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: releng/8.4/sys/net80211/ieee80211_dfs.c 199583 2009-11-20 15:27:52Z jhb $");
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 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
58 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
59 &ieee80211_nol_timeout, 0, "NOL timeout (secs)");
60 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
61
62 static int ieee80211_cac_timeout = 60; /* 60 seconds */
63 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
64 &ieee80211_cac_timeout, 0, "CAC timeout (secs)");
65 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
66
67 void
68 ieee80211_dfs_attach(struct ieee80211com *ic)
69 {
70 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
71
72 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0);
73 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0);
74 }
75
76 void
77 ieee80211_dfs_detach(struct ieee80211com *ic)
78 {
79 /* NB: we assume no locking is needed */
80 ieee80211_dfs_reset(ic);
81 }
82
83 void
84 ieee80211_dfs_reset(struct ieee80211com *ic)
85 {
86 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
87 int i;
88
89 /* NB: we assume no locking is needed */
90 /* NB: cac_timer should be cleared by the state machine */
91 callout_drain(&dfs->nol_timer);
92 for (i = 0; i < ic->ic_nchans; i++)
93 ic->ic_channels[i].ic_state = 0;
94 dfs->lastchan = NULL;
95 }
96
97 static void
98 cac_timeout(void *arg)
99 {
100 struct ieee80211vap *vap = arg;
101 struct ieee80211com *ic = vap->iv_ic;
102 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
103 int i;
104
105 IEEE80211_LOCK_ASSERT(ic);
106
107 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
108 return;
109 /*
110 * When radar is detected during a CAC we are woken
111 * up prematurely to switch to a new channel.
112 * Check the channel to decide how to act.
113 */
114 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
115 ieee80211_notify_cac(ic, ic->ic_curchan,
116 IEEE80211_NOTIFY_CAC_RADAR);
117
118 if_printf(vap->iv_ifp,
119 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
120 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
121
122 /* XXX clobbers any existing desired channel */
123 /* NB: dfs->newchan may be NULL, that's ok */
124 vap->iv_des_chan = dfs->newchan;
125 /* XXX recursive lock need ieee80211_new_state_locked */
126 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0);
127 } else {
128 if_printf(vap->iv_ifp,
129 "CAC timer on channel %u (%u MHz) expired; "
130 "no radar detected\n",
131 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
132 /*
133 * Mark all channels with the current frequency
134 * as having completed CAC; this keeps us from
135 * doing it again until we change channels.
136 */
137 for (i = 0; i < ic->ic_nchans; i++) {
138 struct ieee80211_channel *c = &ic->ic_channels[i];
139 if (c->ic_freq == ic->ic_curchan->ic_freq)
140 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
141 }
142 ieee80211_notify_cac(ic, ic->ic_curchan,
143 IEEE80211_NOTIFY_CAC_EXPIRE);
144 ieee80211_cac_completeswitch(vap);
145 }
146 }
147
148 /*
149 * Initiate the CAC timer. The driver is responsible
150 * for setting up the hardware to scan for radar on the
151 * channnel, we just handle timing things out.
152 */
153 void
154 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
155 {
156 struct ieee80211com *ic = vap->iv_ic;
157 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
158
159 IEEE80211_LOCK_ASSERT(ic);
160
161 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
162 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
163 ticks_to_secs(CAC_TIMEOUT),
164 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
165 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
166 }
167
168 /*
169 * Clear the CAC timer.
170 */
171 void
172 ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
173 {
174 struct ieee80211com *ic = vap->iv_ic;
175 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
176
177 IEEE80211_LOCK_ASSERT(ic);
178
179 /* NB: racey but not important */
180 if (callout_pending(&dfs->cac_timer)) {
181 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
182 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
183 ieee80211_notify_cac(ic, ic->ic_curchan,
184 IEEE80211_NOTIFY_CAC_STOP);
185 }
186 callout_stop(&dfs->cac_timer);
187 }
188
189 void
190 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
191 const struct ieee80211_channel *chan)
192 {
193 int i;
194
195 for (i = 0; i < ic->ic_nchans; i++) {
196 struct ieee80211_channel *c = &ic->ic_channels[i];
197 if (c->ic_freq == chan->ic_freq)
198 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
199 }
200 }
201
202 static void
203 dfs_timeout(void *arg)
204 {
205 struct ieee80211com *ic = arg;
206 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
207 struct ieee80211_channel *c;
208 int i, oldest, now;
209
210 IEEE80211_LOCK_ASSERT(ic);
211
212 now = oldest = ticks;
213 for (i = 0; i < ic->ic_nchans; i++) {
214 c = &ic->ic_channels[i];
215 if (IEEE80211_IS_CHAN_RADAR(c)) {
216 if (time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
217 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
218 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
219 /*
220 * NB: do this here so we get only one
221 * msg instead of one for every channel
222 * table entry.
