class.Session.php

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<?php
/*
        +-----------------------------------------------------------------------------+
        | ILIAS open source                                                           |
        +-----------------------------------------------------------------------------+
        | Copyright (c) 1998-2001 ILIAS open source, University of Cologne            |
        |                                                                             |
        | This program is free software; you can redistribute it and/or               |
        | modify it under the terms of the GNU General Public License                 |
        | as published by the Free Software Foundation; either version 2              |
        | of the License, or (at your option) any later version.                      |
        |                                                                             |
        | This program is distributed in the hope that it will be useful,             |
        | but WITHOUT ANY WARRANTY; without even the implied warranty of              |
        | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               |
        | GNU General Public License for more details.                                |
        |                                                                             |
        | You should have received a copy of the GNU General Public License           |
        | along with this program; if not, write to the Free Software                 |
        | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. |
        +-----------------------------------------------------------------------------+
*/

// Datei:       class.Session.inc
// Benoetigt:    mind. 4.0.1pl2

class Session {
    var $version     = 106;     // V1.06
    var $usesCookies = false;   // Client nimmt Cookies an
    var $transSID    = false;   // Wurde mit --enable-trans-sid
                                // kompiliert  

//---------------------------------------------------------

    function Session($sessionName="SESSID") {
        $this->sendNoCacheHeader();
        
        // force 4 hash bits per character for session_id       // Sascha Hofmann (2005-10-19)
                ini_set("session.hash_bits_per_character","4");
                
        //  Session-Namen setzen, Session initialisieren   
        session_name(isset($sessionName)
            ? $sessionName
            : session_name());

        @session_start();
        
        //  Prüen ob die Session-ID die Standardlänge
        //  von 32 Zeichen hat,
        //  ansonsten Session-ID neu setzen 
        if (strlen(session_id()) < 32)
            {
                mt_srand ((double)microtime()*1000000);
                session_id(md5(uniqid(mt_rand())));
            }
        
        //  Prüfen, ob eine Session-ID übergeben wurde
        //  (über Cookie, POST oder GET)
        $IDpassed = false;
        if  (   isset($_COOKIE[session_name()]) &&
                @strlen($_COOKIE[session_name()]) >= 32
            )   $IDpassed = true;

        if  (   isset($_POST[session_name()]) &&
                @strlen($_POST[session_name()]) >= 32
            )   $IDpassed = true;

        if  (   isset($_GET[session_name()]) &&
                @strlen($_GET[session_name()]) >= 32
            )   $IDpassed = true;
        
        if  (!$IDpassed)  
            {   
                // Es wurde keine (gültige) Session-ID übergeben.
                // Script-Parameter der URL zufügen
                
                $query = @$_SERVER["QUERY_STRING"] != "" ? "?".$_SERVER["QUERY_STRING"] : "";
             
                header("Status: 302 Found");
                
                // Script terminiert
                $this->redirectTo($_SERVER["PHP_SELF"].$query);
            }
            
        // Wenn die Session-ID übergeben wurde, muss sie
                                // nicht unbedingt gültig sein!
        
        // Für weiteren Gebrauch merken
        $this->usesCookies =
                       (isset($_COOKIE[session_name()]) &&
                        @strlen($_COOKIE[session_name()])
                        >= 32);
    }    
 
### -------------------------------------------------------

    function sendNoCacheHeader()    {        
        header("Expires: Sat, 05 Aug 2000 22:27:00 GMT");
        header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
        header("Cache-Control: no-cache, must-revalidate");
        header("Pragma: no-cache");
        header("Cache-Control: post-check=0, pre-check=0");        
    }

### -------------------------------------------------------

    function redirectTo($pathInfo) {
        
        // Relativer Pfad?
        if ($pathInfo[0] != "/")
            {   $pathInfo = substr(getenv("PATH_INFO"),
                                   0,
                                   strrpos(getenv("PATH_INFO"),"/")+1
                                   )
                            .$pathInfo;
            }

        // Läuft dieses Script auf einem non-standard Port? 
        $port    = !preg_match( "/^(80|443)$/",
                                getenv("SERVER_PORT"),
                                $portMatch)
                   ? ":".getenv("SERVER_PORT")
                   : "";
                                         
        // Redirect    
        header("Location: "
               .(($portMatch[1] == 443) ? "https://" : "http://")
               .$_SERVER["HTTP_HOST"].$port.$this->url($pathInfo));
        exit;
    }

### -------------------------------------------------------

    function removeTrail($pathInfo) {
        $dummy = preg_match("/(.*)(?<!&|\?)/",$pathInfo,$match);
        return $match[0];  
    }

### -------------------------------------------------------

    function url($pathInfo)  {        
        if ($this->usesCookies || $this->transSID) return $pathInfo;

        // Anchor-Fragment extrahieren
        $dummyArray = split("#",$pathInfo);
        $pathInfo = $dummyArray[0];

        // evtl. (kaputte) Session-ID(s) aus dem Querystring entfernen
        $pathInfo = preg_replace(   "/[?|&]".session_name()."=[^&]*/",
                                    "",
                                    $pathInfo);
        
        // evtl. Query-Delimiter korrigieren
        if (preg_match("/&/",$pathInfo) && !preg_match("/\?/",$pathInfo))
            {
                // 4ter Parameter für "preg_replace()" erst ab 4.0.1pl2
                $pathInfo = preg_replace("/&/","?",$pathInfo,1); 
            }
        
        // Restmüll entsorgen
        $pathInfo = $this->removeTrail($pathInfo);
        
        // Session-Name und Session-ID frisch hinzufügen  
        $pathInfo .= preg_match("/\?/",$pathInfo) ? "&" : "?";
        $pathInfo .= session_name()."=".session_id();
        
        // Anchor-Fragment wieder anfügen
        $pathInfo .= isset($dummyArray[1]) ? "#".$dummyArray[1] : "";
        
        return $pathInfo;                       
    }
    
### -------------------------------------------------------

    function hidden() {
        if ($this->usesCookies || $this->transSID) return "";
        return "<INPUT  type=\"hidden\"
                        name=\"".session_name()."\"
                        value=\"".session_id()."\">";
    }
} // of class    
    
?>