nextcloud/inc/HTTP/WebDAV/Server.php

<?php 
/*
   +----------------------------------------------------------------------+
   | Copyright (c) 2002-2007 Christian Stocker, Hartmut Holzgraefe        |
   | All rights reserved                                                  |
   |                                                                      |
   | Redistribution and use in source and binary forms, with or without   |
   | modification, are permitted provided that the following conditions   |
   | are met:                                                             |
   |                                                                      |
   | 1. Redistributions of source code must retain the above copyright    |
   |    notice, this list of conditions and the following disclaimer.     |
   | 2. Redistributions in binary form must reproduce the above copyright |
   |    notice, this list of conditions and the following disclaimer in   |
   |    the documentation and/or other materials provided with the        |
   |    distribution.                                                     |
   | 3. The names of the authors may not be used to endorse or promote    |
   |    products derived from this software without specific prior        |
   |    written permission.                                               |
   |                                                                      |
   | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS  |
   | "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT    |
   | LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS    |
   | FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE       |
   | COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,  |
   | INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
   | BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;     |
   | LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER     |
   | CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT   |
   | LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN    |
   | ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE      |
   | POSSIBILITY OF SUCH DAMAGE.                                          |
   +----------------------------------------------------------------------+
*/

oc_require_once("HTTP/WebDAV/Tools/_parse_propfind.php");
oc_require_once("HTTP/WebDAV/Tools/_parse_proppatch.php");
oc_require_once("HTTP/WebDAV/Tools/_parse_lockinfo.php");


/**
 * Virtual base class for implementing WebDAV servers 
 *
 * WebDAV server base class, needs to be extended to do useful work
 * 
 * @package HTTP_WebDAV_Server
 * @author  Hartmut Holzgraefe <hholzgra@php.net>
 * @version @package_version@
 */
class HTTP_WebDAV_Server 
{
    // {{{ Member Variables 
    
    /**
     * complete URI for this request
     *
     * @var string 
     */
    var $uri;
    
    
    /**
     * base URI for this request
     *
     * @var string 
     */
    var $base_uri;


    /**
     * URI path for this request
     *
     * @var string 
     */
    var $path;

    /**
     * Realm string to be used in authentification popups
     *
     * @var string 
     */
    var $http_auth_realm = "PHP WebDAV";

    /**
     * String to be used in "X-Dav-Powered-By" header
     *
     * @var string 
     */
    var $dav_powered_by = "";

    /**
     * Remember parsed If: (RFC2518/9.4) header conditions  
     *
     * @var array
     */
    var $_if_header_uris = array();

    /**
     * HTTP response status/message
     *
     * @var string
     */
    var $_http_status = "200 OK";

    /**
     * encoding of property values passed in
     *
     * @var string
     */
    var $_prop_encoding = "utf-8";

    /**
     * Copy of $_SERVER superglobal array
     *
     * Derived classes may extend the constructor to
     * modify its contents
     *
     * @var array
     */
    var $_SERVER;

    // }}}

    // {{{ Constructor 

    /** 
     * Constructor
     *
     * @param void
     */
    function HTTP_WebDAV_Server() 
    {
        // PHP messages destroy XML output -> switch them off
        ini_set("display_errors", 0);

        // copy $_SERVER variables to local _SERVER array
        // so that derived classes can simply modify these
        $this->_SERVER = $_SERVER;
    }

    // }}}

    // {{{ ServeRequest() 
    /** 
     * Serve WebDAV HTTP request
     *
     * dispatch WebDAV HTTP request to the apropriate method handler
     * 
     * @param  void
     * @return void
     */
    function ServeRequest() 
    {
        // prevent warning in litmus check 'delete_fragment'
        if (strstr($this->_SERVER["REQUEST_URI"], '#')) {
            $this->http_status("400 Bad Request");
            return;
        }

        // default uri is the complete request uri
        $uri = "http";
        if (isset($this->_SERVER["HTTPS"]) && $this->_SERVER["HTTPS"] === "on") {
          $uri = "https";
        }
        $uri.= "://".$this->_SERVER["HTTP_HOST"].$this->_SERVER["SCRIPT_NAME"];
        
        // WebDAV has no concept of a query string and clients (including cadaver)
        // seem to pass '?' unencoded, so we need to extract the path info out
        // of the request URI ourselves
        $path_info = substr($this->_SERVER["REQUEST_URI"], strlen($this->_SERVER["SCRIPT_NAME"]));

        // just in case the path came in empty ...
        if (empty($path_info)) {
            $path_info = "/";
        }

        $this->base_uri = $uri;
        $this->uri      = $uri . $path_info;

        // set path
        $this->path = $this->_urldecode($path_info);
        if (!strlen($this->path)) {
            if ($this->_SERVER["REQUEST_METHOD"] == "GET") {
                // redirect clients that try to GET a collection
                // WebDAV clients should never try this while
                // regular HTTP clients might ...
                header("Location: ".$this->base_uri."/");
                return;
            } else {
                // if a WebDAV client didn't give a path we just assume '/'
                $this->path = "/";
            }
        } 
        
        if (ini_get("magic_quotes_gpc")) {
            $this->path = stripslashes($this->path);
        }
        
        
        // identify ourselves
        if (empty($this->dav_powered_by)) {
            header("X-Dav-Powered-By: PHP class: ".get_class($this));
        } else {
            header("X-Dav-Powered-By: ".$this->dav_powered_by);
        }

        // check authentication
        // for the motivation for not checking OPTIONS requests on / see 
        // http://pear.php.net/bugs/bug.php?id=5363
        if ( (   !(($this->_SERVER['REQUEST_METHOD'] == 'OPTIONS') && ($this->path == "/")))
             && (!$this->_check_auth())) {
            // RFC2518 says we must use Digest instead of Basic
            // but Microsoft Clients do not support Digest
            // and we don't support NTLM and Kerberos
            // so we are stuck with Basic here
            header('WWW-Authenticate: Basic realm="'.($this->http_auth_realm).'"');

            // Windows seems to require this being the last header sent
            // (changed according to PECL bug #3138)
            $this->http_status('401 Unauthorized');

            return;
        }
        
        // check 
        if (! $this->_check_if_header_conditions()) {
            return;
        }
        
        // detect requested method names
        $method  = strtolower($this->_SERVER["REQUEST_METHOD"]);
        error_log("serving $method request");
        $wrapper = "http_".$method;
        
        // activate HEAD emulation by GET if no HEAD method found
        if ($method == "head" && !method_exists($this, "head")) {
            $method = "get";
        }
        
        if (method_exists($this, $wrapper) && ($method == "options" || method_exists($this, $method))) {
            $this->$wrapper();  // call method by name
        } else { // method not found/implemented
            if ($this->_SERVER["REQUEST_METHOD"] == "LOCK") {
                $this->http_status("412 Precondition failed");
            } else {
                $this->http_status("405 Method not allowed");
                header("Allow: ".join(", ", $this->_allow()));  // tell client what's allowed
            }
        }
    }

    // }}}

    // {{{ abstract WebDAV methods 

    // {{{ GET() 
    /**
     * GET implementation
     *
     * overload this method to retrieve resources from your server
     * <br>
     * 
     *
     * @abstract 
     * @param array &$params Array of input and output parameters
     * <br><b>input</b><ul>
     * <li> path - 
     * </ul>
     * <br><b>output</b><ul>
     * <li> size - 
     * </ul>
     * @returns int HTTP-Statuscode
     */

