/*
Xsstc: Cross-site scripting through Cascading Style Sheets
Version 0.1, 26 August 2008

Copyright (C) 2008, Wes Biggs.  All rights reserved.

Redistribution and use in source and binary forms, with or without 
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice, 
      this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright 
      notice, this list of conditions and the following disclaimer in the 
      documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
POSSIBILITY OF SUCH DAMAGE.
*/

var Xsstc = new Object();
Xsstc.cssNode = null;

Xsstc.exec = function(url, c) {
  // Dynamically create the stylesheet
  var h = document.getElementsByTagName("head")[0];

  if (Xsstc.cssNode != null) {
    Xsstc.cssNode.disabled = true; /* Required for IE */
    h.removeChild(Xsstc.cssNode);
  }

  Xsstc.cssNode = document.createElement('link');
  Xsstc.cssNode.type = 'text/css';
  Xsstc.cssNode.rel = 'stylesheet';
  // Add nonce to the URL to ensure reloading
  Xsstc.cssNode.href = url + ((url.indexOf('?') != -1) ? '&' : '?') + 'xsnonce=' + Math.round(Math.random() * 100000000000);
  Xsstc.cssNode.media = 'screen';
  h.appendChild(Xsstc.cssNode);

  // No onLoad callback, so need to poll
  setTimeout('Xsstc.result(' + c + ')', 50);
};

Xsstc.result = function(c) {
  var elem = document.getElementById('Xsstc');
  // IE uses currentStyle, not getComputedStyle(), and camelCase attributes
  if ((x = (elem.currentStyle) ? elem.currentStyle['backgroundImage'] : ((Xsstc.cssNode.sheet == null) ? 'none' : document.defaultView.getComputedStyle(elem, null).getPropertyValue('background-image'))) == 'none') {
    // Should probably eventually die - this could run forever
    setTimeout('Xsstc.result(' + c + ')', 50);
  } else {
    // IE adds double quotes around URL
    c(decodeURIComponent(x.replace(/url\([^\#]*#([^")]*)"?\)/, '$1')));
  }
};