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_media.h> 52 53 #include <net80211/ieee80211_var.h> 54 55 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */ 56 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW, 57 &ieee80211_nol_timeout, 0, "NOL timeout (secs)"); 58 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000) 59 60 static int ieee80211_cac_timeout = 60; /* 60 seconds */ 61 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW, 62 &ieee80211_cac_timeout, 0, "CAC timeout (secs)"); 63 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000) 64 65 void 66 ieee80211_dfs_attach(struct ieee80211com *ic) 67 { 68 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 69 70 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0); 71 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0); 72 } 73 74 void 75 ieee80211_dfs_detach(struct ieee80211com *ic) 76 { 77 /* NB: we assume no locking is needed */ 78 ieee80211_dfs_reset(ic); 79 } 80 81 void 82 ieee80211_dfs_reset(struct ieee80211com *ic) 83 { 84 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 85 int i; 86 87 /* NB: we assume no locking is needed */ 88 /* NB: cac_timer should be cleared by the state machine */ 89 callout_drain(&dfs->nol_timer); 90 for (i = 0; i < ic->ic_nchans; i++) 91 ic->ic_channels[i].ic_state = 0; 92 dfs->lastchan = NULL; 93 } 94 95 static void 96 cac_timeout(void *arg) 97 { 98 struct ieee80211vap *vap = arg; 99 struct ieee80211com *ic = vap->iv_ic; 100 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 101 int i; 102 103 IEEE80211_LOCK_ASSERT(ic); 104 105 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */ 106 return; 107 /* 108 * When radar is detected during a CAC we are woken 109 * up prematurely to switch to a new channel. 110 * Check the channel to decide how to act. 111 */ 112 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) { 113 ieee80211_notify_cac(ic, ic->ic_curchan, 114 IEEE80211_NOTIFY_CAC_RADAR); 115 116 if_printf(vap->iv_ifp, 117 "CAC timer on channel %u (%u MHz) stopped due to radar\n", 118 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 119 120 /* XXX clobbers any existing desired channel */ 121 /* NB: dfs->newchan may be NULL, that's ok */ 122 vap->iv_des_chan = dfs->newchan; 123 /* XXX recursive lock need ieee80211_new_state_locked */ 124 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0); 125 } else { 126 if_printf(vap->iv_ifp, 127 "CAC timer on channel %u (%u MHz) expired; " 128 "no radar detected\n", 129 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 130 /* 131 * Mark all channels with the current frequency 132 * as having completed CAC; this keeps us from 133 * doing it again until we change channels. 134 */ 135 for (i = 0; i < ic->ic_nchans; i++) { 136 struct ieee80211_channel *c = &ic->ic_channels[i]; 137 if (c->ic_freq == ic->ic_curchan->ic_freq) 138 c->ic_state |= IEEE80211_CHANSTATE_CACDONE; 139 } 140 ieee80211_notify_cac(ic, ic->ic_curchan, 141 IEEE80211_NOTIFY_CAC_EXPIRE); 142 ieee80211_cac_completeswitch(vap); 143 } 144 } 145 146 /* 147 * Initiate the CAC timer. The driver is responsible 148 * for setting up the hardware to scan for radar on the 149 * channnel, we just handle timing things out. 150 */ 151 void 152 ieee80211_dfs_cac_start(struct ieee80211vap *vap) 153 { 154 struct ieee80211com *ic = vap->iv_ic; 155 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 156 157 IEEE80211_LOCK_ASSERT(ic); 158 159 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap); 160 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n", 161 ticks_to_secs(CAC_TIMEOUT), 162 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 163 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START); 164 } 165 166 /* 167 * Clear the CAC timer. 168 */ 169 void 170 ieee80211_dfs_cac_stop(struct ieee80211vap *vap) 171 { 172 struct ieee80211com *ic = vap->iv_ic; 173 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 174 175 IEEE80211_LOCK_ASSERT(ic); 176 177 /* NB: racey but not important */ 178 if (callout_pending(&dfs->cac_timer)) { 179 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n", 180 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 181 ieee80211_notify_cac(ic, ic->ic_curchan, 182 IEEE80211_NOTIFY_CAC_STOP); 183 } 184 callout_stop(&dfs->cac_timer); 185 } 186 187 void 188 ieee80211_dfs_cac_clear(struct ieee80211com *ic, 189 const struct ieee80211_channel *chan) 190 { 191 int i; 192 193 for (i = 0; i < ic->ic_nchans; i++) { 194 struct ieee80211_channel *c = &ic->ic_channels[i]; 195 if (c->ic_freq == chan->ic_freq) 196 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 197 } 198 } 199 200 static void 201 dfs_timeout(void *arg) 202 { 203 struct ieee80211com *ic = arg; 204 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 205 struct ieee80211_channel *c; 206 int i, oldest, now; 207 208 IEEE80211_LOCK_ASSERT(ic); 209 210 now = oldest = ticks; 211 for (i = 0; i < ic->ic_nchans; i++) { 212 c = &ic->ic_channels[i]; 213 if (IEEE80211_IS_CHAN_RADAR(c)) { 214 if (time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) { 215 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR; 216 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) { 217 /* 218 * NB: do this here so we get only one 219 * msg instead of one for every channel 220 * table entry. 