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 55 MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state"); 56 57 /* XXX public for sysctl hookup */ 58 int ieee80211_nol_timeout = 30*60; /* 30 minutes */ 59 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000) 60 int ieee80211_cac_timeout = 60; /* 60 seconds */ 61 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000) 62 63 void 64 ieee80211_dfs_attach(struct ieee80211com *ic) 65 { 66 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 67 68 callout_init(&dfs->nol_timer, CALLOUT_MPSAFE); 69 callout_init(&dfs->cac_timer, CALLOUT_MPSAFE); 70 } 71 72 void 73 ieee80211_dfs_detach(struct ieee80211com *ic) 74 { 75 /* NB: we assume no locking is needed */ 76 ieee80211_dfs_reset(ic); 77 } 78 79 void 80 ieee80211_dfs_reset(struct ieee80211com *ic) 81 { 82 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 83 int i; 84 85 /* NB: we assume no locking is needed */ 86 /* NB: cac_timer should be cleared by the state machine */ 87 callout_drain(&dfs->nol_timer); 88 for (i = 0; i < ic->ic_nchans; i++) 89 ic->ic_channels[i].ic_state = 0; 90 dfs->lastchan = NULL; 91 } 92 93 static void 94 cac_timeout(void *arg) 95 { 96 struct ieee80211vap *vap = arg; 97 struct ieee80211com *ic = vap->iv_ic; 98 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 99 int i; 100 101 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */ 102 return; 103 /* 104 * When radar is detected during a CAC we are woken 105 * up prematurely to switch to a new channel. 106 * Check the channel to decide how to act. 107 */ 108 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) { 109 ieee80211_notify_cac(ic, ic->ic_curchan, 110 IEEE80211_NOTIFY_CAC_RADAR); 111 112 if_printf(vap->iv_ifp, 113 "CAC timer on channel %u (%u MHz) stopped due to radar\n", 114 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 115 116 /* XXX clobbers any existing desired channel */ 117 /* NB: dfs->newchan may be NULL, that's ok */ 118 vap->iv_des_chan = dfs->newchan; 119 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0); 120 } else { 121 if_printf(vap->iv_ifp, 122 "CAC timer on channel %u (%u MHz) expired; " 123 "no radar detected\n", 124 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 125 /* 126 * Mark all channels with the current frequency 127 * as having completed CAC; this keeps us from 128 * doing it again until we change channels. 129 */ 130 for (i = 0; i < ic->ic_nchans; i++) { 131 struct ieee80211_channel *c = &ic->ic_channels[i]; 132 if (c->ic_freq == ic->ic_curchan->ic_freq) 133 c->ic_state |= IEEE80211_CHANSTATE_CACDONE; 134 } 135 ieee80211_notify_cac(ic, ic->ic_curchan, 136 IEEE80211_NOTIFY_CAC_EXPIRE); 137 ieee80211_cac_completeswitch(vap); 138 } 139 } 140 141 /* 142 * Initiate the CAC timer. The driver is responsible 143 * for setting up the hardware to scan for radar on the 144 * channnel, we just handle timing things out. 145 */ 146 void 147 ieee80211_dfs_cac_start(struct ieee80211vap *vap) 148 { 149 struct ieee80211com *ic = vap->iv_ic; 150 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 151 152 IEEE80211_LOCK_ASSERT(ic); 153 154 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap); 155 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n", 156 ticks_to_secs(CAC_TIMEOUT), 157 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 158 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START); 159 } 160 161 /* 162 * Clear the CAC timer. 163 */ 164 void 165 ieee80211_dfs_cac_stop(struct ieee80211vap *vap) 166 { 167 struct ieee80211com *ic = vap->iv_ic; 168 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 169 170 IEEE80211_LOCK_ASSERT(ic); 171 172 /* NB: racey but not important */ 173 if (callout_pending(&dfs->cac_timer)) { 174 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n", 175 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 176 ieee80211_notify_cac(ic, ic->ic_curchan, 177 IEEE80211_NOTIFY_CAC_STOP); 178 } 179 /* XXX cannot use drain 'cuz holding a lock */ 180 callout_stop(&dfs->cac_timer); 181 } 182 183 void 184 ieee80211_dfs_cac_clear(struct ieee80211com *ic, 185 const struct ieee80211_channel *chan) 186 { 187 int i; 188 189 for (i = 0; i < ic->ic_nchans; i++) { 190 struct ieee80211_channel *c = &ic->ic_channels[i]; 191 if (c->ic_freq == chan->ic_freq) 192 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 193 } 194 } 195 196 static void 197 dfs_timeout(void *arg) 198 { 199 struct ieee80211com *ic = arg; 200 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 201 struct ieee80211_channel *c; 202 int i, oldest, now; 203 204 IEEE80211_LOCK(ic); 205 now = oldest = ticks; 206 for (i = 0; i < ic->ic_nchans; i++) { 207 c = &ic->ic_channels[i]; 208 if (IEEE80211_IS_CHAN_RADAR(c)) { 209 if (time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) { 210 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR; 211 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) { 212 /* 213 * NB: do this here so we get only one 214 * msg instead of one for every channel 215 * table entry. 