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- /*
- * 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., 51 Franklin Street, Fifth Floor, Boston, MA
- * 02110-1301, USA.
- */
-
- FILE_LICENCE ( GPL2_OR_LATER );
-
- #include <stdint.h>
- #include <stdlib.h>
- #include <string.h>
- #include <byteswap.h>
- #include <errno.h>
- #include <ipxe/if_ether.h>
- #include <ipxe/if_arp.h>
- #include <ipxe/iobuf.h>
- #include <ipxe/netdevice.h>
- #include <ipxe/list.h>
- #include <ipxe/retry.h>
- #include <ipxe/timer.h>
- #include <ipxe/malloc.h>
- #include <ipxe/refcnt.h>
- #include <ipxe/arp.h>
-
- /** @file
- *
- * Address Resolution Protocol
- *
- * This file implements the address resolution protocol as defined in
- * RFC826. The implementation is media-independent and
- * protocol-independent; it is not limited to Ethernet or to IPv4.
- *
- */
-
- /** ARP minimum timeout */
- #define ARP_MIN_TIMEOUT ( TICKS_PER_SEC / 8 )
-
- /** ARP maximum timeout */
- #define ARP_MAX_TIMEOUT ( TICKS_PER_SEC * 3 )
-
- /** An ARP cache entry */
- struct arp_entry {
- /** Reference count */
- struct refcnt refcnt;
- /** List of ARP cache entries */
- struct list_head list;
- /** Network device */
- struct net_device *netdev;
- /** Network-layer protocol */
- struct net_protocol *net_protocol;
- /** Network-layer destination address */
- uint8_t net_dest[MAX_NET_ADDR_LEN];
- /** Network-layer source address */
- uint8_t net_source[MAX_NET_ADDR_LEN];
- /** Link-layer destination address */
- uint8_t ll_dest[MAX_LL_ADDR_LEN];
- /** Retransmission timer */
- struct retry_timer timer;
- /** Pending I/O buffers */
- struct list_head tx_queue;
- };
-
- /** The ARP cache */
- static LIST_HEAD ( arp_entries );
-
- struct net_protocol arp_protocol __net_protocol;
-
- static void arp_expired ( struct retry_timer *timer, int over );
-
- /**
- * Free ARP cache entry
- *
- * @v refcnt Reference count
- */
- static void arp_free ( struct refcnt *refcnt ) {
- struct arp_entry *arp =
- container_of ( refcnt, struct arp_entry, refcnt );
-
- /* Sanity check */
- assert ( list_empty ( &arp->tx_queue ) );
-
- /* Drop reference to network device */
- netdev_put ( arp->netdev );
-
- /* Free entry */
- free ( arp );
- }
-
- /**
- * Create ARP cache entry
- *
- * @v netdev Network device
- * @v net_protocol Network-layer protocol
- * @v net_dest Destination network-layer address
- * @v net_source Source network-layer address
- * @ret arp ARP cache entry, or NULL if allocation failed
- */
- static struct arp_entry * arp_create ( struct net_device *netdev,
- struct net_protocol *net_protocol,
- const void *net_dest,
- const void *net_source ) {
- struct arp_entry *arp;
-
- /* Allocate and initialise entry */
- arp = zalloc ( sizeof ( *arp ) );
- if ( ! arp )
- return NULL;
- ref_init ( &arp->refcnt, arp_free );
- arp->netdev = netdev_get ( netdev );
- arp->net_protocol = net_protocol;
- memcpy ( arp->net_dest, net_dest,
- net_protocol->net_addr_len );
- memcpy ( arp->net_source, net_source,
- net_protocol->net_addr_len );
- timer_init ( &arp->timer, arp_expired, &arp->refcnt );
- arp->timer.min_timeout = ARP_MIN_TIMEOUT;
- arp->timer.max_timeout = ARP_MAX_TIMEOUT;
- INIT_LIST_HEAD ( &arp->tx_queue );
-
- /* Start timer running to trigger initial transmission */
- start_timer_nodelay ( &arp->timer );
-
- /* Transfer ownership to cache */
- list_add ( &arp->list, &arp_entries );
-
- DBGC ( arp, "ARP %p %s %s %s created\n", arp, netdev->name,
- net_protocol->name, net_protocol->ntoa ( net_dest ) );
- return arp;
- }
-
- /**
- * Find entry in the ARP cache
- *
- * @v netdev Network device
- * @v net_protocol Network-layer protocol
- * @v net_dest Destination network-layer address
- * @ret arp ARP cache entry, or NULL if not found
- */
- static struct arp_entry * arp_find ( struct net_device *netdev,
