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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: head/sys/net80211/ieee80211_dfs.c 181193 2008-08-02 17:58:39Z sam $");
28__FBSDID("$FreeBSD: head/sys/net80211/ieee80211_dfs.c 193115 2009-05-30 20:11:23Z sam $");
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
55MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
56
57/* XXX public for sysctl hookup */
58int ieee80211_nol_timeout = 30*60; /* 30 minutes */
57static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
58SYSCTL_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)
60int ieee80211_cac_timeout = 60; /* 60 seconds */
61
62static int ieee80211_cac_timeout = 60; /* 60 seconds */
63SYSCTL_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
67void
68ieee80211_dfs_attach(struct ieee80211com *ic)
69{
70 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
71
72 callout_init(&dfs->nol_timer, CALLOUT_MPSAFE);
73 callout_init(&dfs->cac_timer, CALLOUT_MPSAFE);
74}
75
76void
77ieee80211_dfs_detach(struct ieee80211com *ic)
78{
79 /* NB: we assume no locking is needed */
80 ieee80211_dfs_reset(ic);
81}
82
83void
84ieee80211_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
97static void
98cac_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 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
106 return;
107 /*
108 * When radar is detected during a CAC we are woken
109 * up prematurely to switch to a new channel.
110 * Check the channel to decide how to act.
111 */
112 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
113 ieee80211_notify_cac(ic, ic->ic_curchan,
114 IEEE80211_NOTIFY_CAC_RADAR);
115
116 if_printf(vap->iv_ifp,
117 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
118 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
119
120 /* XXX clobbers any existing desired channel */
121 /* NB: dfs->newchan may be NULL, that's ok */
122 vap->iv_des_chan = dfs->newchan;
123 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0);
124 } else {
125 if_printf(vap->iv_ifp,
126 "CAC timer on channel %u (%u MHz) expired; "
127 "no radar detected\n",
128 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
129 /*
130 * Mark all channels with the current frequency
131 * as having completed CAC; this keeps us from
132 * doing it again until we change channels.
133 */
134 for (i = 0; i < ic->ic_nchans; i++) {
135 struct ieee80211_channel *c = &ic->ic_channels[i];
136 if (c->ic_freq == ic->ic_curchan->ic_freq)
137 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
138 }
139 ieee80211_notify_cac(ic, ic->ic_curchan,
140 IEEE80211_NOTIFY_CAC_EXPIRE);
141 ieee80211_cac_completeswitch(vap);
142 }
143}
144
145/*
146 * Initiate the CAC timer. The driver is responsible
147 * for setting up the hardware to scan for radar on the
148 * channnel, we just handle timing things out.
149 */
150void
151ieee80211_dfs_cac_start(struct ieee80211vap *vap)
152{
153 struct ieee80211com *ic = vap->iv_ic;
154 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
155
156 IEEE80211_LOCK_ASSERT(ic);
157
158 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
159 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
160 ticks_to_secs(CAC_TIMEOUT),
161 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
162 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
163}
164
165/*
166 * Clear the CAC timer.
167 */
168void
169ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
170{
171 struct ieee80211com *ic = vap->iv_ic;
172 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
173
174 IEEE80211_LOCK_ASSERT(ic);
175
176 /* NB: racey but not important */
177 if (callout_pending(&dfs->cac_timer)) {
178 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
179 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
180 ieee80211_notify_cac(ic, ic->ic_curchan,
181 IEEE80211_NOTIFY_CAC_STOP);
182 }
183 /* XXX cannot use drain 'cuz holding a lock */
184 callout_stop(&dfs->cac_timer);
185}
186
187void
188ieee80211_dfs_cac_clear(struct ieee80211com *ic,
189 const struct ieee80211_channel *chan)
190{
191 int i;
192
193 for (i = 0; i < ic->ic_nchans; i++) {
194 struct ieee80211_channel *c = &ic->ic_channels[i];
195 if (c->ic_freq == chan->ic_freq)
196 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
197 }
198}
199
200static void
201dfs_timeout(void *arg)
202{
203 struct ieee80211com *ic = arg;
204 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
205 struct ieee80211_channel *c;
206 int i, oldest, now;
207
208 IEEE80211_LOCK(ic);
209 now = oldest = ticks;
210 for (i = 0; i < ic->ic_nchans; i++) {
211 c = &ic->ic_channels[i];
212 if (IEEE80211_IS_CHAN_RADAR(c)) {
213 if (time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
214 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
215 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
216 /*
217 * NB: do this here so we get only one
218 * msg instead of one for every channel
219 * table entry.