223 */
224 if_printf(ic->ic_ifp, "radar on channel"
225 " %u (%u MHz) cleared after timeout\n",
226 c->ic_ieee, c->ic_freq);
227 /* notify user space */
228 c->ic_state &=
229 ~IEEE80211_CHANSTATE_NORADAR;
230 ieee80211_notify_radar(ic, c);
231 }
232 } else if (dfs->nol_event[i] < oldest)
233 oldest = dfs->nol_event[i];
234 }
235 }
236 if (oldest != now) {
237 /* arrange to process next channel up for a status change */
238 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now);
239 }
240 }
241
242 static void
243 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan,
244 const struct ieee80211_channel *newchan)
245 {
246 if (newchan == NULL)
247 if_printf(ifp, "radar detected on channel %u (%u MHz)\n",
248 curchan->ic_ieee, curchan->ic_freq);
249 else
250 if_printf(ifp, "radar detected on channel %u (%u MHz), "
251 "moving to channel %u (%u MHz)\n",
252 curchan->ic_ieee, curchan->ic_freq,
253 newchan->ic_ieee, newchan->ic_freq);
254 }
255
256 /*
257 * Handle a radar detection event on a channel. The channel is
258 * added to the NOL list and we record the time of the event.
259 * Entries are aged out after NOL_TIMEOUT. If radar was
260 * detected while doing CAC we force a state/channel change.
261 * Otherwise radar triggers a channel switch using the CSA
262 * mechanism (when the channel is the bss channel).
263 */
264 void
265 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
266 {
267 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
268 int i, now;
269
270 IEEE80211_LOCK_ASSERT(ic);
271
272 /*
273 * Mark all entries with this frequency. Notify user
274 * space and arrange for notification when the radar
275 * indication is cleared. Then kick the NOL processing
276 * thread if not already running.
277 */
278 now = ticks;
279 for (i = 0; i < ic->ic_nchans; i++) {
280 struct ieee80211_channel *c = &ic->ic_channels[i];
281 if (c->ic_freq == chan->ic_freq) {
282 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
283 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
284 dfs->nol_event[i] = now;
285 }
286 }
287 ieee80211_notify_radar(ic, chan);
288 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
289 if (!callout_pending(&dfs->nol_timer))
290 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, dfs_timeout, ic);
291
292 /*
293 * If radar is detected on the bss channel while
294 * doing CAC; force a state change by scheduling the
295 * callout to be dispatched asap. Otherwise, if this
296 * event is for the bss channel then we must quiet
297 * traffic and schedule a channel switch.
298 *
299 * Note this allows us to receive notification about
300 * channels other than the bss channel; not sure
301 * that can/will happen but it's simple to support.
302 */
303 if (chan == ic->ic_bsschan) {
304 /* XXX need a way to defer to user app */
305 dfs->newchan = ieee80211_dfs_pickchannel(ic);
306
307 announce_radar(ic->ic_ifp, chan, dfs->newchan);
308
309 if (callout_pending(&dfs->cac_timer))
310 callout_schedule(&dfs->cac_timer, 0);
311 else if (dfs->newchan != NULL) {
312 /* XXX mode 1, switch count 2 */
313 /* XXX calculate switch count based on max
314 switch time and beacon interval? */
315 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
316 } else {
317 /*
318 * Spec says to stop all transmissions and
319 * wait on the current channel for an entry
320 * on the NOL to expire.
321 */
322 /*XXX*/
323 }
324 } else {
325 /*
326 * Issue rate-limited console msgs.
327 */
328 if (dfs->lastchan != chan) {
329 dfs->lastchan = chan;
330 dfs->cureps = 0;
331 announce_radar(ic->ic_ifp, chan, NULL);
332 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
333 announce_radar(ic->ic_ifp, chan, NULL);
334 }
335 }
336 }
337
338 struct ieee80211_channel *
339 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
340 {
341 struct ieee80211_channel *c;
342 int i, flags;
343 uint16_t v;
344
345 /*
346 * Consult the scan cache first.
347 */
348 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
349 /*
350 * XXX if curchan is HT this will never find a channel
351 * XXX 'cuz we scan only legacy channels
352 */
353 c = ieee80211_scan_pickchannel(ic, flags);
354 if (c != NULL)
355 return c;
356 /*
357 * No channel found in scan cache; select a compatible
358 * one at random (skipping channels where radar has
359 * been detected).
360 */
361 get_random_bytes(&v, sizeof(v));
362 v %= ic->ic_nchans;
363 for (i = v; i < ic->ic_nchans; i++) {
364 c = &ic->ic_channels[i];
365 if (!IEEE80211_IS_CHAN_RADAR(c) &&
366 (c->ic_flags & flags) == flags)
367 return c;
368 }
369 for (i = 0; i < v; i++) {
370 c = &ic->ic_channels[i];
371 if (!IEEE80211_IS_CHAN_RADAR(c) &&
372 (c->ic_flags & flags) == flags)
373 return c;
374 }
375 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n");
376 return NULL;
377 }
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