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: src/sys/net80211/ieee80211_dfs.c,v 1.2 2008/08/02 17:58:39 sam Exp $");
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_media.h>
52
53 #include <net80211/ieee80211_var.h>
54
55 MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
56
57 /* XXX public for sysctl hookup */
58 int ieee80211_nol_timeout = 30*60; /* 30 minutes */
59 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
60 int ieee80211_cac_timeout = 60; /* 60 seconds */
61 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
62
63 void
64 ieee80211_dfs_attach(struct ieee80211com *ic)
65 {
66 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
67
68 callout_init(&dfs->nol_timer, CALLOUT_MPSAFE);
69 callout_init(&dfs->cac_timer, CALLOUT_MPSAFE);
70 }
71
72 void
73 ieee80211_dfs_detach(struct ieee80211com *ic)
74 {
75 /* NB: we assume no locking is needed */
76 ieee80211_dfs_reset(ic);
77 }
78
79 void
80 ieee80211_dfs_reset(struct ieee80211com *ic)
81 {
82 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
83 int i;
84
85 /* NB: we assume no locking is needed */
86 /* NB: cac_timer should be cleared by the state machine */
87 callout_drain(&dfs->nol_timer);
88 for (i = 0; i < ic->ic_nchans; i++)
89 ic->ic_channels[i].ic_state = 0;
90 dfs->lastchan = NULL;
91 }
92
93 static void
94 cac_timeout(void *arg)
95 {
96 struct ieee80211vap *vap = arg;
97 struct ieee80211com *ic = vap->iv_ic;
98 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
99 int i;
100
101 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
102 return;
103 /*
104 * When radar is detected during a CAC we are woken
105 * up prematurely to switch to a new channel.
106 * Check the channel to decide how to act.
107 */
108 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
109 ieee80211_notify_cac(ic, ic->ic_curchan,
110 IEEE80211_NOTIFY_CAC_RADAR);
111
112 if_printf(vap->iv_ifp,
113 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
114 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
115
116 /* XXX clobbers any existing desired channel */
117 /* NB: dfs->newchan may be NULL, that's ok */
118 vap->iv_des_chan = dfs->newchan;
119 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0);
120 } else {
121 if_printf(vap->iv_ifp,
122 "CAC timer on channel %u (%u MHz) expired; "
123 "no radar detected\n",
124 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
125 /*
126 * Mark all channels with the current frequency
127 * as having completed CAC; this keeps us from
128 * doing it again until we change channels.
129 */
130 for (i = 0; i < ic->ic_nchans; i++) {
131 struct ieee80211_channel *c = &ic->ic_channels[i];
132 if (c->ic_freq == ic->ic_curchan->ic_freq)
133 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
134 }
135 ieee80211_notify_cac(ic, ic->ic_curchan,
136 IEEE80211_NOTIFY_CAC_EXPIRE);
137 ieee80211_cac_completeswitch(vap);
138 }
139 }
140
141 /*
142 * Initiate the CAC timer. The driver is responsible
143 * for setting up the hardware to scan for radar on the
144 * channnel, we just handle timing things out.
145 */
146 void
147 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
148 {
149 struct ieee80211com *ic = vap->iv_ic;
150 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
151
152 IEEE80211_LOCK_ASSERT(ic);
153
154 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
155 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
156 ticks_to_secs(CAC_TIMEOUT),
157 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
158 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
159 }
160
161 /*
162 * Clear the CAC timer.
163 */
164 void
165 ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
166 {
167 struct ieee80211com *ic = vap->iv_ic;
168 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
169
170 IEEE80211_LOCK_ASSERT(ic);
171
172 /* NB: racey but not important */
173 if (callout_pending(&dfs->cac_timer)) {
174 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
175 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
176 ieee80211_notify_cac(ic, ic->ic_curchan,
177 IEEE80211_NOTIFY_CAC_STOP);
178 }
179 /* XXX cannot use drain 'cuz holding a lock */
180 callout_stop(&dfs->cac_timer);
181 }
182
183 void
184 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
185 const struct ieee80211_channel *chan)
186 {
187 int i;
188
189 for (i = 0; i < ic->ic_nchans; i++) {
190 struct ieee80211_channel *c = &ic->ic_channels[i];
191 if (c->ic_freq == chan->ic_freq)
192 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
193 }
194 }
195
196 static void
197 dfs_timeout(void *arg)
198 {
199 struct ieee80211com *ic = arg;
200 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
201 struct ieee80211_channel *c;
202 int i, oldest, now;
203
204 IEEE80211_LOCK(ic);
205 now = oldest = ticks;
206 for (i = 0; i < ic->ic_nchans; i++) {
207 c = &ic->ic_channels[i];
208 if (IEEE80211_IS_CHAN_RADAR(c)) {
209 if (time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
210 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
211 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
212 /*
213 * NB: do this here so we get only one
214 * msg instead of one for every channel
215 * table entry.
