CKSource

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";

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");

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';