sys/net80211/ieee80211_scan_sw.c

   1 /*-
   2  * Copyright (c) 2002-2008 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 __FBSDID("$FreeBSD$");
  28
  29 /*
  30  * IEEE 802.11 scanning support.
  31  */
  32 #include "opt_wlan.h"
  33
  34 #include <sys/param.h>
  35 #include <sys/systm.h>
  36 #include <sys/proc.h>
  37 #include <sys/kernel.h>
  38 #include <sys/condvar.h>
  39
  40 #include <sys/socket.h>
  41
  42 #include <net/if.h>
  43 #include <net/if_var.h>
  44 #include <net/if_media.h>
  45 #include <net/ethernet.h>
  46
  47 #include <net80211/ieee80211_var.h>
  48
  49 #include <net80211/ieee80211_scan_sw.h>
  50
  51 #include <net/bpf.h>
  52
  53 struct scan_state {
  54         struct ieee80211_scan_state base;       /* public state */
  55
  56         u_int           ss_iflags;              /* flags used internally */
  57 #define ISCAN_MINDWELL  0x0001          /* min dwell time reached */
  58 #define ISCAN_DISCARD   0x0002          /* discard rx'd frames */
  59 #define ISCAN_CANCEL    0x0004          /* cancel current scan */
  60 #define ISCAN_ABORT     0x0008          /* end the scan immediately */
  61         unsigned long   ss_chanmindwell;        /* min dwell on curchan */
  62         unsigned long   ss_scanend;             /* time scan must stop */
  63         u_int           ss_duration;            /* duration for next scan */
  64         struct task     ss_scan_task;           /* scan execution */
  65         struct cv       ss_scan_cv;             /* scan signal */
  66         struct callout  ss_scan_timer;          /* scan timer */
  67 };
  68 #define SCAN_PRIVATE(ss)        ((struct scan_state *) ss)
  69
  70 /*
  71  * Amount of time to go off-channel during a background
  72  * scan.  This value should be large enough to catch most
  73  * ap's but short enough that we can return on-channel
  74  * before our listen interval expires.
  75  *
  76  * XXX tunable
  77  * XXX check against configured listen interval
  78  */
  79 #define IEEE80211_SCAN_OFFCHANNEL       msecs_to_ticks(150)
  80
  81 /*
  82  * Roaming-related defaults.  RSSI thresholds are as returned by the
  83  * driver (.5dBm).  Transmit rate thresholds are IEEE rate codes (i.e
  84  * .5M units) or MCS.
  85  */
  86 /* rssi thresholds */
  87 #define ROAM_RSSI_11A_DEFAULT           14      /* 11a bss */
  88 #define ROAM_RSSI_11B_DEFAULT           14      /* 11b bss */
  89 #define ROAM_RSSI_11BONLY_DEFAULT       14      /* 11b-only bss */
  90 /* transmit rate thresholds */
  91 #define ROAM_RATE_11A_DEFAULT           2*12    /* 11a bss */
  92 #define ROAM_RATE_11B_DEFAULT           2*5     /* 11b bss */
  93 #define ROAM_RATE_11BONLY_DEFAULT       2*1     /* 11b-only bss */
  94 #define ROAM_RATE_HALF_DEFAULT          2*6     /* half-width 11a/g bss */
  95 #define ROAM_RATE_QUARTER_DEFAULT       2*3     /* quarter-width 11a/g bss */
  96 #define ROAM_MCS_11N_DEFAULT            (1 | IEEE80211_RATE_MCS) /* 11n bss */
  97
  98 static  void scan_curchan(struct ieee80211_scan_state *, unsigned long);
  99 static  void scan_mindwell(struct ieee80211_scan_state *);
 100 static  void scan_signal(void *);
 101 static  void scan_task(void *, int);
 102
 103 MALLOC_DEFINE(M_80211_SCAN, "80211scan", "802.11 scan state");
 104
 105 static void
 106 ieee80211_swscan_detach(struct ieee80211com *ic)
 107 {
 108         struct ieee80211_scan_state *ss = ic->ic_scan;
 109
 110         if (ss != NULL) {
 111                 IEEE80211_LOCK(ic);
 112                 SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_ABORT;
 113                 scan_signal(ss);
 114                 IEEE80211_UNLOCK(ic);
 115                 ieee80211_draintask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
 116                 callout_drain(&SCAN_PRIVATE(ss)->ss_scan_timer);
 117                 KASSERT((ic->ic_flags & IEEE80211_F_SCAN) == 0,
 118                     ("scan still running"));
 119
 120                 /*
 121                  * For now, do the ss_ops detach here rather
 122                  * than ieee80211_scan_detach().
 123                  *
 124                  * I'll figure out how to cleanly split things up
 125                  * at a later date.
