The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/net80211/ieee80211_scan_sta.c

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    1 /*-
    2  * Copyright (c) 2002-2009 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/9.0/sys/net80211/ieee80211_scan_sta.c 224717 2011-08-08 16:29:07Z bschmidt $");
   28 
   29 /*
   30  * IEEE 802.11 station scanning support.
   31  */
   32 #include "opt_wlan.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/systm.h>
   36 #include <sys/kernel.h>
   37 #include <sys/module.h>
   38 
   39 #include <sys/socket.h>
   40 
   41 #include <net/if.h>
   42 #include <net/if_media.h>
   43 #include <net/ethernet.h>
   44 
   45 #include <net80211/ieee80211_var.h>
   46 #include <net80211/ieee80211_input.h>
   47 #include <net80211/ieee80211_regdomain.h>
   48 #ifdef IEEE80211_SUPPORT_TDMA
   49 #include <net80211/ieee80211_tdma.h>
   50 #endif
   51 #ifdef IEEE80211_SUPPORT_MESH
   52 #include <net80211/ieee80211_mesh.h>
   53 #endif
   54 
   55 #include <net/bpf.h>
   56 
   57 /*
   58  * Parameters for managing cache entries:
   59  *
   60  * o a station with STA_FAILS_MAX failures is not considered
   61  *   when picking a candidate
   62  * o a station that hasn't had an update in STA_PURGE_SCANS
   63  *   (background) scans is discarded
   64  * o after STA_FAILS_AGE seconds we clear the failure count
   65  */
   66 #define STA_FAILS_MAX   2               /* assoc failures before ignored */
   67 #define STA_FAILS_AGE   (2*60)          /* time before clearing fails (secs) */
   68 #define STA_PURGE_SCANS 2               /* age for purging entries (scans) */
   69 
   70 /* XXX tunable */
   71 #define STA_RSSI_MIN    8               /* min acceptable rssi */
   72 #define STA_RSSI_MAX    40              /* max rssi for comparison */
   73 
   74 struct sta_entry {
   75         struct ieee80211_scan_entry base;
   76         TAILQ_ENTRY(sta_entry) se_list;
   77         LIST_ENTRY(sta_entry) se_hash;
   78         uint8_t         se_fails;               /* failure to associate count */
   79         uint8_t         se_seen;                /* seen during current scan */
   80         uint8_t         se_notseen;             /* not seen in previous scans */
   81         uint8_t         se_flags;
   82 #define STA_DEMOTE11B   0x01                    /* match w/ demoted 11b chan */
   83         uint32_t        se_avgrssi;             /* LPF rssi state */
   84         unsigned long   se_lastupdate;          /* time of last update */
   85         unsigned long   se_lastfail;            /* time of last failure */
   86         unsigned long   se_lastassoc;           /* time of last association */
   87         u_int           se_scangen;             /* iterator scan gen# */
   88         u_int           se_countrygen;          /* gen# of last cc notify */
   89 };
   90 
   91 #define STA_HASHSIZE    32
   92 /* simple hash is enough for variation of macaddr */
   93 #define STA_HASH(addr)  \
   94         (((const uint8_t *)(addr))[IEEE80211_ADDR_LEN - 1] % STA_HASHSIZE)
   95 
   96 #define MAX_IEEE_CHAN   256                     /* max acceptable IEEE chan # */
   97 CTASSERT(MAX_IEEE_CHAN >= 256);
   98 
   99 struct sta_table {
  100         ieee80211_scan_table_lock_t st_lock;    /* on scan table */
  101         TAILQ_HEAD(, sta_entry) st_entry;       /* all entries */
  102         LIST_HEAD(, sta_entry) st_hash[STA_HASHSIZE];
  103         struct mtx      st_scanlock;            /* on st_scaniter */
  104         u_int           st_scaniter;            /* gen# for iterator */
  105         u_int           st_scangen;             /* scan generation # */
  106         int             st_newscan;
  107         /* ap-related state */
  108         int             st_maxrssi[MAX_IEEE_CHAN];
  109 };
  110 
  111 static void sta_flush_table(struct sta_table *);
  112 /*
  113  * match_bss returns a bitmask describing if an entry is suitable
  114  * for use.  If non-zero the entry was deemed not suitable and it's
  115  * contents explains why.  The following flags are or'd to to this
  116  * mask and can be used to figure out why the entry was rejected.
  117  */
  118 #define MATCH_CHANNEL           0x00001 /* channel mismatch */
  119 #define MATCH_CAPINFO           0x00002 /* capabilities mismatch, e.g. no ess */
  120 #define MATCH_PRIVACY           0x00004 /* privacy mismatch */
  121 #define MATCH_RATE              0x00008 /* rate set mismatch */
  122 #define MATCH_SSID              0x00010 /* ssid mismatch */
  123 #define MATCH_BSSID             0x00020 /* bssid mismatch */
  124 #define MATCH_FAILS             0x00040 /* too many failed auth attempts */
  125 #define MATCH_NOTSEEN           0x00080 /* not seen in recent scans */
  126 #define MATCH_RSSI              0x00100 /* rssi deemed too low to use */
  127 #define MATCH_CC                0x00200 /* country code mismatch */
  128 #define MATCH_TDMA_NOIE         0x00400 /* no TDMA ie */
  129 #define MATCH_TDMA_NOTMASTER    0x00800 /* not TDMA master */
  130 #define MATCH_TDMA_NOSLOT       0x01000 /* all TDMA slots occupied */
  131 #define MATCH_TDMA_LOCAL        0x02000 /* local address */
  132 #define MATCH_TDMA_VERSION      0x04000 /* protocol version mismatch */
  133 #define MATCH_MESH_NOID         0x10000 /* no MESHID ie */
  134 #define MATCH_MESHID            0x20000 /* meshid mismatch */
  135 static int match_bss(struct ieee80211vap *,
  136         const struct ieee80211_scan_state *, struct sta_entry *, int);
  137 static void adhoc_age(struct ieee80211_scan_state *);
  138 
  139 static __inline int
  140 isocmp(const uint8_t cc1[], const uint8_t cc2[])
  141 {
  142      return (cc1[0] == cc2[0] && cc1[1] == cc2[1]);
  143 }
  144 
  145 /* number of references from net80211 layer */
  146 static  int nrefs = 0;
  147 /*
  148  * Module glue.
