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1da177e4 LT |
1 | /* |
2 | * Spanning tree protocol; generic parts | |
3 | * Linux ethernet bridge | |
4 | * | |
5 | * Authors: | |
6 | * Lennert Buytenhek <buytenh@gnu.org> | |
7 | * | |
8 | * $Id: br_stp.c,v 1.4 2000/06/19 10:13:35 davem Exp $ | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License | |
12 | * as published by the Free Software Foundation; either version | |
13 | * 2 of the License, or (at your option) any later version. | |
14 | */ | |
15 | #include <linux/kernel.h> | |
1da177e4 LT |
16 | |
17 | #include "br_private.h" | |
18 | #include "br_private_stp.h" | |
19 | ||
20 | /* since time values in bpdu are in jiffies and then scaled (1/256) | |
21 | * before sending, make sure that is at least one. | |
22 | */ | |
23 | #define MESSAGE_AGE_INCR ((HZ < 256) ? 1 : (HZ/256)) | |
24 | ||
25 | static const char *br_port_state_names[] = { | |
9d6f229f | 26 | [BR_STATE_DISABLED] = "disabled", |
1da177e4 | 27 | [BR_STATE_LISTENING] = "listening", |
9d6f229f YH |
28 | [BR_STATE_LEARNING] = "learning", |
29 | [BR_STATE_FORWARDING] = "forwarding", | |
1da177e4 LT |
30 | [BR_STATE_BLOCKING] = "blocking", |
31 | }; | |
32 | ||
33 | void br_log_state(const struct net_bridge_port *p) | |
34 | { | |
35 | pr_info("%s: port %d(%s) entering %s state\n", | |
9d6f229f | 36 | p->br->dev->name, p->port_no, p->dev->name, |
1da177e4 LT |
37 | br_port_state_names[p->state]); |
38 | ||
39 | } | |
40 | ||
41 | /* called under bridge lock */ | |
42 | struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no) | |
43 | { | |
44 | struct net_bridge_port *p; | |
45 | ||
46 | list_for_each_entry_rcu(p, &br->port_list, list) { | |
47 | if (p->port_no == port_no) | |
48 | return p; | |
49 | } | |
50 | ||
51 | return NULL; | |
52 | } | |
53 | ||
54 | /* called under bridge lock */ | |
9d6f229f | 55 | static int br_should_become_root_port(const struct net_bridge_port *p, |
1da177e4 LT |
56 | u16 root_port) |
57 | { | |
58 | struct net_bridge *br; | |
59 | struct net_bridge_port *rp; | |
60 | int t; | |
61 | ||
62 | br = p->br; | |
63 | if (p->state == BR_STATE_DISABLED || | |
64 | br_is_designated_port(p)) | |
65 | return 0; | |
66 | ||
67 | if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0) | |
68 | return 0; | |
69 | ||
70 | if (!root_port) | |
71 | return 1; | |
72 | ||
73 | rp = br_get_port(br, root_port); | |
74 | ||
75 | t = memcmp(&p->designated_root, &rp->designated_root, 8); | |
76 | if (t < 0) | |
77 | return 1; | |
78 | else if (t > 0) | |
79 | return 0; | |
80 | ||
81 | if (p->designated_cost + p->path_cost < | |
82 | rp->designated_cost + rp->path_cost) | |
83 | return 1; | |
84 | else if (p->designated_cost + p->path_cost > | |
85 | rp->designated_cost + rp->path_cost) | |
86 | return 0; | |
87 | ||
88 | t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8); | |
89 | if (t < 0) | |
90 | return 1; | |
91 | else if (t > 0) | |
92 | return 0; | |
93 | ||
94 | if (p->designated_port < rp->designated_port) | |
95 | return 1; | |
96 | else if (p->designated_port > rp->designated_port) | |
97 | return 0; | |
98 | ||
99 | if (p->port_id < rp->port_id) | |
100 | return 1; | |
101 | ||
102 | return 0; | |
103 | } | |
104 | ||
105 | /* called under bridge lock */ | |
106 | static void br_root_selection(struct net_bridge *br) | |
107 | { | |
108 | struct net_bridge_port *p; | |
109 | u16 root_port = 0; | |
110 | ||
111 | list_for_each_entry(p, &br->port_list, list) { | |
112 | if (br_should_become_root_port(p, root_port)) | |
113 | root_port = p->port_no; | |
114 | ||
115 | } | |
116 | ||
117 | br->root_port = root_port; | |
118 | ||
119 | if (!root_port) { | |
120 | br->designated_root = br->bridge_id; | |
121 | br->root_path_cost = 0; | |