    /* abstract
     function GET(&$params) 
     {
     // dummy entry for PHPDoc
     } 
    */

    // }}}

    // {{{ PUT() 
    /**
     * PUT implementation
     *
     * PUT implementation
     *
     * @abstract 
     * @param array &$params
     * @returns int HTTP-Statuscode
     */
    
    /* abstract
     function PUT() 
     {
     // dummy entry for PHPDoc
     } 
    */
    
    // }}}

    // {{{ COPY() 

    /**
     * COPY implementation
     *
     * COPY implementation
     *
     * @abstract 
     * @param array &$params
     * @returns int HTTP-Statuscode
     */
    
    /* abstract
     function COPY() 
     {
     // dummy entry for PHPDoc
     } 
    */

    // }}}

    // {{{ MOVE() 

    /**
     * MOVE implementation
     *
     * MOVE implementation
     *
     * @abstract 
     * @param array &$params
     * @returns int HTTP-Statuscode
     */
    
    /* abstract
     function MOVE() 
     {
     // dummy entry for PHPDoc
     } 
    */

    // }}}

    // {{{ DELETE() 

    /**
     * DELETE implementation
     *
     * DELETE implementation
     *
     * @abstract 
     * @param array &$params
     * @returns int HTTP-Statuscode
     */
    
    /* abstract
     function DELETE() 
     {
     // dummy entry for PHPDoc
     } 
    */
    // }}}

    // {{{ PROPFIND() 

    /**
     * PROPFIND implementation
     *
     * PROPFIND implementation
     *
     * @abstract 
     * @param array &$params
     * @returns int HTTP-Statuscode
     */
    
    /* abstract
     function PROPFIND() 
     {
     // dummy entry for PHPDoc
     } 
    */

    // }}}

    // {{{ PROPPATCH() 

    /**
     * PROPPATCH implementation
     *
     * PROPPATCH implementation
     *
     * @abstract 
     * @param array &$params
     * @returns int HTTP-Statuscode
     */
    
    /* abstract
     function PROPPATCH() 
     {
     // dummy entry for PHPDoc
     } 
    */
    // }}}

    // {{{ LOCK() 

    /**
     * LOCK implementation
     *
     * LOCK implementation
     *
     * @abstract 
     * @param array &$params
     * @returns int HTTP-Statuscode
     */
    
    /* abstract
     function LOCK() 
     {
     // dummy entry for PHPDoc
     } 
    */
    // }}}

    // {{{ UNLOCK() 

    /**
     * UNLOCK implementation
     *
     * UNLOCK implementation
     *
     * @abstract 
     * @param array &$params
     * @returns int HTTP-Statuscode
     */

    /* abstract
     function UNLOCK() 
     {
     // dummy entry for PHPDoc
     } 
    */
    // }}}

    // }}}

    // {{{ other abstract methods 

    // {{{ check_auth() 

    /**
     * check authentication
     *
     * overload this method to retrieve and confirm authentication information
     *
     * @abstract 
     * @param string type Authentication type, e.g. "basic" or "digest"
     * @param string username Transmitted username
     * @param string passwort Transmitted password
     * @returns bool Authentication status
     */
    
    /* abstract
     function checkAuth($type, $username, $password) 
     {
     // dummy entry for PHPDoc
     } 
    */
    
    // }}}

    // {{{ checklock() 

    /**
     * check lock status for a resource
     *
     * overload this method to return shared and exclusive locks 
     * active for this resource
     *
     * @abstract 
     * @param string resource Resource path to check
     * @returns array An array of lock entries each consisting
     *                of 'type' ('shared'/'exclusive'), 'token' and 'timeout'
     */
    
    /* abstract
     function checklock($resource) 
     {
     // dummy entry for PHPDoc
     } 
    */

    // }}}

    // }}}

    // {{{ WebDAV HTTP method wrappers 

    // {{{ http_OPTIONS() 

    /**
     * OPTIONS method handler
     *
     * The OPTIONS method handler creates a valid OPTIONS reply
     * including Dav: and Allowed: headers
     * based on the implemented methods found in the actual instance
     *
     * @param  void
     * @return void
     */
    function http_OPTIONS() 
    {
        // Microsoft clients default to the Frontpage protocol 
        // unless we tell them to use WebDAV
        header("MS-Author-Via: DAV");

        // get allowed methods
        $allow = $this->_allow();

        // dav header
        $dav = array(1);        // assume we are always dav class 1 compliant
        if (isset($allow['LOCK'])) {
            $dav[] = 2;         // dav class 2 requires that locking is supported 
        }

        // tell clients what we found
        $this->http_status("200 OK");
        header("DAV: "  .join(", ", $dav));
        header("Allow: ".join(", ", $allow));

        header("Content-length: 0");
    }

    // }}}


    // {{{ http_PROPFIND() 

    /**
     * PROPFIND method handler
     *
     * @param  void
     * @return void
     */
    function http_PROPFIND() 
    {
        $options = Array();
        $files   = Array();

        $options["path"] = $this->path;
        
        // search depth from header (default is "infinity)
        if (isset($this->_SERVER['HTTP_DEPTH'])) {
            $options["depth"] = $this->_SERVER["HTTP_DEPTH"];
        } else {
            $options["depth"] = "infinity";
        }       

        // analyze request payload
        $propinfo = new _parse_propfind("php://input");
        if (!$propinfo->success) {
            $this->http_status("400 Error");
            return;
        }
        $options['props'] = $propinfo->props;

        // call user handler
        if (!$this->PROPFIND($options, $files)) {
            $files = array("files" => array());
            if (method_exists($this, "checkLock")) {
                // is locked?
                $lock = $this->checkLock($this->path);

                if (is_array($lock) && count($lock)) {
                    $created          = isset($lock['created'])  ? $lock['created']  : time();
                    $modified         = isset($lock['modified']) ? $lock['modified'] : time();
                    $files['files'][] = array("path"  => $this->_slashify($this->path),
                                              "props" => array($this->mkprop("displayname",      $this->path),
                                                               $this->mkprop("creationdate",     $created),
                                                               $this->mkprop("getlastmodified",  $modified),
                                                               $this->mkprop("resourcetype",     ""),
                                                               $this->mkprop("getcontenttype",   ""),
                                                               $this->mkprop("getcontentlength", 0))
                                              );
                }
            }

            if (empty($files['files'])) {
                $this->http_status("404 Not Found");
                return;
            }
        }
        
        // collect namespaces here
        $ns_hash = array();
        
        // Microsoft Clients need this special namespace for date and time values
        $ns_defs = "xmlns:ns0=\"urn:uuid:c2f41010-65b3-11d1-a29f-00aa00c14882/\"";    
    
        // now we loop over all returned file entries
        foreach ($files["files"] as $filekey => $file) {
            
            // nothing to do if no properties were returend for a file
            if (!isset($file["props"]) || !is_array($file["props"])) {
                continue;
            }
            
