修改来自node-http-proxy的压缩后的HTML响应

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.

1. use server.proxy.on("proxyResponse" to check content-encoding
2. do nothing but gather chunk on res.write
3. on res.end, zlib.unzip gathered chunks if content-encoding was "gzip" then oldWrite.call(res,decoded_string), oldEnd.apply(res,arguments)
4. if you want to change something do it while #3

Hope this help you out.