+/**\r
+ * Check if sockets meet certain conditions\r
+ * @param rfds set of sockets to be checked for readability\r
+ * @param wfds set of sockets to be checked for writability\r
+ * @param efds set of sockets to be checked for exceptions\r
+ * @param timeout relative value when to return\r
+ * @return number of selected sockets, GNUNET_SYSERR on error\r
+ */\r