            // now loop over all returned properties
            foreach ($file["props"] as $key => $prop) {
                // as a convenience feature we do not require that user handlers
                // restrict returned properties to the requested ones
                // here we strip all unrequested entries out of the response
                
                switch($options['props']) {
                case "all":
                    // nothing to remove
                    break;
                    
                case "names":
                    // only the names of all existing properties were requested
                    // so we remove all values
                    unset($files["files"][$filekey]["props"][$key]["val"]);
                    break;
                    
                default:
                    $found = false;
                    
                    // search property name in requested properties 
                    foreach ((array)$options["props"] as $reqprop) {
                        if (!isset($reqprop["xmlns"])) {
                            $reqprop["xmlns"] = "";
                        }
                        if (   $reqprop["name"]  == $prop["name"] 
                               && $reqprop["xmlns"] == $prop["ns"]) {
                            $found = true;
                            break;
                        }
                    }
                    
                    // unset property and continue with next one if not found/requested
                    if (!$found) {
                        $files["files"][$filekey]["props"][$key]="";
                        continue(2);
                    }
                    break;
                }
                
                // namespace handling 
                if (empty($prop["ns"])) continue; // no namespace
                $ns = $prop["ns"]; 
                if ($ns == "DAV:") continue; // default namespace
                if (isset($ns_hash[$ns])) continue; // already known

                // register namespace 
                $ns_name = "ns".(count($ns_hash) + 1);
                $ns_hash[$ns] = $ns_name;
                $ns_defs .= " xmlns:$ns_name=\"$ns\"";
            }
        
            // we also need to add empty entries for properties that were requested
            // but for which no values where returned by the user handler
            if (is_array($options['props'])) {
                foreach ($options["props"] as $reqprop) {
                    if ($reqprop['name']=="") continue; // skip empty entries
                    
                    $found = false;
                    
                    if (!isset($reqprop["xmlns"])) {
                        $reqprop["xmlns"] = "";
                    }

                    // check if property exists in result
                    foreach ($file["props"] as $prop) {
                        if (   $reqprop["name"]  == $prop["name"]
                               && $reqprop["xmlns"] == $prop["ns"]) {
                            $found = true;
                            break;
                        }
                    }
                    
                    if (!$found) {
                        if ($reqprop["xmlns"]==="DAV:" && $reqprop["name"]==="lockdiscovery") {
                            // lockdiscovery is handled by the base class
                            $files["files"][$filekey]["props"][] 
                                = $this->mkprop("DAV:", 
                                                "lockdiscovery", 
                                                $this->lockdiscovery($files["files"][$filekey]['path']));
                        } else {
                            // add empty value for this property
                            $files["files"][$filekey]["noprops"][] =
                                $this->mkprop($reqprop["xmlns"], $reqprop["name"], "");

                            // register property namespace if not known yet
                            if ($reqprop["xmlns"] != "DAV:" && !isset($ns_hash[$reqprop["xmlns"]])) {
                                $ns_name = "ns".(count($ns_hash) + 1);
                                $ns_hash[$reqprop["xmlns"]] = $ns_name;
                                $ns_defs .= " xmlns:$ns_name=\"$reqprop[xmlns]\"";
                            }
                        }
                    }
                }
            }
        }
        
        // now we generate the reply header ...
        $this->http_status("207 Multi-Status");
        header('Content-Type: text/xml; charset="utf-8"');
        
        // ... and payload
        echo "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n";
        echo "<D:multistatus xmlns:D=\"DAV:\">\n";
            
        foreach ($files["files"] as $file) {
            // ignore empty or incomplete entries
            if (!is_array($file) || empty($file) || !isset($file["path"])) continue;
            $path = $file['path'];                  
            if (!is_string($path) || $path==="") continue;

            echo " <D:response $ns_defs>\n";
        
            /* TODO right now the user implementation has to make sure
             collections end in a slash, this should be done in here
             by checking the resource attribute */
            $href = $this->_mergePaths($this->_SERVER['SCRIPT_NAME'], $path);

            /* minimal urlencoding is needed for the resource path */
            $href = $this->_urlencode($href);
        
            echo "  <D:href>$href</D:href>\n";
        
            // report all found properties and their values (if any)
            if (isset($file["props"]) && is_array($file["props"])) {
                echo "  <D:propstat>\n";
                echo "   <D:prop>\n";

                foreach ($file["props"] as $key => $prop) {
                    
                    if (!is_array($prop)) continue;
                    if (!isset($prop["name"])) continue;
                    
                    if (!isset($prop["val"]) || $prop["val"] === "" || $prop["val"] === false) {
                        // empty properties (cannot use empty() for check as "0" is a legal value here)
                        if ($prop["ns"]=="DAV:") {
                            echo "     <D:$prop[name]/>\n";
                        } else if (!empty($prop["ns"])) {
                            echo "     <".$ns_hash[$prop["ns"]].":$prop[name]/>\n";
                        } else {
                            echo "     <$prop[name] xmlns=\"\"/>";
                        }
                    } else if ($prop["ns"] == "DAV:") {
                        // some WebDAV properties need special treatment
                        switch ($prop["name"]) {
                        case "creationdate":
                            echo "     <D:creationdate ns0:dt=\"dateTime.tz\">"
                                . gmdate("Y-m-d\\TH:i:s\\Z", $prop['val'])
                                . "</D:creationdate>\n";
                            break;
                        case "getlastmodified":
                            echo "     <D:getlastmodified ns0:dt=\"dateTime.rfc1123\">"
                                . gmdate("D, d M Y H:i:s ", $prop['val'])
                                . "GMT</D:getlastmodified>\n";
                            break;
                        case "resourcetype":
                            echo "     <D:resourcetype><D:$prop[val]/></D:resourcetype>\n";
                            break;
                        case "supportedlock":
                            echo "     <D:supportedlock>$prop[val]</D:supportedlock>\n";
                            break;
                        case "lockdiscovery":  
                            echo "     <D:lockdiscovery>\n";
                            echo $prop["val"];
                            echo "     </D:lockdiscovery>\n";
                            break;
                        // the following are non-standard Microsoft extensions to the DAV namespace
                        case "lastaccessed":
                            echo "     <D:lastaccessed ns0:dt=\"dateTime.rfc1123\">"
                                . gmdate("D, d M Y H:i:s ", $prop['val'])
                                . "GMT</D:lastaccessed>\n";
                            break;
                        case "ishidden":
                            echo "     <D:ishidden>"
                                . is_string($prop['val']) ? $prop['val'] : ($prop['val'] ? 'true' : 'false')
                                . "</D:ishidden>\n";
                            break;
                        default:                                    
                            echo "     <D:$prop[name]>"
                                . $this->_prop_encode(htmlspecialchars($prop['val']))
                                .     "</D:$prop[name]>\n";                               
                            break;
                        }
                    } else {
                        // properties from namespaces != "DAV:" or without any namespace 
                        if ($prop["ns"]) {
                            echo "     <" . $ns_hash[$prop["ns"]] . ":$prop[name]>"
                                . $this->_prop_encode(htmlspecialchars($prop['val']))
                                . "</" . $ns_hash[$prop["ns"]] . ":$prop[name]>\n";
                        } else {
                            echo "     <$prop[name] xmlns=\"\">"
                                . $this->_prop_encode(htmlspecialchars($prop['val']))
                                . "</$prop[name]>\n";
                        }                               
                    }
                }

                echo "   </D:prop>\n";
                echo "   <D:status>HTTP/1.1 200 OK</D:status>\n";
                echo "  </D:propstat>\n";
            }
       