122 | } else { | |
123 | p = br_get_port(br, root_port); | |
124 | br->designated_root = p->designated_root; | |
125 | br->root_path_cost = p->designated_cost + p->path_cost; | |
126 | } | |
127 | } | |
128 | ||
129 | /* called under bridge lock */ | |
130 | void br_become_root_bridge(struct net_bridge *br) | |
131 | { | |
132 | br->max_age = br->bridge_max_age; | |
133 | br->hello_time = br->bridge_hello_time; | |
134 | br->forward_delay = br->bridge_forward_delay; | |
135 | br_topology_change_detection(br); | |
136 | del_timer(&br->tcn_timer); | |
137 | ||
138 | if (br->dev->flags & IFF_UP) { | |
139 | br_config_bpdu_generation(br); | |
140 | mod_timer(&br->hello_timer, jiffies + br->hello_time); | |
141 | } | |
142 | } | |
143 | ||
144 | /* called under bridge lock */ | |
145 | void br_transmit_config(struct net_bridge_port *p) | |
146 | { | |
147 | struct br_config_bpdu bpdu; | |
148 | struct net_bridge *br; | |
149 | ||
150 | ||
151 | if (timer_pending(&p->hold_timer)) { | |
152 | p->config_pending = 1; | |
153 | return; | |
154 | } | |
155 | ||
156 | br = p->br; | |
157 | ||
158 | bpdu.topology_change = br->topology_change; | |
159 | bpdu.topology_change_ack = p->topology_change_ack; | |
160 | bpdu.root = br->designated_root; | |
161 | bpdu.root_path_cost = br->root_path_cost; | |
162 | bpdu.bridge_id = br->bridge_id; | |
163 | bpdu.port_id = p->port_id; | |
164 | if (br_is_root_bridge(br)) | |
165 | bpdu.message_age = 0; | |
166 | else { | |
167 | struct net_bridge_port *root | |
168 | = br_get_port(br, br->root_port); | |
169 | bpdu.message_age = br->max_age | |
170 | - (root->message_age_timer.expires - jiffies) | |
171 | + MESSAGE_AGE_INCR; | |
172 | } | |
173 | bpdu.max_age = br->max_age; | |
174 | bpdu.hello_time = br->hello_time; | |
175 | bpdu.forward_delay = br->forward_delay; | |
176 | ||
177 | if (bpdu.message_age < br->max_age) { | |
178 | br_send_config_bpdu(p, &bpdu); | |
179 | p->topology_change_ack = 0; | |
180 | p->config_pending = 0; | |
181 | mod_timer(&p->hold_timer, jiffies + BR_HOLD_TIME); | |
182 | } | |
183 | } | |
184 | ||
185 | /* called under bridge lock */ | |
9d6f229f | 186 | static inline void br_record_config_information(struct net_bridge_port *p, |
1da177e4 LT |
187 | const struct br_config_bpdu *bpdu) |
188 | { | |
189 | p->designated_root = bpdu->root; | |
190 | p->designated_cost = bpdu->root_path_cost; | |
191 | p->designated_bridge = bpdu->bridge_id; | |
192 | p->designated_port = bpdu->port_id; | |
193 | ||
9d6f229f | 194 | mod_timer(&p->message_age_timer, jiffies |
1da177e4 LT |
195 | + (p->br->max_age - bpdu->message_age)); |
196 | } | |
197 | ||
198 | /* called under bridge lock */ | |
9d6f229f | 199 | static inline void br_record_config_timeout_values(struct net_bridge *br, |
1da177e4 LT |
200 | const struct br_config_bpdu *bpdu) |
201 | { | |
202 | br->max_age = bpdu->max_age; | |
203 | br->hello_time = bpdu->hello_time; | |
204 | br->forward_delay = bpdu->forward_delay; | |
205 | br->topology_change = bpdu->topology_change; | |
206 | } | |
207 | ||
208 | /* called under bridge lock */ | |
209 | void br_transmit_tcn(struct net_bridge *br) | |
210 | { | |
211 | br_send_tcn_bpdu(br_get_port(br, br->root_port)); | |
212 | } | |
213 | ||
214 | /* called under bridge lock */ | |
215 | static int br_should_become_designated_port(const struct net_bridge_port *p) | |
216 | { | |
217 | struct net_bridge *br; | |
218 | int t; | |
219 | ||
220 | br = p->br; | |
221 | if (br_is_designated_port(p)) | |
222 | return 1; | |
223 | ||
224 | if (memcmp(&p->designated_root, &br->designated_root, 8)) | |
225 | return 1; | |
226 | ||
227 | if (br->root_path_cost < p->designated_cost) | |
228 | return 1; | |
