Session trying my patience

ph3n0m

Ok I have gone through various threads, etc and to the best of my ability I am using sessions for a logout screen from a system that I have built.

All well and good

The sessions are created.
When a user reaches the the logout page, the sessions are destroyed.

Whats the problem?
When a session is destroyed, the user is brought back to an index page (called index2.php)

However, if I press the back button, it appears that the session was not destroyed, and is reactivated.

On all pages, I have this page included (function.php)

It is basically a username/name or id catcher to make sure that whoever is veiwing is registered.

<?
if (($username) && ($password)){

$sql_check = "SELECT * from user where username=\"$username\" and password=\"$password\" LIMIT 1"; 
//execute sql query and get results
$sql_check_result = mysql_query($sql_check) or die("The username/password combination you entered is incorrect.");   

$num_check = mysql_numrows($sql_check_result);
if ($num_check == "0"){
header("Location: index2.php");
}

else {
//format results by row 
while ($row = mysql_fetch_array($sql_check_result))  

   {  

   $userID = $row["userid"]; 
   $userName = $row["username"];
   $userPass = $row["password"];
   }        

session_start(); 
$_SESSION['userID'] = $userID;
$_SESSION['userName'] = $userName;
$_SESSION['userPass'] = $userPass; 
$id = $userID;
$dyn = "id=$userID";
}
}
else if ($id){

$sql_check = "SELECT * from user where userid=\"$id\" LIMIT 1"; 
//execute sql query and get results      

$sql_check_result = mysql_query($sql_check) or die("That is an illegal id");   

//format results by row 
$num_check = mysql_numrows($sql_check_result);
if ($num_check == "0"){
header("Location: index2.php");
}

else {
while ($row = mysql_fetch_array($sql_check_result))  

   {  

   $userID = $row["userid"]; 
   $userName = $row["username"];
   $userPass = $row["password"];
   }        

session_start(); 
$_SESSION['userID'] = $userID;
$_SESSION['userName'] = $userName;
$_SESSION['userPass'] = $userPass; 
$id = $userID;
$dyn = "id=$userID";
}
}
else if ((!$username) && (!$password)){
header("Location: index2.php");
}
else if (!$id){
header("Location: index2.php");
}

?>

whilst the logout page is

include("db.inc.php");
$sql_check = "SELECT * from user where userid=\"$id\" LIMIT 1"; 
//execute sql query and get results      

$sql_check_result = mysql_query($sql_check) or die("That is an illegal id");   

//format results by row 
$num_check = mysql_numrows($sql_check_result);


while ($row = mysql_fetch_array($sql_check_result))  

   {  

   $userID = $row["userid"]; 
   $userName = $row["username"];
   $userPass = $row["password"];
   }        

session_start(); 
$_SESSION['userID'] = $userID;
$_SESSION['userName'] = $userName;
$_SESSION['userPass'] = $userPass; 
unset($_SESSION['userID']);
unset($_SESSION['userName']);
unset($_SESSION['userPass']);
// kill session variables

$_SESSION = array(); // reset session array
session_destroy(); // destroy session.
header('Location: index2.php?id=');

Can someone explain to me, where I have gone wrong and maybe a pointer in the right direction?

Thanks in advance

Sayian

Use exit(); after your header at the bottom , also .. you might want to try to un-register the session's instead of unsetting them. This might help , might not.

abc

You have to check your result!

This....

mysql_query();

Is not the result, it is the resource that allows you to access your query result...

So doing this...

$sql_check_result = mysql_query($sql_check) or die("That is an illegal id");

And expecting $sql_check_result to give you the result is wrong! You do this again and again!

You also need to stop doing things when you don't need to do them! Your logout page calls a query that you should not be calling. You do other stuff that is not needed on that page to! I think you really need to read how sessions work because your code is tell's me you don't understand it!

If you want, put all your scripts related to this login, logout system also include your database scheme and zip them up and post a URL that I can download them. Once I have that I will rewrite your code using good logic and add comments so you can see the things your are doing wrong. After I am done you can download it and begin adding your service pages to the security control that I will give you. I offer you this because I see you are trying! I've been there and know how difficult the learning process can be!

abc

ph3n0m

So doing this...

$sql_check_result = mysql_query($sql_check) or die("That is an illegal id");

And expecting $sql_check_result to give you the result is wrong! You do this again and again!

Are you talking about it being placed in the logout page?

ph3n0m

Ok I have updated my logout file to this

session_start();
header("Cache-control: private"); //IE 6 Fix
$_SESSION = array();
session_destroy(); 
header('Location: index2.php');
exit();

However after it succesfully "logs out" and destorys the session, in Firefox/IE, if I click the back button, it shows me the HTML of the last page I was on, and if I click any link, a new session is started up again.

Is there anyway to prevent people from doing this?