The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/net80211/ieee80211_scan.c

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    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: releng/10.0/sys/net80211/ieee80211_scan.c 259185 2013-12-10 19:14:19Z gavin $");
   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_media.h>
   44 #include <net/ethernet.h>
   45 
   46 #include <net80211/ieee80211_var.h>
   47 
   48 #include <net/bpf.h>
   49 
   50 struct scan_state {
   51         struct ieee80211_scan_state base;       /* public state */
   52 
   53         u_int           ss_iflags;              /* flags used internally */
   54 #define ISCAN_MINDWELL  0x0001          /* min dwell time reached */
   55 #define ISCAN_DISCARD   0x0002          /* discard rx'd frames */
   56 #define ISCAN_CANCEL    0x0004          /* cancel current scan */
   57 #define ISCAN_ABORT     0x0008          /* end the scan immediately */
   58         unsigned long   ss_chanmindwell;        /* min dwell on curchan */
   59         unsigned long   ss_scanend;             /* time scan must stop */
   60         u_int           ss_duration;            /* duration for next scan */
   61         struct task     ss_scan_task;           /* scan execution */
   62         struct cv       ss_scan_cv;             /* scan signal */
   63         struct callout  ss_scan_timer;          /* scan timer */
   64 };
   65 #define SCAN_PRIVATE(ss)        ((struct scan_state *) ss)
   66 
   67 /*
   68  * Amount of time to go off-channel during a background
   69  * scan.  This value should be large enough to catch most
   70  * ap's but short enough that we can return on-channel
   71  * before our listen interval expires.
   72  *
   73  * XXX tunable
   74  * XXX check against configured listen interval
   75  */
   76 #define IEEE80211_SCAN_OFFCHANNEL       msecs_to_ticks(150)
   77 
   78 /*
   79  * Roaming-related defaults.  RSSI thresholds are as returned by the
   80  * driver (.5dBm).  Transmit rate thresholds are IEEE rate codes (i.e
   81  * .5M units) or MCS.
   82  */
   83 /* rssi thresholds */
   84 #define ROAM_RSSI_11A_DEFAULT           14      /* 11a bss */
   85 #define ROAM_RSSI_11B_DEFAULT           14      /* 11b bss */
   86 #define ROAM_RSSI_11BONLY_DEFAULT       14      /* 11b-only bss */
   87 /* transmit rate thresholds */
   88 #define ROAM_RATE_11A_DEFAULT           2*12    /* 11a bss */
   89 #define ROAM_RATE_11B_DEFAULT           2*5     /* 11b bss */
   90 #define ROAM_RATE_11BONLY_DEFAULT       2*1     /* 11b-only bss */
   91 #define ROAM_RATE_HALF_DEFAULT          2*6     /* half-width 11a/g bss */
   92 #define ROAM_RATE_QUARTER_DEFAULT       2*3     /* quarter-width 11a/g bss */
   93 #define ROAM_MCS_11N_DEFAULT            (1 | IEEE80211_RATE_MCS) /* 11n bss */
   94 
   95 static  void scan_curchan(struct ieee80211_scan_state *, unsigned long);
   96 static  void scan_mindwell(struct ieee80211_scan_state *);
   97 static  void scan_signal(void *);
   98 static  void scan_task(void *, int);
   99 
  100 MALLOC_DEFINE(M_80211_SCAN, "80211scan", "802.11 scan state");
  101 
  102 void
  103 ieee80211_scan_attach(struct ieee80211com *ic)
  104 {
  105         struct scan_state *ss;
  106 
  107         ss = (struct scan_state *) malloc(sizeof(struct scan_state),
  108                 M_80211_SCAN, M_NOWAIT | M_ZERO);
  109         if (ss == NULL) {
  110                 ic->ic_scan = NULL;
  111                 return;
  112         }
  113         callout_init_mtx(&ss->ss_scan_timer, IEEE80211_LOCK_OBJ(ic), 0);
  114         cv_init(&ss->ss_scan_cv, "scan");
  115         TASK_INIT(&ss->ss_scan_task, 0, scan_task, ss);
  116         ic->ic_scan = &ss->base;
  117         ss->base.ss_ic = ic;
  118 
  119         ic->ic_scan_curchan = scan_curchan;
  120         ic->ic_scan_mindwell = scan_mindwell;
  121 }
  122 
  123 void
  124 ieee80211_scan_detach(struct ieee80211com *ic)
  125 {
  126         struct ieee80211_scan_state *ss = ic->ic_scan;
  127 
  128         if (ss != NULL) {
  129                 IEEE80211_LOCK(ic);
  130                 SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_ABORT;
  131                 scan_signal(ss);
  132                 IEEE80211_UNLOCK(ic);
  133                 ieee80211_draintask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
  134                 callout_drain(&SCAN_PRIVATE(ss)->ss_scan_timer);
  135                 KASSERT((ic->ic_flags & IEEE80211_F_SCAN) == 0,
  136                     ("scan still running"));
  137                 if (ss->ss_ops != NULL) {
  138                         ss->ss_ops->scan_detach(ss);
  139                         ss->ss_ops = NULL;
  140                 }
  141                 ic->ic_scan = NULL;
  142                 free(SCAN_PRIVATE(ss), M_80211_SCAN);
  143         }
  144 }
  145 
  146 static const struct ieee80211_roamparam defroam[IEEE80211_MODE_MAX] = {
  147         [IEEE80211_MODE_11A]    = { .rssi = ROAM_RSSI_11A_DEFAULT,
  148                                     .rate = ROAM_RATE_11A_DEFAULT },
  149         [IEEE80211_MODE_11G]    = { .rssi = ROAM_RSSI_11B_DEFAULT,
  150                                     .rate = ROAM_RATE_11B_DEFAULT },
  151         [IEEE80211_MODE_11B]    = { .rssi = ROAM_RSSI_11BONLY_DEFAULT,
  152                                     .rate = ROAM_RATE_11BONLY_DEFAULT },
  153         [IEEE80211_MODE_TURBO_A]= { .rssi = ROAM_RSSI_11A_DEFAULT,
  154                                     .rate = ROAM_RATE_11A_DEFAULT },
  155         [IEEE80211_MODE_TURBO_G]= { .rssi = ROAM_RSSI_11A_DEFAULT,
  156                                     .rate = ROAM_RATE_11A_DEFAULT },
