fix: allow credentials for trusted CORS requests (#540)

config/default.cjs

@@ -4,6 +4,13 @@ module.exports = {
 		docsHost: 'https://www.jsdelivr.com',
 		port: 3000,
 		processes: 2,
+		cors: {
+			trustedOrigins: [
+				'https://globalping.io',
+				'https://staging.globalping.io',
+				'http://localhost:13000',
+			],
+		},
 		session: {
 			cookieName: 'dash_session_token',
 			cookieSecret: '',

src/lib/http/middleware/cors.ts

@@ -12,8 +12,39 @@ export const corsHandler = () => async (ctx: Context, next: Next) => {
 	return next();
 };
 
-export const corsAuthHandler = () => async (ctx: Context, next: Next) => {
-	ctx.set('Access-Control-Allow-Headers', '*, Authorization');
+export const corsAuthHandler = ({ trustedOrigins = [] }: CorsOptions) => {
+	const exposeHeaders = [
+		'ETag',
+		'Link',
+		'Location',
+		'Retry-After',
+		'X-RateLimit-Limit',
+		'X-RateLimit-Consumed',
+		'X-RateLimit-Remaining',
+		'X-RateLimit-Reset',
+		'X-Credits-Consumed',
+		'X-Credits-Remaining',
+		'X-Request-Cost',
+		'X-Response-Time',
+		'Deprecation',
+		'Sunset',
+	].join(', ');
 
-	return next();
+	return async (ctx: Context, next: Next) => {
+		const origin = ctx.get('Origin');
+
+		// Allow credentials only if the request is coming from a trusted origin.
+		if (trustedOrigins.includes(origin)) {
+			ctx.set('Access-Control-Allow-Origin', ctx.get('Origin'));
+			ctx.set('Access-Control-Allow-Credentials', 'true');
+			ctx.set('Vary', 'Accept-Encoding, Origin');
+		}
+
+		ctx.set('Access-Control-Allow-Headers', 'Authorization, Content-Type');
+		ctx.set('Access-Control-Expose-Headers', exposeHeaders);
+
+		return next();
+	};
 };
+
+export type CorsOptions = { trustedOrigins?: string[] };

src/measurement/route/create-measurement.ts

@@ -2,12 +2,13 @@ import config from 'config';
 import type Router from '@koa/router';
 import { getMeasurementRunner } from '../runner.js';
 import { bodyParser } from '../../lib/http/middleware/body-parser.js';
-import { corsAuthHandler } from '../../lib/http/middleware/cors.js';
+import { corsAuthHandler, CorsOptions } from '../../lib/http/middleware/cors.js';
 import { validate } from '../../lib/http/middleware/validate.js';
 import { authenticate, AuthenticateOptions } from '../../lib/http/middleware/authenticate.js';
 import { schema } from '../schema/global-schema.js';
 import type { ExtendedContext } from '../../types.js';
 
+const corsConfig = config.get<CorsOptions>('server.cors');
 const sessionConfig = config.get<AuthenticateOptions['session']>('server.session');
 const hostConfig = config.get<string>('server.host');
 const runner = getMeasurementRunner();
@@ -26,6 +27,6 @@ const handle = async (ctx: ExtendedContext): Promise<void> => {
 
 export const registerCreateMeasurementRoute = (router: Router): void => {
 	router
-		.options('/measurements', '/measurements', corsAuthHandler())
-		.post('/measurements', '/measurements', authenticate({ session: sessionConfig }), bodyParser(), validate(schema), handle);
+		.options('/measurements', '/measurements', corsAuthHandler(corsConfig))
+		.post('/measurements', '/measurements', corsAuthHandler(corsConfig), authenticate({ session: sessionConfig }), bodyParser(), validate(schema), handle);
 };

test/tests/integration/middleware/cors.test.ts

@@ -25,6 +25,21 @@ describe('cors', () => {
 
 			expect(response.headers['access-control-allow-origin']).to.equal('*');
 		});
+
+		describe('POST /v1/measurements', () => {
+			it('should include the explicit origin if it is trusted', async () => {
+				const response = await requestAgent.options('/v1/measurements').set('Origin', 'https://globalping.io').send() as Response;
+
+				expect(response.headers['access-control-allow-origin']).to.equal('https://globalping.io');
+				expect(response.headers['vary']).to.include('Origin');
+			});
+
+			it('should include the wildcard if the origin is not trusted', async () => {
+				const response = await requestAgent.options('/v1/measurements').send() as Response;
+
+				expect(response.headers['access-control-allow-origin']).to.equal('*');
+			});
+		});
 	});
 
 	describe('Access-Control-Allow-Headers header', () => {
@@ -34,10 +49,10 @@ describe('cors', () => {
 			expect(response.headers['access-control-allow-headers']).to.equal('*');
 		});
 
-		it('should include the header with value of *, Authorization', async () => {
+		it('should include the header with value of Authorization, Content-Type', async () => {
 			const response = await requestAgent.options('/v1/measurements').send() as Response;
 
-			expect(response.headers['access-control-allow-headers']).to.equal('*, Authorization');
+			expect(response.headers['access-control-allow-headers']).to.equal('Authorization, Content-Type');
 		});
 	});
 });