2 * Copyright (c) 2008, 2009, 2010, 2011, 2012 Nicira, Inc.
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"
31 #include "unaligned.h"
33 #include "vlan-bitmap.h"
36 VLOG_DEFINE_THIS_MODULE(mac_learning);
38 COVERAGE_DEFINE(mac_learning_learned);
39 COVERAGE_DEFINE(mac_learning_expired);
41 /* Returns the number of seconds since 'e' (within 'ml') was last learned. */
43 mac_entry_age(const struct mac_learning *ml, const struct mac_entry *e)
45 time_t remaining = e->expires - time_now();
46 return ml->idle_time - remaining;
50 mac_table_hash(const struct mac_learning *ml, const uint8_t mac[ETH_ADDR_LEN],
53 unsigned int mac1 = get_unaligned_u32((uint32_t *) mac);
54 unsigned int mac2 = get_unaligned_u16((uint16_t *) (mac + 4));
55 return hash_3words(mac1, mac2 | (vlan << 16), ml->secret);
58 static struct mac_entry *
59 mac_entry_from_lru_node(struct list *list)
61 return CONTAINER_OF(list, struct mac_entry, lru_node);
64 /* Returns a tag that represents that 'mac' is on an unknown port in 'vlan'.
65 * (When we learn where 'mac' is in 'vlan', this allows flows that were
66 * flooded to be revalidated.) */
68 make_unknown_mac_tag(const struct mac_learning *ml,
69 const uint8_t mac[ETH_ADDR_LEN], uint16_t vlan)
71 return tag_create_deterministic(mac_table_hash(ml, mac, vlan));
74 static struct mac_entry *
75 mac_entry_lookup(const struct mac_learning *ml,
76 const uint8_t mac[ETH_ADDR_LEN], uint16_t vlan)
80 HMAP_FOR_EACH_WITH_HASH (e, hmap_node, mac_table_hash(ml, mac, vlan),
82 if (e->vlan == vlan && eth_addr_equals(e->mac, mac)) {
89 /* If the LRU list is not empty, stores the least-recently-used entry in '*e'
90 * and returns true. Otherwise, if the LRU list is empty, stores NULL in '*e'
91 * and return false. */
93 get_lru(struct mac_learning *ml, struct mac_entry **e)
95 if (!list_is_empty(&ml->lrus)) {
96 *e = mac_entry_from_lru_node(ml->lrus.next);
105 normalize_idle_time(unsigned int idle_time)
107 return (idle_time < 15 ? 15
108 : idle_time > 3600 ? 3600
112 /* Creates and returns a new MAC learning table with an initial MAC aging
113 * timeout of 'idle_time' seconds. */
114 struct mac_learning *
115 mac_learning_create(unsigned int idle_time)
117 struct mac_learning *ml;
119 ml = xmalloc(sizeof *ml);
120 list_init(&ml->lrus);
121 hmap_init(&ml->table);
122 ml->secret = random_uint32();
123 ml->flood_vlans = NULL;
124 ml->idle_time = normalize_idle_time(idle_time);
128 /* Destroys MAC learning table 'ml'. */
130 mac_learning_destroy(struct mac_learning *ml)
133 struct mac_entry *e, *next;
135 HMAP_FOR_EACH_SAFE (e, next, hmap_node, &ml->table) {
136 hmap_remove(&ml->table, &e->hmap_node);
139 hmap_destroy(&ml->table);
141 bitmap_free(ml->flood_vlans);
146 /* Provides a bitmap of VLANs which have learning disabled, that is, VLANs on
147 * which all packets are flooded. Returns true if the set has changed from the
150 mac_learning_set_flood_vlans(struct mac_learning *ml,
151 const unsigned long *bitmap)
153 if (vlan_bitmap_equal(ml->flood_vlans, bitmap)) {
156 bitmap_free(ml->flood_vlans);
157 ml->flood_vlans = vlan_bitmap_clone(bitmap);
162 /* Changes the MAC aging timeout of 'ml' to 'idle_time' seconds. */
164 mac_learning_set_idle_time(struct mac_learning *ml, unsigned int idle_time)
166 idle_time = normalize_idle_time(idle_time);
167 if (idle_time != ml->idle_time) {
171 delta = (int) idle_time - (int) ml->idle_time;
172 LIST_FOR_EACH (e, lru_node, &ml->lrus) {
175 ml->idle_time = idle_time;
180 is_learning_vlan(const struct mac_learning *ml, uint16_t vlan)
182 return !ml->flood_vlans || !bitmap_is_set(ml->flood_vlans, vlan);
185 /* Returns true if 'src_mac' may be learned on 'vlan' for 'ml'.
