bgpd: Make bgp ready to remove distinction between 2 nh tracking types

Allow bgp to figure out if it cares about address resolution instead
of having zebra care about it.  This will allow the removal of the
zapi type for import checking and just use nexthop resolution.

Effectively we just look up the route being returned and
if it is in either table we just handle it instead of
looking for clues from the zapi message type.

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

bgpd/bgp_nht.c

@@ -664,7 +664,7 @@ void bgp_nht_interface_events(struct peer *peer)
 void bgp_parse_nexthop_update(int command, vrf_id_t vrf_id)
 {
 	struct bgp_nexthop_cache_head *tree = NULL;
-	struct bgp_nexthop_cache *bnc;
+	struct bgp_nexthop_cache *bnc_nhc, *bnc_import;
 	struct bgp *bgp;
 	struct zapi_route nhr;
 	afi_t afi;
@@ -685,22 +685,38 @@ void bgp_parse_nexthop_update(int command, vrf_id_t vrf_id)
 	}
 
 	afi = family2afi(nhr.prefix.family);
-	if (command == ZEBRA_NEXTHOP_UPDATE)
-		tree = &bgp->nexthop_cache_table[afi];
-	else if (command == ZEBRA_IMPORT_CHECK_UPDATE)
-		tree = &bgp->import_check_table[afi];
+	tree = &bgp->nexthop_cache_table[afi];
 
-	bnc = bnc_find(tree, &nhr.prefix, nhr.srte_color);
-	if (!bnc) {
+	bnc_nhc = bnc_find(tree, &nhr.prefix, nhr.srte_color);
+	if (!bnc_nhc) {
 		if (BGP_DEBUG(nht, NHT))
 			zlog_debug(
-				"parse nexthop update(%pFX(%u)(%s)): bnc info not found",
+				"parse nexthop update(%pFX(%u)(%s)): bnc info not found for nexthop cache",
+				&nhr.prefix, nhr.srte_color, bgp->name_pretty);
+	} else
+		bgp_process_nexthop_update(bnc_nhc, &nhr);
+
+	tree = &bgp->import_check_table[afi];
+
+	bnc_import = bnc_find(tree, &nhr.prefix, nhr.srte_color);
+	if (!bnc_import) {
+		if (BGP_DEBUG(nht, NHT))
+			zlog_debug(
+				"parse nexthop update(%pFX(%u)(%s)): bnc info not found for import check",
 				&nhr.prefix, nhr.srte_color, bgp->name_pretty);
 		return;
+	} else {
+		if (nhr.type == ZEBRA_ROUTE_BGP
+		    || !prefix_same(&bnc_import->prefix, &nhr.prefix)) {
+			if (BGP_DEBUG(nht, NHT))
+				zlog_debug(
+					"%s: Import Check does not resolve to the same prefix for %pFX received %pFX",
+					__func__, &bnc_import->prefix, &nhr.prefix);
+			return;
+		}
+		bgp_process_nexthop_update(bnc_import, &nhr);
 	}
 
-	bgp_process_nexthop_update(bnc, &nhr);
-
 	/*
 	 * HACK: if any BGP route is dependant on an SR-policy that doesn't
 	 * exist, zebra will never send NH updates relative to that policy. In
@@ -712,12 +728,12 @@ void bgp_parse_nexthop_update(int command, vrf_id_t vrf_id)
 	 * which should provide a better infrastructure to solve this issue in
 	 * a more efficient and elegant way.
 	 */
-	if (nhr.srte_color == 0) {
+	if (nhr.srte_color == 0 && bnc_nhc) {
 		struct bgp_nexthop_cache *bnc_iter;
 
 		frr_each (bgp_nexthop_cache, &bgp->nexthop_cache_table[afi],
 			  bnc_iter) {
-			if (!prefix_same(&bnc->prefix, &bnc_iter->prefix)
+			if (!prefix_same(&bnc_import->prefix, &bnc_iter->prefix)
 			    || bnc_iter->srte_color == 0
 			    || CHECK_FLAG(bnc_iter->flags, BGP_NEXTHOP_VALID))
 				continue;