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.
25 * $FreeBSD: head/sys/net80211/ieee80211_dfs.c 196785 2009-09-03 16:29:02Z sam $
30 * IEEE 802.11 DFS/Radar support.
35 #include <sys/param.h>
36 #include <sys/systm.h>
38 #include <sys/malloc.h>
39 #include <sys/kernel.h>
41 #include <sys/socket.h>
42 #include <sys/sockio.h>
43 #include <sys/endian.h>
44 #include <sys/errno.h>
46 #include <sys/sysctl.h>
49 #include <net/if_media.h>
50 #include <net/route.h>
52 #include <netproto/802_11/ieee80211_var.h>
54 MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
56 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
57 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
58 &ieee80211_nol_timeout, 0, "NOL timeout (secs)");
59 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
61 static int ieee80211_cac_timeout = 60; /* 60 seconds */
62 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
63 &ieee80211_cac_timeout, 0, "CAC timeout (secs)");
64 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
67 ieee80211_dfs_attach(struct ieee80211com *ic)
69 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
71 callout_init(&dfs->nol_timer);
72 callout_init(&dfs->cac_timer);
76 ieee80211_dfs_detach(struct ieee80211com *ic)
78 /* NB: we assume no locking is needed */
79 ieee80211_dfs_reset(ic);
83 ieee80211_dfs_reset(struct ieee80211com *ic)
85 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
88 /* NB: we assume no locking is needed */
89 /* NB: cac_timer should be cleared by the state machine */
90 callout_stop(&dfs->nol_timer);
91 for (i = 0; i < ic->ic_nchans; i++)
92 ic->ic_channels[i].ic_state = 0;
97 cac_timeout(void *arg)
99 struct ieee80211vap *vap = arg;
100 struct ieee80211com *ic = vap->iv_ic;
101 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
106 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
109 * When radar is detected during a CAC we are woken
110 * up prematurely to switch to a new channel.
111 * Check the channel to decide how to act.
113 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
114 ieee80211_notify_cac(ic, ic->ic_curchan,
115 IEEE80211_NOTIFY_CAC_RADAR);
117 if_printf(vap->iv_ifp,
118 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
119 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
121 /* XXX clobbers any existing desired channel */
122 /* NB: dfs->newchan may be NULL, that's ok */
123 vap->iv_des_chan = dfs->newchan;
124 /* XXX recursive lock need ieee80211_new_state_locked */
125 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0);
127 if_printf(vap->iv_ifp,
128 "CAC timer on channel %u (%u MHz) expired; "
129 "no radar detected\n",
130 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
132 * Mark all channels with the current frequency
133 * as having completed CAC; this keeps us from
134 * doing it again until we change channels.
136 for (i = 0; i < ic->ic_nchans; i++) {
137 struct ieee80211_channel *c = &ic->ic_channels[i];
138 if (c->ic_freq == ic->ic_curchan->ic_freq)
139 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
141 ieee80211_notify_cac(ic, ic->ic_curchan,
142 IEEE80211_NOTIFY_CAC_EXPIRE);
143 ieee80211_cac_completeswitch(vap);
146 IEEE80211_UNLOCK(ic);
150 * Initiate the CAC timer. The driver is responsible
151 * for setting up the hardware to scan for radar on the
152 * channnel, we just handle timing things out.
155 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
157 struct ieee80211com *ic = vap->iv_ic;
158 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
160 IEEE80211_LOCK_ASSERT(ic);
162 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
163 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
164 ticks_to_secs(CAC_TIMEOUT),
165 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
166 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
170 * Clear the CAC timer.
