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/include/gpxe/arp.h

 struct pk_buff;
 
 extern int arp_resolve ( struct net_device *netdev, struct pk_buff *pkb,
-			 void *ll_addr );
+			 const void **ll_addr );
 
 extern int arp_process ( struct net_interface *arp_netif,
 			 struct pk_buff *pkb );

src/include/gpxe/llh.h

-#ifndef _LLH_H
-#define _LLH_H
-
-/** @file
- *
- * Link-layer headers
- *
- * This file defines a media-independent link-layer header, used for
- * communication between the network and link layers of the stack.
- *
- */
-
-#include <stdint.h>
-
-/** Maximum length of a link-layer address */
-#define MAX_LLH_ADDR_LEN 6
-
-/** Maximum length of a network-layer address */
-#define MAX_NET_ADDR_LEN 4
-
-/* Network-layer address may be required to contain a raw link-layer address */
-#if MAX_NET_ADDR_LEN < MAX_LLH_ADDR_LEN
-#undef MAX_NET_ADDR_LEN
-#define MAX_NET_ADDR_LEN MAX_LLH_ADDR_LEN
-#endif
-
-/** A media-independent link-layer header
- *
- * This structure represents a generic link-layer header.  It never
- * appears on the wire, but is used to communicate between different
- * layers within the gPXE protocol stack.
- */
-struct gpxehdr {
-	/** The network-layer protocol
-	 *
-	 * This is the network-layer protocol expressed as an
-	 * ETH_P_XXX constant, in network-byte order.
-	 */
-	uint16_t net_proto;
-	/** Flags
-	 *
-	 * Filled in only on outgoing packets.  Value is the
-	 * bitwise-OR of zero or more GPXE_FL_XXX constants.
-	 */
-	uint8_t flags;
-	/** Network-layer address length 
-	 *
-	 * Filled in only on outgoing packets.
-	 */
-	uint8_t net_addr_len;
-	/** Network-layer address
-	 *
-	 * Filled in only on outgoing packets.
-	 */
-	uint8_t net_addr[MAX_NET_ADDR_LEN];
-} __attribute__ (( packed ));
-
-/* Media-independent link-layer header flags */
-#define GPXE_FL_BROADCAST	0x01
-#define GPXE_FL_MULTICAST	0x02
-#define GPXE_FL_RAW		0x04
-
-#endif /* _LLH_H */

src/include/gpxe/netdevice.h

  */
 
 #include <stdint.h>
-#include <gpxe/llh.h>
 #include <gpxe/list.h>
 
 struct net_device;
 struct net_interface;
 struct pk_buff;
 