 126                  */
 127                 if (ss->ss_ops != NULL) {
 128                         ss->ss_ops->scan_detach(ss);
 129                         ss->ss_ops = NULL;
 130                 }
 131                 ic->ic_scan = NULL;
 132                 IEEE80211_FREE(SCAN_PRIVATE(ss), M_80211_SCAN);
 133         }
 134 }
 135
 136 static void
 137 ieee80211_swscan_vattach(struct ieee80211vap *vap)
 138 {
 139         /* nothing to do for now */
 140         /*
 141          * TODO: all of the vap scan calls should be methods!
 142          */
 143
 144 }
 145
 146 static void
 147 ieee80211_swscan_vdetach(struct ieee80211vap *vap)
 148 {
 149         struct ieee80211com *ic = vap->iv_ic;
 150         struct ieee80211_scan_state *ss;
 151
 152         IEEE80211_LOCK_ASSERT(ic);
 153         ss = ic->ic_scan;
 154         if (ss != NULL && ss->ss_vap == vap) {
 155                 if (ic->ic_flags & IEEE80211_F_SCAN) {
 156                         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_ABORT;
 157                         scan_signal(ss);
 158                 }
 159         }
 160 }
 161
 162 static void
 163 ieee80211_swscan_set_scan_duration(struct ieee80211vap *vap, u_int duration)
 164 {
 165         struct ieee80211com *ic = vap->iv_ic;
 166         struct ieee80211_scan_state *ss = ic->ic_scan;
 167
 168         IEEE80211_LOCK_ASSERT(ic);
 169
 170         /* NB: flush frames rx'd before 1st channel change */
 171         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
 172         SCAN_PRIVATE(ss)->ss_duration = duration;
 173 }
 174
 175 /*
 176  * Start a scan unless one is already going.
 177  */
 178 static int
 179 ieee80211_swscan_start_scan_locked(const struct ieee80211_scanner *scan,
 180         struct ieee80211vap *vap, int flags, u_int duration,
 181         u_int mindwell, u_int maxdwell,
 182         u_int nssid, const struct ieee80211_scan_ssid ssids[])
 183 {
 184         struct ieee80211com *ic = vap->iv_ic;
 185         struct ieee80211_scan_state *ss = ic->ic_scan;
 186
 187         IEEE80211_LOCK_ASSERT(ic);
 188
 189         if (ic->ic_flags & IEEE80211_F_CSAPENDING) {
 190                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 191                     "%s: scan inhibited by pending channel change\n", __func__);
 192         } else if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
 193                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 194                     "%s: %s scan, duration %u mindwell %u maxdwell %u, desired mode %s, %s%s%s%s%s%s\n"
 195                     , __func__
 196                     , flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive"
 197                     , duration, mindwell, maxdwell
 198                     , ieee80211_phymode_name[vap->iv_des_mode]
 199                     , flags & IEEE80211_SCAN_FLUSH ? "flush" : "append"
 200                     , flags & IEEE80211_SCAN_NOPICK ? ", nopick" : ""
 201                     , flags & IEEE80211_SCAN_NOJOIN ? ", nojoin" : ""
 202                     , flags & IEEE80211_SCAN_NOBCAST ? ", nobcast" : ""
 203                     , flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : ""
 204                     , flags & IEEE80211_SCAN_ONCE ? ", once" : ""
 205                 );
 206
 207                 ieee80211_scan_update_locked(vap, scan);
 208                 if (ss->ss_ops != NULL) {
 209                         if ((flags & IEEE80211_SCAN_NOSSID) == 0)
 210                                 ieee80211_scan_copy_ssid(vap, ss, nssid, ssids);
 211
 212                         /* NB: top 4 bits for internal use */
 213                         ss->ss_flags = flags & 0xfff;
 214                         if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
 215                                 vap->iv_stats.is_scan_active++;
 216                         else
 217                                 vap->iv_stats.is_scan_passive++;
 218                         if (flags & IEEE80211_SCAN_FLUSH)
 219                                 ss->ss_ops->scan_flush(ss);
 220                         if (flags & IEEE80211_SCAN_BGSCAN)
 221                                 ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
 222
 223                         /* Set duration for this particular scan */
 224                         ieee80211_swscan_set_scan_duration(vap, duration);
 225
 226                         ss->ss_next = 0;
 227                         ss->ss_mindwell = mindwell;
 228                         ss->ss_maxdwell = maxdwell;
 229                         /* NB: scan_start must be before the scan runtask */
 230                         ss->ss_ops->scan_start(ss, vap);
 231 #ifdef IEEE80211_DEBUG
 232                         if (ieee80211_msg_scan(vap))
 233                                 ieee80211_scan_dump(ss);
 234 #endif /* IEEE80211_DEBUG */
 235                         ic->ic_flags |= IEEE80211_F_SCAN;
 236
 237                         /* Start scan task */
 238                         ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
 239                 }
 240                 return 1;
 241         } else {
 242                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 243                     "%s: %s scan already in progress\n", __func__,
 244                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
 245         }
 246         return 0;
 247 }
 248
 249
 250 /*
 251  * Start a scan unless one is already going.
