complete IuCS paging implementation

Add paging timeout to struct gsm_subscriber. Previously, paging timeout was
implemented only on BSC level, where each request has its own timeout value.
The MSC will still send individual requests to BSC or RNC level, where they
timeout individually. However, the MSC must also have an own timeout to be sure
to discard stale pagings that the BSC or RNC never replied for.

Add handle_paging_resp(), copying the few libmsc relevant parts of
gsm48_handle_paging_resp().

2 files changed, 82 insertions, 32 deletions

diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c
index 909642ea1..b86fed31a 100644
--- a/openbsc/src/libmsc/gsm_04_08.c
+++ b/openbsc/src/libmsc/gsm_04_08.c
@@ -1168,7 +1168,7 @@ static int gsm48_rx_rr_pag_resp(struct gsm_subscriber_connection *conn, struct m
 			 classmark_is_r99(&conn->classmark),
 			 conn->via_ran == RAN_UTRAN_IU);
 
-	return rc;
+	return 0;
 }
 
 static int gsm48_rx_rr_app_info(struct gsm_subscriber_connection *conn, struct msgb *msg)
@@ -3451,13 +3451,11 @@ int mncc_tx_to_cc(struct gsm_network *net, int msg_type, void *arg)
 				trans_free(trans);
 				return 0;
 			}
-			/* store setup informations until paging was successfull */
+			/* store setup information until paging succeeds */
 			memcpy(&trans->cc.msg, data, sizeof(struct gsm_mncc));
 
 			/* Request a channel */
-			trans->paging_request = subscr_request_channel(
-							vsub,
-							RSL_CHANNEED_TCH_F,
+			trans->paging_request = subscr_request_conn(subscr,
 							setup_trig_pag_evt,
 							trans);
 			if (!trans->paging_request) {
diff --git a/openbsc/src/libmsc/gsm_subscriber.c b/openbsc/src/libmsc/gsm_subscriber.c
index 315c49218..050da9255 100644
--- a/openbsc/src/libmsc/gsm_subscriber.c
+++ b/openbsc/src/libmsc/gsm_subscriber.c
@@ -59,10 +59,7 @@ static struct bsc_subscr *vlr_subscr_to_bsc_sub(struct llist_head *bsc_subscribe
 	return sub;
 }
 
-/*
- * We got the channel assigned and can now hand this channel
- * over to one of our callbacks.
- */
+/* A connection is established and the paging callbacks may run now. */
 int subscr_paging_dispatch(unsigned int hooknum, unsigned int event,
 			   struct msgb *msg, void *data, void *param)
 {
@@ -73,12 +70,25 @@ int subscr_paging_dispatch(unsigned int hooknum, unsigned int event,
 	struct bsc_subscr *bsub;
 	struct gsm_network *net;
 
-	OSMO_ASSERT(vsub && vsub->cs.is_paging);
+	OSMO_ASSERT(vsub);
 	net = vsub->vlr->user_ctx;
+	OSMO_ASSERT(hooknum == GSM_HOOK_RR_PAGING);
+	OSMO_ASSERT(!(conn && (conn->vsub != vsub)));
+	OSMO_ASSERT(!((event == GSM_PAGING_SUCCEEDED) && !conn));
+
+	LOGP(DPAG, LOGL_DEBUG, "Paging %s for %s (event=%d)\n",
+	     event == GSM_PAGING_SUCCEEDED ? "success" : "failure",
+	     subscr_name(subscr), event);
+
+	if (!subscr->is_paging) {
+		LOGP(DPAG, LOGL_ERROR,
+		     "Paging Response received for subscriber"
+		     " that is not paging.\n");
+		return -EINVAL;
+	}
 
 	/* Inform parts of the system we don't know */
 	sig_data.vsub	= vsub;
-	sig_data.bts	= conn ? conn->bts : NULL;
 	sig_data.conn	= conn;
 	sig_data.paging_result = event;
 	osmo_signal_dispatch(
@@ -90,7 +100,11 @@ int subscr_paging_dispatch(unsigned int hooknum, unsigned int event,
 
 	llist_for_each_entry_safe(request, tmp, &vsub->cs.requests, entry) {
 		llist_del(&request->entry);
-		request->cbfn(hooknum, event, msg, data, request->param);
+		if (request->cbfn) {
+			LOGP(DPAG, LOGL_DEBUG, "Calling paging cbfn.\n");
+			request->cbfn(hooknum, event, msg, data, request->param);
+		} else
+			LOGP(DPAG, LOGL_DEBUG, "Paging without action.\n");
 		talloc_free(request);
 	}
 
@@ -100,28 +114,59 @@ int subscr_paging_dispatch(unsigned int hooknum, unsigned int event,
 	return 0;
 }
 
