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_var.h> 52 #include <net/if_media.h> 53 #include <net/ethernet.h> 54 55 #include <netproto/802_11/ieee80211_var.h> 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 /* 68 DFS* In order to facilitate debugging, a couple of operating 69 * modes aside from the default are needed. 70 * 71 * 0 - default CAC/NOL behaviour - ie, start CAC, place 72 * channel on NOL list. 73 * 1 - send CAC, but don't change channel or add the channel 74 * to the NOL list. 75 * 2 - just match on radar, don't send CAC or place channel in 76 * the NOL list. 77 */ 78 static int ieee80211_dfs_debug = DFS_DBG_NONE; 79 80 /* 81 * This option must not be included in the default kernel 82 * as it allows users to plainly disable CAC/NOL handling. 83 */ 84 #ifdef IEEE80211_DFS_DEBUG 85 SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW, 86 &ieee80211_dfs_debug, 0, "DFS debug behaviour"); 87 #endif 88 89 static int 90 null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm) 91 { 92 return ENOSYS; 93 } 94 95 void 96 ieee80211_dfs_attach(struct ieee80211com *ic) 97 { 98 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 99 100 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0); 101 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0); 102 103 ic->ic_set_quiet = null_set_quiet; 104 } 105 106 void 107 ieee80211_dfs_detach(struct ieee80211com *ic) 108 { 109 /* NB: we assume no locking is needed */ 110 ieee80211_dfs_reset(ic); 111 } 112 113 void 114 ieee80211_dfs_reset(struct ieee80211com *ic) 115 { 116 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 117 int i; 118 119 /* NB: we assume no locking is needed */ 120 /* NB: cac_timer should be cleared by the state machine */ 121 callout_drain(&dfs->nol_timer); 122 for (i = 0; i < ic->ic_nchans; i++) 123 ic->ic_channels[i].ic_state = 0; 124 dfs->lastchan = NULL; 125 } 126 127 static void 128 cac_timeout(void *arg) 129 { 130 struct ieee80211vap *vap = arg; 131 struct ieee80211com *ic = vap->iv_ic; 132 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 133 int i; 134 135 IEEE80211_LOCK_ASSERT(ic); 136 137 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */ 138 return; 139 /* 140 * When radar is detected during a CAC we are woken 141 * up prematurely to switch to a new channel. 142 * Check the channel to decide how to act. 143 */ 144 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) { 145 ieee80211_notify_cac(ic, ic->ic_curchan, 146 IEEE80211_NOTIFY_CAC_RADAR); 147 148 if_printf(vap->iv_ifp, 149 "CAC timer on channel %u (%u MHz) stopped due to radar\n", 150 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 151 152 /* XXX clobbers any existing desired channel */ 153 /* NB: dfs->newchan may be NULL, that's ok */ 154 vap->iv_des_chan = dfs->newchan; 155 /* XXX recursive lock need ieee80211_new_state_locked */ 156 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0); 157 } else { 158 if_printf(vap->iv_ifp, 159 "CAC timer on channel %u (%u MHz) expired; " 160 "no radar detected\n", 161 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 162 /* 163 * Mark all channels with the current frequency 164 * as having completed CAC; this keeps us from 165 * doing it again until we change channels. 166 */ 167 for (i = 0; i < ic->ic_nchans; i++) { 168 struct ieee80211_channel *c = &ic->ic_channels[i]; 169 if (c->ic_freq == ic->ic_curchan->ic_freq) 170 c->ic_state |= IEEE80211_CHANSTATE_CACDONE; 171 } 172 ieee80211_notify_cac(ic, ic->ic_curchan, 173 IEEE80211_NOTIFY_CAC_EXPIRE); 174 ieee80211_cac_completeswitch(vap); 175 } 176 } 177 178 /* 179 * Initiate the CAC timer. The driver is responsible 180 * for setting up the hardware to scan for radar on the 181 * channnel, we just handle timing things out. 182 */ 183 void 184 ieee80211_dfs_cac_start(struct ieee80211vap *vap) 185 { 186 struct ieee80211com *ic = vap->iv_ic; 187 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 188 189 IEEE80211_LOCK_ASSERT(ic); 190 191 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap); 192 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n", 193 ticks_to_secs(CAC_TIMEOUT), 194 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 195 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START); 196 } 197 198 /* 199 * Clear the CAC timer. 