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 requires encryption
	 * @param string $path
	 * @return bool
	 *
	 * Tests if encryption is enabled, and file is allowed by blacklists
	 */
	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;
			
		}
		
		return false;
	}

	/**
	 * Check if a file is encrypted according to database file cache
	 * @param string $path
	 * @return bool
	 */
	private static function isEncrypted( $path ){
	
		// Fetch all file metadata from DB
		$metadata = OC_FileCache_Cached::get( $path, '' );
		
		// Return encryption status
		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 = 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;
		}
	}
}