nodejs doh proxy

"use strict";

const fs = require('fs');
const url = require('url');
const spdy = require('spdy');
const dgram = require('dgram');
const express = require('express');
const getRawBody = require('raw-body');
const base64url = require('base64url');

const cfg = {
    tls: {
        key: fs.readFileSync('/etc/letsencrypt/live/example.com/privkey.pem'),
        cert: fs.readFileSync('/etc/letsencrypt/live/example.com/fullchain.pem')
    },
    password: '',
    port: 443,
    'content-type': 'application/dns-message'
};

const app = express();

app.use((req, res, next) => {

    if (req.headers['accept'] !== cfg['content-type']) {
        res.statusCode = 415;
        return next('Unsupported Media Type');
    }

    next();
});

app.use((req, res, next) => {

    if (cfg.password && req.headers['authorization'] !== cfg.password) {
        res.statusCode = 403;
        return next('Access denied');
    }

    next();
});

app.use((req, res, next) => {
    getRawBody(req, {
        length: req.headers['content-length'],
        limit: 65535,
    }, (err, data) => {
        if (err) return next(err);
        req.body = data;
        next();
    })
});

app.post('/', (req, res) => {
    handle(req.body, res);
});

app.get('/', (req, res) => {
    const query = url.parse(req.url, true).query;
    const msg = base64url.toBuffer(query.dns);
    handle(msg, res);
});

function handle(msg, res)
{
    const server = dgram.createSocket('udp6');

    server.on('error', (err) => {
        res.statusCode = 500;
        res.end('Internal Server Error');
        server.close();
    });

    server.on('message', (msg) => {
        res.set('Content-Type', cfg['content-type']);
        res.end(msg);
        server.close();
    });

    server.bind(0, '::1', () => {
        server.send(msg, 53, '::1');
    });
}

spdy.createServer(cfg.tls, app).listen(cfg.port);

Were you able to get this to work? Public DoH servers send more bytes in the response than what I'm seeing in the lab, and Mozilla testing is not working.

Yes, the code worked with Firefox Nightly at the time of posting. I haven't tested it since.