200 */ 201 void 202 ieee80211_dfs_cac_stop(struct ieee80211vap *vap) 203 { 204 struct ieee80211com *ic = vap->iv_ic; 205 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 206 207 IEEE80211_LOCK_ASSERT(ic); 208 209 /* NB: racey but not important */ 210 if (callout_pending(&dfs->cac_timer)) { 211 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n", 212 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 213 ieee80211_notify_cac(ic, ic->ic_curchan, 214 IEEE80211_NOTIFY_CAC_STOP); 215 } 216 callout_stop(&dfs->cac_timer); 217 } 218 219 void 220 ieee80211_dfs_cac_clear(struct ieee80211com *ic, 221 const struct ieee80211_channel *chan) 222 { 223 int i; 224 225 for (i = 0; i < ic->ic_nchans; i++) { 226 struct ieee80211_channel *c = &ic->ic_channels[i]; 227 if (c->ic_freq == chan->ic_freq) 228 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 229 } 230 } 231 232 static void 233 dfs_timeout(void *arg) 234 { 235 struct ieee80211com *ic = arg; 236 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 237 struct ieee80211_channel *c; 238 int i, oldest, now; 239 240 IEEE80211_LOCK_ASSERT(ic); 241 242 now = oldest = ticks; 243 for (i = 0; i < ic->ic_nchans; i++) { 244 c = &ic->ic_channels[i]; 245 if (IEEE80211_IS_CHAN_RADAR(c)) { 246 if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) { 247 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR; 248 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) { 249 /* 250 * NB: do this here so we get only one 251 * msg instead of one for every channel 252 * table entry. 253 */ 254 ic_printf(ic, "radar on channel %u " 255 "(%u MHz) cleared after timeout\n", 256 c->ic_ieee, c->ic_freq); 257 /* notify user space */ 258 c->ic_state &= 259 ~IEEE80211_CHANSTATE_NORADAR; 260 ieee80211_notify_radar(ic, c); 261 } 262 } else if (dfs->nol_event[i] < oldest) 263 oldest = dfs->nol_event[i]; 264 } 265 } 266 if (oldest != now) { 267 /* arrange to process next channel up for a status change */ 268 #if defined(__DragonFly__) 269 callout_schedule_dfly(&dfs->nol_timer, oldest + NOL_TIMEOUT - now, 270 dfs_timeout, ic); 271 #else 272 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now); 273 #endif 274 } 275 } 276 277 static void 278 announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan, 279 const struct ieee80211_channel *newchan) 280 { 281 if (newchan == NULL) 282 ic_printf(ic, "radar detected on channel %u (%u MHz)\n", 283 curchan->ic_ieee, curchan->ic_freq); 284 else 285 ic_printf(ic, "radar detected on channel %u (%u MHz), " 286 "moving to channel %u (%u MHz)\n", 287 curchan->ic_ieee, curchan->ic_freq, 288 newchan->ic_ieee, newchan->ic_freq); 289 } 290 291 /* 292 * Handle a radar detection event on a channel. The channel is 293 * added to the NOL list and we record the time of the event. 294 * Entries are aged out after NOL_TIMEOUT. If radar was 295 * detected while doing CAC we force a state/channel change. 296 * Otherwise radar triggers a channel switch using the CSA 297 * mechanism (when the channel is the bss channel). 298 */ 299 void 300 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 301 { 302 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 303 int i, now; 304 305 IEEE80211_LOCK_ASSERT(ic); 306 307 /* 308 * If doing DFS debugging (mode 2), don't bother 309 * running the rest of this function. 310 * 311 * Simply announce the presence of the radar and continue 312 * along merrily. 