216 */ 217 if_printf(ic->ic_ifp, "radar on channel" 218 " %u (%u MHz) cleared after timeout\n", 219 c->ic_ieee, c->ic_freq); 220 /* notify user space */ 221 c->ic_state &= 222 ~IEEE80211_CHANSTATE_NORADAR; 223 ieee80211_notify_radar(ic, c); 224 } 225 } else if (dfs->nol_event[i] < oldest) 226 oldest = dfs->nol_event[i]; 227 } 228 } 229 if (oldest != now) { 230 /* arrange to process next channel up for a status change */ 231 callout_reset(&dfs->nol_timer, oldest + NOL_TIMEOUT, 232 dfs_timeout, ic); 233 } 234 IEEE80211_UNLOCK(ic); 235 } 236 237 static void 238 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan, 239 const struct ieee80211_channel *newchan) 240 { 241 if (newchan == NULL) 242 if_printf(ifp, "radar detected on channel %u (%u MHz)\n", 243 curchan->ic_ieee, curchan->ic_freq); 244 else 245 if_printf(ifp, "radar detected on channel %u (%u MHz), " 246 "moving to channel %u (%u MHz)\n", 247 curchan->ic_ieee, curchan->ic_freq, 248 newchan->ic_ieee, newchan->ic_freq); 249 } 250 251 /* 252 * Handle a radar detection event on a channel. The channel is 253 * added to the NOL list and we record the time of the event. 254 * Entries are aged out after NOL_TIMEOUT. If radar was 255 * detected while doing CAC we force a state/channel change. 256 * Otherwise radar triggers a channel switch using the CSA 257 * mechanism (when the channel is the bss channel). 258 */ 259 void 260 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 261 { 262 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 263 int i, now; 264 265 IEEE80211_LOCK_ASSERT(ic); 266 267 /* 268 * Mark all entries with this frequency. Notify user 269 * space and arrange for notification when the radar 270 * indication is cleared. Then kick the NOL processing 271 * thread if not already running. 272 */ 273 now = ticks; 274 for (i = 0; i < ic->ic_nchans; i++) { 275 struct ieee80211_channel *c = &ic->ic_channels[i]; 276 if (c->ic_freq == chan->ic_freq) { 277 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 278 c->ic_state |= IEEE80211_CHANSTATE_RADAR; 279 dfs->nol_event[i] = now; 280 } 281 } 282 ieee80211_notify_radar(ic, chan); 283 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR; 284 if (!callout_pending(&dfs->nol_timer)) 285 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, dfs_timeout, ic); 286 287 /* 288 * If radar is detected on the bss channel while 289 * doing CAC; force a state change by scheduling the 290 * callout to be dispatched asap. Otherwise, if this 291 * event is for the bss channel then we must quiet 292 * traffic and schedule a channel switch. 293 * 294 * Note this allows us to receive notification about 295 * channels other than the bss channel; not sure 296 * that can/will happen but it's simple to support. 297 */ 298 if (chan == ic->ic_bsschan) { 299 /* XXX need a way to defer to user app */ 300 dfs->newchan = ieee80211_dfs_pickchannel(ic); 301 302 announce_radar(ic->ic_ifp, chan, dfs->newchan); 303 304 if (callout_pending(&dfs->cac_timer)) 305 callout_reset(&dfs->nol_timer, 0, dfs_timeout, ic); 306 else if (dfs->newchan != NULL) { 307 /* XXX mode 1, switch count 2 */ 308 /* XXX calculate switch count based on max 309 switch time and beacon interval? */ 310 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 311 } else { 312 /* 313 * Spec says to stop all transmissions and 314 * wait on the current channel for an entry 315 * on the NOL to expire. 316 */ 317 /*XXX*/ 318 } 319 } else { 320 /* 321 * Issue rate-limited console msgs. 322 */ 323 if (dfs->lastchan != chan) { 324 dfs->lastchan = chan; 325 dfs->cureps = 0; 326 announce_radar(ic->ic_ifp, chan, NULL); 327 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 328 announce_radar(ic->ic_ifp, chan, NULL); 329 } 330 } 331 } 332 333 struct ieee80211_channel * 334 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 335 { 336 struct ieee80211_channel *c; 337 int i, flags; 338 uint16_t v; 339 340 /* 341 * Consult the scan cache first. 342 */ 343 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 344 /* 345 * XXX if curchan is HT this will never find a channel 346 * XXX 'cuz we scan only legacy channels 347 */ 348 c = ieee80211_scan_pickchannel(ic, flags); 349 if (c != NULL) 350 return c; 351 /* 352 * No channel found in scan cache; select a compatible 353 * one at random (skipping channels where radar has 354 * been detected). 355 */ 356 get_random_bytes(&v, sizeof(v)); 357 v %= ic->ic_nchans; 358 for (i = v; i < ic->ic_nchans; i++) { 359 c = &ic->ic_channels[i]; 360 if (!IEEE80211_IS_CHAN_RADAR(c) && 361 (c->ic_flags & flags) == flags) 362 return c; 363 } 364 for (i = 0; i < v; i++) { 365 c = &ic->ic_channels[i]; 366 if (!IEEE80211_IS_CHAN_RADAR(c) && 367 (c->ic_flags & flags) == flags) 368 return c; 369 } 370 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n"); 371 return NULL; 372 } 373