Network API now allows for multiple network devices (although the

implementation allows for only one, and does so without compromising on
the efficiency of static allocation).

Link-layer protocols are cleanly separated from the device drivers.

Network-layer protocols are cleanly separated from individual network
devices.

Link-layer and network-layer protocols are cleanly separated from each
other.

3 files changed, 272 insertions, 173 deletions

diff --git a/src/include/gpxe/arp.h b/src/include/gpxe/arp.h
index f6ec47af..a2db80f1 100644
--- a/src/include/gpxe/arp.h
+++ b/src/include/gpxe/arp.h
@@ -1,5 +1,5 @@
-#ifndef _ARP_H
-#define _ARP_H
+#ifndef _GPXE_ARP_H
+#define _GPXE_ARP_H
 
 /** @file
  *
@@ -7,17 +7,10 @@
  *
  */
 
-struct net_device;
-struct net_interface;
-struct pk_buff;
+struct net_header;
+struct ll_header;
 
-extern int arp_resolve ( struct net_device *netdev, struct pk_buff *pkb,
-			 const void **ll_addr );
+extern int arp_resolve ( const struct net_header *nethdr,
+			 struct ll_header *llhdr );
 
-extern int arp_process ( struct net_interface *arp_netif,
-			 struct pk_buff *pkb );
-
-extern int arp_add_generic_header ( struct net_interface *arp_netif,
-				    struct pk_buff *pkb );
-
-#endif /* _ARP_H */
+#endif /* _GPXE_ARP_H */
diff --git a/src/include/gpxe/netdevice.h b/src/include/gpxe/netdevice.h
index 93a98634..f7d78288 100644
--- a/src/include/gpxe/netdevice.h
+++ b/src/include/gpxe/netdevice.h
@@ -1,203 +1,326 @@
-#ifndef _NETDEVICE_H
-#define _NETDEVICE_H
+#ifndef _GPXE_NETDEVICE_H
+#define _GPXE_NETDEVICE_H
 
 /** @file
  *
- * Network device and network interface
+ * Network device management
  *
  */
 
 #include <stdint.h>
-#include <gpxe/list.h>
+#include <gpxe/tables.h>
 
-struct net_device;
-struct net_interface;
 struct pk_buff;
+struct net_protocol;
+struct ll_protocol;
 
 /** Maximum length of a link-layer address */
-#define MAX_LLH_ADDR_LEN 6
+#define MAX_LL_ADDR_LEN 6
 
