session not working as expected with mobile devices

Question

Hi,

I have a site with 2 versions, one for the PC and one for the mobile. PC version goes like this mysite.org whereas mobile version goes mysite.org/mobile So when a user visits the site from a mobile device it is automatically redirected to mysite.org/mobile through JS code. That works fine, however, I am offering my users the choice to see the PC version instead so I need a way to tell the browser to stop redirecting once the PC version button is pressed. This is what I did.

<?php
session_start();
$_SESSION['redirect'] = true;

# Check whether the session should be unset.
if ($_GET['no_redirect'] == "true") {
   unset($_SESSION['redirect']);
}

# Check whether the session is set.
if (isset($_SESSION['redirect'])) {
 $redirect = <<<EOF
<script type='text/javascript'>DM_redirect("mobile/$page");</script>
EOF;
}
?>

my html code goes like this

<script type='text/javascript' src='js/mobile.js'></script>
  $redirect

if the $redirect variable is empty, redirection will not occur no matter what device is being used. The variable wont be empty as long as $_SESSION['redirect'] is true. So my button to stop redirecting and see the PC version looks like this:

<a href="&no_redirect=false" rel="alternate">SEE PC VERSION</a>

whereas the button to go back to the mobile version looks like this

<a href="&no_redirect=true" rel="alternate">SEE MOBILE VERSION</a>

it wont quite work because after pressing the PC version button it goes indeed to the PC version page but if I navigate from there it redirects again to the mobile version. What solution can I use?

Thank you.

Answer 1

Your problem is that you are always setting $_SESSION['redirect'] to true and only unsetting it when $_GET['no_redirect'] is set. So your if condition is always true except for when the "PC version" button is pressed. You could try the following code instead:

session_start();
// if we haven't set redirect, assume we want to redirect
if (!isset($_SESSION['redirect'])) $_SESSION['redirect'] = true;

// Do we want to keep redirecting?
if ($_GET['no_redirect'] == "true") {
    $_SESSION['redirect'] = false;
}

// Should we redirect?
if ($_SESSION['redirect']) {
    $redirect = <<<EOF
<script type='text/javascript'>DM_redirect("mobile/$page");</script>
EOF;
}

This code will now only set $_SESSION['redirect'] to true if it wasn't already set. However, that won't let you get back to the mobile version. Assuming that if the "Mobile version" button is pressed, the page will be called with $_GET['no_redirect'] = "false" , in which case you can change the first part of the code to this:

session_start();
// if we haven't set redirect, assume we want to redirect
if (!isset($_SESSION['redirect'])) $_SESSION['redirect'] = true;

// Do we want to keep redirecting?
if ($_GET['no_redirect'] == "true") {
    $_SESSION['redirect'] = false;
}
elseif ($_GET['no_redirect'] == "false") {
    $_SESSION['redirect'] = true;
}