method, url) {
   this.qsRaw = this._query; // Unused, for backwards compatibility only
   this._redirectList = [];
   this._streamRequest = false;
+  this._lookup = null;
   this.once('end', this.clearTimeout.bind(this));
 }
 
@@ -300,6 +301,20 @@ Request.prototype.agent = function (agent) {
   return this;
 };
 
+/**
+ * Gets/sets the `lookup` function to use custom DNS resolver.
+ *
+ * @param {Function} lookup
+ * @return {Function}
+ * @api public
+ */
+
+Request.prototype.lookup = function (lookup) {
+  if (arguments.length === 0) return this._lookup;
+  this._lookup = lookup;
+  return this;
+};
+
 /**
  * Set _Content-Type_ response header passed through `mime.getType()`.
  *
@@ -759,6 +774,7 @@ Request.prototype.request = function () {
   options.cert = this._cert;
   options.passphrase = this._passphrase;
   options.agent = this._agent;
+  options.lookup = this._lookup;
   options.rejectUnauthorized =
     typeof this._disableTLSCerts === 'boolean'
       ? !this._disableTLSCerts

test/node/lookup.js

@@ -0,0 +1,21 @@
+'use strict';
+const assert = require('assert');
+const dns = require('dns');
+const request = require('../support/client');
+const setup = require('../support/setup');
+
+const base = setup.uri;
+
+function myLookup(hostname, options, callback) {
+  dns.lookup(hostname, options, callback);
+}
+
+describe('req.lookup()', () => {
+  it('should set a custom lookup', () => {
+    const r = request.get(`${base}/ok`).lookup(myLookup);
+    assert(r.lookup() === myLookup);
+    r.then((res) => {
+      res.text.should.equal('ok');
+    });
+  });
+});