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https://github.com/ipxe/ipxe
synced 2025-12-19 02:50:25 +03:00
[neighbour] Generalise concept of neighbour discovery
Split the protocol-independent portions of arp.c into a separate file neighbour.c, to allow for sharing of functionality between IPv4+ARP and IPv6+NDP. Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
388
src/net/arp.c
388
src/net/arp.c
@@ -28,11 +28,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
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#include <ipxe/if_arp.h>
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#include <ipxe/iobuf.h>
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#include <ipxe/netdevice.h>
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#include <ipxe/list.h>
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#include <ipxe/retry.h>
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#include <ipxe/timer.h>
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#include <ipxe/malloc.h>
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#include <ipxe/refcnt.h>
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#include <ipxe/neighbour.h>
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#include <ipxe/arp.h>
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/** @file
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@@ -45,291 +41,30 @@ FILE_LICENCE ( GPL2_OR_LATER );
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*
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*/
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/** ARP minimum timeout */
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#define ARP_MIN_TIMEOUT ( TICKS_PER_SEC / 8 )
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/** ARP maximum timeout */
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#define ARP_MAX_TIMEOUT ( TICKS_PER_SEC * 3 )
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/** An ARP cache entry */
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struct arp_entry {
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/** Reference count */
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struct refcnt refcnt;
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/** List of ARP cache entries */
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struct list_head list;
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/** Network device */
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struct net_device *netdev;
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/** Network-layer protocol */
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struct net_protocol *net_protocol;
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/** Network-layer destination address */
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uint8_t net_dest[MAX_NET_ADDR_LEN];
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/** Network-layer source address */
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uint8_t net_source[MAX_NET_ADDR_LEN];
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/** Link-layer destination address */
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uint8_t ll_dest[MAX_LL_ADDR_LEN];
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/** Retransmission timer */
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struct retry_timer timer;
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/** Pending I/O buffers */
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struct list_head tx_queue;
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};
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/** The ARP cache */
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static LIST_HEAD ( arp_entries );
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struct net_protocol arp_protocol __net_protocol;
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static void arp_expired ( struct retry_timer *timer, int over );
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/**
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* Free ARP cache entry
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*
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* @v refcnt Reference count
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*/
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static void arp_free ( struct refcnt *refcnt ) {
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struct arp_entry *arp =
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container_of ( refcnt, struct arp_entry, refcnt );
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/* Sanity check */
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assert ( list_empty ( &arp->tx_queue ) );
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/* Drop reference to network device */
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netdev_put ( arp->netdev );
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/* Free entry */
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free ( arp );
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}
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/**
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* Create ARP cache entry
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* Transmit ARP request
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*
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* @v netdev Network device
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* @v net_protocol Network-layer protocol
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* @v net_dest Destination network-layer address
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* @v net_source Source network-layer address
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* @ret arp ARP cache entry, or NULL if allocation failed
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*/
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static struct arp_entry * arp_create ( struct net_device *netdev,
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struct net_protocol *net_protocol,
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const void *net_dest,
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const void *net_source ) {
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struct arp_entry *arp;
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/* Allocate and initialise entry */
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arp = zalloc ( sizeof ( *arp ) );
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if ( ! arp )
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return NULL;
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ref_init ( &arp->refcnt, arp_free );
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arp->netdev = netdev_get ( netdev );
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arp->net_protocol = net_protocol;
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memcpy ( arp->net_dest, net_dest,
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net_protocol->net_addr_len );
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memcpy ( arp->net_source, net_source,
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net_protocol->net_addr_len );
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timer_init ( &arp->timer, arp_expired, &arp->refcnt );
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arp->timer.min_timeout = ARP_MIN_TIMEOUT;
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arp->timer.max_timeout = ARP_MAX_TIMEOUT;
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INIT_LIST_HEAD ( &arp->tx_queue );
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/* Start timer running to trigger initial transmission */
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start_timer_nodelay ( &arp->timer );
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/* Transfer ownership to cache */
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list_add ( &arp->list, &arp_entries );
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DBGC ( arp, "ARP %p %s %s %s created\n", arp, netdev->name,
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net_protocol->name, net_protocol->ntoa ( net_dest ) );
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return arp;
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}
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/**
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* Find entry in the ARP cache
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*
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* @v netdev Network device
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* @v net_protocol Network-layer protocol
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* @v net_dest Destination network-layer address
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* @ret arp ARP cache entry, or NULL if not found
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*/
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static struct arp_entry * arp_find ( struct net_device *netdev,
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struct net_protocol *net_protocol,
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const void *net_dest ) {
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struct arp_entry *arp;
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list_for_each_entry ( arp, &arp_entries, list ) {