 /** Maximum length of a network-layer address */
 #define MAX_NET_ADDR_LEN 4
 
+/* Network-layer address may be required to hold a link-layer address
+ * (if NETADDR_FL_RAW is set
+ */
+#if MAX_NET_ADDR_LEN < MAX_LL_ADDR_LEN
+#undef MAX_NET_ADDR_LEN
+#define MAX_NET_ADDR_LEN MAX_LL_ADDR_LEN
+#endif
+
+/** A generic network-layer header */
+struct net_header {
+	/** Network-layer protocol */
+	struct net_protocol *net_protocol;
+	/** Destination address flags
+	 *
+	 * This is the bitwise OR of zero or more NETADDR_FL_XXX
+	 * values.
+	 */
+	int dest_flags;
+	/** Network-layer destination address */
+	uint8_t dest_net_addr[MAX_NET_ADDR_LEN];
+	/** Network-layer source address */
+	uint8_t source_net_addr[MAX_NET_ADDR_LEN];
+};
+
+/** Address is a broadcast address */
+#define NETADDR_FL_BROADCAST 0x01
+
+/** Address is a multicast address */
+#define NETADDR_FL_MULTICAST 0x02
+
+/** Address is a raw hardware address */
+#define NETADDR_FL_RAW 0x04
+
+/** A generic link-layer header */
+struct ll_header {
+	/** Link-layer protocol */
+	struct ll_protocol *ll_protocol;
+	/** Destination address flags
+	 *
+	 * This is the bitwise OR of zero or more NETADDR_FL_XXX
+	 * values.
+	 */
+	int dest_flags;
+	/** Link-layer destination address */
+	uint8_t dest_ll_addr[MAX_LL_ADDR_LEN];
+	/** Link-layer source address */
+	uint8_t source_ll_addr[MAX_LL_ADDR_LEN];
+	/** Network-layer protocol
+	 *
+	 *
+	 * This is an ETH_P_XXX constant, in network-byte order
+	 */
+	uint16_t net_proto;
+};
+
 /**
- * A network device
- *
- * This structure represents a piece of networking hardware.  It has
- * properties such as a link-layer address and methods for
- * transmitting and receiving raw packets.  It does not know anything
- * about network-layer protocols (e.g. IP) or their addresses; these
- * are handled by struct @c net_interface instead.
+ * A network-layer protocol
  *
- * Note that this structure must represent a generic network device,
- * not just an Ethernet device.
  */
-struct net_device {
-	/** Transmit packet
+struct net_protocol {
+	/**
+	 * Perform network-layer routing
 	 *
-	 * @v netdev	Network device
 	 * @v pkb	Packet buffer
+	 * @ret source	Network-layer source address
+	 * @ret dest	Network-layer destination address
 	 * @ret rc	Return status code
 	 *
-	 * This method should cause the hardware to initiate
-	 * transmission of the packet buffer.  The buffer may be
-	 * reused immediately after the method returns, and so the
-	 * method should either wait for packet transmission to
-	 * complete, or take a copy of the buffer contents.
+	 * This method should fill in the source and destination
+	 * addresses with enough information to allow the link layer
+	 * to route the packet.
+	 *
+	 * For example, in the case of IPv4, this method should fill
+	 * in @c source with the IP addresses of the local adapter and
+	 * @c dest with the next hop destination (e.g. the gateway).
 	 */
-	int ( * transmit ) ( struct net_device *netdev,
-			     struct pk_buff *pkb );
-	/** Poll for received packet
+	int ( * route ) ( const struct pk_buff *pkb,
+			  struct net_header *nethdr );
+	/**
+	 * Handle received packets
 	 *
-	 * @v netdev	Network device
-	 * @v pkb	Packet buffer to contain received packet
+	 * @v pkb	Packet buffer
 	 * @ret rc	Return status code
 	 *
-	 * This method should cause the hardware to check for a
-	 * 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, the method should fill the packet buffer and
-	 * return zero for success.
+	 * If this method returns success, it has taken ownership of
+	 * the packet buffer.
 	 */
-	int ( * poll ) ( struct net_device *netdev, struct pk_buff *pkb );
-	/** Build link-layer header
+	int ( * rx ) ( struct pk_buff *pkb );
+	/** Network-layer protocol
 	 *
-	 * @v netdev	Network device
-	 * @v pkb	Packet buffer
+	 * This is an ETH_P_XXX constant, in network-byte order
+	 */
+	uint16_t net_proto;
+	/** Network-layer address length */
+	uint8_t net_addr_len;
+};
+
+/**
+ * A link-layer protocol
+ *
+ */
+struct ll_protocol {
+	/**
+	 * Perform link-layer routing
+	 *
+	 * @v nethdr	Generic network-layer header
+	 * @ret llhdr	Generic link-layer header
 	 * @ret rc	Return status code
 	 *
-	 * This method should fill in the link-layer header based on
-	 * the metadata contained in @c pkb.
+	 * This method should construct the generic link-layer header
+	 * based on the generic network-layer header.
 	 *
 	 * 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 ( * build_llh ) ( struct net_device *netdev, struct pk_buff *pkb );
-	/** Parse link-layer header
+	int ( * route ) ( const struct net_header *nethdr,
+			  struct ll_header *llhdr );
+	/**
+	 * Fill media-specific link-layer header
 	 *
-	 * @v netdev	Network device
+	 * @v llhdr	Generic link-layer header
 	 * @v pkb	Packet buffer
-	 * @ret rc	Return status code
 	 *
-	 * This method should parse the link-layer header and fill in
-	 * the metadata in @c pkb.
+	 * This method should fill in the link-layer header in the
+	 * packet buffer based on information in the generic
+	 * link-layer header.
+	 */
+	void ( * fill_llh ) ( const struct ll_header *llhdr,
+			      struct pk_buff *pkb );
+	/**
+	 * Parse media-specific link-layer header
+	 *
+	 * @v pkb	Packet buffer
+	 * @v llhdr	Generic link-layer header
+	 *
+	 * This method should fill in the generic link-layer header
+	 * based on information in the link-layer header in the packet
+	 * buffer.
 	 */
-	int ( * parse_llh ) ( struct net_device *netdev, struct pk_buff *pkb );
+	void ( * parse_llh ) ( const struct pk_buff *pkb,
+			       struct ll_header *llhdr );
+
 	/** 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
-	 *
-	 * For Ethernet, this is the MAC address.
-	 */
-	uint8_t ll_addr[MAX_LLH_ADDR_LEN];
-	/** Linked list of network devices */
-	struct list_head devices;
-	/** List of network interfaces */
-	struct list_head interfaces;
-	/** Driver private data */
-	void *priv;
+	/** Link-layer header length */
+	uint8_t ll_header_len;
 };
 
