/*
* Copyright (C) 2013 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.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <ipxe/iobuf.h>
#include <ipxe/retry.h>
#include <ipxe/timer.h>
#include <ipxe/malloc.h>
#include <ipxe/neighbour.h>
/** @file
*
* Neighbour discovery
*
* This file implements the abstract functions of neighbour discovery,
* independent of the underlying network protocol (e.g. ARP or NDP).
*
*/
/** Neighbour discovery minimum timeout */
#define NEIGHBOUR_MIN_TIMEOUT ( TICKS_PER_SEC / 8 )
/** Neighbour discovery maximum timeout */
#define NEIGHBOUR_MAX_TIMEOUT ( TICKS_PER_SEC * 3 )
/** The neighbour cache */
struct list_head neighbours = LIST_HEAD_INIT ( neighbours );
static void neighbour_expired ( struct retry_timer *timer, int over );
/**
* Free neighbour cache entry
*
* @v refcnt Reference count
*/
static void neighbour_free ( struct refcnt *refcnt ) {
struct neighbour *neighbour =
container_of ( refcnt, struct neighbour, refcnt );
/* Sanity check */
assert ( list_empty ( &neighbour->tx_queue ) );
/* Drop reference to network device */
netdev_put ( neighbour->netdev );
/* Free neighbour */
free ( neighbour );
}
/**
* Create neighbour cache entry
*
* @v netdev Network device
* @v net_protocol Network-layer protocol
* @v net_dest Destination network-layer address
* @ret neighbour Neighbour cache entry, or NULL if allocation failed
*/
static struct neighbour * neighbour_create ( struct net_device *netdev,
struct net_protocol *net_protocol,
const void *net_dest ) {
struct neighbour *neighbour;
/* Allocate and initialise entry */
neighbour = zalloc ( sizeof ( *neighbour ) );
if ( ! neighbour )
return NULL;
ref_init ( &neighbour->refcnt, neighbour_free );
neighbour->netdev = netdev_get ( netdev );
neighbour->net_protocol = net_protocol;
memcpy ( neighbour->net_dest, net_dest,
net_protocol->net_addr_len );
timer_init ( &neighbour->timer, neighbour_expired, &neighbour->refcnt );
set_timer_limits ( &neighbour->timer, NEIGHBOUR_MIN_TIMEOUT,
NEIGHBOUR_MAX_TIMEOUT );
INIT_LIST_HEAD ( &neighbour->tx_queue );
/* Transfer ownership to cache */
list_add ( &neighbour->list, &neighbours );
DBGC ( neighbour, "NEIGHBOUR %s %s %s created\n", netdev->name,
net_protocol->name, net_protocol->ntoa ( net_dest ) );
return neighbour;
}
/**
* Find neighbour cache entry
*
* @v netdev Network device
* @v net_protocol Network-layer protocol
* @v net_dest Destination network-layer address
* @ret neighbour Neighbour cache entry, or NULL if not found
*/
static struct neighbour * neighbour_find ( struct net_device *netdev,
struct net_protocol *net_protocol,
const void *net_dest ) {
struct neighbour *neighbour;
list_for_each_entry ( neighbour, &neighbours, list ) {
if ( ( neighbour->netdev == netdev ) &&
( neighbour->net_protocol == net_protocol ) &&
( memcmp ( neighbour->net_dest, net_dest,
net_protocol->net_addr_len ) == 0 ) ) {
/* Move to start of cache */
list_del ( &neighbour->list );
list_add ( &neighbour->list, &neighbours );
return neighbour;
}
}
return NULL;
}
/**
* Start neighbour discovery
*
* @v neighbour Neighbour cache entry
* @v discovery Neighbour discovery protocol
* @v net_source Source network-layer address
*/
static void neighbour_discover ( struct neighbour *neighbour,
struct neighbour_discovery *discovery,
const void *net_source ) {
struct net_device *netdev = neighbour->netdev;
struct net_protocol *net_protocol = neighbour->net_protocol;
/* Record discovery protocol and source network-layer address */
neighbour->discovery = discovery;
memcpy ( neighbour->net_source, net_source,
net_protocol->net_addr_len );
/* Start timer to trigger neighbour discovery */
start_timer_nodelay ( &neighbour->timer );
DBGC ( neighbour, "NEIGHBOUR %s %s %s discovering via %s\n",
netdev->name, net_protocol->name,
net_protocol->ntoa ( neighbour->net_dest ),
neighbour->discovery->name );
}
/**
* Complete neighbour discovery
*
* @v neighbour Neighbour cache entry
* @v ll_dest Destination link-layer address
*/
static void neighbour_discovered ( struct neighbour *neighbour,
const void *ll_dest ) {
struct net_device *netdev = neighbour->netdev;
