From d1b27e53ed9e23a0c08c13c22fc0b4c00f3998b2 Mon Sep 17 00:00:00 2001
From: Charles Lyding <19598772+clydin@users.noreply.github.com>
Date: Thu, 7 Dec 2023 14:27:00 -0500
Subject: [PATCH] fix(@angular-devkit/build-angular): ensure port 0 uses random
 port with Vite development server

Vite appears to consider a port value of `0` as a falsy value and use the default Vite port of
`5173` when zero is used as a value for the development server port option. To workaround this
issue, the port checker code now explicitly handles the zero value case and determines a random
port as would be done automatically by the Webpack-based development server.

(cherry picked from commit 5b8e2d5e57d1c0b07f015eec1bd8fb889dfa8a78)
---
 .../dev-server/tests/options/port_spec.ts     |  5 ++++
 .../build_angular/src/utils/check-port.ts     | 25 +++++++++++++------
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/packages/angular_devkit/build_angular/src/builders/dev-server/tests/options/port_spec.ts b/packages/angular_devkit/build_angular/src/builders/dev-server/tests/options/port_spec.ts
index 8091983763c4..b93f4870061d 100644
--- a/packages/angular_devkit/build_angular/src/builders/dev-server/tests/options/port_spec.ts
+++ b/packages/angular_devkit/build_angular/src/builders/dev-server/tests/options/port_spec.ts
@@ -71,6 +71,11 @@ describeServeBuilder(
         expect(result?.success).toBeTrue();
         const port = getResultPort(result);
         expect(port).not.toBe('4200');
+        if (isViteRun) {
+          // Should not be default Vite port either
+          expect(port).not.toBe('5173');
+        }
+
         expect(port).toMatch(/\d{4,6}/);
         expect(await response?.text()).toContain('<title>');
 
diff --git a/packages/angular_devkit/build_angular/src/utils/check-port.ts b/packages/angular_devkit/build_angular/src/utils/check-port.ts
index 3e942266071b..29c738c1d52b 100644
--- a/packages/angular_devkit/build_angular/src/utils/check-port.ts
+++ b/packages/angular_devkit/build_angular/src/utils/check-port.ts
@@ -6,7 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import * as net from 'net';
+import assert from 'node:assert';
+import { AddressInfo, createServer } from 'node:net';
 import { loadEsmModule } from './load-esm';
 import { isTTY } from './tty';
 
@@ -15,12 +16,14 @@ function createInUseError(port: number): Error {
 }
 
 export async function checkPort(port: number, host: string): Promise<number> {
-  if (port === 0) {
-    return 0;
-  }
+  // Disabled due to Vite not handling port 0 and instead always using the default value (5173)
+  // TODO: Enable this again once Vite is fixed
+  // if (port === 0) {
+  //   return 0;
+  // }
 
   return new Promise<number>((resolve, reject) => {
-    const server = net.createServer();
+    const server = createServer();
 
     server
       .once('error', (err: NodeJS.ErrnoException) => {
@@ -46,13 +49,21 @@ export async function checkPort(port: number, host: string): Promise<number> {
             }),
           )
           .then(
-            (answers) => (answers.useDifferent ? resolve(0) : reject(createInUseError(port))),
+            (answers) =>
+              answers.useDifferent ? resolve(checkPort(0, host)) : reject(createInUseError(port)),
             () => reject(createInUseError(port)),
           );
       })
       .once('listening', () => {
+        // Get the actual address from the listening server instance
+        const address = server.address();
+        assert(
+          address && typeof address !== 'string',
+          'Port check server address should always be an object.',
+        );
+
         server.close();
-        resolve(port);
+        resolve(address.port);
       })
       .listen(port, host);
   });