  157         [IEEE80211_MODE_STURBO_A]={ .rssi = ROAM_RSSI_11A_DEFAULT,
  158                                     .rate = ROAM_RATE_11A_DEFAULT },
  159         [IEEE80211_MODE_HALF]   = { .rssi = ROAM_RSSI_11A_DEFAULT,
  160                                     .rate = ROAM_RATE_HALF_DEFAULT },
  161         [IEEE80211_MODE_QUARTER]= { .rssi = ROAM_RSSI_11A_DEFAULT,
  162                                     .rate = ROAM_RATE_QUARTER_DEFAULT },
  163         [IEEE80211_MODE_11NA]   = { .rssi = ROAM_RSSI_11A_DEFAULT,
  164                                     .rate = ROAM_MCS_11N_DEFAULT },
  165         [IEEE80211_MODE_11NG]   = { .rssi = ROAM_RSSI_11B_DEFAULT,
  166                                     .rate = ROAM_MCS_11N_DEFAULT },
  167 };
  168 
  169 void
  170 ieee80211_scan_vattach(struct ieee80211vap *vap)
  171 {
  172         vap->iv_bgscanidle = (IEEE80211_BGSCAN_IDLE_DEFAULT*1000)/hz;
  173         vap->iv_bgscanintvl = IEEE80211_BGSCAN_INTVAL_DEFAULT*hz;
  174         vap->iv_scanvalid = IEEE80211_SCAN_VALID_DEFAULT*hz;
  175 
  176         vap->iv_roaming = IEEE80211_ROAMING_AUTO;
  177         memcpy(vap->iv_roamparms, defroam, sizeof(defroam));
  178 }
  179 
  180 void
  181 ieee80211_scan_vdetach(struct ieee80211vap *vap)
  182 {
  183         struct ieee80211com *ic = vap->iv_ic;
  184         struct ieee80211_scan_state *ss;
  185 
  186         IEEE80211_LOCK(ic);
  187         ss = ic->ic_scan;
  188         if (ss != NULL && ss->ss_vap == vap) {
  189                 if (ic->ic_flags & IEEE80211_F_SCAN) {
  190                         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_ABORT;
  191                         scan_signal(ss);
  192                 }
  193                 if (ss->ss_ops != NULL) {
  194                         ss->ss_ops->scan_detach(ss);
  195                         ss->ss_ops = NULL;
  196                 }
  197                 ss->ss_vap = NULL;
  198         }
  199         IEEE80211_UNLOCK(ic);
  200 }
  201 
  202 /*
  203  * Simple-minded scanner module support.
  204  */
  205 static const char *scan_modnames[IEEE80211_OPMODE_MAX] = {
  206         "wlan_scan_sta",        /* IEEE80211_M_IBSS */
  207         "wlan_scan_sta",        /* IEEE80211_M_STA */
  208         "wlan_scan_wds",        /* IEEE80211_M_WDS */
  209         "wlan_scan_sta",        /* IEEE80211_M_AHDEMO */
  210         "wlan_scan_ap",         /* IEEE80211_M_HOSTAP */
  211         "wlan_scan_monitor",    /* IEEE80211_M_MONITOR */
  212         "wlan_scan_sta",        /* IEEE80211_M_MBSS */
  213 };
  214 static const struct ieee80211_scanner *scanners[IEEE80211_OPMODE_MAX];
  215 
  216 const struct ieee80211_scanner *
  217 ieee80211_scanner_get(enum ieee80211_opmode mode)
  218 {
  219         if (mode >= IEEE80211_OPMODE_MAX)
  220                 return NULL;
  221         if (scanners[mode] == NULL)
  222                 ieee80211_load_module(scan_modnames[mode]);
  223         return scanners[mode];
  224 }
  225 
  226 void
  227 ieee80211_scanner_register(enum ieee80211_opmode mode,
  228         const struct ieee80211_scanner *scan)
  229 {
  230         if (mode >= IEEE80211_OPMODE_MAX)
  231                 return;
  232         scanners[mode] = scan;
  233 }
  234 
  235 void
  236 ieee80211_scanner_unregister(enum ieee80211_opmode mode,
  237         const struct ieee80211_scanner *scan)
  238 {
  239         if (mode >= IEEE80211_OPMODE_MAX)
  240                 return;
  241         if (scanners[mode] == scan)
  242                 scanners[mode] = NULL;
  243 }
  244 
  245 void
  246 ieee80211_scanner_unregister_all(const struct ieee80211_scanner *scan)
  247 {
  248         int m;
  249 
  250         for (m = 0; m < IEEE80211_OPMODE_MAX; m++)
  251                 if (scanners[m] == scan)
  252                         scanners[m] = NULL;
  253 }
  254 
  255 /*
  256  * Update common scanner state to reflect the current
  257  * operating mode.  This is called when the state machine
  258  * is transitioned to RUN state w/o scanning--e.g. when
  259  * operating in monitor mode.  The purpose of this is to
  260  * ensure later callbacks find ss_ops set to properly
  261  * reflect current operating mode.
  262  */
  263 static void
  264 scan_update_locked(struct ieee80211vap *vap,
  265         const struct ieee80211_scanner *scan)
  266 {
  267         struct ieee80211com *ic = vap->iv_ic;
  268         struct ieee80211_scan_state *ss = ic->ic_scan;
  269 
  270         IEEE80211_LOCK_ASSERT(ic);
  271 
  272 #ifdef IEEE80211_DEBUG
  273         if (ss->ss_vap != vap || ss->ss_ops != scan) {
  274                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  275                     "%s: current scanner is <%s:%s>, switch to <%s:%s>\n",
  276                     __func__,
  277                     ss->ss_vap != NULL ?
  278                         ss->ss_vap->iv_ifp->if_xname : "none",
  279                     ss->ss_vap != NULL ?
  280                         ieee80211_opmode_name[ss->ss_vap->iv_opmode] : "none",
  281                     vap->iv_ifp->if_xname,
  282                     ieee80211_opmode_name[vap->iv_opmode]);
  283         }
  284 #endif
  285         ss->ss_vap = vap;
  286         if (ss->ss_ops != scan) {
  287                 /*
  288                  * Switch scanners; detach old, attach new.  Special
  289                  * case where a single scan module implements multiple
  290                  * policies by using different scan ops but a common
  291                  * core.  We assume if the old and new attach methods
  292                  * are identical then it's ok to just change ss_ops
  293                  * and not flush the internal state of the module.
