2 * Copyright (c) 2008, 2009, 2010, 2012 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"
34 VLOG_DEFINE_THIS_MODULE(mac_learning);
36 COVERAGE_DEFINE(mac_learning_learned);
37 COVERAGE_DEFINE(mac_learning_expired);
39 /* Returns the number of seconds since 'e' (within 'ml') was last learned. */
41 mac_entry_age(const struct mac_learning *ml, const struct mac_entry *e)
43 time_t remaining = e->expires - time_now();
44 return ml->idle_time - remaining;
48 mac_table_hash(const uint8_t mac[ETH_ADDR_LEN], uint16_t vlan)
50 return hash_bytes(mac, ETH_ADDR_LEN, vlan);
53 static struct mac_entry *
54 mac_entry_from_lru_node(struct list *list)
56 return CONTAINER_OF(list, struct mac_entry, lru_node);
59 /* Returns a tag that represents that 'mac' is on an unknown port in 'vlan'.
60 * (When we learn where 'mac' is in 'vlan', this allows flows that were
61 * flooded to be revalidated.) */
63 make_unknown_mac_tag(const struct mac_learning *ml,
64 const uint8_t mac[ETH_ADDR_LEN], uint16_t vlan)
66 uint32_t h = hash_int(ml->secret, mac_table_hash(mac, vlan));
67 return tag_create_deterministic(h);
71 mac_table_bucket(const struct mac_learning *ml,
72 const uint8_t mac[ETH_ADDR_LEN],
75 uint32_t hash = mac_table_hash(mac, vlan);
76 const struct list *list = &ml->table[hash & MAC_HASH_MASK];
77 return (struct list *) list;
80 static struct mac_entry *
81 search_bucket(struct list *bucket, const uint8_t mac[ETH_ADDR_LEN],
85 LIST_FOR_EACH (e, hash_node, bucket) {
86 if (eth_addr_equals(e->mac, mac) && e->vlan == vlan) {
93 /* If the LRU list is not empty, stores the least-recently-used entry in '*e'
94 * and returns true. Otherwise, if the LRU list is empty, stores NULL in '*e'
95 * and return false. */
97 get_lru(struct mac_learning *ml, struct mac_entry **e)
99 if (!list_is_empty(&ml->lrus)) {
100 *e = mac_entry_from_lru_node(ml->lrus.next);
108 /* Removes 'e' from the 'ml' hash table. 'e' must not already be on the free
111 free_mac_entry(struct mac_learning *ml, struct mac_entry *e)
113 list_remove(&e->hash_node);
114 list_remove(&e->lru_node);
115 list_push_front(&ml->free, &e->lru_node);
119 normalize_idle_time(unsigned int idle_time)
121 return (idle_time < 15 ? 15
122 : idle_time > 3600 ? 3600
126 /* Creates and returns a new MAC learning table with an initial MAC aging
127 * timeout of 'idle_time' seconds. */
128 struct mac_learning *
129 mac_learning_create(unsigned int idle_time)
131 struct mac_learning *ml;
134 ml = xmalloc(sizeof *ml);
135 list_init(&ml->lrus);
136 list_init(&ml->free);
137 for (i = 0; i < MAC_HASH_SIZE; i++) {
138 list_init(&ml->table[i]);
140 for (i = 0; i < MAC_MAX; i++) {
141 struct mac_entry *s = &ml->entries[i];
142 list_push_front(&ml->free, &s->lru_node);
144 ml->secret = random_uint32();
145 ml->flood_vlans = NULL;
146 ml->idle_time = normalize_idle_time(idle_time);
150 /* Destroys MAC learning table 'ml'. */
152 mac_learning_destroy(struct mac_learning *ml)
155 bitmap_free(ml->flood_vlans);
160 /* Provides a bitmap of VLANs which have learning disabled, that is, VLANs on
161 * which all packets are flooded. It takes ownership of the bitmap. Returns
162 * true if the set has changed from the previous value. */
164 mac_learning_set_flood_vlans(struct mac_learning *ml, unsigned long *bitmap)
166 bool ret = (bitmap == NULL
167 ? ml->flood_vlans != NULL
168 : (ml->flood_vlans == NULL
169 || !bitmap_equal(bitmap, ml->flood_vlans, 4096)));
171 bitmap_free(ml->flood_vlans);
172 ml->flood_vlans = bitmap;
177 /* Changes the MAC aging timeout of 'ml' to 'idle_time' seconds. */
179 mac_learning_set_idle_time(struct mac_learning *ml, unsigned int idle_time)
181 idle_time = normalize_idle_time(idle_time);
182 if (idle_time != ml->idle_time) {
186 delta = (int) idle_time - (int) ml->idle_time;
187 LIST_FOR_EACH (e, lru_node, &ml->lrus) {
190 ml->idle_time = idle_time;
195 is_learning_vlan(const struct mac_learning *ml, uint16_t vlan)
197 return !(ml->flood_vlans && bitmap_is_set(ml->flood_vlans, vlan));
200 /* Attempts to make 'ml' learn from the fact that a frame from 'src_mac' was
201 * just observed arriving from 'src_port' on the given 'vlan'.
