Introduce attributes to interface groups.

As a first user, move the global carp(4) demotion counter
into the interface group. Thus we have the possibility
to define which carp interfaces are demoted together.

Put the demotion counter into the reserved field of the carp header.
With this, we can have carp act smarter if multiple errors occur.
It now always takes over other carp peers, that are advertising
with a higher demote count.  As a side effect, we can also have
group failovers without the need of running in preempt mode.
The protocol change does not break compability with older
implementations.

Collaborative work with mcbride@

OK mcbride@, henning@

1 files changed, 10 insertions, 3 deletions

diff --git a/sys/net/if.h b/sys/net/if.h
index cef94421001..2e54ccd76ad 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if.h,v 1.81 2006/05/27 10:03:15 brad Exp $	*/
+/*	$OpenBSD: if.h,v 1.82 2006/06/02 19:53:12 mpf Exp $	*/
 /*	$NetBSD: if.h,v 1.23 1996/05/07 02:40:27 thorpej Exp $	*/
 
 /*
@@ -433,6 +433,7 @@ struct ifg_group {
 	char				 ifg_group[IFNAMSIZ];
 	u_int				 ifg_refcnt;
 	caddr_t				 ifg_pf_kif;
+	int				 ifg_carp_demoted;
 	TAILQ_HEAD(, ifg_member)	 ifg_members;
 	TAILQ_ENTRY(ifg_group)		 ifg_next;
 };
@@ -456,6 +457,10 @@ struct ifg_req {
 #define	ifgrq_member	ifgrq_ifgrqu.ifgrqu_member
 };
 
+struct ifg_attrib {
+	int	ifg_carp_demoted;
+};
+
 /*
  * Used to lookup groups for an interface
  */
@@ -463,11 +468,13 @@ struct ifgroupreq {
 	char	ifgr_name[IFNAMSIZ];
 	u_int	ifgr_len;
 	union {
-		char	ifgru_group[IFNAMSIZ];
-		struct	ifg_req *ifgru_groups;
+		char			 ifgru_group[IFNAMSIZ];
+		struct	ifg_req		*ifgru_groups;
+		struct	ifg_attrib	 ifgru_attrib;
 	} ifgr_ifgru;
 #define ifgr_group	ifgr_ifgru.ifgru_group
 #define ifgr_groups	ifgr_ifgru.ifgru_groups
+#define ifgr_attrib	ifgr_ifgru.ifgru_attrib
 };
 
 /*