  294                  */
  295                 if (scan == NULL || ss->ss_ops == NULL ||
  296                     ss->ss_ops->scan_attach != scan->scan_attach) {
  297                         if (ss->ss_ops != NULL)
  298                                 ss->ss_ops->scan_detach(ss);
  299                         if (scan != NULL && !scan->scan_attach(ss)) {
  300                                 /* XXX attach failure */
  301                                 /* XXX stat+msg */
  302                                 scan = NULL;
  303                         }
  304                 }
  305                 ss->ss_ops = scan;
  306         }
  307 }
  308 
  309 static char
  310 channel_type(const struct ieee80211_channel *c)
  311 {
  312         if (IEEE80211_IS_CHAN_ST(c))
  313                 return 'S';
  314         if (IEEE80211_IS_CHAN_108A(c))
  315                 return 'T';
  316         if (IEEE80211_IS_CHAN_108G(c))
  317                 return 'G';
  318         if (IEEE80211_IS_CHAN_HT(c))
  319                 return 'n';
  320         if (IEEE80211_IS_CHAN_A(c))
  321                 return 'a';
  322         if (IEEE80211_IS_CHAN_ANYG(c))
  323                 return 'g';
  324         if (IEEE80211_IS_CHAN_B(c))
  325                 return 'b';
  326         return 'f';
  327 }
  328 
  329 void
  330 ieee80211_scan_dump_channels(const struct ieee80211_scan_state *ss)
  331 {
  332         struct ieee80211com *ic = ss->ss_ic;
  333         const char *sep;
  334         int i;
  335 
  336         sep = "";
  337         for (i = ss->ss_next; i < ss->ss_last; i++) {
  338                 const struct ieee80211_channel *c = ss->ss_chans[i];
  339 
  340                 printf("%s%u%c", sep, ieee80211_chan2ieee(ic, c),
  341                         channel_type(c));
  342                 sep = ", ";
  343         }
  344 }
  345 
  346 #ifdef IEEE80211_DEBUG
  347 static void
  348 scan_dump(struct ieee80211_scan_state *ss)
  349 {
  350         struct ieee80211vap *vap = ss->ss_vap;
  351 
  352         if_printf(vap->iv_ifp, "scan set ");
  353         ieee80211_scan_dump_channels(ss);
  354         printf(" dwell min %lums max %lums\n",
  355             ticks_to_msecs(ss->ss_mindwell), ticks_to_msecs(ss->ss_maxdwell));
  356 }
  357 #endif /* IEEE80211_DEBUG */
  358 
  359 static void
  360 copy_ssid(struct ieee80211vap *vap, struct ieee80211_scan_state *ss,
  361         int nssid, const struct ieee80211_scan_ssid ssids[])
  362 {
  363         if (nssid > IEEE80211_SCAN_MAX_SSID) {
  364                 /* XXX printf */
  365                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  366                     "%s: too many ssid %d, ignoring all of them\n",
  367                     __func__, nssid);
  368                 return;
  369         }
  370         memcpy(ss->ss_ssid, ssids, nssid * sizeof(ssids[0]));
  371         ss->ss_nssid = nssid;
  372 }
  373 
  374 /*
  375  * Start a scan unless one is already going.
  376  */
  377 static int
  378 start_scan_locked(const struct ieee80211_scanner *scan,
  379         struct ieee80211vap *vap, int flags, u_int duration,
  380         u_int mindwell, u_int maxdwell,
  381         u_int nssid, const struct ieee80211_scan_ssid ssids[])
  382 {
  383         struct ieee80211com *ic = vap->iv_ic;
  384         struct ieee80211_scan_state *ss = ic->ic_scan;
  385 
  386         IEEE80211_LOCK_ASSERT(ic);
  387 
  388         if (ic->ic_flags & IEEE80211_F_CSAPENDING) {
  389                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  390                     "%s: scan inhibited by pending channel change\n", __func__);
  391         } else if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
  392                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  393                     "%s: %s scan, duration %u mindwell %u maxdwell %u, desired mode %s, %s%s%s%s%s%s\n"
  394                     , __func__
  395                     , flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive"
  396                     , duration, mindwell, maxdwell
  397                     , ieee80211_phymode_name[vap->iv_des_mode]
  398                     , flags & IEEE80211_SCAN_FLUSH ? "flush" : "append"
  399                     , flags & IEEE80211_SCAN_NOPICK ? ", nopick" : ""
  400                     , flags & IEEE80211_SCAN_NOJOIN ? ", nojoin" : ""
  401                     , flags & IEEE80211_SCAN_NOBCAST ? ", nobcast" : ""
  402                     , flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : ""
  403                     , flags & IEEE80211_SCAN_ONCE ? ", once" : ""
  404                 );
  405 
  406                 scan_update_locked(vap, scan);
  407                 if (ss->ss_ops != NULL) {
  408                         if ((flags & IEEE80211_SCAN_NOSSID) == 0)
  409                                 copy_ssid(vap, ss, nssid, ssids);
  410 
  411                         /* NB: top 4 bits for internal use */
  412                         ss->ss_flags = flags & 0xfff;
  413                         if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
  414                                 vap->iv_stats.is_scan_active++;
  415                         else
  416                                 vap->iv_stats.is_scan_passive++;
  417                         if (flags & IEEE80211_SCAN_FLUSH)
  418                                 ss->ss_ops->scan_flush(ss);
  419                         if (flags & IEEE80211_SCAN_BGSCAN)
  420                                 ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
  421 
  422                         /* NB: flush frames rx'd before 1st channel change */
  423                         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
  424                         SCAN_PRIVATE(ss)->ss_duration = duration;
  425                         ss->ss_next = 0;
  426                         ss->ss_mindwell = mindwell;
  427                         ss->ss_maxdwell = maxdwell;
  428                         /* NB: scan_start must be before the scan runtask */
  429                         ss->ss_ops->scan_start(ss, vap);
  430 #ifdef IEEE80211_DEBUG
  431                         if (ieee80211_msg_scan(vap))
  432                                 scan_dump(ss);
  433 #endif /* IEEE80211_DEBUG */
  434                         ic->ic_flags |= IEEE80211_F_SCAN;
  435                         ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
  436                 }
  437                 return 1;
  438         } else {
  439                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  440                     "%s: %s scan already in progress\n", __func__,
  441                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
  442         }
  443         return 0;
  444 }
  445 
  446 /*
  447  * Start a scan unless one is already going.
  448  */
  449 int
  450 ieee80211_start_scan(struct ieee80211vap *vap, int flags,
  451         u_int duration, u_int mindwell, u_int maxdwell,
  452         u_int nssid, const struct ieee80211_scan_ssid ssids[])
  453 {
  454         struct ieee80211com *ic = vap->iv_ic;
  455         const struct ieee80211_scanner *scan;
  456         int result;
  457 
  458         scan = ieee80211_scanner_get(vap->iv_opmode);
  459         if (scan == NULL) {
  460                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  461                     "%s: no scanner support for %s mode\n",
  462                     __func__, ieee80211_opmode_name[vap->iv_opmode]);
  463                 /* XXX stat */
  464                 return 0;
  465         }
  466 
  467         IEEE80211_LOCK(ic);
  468         result = start_scan_locked(scan, vap, flags, duration,
  469             mindwell, maxdwell, nssid, ssids);
  470         IEEE80211_UNLOCK(ic);
  471 
  472         return result;
  473 }
  474 
  475 /*
  476  * Check the scan cache for an ap/channel to use; if that
  477  * fails then kick off a new scan.