220 */
221 if_printf(ic->ic_ifp, "radar on channel"
222 " %u (%u MHz) cleared after timeout\n",
223 c->ic_ieee, c->ic_freq);
224 /* notify user space */
225 c->ic_state &=
226 ~IEEE80211_CHANSTATE_NORADAR;
227 ieee80211_notify_radar(ic, c);
228 }
229 } else if (dfs->nol_event[i] < oldest)
230 oldest = dfs->nol_event[i];
231 }
232 }
233 if (oldest != now) {
234 /* arrange to process next channel up for a status change */
235 callout_reset(&dfs->nol_timer, oldest + NOL_TIMEOUT,
236 dfs_timeout, ic);
237 }
238 IEEE80211_UNLOCK(ic);
239}
240
241static void
242announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan,
243 const struct ieee80211_channel *newchan)
244{
245 if (newchan == NULL)
246 if_printf(ifp, "radar detected on channel %u (%u MHz)\n",
247 curchan->ic_ieee, curchan->ic_freq);
248 else
249 if_printf(ifp, "radar detected on channel %u (%u MHz), "
250 "moving to channel %u (%u MHz)\n",
251 curchan->ic_ieee, curchan->ic_freq,
252 newchan->ic_ieee, newchan->ic_freq);
253}
254
255/*
256 * Handle a radar detection event on a channel. The channel is
257 * added to the NOL list and we record the time of the event.
258 * Entries are aged out after NOL_TIMEOUT. If radar was
259 * detected while doing CAC we force a state/channel change.
260 * Otherwise radar triggers a channel switch using the CSA
261 * mechanism (when the channel is the bss channel).
262 */
263void
264ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
265{
266 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
267 int i, now;
268
269 IEEE80211_LOCK_ASSERT(ic);
270
271 /*
272 * Mark all entries with this frequency. Notify user
273 * space and arrange for notification when the radar
274 * indication is cleared. Then kick the NOL processing
275 * thread if not already running.
276 */
277 now = ticks;
278 for (i = 0; i < ic->ic_nchans; i++) {
279 struct ieee80211_channel *c = &ic->ic_channels[i];
280 if (c->ic_freq == chan->ic_freq) {
281 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
282 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
283 dfs->nol_event[i] = now;
284 }
285 }
286 ieee80211_notify_radar(ic, chan);
287 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
288 if (!callout_pending(&dfs->nol_timer))
289 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, dfs_timeout, ic);
290
291 /*
292 * If radar is detected on the bss channel while
293 * doing CAC; force a state change by scheduling the
294 * callout to be dispatched asap. Otherwise, if this
295 * event is for the bss channel then we must quiet
296 * traffic and schedule a channel switch.
297 *
298 * Note this allows us to receive notification about
299 * channels other than the bss channel; not sure
300 * that can/will happen but it's simple to support.
301 */
302 if (chan == ic->ic_bsschan) {
303 /* XXX need a way to defer to user app */
304 dfs->newchan = ieee80211_dfs_pickchannel(ic);
305
306 announce_radar(ic->ic_ifp, chan, dfs->newchan);
307
308 if (callout_pending(&dfs->cac_timer))
309 callout_schedule(&dfs->cac_timer, 0);
310 else if (dfs->newchan != NULL) {
311 /* XXX mode 1, switch count 2 */
312 /* XXX calculate switch count based on max
313 switch time and beacon interval? */
314 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
315 } else {
316 /*
317 * Spec says to stop all transmissions and
318 * wait on the current channel for an entry
319 * on the NOL to expire.
320 */
321 /*XXX*/
322 }
323 } else {
324 /*
325 * Issue rate-limited console msgs.
326 */
327 if (dfs->lastchan != chan) {
328 dfs->lastchan = chan;
329 dfs->cureps = 0;
330 announce_radar(ic->ic_ifp, chan, NULL);
331 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
332 announce_radar(ic->ic_ifp, chan, NULL);
333 }
334 }
335}
336
337struct ieee80211_channel *
338ieee80211_dfs_pickchannel(struct ieee80211com *ic)
339{
340 struct ieee80211_channel *c;
341 int i, flags;
342 uint16_t v;
343
344 /*
345 * Consult the scan cache first.
346 */
347 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
348 /*
349 * XXX if curchan is HT this will never find a channel
350 * XXX 'cuz we scan only legacy channels
351 */
352 c = ieee80211_scan_pickchannel(ic, flags);
353 if (c != NULL)
354 return c;
355 /*
356 * No channel found in scan cache; select a compatible
357 * one at random (skipping channels where radar has
358 * been detected).
359 */
360 get_random_bytes(&v, sizeof(v));
361 v %= ic->ic_nchans;
362 for (i = v; i < ic->ic_nchans; i++) {
363 c = &ic->ic_channels[i];
364 if (!IEEE80211_IS_CHAN_RADAR(c) &&
365 (c->ic_flags & flags) == flags)
366 return c;
367 }
368 for (i = 0; i < v; i++) {
369 c = &ic->ic_channels[i];
370 if (!IEEE80211_IS_CHAN_RADAR(c) &&
371 (c->ic_flags & flags) == flags)
372 return c;
373 }
374 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n");
375 return NULL;
376}