216 */
217 if_printf(ic->ic_ifp, "radar on channel"
218 " %u (%u MHz) cleared after timeout\n",
219 c->ic_ieee, c->ic_freq);
220 /* notify user space */
221 c->ic_state &=
222 ~IEEE80211_CHANSTATE_NORADAR;
223 ieee80211_notify_radar(ic, c);
224 }
225 } else if (dfs->nol_event[i] < oldest)
226 oldest = dfs->nol_event[i];
227 }
228 }
229 if (oldest != now) {
230 /* arrange to process next channel up for a status change */
231 callout_reset(&dfs->nol_timer, oldest + NOL_TIMEOUT,
232 dfs_timeout, ic);
233 }
234 IEEE80211_UNLOCK(ic);
235 }
236
237 static void
238 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan,
239 const struct ieee80211_channel *newchan)
240 {
241 if (newchan == NULL)
242 if_printf(ifp, "radar detected on channel %u (%u MHz)\n",
243 curchan->ic_ieee, curchan->ic_freq);
244 else
245 if_printf(ifp, "radar detected on channel %u (%u MHz), "
246 "moving to channel %u (%u MHz)\n",
247 curchan->ic_ieee, curchan->ic_freq,
248 newchan->ic_ieee, newchan->ic_freq);
249 }
250
251 /*
252 * Handle a radar detection event on a channel. The channel is
253 * added to the NOL list and we record the time of the event.
254 * Entries are aged out after NOL_TIMEOUT. If radar was
255 * detected while doing CAC we force a state/channel change.
256 * Otherwise radar triggers a channel switch using the CSA
257 * mechanism (when the channel is the bss channel).
258 */
259 void
260 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
261 {
262 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
263 int i, now;
264
265 IEEE80211_LOCK_ASSERT(ic);
266
267 /*
268 * Mark all entries with this frequency. Notify user
269 * space and arrange for notification when the radar
270 * indication is cleared. Then kick the NOL processing
271 * thread if not already running.
272 */
273 now = ticks;
274 for (i = 0; i < ic->ic_nchans; i++) {
275 struct ieee80211_channel *c = &ic->ic_channels[i];
276 if (c->ic_freq == chan->ic_freq) {
277 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
278 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
279 dfs->nol_event[i] = now;
280 }
281 }
282 ieee80211_notify_radar(ic, chan);
283 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
284 if (!callout_pending(&dfs->nol_timer))
285 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, dfs_timeout, ic);
286
287 /*
288 * If radar is detected on the bss channel while
289 * doing CAC; force a state change by scheduling the
290 * callout to be dispatched asap. Otherwise, if this
291 * event is for the bss channel then we must quiet
292 * traffic and schedule a channel switch.
293 *
294 * Note this allows us to receive notification about
295 * channels other than the bss channel; not sure
296 * that can/will happen but it's simple to support.
297 */
298 if (chan == ic->ic_bsschan) {
299 /* XXX need a way to defer to user app */
300 dfs->newchan = ieee80211_dfs_pickchannel(ic);
301
302 announce_radar(ic->ic_ifp, chan, dfs->newchan);
303
304 if (callout_pending(&dfs->cac_timer))
305 callout_schedule(&dfs->cac_timer, 0);
306 else if (dfs->newchan != NULL) {
307 /* XXX mode 1, switch count 2 */
308 /* XXX calculate switch count based on max
309 switch time and beacon interval? */
310 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
311 } else {
312 /*
313 * Spec says to stop all transmissions and
314 * wait on the current channel for an entry
315 * on the NOL to expire.
316 */
317 /*XXX*/
318 }
319 } else {
320 /*
321 * Issue rate-limited console msgs.
322 */
323 if (dfs->lastchan != chan) {
324 dfs->lastchan = chan;
325 dfs->cureps = 0;
326 announce_radar(ic->ic_ifp, chan, NULL);
327 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
328 announce_radar(ic->ic_ifp, chan, NULL);
329 }
330 }
331 }
332
333 struct ieee80211_channel *
334 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
335 {
336 struct ieee80211_channel *c;
337 int i, flags;
338 uint16_t v;
339
340 /*
341 * Consult the scan cache first.
342 */
343 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
344 /*
345 * XXX if curchan is HT this will never find a channel
346 * XXX 'cuz we scan only legacy channels
347 */
348 c = ieee80211_scan_pickchannel(ic, flags);
349 if (c != NULL)
350 return c;
351 /*
352 * No channel found in scan cache; select a compatible
353 * one at random (skipping channels where radar has
354 * been detected).
355 */
356 get_random_bytes(&v, sizeof(v));
357 v %= ic->ic_nchans;
358 for (i = v; i < ic->ic_nchans; i++) {
359 c = &ic->ic_channels[i];
360 if (!IEEE80211_IS_CHAN_RADAR(c) &&
361 (c->ic_flags & flags) == flags)
362 return c;
363 }
364 for (i = 0; i < v; i++) {
365 c = &ic->ic_channels[i];
366 if (!IEEE80211_IS_CHAN_RADAR(c) &&
367 (c->ic_flags & flags) == flags)
368 return c;
369 }
370 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n");
371 return NULL;
372 }
373
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