  149  */
  150 IEEE80211_SCANNER_MODULE(sta, 1);
  151 
  152 /*
  153  * Attach prior to any scanning work.
  154  */
  155 static int
  156 sta_attach(struct ieee80211_scan_state *ss)
  157 {
  158         struct sta_table *st;
  159 
  160         st = (struct sta_table *) malloc(sizeof(struct sta_table),
  161                 M_80211_SCAN, M_NOWAIT | M_ZERO);
  162         if (st == NULL)
  163                 return 0;
  164         IEEE80211_SCAN_TABLE_LOCK_INIT(st, "scantable");
  165         mtx_init(&st->st_scanlock, "scangen", "802.11 scangen", MTX_DEF);
  166         TAILQ_INIT(&st->st_entry);
  167         ss->ss_priv = st;
  168         nrefs++;                        /* NB: we assume caller locking */
  169         return 1;
  170 }
  171 
  172 /*
  173  * Cleanup any private state.
  174  */
  175 static int
  176 sta_detach(struct ieee80211_scan_state *ss)
  177 {
  178         struct sta_table *st = ss->ss_priv;
  179 
  180         if (st != NULL) {
  181                 sta_flush_table(st);
  182                 IEEE80211_SCAN_TABLE_LOCK_DESTROY(st);
  183                 mtx_destroy(&st->st_scanlock);
  184                 free(st, M_80211_SCAN);
  185                 KASSERT(nrefs > 0, ("imbalanced attach/detach"));
  186                 nrefs--;                /* NB: we assume caller locking */
  187         }
  188         return 1;
  189 }
  190 
  191 /*
  192  * Flush all per-scan state.
  193  */
  194 static int
  195 sta_flush(struct ieee80211_scan_state *ss)
  196 {
  197         struct sta_table *st = ss->ss_priv;
  198 
  199         IEEE80211_SCAN_TABLE_LOCK(st);
  200         sta_flush_table(st);
  201         IEEE80211_SCAN_TABLE_UNLOCK(st);
  202         ss->ss_last = 0;
  203         return 0;
  204 }
  205 
  206 /*
  207  * Flush all entries in the scan cache.
  208  */
  209 static void
  210 sta_flush_table(struct sta_table *st)
  211 {
  212         struct sta_entry *se, *next;
  213 
  214         TAILQ_FOREACH_SAFE(se, &st->st_entry, se_list, next) {
  215                 TAILQ_REMOVE(&st->st_entry, se, se_list);
  216                 LIST_REMOVE(se, se_hash);
  217                 ieee80211_ies_cleanup(&se->base.se_ies);
  218                 free(se, M_80211_SCAN);
  219         }
  220         memset(st->st_maxrssi, 0, sizeof(st->st_maxrssi));
  221 }
  222 
  223 /*
  224  * Process a beacon or probe response frame; create an
  225  * entry in the scan cache or update any previous entry.
  226  */
  227 static int
  228 sta_add(struct ieee80211_scan_state *ss, 
  229         const struct ieee80211_scanparams *sp,
  230         const struct ieee80211_frame *wh,
  231         int subtype, int rssi, int noise)
  232 {
  233 #define ISPROBE(_st)    ((_st) == IEEE80211_FC0_SUBTYPE_PROBE_RESP)
  234 #define PICK1ST(_ss) \
  235         ((ss->ss_flags & (IEEE80211_SCAN_PICK1ST | IEEE80211_SCAN_GOTPICK)) == \
  236         IEEE80211_SCAN_PICK1ST)
  237         struct sta_table *st = ss->ss_priv;
  238         const uint8_t *macaddr = wh->i_addr2;
  239         struct ieee80211vap *vap = ss->ss_vap;
  240         struct ieee80211com *ic = vap->iv_ic;
  241         struct ieee80211_channel *c;
  242         struct sta_entry *se;
  243         struct ieee80211_scan_entry *ise;
  244         int hash;
  245 
  246         hash = STA_HASH(macaddr);
  247 
  248         IEEE80211_SCAN_TABLE_LOCK(st);
  249         LIST_FOREACH(se, &st->st_hash[hash], se_hash)
  250                 if (IEEE80211_ADDR_EQ(se->base.se_macaddr, macaddr))
  251                         goto found;
  252         se = (struct sta_entry *) malloc(sizeof(struct sta_entry),
  253                 M_80211_SCAN, M_NOWAIT | M_ZERO);
  254         if (se == NULL) {
  255                 IEEE80211_SCAN_TABLE_UNLOCK(st);
  256                 return 0;
  257         }
  258         se->se_scangen = st->st_scaniter-1;
  259         se->se_avgrssi = IEEE80211_RSSI_DUMMY_MARKER;
  260         IEEE80211_ADDR_COPY(se->base.se_macaddr, macaddr);
  261         TAILQ_INSERT_TAIL(&st->st_entry, se, se_list);
  262         LIST_INSERT_HEAD(&st->st_hash[hash], se, se_hash);
  263 found:
  264         ise = &se->base;
  265         /* XXX ap beaconing multiple ssid w/ same bssid */
  266         if (sp->ssid[1] != 0 &&
  267             (ISPROBE(subtype) || ise->se_ssid[1] == 0))
  268                 memcpy(ise->se_ssid, sp->ssid, 2+sp->ssid[1]);
  269         KASSERT(sp->rates[1] <= IEEE80211_RATE_MAXSIZE,
  270                 ("rate set too large: %u", sp->rates[1]));
  271         memcpy(ise->se_rates, sp->rates, 2+sp->rates[1]);
  272         if (sp->xrates != NULL) {
  273                 /* XXX validate xrates[1] */
  274                 KASSERT(sp->xrates[1] <= IEEE80211_RATE_MAXSIZE,
  275                         ("xrate set too large: %u", sp->xrates[1]));
  276                 memcpy(ise->se_xrates, sp->xrates, 2+sp->xrates[1]);
  277         } else
  278                 ise->se_xrates[1] = 0;
  279         IEEE80211_ADDR_COPY(ise->se_bssid, wh->i_addr3);
  280         if ((sp->status & IEEE80211_BPARSE_OFFCHAN) == 0) {
  281                 /*
  282                  * Record rssi data using extended precision LPF filter.
