zebra: Properly note that a nhg's nexthop has gone down

tests/topotests/isis_tilfa_topo1/rt5/step10/show_ip_route.ref

@@ -457,8 +457,7 @@
           "fib":true,
           "ip":"10.0.8.6",
           "afi":"ipv4",
-          "interfaceName":"eth-rt6",
-          "active":true
+          "interfaceName":"eth-rt6"
         }
       ]
     }

zebra/zebra_nhg.c

@@ -1050,15 +1050,41 @@ static void zebra_nhg_set_valid(struct nhg_hash_entry *nhe, bool valid)
 	}
 
 	/* Update validity of nexthops depending on it */
-	frr_each(nhg_connected_tree, &nhe->nhg_dependents, rb_node_dep)
+	frr_each (nhg_connected_tree, &nhe->nhg_dependents, rb_node_dep) {
+		if (!valid) {
+			/*
+			 * Grab the first nexthop from the depending nexthop group
+			 * then let's find the nexthop in that group that matches
+			 * my individual nexthop and mark it as no longer ACTIVE
+			 */
+			struct nexthop *nexthop = rb_node_dep->nhe->nhg.nexthop;
+
+			while (nexthop) {
+				if (nexthop_same(nexthop, nhe->nhg.nexthop))
+					break;
+
+				nexthop = nexthop->next;
+			}
+
+			if (nexthop)
+				UNSET_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
+		}
 		zebra_nhg_set_valid(rb_node_dep->nhe, valid);
+	}
 }
 
 void zebra_nhg_check_valid(struct nhg_hash_entry *nhe)
 {
 	struct nhg_connected *rb_node_dep = NULL;
 	bool valid = false;
 
+	/*
+	 * If I have other nhe's depending on me, then this is a
+	 * singleton nhe so set this nexthops flag as appropriate.
+	 */
+	if (nhg_connected_tree_count(&nhe->nhg_depends))
+		UNSET_FLAG(nhe->nhg.nexthop->flags, NEXTHOP_FLAG_ACTIVE);
+
 	/* If anthing else in the group is valid, the group is valid */
 	frr_each(nhg_connected_tree, &nhe->nhg_depends, rb_node_dep) {
 		if (CHECK_FLAG(rb_node_dep->nhe->flags, NEXTHOP_GROUP_VALID)) {

zebra/zebra_vty.c

@@ -215,7 +215,7 @@ static char re_status_output_char(const struct route_entry *re,
 			if (is_fib) {
 				star_p = !!CHECK_FLAG(nhop->flags,
 						      NEXTHOP_FLAG_FIB);
-			} else
+			} else if (CHECK_FLAG(nhop->flags, NEXTHOP_FLAG_ACTIVE))
 				star_p = true;
 		}