 /**
- * A network interface
- *
- * This structure represents a particular network layer protocol's
- * interface to a piece of network hardware (a struct @c net_device).
+ * A network-layer address assigned to a network device
  *
  */
-struct net_interface {
-	/** Underlying net device */
-	struct net_device *netdev;
-	/** Linked list of interfaces for this device */
-	struct list_head interfaces;
-	/** Network-layer protocol
-	 *
-	 * This is an ETH_P_XXX constant, in network byte order.
-	 */
-	uint16_t net_proto;
-	/** Network-layer address length */
-	uint8_t net_addr_len;
+struct net_address {
+	/** Network-layer protocol */
+	struct net_protocol *net_protocol;
 	/** Network-layer address */
 	uint8_t net_addr[MAX_NET_ADDR_LEN];
-	/** Fill in packet metadata
+};
+
+/**
+ * A network device
+ *
+ * This structure represents a piece of networking hardware.  It has
+ * properties such as a link-layer address and methods for
+ * transmitting and receiving raw packets.
+ *
+ * Note that this structure must represent a generic network device,
+ * not just an Ethernet device.
+ */
+struct net_device {
+	/** Transmit packet
 	 *
-	 * @v netif	Network interface
+	 * @v netdev	Network device
 	 * @v pkb	Packet buffer
 	 * @ret rc	Return status code
 	 *
-	 * This method should fill in the @c pkb metadata with enough
-	 * information to enable net_device::build_llh to construct
-	 * the link-layer header.
+	 * This method should cause the hardware to initiate
+	 * transmission of the packet buffer.
+	 *
+	 * If the method returns success, ownership of the packet
+	 * buffer is transferred to the @c net_device, which must
+	 * eventually call free_pkb() to release the buffer.
 	 */
-	int ( * add_llh_metadata ) ( struct net_interface *netif,
-				     struct pk_buff *pkb );
-	/** Received packet processor
+	int ( * transmit ) ( struct net_device *netdev, struct pk_buff *pkb );
+	/** Poll for received packet
 	 *
-	 * @v netif	Network interface
-	 * @v pkb	Packet buffer
-	 * @ret rc	Return status code
+	 * @v netdev	Network device
 	 *
-	 * This method is called for packets arriving on the
-	 * associated network device that match this interface's
-	 * network-layer protocol.
+	 * This method should cause the hardware to check for received
+	 * packets.  Any received packets should be delivered via
+	 * netdev_rx().
+	 */
+	void ( * poll ) ( struct net_device *netdev );
+
+	/** Link-layer protocol */
+	struct ll_protocol *ll_protocol;
+	/** Link-layer address
 	 *
-	 * When this method is called, the link-layer header will
-	 * already have been stripped from the packet.
+	 * For Ethernet, this is the MAC address.
 	 */
-	int ( * rx_packet ) ( struct net_interface *netif,
-			      struct pk_buff *pkb );
+	uint8_t ll_addr[MAX_LL_ADDR_LEN];
+
+	/** Driver private data */
+	void *priv;
 };
 
+extern struct net_device static_single_netdev;
+
+/**
+ * Allocate network device
+ *
+ * @v priv_size		Size of private data area (net_device::priv)
+ * @ret netdev		Network device, or NULL
+ *
+ * Allocates space for a network device and its private data area.
+ *
+ * This macro allows for a very efficient implementation in the case
+ * of a single static network device; it neatly avoids dynamic
+ * allocation and can never return failure, meaning that the failure
+ * path will be optimised away.  However, driver writers should not
+ * rely on this feature; the drivers should be written to allow for
+ * multiple instances of network devices.
+ */
+#define alloc_netdev( priv_size ) ( {		\
+	static char priv_data[priv_size];	\
+	static_single_netdev.priv = priv_data;	\
+	&static_single_netdev; } )
+
 /**
- * Find interface for a specific protocol
+ * Register network device
  *
- * @v netdev	Network device
- * @v net_proto	Network-layer protocol, in network byte order
- * @ret netif	Network interface, or NULL if none found
+ * @v netdev		Network device
+ * @ret rc		Return status code
  *
+ * Adds the network device to the list of network devices.
  */
-static inline struct net_interface *
-netdev_find_netif ( const struct net_device *netdev, uint16_t net_proto ) {
-	struct net_interface *netif;
-
-	list_for_each_entry ( netif, &netdev->interfaces, interfaces ) {
-		if ( netif->net_proto == net_proto )
-			return netif;
-	}
-	return NULL;
+static inline int
+register_netdev ( struct net_device *netdev __attribute__ (( unused )) ) {
+	return 0;
 }
 