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if ( ( arp->netdev == netdev ) &&
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( arp->net_protocol == net_protocol ) &&
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( memcmp ( arp->net_dest, net_dest,
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net_protocol->net_addr_len ) == 0 ) ) {
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/* Move to start of cache */
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list_del ( &arp->list );
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list_add ( &arp->list, &arp_entries );
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return arp;
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}
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}
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return NULL;
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}
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/**
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* Destroy ARP cache entry
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*
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* @v arp ARP cache entry
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* @v rc Reason for destruction
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*/
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static void arp_destroy ( struct arp_entry *arp, int rc ) {
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struct net_device *netdev = arp->netdev;
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struct net_protocol *net_protocol = arp->net_protocol;
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struct io_buffer *iobuf;
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/* Take ownership from cache */
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list_del ( &arp->list );
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/* Stop timer */
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stop_timer ( &arp->timer );
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/* Discard any outstanding I/O buffers */
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while ( ( iobuf = list_first_entry ( &arp->tx_queue, struct io_buffer,
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list ) ) != NULL ) {
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DBGC2 ( arp, "ARP %p %s %s %s discarding deferred packet: "
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"%s\n", arp, netdev->name, net_protocol->name,
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net_protocol->ntoa ( arp->net_dest ), strerror ( rc ) );
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list_del ( &iobuf->list );
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netdev_tx_err ( arp->netdev, iobuf, rc );
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}
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DBGC ( arp, "ARP %p %s %s %s destroyed: %s\n", arp, netdev->name,
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net_protocol->name, net_protocol->ntoa ( arp->net_dest ),
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strerror ( rc ) );
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/* Drop remaining reference */
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ref_put ( &arp->refcnt );
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}
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/**
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* Test if ARP cache entry has a valid link-layer address
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*
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* @v arp ARP cache entry
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* @ret resolved ARP cache entry is resolved
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*/
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static inline int arp_resolved ( struct arp_entry *arp ) {
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return ( ! timer_running ( &arp->timer ) );
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}
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/**
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* Transmit packet, determining link-layer address via ARP
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*
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* @v iobuf I/O buffer
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* @v netdev Network device
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* @v net_protocol Network-layer protocol
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* @v net_dest Destination network-layer address
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* @v net_source Source network-layer address
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* @v ll_source Source link-layer address
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* @ret rc Return status code
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*/
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int arp_tx ( struct io_buffer *iobuf, struct net_device *netdev,
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struct net_protocol *net_protocol, const void *net_dest,
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const void *net_source, const void *ll_source ) {
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struct arp_entry *arp;
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/* Find or create ARP cache entry */
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arp = arp_find ( netdev, net_protocol, net_dest );
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if ( ! arp ) {
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arp = arp_create ( netdev, net_protocol, net_dest,
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net_source );
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if ( ! arp )
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return -ENOMEM;
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}
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/* If a link-layer address is available then transmit
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* immediately, otherwise queue for later transmission.
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*/
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if ( arp_resolved ( arp ) ) {
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return net_tx ( iobuf, netdev, net_protocol, arp->ll_dest,
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ll_source );
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} else {
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DBGC2 ( arp, "ARP %p %s %s %s deferring packet\n",
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arp, netdev->name, net_protocol->name,
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net_protocol->ntoa ( net_dest ) );
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list_add_tail ( &iobuf->list, &arp->tx_queue );
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return -EAGAIN;
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}
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}
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/**
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* Update ARP cache entry
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*
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* @v arp ARP cache entry
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* @v ll_dest Destination link-layer address
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*/
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static void arp_update ( struct arp_entry *arp, const void *ll_dest ) {
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struct net_device *netdev = arp->netdev;
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static int arp_tx_request ( struct net_device *netdev,
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struct net_protocol *net_protocol,
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const void *net_dest, const void *net_source ) {
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struct ll_protocol *ll_protocol = netdev->ll_protocol;
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struct net_protocol *net_protocol = arp->net_protocol;
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struct io_buffer *iobuf;
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int rc;
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DBGC ( arp, "ARP %p %s %s %s updated => %s\n", arp, netdev->name,
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net_protocol->name, net_protocol->ntoa ( arp->net_dest ),
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ll_protocol->ntoa ( ll_dest ) );
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/* Fill in link-layer address */
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memcpy ( arp->ll_dest, ll_dest, ll_protocol->ll_addr_len );
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/* Stop retransmission timer */
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stop_timer ( &arp->timer );
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/* Transmit any packets in queue. Take out a temporary
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* reference on the entry to prevent it from going out of
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* scope during the call to net_tx().