 252  *
 253  * Called without the comlock held; grab the comlock as appropriate.
 254  */
 255 static int
 256 ieee80211_swscan_start_scan(const struct ieee80211_scanner *scan,
 257     struct ieee80211vap *vap, int flags,
 258     u_int duration, u_int mindwell, u_int maxdwell,
 259     u_int nssid, const struct ieee80211_scan_ssid ssids[])
 260 {
 261         struct ieee80211com *ic = vap->iv_ic;
 262         int result;
 263
 264         IEEE80211_UNLOCK_ASSERT(ic);
 265
 266         IEEE80211_LOCK(ic);
 267         result = ieee80211_swscan_start_scan_locked(scan, vap, flags, duration,
 268             mindwell, maxdwell, nssid, ssids);
 269         IEEE80211_UNLOCK(ic);
 270
 271         return result;
 272 }
 273
 274 /*
 275  * Check the scan cache for an ap/channel to use; if that
 276  * fails then kick off a new scan.
 277  *
 278  * Called with the comlock held.
 279  *
 280  * XXX TODO: split out!
 281  */
 282 static int
 283 ieee80211_swscan_check_scan(const struct ieee80211_scanner *scan,
 284     struct ieee80211vap *vap, int flags,
 285     u_int duration, u_int mindwell, u_int maxdwell,
 286     u_int nssid, const struct ieee80211_scan_ssid ssids[])
 287 {
 288         struct ieee80211com *ic = vap->iv_ic;
 289         struct ieee80211_scan_state *ss = ic->ic_scan;
 290         int result;
 291
 292         IEEE80211_LOCK_ASSERT(ic);
 293
 294         if (ss->ss_ops != NULL) {
 295                 /* XXX verify ss_ops matches vap->iv_opmode */
 296                 if ((flags & IEEE80211_SCAN_NOSSID) == 0) {
 297                         /*
 298                          * Update the ssid list and mark flags so if
 299                          * we call start_scan it doesn't duplicate work.
 300                          */
 301                         ieee80211_scan_copy_ssid(vap, ss, nssid, ssids);
 302                         flags |= IEEE80211_SCAN_NOSSID;
 303                 }
 304                 if ((ic->ic_flags & IEEE80211_F_SCAN) == 0 &&
 305                     (flags & IEEE80211_SCAN_FLUSH) == 0 &&
 306                     time_before(ticks, ic->ic_lastscan + vap->iv_scanvalid)) {
 307                         /*
 308                          * We're not currently scanning and the cache is
 309                          * deemed hot enough to consult.  Lock out others
 310                          * by marking IEEE80211_F_SCAN while we decide if
 311                          * something is already in the scan cache we can
 312                          * use.  Also discard any frames that might come
 313                          * in while temporarily marked as scanning.
 314                          */
 315                         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
 316                         ic->ic_flags |= IEEE80211_F_SCAN;
 317
 318                         /* NB: need to use supplied flags in check */
 319                         ss->ss_flags = flags & 0xff;
 320                         result = ss->ss_ops->scan_end(ss, vap);
 321
 322                         ic->ic_flags &= ~IEEE80211_F_SCAN;
 323                         SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_DISCARD;
 324                         if (result) {
 325                                 ieee80211_notify_scan_done(vap);
 326                                 return 1;
 327                         }
 328                 }
 329         }
 330         result = ieee80211_swscan_start_scan_locked(scan, vap, flags, duration,
 331             mindwell, maxdwell, nssid, ssids);
 332
 333         return result;
 334 }
 335
 336 /*
 337  * Restart a previous scan.  If the previous scan completed
 338  * then we start again using the existing channel list.
 339  */
 340 static int
 341 ieee80211_swscan_bg_scan(const struct ieee80211_scanner *scan,
 342     struct ieee80211vap *vap, int flags)
 343 {
 344         struct ieee80211com *ic = vap->iv_ic;
 345         struct ieee80211_scan_state *ss = ic->ic_scan;
 346
 347         /* XXX assert unlocked? */
 348         // IEEE80211_UNLOCK_ASSERT(ic);
 349
 350         IEEE80211_LOCK(ic);
 351         if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
 352                 u_int duration;
 353                 /*
 354                  * Go off-channel for a fixed interval that is large
 355                  * enough to catch most ap's but short enough that
 356                  * we can return on-channel before our listen interval
 357                  * expires.
 358                  */
 359                 duration = IEEE80211_SCAN_OFFCHANNEL;
 360
 361                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 362                     "%s: %s scan, ticks %u duration %lu\n", __func__,
 363                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
 364                     ticks, duration);
 365
 366                 ieee80211_scan_update_locked(vap, scan);
 367                 if (ss->ss_ops != NULL) {
 368                         ss->ss_vap = vap;
 369                         /*
 370                          * A background scan does not select a new sta; it
 371                          * just refreshes the scan cache.  Also, indicate
 372                          * the scan logic should follow the beacon schedule:
 373                          * we go off-channel and scan for a while, then
 374                          * return to the bss channel to receive a beacon,
 375                          * then go off-channel again.  All during this time
 376                          * we notify the ap we're in power save mode.  When
 377                          * the scan is complete we leave power save mode.