- struct net_protocol *net_protocol,
- const void *net_dest ) {
- struct arp_entry *arp;
-
- list_for_each_entry ( arp, &arp_entries, list ) {
- if ( ( arp->netdev == netdev ) &&
- ( arp->net_protocol == net_protocol ) &&
- ( memcmp ( arp->net_dest, net_dest,
- net_protocol->net_addr_len ) == 0 ) ) {
-
- /* Move to start of cache */
- list_del ( &arp->list );
- list_add ( &arp->list, &arp_entries );
-
- return arp;
- }
- }
- return NULL;
- }
-
- /**
- * Destroy ARP cache entry
- *
- * @v arp ARP cache entry
- * @v rc Reason for destruction
- */
- static void arp_destroy ( struct arp_entry *arp, int rc ) {
- struct net_device *netdev = arp->netdev;
- struct net_protocol *net_protocol = arp->net_protocol;
- struct io_buffer *iobuf;
-
- /* Take ownership from cache */
- list_del ( &arp->list );
-
- /* Stop timer */
- stop_timer ( &arp->timer );
-
- /* Discard any outstanding I/O buffers */
- while ( ( iobuf = list_first_entry ( &arp->tx_queue, struct io_buffer,
- list ) ) != NULL ) {
- DBGC2 ( arp, "ARP %p %s %s %s discarding deferred packet: "
- "%s\n", arp, netdev->name, net_protocol->name,
- net_protocol->ntoa ( arp->net_dest ), strerror ( rc ) );
- list_del ( &iobuf->list );
- netdev_tx_err ( arp->netdev, iobuf, rc );
- }
-
- DBGC ( arp, "ARP %p %s %s %s destroyed: %s\n", arp, netdev->name,
- net_protocol->name, net_protocol->ntoa ( arp->net_dest ),
- strerror ( rc ) );
-
- /* Drop remaining reference */
- ref_put ( &arp->refcnt );
- }
-
- /**
- * Test if ARP cache entry has a valid link-layer address
- *
- * @v arp ARP cache entry
- * @ret resolved ARP cache entry is resolved
- */
- static inline int arp_resolved ( struct arp_entry *arp ) {
- return ( ! timer_running ( &arp->timer ) );
- }
-
- /**
- * Transmit packet, determining link-layer address via ARP
- *
- * @v iobuf I/O buffer
- * @v netdev Network device
- * @v net_protocol Network-layer protocol
- * @v net_dest Destination network-layer address
- * @v net_source Source network-layer address
- * @v ll_source Source link-layer address
- * @ret rc Return status code
- */
- int arp_tx ( struct io_buffer *iobuf, struct net_device *netdev,
- struct net_protocol *net_protocol, const void *net_dest,
- const void *net_source, const void *ll_source ) {
- struct arp_entry *arp;
-
- /* Find or create ARP cache entry */
- arp = arp_find ( netdev, net_protocol, net_dest );
- if ( ! arp ) {
- arp = arp_create ( netdev, net_protocol, net_dest,
- net_source );
- if ( ! arp )
- return -ENOMEM;
- }
-
- /* If a link-layer address is available then transmit
- * immediately, otherwise queue for later transmission.
- */
- if ( arp_resolved ( arp ) ) {
- return net_tx ( iobuf, netdev, net_protocol, arp->ll_dest,
- ll_source );
- } else {
- DBGC2 ( arp, "ARP %p %s %s %s deferring packet\n",
- arp, netdev->name, net_protocol->name,
- net_protocol->ntoa ( net_dest ) );
- list_add_tail ( &iobuf->list, &arp->tx_queue );
- return -EAGAIN;
- }
- }
-
- /**
- * Update ARP cache entry
- *
- * @v arp ARP cache entry
- * @v ll_dest Destination link-layer address
- */
- static void arp_update ( struct arp_entry *arp, const void *ll_dest ) {
- struct net_device *netdev = arp->netdev;
- struct ll_protocol *ll_protocol = netdev->ll_protocol;
- struct net_protocol *net_protocol = arp->net_protocol;
- struct io_buffer *iobuf;
- int rc;
-
- DBGC ( arp, "ARP %p %s %s %s updated => %s\n", arp, netdev->name,
- net_protocol->name, net_protocol->ntoa ( arp->net_dest ),
- ll_protocol->ntoa ( ll_dest ) );
-
- /* Fill in link-layer address */
- memcpy ( arp->ll_dest, ll_dest, ll_protocol->ll_addr_len );
-
- /* Stop retransmission timer */
- stop_timer ( &arp->timer );
-
- /* Transmit any packets in queue. Take out a temporary
- * reference on the entry to prevent it from going out of
- * scope during the call to net_tx().
