dns: remove redundant code using common variable

`validFamilies` variable is defined 2 times, so remove
redundant code by defining `validFamilies` in util. Plus,
apply the same approach to `validDnsOrders` because it's
also used multiple times.

PR-URL: #57386
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Daeyeon Jeong <daeyeon.dev@gmail.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>

Author: deokjinkim

lib/dns.js

@@ -46,6 +46,8 @@ const {
   getDefaultResultOrder,
   setDefaultResultOrder,
   errorCodes: dnsErrorCodes,
+  validDnsOrders,
+  validFamilies,
 } = require('internal/dns/utils');
 const {
   Resolver,
@@ -138,7 +140,6 @@ function onlookupall(err, addresses) {
 
 // Easy DNS A/AAAA look up
 // lookup(hostname, [options,] callback)
-const validFamilies = [0, 4, 6];
 function lookup(hostname, options, callback) {
   let hints = 0;
   let family = 0;
@@ -192,7 +193,7 @@ function lookup(hostname, options, callback) {
       dnsOrder = options.verbatim ? 'verbatim' : 'ipv4first';
     }
     if (options?.order != null) {
-      validateOneOf(options.order, 'options.order', ['ipv4first', 'ipv6first', 'verbatim']);
+      validateOneOf(options.order, 'options.order', validDnsOrders);
       dnsOrder = options.order;
     }
   }

lib/internal/dns/promises.js

@@ -16,6 +16,8 @@ const {
   getDefaultResultOrder,
   setDefaultResultOrder,
   setDefaultResolver,
+  validDnsOrders,
+  validFamilies,
 } = require('internal/dns/utils');
 
 const {
@@ -179,7 +181,6 @@ function createLookupPromise(family, hostname, all, hints, dnsOrder) {
   });
 }
 
-const validFamilies = [0, 4, 6];
 /**
  * Get the IP address for a given hostname.
  * @param {string} hostname - The hostname to resolve (ex. 'nodejs.org').
@@ -227,7 +228,7 @@ function lookup(hostname, options) {
       dnsOrder = options.verbatim ? 'verbatim' : 'ipv4first';
     }
     if (options?.order != null) {
-      validateOneOf(options.order, 'options.order', ['ipv4first', 'ipv6first', 'verbatim']);
+      validateOneOf(options.order, 'options.order', validDnsOrders);
       dnsOrder = options.order;
     }
   }

lib/internal/dns/utils.js

@@ -201,14 +201,16 @@ class ResolverBase {
 
 let defaultResolver;
 let dnsOrder;
+const validDnsOrders = ['verbatim', 'ipv4first', 'ipv6first'];
+const validFamilies = [0, 4, 6];
 
 function initializeDns() {
   const orderFromCLI = getOptionValue('--dns-result-order');
   if (!orderFromCLI) {
     dnsOrder ??= 'verbatim';
   } else {
     // Allow the deserialized application to override order from CLI.
-    validateOneOf(orderFromCLI, '--dns-result-order', ['verbatim', 'ipv4first', 'ipv6first']);
+    validateOneOf(orderFromCLI, '--dns-result-order', validDnsOrders);
     dnsOrder = orderFromCLI;
   }
 
@@ -281,7 +283,7 @@ function emitInvalidHostnameWarning(hostname) {
 }
 
 function setDefaultResultOrder(value) {
-  validateOneOf(value, 'dnsOrder', ['verbatim', 'ipv4first', 'ipv6first']);
+  validateOneOf(value, 'dnsOrder', validDnsOrders);
   dnsOrder = value;
 }
 
@@ -356,4 +358,6 @@ module.exports = {
   errorCodes,
   createResolverClass,
   initializeDns,
+  validDnsOrders,
+  validFamilies,
 };