 378                          * If any beacon indicates there are frames pending
 379                          * for us then we drop out of power save mode
 380                          * (and background scan) automatically by way of the
 381                          * usual sta power save logic.
 382                          */
 383                         ss->ss_flags |= IEEE80211_SCAN_NOPICK
 384                                      |  IEEE80211_SCAN_BGSCAN
 385                                      |  flags
 386                                      ;
 387                         /* if previous scan completed, restart */
 388                         if (ss->ss_next >= ss->ss_last) {
 389                                 if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
 390                                         vap->iv_stats.is_scan_active++;
 391                                 else
 392                                         vap->iv_stats.is_scan_passive++;
 393                                 /*
 394                                  * NB: beware of the scan cache being flushed;
 395                                  *     if the channel list is empty use the
 396                                  *     scan_start method to populate it.
 397                                  */
 398                                 ss->ss_next = 0;
 399                                 if (ss->ss_last != 0)
 400                                         ss->ss_ops->scan_restart(ss, vap);
 401                                 else {
 402                                         ss->ss_ops->scan_start(ss, vap);
 403 #ifdef IEEE80211_DEBUG
 404                                         if (ieee80211_msg_scan(vap))
 405                                                 ieee80211_scan_dump(ss);
 406 #endif /* IEEE80211_DEBUG */
 407                                 }
 408                         }
 409                         ieee80211_swscan_set_scan_duration(vap, duration);
 410                         ss->ss_maxdwell = duration;
 411                         ic->ic_flags |= IEEE80211_F_SCAN;
 412                         ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
 413                         ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
 414                 } else {
 415                         /* XXX msg+stat */
 416                 }
 417         } else {
 418                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 419                     "%s: %s scan already in progress\n", __func__,
 420                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
 421         }
 422         IEEE80211_UNLOCK(ic);
 423
 424         /* NB: racey, does it matter? */
 425         return (ic->ic_flags & IEEE80211_F_SCAN);
 426 }
 427
 428 /*
 429  * Cancel any scan currently going on for the specified vap.
 430  */
 431 static void
 432 ieee80211_swscan_cancel_scan(struct ieee80211vap *vap)
 433 {
 434         struct ieee80211com *ic = vap->iv_ic;
 435         struct ieee80211_scan_state *ss = ic->ic_scan;
 436
 437         IEEE80211_LOCK(ic);
 438         if ((ic->ic_flags & IEEE80211_F_SCAN) &&
 439             ss->ss_vap == vap &&
 440             (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0) {
 441                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 442                     "%s: cancel %s scan\n", __func__,
 443                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ?
 444                         "active" : "passive");
 445
 446                 /* clear bg scan NOPICK and mark cancel request */
 447                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 448                 SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_CANCEL;
 449                 /* wake up the scan task */
 450                 scan_signal(ss);
 451         } else {
 452                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 453                     "%s: called; F_SCAN=%d, vap=%s, CANCEL=%d\n",
 454                         __func__,
 455                         !! (ic->ic_flags & IEEE80211_F_SCAN),
 456                         (ss->ss_vap == vap ? "match" : "nomatch"),
 457                         !! (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL));
 458         }
 459         IEEE80211_UNLOCK(ic);
 460 }
 461
 462 /*
 463  * Cancel any scan currently going on.
 464  */
 465 static void
 466 ieee80211_swscan_cancel_anyscan(struct ieee80211vap *vap)
 467 {
 468         struct ieee80211com *ic = vap->iv_ic;
 469         struct ieee80211_scan_state *ss = ic->ic_scan;
 470
 471         IEEE80211_LOCK(ic);
 472         if ((ic->ic_flags & IEEE80211_F_SCAN) &&
 473             (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0) {
 474                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 475                     "%s: cancel %s scan\n", __func__,
 476                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ?
 477                         "active" : "passive");
 478
 479                 /* clear bg scan NOPICK and mark cancel request */
 480                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 481                 SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_CANCEL;
 482                 /* wake up the scan task */
 483                 scan_signal(ss);
 484         } else {
 485                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 486                     "%s: called; F_SCAN=%d, vap=%s, CANCEL=%d\n",
 487                         __func__,
 488                         !! (ic->ic_flags & IEEE80211_F_SCAN),
 489                         (ss->ss_vap == vap ? "match" : "nomatch"),
 490                         !! (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL));
 491         }
 492         IEEE80211_UNLOCK(ic);
 493 }
 494
 495 /*
 496  * Public access to scan_next for drivers that manage
 497  * scanning themselves (e.g. for firmware-based devices).
