expiration: Speculative fixes for the periodic expiring handling

We were expiring subscribers during active calls. This is because
the T3212 is stopped under certain conditions but we didn't stop
that timer at all.

Remember if T3212 timer was stopped due something done by NITB and
update the expiration time at the end of the radio connection, as
the phone should restart it when returning to MM Idle.

It is a bit difficult to decide when we should set the flag. E.g.
in a CM Service Request we don't know if we accept the service and
during a LU we already send MM messages before we accept or reject
the subscriber.

The easiest is to set the flag when receiving a paging response
on known subscribers and at the end of the authentication process.

Do not expire a subscriber that has an active connection that is
marked with the flag, e.g. we would still expire a subscriber that
is being paged.

Manual tests executed/passed:

 * gst LUTest.st verified that a expiration date was set
 * gst SMSTest.st (doing another LU but forcing a timeout on the
   SMS sending). Verified that the expire_lu was updated.

1 files changed, 42 insertions, 16 deletions

diff --git a/openbsc/src/libmsc/gsm_subscriber.c b/openbsc/src/libmsc/gsm_subscriber.c
index 7ff44075c..6abb0d832 100644
--- a/openbsc/src/libmsc/gsm_subscriber.c
+++ b/openbsc/src/libmsc/gsm_subscriber.c
@@ -1,7 +1,7 @@
 /* The concept of a subscriber for the MSC, roughly HLR/VLR functionality */
 
 /* (C) 2008 by Harald Welte <laforge@gnumonks.org>
- * (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2009,2013 by Holger Hans Peter Freyther <zecke@selfish.org>
  *
  * All Rights Reserved
  *
@@ -37,6 +37,7 @@
 #include <openbsc/paging.h>
 #include <openbsc/signal.h>
 #include <openbsc/db.h>
+#include <openbsc/chan_alloc.h>
 
 void *tall_sub_req_ctx;
 
@@ -323,6 +324,21 @@ struct gsm_subscriber *subscr_get_by_id(struct gsm_network *net,
 	return db_get_subscriber(net, GSM_SUBSCRIBER_ID, buf);
 }
 
+int subscr_update_expire_lu(struct gsm_subscriber *s, struct gsm_bts *bts)
+{
+	int rc;
+
+	/* Table 10.5.33: The T3212 timeout value field is coded as the
+	 * binary representation of the timeout value for
+	 * periodic updating in decihours. Mark the subscriber as
+	 * inactive if it missed two consecutive location updates.
+	 * Timeout is twice the t3212 value plus one minute */
+	s->expire_lu = time(NULL) +
+			(bts->si_common.chan_desc.t3212 * 60 * 6 * 2) + 60;
+	rc = db_sync_subscriber(s);
+	db_subscriber_update(s);
+	return rc;
+}
 
 int subscr_update(struct gsm_subscriber *s, struct gsm_bts *bts, int reason)
 {
@@ -335,24 +351,19 @@ int subscr_update(struct gsm_subscriber *s, struct gsm_bts *bts, int reason)
 		/* Indicate "attached to LAC" */
 		s->lac = bts->location_area_code;
 
+		LOGP(DMM, LOGL_INFO, "Subscriber %s ATTACHED LAC=%u\n",
+			subscr_name(s), s->lac);
+
 		/* FIXME: We should allow 0 for T3212 as well to disable the
 		 * location update period. In that case we will need a way to
 		 * indicate that in the database and then reenable that value in
 		 * VTY.
 		 */
-
-		/* Table 10.5.33: The T3212 timeout value field is coded as the
-		 * binary representation of the timeout value for
-		 * periodic updating in decihours. Mark the subscriber as
-		 * inactive if it missed two consecutive location updates.
-		 * Timeout is twice the t3212 value plus one minute */
-		s->expire_lu = time(NULL) +
-			(bts->si_common.chan_desc.t3212 * 60 * 6 * 2) + 60;
-
-		LOGP(DMM, LOGL_INFO, "Subscriber %s ATTACHED LAC=%u\n",
-			subscr_name(s), s->lac);
-		rc = db_sync_subscriber(s);
-		db_subscriber_update(s);
+		/*
+		 * The below will set a new expire_lu but as a side-effect
+		 * the new lac will be saved in the database.
+		 */
+		rc = subscr_update_expire_lu(s, bts);
 		osmo_signal_dispatch(SS_SUBSCR, S_SUBSCR_ATTACHED, s);
 		break;
 	case GSM_SUBSCRIBER_UPDATE_DETACHED:
@@ -383,8 +394,23 @@ void subscr_update_from_db(struct gsm_subscriber *sub)
 static void subscr_expire_callback(void *data, long long unsigned int id)
 {
 	struct gsm_network *net = data;
-	struct gsm_subscriber *s =
-		subscr_get_by_id(net, id);
+	struct gsm_subscriber *s = subscr_get_by_id(net, id);
+	struct gsm_subscriber_connection *conn = connection_for_subscr(s);
+
+	/*
+	 * The subscriber is active and the phone stopped the timer. As
+	 * we don't want to periodically update the database for active
+	 * subscribers we will just do it when the subscriber was selected
+	 * for expiration. This way on the next around another subscriber
+	 * will be selected.
+	 */
+	if (conn && conn->expire_timer_stopped) {
+		LOGP(DMM, LOGL_DEBUG, "Not expiring subscriber %s (ID %llu)\n",
+			subscr_name(s), id);
+		subscr_update_expire_lu(s, conn->bts);
+		return;
+	}
+
 
 	LOGP(DMM, LOGL_NOTICE, "Expiring inactive subscriber %s (ID %llu)\n",
 			subscr_name(s), id);