  283                  *
  284                  * NB: use only on-channel data to insure we get a good
  285                  *     estimate of the signal we'll see when associated.
  286                  */
  287                 IEEE80211_RSSI_LPF(se->se_avgrssi, rssi);
  288                 ise->se_rssi = IEEE80211_RSSI_GET(se->se_avgrssi);
  289                 ise->se_noise = noise;
  290         }
  291         memcpy(ise->se_tstamp.data, sp->tstamp, sizeof(ise->se_tstamp));
  292         ise->se_intval = sp->bintval;
  293         ise->se_capinfo = sp->capinfo;
  294 #ifdef IEEE80211_SUPPORT_MESH
  295         if (sp->meshid != NULL && sp->meshid[1] != 0)
  296                 memcpy(ise->se_meshid, sp->meshid, 2+sp->meshid[1]);
  297 #endif
  298         /*
  299          * Beware of overriding se_chan for frames seen
  300          * off-channel; this can cause us to attempt an
  301          * association on the wrong channel.
  302          */
  303         if (sp->status & IEEE80211_BPARSE_OFFCHAN) {
  304                 /*
  305                  * Off-channel, locate the home/bss channel for the sta
  306                  * using the value broadcast in the DSPARMS ie.  We know
  307                  * sp->chan has this value because it's used to calculate
  308                  * IEEE80211_BPARSE_OFFCHAN.
  309                  */
  310                 c = ieee80211_find_channel_byieee(ic, sp->chan,
  311                     ic->ic_curchan->ic_flags);
  312                 if (c != NULL) {
  313                         ise->se_chan = c;
  314                 } else if (ise->se_chan == NULL) {
  315                         /* should not happen, pick something */
  316                         ise->se_chan = ic->ic_curchan;
  317                 }
  318         } else
  319                 ise->se_chan = ic->ic_curchan;
  320         if (IEEE80211_IS_CHAN_HT(ise->se_chan) && sp->htcap == NULL) {
  321                 /* Demote legacy networks to a non-HT channel. */
  322                 c = ieee80211_find_channel(ic, ise->se_chan->ic_freq,
  323                     ise->se_chan->ic_flags & ~IEEE80211_CHAN_HT);
  324                 KASSERT(c != NULL,
  325                     ("no legacy channel %u", ise->se_chan->ic_ieee));
  326                 ise->se_chan = c;
  327         }
  328         ise->se_fhdwell = sp->fhdwell;
  329         ise->se_fhindex = sp->fhindex;
  330         ise->se_erp = sp->erp;
  331         ise->se_timoff = sp->timoff;
  332         if (sp->tim != NULL) {
  333                 const struct ieee80211_tim_ie *tim =
  334                     (const struct ieee80211_tim_ie *) sp->tim;
  335                 ise->se_dtimperiod = tim->tim_period;
  336         }
  337         if (sp->country != NULL) {
  338                 const struct ieee80211_country_ie *cie =
  339                     (const struct ieee80211_country_ie *) sp->country;
  340                 /*
  341                  * If 11d is enabled and we're attempting to join a bss
  342                  * that advertises it's country code then compare our
  343                  * current settings to what we fetched from the country ie.
  344                  * If our country code is unspecified or different then
  345                  * dispatch an event to user space that identifies the
  346                  * country code so our regdomain config can be changed.
  347                  */
  348                 /* XXX only for STA mode? */
  349                 if ((IEEE80211_IS_CHAN_11D(ise->se_chan) ||
  350                     (vap->iv_flags_ext & IEEE80211_FEXT_DOTD)) &&
  351                     (ic->ic_regdomain.country == CTRY_DEFAULT ||
  352                      !isocmp(cie->cc, ic->ic_regdomain.isocc))) {
  353                         /* only issue one notify event per scan */
  354                         if (se->se_countrygen != st->st_scangen) {
  355                                 ieee80211_notify_country(vap, ise->se_bssid,
  356                                     cie->cc);
  357                                 se->se_countrygen = st->st_scangen;
  358                         }
  359                 }
  360                 ise->se_cc[0] = cie->cc[0];
  361                 ise->se_cc[1] = cie->cc[1];
  362         }
  363         /* NB: no need to setup ie ptrs; they are not (currently) used */
  364         (void) ieee80211_ies_init(&ise->se_ies, sp->ies, sp->ies_len);
  365 
  366         /* clear failure count after STA_FAIL_AGE passes */
  367         if (se->se_fails && (ticks - se->se_lastfail) > STA_FAILS_AGE*hz) {
  368                 se->se_fails = 0;
  369                 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_SCAN, macaddr,
  370                     "%s: fails %u", __func__, se->se_fails);
  371         }
  372 
  373         se->se_lastupdate = ticks;              /* update time */
  374         se->se_seen = 1;
  375         se->se_notseen = 0;
  376 
  377         KASSERT(sizeof(sp->bchan) == 1, ("bchan size"));
  378         if (rssi > st->st_maxrssi[sp->bchan])
  379                 st->st_maxrssi[sp->bchan] = rssi;
  380 
  381         IEEE80211_SCAN_TABLE_UNLOCK(st);
  382 
  383         /*
  384          * If looking for a quick choice and nothing's
  385          * been found check here.
  386          */
  387         if (PICK1ST(ss) && match_bss(vap, ss, se, IEEE80211_MSG_SCAN) == 0)
  388                 ss->ss_flags |= IEEE80211_SCAN_GOTPICK;
  389 
  390         return 1;
  391 #undef PICK1ST
  392 #undef ISPROBE
  393 }
  394 
  395 /*
  396  * Check if a channel is excluded by user request.
  397  */
  398 static int
  399 isexcluded(struct ieee80211vap *vap, const struct ieee80211_channel *c)
  400 {
  401         return (isclr(vap->iv_ic->ic_chan_active, c->ic_ieee) ||
  402             (vap->iv_des_chan != IEEE80211_CHAN_ANYC &&
  403              c->ic_freq != vap->iv_des_chan->ic_freq));
  404 }
  405 
  406 static struct ieee80211_channel *
  407 find11gchannel(struct ieee80211com *ic, int i, int freq)
  408 {
  409         struct ieee80211_channel *c;
  410         int j;
  411 
  412         /*
  413          * The normal ordering in the channel list is b channel
  414          * immediately followed by g so optimize the search for
  415          * this.  We'll still do a full search just in case.
