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<?php |
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/** |
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* Session class |
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* |
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* handles the session stuff. creates session when no one exists, sets and gets values, and closes the session |
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* properly (=logout). Not to forget the check if the user is logged in or not. |
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*/ |
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class Session |
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{ |
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/** |
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* starts the session |
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*/ |
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public static function init() |
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{ |
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// if no session exist, start the session |
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if (session_id() == '') { |
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session_start(); |
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} |
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} |
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/** |
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* sets a specific value to a specific key of the session |
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* |
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* @param mixed $key key |
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* @param mixed $value value |
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*/ |
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public static function set($key, $value) |
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{ |
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$_SESSION[$key] = $value; |
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} |
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/** |
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* gets/returns the value of a specific key of the session |
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* |
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* @param mixed $key Usually a string, right ? |
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* @return mixed the key's value or nothing |
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*/ |
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public static function get($key) |
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{ |
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if (isset($_SESSION[$key])) { |
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$value = $_SESSION[$key]; |
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// filter the value for XSS vulnerabilities |
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return Filter::XSSFilter($value); |
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} |
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} |
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/** |
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* adds a value as a new array element to the key. |
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* useful for collecting error messages etc |
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* |
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* @param mixed $key |
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* @param mixed $value |
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*/ |
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public static function add($key, $value) |
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{ |
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$_SESSION[$key][] = $value; |
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} |
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/** |
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* deletes the session (= logs the user out) |
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*/ |
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public static function destroy() |
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{ |
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session_destroy(); |
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} |
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/** |
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* update session id in database |
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* |
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* @access public |
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* @static static method |
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* @param string $userId |
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* @param string $sessionId |
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*/ |
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public static function updateSessionId($userId, $sessionId = null) |
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{ |
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$database = DatabaseFactory::getFactory()->getConnection(); |
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$sql = "UPDATE users SET session_id = :session_id WHERE user_id = :user_id"; |
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$query = $database->prepare($sql); |
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$query->execute(array(':session_id' => $sessionId, ":user_id" => $userId)); |
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} |
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/** |
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* checks for session concurrency |
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* |
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* This is done as the following: |
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* UserA logs in with his session id('123') and it will be stored in the database. |
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* Then, UserB logs in also using the same email and password of UserA from another PC, |
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* and also store the session id('456') in the database |
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* |
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* Now, Whenever UserA performs any action, |
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* You then check the session_id() against the last one stored in the database('456'), |
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* If they don't match then log both of them out. |
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* |
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* @access public |
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* @static static method |
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* @return bool |
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* @see Session::updateSessionId() |
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* @see http://stackoverflow.com/questions/6126285/php-stop-concurrent-user-logins |
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*/ |
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public static function isConcurrentSessionExists() |
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{ |
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$session_id = session_id(); |
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$userId = Session::get('user_id'); |
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if (isset($userId) && isset($session_id)) { |
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$database = DatabaseFactory::getFactory()->getConnection(); |
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$sql = "SELECT session_id FROM users WHERE user_id = :user_id LIMIT 1"; |
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$query = $database->prepare($sql); |
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$query->execute(array(":user_id" => $userId)); |
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$result = $query->fetch(); |
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$userSessionId = !empty($result)? $result->session_id: null; |
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return $session_id !== $userSessionId; |
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} |
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return false; |
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} |
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/** |
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* Checks if the user is logged in or not |
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* |
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* @return bool user's login status |
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*/ |
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public static function userIsLoggedIn() |
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{ |
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return (self::get('user_logged_in') ? true : false); |
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} |
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} |
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panique /
huge