- */
- ref_get ( &arp->refcnt );
- while ( ( iobuf = list_first_entry ( &arp->tx_queue, struct io_buffer,
- list ) ) != NULL ) {
- DBGC2 ( arp, "ARP %p %s %s %s transmitting deferred packet\n",
- arp, netdev->name, net_protocol->name,
- net_protocol->ntoa ( arp->net_dest ) );
- list_del ( &iobuf->list );
- if ( ( rc = net_tx ( iobuf, netdev, net_protocol, ll_dest,
- netdev->ll_addr ) ) != 0 ) {
- DBGC ( arp, "ARP %p could not transmit deferred "
- "packet: %s\n", arp, strerror ( rc ) );
- /* Ignore error and continue */
- }
- }
- ref_put ( &arp->refcnt );
- }
-
- /**
- * Handle ARP timer expiry
- *
- * @v timer Retry timer
- * @v fail Failure indicator
- */
- static void arp_expired ( struct retry_timer *timer, int fail ) {
- struct arp_entry *arp = container_of ( timer, struct arp_entry, timer );
- struct net_device *netdev = arp->netdev;
- struct ll_protocol *ll_protocol = netdev->ll_protocol;
- struct net_protocol *net_protocol = arp->net_protocol;
- struct io_buffer *iobuf;
- struct arphdr *arphdr;
- int rc;
-
- /* If we have failed, destroy the cache entry */
- if ( fail ) {
- arp_destroy ( arp, -ETIMEDOUT );
- return;
- }
-
- /* Restart the timer */
- start_timer ( &arp->timer );
-
- /* Allocate ARP packet */
- iobuf = alloc_iob ( MAX_LL_HEADER_LEN + sizeof ( *arphdr ) +
- ( 2 * ( MAX_LL_ADDR_LEN + MAX_NET_ADDR_LEN ) ) );
- if ( ! iobuf ) {
- /* Leave timer running and try again later */
- return;
- }
- iob_reserve ( iobuf, MAX_LL_HEADER_LEN );
-
- /* Build up ARP request */
- arphdr = iob_put ( iobuf, sizeof ( *arphdr ) );
- arphdr->ar_hrd = ll_protocol->ll_proto;
- arphdr->ar_hln = ll_protocol->ll_addr_len;
- arphdr->ar_pro = net_protocol->net_proto;
- arphdr->ar_pln = net_protocol->net_addr_len;
- arphdr->ar_op = htons ( ARPOP_REQUEST );
- memcpy ( iob_put ( iobuf, ll_protocol->ll_addr_len ),
- netdev->ll_addr, ll_protocol->ll_addr_len );
- memcpy ( iob_put ( iobuf, net_protocol->net_addr_len ),
- arp->net_source, net_protocol->net_addr_len );
- memset ( iob_put ( iobuf, ll_protocol->ll_addr_len ),
- 0, ll_protocol->ll_addr_len );
- memcpy ( iob_put ( iobuf, net_protocol->net_addr_len ),
- arp->net_dest, net_protocol->net_addr_len );
-
- /* Transmit ARP request */
- if ( ( rc = net_tx ( iobuf, netdev, &arp_protocol,
- netdev->ll_broadcast, netdev->ll_addr ) ) != 0 ) {
- DBGC ( arp, "ARP %p could not transmit request: %s\n",
- arp, strerror ( rc ) );
- return;
- }
- }
-
- /**
- * Identify ARP protocol
- *
- * @v net_proto Network-layer protocol, in network-endian order
- * @ret arp_net_protocol ARP protocol, or NULL
- *
- */
- static struct arp_net_protocol * arp_find_protocol ( uint16_t net_proto ) {
- struct arp_net_protocol *arp_net_protocol;
-
- for_each_table_entry ( arp_net_protocol, ARP_NET_PROTOCOLS ) {
- if ( arp_net_protocol->net_protocol->net_proto == net_proto ) {
- return arp_net_protocol;
- }
- }
- return NULL;
- }
-
- /**
- * Process incoming ARP packets
- *
- * @v iobuf I/O buffer
- * @v netdev Network device
- * @v ll_source Link-layer source address
- * @v flags Packet flags
- * @ret rc Return status code
- */
- static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
- const void *ll_dest __unused,