  416          */
  417         for (j = i+1; j < ic->ic_nchans; j++) {
  418                 c = &ic->ic_channels[j];
  419                 if (c->ic_freq == freq && IEEE80211_IS_CHAN_G(c))
  420                         return c;
  421         }
  422         for (j = 0; j < i; j++) {
  423                 c = &ic->ic_channels[j];
  424                 if (c->ic_freq == freq && IEEE80211_IS_CHAN_G(c))
  425                         return c;
  426         }
  427         return NULL;
  428 }
  429 
  430 static const u_int chanflags[IEEE80211_MODE_MAX] = {
  431         [IEEE80211_MODE_AUTO]     = IEEE80211_CHAN_B,
  432         [IEEE80211_MODE_11A]      = IEEE80211_CHAN_A,
  433         [IEEE80211_MODE_11B]      = IEEE80211_CHAN_B,
  434         [IEEE80211_MODE_11G]      = IEEE80211_CHAN_G,
  435         [IEEE80211_MODE_FH]       = IEEE80211_CHAN_FHSS,
  436         /* check base channel */
  437         [IEEE80211_MODE_TURBO_A]  = IEEE80211_CHAN_A,
  438         [IEEE80211_MODE_TURBO_G]  = IEEE80211_CHAN_G,
  439         [IEEE80211_MODE_STURBO_A] = IEEE80211_CHAN_ST,
  440         [IEEE80211_MODE_HALF]     = IEEE80211_CHAN_HALF,
  441         [IEEE80211_MODE_QUARTER]  = IEEE80211_CHAN_QUARTER,
  442         /* check legacy */
  443         [IEEE80211_MODE_11NA]     = IEEE80211_CHAN_A,
  444         [IEEE80211_MODE_11NG]     = IEEE80211_CHAN_G,
  445 };
  446 
  447 static void
  448 add_channels(struct ieee80211vap *vap,
  449         struct ieee80211_scan_state *ss,
  450         enum ieee80211_phymode mode, const uint16_t freq[], int nfreq)
  451 {
  452 #define N(a)    (sizeof(a) / sizeof(a[0]))
  453         struct ieee80211com *ic = vap->iv_ic;
  454         struct ieee80211_channel *c, *cg;
  455         u_int modeflags;
  456         int i;
  457 
  458         KASSERT(mode < N(chanflags), ("Unexpected mode %u", mode));
  459         modeflags = chanflags[mode];
  460         for (i = 0; i < nfreq; i++) {
  461                 if (ss->ss_last >= IEEE80211_SCAN_MAX)
  462                         break;
  463 
  464                 c = ieee80211_find_channel(ic, freq[i], modeflags);
  465                 if (c == NULL || isexcluded(vap, c))
  466                         continue;
  467                 if (mode == IEEE80211_MODE_AUTO) {
  468                         /*
  469                          * XXX special-case 11b/g channels so we select
  470                          *     the g channel if both are present.
  471                          */
  472                         if (IEEE80211_IS_CHAN_B(c) &&
  473                             (cg = find11gchannel(ic, i, c->ic_freq)) != NULL)
  474                                 c = cg;
  475                 }
  476                 ss->ss_chans[ss->ss_last++] = c;
  477         }
  478 #undef N
  479 }
  480 
  481 struct scanlist {
  482         uint16_t        mode;
  483         uint16_t        count;
  484         const uint16_t  *list;
  485 };
  486 
  487 static int
  488 checktable(const struct scanlist *scan, const struct ieee80211_channel *c)
  489 {
  490         int i;
  491 
  492         for (; scan->list != NULL; scan++) {
  493                 for (i = 0; i < scan->count; i++)
  494                         if (scan->list[i] == c->ic_freq) 
  495                                 return 1;
  496         }
  497         return 0;
  498 }
  499 
  500 static int
  501 onscanlist(const struct ieee80211_scan_state *ss,
  502         const struct ieee80211_channel *c)
  503 {
  504         int i;
  505 
  506         for (i = 0; i < ss->ss_last; i++)
  507                 if (ss->ss_chans[i] == c)
  508                         return 1;
  509         return 0;
  510 }
  511 
  512 static void
  513 sweepchannels(struct ieee80211_scan_state *ss, struct ieee80211vap *vap,
  514         const struct scanlist table[])
  515 {
  516         struct ieee80211com *ic = vap->iv_ic;
  517         struct ieee80211_channel *c;
  518         int i;
  519 
  520         for (i = 0; i < ic->ic_nchans; i++) {
  521                 if (ss->ss_last >= IEEE80211_SCAN_MAX)
  522                         break;
  523 
  524                 c = &ic->ic_channels[i];
  525                 /*
  526                  * Ignore dynamic turbo channels; we scan them
  527                  * in normal mode (i.e. not boosted).  Likewise
  528                  * for HT channels, they get scanned using
  529                  * legacy rates.
  530                  */
  531                 if (IEEE80211_IS_CHAN_DTURBO(c) || IEEE80211_IS_CHAN_HT(c))
  532                         continue;
  533 
  534                 /*
  535                  * If a desired mode was specified, scan only 
  536                  * channels that satisfy that constraint.
  537                  */
  538                 if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
  539                     vap->iv_des_mode != ieee80211_chan2mode(c))
  540                         continue;
  541 
  542                 /*
  543                  * Skip channels excluded by user request.
  544                  */
  545                 if (isexcluded(vap, c))
  546                         continue;
  547 
  548                 /*
  549                  * Add the channel unless it is listed in the
  550                  * fixed scan order tables.  This insures we
  551                  * don't sweep back in channels we filtered out
  552                  * above.
  553                  */
  554                 if (checktable(table, c))
  555                         continue;
  556 
  557                 /* Add channel to scanning list. */
  558                 ss->ss_chans[ss->ss_last++] = c;
  559         }
  560         /*
  561          * Explicitly add any desired channel if:
  562          * - not already on the scan list
  563          * - allowed by any desired mode constraint
  564          * - there is space in the scan list
  565          * This allows the channel to be used when the filtering
  566          * mechanisms would otherwise elide it (e.g HT, turbo).
