2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2007-2008 Sam Leffler, Errno Consulting
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
34 * IEEE 802.11 DFS/Radar support.
39 #include <sys/param.h>
40 #include <sys/systm.h>
42 #include <sys/malloc.h>
43 #include <sys/kernel.h>
45 #include <sys/socket.h>
46 #include <sys/sockio.h>
47 #include <sys/endian.h>
48 #include <sys/errno.h>
50 #include <sys/sysctl.h>
53 #include <net/if_var.h>
54 #include <net/if_media.h>
55 #include <net/ethernet.h>
57 #include <net80211/ieee80211_var.h>
59 static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
61 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
62 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
63 &ieee80211_nol_timeout, 0, "NOL timeout (secs)");
64 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
66 static int ieee80211_cac_timeout = 60; /* 60 seconds */
67 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
68 &ieee80211_cac_timeout, 0, "CAC timeout (secs)");
69 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
72 DFS* In order to facilitate debugging, a couple of operating
73 * modes aside from the default are needed.
75 * 0 - default CAC/NOL behaviour - ie, start CAC, place
76 * channel on NOL list.
77 * 1 - send CAC, but don't change channel or add the channel
79 * 2 - just match on radar, don't send CAC or place channel in
82 static int ieee80211_dfs_debug = DFS_DBG_NONE;
85 * This option must not be included in the default kernel
86 * as it allows users to plainly disable CAC/NOL handling.
88 #ifdef IEEE80211_DFS_DEBUG
89 SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW,
90 &ieee80211_dfs_debug, 0, "DFS debug behaviour");
94 null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm)
100 ieee80211_dfs_attach(struct ieee80211com *ic)
102 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
104 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0);
105 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0);
107 ic->ic_set_quiet = null_set_quiet;
111 ieee80211_dfs_detach(struct ieee80211com *ic)
113 /* NB: we assume no locking is needed */
114 ieee80211_dfs_reset(ic);
118 ieee80211_dfs_reset(struct ieee80211com *ic)
120 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
123 /* NB: we assume no locking is needed */
124 /* NB: cac_timer should be cleared by the state machine */
125 callout_drain(&dfs->nol_timer);
126 for (i = 0; i < ic->ic_nchans; i++)
127 ic->ic_channels[i].ic_state = 0;
128 dfs->lastchan = NULL;
132 cac_timeout(void *arg)
134 struct ieee80211vap *vap = arg;
135 struct ieee80211com *ic = vap->iv_ic;
136 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
139 IEEE80211_LOCK_ASSERT(ic);
141 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
144 * When radar is detected during a CAC we are woken
145 * up prematurely to switch to a new channel.
146 * Check the channel to decide how to act.
148 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
149 ieee80211_notify_cac(ic, ic->ic_curchan,
150 IEEE80211_NOTIFY_CAC_RADAR);
152 if_printf(vap->iv_ifp,
153 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
154 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
156 /* XXX clobbers any existing desired channel */
157 /* NB: dfs->newchan may be NULL, that's ok */
158 vap->iv_des_chan = dfs->newchan;
159 ieee80211_new_state_locked(vap, IEEE80211_S_SCAN, 0);
161 if_printf(vap->iv_ifp,
162 "CAC timer on channel %u (%u MHz) expired; "
163 "no radar detected\n",
164 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
166 * Mark all channels with the current frequency
167 * as having completed CAC; this keeps us from
168 * doing it again until we change channels.
170 for (i = 0; i < ic->ic_nchans; i++) {
171 struct ieee80211_channel *c = &ic->ic_channels[i];
172 if (c->ic_freq == ic->ic_curchan->ic_freq)
173 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
175 ieee80211_notify_cac(ic, ic->ic_curchan,
176 IEEE80211_NOTIFY_CAC_EXPIRE);
177 ieee80211_cac_completeswitch(vap);
182 * Initiate the CAC timer. The driver is responsible
183 * for setting up the hardware to scan for radar on the
184 * channnel, we just handle timing things out.
187 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
189 struct ieee80211com *ic = vap->iv_ic;
190 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
192 IEEE80211_LOCK_ASSERT(ic);
194 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
195 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
196 ticks_to_secs(CAC_TIMEOUT),
197 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
198 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
202 * Clear the CAC timer.
