Remove the concept of the media-independent link-layer header and replace

it with metadata in the pkb structure.  This is required since UNDI will
want to be able to parse the link-layer header without destroying it.

src/net/arp.c

@@ -23,7 +23,6 @@
 #include <gpxe/if_ether.h>
 #include <gpxe/if_arp.h>
 #include <gpxe/pkbuff.h>
-#include <gpxe/llh.h>
 #include <gpxe/netdevice.h>
 #include <gpxe/arp.h>
 
@@ -91,45 +90,43 @@ arp_find_entry ( uint16_t ll_proto, uint16_t net_proto, const void *net_addr,
  *
  * @v netdev		Network device
  * @v pkb		Packet buffer
- * @v ll_addr		Buffer to contain link-layer address
+ * @ret ll_addr		Pointer to link-layer address
  * @ret rc		Return status code
  *
- * The packet buffer must start with a media-independent link-layer
- * header (a struct @c gpxehdr).  This function will use the ARP cache
- * to look up the link-layer address for the media corresponding to
- * @c netdev and the network-layer address as specified in @c gpxehdr.
+ * This function will use the ARP cache to look up the link-layer
+ * address for the media corresponding to @c netdev and the
+ * network-layer address as specified in the @c pkb metadata.
  *
  * If no address is found in the ARP cache, an ARP request will be
  * transmitted, -ENOENT will be returned, and the packet buffer
  * contents will be undefined.
  */
 int arp_resolve ( struct net_device *netdev, struct pk_buff *pkb,
-		  void *ll_addr ) {
-	struct gpxehdr *gpxehdr = pkb->data;
+		  const void **ll_addr ) {
 	const struct arp_entry *arp;
 	struct net_interface *netif;
 	struct arphdr *arphdr;
 
 	/* Look for existing entry in ARP table */
-	arp = arp_find_entry ( netdev->ll_proto, gpxehdr->net_proto,
-			       gpxehdr->net_addr, gpxehdr->net_addr_len );
+	arp = arp_find_entry ( netdev->ll_proto, pkb->net_proto,
+			       pkb->net_addr, pkb->net_addr_len );
 	if ( arp ) {
-		memcpy ( ll_addr, arp->ll_addr, netdev->ll_addr_len );
+		*ll_addr = arp->ll_addr;
 		return 0;
 	}
 
 	/* Find interface for this protocol */
-	netif = netdev_find_netif ( netdev, gpxehdr->net_proto );
+	netif = netdev_find_netif ( netdev, pkb->net_proto );
 	if ( ! netif )
 		return -EAFNOSUPPORT;
 
 	/* Build up ARP request */
-	pkb_unput ( pkb, pkb_len ( pkb ) - sizeof ( *gpxehdr ) );
+	pkb_empty ( pkb );
 	arphdr = pkb_put ( pkb, sizeof ( *arphdr ) );
 	arphdr->ar_hrd = netdev->ll_proto;
 	arphdr->ar_hln = netdev->ll_addr_len;
-	arphdr->ar_pro = gpxehdr->net_proto;
-	arphdr->ar_pln = gpxehdr->net_addr_len;
+	arphdr->ar_pro = pkb->net_proto;
+	arphdr->ar_pln = pkb->net_addr_len;
 	arphdr->ar_op = htons ( ARPOP_REQUEST );
 	memcpy ( pkb_put ( pkb, netdev->ll_addr_len ),
 		 netdev->ll_addr, netdev->ll_addr_len );
@@ -138,8 +135,7 @@ int arp_resolve ( struct net_device *netdev, struct pk_buff *pkb,
 	memset ( pkb_put ( pkb, netdev->ll_addr_len ),
 		 0xff, netdev->ll_addr_len );
 	memcpy ( pkb_put ( pkb, netif->net_addr_len ),
-		 gpxehdr->net_addr, netif->net_addr_len );
-	pkb_pull ( pkb, sizeof ( *gpxehdr ) );
+		 pkb->net_addr, netif->net_addr_len );
 
 	/* Locate ARP interface and send ARP request */
 	netif = netdev_find_netif ( netdev, htons ( ETH_P_ARP ) );
@@ -228,17 +224,14 @@ int arp_process ( struct net_interface *arp_netif, struct pk_buff *pkb ) {
  * @v pkb		Packet buffer
  * @ret rc		Return status code
  */
-int arp_add_generic_header ( struct net_interface *arp_netif __unused,
-			     struct pk_buff *pkb ) {
+int arp_add_llh_metadata ( struct net_interface *arp_netif __unused,
+			   struct pk_buff *pkb ) {
 	struct arphdr *arphdr = pkb->data;
-	struct gpxehdr *gpxehdr;
 