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*/
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ref_get ( &arp->refcnt );
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while ( ( iobuf = list_first_entry ( &arp->tx_queue, struct io_buffer,
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list ) ) != NULL ) {
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DBGC2 ( arp, "ARP %p %s %s %s transmitting deferred packet\n",
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arp, netdev->name, net_protocol->name,
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net_protocol->ntoa ( arp->net_dest ) );
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list_del ( &iobuf->list );
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if ( ( rc = net_tx ( iobuf, netdev, net_protocol, ll_dest,
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netdev->ll_addr ) ) != 0 ) {
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DBGC ( arp, "ARP %p could not transmit deferred "
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"packet: %s\n", arp, strerror ( rc ) );
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/* Ignore error and continue */
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}
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}
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ref_put ( &arp->refcnt );
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}
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/**
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* Handle ARP timer expiry
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*
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* @v timer Retry timer
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* @v fail Failure indicator
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*/
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static void arp_expired ( struct retry_timer *timer, int fail ) {
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struct arp_entry *arp = container_of ( timer, struct arp_entry, timer );
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struct net_device *netdev = arp->netdev;
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struct ll_protocol *ll_protocol = netdev->ll_protocol;
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struct net_protocol *net_protocol = arp->net_protocol;
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struct io_buffer *iobuf;
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struct arphdr *arphdr;
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int rc;
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/* If we have failed, destroy the cache entry */
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if ( fail ) {
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arp_destroy ( arp, -ETIMEDOUT );
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return;
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}
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/* Restart the timer */
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start_timer ( &arp->timer );
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/* Allocate ARP packet */
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iobuf = alloc_iob ( MAX_LL_HEADER_LEN + sizeof ( *arphdr ) +
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( 2 * ( MAX_LL_ADDR_LEN + MAX_NET_ADDR_LEN ) ) );
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if ( ! iobuf ) {
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/* Leave timer running and try again later */
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return;
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}
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if ( ! iobuf )
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return -ENOMEM;
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iob_reserve ( iobuf, MAX_LL_HEADER_LEN );
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/* Build up ARP request */
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@@ -342,21 +77,30 @@ static void arp_expired ( struct retry_timer *timer, int fail ) {
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memcpy ( iob_put ( iobuf, ll_protocol->ll_addr_len ),
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netdev->ll_addr, ll_protocol->ll_addr_len );
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memcpy ( iob_put ( iobuf, net_protocol->net_addr_len ),
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arp->net_source, net_protocol->net_addr_len );
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net_source, net_protocol->net_addr_len );
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memset ( iob_put ( iobuf, ll_protocol->ll_addr_len ),
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0, ll_protocol->ll_addr_len );
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memcpy ( iob_put ( iobuf, net_protocol->net_addr_len ),
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arp->net_dest, net_protocol->net_addr_len );
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net_dest, net_protocol->net_addr_len );
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/* Transmit ARP request */
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if ( ( rc = net_tx ( iobuf, netdev, &arp_protocol,
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netdev->ll_broadcast, netdev->ll_addr ) ) != 0 ) {
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DBGC ( arp, "ARP %p could not transmit request: %s\n",
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arp, strerror ( rc ) );
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return;
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DBGC ( netdev, "ARP %s %s %s could not transmit request: %s\n",
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netdev->name, net_protocol->name,
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net_protocol->ntoa ( net_dest ), strerror ( rc ) );
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return rc;
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}
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return 0;
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}
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/** ARP neighbour discovery protocol */
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struct neighbour_discovery arp_discovery = {
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.name = "ARP",
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.tx_request = arp_tx_request,
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};
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/**
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* Identify ARP protocol
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*
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@@ -368,9 +112,8 @@ static struct arp_net_protocol * arp_find_protocol ( uint16_t net_proto ) {
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struct arp_net_protocol *arp_net_protocol;
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for_each_table_entry ( arp_net_protocol, ARP_NET_PROTOCOLS ) {
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if ( arp_net_protocol->net_protocol->net_proto == net_proto ) {
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if ( arp_net_protocol->net_protocol->net_proto == net_proto )
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return arp_net_protocol;
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}
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}
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return NULL;
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}
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@@ -392,7 +135,6 @@ static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
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struct arp_net_protocol *arp_net_protocol;
