server.php

很棒的在线教学系统

    {
        $args = func_get_args();
        if (count($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");