pimd: fix null register before aging out reg-stop

It looks like the code was trying to do this with the null_register
parameter on pim_upstream_start_register_stop_timer(), but that didn't
quite work right.  Restructure a bit to get it right.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
(cherry picked from commit dce38da8061a7ac62c690dbb8a89cae7f9a758d6)

# Conflicts:
#	pimd/pim_upstream.c

3 files changed, 46 insertions, 18 deletions

diff --git a/pimd/pim_register.c b/pimd/pim_register.c
index 9ccdae13bc..d4eb88e75b 100644
--- a/pimd/pim_register.c
+++ b/pimd/pim_register.c
@@ -123,12 +123,12 @@ static void pim_reg_stop_upstream(struct pim_instance *pim,
 		up->reg_state = PIM_REG_PRUNE;
 		pim_channel_del_oif(up->channel_oil, pim->regiface,
 				    PIM_OIF_FLAG_PROTO_PIM, __func__);
-		pim_upstream_start_register_stop_timer(up, 0);
+		pim_upstream_start_register_probe_timer(up);
 		pim_vxlan_update_sg_reg_state(pim, up, false);
 		break;
 	case PIM_REG_JOIN_PENDING:
 		up->reg_state = PIM_REG_PRUNE;
-		pim_upstream_start_register_stop_timer(up, 0);
+		pim_upstream_start_register_probe_timer(up);
 		return;
 	}
 }
diff --git a/pimd/pim_upstream.c b/pimd/pim_upstream.c
index be575ee1ec..749790fb97 100644
--- a/pimd/pim_upstream.c
+++ b/pimd/pim_upstream.c
@@ -1692,6 +1692,8 @@ const char *pim_reg_state2str(enum pim_reg_state reg_state, char *state_str,
 	return state_str;
 }
 
+static void pim_upstream_start_register_stop_timer(struct pim_upstream *up);
+
 static void pim_upstream_register_stop_timer(struct thread *t)
 {
 	struct pim_interface *pim_ifp;
@@ -1738,7 +1740,7 @@ static void pim_upstream_register_stop_timer(struct thread *t)
 			return;
 		}
 		up->reg_state = PIM_REG_JOIN_PENDING;
-		pim_upstream_start_register_stop_timer(up, 1);
+		pim_upstream_start_register_stop_timer(up);
 
 		if (((up->channel_oil->cc.lastused / 100)
 		     > pim->keep_alive_time)
@@ -1756,24 +1758,13 @@ static void pim_upstream_register_stop_timer(struct thread *t)
 	}
 }
 
-void pim_upstream_start_register_stop_timer(struct pim_upstream *up,
-					    int null_register)
+static void pim_upstream_start_register_stop_timer(struct pim_upstream *up)
 {
 	uint32_t time;
 
 	THREAD_OFF(up->t_rs_timer);
 
-	if (!null_register) {
-		uint32_t lower = (0.5 * router->register_suppress_time);
-		uint32_t upper = (1.5 * router->register_suppress_time);
-		time = lower + (frr_weak_random() % (upper - lower + 1));
-		/* Make sure we don't wrap around */
-		if (time >= router->register_probe_time)
-			time -= router->register_probe_time;
-		else
-			time = 0;
-	} else
-		time = router->register_probe_time;
+	time = router->register_probe_time;
 
 	if (PIM_DEBUG_PIM_TRACE) {
 		zlog_debug(
@@ -1784,6 +1775,44 @@ void pim_upstream_start_register_stop_timer(struct pim_upstream *up,
 			 time, &up->t_rs_timer);
 }
 
+static void pim_upstream_register_probe_timer(struct thread *t)
+{
+	struct pim_upstream *up = THREAD_ARG(t);
+
+	if (!up->rpf.source_nexthop.interface ||
+	    !up->rpf.source_nexthop.interface->info) {
+		if (PIM_DEBUG_PIM_REG)
+			zlog_debug("cannot send Null register for %pSG, no path to RP",
+				   &up->sg);
+	} else
+		pim_null_register_send(up);
+
+	pim_upstream_start_register_stop_timer(up);
+}
+
+void pim_upstream_start_register_probe_timer(struct pim_upstream *up)
+{
+	uint32_t time;
+
+	THREAD_OFF(up->t_rs_timer);
+
+	uint32_t lower = (0.5 * router->register_suppress_time);
+	uint32_t upper = (1.5 * router->register_suppress_time);
+	time = lower + (frr_weak_random() % (upper - lower + 1));
+	/* Make sure we don't wrap around */
+	if (time >= router->register_probe_time)
+		time -= router->register_probe_time;
+	else
+		time = 0;
+
+	if (PIM_DEBUG_PIM_TRACE)
+		zlog_debug("%s: (S,G)=%s Starting upstream register stop null probe timer %d",
+			   __func__, up->sg_str, time);
+
+	thread_add_timer(router->master, pim_upstream_register_probe_timer, up,
+			time, &up->t_rs_timer);
+}
+
 int pim_upstream_inherited_olist_decide(struct pim_instance *pim,
 					struct pim_upstream *up)
 {
diff --git a/pimd/pim_upstream.h b/pimd/pim_upstream.h
index 15c4fcfe7e..a7611b0489 100644
--- a/pimd/pim_upstream.h
+++ b/pimd/pim_upstream.h
@@ -344,8 +344,7 @@ int pim_upstream_is_sg_rpt(struct pim_upstream *up);
 void pim_upstream_set_sptbit(struct pim_upstream *up,
 			     struct interface *incoming);
 
-void pim_upstream_start_register_stop_timer(struct pim_upstream *up,
-					    int null_register);
+void pim_upstream_start_register_probe_timer(struct pim_upstream *up);
 
 void pim_upstream_send_join(struct pim_upstream *up);