-extern int register_netdevice ( struct net_device *netdev );
-extern void unregister_netdevice ( struct net_device *netdev );
-extern int netdev_send ( struct net_device *netdev, struct pk_buff *pkb );
-extern int netdev_poll ( struct net_device *netdev, struct pk_buff *pkb );
-extern int netif_send ( struct net_interface *netif, struct pk_buff *pkb );
-extern int netdev_rx_packet ( struct net_device *netdev, struct pk_buff *pkb );
-extern int net_poll ( struct pk_buff *pkb, struct net_device **netdev );
+/**
+ * Unregister network device
+ *
+ * @v netdev		Network device
+ *
+ * Removes the network device from the list of network devices.
+ */
+static inline void 
+unregister_netdev ( struct net_device *netdev __attribute__ (( unused )) ) {
+	/* Nothing to do */
+}
 
+/**
+ * Free network device
+ *
+ * @v netdev		Network device
+ */
+static inline void
+free_netdev ( struct net_device *netdev __attribute__ (( unused )) ) {
+	/* Nothing to do */
+}
 
+/**
+ * Register a link-layer protocol
+ *
+ * @v protocol		Link-layer protocol
+ */
+#define LL_PROTOCOL( protocol ) \
+	struct ll_protocol protocol __table ( ll_protocols, 00 )
 
-extern struct net_device static_single_netdev;
+/**
+ * Register a network-layer protocol
+ *
+ * @v protocol		Network-layer protocol
+ */
+#define NET_PROTOCOL( protocol ) \
+	struct net_protocol protocol __table ( net_protocols, 00 )
 
-/* Must be a macro because priv_data[] is of variable size */
-#define alloc_netdevice( priv_size ) ( {		\
-	static char priv_data[priv_size];		\
-	static_single_netdev.priv = priv_data;	\
-	&static_single_netdev; } )
+/**
+ * Register a network-layer address for the static single network device
+ *
+ * @v net_address	Network-layer address
+ */
+#define STATIC_SINGLE_NETDEV_ADDRESS( address ) \
+	struct net_address address __table ( sgl_netdev_addresses, 00 )
 
+extern struct net_protocol *net_find_protocol ( uint16_t net_proto );
+extern struct net_device * net_find_address ( struct net_protocol *net_proto,
+					      void *net_addr );
 
-static inline void free_netdevice ( struct net_device *netdev __unused ) {
-	/* Do nothing */
-}
+extern int net_transmit ( struct pk_buff *pkb );
+extern int net_poll ( void );
+extern void netdev_rx ( struct net_device *netdev, struct pk_buff *pkb );
+extern struct pk_buff * net_rx_dequeue ( void );
 
-#endif /* _NETDEVICE_H */
+#endif /* _GPXE_NETDEVICE_H */
diff --git a/src/include/gpxe/pkbuff.h b/src/include/gpxe/pkbuff.h
index f82f508a..2e3980a8 100644
--- a/src/include/gpxe/pkbuff.h
+++ b/src/include/gpxe/pkbuff.h
@@ -1,5 +1,5 @@
-#ifndef _PKBUFF_H
-#define _PKBUFF_H
+#ifndef _GPXE_PKBUFF_H
+#define _GPXE_PKBUFF_H
 
 /** @file
  *
@@ -12,6 +12,10 @@
 
 #include <stdint.h>
 #include <assert.h>
+#include <gpxe/list.h>
+
+struct net_protocol;
+struct ll_protocol;
 
 /** A packet buffer
  *
@@ -27,38 +31,14 @@ struct pk_buff {
 	/** 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
+	/** List of which this buffer is a member */
+	struct list_head list;
 
-/** 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
+	/** The network-layer protocol */
+	struct net_protocol *net_protocol;
+	/** The link-layer protocol */
+	struct ll_protocol *ll_protocol;
+};
 
 /**
  * Add data to start of packet buffer
@@ -130,4 +110,7 @@ static inline size_t pkb_len ( struct pk_buff *pkb ) {
 	return ( pkb->tail - pkb->data );
 }
 
-#endif /* _PKBUFF_H */
+extern struct pk_buff * alloc_pkb ( size_t len );
+extern void free_pkb ( struct pk_buff *pkb );
+
+#endif /* _GPXE_PKBUFF_H */