bgpd: fix sending ipv6 local nexthop if global present

bgpd keeps on advertising IPv6 prefixes with a IPv6 link-local nexthop
after a valid IPv6 global appears.

At bgpd startup, the IPv6 global is announced by zebra after the
link-local. Only the link-local is advertised. Clearing the BGP sessions
make the global to to be announced.

Update the nexthops with the global IPv6 when available.

Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>

diff --git a/bgpd/bgp_zebra.c b/bgpd/bgp_zebra.c
index 5977180ce5135f45f9329442a1edf36564210f80..5c0a6a09c3dfc787d9459a4c9a2ccc730d8e2478 100644 (file)
--- a/bgpd/bgp_zebra.c
+++ b/bgpd/bgp_zebra.c
@@ -303,11 +303,12 @@ static int bgp_ifp_down(struct interface *ifp)
 
 static int bgp_interface_address_add(ZAPI_CALLBACK_ARGS)
 {
-       struct connected *ifc;
+       struct connected *ifc, *connected;
        struct bgp *bgp;
        struct peer *peer;
        struct prefix *addr;
        struct listnode *node, *nnode;
+       bool v6_ll_in_nh_global;
        afi_t afi;
        safi_t safi;
 
@@ -342,6 +343,27 @@ static int bgp_interface_address_add(ZAPI_CALLBACK_ARGS)
                addr = ifc->address;
 
                for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer)) {
+                       v6_ll_in_nh_global = false;
+
+                       if (IN6_IS_ADDR_LINKLOCAL(&peer->nexthop.v6_global)) {
+                               frr_each (if_connected, ifc->ifp->connected,
+                                         connected) {
+                                       if (connected->address->family !=
+                                           AF_INET6)
+                                               continue;
+                                       if (!IPV6_ADDR_SAME(&connected->address
+                                                                    ->u.prefix6,
+                                                           &peer->nexthop
+                                                                    .v6_global))
+                                               continue;
+                                       /* peer->nexthop.v6_global contains a link-local address
+                                        * that needs to be replaced by the global address.
+                                        */
+                                       v6_ll_in_nh_global = true;
+                                       break;
+                               }
+                       }
+
                        /*
                         * If the Peer's interface name matches the
                         * interface name for which BGP received the
@@ -352,10 +374,11 @@ static int bgp_interface_address_add(ZAPI_CALLBACK_ARGS)
                         * into peer's v6_global and send updates out
                         * with new nexthop addr.
                         */
-                       if ((peer->conf_if &&
-                            (strcmp(peer->conf_if, ifc->ifp->name) == 0)) &&
-                           ((IS_MAPPED_IPV6(&peer->nexthop.v6_global)) ||
-                            IN6_IS_ADDR_LINKLOCAL(&peer->nexthop.v6_global))) {
+                       if (v6_ll_in_nh_global ||
+                           (peer->conf_if &&
+                            strcmp(peer->conf_if, ifc->ifp->name) == 0 &&
+                            (IS_MAPPED_IPV6(&peer->nexthop.v6_global) ||
+                             IN6_IS_ADDR_LINKLOCAL(&peer->nexthop.v6_global)))) {
                                if (bgp_debug_zebra(ifc->address)) {
                                        zlog_debug("Update peer %pBP's current intf global addr from %pI6 to %pI6 and send updates",
                                                   peer,