221 */ 222 if_printf(ic->ic_ifp, "radar on channel" 223 " %u (%u MHz) cleared after timeout\n", 224 c->ic_ieee, c->ic_freq); 225 /* notify user space */ 226 c->ic_state &= 227 ~IEEE80211_CHANSTATE_NORADAR; 228 ieee80211_notify_radar(ic, c); 229 } 230 } else if (dfs->nol_event[i] < oldest) 231 oldest = dfs->nol_event[i]; 232 } 233 } 234 if (oldest != now) { 235 /* arrange to process next channel up for a status change */ 236 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now); 237 } 238 } 239 240 static void 241 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan, 242 const struct ieee80211_channel *newchan) 243 { 244 if (newchan == NULL) 245 if_printf(ifp, "radar detected on channel %u (%u MHz)\n", 246 curchan->ic_ieee, curchan->ic_freq); 247 else 248 if_printf(ifp, "radar detected on channel %u (%u MHz), " 249 "moving to channel %u (%u MHz)\n", 250 curchan->ic_ieee, curchan->ic_freq, 251 newchan->ic_ieee, newchan->ic_freq); 252 } 253 254 /* 255 * Handle a radar detection event on a channel. The channel is 256 * added to the NOL list and we record the time of the event. 257 * Entries are aged out after NOL_TIMEOUT. If radar was 258 * detected while doing CAC we force a state/channel change. 259 * Otherwise radar triggers a channel switch using the CSA 260 * mechanism (when the channel is the bss channel). 261 */ 262 void 263 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 264 { 265 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 266 int i, now; 267 268 IEEE80211_LOCK_ASSERT(ic); 269 270 /* 271 * Mark all entries with this frequency. Notify user 272 * space and arrange for notification when the radar 273 * indication is cleared. Then kick the NOL processing 274 * thread if not already running. 275 */ 276 now = ticks; 277 for (i = 0; i < ic->ic_nchans; i++) { 278 struct ieee80211_channel *c = &ic->ic_channels[i]; 279 if (c->ic_freq == chan->ic_freq) { 280 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 281 c->ic_state |= IEEE80211_CHANSTATE_RADAR; 282 dfs->nol_event[i] = now; 283 } 284 } 285 ieee80211_notify_radar(ic, chan); 286 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR; 287 if (!callout_pending(&dfs->nol_timer)) 288 callout_reset(&dfs->nol_timer, NOL_TIMEOUT, dfs_timeout, ic); 289 290 /* 291 * If radar is detected on the bss channel while 292 * doing CAC; force a state change by scheduling the 293 * callout to be dispatched asap. Otherwise, if this 294 * event is for the bss channel then we must quiet 295 * traffic and schedule a channel switch. 296 * 297 * Note this allows us to receive notification about 298 * channels other than the bss channel; not sure 299 * that can/will happen but it's simple to support. 300 */ 301 if (chan == ic->ic_bsschan) { 302 /* XXX need a way to defer to user app */ 303 dfs->newchan = ieee80211_dfs_pickchannel(ic); 304 305 announce_radar(ic->ic_ifp, chan, dfs->newchan); 306 307 if (callout_pending(&dfs->cac_timer)) 308 callout_schedule(&dfs->cac_timer, 0); 309 else if (dfs->newchan != NULL) { 310 /* XXX mode 1, switch count 2 */ 311 /* XXX calculate switch count based on max 312 switch time and beacon interval? */ 313 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 314 } else { 315 /* 316 * Spec says to stop all transmissions and 317 * wait on the current channel for an entry 318 * on the NOL to expire. 319 */ 320 /*XXX*/ 321 if_printf(ic->ic_ifp, "%s: No free channels; waiting for entry " 322 "on NOL to expire\n", __func__); 323 } 324 } else { 325 /* 326 * Issue rate-limited console msgs. 327 */ 328 if (dfs->lastchan != chan) { 329 dfs->lastchan = chan; 330 dfs->cureps = 0; 331 announce_radar(ic->ic_ifp, chan, NULL); 332 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 333 announce_radar(ic->ic_ifp, chan, NULL); 334 } 335 } 336 } 337 338 struct ieee80211_channel * 339 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 340 { 341 struct ieee80211_channel *c; 342 int i, flags; 343 uint16_t v; 344 345 /* 346 * Consult the scan cache first. 347 */ 348 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 349 /* 350 * XXX if curchan is HT this will never find a channel 351 * XXX 'cuz we scan only legacy channels 352 */ 353 c = ieee80211_scan_pickchannel(ic, flags); 354 if (c != NULL) 355 return c; 356 /* 357 * No channel found in scan cache; select a compatible 358 * one at random (skipping channels where radar has 359 * been detected). 360 */ 361 get_random_bytes(&v, sizeof(v)); 362 v %= ic->ic_nchans; 363 for (i = v; i < ic->ic_nchans; i++) { 364 c = &ic->ic_channels[i]; 365 if (!IEEE80211_IS_CHAN_RADAR(c) && 366 (c->ic_flags & flags) == flags) 367 return c; 368 } 369 for (i = 0; i < v; i++) { 370 c = &ic->ic_channels[i]; 371 if (!IEEE80211_IS_CHAN_RADAR(c) && 372 (c->ic_flags & flags) == flags) 373 return c; 374 } 375 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n"); 376 return NULL; 377 } 378