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

2 files changed, 12 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;
diff --git a/sys/netinet/ip_carp.h b/sys/netinet/ip_carp.h
index 7be91c0..22b08b2 100644
--- a/sys/netinet/ip_carp.h
+++ b/sys/netinet/ip_carp.h
@@ -148,6 +148,7 @@ void		carp_carpdev_state(struct ifnet *);
 void		carp_input (struct mbuf *, int);
 int		carp6_input (struct mbuf **, int *, int);
 int		carp_output (struct ifnet *, struct mbuf *, struct sockaddr *);
+int		carp_master(struct ifaddr *);
 int		carp_iamatch(struct ifaddr *, uint8_t **);
 struct ifaddr	*carp_iamatch6(struct ifnet *, struct in6_addr *);
 caddr_t		carp_macmatch6(struct ifnet *, struct mbuf *, const struct in6_addr *);
@@ -160,6 +161,7 @@ extern int (*carp_attach_p)(struct ifaddr *, int);
 extern void (*carp_detach_p)(struct ifaddr *);
 extern void (*carp_linkstate_p)(struct ifnet *);
 extern void (*carp_demote_adj_p)(int, char *);
+extern int (*carp_master_p)(struct ifaddr *);
 /* net/if_bridge.c net/if_ethersubr.c */
 extern int (*carp_forus_p)(struct ifnet *, u_char *);
 /* net/if_ethersubr.c */