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 /* XXX recursive lock need ieee80211_new_state_locked */ 158 ieee80211_new_state(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 (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 if_printf(ic->ic_ifp, "radar on channel" 257 " %u (%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 ifnet *ifp, const struct ieee80211_channel *curchan, 276 const struct ieee80211_channel *newchan) 277 { 278 if (newchan == NULL) 279 if_printf(ifp, "radar detected on channel %u (%u MHz)\n", 280 curchan->ic_ieee, curchan->ic_freq); 281 else 282 if_printf(ifp, "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->ic_ifp, 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->ic_ifp, 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 if_printf(ic->ic_ifp, "%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->ic_ifp, chan, NULL); 394 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 395 announce_radar(ic->ic_ifp, 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 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 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n"); 438 return NULL; 439 } 440