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- <h3>ADODB Session Management Manual</h3>
- <p>v5.20.3 01-Jan-2016<br>
- © 2000-2013 John Lim (jlim#natsoft.com)<br>
- © 2014 Damien Regad, Mark Newnham and the ADOdb community</p>
- <p> <font size="1">This software is dual licensed using BSD-Style and
- LGPL. This means you can use it in compiled proprietary and commercial
- products. </font>
- <p>Useful ADOdb links: <a href="http://adodb.sourceforge.net/#download">Download</a>
- <a href="http://adodb.sourceforge.net/#docs">Other Docs</a>
- </p>
- <h3>Introduction</h3>
- <p>This documentation discusses the old adodb-session.php.
- Here is the <a href=docs-session.htm>new documentation</a> on the newer adodb-session2.php.
- <p> We store state information specific to a user or web client in
- session variables. These session variables persist throughout a
- session, as the user moves from page to page. </p>
- <p>To use session variables, call session_start() at the beginning of
- your web page, before your HTTP headers are sent. Then for every
- variable you want to keep alive for the duration of the session, call
- session_register($variable_name). By default, the session handler will
- keep track of the session by using a cookie. You can save objects or
- arrays in session variables also.
- </p>
- <p>The default method of storing sessions is to store it in a file.
- However if you have special needs such as you:
- </p>
- <ul>
- <li>Have multiple web servers that need to share session info</li>
- <li>Need to do special processing of each session</li>
- <li>Require notification when a session expires</li>
- </ul>
- <p>The ADOdb session handler provides you with the above
- additional capabilities by storing the session information as records
- in a database table that can be shared across multiple servers. </p>
- <p>These records will be garbage collected based on the php.ini [session] timeout settings.
- You can register a notification function to notify you when the record has expired and
- is about to be freed by the garbage collector.</p>
- <p><b>Important Upgrade Notice:</b> Since ADOdb 4.05, the session files
- have been moved to its own folder, adodb/session. This is a rewrite
- of the session code by Ross Smith. The old session code is in
- adodb/session/old. </p>
- <h4>ADOdb Session Handler Features</h4>
- <ul>
- <li>Ability to define a notification function that is called when a
- session expires. Typically
- used to detect session logout and release global resources. </li>
- <li>Optimization of database writes. We crc32 the session data and
- only perform an update
- to the session data if there is a data change. </li>
- <li>Support for large amounts of session data with CLOBs (see
- adodb-session-clob.php). Useful
- for Oracle. </li>
- <li>Support for encrypted session data, see
- adodb-cryptsession.php. Enabling encryption is simply a matter of
- including adodb-cryptsession.php instead of adodb-session.php. </li>
- </ul>
- <h3>Setup</h3>
- <p>There are 3 session management files that you can use:
- </p>
- <pre>adodb-session.php : The default<br>adodb-session-clob.php : Use this if you are storing DATA in clobs<br>adodb-cryptsession.php : Use this if you want to store encrypted session data in the database<br><br>
- </pre>
- <p><strong>Examples</strong>
- <p><pre>
- <font
- color="#004040"> include('adodb/adodb.inc.php');<br> <br><b> $ADODB_SESSION_DRIVER='mysql';<br> $ADODB_SESSION_CONNECT='localhost';<br> $ADODB_SESSION_USER ='scott';<br> $ADODB_SESSION_PWD ='tiger';<br> $ADODB_SESSION_DB ='sessiondb';</b><br> <br> <b>include('adodb/session/adodb-session.php');</b><br> session_start();<br> <br> #<br> # Test session vars, the following should increment on refresh<br> #<br> $_SESSION['AVAR'] += 1;<br> print "<p>\$_SESSION['AVAR']={$_SESSION['AVAR']}</p>";<br></font></pre>
- <p>To force non-persistent connections, call adodb_session_open() first before session_start():
- <p>
- <pre>
- <font color="#004040"><br> include('adodb/adodb.inc.php');<br> <br><b> $ADODB_SESSION_DRIVER='mysql';<br> $ADODB_SESSION_CONNECT='localhost';<br> $ADODB_SESSION_USER ='scott';<br> $ADODB_SESSION_PWD ='tiger';<br> $ADODB_SESSION_DB ='sessiondb';</b><br> <br> <b>include('adodb/session/adodb-session.php');<br> adodb_sess_open(false,false,false);</b><br> session_start();<br> </font>
- </pre>
- <p> The 3rd parameter to adodb_sess_open($path, $sessname, $connectMode) sets the connection method. You can pass in the following:</p>
- <table width="50%" border="1">
- <tr>
- <td><b>$connectMode</b></td>
- <td><b>Connection Method</b></td>
- </tr>
- <tr>
- <td>true</td>
- <td><p>PConnect( )</p></td>
- </tr>
- <tr>
- <td>false</td>
- <td>Connect( )</td>
- </tr>
- <tr>
- <td>'N'</td>
- <td>NConnect( )</td>
- </tr>
- <tr>
- <td>'P'</td>
- <td>PConnect( )</td>
- </tr>
- <tr>
- <td>'C'</td>
- <td>Connect( )</td>
- </tr>
- </table>
- <p>To use a encrypted sessions, simply replace the file adodb-session.php:</p>
- <pre> <font
- color="#004040"><br> include('adodb/adodb.inc.php');<br> <br><b> $ADODB_SESSION_DRIVER='mysql';<br> $ADODB_SESSION_CONNECT='localhost';<br> $ADODB_SESSION_USER ='scott';<br> $ADODB_SESSION_PWD ='tiger';<br> $ADODB_SESSION_DB ='sessiondb';<br> <br> include('adodb/session/adodb-cryptsession.php');</b><br> session_start();</font><br>
- </pre>
- <p>And the same technique for adodb-session-clob.php:</p>
- <pre> <font
- color="#004040"><br> include('adodb/adodb.inc.php');<br> <br><b> $ADODB_SESSION_DRIVER='mysql';<br> $ADODB_SESSION_CONNECT='localhost';<br> $ADODB_SESSION_USER ='scott';<br> $ADODB_SESSION_PWD ='tiger';<br> $ADODB_SESSION_DB ='sessiondb';<br> <br> include('adodb/session/adodb-session-clob.php');</b><br> session_start();</font>
- </pre>
- <p>An alternative way to set persistant or non-persistent connections is to call the following function before session_start() is called.
