Tamal Tamal - 6 months ago 121
HTML Question

How to Disable Browser Back Button functionality after click on Logout Button in PHP

I am having trouble with the browser back button.
When the User press Log out it have to destroy the session and cookies. I wrote the following code:

index.php

<!DOCTYPE html>
<html lang="en">
<head>
<script type="text/javascript">
function disablebackbutton(){
window.history.forward();
}
disablebackbutton();
</script>
</head>
<body>
<form name="loginform" method="post" action="<?php echo __PROJECT_LINK__; ?>/php/login_exec.php">
<div class="modal-body">
<div class="form-horizontal">
<div class="form-group">
<label class="control-label">
<?php
if( isset($_SESSION['ERRMsg_ARR']) && is_array($_SESSION['ERRMsg_ARR']) && count($_SESSION['ERRMsg_ARR']) >0 ) {
echo '<ul class="err">';
foreach($_SESSION['ERRMsg_ARR'] as $msg) {
echo '<span class="label label-warning" style="margin-left: 5px;">',$msg,'</span>';
}
echo '</ul>';
unset($_SESSION['ERRMsg_ARR']);
}
?>
</label>
</div>
<div class="subnav subnav-fixed nav navbar" style="margin-top: 10px; margin-right: 10px; margin-left: 10px;">
<ul class="nav nav-pills">
<li style="margin-top: 10px;">
<span class="label label-default" style="margin-left: 22px;">Username</span>
<input type="text" id="inputUserName" name="username" placeholder="Username" style="margin-left: 5px;">
</li>
<li style="margin-top: 10px;">
<span class="label label-default" style="margin-left: 22px;">Password</span>
<input type="password" id="inputPassword" name="password" placeholder="Password" style="margin-left: 5px;">
</li>
<li style="margin-top: 10px; margin-bottom: 10px;">
</li>
</ul>
</div>
</div>
</div>
<div class="modal-footer">
<!--?php $this->btnLogLogin->Render();?-->
<button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
<button type="submit" class="btn btn-primary">Sign In</button>
</div>
</form>
</body>
</html>


login_exec.php

<?php
//Start session
if (session_status() == PHP_SESSION_NONE) {
session_start();
}
//Include database connection details
require_once('connection.php');

//Array to store validation errors
$errmsg_arr = array();

//Validation error flag
$errflag = false;

//Function to sanitize values received from the form. Prevents SQL injection
function clean($str) {
$str = @trim($str);
if(get_magic_quotes_gpc()) {
$str = stripslashes($str);
}
return mysql_real_escape_string($str);
}
if(isset($_POST['username']))
{
//Sanitize the POST values
$username = ($_POST['username']);
$password = ($_POST['password']);

//Input Validations
if($username == '') {
$errmsg_arr[] = 'Username missing';
$errflag = true;
}
if($password == '') {
$errmsg_arr[] = 'Password missing';
$errflag = true;
}

//If there are input validations, redirect back to the login form
if($errflag==true) {
$_SESSION['ERRMsg_ARR'] = $errmsg_arr;
session_write_close();
header("location:../index.php");
exit();
}

//Create query
$qry="SELECT * FROM admin WHERE user_name='$username' AND password='$password'";
$result=mysql_query($qry);

//Check whether the query was successful or not
if($result) {
if(mysql_num_rows($result)) {
while($row = mysql_fetch_array($result))
{
if($row['User_Status']=="Active"){
$expire=time()+60*60*24*30; //1month
setcookie("User_id", $row['User_id'], $expire);
$name = $row['full_name'];
$parts = explode(" ", $name);
$lastname = array_pop($parts);
$firstname = implode(" ", $parts);
$_SESSION['USER'] = $firstname;
$_SESSION['UID'] = $row['User_id'];
$_SESSION['URights'] = $row['Rights'];
header("location:../welcome.php");
}
else{
$errmsg_arr[] = 'User Status is Block. Please contact your Administrator.';
$errflag = true;
if($errflag) {
$_SESSION['ERRMsg_ARR'] = $errmsg_arr;
session_write_close();
header("location: ../index.php");
exit();
}
}
}
}
else {
//Login failed
$errmsg_arr[] = 'Username and Password not found';
$errflag = true;
if($errflag) {
$_SESSION['ERRMsg_ARR'] = $errmsg_arr;
session_write_close();
header("location: ../index.php");
exit();
}
}
}else {
die("Query failed");
}
}
?>