205 ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
207 struct ieee80211com *ic = vap->iv_ic;
208 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
210 IEEE80211_LOCK_ASSERT(ic);
212 /* NB: racey but not important */
213 if (callout_pending(&dfs->cac_timer)) {
214 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
215 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
216 ieee80211_notify_cac(ic, ic->ic_curchan,
217 IEEE80211_NOTIFY_CAC_STOP);
219 callout_stop(&dfs->cac_timer);
223 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
224 const struct ieee80211_channel *chan)
228 for (i = 0; i < ic->ic_nchans; i++) {
229 struct ieee80211_channel *c = &ic->ic_channels[i];
230 if (c->ic_freq == chan->ic_freq)
231 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
236 dfs_timeout(void *arg)
238 struct ieee80211com *ic = arg;
239 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
240 struct ieee80211_channel *c;
243 IEEE80211_LOCK_ASSERT(ic);
245 now = oldest = ticks;
246 for (i = 0; i < ic->ic_nchans; i++) {
247 c = &ic->ic_channels[i];
248 if (IEEE80211_IS_CHAN_RADAR(c)) {
249 if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
250 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
251 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
253 * NB: do this here so we get only one
254 * msg instead of one for every channel
257 ic_printf(ic, "radar on channel %u "
258 "(%u MHz) cleared after timeout\n",
259 c->ic_ieee, c->ic_freq);
260 /* notify user space */
262 ~IEEE80211_CHANSTATE_NORADAR;
263 ieee80211_notify_radar(ic, c);
265 } else if (dfs->nol_event[i] < oldest)
266 oldest = dfs->nol_event[i];
270 /* arrange to process next channel up for a status change */
271 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now);
276 announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan,
277 const struct ieee80211_channel *newchan)
280 ic_printf(ic, "radar detected on channel %u (%u MHz)\n",
281 curchan->ic_ieee, curchan->ic_freq);
283 ic_printf(ic, "radar detected on channel %u (%u MHz), "
284 "moving to channel %u (%u MHz)\n",
285 curchan->ic_ieee, curchan->ic_freq,
286 newchan->ic_ieee, newchan->ic_freq);
290 * Handle a radar detection event on a channel. The channel is
291 * added to the NOL list and we record the time of the event.
292 * Entries are aged out after NOL_TIMEOUT. If radar was
293 * detected while doing CAC we force a state/channel change.
294 * Otherwise radar triggers a channel switch using the CSA
295 * mechanism (when the channel is the bss channel).
298 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
300 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
303 IEEE80211_LOCK_ASSERT(ic);
306 * If doing DFS debugging (mode 2), don't bother
307 * running the rest of this function.
309 * Simply announce the presence of the radar and continue
312 if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) {
313 announce_radar(ic, chan, chan);
314 ieee80211_notify_radar(ic, chan);
319 * Don't mark the channel and don't put it into NOL
320 * if we're doing DFS debugging.
322 if (ieee80211_dfs_debug == DFS_DBG_NONE) {
324 * Mark all entries with this frequency. Notify user
325 * space and arrange for notification when the radar
326 * indication is cleared. Then kick the NOL processing
327 * thread if not already running.
330 for (i = 0; i < ic->ic_nchans; i++) {
331 struct ieee80211_channel *c = &ic->ic_channels[i];
332 if (c->ic_freq == chan->ic_freq) {
333 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
334 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
335 dfs->nol_event[i] = now;
338 ieee80211_notify_radar(ic, chan);
339 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
340 if (!callout_pending(&dfs->nol_timer))
341 callout_reset(&dfs->nol_timer, NOL_TIMEOUT,
346 * If radar is detected on the bss channel while
347 * doing CAC; force a state change by scheduling the
348 * callout to be dispatched asap. Otherwise, if this
349 * event is for the bss channel then we must quiet
350 * traffic and schedule a channel switch.
352 * Note this allows us to receive notification about
353 * channels other than the bss channel; not sure
354 * that can/will happen but it's simple to support.
356 if (chan == ic->ic_bsschan) {
357 /* XXX need a way to defer to user app */
360 * Don't flip over to a new channel if
361 * we are currently doing DFS debugging.
363 if (ieee80211_dfs_debug == DFS_DBG_NONE)
364 dfs->newchan = ieee80211_dfs_pickchannel(ic);
368 announce_radar(ic, chan, dfs->newchan);
370 if (callout_pending(&dfs->cac_timer))
371 callout_schedule(&dfs->cac_timer, 0);
372 else if (dfs->newchan != NULL) {
373 /* XXX mode 1, switch count 2 */
374 /* XXX calculate switch count based on max
375 switch time and beacon interval? */
376 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
379 * Spec says to stop all transmissions and
380 * wait on the current channel for an entry
381 * on the NOL to expire.
384 ic_printf(ic, "%s: No free channels; waiting for entry "
385 "on NOL to expire\n", __func__);
389 * Issue rate-limited console msgs.
391 if (dfs->lastchan != chan) {
392 dfs->lastchan = chan;
394 announce_radar(ic, chan, NULL);
395 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
396 announce_radar(ic, chan, NULL);
401 struct ieee80211_channel *
402 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
404 struct ieee80211_channel *c;
409 * Consult the scan cache first.
411 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
413 * XXX if curchan is HT this will never find a channel
414 * XXX 'cuz we scan only legacy channels
416 c = ieee80211_scan_pickchannel(ic, flags);
420 * No channel found in scan cache; select a compatible
421 * one at random (skipping channels where radar has
424 get_random_bytes(&v, sizeof(v));
426 for (i = v; i < ic->ic_nchans; i++) {
427 c = &ic->ic_channels[i];
428 if (!IEEE80211_IS_CHAN_RADAR(c) &&
429 (c->ic_flags & flags) == flags)
432 for (i = 0; i < v; i++) {
433 c = &ic->ic_channels[i];
434 if (!IEEE80211_IS_CHAN_RADAR(c) &&
435 (c->ic_flags & flags) == flags)
438 ic_printf(ic, "HELP, no channel located to switch to!\n");