- <pre>
- ADODB_Session::persist('P'); # 'C' for non-persistent connections
- </pre>
- <h4>Installation</h4>
- <p>1. Create this table in your database (MySQL syntax):
- <p><pre> <a
- name="sessiontab"></a> <font color="#004040">
- create table sessions (
- SESSKEY char(32) not null,
- EXPIRY int(11) unsigned not null,
- EXPIREREF varchar(64),
- DATA text not null,
- primary key (sesskey)
- );</font>
- </pre>
- <p>You may want to rename the 'data' field to 'session_data' as
- 'data' appears to be a reserved word for one or more of the following:
- <ul>
- <li> ANSI SQL
- <li> IBM DB2
- <li> MS SQL Server
- <li> Postgres
- <li> SAP
- </ul>
- <p>
- If you do, then execute:
- <pre>
- ADODB_Session::dataFieldName('session_data');
- </pre>
- <p> For the adodb-session-clob.php version, create this:
- <p> <pre>
- <font
- color="#004040"><br> create table sessions (<br> SESSKEY char(32) not null,<br> EXPIRY int(11) unsigned not null,<br> EXPIREREF varchar(64),<br> DATA CLOB,<br> primary key (sesskey)<br> );</font>
- </pre>
- <p>2. Then define the following parameters. You can either modify this file, or define them before this file is included:
- <pre> <font
- color="#004040"><br> $ADODB_SESSION_DRIVER='database driver, eg. mysql or ibase';<br> $ADODB_SESSION_CONNECT='server to connect to';<br> $ADODB_SESSION_USER ='user';<br> $ADODB_SESSION_PWD ='password';<br> $ADODB_SESSION_DB ='database';<br> $ADODB_SESSION_TBL = 'sessions'; # setting this is optional<br> </font>
- </pre><p>
- When the session is created, $<b>ADODB_SESS_CONN</b> holds the connection object.<br> <br> 3. Recommended is PHP 4.0.6 or later. There are documented session bugs in earlier versions of PHP.
- <h3>Notifications</h3>
- <p>You can receive notification when your session is cleaned up by the session garbage collector or
- when you call session_destroy().
- <p>PHP's session extension will automatically run a special garbage collection function based on
- your php.ini session.cookie_lifetime and session.gc_probability settings. This will in turn call
- adodb's garbage collection function, which can be setup to do notification.
- <p>
- <pre>
- PHP Session --> ADOdb Session --> Find all recs --> Send --> Delete queued
- GC Function GC Function to be deleted notification records
- executed at called by for all recs
- random time Session Extension queued for deletion
- </pre>
- <p>When a session is created, we need to store a value in the session record (in the EXPIREREF field), typically
- the userid of the session. Later when the session has expired, just before the record is deleted,
- we reload the EXPIREREF field and call the notification function with the value of EXPIREREF, which
- is the userid of the person being logged off.
- <p>ADOdb uses a global variable $ADODB_SESSION_EXPIRE_NOTIFY that you must predefine before session
- start to store the notification configuration.
- $ADODB_SESSION_EXPIRE_NOTIFY is an array with 2 elements, the
- first being the name of the session variable you would like to store in
- the EXPIREREF field, and the 2nd is the notification function's name. </p>
- <p>For example, suppose we want to be notified when a user's session has expired,
- based on the userid. When the user logs in, we store the id in the global session variable
- $USERID. The function name is 'NotifyFn'.
- <p>
- So we define (before session_start() is called): </p>
- <pre> <font color="#004040">
- $ADODB_SESSION_EXPIRE_NOTIFY = array('USERID','NotifyFn');
- </font></pre>
- And when the NotifyFn is called (when the session expires), the
- $USERID is passed in as the first parameter, eg. NotifyFn($userid, $sesskey). The
- session key (which is the primary key of the record in the sessions
- table) is the 2nd parameter.