186 * Returns false if 'ml' is NULL, if src_mac is not valid for learning, or if
187 * 'vlan' is configured on 'ml' to flood all packets. */
189 mac_learning_may_learn(const struct mac_learning *ml,
190 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan)
192 return ml && is_learning_vlan(ml, vlan) && !eth_addr_is_multicast(src_mac);
195 /* Searches 'ml' for and returns a MAC learning entry for 'src_mac' in 'vlan',
196 * inserting a new entry if necessary. The caller must have already verified,
197 * by calling mac_learning_may_learn(), that 'src_mac' and 'vlan' are
200 * If the returned MAC entry is new (as may be determined by calling
201 * mac_entry_is_new()), then the caller must pass the new entry to
202 * mac_learning_changed(). The caller must also initialize the new entry's
203 * 'port' member. Otherwise calling those functions is at the caller's
206 mac_learning_insert(struct mac_learning *ml,
207 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan)
211 e = mac_entry_lookup(ml, src_mac, vlan);
213 uint32_t hash = mac_table_hash(ml, src_mac, vlan);
215 if (hmap_count(&ml->table) >= MAC_MAX) {
217 mac_learning_expire(ml, e);
220 e = xmalloc(sizeof *e);
221 hmap_insert(&ml->table, &e->hmap_node, hash);
222 memcpy(e->mac, src_mac, ETH_ADDR_LEN);
225 e->grat_arp_lock = TIME_MIN;
227 list_remove(&e->lru_node);
230 /* Mark 'e' as recently used. */
231 list_push_back(&ml->lrus, &e->lru_node);
232 e->expires = time_now() + ml->idle_time;
237 /* Changes 'e''s tag to a new, randomly selected one, and returns the tag that
238 * would have been previously used for this entry's MAC and VLAN (either before
239 * 'e' was inserted, if it is new, or otherwise before its port was updated.)
241 * The client should call this function after obtaining a MAC learning entry
242 * from mac_learning_insert(), if the entry is either new or if its learned
243 * port has changed. */
245 mac_learning_changed(struct mac_learning *ml, struct mac_entry *e)
247 tag_type old_tag = e->tag;
249 COVERAGE_INC(mac_learning_learned);
251 e->tag = tag_create_random();
252 return old_tag ? old_tag : make_unknown_mac_tag(ml, e->mac, e->vlan);
255 /* Looks up MAC 'dst' for VLAN 'vlan' in 'ml' and returns the associated MAC
256 * learning entry, if any. If 'tag' is nonnull, then the tag that associates
257 * 'dst' and 'vlan' with its currently learned port will be OR'd into
260 mac_learning_lookup(const struct mac_learning *ml,
261 const uint8_t dst[ETH_ADDR_LEN], uint16_t vlan,
264 if (eth_addr_is_multicast(dst)) {
265 /* No tag because the treatment of multicast destinations never
268 } else if (!is_learning_vlan(ml, vlan)) {
269 /* We don't tag this property. The set of learning VLANs changes so
270 * rarely that we revalidate every flow when it changes. */
273 struct mac_entry *e = mac_entry_lookup(ml, dst, vlan);
275 assert(e == NULL || e->tag != 0);
277 /* Tag either the learned port or the lack thereof. */
278 *tag |= e ? e->tag : make_unknown_mac_tag(ml, dst, vlan);
284 /* Expires 'e' from the 'ml' hash table. */
286 mac_learning_expire(struct mac_learning *ml, struct mac_entry *e)
288 hmap_remove(&ml->table, &e->hmap_node);
289 list_remove(&e->lru_node);
293 /* Expires all the mac-learning entries in 'ml'. If not NULL, the tags in 'ml'
294 * are added to 'tags'. Otherwise the tags in 'ml' are discarded. The client
295 * is responsible for revalidating any flows that depend on 'ml', if
298 mac_learning_flush(struct mac_learning *ml, struct tag_set *tags)
301 while (get_lru(ml, &e)){
303 tag_set_add(tags, e->tag);
305 mac_learning_expire(ml, e);
307 hmap_shrink(&ml->table);
311 mac_learning_run(struct mac_learning *ml, struct tag_set *set)
314 while (get_lru(ml, &e) && time_now() >= e->expires) {
315 COVERAGE_INC(mac_learning_expired);
317 tag_set_add(set, e->tag);
319 mac_learning_expire(ml, e);
324 mac_learning_wait(struct mac_learning *ml)
326 if (!list_is_empty(&ml->lrus)) {
327 struct mac_entry *e = mac_entry_from_lru_node(ml->lrus.next);
328 poll_timer_wait_until(e->expires * 1000LL);