title: Getting the host and URI in PHP when request is passed via a proxy
body: <p>We have a site that resides on server A with the URL eg www.blah.com, however when it is live it will be accessed at the url eg www.notblah.com which will proxy the request to server A.</p>
  
  <p>My question is, in PHP how does one properly work out the host and URI when the request is passed via a proxy? $_SERVER['host'] and $_SERVER['uri'] give me www.blah.com not the URL accessed via the proxy server.</p>