zebra: Only send down pertinent information on RTM_DELROUTE

Background:

v6 does not have route replace semantics.  If you want to add a nexthop
to an existing route, you just send RTM_NEWROUTE and the new nexthop.
If you want to delete a nexthop you should just send RTM_DELROUTE
with the removed nexthop.

This leads to situations where if zebra is processing a route
and has lost track of intermediate nexthops( yes this sucks )
then v6 routes will get out of sync when we try to implement
route replace semantics.

So notice when we are doing a route delete and the route is
not being updated, just send the prefix and tell it too delete.

Ticket: CM-20391
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

diff --git a/zebra/rt_netlink.c b/zebra/rt_netlink.c
index fbe2bbb815336b44d20b58658f86c3e21ffdbcde..3206ba724089423f01707e42767794434507c579 100644 (file)
--- a/zebra/rt_netlink.c
+++ b/zebra/rt_netlink.c
@@ -1305,7 +1305,6 @@ static int netlink_route_multipath(int cmd, struct prefix *p,
        struct sockaddr_nl snl;
        struct nexthop *nexthop = NULL;
        unsigned int nexthop_num;
-       int discard = 0;
        int family = PREFIX_FAMILY(p);
        const char *routedesc;
        int setsrc = 0;
@@ -1373,7 +1372,13 @@ static int netlink_route_multipath(int cmd, struct prefix *p,
                addattr32(&req.n, sizeof req, RTA_TABLE, re->table);
        }
 
-       if (discard)
+       /*
+        * If we are not updating the route and we have received
+        * a route delete, then all we need to fill in is the
+        * prefix information to tell the kernel to schwack
+        * it.
+        */
+       if (!update && cmd == RTM_DELROUTE)
                goto skip;
 
        if (re->mtu || re->nexthop_mtu) {