Resolve source address selection in presense of CARP. Add a couple

of helper functions:

- carp_master()   - boolean function which is true if an address
		    is in the MASTER state.
- ifa_preferred() - boolean function that compares two addresses,
		    and is aware of CARP.

  Utilize ifa_preferred() in ifa_ifwithnet().

  The previous version of patch also changed source address selection
logic in jails using carp_master(), but we failed to negotiate this part
with Bjoern. May be we will approach this problem again later.

Reported & tested by:	Anton Yuzhaninov <citrin citrin.ru>
Sponsored by:		Nginx, Inc

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/netinet/ip_carp.c b/sys/netinet/ip_carp.c
index ac6b043..ae3da96 100644
--- a/sys/netinet/ip_carp.c
+++ b/sys/netinet/ip_carp.c
@@ -969,6 +969,14 @@ carp_ifa_delroute(struct ifaddr *ifa)
 	}
 }
 
+int
+carp_master(struct ifaddr *ifa)
+{
+	struct carp_softc *sc = ifa->ifa_carp;
+
+	return (sc->sc_state == MASTER);
+}
+
 #ifdef INET
 /*
  * Broadcast a gratuitous ARP request containing
@@ -2072,6 +2080,7 @@ carp_mod_cleanup(void)
 	carp_forus_p = NULL;
 	carp_output_p = NULL;
 	carp_demote_adj_p = NULL;
+	carp_master_p = NULL;
 	mtx_unlock(&carp_mtx);
 	taskqueue_drain(taskqueue_swi, &carp_sendall_task);
 	mtx_destroy(&carp_mtx);
@@ -2092,6 +2101,7 @@ carp_mod_load(void)
 	carp_attach_p = carp_attach;
 	carp_detach_p = carp_detach;
 	carp_demote_adj_p = carp_demote_adj;
+	carp_master_p = carp_master;
 #ifdef INET6
 	carp_iamatch6_p = carp_iamatch6;
 	carp_macmatch6_p = carp_macmatch6;