            // now report all properties requested but not found
            if (isset($file["noprops"])) {
                echo "  <D:propstat>\n";
                echo "   <D:prop>\n";

                foreach ($file["noprops"] as $key => $prop) {
                    if ($prop["ns"] == "DAV:") {
                        echo "     <D:$prop[name]/>\n";
                    } else if ($prop["ns"] == "") {
                        echo "     <$prop[name] xmlns=\"\"/>\n";
                    } else {
                        echo "     <" . $ns_hash[$prop["ns"]] . ":$prop[name]/>\n";
                    }
                }

                echo "   </D:prop>\n";
                echo "   <D:status>HTTP/1.1 404 Not Found</D:status>\n";
                echo "  </D:propstat>\n";
            }
            
            echo " </D:response>\n";
        }
        
        echo "</D:multistatus>\n";
    }

    
    // }}}
    
    // {{{ http_PROPPATCH() 

    /**
     * PROPPATCH method handler
     *
     * @param  void
     * @return void
     */
    function http_PROPPATCH() 
    {
        if ($this->_check_lock_status($this->path)) {
            $options = Array();

            $options["path"] = $this->path;

            $propinfo = new _parse_proppatch("php://input");
            
            if (!$propinfo->success) {
                $this->http_status("400 Error");
                return;
            }
            
            $options['props'] = $propinfo->props;
            
            $responsedescr = $this->PROPPATCH($options);
            
            $this->http_status("207 Multi-Status");
            header('Content-Type: text/xml; charset="utf-8"');
            
            echo "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n";

            echo "<D:multistatus xmlns:D=\"DAV:\">\n";
            echo " <D:response>\n";
            echo "  <D:href>".$this->_urlencode($this->_mergePaths($this->_SERVER["SCRIPT_NAME"], $this->path))."</D:href>\n";

            foreach ($options["props"] as $prop) {
                echo "   <D:propstat>\n";
                echo "    <D:prop><$prop[name] xmlns=\"$prop[ns]\"/></D:prop>\n";
                echo "    <D:status>HTTP/1.1 $prop[status]</D:status>\n";
                echo "   </D:propstat>\n";
            }

            if ($responsedescr) {
                echo "  <D:responsedescription>".
                    $this->_prop_encode(htmlspecialchars($responsedescr)).
                    "</D:responsedescription>\n";
            }

            echo " </D:response>\n";
            echo "</D:multistatus>\n";
        } else {
            $this->http_status("423 Locked");
        }
    }
    
    // }}}


    // {{{ http_MKCOL() 

    /**
     * MKCOL method handler
     *
     * @param  void
     * @return void
     */
    function http_MKCOL() 
    {
        $options = Array();

        $options["path"] = $this->path;

        $stat = $this->MKCOL($options);

        $this->http_status($stat);
    }

    // }}}


    // {{{ http_GET() 

    /**
     * GET method handler
     *
     * @param void
     * @returns void
     */
    function http_GET() 
    {
        // TODO check for invalid stream
        $options         = Array();
        $options["path"] = $this->path;

        $this->_get_ranges($options);

        if (true === ($status = $this->GET($options))) {
            if (!headers_sent()) {
                $status = "200 OK";

                if (!isset($options['mimetype'])) {
                    $options['mimetype'] = "application/octet-stream";
                }
                header("Content-type: $options[mimetype]");
                
                if (isset($options['mtime'])) {
                    header("Last-modified:".gmdate("D, d M Y H:i:s ", $options['mtime'])."GMT");
                }
                
                if (isset($options['stream'])) {
                    // GET handler returned a stream
                    if (!empty($options['ranges']) && (0===fseek($options['stream'], 0, SEEK_SET))) {
                        // partial request and stream is seekable 
                        
                        if (count($options['ranges']) === 1) {
                            $range = $options['ranges'][0];
                            
                            if (isset($range['start'])) {
                                fseek($options['stream'], $range['start'], SEEK_SET);
                                if (feof($options['stream'])) {
                                    $this->http_status("416 Requested range not satisfiable");
                                    return;
                                }

                                if (isset($range['end'])) {
                                    $size = $range['end']-$range['start']+1;
                                    $this->http_status("206 partial");
                                    header("Content-length: $size");
                                    header("Content-range: $range[start]-$range[end]/"
                                           . (isset($options['size']) ? $options['size'] : "*"));
                                    while ($size && !feof($options['stream'])) {
                                        $buffer = fread($options['stream'], 4096);
                                        $size  -= $this->bytes($buffer);
                                        echo $buffer;
                                    }
                                } else {
                                    $this->http_status("206 partial");
                                    if (isset($options['size'])) {
                                        header("Content-length: ".($options['size'] - $range['start']));
                                        header("Content-range: ".$range['start']."-".$range['end']."/"
                                               . (isset($options['size']) ? $options['size'] : "*"));
                                    }
                                    fpassthru($options['stream']);
                                }
                            } else {
                                header("Content-length: ".$range['last']);
                                fseek($options['stream'], -$range['last'], SEEK_END);
                                fpassthru($options['stream']);
                            }
                        } else {
                            $this->_multipart_byterange_header(); // init multipart
                            foreach ($options['ranges'] as $range) {
                                // TODO what if size unknown? 500?
                                if (isset($range['start'])) {
                                    $from = $range['start'];
                                    $to   = !empty($range['end']) ? $range['end'] : $options['size']-1; 
                                } else {
                                    $from = $options['size'] - $range['last']-1;
                                    $to   = $options['size'] -1;
                                }
                                $total = isset($options['size']) ? $options['size'] : "*"; 
                                $size  = $to - $from + 1;
                                $this->_multipart_byterange_header($options['mimetype'], $from, $to, $total);


                                fseek($options['stream'], $from, SEEK_SET);
                                while ($size && !feof($options['stream'])) {
                                    $buffer = fread($options['stream'], 4096);
                                    $size  -= $this->bytes($buffer);
                                    echo $buffer;
                                }
                            }
                            $this->_multipart_byterange_header(); // end multipart
                        }
                    } else {
                        // normal request or stream isn't seekable, return full content
                        if (isset($options['size'])) {
                            header("Content-length: ".$options['size']);
                        }
                        fpassthru($options['stream']);
                        return; // no more headers
                    }
                } elseif (isset($options['data'])) {
                    if (is_array($options['data'])) {
                        // reply to partial request
                    } else {
                        header("Content-length: ".$this->bytes($options['data']));
                        echo $options['data'];
                    }
                }
            } 
        } 

        if (!headers_sent()) {
            if (false === $status) {
                $this->http_status("404 not found");
            } else {
                // TODO: check setting of headers in various code paths above
                $this->http_status("$status");
            }
        }
    }


    /**
     * parse HTTP Range: header
     *
     * @param  array options array to store result in
     * @return void
     */
    function _get_ranges(&$options) 
    {
        // process Range: header if present
        if (isset($this->_SERVER['HTTP_RANGE'])) {

            // we only support standard "bytes" range specifications for now
            if (preg_match('/bytes\s*=\s*(.+)/', $this->_SERVER['HTTP_RANGE'], $matches)) {
                $options["ranges"] = array();

