setting and unsetting a session though an URL - php

Question

Hi,
I need to create a session as soon as the visitor enters my page. Then by clicking on a link that takes to an URL like this example.org/page?no_redirect=true the session must be destroyed but the session should be created again if they click on a link to this URL example.org/page?no_redirect=false.
I did it like this:
session_start();
$_SESSION['redirect'] = "false";
if($_GET['no_redirect'] == "true")
{
$_SESSION['redirect']="true";
} elseif ($_GET['no_redirect'] == "false") {
$_SESSION['redirect']="false";
}
if ($_SESSION['redirect']!=true) {
$redirect = <<<EOF
<script type='text/javascript'>DM_redirect("mobile/$page");</script>
EOF;
}
but its not working. What could it be?
Thank you.

Answer 1

The check if ($_SESSION['redirect'] != true) makes no sense, because you are comparing a non-empty string to a boolean. Non-empty strings always evaluate to true, so your check is really if (true != true), which means the content inside the block will never be executed.
A more sensible approach would be to unset your session once its purpose has been served instead of setting it to "true" / "false".
Code:
session_start();
# Check whether the session should be unset.
if ($_GET['no_redirect'] == "true") {
unset($_SESSION['redirect']);
}
# Check whether the session should be set.
else if ($_GET['no_redirect'] == "false") {
$_SESSION['redirect'] = "true";
}
# Check whether the session is set.
if (isset($_SESSION['redirect'])) {
$redirect = <<<EOF
<script type='text/javascript'>DM_redirect("mobile/$page");</script>
EOF;
}