add some helpers for working with ethernet addresses as uint64_t

the main bits are ether_addr_to_e64 and ether_e64_to addr for loading
an ethernet address into a uin64_t and visa versa. there's also
some macros for testing if an address in a uint64_t is multicast,
broadcast, anyaddr, or if it's an 802.1q reserved multicast group
address.

the reason for this functionality is once you have an ethernet
address as a uint64_t, operations like compares, bit tests, and
so on are fast and easy.

tested on amd64 and sparc64

2 files changed, 48 insertions, 2 deletions

diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index 47d74957fdf..aeee969f26a 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_ethersubr.c,v 1.270 2021/02/06 13:15:37 bluhm Exp $	*/
+/*	$OpenBSD: if_ethersubr.c,v 1.271 2021/02/26 01:12:37 dlg Exp $	*/
 /*	$NetBSD: if_ethersubr.c,v 1.19 1996/05/07 02:40:30 thorpej Exp $	*/
 
 /*
@@ -996,3 +996,28 @@ ether_delmulti(struct ifreq *ifr, struct arpcom *ac)
 	 */
 	return (ENETRESET);
 }
+
+uint64_t
+ether_addr_to_e64(const struct ether_addr *ea)
+{
+	uint64_t e64 = 0;
+	size_t i;
+
+	for (i = 0; i < nitems(ea->ether_addr_octet); i++) {
+		e64 <<= 8;
+		e64 |= ea->ether_addr_octet[i];
+	}
+
+	return (e64);
+}
+
+void
+ether_e64_to_addr(struct ether_addr *ea, uint64_t e64)
+{
+	size_t i = nitems(ea->ether_addr_octet);
+
+	do {
+		ea->ether_addr_octet[--i] = e64;
+		e64 >>= 8;
+	} while (i > 0);
+}
diff --git a/sys/netinet/if_ether.h b/sys/netinet/if_ether.h
index 8ae1f2b3bce..04d92124df6 100644
--- a/sys/netinet/if_ether.h
+++ b/sys/netinet/if_ether.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_ether.h,v 1.78 2020/07/22 02:16:02 dlg Exp $	*/
+/*	$OpenBSD: if_ether.h,v 1.79 2021/02/26 01:12:37 dlg Exp $	*/
 /*	$NetBSD: if_ether.h,v 1.22 1996/05/11 13:00:00 mycroft Exp $	*/
 
 /*
@@ -116,6 +116,24 @@ struct  ether_vlan_header {
 	  (addr)[3] | (addr)[4] | (addr)[5]) == 0x00)
 #define	ETHER_IS_EQ(a1, a2)	(memcmp((a1), (a2), ETHER_ADDR_LEN) == 0)
 
+/*
+ * It can be faster to work with ethernet addresses as a uint64_t.
+ * Provide some constants and functionality centrally to better
+ * support this.
+ */
+
+#define ETH64_IS_MULTICAST(_e64)	((_e64) & 0x010000000000ULL)
+#define ETH64_IS_BROADCAST(_e64)	((_e64) == 0xffffffffffffULL)
+#define ETH64_IS_ANYADDR(_e64)		((_e64) == 0x000000000000ULL)
+
+#define ETH64_8021_RSVD_PREFIX		0x0180c2000000ULL
+#define ETH64_8021_RSVD_MASK		0xfffffffffff0ULL
+#define ETH64_IS_8021_RSVD(_e64)	\
+    (((_e64) & ETH64_8021_RSVD_MASK) == ETH64_8021_RSVD_PREFIX)
+
+/*
+ * Ethernet MTU constants.
+ */
 #define	ETHERMTU	(ETHER_MAX_LEN - ETHER_HDR_LEN - ETHER_CRC_LEN)
 #define	ETHERMIN	(ETHER_MIN_LEN - ETHER_HDR_LEN - ETHER_CRC_LEN)
 
@@ -272,6 +290,9 @@ const struct ether_brport *
 const struct ether_brport *
 	ether_brport_get_locked(struct ifnet *);
 
+uint64_t	ether_addr_to_e64(const struct ether_addr *);
+void		ether_e64_to_addr(struct ether_addr *, uint64_t);
+
 /*
  * Ethernet multicast address structure.  There is one of these for each
  * multicast address or range of multicast addresses that we are supposed