  478  */
  479 int
  480 ieee80211_check_scan(struct ieee80211vap *vap, int flags,
  481         u_int duration, u_int mindwell, u_int maxdwell,
  482         u_int nssid, const struct ieee80211_scan_ssid ssids[])
  483 {
  484         struct ieee80211com *ic = vap->iv_ic;
  485         struct ieee80211_scan_state *ss = ic->ic_scan;
  486         const struct ieee80211_scanner *scan;
  487         int result;
  488 
  489         scan = ieee80211_scanner_get(vap->iv_opmode);
  490         if (scan == NULL) {
  491                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  492                     "%s: no scanner support for %s mode\n",
  493                     __func__, vap->iv_opmode);
  494                 /* XXX stat */
  495                 return 0;
  496         }
  497 
  498         /*
  499          * Check if there's a list of scan candidates already.
  500          * XXX want more than the ap we're currently associated with
  501          */
  502 
  503         IEEE80211_LOCK(ic);
  504         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  505             "%s: %s scan, %s%s%s%s%s\n"
  506             , __func__
  507             , flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive"
  508             , flags & IEEE80211_SCAN_FLUSH ? "flush" : "append"
  509             , flags & IEEE80211_SCAN_NOPICK ? ", nopick" : ""
  510             , flags & IEEE80211_SCAN_NOJOIN ? ", nojoin" : ""
  511             , flags & IEEE80211_SCAN_PICK1ST ? ", pick1st" : ""
  512             , flags & IEEE80211_SCAN_ONCE ? ", once" : ""
  513         );
  514 
  515         if (ss->ss_ops != scan) {
  516                 /* XXX re-use cache contents? e.g. adhoc<->sta */
  517                 flags |= IEEE80211_SCAN_FLUSH;
  518         }
  519         scan_update_locked(vap, scan);
  520         if (ss->ss_ops != NULL) {
  521                 /* XXX verify ss_ops matches vap->iv_opmode */
  522                 if ((flags & IEEE80211_SCAN_NOSSID) == 0) {
  523                         /*
  524                          * Update the ssid list and mark flags so if
  525                          * we call start_scan it doesn't duplicate work.
  526                          */
  527                         copy_ssid(vap, ss, nssid, ssids);
  528                         flags |= IEEE80211_SCAN_NOSSID;
  529                 }
  530                 if ((ic->ic_flags & IEEE80211_F_SCAN) == 0 &&
  531                     (flags & IEEE80211_SCAN_FLUSH) == 0 &&
  532                     time_before(ticks, ic->ic_lastscan + vap->iv_scanvalid)) {
  533                         /*
  534                          * We're not currently scanning and the cache is
  535                          * deemed hot enough to consult.  Lock out others
  536                          * by marking IEEE80211_F_SCAN while we decide if
  537                          * something is already in the scan cache we can
  538                          * use.  Also discard any frames that might come
  539                          * in while temporarily marked as scanning.
  540                          */
  541                         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
  542                         ic->ic_flags |= IEEE80211_F_SCAN;
  543 
  544                         /* NB: need to use supplied flags in check */
  545                         ss->ss_flags = flags & 0xff;
  546                         result = ss->ss_ops->scan_end(ss, vap);
  547 
  548                         ic->ic_flags &= ~IEEE80211_F_SCAN;
  549                         SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_DISCARD;
  550                         if (result) {
  551                                 ieee80211_notify_scan_done(vap);
  552                                 IEEE80211_UNLOCK(ic);
  553                                 return 1;
  554                         }
  555                 }
  556         }
  557         result = start_scan_locked(scan, vap, flags, duration,
  558             mindwell, maxdwell, nssid, ssids);
  559         IEEE80211_UNLOCK(ic);
  560 
  561         return result;
  562 }
  563 
  564 /*
  565  * Check the scan cache for an ap/channel to use; if that fails
  566  * then kick off a scan using the current settings.
  567  */
  568 int
  569 ieee80211_check_scan_current(struct ieee80211vap *vap)
  570 {
  571         return ieee80211_check_scan(vap,
  572             IEEE80211_SCAN_ACTIVE,
  573             IEEE80211_SCAN_FOREVER, 0, 0,
  574             vap->iv_des_nssid, vap->iv_des_ssid);
  575 }
  576 
  577 /*
  578  * Restart a previous scan.  If the previous scan completed
  579  * then we start again using the existing channel list.
  580  */
  581 int
  582 ieee80211_bg_scan(struct ieee80211vap *vap, int flags)
  583 {
  584         struct ieee80211com *ic = vap->iv_ic;
  585         struct ieee80211_scan_state *ss = ic->ic_scan;
  586         const struct ieee80211_scanner *scan;
  587 
  588         scan = ieee80211_scanner_get(vap->iv_opmode);
  589         if (scan == NULL) {
  590                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  591                     "%s: no scanner support for %s mode\n",
  592                     __func__, vap->iv_opmode);
  593                 /* XXX stat */
  594                 return 0;
  595         }
  596 
  597         IEEE80211_LOCK(ic);
  598         if ((ic->ic_flags & IEEE80211_F_SCAN) == 0) {
  599                 u_int duration;
  600                 /*
  601                  * Go off-channel for a fixed interval that is large
  602                  * enough to catch most ap's but short enough that
  603                  * we can return on-channel before our listen interval
  604                  * expires.
  605                  */
  606                 duration = IEEE80211_SCAN_OFFCHANNEL;
  607 
  608                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  609                     "%s: %s scan, ticks %u duration %lu\n", __func__,
  610                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive",
  611                     ticks, duration);
  612 
  613                 scan_update_locked(vap, scan);
  614                 if (ss->ss_ops != NULL) {
  615                         ss->ss_vap = vap;
  616                         /*
  617                          * A background scan does not select a new sta; it
  618                          * just refreshes the scan cache.  Also, indicate
  619                          * the scan logic should follow the beacon schedule:
  620                          * we go off-channel and scan for a while, then
  621                          * return to the bss channel to receive a beacon,
  622                          * then go off-channel again.  All during this time
  623                          * we notify the ap we're in power save mode.  When
  624                          * the scan is complete we leave power save mode.
  625                          * If any beacon indicates there are frames pending
  626                          * for us then we drop out of power save mode
  627                          * (and background scan) automatically by way of the
  628                          * usual sta power save logic.
