While looking into filtering out messages for L2 routes in the kernel to reduce
load on routing daemons, I noticed that the RTM_DELETE messages do not have
the RTF_LLINFO flag set, which is inconvenient because that's what I want to
filter on.
I tracked this down to r1.361 and r1.362 of net/route.c, where we stopped
saving rt->rt_flags before calling rtrequest_delete(). rtrequest_delete()
calls ifp->if_rtrequest(), which removes the llinfo from the route and clears
RTF_LLINFO.
I think the simplest way to fix this would be for rtdeletemsg() to go back to
calling rtm_miss() directly rather than using rtm_send(). Adding more
parameters to rtm_send() to specify additional flags seems like
overcomplicating it.
Index: route.c
===================================================================
RCS file: /cvs/src/sys/net/route.c,v
retrieving revision 1.394
diff -u -p -r1.394 route.c
--- route.c 24 Jun 2020 22:03:43 -0000 1.394
+++ route.c 11 Aug 2020 04:12:51 -0000
@@ -663,6 +663,7 @@ rtdeletemsg(struct rtentry *rt, struct i
{
int error;
struct rt_addrinfo info;
+ struct sockaddr_rtlabel sa_rl;
struct sockaddr_in6 sa_mask;
KASSERT(rt->rt_ifidx == ifp->if_index);
@@ -677,8 +678,13 @@ rtdeletemsg(struct rtentry *rt, struct i
info.rti_info[RTAX_GATEWAY] = rt->rt_gateway;
if (!ISSET(rt->rt_flags, RTF_HOST))
info.rti_info[RTAX_NETMASK] = rt_plen2mask(rt, &sa_mask);
+ info.rti_info[RTAX_LABEL] = rtlabel_id2sa(rt->rt_labelid, &sa_rl);
+ info.rti_flags = rt->rt_flags;
+ info.rti_info[RTAX_IFP] = sdltosa(ifp->if_sadl);
+ info.rti_info[RTAX_IFA] = rt->rt_ifa->ifa_addr;
error = rtrequest_delete(&info, rt->rt_priority, ifp, &rt, tableid);
- rtm_send(rt, RTM_DELETE, error, tableid);
+ rtm_miss(RTM_DELETE, &info, info.rti_flags, rt->rt_priority,
+ rt->rt_ifidx, error, tableid);
if (error == 0)
rtfree(rt);
return (error);