+/** Maximum length of a link-layer address */
+#define MAX_LLH_ADDR_LEN 6
+
+/** Maximum length of a network-layer address */
+#define MAX_NET_ADDR_LEN 4
+
 /**
  * A network device
  *
 	/** Poll for received packet
 	 *
 	 * @v netdev	Network device
-	 * @v retrieve	Flag indicating whether or not to retrieve packet
 	 * @v pkb	Packet buffer to contain received packet
 	 * @ret rc	Return status code
 	 *
 	 * received packet.  If no packet is available, the method
 	 * should return -EAGAIN (i.e. this method is *always*
 	 * considered to be a non-blocking read).  If a packet is
-	 * available, but @c retrieve is false, the method should
-	 * return zero for success.  If a packet is available and @c
-	 * retrieve is true, the method should fill the packet buffer
-	 * and return zero for success.
+	 * available, the method should fill the packet buffer and
+	 * return zero for success.
 	 */
-	int ( * poll ) ( struct net_device *netdev, int retrieve,
-			 struct pk_buff *pkb );
-	/** Build media-specific link-layer header
+	int ( * poll ) ( struct net_device *netdev, struct pk_buff *pkb );
+	/** Build link-layer header
 	 *
 	 * @v netdev	Network device
 	 * @v pkb	Packet buffer
 	 * @ret rc	Return status code
 	 *
-	 * This method should convert the packet buffer's generic
-	 * link-layer header (a struct gpxehdr) into a media-specific
-	 * link-layer header (e.g. a struct ethhdr).  The generic
-	 * header should be removed from the buffer (via pkb_pull())
-	 * and the media-specific header should be prepended (via
-	 * pkb_push()) in its place.
+	 * This method should fill in the link-layer header based on
+	 * the metadata contained in @c pkb.
 	 *
 	 * If a link-layer header cannot be constructed (e.g. because
 	 * of a missing ARP cache entry), then this method should
 	 * return an error (after transmitting an ARP request, if
 	 * applicable).
 	 */
-	int ( * make_media_header ) ( struct net_device *netdev,
-				      struct pk_buff *pkb );
-	/** Build media-independent link-layer header
+	int ( * build_llh ) ( struct net_device *netdev, struct pk_buff *pkb );
+	/** Parse link-layer header
 	 *
 	 * @v netdev	Network device
 	 * @v pkb	Packet buffer
 	 * @ret rc	Return status code
 	 *
-	 * This method should convert the packet buffer's
-	 * media-specific link-layer header (e.g. a struct ethhdr)
-	 * into a generic link-layer header (a struct gpxehdr).  It
-	 * performs the converse function of make_media_header().
-	 *
-	 * Note that the gpxehdr::addr and gpxehdr::addrlen fields
-	 * will not be filled in by this function, since doing so
-	 * would require understanding the network-layer header.
+	 * This method should parse the link-layer header and fill in
+	 * the metadata in @c pkb.
 	 */
-	int ( * make_generic_header ) ( struct net_device *netdev,
-					struct pk_buff *pkb );
+	int ( * parse_llh ) ( struct net_device *netdev, struct pk_buff *pkb );
 	/** Link-layer protocol
 	 *
 	 * This is an ARPHRD_XXX constant, in network byte order.
 	 */
 	uint16_t ll_proto;
+	/** Link-layer header length */
+	uint8_t ll_hlen;
 	/** Link-layer address length */
 	uint8_t ll_addr_len;
 	/** Link-layer address
 	 */
 	int ( * process ) ( struct net_interface *netif,
 			    struct pk_buff *pkb );
-	/** Add media-independent link-layer header
+	/** Fill in packet metadata
 	 *
 	 * @v netif	Network interface
 	 * @v pkb	Packet buffer
 	 * @ret rc	Return status code
 	 *
-	 * This method should prepend a generic link-layer header (a
-	 * struct @c gpxehdr) to the packet buffer using pkb_push().
+	 * This method should fill in the @c pkb metadata with enough
+	 * information to enable net_device::build_llh to construct
+	 * the link-layer header.
 	 */
-	int ( * add_generic_header ) ( struct net_interface *netif,
-				       struct pk_buff *pkb );
+	int ( * add_llh_metadata ) ( struct net_interface *netif,
+				     struct pk_buff *pkb );
 };
 
 /**
 
 extern int register_netdevice ( struct net_device *netdev );
 
-static inline void unregister_netdevice ( struct net_device *netdev __unused ){
-	/* Do nothing */
-}
+extern void unregister_netdevice ( struct net_device *netdev );
 
 static inline void free_netdevice ( struct net_device *netdev __unused ) {
 	/* Do nothing */

src/include/gpxe/pkbuff.h

 	void *tail;
 	/** End of the buffer */
         void *end;
+
+	/** The network-layer protocol
+	 *
+	 * This is the network-layer protocol expressed as an
+	 * ETH_P_XXX constant, in network-byte order.
+	 */
+	uint16_t net_proto;
+	/** Flags
+	 *
+	 * Filled in only on outgoing packets.  Value is the
+	 * bitwise-OR of zero or more PKB_FL_XXX constants.
+	 */
+	uint8_t flags;
+	/** Network-layer address length 
+	 *
+	 * Filled in only on outgoing packets.
+	 */
+	uint8_t net_addr_len;
+	/** Network-layer address
+	 *
+	 * Filled in only on outgoing packets.
+	 */
+	void *net_addr;
 };
 
+/** Packet is a broadcast packet */
+#define PKB_FL_BROADCAST 0x01
+
+/** Packet is a multicast packet */
+#define PKB_FL_MULTICAST 0x02
+
+/** Network-layer address is a raw hardware address */
+#define PKB_FL_RAW_NET_ADDR 0x04
+
 /**
  * Add data to start of packet buffer
  *

src/net/arp.c

 #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>
 
  *
  * @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 );
 	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 ) );
  * @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

+/*
+ * 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;
+}