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m3ua/sua: Implement ASP Hearbeat procedure

This implements M3UA/SUA Heartbeat Procedure.

Change-Id: Ie4d90447ef8f1b1174085aad55114ab6460ca559
---
M src/xua_asp_fsm.c
1 file changed, 81 insertions(+), 2 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/libosmo-sigtran refs/changes/61/40461/1

diff --git a/src/xua_asp_fsm.c b/src/xua_asp_fsm.c
index 7c0c105..a12e684 100644
--- a/src/xua_asp_fsm.c
+++ b/src/xua_asp_fsm.c
@@ -89,6 +89,12 @@
 		struct osmo_timer_list timer;
 		int out_event;
 	} t_ack;
+
+	/* Timer for tracking HEARBEAT without HEARBEAT ACK */
+	struct {
+		struct osmo_timer_list timer;
+		uint32_t unacked_beats;
+	} t_beat;
 };
 
 struct osmo_xlm_prim *xua_xlm_prim_alloc(enum osmo_xlm_prim_type prim_type,
@@ -388,6 +394,61 @@
 	}
 }
 
+static void xua_t_beat_stop(struct osmo_fsm_inst *fi)
+{
+	struct xua_asp_fsm_priv *xafp = fi->priv;
+	osmo_timer_del(&xafp->t_beat.timer);
+	xafp->t_beat.unacked_beats = 0;
+}
+
+static void xua_t_beat_send(struct osmo_fsm_inst *fi)
+{
+	struct xua_asp_fsm_priv *xafp = fi->priv;
+	uint32_t timeout_sec;
+
+	timeout_sec = osmo_tdef_get(xafp->asp->cfg.T_defs_xua, SS7_ASP_XUA_T_BEAT, OSMO_TDEF_S, -1);
+
+	/* T(beat) disabled */
+	if (timeout_sec == 0) {
+		xua_t_beat_stop(fi);
+		return;
+	}
+
+	/* Avoid increasing in case some extra gratuitous PING is transmitted: */
+	if (!osmo_timer_pending(&xafp->t_beat.timer))
+		xafp->t_beat.unacked_beats++;
+
+	/* (re-)arm T(beat): */
+	osmo_timer_schedule(&xafp->t_beat.timer, timeout_sec, 0);
+
+	/* Send HEARTBEAT: */
+	peer_send(fi, XUA_ASP_E_ASPSM_BEAT, NULL);
+
+}
+
+static void xua_t_beat_cb(void *_fi)
+{
+	struct osmo_fsm_inst *fi = _fi;
+	struct xua_asp_fsm_priv *xafp = fi->priv;
+
+	LOGPFSML(fi, LOGL_NOTICE, "Peer didn't respond to PING? with PONG!\n");
+
+	if (xafp->t_beat.unacked_beats < 2) {
+		xua_t_beat_send(fi);
+		return;
+	}
+
+	/* RFC4666 4.3.4.6: If no Heartbeat Ack message (or any other M3UA
+	 * message) is received from the M3UA peer within 2*T(beat), the remote
+	 * M3UA peer is considered unavailable.  Transmission of Heartbeat
+	 * messages is stopped, and the signalling process SHOULD attempt to
+	 * re-establish communication if it is configured as the client for the
+	 * disconnected M3UA peer.
+	 */
+	ss7_asp_disconnect_stream(xafp->asp);
+
+}
+
 #define ENSURE_ASP_OR_IPSP(fi, event) 					\
 	do {								\
 		struct xua_asp_fsm_priv *_xafp = fi->priv;		\
@@ -423,6 +484,7 @@
 {
 	struct xua_asp_fsm_priv *xafp = fi->priv;
 	struct osmo_ss7_asp *asp = xafp->asp;
+	xua_t_beat_stop(fi);
 	dispatch_to_all_as(fi, XUA_ASPAS_ASP_DOWN_IND, asp);
 }
 
@@ -489,6 +551,13 @@
 {
 	struct xua_asp_fsm_priv *xafp = fi->priv;
 	struct osmo_ss7_asp *asp = xafp->asp;
+	bool went_up = (prev_state == XUA_ASP_S_DOWN);
+
+	if (went_up) {
+		/* Now we are done with IPA handshake, Start Hearbeat Procedure, T(beat): */
+		xua_t_beat_send(fi);
+	}
+
 	/* RFC4666 4.3.4.5: "When an ASP moves from ASP-DOWN to ASP-INACTIVE within a
 	 * particular AS, a Notify message SHOULD be sent, by the ASP-UP receptor,
 	 * after sending the ASP-UP-ACK, in order to inform the ASP of the current AS
@@ -498,7 +567,7 @@
 	struct xua_as_event_asp_inactive_ind_pars pars = {
 		.asp = asp,
 		.asp_requires_notify = (asp->cfg.role != OSMO_SS7_ASP_ROLE_ASP) &&
-				       (prev_state == XUA_ASP_S_DOWN),
+				       went_up,
 	};
 	dispatch_to_all_as(fi, XUA_ASPAS_ASP_INACTIVE_IND, &pars);
 }
@@ -620,6 +689,13 @@
 {
 	struct xua_asp_fsm_priv *xafp = fi->priv;
 	struct osmo_ss7_asp *asp = xafp->asp;
+	bool went_up = (prev_state == XUA_ASP_S_DOWN);
+
+	if (went_up) {
+		/* Now we are done with IPA handshake, Start Hearbeat Procedure, T(beat): */
+		xua_t_beat_send(fi);
+	}
+
 	dispatch_to_all_as(fi, XUA_ASPAS_ASP_ACTIVE_IND, asp);
 }
 
@@ -717,7 +793,7 @@
 		peer_send(fi, XUA_ASP_E_ASPSM_BEAT_ACK, xua);
 		break;
 	case XUA_ASP_E_ASPSM_BEAT_ACK:
-		/* FIXME: stop timer, if any */
+		xafp->t_beat.unacked_beats = 0;
 		break;
 	case XUA_ASP_E_AS_ASSIGNED:
 		/* Ignore, only used in IPA asps so far. */
@@ -742,6 +818,7 @@
 		return;
 
 	osmo_timer_del(&xafp->t_ack.timer);
+	xua_t_beat_stop(fi);
 
 	if (xafp->asp)
 		xafp->asp->fi = NULL;
@@ -839,6 +916,8 @@
 	xafp->role = role;
 	xafp->asp = asp;
 
+	osmo_timer_setup(&xafp->t_beat.timer, xua_t_beat_cb, fi);
+
 	fi->priv = xafp;
 
 	/* Attach FSM to ASP: */

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