Return whole file if range request cannot be granted due to encryption

Whenenver range headers are set and encryption is enabled, it is not
possible to automatically fseek() to the proper position.

To avoid returning corrupt/invalid data or causing a decryption error,
the range headers are stripped so that the SabreDAV code in httpGet()
returns the whole file.

lib/private/connector/sabre/server.php

@@ -33,6 +33,11 @@ class OC_Connector_Sabre_Server extends Sabre\DAV\Server {
 	 */
 	private $overLoadedUri = null;
 
+	/**
+	 * @var boolean
+	 */
+	private $ignoreRangeHeader = false;
+
 	public function getRequestUri() {
 
 		if (!is_null($this->overLoadedUri)) {
@@ -59,6 +64,23 @@ class OC_Connector_Sabre_Server extends Sabre\DAV\Server {
 		return $result;
 	}
 
+	public function getHTTPRange() {
+		if ($this->ignoreRangeHeader) {
+			return null;
+		}
+		return parent::getHTTPRange();
+	}
+
+	protected function httpGet($uri) {
+		$range = $this->getHTTPRange();
+
+		if (OC_App::isEnabled('files_encryption') && $range) {
+			// encryption does not support range requests
+			$this->ignoreRangeHeader = true;	
+		}
+		return parent::httpGet($uri);
+	}
+
 	/**
 	 * @see \Sabre\DAV\Server
 	 */