1 /*-
2 * Copyright (c) 2007-2008 Sam Leffler, Errno Consulting
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #include <sys/cdefs.h>
27 #ifdef __FreeBSD__
28 __FBSDID("$FreeBSD$");
29 #endif
30
31 /*
32 * IEEE 802.11 DFS/Radar support.
33 */
34 #include "opt_inet.h"
35 #include "opt_wlan.h"
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/mbuf.h>
40 #include <sys/malloc.h>
41 #include <sys/kernel.h>
42
43 #include <sys/socket.h>
44 #include <sys/sockio.h>
45 #include <sys/endian.h>
46 #include <sys/errno.h>
47 #include <sys/proc.h>
48 #include <sys/sysctl.h>
49
50 #include <net/if.h>
51 #include <net/if_var.h>
52 #include <net/if_media.h>
53 #include <net/ethernet.h>
54
55 #include <net80211/ieee80211_var.h>
56
57 static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
58
59 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
60 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
61 &ieee80211_nol_timeout, 0, "NOL timeout (secs)");
62 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
63
64 static int ieee80211_cac_timeout = 60; /* 60 seconds */
65 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
66 &ieee80211_cac_timeout, 0, "CAC timeout (secs)");
67 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
68
69 /*
70 DFS* In order to facilitate debugging, a couple of operating
71 * modes aside from the default are needed.
72 *
73 * 0 - default CAC/NOL behaviour - ie, start CAC, place
74 * channel on NOL list.
75 * 1 - send CAC, but don't change channel or add the channel
76 * to the NOL list.
77 * 2 - just match on radar, don't send CAC or place channel in
78 * the NOL list.
79 */
80 static int ieee80211_dfs_debug = DFS_DBG_NONE;
81
82 /*
83 * This option must not be included in the default kernel
84 * as it allows users to plainly disable CAC/NOL handling.
85 */
86 #ifdef IEEE80211_DFS_DEBUG
87 SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW,
88 &ieee80211_dfs_debug, 0, "DFS debug behaviour");
89 #endif
90
91 static int
null_set_quiet(struct ieee80211_node * ni,u_int8_t * quiet_elm)92 null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm)
93 {
94 return ENOSYS;
95 }
96
97 void
ieee80211_dfs_attach(struct ieee80211com * ic)98 ieee80211_dfs_attach(struct ieee80211com *ic)
99 {
100 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
101
102 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0);
103 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0);
104
105 ic->ic_set_quiet = null_set_quiet;
106 }
107
108 void
ieee80211_dfs_detach(struct ieee80211com * ic)109 ieee80211_dfs_detach(struct ieee80211com *ic)
110 {
111 /* NB: we assume no locking is needed */
112 ieee80211_dfs_reset(ic);
113 }
114
115 void
ieee80211_dfs_reset(struct ieee80211com * ic)116 ieee80211_dfs_reset(struct ieee80211com *ic)
117 {
118 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
119 int i;
120
121 /* NB: we assume no locking is needed */
122 /* NB: cac_timer should be cleared by the state machine */
123 callout_drain(&dfs->nol_timer);
124 for (i = 0; i < ic->ic_nchans; i++)
125 ic->ic_channels[i].ic_state = 0;
126 dfs->lastchan = NULL;
127 }
128
129 static void
cac_timeout(void * arg)130 cac_timeout(void *arg)
131 {
132 struct ieee80211vap *vap = arg;
133 struct ieee80211com *ic = vap->iv_ic;
134 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
135 int i;
136
137 IEEE80211_LOCK_ASSERT(ic);
138
139 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
140 return;
141 /*
142 * When radar is detected during a CAC we are woken
143 * up prematurely to switch to a new channel.
144 * Check the channel to decide how to act.
145 */
146 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
147 ieee80211_notify_cac(ic, ic->ic_curchan,
148 IEEE80211_NOTIFY_CAC_RADAR);
149
150 if_printf(vap->iv_ifp,
151 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
152 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
153
154 /* XXX clobbers any existing desired channel */
155 /* NB: dfs->newchan may be NULL, that's ok */
156 vap->iv_des_chan = dfs->newchan;
157 ieee80211_new_state_locked(vap, IEEE80211_S_SCAN, 0);
158 } else {
159 if_printf(vap->iv_ifp,
160 "CAC timer on channel %u (%u MHz) expired; "
161 "no radar detected\n",
162 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
163 /*
164 * Mark all channels with the current frequency
165 * as having completed CAC; this keeps us from
166 * doing it again until we change channels.
