zebra: Store received NHG from upper level protocol

Upper level protocols are sending down a list of nexthops
that a temporary nhg was created to hold it.  After
route resolution is done, this NHG is thrown away.
Let's keep this received NHG as a pointer off the RE.

Follow the `installedNexthopGroupId` pattern for display
purposes at this point in time.

Signed-off-by: Donald Sharp <[email protected]>

Author: donaldsharp

zebra/rib.h

@@ -85,6 +85,8 @@ struct route_entry {
 	 */
 	struct nhg_hash_entry *nhe;
 
+	struct nhg_hash_entry *nhe_received;
+
 	/*
 	 * Nexthop group hash entry IDs.
 	 * Since the nhe_id is used as a temporary holder

zebra/zebra_rib.c

@@ -474,6 +474,12 @@ static void route_entry_attach_ref(struct route_entry *re,
 	zebra_nhg_increment_ref(new);
 }
 
+static void route_entry_update_original_nhe(struct route_entry *re, struct nhg_hash_entry *nhe)
+{
+	re->nhe_received = nhe;
+	zebra_nhg_increment_ref(nhe);
+}
+
 /* Replace (if 'new_nhghe') or clear (if that's NULL) an re's nhe. */
 int route_entry_update_nhe(struct route_entry *re,
 			   struct nhg_hash_entry *new_nhghe)
@@ -503,6 +509,14 @@ int route_entry_update_nhe(struct route_entry *re,
 	/* Detach / deref previous nhg */
 
 	if (old_nhg) {
+		if (re->nhe_received == old_nhg) {
+			zebra_nhg_decrement_ref(old_nhg);
+		}
+		if (new_nhghe)
+			zebra_nhg_increment_ref(new_nhghe);
+
+		re->nhe_received = new_nhghe;
+
 		/*
 		 * Return true if we are deleting the previous NHE
 		 * Note: we dont check the return value of the function anywhere
@@ -2703,6 +2717,11 @@ static void rib_re_nhg_free(struct route_entry *re)
 		nexthops_free(re->nhe->nhg.nexthop);
 
 	nexthops_free(re->fib_ng.nexthop);
+
+	if (re->nhe_received) {
+		zebra_nhg_decrement_ref(re->nhe_received);
+		re->nhe_received = NULL;
+	}
 }
 
 struct zebra_early_route {
@@ -2813,6 +2832,7 @@ static void process_subq_early_route_add(struct zebra_early_route *ere)
 	 * if old_id != new_id.
 	 */
 	route_entry_update_nhe(re, nhe);
+	route_entry_update_original_nhe(re, nhe);
 
 	/* Make it sure prefixlen is applied to the prefix. */
 	apply_mask(&ere->p);

zebra/zebra_vty.c

@@ -477,6 +477,10 @@ static void vty_show_ip_route_detail(struct vty *vty, struct route_node *rn,
 				vty_out(vty,
 					"  Installed Nexthop Group ID: %u\n",
 					re->nhe_installed_id);
+
+			if (re->nhe_received)
+				vty_out(vty, "  Received Nexthop Group ID: %u\n",
+					re->nhe_received->id);
 		}
 
 		for (ALL_NEXTHOPS(re->nhe->nhg, nexthop)) {
@@ -589,6 +593,9 @@ static void vty_show_ip_route(struct vty *vty, struct route_node *rn,
 			json_object_int_add(json_route,
 					    "installedNexthopGroupId",
 					    re->nhe_installed_id);
+		if (re->nhe_received)
+			json_object_int_add(json_route, "receivedNexthopGroupId",
+					    re->nhe_received->id);
 
 		json_object_string_add(json_route, "uptime", up_str);