ieee80211_dfs.c revision 193666
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 193666 2009-06-07 23:16:59Z 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 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(&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_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT); 236 } 237 IEEE80211_UNLOCK(ic); 238} 239 240static void 241announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan, 242 const struct ieee80211_channel *newchan) 243{ 244 if (newchan == NULL) 245 if_printf(ifp, "radar detected on channel %u (%u MHz)\n", 246 curchan->ic_ieee, curchan->ic_freq); 247 else 248 if_printf(ifp, "radar detected on channel %u (%u MHz), " 249 "moving to channel %u (%u MHz)\n", 250 curchan->ic_ieee, curchan->ic_freq, 251 newchan->ic_ieee, newchan->ic_freq); 252} 253 254/* 255 * Handle a radar detection event on a channel. The channel is 256 * added to the NOL list and we record the time of the event. 257 * Entries are aged out after NOL_TIMEOUT. If radar was 258 * detected while doing CAC we force a state/channel change. 259 * Otherwise radar triggers a channel switch using the CSA 260 * mechanism (when the channel is the bss channel). 261 */ 262void 263ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 264{ 265 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 266 int i, now; 267 268 IEEE80211_LOCK_ASSERT(ic); 269 270 /* 271 * Mark all entries with this frequency. Notify user 272 * space and arrange for notification when the radar 273 * indication is cleared. Then kick the NOL processing 274 * thread if not already running. 275 */ 276 now = ticks; 277 for (i = 0; i < ic->ic_nchans; i++) { 278 struct ieee80211_channel *c = &ic->ic_channels[i]; 279 if (c->ic_freq == chan->ic_freq) { 280 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 281 c->ic_state |= IEEE80211_CHANSTATE_RADAR; 282 dfs->nol_event[i] = now; 283 } 284 } 285 ieee80211_notify_radar(ic, chan); 286 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR; 287 if (!callout_pending(&dfs->nol_timer)) 288 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, dfs_timeout, ic); 289 290 /* 291 * If radar is detected on the bss channel while 292 * doing CAC; force a state change by scheduling the 293 * callout to be dispatched asap. Otherwise, if this 294 * event is for the bss channel then we must quiet 295 * traffic and schedule a channel switch. 296 * 297 * Note this allows us to receive notification about 298 * channels other than the bss channel; not sure 299 * that can/will happen but it's simple to support. 300 */ 301 if (chan == ic->ic_bsschan) { 302 /* XXX need a way to defer to user app */ 303 dfs->newchan = ieee80211_dfs_pickchannel(ic); 304 305 announce_radar(ic->ic_ifp, chan, dfs->newchan); 306 307 if (callout_pending(&dfs->cac_timer)) 308 callout_schedule(&dfs->cac_timer, 0); 309 else if (dfs->newchan != NULL) { 310 /* XXX mode 1, switch count 2 */ 311 /* XXX calculate switch count based on max 312 switch time and beacon interval? */ 313 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 314 } else { 315 /* 316 * Spec says to stop all transmissions and 317 * wait on the current channel for an entry 318 * on the NOL to expire. 319 */ 320 /*XXX*/ 321 } 322 } else { 323 /* 324 * Issue rate-limited console msgs. 325 */ 326 if (dfs->lastchan != chan) { 327 dfs->lastchan = chan; 328 dfs->cureps = 0; 329 announce_radar(ic->ic_ifp, chan, NULL); 330 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 331 announce_radar(ic->ic_ifp, chan, NULL); 332 } 333 } 334} 335 336struct ieee80211_channel * 337ieee80211_dfs_pickchannel(struct ieee80211com *ic) 338{ 339 struct ieee80211_channel *c; 340 int i, flags; 341 uint16_t v; 342 343 /* 344 * Consult the scan cache first. 345 */ 346 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 347 /* 348 * XXX if curchan is HT this will never find a channel 349 * XXX 'cuz we scan only legacy channels 350 */ 351 c = ieee80211_scan_pickchannel(ic, flags); 352 if (c != NULL) 353 return c; 354 /* 355 * No channel found in scan cache; select a compatible 356 * one at random (skipping channels where radar has 357 * been detected). 358 */ 359 get_random_bytes(&v, sizeof(v)); 360 v %= ic->ic_nchans; 361 for (i = v; i < ic->ic_nchans; i++) { 362 c = &ic->ic_channels[i]; 363 if (!IEEE80211_IS_CHAN_RADAR(c) && 364 (c->ic_flags & flags) == flags) 365 return c; 366 } 367 for (i = 0; i < v; i++) { 368 c = &ic->ic_channels[i]; 369 if (!IEEE80211_IS_CHAN_RADAR(c) && 370 (c->ic_flags & flags) == flags) 371 return c; 372 } 373 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n"); 374 return NULL; 375} 376