                // ranges are comma separated
                foreach (explode(",", $matches[1]) as $range) {
                    // ranges are either from-to pairs or just end positions
                    list($start, $end) = explode("-", $range);
                    $options["ranges"][] = ($start==="") 
                        ? array("last"=>$end) 
                        : array("start"=>$start, "end"=>$end);
                }
            }
        }
    }

    /**
     * generate separator headers for multipart response
     *
     * first and last call happen without parameters to generate 
     * the initial header and closing sequence, all calls inbetween
     * require content mimetype, start and end byte position and
     * optionaly the total byte length of the requested resource
     *
     * @param  string  mimetype
     * @param  int     start byte position
     * @param  int     end   byte position
     * @param  int     total resource byte size
     */
    function _multipart_byterange_header($mimetype = false, $from = false, $to=false, $total=false) 
    {
        if ($mimetype === false) {
            if (!isset($this->multipart_separator)) {
                // initial

                // a little naive, this sequence *might* be part of the content
                // but it's really not likely and rather expensive to check 
                $this->multipart_separator = "SEPARATOR_".md5(microtime());

                // generate HTTP header
                header("Content-type: multipart/byteranges; boundary=".$this->multipart_separator);
            } else {
                // final 

                // generate closing multipart sequence
                echo "\n--{$this->multipart_separator}--";
            }
        } else {
            // generate separator and header for next part
            echo "\n--{$this->multipart_separator}\n";
            echo "Content-type: $mimetype\n";
            echo "Content-range: $from-$to/". ($total === false ? "*" : $total);
            echo "\n\n";
        }
    }

            

    // }}}

    // {{{ http_HEAD() 

    /**
     * HEAD method handler
     *
     * @param  void
     * @return void
     */
    function http_HEAD() 
    {
        $status          = false;
        $options         = Array();
        $options["path"] = $this->path;
        
        if (method_exists($this, "HEAD")) {
            $status = $this->head($options);
        } else if (method_exists($this, "GET")) {
            ob_start();
            $status = $this->GET($options);
            if (!isset($options['size'])) {
                $options['size'] = ob_get_length();
            }
            ob_end_clean();
        }
        
        if (!isset($options['mimetype'])) {
            $options['mimetype'] = "application/octet-stream";
        }
        header("Content-type: $options[mimetype]");
        
        if (isset($options['mtime'])) {
            header("Last-modified:".gmdate("D, d M Y H:i:s ", $options['mtime'])."GMT");
        }
                
        if (isset($options['size'])) {
            header("Content-length: ".$options['size']);
        }

        if ($status === true)  $status = "200 OK";
        if ($status === false) $status = "404 Not found";
        
        $this->http_status($status);
    }

    // }}}

    // {{{ http_PUT() 

    /**
     * PUT method handler
     *
     * @param  void
     * @return void
     */
    function http_PUT() 
    {
        if ($this->_check_lock_status($this->path)) {
            $options                   = Array();
            $options["path"]           = $this->path;
            $options["content_length"] = $this->_SERVER["CONTENT_LENGTH"];

            // get the Content-type 
            if (isset($this->_SERVER["CONTENT_TYPE"])) {
                // for now we do not support any sort of multipart requests
                if (!strncmp($this->_SERVER["CONTENT_TYPE"], "multipart/", 10)) {
                    $this->http_status("501 not implemented");
                    echo "The service does not support mulipart PUT requests";
                    return;
                }
                $options["content_type"] = $this->_SERVER["CONTENT_TYPE"];
            } else {
                // default content type if none given
                $options["content_type"] = "application/octet-stream";
            }

            /* RFC 2616 2.6 says: "The recipient of the entity MUST NOT 
             ignore any Content-* (e.g. Content-Range) headers that it 
             does not understand or implement and MUST return a 501 
             (Not Implemented) response in such cases."
            */ 
            foreach ($this->_SERVER as $key => $val) {
                if (strncmp($key, "HTTP_CONTENT", 11)) continue;
                switch ($key) {
                case 'HTTP_CONTENT_ENCODING': // RFC 2616 14.11
                    // TODO support this if ext/zlib filters are available
                    $this->http_status("501 not implemented"); 
                    echo "The service does not support '$val' content encoding";
                    return;

                case 'HTTP_CONTENT_LANGUAGE': // RFC 2616 14.12
                    // we assume it is not critical if this one is ignored
                    // in the actual PUT implementation ...
                    $options["content_language"] = $val;
                    break;

                case 'HTTP_CONTENT_LENGTH':
                    // defined on IIS and has the same value as CONTENT_LENGTH
                    break;

                case 'HTTP_CONTENT_LOCATION': // RFC 2616 14.14
                    /* The meaning of the Content-Location header in PUT 
                     or POST requests is undefined; servers are free 
                     to ignore it in those cases. */
                    break;

                case 'HTTP_CONTENT_RANGE':    // RFC 2616 14.16
                    // single byte range requests are supported
                    // the header format is also specified in RFC 2616 14.16
                    // TODO we have to ensure that implementations support this or send 501 instead
                    if (!preg_match('@bytes\s+(\d+)-(\d+)/((\d+)|\*)@', $val, $matches)) {
                        $this->http_status("400 bad request"); 
                        echo "The service does only support single byte ranges";
                        return;
                    }
                    
                    $range = array("start"=>$matches[1], "end"=>$matches[2]);
                    if (is_numeric($matches[3])) {
                        $range["total_length"] = $matches[3];
                    }
                    $option["ranges"][] = $range;

                    // TODO make sure the implementation supports partial PUT
                    // this has to be done in advance to avoid data being overwritten
                    // on implementations that do not support this ...
                    break;

                case 'HTTP_CONTENT_TYPE':
                    // defined on IIS and has the same value as CONTENT_TYPE
                    break;

                case 'HTTP_CONTENT_MD5':      // RFC 2616 14.15
                    // TODO: maybe we can just pretend here?
                    $this->http_status("501 not implemented"); 
                    echo "The service does not support content MD5 checksum verification"; 
                    return;

                default: 
                    // any other unknown Content-* headers
                    $this->http_status("501 not implemented"); 
                    echo "The service does not support '$key'"; 
                    return;
                }
            }
            $options["stream"] = fopen("php://input", "r");

            $stat = $this->PUT($options);

            if ($stat === false) {
                $stat = "403 Forbidden";
            } else if (is_resource($stat) && get_resource_type($stat) == "stream") {
                $stream = $stat;

                $stat = $options["new"] ? "201 Created" : "204 No Content";

                if (!empty($options["ranges"])) {
                    // TODO multipart support is missing (see also above)
                    if (0 == fseek($stream, $range[0]["start"], SEEK_SET)) {
                        $length = $range[0]["end"]-$range[0]["start"]+1;
                        if (!fwrite($stream, fread($options["stream"], $length))) {
                            $stat = "403 Forbidden"; 
                        }
                    } else {
                        $stat = "403 Forbidden"; 
                    }
                } else {
                    while (!feof($options["stream"])) {
                        if (false === fwrite($stream, fread($options["stream"], 4096))) {
                            $stat = "403 Forbidden"; 
                            break;
                        }
                    }
                }

                fclose($stream);            
            } 

            $this->http_status($stat);
        } else {
            $this->http_status("423 Locked");
        }
    }