  629                          */
  630                         ss->ss_flags |= IEEE80211_SCAN_NOPICK
  631                                      |  IEEE80211_SCAN_BGSCAN
  632                                      |  flags
  633                                      ;
  634                         /* if previous scan completed, restart */
  635                         if (ss->ss_next >= ss->ss_last) {
  636                                 if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
  637                                         vap->iv_stats.is_scan_active++;
  638                                 else
  639                                         vap->iv_stats.is_scan_passive++;
  640                                 /*
  641                                  * NB: beware of the scan cache being flushed;
  642                                  *     if the channel list is empty use the
  643                                  *     scan_start method to populate it.
  644                                  */
  645                                 ss->ss_next = 0;
  646                                 if (ss->ss_last != 0)
  647                                         ss->ss_ops->scan_restart(ss, vap);
  648                                 else {
  649                                         ss->ss_ops->scan_start(ss, vap);
  650 #ifdef IEEE80211_DEBUG
  651                                         if (ieee80211_msg_scan(vap))
  652                                                 scan_dump(ss);
  653 #endif /* IEEE80211_DEBUG */
  654                                 }
  655                         }
  656                         /* NB: flush frames rx'd before 1st channel change */
  657                         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_DISCARD;
  658                         SCAN_PRIVATE(ss)->ss_duration = duration;
  659                         ss->ss_maxdwell = duration;
  660                         ic->ic_flags |= IEEE80211_F_SCAN;
  661                         ic->ic_flags_ext |= IEEE80211_FEXT_BGSCAN;
  662                         ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
  663                 } else {
  664                         /* XXX msg+stat */
  665                 }
  666         } else {
  667                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  668                     "%s: %s scan already in progress\n", __func__,
  669                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ? "active" : "passive");
  670         }
  671         IEEE80211_UNLOCK(ic);
  672 
  673         /* NB: racey, does it matter? */
  674         return (ic->ic_flags & IEEE80211_F_SCAN);
  675 }
  676 
  677 /*
  678  * Cancel any scan currently going on for the specified vap.
  679  */
  680 void
  681 ieee80211_cancel_scan(struct ieee80211vap *vap)
  682 {
  683         struct ieee80211com *ic = vap->iv_ic;
  684         struct ieee80211_scan_state *ss = ic->ic_scan;
  685 
  686         IEEE80211_LOCK(ic);
  687         if ((ic->ic_flags & IEEE80211_F_SCAN) &&
  688             ss->ss_vap == vap &&
  689             (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0) {
  690                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  691                     "%s: cancel %s scan\n", __func__,
  692                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ?
  693                         "active" : "passive");
  694 
  695                 /* clear bg scan NOPICK and mark cancel request */
  696                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
  697                 SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_CANCEL;
  698                 /* wake up the scan task */
  699                 scan_signal(ss);
  700         }
  701         IEEE80211_UNLOCK(ic);
  702 }
  703 
  704 /*
  705  * Cancel any scan currently going on.
  706  */
  707 void
  708 ieee80211_cancel_anyscan(struct ieee80211vap *vap)
  709 {
  710         struct ieee80211com *ic = vap->iv_ic;
  711         struct ieee80211_scan_state *ss = ic->ic_scan;
  712 
  713         IEEE80211_LOCK(ic);
  714         if ((ic->ic_flags & IEEE80211_F_SCAN) &&
  715             (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0) {
  716                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  717                     "%s: cancel %s scan\n", __func__,
  718                     ss->ss_flags & IEEE80211_SCAN_ACTIVE ?
  719                         "active" : "passive");
  720 
  721                 /* clear bg scan NOPICK and mark cancel request */
  722                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
  723                 SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_CANCEL;
  724                 /* wake up the scan task */
  725                 scan_signal(ss);
  726         }
  727         IEEE80211_UNLOCK(ic);
  728 }
  729 
  730 /*
  731  * Public access to scan_next for drivers that manage
  732  * scanning themselves (e.g. for firmware-based devices).
  733  */
  734 void
  735 ieee80211_scan_next(struct ieee80211vap *vap)
  736 {
  737         struct ieee80211com *ic = vap->iv_ic;
  738         struct ieee80211_scan_state *ss = ic->ic_scan;
  739 
  740         /* wake up the scan task */
  741         IEEE80211_LOCK(ic);
  742         scan_signal(ss);
  743         IEEE80211_UNLOCK(ic);
  744 }
  745 
  746 /*
  747  * Public access to scan_next for drivers that are not able to scan single
  748  * channels (e.g. for firmware-based devices).
  749  */
  750 void
  751 ieee80211_scan_done(struct ieee80211vap *vap)
  752 {
  753         struct ieee80211com *ic = vap->iv_ic;
  754         struct ieee80211_scan_state *ss;
  755 
  756         IEEE80211_LOCK(ic);
  757         ss = ic->ic_scan;
  758         ss->ss_next = ss->ss_last; /* all channels are complete */
  759         scan_signal(ss);
  760         IEEE80211_UNLOCK(ic);
  761 }
  762 
  763 /*
  764  * Probe the curent channel, if allowed, while scanning.
  765  * If the channel is not marked passive-only then send
  766  * a probe request immediately.  Otherwise mark state and
  767  * listen for beacons on the channel; if we receive something
  768  * then we'll transmit a probe request.
  769  */
  770 void
  771 ieee80211_probe_curchan(struct ieee80211vap *vap, int force)
  772 {
  773         struct ieee80211com *ic = vap->iv_ic;
  774         struct ieee80211_scan_state *ss = ic->ic_scan;
  775         struct ifnet *ifp = vap->iv_ifp;
  776         int i;
  777 
  778         if ((ic->ic_curchan->ic_flags & IEEE80211_CHAN_PASSIVE) && !force) {
  779                 ic->ic_flags_ext |= IEEE80211_FEXT_PROBECHAN;
  780                 return;
  781         }
  782         /*
  783          * Send directed probe requests followed by any
  784          * broadcast probe request.
  785          * XXX remove dependence on ic/vap->iv_bss
  786          */
  787         for (i = 0; i < ss->ss_nssid; i++)
  788                 ieee80211_send_probereq(vap->iv_bss,
  789                         vap->iv_myaddr, ifp->if_broadcastaddr,
  790                         ifp->if_broadcastaddr,
  791                         ss->ss_ssid[i].ssid, ss->ss_ssid[i].len);
  792         if ((ss->ss_flags & IEEE80211_SCAN_NOBCAST) == 0)
  793                 ieee80211_send_probereq(vap->iv_bss,
  794                         vap->iv_myaddr, ifp->if_broadcastaddr,
  795                         ifp->if_broadcastaddr,
  796                         "", 0);
  797 }
  798 
  799 /*
  800  * Scan curchan.  If this is an active scan and the channel
  801  * is not marked passive then send probe request frame(s).
  802  * Arrange for the channel change after maxdwell ticks.
