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("$FreeBSD$");
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
55static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
56
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)
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_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0);
73	callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0);
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	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 */
153void
154ieee80211_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 */
171void
172ieee80211_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
189void
190ieee80211_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
202static void
203dfs_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
242static void
243announce_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 */
264void
265ieee80211_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			if_printf(ic->ic_ifp, "%s: No free channels; waiting for entry "
324			    "on NOL to expire\n", __func__);
325		}
326	} else {
327		/*
328		 * Issue rate-limited console msgs.
329		 */
330		if (dfs->lastchan != chan) {
331			dfs->lastchan = chan;
332			dfs->cureps = 0;
333			announce_radar(ic->ic_ifp, chan, NULL);
334		} else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
335			announce_radar(ic->ic_ifp, chan, NULL);
336		}
337	}
338}
339
340struct ieee80211_channel *
341ieee80211_dfs_pickchannel(struct ieee80211com *ic)
342{
343	struct ieee80211_channel *c;
344	int i, flags;
345	uint16_t v;
346
347	/*
348	 * Consult the scan cache first.
349	 */
350	flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
351	/*
352	 * XXX if curchan is HT this will never find a channel
353	 * XXX 'cuz we scan only legacy channels
354	 */
355	c = ieee80211_scan_pickchannel(ic, flags);
356	if (c != NULL)
357		return c;
358	/*
359	 * No channel found in scan cache; select a compatible
360	 * one at random (skipping channels where radar has
361	 * been detected).
362	 */
363	get_random_bytes(&v, sizeof(v));
364	v %= ic->ic_nchans;
365	for (i = v; i < ic->ic_nchans; i++) {
366		c = &ic->ic_channels[i];
367		if (!IEEE80211_IS_CHAN_RADAR(c) &&
368		   (c->ic_flags & flags) == flags)
369			return c;
370	}
371	for (i = 0; i < v; i++) {
372		c = &ic->ic_channels[i];
373		if (!IEEE80211_IS_CHAN_RADAR(c) &&
374		   (c->ic_flags & flags) == flags)
375			return c;
376	}
377	if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n");
378	return NULL;
379}
380