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git.ipfire.org Git - thirdparty/bird.git/blob - nest/neighbor.c
2 * BIRD -- Neighbor Cache
4 * (c) 1998--2000 Martin Mares <mj@ucw.cz>
6 * Can be freely distributed and used under the terms of the GNU GPL.
12 * Most routing protocols need to associate their internal state data with
13 * neighboring routers, check whether an address given as the next hop
14 * attribute of a route is really an address of a directly connected host
15 * and which interface is it connected through. Also, they often need to
16 * be notified when a neighbor ceases to exist or when their long awaited
17 * neighbor becomes connected. The neighbor cache is there to solve all
20 * The neighbor cache maintains a collection of neighbor entries. Each
21 * entry represents one IP address corresponding to either our directly
22 * connected neighbor or our own end of the link (when the scope of the
23 * address is set to %SCOPE_HOST) together with per-neighbor data belonging to a
26 * Active entries represent known neighbors and are stored in a hash
27 * table (to allow fast retrieval based on the IP address of the node) and
28 * two linked lists: one global and one per-interface (allowing quick
29 * processing of interface change events). Inactive entries exist only
30 * when the protocol has explicitly requested it via the %NEF_STICKY
31 * flag because it wishes to be notified when the node will again become
32 * a neighbor. Such entries are enqueued in a special list which is walked
33 * whenever an interface changes its state to up.
35 * When a neighbor event occurs (a neighbor gets disconnected or a sticky
36 * inactive neighbor becomes connected), the protocol hook neigh_notify()
37 * is called to advertise the change.
42 #include "nest/bird.h"
43 #include "nest/iface.h"
44 #include "nest/protocol.h"
45 #include "lib/resource.h"
47 #define NEIGH_HASH_SIZE 256
49 static slab
*neigh_slab
;
50 static list sticky_neigh_list
, neigh_hash_table
[NEIGH_HASH_SIZE
];
53 neigh_hash(struct proto
*p
, ip_addr
*a
)
55 return (p
->hash_key
^ ipa_hash(*a
)) & (NEIGH_HASH_SIZE
-1);
59 if_connected(ip_addr
*a
, struct iface
*i
, struct ifa
**ap
)
63 if (!(i
->flags
& IF_UP
))
69 WALK_LIST(b
, i
->addrs
)
73 if (ipa_equal(*a
, b
->ip
))
75 if (b
->flags
& IA_PEER
)
77 if (ipa_equal(*a
, b
->opposite
))
82 if (ipa_in_net(*a
, b
->prefix
, b
->pxlen
))
85 if ((b
->pxlen
< (BITS_PER_IP_ADDRESS
- 1)) &&
86 (ipa_equal(*a
, b
->prefix
) || /* Network address */
87 ipa_equal(*a
, b
->brd
))) /* Broadcast */
104 * neigh_find - find or create a neighbor entry.
105 * @p: protocol which asks for the entry.
106 * @a: pointer to IP address of the node to be searched for.
107 * @flags: 0 or %NEF_STICKY if you want to create a sticky entry.
109 * Search the neighbor cache for a node with given IP address. If
110 * it's found, a pointer to the neighbor entry is returned. If no
111 * such entry exists and the node is directly connected on
112 * one of our active interfaces, a new entry is created and returned
113 * to the caller with protocol-dependent fields initialized to zero.
114 * If the node is not connected directly or *@a is not a valid unicast
115 * IP address, neigh_find() returns %NULL.
118 neigh_find(struct proto
*p
, ip_addr
*a
, unsigned flags
)
120 return neigh_find2(p
, a
, NULL
, flags
);
125 neigh_find2(struct proto
*p
, ip_addr
*a
, struct iface
*ifa
, unsigned flags
)
128 int class, scope
= -1;
129 uint h
= neigh_hash(p
, a
);
133 WALK_LIST(n
, neigh_hash_table
[h
]) /* Search the cache */
134 if (n
->proto
== p
&& ipa_equal(*a
, n
->addr
) && (!ifa
|| (ifa
== n
->iface
)))
137 class = ipa_classify(*a
);
138 if (class < 0) /* Invalid address */
140 if (((class & IADDR_SCOPE_MASK
) == SCOPE_HOST
) ||
141 (((class & IADDR_SCOPE_MASK
) == SCOPE_LINK
) && (ifa
== NULL
)) ||
142 !(class & IADDR_HOST
))
143 return NULL
; /* Bad scope or a somecast */
147 scope
= if_connected(a
, ifa
, &addr
);
150 if ((scope
< 0) && (flags
& NEF_ONLINK
))
151 scope
= class & IADDR_SCOPE_MASK
;
154 WALK_LIST(i
, iface_list
)
155 if ((scope
= if_connected(a
, i
, &addr
)) >= 0)
161 /* scope < 0 means i don't know neighbor */
162 /* scope >= 0 implies ifa != NULL */
164 if ((scope
< 0) && !(flags
& NEF_STICKY
))
167 n
= sl_alloc(neigh_slab
);
171 add_tail(&neigh_hash_table
[h
], &n
->n
);
172 add_tail(&ifa
->neighbors
, &n
->if_n
);
176 add_tail(&sticky_neigh_list
, &n
->n
);
190 * neigh_dump - dump specified neighbor entry.
191 * @n: the entry to dump
193 * This functions dumps the contents of a given neighbor entry
197 neigh_dump(neighbor
*n
)
199 debug("%p %I ", n
, n
->addr
);
201 debug("%s ", n
->iface
->name
);
204 debug("%s %p %08x scope %s", n
->proto
->name
, n
->data
, n
->aux
, ip_scope_text(n
->scope
));
205 if (n
->flags
& NEF_STICKY
)
211 * neigh_dump_all - dump all neighbor entries.
