batman-adv: Prepare framework for mesh genl config

The batman-adv configuration interface was implemented solely using sysfs.
This approach was condemned by non-batadv developers as "huge mistake".
Instead a netlink/genl based implementation was suggested.

The main objects for this configuration is the mesh/soft-interface object.
Its actual object in memory already contains most of the available
configuration settings. The genl interface reflects this by allowing to
get/set it using the mesh specific commands.

The BATADV_CMD_GET_MESH_INFO (or short version BATADV_CMD_GET_MESH) is
reused as get command because it already provides the content of other
information from the mesh/soft-interface which are not yet configuration
specific.

The set command BATADV_CMD_SET_MESH will also notify interested userspace
listeners of the "config" mcast group using the BATADV_CMD_SET_MESH command
message type that settings might have been changed and what the current
values are.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

include/uapi/linux/batman_adv.h

@@ -27,6 +27,7 @@
 
 #define BATADV_NL_NAME "batadv"
 
+#define BATADV_NL_MCAST_GROUP_CONFIG	"config"
 #define BATADV_NL_MCAST_GROUP_TPMETER	"tpmeter"
 
 /**
@@ -372,10 +373,14 @@ enum batadv_nl_commands {
 	BATADV_CMD_UNSPEC,
 
 	/**
-	 * @BATADV_CMD_GET_MESH_INFO: Query basic information about batman-adv
-	 * device
+	 * @BATADV_CMD_GET_MESH: Get attributes from softif/mesh
 	 */
-	BATADV_CMD_GET_MESH_INFO,
+	BATADV_CMD_GET_MESH,
+
+	/**
+	 * @BATADV_CMD_GET_MESH_INFO: Alias for @BATADV_CMD_GET_MESH
+	 */
+	BATADV_CMD_GET_MESH_INFO = BATADV_CMD_GET_MESH,
 
 	/**
 	 * @BATADV_CMD_TP_METER: Start a tp meter session
@@ -443,6 +448,11 @@ enum batadv_nl_commands {
 	 */
 	BATADV_CMD_GET_MCAST_FLAGS,
 
+	/**
+	 * @BATADV_CMD_SET_MESH: Set attributes for softif/mesh
+	 */
+	BATADV_CMD_SET_MESH,
+
 	/* add new commands above here */
 
 	/**