  567          */
  568         c = vap->iv_des_chan;
  569         if (c != IEEE80211_CHAN_ANYC &&
  570             !onscanlist(ss, c) &&
  571             (vap->iv_des_mode == IEEE80211_MODE_AUTO ||
  572              vap->iv_des_mode == ieee80211_chan2mode(c)) &&
  573             ss->ss_last < IEEE80211_SCAN_MAX)
  574                 ss->ss_chans[ss->ss_last++] = c;
  575 }
  576 
  577 static void
  578 makescanlist(struct ieee80211_scan_state *ss, struct ieee80211vap *vap,
  579         const struct scanlist table[])
  580 {
  581         const struct scanlist *scan;
  582         enum ieee80211_phymode mode;
  583 
  584         ss->ss_last = 0;
  585         /*
  586          * Use the table of ordered channels to construct the list
  587          * of channels for scanning.  Any channels in the ordered
  588          * list not in the master list will be discarded.
  589          */
  590         for (scan = table; scan->list != NULL; scan++) {
  591                 mode = scan->mode;
  592                 if (vap->iv_des_mode != IEEE80211_MODE_AUTO) {
  593                         /*
  594                          * If a desired mode was specified, scan only 
  595                          * channels that satisfy that constraint.
  596                          */
  597                         if (vap->iv_des_mode != mode) {
  598                                 /*
  599                                  * The scan table marks 2.4Ghz channels as b
  600                                  * so if the desired mode is 11g, then use
  601                                  * the 11b channel list but upgrade the mode.
  602                                  */
  603                                 if (vap->iv_des_mode != IEEE80211_MODE_11G ||
  604                                     mode != IEEE80211_MODE_11B)
  605                                         continue;
  606                                 mode = IEEE80211_MODE_11G;      /* upgrade */
  607                         }
  608                 } else {
  609                         /*
  610                          * This lets add_channels upgrade an 11b channel
  611                          * to 11g if available.
  612                          */
  613                         if (mode == IEEE80211_MODE_11B)
  614                                 mode = IEEE80211_MODE_AUTO;
  615                 }
  616 #ifdef IEEE80211_F_XR
  617                 /* XR does not operate on turbo channels */
  618                 if ((vap->iv_flags & IEEE80211_F_XR) &&
  619                     (mode == IEEE80211_MODE_TURBO_A ||
  620                      mode == IEEE80211_MODE_TURBO_G ||
  621                      mode == IEEE80211_MODE_STURBO_A))
  622                         continue;
  623 #endif
  624                 /*
  625                  * Add the list of the channels; any that are not
  626                  * in the master channel list will be discarded.
  627                  */
  628                 add_channels(vap, ss, mode, scan->list, scan->count);
  629         }
  630 
  631         /*
  632          * Add the channels from the ic that are not present
  633          * in the table.
  634          */
  635         sweepchannels(ss, vap, table);
  636 }
  637 
  638 static const uint16_t rcl1[] =          /* 8 FCC channel: 52, 56, 60, 64, 36, 40, 44, 48 */
  639 { 5260, 5280, 5300, 5320, 5180, 5200, 5220, 5240 };
  640 static const uint16_t rcl2[] =          /* 4 MKK channels: 34, 38, 42, 46 */
  641 { 5170, 5190, 5210, 5230 };
  642 static const uint16_t rcl3[] =          /* 2.4Ghz ch: 1,6,11,7,13 */
  643 { 2412, 2437, 2462, 2442, 2472 };
  644 static const uint16_t rcl4[] =          /* 5 FCC channel: 149, 153, 161, 165 */
  645 { 5745, 5765, 5785, 5805, 5825 };
  646 static const uint16_t rcl7[] =          /* 11 ETSI channel: 100,104,108,112,116,120,124,128,132,136,140 */
  647 { 5500, 5520, 5540, 5560, 5580, 5600, 5620, 5640, 5660, 5680, 5700 };
  648 static const uint16_t rcl8[] =          /* 2.4Ghz ch: 2,3,4,5,8,9,10,12 */
  649 { 2417, 2422, 2427, 2432, 2447, 2452, 2457, 2467 };
  650 static const uint16_t rcl9[] =          /* 2.4Ghz ch: 14 */
  651 { 2484 };
  652 static const uint16_t rcl10[] = /* Added Korean channels 2312-2372 */
  653 { 2312, 2317, 2322, 2327, 2332, 2337, 2342, 2347, 2352, 2357, 2362, 2367, 2372 };
  654 static const uint16_t rcl11[] = /* Added Japan channels in 4.9/5.0 spectrum */
  655 { 5040, 5060, 5080, 4920, 4940, 4960, 4980 };
  656 #ifdef ATH_TURBO_SCAN
  657 static const uint16_t rcl5[] =          /* 3 static turbo channels */
  658 { 5210, 5250, 5290 };
  659 static const uint16_t rcl6[] =          /* 2 static turbo channels */
  660 { 5760, 5800 };
  661 static const uint16_t rcl6x[] = /* 4 FCC3 turbo channels */
  662 { 5540, 5580, 5620, 5660 };
  663 static const uint16_t rcl12[] = /* 2.4Ghz Turbo channel 6 */
  664 { 2437 };
  665 static const uint16_t rcl13[] = /* dynamic Turbo channels */
  666 { 5200, 5240, 5280, 5765, 5805 };
  667 #endif /* ATH_TURBO_SCAN */
  668 
  669 #define X(a)    .count = sizeof(a)/sizeof(a[0]), .list = a
  670 
  671 static const struct scanlist staScanTable[] = {
  672         { IEEE80211_MODE_11B,           X(rcl3) },
  673         { IEEE80211_MODE_11A,           X(rcl1) },
  674         { IEEE80211_MODE_11A,           X(rcl2) },
  675         { IEEE80211_MODE_11B,           X(rcl8) },
  676         { IEEE80211_MODE_11B,           X(rcl9) },
  677         { IEEE80211_MODE_11A,           X(rcl4) },
  678 #ifdef ATH_TURBO_SCAN
  679         { IEEE80211_MODE_STURBO_A,      X(rcl5) },
  680         { IEEE80211_MODE_STURBO_A,      X(rcl6) },
  681         { IEEE80211_MODE_TURBO_A,       X(rcl6x) },
  682         { IEEE80211_MODE_TURBO_A,       X(rcl13) },
  683 #endif /* ATH_TURBO_SCAN */
  684         { IEEE80211_MODE_11A,           X(rcl7) },
  685         { IEEE80211_MODE_11B,           X(rcl10) },
  686         { IEEE80211_MODE_11A,           X(rcl11) },
  687 #ifdef ATH_TURBO_SCAN
  688         { IEEE80211_MODE_TURBO_G,       X(rcl12) },
  689 #endif /* ATH_TURBO_SCAN */
  690         { .list = NULL }
  691 };
  692 
  693 /*
  694  * Start a station-mode scan by populating the channel list.
