source: trunk/lib/App.inc.php @ 17

<?php
/**
 * App.inc.php
 * code by strangecode :: www.strangecode.com :: this document contains copyrighted information
 *
 * Primary application framework class.
 *
 * @author  Quinn Comendant <quinn@strangecode.com>
 * @version 1.0
 */
 
//  Message Types
define('MSG_SUCCESS', 0);
define('MSG_NOTICE', 1);
define('MSG_WARNING', 2);
define('MSG_ERR', 3); // PHP user error style.
define('MSG_ERROR', 3);

require_once dirname(__FILE__) . '/Utilities.inc.php';

class App {
    
    // Name of this application.
    var $app = '_app_';

    // If App::start has run successfully.
    var $running = false;

    // Instance of database object.
    var $db;

    // Hash of global application parameters.
    var $_params = array();

    // Default parameters.
    var $_param_defaults = array(

        // Public name and email address for this application.
        'site_name' => null,
        'site_email' => null,

        // The location the user will go if the system doesn't knew where else to send them.
        'redirect_home_url' => '/',
        
        // SSL URL used when redirecting with App::sslOn().
        'ssl_domain' => null,
        'ssl_enabled' => false,
    
        // Character set for page output. Set in the Content-Type header and an HTML <meta content-type> tag.
        'character_set' => 'utf-8',

        // Human-readable format used to display dates.
        'date_format' => 'd M Y',
        'sql_date_format' => '%e %b %Y',
        'sql_time_format' => '%k:%i',

        // Use php sessions?
        'enable_session' => false,
        'session_name' => 'Strangecode',
        'session_use_cookies' => true,
    
        // Use database?
        'enable_db' => false,

        // Use db-based sessions?
        'enable_db_session_handler' => false,
    
        // DB passwords should be set as apache environment variables in httpd.conf, readable only by root.
        'db_server' => 'localhost',
        'db_name' => null,
        'db_user' => null,
        'db_pass' => null,

        // Database debugging.
        'db_always_debug' => false, // TRUE = display all SQL queries.
        'db_debug' => false, // TRUE = display db errors.
        'db_die_on_failure' => false, // TRUE = script stops on db error.
        
        // For classes that require db tables, do we check that a table exists and create if missing?
        'db_create_tables' => null,

        // The level of error reporting. Don't set this to 0 to suppress messages, instead use display_errors to control display.
        'error_reporting' => E_ALL,

        // Don't display errors by default; it is preferable to log them to a file.
        'display_errors' => false,
    
        // Directory in which to store log files.
        'log_directory' => null,

        // PHP error log.
        'php_error_log' => 'php_error_log',

        // General application log.
        'log_filename' => 'app_error_log',

        // Logging priority can be any of the following, or false to deactivate:
        // LOG_EMERG     system is unusable
        // LOG_ALERT     action must be taken immediately
        // LOG_CRIT      critical conditions
        // LOG_ERR       error conditions
        // LOG_WARNING   warning conditions
        // LOG_NOTICE    normal, but significant, condition
        // LOG_INFO      informational message
        // LOG_DEBUG     debug-level message
        'log_file_priority' => false,
        'log_email_priority' => false,
        'log_sms_priority' => false,
        'log_screen_priority' => false,
    
        // Email address to receive log event emails.
        'log_to_email_address' => null,
        
        // SMS Email address to receive log event SMS messages
        'log_to_sms_address' => null,
    
        // A key for calculating simple cryptographic signatures. Set using as an environment variables in the httpd.conf with 'SetEnv SIGNING_KEY <key>'
        'signing_key' => 'aae6abd6209d82a691a9f96384a7634a',
    );
    
    /**
     * This method enforces the singleton pattern for this class. Only one application is running at a time.
     *
     * @return  object  Reference to the global SessionCache object.
     * @access  public
     * @static
     */
    function &getInstance($app=null)
    {
        static $instance = null;

        if ($instance === null) {
            $instance = new App($app);
        }

        return $instance;
    }
    
    /**
     * Constructor.
     */
    function App($app=null)
    {
        if (isset($app)) {
            $this->app .= $app;
        }
        
        if (!isset($_SESSION[$this->app])) {
            $_SESSION[$this->app] = array();
        }

