bgpd: split nexthop-local unchanged peer subgroup

5bb99cc ("bgpd: reset ipv6 invalid link-local nexthop") now resets
the link-local when originating and destination peers are not on the
same network segment. However, it does not work all the time.

The fix compares the 'from' and 'peer' global IPv6 address. However,
'peer' refers to one of the peers of subgroup. The subgroup may contain
peers located on different network segment.

Split nexthop-local unchanged peer subgroup by network segment.

Fixes: 5bb99cc ("bgpd: reset ipv6 invalid link-local nexthop")
Signed-off-by: Louis Scalbert <[email protected]>

bgpd/bgp_updgrp.c

@@ -455,6 +455,10 @@ static unsigned int updgrp_hash_key_make(const void *p)
 		key = jhash_1word(jhash(soo_str, strlen(soo_str), SEED1), key);
 	}
 
+	if (afi == AFI_IP6 &&
+	    (CHECK_FLAG(peer->af_flags[afi][safi], PEER_FLAG_NEXTHOP_LOCAL_UNCHANGED)))
+		key = jhash(&peer->nexthop.v6_global, IPV6_MAX_BYTELEN, key);
+
 	/*
 	 * ANY NEW ITEMS THAT ARE ADDED TO THE key, ENSURE DEBUG
 	 * STATEMENT STAYS UP TO DATE
@@ -521,6 +525,12 @@ static unsigned int updgrp_hash_key_make(const void *p)
 			peer->soo[afi][safi]
 				? ecommunity_str(peer->soo[afi][safi])
 				: "(NONE)");
+		zlog_debug("%pBP Update Group Hash: IPv6 nexthop-local unchanged: %d IPv6 global %pI6",
+			   peer,
+			   afi == AFI_IP6 && (CHECK_FLAG(peer->af_flags[afi][safi],
+							 PEER_FLAG_NEXTHOP_LOCAL_UNCHANGED)),
+			   &peer->nexthop.v6_global);
+
 		zlog_debug("%pBP Update Group Hash key: %u", peer, key);
 	}
 	return key;
@@ -655,6 +665,12 @@ static bool updgrp_hash_cmp(const void *p1, const void *p2)
 	    !sockunion_same(&pe1->connection->su, &pe2->connection->su))
 		return false;
 
+	if (afi == AFI_IP6 &&
+	    (CHECK_FLAG(flags1, PEER_FLAG_NEXTHOP_LOCAL_UNCHANGED) ||
+	     CHECK_FLAG(flags2, PEER_FLAG_NEXTHOP_LOCAL_UNCHANGED)) &&
+	    !IPV6_ADDR_SAME(&pe1->nexthop.v6_global, &pe2->nexthop.v6_global))
+		return false;
+
 	return true;
 }