diff options
Diffstat (limited to 'qemu/roms/ipxe/src/net/neighbour.c')
| -rw-r--r-- | qemu/roms/ipxe/src/net/neighbour.c | 428 |
1 files changed, 428 insertions, 0 deletions
diff --git a/qemu/roms/ipxe/src/net/neighbour.c b/qemu/roms/ipxe/src/net/neighbour.c new file mode 100644 index 000000000..e3026ce46 --- /dev/null +++ b/qemu/roms/ipxe/src/net/neighbour.c @@ -0,0 +1,428 @@ +/* + * 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. + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +#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 ); + neighbour->timer.min_timeout = NEIGHBOUR_MIN_TIMEOUT; + neighbour->timer.max_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 -EAGAIN; + } +} + +/** + * 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, +}; |