From f3f3d7df5bc31df339c421cb017bd79baf8827f3 Mon Sep 17 00:00:00 2001
From: Nathan Rajlich <n@n8.io>
Date: Tue, 13 Sep 2022 11:38:42 -0700
Subject: [PATCH] [cli] Replace "0.0.0.0" with "localhost" in `vc dev` (#8547)

Instead of replacing "127.0.0.1" in `vc dev`, replace "0.0.0.0" when rendering the URL to access the `vc dev` server.

The thought here is that the IPv6 form is replacing the catch-all host name (`::`), but the IPv4 version is only replacing the explicit "127.0.0.1" version, so there's an inconsistency.

Considering the catch-all host names are not usually intended to be routable anyways, we will fix the inconsistency by only replacing the catch-all versions instead of localhost.

Also, since Node.js will default to binding to the catch-all address when not explicitly specifying a host, this replacement will only happen in that case. If the user is explicitly specifing a host to bind to (i.e. `vc dev -l 127.0.0.1:8080` or `vc dev -l tcp://[::1]:8080`) then it makes more sense to print explicitly what the user specified.
---
 packages/cli/src/commands/dev/dev.ts            |  2 +-
 packages/cli/src/util/dev/parse-listen.ts       |  9 +++++----
 packages/cli/src/util/dev/server.ts             |  5 ++---
 .../cli/test/unit/util/dev/parse-listen.test.ts | 17 ++++++++++++++++-
 4 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/packages/cli/src/commands/dev/dev.ts b/packages/cli/src/commands/dev/dev.ts
index ccdf78f06..42e0af5fd 100644
--- a/packages/cli/src/commands/dev/dev.ts
+++ b/packages/cli/src/commands/dev/dev.ts
@@ -2,7 +2,7 @@ import { resolve, join } from 'path';
 import fs from 'fs-extra';
 
 import DevServer from '../../util/dev/server';
-import parseListen from '../../util/dev/parse-listen';
+import { parseListen } from '../../util/dev/parse-listen';
 import { ProjectEnvVariable } from '../../types';
 import Client from '../../util/client';
 import { getLinkedProject } from '../../util/projects/link';
diff --git a/packages/cli/src/util/dev/parse-listen.ts b/packages/cli/src/util/dev/parse-listen.ts
index ca6ac4875..0b3556bc0 100644
--- a/packages/cli/src/util/dev/parse-listen.ts
+++ b/packages/cli/src/util/dev/parse-listen.ts
@@ -1,10 +1,7 @@
 import { parse } from 'url';
 import { ListenSpec } from './types';
 
-export default function parseListen(
-  str: string,
-  defaultPort = 3000
-): ListenSpec {
+export function parseListen(str: string, defaultPort = 3000): ListenSpec {
   let port = Number(str);
 
   if (!isNaN(port)) {
@@ -50,3 +47,7 @@ export default function parseListen(
       );
   }
 }
+
+export function replaceLocalhost(address: string): string {
+  return address.replace('[::]', 'localhost').replace('0.0.0.0', 'localhost');
+}
diff --git a/packages/cli/src/util/dev/server.ts b/packages/cli/src/util/dev/server.ts
index 92b3ab721..13e28dff7 100644
--- a/packages/cli/src/util/dev/server.ts
+++ b/packages/cli/src/util/dev/server.ts
@@ -103,6 +103,7 @@ import {
 } from '../is-error';
 import isURL from './is-url';
 import { pickOverrides } from '../projects/project-settings';
+import { replaceLocalhost } from './parse-listen';
 
 const frontendRuntimeSet = new Set(
   frameworkList.map(f => f.useRuntime?.use || '@vercel/static-build')
@@ -930,9 +931,7 @@ export default class DevServer {
       }
     }
 
-    this._address = new URL(
-      address.replace('[::]', 'localhost').replace('127.0.0.1', 'localhost')
-    );
+    this._address = new URL(replaceLocalhost(address));
 
     const vercelConfig = await this.getVercelConfig();
     const devCommandPromise = this.runDevCommand();
diff --git a/packages/cli/test/unit/util/dev/parse-listen.test.ts b/packages/cli/test/unit/util/dev/parse-listen.test.ts
index 9d3f36d09..b37c2fecb 100644
--- a/packages/cli/test/unit/util/dev/parse-listen.test.ts
+++ b/packages/cli/test/unit/util/dev/parse-listen.test.ts
@@ -1,4 +1,7 @@
-import parseListen from '../../../../src/util/dev/parse-listen';
+import {
+  parseListen,
+  replaceLocalhost,
+} from '../../../../src/util/dev/parse-listen';
 
 const IS_WINDOWS = process.platform === 'win32';
 
@@ -69,3 +72,15 @@ describe('parseListen', () => {
     expect(err.message).toEqual('Unknown `--listen` scheme (protocol): bad:');
   });
 });
+
+describe('replaceLocalhost', () => {
+  test.each([
+    { input: 'http://192.168.0.1:1234', output: 'http://192.168.0.1:1234' },
+    { input: 'http://127.0.0.1:4000', output: 'http://127.0.0.1:4000' },
+    { input: 'http://[::1]:3001', output: 'http://[::1]:3001' },
+    { input: 'http://0.0.0.0:3000', output: 'http://localhost:3000' },
+    { input: 'http://[::]:3002', output: 'http://localhost:3002' },
+  ])('"$input" → "$output"', ({ input, output }) => {
+    expect(replaceLocalhost(input)).toEqual(output);
+  });
+});