node-js-http-proxy-capturing-audio-mpeg-files.js

var httpProxy = require('http-proxy');
var http = require('http');
var fs = require('fs');

var proxy = httpProxy.createProxyServer({
  target:'http://localhost:9005'
});

proxy.listen(8005);

//
// Listen for the `error` event on `proxy`.
proxy.on('error', function (err, req, res) {
  res.writeHead(500, {
    'Content-Type': 'text/plain;charset=utf-8'
  });
  console.log(err);
  res.end('Something went wrong.');
});

//
// Listen for the `proxyRes` event on `proxy`.
//
proxy.on('proxyRes', function (proxyRes, req, res) {
  console.log('For ' + JSON.stringify(req.url) + '\n'
    + 'RAW Response from the target',
    JSON.stringify(proxyRes.headers, true, 2));
    
  var contentType = proxyRes.headers['content-type'];
  if (!contentType)
    return;
  contentType = contentType.replace(/\s*;\s*.*/, '').toLowerCase();
  if (contentType != "audio/mpeg")
    return;
    
  var filename = encodeURIComponent(req.url) + ".mpeg";
  var writable = fs.createWriteStream(filename);
  proxyRes.pipe(writable);
});


//
// Create your target server
//
http.createServer(function (req, res) {
  proxy.web(req, res, {
    target: 'http://' + req.headers.host
  });
}).listen(9005);