213 * This function dumps the contents of the neighbor cache to
222 debug("Known neighbors:\n");
223 WALK_LIST(n
, sticky_neigh_list
)
225 for(i
=0; i
<NEIGH_HASH_SIZE
; i
++)
226 WALK_LIST(n
, neigh_hash_table
[i
])
232 neigh_up(neighbor
*n
, struct iface
*i
, int scope
, struct ifa
*a
)
237 add_tail(&i
->neighbors
, &n
->if_n
);
239 add_tail(&neigh_hash_table
[neigh_hash(n
->proto
, &n
->addr
)], &n
->n
);
240 DBG("Waking up sticky neighbor %I\n", n
->addr
);
241 if (n
->proto
->neigh_notify
&& n
->proto
->core_state
!= FS_FLUSHING
)
242 n
->proto
->neigh_notify(n
);
246 neigh_down(neighbor
*n
)
248 DBG("Flushing neighbor %I on %s\n", n
->addr
, n
->iface
->name
);
250 if (! (n
->flags
& NEF_BIND
))
254 if (n
->proto
->neigh_notify
&& n
->proto
->core_state
!= FS_FLUSHING
)
255 n
->proto
->neigh_notify(n
);
257 if (n
->flags
& NEF_STICKY
)
259 add_tail(&sticky_neigh_list
, &n
->n
);
261 /* Respawn neighbor if there is another matching prefix */
267 WALK_LIST(i
, iface_list
)
268 if ((scope
= if_connected(&n
->addr
, i
, &a
)) >= 0)
270 neigh_up(n
, i
, scope
, a
);
275 sl_free(neigh_slab
, n
);
280 * neigh_if_up: notify neighbor cache about interface up event
281 * @i: interface in question
283 * Tell the neighbor cache that a new interface became up.
285 * The neighbor cache wakes up all inactive sticky neighbors with
286 * addresses belonging to prefixes of the interface @i.
289 neigh_if_up(struct iface
*i
)
295 WALK_LIST_DELSAFE(n
, next
, sticky_neigh_list
)
296 if ((!n
->iface
|| n
->iface
== i
) &&
297 ((scope
= if_connected(&n
->addr
, i
, &a
)) >= 0))
298 neigh_up(n
, i
, scope
, a
);
302 * neigh_if_down - notify neighbor cache about interface down event
303 * @i: the interface in question
305 * Notify the neighbor cache that an interface has ceased to exist.
307 * It causes all entries belonging to neighbors connected to this interface
311 neigh_if_down(struct iface
*i
)
315 WALK_LIST_DELSAFE(x
, y
, i
->neighbors
)
316 neigh_down(SKIP_BACK(neighbor
, if_n
, x
));
320 * neigh_if_link - notify neighbor cache about interface link change
321 * @i: the interface in question
323 * Notify the neighbor cache that an interface changed link state.
324 * All owners of neighbor entries connected to this interface are
328 neigh_if_link(struct iface
*i
)
332 WALK_LIST_DELSAFE(x
, y
, i
->neighbors
)
334 neighbor
*n
= SKIP_BACK(neighbor
, if_n
, x
);
335 if (n
->proto
->neigh_notify
&& n
->proto
->core_state
!= FS_FLUSHING
)
336 n
->proto
->neigh_notify(n
);
341 * neigh_ifa_update: notify neighbor cache about interface address add or remove event
342 * @a: interface address in question
344 * Tell the neighbor cache that an address was added or removed.
346 * The neighbor cache wakes up all inactive sticky neighbors with
347 * addresses belonging to prefixes of the interface belonging to @ifa
348 * and causes all unreachable neighbors to be flushed.
351 neigh_ifa_update(struct ifa
*a
)
353 struct iface
*i
= a
->iface
;
356 /* Remove all neighbors whose scope has changed */
357 WALK_LIST_DELSAFE(x
, y
, i
->neighbors
)
360 neighbor
*n
= SKIP_BACK(neighbor
, if_n
, x
);
361 if (if_connected(&n
->addr
, i
, &aa
) != n
->scope
)
365 /* Wake up all sticky neighbors that are reachable now */
370 neigh_prune_one(neighbor
*n
)
372 if (n
->proto
->proto_state
!= PS_DOWN
)
377 sl_free(neigh_slab
, n
);
381 * neigh_prune - prune neighbor cache
383 * neigh_prune() examines all neighbor entries cached and removes those
384 * corresponding to inactive protocols. It's called whenever a protocol
385 * is shut down to get rid of all its heritage.
394 DBG("Pruning neighbors\n");
395 for(i
=0; i
<NEIGH_HASH_SIZE
; i
++)
396 WALK_LIST_DELSAFE(n
, m
, neigh_hash_table
[i
])
398 WALK_LIST_DELSAFE(n
, m
, sticky_neigh_list
)
403 * neigh_init - initialize the neighbor cache.
404 * @if_pool: resource pool to be used for neighbor entries.
406 * This function is called during BIRD startup to initialize
407 * the neighbor cache module.
410 neigh_init(pool
*if_pool
)
414 neigh_slab
= sl_new(if_pool
, sizeof(neighbor
));
415 init_list(&sticky_neigh_list
);
416 for(i
=0; i
<NEIGH_HASH_SIZE
; i
++)
417 init_list(&neigh_hash_table
[i
]);