2 * Copyright (c) 2008, 2009, 2010, 2011 Nicira Networks.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
18 #include "mac-learning.h"
28 #include "poll-loop.h"
32 #include "vlan-bitmap.h"
35 VLOG_DEFINE_THIS_MODULE(mac_learning);
37 COVERAGE_DEFINE(mac_learning_learned);
38 COVERAGE_DEFINE(mac_learning_expired);
40 /* Returns the number of seconds since 'e' was last learned. */
42 mac_entry_age(const struct mac_entry *e)
44 time_t remaining = e->expires - time_now();
45 return MAC_ENTRY_IDLE_TIME - remaining;
49 mac_table_hash(const uint8_t mac[ETH_ADDR_LEN], uint16_t vlan)
51 return hash_bytes(mac, ETH_ADDR_LEN, vlan);
54 static struct mac_entry *
55 mac_entry_from_lru_node(struct list *list)
57 return CONTAINER_OF(list, struct mac_entry, lru_node);
60 /* Returns a tag that represents that 'mac' is on an unknown port in 'vlan'.
61 * (When we learn where 'mac' is in 'vlan', this allows flows that were
62 * flooded to be revalidated.) */
64 make_unknown_mac_tag(const struct mac_learning *ml,
65 const uint8_t mac[ETH_ADDR_LEN], uint16_t vlan)
67 uint32_t h = hash_int(ml->secret, mac_table_hash(mac, vlan));
68 return tag_create_deterministic(h);
72 mac_table_bucket(const struct mac_learning *ml,
73 const uint8_t mac[ETH_ADDR_LEN],
76 uint32_t hash = mac_table_hash(mac, vlan);
77 const struct list *list = &ml->table[hash & MAC_HASH_BITS];
78 return (struct list *) list;
81 static struct mac_entry *
82 search_bucket(struct list *bucket, const uint8_t mac[ETH_ADDR_LEN],
86 LIST_FOR_EACH (e, hash_node, bucket) {
87 if (eth_addr_equals(e->mac, mac) && e->vlan == vlan) {
94 /* If the LRU list is not empty, stores the least-recently-used entry in '*e'
95 * and returns true. Otherwise, if the LRU list is empty, stores NULL in '*e'
96 * and return false. */
98 get_lru(struct mac_learning *ml, struct mac_entry **e)
100 if (!list_is_empty(&ml->lrus)) {
101 *e = mac_entry_from_lru_node(ml->lrus.next);
109 /* Creates and returns a new MAC learning table. */
110 struct mac_learning *
111 mac_learning_create(void)
113 struct mac_learning *ml;
116 ml = xmalloc(sizeof *ml);
117 list_init(&ml->lrus);
118 list_init(&ml->free);
119 for (i = 0; i < MAC_HASH_SIZE; i++) {
120 list_init(&ml->table[i]);
122 for (i = 0; i < MAC_MAX; i++) {
123 struct mac_entry *s = &ml->entries[i];
124 list_push_front(&ml->free, &s->lru_node);
126 ml->secret = random_uint32();
127 ml->flood_vlans = NULL;
131 /* Destroys MAC learning table 'ml'. */
133 mac_learning_destroy(struct mac_learning *ml)
136 bitmap_free(ml->flood_vlans);
141 /* Provides a bitmap of VLANs which have learning disabled, that is, VLANs on
142 * which all packets are flooded. It takes ownership of the bitmap. Returns
143 * true if the set has changed from the previous value. */
145 mac_learning_set_flood_vlans(struct mac_learning *ml, unsigned long *bitmap)
147 bool ret = vlan_bitmap_equal(ml->flood_vlans, bitmap);
149 bitmap_free(ml->flood_vlans);
150 ml->flood_vlans = bitmap;
156 is_learning_vlan(const struct mac_learning *ml, uint16_t vlan)
158 return vlan_bitmap_contains(ml->flood_vlans, vlan);
161 /* Returns true if 'src_mac' may be learned on 'vlan' for 'ml'.
