1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2007-2008 Sam Leffler, Errno Consulting 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 /* 29 * IEEE 802.11 DFS/Radar support. 30 */ 31 #include "opt_inet.h" 32 #include "opt_wlan.h" 33 34 #include <sys/param.h> 35 #include <sys/systm.h> 36 #include <sys/mbuf.h> 37 #include <sys/malloc.h> 38 #include <sys/kernel.h> 39 40 #include <sys/socket.h> 41 #include <sys/sockio.h> 42 #include <sys/endian.h> 43 #include <sys/errno.h> 44 #include <sys/proc.h> 45 #include <sys/sysctl.h> 46 47 #include <net/if.h> 48 #include <net/if_var.h> 49 #include <net/if_media.h> 50 #include <net/ethernet.h> 51 52 #include <net80211/ieee80211_var.h> 53 54 static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state"); 55 56 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */ 57 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW, 58 &ieee80211_nol_timeout, 0, "NOL timeout (secs)"); 59 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000) 60 61 static int ieee80211_cac_timeout = 60; /* 60 seconds */ 62 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW, 63 &ieee80211_cac_timeout, 0, "CAC timeout (secs)"); 64 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000) 65 66 /* 67 DFS* In order to facilitate debugging, a couple of operating 68 * modes aside from the default are needed. 69 * 70 * 0 - default CAC/NOL behaviour - ie, start CAC, place 71 * channel on NOL list. 72 * 1 - send CAC, but don't change channel or add the channel 73 * to the NOL list. 74 * 2 - just match on radar, don't send CAC or place channel in 75 * the NOL list. 76 */ 77 static int ieee80211_dfs_debug = DFS_DBG_NONE; 78 79 /* 80 * This option must not be included in the default kernel 81 * as it allows users to plainly disable CAC/NOL handling. 82 */ 83 #ifdef IEEE80211_DFS_DEBUG 84 SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW, 85 &ieee80211_dfs_debug, 0, "DFS debug behaviour"); 86 #endif 87 88 static int 89 null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm) 90 { 91 return ENOSYS; 92 } 93 94 void 95 ieee80211_dfs_attach(struct ieee80211com *ic) 96 { 97 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 98 99 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0); 100 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0); 101 102 ic->ic_set_quiet = null_set_quiet; 103 } 104 105 void 106 ieee80211_dfs_detach(struct ieee80211com *ic) 107 { 108 /* NB: we assume no locking is needed */ 109 ieee80211_dfs_reset(ic); 110 } 111 112 void 113 ieee80211_dfs_reset(struct ieee80211com *ic) 114 { 115 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 116 int i; 117 118 /* NB: we assume no locking is needed */ 119 /* NB: cac_timer should be cleared by the state machine */ 120 callout_drain(&dfs->nol_timer); 121 for (i = 0; i < ic->ic_nchans; i++) 122 ic->ic_channels[i].ic_state = 0; 123 dfs->lastchan = NULL; 124 } 125 126 static void 127 cac_timeout(void *arg) 128 { 129 struct ieee80211vap *vap = arg; 130 struct ieee80211com *ic = vap->iv_ic; 131 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 132 int i; 133 134 IEEE80211_LOCK_ASSERT(ic); 135 136 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */ 137 return; 138 /* 139 * When radar is detected during a CAC we are woken 140 * up prematurely to switch to a new channel. 141 * Check the channel to decide how to act. 142 */ 143 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) { 144 ieee80211_notify_cac(ic, ic->ic_curchan, 145 IEEE80211_NOTIFY_CAC_RADAR); 146 147 net80211_vap_printf(vap, 148 "CAC timer on channel %u (%u MHz) stopped due to radar\n", 149 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 150 151 /* XXX clobbers any existing desired channel */ 152 /* NB: dfs->newchan may be NULL, that's ok */ 153 vap->iv_des_chan = dfs->newchan; 154 ieee80211_new_state_locked(vap, IEEE80211_S_SCAN, 0); 155 } else { 156 net80211_vap_printf(vap, 157 "CAC timer on channel %u (%u MHz) expired; " 158 "no radar detected\n", 159 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 160 /* 161 * Mark all channels with the current frequency 162 * as having completed CAC; this keeps us from 163 * doing it again until we change channels. 164 */ 165 for (i = 0; i < ic->ic_nchans; i++) { 166 struct ieee80211_channel *c = &ic->ic_channels[i]; 167 if (c->ic_freq == ic->ic_curchan->ic_freq) 168 c->ic_state |= IEEE80211_CHANSTATE_CACDONE; 169 } 170 ieee80211_notify_cac(ic, ic->ic_curchan, 171 IEEE80211_NOTIFY_CAC_EXPIRE); 172 ieee80211_cac_completeswitch(vap); 173 } 174 } 175 176 /* 177 * Initiate the CAC timer. The driver is responsible 178 * for setting up the hardware to scan for radar on the 179 * channnel, we just handle timing things out. 180 */ 181 void 182 ieee80211_dfs_cac_start(struct ieee80211vap *vap) 183 { 184 struct ieee80211com *ic = vap->iv_ic; 185 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 186 187 IEEE80211_LOCK_ASSERT(ic); 188 189 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap); 190 net80211_vap_printf(vap, 191 "start %d second CAC timer on channel %u (%u MHz)\n", 192 ticks_to_secs(CAC_TIMEOUT), 193 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 194 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START); 195 } 196 197 /* 198 * Clear the CAC timer. 