        // Initialize default parameters.
        $this->_params = array_merge($this->_params, $this->_param_defaults);
    }

    /**
     * Set (or overwrite existing) parameters by passing an array of new parameters.
     *
     * @access public
     * @param  array    $param     Array of parameters (key => val pairs).
     */
    function setParam($param=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (isset($param) && is_array($param)) {
            // Merge new parameters with old overriding only those passed.
            $this->_params = array_merge($this->_params, $param);
        }
    }

    /**
     * Return the value of a parameter.
     *
     * @access  public
     * @param   string  $param      The key of the parameter to return.
     * @return  mixed               Parameter value, or null if not existing.
     */
    function &getParam($param=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }
        
        if ($param === null) {
            return $this->_params;
        } else if (isset($this->_params[$param])) {
            return $this->_params[$param];
        } else {
            App::logMsg(sprintf('Parameter is not set: %s', $param), LOG_DEBUG, __FILE__, __LINE__);
            return null;
        }
    }
    
    /**
     * Begin running this application.
     *
     * @access  public
     * @author  Quinn Comendant <quinn@strangecode.com>
     * @since   15 Jul 2005 00:32:21
     */
    function start()
    {
        if ($this->running) {
            return false;
        }
        
        // Error reporting.
        ini_set('error_reporting', $this->getParam('error_reporting'));
        ini_set('display_errors', $this->getParam('display_errors'));
        ini_set('log_errors', true);
        if (is_dir($this->getParam('log_directory')) && is_writable($this->getParam('log_directory'))) {
            ini_set('error_log', $this->getParam('log_directory') . '/' . $this->getParam('php_error_log'));
        }
        
        
        /**
         * 1. Start Database.
         */
        
        if ($this->getParam('enable_db')) {
        
            // DB connection parameters taken from environment variables in the httpd.conf file, readable only by root.
            if (!empty($_SERVER['DB_SERVER'])) {
                $this->setParam(array('db_server' => $_SERVER['DB_SERVER']));
            }
            if (!empty($_SERVER['DB_NAME'])) {
                $this->setParam(array('db_name' => $_SERVER['DB_NAME']));
            }
            if (!empty($_SERVER['DB_USER'])) {
                $this->setParam(array('db_user' => $_SERVER['DB_USER']));
            }
            if (!empty($_SERVER['DB_PASS'])) {
                $this->setParam(array('db_pass' => $_SERVER['DB_PASS']));
            }
            
            // The only instance of the DB object.
            require_once dirname(__FILE__) . '/DB.inc.php';
            
            $this->db =& DB::getInstance();
            
            $this->db->setParam(array(
                'db_server' => $this->getParam('db_server'),
                'db_name' => $this->getParam('db_name'),
                'db_user' => $this->getParam('db_user'),
                'db_pass' => $this->getParam('db_pass'),
                'db_always_debug' => $this->getParam('db_always_debug'),
                'db_debug' => $this->getParam('db_debug'),
                'db_die_on_failure' => $this->getParam('db_die_on_failure'),
            ));

            // Connect to database.
            $this->db->connect();
        }
        
        
        /**
         * 2. Start PHP session.
         */
    
        // Skip session for some user agents.
        if (preg_match('/Atomz|ApacheBench|Wget/i', getenv('HTTP_USER_AGENT'))) {
            $this->setParam(array('enable_session' => false));
        }
        
        if (true === $this->getParam('enable_session')) {
        
            // Set the session ID to one provided in GET/POST. This is necessary for linking
            // between domains and keeping the same session.
            if ($ses = getFormData($this->getParam('session_name'), false)) {
                session_id($ses);
            }
        
            if (true === $this->getParam('enable_db_session_handler') && true === $this->getParam('enable_db')) {
                // Database session handling.
                require_once dirname(__FILE__) . '/DBSessionHandler.inc.php';
                $db_save_handler = new DBSessionHandler($this->db, array(
                    'db_table' => 'session_tbl',
                    'create_table' => $this->getParam('db_create_tables'),
                ));
            }
            
            // Session parameters.
            ini_set('session.use_cookies', $this->getParam('session_use_cookies'));
            ini_set('session.use_trans_sid', false);
            ini_set('session.entropy_file', '/dev/urandom');
            ini_set('session.entropy_length', '512');
            session_name($this->getParam('session_name'));
            
