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.

1 files changed, 171 insertions, 86 deletions

diff --git a/src/net/netdevice.c b/src/net/netdevice.c
index d7ad3080..3ff6657c 100644
--- a/src/net/netdevice.c
+++ b/src/net/netdevice.c
@@ -18,146 +18,231 @@
 
 #include <stdint.h>
 #include <byteswap.h>
+#include <string.h>
 #include <errno.h>
 #include <gpxe/if_ether.h>
 #include <gpxe/pkbuff.h>
+#include <gpxe/tables.h>
 #include <gpxe/netdevice.h>
 
 /** @file
  *
- * Network devices and network interfaces
+ * Network device management
  *
  */
 
-/** List of all registered network devices */
-static LIST_HEAD ( net_devices );
-
 /**
- * Register network device
+ * Static single instance of a network device
+ *
+ * The gPXE API is designed to accommodate multiple network devices.
+ * However, in the interests of code size, the implementation behind
+ * the API supports only a single instance of a network device.
  *
- * @v netdev	Network device
- * @ret rc	Return status code
+ * No code outside of netdevice.c should ever refer directly to @c
+ * static_single_netdev.
  *
- * Adds the network device to the list of network devices.
+ * Callers should always check the return status of alloc_netdev(),
+ * register_netdev() etc.  In the current implementation this code
+ * will be optimised out by the compiler, so there is no penalty.
  */
-int register_netdevice ( struct net_device *netdev ) {
-	list_add ( &netdev->devices, &net_devices );
-	return 0;
-}
+struct net_device static_single_netdev;
+
+/** Registered network-layer protocols */
+static struct net_protocol net_protocols[0] __table_start ( net_protocols );
+static struct net_protocol net_protocols_end[0] __table_end ( net_protocols );
+
+/** Network-layer addresses for @c static_single_netdev */
+static struct net_address static_single_netdev_addresses[0]
+	__table_start ( sgl_netdev_addresses );
+static struct net_address static_single_netdev_addresses_end[0]
+	__table_end ( sgl_netdev_addresses );
+
+/** Recevied packet queue */
+static LIST_HEAD ( rx_queue );
 
 /**
- * Unregister network device
+ * Identify network protocol
  *
- * @v netdev	Network device
+ * @v net_proto		Network-layer protocol, in network-byte order
+ * @ret net_protocol	Network-layer protocol, or NULL
  *
- * Removes the network device from the list of network devices.
+ * Identify a network-layer protocol from a protocol number, which
+ * must be an ETH_P_XXX constant in network-byte order.
  */
-void unregister_netdevice ( struct net_device *netdev ) {
-	list_del ( &netdev->devices );
+struct net_protocol * net_find_protocol ( uint16_t net_proto ) {
+	struct net_protocol *net_protocol;
+
+	for ( net_protocol = net_protocols ; net_protocol < net_protocols_end ;
+	      net_protocol++ ) {
+		if ( net_protocol->net_proto == net_proto )
+			return net_protocol;
+	}
+	return NULL;
 }
 
 /**
- * Transmit packet via network device
+ * Identify network device by network-layer address
  *
- * @v netdev	Network device
- * @v pkb	Packet buffer
- * @ret rc	Return status code
+ * @v net_protocol	Network-layer protocol
+ * @v net_addr		Network-layer address
+ * @ret netdev		Network device, or NULL
  *
- * Transmits the packet via the network device.  The @c pkb link-layer
- * metadata must already have been filled in, and space for the
- * link-layer header must already be present in the packet buffer.
+ * Searches through all network devices to find the device with the
+ * specified network-layer address.
+ *
+ * Note that even with a static single network device, this function
+ * can still return NULL.
  */
-int netdev_send ( struct net_device *netdev, struct pk_buff *pkb ) {
-	int rc;
-
-	if ( pkb->net_proto != ETH_P_RAW ) {
-		if ( ( rc = netdev->build_llh ( netdev, pkb ) ) != 0 )
-			return rc;
+struct net_device * net_find_address ( struct net_protocol *net_protocol,
+				       void *net_addr ) {
+	struct net_address *net_address;
+	struct net_device *netdev = &static_single_netdev;
+	
+	for ( net_address = static_single_netdev_addresses ;
+	      net_address < static_single_netdev_addresses_end ;
+	      net_address ++ ) {
+		if ( ( net_address->net_protocol == net_protocol ) &&
+		     ( memcmp ( net_address->net_addr, net_addr,
+				net_protocol->net_addr_len ) == 0 ) )
+			return netdev;
 	}
-	return netdev->transmit ( netdev, pkb );
+	return NULL;
 }
 
