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 * $FreeBSD: head/sys/net80211/ieee80211_dfs.c 196785 2009-09-03 16:29:02Z sam $ 26 * $DragonFly$ 27 */ 28 29 /* 30 * IEEE 802.11 DFS/Radar support. 31 */ 32 #include "opt_inet.h" 33 #include "opt_wlan.h" 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/mbuf.h> 38 #include <sys/malloc.h> 39 #include <sys/kernel.h> 40 41 #include <sys/socket.h> 42 #include <sys/sockio.h> 43 #include <sys/endian.h> 44 #include <sys/errno.h> 45 #include <sys/proc.h> 46 #include <sys/sysctl.h> 47 48 #include <net/if.h> 49 #include <net/if_media.h> 50 #include <net/route.h> 51 52 #include <netproto/802_11/ieee80211_var.h> 53 54 MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state"); 55 56 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */ 57 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW, 58 &ieee80211_nol_timeout, 0, "NOL timeout (secs)"); 59 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000) 60 61 static int ieee80211_cac_timeout = 60; /* 60 seconds */ 62 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW, 63 &ieee80211_cac_timeout, 0, "CAC timeout (secs)"); 64 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000) 65 66 void 67 ieee80211_dfs_attach(struct ieee80211com *ic) 68 { 69 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 70 71 callout_init(&dfs->nol_timer); 72 callout_init(&dfs->cac_timer); 73 } 74 75 void 76 ieee80211_dfs_detach(struct ieee80211com *ic) 77 { 78 /* NB: we assume no locking is needed */ 79 ieee80211_dfs_reset(ic); 80 } 81 82 void 83 ieee80211_dfs_reset(struct ieee80211com *ic) 84 { 85 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 86 int i; 87 88 /* NB: we assume no locking is needed */ 89 /* NB: cac_timer should be cleared by the state machine */ 90 callout_stop(&dfs->nol_timer); 91 for (i = 0; i < ic->ic_nchans; i++) 92 ic->ic_channels[i].ic_state = 0; 93 dfs->lastchan = NULL; 94 } 95 96 static void 97 cac_timeout_callout(void *arg) 98 { 99 struct ieee80211vap *vap = arg; 100 struct ieee80211com *ic; 101 struct ieee80211_dfs_state *dfs; 102 int i; 103 104 wlan_serialize_enter(); 105 ic = vap->iv_ic; 106 dfs = &ic->ic_dfs; 107 if (vap->iv_state != IEEE80211_S_CAC) { /* NB: just in case */ 108 wlan_serialize_exit(); 109 return; 110 } 111 /* 112 * When radar is detected during a CAC we are woken 113 * up prematurely to switch to a new channel. 114 * Check the channel to decide how to act. 115 */ 116 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) { 117 ieee80211_notify_cac(ic, ic->ic_curchan, 118 IEEE80211_NOTIFY_CAC_RADAR); 119 120 if_printf(vap->iv_ifp, 121 "CAC timer on channel %u (%u MHz) stopped due to radar\n", 122 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 123 124 /* XXX clobbers any existing desired channel */ 125 /* NB: dfs->newchan may be NULL, that's ok */ 126 vap->iv_des_chan = dfs->newchan; 127 /* XXX recursive lock need ieee80211_new_state_locked */ 128 ieee80211_new_state(vap, IEEE80211_S_SCAN, 0); 129 } else { 130 if_printf(vap->iv_ifp, 131 "CAC timer on channel %u (%u MHz) expired; " 132 "no radar detected\n", 133 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 134 /* 135 * Mark all channels with the current frequency 136 * as having completed CAC; this keeps us from 137 * doing it again until we change channels. 138 */ 139 for (i = 0; i < ic->ic_nchans; i++) { 140 struct ieee80211_channel *c = &ic->ic_channels[i]; 141 if (c->ic_freq == ic->ic_curchan->ic_freq) 142 c->ic_state |= IEEE80211_CHANSTATE_CACDONE; 143 } 144 ieee80211_notify_cac(ic, ic->ic_curchan, 145 IEEE80211_NOTIFY_CAC_EXPIRE); 146 ieee80211_cac_completeswitch(vap); 147 } 148 wlan_serialize_exit(); 149 } 150 151 /* 152 * Initiate the CAC timer. The driver is responsible 153 * for setting up the hardware to scan for radar on the 154 * channnel, we just handle timing things out. 155 */ 156 void 157 ieee80211_dfs_cac_start(struct ieee80211vap *vap) 158 { 159 struct ieee80211com *ic = vap->iv_ic; 160 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 161 162 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout_callout, vap); 163 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n", 164 ticks_to_secs(CAC_TIMEOUT), 165 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 166 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START); 167 } 168 169 /* 170 * Clear the CAC timer. 