Session

The icanboogie/session package provides an interface to easily manage PHP sessions. You create a session instance with the desired options and the session is automatically started when reading or writing. The session instance is used as an array, just like $_SESSION. You can provide session segments to your components so that they have a safe place to store their own session values. Flash values can be used in the session and its segments. Finally, you can use the session token with unsafe HTTP methods to prevent CSRF.

It is important to keep in mind that the session instance it basically mapping the $_SESSION array and session_* functions, thus you don't need to change anything in your application setup. You may use Redis to store sessions and some fancy session handler, it makes no difference.

The following code demonstrates some usages of the session instance:

<?php

use ICanBoogie\Session;

$session = new Session;

#
# The session is automatically started when reading or writing
#
if (!isset($session['bar']))
{
    $session['bar'] = 'foo';
}

#
# Optionally, changes can be commited right away,
# also closing the session.
#
$session->commit();

#
# The session is automatically re-started on read or write
#
$session['baz'] = 'dib';

#
# Using isolated session segments
#
$segment = $session->segments['Vendor\NameSpace'];
$segment['bar'] = 123;
echo $session->segments['Vendor\NameSpace']['bar']; // 123
$session->segments['Vendor\NameSpace']['bar'] = 456;
echo $segment['bar']; // 456

#
# Using flash
#
$session->flash['info'] = "Well done!";
$session->segments['Vendor\NameSpace']->flash['bar'] = 123;

#
# The session token can be used to prevent CSRF. A new token is
# generated if none exists.
#
$token = $session->token;       // 86eac2e0d91521df1efe7422e0d9ce48ef5ac75778ca36176bf4b84db9ff35858e491923e6f034ece8bcc4b38c3f7e99
$session->verify_token($token); // true

#
# Of course all of this is just mapping to the `$_SESSION` array
#
echo $_SESSION['bar']; // foo
echo $_SESSION['baz']; // dib
echo $_SESSION['Vendor\NameSpace']['bar']; // 456

Installation

composer require icanboogie/session

Getting started

A Session instance is a representation of a PHP session. It is created with parameters mapped to session_* functions. Options can be defined to customize you session, their default values are inherited from the PHP config.

The following code demonstrates how a session using default values can be instantiated:

use ICanBoogie\Session;

$session = new Session;

Note: Nothing prevents you from using multiple Session instances but it is not recommended.

The following code demonstrates how options can be used to customize the session instance. Only a few options are demonstrated here, more are available.

use ICanBoogie\Session;
use ICanBoogie\Session\CookieParams;

$session = new Session([

    Session::OPTION_NAME => 'SID',
    Session::OPTION_CACHE_LIMITER => 'public',
    Session::OPTION_COOKIE_PARAMS => [

        CookieParams::OPTION_DOMAIN => '.mydomain.tld',
        CookieParams::OPTION_SECURE => true

    ]

]);

If you are defining these options in a config file, you might want to use the light weight SessionOptions interface:

<?php

// config/session.php

use ICanBoogie\SessionOptions as Session;

return [

    Session::OPTION_NAME => 'SID',
    Session::OPTION_CACHE_LIMITER => 'public',
    Session::OPTION_COOKIE_PARAMS => [

        CookieParams::OPTION_DOMAIN => '.mydomain.tld',
        CookieParams::OPTION_SECURE => true

    ]

];

Session segments

Session segments provide a safe place for components to store their values without conflicts. That is, two components may safely use a same key because their value is stored in different session segments. Segments act as namespaces for session values. It is then important to choose a safe namespace, a class name is often the safest option.

Session and session segments instances all implement the SessionSegment interface. Components requiring session storage should use that interface rather than the Session class.

Note: Obtaining a segment does not start a session, only read/write may automatically start a session. So don't hesitate to obtain session segments.

The following example demonstrates how a session segment might be injected into a controller:

<?php

use ICanBoogie\SessionSegment;

class UserController
{
    /**
     * @var SessionSegment
     */
    private $session;

    public function __construct(SessionSegment $session)
    {
        $this->session = $session;
    }

    public function action_post_login()
    {
        // …

        $this->session['user_id'] = $user->id;
    }
}

// …

use ICanBoogie\Session;

$session = new Session;
$controller = new UserController($session->segments[UserControlller::class]);

Flash values

Flash values are session values that are forgotten after they are read, although they can be read multiple time during the run time of a PHP script. They can be set in the session or in its segments.

The following example demonstrates how flash values work with the session and segments:

<?php

use ICanBoogie\Session;

$session = new Session;
$session->flash['abc'] = 123;
$session->segments['segment-one']->flash['abc'] = 456;

The $_SESSION array would look like this:

array(2) {
  '__FLASH__' =>
  array(1) {
    'abc' =>
    int(123)
  }
  'segment-one' =>
  array(1) {
    '__FLASH__' =>
    array(1) {
      'abc' =>
      int(456)
    }
  }
}

After a flash values is read, it disappears from the session/segment, although it can be read multiple time during the run time of a PHP script:

<?php

$session_abc = $session->flash['abc'];   // 123
$session_abc === $session->flash['abc']; // true
$segment_abc = $session->segments['segment-one']->flash['abc'];   // 456
$segment_abc === $session->segments['segment-one']->flash['abc']; // true

array(2) {
  '__FLASH__' =>
  array(0) {
  }
  'segment-one' =>
  array(1) {
    '__FLASH__' =>
    array(0) {
    }
  }
}

Defeating Cross-Site Request Forgery

The Session instance provides a session token that may be used to protect your application against Cross-Site Request Forgery. Your application should verify that token before processing unsafe request, which use HTTP methods POST, PUT, and DELETE.

Note: You can trust that the session has always a token. If none exists when a token is requested a new one is created.

The following example demonstrates how to use the session token with a POST form:

<?php

/**
  * @var \ICanBoogie\Session $session
  */

?>

<form method="POST" action="/articles">
    <input type="hidden" value="<?= $session->token ?>" name="_session_token" />
    <!-- the remainder of the form … -->
</form>

When processing an unsafe request, make sure the session token is valid:

<?php

/**
  * @var \ICanBoogie\Session $session
  */

if (in_array($_SERVER['REQUEST_METHOD'], [ 'POST', 'PUT', 'DELETE' ]))
{
    $token = isset($_POST['_session_token']) ? $_POST['_session_token'] : null;

    if ($session->verify_token($token))
    {
        // Token is verified, we can proceed with the request.
    }
    else
    {
        // Token verification failed, we should throw an exception.
    }
}

---

Continuous Integration

The project is continuously tested by GitHub actions.

Code of Conduct

This project adheres to a Contributor Code of Conduct. By participating in this project and its community, you're expected to uphold this code.

Contributing

See CONTRIBUTING for details.