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 * 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 <net80211/ieee80211_var.h> 56 57 static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state"); 58 59 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */ 60 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW, 61 &ieee80211_nol_timeout, 0, "NOL timeout (secs)"); 62 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000) 63 64 static int ieee80211_cac_timeout = 60; /* 60 seconds */ 65 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW, 66 &ieee80211_cac_timeout, 0, "CAC timeout (secs)"); 67 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000) 68 69 /* 70 DFS* In order to facilitate debugging, a couple of operating 71 * modes aside from the default are needed. 72 * 73 * 0 - default CAC/NOL behaviour - ie, start CAC, place 74 * channel on NOL list. 75 * 1 - send CAC, but don't change channel or add the channel 76 * to the NOL list. 77 * 2 - just match on radar, don't send CAC or place channel in 78 * the NOL list. 79 */ 80 static int ieee80211_dfs_debug = DFS_DBG_NONE; 81 82 /* 83 * This option must not be included in the default kernel 84 * as it allows users to plainly disable CAC/NOL handling. 85 */ 86 #ifdef IEEE80211_DFS_DEBUG 87 SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW, 88 &ieee80211_dfs_debug, 0, "DFS debug behaviour"); 89 #endif 90 91 static int 92 null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm) 93 { 94 return ENOSYS; 95 } 96 97 void 98 ieee80211_dfs_attach(struct ieee80211com *ic) 99 { 100 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 101 102 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0); 103 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0); 104 105 ic->ic_set_quiet = null_set_quiet; 106 } 107 108 void 109 ieee80211_dfs_detach(struct ieee80211com *ic) 110 { 111 /* NB: we assume no locking is needed */ 112 ieee80211_dfs_reset(ic); 113 } 114 115 void 116 ieee80211_dfs_reset(struct ieee80211com *ic) 117 { 118 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 119 int i; 120 121 /* NB: we assume no locking is needed */ 122 /* NB: cac_timer should be cleared by the state machine */ 123 callout_drain(&dfs->nol_timer); 124 for (i = 0; i < ic->ic_nchans; i++) 125 ic->ic_channels[i].ic_state = 0; 126 dfs->lastchan = NULL; 127 } 128 129 static void 130 cac_timeout(void *arg) 131 { 132 struct ieee80211vap *vap = arg; 133 struct ieee80211com *ic = vap->iv_ic; 134 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 135 int i; 136 137 IEEE80211_LOCK_ASSERT(ic); 138 139 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */ 140 return; 141 /* 142 * When radar is detected during a CAC we are woken 143 * up prematurely to switch to a new channel. 144 * Check the channel to decide how to act. 145 */ 146 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) { 147 ieee80211_notify_cac(ic, ic->ic_curchan, 148 IEEE80211_NOTIFY_CAC_RADAR); 149 150 if_printf(vap->iv_ifp, 151 "CAC timer on channel %u (%u MHz) stopped due to radar\n", 152 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 153 154 /* XXX clobbers any existing desired channel */ 155 /* NB: dfs->newchan may be NULL, that's ok */ 156 vap->iv_des_chan = dfs->newchan; 157 ieee80211_new_state_locked(vap, IEEE80211_S_SCAN, 0); 158 } else { 159 if_printf(vap->iv_ifp, 160 "CAC timer on channel %u (%u MHz) expired; " 161 "no radar detected\n", 162 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 163 /* 164 * Mark all channels with the current frequency 165 * as having completed CAC; this keeps us from 166 * doing it again until we change channels. 