-	/* We're ARP; we always know the raw link-layer address we want */
-	gpxehdr = pkb_push ( pkb, sizeof ( *gpxehdr ) );
-	gpxehdr->net_proto = htons ( ETH_P_ARP );
-	gpxehdr->flags = GPXE_FL_RAW;
-	gpxehdr->net_addr_len = arphdr->ar_hln;
-	memcpy ( gpxehdr->net_addr, arp_target_ha ( arphdr ), arphdr->ar_hln );
+	pkb->net_proto = htons ( ETH_P_ARP );
+	pkb->flags = PKB_FL_RAW_NET_ADDR;
+	pkb->net_addr_len = arphdr->ar_hln;
+	pkb->net_addr = arp_target_ha ( arphdr );
 	
 	return 0;
 }

src/net/ethernet.c

@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include <byteswap.h>
+#include <assert.h>
+#include <gpxe/if_ether.h>
+#include <gpxe/netdevice.h>
+#include <gpxe/pkbuff.h>
+#include <gpxe/arp.h>
+
+/** @file
+ *
+ * Ethernet protocol
+ *
+ */
+
+/** Ethernet broadcast MAC address */
+static uint8_t eth_broadcast[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
+
+/**
+ * Build Ethernet link-layer header
+ *
+ * @v netdev	Network device
+ * @v pkb	Packet buffer
+ * @ret rc	Return status code
+ *
+ * This constructs the Ethernet link-layer header (destination MAC,
+ * source MAC, network-layer protocol) based on the metadata found in
+ * @c pkb.
+ *
+ * If the destination MAC address cannot be determined, an ARP request
+ * is sent for the requested network-layer address instead.
+ */
+int eth_build_llh ( struct net_device *netdev, struct pk_buff *pkb ) {
+	struct ethhdr *ethhdr = pkb->data;
+	const void *eth_dest;
+	int rc;
+
+	/* Do the easy bits */
+	ethhdr->h_protocol = pkb->net_proto;
+	memcpy ( ethhdr->h_source, netdev->ll_addr,
+		 sizeof ( ethhdr->h_source ) );
+
+	/* Work out the destination MAC address */
+	if ( pkb->flags & PKB_FL_RAW_NET_ADDR ) {
+		eth_dest = pkb->net_addr;
+	} else if ( pkb->flags & PKB_FL_BROADCAST ) {
+		eth_dest = eth_broadcast;
+	} else if ( pkb->flags & PKB_FL_MULTICAST ) {
+		/* IP multicast is a special case; there exists a
+		 * direct mapping from IP address to MAC address
+		 */
+		assert ( pkb->net_proto == htons ( ETH_P_IP ) );
+		ethhdr->h_dest[0] = 0x01;
+		ethhdr->h_dest[1] = 0x00;
+		ethhdr->h_dest[2] = 0x5e;
+		ethhdr->h_dest[3] = *( ( char * ) pkb->net_addr + 1 ) & 0x7f;
+		ethhdr->h_dest[4] = *( ( char * ) pkb->net_addr + 2 );
+		ethhdr->h_dest[5] = *( ( char * ) pkb->net_addr + 3 );
+		eth_dest = ethhdr->h_dest;
+	} else {
+		/* Otherwise, look up the address using ARP */
+		if ( ( rc = arp_resolve ( netdev, pkb, &eth_dest ) ) != 0 )
+			return rc;
+	}
+
+	/* Fill in destination MAC address */
+	memcpy ( ethhdr->h_dest, eth_dest, sizeof ( ethhdr->h_dest ) );
+
+	return 0;
+}
+
+/**
+ * Parse Ethernet link-layer header
+ *
+ * @v netdev	Network device
+ * @v pkb	Packet buffer
+ * @ret rc	Return status code
+ *
+ * This parses the Ethernet link-layer header (destination MAC, source
+ * MAC, network-layer protocol) and fills in the metadata in @c pkb.
+ */
+int eth_parse_llh ( struct net_device *netdev __unused, struct pk_buff *pkb ) {
+	struct ethhdr *ethhdr = pkb->data;
+
+	pkb->net_proto = ethhdr->h_protocol;
+	pkb->flags = PKB_FL_RAW_NET_ADDR;
+	pkb->net_addr_len = sizeof ( ethhdr->h_dest );
+	pkb->net_addr = ethhdr->h_dest;
+
+	if ( memcmp ( ethhdr->h_dest, eth_broadcast,
+		      sizeof ( ethhdr->h_dest ) ) == 0 ) {
+		pkb->flags |= PKB_FL_BROADCAST;
+	} else if ( ethhdr->h_dest[0] & 0x01 ) {
+		pkb->flags |= PKB_FL_MULTICAST;
+	}
+
+	return 0;
+}