            // Start the session. Access session data using: $_SESSION['...']
            session_start();
        }
        
        
        /**
         * 3. Misc setup.
         */

        // Script URI will be something like http://host.name.tld (no ending slash)
        // and is used whenever a URL need be used to the current site.
        // Not available on cli scripts obviously.
        if (isset($_SERVER['HTTP_HOST']) && '' != $_SERVER['HTTP_HOST']) {
            $this->setParam(array('site_url' => sprintf('%s://%s', ('on' == getenv('HTTPS') ? 'https' : 'http'), getenv('HTTP_HOST'))));
        }

        // A key for calculating simple cryptographic signatures.
        if (isset($_SERVER['SIGNING_KEY'])) {
            $this->setParam(array('signing_key' => $_SERVER['SIGNING_KEY']));
        }
        
        // Used as the fifth parameter to mail() to set the return address for sent messages. Requires safe_mode off.
        if ('' != $this->getParam('site_email') && !$this->getParam('envelope_sender_address')) {
            $this->setParam(array('envelope_sender_address' => '-f ' . $this->getParam('site_email')));
        }

        // Character set. This should also be printed in the html header template.
        header('Content-type: text/html; charset=' . $this->getParam('character_set'));
        
        $this->running = true;
    }
    
    /**
     * Stop running this application.
     *
     * @access  public
     * @author  Quinn Comendant <quinn@strangecode.com>
     * @since   17 Jul 2005 17:20:18
     */
    function stop()
    {
        session_write_close();
        $this->db->close();
        restore_include_path();
        $this->running = false;
    }
    
    
    /**
     * Add a message to the string globalmessage, which is printed in the header.
     * Just a simple way to print messages to the user.
     *
     * @access public
     *
     * @param string $message The text description of the message.
     * @param int    $type    The type of message: MSG_NOTICE,
     *                        MSG_SUCCESS, MSG_WARNING, or MSG_ERR.
     * @param string $file    __FILE__.
     * @param string $line    __LINE__.
     */
    function raiseMsg($message, $type=MSG_NOTICE, $file=null, $line=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        $_SESSION[$this->app]['messages'][] = array(
            'type'    => $type, 
            'message' => $message,
            'file'    => $file,
            'line'    => $line
        );
        
        if (!in_array($type, array(MSG_NOTICE, MSG_SUCCESS, MSG_WARNING, MSG_ERR))) {
            App::logMsg(sprintf('Invalid MSG_* type: %s', $type), LOG_DEBUG, __FILE__, __LINE__);
        }
    }
    
    /**
     * Prints the HTML for displaying raised messages.
     *
     * @access  public
     * @author  Quinn Comendant <quinn@strangecode.com>
     * @since   15 Jul 2005 01:39:14
     */
    function printRaisedMessages()
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }

        while (isset($_SESSION[$this->app]['messages']) && $message = array_shift($_SESSION[$this->app]['messages'])) {
            ?><div class="codebasemsg"><?php
            if (error_reporting() > 0 && $this->getParam('display_errors')) {
                echo "\n<!-- [" . $message['file'] . ' : ' . $message['line'] . '] -->';
            }
            switch ($message['type']) {
            case MSG_ERR:
                echo '<div class="error">' . $message['message'] . '</div>';
                break;
    
            case MSG_WARNING:
                echo '<div class="warning">' . $message['message'] . '</div>';
                break;
    
            case MSG_SUCCESS:
                echo '<div class="success">' . $message['message'] . '</div>';
                break;
    
            case MSG_NOTICE:
            default:
                echo '<div class="notice">' . $message['message'] . '</div>';
                break;
    
            }
            ?></div><?php
        }
    }
    
    /**
     * Logs a message to a user defined log file. Additional actions to take for
     * different types of message types can be specified (ERROR, NOTICE, etc).
     *
     * @access public
     *
     * @param string $message   The text description of the message.
     * @param int    $priority  The type of message priority (in descending order):
     *                          LOG_EMERG     system is unusable
     *                          LOG_ALERT     action must be taken immediately
     *                          LOG_CRIT      critical conditions
     *                          LOG_ERR       error conditions
     *                          LOG_WARNING   warning conditions
     *                          LOG_NOTICE    normal, but significant, condition
     *                          LOG_INFO      informational message
     *                          LOG_DEBUG     debug-level message
     * @param string $file      The file where the log event occurs.
     * @param string $line      The line of the file where the log event occurs.
     */
    function logMsg($message, $priority=LOG_INFO, $file=null, $line=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }
        
