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[neighbour] Generalise concept of neighbour discovery

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Split the protocol-independent portions of arp.c into a separate file
neighbour.c, to allow for sharing of functionality between IPv4+ARP
and IPv6+NDP.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2013-09-01 16:13:58 +01:00
parent 6bf36f57a0
commit c6a04085d2
5 changed files with 579 additions and 357 deletions
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24
src/include/ipxe/arp.h
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@ -11,6 +11,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
#include <ipxe/tables.h>
#include <ipxe/netdevice.h>
#include <ipxe/neighbour.h>
/** A network-layer protocol that relies upon ARP */
struct arp_net_protocol {
@ -34,9 +35,26 @@ struct arp_net_protocol {
#define __arp_net_protocol __table_entry ( ARP_NET_PROTOCOLS, 01 )
extern struct net_protocol arp_protocol __net_protocol;
extern struct neighbour_discovery arp_discovery;
extern 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 );
/**
* 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
*/
static inline 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 ) {
return neighbour_tx ( iobuf, netdev, net_protocol, net_dest,
&arp_discovery, net_source, ll_source );
}
#endif /* _IPXE_ARP_H */

1
src/include/ipxe/errfile.h
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@ -214,6 +214,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
#define ERRFILE_nfs_open ( ERRFILE_NET | 0x00340000 )
#define ERRFILE_mount ( ERRFILE_NET | 0x00350000 )
#define ERRFILE_oncrpc_iob ( ERRFILE_NET | 0x00360000 )
#define ERRFILE_neighbour ( ERRFILE_NET | 0x00370000 )
#define ERRFILE_image ( ERRFILE_IMAGE | 0x00000000 )
#define ERRFILE_elf ( ERRFILE_IMAGE | 0x00010000 )

44
src/include/ipxe/neighbour.h Normal file
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@ -0,0 +1,44 @@
#ifndef _IPXE_NEIGHBOUR_H
#define _IPXE_NEIGHBOUR_H
/** @file
*
* Neighbour discovery
*
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <ipxe/netdevice.h>
/** A neighbour discovery protocol */
struct neighbour_discovery {
/** Name */
const char *name;
/**
* Transmit neighbour discovery 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
*/
int ( * tx_request ) ( struct net_device *netdev,
struct net_protocol *net_protocol,
const void *net_dest, const void *net_source );
};
extern 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 );
extern int neighbour_update ( struct net_device *netdev,
struct net_protocol *net_protocol,
const void *net_dest, const void *ll_dest );
extern int neighbour_define ( struct net_device *netdev,
struct net_protocol *net_protocol,
const void *net_dest, const void *ll_dest );
#endif /* _IPXE_NEIGHBOUR_H */

388
src/net/arp.c
View File

@ -28,11 +28,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
#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/neighbour.h>
#include <ipxe/arp.h>
/** @file
@ -45,291 +41,30 @@ FILE_LICENCE ( GPL2_OR_LATER );
*
*/
/** 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
* 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 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;
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 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;
}
if ( ! iobuf )
return -ENOMEM;
iob_reserve ( iobuf, MAX_LL_HEADER_LEN );
/* Build up ARP request */
@ -342,21 +77,30 @@ static void arp_expired ( struct retry_timer *timer, int fail ) {
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 );
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 );
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;
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
*
@ -368,9 +112,8 @@ 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 ) {
if ( arp_net_protocol->net_protocol->net_proto == net_proto )
return arp_net_protocol;
}
}
return NULL;
}
@ -392,7 +135,6 @@ static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
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 */
@ -412,11 +154,9 @@ static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
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 ) );
}
/* 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 ) ) {
@ -431,10 +171,10 @@ static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
}
/* 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 ) );
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 );
@ -444,8 +184,10 @@ static int arp_rx ( struct io_buffer *iobuf, struct net_device *netdev,
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 ) );
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;
}
@ -469,72 +211,10 @@ static const char * arp_ntoa ( const void *net_addr __unused ) {
return "<ARP>";
}
/** ARP protocol */
/** ARP network 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,
};

479
src/net/neighbour.c Normal file
View File

@ -0,0 +1,479 @@
/*
* 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/refcnt.h>
#include <ipxe/list.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).
*
*/
/** A neighbour cache entry */
struct neighbour {
/** Reference count */
struct refcnt refcnt;
/** List of neighbour 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];
/** Link-layer destination address */
uint8_t ll_dest[MAX_LL_ADDR_LEN];
/** Neighbour discovery protocol (if any) */
struct neighbour_discovery *discovery;
/** Network-layer source address (if any) */
uint8_t net_source[MAX_NET_ADDR_LEN];
/** Retransmission timer */
struct retry_timer timer;
/** Pending I/O buffers */
struct list_head tx_queue;
};
/** 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 */
static LIST_HEAD ( 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 );
}
/**
* Test if neighbour cache entry has a valid link-layer address
*
* @v neighbour Neighbour cache entry
* @ret has_ll_dest Neighbour cache entry has a valid link-layer address
*/
static inline __attribute__ (( always_inline )) int
neighbour_has_ll_dest ( struct neighbour *neighbour ) {
return ( ! timer_running ( &neighbour->timer ) );
}
/**
* 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 creation
*
* @v netdev Network device
*/
static int neighbour_probe ( struct net_device *netdev __unused ) {
/* Nothing to do */
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",
.probe = neighbour_probe,
.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,
};