Why are you making server side stuff when all you need is to redirect browser to different window.location.href?
Here is code that parses ?file= QueryString (taken from this question) and redirects user to that address in 1 second (works for me even on Android browsers):
<script type="text/javascript">
var urlParams;
(window.onpopstate = function () {
var match,
pl = /\+/g, // Regex for replacing addition symbol with a space
search = /([^&=]+)=?([^&]*)/g,
decode = function (s) { return decodeURIComponent(s.replace(pl, " ")); },
query = window.location.search.substring(1);
urlParams = {};
while (match = search.exec(query))
urlParams[decode(match[1])] = decode(match[2]);
})();
(window.onload = function() {
var path = urlParams["file"];
setTimeout(function() { document.location.href = path; }, 1000);
});
</script>
If you have jQuery in your project definitely remove those window.onpopstate & window.onload handlers and do everything in $(document).ready(function () { } );