        // If priority is not specified, assume the worst.
        if (!$this->logPriorityToString($priority)) {
            $this->logMsg(sprintf('Log priority %s not defined. (Message: %s)', $priority, $message), LOG_EMERG, $file, $line);
            $priority = LOG_EMERG;
        }
    
        // If log file is not specified, don't log to a file.
        if (!$this->getParam('log_directory') || !$this->getParam('log_filename') || !is_dir($this->getParam('log_directory')) || !is_writable($this->getParam('log_directory'))) {
            $this->setParam(array('log_file_priority' => false));
            // We must use trigger_error to report this problem rather than calling App::logMsg, which might lead to an infinite loop.
            trigger_error(sprintf('Codebase error: log directory (%s) not found or writable.', $this->getParam('log_directory')), E_USER_NOTICE);
        }
        
        // Make sure to log in the system's locale.
        $locale = setlocale(LC_TIME, 0);
        setlocale(LC_TIME, 'C');
        
        // Data to be stored for a log event.
        $event = array();
        $event['date'] = date('Y-m-d H:i:s');
        $event['remote ip'] = getRemoteAddr();
        if (substr(PHP_OS, 0, 3) != 'WIN') {
            $event['pid'] = posix_getpid();
        }
        $event['type'] = $this->logPriorityToString($priority);
        $event['file:line'] = "$file : $line";
        $event['message'] = strip_tags(preg_replace('/\s{2,}/', ' ', $message));
    
        $event_str = '[' . join('] [', $event) . ']';
        
        // FILE ACTION
        if ($this->getParam('log_file_priority') && $priority <= $this->getParam('log_file_priority')) {
            error_log($event_str . "\n", 3, $this->getParam('log_directory') . '/' . $this->getParam('log_filename'));
        }
    
        // EMAIL ACTION
        if ($this->getParam('log_email_priority') && $priority <= $this->getParam('log_email_priority')) {
            $subject = sprintf('[%s %s] %s', getenv('HTTP_HOST'), $event['type'], $message);
            $email_msg = sprintf("A %s log event occured on %s\n\n", $event['type'], getenv('HTTP_HOST'));
            $headers = "From: codebase@strangecode.com\r\n";
            foreach ($event as $k=>$v) {
                $email_msg .= sprintf("%-11s%s\n", $k, $v);
            }
            mail($this->getParam('log_to_email_address'), $subject, $email_msg, $headers, '-f codebase@strangecode.com');
        }
        
        // SMS ACTION
        if ($this->getParam('log_sms_priority') && $priority <= $this->getParam('log_sms_priority')) {
            $subject = sprintf('[%s %s]', getenv('HTTP_HOST'), $priority);
            $sms_msg = sprintf('%s:%s %s', basename($file), $line, $event['message']);
            $headers = "From: codebase@strangecode.com\r\n";
            mail($this->getParam('log_to_sms_address'), $subject, $sms_msg, $headers, '-f codebase@strangecode.com');
        }
    
        // SCREEN ACTION
        if ($this->getParam('log_screen_priority') && $priority <= $this->getParam('log_screen_priority')) {
            echo "[{$event['date']}] [{$event['type']}] [{$event['file:line']}] [{$event['message']}]\n";
        }
    
        // Restore original locale.
        setlocale(LC_TIME, $locale);
    }
    
    /**
     * Returns the string representation of a LOG_* integer constant.
     *
     * @param int  $priority  The LOG_* integer constant.
     *
     * @return                The string representation of $priority.
     */
    function logPriorityToString ($priority) {
        $priorities = array(
            LOG_EMERG   => 'emergency',
            LOG_ALERT   => 'alert',
            LOG_CRIT    => 'critical',
            LOG_ERR     => 'error',
            LOG_WARNING => 'warning',
            LOG_NOTICE  => 'notice',
            LOG_INFO    => 'info',
            LOG_DEBUG   => 'debug'
        );
        if (isset($priorities[$priority])) {
            return $priorities[$priority];
        } else {
            return false;
        }
    }
    