229 | else if (br->root_path_cost > p->designated_cost) | |
230 | return 0; | |
231 | ||
232 | t = memcmp(&br->bridge_id, &p->designated_bridge, 8); | |
233 | if (t < 0) | |
234 | return 1; | |
235 | else if (t > 0) | |
236 | return 0; | |
237 | ||
238 | if (p->port_id < p->designated_port) | |
239 | return 1; | |
240 | ||
241 | return 0; | |
242 | } | |
243 | ||
244 | /* called under bridge lock */ | |
245 | static void br_designated_port_selection(struct net_bridge *br) | |
246 | { | |
247 | struct net_bridge_port *p; | |
248 | ||
249 | list_for_each_entry(p, &br->port_list, list) { | |
250 | if (p->state != BR_STATE_DISABLED && | |
251 | br_should_become_designated_port(p)) | |
252 | br_become_designated_port(p); | |
253 | ||
254 | } | |
255 | } | |
256 | ||
257 | /* called under bridge lock */ | |
258 | static int br_supersedes_port_info(struct net_bridge_port *p, struct br_config_bpdu *bpdu) | |
259 | { | |
260 | int t; | |
261 | ||
262 | t = memcmp(&bpdu->root, &p->designated_root, 8); | |
263 | if (t < 0) | |
264 | return 1; | |
265 | else if (t > 0) | |
266 | return 0; | |
267 | ||
268 | if (bpdu->root_path_cost < p->designated_cost) | |
269 | return 1; | |
270 | else if (bpdu->root_path_cost > p->designated_cost) | |
271 | return 0; | |
272 | ||
273 | t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8); | |
274 | if (t < 0) | |
275 | return 1; | |
276 | else if (t > 0) | |
277 | return 0; | |
278 | ||
279 | if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8)) | |
280 | return 1; | |
281 | ||
282 | if (bpdu->port_id <= p->designated_port) | |
283 | return 1; | |
284 | ||
285 | return 0; | |
286 | } | |
287 | ||
288 | /* called under bridge lock */ | |
289 | static inline void br_topology_change_acknowledged(struct net_bridge *br) | |
290 | { | |
291 | br->topology_change_detected = 0; | |
292 | del_timer(&br->tcn_timer); | |
293 | } | |
294 | ||
295 | /* called under bridge lock */ | |
296 | void br_topology_change_detection(struct net_bridge *br) | |
297 | { | |
298 | int isroot = br_is_root_bridge(br); | |
299 | ||
300 | pr_info("%s: topology change detected, %s\n", br->dev->name, | |
301 | isroot ? "propagating" : "sending tcn bpdu"); | |
302 | ||
303 | if (isroot) { | |
304 | br->topology_change = 1; | |
305 | mod_timer(&br->topology_change_timer, jiffies | |
306 | + br->bridge_forward_delay + br->bridge_max_age); | |
307 | } else if (!br->topology_change_detected) { | |
308 | br_transmit_tcn(br); | |
309 | mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time); | |
310 | } | |
311 | ||
312 | br->topology_change_detected = 1; | |
313 | } | |
314 | ||
315 | /* called under bridge lock */ | |
316 | void br_config_bpdu_generation(struct net_bridge *br) | |
317 | { | |
318 | struct net_bridge_port *p; | |
319 | ||
320 | list_for_each_entry(p, &br->port_list, list) { | |
321 | if (p->state != BR_STATE_DISABLED && | |
322 | br_is_designated_port(p)) | |
323 | br_transmit_config(p); | |
324 | } | |
325 | } | |
326 | ||
327 | /* called under bridge lock */ | |
328 | static inline void br_reply(struct net_bridge_port *p) | |
329 | { | |
330 | br_transmit_config(p); | |
331 | } | |
332 | ||
333 | /* called under bridge lock */ | |
334 | void br_configuration_update(struct net_bridge *br) | |
335 | { | |
336 | br_root_selection(br); | |
337 | br_designated_port_selection(br); | |
338 | } | |
339 | ||
340 | /* called under bridge lock */ | |
341 | void br_become_designated_port(struct net_bridge_port *p) | |
342 | { | |
343 | struct net_bridge *br; | |
344 | ||
345 | br = p->br; | |
346 | p->designated_root = br->designated_root; | |
347 | p->designated_cost = br->root_path_cost; | |
348 | p->designated_bridge = br->bridge_id; | |
349 | p->designated_port = p->port_id; | |
350 | } | |
