I've created a session to keep track of some user actions on a specific page.
When user navigates away from that specific page (but still on the same site), I need to reset the session.
I can set set timer for when session expires, but that's not what I want.
How can I reset session on page navigation?
Just make resetting the session the very first thing you do when loading a new page.
Do you have a single page that all traffic is routed through? If so you could do a simple check
if ($current_page != $session_page) {
$_SESSION = array();
}
If you don't have a single page all traffic goes through, then you will need to reset the session at the beginning of every other page.
$_SESSION = array();
Alternatively you can use
unset($_SESSION);
or
session_destroy();
Though note these handle slightly differently to the suggestions above. Note the second (session_destroy) will require you restart the session should you need it again.
You can never be sure that the session is really destroyed.
But there is an old trick used in for example chat applications where a "... is leaving" message is to be printed: On unload just open a popup windows with window.open() that calls your logout page and then closes itself.
What I've done in the past is make a quick ajax call on unload to an unset page, much like the other answers on this page.
<script>
function myAjaxCall(){
//if using jquery
$.ajax('unset.php');
}
</script>
<body onunload="myAjaxCall()">
Related
Please help me out to clear login session.
For example
If I am a user of a particular & I want to check my updates. So I used my user id & password to login to the particular page.
After checking my updates I logged out from the page. After logging out, I used back button in the browser to go back to previous session.
Automatically enters into my page without giving any login details. To prevent from entering into page without any login details the session should be cleared. So help me out to clear the session.
This is a client side problem. If you press back button in browser, the browser loads the previously stored cached page.
Better way is, You should write a javascript function in login page which invokes logout.jsp whenever loaded first time or through back button.
You need to set the cache control header on your pages to ensure they are not cached. Since Have a look at the following question which goes into detail about how to set the cache header correctly in different languages - How to control web page caching, across all browsers?
To clear session in php, you can call a script logout.php containing the following :
<?php
session_start();
$_SESSION = array();
// PHPSESSID is default name, but you may have a custom.
setcookie("PHPSESSID", '', time() - 1, '/');
}
See a more complete example at
http://fr.php.net/session_destroy
I don't want the user to go back to secured pages by clicking back button after logging out. In my logout code, I am unsetting the sessions and redirecting to login page.But, I think the browser is caching the page so it becomes visible despite the session being destroyed from logout.
I am able to avoid this by not allowing the browser to cache
header("Cache-Control", "no-cache, no-store, must-revalidate")
But this way I am loosing the advantage of Browser Caching.
Please suggest a better way of achieving this. I feel, there must be a way of handling this by javascript client side
Implement this in PHP and not javascript.
At the top of each page, check to see if the user is logged in. If not, they should be redirected to a login page:
<?php
if(!isset($_SESSION['logged_in'])) :
header("Location: login.php");
?>
As you mentioned, on logout, simply unset the logged_in session variable, and destroy the session:
<?php
unset($_SESSION['logged_in']);
session_destroy();
?>
If the user clicks back now, no logged_in session variable will be available, and the page will not load.
I was facing this same problem and spent whole day in figuring out it,
Finally rectified it as follows:
In login validation script if user is authenticated set one session value for instance as follows:
$_SESSION['status']="Active";
And then in User Profile script put following code snippet:
<?php
session_start();
if($_SESSION['status']!="Active")
{
header("location:login.php");
}
?>
What above code does is, only and only if $_SESSION['status'] is set to "Active" then only it will go to user profile , and this session key will be set to "Active" only if user is authenticated... [Mind the negation [' ! '] in above code snippet]
Probably logout code should be as follows:
{
session_start();
session_destroy();
$_SESSION = array();
header("location:login.php");
}
Hope this helps...!!!
Here's an easy solution which I have used in my application.
