OAuth2: how to proxy request?

[anxxxxsoxxxxx]

Let's say I want to proxy a client authorization request to the Twitter OAuth2 server, which still does not support CORS, and then send the response back to the client. I don't want to use nginx or similar solutions; instead, I plan to use uWS as an all-in-one solution, handling proxying, HTTP, WebSocket, and file serving functionalities (who else do so?).

Not the best example:

import { randomBytes } from 'node:crypto'
import { get } from 'node:https'
import { config } from './config.js'

server.get('/authorize', (res, req) => {
    res.onAborted(() => res.aborted = true)

    const base = 'https://twitter.com/i/oauth2/authorize'
    const challenge = randomBytes(32).toString('base64url')
    const state = randomBytes(32).toString('base64url')

    const search = '?' + [
        'client_id=' + config.client_id,
        'code_challenge_method=' + 'plain',
        'code_challenge=' + challenge,
        'redirect_uri=' + config.origin,
        'response_type=' + 'code',
        'scope=' + 'tweet.read tweet.write users.read',
        'state=' + state,
    ].join('&')

    const url = encodeURI(base + search)

    get(url, (r) => {
        let body = ''

        r.on('data', (d) => body += d)

        r.on('end', () => !res.aborted && res.cork(() => {
            for (const [k, v] of Object.entries(r.headers)) res.writeHeader(k, v)

            res.end(body)
        }))
    }).on('error', (e) => {
        console.error(e)
    })
})