From: Donald Sharp <sharpd@cumulusnetworks.com>
Date: Mon, 9 Apr 2018 18:16:00 +0000 (-0400)
Subject: zebra: Only send down pertinent information on RTM_DELROUTE
X-Git-Tag: frr-4.0.1~13^2
X-Git-Url: https://git.puffer.fish/?a=commitdiff_plain;h=c8c34e5234a0aacf14b66256f888d3512abb8260;p=matthieu%2Ffrr.git

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 fbe2bbb815..3206ba7240 100644
--- 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) {