167 */
168 for (i = 0; i < ic->ic_nchans; i++) {
169 struct ieee80211_channel *c = &ic->ic_channels[i];
170 if (c->ic_freq == ic->ic_curchan->ic_freq)
171 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
172 }
173 ieee80211_notify_cac(ic, ic->ic_curchan,
174 IEEE80211_NOTIFY_CAC_EXPIRE);
175 ieee80211_cac_completeswitch(vap);
176 }
177 }
178
179 /*
180 * Initiate the CAC timer. The driver is responsible
181 * for setting up the hardware to scan for radar on the
182 * channnel, we just handle timing things out.
183 */
184 void
ieee80211_dfs_cac_start(struct ieee80211vap * vap)185 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
186 {
187 struct ieee80211com *ic = vap->iv_ic;
188 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
189
190 IEEE80211_LOCK_ASSERT(ic);
191
192 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
193 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
194 ticks_to_secs(CAC_TIMEOUT),
195 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
196 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
197 }
198
199 /*
200 * Clear the CAC timer.
201 */
202 void
ieee80211_dfs_cac_stop(struct ieee80211vap * vap)203 ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
204 {
205 struct ieee80211com *ic = vap->iv_ic;
206 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
207
208 IEEE80211_LOCK_ASSERT(ic);
209
210 /* NB: racey but not important */
211 if (callout_pending(&dfs->cac_timer)) {
212 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
213 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
214 ieee80211_notify_cac(ic, ic->ic_curchan,
215 IEEE80211_NOTIFY_CAC_STOP);
216 }
217 callout_stop(&dfs->cac_timer);
218 }
219
220 void
ieee80211_dfs_cac_clear(struct ieee80211com * ic,const struct ieee80211_channel * chan)221 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
222 const struct ieee80211_channel *chan)
223 {
224 int i;
225
226 for (i = 0; i < ic->ic_nchans; i++) {
227 struct ieee80211_channel *c = &ic->ic_channels[i];
228 if (c->ic_freq == chan->ic_freq)
229 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
230 }
231 }
232
233 static void
dfs_timeout(void * arg)234 dfs_timeout(void *arg)
235 {
236 struct ieee80211com *ic = arg;
237 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
238 struct ieee80211_channel *c;
239 int i, oldest, now;
240
241 IEEE80211_LOCK_ASSERT(ic);
242
243 now = oldest = ticks;
244 for (i = 0; i < ic->ic_nchans; i++) {
245 c = &ic->ic_channels[i];
246 if (IEEE80211_IS_CHAN_RADAR(c)) {
247 if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
248 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
249 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
250 /*
251 * NB: do this here so we get only one
252 * msg instead of one for every channel
253 * table entry.
254 */
255 ic_printf(ic, "radar on channel %u "
256 "(%u MHz) cleared after timeout\n",
257 c->ic_ieee, c->ic_freq);
258 /* notify user space */
259 c->ic_state &=
260 ~IEEE80211_CHANSTATE_NORADAR;
261 ieee80211_notify_radar(ic, c);
262 }
263 } else if (dfs->nol_event[i] < oldest)
264 oldest = dfs->nol_event[i];
265 }
266 }
267 if (oldest != now) {
268 /* arrange to process next channel up for a status change */
269 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now);
270 }
271 }
272
273 static void
announce_radar(struct ieee80211com * ic,const struct ieee80211_channel * curchan,const struct ieee80211_channel * newchan)274 announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan,
275 const struct ieee80211_channel *newchan)
276 {
277 if (newchan == NULL)
278 ic_printf(ic, "radar detected on channel %u (%u MHz)\n",
279 curchan->ic_ieee, curchan->ic_freq);
280 else
281 ic_printf(ic, "radar detected on channel %u (%u MHz), "
282 "moving to channel %u (%u MHz)\n",
283 curchan->ic_ieee, curchan->ic_freq,
284 newchan->ic_ieee, newchan->ic_freq);
285 }
286
287 /*
288 * Handle a radar detection event on a channel. The channel is
289 * added to the NOL list and we record the time of the event.
290 * Entries are aged out after NOL_TIMEOUT. If radar was
291 * detected while doing CAC we force a state/channel change.
292 * Otherwise radar triggers a channel switch using the CSA
293 * mechanism (when the channel is the bss channel).
294 */
295 void
ieee80211_dfs_notify_radar(struct ieee80211com * ic,struct ieee80211_channel * chan)296 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
297 {
298 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
299 int i, now;
300
301 IEEE80211_LOCK_ASSERT(ic);
302
303 /*
304 * If doing DFS debugging (mode 2), don't bother
305 * running the rest of this function.