    /**
     * Outputs a fully qualified URL with a query of all the used (ie: not empty)
     * keys and values, including optional queries. This allows simple printing of
     * links without needing to know which queries to add to it. If cookies are not
     * used, the session id will be propogated in the URL.
     *
     * @global string $carry_queries       An array of keys to define which values to
     *                                     carry through from the POST or GET.
     *                                     $carry_queries = array('qry'); for example.
     *
     * @param  string $url                 The initial url
     * @param  mixed  $carry_args          Additional url arguments to carry in the query,
     *                                     or FALSE to prevent carrying queries. Can be any of the following formats:
     *                                     -array('key1', key2', key3')  <-- to save these keys if in the form data.
     *                                     -array('key1'=>'value', key2'='value')  <-- to set keys to default values if not present in form data.
     *                                     -false  <-- To not carry any queries. If URL already has queries those will be retained.
     *
     * @param  mixed  $always_include_sid  Always add the session id, even if using_trans_sid = true. This is required when
     *                                     URL starts with http, since PHP using_trans_sid doesn't do those and also for
     *                                     header('Location...') redirections.
     *
     * @return string url with attached queries and, if not using cookies, the session id
     */
    function oHREF($url='', $carry_args=null, $always_include_sid=false)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        static $_using_trans_sid;
        global $carry_queries;
    
        // Save the trans_sid setting.
        if (!isset($_using_trans_sid)) {
            $_using_trans_sid = ini_get('session.use_trans_sid');
        }
    
        // Initialize the carried queries.
        if (!isset($carry_queries['_carry_queries_init'])) {
            if (!is_array($carry_queries)) {
                $carry_queries = array($carry_queries);
            }
            $tmp = $carry_queries;
            $carry_queries = array();
            foreach ($tmp as $key) {
                if (!empty($key) && getFormData($key, false)) {
                    $carry_queries[$key] = getFormData($key);
                }
            }
            $carry_queries['_carry_queries_init'] = true;
        }
    
        // Get any additional query arguments to add to the $carry_queries array.
        // If FALSE is a function argument, DO NOT carry the queries.
        $do_carry_queries = true;
        $one_time_carry_queries = array();
        if (!is_null($carry_args)) {
            if (is_array($carry_args) && !empty($carry_args)) {
                foreach ($carry_args as $key=>$arg) {
                    // Get query from appropriate source.
                    if (false === $arg) {
                        $do_carry_queries = false;
                    } else if (false !== getFormData($arg, false)) {
                        $one_time_carry_queries[$arg] = getFormData($arg); // Set arg to form data if available.
                    } else if (!is_numeric($key) && '' != $arg) {
                        $one_time_carry_queries[$key] = getFormData($key, $arg); // Set to arg to default if specified (overwritten by form data).
                    }
                }
            } else if (false !== getFormData($carry_args, false)) {
                $one_time_carry_queries[$carry_args] = getFormData($carry_args);
            } else if (false === $carry_args) {
                $do_carry_queries = false;
            }
        }
    
        // Get the first delimiter that is needed in the url.
        $delim = preg_match('/\?/', $url) ? ini_get('arg_separator.output') : '?';
        
        $q = '';
        if ($do_carry_queries) {
            // Join the perm and temp carry_queries and filter out the _carry_queries_init element for the final query args.
            $query_args = array_diff_assoc(urlEncodeArray(array_merge($carry_queries, $one_time_carry_queries)), array('_carry_queries_init' => true));
            foreach ($query_args as $key=>$val) {
                // Check value is set and value does not already exist in the url.
                if (!preg_match('/[?&]' . preg_quote($key) . '=/', $url)) {
                    $q .= $delim . $key . '=' . $val;
                    $delim = ini_get('arg_separator.output');
                }
            }
        }
    
