chore(mcp): support --allowed-hosts=*

packages/playwright/src/mcp/program.ts

@@ -29,7 +29,7 @@ import type { MCPProvider } from './sdk/proxyBackend';
 
 export function decorateCommand(command: Command, version: string) {
   command
-      .option('--allowed-hosts <hosts...>', 'comma-separated list of hosts this server is allowed to serve from. Defaults to the host the server is bound to.', commaSeparatedList)
+      .option('--allowed-hosts <hosts...>', 'comma-separated list of hosts this server is allowed to serve from. Defaults to the host the server is bound to. Pass \'*\' to disable the host check.', commaSeparatedList)
       .option('--allowed-origins <origins>', 'semicolon-separated list of origins to allow the browser to request. Default is to allow all.', semicolonSeparatedList)
       .option('--blocked-origins <origins>', 'semicolon-separated list of origins to block the browser from requesting. Blocklist is evaluated before allowlist. If used without the allowlist, requests not matching the blocklist are still allowed.', semicolonSeparatedList)
       .option('--block-service-workers', 'block service workers')

packages/playwright/src/mcp/sdk/http.ts

@@ -63,21 +63,24 @@ export async function installHttpTransport(httpServer: http.Server, serverBacken
   const url = httpAddressToString(httpServer.address());
   const host = new URL(url).host;
   allowedHosts = (allowedHosts || [host]).map(h => h.toLowerCase());
+  const allowAnyHost = allowedHosts.includes('*');
 
   const sseSessions = new Map();
   const streamableSessions = new Map();
   httpServer.on('request', async (req, res) => {
-    const host = req.headers.host?.toLowerCase();
-    if (!host) {
-      res.statusCode = 400;
-      return res.end('Missing host');
-    }
+    if (!allowAnyHost) {
+      const host = req.headers.host?.toLowerCase();
+      if (!host) {
+        res.statusCode = 400;
+        return res.end('Missing host');
+      }
 
-    // Prevent DNS evil.com -> localhost rebind.
-    if (!allowedHosts.includes(host)) {
-      // Access from the browser is forbidden.
-      res.statusCode = 403;
-      return res.end('Access is only allowed at ' + allowedHosts.join(', '));
+      // Prevent DNS evil.com -> localhost rebind.
+      if (!allowedHosts.includes(host)) {
+        // Access from the browser is forbidden.
+        res.statusCode = 403;
+        return res.end('Access is only allowed at ' + allowedHosts.join(', '));
+      }
     }
 
     const url = new URL(`http://localhost${req.url}`);

tests/mcp/http.spec.ts

@@ -378,6 +378,14 @@ test('should respect allowed hosts (positive)', async ({ serverEndpoint }) => {
   expect(response.status).toBe(400);
 });
 
+test('should be able to allow any host', async ({ serverEndpoint }) => {
+  const { url } = await serverEndpoint({ args: ['--allowed-hosts=*'] });
+  const response = await fetch(url.href);
+  // 400 is expected for the mcp fetch.
+  expect(response.status).toBe(400);
+  expect(await response.text()).toBe('Invalid request');
+});
+
 async function findFreePort(): Promise<number> {
   return new Promise((resolve, reject) => {
     const server = net.createServer();