  695  */
  696 static int
  697 sta_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  698 {
  699         struct sta_table *st = ss->ss_priv;
  700 
  701         makescanlist(ss, vap, staScanTable);
  702 
  703         if (ss->ss_mindwell == 0)
  704                 ss->ss_mindwell = msecs_to_ticks(20);   /* 20ms */
  705         if (ss->ss_maxdwell == 0)
  706                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
  707 
  708         st->st_scangen++;
  709         st->st_newscan = 1;
  710 
  711         return 0;
  712 }
  713 
  714 /*
  715  * Restart a scan, typically a bg scan but can
  716  * also be a fg scan that came up empty.
  717  */
  718 static int
  719 sta_restart(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  720 {
  721         struct sta_table *st = ss->ss_priv;
  722 
  723         st->st_newscan = 1;
  724         return 0;
  725 }
  726 
  727 /*
  728  * Cancel an ongoing scan.
  729  */
  730 static int
  731 sta_cancel(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  732 {
  733         return 0;
  734 }
  735 
  736 /* unalligned little endian access */     
  737 #define LE_READ_2(p)                                    \
  738         ((uint16_t)                                     \
  739          ((((const uint8_t *)(p))[0]      ) |           \
  740           (((const uint8_t *)(p))[1] <<  8)))
  741  
  742 /*
  743  * Demote any supplied 11g channel to 11b.  There should
  744  * always be an 11b channel but we check anyway...
  745  */
  746 static struct ieee80211_channel *
  747 demote11b(struct ieee80211vap *vap, struct ieee80211_channel *chan)
  748 {
  749         struct ieee80211_channel *c;
  750 
  751         if (IEEE80211_IS_CHAN_ANYG(chan) &&
  752             vap->iv_des_mode == IEEE80211_MODE_AUTO) {
  753                 c = ieee80211_find_channel(vap->iv_ic, chan->ic_freq,
  754                     (chan->ic_flags &~ (IEEE80211_CHAN_PUREG | IEEE80211_CHAN_G)) |
  755                     IEEE80211_CHAN_B);
  756                 if (c != NULL)
  757                         chan = c;
  758         }
  759         return chan;
  760 }
  761 
  762 static int
  763 maxrate(const struct ieee80211_scan_entry *se)
  764 {
  765         const struct ieee80211_ie_htcap *htcap =
  766             (const struct ieee80211_ie_htcap *) se->se_ies.htcap_ie;
  767         int rmax, r, i, txstream;
  768         uint16_t caps;
  769         uint8_t txparams;
  770 
  771         rmax = 0;
  772         if (htcap != NULL) {
  773                 /*
  774                  * HT station; inspect supported MCS and then adjust
  775                  * rate by channel width.
  776                  */
  777                 txparams = htcap->hc_mcsset[12];
  778                 if (txparams & 0x3) {
  779                         /*
  780                          * TX MCS parameters defined and not equal to RX,
  781                          * extract the number of spartial streams and
  782                          * map it to the highest MCS rate.
  783                          */
  784                         txstream = ((txparams & 0xc) >> 2) + 1;
  785                         i = txstream * 8 - 1;
  786                 } else
  787                         for (i = 31; i >= 0 && isclr(htcap->hc_mcsset, i); i--);
  788                 if (i >= 0) {
  789                         caps = LE_READ_2(&htcap->hc_cap);
  790                         if ((caps & IEEE80211_HTCAP_CHWIDTH40) &&
  791                             (caps & IEEE80211_HTCAP_SHORTGI40))
  792                                 rmax = ieee80211_htrates[i].ht40_rate_400ns;
  793                         else if (caps & IEEE80211_HTCAP_CHWIDTH40)
  794                                 rmax = ieee80211_htrates[i].ht40_rate_800ns;
  795                         else if (caps & IEEE80211_HTCAP_SHORTGI20)
  796                                 rmax = ieee80211_htrates[i].ht20_rate_400ns;
  797                         else
  798                                 rmax = ieee80211_htrates[i].ht20_rate_800ns;
  799                 }
  800         }
  801         for (i = 0; i < se->se_rates[1]; i++) {
  802                 r = se->se_rates[2+i] & IEEE80211_RATE_VAL;
  803                 if (r > rmax)
  804                         rmax = r;
  805         }
  806         for (i = 0; i < se->se_xrates[1]; i++) {
  807                 r = se->se_xrates[2+i] & IEEE80211_RATE_VAL;
  808                 if (r > rmax)
  809                         rmax = r;
  810         }
  811         return rmax;
  812 }
  813 
  814 /*
  815  * Compare the capabilities of two entries and decide which is
  816  * more desirable (return >0 if a is considered better).  Note
  817  * that we assume compatibility/usability has already been checked
  818  * so we don't need to (e.g. validate whether privacy is supported).
  819  * Used to select the best scan candidate for association in a BSS.
  820  */
  821 static int
  822 sta_compare(const struct sta_entry *a, const struct sta_entry *b)
  823 {
  824 #define PREFER(_a,_b,_what) do {                        \
  825         if (((_a) ^ (_b)) & (_what))                    \
  826                 return ((_a) & (_what)) ? 1 : -1;       \
  827 } while (0)
  828         int maxa, maxb;
  829         int8_t rssia, rssib;
  830         int weight;
  831 
  832         /* privacy support */
  833         PREFER(a->base.se_capinfo, b->base.se_capinfo,
  834                 IEEE80211_CAPINFO_PRIVACY);
  835 
  836         /* compare count of previous failures */
  837         weight = b->se_fails - a->se_fails;
  838         if (abs(weight) > 1)
  839                 return weight;
  840 
  841         /*
  842          * Compare rssi.  If the two are considered equivalent
  843          * then fallback to other criteria.  We threshold the
  844          * comparisons to avoid selecting an ap purely by rssi
  845          * when both values may be good but one ap is otherwise
  846          * more desirable (e.g. an 11b-only ap with stronger
  847          * signal than an 11g ap).