    // }}}


    // {{{ http_DELETE() 

    /**
     * DELETE method handler
     *
     * @param  void
     * @return void
     */
    function http_DELETE() 
    {
        // check RFC 2518 Section 9.2, last paragraph
        if (isset($this->_SERVER["HTTP_DEPTH"])) {
            if ($this->_SERVER["HTTP_DEPTH"] != "infinity") {
                $this->http_status("400 Bad Request");
                return;
            }
        }

        // check lock status
        if ($this->_check_lock_status($this->path)) {
            // ok, proceed
            $options         = Array();
            $options["path"] = $this->path;

            $stat = $this->DELETE($options);

            $this->http_status($stat);
        } else {
            // sorry, its locked
            $this->http_status("423 Locked");
        }
    }

    // }}}

    // {{{ http_COPY() 

    /**
     * COPY method handler
     *
     * @param  void
     * @return void
     */
    function http_COPY() 
    {
        // no need to check source lock status here 
        // destination lock status is always checked by the helper method
        $this->_copymove("copy");
    }

    // }}}

    // {{{ http_MOVE() 

    /**
     * MOVE method handler
     *
     * @param  void
     * @return void
     */
    function http_MOVE() 
    {
        if ($this->_check_lock_status($this->path)) {
            // destination lock status is always checked by the helper method
            $this->_copymove("move");
        } else {
            $this->http_status("423 Locked");
        }
    }

    // }}}


    // {{{ http_LOCK() 

    /**
     * LOCK method handler
     *
     * @param  void
     * @return void
     */
    function http_LOCK() 
    {
        $options         = Array();
        $options["path"] = $this->path;
        
        if (isset($this->_SERVER['HTTP_DEPTH'])) {
            $options["depth"] = $this->_SERVER["HTTP_DEPTH"];
        } else {
            $options["depth"] = "infinity";
        }
        
        if (isset($this->_SERVER["HTTP_TIMEOUT"])) {
            $options["timeout"] = explode(",", $this->_SERVER["HTTP_TIMEOUT"]);
        }
        
        if (empty($this->_SERVER['CONTENT_LENGTH']) && !empty($this->_SERVER['HTTP_IF'])) {
            // check if locking is possible
            if (!$this->_check_lock_status($this->path)) {
                $this->http_status("423 Locked");
                return;
            }

            // refresh lock
            $options["locktoken"] = substr($this->_SERVER['HTTP_IF'], 2, -2);
            $options["update"]    = $options["locktoken"];

            // setting defaults for required fields, LOCK() SHOULD overwrite these
            $options['owner']     = "unknown";
            $options['scope']     = "exclusive";
            $options['type']      = "write";


            $stat = $this->LOCK($options);
        } else {
            // extract lock request information from request XML payload
            $lockinfo = new _parse_lockinfo("php://input");
            if (!$lockinfo->success) {
                $this->http_status("400 bad request"); 
            }

            // check if locking is possible
            if (!$this->_check_lock_status($this->path, $lockinfo->lockscope === "shared")) {
                $this->http_status("423 Locked");
                return;
            }

            // new lock 
            $options["scope"]     = $lockinfo->lockscope;
            $options["type"]      = $lockinfo->locktype;
            $options["owner"]     = $lockinfo->owner;            
            $options["locktoken"] = $this->_new_locktoken();
            
            $stat = $this->LOCK($options);              
        }
        
        if (is_bool($stat)) {
            $http_stat = $stat ? "200 OK" : "423 Locked";
        } else {
            $http_stat = (string)$stat;
        }
        $this->http_status($http_stat);
        
        if ($http_stat{0} == 2) { // 2xx states are ok 
            if ($options["timeout"]) {
                // if multiple timeout values were given we take the first only
                if (is_array($options["timeout"])) {
                    reset($options["timeout"]);
                    $options["timeout"] = current($options["timeout"]);
                }
                // if the timeout is numeric only we need to reformat it
                if (is_numeric($options["timeout"])) {
                    // more than a million is considered an absolute timestamp
                    // less is more likely a relative value
                    if ($options["timeout"]>1000000) {
                        $timeout = "Second-".($options['timeout']-time());
                    } else {
                        $timeout = "Second-$options[timeout]";
                    }
                } else {
                    // non-numeric values are passed on verbatim,
                    // no error checking is performed here in this case
                    // TODO: send "Infinite" on invalid timeout strings?
                    $timeout = $options["timeout"];
                }
            } else {
                $timeout = "Infinite";
            }
            
            header('Content-Type: text/xml; charset="utf-8"');
            header("Lock-Token: <$options[locktoken]>");
            echo "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n";
            echo "<D:prop xmlns:D=\"DAV:\">\n";
            echo " <D:lockdiscovery>\n";
            echo "  <D:activelock>\n";
            echo "   <D:lockscope><D:$options[scope]/></D:lockscope>\n";
            echo "   <D:locktype><D:$options[type]/></D:locktype>\n";
            echo "   <D:depth>$options[depth]</D:depth>\n";
            echo "   <D:owner>$options[owner]</D:owner>\n";
            echo "   <D:timeout>$timeout</D:timeout>\n";
            echo "   <D:locktoken><D:href>$options[locktoken]</D:href></D:locktoken>\n";
            echo "  </D:activelock>\n";
            echo " </D:lockdiscovery>\n";
            echo "</D:prop>\n\n";
        }
    }
    

    // }}}

    // {{{ http_UNLOCK() 

    /**
     * UNLOCK method handler
     *
     * @param  void
     * @return void
     */
    function http_UNLOCK() 
    {
        $options         = Array();
        $options["path"] = $this->path;

        if (isset($this->_SERVER['HTTP_DEPTH'])) {
            $options["depth"] = $this->_SERVER["HTTP_DEPTH"];
        } else {
            $options["depth"] = "infinity";
        }

        // strip surrounding <>
        $options["token"] = substr(trim($this->_SERVER["HTTP_LOCK_TOKEN"]), 1, -1);  

        // call user method
        $stat = $this->UNLOCK($options);

        $this->http_status($stat);
    }

    // }}}

    // }}}

    // {{{ _copymove() 

    function _copymove($what) 
    {
        $options         = Array();
        $options["path"] = $this->path;

        if (isset($this->_SERVER["HTTP_DEPTH"])) {
            $options["depth"] = $this->_SERVER["HTTP_DEPTH"];
        } else {
            $options["depth"] = "infinity";
        }

        $http_header_host = preg_replace("/:80$/", "", $this->_SERVER["HTTP_HOST"]);

        $url  = parse_url($this->_SERVER["HTTP_DESTINATION"]);
        $path = urldecode($url["path"]);

        if (isset($url["host"])) {
            // TODO check url scheme, too
            $http_host = $url["host"];
            if (isset($url["port"]) && $url["port"] != 80)
                $http_host.= ":".$url["port"];
        } else {
            // only path given, set host to self
            $http_host == $http_header_host;
        }

        if ($http_host == $http_header_host &&
            !strncmp($this->_SERVER["SCRIPT_NAME"], $path,
                     strlen($this->_SERVER["SCRIPT_NAME"]))) {
            $options["dest"] = substr($path, strlen($this->_SERVER["SCRIPT_NAME"]));
            if (!$this->_check_lock_status($options["dest"])) {
                $this->http_status("423 Locked");
                return;
            }

