nextcloud/apps/files_encryption/lib/proxy.php

<?php

/**
* ownCloud
*
* @author Robin Appelman
* @copyright 2011 Robin Appelman icewind1991@gmail.com
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
* License as published by the Free Software Foundation; either
* version 3 of the License, or any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU AFFERO GENERAL PUBLIC LICENSE for more details.
*
* You should have received a copy of the GNU Affero General Public
* License along with this library.  If not, see <http://www.gnu.org/licenses/>.
*
*/

/**
 * transparent encryption
 */

class OC_FileProxy_Encryption extends OC_FileProxy{
	private static $blackList=null; //mimetypes blacklisted from encryption
	private static $enableEncryption=null;

	/**
	 * check if a file should be encrypted during write
	 * @param string $path
	 * @return bool
	 */
	private static function shouldEncrypt($path) {
		if(is_null(self::$enableEncryption)) {
			self::$enableEncryption=(OCP\Config::getAppValue('files_encryption','enable_encryption','true')=='true');
		}
		if(!self::$enableEncryption) {
			return false;
		}
		if(is_null(self::$blackList)) {
			self::$blackList=explode(',',OCP\Config::getAppValue('files_encryption','type_blacklist','jpg,png,jpeg,avi,mpg,mpeg,mkv,mp3,oga,ogv,ogg'));
		}
		if(self::isEncrypted($path)) {
			return true;
		}
		$extension=substr($path,strrpos($path,'.')+1);
		if(array_search($extension,self::$blackList)===false) {
			return true;
		}
	}

	/**
	 * check if a file is encrypted
	 * @param string $path
	 * @return bool
	 */
	private static function isEncrypted($path) {
		$metadata=OC_FileCache_Cached::get($path,'');
		return isset($metadata['encrypted']) and (bool)$metadata['encrypted'];
	}

	public function preFile_put_contents($path,&$data) {
		if(self::shouldEncrypt($path)) {
			if (!is_resource($data)) {//stream put contents should have been converter to fopen
				$size=strlen($data);
				$data=OC_Crypt::blockEncrypt($data);
				OC_FileCache::put($path,array('encrypted'=>true,'size'=>$size),'');
			}
		}
	}

	public function postFile_get_contents($path,$data) {
		if(self::isEncrypted($path)) {
			$cached=OC_FileCache_Cached::get($path,'');
			$data=OC_Crypt::blockDecrypt($data,'',$cached['size']);
		}
		return $data;
	}

	public function postFopen($path,&$result) {
		if(!$result) {
			return $result;
		}
		$meta=stream_get_meta_data($result);
		if(self::isEncrypted($path)) {
			fclose($result);
			$result=fopen('crypt://'.$path,$meta['mode']);
		}elseif(self::shouldEncrypt($path) and $meta['mode']!='r' and $meta['mode']!='rb') {
			if(OC_Filesystem::file_exists($path) and OC_Filesystem::filesize($path)>0) {
				//first encrypt the target file so we don't end up with a half encrypted file
				OCP\Util::writeLog('files_encryption','Decrypting '.$path.' before writing',OCP\Util::DEBUG);
				$tmp=fopen('php://temp');
				OCP\Files::streamCopy($result,$tmp);
				fclose($result);
				OC_Filesystem::file_put_contents($path,$tmp);
				fclose($tmp);
			}
			$result=fopen('crypt://'.$path,$meta['mode']);
		}
		return $result;
	}

	public function postGetMimeType($path,$mime) {
		if(self::isEncrypted($path)) {
			$mime=OCP\Files::getMimeType('crypt://'.$path,'w');
		}
		return $mime;
	}

	public function postStat($path,$data) {
		if(self::isEncrypted($path)) {
			$cached=OC_FileCache_Cached::get($path,'');
			$data['size']=$cached['size'];
		}
		return $data;
	}

	public function postFileSize($path,$size) {
		if(self::isEncrypted($path)) {
			$cached=OC_FileCache_Cached::get($path,'');
			return  $cached['size'];
		}else{
			return $size;
		}
	}
}