pimd: Limit pim's ecmp to what zebra tells us is the multipath

Zebra can be setup to use a value that is less than MULTIPATH_NUM.
When pimd connects to zebra, zebra will inform pim about the MULTIPATH_NUM
used.  Let's use that value for figuring out our multipath value.

Signed-off-by: Donald Sharp <sharpd@nvidia.com>

6 files changed, 22 insertions, 17 deletions

diff --git a/pimd/pim_instance.h b/pimd/pim_instance.h
index b19e8208ba..23b9df4aff 100644
--- a/pimd/pim_instance.h
+++ b/pimd/pim_instance.h
@@ -88,6 +88,7 @@ struct pim_router {
 	uint32_t register_suppress_time;
 	int packet_process;
 	uint32_t register_probe_time;
+	uint16_t multipath;
 
 	/*
 	 * What is the default vrf that we work in
diff --git a/pimd/pim_nht.c b/pimd/pim_nht.c
index 22716c2a92..564d16a60b 100644
--- a/pimd/pim_nht.c
+++ b/pimd/pim_nht.c
@@ -304,15 +304,15 @@ bool pim_nht_bsr_rpf_check(struct pim_instance *pim, struct in_addr bsr_addr,
 		 * "check cache or get immediate result." But until that can
 		 * be worked in, here's a copy of the code below :(
 		 */
-		struct pim_zlookup_nexthop nexthop_tab[MULTIPATH_NUM];
+		struct pim_zlookup_nexthop nexthop_tab[router->multipath];
 		ifindex_t i;
 		struct interface *ifp = NULL;
 		int num_ifindex;
 
 		memset(nexthop_tab, 0, sizeof(nexthop_tab));
-		num_ifindex = zclient_lookup_nexthop(pim, nexthop_tab,
-						     MULTIPATH_NUM, bsr_addr,
-						     PIM_NEXTHOP_LOOKUP_MAX);
+		num_ifindex = zclient_lookup_nexthop(
+			pim, nexthop_tab, router->multipath, bsr_addr,
+			PIM_NEXTHOP_LOOKUP_MAX);
 
 		if (num_ifindex <= 0)
 			return false;
@@ -501,8 +501,8 @@ static int pim_ecmp_nexthop_search(struct pim_instance *pim,
 				   struct prefix *src, struct prefix *grp,
 				   int neighbor_needed)
 {
-	struct pim_neighbor *nbrs[MULTIPATH_NUM], *nbr = NULL;
-	struct interface *ifps[MULTIPATH_NUM];
+	struct pim_neighbor *nbrs[router->multipath], *nbr = NULL;
+	struct interface *ifps[router->multipath];
 	struct nexthop *nh_node = NULL;
 	ifindex_t first_ifindex;
 	struct interface *ifp = NULL;
@@ -888,11 +888,11 @@ int pim_ecmp_nexthop_lookup(struct pim_instance *pim,
 			    struct prefix *grp, int neighbor_needed)
 {
 	struct pim_nexthop_cache *pnc;
-	struct pim_zlookup_nexthop nexthop_tab[MULTIPATH_NUM];
-	struct pim_neighbor *nbrs[MULTIPATH_NUM], *nbr = NULL;
+	struct pim_zlookup_nexthop nexthop_tab[router->multipath];
+	struct pim_neighbor *nbrs[router->multipath], *nbr = NULL;
 	struct pim_rpf rpf;
 	int num_ifindex;
-	struct interface *ifps[MULTIPATH_NUM], *ifp;
+	struct interface *ifps[router->multipath], *ifp;
 	int first_ifindex;
 	int found = 0;
 	uint8_t i = 0;
@@ -915,9 +915,10 @@ int pim_ecmp_nexthop_lookup(struct pim_instance *pim,
 	}
 