Add the below code inside script tag in the login HTML page (or whichever page it redirects to after logout)
<script>
history.pushState(null, null, null);
window.addEventListener('popstate', function () {
history.pushState(null, null, null);
});
</script>
It will disable the back button. You will not be able to go back by clicking on the back button.
Note: Not tested on Safari.
I think your only server side option is to disallow caching. This is actually not that bad if you are using a Javascript heavy application as your main HTML might only be a series of JS calls and the Views are then generated on the fly. That way the bulk of the data (JS MVC and core code) is cached but the actual page request isn't.
To add to the comments pasted below I would suggest adding a small AJAX call during load time that fires even for cached pages that goes to your backend and checks the session. If not session is not found it would redirect the user away. This is clientside code and not a secure fix, sure, but looks nicer.
You could get this off your conscience with
A cheap fix if all else fails would be a "Please close this window for security reasons" message on the logged out page. – izb May 9 '12 at 8:36
But like N.B. said
You don't have to disable anything. If they go back, they're served the cached version of the restricted page. If they try to click around it, nothing will work because the appropriate session won't be set. – N.B. May 9 '12 at 7:50
You could insert a condition/function on each restricted page, checking if the appropriate session variable is set or not. This way, you can print 2 versions of the page (one for the valid users, and one redirecting to the login page)
Avoiding the user to go back is not a good reason and most of all not secure at all.
If you test the user's session before every "admin" action made on the website, you should be fine, even if the user hit the back button, sees the cached page and tries something.
The "ties something" will return an error since the session is no longer valid.
Instead, you should focus on having a really secured back office.
Here's an easy and quick solution.
To the login form tag add target="_blank" which displays content in a different window. Then after logout simply close that window and the back button problem (Safari browser) is solved.
Even trying to use the history will not display the page and instead redirect to login page. This is fine for Safari browsers but for others such as Firefox the session_destroy(); takes care of it.
the pages on which you required loged in, use setInterval for every 1000 ms and check wheather user is logged in or not using ajax. if user session is invalid, redirect him to log in page.
Note that although users can't change anything after resetting session data and/or cookie, they still may see usual information accessible to a logged in user as they appeared on the last visit. That is caused by browser caching the page.
You have to be sure to add the header on every page accessible by a logged in user, telling the browser that the data is sensitive and they should not cache the script result for the back button. It is important to add
header("Cache-Control: no-cache, must-revalidate");
Note that those other elements other than the immediate result of the script under this header, will still be cached and you can benefit from it. See that you gradually load parts of your page and tag sensitive data and the main HTML with this header.
As the answer suggests, unsetting the logged_in portion of $_SESSION global variable can achieve logging out, but be aware that first, you don't need to destroy session as mentioned in the PHP's session_destroy() documentation
Note: You do not have to call session_destroy() from usual code. Cleanup $_SESSION array rather than destroying session data.
And second, you better not to destroy the session at all as the next warning on the documentation explains.
Also, unset() is a lazy function; meaning that it won't apply the effect, until next use of the (part of the) variable in question. It is good practice to use assignment for immediate effect in sensitive cases, mostly global variables that may be used in concurrent requests. I suggest you use this instead:
$_SESSION['logged_in'] = null;
and let the garbage collector collects it, at the same time it is not valid as a logged in user.
Finally, to complete the solution, Here are some functions:
<?php
/*
* Check the authenticity of the user
*/
function check_auth()
{
if (empty($_SESSION['logged_in']))
{
header('Location: login.php');
// Immediately exit and send response to the client and do not go furthur in whatever script it is part of.
exit();
}
}
/*
* Logging the user out
*/
function logout()
{
$_SESSION['logged_in'] = null;
// empty($null_variable) is true but isset($null_variable) is also true so using unset too as a safeguard for further codes
unset($_SESSION['logged_in']);
// Note that the script continues running since it may be a part of an ajax request and the rest handled in the client side.
}
Right now, when the user comes to a page a session is started; that's working fine. But how can I detect when a user leaves that page? I need it so that when the user leaves the page, the session is destroyed.
