Different values been given for cookies

Question

I don't know what's going on with my cookies, I basically have a system that generates a random code, stores it in a cookie and also in a database. When the user logs back in, along with username/password authentication, this cookie has to match the database too in order to pass through the login phase (it's basically a system to authorise certain machines to access).

The problem is: Basically, I have set up a method to check the cookie data before I log in, it's just a page that prints the cookie data that I can access without logging in. This is located in '/includes/check_cookies.php'. I also have the main login script, that is meant to read the cookie data before anything and see if the 'auth_code' matches the database entry, if it does, allow access providing the username and password is correct etc etc, if it doesn't, it will generate a new 'auth_code' and store it in a table and the cookie. This is based on whether the user is an admin or a standard user, admin's can auth themselves there and then, standard users can't. Say i log in for the first time right now, I'm an admin, so can authorise myself, and it works a treat, i can logout and back in without a hitch. BUT, if i then went home tonight and came back tomorrow morning, attempted to log in, I would be told that my computer isn't authorised again, even though, when checked, the cookie entry matches the database within my check_cookies file, but a new one is generated in the login script? I'm seriously baffled.

But anyway, here's the relevant code (I will use the admin code):

$auth_code = $_COOKIE['auth_code'];
echo $auth_code . "<br>";

// Check Cookie Auth Code Vs Database Auth Code
$auth_query = "SELECT * FROM authorised_computers WHERE auth_code = '".$auth_code."';";
$auth_result = mysqli_query($link,$auth_query);
if($auth_result->num_rows == 0) {
    $auth = 0;
} else {
    $auth = 1;
}

if($auth == 1) {
    setcookie('admin',$admin,$cookie_expire,'/');
    setcookie('login_time',$date,$cookie_expire,'/');
    $_SESSION['logged_in'] = "true";
    header('Location: ../logs.php');
} elseif($auth == 0) {
    setcookie('auth_code',$no_generator,$cookie_expire,'/');
    setcookie('admin',$admin,$cookie_expire,'/');
    setcookie('login_time',$date,$cookie_expire,'/');
    $_SESSION['logged_in'] = "false";
    header('Location: admin_auth.php'); 
}

Basically the code is setting $auth to '0' and following that route.

Below is the cookie data from the login script:

    Array
(
    [auth_code] => 13367320 // Does not match database
    [admin] => 1
    [acc_id] => 1
    [user_id] => 10001
    [login_time] => 2015/07/29 10:25:20
)

And cookie data from before the login attempt:

Array
(
    [auth_code] => 342221-32 // Matches the Database
    [admin] => 1
    [acc_id] => 1
    [user_id] => 10001
    [login_time] => 2015/07/29 10:25:35
)

Basically, the new auth code shouldn't have been generated as the cookie data already matched the Database, so should have just gone straight through.

I have a feeling that it may be an issue with the cookies expiring, but i have set the cookies to: $cookie_expire = time() + (21*365*24*60*60); so they shouldn't be. I might be missing something blatant, but then again, my understanding of Cookies isn't the greatest. Any help would be much appreciated!

Answer 1

Upon checking my code, I found that I was re-setting the cookie further up the code when logging in, thus changing the "cookie code" so it did not match. I have since removed/re-wrote the login script and all appears to be working as it should. Just need to retest it tomorrow morning to see if the issue occurs again.

Thanks for everyones input.