Re-add ifi_epoch, to struct if_data, this time replacing ifi_unused

to avoid ABI changes.  It is set to the last time the interface
counters were zeroed, currently the time if_attach() was called.  It is
intentended to be a valid value for RFC2233's ifCounterDiscontinuityTime
and to make it easier for applications to verify that the interface they
find at a given index is the one that was there last time they looked.

Due to space constraints ifi_epoch is a time_t rather then a struct
timeval.  SNMP would prefer higher precision, but this unlikely to be
useful in practice.

2 files changed, 5 insertions, 1 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index 1ba833e..7a84bf8 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -384,6 +384,7 @@ if_attach(struct ifnet *ifp)
 	TAILQ_INIT(&ifp->if_multiaddrs);
 	knlist_init(&ifp->if_klist, NULL);
 	getmicrotime(&ifp->if_lastchange);
+	ifp->if_data.ifi_epoch = time_second;
 
 #ifdef MAC
 	mac_init_ifnet(ifp);
diff --git a/sys/net/if.h b/sys/net/if.h
index 8b32fd1..77ffb1a 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -102,7 +102,10 @@ struct if_data {
 	u_long	ifi_iqdrops;		/* dropped on input, this interface */
 	u_long	ifi_noproto;		/* destined for unsupported protocol */
 	u_long	ifi_hwassist;		/* HW offload capabilities */
-	u_long	ifi_unused;		/* XXX was ifi_xmittiming */
+	time_t	ifi_epoch;		/* time of attach or stat reset */
+#ifdef __alpha__
+	u_int	ifi_timepad;		/* time_t is int, not long on alpha */
+#endif
 	struct	timeval ifi_lastchange;	/* time of last administrative change */
 };