203 * Returns nonzero if we actually learned something from this, zero if it just
204 * confirms what we already knew. The nonzero return value is the tag of flows
205 * that now need revalidation.
207 * The 'vlan' parameter is used to maintain separate per-VLAN learning tables.
208 * Specify 0 if this behavior is undesirable.
210 * 'lock_type' specifies whether the entry should be locked or existing locks
213 mac_learning_learn(struct mac_learning *ml,
214 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan,
215 uint16_t src_port, enum grat_arp_lock_type lock_type)
220 if (!is_learning_vlan(ml, vlan)) {
224 if (eth_addr_is_multicast(src_mac)) {
225 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(30, 30);
226 VLOG_DBG_RL(&rl, "multicast packet source "ETH_ADDR_FMT,
227 ETH_ADDR_ARGS(src_mac));
231 bucket = mac_table_bucket(ml, src_mac, vlan);
232 e = search_bucket(bucket, src_mac, vlan);
234 if (!list_is_empty(&ml->free)) {
235 e = mac_entry_from_lru_node(ml->free.next);
237 e = mac_entry_from_lru_node(ml->lrus.next);
238 list_remove(&e->hash_node);
240 memcpy(e->mac, src_mac, ETH_ADDR_LEN);
241 list_push_front(bucket, &e->hash_node);
244 e->tag = make_unknown_mac_tag(ml, src_mac, vlan);
245 e->grat_arp_lock = TIME_MIN;
248 if (lock_type != GRAT_ARP_LOCK_CHECK || time_now() >= e->grat_arp_lock) {
249 /* Make the entry most-recently-used. */
250 list_remove(&e->lru_node);
251 list_push_back(&ml->lrus, &e->lru_node);
252 e->expires = time_now() + ml->idle_time;
253 if (lock_type == GRAT_ARP_LOCK_SET) {
254 e->grat_arp_lock = time_now() + MAC_GRAT_ARP_LOCK_TIME;
257 /* Did we learn something? */
258 if (e->port != src_port) {
259 tag_type old_tag = e->tag;
261 e->tag = tag_create_random();
262 COVERAGE_INC(mac_learning_learned);
270 /* Looks up MAC 'dst' for VLAN 'vlan' in 'ml'. Returns the port on which a
271 * frame destined for 'dst' should be sent, -1 if unknown. 'is_grat_arp_locked'
272 * is an optional parameter that returns whether the entry is currently
275 mac_learning_lookup(const struct mac_learning *ml,
276 const uint8_t dst[ETH_ADDR_LEN], uint16_t vlan,
277 bool *is_grat_arp_locked)
280 return mac_learning_lookup_tag(ml, dst, vlan, &tag, is_grat_arp_locked);
283 /* Looks up MAC 'dst' for VLAN 'vlan' in 'ml'. Returns the port on which a
284 * frame destined for 'dst' should be sent, -1 if unknown.
286 * Adds to '*tag' (which the caller must have initialized) the tag that should
287 * be attached to any flow created based on the return value, if any, to allow
288 * those flows to be revalidated when the MAC learning entry changes.
290 * 'is_grat_arp_locked' is an optional parameter that returns whether the entry
291 * is currently locked.*/
293 mac_learning_lookup_tag(const struct mac_learning *ml,
294 const uint8_t dst[ETH_ADDR_LEN], uint16_t vlan,
295 tag_type *tag, bool *is_grat_arp_locked)
297 if (eth_addr_is_multicast(dst) || !is_learning_vlan(ml, vlan)) {
300 struct mac_entry *e = search_bucket(mac_table_bucket(ml, dst, vlan),
305 if (is_grat_arp_locked) {
306 *is_grat_arp_locked = time_now() < e->grat_arp_lock;
311 *tag |= make_unknown_mac_tag(ml, dst, vlan);
317 /* Expires all the mac-learning entries in 'ml'. The tags in 'ml' are
318 * discarded, so the client is responsible for revalidating any flows that
319 * depend on 'ml', if necessary. */
321 mac_learning_flush(struct mac_learning *ml)
324 while (get_lru(ml, &e)){
325 free_mac_entry(ml, e);
330 mac_learning_run(struct mac_learning *ml, struct tag_set *set)
333 while (get_lru(ml, &e) && time_now() >= e->expires) {
334 COVERAGE_INC(mac_learning_expired);
336 tag_set_add(set, e->tag);
338 free_mac_entry(ml, e);
343 mac_learning_wait(struct mac_learning *ml)
345 if (!list_is_empty(&ml->lrus)) {
346 struct mac_entry *e = mac_entry_from_lru_node(ml->lrus.next);
347 poll_timer_wait_until(e->expires * 1000LL);