nextcloud/apps/files_encryption/lib/cryptstream.php

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<?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/>.
*
*/
/**
* transparently encrypted filestream
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*
* you can use it as wrapper around an existing stream by setting OC_CryptStream::$sourceStreams['foo']=array('path'=>$path,'stream'=>$stream)
* and then fopen('crypt://streams/foo');
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*/
class OC_CryptStream{
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public static $sourceStreams=array();
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private $source;
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private $path;
private $readBuffer;//for streams that dont support seeking
private $meta=array();//header/meta for source stream
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public function stream_open($path, $mode, $options, &$opened_path){
$path=str_replace('crypt://','',$path);
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if(dirname($path)=='streams' and isset(self::$sourceStreams[basename($path)])){
$this->source=self::$sourceStreams[basename($path)]['stream'];
$this->path=self::$sourceStreams[basename($path)]['path'];
}else{
$this->path=$path;
OC_Log::write('files_encryption','open encrypted '.$path. ' in '.$mode,OC_Log::DEBUG);
OC_FileProxy::$enabled=false;//disable fileproxies so we can open the source file
$this->source=OC_FileSystem::fopen($path,$mode);
OC_FileProxy::$enabled=true;
if(!is_resource($this->source)){
OC_Log::write('files_encryption','failed to open '.$path,OC_Log::ERROR);
}
}
if(is_resource($this->source)){
$this->meta=stream_get_meta_data($this->source);
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}
return is_resource($this->source);
}
public function stream_seek($offset, $whence=SEEK_SET){
fseek($this->source,$offset,$whence);
}
public function stream_tell(){
return ftell($this->source);
}
public function stream_read($count){
$pos=0;
$currentPos=ftell($this->source);
$offset=$currentPos%8192;
$result='';
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if($offset>0){
if($this->meta['seekable']){
fseek($this->source,-$offset,SEEK_CUR);//if seeking isnt supported the internal read buffer will be used
}else{
$pos=strlen($this->readBuffer);
$result=$this->readBuffer;
}
}
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while($count>$pos){
$data=fread($this->source,8192);
$pos+=8192;
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if(strlen($data)){
$result.=OC_Crypt::decrypt($data);
}
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}
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if(!$this->meta['seekable']){
$this->readBuffer=substr($result,$count);
}
return substr($result,0,$count);
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}
public function stream_write($data){
$length=strlen($data);
$written=0;
$currentPos=ftell($this->source);
if($currentPos%8192!=0){
//make sure we always start on a block start
fseek($this->source,-($currentPos%8192),SEEK_CUR);
$encryptedBlock=fread($this->source,8192);
fseek($this->source,-($currentPos%8192),SEEK_CUR);
$block=OC_Crypt::decrypt($encryptedBlock);
$data=substr($block,0,$currentPos%8192).$data;
}
while(strlen($data)>0){
if(strlen($data)<8192){
//fetch the current data in that block and append it to the input so we always write entire blocks
$oldPos=ftell($this->source);
$encryptedBlock=fread($this->source,8192);
fseek($this->source,$oldPos);
$block=OC_Crypt::decrypt($encryptedBlock);
$data.=substr($block,strlen($data));
}
$encrypted=OC_Crypt::encrypt(substr($data,0,8192));
fwrite($this->source,$encrypted);
$data=substr($data,8192);
}
return $length;
}
public function stream_set_option($option,$arg1,$arg2){
switch($option){
case STREAM_OPTION_BLOCKING:
stream_set_blocking($this->source,$arg1);
break;
case STREAM_OPTION_READ_TIMEOUT:
stream_set_timeout($this->source,$arg1,$arg2);
break;
case STREAM_OPTION_WRITE_BUFFER:
stream_set_write_buffer($this->source,$arg1,$arg2);
}
}
public function stream_stat(){
return fstat($this->source);
}
public function stream_lock($mode){
flock($this->source,$mode);
}
public function stream_flush(){
return fflush($this->source);
}
public function stream_eof(){
return feof($this->source);
}
public function stream_close(){
OC_FileCache::put($this->path,array('encrypted'=>true));
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return fclose($this->source);
}
}