  803  */
  804 static void
  805 scan_curchan(struct ieee80211_scan_state *ss, unsigned long maxdwell)
  806 {
  807         struct ieee80211vap *vap  = ss->ss_vap;
  808 
  809         IEEE80211_LOCK(vap->iv_ic);
  810         if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
  811                 ieee80211_probe_curchan(vap, 0);
  812         callout_reset(&SCAN_PRIVATE(ss)->ss_scan_timer,
  813             maxdwell, scan_signal, ss);
  814         IEEE80211_UNLOCK(vap->iv_ic);
  815 }
  816 
  817 static void
  818 scan_signal(void *arg)
  819 {
  820         struct ieee80211_scan_state *ss = (struct ieee80211_scan_state *) arg;
  821 
  822         IEEE80211_LOCK_ASSERT(ss->ss_ic);
  823 
  824         cv_signal(&SCAN_PRIVATE(ss)->ss_scan_cv);
  825 }
  826 
  827 /*
  828  * Handle mindwell requirements completed; initiate a channel
  829  * change to the next channel asap.
  830  */
  831 static void
  832 scan_mindwell(struct ieee80211_scan_state *ss)
  833 {
  834         struct ieee80211com *ic = ss->ss_ic;
  835 
  836         IEEE80211_LOCK(ic);
  837         scan_signal(ss);
  838         IEEE80211_UNLOCK(ic);
  839 }
  840 
  841 static void
  842 scan_task(void *arg, int pending)
  843 {
  844 #define ISCAN_REP       (ISCAN_MINDWELL | ISCAN_DISCARD)
  845         struct ieee80211_scan_state *ss = (struct ieee80211_scan_state *) arg;
  846         struct ieee80211vap *vap = ss->ss_vap;
  847         struct ieee80211com *ic = ss->ss_ic;
  848         struct ieee80211_channel *chan;
  849         unsigned long maxdwell, scanend;
  850         int scandone = 0;
  851 
  852         IEEE80211_LOCK(ic);
  853         if (vap == NULL || (ic->ic_flags & IEEE80211_F_SCAN) == 0 ||
  854             (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)) {
  855                 /* Cancelled before we started */
  856                 goto done;
  857         }
  858 
  859         if (ss->ss_next == ss->ss_last) {
  860                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  861                         "%s: no channels to scan\n", __func__);
  862                 scandone = 1;
  863                 goto done;
  864         }
  865 
  866         if (vap->iv_opmode == IEEE80211_M_STA &&
  867             vap->iv_state == IEEE80211_S_RUN) {
  868                 if ((vap->iv_bss->ni_flags & IEEE80211_NODE_PWR_MGT) == 0) {
  869                         /* Enable station power save mode */
  870                         vap->iv_sta_ps(vap, 1);
  871                         /*
  872                          * Use an 1ms delay so the null data frame has a chance
  873                          * to go out.
  874                          * XXX Should use M_TXCB mechanism to eliminate this.
  875                          */
  876                         cv_timedwait(&SCAN_PRIVATE(ss)->ss_scan_cv,
  877                             IEEE80211_LOCK_OBJ(ic), hz / 1000);
  878                         if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)
  879                                 goto done;
  880                 }
  881         }
  882 
  883         scanend = ticks + SCAN_PRIVATE(ss)->ss_duration;
  884         IEEE80211_UNLOCK(ic);
  885         ic->ic_scan_start(ic);          /* notify driver */
  886         IEEE80211_LOCK(ic);
  887 
  888         for (;;) {
  889                 scandone = (ss->ss_next >= ss->ss_last) ||
  890                     (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0;
  891                 if (scandone || (ss->ss_flags & IEEE80211_SCAN_GOTPICK) ||
  892                     (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT) ||
  893                      time_after(ticks + ss->ss_mindwell, scanend))
  894                         break;
  895 
  896                 chan = ss->ss_chans[ss->ss_next++];
  897 
  898                 /*
  899                  * Watch for truncation due to the scan end time.
  900                  */
  901                 if (time_after(ticks + ss->ss_maxdwell, scanend))
  902                         maxdwell = scanend - ticks;
  903                 else
  904                         maxdwell = ss->ss_maxdwell;
  905 
  906                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
  907                     "%s: chan %3d%c -> %3d%c [%s, dwell min %lums max %lums]\n",
  908                     __func__,
  909                     ieee80211_chan2ieee(ic, ic->ic_curchan),
  910                         channel_type(ic->ic_curchan),
  911                     ieee80211_chan2ieee(ic, chan), channel_type(chan),
  912                     (ss->ss_flags & IEEE80211_SCAN_ACTIVE) &&
  913                         (chan->ic_flags & IEEE80211_CHAN_PASSIVE) == 0 ?
  914                         "active" : "passive",
  915                     ticks_to_msecs(ss->ss_mindwell), ticks_to_msecs(maxdwell));
  916 
  917                 /*
  918                  * Potentially change channel and phy mode.
  919                  */
  920                 ic->ic_curchan = chan;
  921                 ic->ic_rt = ieee80211_get_ratetable(chan);
  922                 IEEE80211_UNLOCK(ic);
  923                 /*
  924                  * Perform the channel change and scan unlocked so the driver
  925                  * may sleep. Once set_channel returns the hardware has
  926                  * completed the channel change.
  927                  */
  928                 ic->ic_set_channel(ic);
  929                 ieee80211_radiotap_chan_change(ic);
  930 
  931                 /*
  932                  * Scan curchan.  Drivers for "intelligent hardware"
  933                  * override ic_scan_curchan to tell the device to do
  934                  * the work.  Otherwise we manage the work outselves;
  935                  * sending a probe request (as needed), and arming the
  936                  * timeout to switch channels after maxdwell ticks.
  937                  *
  938                  * scan_curchan should only pause for the time required to
  939                  * prepare/initiate the hardware for the scan (if at all), the
  940                  * below condvar is used to sleep for the channels dwell time
  941                  * and allows it to be signalled for abort.
  942                  */
  943                 ic->ic_scan_curchan(ss, maxdwell);
  944                 IEEE80211_LOCK(ic);
  945 
  946                 SCAN_PRIVATE(ss)->ss_chanmindwell = ticks + ss->ss_mindwell;
  947                 /* clear mindwell lock and initial channel change flush */
  948                 SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
  949 
  950                 if ((SCAN_PRIVATE(ss)->ss_iflags & (ISCAN_CANCEL|ISCAN_ABORT)))
  951                         continue;
  952 
  953                 /* Wait to be signalled to scan the next channel */
  954                 cv_wait(&SCAN_PRIVATE(ss)->ss_scan_cv, IEEE80211_LOCK_OBJ(ic));
  955         }
  956         if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_ABORT)
  957                 goto done;
  958 
  959         IEEE80211_UNLOCK(ic);
  960         ic->ic_scan_end(ic);            /* notify driver */
  961         IEEE80211_LOCK(ic);
  962 
  963         /*
  964          * Since a cancellation may have occured during one of the
  965          * driver calls (whilst unlocked), update scandone.
