<?php

/*

MySQL Session storage. Designed to work with the following table:

CREATE TABLE IF NOT EXISTS `phpsessions` (
  `SESSID` int(11) NOT NULL,
  `data` text CHARACTER SET utf8 NOT NULL,
  `last` int(11) NOT NULL,
  UNIQUE KEY `SESSID` (`SESSID`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

`last` is a unix timestamp, hence INT.

Take note that in it's current form this system wont support hexadecimal session IDs, which mean the default
IDs, assigned by PHP will be trimmed. This is done, because SESSID has to be a unique column, and this is only
achievable with columns of type INT. If you wish to employ a TEXT column, you'll have to modify the _write
function to accomodate detection of existing records other than ON DUPLICATE UPDATE, since this only works with
unique fields.

Fucntion names are self-explanatory.

Debugging mode is enabled, uncomment the specified lines in order to disable it.

*/

ini_set('session.gc_probability', 1);       // Set to 1000 to make sure cleanup fires every time
ini_set('session.gc_divisor', 1000);
ini_set('session.gc_maxlifetime', 1440);    // Reduce to see cleanup in action


// Main config function (of sorts)
function __DB($string)
{
    // Set access credentials
    $db_host = "yourhost";
    $db_user = "yourname";
    $db_pass = "yourpass";
    $db_name = "database";  // Database name
    switch($string)
    {
        case "host":
            return $db_host;
        case "user":
            return $db_user;
        case "pass":
            return $db_pass;
        case "name":
            return $db_name;
    }
    return '';
}

### BEGIN CUSTOM SESSION RECORDING FUNCTIONS ##################################################

function _open($sess_path, $sess_name)
{
    // Since a session is openned on every page load, you might want to disable this anyway
    // Output debug information to a file, uncomment next line to disable
    // /*
    $file=fopen("debug.txt","a");
    $ostring = time() . " :: Openning session\n";
    fwrite($file,$ostring);
    fclose($file);
    // */

    // Must always return true; if persistent connections are possible, setup the use of one here
    // You may also generate your own ID here, just make sure it's compatible with the var type of the db column
    // Since the sonctructor takes two parameters, you may want to use them, in case you forked your code to use
    // several locations to store diffirent sessions or for whatever crazy reason you might. Don't remove them
    // From the paramether list, though, it will break things
    return true;
}

function _close()
{
    // Output debug information to a file, uncomment next line to disable
    // /*
    $file=fopen("debug.txt","a");
    $ostring = time() . " :: Closing session\n";
    fwrite($file,$ostring);
    fclose($file);
    // */

    // Must always return true; take into account the use of persistent connections here
    return true;
}

function _read($id)
{
    // Open connection to database
    $_sess_db = mysql_connect(__DB("host"), __DB("user"), __DB("pass"));
    mysql_select_db(__DB("name"), $_sess_db);
    // Make sure data is properly escaped and not mangled by the ini settings
    if(get_magic_quotes_gpc()) $id = stripslashes($id);
    $id = mysql_real_escape_string($id);

    $last = time();
    $data = '';

    // Get requested data
    $result = mysql_query("SELECT * FROM `phpsessions` WHERE `SESSID` = '{$id}'");
    while($sess_data = mysql_fetch_array($result))
    {
        $data = $sess_data['data'];
    }
    mysql_close($_sess_db);

    // Output debug information to a file, uncomment next line to disable
    // /*
    $file=fopen("debug.txt","a");
    $ostring = time() . " :: READ << ID: {$id} :: Data: {$data}\n";
    fwrite($file,$ostring);
    fclose($file);
    // */

    // Resulting data is a serialized array, which is exactly what we need. Do not process it, PHP takes care of everything.
    return $data;
}

function _write($id, $data)
{
    // Open connection to database
    $_sess_db = mysql_connect(__DB("host"), __DB("user"), __DB("pass"));
    mysql_select_db(__DB("name"), $_sess_db);
    // Make sure data is properly escaped and not mangled by the ini settings
    if(get_magic_quotes_gpc())
    {
        $id = stripslashes($id);
        $data = stripslashes($data);
    }
    $id = mysql_real_escape_string($id);
    $data = mysql_real_escape_string($data);

    $last = time();

    // Modify database; PHP gives us a serialized array to begin with, so we're cool without processing it.
    $result = mysql_query("
        INSERT INTO `phpsessions` (`SESSID`,`data`,`last`)
        VALUES ('{$id}','{$data}','{$last}')
        ON DUPLICATE KEY UPDATE
            `data` = '{$data}',
            `last` = '{$last}'
        ");
    mysql_close($_sess_db);

    // Output debug information to a file, uncomment next line to disable
    ### NOTE: Changes to the database wont be visible in the debug until the database is flushed. The database, however, will change in real time ###
    // /*
    $file=fopen("debug.txt","a");
    $ostring = time() . " :: WRITE >> ID: {$id} :: Data: {$data}\n";
    fwrite($file,$ostring);
    fclose($file);
    // */

    return $result;
}

function _destroy($id)
{
    // Output debug information to a file, uncomment next line to disable
    // /*
    $file=fopen("debug.txt","a");
    $ostring = time() . " :: Destroying session: {$id}\n";
    fwrite($file,$ostring);
    fclose($file);
    // */

    // Open connection to database
    $_sess_db = mysql_connect(__DB("host"), __DB("user"), __DB("pass"));
    mysql_select_db(__DB("name"), $_sess_db);
    // Make sure data is properly escaped and not mangled by the ini settings
    if(get_magic_quotes_gpc()) $id = stripslashes($id);
    $id = mysql_real_escape_string($id);

    // Preform requested operation
    $result = mysql_query("DELETE FROM `phpsessions` WHERE `id` = '{$id}'");
    mysql_close($_sess_db);
    return $result;
}

function _clean($max)
{
    // Open connection to database
    $_sess_db = mysql_connect(__DB("host"), __DB("user"), __DB("pass"));
    mysql_select_db(__DB("name"), $_sess_db);
    // Determine deletion treshhold
    $max = (int)$max;
    $old = time() - $max;

    // Finalize cleanup
    $result = mysql_query("DELETE FROM `phpsessions` WHERE `last` < '{$old}'");
    mysql_close($_sess_db);

    // Output debug information to a file, uncomment next line to disable
    // /*
    $file=fopen("debug.txt","a");
    $ostring = time() . " :: Cleaning up sessions older than: {$old}\n";
    fwrite($file,$ostring);
    fclose($file);
    // */

    return $result;
}

// Initialize our custom handler; you might want this at the beginning of the file, but it might cause problems
session_set_save_handler('_open',
                         '_close',
                         '_read',
                         '_write',
                         '_destroy',
                         '_clean');


### END CUSTOM SESSION RECORDING FUNCTIONS ###################################################

?>