+static void paging_timeout_release(struct gsm_subscriber *subscr)
+{
+	DEBUGP(DPAG, "Paging timeout released for %s\n", subscr_name(subscr));
+	osmo_timer_del(&subscr->paging_timeout);
+}
+
+static void paging_timeout(void *data)
+{
+	struct gsm_subscriber *subscr = data;
+	DEBUGP(DPAG, "Paging timeout reached for %s\n", subscr_name(subscr));
+	paging_timeout_release(subscr);
+	subscr_paging_dispatch(GSM_HOOK_RR_PAGING, GSM_PAGING_EXPIRED,
+			       NULL, NULL, subscr);
+}
+
+static void paging_timeout_start(struct gsm_subscriber *subscr)
+{
+	DEBUGP(DPAG, "Starting paging timeout for %s\n", subscr_name(subscr));
+	subscr->paging_timeout.data = subscr;
+	subscr->paging_timeout.cb = paging_timeout;
+	osmo_timer_schedule(&subscr->paging_timeout, 10, 0);
+	/* TODO: configurable timeout duration? */
+}
+
+
 static int subscr_paging_sec_cb(unsigned int hooknum, unsigned int event,
                                 struct msgb *msg, void *data, void *param)
 {
 	int rc;
+	struct gsm_subscriber_connection *conn = data;
+	OSMO_ASSERT(conn);
 
 	switch (event) {
 		case GSM_SECURITY_AUTH_FAILED:
-			/* Dispatch as paging failure */
+			LOGP(DPAG, LOGL_ERROR,
+			     "Dropping Paging Response:"
+			     " authorization failed for subscriber %s\n",
+			     subscr_name(conn->subscr));
 			rc = subscr_paging_dispatch(
 				GSM_HOOK_RR_PAGING, GSM_PAGING_EXPIRED,
-				msg, data, param);
+				msg, conn, conn->subscr);
 			break;
 
 		case GSM_SECURITY_NOAVAIL:
 		case GSM_SECURITY_SUCCEEDED:
-			/* Dispatch as paging failure */
 			rc = subscr_paging_dispatch(
 				GSM_HOOK_RR_PAGING, GSM_PAGING_SUCCEEDED,
-				msg, data, param);
+				msg, conn, conn->subscr);
 			break;
 
 		default:
+			LOGP(DPAG, LOGL_FATAL,
+			     "Invalid authorization event: %d\n", event);
 			rc = -EINVAL;
 	}
 
@@ -138,6 +183,8 @@ int subscr_rx_paging_response(struct msgb *msg,
 	gh = msgb_l3(msg);
 	pr = (struct gsm48_pag_resp *)gh->data;
 
+	paging_timeout_release(conn->subscr);
+
 	/* Secure the connection */
 	if (subscr_authorized(conn->subscr))
 		return gsm48_secure_channel(conn, pr->key_seq,
@@ -149,9 +196,21 @@ int subscr_rx_paging_response(struct msgb *msg,
 	return -1;
 }
 
-struct subscr_request *subscr_request_channel(struct vlr_subscr *vsub,
-					      int channel_type,
-					      gsm_cbfn *cbfn, void *param)
+static int msc_paging_request(struct gsm_subscriber *subscr)
+{
+	/* The subscriber was last seen in subscr->lac. Find out which
+	 * BSCs/RNCs are responsible and send them a paging request via open
+	 * SCCP connections (if any). */
+	/* TODO Implementing only RNC paging, since this is code on the iu branch.
+	 * Need to add BSC paging at some point. */
+	return iu_page_cs(subscr->imsi,
+			  subscr->tmsi == GSM_RESERVED_TMSI?
+				NULL : &subscr->tmsi,
+			  subscr->lac);
+}
+
+struct subscr_request *subscr_request_conn(struct vlr_subscr *vsub,
+					   gsm_cbfn *cbfn, void *param)
 {
 	int rc;
 	struct subscr_request *request;
@@ -159,20 +218,10 @@ struct subscr_request *subscr_request_channel(struct vlr_subscr *vsub,
 	struct gsm_network *net = vsub->vlr->user_ctx;
 
 	/* Start paging.. we know it is async so we can do it before */
-	if (!vsub->cs.is_paging) {
-		LOGP(DMM, LOGL_DEBUG, "Subscriber %s not paged yet.\n",
+	if (!subscr->is_paging) {
+		LOGP(DMM, LOGL_DEBUG, "Subscriber %s not paged yet, start paging.\n",
 		     vlr_subscr_name(vsub));
-#if 0
-		TODO implement paging response in libmsc!
-		Excluding this to be able to link without libbsc:
-
-		bsub = vlr_subscr_to_bsc_sub(net->bsc_subscribers, vsub);
-		rc = paging_request(net, bsub, channel_type, subscr_paging_cb,
-				    vsub);
-		bsc_subscr_put(bsub);
-#else
-		rc = -ENOTSUP;
-#endif
+		rc = msc_paging_request(vsub);
 		if (rc <= 0) {
 			LOGP(DMM, LOGL_ERROR, "Subscriber %s paging failed: %d\n",
 			     vlr_subscr_name(vsub), rc);
@@ -181,6 +230,9 @@ struct subscr_request *subscr_request_channel(struct vlr_subscr *vsub,
 		/* reduced on the first paging callback */
 		vlr_subscr_get(vsub);
 		vsub->cs.is_paging = true;
+	} else {
+		LOGP(DMM, LOGL_DEBUG, "Subscriber %s already paged.\n",
+			subscr_name(subscr));
 	}
 
 	/* TODO: Stop paging in case of memory allocation failure */