struct ll_protocol *ll_protocol = netdev->ll_protocol;
struct net_protocol *net_protocol = neighbour->net_protocol;
struct io_buffer *iobuf;
int rc;
/* Fill in link-layer address */
memcpy ( neighbour->ll_dest, ll_dest, ll_protocol->ll_addr_len );
DBGC ( neighbour, "NEIGHBOUR %s %s %s is %s %s\n", netdev->name,
net_protocol->name, net_protocol->ntoa ( neighbour->net_dest ),
ll_protocol->name, ll_protocol->ntoa ( neighbour->ll_dest ) );
/* Stop retransmission timer */
stop_timer ( &neighbour->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 ( &neighbour->refcnt );
while ( ( iobuf = list_first_entry ( &neighbour->tx_queue,
struct io_buffer, list )) != NULL){
DBGC2 ( neighbour, "NEIGHBOUR %s %s %s transmitting deferred "
"packet\n", netdev->name, net_protocol->name,
net_protocol->ntoa ( neighbour->net_dest ) );
list_del ( &iobuf->list );
if ( ( rc = net_tx ( iobuf, netdev, net_protocol, ll_dest,
netdev->ll_addr ) ) != 0 ) {
DBGC ( neighbour, "NEIGHBOUR %s %s %s could not "
"transmit deferred packet: %s\n",
netdev->name, net_protocol->name,
net_protocol->ntoa ( neighbour->net_dest ),
strerror ( rc ) );
/* Ignore error and continue */
}
}
ref_put ( &neighbour->refcnt );
}
/**
* Destroy neighbour cache entry
*
* @v neighbour Neighbour cache entry
* @v rc Reason for destruction
*/
static void neighbour_destroy ( struct neighbour *neighbour, int rc ) {
struct net_device *netdev = neighbour->netdev;
struct net_protocol *net_protocol = neighbour->net_protocol;
struct io_buffer *iobuf;
/* Take ownership from cache */
list_del ( &neighbour->list );
/* Stop timer */
stop_timer ( &neighbour->timer );
/* Discard any outstanding I/O buffers */
while ( ( iobuf = list_first_entry ( &neighbour->tx_queue,
struct io_buffer, list )) != NULL){
DBGC2 ( neighbour, "NEIGHBOUR %s %s %s discarding deferred "
"packet: %s\n", netdev->name, net_protocol->name,
net_protocol->ntoa ( neighbour->net_dest ),
strerror ( rc ) );
list_del ( &iobuf->list );
netdev_tx_err ( neighbour->netdev, iobuf, rc );
}
DBGC ( neighbour, "NEIGHBOUR %s %s %s destroyed: %s\n", netdev->name,
net_protocol->name, net_protocol->ntoa ( neighbour->net_dest ),
strerror ( rc ) );
/* Drop remaining reference */
ref_put ( &neighbour->refcnt );
}
/**
* Handle neighbour timer expiry
*
* @v timer Retry timer
* @v fail Failure indicator
*/
static void neighbour_expired ( struct retry_timer *timer, int fail ) {
struct neighbour *neighbour =
container_of ( timer, struct neighbour, timer );
struct net_device *netdev = neighbour->netdev;
struct net_protocol *net_protocol = neighbour->net_protocol;
struct neighbour_discovery *discovery =
neighbour->discovery;
const void *net_dest = neighbour->net_dest;
const void *net_source = neighbour->net_source;
int rc;
/* If we have failed, destroy the cache entry */
if ( fail ) {
neighbour_destroy ( neighbour, -ETIMEDOUT );
return;
}
/* Restart the timer */
start_timer ( &neighbour->timer );
/* Transmit neighbour request */
if ( ( rc = discovery->tx_request ( netdev, net_protocol, net_dest,
net_source ) ) != 0 ) {
DBGC ( neighbour, "NEIGHBOUR %s %s %s could not transmit %s "
"request: %s\n", netdev->name, net_protocol->name,
net_protocol->ntoa ( neighbour->net_dest ),
neighbour->discovery->name, strerror ( rc ) );
/* Retransmit when timer expires */
return;
}
}
/**
* Transmit packet, determining link-layer address via neighbour discovery
*
* @v iobuf I/O buffer
* @v netdev Network device
* @v discovery Neighbour discovery protocol
* @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 neighbour_tx ( struct io_buffer *iobuf, struct net_device *netdev,
struct net_protocol *net_protocol, const void *net_dest,
struct neighbour_discovery *discovery,
const void *net_source, const void *ll_source ) {
struct neighbour *neighbour;
/* Find or create neighbour cache entry */
neighbour = neighbour_find ( netdev, net_protocol, net_dest );
if ( ! neighbour ) {
neighbour = neighbour_create ( netdev, net_protocol, net_dest );
if ( ! neighbour )
return -ENOMEM;
neighbour_discover ( neighbour, discovery, net_source );
}
/* If a link-layer address is available then transmit
* immediately, otherwise queue for later transmission.
