Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/net80211/ieee80211_dfs.c
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1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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 __FBSDID("$FreeBSD: releng/12.0/sys/net80211/ieee80211_dfs.c 326272 2017-11-27 15:23:17Z pfg $"); 31 #endif 32 33 /* 34 * IEEE 802.11 DFS/Radar support. 35 */ 36 #include "opt_inet.h" 37 #include "opt_wlan.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/mbuf.h> 42 #include <sys/malloc.h> 43 #include <sys/kernel.h> 44 45 #include <sys/socket.h> 46 #include <sys/sockio.h> 47 #include <sys/endian.h> 48 #include <sys/errno.h> 49 #include <sys/proc.h> 50 #include <sys/sysctl.h> 51 52 #include <net/if.h> 53 #include <net/if_var.h> 54 #include <net/if_media.h> 55 #include <net/ethernet.h> 56 57 #include <net80211/ieee80211_var.h> 58 59 static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state"); 60 61 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */ 62 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW, 63 &ieee80211_nol_timeout, 0, "NOL timeout (secs)"); 64 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000) 65 66 static int ieee80211_cac_timeout = 60; /* 60 seconds */ 67 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW, 68 &ieee80211_cac_timeout, 0, "CAC timeout (secs)"); 69 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000) 70 71 /* 72 DFS* In order to facilitate debugging, a couple of operating 73 * modes aside from the default are needed. 74 * 75 * 0 - default CAC/NOL behaviour - ie, start CAC, place 76 * channel on NOL list. 77 * 1 - send CAC, but don't change channel or add the channel 78 * to the NOL list. 79 * 2 - just match on radar, don't send CAC or place channel in 80 * the NOL list. 81 */ 82 static int ieee80211_dfs_debug = DFS_DBG_NONE; 83 84 /* 85 * This option must not be included in the default kernel 86 * as it allows users to plainly disable CAC/NOL handling. 87 */ 88 #ifdef IEEE80211_DFS_DEBUG 89 SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW, 90 &ieee80211_dfs_debug, 0, "DFS debug behaviour"); 91 #endif 92 93 static int 94 null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm) 95 { 96 return ENOSYS; 97 } 98 99 void 100 ieee80211_dfs_attach(struct ieee80211com *ic) 101 { 102 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 103 104 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0); 105 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0); 106 107 ic->ic_set_quiet = null_set_quiet; 108 } 109 110 void 111 ieee80211_dfs_detach(struct ieee80211com *ic) 112 { 113 /* NB: we assume no locking is needed */ 114 ieee80211_dfs_reset(ic); 115 } 116 117 void 118 ieee80211_dfs_reset(struct ieee80211com *ic) 119 { 120 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 121 int i; 122 123 /* NB: we assume no locking is needed */ 124 /* NB: cac_timer should be cleared by the state machine */ 125 callout_drain(&dfs->nol_timer); 126 for (i = 0; i < ic->ic_nchans; i++) 127 ic->ic_channels[i].ic_state = 0; 128 dfs->lastchan = NULL; 129 } 130 131 static void 132 cac_timeout(void *arg) 133 { 134 struct ieee80211vap *vap = arg; 135 struct ieee80211com *ic = vap->iv_ic; 136 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 137 int i; 138 139 IEEE80211_LOCK_ASSERT(ic); 140 141 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */ 142 return; 143 /* 144 * When radar is detected during a CAC we are woken 145 * up prematurely to switch to a new channel. 146 * Check the channel to decide how to act. 147 */ 148 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) { 149 ieee80211_notify_cac(ic, ic->ic_curchan, 150 IEEE80211_NOTIFY_CAC_RADAR); 151 152 if_printf(vap->iv_ifp, 153 "CAC timer on channel %u (%u MHz) stopped due to radar\n", 154 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 155 156 /* XXX clobbers any existing desired channel */ 157 /* NB: dfs->newchan may be NULL, that's ok */ 158 vap->iv_des_chan = dfs->newchan; 159 /* XXX recursive lock need ieee80211_new_state_locked */ 160 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0); 161 } else { 162 if_printf(vap->iv_ifp, 163 "CAC timer on channel %u (%u MHz) expired; " 164 "no radar detected\n", 165 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 166 /* 167 * Mark all channels with the current frequency 168 * as having completed CAC; this keeps us from 169 * doing it again until we change channels. 