- <p> Here is an example of a Notification function that deletes some
- records in the database and temporary files: </p>
- <pre><font color="#004040">
- function NotifyFn($expireref, $sesskey)
- {
- global $ADODB_SESS_CONN; # the session connection object
- $user = $ADODB_SESS_CONN->qstr($expireref);
- $ADODB_SESS_CONN->Execute("delete from shopping_cart where user=$user");
- system("rm /work/tmpfiles/$expireref/*");
- }</font>
- </pre>
- <p> NOTE 1: If you have register_globals disabled in php.ini, then you
- will have to manually set the EXPIREREF. E.g. </p>
- <pre> <font color="#004040">
- $GLOBALS['USERID'] = GetUserID();
- $ADODB_SESSION_EXPIRE_NOTIFY = array('USERID','NotifyFn');</font>
- </pre>
- <p> NOTE 2: If you want to change the EXPIREREF after the session
- record has been created, you will need to modify any session variable
- to force a database record update.
- </p>
- <h4>Neat Notification Tricks</h4>
- <p><i>ExpireRef</i> normally holds the user id of the current session.
- </p>
- <p>1. You can then write a session monitor, scanning expireref to see
- who is currently logged on.
- </p>
- <p>2. If you delete the sessions record for a specific user, eg.
- </p>
- <pre>delete from sessions where expireref = '$USER'<br></pre>
- then the user is logged out. Useful for ejecting someone from a
- site.
- <p>3. You can scan the sessions table to ensure no user
- can be logged in twice. Useful for security reasons.
- </p>
- <h3>Using Oracle CLOBs</h3>
- <p>Suppose you are storing the DATA field in a CLOB:
- <pre><font color="#004040">
- CREATE TABLE sessions (
- SESSKEY VARCHAR(32) NOT NULL,
- EXPIRY NUMBER(16) NOT NULL,
- EXPIREREF VARCHAR(64),
- DATA CLOB,
- PRIMARY KEY (sesskey)
- );</font>
- </pre>
- <p>Then your PHP code could look like this:
- <pre>
- ADODB_SESSION_DRIVER='oci8';
- $ADODB_SESSION_CONNECT=$tnsname;
- $ADODB_SESSION_USER ='scott';
- $ADODB_SESSION_PWD = 'tiger';
- $ADODB_SESSION_DB ='';
- $ADODB_SESSION_USE_LOBS = 'clob';
- $ADODB_SESSION_TBL = 'sessions';
- $ADODB_SESS_DEBUG=0;
- include(ADODB_DIR.'/session/adodb-session.php');
- ADODB_Session::persist('P'); # use 'C' for non-persistent connects
- session_start();
- </pre>
- <p>Note that you can set persistance using ADODB_Session::persist('P').
- <h3>Compression/Encryption Schemes</h3>
- Since ADOdb 4.05, thanks to Ross Smith, multiple encryption and
- compression schemes are supported. Currently, supported are:
- <p>
- <pre> MD5Crypt (crypt.inc.php)<br> MCrypt<br> Secure (Horde's emulation of MCrypt, if MCrypt module is not available.)<br> GZip<br> BZip2<br></pre>
- <p>These are stackable. E.g.
- <p><pre>ADODB_Session::filter(new ADODB_Compress_Bzip2());<br>ADODB_Session::filter(new ADODB_Encrypt_MD5());<br></pre>
- will compress and then encrypt the record in the database.
- <h3>adodb_session_regenerate_id()</h3>
- <p>Dynamically change the current session id with a newly generated one and update database. Currently only
- works with cookies. Useful to improve security by reducing the risk of session-hijacking.
- See this article on <a href=http://shiflett.org/articles/session-fixation>Session Fixation</a> for more info
- on the theory behind this feature. Usage:
- <pre>
- $ADODB_SESSION_DRIVER='mysql';
- $ADODB_SESSION_CONNECT='localhost';
- $ADODB_SESSION_USER ='root';
- $ADODB_SESSION_PWD ='abc';
- $ADODB_SESSION_DB ='phplens';
- include('path/to/adodb/session/adodb-session.php');
- session_start();
- # Every 10 page loads, reset cookie for safety.
- # This is extremely simplistic example, better
- # to regenerate only when the user logs in or changes
- # user privilege levels.
- if ((rand()%10) == 0) adodb_session_regenerate_id();
- </pre>
- <p>This function calls session_regenerate_id() internally or simulates it if the function does not exist.
- <h3>Vacuum/Optimize Database</h3>
- <p>During session garbage collection, if postgresql is detected,
- ADOdb can be set to run VACUUM. If mysql is detected, then optimize database
- could be called.You can turn this on or off using:</p>
- <pre>$turnOn = true; # or false
- ADODB_Session::optimize($turnOn);
- </pre>
- <p>The default for optimization is it is disabled.</p>
- <h2>More Info</h2>
- <p>Also see the <a href="docs-adodb.htm">core ADOdb documentation</a>.
- </p>
- </body>
- </html>
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