<?php
session_start();

include("connect.php");

$timeout = 60 * 30;
$fingerprint = md5($_SERVER['REMOTE_ADDR'] . $_SERVER['HTTP_USER_AGENT']);

if(isset($_POST['userName']))
{
    $user = mysql_real_escape_string($_POST['userName']);
    $password = mysql_real_escape_string($_POST['password']);
    $matchingUser = mysql_query("SELECT * FROM `users` WHERE username='$user' AND password=MD5('$password') LIMIT 1");
    if (mysql_num_rows($matchingUser))
    {
    	if($matchingUser['inactive'] == 1)//Checks if the inactive field of the user is set to one
    	{
    		$error = "Your e-mail Id has not been verified. Check your mail to verify your e-mail Id. However you'll be logged in to site with less privileges.";
    		$_SESSION['inactive'] = true;
    	}
    	$_SESSION['user'] = $user;
    	$_SESSION['lastActive'] = time();
    	$_SESSION['fingerprint'] = $fingerprint;
    }
    else
    {
    	$error = "Invalid user id";
    }
}
if ((isset($_SESSION['lastActive']) && $_SESSION['lastActive']<(time()-$timeout)) || (isset($_SESSION['fingerprint']) && $_SESSION['fingerprint']!=$fingerprint)
     || isset($_GET['logout'])
    )
{
    setcookie(session_name(), '', time()-3600, '/');
    session_destroy();
}
else
{
    session_regenerate_id();
    $_SESSION['lastActive'] = time();
    $_SESSION['fingerprint'] = $fingerprint;
}
?>

<?php
   if(!isset($_SESSION['user']))
    {
        if(isset($error)) echo $error;
           echo '<form action="' . $_SERVER["PHP_SELF"] . '" method="post">
        <label>Username: </label>
        <input type="text" name="userName" value="';if(isset($_POST['userName'])) echo $_POST["userName"]; echo '" /><br />
        <label>Password: </label>
        <input type="password" name="password" />
        <input type="submit" value="Login" class="button" />
        <ul class="sidemenu">
        <li><a href="register.php">Register</a></li>
        <li><a href="forgotPassword.php">Forgot Password</a></li>
    </ul>
    </form>';
    }
    else
    {
        echo '<ul class="sidemenu">
        <li>' . $_SESSION['user'] . '</li>
        <li><a href="' . $_SERVER["PHP_SELF"] . '?logout=true">Logout</a></li>
        </ul>';
    }
?>

unset($_SESSION['user']);
unset($_SESSION['lastActive']);
unset($_SESSION['fingerprint']);

if($matchingUser['inactive'] == 1)

if(!$matchingUser['inactive'])

if($matchingUser['isactive'])

if($matchingUser->isActive())

<a href="' . $_SERVER["PHP_SELF"] . '?logout=true">

<a href="?logout=true">

$matchingUser = mysql_query("SELECT * FROM `users` WHERE username='$user' AND password=MD5('$password') LIMIT 1");
if (mysql_num_rows($matchingUser))
{
    $matchingUserData = mysql_fetch_assoc($matchingUser);
    if($matchingUserData['inactive'] == 1) //Checks if the inactive field of the user is set to one
    {
        $error = "Your e-mail Id has not been verified. Check your mail to verify your e-mail Id. However you'll be logged in to site with less privileges.";
        $_SESSION['inactive'] = true;
    }

function generateHash($plainText, $salt = null)
{
    define('SALT_LENGTH', 9);
    if ($salt === null)
    {
        $salt = substr(md5(uniqid(rand(), true)), 0, SALT_LENGTH);
    return array($salt, sha1($salt . $plainText) );
    }
    else
    {
        $salt = substr($salt, 0, SALT_LENGTH);
    return sha1($salt . $plainText);
    }

}