173 ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
175 struct ieee80211com *ic = vap->iv_ic;
176 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
178 IEEE80211_LOCK_ASSERT(ic);
180 /* NB: racey but not important */
181 if (callout_pending(&dfs->cac_timer)) {
182 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
183 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
184 ieee80211_notify_cac(ic, ic->ic_curchan,
185 IEEE80211_NOTIFY_CAC_STOP);
187 callout_stop(&dfs->cac_timer);
191 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
192 const struct ieee80211_channel *chan)
196 for (i = 0; i < ic->ic_nchans; i++) {
197 struct ieee80211_channel *c = &ic->ic_channels[i];
198 if (c->ic_freq == chan->ic_freq)
199 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
204 dfs_timeout(void *arg)
206 struct ieee80211com *ic = arg;
207 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
208 struct ieee80211_channel *c;
213 now = oldest = ticks;
214 for (i = 0; i < ic->ic_nchans; i++) {
215 c = &ic->ic_channels[i];
216 if (IEEE80211_IS_CHAN_RADAR(c)) {
217 if (time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
218 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
219 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
221 * NB: do this here so we get only one
222 * msg instead of one for every channel
225 if_printf(ic->ic_ifp, "radar on channel"
226 " %u (%u MHz) cleared after timeout\n",
227 c->ic_ieee, c->ic_freq);
228 /* notify user space */
230 ~IEEE80211_CHANSTATE_NORADAR;
231 ieee80211_notify_radar(ic, c);
233 } else if (dfs->nol_event[i] < oldest)
234 oldest = dfs->nol_event[i];
238 /* arrange to process next channel up for a status change */
239 callout_reset(&dfs->nol_timer, oldest + NOL_TIMEOUT - now,
243 IEEE80211_UNLOCK(ic);
247 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan,
248 const struct ieee80211_channel *newchan)
251 if_printf(ifp, "radar detected on channel %u (%u MHz)\n",
252 curchan->ic_ieee, curchan->ic_freq);
254 if_printf(ifp, "radar detected on channel %u (%u MHz), "
255 "moving to channel %u (%u MHz)\n",
256 curchan->ic_ieee, curchan->ic_freq,
257 newchan->ic_ieee, newchan->ic_freq);
261 * Handle a radar detection event on a channel. The channel is
262 * added to the NOL list and we record the time of the event.
263 * Entries are aged out after NOL_TIMEOUT. If radar was
264 * detected while doing CAC we force a state/channel change.
265 * Otherwise radar triggers a channel switch using the CSA
266 * mechanism (when the channel is the bss channel).
269 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
271 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
274 IEEE80211_LOCK_ASSERT(ic);
277 * Mark all entries with this frequency. Notify user
278 * space and arrange for notification when the radar
279 * indication is cleared. Then kick the NOL processing
280 * thread if not already running.
283 for (i = 0; i < ic->ic_nchans; i++) {
284 struct ieee80211_channel *c = &ic->ic_channels[i];
285 if (c->ic_freq == chan->ic_freq) {
286 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
287 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
288 dfs->nol_event[i] = now;
291 ieee80211_notify_radar(ic, chan);
292 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
293 if (!callout_pending(&dfs->nol_timer))
294 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, dfs_timeout, ic);
297 * If radar is detected on the bss channel while
298 * doing CAC; force a state change by scheduling the
299 * callout to be dispatched asap. Otherwise, if this
300 * event is for the bss channel then we must quiet
301 * traffic and schedule a channel switch.
303 * Note this allows us to receive notification about
304 * channels other than the bss channel; not sure
305 * that can/will happen but it's simple to support.
307 if (chan == ic->ic_bsschan) {
308 /* XXX need a way to defer to user app */
309 dfs->newchan = ieee80211_dfs_pickchannel(ic);
311 announce_radar(ic->ic_ifp, chan, dfs->newchan);
314 if (callout_pending(&dfs->cac_timer))
315 callout_reset(&dfs->cac_timer, 0, cac_timeout, vap);
316 else if (dfs->newchan != NULL) {
317 /* XXX mode 1, switch count 2 */
318 /* XXX calculate switch count based on max
319 switch time and beacon interval? */
320 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
323 * Spec says to stop all transmissions and
324 * wait on the current channel for an entry
325 * on the NOL to expire.
332 * Issue rate-limited console msgs.
334 if (dfs->lastchan != chan) {
335 dfs->lastchan = chan;
337 announce_radar(ic->ic_ifp, chan, NULL);
338 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
339 announce_radar(ic->ic_ifp, chan, NULL);
344 struct ieee80211_channel *
345 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
347 struct ieee80211_channel *c;
352 * Consult the scan cache first.
354 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
356 * XXX if curchan is HT this will never find a channel
357 * XXX 'cuz we scan only legacy channels
359 c = ieee80211_scan_pickchannel(ic, flags);
363 * No channel found in scan cache; select a compatible
364 * one at random (skipping channels where radar has
367 get_random_bytes(&v, sizeof(v));
369 for (i = v; i < ic->ic_nchans; i++) {
370 c = &ic->ic_channels[i];
371 if (!IEEE80211_IS_CHAN_RADAR(c) &&
372 (c->ic_flags & flags) == flags)
375 for (i = 0; i < v; i++) {
376 c = &ic->ic_channels[i];
377 if (!IEEE80211_IS_CHAN_RADAR(c) &&
378 (c->ic_flags & flags) == flags)
381 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n");