 498  */
 499 static void
 500 ieee80211_swscan_scan_next(struct ieee80211vap *vap)
 501 {
 502         struct ieee80211com *ic = vap->iv_ic;
 503         struct ieee80211_scan_state *ss = ic->ic_scan;
 504
 505         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN, "%s: called\n", __func__);
 506
 507         /* wake up the scan task */
 508         IEEE80211_LOCK(ic);
 509         scan_signal(ss);
 510         IEEE80211_UNLOCK(ic);
 511 }
 512
 513 /*
 514  * Public access to scan_next for drivers that are not able to scan single
 515  * channels (e.g. for firmware-based devices).
 516  */
 517 static void
 518 ieee80211_swscan_scan_done(struct ieee80211vap *vap)
 519 {
 520         struct ieee80211com *ic = vap->iv_ic;
 521         struct ieee80211_scan_state *ss;
 522
 523         IEEE80211_LOCK_ASSERT(ic);
 524
 525         ss = ic->ic_scan;
 526         scan_signal(ss);
 527 }
 528
 529 /*
 530  * Probe the curent channel, if allowed, while scanning.
 531  * If the channel is not marked passive-only then send
 532  * a probe request immediately.  Otherwise mark state and
 533  * listen for beacons on the channel; if we receive something
 534  * then we'll transmit a probe request.
 535  */
 536 static void
 537 ieee80211_swscan_probe_curchan(struct ieee80211vap *vap, int force)
 538 {
 539         struct ieee80211com *ic = vap->iv_ic;
 540         struct ieee80211_scan_state *ss = ic->ic_scan;
 541         struct ifnet *ifp = vap->iv_ifp;
 542         int i;
 543
 544         /*
 545          * Send directed probe requests followed by any
 546          * broadcast probe request.
 547          * XXX remove dependence on ic/vap->iv_bss
 548          */
 549         for (i = 0; i < ss->ss_nssid; i++)
 550                 ieee80211_send_probereq(vap->iv_bss,
 551                         vap->iv_myaddr, ifp->if_broadcastaddr,
 552                         ifp->if_broadcastaddr,
 553                         ss->ss_ssid[i].ssid, ss->ss_ssid[i].len);
 554         if ((ss->ss_flags & IEEE80211_SCAN_NOBCAST) == 0)
 555                 ieee80211_send_probereq(vap->iv_bss,
 556                         vap->iv_myaddr, ifp->if_broadcastaddr,
 557                         ifp->if_broadcastaddr,
 558                         "", 0);
 559 }
 560
 561 /*
 562  * Scan curchan.  If this is an active scan and the channel
 563  * is not marked passive then send probe request frame(s).
 564  * Arrange for the channel change after maxdwell ticks.
 565  */
 566 static void
 567 scan_curchan(struct ieee80211_scan_state *ss, unsigned long maxdwell)
 568 {
 569         struct ieee80211vap *vap  = ss->ss_vap;
 570
 571         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 572             "%s: calling; maxdwell=%lu\n",
 573             __func__,
 574             maxdwell);
 575         IEEE80211_LOCK(vap->iv_ic);
 576         if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
 577                 ieee80211_probe_curchan(vap, 0);
 578         callout_reset(&SCAN_PRIVATE(ss)->ss_scan_timer,
 579             maxdwell, scan_signal, ss);
 580         IEEE80211_UNLOCK(vap->iv_ic);
 581 }
 582
 583 static void
 584 scan_signal(void *arg)
 585 {
 586         struct ieee80211_scan_state *ss = (struct ieee80211_scan_state *) arg;
 587
 588         IEEE80211_LOCK_ASSERT(ss->ss_ic);
 589         cv_signal(&SCAN_PRIVATE(ss)->ss_scan_cv);
 590 }
 591
 592 /*
 593  * Handle mindwell requirements completed; initiate a channel
 594  * change to the next channel asap.
 595  */
 596 static void
 597 scan_mindwell(struct ieee80211_scan_state *ss)
 598 {
 599         struct ieee80211com *ic = ss->ss_ic;
 600
 601         IEEE80211_DPRINTF(ss->ss_vap, IEEE80211_MSG_SCAN, "%s: called\n", __func__);
 602
 603         IEEE80211_LOCK(ic);
 604         scan_signal(ss);
 605         IEEE80211_UNLOCK(ic);
 606 }
 607
 608 static void
 609 scan_task(void *arg, int pending)
 610 {
 611 #define ISCAN_REP       (ISCAN_MINDWELL | ISCAN_DISCARD)
 612         struct ieee80211_scan_state *ss = (struct ieee80211_scan_state *) arg;
 613         struct ieee80211vap *vap = ss->ss_vap;
 614         struct ieee80211com *ic = ss->ss_ic;
 615         struct ieee80211_channel *chan;
 616         unsigned long maxdwell, scanend;
 617         int scandone = 0;
 618
 619         IEEE80211_LOCK(ic);
 620         if (vap == NULL || (ic->ic_flags & IEEE80211_F_SCAN) == 0 ||
 621             (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)) {
 622                 /* Cancelled before we started */
 623                 goto done;
 624         }
 625
 626         if (ss->ss_next == ss->ss_last) {
 627                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 628                         "%s: no channels to scan\n", __func__);
 629                 scandone = 1;
 630                 goto done;
 631         }
 632
 633         if (vap->iv_opmode == IEEE80211_M_STA &&
 634             vap->iv_state == IEEE80211_S_RUN) {
 635                 if ((vap->iv_bss->ni_flags & IEEE80211_NODE_PWR_MGT) == 0) {
 636                         /* Enable station power save mode */
 637                         vap->iv_sta_ps(vap, 1);
 638                         /*
 639                          * Use an 1ms delay so the null data frame has a chance
 640                          * to go out.
