_worker.js

// export default {
//   async fetch(request, env) {
//     let url = new URL(request.url);
//     if (url.pathname.startsWith('/')) {
//       url.hostname = 'api.telegram.org'
//       let new_request = new Request(url, request);
//       return fetch(new_request);
//     }
//     return env.ASSETS.fetch(request);
//   },
// };

const whitelist = ["/bot5275515832:"];
const tg_host = "api.telegram.org";
addEventListener('fetch', event => {
    event.respondWith(handleRequest(event.request))
})
function validate(path) {
    for (var i = 0; i < whitelist.length; i++) {
        if (path.startsWith(whitelist[i]))
            return true;
    }
    return false;
}
async function handleRequest(request) {
    var u = new URL(request.url);
    u.host = tg_host;
    if (!validate(u.pathname))
        return new Response('Unauthorized', {
            status: 403
        });
    var req = new Request(u, {
        method: request.method,
        headers: request.headers,
        body: request.body
    });
    const result = await fetch(req);
    return result;
}