proxy.js

/*
 * This is a naive attempt to protect against transparent proxies.
 * - We pass the request host and path in from Rack and compare it against what JS sees.
 * - If they don't match, put them where they should be.
 *
 */
(function(location) {
  if (location.hostname !== proxyCheck.hostname || location.pathname !== proxyCheck.pathname) {
    /* Use an anchor tag as a parser. */
    var redirectParser = document.createElement('a');

    /* Grab the current, browser-side URL */
    redirectParser.href = location.href;

    /* Then munge the hostname, pathname, and port to match the server. */
    redirectParser.hostname = proxyCheck.hostname;
    redirectParser.pathname = proxyCheck.pathname;
    redirectParser.port = '';

    /* And redirect away. */
    window.top.location.replace(redirectParser.href);
  }
})(window.location);