<?php
    $db_host = 'localhost';
    $db_user = 'root';
    $db_pass = '';
    $db_name = 'guestbook';
    $login_name = 'admin';
    $login_pass = 'password';

    function logged_in() {
        if (!isset($_SESSION))
            session_start();
        if (isset($_SESSION['username']) && isset($_SESSION['password']))
            return $_SESSION['username'] === $login_name && $_SESSION['password'] === $login_pass;
        else
            return false;
    };
?>