  848          */
  849         rssia = MIN(a->base.se_rssi, STA_RSSI_MAX);
  850         rssib = MIN(b->base.se_rssi, STA_RSSI_MAX);
  851         if (abs(rssib - rssia) < 5) {
  852                 /* best/max rate preferred if signal level close enough XXX */
  853                 maxa = maxrate(&a->base);
  854                 maxb = maxrate(&b->base);
  855                 if (maxa != maxb)
  856                         return maxa - maxb;
  857                 /* XXX use freq for channel preference */
  858                 /* for now just prefer 5Ghz band to all other bands */
  859                 PREFER(IEEE80211_IS_CHAN_5GHZ(a->base.se_chan),
  860                        IEEE80211_IS_CHAN_5GHZ(b->base.se_chan), 1);
  861         }
  862         /* all things being equal, use signal level */
  863         return a->base.se_rssi - b->base.se_rssi;
  864 #undef PREFER
  865 }
  866 
  867 /*
  868  * Check rate set suitability and return the best supported rate.
  869  * XXX inspect MCS for HT
  870  */
  871 static int
  872 check_rate(struct ieee80211vap *vap, const struct ieee80211_channel *chan,
  873     const struct ieee80211_scan_entry *se)
  874 {
  875 #define RV(v)   ((v) & IEEE80211_RATE_VAL)
  876         const struct ieee80211_rateset *srs;
  877         int i, j, nrs, r, okrate, badrate, fixedrate, ucastrate;
  878         const uint8_t *rs;
  879 
  880         okrate = badrate = 0;
  881 
  882         srs = ieee80211_get_suprates(vap->iv_ic, chan);
  883         nrs = se->se_rates[1];
  884         rs = se->se_rates+2;
  885         /* XXX MCS */
  886         ucastrate = vap->iv_txparms[ieee80211_chan2mode(chan)].ucastrate;
  887         fixedrate = IEEE80211_FIXED_RATE_NONE;
  888 again:
  889         for (i = 0; i < nrs; i++) {
  890                 r = RV(rs[i]);
  891                 badrate = r;
  892                 /*
  893                  * Check any fixed rate is included. 
  894                  */
  895                 if (r == ucastrate)
  896                         fixedrate = r;
  897                 /*
  898                  * Check against our supported rates.
  899                  */
  900                 for (j = 0; j < srs->rs_nrates; j++)
  901                         if (r == RV(srs->rs_rates[j])) {
  902                                 if (r > okrate)         /* NB: track max */
  903                                         okrate = r;
  904                                 break;
  905                         }
  906 
  907                 if (j == srs->rs_nrates && (rs[i] & IEEE80211_RATE_BASIC)) {
  908                         /*
  909                          * Don't try joining a BSS, if we don't support
  910                          * one of its basic rates.
  911                          */
  912                         okrate = 0;
  913                         goto back;
  914                 }
  915         }
  916         if (rs == se->se_rates+2) {
  917                 /* scan xrates too; sort of an algol68-style for loop */
  918                 nrs = se->se_xrates[1];
  919                 rs = se->se_xrates+2;
  920                 goto again;
  921         }
  922 
  923 back:
  924         if (okrate == 0 || ucastrate != fixedrate)
  925                 return badrate | IEEE80211_RATE_BASIC;
  926         else
  927                 return RV(okrate);
  928 #undef RV
  929 }
  930 
  931 static __inline int
  932 match_id(const uint8_t *ie, const uint8_t *val, int len)
  933 {
  934         return (ie[1] == len && memcmp(ie+2, val, len) == 0);
  935 }
  936 
  937 static int
  938 match_ssid(const uint8_t *ie,
  939         int nssid, const struct ieee80211_scan_ssid ssids[])
  940 {
  941         int i;
  942 
  943         for (i = 0; i < nssid; i++) {
  944                 if (match_id(ie, ssids[i].ssid, ssids[i].len))
  945                         return 1;
  946         }
  947         return 0;
  948 }
  949 
  950 #ifdef IEEE80211_SUPPORT_TDMA
  951 static int
  952 tdma_isfull(const struct ieee80211_tdma_param *tdma)
  953 {
  954         int slot, slotcnt;
  955 
  956         slotcnt = tdma->tdma_slotcnt;
  957         for (slot = slotcnt-1; slot >= 0; slot--)
  958                 if (isclr(tdma->tdma_inuse, slot))
  959                         return 0;
  960         return 1;
  961 }
  962 #endif /* IEEE80211_SUPPORT_TDMA */
  963 
  964 /*
  965  * Test a scan candidate for suitability/compatibility.
  966  */
  967 static int
  968 match_bss(struct ieee80211vap *vap,
  969         const struct ieee80211_scan_state *ss, struct sta_entry *se0,
  970         int debug)
  971 {
  972         struct ieee80211com *ic = vap->iv_ic;
  973         struct ieee80211_scan_entry *se = &se0->base;
  974         uint8_t rate;
  975         int fail;
  976 
  977         fail = 0;
  978         if (isclr(ic->ic_chan_active, ieee80211_chan2ieee(ic, se->se_chan)))
  979                 fail |= MATCH_CHANNEL;
  980         /*
  981          * NB: normally the desired mode is used to construct
  982          * the channel list, but it's possible for the scan
  983          * cache to include entries for stations outside this
  984          * list so we check the desired mode here to weed them
  985          * out.
  986          */
  987         if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
  988             (se->se_chan->ic_flags & IEEE80211_CHAN_ALLTURBO) !=
  989             chanflags[vap->iv_des_mode])
  990                 fail |= MATCH_CHANNEL;
  991         if (vap->iv_opmode == IEEE80211_M_IBSS) {
  992                 if ((se->se_capinfo & IEEE80211_CAPINFO_IBSS) == 0)
  993                         fail |= MATCH_CAPINFO;
  994 #ifdef IEEE80211_SUPPORT_TDMA
  995         } else if (vap->iv_opmode == IEEE80211_M_AHDEMO) {
  996                 /*
  997                  * Adhoc demo network setup shouldn't really be scanning
  998                  * but just in case skip stations operating in IBSS or
  999                  * BSS mode.
