<div id="login_form">
<?php
if (isset($_SESSION['username']))
    header('Location: ?page=overview');
else
    {
        echo "
            <div id='form_placement'
            <form action='.' method='POST'>
                <input type='text' name='username' id='username' value='Username' />
                <br />
                <input type='password' name='password' id='password' value='Password' /><br />
                <input type='submit' name='submit' id='loginSubmit' class='loginSubmit' value='Log in' />
            </form>
            </div>
        ";
    }

?>

<?php

if (isset($_POST['submit']))
                        {
                            //Get data
                            $username = $_POST['username'];
                            $password = $_POST['password'];

                                    if ($username && $password)
                                        {
                                            // To protect MySQL injection
                                            $username = stripslashes($username);
                                            $password = stripslashes($password);
                                            $username = mysqli_real_escape_string($connect, $username);
                                            $password = mysqli_real_escape_string($connect, $password);

                                            $login = mysqli_query($connect, "SELECT * FROM users WHERE username = '$username'");
                                            while ($row = mysqli_fetch_assoc($login))
                                            {
                                                $db_password = $row['password'];
                                                if (sha1($password) == $db_password)
                                                    $loginok = TRUE;
                                                else
                                                    $loginok = FALSE;

                                                if ($loginok == TRUE)
                                                    {
                                                        // Register $username, $password
                                                        $_SESSION["username"] = $username;
                                                        exit();
                                                    }
                                                else
                                                    die('Feil brukernavn/passord.');
                                            }
                                        }
                                    else
                                        echo "Vennligst fyll ut alle felter.";
                        }

?>
</div> <!-- Closes #login_form -->