test: introduce test/common/internet.addresses

This commit introduces test/common/internet.address, which
includes a set of addresses for doing internet tests.
These addresses can be overriden using NODE_TEST_* environment
variables.

PR-URL: https://github.com/nodejs/node/pull/16390
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/common/README.md

@@ -10,6 +10,7 @@ This directory contains modules used to test the Node.js implementation.
 * [DNS module](#dns-module)
 * [Duplex pair helper](#duplex-pair-helper)
 * [Fixtures module](#fixtures-module)
+* [Internet module](#internet-module)
 * [WPT module](#wpt-module)
 
 ## Benchmark Module
@@ -498,6 +499,40 @@ Returns the result of
 Returns the result of
 `fs.readFileSync(path.join(fixtures.fixturesDir, 'keys', arg), 'enc')`.
 
+## Internet Module
+
+The `common/internet` module provides utilities for working with
+internet-related tests.
+
+### internet.addresses
+
+* [<Object>]
+  * `INET_HOST` [<String>] A generic host that has registered common
+    DNS records, supports both IPv4 and IPv6, and provides basic HTTP/HTTPS
+    services
+  * `INET4_HOST` [<String>] A host that provides IPv4 services
+  * `INET6_HOST` [<String>] A host that provides IPv6 services
+  * `INET4_IP` [<String>] An accessible IPv4 IP, defaults to the
+    Google Public DNS IPv4 address
+  * `INET6_IP` [<String>] An accessible IPv6 IP, defaults to the
+    Google Public DNS IPv6 address
+  * `INVALID_HOST` [<String>] An invalid host that cannot be resolved
+  * `MX_HOST` [<String>] A host with MX records registered
+  * `SRV_HOST` [<String>] A host with SRV records registered
+  * `PTR_HOST` [<String>] A host with PTR records registered
+  * `NAPTR_HOST` [<String>] A host with NAPTR records registered
+  * `SOA_HOST` [<String>] A host with SOA records registered
+  * `CNAME_HOST` [<String>] A host with CNAME records registered
+  * `NS_HOST` [<String>] A host with NS records registered
+  * `TXT_HOST` [<String>] A host with TXT records registered
+  * `DNS4_SERVER` [<String>] An accessible IPv4 DNS server
+  * `DNS6_SERVER` [<String>] An accessible IPv6 DNS server
+
+A set of addresses for internet-related tests. All properties are configurable
+via `NODE_TEST_*` environment variables. For example, to configure
+`internet.addresses.INET_HOST`, set the environment
+vairable `NODE_TEST_INET_HOST` to a specified host.
+
 ## WPT Module
 
 The wpt.js module is a port of parts of

test/common/dns.js

@@ -287,4 +287,6 @@ function writeDNSPacket(parsed) {
   }));
 }
 
-module.exports = { types, classes, writeDNSPacket, parseDNSPacket };
+module.exports = {
+  types, classes, writeDNSPacket, parseDNSPacket
+};

test/common/internet.js

@@ -0,0 +1,54 @@
+/* eslint-disable required-modules */
+'use strict';
+
+// Utilities for internet-related tests
+
+const addresses = {
+  // A generic host that has registered common DNS records,
+  // supports both IPv4 and IPv6, and provides basic HTTP/HTTPS services
+  INET_HOST: 'nodejs.org',
+  // A host that provides IPv4 services
+  INET4_HOST: 'nodejs.org',
+  // A host that provides IPv6 services
+  INET6_HOST: 'nodejs.org',
+  // An accessible IPv4 IP,
+  // defaults to the Google Public DNS IPv4 address
+  INET4_IP: '8.8.8.8',
+  // An accessible IPv6 IP,
+  // defaults to the Google Public DNS IPv6 address
+  INET6_IP: '2001:4860:4860::8888',
+  // An invalid host that cannot be resolved
+  // See https://tools.ietf.org/html/rfc2606#section-2
+  INVALID_HOST: 'something.invalid',
+  // A host with MX records registered
+  MX_HOST: 'nodejs.org',
+  // A host with SRV records registered
+  SRV_HOST: '_jabber._tcp.google.com',
+  // A host with PTR records registered
+  PTR_HOST: '8.8.8.8.in-addr.arpa',
+  // A host with NAPTR records registered
+  NAPTR_HOST: 'sip2sip.info',
+  // A host with SOA records registered
+  SOA_HOST: 'nodejs.org',
+  // A host with CNAME records registered
+  CNAME_HOST: 'blog.nodejs.org',
+  // A host with NS records registered
+  NS_HOST: 'nodejs.org',
+  // A host with TXT records registered
+  TXT_HOST: 'nodejs.org',
+  // An accessible IPv4 DNS server
+  DNS4_SERVER: '8.8.8.8',
+  // An accessible IPv4 DNS server
+  DNS6_SERVER: '2001:4860:4860::8888'
+};
+
+for (const key of Object.keys(addresses)) {
+  const envName = `NODE_TEST_${key}`;
+  if (process.env[envName]) {
+    addresses[key] = process.env[envName];
+  }
+}
+
+module.exports = {
+  addresses
+};