162 * Returns false if 'ml' is NULL, if src_mac is not valid for learning, or if
163 * 'vlan' is configured on 'ml' to flood all packets. */
165 mac_learning_may_learn(const struct mac_learning *ml,
166 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan)
168 return ml && is_learning_vlan(ml, vlan) && !eth_addr_is_multicast(src_mac);
171 /* Searches 'ml' for and returns a MAC learning entry for 'src_mac' in 'vlan',
172 * inserting a new entry if necessary. The caller must have already verified,
173 * by calling mac_learning_may_learn(), that 'src_mac' and 'vlan' are
176 * If the returned MAC entry is new (as may be determined by calling
177 * mac_entry_is_new()), then the caller must pass the new entry to
178 * mac_learning_changed(). The caller must also initialize the new entry's
179 * 'port' member. Otherwise calling those functions is at the caller's
182 mac_learning_insert(struct mac_learning *ml,
183 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan)
188 bucket = mac_table_bucket(ml, src_mac, vlan);
189 e = search_bucket(bucket, src_mac, vlan);
191 if (!list_is_empty(&ml->free)) {
192 e = mac_entry_from_lru_node(ml->free.next);
194 e = mac_entry_from_lru_node(ml->lrus.next);
195 list_remove(&e->hash_node);
197 list_push_front(bucket, &e->hash_node);
198 memcpy(e->mac, src_mac, ETH_ADDR_LEN);
201 e->grat_arp_lock = TIME_MIN;
204 /* Mark 'e' as recently used. */
205 list_remove(&e->lru_node);
206 list_push_back(&ml->lrus, &e->lru_node);
207 e->expires = time_now() + MAC_ENTRY_IDLE_TIME;
212 /* Changes 'e''s tag to a new, randomly selected one, and returns the tag that
213 * would have been previously used for this entry's MAC and VLAN (either before
214 * 'e' was inserted, if it is new, or otherwise before its port was updated.)
216 * The client should call this function after obtaining a MAC learning entry
217 * from mac_learning_insert(), if the entry is either new or if its learned
218 * port has changed. */
220 mac_learning_changed(struct mac_learning *ml, struct mac_entry *e)
222 tag_type old_tag = e->tag;
224 COVERAGE_INC(mac_learning_learned);
226 e->tag = tag_create_random();
227 return old_tag ? old_tag : make_unknown_mac_tag(ml, e->mac, e->vlan);
230 /* Looks up MAC 'dst' for VLAN 'vlan' in 'ml' and returns the associated MAC
231 * learning entry, if any. If 'tag' is nonnull, then the tag that associates
232 * 'dst' and 'vlan' with its currently learned port will be OR'd into
235 mac_learning_lookup(const struct mac_learning *ml,
236 const uint8_t dst[ETH_ADDR_LEN], uint16_t vlan,
239 if (eth_addr_is_multicast(dst)) {
240 /* No tag because the treatment of multicast destinations never
243 } else if (!is_learning_vlan(ml, vlan)) {
244 /* We don't tag this property. The set of learning VLANs changes so
245 * rarely that we revalidate every flow when it changes. */
248 struct mac_entry *e = search_bucket(mac_table_bucket(ml, dst, vlan),
250 assert(e == NULL || e->tag != 0);
252 /* Tag either the learned port or the lack thereof. */
253 *tag |= e ? e->tag : make_unknown_mac_tag(ml, dst, vlan);
259 /* Expires 'e' from the 'ml' hash table. 'e' must not already be on the free
262 mac_learning_expire(struct mac_learning *ml, struct mac_entry *e)
264 list_remove(&e->hash_node);
265 list_remove(&e->lru_node);
266 list_push_front(&ml->free, &e->lru_node);
269 /* Expires all the mac-learning entries in 'ml'. The tags in 'ml' are
270 * discarded, so the client is responsible for revalidating any flows that
271 * depend on 'ml', if necessary. */
273 mac_learning_flush(struct mac_learning *ml)
276 while (get_lru(ml, &e)){
277 mac_learning_expire(ml, e);
282 mac_learning_run(struct mac_learning *ml, struct tag_set *set)
285 while (get_lru(ml, &e) && time_now() >= e->expires) {
286 COVERAGE_INC(mac_learning_expired);
288 tag_set_add(set, e->tag);
290 mac_learning_expire(ml, e);
295 mac_learning_wait(struct mac_learning *ml)
297 if (!list_is_empty(&ml->lrus)) {
298 struct mac_entry *e = mac_entry_from_lru_node(ml->lrus.next);
299 poll_timer_wait_until(e->expires * 1000LL);