dns: return localhost IP directly

lib/dns.js

@@ -213,6 +213,21 @@ function lookup(hostname, options, callback) {
     return {};
   }
 
+  if (hostname === 'localhost') {
+    const local4 = { address: '127.0.0.1', family: 4 };
+    const local6 = { address: '::1', family: 6 };
+
+    if (all) {
+      const addresses = family === 4 ? [ local4 ] : family === 6 ? [ local6 ] :
+        dnsOrder === 'ipv6first' ? [ local6, local4 ] : [ local4, local6 ];
+      process.nextTick(callback, null, addresses);
+    } else {
+      const { address, family: localFamily } = family === 6 || dnsOrder === 'ipv6first' ? local6 : local4;
+      process.nextTick(callback, null, address, localFamily);
+    }
+    return {};
+  }
+
   const req = new GetAddrInfoReqWrap();
   req.callback = callback;
   req.family = family;

lib/internal/dns/promises.js

@@ -147,6 +147,16 @@ function createLookupPromise(family, hostname, all, hints, dnsOrder) {
       return;
     }
 
+    if (hostname === 'localhost') {
+      const local4 = { address: '127.0.0.1', family: 4 };
+      const local6 = { address: '::1', family: 6 };
+      const addresses = family === 4 ? [ local4 ] : family === 6 ? [ local6 ] :
+        dnsOrder === 'ipv6first' ? [ local6, local4 ] : [ local4, local6 ];
+
+      resolve(all ? addresses : addresses[0]);
+      return;
+    }
+
     const req = new GetAddrInfoReqWrap();
 
     req.family = family;

test/async-hooks/test-graph.shutdown.js

@@ -36,8 +36,6 @@ function onexit() {
     hooks,
     [ { type: 'TCPSERVERWRAP', id: 'tcpserver:1', triggerAsyncId: null },
       { type: 'TCPWRAP', id: 'tcp:1', triggerAsyncId: 'tcpserver:1' },
-      { type: 'GETADDRINFOREQWRAP',
-        id: 'getaddrinforeq:1', triggerAsyncId: 'tcp:1' },
       { type: 'TCPCONNECTWRAP',
         id: 'tcpconnect:1', triggerAsyncId: 'tcp:1' },
       { type: 'TCPWRAP', id: 'tcp:2', triggerAsyncId: 'tcpserver:1' },

test/async-hooks/test-graph.tls-write.js

@@ -60,8 +60,6 @@ function onexit() {
     [ { type: 'TCPSERVERWRAP', id: 'tcpserver:1', triggerAsyncId: null },
       { type: 'TCPWRAP', id: 'tcp:1', triggerAsyncId: 'tcpserver:1' },
       { type: 'TLSWRAP', id: 'tls:1', triggerAsyncId: 'tcpserver:1' },
-      { type: 'GETADDRINFOREQWRAP',
-        id: 'getaddrinforeq:1', triggerAsyncId: 'tls:1' },
       { type: 'TCPCONNECTWRAP',
         id: 'tcpconnect:1', triggerAsyncId: 'tcp:1' },
       { type: 'TCPWRAP', id: 'tcp:2', triggerAsyncId: 'tcpserver:1' },

test/parallel/test-dns-perf_hooks.js

@@ -20,13 +20,13 @@ function inc() {
 
 // If DNS resolution fails, skip it
 // https://github.com/nodejs/node/issues/44003
-dns.lookup('localhost', common.mustCall((err) => { !err && inc(); }));
+dns.lookup('nodejs.org', common.mustCall((err) => { !err && inc(); }));
 dns.lookupService('127.0.0.1', 80, common.mustCall((err) => { !err && inc(); }));
-dns.resolveAny('localhost', common.mustCall((err) => { !err && inc(); }));
+dns.resolveAny('nodejs.org', common.mustCall((err) => { !err && inc(); }));
 
-dns.promises.lookup('localhost').then(inc).catch(() => {});
+dns.promises.lookup('nodejs.org').then(inc).catch(() => {});
 dns.promises.lookupService('127.0.0.1', 80).then(inc).catch(() => {});
-dns.promises.resolveAny('localhost').then(inc).catch(() => {});
+dns.promises.resolveAny('nodejs.org').then(inc).catch(() => {});
 
 process.on('exit', () => {
   assert.strictEqual(entries.length, count);

test/parallel/test-http2-goaway-delayed-request.js

@@ -18,5 +18,5 @@ server.listen(0, common.mustCall(() => {
   const stream = client.request();
   stream.on('error', common.expectsError({ code: 'ERR_HTTP2_GOAWAY_SESSION' }));
 
-  setImmediate(() => client.close());
+  client.close();
 }));

test/parallel/test-permission-net-dns.js

@@ -7,10 +7,10 @@ const dns = require('dns');
 const { Resolver } = dns.promises;
 
 {
-  dns.lookup('localhost', common.mustCall((err) => {
+  dns.lookup('nodejs.org', common.mustCall((err) => {
     assert.strictEqual(err.code, 'ERR_ACCESS_DENIED');
   }));
-  dns.promises.lookup('localhost').catch(common.mustCall((err) => {
+  dns.promises.lookup('nodejs.org').catch(common.mustCall((err) => {
     assert.strictEqual(err.code, 'ERR_ACCESS_DENIED');
   }));
 }

test/report/test-report-exclude-network.js

@@ -64,19 +64,8 @@ describe('report exclude network option', () => {
           (ep[ip4 ? 'ip4' : 'ip6'] === (ip4 ? '127.0.0.1' : '::1')),
       )?.[local ? 'localEndpoint' : 'remoteEndpoint'];
     };
-    try {
-      // The reverse DNS of 127.0.0.1 can be a lot of things other than localhost
-      // it could resolve to the server name for instance
-      assert.notStrictEqual(findHandle(true)?.host, '127.0.0.1');
-      assert.notStrictEqual(findHandle(false)?.host, '127.0.0.1');
 
-      if (ipv6Available) {
-        assert.notStrictEqual(findHandle(true, false)?.host, '::1');
-        assert.notStrictEqual(findHandle(false, false)?.host, '::1');
-      }
-    } catch (e) {
-      throw new Error(e?.message + ' in ' + JSON.stringify(tcp, null, 2), { cause: e });
-    }
+    // Lookup for 'localhost' does not require DNS queries, hence not tested
 
     process.report.excludeNetwork = true;
     report = process.report.getReport();