313 */ 314 if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) { 315 announce_radar(ic, chan, chan); 316 ieee80211_notify_radar(ic, chan); 317 return; 318 } 319 320 /* 321 * Don't mark the channel and don't put it into NOL 322 * if we're doing DFS debugging. 323 */ 324 if (ieee80211_dfs_debug == DFS_DBG_NONE) { 325 /* 326 * Mark all entries with this frequency. Notify user 327 * space and arrange for notification when the radar 328 * indication is cleared. Then kick the NOL processing 329 * thread if not already running. 330 */ 331 now = ticks; 332 for (i = 0; i < ic->ic_nchans; i++) { 333 struct ieee80211_channel *c = &ic->ic_channels[i]; 334 if (c->ic_freq == chan->ic_freq) { 335 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 336 c->ic_state |= IEEE80211_CHANSTATE_RADAR; 337 dfs->nol_event[i] = now; 338 } 339 } 340 ieee80211_notify_radar(ic, chan); 341 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR; 342 if (!callout_pending(&dfs->nol_timer)) 343 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, 344 dfs_timeout, ic); 345 } 346 347 /* 348 * If radar is detected on the bss channel while 349 * doing CAC; force a state change by scheduling the 350 * callout to be dispatched asap. Otherwise, if this 351 * event is for the bss channel then we must quiet 352 * traffic and schedule a channel switch. 353 * 354 * Note this allows us to receive notification about 355 * channels other than the bss channel; not sure 356 * that can/will happen but it's simple to support. 357 */ 358 if (chan == ic->ic_bsschan) { 359 /* XXX need a way to defer to user app */ 360 361 /* 362 * Don't flip over to a new channel if 363 * we are currently doing DFS debugging. 364 */ 365 if (ieee80211_dfs_debug == DFS_DBG_NONE) 366 dfs->newchan = ieee80211_dfs_pickchannel(ic); 367 else 368 dfs->newchan = chan; 369 370 announce_radar(ic, chan, dfs->newchan); 371 372 if (callout_pending(&dfs->cac_timer)) 373 #if defined(__DragonFly__) 374 callout_schedule_dfly(&dfs->cac_timer, 0, 375 cac_timeout, 376 callout_arg(&dfs->cac_timer)); 377 #else 378 callout_schedule(&dfs->cac_timer, 0); 379 #endif 380 else if (dfs->newchan != NULL) { 381 /* XXX mode 1, switch count 2 */ 382 /* XXX calculate switch count based on max 383 switch time and beacon interval? */ 384 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 385 } else { 386 /* 387 * Spec says to stop all transmissions and 388 * wait on the current channel for an entry 389 * on the NOL to expire. 390 */ 391 /*XXX*/ 392 ic_printf(ic, "%s: No free channels; waiting for entry " 393 "on NOL to expire\n", __func__); 394 } 395 } else { 396 /* 397 * Issue rate-limited console msgs. 398 */ 399 if (dfs->lastchan != chan) { 400 dfs->lastchan = chan; 401 dfs->cureps = 0; 402 announce_radar(ic, chan, NULL); 403 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 404 announce_radar(ic, chan, NULL); 405 } 406 } 407 } 408 409 struct ieee80211_channel * 410 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 411 { 412 struct ieee80211_channel *c; 413 int i, flags; 414 uint16_t v; 415 416 /* 417 * Consult the scan cache first. 418 */ 419 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 420 /* 421 * XXX if curchan is HT this will never find a channel 422 * XXX 'cuz we scan only legacy channels 423 */ 424 c = ieee80211_scan_pickchannel(ic, flags); 425 if (c != NULL) 426 return c; 427 /* 428 * No channel found in scan cache; select a compatible 429 * one at random (skipping channels where radar has 430 * been detected). 431 */ 432 get_random_bytes(&v, sizeof(v)); 433 v %= ic->ic_nchans; 434 for (i = v; i < ic->ic_nchans; i++) { 435 c = &ic->ic_channels[i]; 436 if (!IEEE80211_IS_CHAN_RADAR(c) && 437 (c->ic_flags & flags) == flags) 438 return c; 439 } 440 for (i = 0; i < v; i++) { 441 c = &ic->ic_channels[i]; 442 if (!IEEE80211_IS_CHAN_RADAR(c) && 443 (c->ic_flags & flags) == flags) 444 return c; 445 } 446 ic_printf(ic, "HELP, no channel located to switch to!\n"); 447 return NULL; 448 } 449