199 */ 200 void 201 ieee80211_dfs_cac_stop(struct ieee80211vap *vap) 202 { 203 struct ieee80211com *ic = vap->iv_ic; 204 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 205 206 IEEE80211_LOCK_ASSERT(ic); 207 208 /* NB: racey but not important */ 209 if (callout_pending(&dfs->cac_timer)) { 210 net80211_vap_printf(vap, 211 "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 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now); 269 } 270 } 271 272 static void 273 announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan, 274 const struct ieee80211_channel *newchan) 275 { 276 if (newchan == NULL) 277 ic_printf(ic, "radar detected on channel %u (%u MHz)\n", 278 curchan->ic_ieee, curchan->ic_freq); 279 else 280 ic_printf(ic, "radar detected on channel %u (%u MHz), " 281 "moving to channel %u (%u MHz)\n", 282 curchan->ic_ieee, curchan->ic_freq, 283 newchan->ic_ieee, newchan->ic_freq); 284 } 285 286 /* 287 * Handle a radar detection event on a channel. The channel is 288 * added to the NOL list and we record the time of the event. 289 * Entries are aged out after NOL_TIMEOUT. If radar was 290 * detected while doing CAC we force a state/channel change. 291 * Otherwise radar triggers a channel switch using the CSA 292 * mechanism (when the channel is the bss channel). 293 */ 294 void 295 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 296 { 297 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 298 int i, now; 299 300 IEEE80211_LOCK_ASSERT(ic); 301 302 /* 303 * If doing DFS debugging (mode 2), don't bother 304 * running the rest of this function. 305 * 306 * Simply announce the presence of the radar and continue 307 * along merrily. 308 */ 309 if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) { 310 announce_radar(ic, chan, chan); 311 ieee80211_notify_radar(ic, chan); 312 return; 313 } 314 315 /* 316 * Don't mark the channel and don't put it into NOL 317 * if we're doing DFS debugging. 318 */ 319 if (ieee80211_dfs_debug == DFS_DBG_NONE) { 320 /* 321 * Mark all entries with this frequency. Notify user 322 * space and arrange for notification when the radar 323 * indication is cleared. Then kick the NOL processing 324 * thread if not already running. 325 */ 326 now = ticks; 327 for (i = 0; i < ic->ic_nchans; i++) { 328 struct ieee80211_channel *c = &ic->ic_channels[i]; 329 if (c->ic_freq == chan->ic_freq) { 330 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 331 c->ic_state |= IEEE80211_CHANSTATE_RADAR; 332 dfs->nol_event[i] = now; 333 } 334 } 335 ieee80211_notify_radar(ic, chan); 336 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR; 337 if (!callout_pending(&dfs->nol_timer)) 338 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, 339 dfs_timeout, ic); 340 } 341 342 /* 343 * If radar is detected on the bss channel while 344 * doing CAC; force a state change by scheduling the 345 * callout to be dispatched asap. Otherwise, if this 346 * event is for the bss channel then we must quiet 347 * traffic and schedule a channel switch. 348 * 349 * Note this allows us to receive notification about 350 * channels other than the bss channel; not sure 351 * that can/will happen but it's simple to support. 352 */ 353 if (chan == ic->ic_bsschan) { 354 /* XXX need a way to defer to user app */ 355 356 /* 357 * Don't flip over to a new channel if 358 * we are currently doing DFS debugging. 359 */ 360 if (ieee80211_dfs_debug == DFS_DBG_NONE) 361 dfs->newchan = ieee80211_dfs_pickchannel(ic); 362 else 363 dfs->newchan = chan; 364 365 announce_radar(ic, chan, dfs->newchan); 366 367 if (callout_pending(&dfs->cac_timer)) 368 callout_schedule(&dfs->cac_timer, 0); 369 else if (dfs->newchan != NULL) { 370 /* XXX mode 1, switch count 2 */ 371 /* XXX calculate switch count based on max 372 switch time and beacon interval? */ 373 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 374 } else { 375 /* 376 * Spec says to stop all transmissions and 377 * wait on the current channel for an entry 378 * on the NOL to expire. 379 */ 380 /*XXX*/ 381 ic_printf(ic, "%s: No free channels; waiting for entry " 382 "on NOL to expire\n", __func__); 383 } 384 } else { 385 /* 386 * Issue rate-limited console msgs. 387 */ 388 if (dfs->lastchan != chan) { 389 dfs->lastchan = chan; 390 dfs->cureps = 0; 391 announce_radar(ic, chan, NULL); 392 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 393 announce_radar(ic, chan, NULL); 394 } 395 } 396 } 397 398 struct ieee80211_channel * 399 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 400 { 401 struct ieee80211_channel *c; 402 int i, flags; 403 uint16_t v; 404 405 /* 406 * Consult the scan cache first. 407 */ 408 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 409 /* 410 * XXX if curchan is HT this will never find a channel 411 * XXX 'cuz we scan only legacy channels 412 */ 413 c = ieee80211_scan_pickchannel(ic, flags); 414 if (c != NULL) 415 return c; 416 /* 417 * No channel found in scan cache; select a compatible 418 * one at random (skipping channels where radar has 419 * been detected). 420 */ 421 net80211_get_random_bytes(&v, sizeof(v)); 422 v %= ic->ic_nchans; 423 for (i = v; i < ic->ic_nchans; i++) { 424 c = &ic->ic_channels[i]; 425 if (!IEEE80211_IS_CHAN_RADAR(c) && 426 (c->ic_flags & flags) == flags) 427 return c; 428 } 429 for (i = 0; i < v; i++) { 430 c = &ic->ic_channels[i]; 431 if (!IEEE80211_IS_CHAN_RADAR(c) && 432 (c->ic_flags & flags) == flags) 433 return c; 434 } 435 ic_printf(ic, "HELP, no channel located to switch to!\n"); 436 return NULL; 437 } 438