 /**
- * Poll for packet on network device
+ * Transmit packet
  *
- * @v netdev	Network device
- * @v pkb	Packet buffer
- * @ret rc	Return status code
+ * @v pkb		Packet buffer
+ * @ret rc		Return status code
  *
- * Polls the network device for a packet.  If a packet is available,
- * it will be added to the packet buffer, and the link-layer metadata
- * fields in @c pkb will be filled in.
+ * Transmits the packet via the appropriate network device.  If this
+ * function returns success, it has taken ownership of the packet
+ * buffer.
  */
-int netdev_poll ( struct net_device *netdev, struct pk_buff *pkb ) {
+int net_transmit ( struct pk_buff *pkb ) {
+	struct net_protocol *net_protocol;
+	struct net_header nethdr;
+	struct ll_protocol *ll_protocol;
+	struct ll_header llhdr;
+	struct net_device *netdev;
 	int rc;
 
-	if ( ( rc = netdev->poll ( netdev, pkb ) ) != 0 )
-		return rc;
-	return netdev->parse_llh ( netdev, pkb );
+	/* Perform network-layer routing */
+	net_protocol = pkb->net_protocol;
+	nethdr.net_protocol = net_protocol;
+	if ( ( rc = net_protocol->route ( pkb, &nethdr ) ) != 0 )
+		goto err;
+
+	/* Identify transmitting network device */
+	netdev = net_find_address ( net_protocol, nethdr.source_net_addr );
+	if ( ! netdev )
+		goto err;
+
+	/* Perform link-layer routing */
+	ll_protocol = netdev->ll_protocol;
+	llhdr.ll_protocol = ll_protocol;
+	llhdr.net_proto = net_protocol->net_proto;
+	memcpy ( llhdr.source_ll_addr, netdev->ll_addr,
+		 ll_protocol->ll_addr_len);
+	if ( ( rc = ll_protocol->route ( &nethdr, &llhdr ) ) != 0 )
+		goto err;
+
+	/* Prepend link-layer header */
+	pkb_push ( pkb, ll_protocol->ll_header_len );
+	ll_protocol->fill_llh ( &llhdr, pkb );
+
+	/* Transmit packet */
+	if ( ( rc = netdev->transmit ( netdev, pkb ) ) != 0 )
+		goto err;
+
+	return 0;
+
+ err:
+	free_pkb ( pkb );
+	return rc;
 }
 
 /**
- * Transmit packet via network interface
+ * Poll for packet on all network devices
  *
- * @v netif	Network interface
- * @v pkb	Packet buffer
- * @ret rc	Return status code
+ * @ret True		There are packets present in the receive queue
+ * @ret False		There are no packets present in the receive queue
  *
- * Transmits the packet via the network interface.  The packet must
- * start with a network-layer header (e.g. an IP header, for an IP
- * interface).  The packet contents are undefined on return.
+ * Polls all network devices for received packets.  Any received
+ * packets will be added to the RX packet queue via netdev_rx().
  */
-int netif_send ( struct net_interface *netif, struct pk_buff *pkb ) {
-	struct net_device *netdev = netif->netdev;
-	int rc;
+int net_poll ( void ) {
+	struct net_device *netdev = &static_single_netdev;
+
+	netdev->poll ( netdev );
 