 641                          * XXX Should use M_TXCB mechanism to eliminate this.
 642                          */
 643                         cv_timedwait(&SCAN_PRIVATE(ss)->ss_scan_cv,
 644                             IEEE80211_LOCK_OBJ(ic), hz / 1000);
 645                         if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)
 646                                 goto done;
 647                 }
 648         }
 649
 650         scanend = ticks + SCAN_PRIVATE(ss)->ss_duration;
 651
 652         /* XXX scan state can change! Re-validate scan state! */
 653
 654         IEEE80211_UNLOCK(ic);
 655         ic->ic_scan_start(ic);          /* notify driver */
 656         IEEE80211_LOCK(ic);
 657
 658         for (;;) {
 659
 660                 scandone = (ss->ss_next >= ss->ss_last) ||
 661                     (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0;
 662
 663                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 664                     "%s: loop start; scandone=%d\n",
 665                     __func__,
 666                     scandone);
 667
 668                 if (scandone || (ss->ss_flags & IEEE80211_SCAN_GOTPICK) ||
 669                     (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT) ||
 670                      time_after(ticks + ss->ss_mindwell, scanend))
 671                         break;
 672
 673                 chan = ss->ss_chans[ss->ss_next++];
 674
 675                 /*
 676                  * Watch for truncation due to the scan end time.
 677                  */
 678                 if (time_after(ticks + ss->ss_maxdwell, scanend))
 679                         maxdwell = scanend - ticks;
 680                 else
 681                         maxdwell = ss->ss_maxdwell;
 682
 683                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 684                     "%s: chan %3d%c -> %3d%c [%s, dwell min %lums max %lums]\n",
 685                     __func__,
 686                     ieee80211_chan2ieee(ic, ic->ic_curchan),
 687                     ieee80211_channel_type_char(ic->ic_curchan),
 688                     ieee80211_chan2ieee(ic, chan),
 689                     ieee80211_channel_type_char(chan),
 690                     (ss->ss_flags & IEEE80211_SCAN_ACTIVE) &&
 691                         (chan->ic_flags & IEEE80211_CHAN_PASSIVE) == 0 ?
 692                         "active" : "passive",
 693                     ticks_to_msecs(ss->ss_mindwell), ticks_to_msecs(maxdwell));
 694
 695                 /*
 696                  * Potentially change channel and phy mode.
 697                  */
 698                 ic->ic_curchan = chan;
 699                 ic->ic_rt = ieee80211_get_ratetable(chan);
 700                 IEEE80211_UNLOCK(ic);
 701                 /*
 702                  * Perform the channel change and scan unlocked so the driver
 703                  * may sleep. Once set_channel returns the hardware has
 704                  * completed the channel change.
 705                  */
 706                 ic->ic_set_channel(ic);
 707                 ieee80211_radiotap_chan_change(ic);
 708
 709                 /*
 710                  * Scan curchan.  Drivers for "intelligent hardware"
 711                  * override ic_scan_curchan to tell the device to do
 712                  * the work.  Otherwise we manage the work outselves;
 713                  * sending a probe request (as needed), and arming the
 714                  * timeout to switch channels after maxdwell ticks.
 715                  *
 716                  * scan_curchan should only pause for the time required to
 717                  * prepare/initiate the hardware for the scan (if at all), the
 718                  * below condvar is used to sleep for the channels dwell time
 719                  * and allows it to be signalled for abort.
