52 lines
2.3 KiB
Plaintext
52 lines
2.3 KiB
Plaintext
import express from 'express';
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import { hostHeaderValidation, localhostHostValidation } from './middleware/hostHeaderValidation.js';
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/**
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* Creates an Express application pre-configured for MCP servers.
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*
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* When the host is '127.0.0.1', 'localhost', or '::1' (the default is '127.0.0.1'),
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* DNS rebinding protection middleware is automatically applied to protect against
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* DNS rebinding attacks on localhost servers.
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*
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* @param options - Configuration options
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* @returns A configured Express application
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*
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* @example
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* ```typescript
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* // Basic usage - defaults to 127.0.0.1 with DNS rebinding protection
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* const app = createMcpExpressApp();
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*
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* // Custom host - DNS rebinding protection only applied for localhost hosts
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* const app = createMcpExpressApp({ host: '0.0.0.0' }); // No automatic DNS rebinding protection
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* const app = createMcpExpressApp({ host: 'localhost' }); // DNS rebinding protection enabled
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*
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* // Custom allowed hosts for non-localhost binding
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* const app = createMcpExpressApp({ host: '0.0.0.0', allowedHosts: ['myapp.local', 'localhost'] });
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* ```
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*/
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export function createMcpExpressApp(options = {}) {
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const { host = '127.0.0.1', allowedHosts } = options;
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const app = express();
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// If allowedHosts is explicitly provided, use that for validation
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if (allowedHosts) {
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app.use(hostHeaderValidation(allowedHosts));
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}
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else {
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// Apply DNS rebinding protection automatically for localhost hosts
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const localhostHosts = ['127.0.0.1', 'localhost', '::1'];
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if (localhostHosts.includes(host)) {
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app.use(localhostHostValidation());
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}
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else if (host === '0.0.0.0' || host === '::') {
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// Warn when binding to all interfaces without DNS rebinding protection
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// eslint-disable-next-line no-console
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console.warn(`Warning: Server is binding to ${host} without DNS rebinding protection. ` +
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'Consider using the allowedHosts option to restrict allowed hosts, ' +
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'or use authentication to protect your server.');
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}
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}
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// The JSON body parser runs after the Host header validation, so a request
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// with a disallowed Host is answered 403 without its body being read.
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app.use(express.json());
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return app;
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}
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//# sourceMappingURL=express.js.map |