From 60594ce643a051ecb0f7ff365660470b62334406 Mon Sep 17 00:00:00 2001
From: Szymon Marczak <36894700+szmarczak@users.noreply.github.com>
Date: Sat, 31 Jul 2021 21:59:31 +0200
Subject: [PATCH] Fix unhandled exception when lookup returns invalid IP early

Fixes #1737
---
 source/core/index.ts | 14 ++++++++++++--
 test/http.ts         | 12 ++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/source/core/index.ts b/source/core/index.ts
index 9553c915e..39a944a7a 100644
--- a/source/core/index.ts
+++ b/source/core/index.ts
@@ -1113,11 +1113,21 @@ export default class Request extends Duplex implements RequestEvents<Request> {
 		const fn = options.cache ? this._createCacheableRequest : request;
 
 		try {
-			let requestOrResponse = await fn(url, this._requestOptions);
+			// We can't do `await fn(...)`,
+			// because stream `error` event can be emitted before `Promise.resolve()`.
+			let requestOrResponse = fn(url, this._requestOptions);
+
+			if (is.promise(requestOrResponse)) {
+				requestOrResponse = await requestOrResponse;
+			}
 
 			// Fallback
 			if (is.undefined(requestOrResponse)) {
-				requestOrResponse = await options.getFallbackRequestFunction()(url, this._requestOptions);
+				requestOrResponse = options.getFallbackRequestFunction()(url, this._requestOptions);
+
+				if (is.promise(requestOrResponse)) {
+					requestOrResponse = await requestOrResponse;
+				}
 			}
 
 			if (isClientRequest(requestOrResponse!)) {
diff --git a/test/http.ts b/test/http.ts
index ff8e2e06e..eab945a97 100644
--- a/test/http.ts
+++ b/test/http.ts
@@ -357,3 +357,15 @@ test('JSON request custom stringifier', withServer, async (t, server, got) => {
 		json: payload,
 	})).body, customStringify(payload));
 });
+
+test('ClientRequest can throw before promise resolves', async t => {
+	await t.throwsAsync(got('http://example.com', {
+		dnsLookup: ((_hostname: string, _options: unknown, callback: Function) => {
+			queueMicrotask(() => {
+				callback(null, 'fe80::0000:0000:0000:0000', 6);
+			});
+		}) as any
+	}), {
+		code: 'EINVAL'
+	});
+});