feat(dns): added support for a custom lookup function; (#5339)

lib/helpers/callbackify.js

@@ -0,0 +1,16 @@
+import utils from "../utils.js";
+
+const callbackify = (fn, reducer) => {
+  return utils.isAsyncFn(fn) ? function (...args) {
+    const cb = args.pop();
+    fn.apply(this, args).then((value) => {
+      try {
+        reducer ? cb(null, ...reducer(value)) : cb(null, value);
+      } catch (err) {
+        cb(err);
+      }
+    }, cb);
+  } : fn;
+}
+
+export default callbackify;