        } else {
            $options["dest_url"] = $this->_SERVER["HTTP_DESTINATION"];
        }

        // see RFC 2518 Sections 9.6, 8.8.4 and 8.9.3
        if (isset($this->_SERVER["HTTP_OVERWRITE"])) {
            $options["overwrite"] = $this->_SERVER["HTTP_OVERWRITE"] == "T";
        } else {
            $options["overwrite"] = true;
        }

        $stat = $this->$what($options);
        $this->http_status($stat);
    }

    // }}}

    // {{{ _allow() 

    /**
     * check for implemented HTTP methods
     *
     * @param  void
     * @return array something
     */
    function _allow() 
    {
        // OPTIONS is always there
        $allow = array("OPTIONS" =>"OPTIONS");

        // all other METHODS need both a http_method() wrapper
        // and a method() implementation
        // the base class supplies wrappers only
        foreach (get_class_methods($this) as $method) {
            if (!strncmp("http_", $method, 5)) {
                $method = strtoupper(substr($method, 5));
                if (method_exists($this, $method)) {
                    $allow[$method] = $method;
                }
            }
        }

        // we can emulate a missing HEAD implemetation using GET
        if (isset($allow["GET"]))
            $allow["HEAD"] = "HEAD";

        // no LOCK without checklok()
        if (!method_exists($this, "checklock")) {
            unset($allow["LOCK"]);
            unset($allow["UNLOCK"]);
        }

        return $allow;
    }

    // }}}

    /**
     * helper for property element creation
     *
     * @param  string  XML namespace (optional)
     * @param  string  property name
     * @param  string  property value
     * @return array   property array
     */
    function mkprop() 
    {
        $args = func_get_args();
        if (count($args) == 3) {
            return array("ns"   => $args[0], 
                         "name" => $args[1],
                         "val"  => $args[2]);
        } else {
            return array("ns"   => "DAV:", 
                         "name" => $args[0],
                         "val"  => $args[1]);
        }
    }

    // {{{ _check_auth 

    /**
     * check authentication if check is implemented
     * 
     * @param  void
     * @return bool  true if authentication succeded or not necessary
     */
    function _check_auth() 
    {
        $auth_type = isset($this->_SERVER["AUTH_TYPE"]) 
            ? $this->_SERVER["AUTH_TYPE"] 
            : null;

        $auth_user = isset($this->_SERVER["PHP_AUTH_USER"]) 
            ? $this->_SERVER["PHP_AUTH_USER"] 
            : null;

        $auth_pw   = isset($this->_SERVER["PHP_AUTH_PW"]) 
            ? $this->_SERVER["PHP_AUTH_PW"] 
            : null;

        if (method_exists($this, "checkAuth")) {
            // PEAR style method name
            return $this->checkAuth($auth_type, $auth_user, $auth_pw);
        } else if (method_exists($this, "check_auth")) {
            // old (pre 1.0) method name
            return $this->check_auth($auth_type, $auth_user, $auth_pw);
        } else {
            // no method found -> no authentication required
            return true;
        }
    }

    // }}}

    // {{{ UUID stuff 
    
    /**
     * generate Unique Universal IDentifier for lock token
     *
     * @param  void
     * @return string  a new UUID
     */
    function _new_uuid() 
    {
        // use uuid extension from PECL if available
        if (function_exists("uuid_create")) {
            return uuid_create();
        }

        // fallback
        $uuid = md5(microtime().getmypid());    // this should be random enough for now

        // set variant and version fields for 'true' random uuid
        $uuid{12} = "4";
        $n = 8 + (ord($uuid{16}) & 3);
        $hex = "0123456789abcdef";
        $uuid{16} = $hex{$n};

        // return formated uuid
        return substr($uuid,  0, 8)."-"
            .  substr($uuid,  8, 4)."-"
            .  substr($uuid, 12, 4)."-"
            .  substr($uuid, 16, 4)."-"
            .  substr($uuid, 20);
    }

    /**
     * create a new opaque lock token as defined in RFC2518
     *
     * @param  void
     * @return string  new RFC2518 opaque lock token
     */
    function _new_locktoken() 
    {
        return "opaquelocktoken:".$this->_new_uuid();
    }

    // }}}

    // {{{ WebDAV If: header parsing 

    /**
     * 
     *
     * @param  string  header string to parse
     * @param  int     current parsing position
     * @return array   next token (type and value)
     */
    function _if_header_lexer($string, &$pos) 
    {
        // skip whitespace
        while (ctype_space($string{$pos})) {
            ++$pos;
        }

        // already at end of string?
        if (strlen($string) <= $pos) {
            return false;
        }

        // get next character
        $c = $string{$pos++};

        // now it depends on what we found
        switch ($c) {
        case "<":
            // URIs are enclosed in <...>
            $pos2 = strpos($string, ">", $pos);
            $uri  = substr($string, $pos, $pos2 - $pos);
            $pos  = $pos2 + 1;
            return array("URI", $uri);

        case "[":
            //Etags are enclosed in [...]
            if ($string{$pos} == "W") {
                $type = "ETAG_WEAK";
                $pos += 2;
            } else {
                $type = "ETAG_STRONG";
            }
            $pos2 = strpos($string, "]", $pos);
            $etag = substr($string, $pos + 1, $pos2 - $pos - 2);
            $pos  = $pos2 + 1;
            return array($type, $etag);

        case "N":
            // "N" indicates negation
            $pos += 2;
            return array("NOT", "Not");

        default:
            // anything else is passed verbatim char by char
            return array("CHAR", $c);
        }
    }

    /** 
     * parse If: header
     *
     * @param  string  header string
     * @return array   URIs and their conditions
     */
    function _if_header_parser($str) 
    {
        $pos  = 0;
        $len  = strlen($str);
        $uris = array();

        // parser loop
        while ($pos < $len) {
            // get next token
            $token = $this->_if_header_lexer($str, $pos);

            // check for URI
            if ($token[0] == "URI") {
                $uri   = $token[1]; // remember URI
                $token = $this->_if_header_lexer($str, $pos); // get next token
            } else {
                $uri = "";
            }

            // sanity check
            if ($token[0] != "CHAR" || $token[1] != "(") {
                return false;
            }

