Fill PHP Sessions with default data - php

Question

I'm currently building a little website from scratch. I use a custom SessionHandler to store my sessions in the database which seems to work fine. So as soon as the user logs in I can store the relevant information (for example language) in the session data.
However I would also like to store certain data for users that are not logged in (yet) - again mainly the selected language but also some other stuff. To keep things clean I'd like to set all these standard values in one place, as soon as there is a session without a valid login.
The best place should obviously be my handler, however I'm not sure which function to use and how to get my data in there. I've attached the important parts of the code below.
I'm sure there is a simple solution for it, but so far I haven't gotten there. And it's also a terrible problem to google for ..
Thanks for the help!
public function __construct() {
$this->databaseController = new DatabaseController();
ini_set('session.gc_maxlifetime', SESSION_MAX_LIFETIME);
ini_set('session.gc_probability', 1);
ini_set('session.gc_divisor', 100);
session_set_save_handler(
array($this, "_open"),
array($this, "_close"),
array($this, "_read"),
array($this, "_write"),
array($this, "_destroy"),
array($this, "_gc")
);
}
public function _open() {
return $this->databaseController->check();
}
public function _close() {
return $this->databaseController->close();
}
public function _read($id) {
$result = $this->databaseController->getFirstRow("SELECT sessionData FROM bf1_sessions WHERE sessionID = '".mysql_real_escape_string($id)."'");
if (!empty($result['sessionData'])) {
return $result['sessionData'];
}
else {
return '';
}
}
public function _write($id, $data) {
$access = time();
$result = $this->databaseController->executeQuery("REPLACE INTO bf1_sessions (sessionID, sessionAccess, sessionData) VALUES ('".mysql_real_escape_string($id)."', '".intval($access)."', '".mysql_real_escape_string($data)."')");
return $result;
}

Answer 1

Since I've never really used custom session handlers, I had to read the documentation a bit. This will be more psuedo-code, but it should get you in the right direction. Anytime you start a session, it will first call open() and then read(string $sessionId). You are currently selecting session data from the database and returning the serialized data or a blank string (as you should). Instead of returning the blank string, you should just be able to return a serialized string of your default data.
public function _read($id) {
$result = $this->databaseController->getFirstRow("SELECT sessionData FROM bf1_sessions WHERE sessionID = '".mysql_real_escape_string($id)."'");
if (!empty($result['sessionData'])) {
return $result['sessionData'];
}
else {
return serialize(array(
'foo' => 'bar',
'test' => 123
));
}
}
Please note the above may not work exactly as expected. I am assuming that the serialized data is meant to be a simple array of key/value pairs like in my above example. Also, serialize() may not do exactly what you expect it too due to the following notice on the session_set_save_handler() documentation:
While the data looks similar to serialize() please note it is a different format which is speficied in the session.serialize_handler ini setting.
A final thought: you shouldn't actually need to write this default data to the database, since every time you save/close the session write($sessionId, $data) is called with all of the data (instead of just the changes). So you should be fine to just return default data on read() and save everything anytime write() is called. I'm just mentioning this, because there is a chance something weird happens and you may need to actually INSERT INTO the default data before returning it in your read() function. Please comment if you any problems implementing this.
Links:
session_set_save_handler()
serialize()
session.serialize_handler