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struct net_protocol *net_protocol;
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struct ll_protocol *ll_protocol;
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struct arp_entry *arp;
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int rc;
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/* Identify network-layer and link-layer protocols */
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@@ -412,11 +154,9 @@ static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
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goto done;
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}
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/* See if we have an entry for this sender, and update it if so */
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arp = arp_find ( netdev, net_protocol, arp_sender_pa ( arphdr ) );
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if ( arp ) {
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arp_update ( arp, arp_sender_ha ( arphdr ) );
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}
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/* Update neighbour cache entry for this sender, if any */
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neighbour_update ( netdev, net_protocol, arp_sender_pa ( arphdr ),
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arp_sender_ha ( arphdr ) );
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/* If it's not a request, there's nothing more to do */
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if ( arphdr->ar_op != htons ( ARPOP_REQUEST ) ) {
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@@ -431,10 +171,10 @@ static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
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}
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/* Change request to a reply */
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DBGC ( netdev, "ARP reply %s %s %s => %s %s\n",
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netdev->name, net_protocol->name,
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net_protocol->ntoa ( arp_target_pa ( arphdr ) ),
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ll_protocol->name, ll_protocol->ntoa ( netdev->ll_addr ) );
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DBGC2 ( netdev, "ARP %s %s %s reply => %s %s\n",
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netdev->name, net_protocol->name,
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net_protocol->ntoa ( arp_target_pa ( arphdr ) ),
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ll_protocol->name, ll_protocol->ntoa ( netdev->ll_addr ) );
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arphdr->ar_op = htons ( ARPOP_REPLY );
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memswap ( arp_sender_ha ( arphdr ), arp_target_ha ( arphdr ),
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arphdr->ar_hln + arphdr->ar_pln );
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@@ -444,8 +184,10 @@ static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
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if ( ( rc = net_tx ( iob_disown ( iobuf ), netdev, &arp_protocol,
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arp_target_ha ( arphdr ),
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netdev->ll_addr ) ) != 0 ) {
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DBGC ( netdev, "ARP could not transmit reply via %s: %s\n",
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netdev->name, strerror ( rc ) );
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DBGC ( netdev, "ARP %s %s %s could not transmit reply: %s\n",
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netdev->name, net_protocol->name,
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net_protocol->ntoa ( arp_target_pa ( arphdr ) ),
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strerror ( rc ) );
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goto done;
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}
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@@ -469,72 +211,10 @@ static const char * arp_ntoa ( const void *net_addr __unused ) {
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return "<ARP>";
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}
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/** ARP protocol */
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/** ARP network protocol */
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struct net_protocol arp_protocol __net_protocol = {
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.name = "ARP",
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.net_proto = htons ( ETH_P_ARP ),
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.rx = arp_rx,
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.ntoa = arp_ntoa,
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};
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/**
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* Update ARP cache on network device creation
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*
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* @v netdev Network device
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*/
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static int arp_probe ( struct net_device *netdev __unused ) {
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/* Nothing to do */
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return 0;
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}
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/**
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* Update ARP cache on network device state change or removal
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*
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* @v netdev Network device
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*/
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static void arp_flush ( struct net_device *netdev ) {
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struct arp_entry *arp;
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struct arp_entry *tmp;
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/* Remove all ARP cache entries when a network device is closed */
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if ( ! netdev_is_open ( netdev ) ) {
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list_for_each_entry_safe ( arp, tmp, &arp_entries, list )
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arp_destroy ( arp, -ENODEV );
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}
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}
|
||||
|
||||
/** ARP driver (for net device notifications) */
|
||||
struct net_driver arp_net_driver __net_driver = {
|
||||
.name = "ARP",
|
||||
.probe = arp_probe,
|
||||
.notify = arp_flush,
|
||||
.remove = arp_flush,
|
||||
};
|
||||
|
||||
/**
|
||||
* Discard some cached ARP entries
|
||||
*
|
||||
* @ret discarded Number of cached items discarded
|
||||
*/
|
||||
static unsigned int arp_discard ( void ) {
|
||||
struct arp_entry *arp;
|
||||
|
||||
/* Drop oldest cache entry, if any */
|
||||
arp = list_last_entry ( &arp_entries, struct arp_entry, list );
|
||||
if ( arp ) {
|
||||
arp_destroy ( arp, -ENOBUFS );
|
||||
return 1;
|
||||
} else {
|
||||
return 0;
|
||||
}
|
||||
}
|
||||
|
||||
/** ARP cache discarder
|
||||
*
|
||||
* ARP cache entries are deemed to have a high replacement cost, since
|
||||
* flushing an active ARP cache entry midway through a TCP transfer
|
||||
* will cause substantial disruption.
|
||||
*/
|
||||
struct cache_discarder arp_discarder __cache_discarder ( CACHE_EXPENSIVE ) = {
|
||||
.discard = arp_discard,
|
||||
};
|
||||
|
||||
Reference in New Issue
Block a user