306 *
307 * Simply announce the presence of the radar and continue
308 * along merrily.
309 */
310 if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) {
311 announce_radar(ic, chan, chan);
312 ieee80211_notify_radar(ic, chan);
313 return;
314 }
315
316 /*
317 * Don't mark the channel and don't put it into NOL
318 * if we're doing DFS debugging.
319 */
320 if (ieee80211_dfs_debug == DFS_DBG_NONE) {
321 /*
322 * Mark all entries with this frequency. Notify user
323 * space and arrange for notification when the radar
324 * indication is cleared. Then kick the NOL processing
325 * thread if not already running.
326 */
327 now = ticks;
328 for (i = 0; i < ic->ic_nchans; i++) {
329 struct ieee80211_channel *c = &ic->ic_channels[i];
330 if (c->ic_freq == chan->ic_freq) {
331 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
332 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
333 dfs->nol_event[i] = now;
334 }
335 }
336 ieee80211_notify_radar(ic, chan);
337 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
338 if (!callout_pending(&dfs->nol_timer))
339 callout_reset(&dfs->nol_timer, NOL_TIMEOUT,
340 dfs_timeout, ic);
341 }
342
343 /*
344 * If radar is detected on the bss channel while
345 * doing CAC; force a state change by scheduling the
346 * callout to be dispatched asap. Otherwise, if this
347 * event is for the bss channel then we must quiet
348 * traffic and schedule a channel switch.
349 *
350 * Note this allows us to receive notification about
351 * channels other than the bss channel; not sure
352 * that can/will happen but it's simple to support.
353 */
354 if (chan == ic->ic_bsschan) {
355 /* XXX need a way to defer to user app */
356
357 /*
358 * Don't flip over to a new channel if
359 * we are currently doing DFS debugging.
360 */
361 if (ieee80211_dfs_debug == DFS_DBG_NONE)
362 dfs->newchan = ieee80211_dfs_pickchannel(ic);
363 else
364 dfs->newchan = chan;
365
366 announce_radar(ic, chan, dfs->newchan);
367
368 if (callout_pending(&dfs->cac_timer))
369 callout_schedule(&dfs->cac_timer, 0);
370 else if (dfs->newchan != NULL) {
371 /* XXX mode 1, switch count 2 */
372 /* XXX calculate switch count based on max
373 switch time and beacon interval? */
374 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
375 } else {
376 /*
377 * Spec says to stop all transmissions and
378 * wait on the current channel for an entry
379 * on the NOL to expire.
380 */
381 /*XXX*/
382 ic_printf(ic, "%s: No free channels; waiting for entry "
383 "on NOL to expire\n", __func__);
384 }
385 } else {
386 /*
387 * Issue rate-limited console msgs.
388 */
389 if (dfs->lastchan != chan) {
390 dfs->lastchan = chan;
391 dfs->cureps = 0;
392 announce_radar(ic, chan, NULL);
393 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
394 announce_radar(ic, chan, NULL);
395 }
396 }
397 }
398
399 struct ieee80211_channel *
ieee80211_dfs_pickchannel(struct ieee80211com * ic)400 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
401 {
402 struct ieee80211_channel *c;
403 int i, flags;
404 uint16_t v;
405
406 /*
407 * Consult the scan cache first.
408 */
409 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
410 /*
411 * XXX if curchan is HT this will never find a channel
412 * XXX 'cuz we scan only legacy channels
413 */
414 c = ieee80211_scan_pickchannel(ic, flags);
415 if (c != NULL)
416 return c;
417 /*
418 * No channel found in scan cache; select a compatible
419 * one at random (skipping channels where radar has
420 * been detected).
421 */
422 get_random_bytes(&v, sizeof(v));
423 v %= ic->ic_nchans;
424 for (i = v; i < ic->ic_nchans; i++) {
425 c = &ic->ic_channels[i];
426 if (!IEEE80211_IS_CHAN_RADAR(c) &&
427 (c->ic_flags & flags) == flags)
428 return c;
429 }
430 for (i = 0; i < v; i++) {
431 c = &ic->ic_channels[i];
432 if (!IEEE80211_IS_CHAN_RADAR(c) &&
433 (c->ic_flags & flags) == flags)
434 return c;
435 }
436 ic_printf(ic, "HELP, no channel located to switch to!\n");
437 return NULL;
438 }
439