Show a warning in the installer if no secure RNG is available

2 files changed, 27 insertions, 1 deletions

diff --git a/lib/setup.php b/lib/setup.php
index 9e7129da5b5..8d80e9d9789 100644
--- a/lib/setup.php
+++ b/lib/setup.php
@@ -4,11 +4,13 @@ $hasSQLite = (is_callable('sqlite_open') or class_exists('SQLite3'));
 $hasMySQL = is_callable('mysql_connect');
 $hasPostgreSQL = is_callable('pg_connect');
 $datadir = OC_Config::getValue('datadirectory', OC::$SERVERROOT.'/data');
+
 $opts = array(
 	'hasSQLite' => $hasSQLite,
 	'hasMySQL' => $hasMySQL,
 	'hasPostgreSQL' => $hasPostgreSQL,
 	'directory' => $datadir,
+	'secureRNG' => OC_Util::secureRNG_available(),
 	'errors' => array(),
 );
 
diff --git a/lib/util.php b/lib/util.php
index 127570e9f3d..8db3c307f95 100644
--- a/lib/util.php
+++ b/lib/util.php
@@ -463,6 +463,7 @@ class OC_Util {
 	* @brief Generates a cryptographical secure pseudorandom string
 	* @param Int with the length of the random string
 	* @return String
+	* Please also update secureRNG_available if you change something here
 	*/
 	public static function generate_random_bytes($length = 30) {
 
@@ -493,4 +494,27 @@ class OC_Util {
 		}        
 		return $pseudo_byte;
 	}
-}
+	
+	/*
+	* @brief Checks if a secure random number generator is available
+	* @return bool 
+	*/
+	public static function secureRNG_available() {
+
+		// Check openssl_random_pseudo_bytes
+		if(function_exists('openssl_random_pseudo_bytes')) { 
+			openssl_random_pseudo_bytes(1, $strong);
+			if($strong == TRUE) {
+				return true;
+			}
+		}
+
+		// Check /dev/random
+		$fp = @file_get_contents('/dev/random', false, null, 0, 1);
+		if ($fp !== FALSE) {
+			return true;
+		}
+
+		return false;
+	}	
+}
\ No newline at end of file