mirror of
https://github.com/EGroupware/egroupware.git
synced 2024-12-13 02:01:05 +01:00
180 lines
10 KiB
HTML
180 lines
10 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
<html>
|
|
<head>
|
|
<title>ADODB Session Management Manual</title>
|
|
<meta http-equiv="Content-Type"
|
|
content="text/html; charset=iso-8859-1">
|
|
<style type="text/css">
|
|
body, td {
|
|
/*font-family: Arial, Helvetica, sans-serif;*/
|
|
font-size: 11pt;
|
|
}
|
|
pre {
|
|
font-size: 9pt;
|
|
background-color: #EEEEEE; padding: .5em; margin: 0px;
|
|
}
|
|
.toplink {
|
|
font-size: 8pt;
|
|
}
|
|
</style>
|
|
</head>
|
|
<body style="background-color: rgb(255, 255, 255);">
|
|
<h3>ADODB Session Management Manual</h3>
|
|
<p>
|
|
V4.50 6 July 2004 (c) 2000-2004 John Lim (jlim#natsoft.com.my)
|
|
</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>
|
|
<table border="1">
|
|
<tbody>
|
|
<tr>
|
|
<td><font color="red">Kindly note that the ADOdb home page has
|
|
moved to <a href="http://adodb.sourceforge.net/">http://adodb.sourceforge.net/</a>
|
|
because of the persistent unreliability of http://php.weblogs.com. <b>Please
|
|
change your links</b>!</font></td>
|
|
</tr>
|
|
<tr>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</p>
|
|
<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> 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>Then 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><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.inc.php. Enabling encryption is simply a matter of
|
|
including adodb-cryptsession.inc.php instead of adodb-session.inc.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> To use a encrypted sessions, simply replace the file:</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>
|
|
<h4>Installation</h4>
|
|
<p>1. Create this table in your database (syntax might vary depending on your db):
|
|
<p><pre> <a
|
|
name="sessiontab"></a> <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 text not null,<br> primary key (sesskey)<br> );</font><br>
|
|
</pre>
|
|
<p> For the adodb-session-clob.php version, create this:
|
|
<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 <br> in earlier versions of PHP.
|
|
<h3>Notifications</h3>
|
|
<p>If you want to receive notification when a session expires, then tag
|
|
the session record with a <a href="#sessiontab">EXPIREREF</a> tag (see
|
|
the definition of the sessions table above). Before any session record
|
|
is deleted, ADOdb will call a notification function, passing in the
|
|
EXPIREREF.
|
|
</p>
|
|
<p>When a session is first created, we check a global variable
|
|
$ADODB_SESSION_EXPIRE_NOTIFY. This 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> Suppose we want to be notified when a user's session has expired,
|
|
based on the userid. The user id in the global session variable
|
|
$USERID. The function name is 'NotifyFn'. So we define: </p>
|
|
<pre> <font color="#004040"><br> $ADODB_SESSION_EXPIRE_NOTIFY = array('USERID','NotifyFn');<br> </font></pre>
|
|
And when the NotifyFn is called (when the session expires), we pass the
|
|
$USERID as the first parameter, eg. NotifyFn($userid, $sesskey). The
|
|
session key (which is the primary key of the record in the sessions
|
|
table) is the 2nd parameter.
|
|
<p> Here is an example of a Notification function that deletes some
|
|
records in the database and temporary files: </p>
|
|
<pre><font color="#004040"><br> function NotifyFn($expireref, $sesskey)<br> {<br> global $ADODB_SESS_CONN; # the session connection object<br><br> $user = $ADODB_SESS_CONN->qstr($expireref);<br> $ADODB_SESS_CONN->Execute("delete from shopping_cart where user=$user");<br> system("rm /work/tmpfiles/$expireref/*");<br> }</font><br> </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'] =& $_SESSION['USERID'];
|
|
$ADODB_SESSION_EXPIRE_NOTIFY = array('USERID','NotifyFn');</font>
|
|
</pre>
|
|
<p> NOTE 2: If you want to change the EXPIREREF after the session
|
|
record has been created, you will need to modify any session variable
|
|
to force a database record update.
|
|
</p>
|
|
<h4>Neat Notification Tricks</h4>
|
|
<p><i>ExpireRef</i> normally holds the user id of the current session.
|
|
</p>
|
|
<p>1. You can then write a session monitor, scanning expireref to see
|
|
who is currently logged on.
|
|
</p>
|
|
<p>2. If you delete the sessions record for a specific user, eg.
|
|
</p>
|
|
<pre>delete from sessions where expireref = '$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>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.
|
|
<p>Also see the <a href="docs-adodb.htm">core ADOdb documentation</a>.
|
|
</p>
|
|
</body>
|
|
</html>
|