bgpd: Enforce self-next-hop check in next-hop update.

When BGP receives a connected route from Zebra, it processes the
routes for the next-hop update.
While doing so, BGP must ignore routes whose next-hop address matches
the address of the connected route for which Zebra sent the next-hop update
message.

Signed-off-by: NaveenThanikachalam <nthanikachal@vmware.com>

bgpd/bgp_nht.c

@@ -745,8 +745,16 @@ static void evaluate_paths(struct bgp_nexthop_cache *bnc)
 			bnc_is_valid_nexthop =
 				bgp_isvalid_labeled_nexthop(bnc) ? 1 : 0;
 		} else {
-			bnc_is_valid_nexthop =
-				bgp_isvalid_nexthop(bnc) ? 1 : 0;
+			if (bgp_update_martian_nexthop(bnc->bgp, afi, safi,
+						       path->type,
+						       path->sub_type,
+						       path->attr, rn)) {
+				zlog_debug("Prefix %pRN, ignoring path due to martian or self-next-hop",
+					   rn);
+			} else {
+				bnc_is_valid_nexthop =
+					bgp_isvalid_nexthop(bnc) ? 1 : 0;
+			}
 		}
 
 		if (BGP_DEBUG(nht, NHT))

bgpd/bgp_route.c

@@ -3226,9 +3226,9 @@ static bool overlay_index_equal(afi_t afi, struct bgp_path_info *path,
 }
 
 /* Check if received nexthop is valid or not. */
-static bool bgp_update_martian_nexthop(struct bgp *bgp, afi_t afi, safi_t safi,
-				       uint8_t type, uint8_t stype,
-				       struct attr *attr, struct bgp_node *rn)
+bool bgp_update_martian_nexthop(struct bgp *bgp, afi_t afi, safi_t safi,
+				uint8_t type, uint8_t stype, struct attr *attr,
+				struct bgp_node *rn)
 {
 	bool ret = 0;
 

bgpd/bgp_route.h

@@ -677,4 +677,7 @@ extern int bgp_show_table_rd(struct vty *vty, struct bgp *bgp, safi_t safi,
 			     enum bgp_show_type type, void *output_arg,
 			     bool use_json);
 extern int bgp_best_path_select_defer(struct bgp *bgp, afi_t afi, safi_t safi);
+extern bool bgp_update_martian_nexthop(struct bgp *bgp, afi_t afi, safi_t safi,
+				       uint8_t type, uint8_t stype,
+				       struct attr *attr, struct bgp_node *rn);
 #endif /* _QUAGGA_BGP_ROUTE_H */