-	if ( ( rc = netif->add_llh_metadata ( netif, pkb ) ) != 0 )
-		return rc;
-	pkb_push ( pkb, netdev->ll_hlen );
-	return netdev_send ( netdev, pkb );
+	return ( ! list_empty ( &rx_queue ) );
 }
 
 /**
- * Process received packet
+ * Add packet to receive queue
  *
- * @v netif	Network interface
- * @v pkb	Packet buffer
- * @ret rc	Return status code
+ * @v netdev		Network device
+ * @v pkb		Packet buffer
  *
- * Processes a packet received via netdev_poll().  The interface
- * corresponding to the network-layer protocol is identified, the
- * link-layer header is stripped from the packet and the packet is
- * passed to the net_interface::rx_packet() method.
+ * The packet is added to the RX queue.  Ownership of the packet is
+ * transferred to the RX queue; the caller must not touch the packet
+ * buffer after calling netdev_rx().
  */
-int netdev_rx_packet ( struct net_device *netdev, struct pk_buff *pkb ) {
-	struct net_interface *netif;
-
-	netif = netdev_find_netif ( netdev, pkb->net_proto );
-	if ( ! netif )
-		return -EAFNOSUPPORT;
-
-	pkb_pull ( pkb, netdev->ll_hlen );
-	return netif->rx_packet ( netif, pkb );
+void netdev_rx ( struct net_device *netdev, struct pk_buff *pkb ) {
+	pkb->ll_protocol = netdev->ll_protocol;
+	list_add_tail ( &pkb->list, &rx_queue );
 }
 
 /**
- * Poll for packet on all network devices
+ * Remove packet from receive queue
  *
- * @v pkb	Packet buffer
- * @ret netdev	Network device
- * @ret rc	Return status code
+ * @ret pkb		Packet buffer, or NULL
  *
- * Polls all network devices for a packet.  If a packet is available
- * on any interface, @c netdev will be filled in and the packet will
- * be received as per netdev_poll().
+ * Removes the first packet from the RX queue and returns it.
+ * Ownership of the packet is transferred to the caller.
  */
-int net_poll ( struct pk_buff *pkb, struct net_device **netdev ) {
-	int rc;
+struct pk_buff * net_rx_dequeue ( void ) {
+	struct pk_buff *pkb;
 
-	list_for_each_entry ( (*netdev), &net_devices, devices ) {
-		if ( ( rc = netdev_poll ( *netdev, pkb ) ) == 0 )
-			return rc;
+	list_for_each_entry ( pkb, &rx_queue, list ) {
+		list_del ( &pkb->list );
+		return pkb;
 	}
+	return NULL;
+}
 
-	return -EAGAIN;
+void net_run ( void ) {
+	struct pk_buff *pkb;
+	struct ll_protocol *ll_protocol;
+	struct ll_header llhdr;
+	struct net_protocol *net_protocol;
+
+	while ( ( pkb = net_rx_dequeue () ) ) {
+
+		/* Parse link-layer header */
+		ll_protocol = pkb->ll_protocol;
+		ll_protocol->parse_llh ( pkb, &llhdr );
+
+		/* Identify network-layer protocol */
+		net_protocol = net_find_protocol ( llhdr.net_proto );
+		if ( ! net_protocol ) {
+			DBG ( "Unknown network-layer protocol %02x\n",
+			      ntohs ( llhdr.net_proto ) );
+			free_pkb ( pkb );
+			continue;
+		}
+
+		/* Strip off link-layer header */
+		pkb_pull ( pkb, ll_protocol->ll_header_len );
+
+		/* Hand off to network layer */
+		if ( net_protocol->rx ( pkb ) != 0 ) {
+			free_pkb ( pkb );
+			continue;
+		}
+	}
 }
+
+
+