        // Include the necessary SID if the following is true:
        // - no cookie in http request OR cookies disabled in App
        // - sessions are enabled
        // - the link stays on our site
        // - transparent SID propogation with session.use_trans_sid is not being used OR url begins with protocol (using_trans_sid has no effect here)
        // OR 
        // - we must include the SID because we say so (it's used in a context where cookies will not be effective, ie. moving from http to https)
        // AND
        // - the SID is not already in the query.
        if (
            (
                (
                    (
                        !isset($_COOKIE[session_name()]) 
                        || !$this->getParam('session_use_cookies')
                    ) 
                    && $this->getParam('enable_session')
                    && isMyDomain($url) 
                    && 
                    (
                        !$_using_trans_sid
                        || preg_match('!^(http|https)://!i', $url)
                    )
                ) 
                || $always_include_sid
            )
            && !preg_match('/[?&]' . preg_quote(session_name()) . '=/', $url)
        ) {
            $url .= $q . $delim . session_name() . '=' . session_id();
            return $url;
        } else {
            $url .= $q;
            return $url;
        }
    }
    
    /**
     * Prints a hidden form element with the PHPSESSID when cookies are not used, as well
     * as hidden form elements for GET_VARS that might be in use. 
     *
     * @global string $carry_queries     An array of keys to define which values to
     *                                   carry through from the POST or GET.
     *                                   $carry_queries = array('qry'); for example
     *
     * @param  mixed  $carry_args        Additional url arguments to carry in the query,
     *                                   or FALSE to prevent carrying queries. Can be any of the following formats:
     *                                   -array('key1', key2', key3')  <-- to save these keys if in the form data.
     *                                   -array('key1'=>'value', key2'='value')  <-- to set keys to default values if not present in form data.
     *                                   -false  <-- To not carry any queries. If URL already has queries those will be retained.
     */
    function printHiddenSession($carry_args=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        static $_using_trans_sid;
        global $carry_queries;
    
        // Save the trans_sid setting.
        if (!isset($_using_trans_sid)) {
            $_using_trans_sid = ini_get('session.use_trans_sid');
        }
        
        // Initialize the carried queries.
        if (!isset($carry_queries['_carry_queries_init'])) {
            if (!is_array($carry_queries)) {
                $carry_queries = array($carry_queries);
            }
            $tmp = $carry_queries;
            $carry_queries = array();
            foreach ($tmp as $key) {
                if (!empty($key) && getFormData($key, false)) {
                    $carry_queries[$key] = getFormData($key);
                }
            }
            $carry_queries['_carry_queries_init'] = true;
        }
    
        // Get any additional query names to add to the $carry_queries array 
        // that are found as function arguments.
        // If FALSE is a function argument, DO NOT carry the queries.
        $do_carry_queries = true;
        $one_time_carry_queries = array();
        if (!is_null($carry_args)) {
            if (is_array($carry_args) && !empty($carry_args)) {
                foreach ($carry_args as $key=>$arg) {
                    // Get query from appropriate source.
                    if (false === $arg) {
                        $do_carry_queries = false;
                    } else if (false !== getFormData($arg, false)) {
                        $one_time_carry_queries[$arg] = getFormData($arg); // Set arg to form data if available.
                    } else if (!is_numeric($key) && '' != $arg) {
                        $one_time_carry_queries[$key] = getFormData($key, $arg); // Set to arg to default if specified (overwritten by form data).
                    }
                }
            } else if (false !== getFormData($carry_args, false)) {
                $one_time_carry_queries[$carry_args] = getFormData($carry_args);
            } else if (false === $carry_args) {
                $do_carry_queries = false;
            }
        }
        
        // For each existing POST value, we create a hidden input to carry it through a form.
        if ($do_carry_queries) {
            // Join the perm and temp carry_queries and filter out the _carry_queries_init element for the final query args.
            $query_args = array_diff_assoc(urlEncodeArray(array_merge($carry_queries, $one_time_carry_queries)), array('_carry_queries_init' => true));
            foreach ($query_args as $key=>$val) {
                echo '<input type="hidden" name="' . $key . '" value="' . $val . '" />';
            }
        }
        
        // Include the SID if cookies are disabled.
        if (!isset($_COOKIE[session_name()]) && !$_using_trans_sid) {
            echo '<input type="hidden" name="' . session_name() . '" value="' . session_id() . '" />';
        }
    }
    