You wouldn't be able to use PHP to detect the user leaving the page, but you can send an ajax request via javascript on the unload event to destroy that users session.
Related post: Can you fire an event in JavaScript before the user closes the window?
If you're only worried about pages within your website:
if($_SERVER['REQUEST_URI'] !== 'page_with_session.php'){
session_destroy(); // Kill session for all pages but page_with_session.php
}
HTTP is an asynchronous protocol. Asynchronous connections with user sessions are valid in a certain period of time. This time is also refered as expiry time. Therefore sessions have an expiry time. And this time will be renewed while a user accesses your page and invalidated(destroyed) if he does no action in this timeframe.
There is no other way to determine if a user leaves your page.
It is impossible in general case
That's not really how the internet works; you could try sending a signal with onbeforeunload() but it's not a guarantee. Since session garbage is just a probability, and I don't know what your viewership looks like, I'd suggest putting something like this in a common file:
if (isset($_SESSION['last_seen']) && $_SESSION['last_seen'] < time() - 3600) {
session_unset();
session_destroy();
header('Location: logout_or_whatever.php');
exit;
}
$_SESSION['last_seen'] = time();
I use PHP sessions with session_start() to maintain state of which user is logged into my site. This works fine by just calling session_start() and the top of all my files once the user is logged in.
However, I'd like to have it so when they click the site's icon in the menu bar, if they are logged in it won't send them to the homepage but rather to their logged in personal page. However, a simple session_start() to recognize the user is logged in and redirect them at the top of the homepage does not work.
None of the session variables are recognized from the home page. Yet the session is not actually killed - I can go back in the history and am still logged into the site. Would there be a reason the homepage should give different behavior than every other page?
No, it shouldn't be different.
In order to see what variables are available in your $_SESSION, you can do this
var_dump($_SESSION);
If it's empty then there is a problem. You can try to see the session_id with the method
echo session_id();
It should be the same session_id in both your logged page and home page. If this is not the case, maybe you are messing up with cookies?
Make sure that session_start() is only being called once. If you call it twice, it could interfere with the session handling. I would recommend that you call session_start() on every page the user can be logged in on (frankly I see no reason not to call it on every page period, but someone please correct me if this is bad) but only once. At that point, you can check the _SESSION and see if the user's logged in key is set. If so, redirect them.
if u are calling session_start() on each page and you don't know that a session is already strated in your include/require pages then use # like this #session_start()
note: although this is not good practice to use #
to send a user to their personal page rather than home page
..u need to develop a logic and also personal page will be based on user id of logged user.On home page something like below
home.php(raw code)
<?php if(!empty($_SESSION['user_id'])) {
header("Location : personal_page.php?id=".$_SESSION['user_id']);
exit();
} else {
//your page code
}
?>
for login via history pages problem:
you create a logout.php to end user session, do not forget to start the session in this page!, using session_start() at the very begging of your script. Thus,
session_start();
session_unset();
session_destroy();
will be the right sequence to end a user's session.
reference
Happy To Help :)
It causes conflicts when the user open another page on another window/tab. So how to prevent these conflicts? One way is to set session same for each page the same..every time the user logout/logins the session will be regenerated.
<?php
//every page sets its own session if its not ajax so that it dont expire
if(is_ajax()){
$_SESSION['token'] = md5(rand());
}
echo '<div id="token">'.$_SESSION['token'].'</div>';
?>
tokens will be passed from div.token to perform ajax requests by jquery. but then when the user opens another tab new session is set then the other page returns 'Invalid Request' error.
Having multiple pages or tabs open should not interfere with the session. If it does, you're probably putting a bit too much into the session.
What are you storing in the session? It sounds like you're probably storing something in the session that belongs in the URL.
Edit: After seeing your edit, you may want to check out the top answer in this question:
PHP - CSRF - How to make it works in all tabs?