170 */ 171 for (i = 0; i < ic->ic_nchans; i++) { 172 struct ieee80211_channel *c = &ic->ic_channels[i]; 173 if (c->ic_freq == ic->ic_curchan->ic_freq) 174 c->ic_state |= IEEE80211_CHANSTATE_CACDONE; 175 } 176 ieee80211_notify_cac(ic, ic->ic_curchan, 177 IEEE80211_NOTIFY_CAC_EXPIRE); 178 ieee80211_cac_completeswitch(vap); 179 } 180 } 181 182 /* 183 * Initiate the CAC timer. The driver is responsible 184 * for setting up the hardware to scan for radar on the 185 * channnel, we just handle timing things out. 186 */ 187 void 188 ieee80211_dfs_cac_start(struct ieee80211vap *vap) 189 { 190 struct ieee80211com *ic = vap->iv_ic; 191 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 192 193 IEEE80211_LOCK_ASSERT(ic); 194 195 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap); 196 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n", 197 ticks_to_secs(CAC_TIMEOUT), 198 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 199 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START); 200 } 201 202 /* 203 * Clear the CAC timer. 204 */ 205 void 206 ieee80211_dfs_cac_stop(struct ieee80211vap *vap) 207 { 208 struct ieee80211com *ic = vap->iv_ic; 209 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 210 211 IEEE80211_LOCK_ASSERT(ic); 212 213 /* NB: racey but not important */ 214 if (callout_pending(&dfs->cac_timer)) { 215 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n", 216 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 217 ieee80211_notify_cac(ic, ic->ic_curchan, 218 IEEE80211_NOTIFY_CAC_STOP); 219 } 220 callout_stop(&dfs->cac_timer); 221 } 222 223 void 224 ieee80211_dfs_cac_clear(struct ieee80211com *ic, 225 const struct ieee80211_channel *chan) 226 { 227 int i; 228 229 for (i = 0; i < ic->ic_nchans; i++) { 230 struct ieee80211_channel *c = &ic->ic_channels[i]; 231 if (c->ic_freq == chan->ic_freq) 232 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 233 } 234 } 235 236 static void 237 dfs_timeout(void *arg) 238 { 239 struct ieee80211com *ic = arg; 240 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 241 struct ieee80211_channel *c; 242 int i, oldest, now; 243 244 IEEE80211_LOCK_ASSERT(ic); 245 246 now = oldest = ticks; 247 for (i = 0; i < ic->ic_nchans; i++) { 248 c = &ic->ic_channels[i]; 249 if (IEEE80211_IS_CHAN_RADAR(c)) { 250 if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) { 251 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR; 252 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) { 253 /* 254 * NB: do this here so we get only one 255 * msg instead of one for every channel 256 * table entry. 257 */ 258 ic_printf(ic, "radar on channel %u " 259 "(%u MHz) cleared after timeout\n", 260 c->ic_ieee, c->ic_freq); 261 /* notify user space */ 262 c->ic_state &= 263 ~IEEE80211_CHANSTATE_NORADAR; 264 ieee80211_notify_radar(ic, c); 265 } 266 } else if (dfs->nol_event[i] < oldest) 267 oldest = dfs->nol_event[i]; 268 } 269 } 270 if (oldest != now) { 271 /* arrange to process next channel up for a status change */ 272 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now); 273 } 274 } 275 276 static void 277 announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan, 278 const struct ieee80211_channel *newchan) 279 { 280 if (newchan == NULL) 281 ic_printf(ic, "radar detected on channel %u (%u MHz)\n", 282 curchan->ic_ieee, curchan->ic_freq); 283 else 284 ic_printf(ic, "radar detected on channel %u (%u MHz), " 285 "moving to channel %u (%u MHz)\n", 286 curchan->ic_ieee, curchan->ic_freq, 287 newchan->ic_ieee, newchan->ic_freq); 288 } 289 290 /* 291 * Handle a radar detection event on a channel. The channel is 292 * added to the NOL list and we record the time of the event. 293 * Entries are aged out after NOL_TIMEOUT. If radar was 294 * detected while doing CAC we force a state/channel change. 295 * Otherwise radar triggers a channel switch using the CSA 296 * mechanism (when the channel is the bss channel). 