    /**
     * Uses an http header to redirect the client to the given $url. If sessions are not used
     * and the session is not already defined in the given $url, the SID is appended as a URI query.
     * As with all header generating functions, make sure this is called before any other output.
     *
     * @param   string  $url                    The URL the client will be redirected to.
     * @param   mixed   $carry_args             Additional url arguments to carry in the query,
     *                                          or FALSE to prevent carrying queries. Can be any of the following formats:
     *                                          -array('key1', key2', key3')  <-- to save these keys if in the form data.
     *                                          -array('key1'=>'value', key2'='value')  <-- to set keys to default values if not present in form data.
     *                                          -false  <-- To not carry any queries. If URL already has queries those will be retained.
     * @param   bool    $always_include_sid     Force session id to be added to Location header.
     */
    function dieURL($url, $carry_args=null, $always_include_sid=false)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        if ('' == $url) {
            // If URL is not specified, use the redirect_home_url.
            $url = $this->getParam('redirect_home_url');
        }
    
        if (preg_match('!^/!', $url)) {
            // If relative URL is given, prepend correct local hostname.
            $my_url = parse_url($_SERVER['SCRIPT_URI']);
            $url = sprintf('%s://%s%s', $my_url['scheme'], $my_url['host'], $url);
        }
    
        $url = $this->oHREF($url, $carry_args, $always_include_sid);
        
        header(sprintf('Location: %s', $url));
        $this->logMsg(sprintf('dieURL: %s', $url), LOG_DEBUG, __FILE__, __LINE__);
        
        // End this application.
        // Recommended, although I'm not sure it's necessary: http://cn2.php.net/session_write_close
        $this->stop();
        die;
    }
    
    /**
     * Redirects a user by calling the App::dieURL(). It will use:
     * 1. the stored boomerang URL, it it exists
     * 2. the referring URL, it it exists.
     * 3. an empty string, which will force App::dieURL to use the default URL.
     */
    function dieBoomerangURL($id=null, $carry_args=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        // Get URL from stored boomerang. Allow non specific URL if ID not valid.
        if ($this->validBoomerangURL($id, true)) {
            if (isset($id) && isset($_SESSION[$this->app]['boomerang']['url'][$id])) {
                $url = $_SESSION[$this->app]['boomerang']['url'][$id];
            } else {
                $url = end($_SESSION[$this->app]['boomerang']['url']);
            }
        } else if (!refererIsMe() && !preg_match('/admin_common/', getenv('SCRIPT_NAME'))) {
            // Ensure that the redirecting page is not also the referrer.
            // admin_common is an alias of 'admin', which confuses this function. Just here for local testing.
            $url = getenv('HTTP_REFERER');
        } else {
            $url = '';
        }
    
        $this->logMsg(sprintf('dieBoomerangURL: %s', $url), LOG_DEBUG, __FILE__, __LINE__);
    
        // Delete stored boomerang.
        $this->deleteBoomerangURL($id);
            
        // A redirection will never happen immediatly twice.
        // Set the time so ensure this doesn't happen.
        $_SESSION[$this->app]['boomerang']['time'] = time();
        $this->dieURL($url, $carry_args);
    }
    
    /**
     * Set the URL to return to when App::dieBoomerangURL() is called.
     *
     * @param string  $url  A fully validated URL.
     * @param bool  $id     An identification tag for this url.
     * FIXME: url garbage collection?
     */
    function setBoomerangURL($url=null, $id=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        // A redirection will never happen immediatly after setting the boomerangURL.
        // Set the time so ensure this doesn't happen. See App::validBoomerangURL for more.
    
        if (isset($url) && is_string($url)) {
            // Delete any boomerang request keys in the query string.
            $url = preg_replace('/boomerang=[\w]+/', '', $url);
            
            if (is_array($_SESSION[$this->app]['boomerang']['url']) && !empty($_SESSION[$this->app]['boomerang']['url'])) {
                // If the URL currently exists in the boomerang array, delete.
                while ($existing_key = array_search($url, $_SESSION[$this->app]['boomerang']['url'])) {
                    unset($_SESSION[$this->app]['boomerang']['url'][$existing_key]);
                }
            }
            
            if (isset($id)) {
                $_SESSION[$this->app]['boomerang']['url'][$id] = $url;
            } else {
                $_SESSION[$this->app]['boomerang']['url'][] = $url;
            }
            $this->logMsg(sprintf('setBoomerangURL: %s', $url), LOG_DEBUG, __FILE__, __LINE__);
            return true;
        } else {
            return false;
        }
    }
    