 	memset(nexthop_tab, 0,
-	       sizeof(struct pim_zlookup_nexthop) * MULTIPATH_NUM);
-	num_ifindex = zclient_lookup_nexthop(pim, nexthop_tab, MULTIPATH_NUM,
-					     src_addr, PIM_NEXTHOP_LOOKUP_MAX);
+	       sizeof(struct pim_zlookup_nexthop) * router->multipath);
+	num_ifindex =
+		zclient_lookup_nexthop(pim, nexthop_tab, router->multipath,
+				       src_addr, PIM_NEXTHOP_LOOKUP_MAX);
 	if (num_ifindex < 1) {
 		if (PIM_DEBUG_PIM_NHT)
 			zlog_warn(
diff --git a/pimd/pim_rpf.c b/pimd/pim_rpf.c
index c470bcd4d7..bd4dd31a2c 100644
--- a/pimd/pim_rpf.c
+++ b/pimd/pim_rpf.c
@@ -54,7 +54,7 @@ void pim_rpf_set_refresh_time(struct pim_instance *pim)
 bool pim_nexthop_lookup(struct pim_instance *pim, struct pim_nexthop *nexthop,
 			pim_addr addr, int neighbor_needed)
 {
-	struct pim_zlookup_nexthop nexthop_tab[MULTIPATH_NUM];
+	struct pim_zlookup_nexthop nexthop_tab[router->multipath];
 	struct pim_neighbor *nbr = NULL;
 	int num_ifindex;
 	struct interface *ifp = NULL;
@@ -92,9 +92,10 @@ bool pim_nexthop_lookup(struct pim_instance *pim, struct pim_nexthop *nexthop,
 	}
 
 	memset(nexthop_tab, 0,
-	       sizeof(struct pim_zlookup_nexthop) * MULTIPATH_NUM);
-	num_ifindex = zclient_lookup_nexthop(pim, nexthop_tab, MULTIPATH_NUM,
-					     addr, PIM_NEXTHOP_LOOKUP_MAX);
+	       sizeof(struct pim_zlookup_nexthop) * router->multipath);
+	num_ifindex =
+		zclient_lookup_nexthop(pim, nexthop_tab, router->multipath,
+				       addr, PIM_NEXTHOP_LOOKUP_MAX);
 	if (num_ifindex < 1) {
 		zlog_warn(
 			"%s %s: could not find nexthop ifindex for address %pPAs",
diff --git a/pimd/pim_zebra.c b/pimd/pim_zebra.c
index 4135ae0408..7f217d9c2e 100644
--- a/pimd/pim_zebra.c
+++ b/pimd/pim_zebra.c
@@ -452,6 +452,7 @@ static void pim_zebra_connected(struct zclient *zclient)
 static void pim_zebra_capabilities(struct zclient_capabilities *cap)
 {
 	router->mlag_role = cap->role;
+	router->multipath = cap->ecmp;
 }
 
 static zclient_handler *const pim_handlers[] = {
diff --git a/pimd/pim_zlookup.c b/pimd/pim_zlookup.c
index a3978bd0d2..28777e4947 100644
--- a/pimd/pim_zlookup.c
+++ b/pimd/pim_zlookup.c
@@ -211,7 +211,7 @@ static int zclient_read_nexthop(struct pim_instance *pim,
 	metric = stream_getl(s);
 	nexthop_num = stream_getc(s);
 
-	if (nexthop_num < 1) {
+	if (nexthop_num < 1 || nexthop_num > router->multipath) {
 		if (PIM_DEBUG_PIM_NHT_DETAIL)
 			zlog_debug("%s: socket %d bad nexthop_num=%d", __func__,
 				   zlookup->sock, nexthop_num);
diff --git a/pimd/pimd.c b/pimd/pimd.c
index 58e874fd11..a3be3f66e1 100644
--- a/pimd/pimd.c
+++ b/pimd/pimd.c
@@ -100,6 +100,7 @@ void pim_router_init(void)
 	router->debugs = 0;
 	router->master = frr_init();
 	router->t_periodic = PIM_DEFAULT_T_PERIODIC;
+	router->multipath = MULTIPATH_NUM;
 
 	/*
 	  RFC 4601: 4.6.3.  Assert Metrics