 720                  */
 721                 ic->ic_scan_curchan(ss, maxdwell);
 722                 IEEE80211_LOCK(ic);
 723
 724                 /* XXX scan state can change! Re-validate scan state! */
 725
 726                 SCAN_PRIVATE(ss)->ss_chanmindwell = ticks + ss->ss_mindwell;
 727                 /* clear mindwell lock and initial channel change flush */
 728                 SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
 729
 730                 if ((SCAN_PRIVATE(ss)->ss_iflags & (ISCAN_CANCEL|ISCAN_ABORT)))
 731                         continue;
 732
 733                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN, "%s: waiting\n", __func__);
 734                 /* Wait to be signalled to scan the next channel */
 735                 cv_wait(&SCAN_PRIVATE(ss)->ss_scan_cv, IEEE80211_LOCK_OBJ(ic));
 736         }
 737
 738         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN, "%s: out\n", __func__);
 739
 740         if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)
 741                 goto done;
 742
 743         IEEE80211_UNLOCK(ic);
 744         ic->ic_scan_end(ic);            /* notify driver */
 745         IEEE80211_LOCK(ic);
 746         /* XXX scan state can change! Re-validate scan state! */
 747
 748         /*
 749          * Since a cancellation may have occured during one of the
 750          * driver calls (whilst unlocked), update scandone.
 751          */
 752         if (scandone == 0 &&
 753             ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0)) {
 754                 /* XXX printf? */
 755                 if_printf(vap->iv_ifp,
 756                     "%s: OOPS! scan cancelled during driver call (1)!\n",
 757                     __func__);
 758                 scandone = 1;
 759         }
 760
 761         /*
 762          * Record scan complete time.  Note that we also do
 763          * this when canceled so any background scan will
 764          * not be restarted for a while.
 765          */
 766         if (scandone)
 767                 ic->ic_lastscan = ticks;
 768         /* return to the bss channel */
 769         if (ic->ic_bsschan != IEEE80211_CHAN_ANYC &&
 770             ic->ic_curchan != ic->ic_bsschan) {
 771                 ieee80211_setupcurchan(ic, ic->ic_bsschan);
 772                 IEEE80211_UNLOCK(ic);
 773                 ic->ic_set_channel(ic);
 774                 ieee80211_radiotap_chan_change(ic);
 775                 IEEE80211_LOCK(ic);
 776         }
 777         /* clear internal flags and any indication of a pick */
 778         SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
 779         ss->ss_flags &= ~IEEE80211_SCAN_GOTPICK;
 780
 781         /*
 782          * If not canceled and scan completed, do post-processing.
 783          * If the callback function returns 0, then it wants to
 784          * continue/restart scanning.  Unfortunately we needed to
 785          * notify the driver to end the scan above to avoid having
 786          * rx frames alter the scan candidate list.
 787          */
 788         if ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0 &&
 789             !ss->ss_ops->scan_end(ss, vap) &&
 790             (ss->ss_flags & IEEE80211_SCAN_ONCE) == 0 &&
 791             time_before(ticks + ss->ss_mindwell, scanend)) {
 792                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 793                     "%s: done, restart "
 794                     "[ticks %u, dwell min %lu scanend %lu]\n",
 795                     __func__,
 796                     ticks, ss->ss_mindwell, scanend);
 797                 ss->ss_next = 0;        /* reset to begining */
 798                 if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
 799                         vap->iv_stats.is_scan_active++;
 800                 else
 801                         vap->iv_stats.is_scan_passive++;
 802
 803                 ss->ss_ops->scan_restart(ss, vap);      /* XXX? */
 804                 ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
 805                 IEEE80211_UNLOCK(ic);
 806                 return;
 807         }
 808
 809         /* past here, scandone is ``true'' if not in bg mode */
 810         if ((ss->ss_flags & IEEE80211_SCAN_BGSCAN) == 0)
 811                 scandone = 1;
 812
 813         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 814             "%s: %s, [ticks %u, dwell min %lu scanend %lu]\n",
 815             __func__, scandone ? "done" : "stopped",
 816             ticks, ss->ss_mindwell, scanend);
 817
 818         /*
 819          * Since a cancellation may have occured during one of the
 820          * driver calls (whilst unlocked), update scandone.
 821          */
 822         if (scandone == 0 &&
 823             ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0)) {
 824                 /* XXX printf? */
 825                 if_printf(vap->iv_ifp,
 826                     "%s: OOPS! scan cancelled during driver call (2)!\n",
 827                     __func__);
 828                 scandone = 1;
 829         }
 830
 831         /*
 832          * Clear the SCAN bit first in case frames are
 833          * pending on the station power save queue.  If
 834          * we defer this then the dispatch of the frames
 835          * may generate a request to cancel scanning.
 836          */
 837 done:
 838         ic->ic_flags &= ~IEEE80211_F_SCAN;
 839         /*
 840          * Drop out of power save mode when a scan has
 841          * completed.  If this scan was prematurely terminated
 842          * because it is a background scan then don't notify
 843          * the ap; we'll either return to scanning after we
 844          * receive the beacon frame or we'll drop out of power
 845          * save mode because the beacon indicates we have frames
 846          * waiting for us.