    /**
     * Return the URL set for the specified $id.
     *
     * @param string  $id     An identification tag for this url.
     */
    function getBoomerangURL($id=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        if (isset($id)) {
            if (isset($_SESSION[$this->app]['boomerang']['url'][$id])) {
                return $_SESSION[$this->app]['boomerang']['url'][$id];
            } else {
                return '';
            }
        } else if (is_array($_SESSION[$this->app]['boomerang']['url'])) {
            return end($_SESSION[$this->app]['boomerang']['url']);
        } else {
            return false;
        }
    }
    
    /**
     * Delete the URL set for the specified $id.
     *
     * @param string  $id     An identification tag for this url.
     */
    function deleteBoomerangURL($id=null)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        if (isset($id) && isset($_SESSION[$this->app]['boomerang']['url'][$id])) {
            unset($_SESSION[$this->app]['boomerang']['url'][$id]);
        } else if (is_array($_SESSION[$this->app]['boomerang']['url'])) {
            array_pop($_SESSION[$this->app]['boomerang']['url']);
        }
    }
    
    /**
     * Check if a valid boomerang URL value has been set.
     * if it is not the current url, and has not been accessed within n seconds.
     *
     * @return bool  True if it is set and not the current URL.
     */
    function validBoomerangURL($id=null, $use_nonspecificboomerang=false)
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }

        if (!$this->running) {
            return false;
        }
        
        if (!isset($_SESSION[$this->app]['boomerang']['url'])) {
            return false;
        }
    
        // Time is the timestamp of a boomerangURL redirection, or setting of a boomerangURL.
        // a boomerang redirection will always occur at least several seconds after the last boomerang redirect
        // or a boomerang being set.
        $boomerang_time = isset($_SESSION[$this->app]['boomerang']['time']) ? $_SESSION[$this->app]['boomerang']['time'] : 0;
        
        if (isset($id) && isset($_SESSION[$this->app]['boomerang']['url'][$id])) {
            $url = $_SESSION[$this->app]['boomerang']['url'][$id];
        } else if (!isset($id) || $use_nonspecificboomerang) {
            // Use non specific boomerang if available.
            $url = end($_SESSION[$this->app]['boomerang']['url']);
        }
    
        $this->logMsg(sprintf('validBoomerangURL testing url: %s', $url), LOG_DEBUG, __FILE__, __LINE__);
        if (empty($url)) {
            return false;
        }
        if ($url == absoluteMe()) {
            // The URL we are directing to is the current page.
            $this->logMsg(sprintf('Boomerang URL not valid, same as absoluteMe: %s', $url), LOG_WARNING, __FILE__, __LINE__);
            return false;
        }
        if ($boomerang_time >= (time() - 2)) {
            // Last boomerang direction was more than 2 seconds ago.
            $this->logMsg(sprintf('Boomerang URL not valid, boomerang_time too short: %s', time() - $boomerang_time), LOG_WARNING, __FILE__, __LINE__);
            return false;
        }
        
        $this->logMsg(sprintf('validBoomerangURL found: %s', $url), LOG_DEBUG, __FILE__, __LINE__);
        return true;
    }

    /**
     * Force the user to connect via https (port 443) by redirecting them to
     * the same page but with https.
     */
    function sslOn()
    {
        if (!isset($this) || !is_a($this, 'App')) {
            $this =& App::getInstance();
        }
        
        if ('on' != getenv('HTTPS') && $this->getParam('ssl_enabled') && preg_match('/mod_ssl/i', getenv('SERVER_SOFTWARE'))) {
            $this->raiseMsg(sprintf(_("Secure SSL connection made to %s"), $this->getParam('ssl_domain')), MSG_NOTICE, __FILE__, __LINE__);
            // Always append session because some browsers do not send cookie when crossing to SSL URL.
            $this->dieURL('https://' . $this->getParam('ssl_domain') . getenv('REQUEST_URI'), null, true);
        }
    }
        
    
    /**
     * to enforce the user to connect via http (port 80) by redirecting them to
     * a http version of the current url.
     */
    function sslOff()
    {
        if ('on' == getenv('HTTPS')) {
            $this->dieURL('http://' . getenv('HTTP_HOST') . getenv('REQUEST_URI'), null, true);
        }
    }

    
} // End.

?>