Loginform

<?php
$control = 0;
session_start();
if (!isset($_SESSION["username"]) && !isset($_GET["page"])) {
    $control = 0;
}
if ($_GET["page"] == "log") {
    $user = $_POST["user"];
    $password = $_POST["password"];
    if ($user == "Example" && $password == "12345") {
        $_SESSION["username"] = $user;
        $control = 1;
    } else {
        $control = 2;
    }
}
?>
<html>
<head>
    <title>Login</title>
    <?php
    if ($control == 1) {
    ?>
        <meta http-equiv="refresh" content="3; URL=seite2.php">
    <?php
    }
    ?>
</head>
<body>
<?php
if ($control == 0) {
?>
    Please enter your username and you password<br/>
    <form method="post" action="index.php?page=log">
        Username: <input type="text" name="user" value="OK"/><br/>
        Password: <input type="password" name="password" /><br/>
        <button type="submit">Login</button>
    </form>
<?php
}
if ($control == 1) {
?>
    Login successful, you will be redirected
<?php
}
if ($control == 2) {
?>
    Wrong username or password, <a href="index.php">try again</a>.
<?php
}
?>
</body>
</html>