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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/neighbour.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.
*
*/
struct net_protocol arp_protocol __net_protocol;
/**
* Transmit ARP request
*
* @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 rc Return status code
*/
static int arp_tx_request ( struct net_device *netdev,
struct net_protocol *net_protocol,
const void *net_dest, const void *net_source ) {
struct ll_protocol *ll_protocol = netdev->ll_protocol;
struct io_buffer *iobuf;
struct arphdr *arphdr;
int rc;
/* Allocate ARP packet */
iobuf = alloc_iob ( MAX_LL_HEADER_LEN + sizeof ( *arphdr ) +
( 2 * ( MAX_LL_ADDR_LEN + MAX_NET_ADDR_LEN ) ) );
if ( ! iobuf )
return -ENOMEM;
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 ),
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 ),
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 ( netdev, "ARP %s %s %s could not transmit request: %s\n",
netdev->name, net_protocol->name,
net_protocol->ntoa ( net_dest ), strerror ( rc ) );
return rc;
}
return 0;
}
/** ARP neighbour discovery protocol */
struct neighbour_discovery arp_discovery = {
.name = "ARP",
.tx_request = arp_tx_request,
};
/**
* 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;
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;
}
/* Update neighbour cache entry for this sender, if any */
neighbour_update ( netdev, net_protocol, arp_sender_pa ( arphdr ),
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 */
DBGC2 ( netdev, "ARP %s %s %s reply => %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 %s %s %s could not transmit reply: %s\n",
netdev->name, net_protocol->name,
net_protocol->ntoa ( arp_target_pa ( arphdr ) ),
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 network protocol */
struct net_protocol arp_protocol __net_protocol = {
.name = "ARP",
.net_proto = htons ( ETH_P_ARP ),
.rx = arp_rx,
.ntoa = arp_ntoa,
};
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