In complemence to ifa_add_loopback_route() and ifa_del_loopback_route()

provide function ifa_switch_loopback_route() that will be used in case when
an interface address used for a loopback route goes away, but we have another
interface address with same address value and want to preserve loopback
route.

Sponsored by:	Netflix
Sponsored by:	Nginx, Inc.

2 files changed, 20 insertions, 0 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index 17c36d1..9383b63 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -1525,6 +1525,25 @@ ifa_del_loopback_route(struct ifaddr *ifa, struct sockaddr *ia)
 	return (error);
 }
 
+int
+ifa_switch_loopback_route(struct ifaddr *ifa, struct sockaddr *sa)
+{
+	struct rtentry *rt;
+
+	rt = rtalloc1_fib(sa, 0, 0, 0);
+	if (rt == NULL) {
+		log(LOG_DEBUG, "%s: fail", __func__);
+		return (EHOSTUNREACH);
+	}
+	((struct sockaddr_dl *)rt->rt_gateway)->sdl_type =
+	    ifa->ifa_ifp->if_type;
+	((struct sockaddr_dl *)rt->rt_gateway)->sdl_index =
+	    ifa->ifa_ifp->if_index;
+	RTFREE_LOCKED(rt);
+
+	return (0);
+}
+
 /*
  * XXX: Because sockaddr_dl has deeper structure than the sockaddr
  * structs used to represent other address families, it is necessary
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
index 22ccbd9..26163ad 100644
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -502,6 +502,7 @@ struct	ifnet *ifunit_ref(const char *);
 
 int	ifa_add_loopback_route(struct ifaddr *, struct sockaddr *);
 int	ifa_del_loopback_route(struct ifaddr *, struct sockaddr *);
+int	ifa_switch_loopback_route(struct ifaddr *, struct sockaddr *);
 
 struct	ifaddr *ifa_ifwithaddr(struct sockaddr *);
 int		ifa_ifwithaddr_check(struct sockaddr *);