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 #include <sys/cdefs.h> 29 #ifdef __FreeBSD__ 30 #endif 31 32 /* 33 * IEEE 802.11 DFS/Radar support. 34 */ 35 #include "opt_inet.h" 36 #include "opt_wlan.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/mbuf.h> 41 #include <sys/malloc.h> 42 #include <sys/kernel.h> 43 44 #include <sys/socket.h> 45 #include <sys/sockio.h> 46 #include <sys/endian.h> 47 #include <sys/errno.h> 48 #include <sys/proc.h> 49 #include <sys/sysctl.h> 50 51 #include <net/if.h> 52 #include <net/if_var.h> 53 #include <net/if_media.h> 54 #include <net/ethernet.h> 55 56 #include <net80211/ieee80211_var.h> 57 58 static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state"); 59 60 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */ 61 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW, 62 &ieee80211_nol_timeout, 0, "NOL timeout (secs)"); 63 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000) 64 65 static int ieee80211_cac_timeout = 60; /* 60 seconds */ 66 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW, 67 &ieee80211_cac_timeout, 0, "CAC timeout (secs)"); 68 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000) 69 70 /* 71 DFS* In order to facilitate debugging, a couple of operating 72 * modes aside from the default are needed. 73 * 74 * 0 - default CAC/NOL behaviour - ie, start CAC, place 75 * channel on NOL list. 76 * 1 - send CAC, but don't change channel or add the channel 77 * to the NOL list. 78 * 2 - just match on radar, don't send CAC or place channel in 79 * the NOL list. 80 */ 81 static int ieee80211_dfs_debug = DFS_DBG_NONE; 82 83 /* 84 * This option must not be included in the default kernel 85 * as it allows users to plainly disable CAC/NOL handling. 86 */ 87 #ifdef IEEE80211_DFS_DEBUG 88 SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW, 89 &ieee80211_dfs_debug, 0, "DFS debug behaviour"); 90 #endif 91 92 static int 93 null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm) 94 { 95 return ENOSYS; 96 } 97 98 void 99 ieee80211_dfs_attach(struct ieee80211com *ic) 100 { 101 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 102 103 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0); 104 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0); 105 106 ic->ic_set_quiet = null_set_quiet; 107 } 108 109 void 110 ieee80211_dfs_detach(struct ieee80211com *ic) 111 { 112 /* NB: we assume no locking is needed */ 113 ieee80211_dfs_reset(ic); 114 } 115 116 void 117 ieee80211_dfs_reset(struct ieee80211com *ic) 118 { 119 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 120 int i; 121 122 /* NB: we assume no locking is needed */ 123 /* NB: cac_timer should be cleared by the state machine */ 124 callout_drain(&dfs->nol_timer); 125 for (i = 0; i < ic->ic_nchans; i++) 126 ic->ic_channels[i].ic_state = 0; 127 dfs->lastchan = NULL; 128 } 129 130 static void 131 cac_timeout(void *arg) 132 { 133 struct ieee80211vap *vap = arg; 134 struct ieee80211com *ic = vap->iv_ic; 135 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 136 int i; 137 138 IEEE80211_LOCK_ASSERT(ic); 139 140 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */ 141 return; 142 /* 143 * When radar is detected during a CAC we are woken 144 * up prematurely to switch to a new channel. 145 * Check the channel to decide how to act. 146 */ 147 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) { 148 ieee80211_notify_cac(ic, ic->ic_curchan, 149 IEEE80211_NOTIFY_CAC_RADAR); 150 151 if_printf(vap->iv_ifp, 152 "CAC timer on channel %u (%u MHz) stopped due to radar\n", 153 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 154 155 /* XXX clobbers any existing desired channel */ 156 /* NB: dfs->newchan may be NULL, that's ok */ 157 vap->iv_des_chan = dfs->newchan; 158 ieee80211_new_state_locked(vap, IEEE80211_S_SCAN, 0); 159 } else { 160 if_printf(vap->iv_ifp, 161 "CAC timer on channel %u (%u MHz) expired; " 162 "no radar detected\n", 163 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 164 /* 165 * Mark all channels with the current frequency 166 * as having completed CAC; this keeps us from 167 * doing it again until we change channels. 