[script-review] Loginsysteem

Inloggen:
<?php
/**
 * @author Arwin van der Velden
 * @copyright 2009
 * @name index.php
 */	
if(!isingelogd()) {
	// Anti-flood, na 5 keer verkeerd inloggen wordt je IP adres 24 uur geband
	$query = "SELECT COUNT(id) as attempts FROM ".$settings['db_login_attempts_table']." WHERE time < (NOW() - INTERVAL 24 HOUR) AND ip = '".$mysqli->real_escape_string($_SERVER['REMOTE_ADDR'])."' AND host = '".$mysqli->real_escape_string($_SERVER['HTTP_USER_AGENT'])."'";
	
	if ($result = $mysqli->query($query)) {	
		$login_attempt = $result->fetch_array();
		
		if($login_attempt['attempts'] > $settings['max_login_pogingen']) { // Controleren of je bent geband
			echo 'U bent tijdelijk geband<br>';
		} else {
	
			if (strtoupper($_SERVER['REQUEST_METHOD']) != 'POST') {						
				$formulier = true;
			} else {						
				$formulier = false;					
				if(ctype_digit($_POST['form']) && time() < strtotime("+1 minute", $_POST['form'])) { 				
					$username = htmlspecialchars($_POST['username']);
					$hashedPass = sha1($username.$_POST['pass']);
			 
			        $query = "SELECT ID FROM ".$settings['db_gebruikers_table']." WHERE gebruikersnaam = '".$mysqli->real_escape_string($username)."' AND wachtwoord = '".$mysqli->real_escape_string($hashedPass)."'";
			
					if ($result = $mysqli->query($query)) {
			
						$userId = $result->fetch_array();
			
				        if(ctype_digit($userId['ID'])) {			
				            $hash = sha1($userId['ID'] . $_SERVER['HTTP_USER_AGENT']);
				            // Cookies maken
				            setcookie('user_id', $userId['ID'], time() + 60*60*24*365, '/');
				            setcookie('user_hash', $hash, time() + 60*60*24*365, '/');            
				            // Update query samenstellen, ip en hash updaten
				         $sql = "INSERT INTO ".$settings['db_sessions_table']." (gebruikerID, hash, datum, ip) VALUES ( '".$mysqli->real_escape_string($userId['ID'])."', '".$hash."', NOW(), '".$mysqli->real_escape_string($_SERVER['REMOTE_ADDR'])."')";
				            // Query uitvoeren			
							if(!$result = $mysqli->query($sql))	{
							    trigger_error('Fout in query: '.$mysqli->error);
							} else {
							    if($mysqli->affected_rows > 0) { 
							    	echo 'Je bent ingelogd!';
							    }
							}									        
				        } else {				        	
				        	$sql = "INSERT INTO ".$settings['db_login_attempts_table']." (time, ip, host) VALUES ( NOW(), '".$mysqli->real_escape_string($_SERVER['REMOTE_ADDR'])."', '".$mysqli->real_escape_string($_SERVER['HTTP_USER_AGENT'])."')";				            
			
							if(!$result = $mysqli->query($sql)) {
							    trigger_error('Fout in query: '.$mysqli->error);
							}/*else {
							    if($mysqli->affected_rows > 0) { 
							    	echo 'Attempt ingevoerd<br>';
							    }
							}
				        	*/
							echo 'Het wachtwoord of gebruikersnaam was incorrect';
							$formulier = true;
						}
			
					} 
					
				} else {
					echo 'Fout bij inloggen. Probeer het opnieuw.';
				}
			
			}
			if($formulier) {
				echo '	<form method="post" action="'.end(explode('/', $_SERVER["REQUEST_URI"])).'"> 				
					<p><label>Username:</label><input type="text" name="username" value="" /></p>
					<p><label>Password:</label><input type="password" name="pass" value="" /></p>
					<br><input type="hidden" name="form" value="'.time().'" />						
					<p><input type="submit" value="Inloggen" /></p>						
					</form>
				';				
			}
			}
	}
 
} else {
	echo 'U bent al ingelogd.';
}
?>

/* ---------------------------------------------- */
	
Functie om te checken of je bent ingelogd:
<?php
function isingelogd(){
	global $settings, $mysqli;
    // Kijken of er cookies zijn gezet, en controleren of ze valid zijn
    if(isset($_COOKIE['user_id']) && ctype_digit($_COOKIE['user_id']) && isset($_COOKIE['user_hash']) && ctype_alnum($_COOKIE['user_hash'])) {
        $query = "SELECT gebruikerID FROM ".$settings['db_sessions_table']." WHERE gebruikerID = '".$mysqli->real_escape_string($_COOKIE['user_id'])."' AND hash = '".$mysqli->real_escape_string($_COOKIE['user_hash'])."' AND ip = '".$mysqli->real_escape_string($_SERVER['REMOTE_ADDR'])."'";
        
        // Query uitvoeren
		if ($result = $mysqli->query($query)) {

			$userId = $result->fetch_array();

            if(ctype_digit($userId['gebruikerID'])) {
                // Controleren of de hash ook klopt (browsercheck)
                if(sha1($_COOKIE['user_id'] . $_SERVER['HTTP_USER_AGENT']) == $_COOKIE['user_hash']) {
                    return true;
                } else { // Browser is veranderd
                    // Niet ingelogd
					$query = 'UPDATE '.$settings['db_sessions_table'].' SET hash = NULL, ip = \''.$mysqli->real_escape_string($_SERVER['REMOTE_ADDR']).'\' WHERE gebruikerID = \''.$mysqli->real_escape_string($_COOKIE['user_id']).'\'';
					
					$mysqli->query($query);
					
					// Cookies verwijderen
                    setcookie('user_id', 0, time() - 3600, '/');
                    setcookie('user_hash', '', time() - 3600, '/');        
                    return false;	                     
                }
                
            }   
		}     
        
    } else {    
    	// Geen geldige cookies gezet
        // Niet ingelogd
        return false;
    }        
}  
?>