171 */ 172 void 173 ieee80211_dfs_cac_stop(struct ieee80211vap *vap) 174 { 175 struct ieee80211com *ic = vap->iv_ic; 176 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 177 178 /* NB: racey but not important */ 179 if (callout_pending(&dfs->cac_timer)) { 180 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n", 181 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq); 182 ieee80211_notify_cac(ic, ic->ic_curchan, 183 IEEE80211_NOTIFY_CAC_STOP); 184 } 185 callout_stop(&dfs->cac_timer); 186 } 187 188 void 189 ieee80211_dfs_cac_clear(struct ieee80211com *ic, 190 const struct ieee80211_channel *chan) 191 { 192 int i; 193 194 for (i = 0; i < ic->ic_nchans; i++) { 195 struct ieee80211_channel *c = &ic->ic_channels[i]; 196 if (c->ic_freq == chan->ic_freq) 197 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE; 198 } 199 } 200 201 static void 202 dfs_timeout_callout(void *arg) 203 { 204 struct ieee80211com *ic = arg; 205 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 206 struct ieee80211_channel *c; 207 int i, oldest, now; 208 209 wlan_serialize_enter(); 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_reset(&dfs->nol_timer, oldest + NOL_TIMEOUT - now, 237 dfs_timeout_callout, ic); 238 } 239 wlan_serialize_exit(); 240 } 241 242 static void 243 announce_radar(struct ifnet *ifp, const struct ieee80211_channel *curchan, 244 const struct ieee80211_channel *newchan) 245 { 246 if (newchan == NULL) 247 if_printf(ifp, "radar detected on channel %u (%u MHz)\n", 248 curchan->ic_ieee, curchan->ic_freq); 249 else 250 if_printf(ifp, "radar detected on channel %u (%u MHz), " 251 "moving to channel %u (%u MHz)\n", 252 curchan->ic_ieee, curchan->ic_freq, 253 newchan->ic_ieee, newchan->ic_freq); 254 } 255 256 /* 257 * Handle a radar detection event on a channel. The channel is 258 * added to the NOL list and we record the time of the event. 259 * Entries are aged out after NOL_TIMEOUT. If radar was 260 * detected while doing CAC we force a state/channel change. 261 * Otherwise radar triggers a channel switch using the CSA 262 * mechanism (when the channel is the bss channel). 263 */ 264 void 265 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan) 266 { 267 struct ieee80211_dfs_state *dfs = &ic->ic_dfs; 268 int i, now; 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, 289 dfs_timeout_callout, ic); 290 } 291 292 /* 293 * If radar is detected on the bss channel while 294 * doing CAC; force a state change by scheduling the 295 * callout to be dispatched asap. Otherwise, if this 296 * event is for the bss channel then we must quiet 297 * traffic and schedule a channel switch. 298 * 299 * Note this allows us to receive notification about 300 * channels other than the bss channel; not sure 301 * that can/will happen but it's simple to support. 302 */ 303 if (chan == ic->ic_bsschan) { 304 /* XXX need a way to defer to user app */ 305 dfs->newchan = ieee80211_dfs_pickchannel(ic); 306 307 announce_radar(ic->ic_ifp, chan, dfs->newchan); 308 309 #ifdef notyet 310 if (callout_pending(&dfs->cac_timer)) { 311 callout_reset(&dfs->cac_timer, 0, 312 cac_timeout_callout, vap); 313 } 314 else if (dfs->newchan != NULL) { 315 /* XXX mode 1, switch count 2 */ 316 /* XXX calculate switch count based on max 317 switch time and beacon interval? */ 318 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2); 319 } else { 320 /* 321 * Spec says to stop all transmissions and 322 * wait on the current channel for an entry 323 * on the NOL to expire. 324 */ 325 /*XXX*/ 326 } 327 #endif 328 } else { 329 /* 330 * Issue rate-limited console msgs. 331 */ 332 if (dfs->lastchan != chan) { 333 dfs->lastchan = chan; 334 dfs->cureps = 0; 335 announce_radar(ic->ic_ifp, chan, NULL); 336 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) { 337 announce_radar(ic->ic_ifp, chan, NULL); 338 } 339 } 340 } 341 342 struct ieee80211_channel * 343 ieee80211_dfs_pickchannel(struct ieee80211com *ic) 344 { 345 struct ieee80211_channel *c; 346 int i, flags; 347 uint16_t v; 348 349 /* 350 * Consult the scan cache first. 351 */ 352 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL; 353 /* 354 * XXX if curchan is HT this will never find a channel 355 * XXX 'cuz we scan only legacy channels 356 */ 357 c = ieee80211_scan_pickchannel(ic, flags); 358 if (c != NULL) 359 return c; 360 /* 361 * No channel found in scan cache; select a compatible 362 * one at random (skipping channels where radar has 363 * been detected). 364 */ 365 get_random_bytes(&v, sizeof(v)); 366 v %= ic->ic_nchans; 367 for (i = v; i < ic->ic_nchans; i++) { 368 c = &ic->ic_channels[i]; 369 if (!IEEE80211_IS_CHAN_RADAR(c) && 370 (c->ic_flags & flags) == flags) 371 return c; 372 } 373 for (i = 0; i < v; i++) { 374 c = &ic->ic_channels[i]; 375 if (!IEEE80211_IS_CHAN_RADAR(c) && 376 (c->ic_flags & flags) == flags) 377 return c; 378 } 379 if_printf(ic->ic_ifp, "HELP, no channel located to switch to!\n"); 380 return NULL; 381 } 382