CODEWITHSUNDEEP
phphtmldatabase
dirigibleplum
dirigibleplum

Reputation: 137

Simple Logout Script

I'm using the code below to log users in. When the new session is created they are redirected to a new page - content.php. I wonder what's the best way/the proper way to destroy the session and log out the users, redirectiong them back to the index.php.

<?php 
if (isset($_REQUEST['signin'])){

$username = $_POST['username'];
$password = $_POST['password'];

$query = "SELECT * FROM `user` WHERE username='$username' and password='$password'";
$result = mysql_query($query) or die(mysql_error());
$count = mysql_num_rows($result);

if ($count == 1){
$_SESSION['username'] = $username;
header('Location: content.php');
}
else{
echo "Invalid Login Credentials.";
}
}
if (isset($_SESSION['username'])){
$username = $_SESSION['username'];
header('Location: content.php');
}
?>


<form method="post" name="login">
        <?php 
        if (isset($msg) & !empty($msg)) {
                    echo $msg;
                    }
        ?>
        <label for="username">Username:</label><br>
        <input type="text" name="username"><br>
        <label for="password">Password:</label><br>
        <input type="password" name="password"><br>
        <button type="submit" name="signin">Sign in</button>
</form>

I know that there are flaws in this script (e.g. not encrypted password), but for now I'm looking for a simple script to log out.

Upvotes: 1

Views: 17296

Answers (5)

UniDoX
UniDoX

Reputation: 1

<?php
if (!isset($_SESSION)) { session_start(); }

$_SESSION = array(); 

session_destroy(); 

header("Location: login"); //login.php if you havent setup your htaccess to use without.php
exit();
?>

Upvotes: 0

Spencer D
Spencer D

Reputation: 3486

First of all, please check your query variables before you query, otherwise you run the risk of SQL injection.

Next, when you set up a session, you must call session_start(); at the top of your script to utilize the session.

Finally, to log the user out, you simply call session_destroy(); and the existing session is destroyed.

I have rewritten your code a little 

<?php 
session_start();
if (isset($_REQUEST['signin'])){
    $username = $_POST['username'];
    $password = $_POST['password'];

    $sql_connection = new mysqli("dbHost", "dbUsername", "dbPassword", "dbName");
    if($sql_connection->connect_errno){
        die("db error");
    }
    $username = $sql_connection->real_escape_string($username);
    $password = $sql_connection->real_escape_string($password);
    $query = "SELECT * FROM `user` WHERE username='$username' and password='$password' LIMIT 1;";
    $result = $sql_connection->query($query) or die("db error");
    $count = $result->num_rows;

    if ($count == 1){
        $_SESSION['username'] = $username;
        header('Location: content.php');
        die();
    }else{
        echo "Invalid Login Credentials.";
    }
}elseif(isset($_SESSION['username'])){
    $username = $_SESSION['username'];
    header('Location: content.php');
    die();
}
?>
<form method="post" name="login">
        <?php 
        if (isset($msg) & !empty($msg)) {
                    echo $msg;
                    }
        ?>
        <label for="username">Username:</label><br>
        <input type="text" name="username"><br>
        <label for="password">Password:</label><br>
        <input type="password" name="password"><br>
        <button type="submit" name="signin">Sign in</button>
</form>

This uses MySQLi instead of MySQL due to the impending removal. It also escapes the input and sets up the session.

Upvotes: 0

nettux
nettux

Reputation: 5406

session_start();
$_SESSION = array();
if (ini_get("session.use_cookies")) {
    $params = session_get_cookie_params();
        setcookie(session_name(), '', time() - 42000,
        $params["path"], $params["domain"],
        $params["secure"], $params["httponly"]
    );
}
session_destroy();
header("Location: index.php"); exit;

Upvotes: 1

Jordi Kroon
Jordi Kroon

Reputation: 2597

The best and most simple way to logout a user is to destroy the whole session or unset the necessary session keys.

session_destroy();
// or...
unset($_SESSION['username'];

header('Location: index.php');

I prefer the unset because you might want to store more data in the session array.

Upvotes: 1

Victory
Victory

Reputation: 5890

First things first you need to sanitize your inputs so

$username = mysql_real_escape_string($_POST['username']);
$password = mysql_real_escape_string($_POST['password']);

Now, as for clearing a session. Your logout script should useunset

unset($_SESSION['username']);
unset($_SESSION['password']);

Upvotes: 1

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