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 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) 61 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) 66 67 void 68 ieee80211_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 76 void 77 ieee80211_dfs_detach(struct ieee80211com *ic) 78 { 79 /* NB: we assume no locking is needed */ 80 ieee80211_dfs_reset(ic); 81 } 82 83 void 84 ieee80211_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 97 static void 98 cac_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 */ 153 void 154 ieee80211_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 */ 171 void 172 ieee80211_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 } 188 189 void 190 ieee80211_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 } 201 202 static void 203 dfs_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 } 241 242 static void 243 announce_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 */ 264 void 265 ieee80211_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 } 324 } else { 325 /* 326 * Issue rate-limited console msgs. 327 */ 328 if (dfs->lastchan != chan) { 329 dfs->lastchan = chan; 330 dfs->cureps = 0; 331 announce_radar(ic->ic_ifp, chan, NULL); 332 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 333 announce_radar(ic->ic_ifp, chan, NULL); 334 } 335 } 336 } 337 338 struct ieee80211_channel * 339 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 340 { 341 struct ieee80211_channel *c; 342 int i, flags; 343 uint16_t v; 344 345 /* 346 * Consult the scan cache first. 347 */ 348 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 349 /* 350 * XXX if curchan is HT this will never find a channel 351 * XXX 'cuz we scan only legacy channels 352 */ 353 c = ieee80211_scan_pickchannel(ic, flags); 354 if (c != NULL) 355 return c; 356 /* 357 * No channel found in scan cache; select a compatible 358 * one at random (skipping channels where radar has 359 * been detected). 360 */ 361 get_random_bytes(&v, sizeof(v)); 362 v %= ic->ic_nchans; 363 for (i = v; i < ic->ic_nchans; i++) { 364 c = &ic->ic_channels[i]; 365 if (!IEEE80211_IS_CHAN_RADAR(c) && 366 (c->ic_flags & flags) == flags) 367 return c; 368 } 369 for (i = 0; i < v; i++) { 370 c = &ic->ic_channels[i]; 371 if (!IEEE80211_IS_CHAN_RADAR(c) && 372 (c->ic_flags & flags) == flags) 373 return c; 374 } 375 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n"); 376 return NULL; 377 } 378