I have an http-proxy to proxy any website and inject some custom JS file before to serve the HTML back to the client. Whenever I try to access the proxied website, it will hang up or the browser seems to load indeterminately. But when I check the HTML source, I successfully managed to inject my custom JavaScript file. Here is the code:
const cheerio = require('cheerio');
const http = require('http');
const httpProxy = require('http-proxy');
const { ungzip } = require('node-gzip');
_initProxy(host: string) {
let proxy = httpProxy.createProxyServer({});
let option = {
target: host,
selfHandleResponse: true
};
proxy.on('proxyRes', function (proxyRes, req, res) {
let body = [];
proxyRes.on('data', function (chunk) {
body.push(chunk);
});
proxyRes.on('end', async function () {
let buffer = Buffer.concat(body);
if (proxyRes.headers['content-encoding'] === 'gzip') {
try {
let $ = null;
const decompressed = await ungzip(buffer);
const scriptTag = '<script src="my-customjs.js"></script>';
$ = await cheerio.load(decompressed.toString());
await $('body').append(scriptTag);
res.end($.html());
} catch (e) {
console.log(e);
}
}
});
});
let server = http.createServer(function (req, res) {
proxy.web(req, res, option, function (e) {
console.log(e);
});
});
console.log("listening on port 5051");
server.listen(5051);
}
Can someone please tell me if I am doing anything wrong, it looks like node-http-proxy is dying a lot and can't rely much on it since the proxy can work sometimes and die at the next run, depending on how many times I ran the server.
I ended up writing a small Python Server using CherryPy and proxied the web app with mitmproxy. Everything is now working smoothly. Maybe I was doing it wrong with node-http-proxy but I also became sceptic about using it in a production environment.