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server.js
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server.js
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// Dependencies
const proxy = require('http-proxy');
const https = require('https');
const http = require('http');
const crypto = require('crypto');
const assert = require('assert');
const zlib = require('zlib');
const { URL } = require('url');
// Manual constants
const ALLOWED_METHODS = http.METHODS;
const ALLOWED_PROTOS = ['http', 'https'];
const ALLOWED_GZIP_METHODS = ['transform', 'decode', 'append'];
const DEFAULT_PROTO = 'https';
const DEFAULT_USERAGENT = 'Mozilla';
const getHosts = (hosts) => {
if (!hosts) {
return [];
}
let parsed = [];
hosts = hosts.split(',');
for (let i = 0; i < hosts.length; i++) {
const host = hosts[i];
try {
(() => new URL(`${DEFAULT_PROTO}://${host}`))();
} catch (e) {
throw new Error(`Configuration error! Invalid host domain on item ${host}`);
}
parsed.push({
host: host
});
}
return parsed;
};
// Environment Constants
const PORT = process.env.PORT || 80;
const ACCESS_KEY = process.env.ACCESS_KEY && Buffer.from(process.env.ACCESS_KEY);
const USE_WHITELIST = process.env.USE_WHITELIST === 'true';
const USE_OVERRIDE_STATUS = process.env.USE_OVERRIDE_STATUS === 'true';
const REWRITE_ACCEPT_ENCODING = process.env.REWRITE_ACCEPT_ENCODING === 'true';
const APPEND_HEAD = process.env.APPEND_HEAD === 'true';
const ALLOWED_HOSTS = getHosts(process.env.ALLOWED_HOSTS);
const GZIP_METHOD = process.env.GZIP_METHOD;
assert.ok(ACCESS_KEY, 'Missing ACCESS_KEY');
assert.ok(ALLOWED_GZIP_METHODS.includes(GZIP_METHOD), `GZIP_METHOD must be one of the following values: ${JSON.stringify(ALLOWED_GZIP_METHODS)}`);
const server = http.createServer();
const httpsProxy = proxy.createProxyServer({
agent: new https.Agent({
checkServerIdentity: (host, cert) => {
return undefined;
}
}),
changeOrigin: true
});
const httpProxy = proxy.createProxyServer({
changeOrigin: true
});
const writeErr = (res, status, message) => {
res.writeHead(status, {'Content-Type': 'text/plain'});
res.end(message);
};
const onProxyError = (err, req, res) => {
console.error(err);
writeErr(res, 500, 'Proxying failed');
};
const appendHead = (proxyRes, res, append) => {
const encoding = proxyRes.headers['content-encoding'];
let handler;
let encoder;
let appendEncoded;
switch (encoding) {
case 'gzip':
handler = zlib.gzip;
break;
default:
appendEncoded = append;
}
if (handler) {
encoder = new Promise((resolve, reject) => {
handler(append, (e, buf) => {
if (e) {
reject(e);
}
appendEncoded = buf;
resolve();
});
});
}
if ('content-length' in proxyRes.headers) {
delete proxyRes.headers['content-length'];
}
const _end = res.end;
res.end = async () => {
if (!appendEncoded) {
try {
await encoder;
} catch (e) {
console.error(`Encoder error: ${e}`);
return;
}
}
res.write(appendEncoded);
_end.call(res);
};
};
const transformEncoded = (proxyRes, res, append) => {
const encoding = proxyRes.headers['content-encoding'];
let decodeHandler;
let encodeHandler;
let encoder;
let decoder;
switch (encoding) {
case 'gzip':
decodeHandler = zlib.createGunzip;
encodeHandler = zlib.createGzip;
break;
}
if (decodeHandler) {
decoder = decodeHandler();
encoder = encodeHandler();
const _write = res.write.bind(res);
const _end = res.end.bind(res);
res.write = (chunk) => {
decoder.write(chunk);
};
res.end = () => {
decoder.end();
};
if (GZIP_METHOD === 'transform') {
decoder.on('end', () => {
encoder.write(append);
encoder.end();
});
decoder.pipe(encoder, {end: false});
encoder.on('data', (chunk) => {