- const void *ll_source __unused,
- unsigned int flags __unused ) {
- struct arphdr *arphdr = iobuf->data;
- struct arp_net_protocol *arp_net_protocol;
- struct net_protocol *net_protocol;
- struct ll_protocol *ll_protocol;
- struct arp_entry *arp;
- int rc;
-
- /* Identify network-layer and link-layer protocols */
- arp_net_protocol = arp_find_protocol ( arphdr->ar_pro );
- if ( ! arp_net_protocol ) {
- rc = -EPROTONOSUPPORT;
- goto done;
- }
- net_protocol = arp_net_protocol->net_protocol;
- ll_protocol = netdev->ll_protocol;
-
- /* Sanity checks */
- if ( ( arphdr->ar_hrd != ll_protocol->ll_proto ) ||
- ( arphdr->ar_hln != ll_protocol->ll_addr_len ) ||
- ( arphdr->ar_pln != net_protocol->net_addr_len ) ) {
- rc = -EINVAL;
- goto done;
- }
-
- /* See if we have an entry for this sender, and update it if so */
- arp = arp_find ( netdev, net_protocol, arp_sender_pa ( arphdr ) );
- if ( arp ) {
- arp_update ( arp, arp_sender_ha ( arphdr ) );
- }
-
- /* If it's not a request, there's nothing more to do */
- if ( arphdr->ar_op != htons ( ARPOP_REQUEST ) ) {
- rc = 0;
- goto done;
- }
-
- /* See if we own the target protocol address */
- if ( arp_net_protocol->check ( netdev, arp_target_pa ( arphdr ) ) != 0){
- rc = 0;
- goto done;
- }
-
- /* Change request to a reply */
- DBGC ( netdev, "ARP reply %s %s %s => %s %s\n",
- netdev->name, net_protocol->name,
- net_protocol->ntoa ( arp_target_pa ( arphdr ) ),
- ll_protocol->name, ll_protocol->ntoa ( netdev->ll_addr ) );
- arphdr->ar_op = htons ( ARPOP_REPLY );
- memswap ( arp_sender_ha ( arphdr ), arp_target_ha ( arphdr ),
- arphdr->ar_hln + arphdr->ar_pln );
- memcpy ( arp_sender_ha ( arphdr ), netdev->ll_addr, arphdr->ar_hln );
-
- /* Send reply */
- if ( ( rc = net_tx ( iob_disown ( iobuf ), netdev, &arp_protocol,
- arp_target_ha ( arphdr ),
- netdev->ll_addr ) ) != 0 ) {
- DBGC ( netdev, "ARP could not transmit reply via %s: %s\n",
- netdev->name, strerror ( rc ) );
- goto done;
- }
-
- /* Success */
- rc = 0;
-
- done:
- free_iob ( iobuf );
- return rc;
- }
-
- /**
- * Transcribe ARP address
- *
- * @v net_addr ARP address
- * @ret string "<ARP>"
- *
- * This operation is meaningless for the ARP protocol.
- */
- static const char * arp_ntoa ( const void *net_addr __unused ) {
- return "<ARP>";
- }
-
- /** ARP protocol */
- struct net_protocol arp_protocol __net_protocol = {
- .name = "ARP",
- .net_proto = htons ( ETH_P_ARP ),
- .rx = arp_rx,
- .ntoa = arp_ntoa,
- };
-
- /**
- * Update ARP cache on network device creation
- *
- * @v netdev Network device
- */
- static int arp_probe ( struct net_device *netdev __unused ) {
- /* Nothing to do */
- return 0;
- }
-
- /**
- * Update ARP cache on network device state change or removal
- *
- * @v netdev Network device
- */
- static void arp_flush ( struct net_device *netdev ) {
- struct arp_entry *arp;
- struct arp_entry *tmp;
-
- /* Remove all ARP cache entries when a network device is closed */
- if ( ! netdev_is_open ( netdev ) ) {
- list_for_each_entry_safe ( arp, tmp, &arp_entries, list )
- arp_destroy ( arp, -ENODEV );
- }
- }
-
- /** 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,
- };
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