Fix DNS timing being non-zero when connecting to IP addresses

Fixes #2279

Author: sindresorhus

source/core/index.ts

@@ -712,6 +712,19 @@ export default class Request extends Duplex implements RequestEvents<Request> {
 		this._responseSize = Number(response.headers['content-length']) || undefined;
 		this.response = typedResponse;
 
+		// Workaround for http-timer bug: when connecting to an IP address (no DNS lookup),
+		// http-timer sets lookup = connect instead of lookup = socket, resulting in
+		// dns = lookup - socket being a small positive number instead of 0.
+		// See https://github.com/sindresorhus/got/issues/2279
+		const {timings} = response;
+		if (timings?.lookup !== undefined && timings.socket !== undefined && timings.connect !== undefined && timings.lookup === timings.connect && timings.phases.dns !== 0) {
+			// Fix the DNS phase to be 0 and set lookup to socket time
+			timings.phases.dns = 0;
+			timings.lookup = timings.socket;
+			// Recalculate TCP time to be the full time from socket to connect
+			timings.phases.tcp = timings.connect - timings.socket;
+		}
+
 		response.once('error', (error: Error) => {
 			this._aborted = true;
 

test/timings.ts

@@ -1,4 +1,5 @@
 import test from 'ava';
+import got from '../source/index.js';
 import withServer, {withHttpsServer} from './helpers/with-server.js';
 
 test('http/1 timings', withServer, async (t, server, got) => {
@@ -85,3 +86,19 @@ test('timings.end is set when stream is destroyed before completion', withServer
 
 	t.pass();
 });
+
+test('dns timing is 0 for IP addresses', withServer, async (t, server) => {
+	server.get('/', (_request, response) => {
+		response.end('ok');
+	});
+
+	// Get the actual IP address the server is bound to
+	const address = server.http.address() as {address: string; family: string; port: number};
+	const host = address.family === 'IPv6' ? `[${address.address}]` : address.address;
+	const {timings} = await got(`http://${host}:${server.port}/`);
+
+	// When connecting to an IP address, there is no DNS lookup
+	t.is(timings.phases.dns, 0);
+	// Lookup timestamp should equal socket timestamp (no time elapsed for DNS)
+	t.is(timings.lookup, timings.socket);
+});