168 */ 169 for (i = 0; i < ic->ic_nchans; i++) { 170 struct ieee80211_channel *c = &ic->ic_channels[i]; 171 if (c->ic_freq == ic->ic_curchan->ic_freq) 172 c->ic_state |= IEEE80211_CHANSTATE_CACDONE; 173 } 174 ieee80211_notify_cac(ic, ic->ic_curchan, 175 IEEE80211_NOTIFY_CAC_EXPIRE); 176 ieee80211_cac_completeswitch(vap); 177 } 178 } 179 180 /* 181 * Initiate the CAC timer. The driver is responsible 182 * for setting up the hardware to scan for radar on the 183 * channnel, we just handle timing things out. 184 */ 185 void 186 ieee80211_dfs_cac_start(struct ieee80211vap *vap) 187 { 188 struct ieee80211com *ic = vap->iv_ic; 189 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 190 191 IEEE80211_LOCK_ASSERT(ic); 192 193 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap); 194 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n", 195 ticks_to_secs(CAC_TIMEOUT), 196 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 197 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START); 198 } 199 200 /* 201 * Clear the CAC timer. 202 */ 203 void 204 ieee80211_dfs_cac_stop(struct ieee80211vap *vap) 205 { 206 struct ieee80211com *ic = vap->iv_ic; 207 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 208 209 IEEE80211_LOCK_ASSERT(ic); 210 211 /* NB: racey but not important */ 212 if (callout_pending(&dfs->cac_timer)) { 213 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n", 214 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 215 ieee80211_notify_cac(ic, ic->ic_curchan, 216 IEEE80211_NOTIFY_CAC_STOP); 217 } 218 callout_stop(&dfs->cac_timer); 219 } 220 221 void 222 ieee80211_dfs_cac_clear(struct ieee80211com *ic, 223 const struct ieee80211_channel *chan) 224 { 225 int i; 226 227 for (i = 0; i < ic->ic_nchans; i++) { 228 struct ieee80211_channel *c = &ic->ic_channels[i]; 229 if (c->ic_freq == chan->ic_freq) 230 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 231 } 232 } 233 234 static void 235 dfs_timeout(void *arg) 236 { 237 struct ieee80211com *ic = arg; 238 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 239 struct ieee80211_channel *c; 240 int i, oldest, now; 241 242 IEEE80211_LOCK_ASSERT(ic); 243 244 now = oldest = ticks; 245 for (i = 0; i < ic->ic_nchans; i++) { 246 c = &ic->ic_channels[i]; 247 if (IEEE80211_IS_CHAN_RADAR(c)) { 248 if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) { 249 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR; 250 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) { 251 /* 252 * NB: do this here so we get only one 253 * msg instead of one for every channel 254 * table entry. 255 */ 256 ic_printf(ic, "radar on channel %u " 257 "(%u MHz) cleared after timeout\n", 258 c->ic_ieee, c->ic_freq); 259 /* notify user space */ 260 c->ic_state &= 261 ~IEEE80211_CHANSTATE_NORADAR; 262 ieee80211_notify_radar(ic, c); 263 } 264 } else if (dfs->nol_event[i] < oldest) 265 oldest = dfs->nol_event[i]; 266 } 267 } 268 if (oldest != now) { 269 /* arrange to process next channel up for a status change */ 270 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now); 271 } 272 } 273 274 static void 275 announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan, 276 const struct ieee80211_channel *newchan) 277 { 278 if (newchan == NULL) 279 ic_printf(ic, "radar detected on channel %u (%u MHz)\n", 280 curchan->ic_ieee, curchan->ic_freq); 281 else 282 ic_printf(ic, "radar detected on channel %u (%u MHz), " 283 "moving to channel %u (%u MHz)\n", 284 curchan->ic_ieee, curchan->ic_freq, 285 newchan->ic_ieee, newchan->ic_freq); 286 } 287 288 /* 289 * Handle a radar detection event on a channel. The channel is 290 * added to the NOL list and we record the time of the event. 291 * Entries are aged out after NOL_TIMEOUT. If radar was 292 * detected while doing CAC we force a state/channel change. 293 * Otherwise radar triggers a channel switch using the CSA 294 * mechanism (when the channel is the bss channel). 