title: how reliabile is document.referrer, can it be spoofed/ faked?
body: <p>How reliable is <code>document.referrer</code> in determining the source?</p>
  
  <p>I want a website (A) to only work if the visitor came from a specific other website (B).</p>
  
  <p>I am planning to use <code>document.referrer</code> in website A to check whether website B is the source (check is done server-side).</p>
  
  <p>Is it safe and reliable way? If not, what are my alternatives?</p>
  
  <p>I have looked at <a href="https://stackoverflow.com/questions/8893269/what-is-the-most-reliable-way-to-hide-spoof-the-referrer-in-javascript">this</a>, but the use case is exact opposite of mine.</p>