Mobile_detect php redirecting to subdomain - Stuck in a redirect loop!

Question

I am using the following code in a module for redirection to a subdomain whenever a mobile is detected;

<?php

  function mobydetect_init() {
  include("PATH/TO/Mobile_Detect.php");

  $detect = new Mobile_Detect();
  if ($detect->isMobile()) {
    header('Location: http://m.mysite.com');
    drupal_exit();
  }
}

However when I go to my site using a mobile I get this error message;

"This web page has a redirect loop."

I have disabled to subdomain from redirecting to the main domain in Aegir. So where's the loop coming from?

Answer 1

Presumably your hook_init runs on both domains.

You need to check you're not already on the redirected page prior to redirection.

e.g

/**
 * Implements hook_init
 */
function mobydetect_init() {
  if($_SERVER['HTTP_HOST'] != 'm.mysite.com'){
    include("PATH/TO/Mobile_Detect.php");
    $detect = new Mobile_Detect();
    if ($detect->isMobile()) {
      drupal_goto('http://m.mysite.com', array('absolute' => TRUE, 'external' => TRUE));
    }
  }
}

Note, hook_init doesn't run on cached pages so you may find mobile users aren't redirected on cached pages. You could try using hook_boot instead or else offload to the webserver conf.