297 */ 298 void 299 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 300 { 301 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 302 int i, now; 303 304 IEEE80211_LOCK_ASSERT(ic); 305 306 /* 307 * If doing DFS debugging (mode 2), don't bother 308 * running the rest of this function. 309 * 310 * Simply announce the presence of the radar and continue 311 * along merrily. 312 */ 313 if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) { 314 announce_radar(ic, chan, chan); 315 ieee80211_notify_radar(ic, chan); 316 return; 317 } 318 319 /* 320 * Don't mark the channel and don't put it into NOL 321 * if we're doing DFS debugging. 322 */ 323 if (ieee80211_dfs_debug == DFS_DBG_NONE) { 324 /* 325 * Mark all entries with this frequency. Notify user 326 * space and arrange for notification when the radar 327 * indication is cleared. Then kick the NOL processing 328 * thread if not already running. 329 */ 330 now = ticks; 331 for (i = 0; i < ic->ic_nchans; i++) { 332 struct ieee80211_channel *c = &ic->ic_channels[i]; 333 if (c->ic_freq == chan->ic_freq) { 334 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 335 c->ic_state |= IEEE80211_CHANSTATE_RADAR; 336 dfs->nol_event[i] = now; 337 } 338 } 339 ieee80211_notify_radar(ic, chan); 340 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR; 341 if (!callout_pending(&dfs->nol_timer)) 342 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, 343 dfs_timeout, ic); 344 } 345 346 /* 347 * If radar is detected on the bss channel while 348 * doing CAC; force a state change by scheduling the 349 * callout to be dispatched asap. Otherwise, if this 350 * event is for the bss channel then we must quiet 351 * traffic and schedule a channel switch. 352 * 353 * Note this allows us to receive notification about 354 * channels other than the bss channel; not sure 355 * that can/will happen but it's simple to support. 356 */ 357 if (chan == ic->ic_bsschan) { 358 /* XXX need a way to defer to user app */ 359 360 /* 361 * Don't flip over to a new channel if 362 * we are currently doing DFS debugging. 363 */ 364 if (ieee80211_dfs_debug == DFS_DBG_NONE) 365 dfs->newchan = ieee80211_dfs_pickchannel(ic); 366 else 367 dfs->newchan = chan; 368 369 announce_radar(ic, chan, dfs->newchan); 370 371 if (callout_pending(&dfs->cac_timer)) 372 callout_schedule(&dfs->cac_timer, 0); 373 else if (dfs->newchan != NULL) { 374 /* XXX mode 1, switch count 2 */ 375 /* XXX calculate switch count based on max 376 switch time and beacon interval? */ 377 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 378 } else { 379 /* 380 * Spec says to stop all transmissions and 381 * wait on the current channel for an entry 382 * on the NOL to expire. 383 */ 384 /*XXX*/ 385 ic_printf(ic, "%s: No free channels; waiting for entry " 386 "on NOL to expire\n", __func__); 387 } 388 } else { 389 /* 390 * Issue rate-limited console msgs. 391 */ 392 if (dfs->lastchan != chan) { 393 dfs->lastchan = chan; 394 dfs->cureps = 0; 395 announce_radar(ic, chan, NULL); 396 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 397 announce_radar(ic, chan, NULL); 398 } 399 } 400 } 401 402 struct ieee80211_channel * 403 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 404 { 405 struct ieee80211_channel *c; 406 int i, flags; 407 uint16_t v; 408 409 /* 410 * Consult the scan cache first. 411 */ 412 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 413 /* 414 * XXX if curchan is HT this will never find a channel 415 * XXX 'cuz we scan only legacy channels 416 */ 417 c = ieee80211_scan_pickchannel(ic, flags); 418 if (c != NULL) 419 return c; 420 /* 421 * No channel found in scan cache; select a compatible 422 * one at random (skipping channels where radar has 423 * been detected). 424 */ 425 get_random_bytes(&v, sizeof(v)); 426 v %= ic->ic_nchans; 427 for (i = v; i < ic->ic_nchans; i++) { 428 c = &ic->ic_channels[i]; 429 if (!IEEE80211_IS_CHAN_RADAR(c) && 430 (c->ic_flags & flags) == flags) 431 return c; 432 } 433 for (i = 0; i < v; i++) { 434 c = &ic->ic_channels[i]; 435 if (!IEEE80211_IS_CHAN_RADAR(c) && 436 (c->ic_flags & flags) == flags) 437 return c; 438 } 439 ic_printf(ic, "HELP, no channel located to switch to!\n"); 440 return NULL; 441 }
Cache object: 802b07d581d5869e577b6cd5ccbbe1a5
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