224 lines
9.2 KiB
Markdown
224 lines
9.2 KiB
Markdown
# Using Sessions and Cookies
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Kohana provides a couple of classes that make it easy to work with both cookies and sessions. At a high level both sessions and cookies provide the same function. They allow the developer to store temporary or persistent information about a specific client for later retrieval.
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Cookies should be used for storing non-private data that is persistent for a long period of time. For example storing a user id or a language preference. Use the [Cookie] class for getting and setting cookies.
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[!!] Kohana uses "signed" cookies. Every cookie that is stored is combined with a secure hash to prevent modification of the cookie. This hash is generated using [Cookie::salt], which uses the [Cookie::$salt] property. You should [change this setting](using.configuration) when your application is live.
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Sessions should be used for storing temporary or private data. Very sensitive data should be stored using the [Session] class with the "database" or "native" adapters. When using the "cookie" adapter, the session should always be encrypted.
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[!!] For more information on best practices with session variables see [the seven deadly sins of sessions](http://lists.nyphp.org/pipermail/talk/2006-December/020358.html).
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# Storing, Retrieving, and Deleting Data
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[Cookie] and [Session] provide a very similar API for storing data. The main difference between them is that sessions are accessed using an object, and cookies are accessed using a static class.
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Accessing the session instance is done using the [Session::instance] method:
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// Get the session instance
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$session = Session::instance();
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When using sessions, you can also get all of the current session data using the [Session::as_array] method:
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// Get all of the session data as an array
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$data = $session->as_array();
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You can also use this to overload the `$_SESSION` global to get and set data in a way more similar to standard PHP:
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// Overload $_SESSION with the session data
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$_SESSION =& $session->as_array();
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// Set session data
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$_SESSION[$key] = $value;
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## Storing Data {#setting}
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Storing session or cookie data is done using the `set` method:
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// Set session data
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$session->set($key, $value);
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// Set cookie data
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Cookie::set($key, $value);
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// Store a user id
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$session->set('user_id', 10);
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Cookie::set('user_id', 10);
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## Retrieving Data {#getting}
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Getting session or cookie data is done using the `get` method:
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// Get session data
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$data = $session->get($key, $default_value);
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// Get cookie data
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$data = Cookie::get($key, $default_value);
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// Get the user id
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$user = $session->get('user_id');
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$user = Cookie::get('user_id');
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## Deleting Data {#deleting}
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Deleting session or cookie data is done using the `delete` method:
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// Delete session data
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$session->delete($key);
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// Delete cookie data
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Cookie::delete($key);
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// Delete the user id
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$session->delete('user_id');
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Cookie::delete('user_id');
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# Configuration {#configuration}
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Both cookies and sessions have several configuration settings which affect how data is stored. Always check these settings before making your application live, as many of them will have a direct affect on the security of your application.
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## Cookie Settings {#cookie-settings}
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All of the cookie settings are changed using static properties. You can either change these settings in `bootstrap.php` or by using a [class extension](using.autoloading#class-extension).
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The most important setting is [Cookie::$salt], which is used for secure signing. This value should be changed and kept secret:
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Cookie::$salt = 'your secret is safe with me';
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[!!] Changing this value will render all cookies that have been set before invalid.
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By default, cookies are stored until the browser is closed. To use a specific lifetime, change the [Cookie::$expiration] setting:
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// Set cookies to expire after 1 week
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Cookie::$expiration = 604800;
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// Alternative to using raw integers, for better clarity
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Cookie::$expiration = Date::WEEK;
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The path that the cookie can be accessed from can be restricted using the [Cookie::$path] setting.
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// Allow cookies only when going to /public/*
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Cookie::$path = '/public/';
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The domain that the cookie can be accessed from can also be restricted, using the [Cookie::$domain] setting.
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// Allow cookies only on the domain www.example.com
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Cookie::$domain = 'www.example.com';
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If you want to make the cookie accessible on all subdomains, use a dot at the beginning of the domain.
