Modify Gzipped HTML response from node-http-proxy - php

Question

Problem:
Modifying a Gzipped HTML response gives a white-screen when using node-http-proxy to proxy requests to a vagrant box.
What I have so far:
My method of intercepting the requests & modifying the html (seen below) is working well for all requests that are NOT Gzipped. (I've tested using node, ruby, PHP & apache servers).
The confusing part:
I have a test suite that starts the proxy & makes a request to it. If I console.log the response I can clearly see that the HTML has been modified - it's just that it won't display in the browser at all...
The proxy setup
var server = httpProxy.createServer(function (req, res, proxy) {
var next = function () {
proxy.proxyRequest(req, res, {
host: "172.22.22.22",
port: 80,
changeOrigin: true
});
};
var write = res.write;
res.write = function (string, encoding) {
var body = string instanceof Buffer ? string.toString() : string;
body = body.replace(/<\/body>/, function (w) {
return "<script>console.log('injected')</script>\n" + w;
});
if (string instanceof Buffer) {
string = new Buffer(body);
} else {
string = body;
}
write.call(res, string, encoding);
};
next();
}).listen(3002);
// Remove content-length, defaults to 'chunked'
server.proxy.on("proxyResponse", function (req, res, response) {
if (response.headers.hasOwnProperty("content-length")) {
delete response.headers["content-length"];
}
});
My test case showing correctly modified HTML
it("can modify the html response", function (done) {
var data;
http.get(proxyHost, function (res) {
var chunks = [];
res.on("data", function (chunk) {
chunks.push(chunk.toString());
});
res.on("end", function () {
data = chunks.join("");
console.log(data); // snippet can be seen in this response
done();
});
});
});
Any ideas?

Answer 1

I have solved this problem.
Can't upload the source, but I can give you some hints on this.
use server.proxy.on("proxyResponse" to check content-encoding
do nothing but gather chunk on res.write
on res.end, zlib.unzip gathered chunks if content-encoding was "gzip" then oldWrite.call(res,decoded_string), oldEnd.apply(res,arguments)
if you want to change something do it while #3
Hope this help you out.