 847          */
 848         if (scandone) {
 849                 vap->iv_sta_ps(vap, 0);
 850                 if (ss->ss_next >= ss->ss_last) {
 851                         ieee80211_notify_scan_done(vap);
 852                         ic->ic_flags_ext &= ~IEEE80211_FEXT_BGSCAN;
 853                 }
 854         }
 855         SCAN_PRIVATE(ss)->ss_iflags &= ~(ISCAN_CANCEL|ISCAN_ABORT);
 856         ss->ss_flags &= ~(IEEE80211_SCAN_ONCE | IEEE80211_SCAN_PICK1ST);
 857         IEEE80211_UNLOCK(ic);
 858 #undef ISCAN_REP
 859 }
 860
 861 /*
 862  * Process a beacon or probe response frame.
 863  */
 864 static void
 865 ieee80211_swscan_add_scan(struct ieee80211vap *vap,
 866         struct ieee80211_channel *curchan,
 867         const struct ieee80211_scanparams *sp,
 868         const struct ieee80211_frame *wh,
 869         int subtype, int rssi, int noise)
 870 {
 871         struct ieee80211com *ic = vap->iv_ic;
 872         struct ieee80211_scan_state *ss = ic->ic_scan;
 873
 874         /* XXX locking */
 875         /*
 876          * Frames received during startup are discarded to avoid
 877          * using scan state setup on the initial entry to the timer
 878          * callback.  This can occur because the device may enable
 879          * rx prior to our doing the initial channel change in the
 880          * timer routine.
 881          */
 882         if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_DISCARD)
 883                 return;
 884 #ifdef IEEE80211_DEBUG
 885         if (ieee80211_msg_scan(vap) && (ic->ic_flags & IEEE80211_F_SCAN))
 886                 ieee80211_scan_dump_probe_beacon(subtype, 1, wh->i_addr2, sp, rssi);
 887 #endif
 888         if (ss->ss_ops != NULL &&
 889             ss->ss_ops->scan_add(ss, curchan, sp, wh, subtype, rssi, noise)) {
 890                 /*
 891                  * If we've reached the min dwell time terminate
 892                  * the timer so we'll switch to the next channel.
 893                  */
 894                 if ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_MINDWELL) == 0 &&
 895                     time_after_eq(ticks, SCAN_PRIVATE(ss)->ss_chanmindwell)) {
 896                         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 897                             "%s: chan %3d%c min dwell met (%u > %lu)\n",
 898                             __func__,
 899                             ieee80211_chan2ieee(ic, ic->ic_curchan),
 900                             ieee80211_channel_type_char(ic->ic_curchan),
 901                             ticks, SCAN_PRIVATE(ss)->ss_chanmindwell);
 902                         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_MINDWELL;
 903                         /*
 904                          * NB: trigger at next clock tick or wait for the
 905                          * hardware.
 906                          */
 907                         ic->ic_scan_mindwell(ss);
 908                 }
 909         }
 910 }
 911
 912 static struct ieee80211_scan_methods swscan_methods = {
 913         .sc_attach = ieee80211_swscan_attach,
 914         .sc_detach = ieee80211_swscan_detach,
 915         .sc_vattach = ieee80211_swscan_vattach,
 916         .sc_vdetach = ieee80211_swscan_vdetach,
 917         .sc_set_scan_duration = ieee80211_swscan_set_scan_duration,
 918         .sc_start_scan = ieee80211_swscan_start_scan,
 919         .sc_check_scan = ieee80211_swscan_check_scan,
 920         .sc_bg_scan = ieee80211_swscan_bg_scan,
 921         .sc_cancel_scan = ieee80211_swscan_cancel_scan,
 922         .sc_cancel_anyscan = ieee80211_swscan_cancel_anyscan,
 923         .sc_scan_next = ieee80211_swscan_scan_next,
 924         .sc_scan_done = ieee80211_swscan_scan_done,
 925         .sc_scan_probe_curchan = ieee80211_swscan_probe_curchan,
 926         .sc_add_scan = ieee80211_swscan_add_scan
 927 };
 928
 929 /*
 930  * Default scan attach method.
 931  */
 932 void
 933 ieee80211_swscan_attach(struct ieee80211com *ic)
 934 {
 935         struct scan_state *ss;
 936
 937         /*
 938          * Setup the default methods
 939          */
 940         ic->ic_scan_methods = &swscan_methods;
 941
 942         /* Allocate initial scan state */
 943         ss = (struct scan_state *) IEEE80211_MALLOC(sizeof(struct scan_state),
 944                 M_80211_SCAN, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
 945         if (ss == NULL) {
 946                 ic->ic_scan = NULL;
 947                 return;
 948         }
 949         callout_init_mtx(&ss->ss_scan_timer, IEEE80211_LOCK_OBJ(ic), 0);
 950         cv_init(&ss->ss_scan_cv, "scan");
 951         TASK_INIT(&ss->ss_scan_task, 0, scan_task, ss);
 952
 953         ic->ic_scan = &ss->base;
 954         ss->base.ss_ic = ic;
 955
 956         ic->ic_scan_curchan = scan_curchan;
 957         ic->ic_scan_mindwell = scan_mindwell;
 958 }