2 * Copyright (c) 2007-2008 Sam Leffler, Errno Consulting
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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.
26 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
32 * IEEE 802.11 DFS/Radar support.
37 #include <sys/param.h>
38 #include <sys/systm.h>
40 #include <sys/malloc.h>
41 #include <sys/kernel.h>
43 #include <sys/socket.h>
44 #include <sys/sockio.h>
45 #include <sys/endian.h>
46 #include <sys/errno.h>
48 #include <sys/sysctl.h>
51 #include <net/if_media.h>
53 #include <net80211/ieee80211_var.h>
55 MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
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)
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)
68 ieee80211_dfs_attach(struct ieee80211com *ic)
70 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
72 callout_init(&dfs->nol_timer, CALLOUT_MPSAFE);
73 callout_init(&dfs->cac_timer, CALLOUT_MPSAFE);
77 ieee80211_dfs_detach(struct ieee80211com *ic)
79 /* NB: we assume no locking is needed */
80 ieee80211_dfs_reset(ic);
84 ieee80211_dfs_reset(struct ieee80211com *ic)
86 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
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;
98 cac_timeout(void *arg)
100 struct ieee80211vap *vap = arg;
101 struct ieee80211com *ic = vap->iv_ic;
102 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
105 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
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.
112 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
113 ieee80211_notify_cac(ic, ic->ic_curchan,
114 IEEE80211_NOTIFY_CAC_RADAR);
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);
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);
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);
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.
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;
139 ieee80211_notify_cac(ic, ic->ic_curchan,
140 IEEE80211_NOTIFY_CAC_EXPIRE);
141 ieee80211_cac_completeswitch(vap);
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.
151 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
153 struct ieee80211com *ic = vap->iv_ic;
154 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
156 IEEE80211_LOCK_ASSERT(ic);
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);
166 * Clear the CAC timer.
169 ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
171 struct ieee80211com *ic = vap->iv_ic;
172 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
174 IEEE80211_LOCK_ASSERT(ic);
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);
183 /* XXX cannot use drain 'cuz holding a lock */
184 callout_stop(&dfs->cac_timer);
188 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
189 const struct ieee80211_channel *chan)
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;
201 dfs_timeout(void *arg)
203 struct ieee80211com *ic = arg;
204 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
205 struct ieee80211_channel *c;
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) {
217 * NB: do this here so we get only one
218 * msg instead of one for every channel
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 */
226 ~IEEE80211_CHANSTATE_NORADAR;
227 ieee80211_notify_radar(ic, c);
229 } else if (dfs->nol_event[i] < oldest)
230 oldest = dfs->nol_event[i];
234 /* arrange to process next channel up for a status change */
235 callout_reset(&dfs->nol_timer, oldest + NOL_TIMEOUT,
238 IEEE80211_UNLOCK(ic);
242 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan,
243 const struct ieee80211_channel *newchan)
246 if_printf(ifp, "radar detected on channel %u (%u MHz)\n",
247 curchan->ic_ieee, curchan->ic_freq);
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);
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).
264 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
266 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
269 IEEE80211_LOCK_ASSERT(ic);
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.
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;
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);
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.
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.
302 if (chan == ic->ic_bsschan) {
303 /* XXX need a way to defer to user app */
304 dfs->newchan = ieee80211_dfs_pickchannel(ic);
306 announce_radar(ic->ic_ifp, chan, dfs->newchan);
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);
317 * Spec says to stop all transmissions and
318 * wait on the current channel for an entry
319 * on the NOL to expire.
325 * Issue rate-limited console msgs.
327 if (dfs->lastchan != chan) {
328 dfs->lastchan = chan;
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);
337 struct ieee80211_channel *
338 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
340 struct ieee80211_channel *c;
345 * Consult the scan cache first.
347 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
349 * XXX if curchan is HT this will never find a channel
350 * XXX 'cuz we scan only legacy channels
352 c = ieee80211_scan_pickchannel(ic, flags);
356 * No channel found in scan cache; select a compatible
357 * one at random (skipping channels where radar has
360 get_random_bytes(&v, sizeof(v));
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)
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)
374 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n");