title: Sanitize $_GET parameters to avoid XSS and other attacks
body: <p>I have a website in php that does include() to embed the content into a template. The page to load is given in a get parameter, I add ".php" to the end of the parameter and include that page. I need to do some security check to avoid XSS or other stuff (not mysql injection since we do not have a database). What I've come up with is the following.</p>
  
  <pre><code>$page = $_GET['page'];
  
  if(!strpos(strtolower($page), 'http') || !strpos($page, '/') ||
      !strpos($page, '\\') || !strpos($page, '..')) {
          //append ".php" to $page and include the page
  </code></pre>
  
  <p>Is there any other thing I can do to furtherly sanitize my input?</p>