--- /dev/null
+/*
+ * 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,
+};
Code Review / kvmfornfv.git / blobdiff