title: is $_SERVER['HTTP_REFERER'] safe?
body: <p>I'm using $_SERVER['HTTP_REFERER'] to generate a dynamic back link. </p>
  
  <pre><code>&lt;a href="&lt;?php echo $_SERVER['HTTP_REFERER'] ?&gt;"&gt;Return to..blah&lt;/a&gt;
  </code></pre>
  
  <p>Is it reasonably safe to do so?</p>