/**
* @param int $count
* @return bool|string
* @throws \Exception
*/
public function stream_read($count)
{
$this->writeCache = '';
if ($count !== 8192) {
// $count will always be 8192 https://bugs.php.net/bug.php?id=21641
// This makes this function a lot simpler, but will break this class if the above 'bug' gets 'fixed'
\OCP\Util::writeLog('Encryption library', 'PHP "bug" 21641 no longer holds, decryption system requires refactoring', \OCP\Util::FATAL);
die;
}
// Get the data from the file handle
$data = fread($this->handle, $count);
$result = null;
if (strlen($data)) {
if (!$this->getKey()) {
// Error! We don't have a key to decrypt the file with
throw new \Exception('Encryption key not found for "' . $this->rawPath . '" during attempted read via stream');
} else {
// Decrypt data
$result = Crypt::symmetricDecryptFileContent($data, $this->plainKey);
}
}
return $result;
}
/**
* get the file size of the unencrypted file
* @param string $path absolute path
* @return bool
*/
public function getFileSize($path)
{
$result = 0;
// Disable encryption proxy to prevent recursive calls
$proxyStatus = \OC_FileProxy::$enabled;
\OC_FileProxy::$enabled = false;
// split the path parts
$pathParts = explode('/', $path);
if (isset($pathParts[2]) && $pathParts[2] === 'files' && $this->view->file_exists($path) && $this->isEncryptedPath($path)) {
$cipher = 'AES-128-CFB';
$realSize = 0;
// get the size from filesystem
$size = $this->view->filesize($path);
// open stream
$stream = $this->view->fopen($path, "r");
if (is_resource($stream)) {
// if the file contains a encryption header we
// we set the cipher
// and we update the size
if ($this->containHeader($path)) {
$data = fread($stream, Crypt::BLOCKSIZE);
$header = Crypt::parseHeader($data);
$cipher = Crypt::getCipher($header);
$size -= Crypt::BLOCKSIZE;
}
// fast path, else the calculation for $lastChunkNr is bogus
if ($size === 0) {
\OC_FileProxy::$enabled = $proxyStatus;
return 0;
}
// calculate last chunk nr
// next highest is end of chunks, one subtracted is last one
// we have to read the last chunk, we can't just calculate it (because of padding etc)
$lastChunkNr = ceil($size / Crypt::BLOCKSIZE) - 1;
// calculate last chunk position
$lastChunkPos = $lastChunkNr * Crypt::BLOCKSIZE;
// get the content of the last chunk
if (@fseek($stream, $lastChunkPos, SEEK_CUR) === 0) {
$realSize += $lastChunkNr * 6126;
}
$lastChunkContentEncrypted = '';
$count = Crypt::BLOCKSIZE;
while ($count > 0) {
$data = fread($stream, Crypt::BLOCKSIZE);
$count = strlen($data);
$lastChunkContentEncrypted .= $data;
if (strlen($lastChunkContentEncrypted) > Crypt::BLOCKSIZE) {
$realSize += 6126;
$lastChunkContentEncrypted = substr($lastChunkContentEncrypted, Crypt::BLOCKSIZE);
}
}
fclose($stream);
$relPath = Helper::stripUserFilesPath($path);
$shareKey = Keymanager::getShareKey($this->view, $this->keyId, $this, $relPath);
if ($shareKey === false) {
\OC_FileProxy::$enabled = $proxyStatus;
return $result;
}
$session = new Session($this->view);
$privateKey = $session->getPrivateKey();
$plainKeyfile = $this->decryptKeyfile($relPath, $privateKey);
$plainKey = Crypt::multiKeyDecrypt($plainKeyfile, $shareKey, $privateKey);
$lastChunkContent = Crypt::symmetricDecryptFileContent($lastChunkContentEncrypted, $plainKey, $cipher);
// calc the real file size with the size of the last chunk
$realSize += strlen($lastChunkContent);
// store file size
$result = $realSize;
}
}
\OC_FileProxy::$enabled = $proxyStatus;
return $result;
}
/**
* @param int $count
* @return bool|string
* @throws \OCA\Encryption\Exceptions\EncryptionException
*/
public function stream_read($count)
{
$this->writeCache = '';
if ($count !== Crypt::BLOCKSIZE) {
\OCP\Util::writeLog('Encryption library', 'PHP "bug" 21641 no longer holds, decryption system requires refactoring', \OCP\Util::FATAL);
throw new \OCA\Encryption\Exceptions\EncryptionException('expected a blog size of 8192 byte', 20);
}
// Get the data from the file handle
$data = fread($this->handle, $count);
// if this block contained the header we move on to the next block
if (Crypt::isHeader($data)) {
$data = fread($this->handle, $count);
}
$result = null;
if (strlen($data)) {
if (!$this->getKey()) {
// Error! We don't have a key to decrypt the file with
throw new \Exception('Encryption key not found for "' . $this->rawPath . '" during attempted read via stream');
} else {
// Decrypt data
$result = Crypt::symmetricDecryptFileContent($data, $this->plainKey, $this->cipher);
}
}
return $result;
}