welcome.php

<?php include 'qcubed.inc.php'; ?>
<?php
$User_Name = $_SESSION['USER'];
?>
<html>

<head>
<title>Welcome</title>
</head>
<body>
<h1>Welcome <?php echo $User_Name; ?></h1>
<h2><a href = "<?php echo __PROJECT_LINK__; ?>/Info.php">Info</a></h2>
<h2><a href = "<?php echo __PROJECT_LINK__; ?>/php/logout.php">Sign Out</a></h2>
</body>
</html>


Info.php

<?php include '../../qcubed.inc.php';?>
<!DOCTYPE html>
<html lang="en">
<head>
<title><?php echo __PROJECT_TITLE__; ?> - Full Info</title>
<script type="text/javascript">
function disablebackbutton(){
window.history.forward();
}
disablebackbutton();
</script>
</head>
<?php
if(isset($_SESSION['UID']) && $_SESSION['UID'] != "")
{
//Task to do
$User_Name = $_SESSION['USER'];
?>
<body>
<h1>Info about <?php echo $User_Name; ?></h1>
<h2><a href = "<?php echo __PROJECT_LINK__; ?>/php/logout.php">Sign Out</a></h2>
</body>
<?php
}
else{
//redirect URL
?>
<script>
alert('You must Login first.');
window.location.href='../../index.php';
</script>";
<?php

exit();
}
?>

</html>


logout.php

<?php
//session_write_close();
session_start(); # NOTE THE SESSION START
$expire=time()-60*60*24*30; //1month
if(isset($_COOKIE['User_id'])):
setcookie('User_id', '', $expire, '/');
endif;
unset($_SESSION['UID']);
unset($_SESSION['USER']);
unset($_SESSION['URights']);
unset($_SESSION['UReg']);
$_SESSION = array();
foreach(array_keys($_SESSION) as $k) unset($_SESSION[$k]);
session_unset();
session_destroy();
header("location: ../index.php");
exit(); # NOTE THE EXIT
?>


After pressing log out from Info.php , when I press the browser back button it is showing my previous Logined user page and session username in Info.php page,
but if I use the following javascript in head section of every page it disable all the browser back button at the time of login also.

<script type="text/javascript">
function disablebackbutton(){
window.history.forward();
}
disablebackbutton();
</script>


I want to disable the browser back button only after the the time of logout.
Please help me.

Answer

At last I solved my problem ..... :-) I use this following code in

logout.php

<html>
<head>
    <script type = "text/javascript" >
    window.history.forward();
    function preventBack() { window.history.forward(1); }
    setTimeout("preventBack()", 0);
    window.onunload = function () { null };
</script>

</head>
<body onload="preventBack();" onpageshow="if (event.persisted) preventBack();" onunload="">
Please Wait..
<?php

session_start(); # NOTE THE SESSION START
$expire=time()-60*60*24*30; //1month
if(isset($_COOKIE['User_id'])){
    setcookie('User_id', '', $expire);
}
unset($_SESSION['UID']);
unset($_SESSION['USER']);
unset($_SESSION['URights']);
unset($_SESSION['UReg']);
$_SESSION = array();
foreach(array_keys($_SESSION) as $k) unset($_SESSION[$k]);
session_unset();
session_destroy();

header("Refresh: 2;url=../index.php");
?>
</body>
</html>

Now it's avoid me to use browser back button after logout and destroy the session. Thank you all for yours valuable support...

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