feat: add --(allowed|blocked)-origins (#319)

Useful to limit the agent when using the playwright-mcp server with an
agent in auto-invocation mode.

Not intended to be a security feature.

tests/request-blocking.spec.ts

@@ -0,0 +1,91 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { Client } from '@modelcontextprotocol/sdk/client/index.js';
+import { test, expect } from './fixtures.ts';
+
+const BLOCK_MESSAGE = /Blocked by Web Inspector|NS_ERROR_FAILURE|net::ERR_BLOCKED_BY_CLIENT/g;
+
+const fetchPage = async (client: Client, url: string) => {
+  const result = await client.callTool({
+    name: 'browser_navigate',
+    arguments: {
+      url,
+    },
+  });
+
+  return JSON.stringify(result, null, 2);
+};
+
+test('default to allow all', async ({ server, client }) => {
+  server.route('/ppp', (_req, res) => {
+    res.writeHead(200, { 'Content-Type': 'text/html' });
+    res.end('content:PPP');
+  });
+  const result = await fetchPage(client, server.PREFIX + '/ppp');
+  expect(result).toContain('content:PPP');
+});
+
+test('blocked works', async ({ startClient }) => {
+  const client = await startClient({
+    args: ['--blocked-origins', 'microsoft.com;example.com;playwright.dev']
+  });
+  const result = await fetchPage(client, 'https://example.com/');
+  expect(result).toMatch(BLOCK_MESSAGE);
+});
+
+test('allowed works', async ({ server, startClient }) => {
+  server.route('/ppp', (_req, res) => {
+    res.writeHead(200, { 'Content-Type': 'text/html' });
+    res.end('content:PPP');
+  });
+  const client = await startClient({
+    args: ['--allowed-origins', `microsoft.com;${new URL(server.PREFIX).host};playwright.dev`]
+  });
+  const result = await fetchPage(client, server.PREFIX + '/ppp');
+  expect(result).toContain('content:PPP');
+});
+
+test('blocked takes precedence', async ({ startClient }) => {
+  const client = await startClient({
+    args: [
+      '--blocked-origins', 'example.com',
+      '--allowed-origins', 'example.com',
+    ],
+  });
+  const result = await fetchPage(client, 'https://example.com/');
+  expect(result).toMatch(BLOCK_MESSAGE);
+});
+
+test('allowed without blocked blocks all non-explicitly specified origins', async ({ startClient }) => {
+  const client = await startClient({
+    args: ['--allowed-origins', 'playwright.dev'],
+  });
+  const result = await fetchPage(client, 'https://example.com/');
+  expect(result).toMatch(BLOCK_MESSAGE);
+});
+
+test('blocked without allowed allows non-explicitly specified origins', async ({ server, startClient }) => {
+  server.route('/ppp', (_req, res) => {
+    res.writeHead(200, { 'Content-Type': 'text/html' });
+    res.end('content:PPP');
+  });
+  const client = await startClient({
+    args: ['--blocked-origins', 'example.com'],
+  });
+  const result = await fetchPage(client, server.PREFIX + '/ppp');
+  expect(result).toContain('content:PPP');
+});