  966          */
  967         if (scandone == 0 &&
  968             ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0)) {
  969                 /* XXX printf? */
  970                 if_printf(vap->iv_ifp,
  971                     "%s: OOPS! scan cancelled during driver call!\n",
  972                     __func__);
  973         }
  974         scandone |= ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) != 0);
  975 
  976         /*
  977          * Record scan complete time.  Note that we also do
  978          * this when canceled so any background scan will
  979          * not be restarted for a while.
  980          */
  981         if (scandone)
  982                 ic->ic_lastscan = ticks;
  983         /* return to the bss channel */
  984         if (ic->ic_bsschan != IEEE80211_CHAN_ANYC &&
  985             ic->ic_curchan != ic->ic_bsschan) {
  986                 ieee80211_setupcurchan(ic, ic->ic_bsschan);
  987                 IEEE80211_UNLOCK(ic);
  988                 ic->ic_set_channel(ic);
  989                 ieee80211_radiotap_chan_change(ic);
  990                 IEEE80211_LOCK(ic);
  991         }
  992         /* clear internal flags and any indication of a pick */
  993         SCAN_PRIVATE(ss)->ss_iflags &= ~ISCAN_REP;
  994         ss->ss_flags &= ~IEEE80211_SCAN_GOTPICK;
  995 
  996         /*
  997          * If not canceled and scan completed, do post-processing.
  998          * If the callback function returns 0, then it wants to
  999          * continue/restart scanning.  Unfortunately we needed to
 1000          * notify the driver to end the scan above to avoid having
 1001          * rx frames alter the scan candidate list.
 1002          */
 1003         if ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_CANCEL) == 0 &&
 1004             !ss->ss_ops->scan_end(ss, vap) &&
 1005             (ss->ss_flags & IEEE80211_SCAN_ONCE) == 0 &&
 1006             time_before(ticks + ss->ss_mindwell, scanend)) {
 1007                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1008                     "%s: done, restart "
 1009                     "[ticks %u, dwell min %lu scanend %lu]\n",
 1010                     __func__,
 1011                     ticks, ss->ss_mindwell, scanend);
 1012                 ss->ss_next = 0;        /* reset to begining */
 1013                 if (ss->ss_flags & IEEE80211_SCAN_ACTIVE)
 1014                         vap->iv_stats.is_scan_active++;
 1015                 else
 1016                         vap->iv_stats.is_scan_passive++;
 1017 
 1018                 ss->ss_ops->scan_restart(ss, vap);      /* XXX? */
 1019                 ieee80211_runtask(ic, &SCAN_PRIVATE(ss)->ss_scan_task);
 1020                 IEEE80211_UNLOCK(ic);
 1021                 return;
 1022         }
 1023 
 1024         /* past here, scandone is ``true'' if not in bg mode */
 1025         if ((ss->ss_flags & IEEE80211_SCAN_BGSCAN) == 0)
 1026                 scandone = 1;
 1027 
 1028         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1029             "%s: %s, [ticks %u, dwell min %lu scanend %lu]\n",
 1030             __func__, scandone ? "done" : "stopped",
 1031             ticks, ss->ss_mindwell, scanend);
 1032 
 1033         /*
 1034          * Clear the SCAN bit first in case frames are
 1035          * pending on the station power save queue.  If
 1036          * we defer this then the dispatch of the frames
 1037          * may generate a request to cancel scanning.
 1038          */
 1039 done:
 1040         ic->ic_flags &= ~IEEE80211_F_SCAN;
 1041         /*
 1042          * Drop out of power save mode when a scan has
 1043          * completed.  If this scan was prematurely terminated
 1044          * because it is a background scan then don't notify
 1045          * the ap; we'll either return to scanning after we
 1046          * receive the beacon frame or we'll drop out of power
 1047          * save mode because the beacon indicates we have frames
 1048          * waiting for us.
 1049          */
 1050         if (scandone) {
 1051                 vap->iv_sta_ps(vap, 0);
 1052                 if (ss->ss_next >= ss->ss_last) {
 1053                         ieee80211_notify_scan_done(vap);
 1054                         ic->ic_flags_ext &= ~IEEE80211_FEXT_BGSCAN;
 1055                 }
 1056         }
 1057         SCAN_PRIVATE(ss)->ss_iflags &= ~(ISCAN_CANCEL|ISCAN_ABORT);
 1058         ss->ss_flags &= ~(IEEE80211_SCAN_ONCE | IEEE80211_SCAN_PICK1ST);
 1059         IEEE80211_UNLOCK(ic);
 1060 #undef ISCAN_REP
 1061 }
 1062 
 1063 #ifdef IEEE80211_DEBUG
 1064 static void
 1065 dump_country(const uint8_t *ie)
 1066 {
 1067         const struct ieee80211_country_ie *cie =
 1068            (const struct ieee80211_country_ie *) ie;
 1069         int i, nbands, schan, nchan;
 1070 
 1071         if (cie->len < 3) {
 1072                 printf(" <bogus country ie, len %d>", cie->len);
 1073                 return;
 1074         }
 1075         printf(" country [%c%c%c", cie->cc[0], cie->cc[1], cie->cc[2]);
 1076         nbands = (cie->len - 3) / sizeof(cie->band[0]);
 1077         for (i = 0; i < nbands; i++) {
 1078                 schan = cie->band[i].schan;
 1079                 nchan = cie->band[i].nchan;
 1080                 if (nchan != 1)
 1081                         printf(" %u-%u,%u", schan, schan + nchan-1,
 1082                             cie->band[i].maxtxpwr);
 1083                 else
 1084                         printf(" %u,%u", schan, cie->band[i].maxtxpwr);
 1085         }
 1086         printf("]");
 1087 }
 1088 
 1089 static void
 1090 dump_probe_beacon(uint8_t subtype, int isnew,
 1091         const uint8_t mac[IEEE80211_ADDR_LEN],
 1092         const struct ieee80211_scanparams *sp, int rssi)
 1093 {
 1094 
 1095         printf("[%s] %s%s on chan %u (bss chan %u) ",
 1096             ether_sprintf(mac), isnew ? "new " : "",
 1097             ieee80211_mgt_subtype_name[subtype >> IEEE80211_FC0_SUBTYPE_SHIFT],
 1098             sp->chan, sp->bchan);
 1099         ieee80211_print_essid(sp->ssid + 2, sp->ssid[1]);
 1100         printf(" rssi %d\n", rssi);
 1101 
 1102         if (isnew) {
 1103                 printf("[%s] caps 0x%x bintval %u erp 0x%x", 
 1104                         ether_sprintf(mac), sp->capinfo, sp->bintval, sp->erp);
 1105                 if (sp->country != NULL)
 1106                         dump_country(sp->country);
 1107                 printf("\n");
 1108         }
 1109 }
 1110 #endif /* IEEE80211_DEBUG */
 1111 
 1112 /*
 1113  * Process a beacon or probe response frame.