167 */ 168 for (i = 0; i < ic->ic_nchans; i++) { 169 struct ieee80211_channel *c = &ic->ic_channels[i]; 170 if (c->ic_freq == ic->ic_curchan->ic_freq) 171 c->ic_state |= IEEE80211_CHANSTATE_CACDONE; 172 } 173 ieee80211_notify_cac(ic, ic->ic_curchan, 174 IEEE80211_NOTIFY_CAC_EXPIRE); 175 ieee80211_cac_completeswitch(vap); 176 } 177 } 178 179 /* 180 * Initiate the CAC timer. The driver is responsible 181 * for setting up the hardware to scan for radar on the 182 * channnel, we just handle timing things out. 183 */ 184 void 185 ieee80211_dfs_cac_start(struct ieee80211vap *vap) 186 { 187 struct ieee80211com *ic = vap->iv_ic; 188 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 189 190 IEEE80211_LOCK_ASSERT(ic); 191 192 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap); 193 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n", 194 ticks_to_secs(CAC_TIMEOUT), 195 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 196 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START); 197 } 198 199 /* 200 * Clear the CAC timer. 201 */ 202 void 203 ieee80211_dfs_cac_stop(struct ieee80211vap *vap) 204 { 205 struct ieee80211com *ic = vap->iv_ic; 206 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 207 208 IEEE80211_LOCK_ASSERT(ic); 209 210 /* NB: racey but not important */ 211 if (callout_pending(&dfs->cac_timer)) { 212 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n", 213 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 214 ieee80211_notify_cac(ic, ic->ic_curchan, 215 IEEE80211_NOTIFY_CAC_STOP); 216 } 217 callout_stop(&dfs->cac_timer); 218 } 219 220 void 221 ieee80211_dfs_cac_clear(struct ieee80211com *ic, 222 const struct ieee80211_channel *chan) 223 { 224 int i; 225 226 for (i = 0; i < ic->ic_nchans; i++) { 227 struct ieee80211_channel *c = &ic->ic_channels[i]; 228 if (c->ic_freq == chan->ic_freq) 229 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 230 } 231 } 232 233 static void 234 dfs_timeout(void *arg) 235 { 236 struct ieee80211com *ic = arg; 237 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 238 struct ieee80211_channel *c; 239 int i, oldest, now; 240 241 IEEE80211_LOCK_ASSERT(ic); 242 243 now = oldest = ticks; 244 for (i = 0; i < ic->ic_nchans; i++) { 245 c = &ic->ic_channels[i]; 246 if (IEEE80211_IS_CHAN_RADAR(c)) { 247 if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) { 248 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR; 249 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) { 250 /* 251 * NB: do this here so we get only one 252 * msg instead of one for every channel 253 * table entry. 254 */ 255 ic_printf(ic, "radar on channel %u " 256 "(%u MHz) cleared after timeout\n", 257 c->ic_ieee, c->ic_freq); 258 /* notify user space */ 259 c->ic_state &= 260 ~IEEE80211_CHANSTATE_NORADAR; 261 ieee80211_notify_radar(ic, c); 262 } 263 } else if (dfs->nol_event[i] < oldest) 264 oldest = dfs->nol_event[i]; 265 } 266 } 267 if (oldest != now) { 268 /* arrange to process next channel up for a status change */ 269 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now); 270 } 271 } 272 273 static void 274 announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan, 275 const struct ieee80211_channel *newchan) 276 { 277 if (newchan == NULL) 278 ic_printf(ic, "radar detected on channel %u (%u MHz)\n", 279 curchan->ic_ieee, curchan->ic_freq); 280 else 281 ic_printf(ic, "radar detected on channel %u (%u MHz), " 282 "moving to channel %u (%u MHz)\n", 283 curchan->ic_ieee, curchan->ic_freq, 284 newchan->ic_ieee, newchan->ic_freq); 285 } 286 287 /* 288 * Handle a radar detection event on a channel. The channel is 289 * added to the NOL list and we record the time of the event. 290 * Entries are aged out after NOL_TIMEOUT. If radar was 291 * detected while doing CAC we force a state/channel change. 292 * Otherwise radar triggers a channel switch using the CSA 293 * mechanism (when the channel is the bss channel). 294 */ 295 void 296 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 297 { 298 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 299 int i, now; 300 301 IEEE80211_LOCK_ASSERT(ic); 302 303 /* 304 * If doing DFS debugging (mode 2), don't bother 305 * running the rest of this function. 306 * 307 * Simply announce the presence of the radar and continue 308 * along merrily. 