Revision as of 20:43, 17 May 2010

CKFinder functionality can be extended with server side plugins. Althought the full source code of CKFinder server connector is available and it can be changed in any way, a much better way of enhancing CKFinder connector is to create a plugin.

The main advantages of plugins are:

• Upgrades are much easier.
• The plugin code is in a single place.
• Plugins can be easily turned off when are not needed anymore.

Common use cases:

• Adding new server side command (i.e. fileditor and imageresize plugin).
• Working with uploaded file (i.e. watermark plugin).
• Extending the information returned by the Init command (i.e. imageresize plugin).

Creating a plugin

Step1: Create plugin folder

Create a directory for your plugin inside of the "plugins" directory (by default CKFinder comes with three plugins: dummy, fileeditor, imagreresize). Let's use "myplugin" as the plugin name and use the same name for our new folder.

Step2: Create plugin file

Inside of your plugin's folder ("myplugin") create an empty file named plugin.php.

Step3: Add plugin definition

// Let's create an empty PHP file for now

Step4: Enable plugin

Add an include_once/require_once statement in the PHP configuration file (config.php):

include_once "plugins/myplugin/plugin.php";

PHP plugin system

Hooks

CKFinder provides several hooks that can be used to extend the functionality of the CKFinder application. Assigning a function (also known as an event handler) to a hook will cause that function to be called at the appropriate point in the main CKFinder code, to perform whatever additional task(s) the developer thinks would be useful at that point. Each hook can have multiple handlers assigned to it, in which case it will call the functions in the order that they are assigned.

Hooks should be assigned in a plugin file. The easiest way to assign a function to a hook is:

$config['Hooks']['event'][] = 'function';

However, usually you'll provide a class instance and a method name.

// Resulting function call: $object->someMethod($param1, $param2);
$config['Hooks']['event'][] = array($object, 'someMethod');

Available hooks

Adding new server side command

Let's write a plugin that adds a new server side command to the connector.

For the sake of simplicity, we'll first create a simple plugin.php that just does exactly what we need:

<?php

// (2) Include base XML command handler
require_once CKFINDER_CONNECTOR_LIB_DIR . "/CommandHandler/XmlCommandHandlerBase.php";

// Since we will send a XML response, we'll extend the XmlCommandHandlerBase
class CKFinder_Connector_CommandHandler_FileSize extends CKFinder_Connector_CommandHandler_XmlCommandHandlerBase
{
    // (4) The buildXml method is used to construct an XML response
    function buildXml()
    {
        $fileName = $_GET["fileName"];
        $filePath = CKFinder_Connector_Utils_FileSystem::combinePaths($this->_currentFolder->getServerPath(), $fileName);

        // (5) Adding a <FileSize> element to the XML response.
        $oNode = new Ckfinder_Connector_Utils_XmlNode("FileSize");
        $oNode->addAttribute("size", filesize($filePath));
        $this->_connectorNode->addChild($oNode);
    }

    // (3) Register the "FileSize" command
    function onBeforeExecuteCommand( &$command )
    {
        if ( $command == 'FileSize' )
        {
            // The sendResponse method is defined in XmlCommandHandlerBase, it creates 
            // a basic XML response and calls the buildXml()method 
            $this->sendResponse();
            // false = stop further execution.
            return false;
        }

        return true ;
    }
}

$CommandHandler_FileSize = new CKFinder_Connector_CommandHandler_FileSize();
// (1) Register the onBeforeExecuteCommand method to be called by the BeforeExecuteCommand hook.
$config['Hooks']['BeforeExecuteCommand'][] = array($CommandHandler_FileSize, "onBeforeExecuteCommand");

Step1: Create plugin folder

The full source code of a plugin with all necessary security checks:

<?php

// A simple protection against calling this file directly.
if (!defined('IN_CKFINDER')) exit;

// Include base XML command handler
require_once CKFINDER_CONNECTOR_LIB_DIR . "/CommandHandler/XmlCommandHandlerBase.php";

// Since we will send a XML response, we'll reuse the XmlCommandHandler
class CKFinder_Connector_CommandHandler_FileSize extends CKFinder_Connector_CommandHandler_XmlCommandHandlerBase
{
    // The buildXml method is used to construct an XML response
    function buildXml()
    {
        // A "must have", checking whether the connector is enabled and the basic parameters (like current folder) are safe.
        $this->checkConnector();
        $this->checkRequest();

        // Checking ACL permissions, we're just getting an information about a file, so FILE_VIEW permission seems to be ok.
        if (!$this->_currentFolder->checkAcl(CKFINDER_CONNECTOR_ACL_FILE_VIEW)) {
            $this->_errorHandler->throwError(CKFINDER_CONNECTOR_ERROR_UNAUTHORIZED);
        }

        // Make sure we actually received a file name
        if (!isset($_GET["fileName"])) {
            $this->_errorHandler->throwError(CKFINDER_CONNECTOR_ERROR_INVALID_NAME);
        }

        $fileName = CKFinder_Connector_Utils_FileSystem::convertToFilesystemEncoding($_GET["fileName"]);
        $resourceTypeInfo = $this->_currentFolder->getResourceTypeConfig();

        // Use the resource type configuration object to check whether the extension of a file to check is really allowed.
        if (!$resourceTypeInfo->checkExtension($fileName)) {
            $this->_errorHandler->throwError(CKFINDER_CONNECTOR_ERROR_INVALID_EXTENSION);
        }

        // Make sure that the file name is really ok and has not been sent by a hacker
        if (!CKFinder_Connector_Utils_FileSystem::checkFileName($fileName) || $resourceTypeInfo->checkIsHiddenFile($fileName)) {
            $this->_errorHandler->throwError(CKFINDER_CONNECTOR_ERROR_INVALID_REQUEST);
        }

        $filePath = CKFinder_Connector_Utils_FileSystem::combinePaths($this->_currentFolder->getServerPath(), $fileName);

        if (!file_exists($filePath) || !is_file($filePath)) {
            $this->_errorHandler->throwError(CKFINDER_CONNECTOR_ERROR_FILE_NOT_FOUND);
        }

        $size = filesize($filePath);

        // *** The main part of this plugin ****
        // Adding a <FileSize> element to the XML response.
        $oNode = new Ckfinder_Connector_Utils_XmlNode("FileSize");
        $oNode->addAttribute("size", $size);
        $this->_connectorNode->addChild($oNode);
    }

    // Register the "FileSize" command
    function onBeforeExecuteCommand( &$command )
    {
        if ( $command == 'FileSize' )
        {
            // The sendResponse method is defined in XmlCommandHandlerBase, it creates 
            // a basic XML response and calls the buildXml()method 
            $this->sendResponse();
            // false = stop further execution.
            return false;
        }

        return true ;
    }
}

$CommandHandler_FileSize = new CKFinder_Connector_CommandHandler_FileSize();
// Register the onBeforeExecuteCommand method to be called by the BeforeExecuteCommand hook.
$config['Hooks']['BeforeExecuteCommand'][] = array($CommandHandler_FileSize, "onBeforeExecuteCommand");
// (Optional) Register a javascript plugin named "dummy"
$config['Plugins'][] = 'dummy';