 1114  */
 1115 void
 1116 ieee80211_add_scan(struct ieee80211vap *vap,
 1117         const struct ieee80211_scanparams *sp,
 1118         const struct ieee80211_frame *wh,
 1119         int subtype, int rssi, int noise)
 1120 {
 1121         struct ieee80211com *ic = vap->iv_ic;
 1122         struct ieee80211_scan_state *ss = ic->ic_scan;
 1123 
 1124         /* XXX locking */
 1125         /*
 1126          * Frames received during startup are discarded to avoid
 1127          * using scan state setup on the initial entry to the timer
 1128          * callback.  This can occur because the device may enable
 1129          * rx prior to our doing the initial channel change in the
 1130          * timer routine.
 1131          */
 1132         if (SCAN_PRIVATE(ss)->ss_iflags & ISCAN_DISCARD)
 1133                 return;
 1134 #ifdef IEEE80211_DEBUG
 1135         if (ieee80211_msg_scan(vap) && (ic->ic_flags & IEEE80211_F_SCAN))
 1136                 dump_probe_beacon(subtype, 1, wh->i_addr2, sp, rssi);
 1137 #endif
 1138         if (ss->ss_ops != NULL &&
 1139             ss->ss_ops->scan_add(ss, sp, wh, subtype, rssi, noise)) {
 1140                 /*
 1141                  * If we've reached the min dwell time terminate
 1142                  * the timer so we'll switch to the next channel.
 1143                  */
 1144                 if ((SCAN_PRIVATE(ss)->ss_iflags & ISCAN_MINDWELL) == 0 &&
 1145                     time_after_eq(ticks, SCAN_PRIVATE(ss)->ss_chanmindwell)) {
 1146                         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1147                             "%s: chan %3d%c min dwell met (%u > %lu)\n",
 1148                             __func__,
 1149                             ieee80211_chan2ieee(ic, ic->ic_curchan),
 1150                                 channel_type(ic->ic_curchan),
 1151                             ticks, SCAN_PRIVATE(ss)->ss_chanmindwell);
 1152                         SCAN_PRIVATE(ss)->ss_iflags |= ISCAN_MINDWELL;
 1153                         /*
 1154                          * NB: trigger at next clock tick or wait for the
 1155                          * hardware.
 1156                          */
 1157                         ic->ic_scan_mindwell(ss);
 1158                 }
 1159         }
 1160 }
 1161 
 1162 /*
 1163  * Timeout/age scan cache entries; called from sta timeout
 1164  * timer (XXX should be self-contained).
 1165  */
 1166 void
 1167 ieee80211_scan_timeout(struct ieee80211com *ic)
 1168 {
 1169         struct ieee80211_scan_state *ss = ic->ic_scan;
 1170 
 1171         if (ss->ss_ops != NULL)
 1172                 ss->ss_ops->scan_age(ss);
 1173 }
 1174 
 1175 /*
 1176  * Mark a scan cache entry after a successful associate.
 1177  */
 1178 void
 1179 ieee80211_scan_assoc_success(struct ieee80211vap *vap, const uint8_t mac[])
 1180 {
 1181         struct ieee80211_scan_state *ss = vap->iv_ic->ic_scan;
 1182 
 1183         if (ss->ss_ops != NULL) {
 1184                 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_SCAN,
 1185                         mac, "%s",  __func__);
 1186                 ss->ss_ops->scan_assoc_success(ss, mac);
 1187         }
 1188 }
 1189 
 1190 /*
 1191  * Demerit a scan cache entry after failing to associate.
 1192  */
 1193 void
 1194 ieee80211_scan_assoc_fail(struct ieee80211vap *vap,
 1195         const uint8_t mac[], int reason)
 1196 {
 1197         struct ieee80211_scan_state *ss = vap->iv_ic->ic_scan;
 1198 
 1199         if (ss->ss_ops != NULL) {
 1200                 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_SCAN, mac,
 1201                         "%s: reason %u", __func__, reason);
 1202                 ss->ss_ops->scan_assoc_fail(ss, mac, reason);
 1203         }
 1204 }
 1205 
 1206 /*
 1207  * Iterate over the contents of the scan cache.
 1208  */
 1209 void
 1210 ieee80211_scan_iterate(struct ieee80211vap *vap,
 1211         ieee80211_scan_iter_func *f, void *arg)
 1212 {
 1213         struct ieee80211_scan_state *ss = vap->iv_ic->ic_scan;
 1214 
 1215         if (ss->ss_ops != NULL)
 1216                 ss->ss_ops->scan_iterate(ss, f, arg);
 1217 }
 1218 
 1219 /*
 1220  * Flush the contents of the scan cache.
 1221  */
 1222 void
 1223 ieee80211_scan_flush(struct ieee80211vap *vap)
 1224 {
 1225         struct ieee80211_scan_state *ss = vap->iv_ic->ic_scan;
 1226 
 1227         if (ss->ss_ops != NULL && ss->ss_vap == vap) {
 1228                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN, "%s\n",  __func__);
 1229                 ss->ss_ops->scan_flush(ss);
 1230         }
 1231 }
 1232 
 1233 /*
 1234  * Check the scan cache for an ap/channel to use; if that
 1235  * fails then kick off a new scan.
 1236  */
 1237 struct ieee80211_channel *
 1238 ieee80211_scan_pickchannel(struct ieee80211com *ic, int flags)
 1239 {
 1240         struct ieee80211_scan_state *ss = ic->ic_scan;
 1241 
 1242         IEEE80211_LOCK_ASSERT(ic);
 1243 
 1244         if (ss == NULL || ss->ss_ops == NULL || ss->ss_vap == NULL) {
 1245                 /* XXX printf? */
 1246                 return NULL;
 1247         }
 1248         if (ss->ss_ops->scan_pickchan == NULL) {
 1249                 IEEE80211_DPRINTF(ss->ss_vap, IEEE80211_MSG_SCAN,
 1250                     "%s: scan module does not support picking a channel, "
 1251                     "opmode %s\n", __func__, ss->ss_vap->iv_opmode);
 1252                 return NULL;
 1253         }
 1254         return ss->ss_ops->scan_pickchan(ss, flags);
 1255 }

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