309 */ 310 if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) { 311 announce_radar(ic, chan, chan); 312 ieee80211_notify_radar(ic, chan); 313 return; 314 } 315 316 /* 317 * Don't mark the channel and don't put it into NOL 318 * if we're doing DFS debugging. 319 */ 320 if (ieee80211_dfs_debug == DFS_DBG_NONE) { 321 /* 322 * Mark all entries with this frequency. Notify user 323 * space and arrange for notification when the radar 324 * indication is cleared. Then kick the NOL processing 325 * thread if not already running. 326 */ 327 now = ticks; 328 for (i = 0; i < ic->ic_nchans; i++) { 329 struct ieee80211_channel *c = &ic->ic_channels[i]; 330 if (c->ic_freq == chan->ic_freq) { 331 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 332 c->ic_state |= IEEE80211_CHANSTATE_RADAR; 333 dfs->nol_event[i] = now; 334 } 335 } 336 ieee80211_notify_radar(ic, chan); 337 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR; 338 if (!callout_pending(&dfs->nol_timer)) 339 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, 340 dfs_timeout, ic); 341 } 342 343 /* 344 * If radar is detected on the bss channel while 345 * doing CAC; force a state change by scheduling the 346 * callout to be dispatched asap. Otherwise, if this 347 * event is for the bss channel then we must quiet 348 * traffic and schedule a channel switch. 349 * 350 * Note this allows us to receive notification about 351 * channels other than the bss channel; not sure 352 * that can/will happen but it's simple to support. 353 */ 354 if (chan == ic->ic_bsschan) { 355 /* XXX need a way to defer to user app */ 356 357 /* 358 * Don't flip over to a new channel if 359 * we are currently doing DFS debugging. 360 */ 361 if (ieee80211_dfs_debug == DFS_DBG_NONE) 362 dfs->newchan = ieee80211_dfs_pickchannel(ic); 363 else 364 dfs->newchan = chan; 365 366 announce_radar(ic, chan, dfs->newchan); 367 368 if (callout_pending(&dfs->cac_timer)) 369 callout_schedule(&dfs->cac_timer, 0); 370 else if (dfs->newchan != NULL) { 371 /* XXX mode 1, switch count 2 */ 372 /* XXX calculate switch count based on max 373 switch time and beacon interval? */ 374 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 375 } else { 376 /* 377 * Spec says to stop all transmissions and 378 * wait on the current channel for an entry 379 * on the NOL to expire. 380 */ 381 /*XXX*/ 382 ic_printf(ic, "%s: No free channels; waiting for entry " 383 "on NOL to expire\n", __func__); 384 } 385 } else { 386 /* 387 * Issue rate-limited console msgs. 388 */ 389 if (dfs->lastchan != chan) { 390 dfs->lastchan = chan; 391 dfs->cureps = 0; 392 announce_radar(ic, chan, NULL); 393 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 394 announce_radar(ic, chan, NULL); 395 } 396 } 397 } 398 399 struct ieee80211_channel * 400 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 401 { 402 struct ieee80211_channel *c; 403 int i, flags; 404 uint16_t v; 405 406 /* 407 * Consult the scan cache first. 408 */ 409 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 410 /* 411 * XXX if curchan is HT this will never find a channel 412 * XXX 'cuz we scan only legacy channels 413 */ 414 c = ieee80211_scan_pickchannel(ic, flags); 415 if (c != NULL) 416 return c; 417 /* 418 * No channel found in scan cache; select a compatible 419 * one at random (skipping channels where radar has 420 * been detected). 421 */ 422 get_random_bytes(&v, sizeof(v)); 423 v %= ic->ic_nchans; 424 for (i = v; i < ic->ic_nchans; i++) { 425 c = &ic->ic_channels[i]; 426 if (!IEEE80211_IS_CHAN_RADAR(c) && 427 (c->ic_flags & flags) == flags) 428 return c; 429 } 430 for (i = 0; i < v; i++) { 431 c = &ic->ic_channels[i]; 432 if (!IEEE80211_IS_CHAN_RADAR(c) && 433 (c->ic_flags & flags) == flags) 434 return c; 435 } 436 ic_printf(ic, "HELP, no channel located to switch to!\n"); 437 return NULL; 438 }
Cache object: f70c4603b76814f25407e184c6984137
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