            $list  = array();
            $level = 1;
            $not   = "";
            while ($level) {
                $token = $this->_if_header_lexer($str, $pos);
                if ($token[0] == "NOT") {
                    $not = "!";
                    continue;
                }
                switch ($token[0]) {
                case "CHAR":
                    switch ($token[1]) {
                    case "(":
                        $level++;
                        break;
                    case ")":
                        $level--;
                        break;
                    default:
                        return false;
                    }
                    break;

                case "URI":
                    $list[] = $not."<$token[1]>";
                    break;

                case "ETAG_WEAK":
                    $list[] = $not."[W/'$token[1]']>";
                    break;

                case "ETAG_STRONG":
                    $list[] = $not."['$token[1]']>";
                    break;

                default:
                    return false;
                }
                $not = "";
            }

            if (isset($uris[$uri]) && is_array($uris[$uri])) {
                $uris[$uri] = array_merge($uris[$uri], $list);
            } else {
                $uris[$uri] = $list;
            }
        }

        return $uris;
    }

    /**
     * check if conditions from "If:" headers are meat 
     *
     * the "If:" header is an extension to HTTP/1.1
     * defined in RFC 2518 section 9.4
     *
     * @param  void
     * @return void
     */
    function _check_if_header_conditions() 
    {
        if (isset($this->_SERVER["HTTP_IF"])) {
            $this->_if_header_uris =
                $this->_if_header_parser($this->_SERVER["HTTP_IF"]);

            foreach ($this->_if_header_uris as $uri => $conditions) {
                if ($uri == "") {
                    $uri = $this->uri;
                }
                // all must match
                $state = true;
                foreach ($conditions as $condition) {
                    // lock tokens may be free form (RFC2518 6.3)
                    // but if opaquelocktokens are used (RFC2518 6.4)
                    // we have to check the format (litmus tests this)
                    if (!strncmp($condition, "<opaquelocktoken:", strlen("<opaquelocktoken"))) {
                        if (!preg_match('/^<opaquelocktoken:[[:xdigit:]]{8}-[[:xdigit:]]{4}-[[:xdigit:]]{4}-[[:xdigit:]]{4}-[[:xdigit:]]{12}>$/', $condition)) {
                            $this->http_status("423 Locked");
                            return false;
                        }
                    }
                    if (!$this->_check_uri_condition($uri, $condition)) {
                        $this->http_status("412 Precondition failed");
                        $state = false;
                        break;
                    }
                }

                // any match is ok
                if ($state == true) {
                    return true;
                }
            }
            return false;
        }
        return true;
    }

    /**
     * Check a single URI condition parsed from an if-header
     *
     * Check a single URI condition parsed from an if-header
     *
     * @abstract 
     * @param string $uri URI to check
     * @param string $condition Condition to check for this URI
     * @returns bool Condition check result
     */
    function _check_uri_condition($uri, $condition) 
    {
        // not really implemented here, 
        // implementations must override

        // a lock token can never be from the DAV: scheme
        // litmus uses DAV:no-lock in some tests
        if (!strncmp("<DAV:", $condition, 5)) {
            return false;
        }

        return true;
    }


    /**
     * 
     *
     * @param  string  path of resource to check
     * @param  bool    exclusive lock?
     */
    function _check_lock_status($path, $exclusive_only = false) 
    {
        // FIXME depth -> ignored for now
        if (method_exists($this, "checkLock")) {
            // is locked?
            $lock = $this->checkLock($path);

            // ... and lock is not owned?
            if (is_array($lock) && count($lock)) {
                // FIXME doesn't check uri restrictions yet
                if (!isset($this->_SERVER["HTTP_IF"]) || !strstr($this->_SERVER["HTTP_IF"], $lock["token"])) {
                    if (!$exclusive_only || ($lock["scope"] !== "shared"))
                        return false;
                }
            }
        }
        return true;
    }


    // }}}


    /**
     * Generate lockdiscovery reply from checklock() result
     *
     * @param   string  resource path to check
     * @return  string  lockdiscovery response
     */
    function lockdiscovery($path) 
    {
        // no lock support without checklock() method
        if (!method_exists($this, "checklock")) {
            return "";
        }

        // collect response here
        $activelocks = "";

        // get checklock() reply
        $lock = $this->checklock($path);

        // generate <activelock> block for returned data
        if (is_array($lock) && count($lock)) {
            // check for 'timeout' or 'expires'
            if (!empty($lock["expires"])) {
                $timeout = "Second-".($lock["expires"] - time());
            } else if (!empty($lock["timeout"])) {
                $timeout = "Second-$lock[timeout]";
            } else {
                $timeout = "Infinite";
            }

            // genreate response block
            $activelocks.= "
              <D:activelock>
               <D:lockscope><D:$lock[scope]/></D:lockscope>
               <D:locktype><D:$lock[type]/></D:locktype>
               <D:depth>$lock[depth]</D:depth>
               <D:owner>$lock[owner]</D:owner>
               <D:timeout>$timeout</D:timeout>
               <D:locktoken><D:href>$lock[token]</D:href></D:locktoken>
              </D:activelock>
             ";
        }

        // return generated response
        return $activelocks;
    }

    /**
     * set HTTP return status and mirror it in a private header
     *
     * @param  string  status code and message
     * @return void
     */
    function http_status($status) 
    {
        // simplified success case
        if ($status === true) {
            $status = "200 OK";
        }

        // remember status
        $this->_http_status = $status;

        // generate HTTP status response
        header("HTTP/1.1 $status");
        header("X-WebDAV-Status: $status", true);
    }

    /**
     * private minimalistic version of PHP urlencode()
     *
     * only blanks, percent and XML special chars must be encoded here
     * full urlencode() encoding confuses some clients ...
     *
     * @param  string  URL to encode
     * @return string  encoded URL
     */
    function _urlencode($url) 
    {
        return strtr($url, array(" "=>"%20",
                                 "%"=>"%25",
                                 "&"=>"%26",
                                 "<"=>"%3C",
                                 ">"=>"%3E",
                                 ));
    }

    /**
     * private version of PHP urldecode
     *
     * not really needed but added for completenes
     *
     * @param  string  URL to decode
     * @return string  decoded URL
     */
    function _urldecode($path) 
    {
        return rawurldecode($path);
    }

    /**
     * UTF-8 encode property values if not already done so
     *
     * @param  string  text to encode
     * @return string  utf-8 encoded text
     */
    function _prop_encode($text) 
    {
        switch (strtolower($this->_prop_encoding)) {
        case "utf-8":
            return $text;
        case "iso-8859-1":
        case "iso-8859-15":
        case "latin-1":
        default:
            return utf8_encode($text);
        }
    }

    /**
     * Slashify - make sure path ends in a slash
     *
     * @param   string directory path
     * @returns string directory path wiht trailing slash
     */
    function _slashify($path) 
    {
        if ($path[strlen($path)-1] != '/') {
            $path = $path."/";
        }
        return $path;
    }

    /**
     * Unslashify - make sure path doesn't in a slash
     *
     * @param   string directory path
     * @returns string directory path wihtout trailing slash
     */
    function _unslashify($path) 
    {
        if ($path[strlen($path)-1] == '/') {
            $path = substr($path, 0, strlen($path) -1);
        }
        return $path;
    }

    /**
     * Merge two paths, make sure there is exactly one slash between them
     *
     * @param  string  parent path
     * @param  string  child path
     * @return string  merged path
     */
    function _mergePaths($parent, $child) 
    {
        if ($child{0} == '/') {
            return $this->_unslashify($parent).$child;
        } else {
            return $this->_slashify($parent).$child;
        }
    }
    
    /**
     * mbstring.func_overload save strlen version: counting the bytes not the chars
     *
     * @param string $str
     * @return int
     */
    function bytes($str)
    {
    	static $func_overload;
    	
    	if (is_null($func_overload))
    	{
    		$func_overload = @extension_loaded('mbstring') ? ini_get('mbstring.func_overload') : 0;
    	}
    	return $func_overload & 2 ? mb_strlen($str,'ascii') : strlen($str);
    }
} 
?>