295 */ 296 void 297 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 298 { 299 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 300 int i, now; 301 302 IEEE80211_LOCK_ASSERT(ic); 303 304 /* 305 * If doing DFS debugging (mode 2), don't bother 306 * running the rest of this function. 307 * 308 * Simply announce the presence of the radar and continue 309 * along merrily. 310 */ 311 if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) { 312 announce_radar(ic, chan, chan); 313 ieee80211_notify_radar(ic, chan); 314 return; 315 } 316 317 /* 318 * Don't mark the channel and don't put it into NOL 319 * if we're doing DFS debugging. 320 */ 321 if (ieee80211_dfs_debug == DFS_DBG_NONE) { 322 /* 323 * Mark all entries with this frequency. Notify user 324 * space and arrange for notification when the radar 325 * indication is cleared. Then kick the NOL processing 326 * thread if not already running. 327 */ 328 now = ticks; 329 for (i = 0; i < ic->ic_nchans; i++) { 330 struct ieee80211_channel *c = &ic->ic_channels[i]; 331 if (c->ic_freq == chan->ic_freq) { 332 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 333 c->ic_state |= IEEE80211_CHANSTATE_RADAR; 334 dfs->nol_event[i] = now; 335 } 336 } 337 ieee80211_notify_radar(ic, chan); 338 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR; 339 if (!callout_pending(&dfs->nol_timer)) 340 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, 341 dfs_timeout, ic); 342 } 343 344 /* 345 * If radar is detected on the bss channel while 346 * doing CAC; force a state change by scheduling the 347 * callout to be dispatched asap. Otherwise, if this 348 * event is for the bss channel then we must quiet 349 * traffic and schedule a channel switch. 350 * 351 * Note this allows us to receive notification about 352 * channels other than the bss channel; not sure 353 * that can/will happen but it's simple to support. 354 */ 355 if (chan == ic->ic_bsschan) { 356 /* XXX need a way to defer to user app */ 357 358 /* 359 * Don't flip over to a new channel if 360 * we are currently doing DFS debugging. 361 */ 362 if (ieee80211_dfs_debug == DFS_DBG_NONE) 363 dfs->newchan = ieee80211_dfs_pickchannel(ic); 364 else 365 dfs->newchan = chan; 366 367 announce_radar(ic, chan, dfs->newchan); 368 369 if (callout_pending(&dfs->cac_timer)) 370 callout_schedule(&dfs->cac_timer, 0); 371 else if (dfs->newchan != NULL) { 372 /* XXX mode 1, switch count 2 */ 373 /* XXX calculate switch count based on max 374 switch time and beacon interval? */ 375 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 376 } else { 377 /* 378 * Spec says to stop all transmissions and 379 * wait on the current channel for an entry 380 * on the NOL to expire. 381 */ 382 /*XXX*/ 383 ic_printf(ic, "%s: No free channels; waiting for entry " 384 "on NOL to expire\n", __func__); 385 } 386 } else { 387 /* 388 * Issue rate-limited console msgs. 389 */ 390 if (dfs->lastchan != chan) { 391 dfs->lastchan = chan; 392 dfs->cureps = 0; 393 announce_radar(ic, chan, NULL); 394 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 395 announce_radar(ic, chan, NULL); 396 } 397 } 398 } 399 400 struct ieee80211_channel * 401 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 402 { 403 struct ieee80211_channel *c; 404 int i, flags; 405 uint16_t v; 406 407 /* 408 * Consult the scan cache first. 409 */ 410 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 411 /* 412 * XXX if curchan is HT this will never find a channel 413 * XXX 'cuz we scan only legacy channels 414 */ 415 c = ieee80211_scan_pickchannel(ic, flags); 416 if (c != NULL) 417 return c; 418 /* 419 * No channel found in scan cache; select a compatible 420 * one at random (skipping channels where radar has 421 * been detected). 422 */ 423 net80211_get_random_bytes(&v, sizeof(v)); 424 v %= ic->ic_nchans; 425 for (i = v; i < ic->ic_nchans; i++) { 426 c = &ic->ic_channels[i]; 427 if (!IEEE80211_IS_CHAN_RADAR(c) && 428 (c->ic_flags & flags) == flags) 429 return c; 430 } 431 for (i = 0; i < v; i++) { 432 c = &ic->ic_channels[i]; 433 if (!IEEE80211_IS_CHAN_RADAR(c) && 434 (c->ic_flags & flags) == flags) 435 return c; 436 } 437 ic_printf(ic, "HELP, no channel located to switch to!\n"); 438 return NULL; 439 } 440