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// Allow cookies to be accessed on example.com and *.example.com
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Cookie::$domain = '.example.com';
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To only allow the cookie to be accessed over a secure (HTTPS) connection, use the [Cookie::$secure] setting.
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// Allow cookies to be accessed only on a secure connection
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Cookie::$secure = TRUE;
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// Allow cookies to be accessed on any connection
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Cookie::$secure = FALSE;
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To prevent cookies from being accessed using Javascript, you can change the [Cookie::$httponly] setting.
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// Make cookies inaccessible to Javascript
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Cookie::$httponly = TRUE;
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## Session Adapters {#adapters}
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When creating or accessing an instance of the [Session] class you can decide which session adapter you wish to use. The session adapters that are available to you are:
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Native
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: Stores session data in the default location for your web server. The storage location is defined by [session.save_path](http://php.net/manual/session.configuration.php#ini.session.save-path) in `php.ini` or defined by [ini_set](http://php.net/ini_set).
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Database
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: Stores session data in a database table using the [Session_Database] class. Requires the [Database] module to be enabled.
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Cookie
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: Stores session data in a cookie using the [Cookie] class. **Sessions will have a 4KB limit when using this adapter.**
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The default adapter can be set by changing the value of [Session::$default]. The default adapter is "native".
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[!!] As with cookies, a "lifetime" setting of "0" means that the session will expire when the browser is closed.
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### Session Adapter Settings
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You can apply configuration settings to each of the session adapters by creating a session config file at `APPPATH/config/session.php`. The following sample configuration file defines all the settings for each adapter:
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return array(
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'native' => array(
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'name' => 'session_name',
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'lifetime' => 43200,
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),
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'cookie' => array(
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'name' => 'cookie_name',
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'encrypted' => TRUE,
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'lifetime' => 43200,
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),
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'database' => array(
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'name' => 'cookie_name',
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'encrypted' => TRUE,
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'lifetime' => 43200,
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'group' => 'default',
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'table' => 'table_name',
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'columns' => array(
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'session_id' => 'session_id',
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'last_active' => 'last_active',
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'contents' => 'contents'
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),
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'gc' => 500,
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),
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);
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#### Native Adapter {#adapter-native}
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Type | Setting | Description | Default
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----------|-----------|---------------------------------------------------|-----------
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`string` | name | name of the session | `"session"`
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`integer` | lifetime | number of seconds the session should live for | `0`
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#### Cookie Adapter {#adapter-cookie}
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Type | Setting | Description | Default
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----------|-----------|---------------------------------------------------|-----------
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`string` | name | name of the cookie used to store the session data | `"session"`
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`boolean` | encrypted | encrypt the session data using [Encrypt]? | `FALSE`
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`integer` | lifetime | number of seconds the session should live for | `0`
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#### Database Adapter {#adapter-database}
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Type | Setting | Description | Default
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----------|-----------|---------------------------------------------------|-----------
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`string` | group | [Database::instance] group name | `"default"`
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`string` | table | table name to store sessions in | `"sessions"`
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`array` | columns | associative array of column aliases | `array`
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`integer` | gc | 1:x chance that garbage collection will be run | `500`
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`string` | name | name of the cookie used to store the session data | `"session"`
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`boolean` | encrypted | encrypt the session data using [Encrypt]? | `FALSE`
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`integer` | lifetime | number of seconds the session should live for | `0`
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##### Table Schema
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You will need to create the session storage table in the database. This is the default schema:
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CREATE TABLE `sessions` (
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`session_id` VARCHAR(24) NOT NULL,
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`last_active` INT UNSIGNED NOT NULL,
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`contents` TEXT NOT NULL,
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PRIMARY KEY (`session_id`),
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INDEX (`last_active`)
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) ENGINE = MYISAM;
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##### Table Columns
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You can change the column names to match an existing database schema when connecting to a legacy session table. The default value is the same as the key value.
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session_id
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: the name of the "id" column
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last_active
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: UNIX timestamp of the last time the session was updated
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contents
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: session data stored as a serialized string, and optionally encrypted
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