*/
if ( neighbour_has_ll_dest ( neighbour ) ) {
return net_tx ( iobuf, netdev, net_protocol, neighbour->ll_dest,
ll_source );
} else {
DBGC2 ( neighbour, "NEIGHBOUR %s %s %s deferring packet\n",
netdev->name, net_protocol->name,
net_protocol->ntoa ( net_dest ) );
list_add_tail ( &iobuf->list, &neighbour->tx_queue );
return 0;
}
}
/**
* Update existing neighbour cache entry
*
* @v netdev Network device
* @v net_protocol Network-layer protocol
* @v net_dest Destination network-layer address
* @v ll_dest Destination link-layer address
* @ret rc Return status code
*/
int neighbour_update ( struct net_device *netdev,
struct net_protocol *net_protocol,
const void *net_dest, const void *ll_dest ) {
struct neighbour *neighbour;
/* Find neighbour cache entry */
neighbour = neighbour_find ( netdev, net_protocol, net_dest );
if ( ! neighbour )
return -ENOENT;
/* Set destination address */
neighbour_discovered ( neighbour, ll_dest );
return 0;
}
/**
* Define neighbour cache entry
*
* @v netdev Network device
* @v net_protocol Network-layer protocol
* @v net_dest Destination network-layer address
* @v ll_dest Destination link-layer address, if known
* @ret rc Return status code
*/
int neighbour_define ( struct net_device *netdev,
struct net_protocol *net_protocol,
const void *net_dest, const void *ll_dest ) {
struct neighbour *neighbour;
/* Find or create neighbour cache entry */
neighbour = neighbour_find ( netdev, net_protocol, net_dest );
if ( ! neighbour ) {
neighbour = neighbour_create ( netdev, net_protocol, net_dest );
if ( ! neighbour )
return -ENOMEM;
}
/* Set destination address */
neighbour_discovered ( neighbour, ll_dest );
return 0;
}
/**
* Update neighbour cache on network device state change or removal
*
* @v netdev Network device
*/
static void neighbour_flush ( struct net_device *netdev ) {
struct neighbour *neighbour;
struct neighbour *tmp;
/* Remove all neighbour cache entries when a network device is closed */
if ( ! netdev_is_open ( netdev ) ) {
list_for_each_entry_safe ( neighbour, tmp, &neighbours, list )
neighbour_destroy ( neighbour, -ENODEV );
}
}
/** Neighbour driver (for net device notifications) */
struct net_driver neighbour_net_driver __net_driver = {
.name = "Neighbour",
.notify = neighbour_flush,
.remove = neighbour_flush,
};
/**
* Discard some cached neighbour entries
*
* @ret discarded Number of cached items discarded
*/
static unsigned int neighbour_discard ( void ) {
struct neighbour *neighbour;
/* Drop oldest cache entry, if any */
neighbour = list_last_entry ( &neighbours, struct neighbour, list );
if ( neighbour ) {
neighbour_destroy ( neighbour, -ENOBUFS );
return 1;
} else {
return 0;
}
}
/**
* Neighbour cache discarder
*
* Neighbour cache entries are deemed to have a high replacement cost,
* since flushing an active neighbour cache entry midway through a TCP
* transfer will cause substantial disruption.
*/
struct cache_discarder neighbour_discarder __cache_discarder (CACHE_EXPENSIVE)={
.discard = neighbour_discard,
};