351 | ||
352 | ||
353 | /* called under bridge lock */ | |
354 | static void br_make_blocking(struct net_bridge_port *p) | |
355 | { | |
356 | if (p->state != BR_STATE_DISABLED && | |
357 | p->state != BR_STATE_BLOCKING) { | |
358 | if (p->state == BR_STATE_FORWARDING || | |
359 | p->state == BR_STATE_LEARNING) | |
360 | br_topology_change_detection(p->br); | |
361 | ||
362 | p->state = BR_STATE_BLOCKING; | |
363 | br_log_state(p); | |
364 | del_timer(&p->forward_delay_timer); | |
365 | } | |
366 | } | |
367 | ||
368 | /* called under bridge lock */ | |
369 | static void br_make_forwarding(struct net_bridge_port *p) | |
370 | { | |
371 | if (p->state == BR_STATE_BLOCKING) { | |
9cde0708 | 372 | if (p->br->stp_enabled == BR_KERNEL_STP) |
1da177e4 | 373 | p->state = BR_STATE_LISTENING; |
9cde0708 | 374 | else |
1da177e4 | 375 | p->state = BR_STATE_LEARNING; |
9cde0708 | 376 | |
1da177e4 LT |
377 | br_log_state(p); |
378 | mod_timer(&p->forward_delay_timer, jiffies + p->br->forward_delay); } | |
379 | } | |
380 | ||
381 | /* called under bridge lock */ | |
382 | void br_port_state_selection(struct net_bridge *br) | |
383 | { | |
384 | struct net_bridge_port *p; | |
385 | ||
9cde0708 SH |
386 | /* Don't change port states if userspace is handling STP */ |
387 | if (br->stp_enabled == BR_USER_STP) | |
388 | return; | |
389 | ||
1da177e4 LT |
390 | list_for_each_entry(p, &br->port_list, list) { |
391 | if (p->state != BR_STATE_DISABLED) { | |
392 | if (p->port_no == br->root_port) { | |
393 | p->config_pending = 0; | |
394 | p->topology_change_ack = 0; | |
395 | br_make_forwarding(p); | |
396 | } else if (br_is_designated_port(p)) { | |
397 | del_timer(&p->message_age_timer); | |
398 | br_make_forwarding(p); | |
399 | } else { | |
400 | p->config_pending = 0; | |
401 | p->topology_change_ack = 0; | |
402 | br_make_blocking(p); | |
403 | } | |
404 | } | |
405 | ||
406 | } | |
407 | } | |
408 | ||
409 | /* called under bridge lock */ | |
410 | static inline void br_topology_change_acknowledge(struct net_bridge_port *p) | |
411 | { | |
412 | p->topology_change_ack = 1; | |
413 | br_transmit_config(p); | |
414 | } | |
415 | ||
416 | /* called under bridge lock */ | |
417 | void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu) | |
418 | { | |
419 | struct net_bridge *br; | |
420 | int was_root; | |
9d6f229f | 421 | |
1da177e4 LT |
422 | br = p->br; |
423 | was_root = br_is_root_bridge(br); | |
424 | ||
425 | if (br_supersedes_port_info(p, bpdu)) { | |
426 | br_record_config_information(p, bpdu); | |
427 | br_configuration_update(br); | |
428 | br_port_state_selection(br); | |
429 | ||
430 | if (!br_is_root_bridge(br) && was_root) { | |
431 | del_timer(&br->hello_timer); | |
432 | if (br->topology_change_detected) { | |
433 | del_timer(&br->topology_change_timer); | |
434 | br_transmit_tcn(br); | |
435 | ||
9d6f229f | 436 | mod_timer(&br->tcn_timer, |
1da177e4 LT |
437 | jiffies + br->bridge_hello_time); |
438 | } | |
439 | } | |
440 | ||
441 | if (p->port_no == br->root_port) { | |
442 | br_record_config_timeout_values(br, bpdu); | |
443 | br_config_bpdu_generation(br); | |
444 | if (bpdu->topology_change_ack) | |
445 | br_topology_change_acknowledged(br); | |
446 | } | |
9d6f229f YH |
447 | } else if (br_is_designated_port(p)) { |
448 | br_reply(p); | |
1da177e4 LT |
449 | } |
450 | } | |
451 | ||
452 | /* called under bridge lock */ | |
453 | void br_received_tcn_bpdu(struct net_bridge_port *p) | |
454 | { | |
455 | if (br_is_designated_port(p)) { | |
456 | pr_info("%s: received tcn bpdu on port %i(%s)\n", | |
457 | p->br->dev->name, p->port_no, p->dev->name); | |
458 | ||
459 | br_topology_change_detection(p->br); | |
460 | br_topology_change_acknowledge(p); | |
461 | } | |
462 | } |