import 'package:shelf/shelf.dart'; Middleware checkAuthorization() { return (Handler handler) { return (Request request) async { if ((request.url.path.startsWith('greet') || request.url.path.startsWith('echo') || request.url.path.startsWith('upload')) && request.headers['Authorization'] != 'Bearer mysecrettoken') { return Response.forbidden('Authorization header missing or invalid'); } return handler(request); }; }; }