Add ARP statistics to the kernel and netstat.

New counters now exist for:
requests sent
replies sent
requests received
replies received
packets received
total packets dropped due to no ARP entry
entrys timed out
Duplicate IPs seen

The new statistics are seen in the netstat command
when it is given the -s command line switch.

MFC after:	2 weeks
In collaboration with: bz

1 files changed, 26 insertions, 1 deletions

diff --git a/sys/net/if_arp.h b/sys/net/if_arp.h
index 1e18804..2bb6358 100644
--- a/sys/net/if_arp.h
+++ b/sys/net/if_arp.h
@@ -108,6 +108,31 @@ struct	arpcom {
 #define IFP2AC(ifp) ((struct arpcom *)(ifp->if_l2com))
 #define AC2IFP(ac) ((ac)->ac_ifp)
 
-#endif
+#endif /* _KERNEL */
+
+struct arpstat {
+	/* Normal things that happen: */
+	u_long txrequests;	/* # of ARP requests sent by this host. */
+	u_long txreplies;	/* # of ARP replies sent by this host. */
+	u_long rxrequests;	/* # of ARP requests received by this host. */
+	u_long rxreplies;	/* # of ARP replies received by this host. */
+	u_long received;	/* # of ARP packets received by this host. */
+
+	u_long arp_spares[4];	/* For either the upper or lower half. */
+	/* Abnormal event and error  counting: */
+	u_long dropped;		/* # of packets dropped waiting for a reply. */
+	u_long timeouts;	/* # of times with entries removed */
+				/* due to timeout. */
+	u_long dupips;		/* # of duplicate IPs detected. */
+};
+
+/*
+ * In-kernel consumers can use these accessor macros directly to update
+ * stats.
+ */
+#define	ARPSTAT_ADD(name, val)	V_arpstat.name += (val)
+#define	ARPSTAT_SUB(name, val)	V_arpstat.name -= (val)
+#define	ARPSTAT_INC(name)	ARPSTAT_ADD(name, 1)
+#define	ARPSTAT_DEC(name)	ARPSTAT_SUB(name, 1)
 
 #endif /* !_NET_IF_ARP_H_ */