Use IFCAP_VLAN_MTU and IFCAP_VLAN_HWTAGGING capabilities:

LINK0 disappears; we now set IFCAP_VLAN_HWTAGGING at ifnet->if_capabilities
in the Ethernet driver for cards/drivers which support hardware tagging.

MTU ambiguity disppears; we now set IFCAP_VLAN_MTU in the Ethernet driver
when we know the chip will not truncate/discard vlan-sized frames.

Only allow the MTU to be changed within the scope of the parent interface's
MTU.  (Here we also take into account IFCAP_VLAN_MTU)

Propagate hardware-assisted IP/TCP/UDP checksumming flags to the vlan interface
if the card supports hardware tagging (from NetBSD)

1 files changed, 55 insertions, 27 deletions

diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index 5f7546803fa..53b1457c7b6 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_vlan.c,v 1.24 2001/06/27 06:07:46 kjc Exp $ */
+/*	$OpenBSD: if_vlan.c,v 1.25 2001/08/03 23:21:19 chris Exp $ */
 /*
  * Copyright 1998 Massachusetts Institute of Technology
  *
@@ -41,16 +41,10 @@
  * if_start(), rewrite them for use by the real outgoing interface,
  * and ask it to send them.
  *
- *
- * XXX It's incorrect to assume that we must always kludge up
- * headers on the physical device's behalf: some devices support
- * VLAN tag insersion and extraction in firmware. For these cases,
- * one can change the behavior of the vlan interface by setting
- * the LINK0 flag on it (that is setting the vlan interface's LINK0
- * flag, _not_ the parent's LINK0 flag; we try to leave the parent
- * alone). If the interface has the LINK0 flag set, then it will
- * not modify the ethernet header on output because the parent
- * can do that for itself. On input, the parent can call vlan_input_tag()
+ * Some devices support 802.1Q tag insertion and extraction in firmware.
+ * The vlan interface behavior changes when the IFCAP_VLAN_HWTAGGING
+ * capability is set on the parent.  In this case, vlan_start() will not
+ * modify the ethernet header.  On input, the parent can call vlan_input_tag()
  * directly in order to supply us with an incoming mbuf and the vlan
  * tag value that goes with it.
  */
@@ -230,9 +224,9 @@ vlan_start(struct ifnet *ifp)
 #endif
 
 		/*
-		 * If the LINK0 flag is set, it means the underlying interface
-		 * can do VLAN tag insertion itself and doesn't require us to
-	 	 * create a special header for it. In this case, we just pass
+		 * If the IFCAP_VLAN_HWTAGGING capability is set on the parent,
+		 * it can do VLAN tag insertion itself and doesn't require us
+	 	 * to create a special header for it. In this case, we just pass
 		 * the packet along. However, we need some way to tell the
 		 * interface where the packet came from so that it knows how
 		 * to find the VLAN tag to use, so we set the rcvif in the
@@ -247,7 +241,7 @@ vlan_start(struct ifnet *ifp)
 		 * following potentially bogus rcvif pointers off into
 		 * never-never land.
 		 */
-		if (ifp->if_flags & IFF_LINK0) {
+		if (p->if_capabilities & IFCAP_VLAN_HWTAGGING) {
 			m->m_pkthdr.rcvif = ifp;
 			m->m_flags |= M_PROTO1;
 		} else {
@@ -444,7 +438,22 @@ vlan_config(struct ifvlan *ifv, struct ifnet *p)
 	if (ifv->ifv_p)
 		return EBUSY;
 	ifv->ifv_p = p;
-	ifv->ifv_if.if_mtu = p->if_data.ifi_mtu;
+
+	if (p->if_capabilities & IFCAP_VLAN_MTU)
+		ifv->ifv_if.if_mtu = p->if_mtu;
+	else {
+		/*
+		 * This will be incompatible with strict
+		 * 802.1Q implementations
+		 */
+		ifv->ifv_if.if_mtu = p->if_mtu - EVL_ENCAPLEN;
+#ifdef DIAGNOSTIC
+		printf("%s: initialized with non-standard mtu %d (parent %s)\n",
+		    ifv->ifv_if.if_xname, ifv->ifv_if.if_mtu,
+		    ifv->ifv_p->if_xname);
+#endif
+	}
+
 	ifv->ifv_if.if_flags = p->if_flags &
 	    (IFF_UP | IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST);
 
@@ -455,6 +464,23 @@ vlan_config(struct ifvlan *ifv, struct ifnet *p)
 	ifv->ifv_if.if_type = p->if_type;
 
 	/*
+	 * If the parent interface can do hardware-assisted
+	 * VLAN encapsulation, then propagate its hardware-
+	 * assisted checksumming flags.
+	 *
+	 * If the card cannot handle hardware tagging, it cannot
+	 * possibly compute the correct checksums for tagged packets.
+	 *
+	 * This brings up another possibility, do cards exist which
+	 * have all of these capabilities but cannot utilize them together?
+	 */
+	if (p->if_capabilities & IFCAP_VLAN_HWTAGGING)
+		ifv->ifv_if.if_capabilities = p->if_capabilities &
+		    (IFCAP_CSUM_IPv4|IFCAP_CSUM_TCPv4|
+		    IFCAP_CSUM_UDPv4);
+		/* (IFCAP_CSUM_TCPv6|IFCAP_CSUM_UDPv6); */
+
+	/*
 	 * Set up our ``Ethernet address'' to reflect the underlying
 	 * physical interface's.
 	 */
@@ -549,7 +575,7 @@ vlan_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
 	struct ifreq *ifr;
 	struct ifvlan *ifv;
 	struct vlanreq vlr;
-	int error = 0;
+	int error = 0, p_mtu = 0;
 
 	ifr = (struct ifreq *)data;
 	ifa = (struct ifaddr *)data;
@@ -585,17 +611,19 @@ vlan_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
 		break;
 
 	case SIOCSIFMTU:
-		/*
-		 * XXX Set the interface MTU.
-		 * This is bogus. The underlying interface might support
-	 	 * jumbo frames.  It would be nice to replace ETHERMTU
-		 * with the parent interface's MTU in the following statement.
-		 */
-		if (ifr->ifr_mtu > ETHERMTU || ifr->ifr_mtu < ETHERMIN) {
+		if (ifv->ifv_p != NULL) {
+			if (ifv->ifv_p->if_capabilities & IFCAP_VLAN_MTU)
+				p_mtu = ifv->ifv_p->if_mtu;
+			else
+				p_mtu = ifv->ifv_p->if_mtu - EVL_ENCAPLEN;
+			
+			if (ifr->ifr_mtu > p_mtu || ifr->ifr_mtu < ETHERMIN)
+				error = EINVAL;
+			else
+				ifp->if_mtu = ifr->ifr_mtu;
+		} else
 			error = EINVAL;
-		} else {
-			ifp->if_mtu = ifr->ifr_mtu;
-		}
+
 		break;
 
 	case SIOCSETVLAN: