Make extending subscriber creation easier

* rename variable controlling subscriber creation
* use enum for subscriber creation policy
* move check for subscriber creation policy into separate static
  function

Related: OS#1658, OS#1647
Change-Id: I3b10a9a764fd3a7bb96717a990e52caae16266da
Reviewed-on: https://gerrit.osmocom.org/42
Tested-by: Jenkins Builder
Reviewed-by: Holger Freyther <holger@freyther.de>
diff --git a/openbsc/src/libmsc/vty_interface_layer3.c b/openbsc/src/libmsc/vty_interface_layer3.c
index 4c2088a..5d74e04 100644
--- a/openbsc/src/libmsc/vty_interface_layer3.c
+++ b/openbsc/src/libmsc/vty_interface_layer3.c
@@ -1036,7 +1036,7 @@
       "Make a new record when a subscriber is first seen.\n")
 {
 	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
-	gsmnet->create_subscriber = 1;
+	gsmnet->subscr_creation_mode = GSM_SUBSCR_CREAT_W_RAND_EXT;
 	return CMD_SUCCESS;
 }
 
@@ -1045,7 +1045,7 @@
       NO_STR "Make a new record when a subscriber is first seen.\n")
 {
 	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
-	gsmnet->create_subscriber = 0;
+	gsmnet->subscr_creation_mode = GSM_SUBSCR_DONT_CREATE;
 	return CMD_SUCCESS;
 }
 
@@ -1072,7 +1072,7 @@
 	struct gsm_network *gsmnet = gsmnet_from_vty(vty);
 	vty_out(vty, "nitb%s", VTY_NEWLINE);
 	vty_out(vty, " %ssubscriber-create-on-demand%s",
-		gsmnet->create_subscriber ? "" : "no ", VTY_NEWLINE);
+		gsmnet->subscr_creation_mode ? "" : "no ", VTY_NEWLINE);
 	vty_out(vty, " %sassign-tmsi%s",
 		gsmnet->avoid_tmsi ? "no " : "", VTY_NEWLINE);
 	return CMD_SUCCESS;