_write(chunk);
});
encoder.on('end', () => {
_end();
});
} else if (GZIP_METHOD === 'decode') {
decoder.on('data', (chunk) => {
_write(chunk);
});
decoder.on('end', () => {
_write(append);
_end();
});
if ('content-encoding' in proxyRes.headers) {
delete proxyRes.headers['content-encoding'];
}
}
}
if ('content-length' in proxyRes.headers) {
delete proxyRes.headers['content-length'];
}
};
const processResponse = (proxyRes, res, append) => {
if (['transform', 'decode'].includes(GZIP_METHOD) && proxyRes.headers['content-encoding']) {
transformEncoded(proxyRes, res, append);
} else {
appendHead(proxyRes, res, append);
}
};
const onProxyReq = (proxyReq, req, res, options) => {
proxyReq.setHeader('User-Agent', proxyReq.getHeader('proxy-override-user-agent') || DEFAULT_USERAGENT);
if (REWRITE_ACCEPT_ENCODING) {
proxyReq.setHeader('Accept-Encoding', 'gzip');
}
proxyReq.removeHeader('roblox-id');
proxyReq.removeHeader('proxy-access-key');
proxyReq.removeHeader('proxy-target');
};
const onProxyRes = (proxyRes, req, res) => {
const head = {
headers: Object.assign({}, proxyRes.headers),
status: {
code: proxyRes.statusCode,
message: proxyRes.statusMessage
}
};
if (USE_OVERRIDE_STATUS) {
proxyRes.statusCode = 200;
}
if (APPEND_HEAD) {
const append = `"""${JSON.stringify(head)}"""`;
processResponse(proxyRes, res, append);
}
};
httpsProxy.on('error', onProxyError);
httpsProxy.on('proxyReq', onProxyReq);
httpsProxy.on('proxyRes', onProxyRes);
httpProxy.on('error', onProxyError);
httpProxy.on('proxyReq', onProxyReq);
httpProxy.on('proxyRes', onProxyRes);
const doProxy = (target, proto, req, res) => {
var options = {
target: proto + '://' + target.host
};
if (proto === 'https') {
httpsProxy.web(req, res, options);
} else if (proto === 'http') {
httpProxy.web(req, res, options);
} else {
throw new Error(`Do proxy error: Unsupported protocol ${proto}`);
}
};
server.on('request', (req, res) => {
const method = req.headers['proxy-target-override-method'];
if (method) {
if (ALLOWED_METHODS.includes(method)) {
req.method = method;
} else {
writeErr(res, 400, 'Invalid target method');
return;
}
}
const overrideProto = req.headers['proxy-target-override-proto'];
if (overrideProto && !ALLOWED_PROTOS.includes(overrideProto)) {
writeErr(res, 400, 'Invalid target protocol');
return;
}
const accessKey = req.headers['proxy-access-key'];
const requestedTarget = req.headers['proxy-target'];
if (accessKey && requestedTarget) {
req.on('error', (err) => {
console.error(`Request error: ${err}`);
});
const accessKeyBuffer = Buffer.from(accessKey);
if (accessKeyBuffer.length === ACCESS_KEY.length && crypto.timingSafeEqual(accessKeyBuffer, ACCESS_KEY)) {
let parsedTarget;
try {
parsedTarget = new URL(`https://${requestedTarget}`);
} catch (e) {
writeErr(res, 400, 'Invalid target');
return;
}
const requestedHost = parsedTarget.host;
let hostAllowed = false;
let hostProto = DEFAULT_PROTO;
for (let i = 0; i < ALLOWED_HOSTS.length; i++) {
const iHost = ALLOWED_HOSTS[i];
if (requestedHost === iHost.host) {
hostAllowed = true;
break;
}
}
if (!USE_WHITELIST) {
hostAllowed = true;
}
if (overrideProto) {
hostProto = overrideProto;
}
if (hostAllowed) {
doProxy(parsedTarget, hostProto, req, res);
} else {
writeErr(res, 400, 'Host not whitelisted');
}
} else {
writeErr(res, 403, 'Invalid access key');
}
} else {
writeErr(res, 400, 'proxy-access-key and proxy-target headers are both required');
}
});
server.listen(PORT, (err) => {
if (err) {
console.error(`Server listening error: ${err}`);
return;
}
console.log(`Server started on port ${PORT}`);
});