title: $_SERVER['HTTP_REFERER'] returns empty PHP
body: <p>Basically I have 2 websites. <strong>website1</strong> is the main website which is a blog. Now I am sending visitors to <strong>website2</strong> if the visitor is not logged in to <strong>website1</strong>. Then <strong>website2</strong> redirects visitors back to the <strong>website1</strong> with some data so that he can log in.</p>
  
  <p>Now my goal is to check if the user is coming from <strong>website2</strong> or not.</p>
  
  <p>I tried </p>
  
  <p><code>$referer_parse = parse_url($_SERVER['HTTP_REFERER']);
   var_dump($referer_parse);</code></p>
  
  <p>which returns <code>array(1) { ["path"]=&gt; string(0) "" }</code></p>
  
  <p>I created an <strong>anchor tag</strong> for <strong>website1</strong> and the visitors coming to <strong>website1</strong> by clicking on the link shows the right things for the above code. But it is not working when <strong>website2</strong> redirects automatically.</p>