 1000                  */
 1001                 if (se->se_capinfo & (IEEE80211_CAPINFO_IBSS|IEEE80211_CAPINFO_ESS))
 1002                         fail |= MATCH_CAPINFO;
 1003                 /*
 1004                  * TDMA operation cannot coexist with a normal 802.11 network;
 1005                  * skip if IBSS or ESS capabilities are marked and require
 1006                  * the beacon have a TDMA ie present.
 1007                  */
 1008                 if (vap->iv_caps & IEEE80211_C_TDMA) {
 1009                         const struct ieee80211_tdma_param *tdma =
 1010                             (const struct ieee80211_tdma_param *)se->se_ies.tdma_ie;
 1011                         const struct ieee80211_tdma_state *ts = vap->iv_tdma;
 1012 
 1013                         if (tdma == NULL)
 1014                                 fail |= MATCH_TDMA_NOIE;
 1015                         else if (tdma->tdma_version != ts->tdma_version)
 1016                                 fail |= MATCH_TDMA_VERSION;
 1017                         else if (tdma->tdma_slot != 0)
 1018                                 fail |= MATCH_TDMA_NOTMASTER;
 1019                         else if (tdma_isfull(tdma))
 1020                                 fail |= MATCH_TDMA_NOSLOT;
 1021 #if 0
 1022                         else if (ieee80211_local_address(se->se_macaddr))
 1023                                 fail |= MATCH_TDMA_LOCAL;
 1024 #endif
 1025                 }
 1026 #endif /* IEEE80211_SUPPORT_TDMA */
 1027 #ifdef IEEE80211_SUPPORT_MESH
 1028         } else if (vap->iv_opmode == IEEE80211_M_MBSS) {
 1029                 const struct ieee80211_mesh_state *ms = vap->iv_mesh;
 1030                 /*
 1031                  * Mesh nodes have IBSS & ESS bits in capinfo turned off
 1032                  * and two special ie's that must be present.
 1033                  */
 1034                 if (se->se_capinfo & (IEEE80211_CAPINFO_IBSS|IEEE80211_CAPINFO_ESS))
 1035                         fail |= MATCH_CAPINFO;
 1036                 else if (se->se_meshid[0] != IEEE80211_ELEMID_MESHID)
 1037                         fail |= MATCH_MESH_NOID;
 1038                 else if (ms->ms_idlen != 0 &&
 1039                     match_id(se->se_meshid, ms->ms_id, ms->ms_idlen))
 1040                         fail |= MATCH_MESHID;
 1041 #endif
 1042         } else {
 1043                 if ((se->se_capinfo & IEEE80211_CAPINFO_ESS) == 0)
 1044                         fail |= MATCH_CAPINFO;
 1045                 /*
 1046                  * If 11d is enabled and we're attempting to join a bss
 1047                  * that advertises it's country code then compare our
 1048                  * current settings to what we fetched from the country ie.
 1049                  * If our country code is unspecified or different then do
 1050                  * not attempt to join the bss.  We should have already
 1051                  * dispatched an event to user space that identifies the
 1052                  * new country code so our regdomain config should match.
 1053                  */
 1054                 if ((IEEE80211_IS_CHAN_11D(se->se_chan) ||
 1055                     (vap->iv_flags_ext & IEEE80211_FEXT_DOTD)) &&
 1056                     se->se_cc[0] != 0 &&
 1057                     (ic->ic_regdomain.country == CTRY_DEFAULT ||
 1058                      !isocmp(se->se_cc, ic->ic_regdomain.isocc)))
 1059                         fail |= MATCH_CC;
 1060         }
 1061         if (vap->iv_flags & IEEE80211_F_PRIVACY) {
 1062                 if ((se->se_capinfo & IEEE80211_CAPINFO_PRIVACY) == 0)
 1063                         fail |= MATCH_PRIVACY;
 1064         } else {
 1065                 /* XXX does this mean privacy is supported or required? */
 1066                 if (se->se_capinfo & IEEE80211_CAPINFO_PRIVACY)
 1067                         fail |= MATCH_PRIVACY;
 1068         }
 1069         se0->se_flags &= ~STA_DEMOTE11B;
 1070         rate = check_rate(vap, se->se_chan, se);
 1071         if (rate & IEEE80211_RATE_BASIC) {
 1072                 fail |= MATCH_RATE;
 1073                 /*
 1074                  * An 11b-only ap will give a rate mismatch if there is an
 1075                  * OFDM fixed tx rate for 11g.  Try downgrading the channel
 1076                  * in the scan list to 11b and retry the rate check.
 1077                  */
 1078                 if (IEEE80211_IS_CHAN_ANYG(se->se_chan)) {
 1079                         rate = check_rate(vap, demote11b(vap, se->se_chan), se);
 1080                         if ((rate & IEEE80211_RATE_BASIC) == 0) {
 1081                                 fail &= ~MATCH_RATE;
 1082                                 se0->se_flags |= STA_DEMOTE11B;
 1083                         }
 1084                 }
 1085         } else if (rate < 2*24) {
 1086                 /*
 1087                  * This is an 11b-only ap.  Check the desired mode in
 1088                  * case that needs to be honored (mode 11g filters out
 1089                  * 11b-only ap's).  Otherwise force any 11g channel used
 1090                  * in scanning to be demoted.
 1091                  *
 1092                  * NB: we cheat a bit here by looking at the max rate;
 1093                  *     we could/should check the rates.
 1094                  */
 1095                 if (!(vap->iv_des_mode == IEEE80211_MODE_AUTO ||
 1096                       vap->iv_des_mode == IEEE80211_MODE_11B))
 1097                         fail |= MATCH_RATE;
 1098                 else
 1099                         se0->se_flags |= STA_DEMOTE11B;
 1100         }
 1101         if (ss->ss_nssid != 0 &&
 1102             !match_ssid(se->se_ssid, ss->ss_nssid, ss->ss_ssid))
 1103                 fail |= MATCH_SSID;
 1104         if ((vap->iv_flags & IEEE80211_F_DESBSSID) &&
 1105             !IEEE80211_ADDR_EQ(vap->iv_des_bssid, se->se_bssid))
 1106                 fail |= MATCH_BSSID;
 1107         if (se0->se_fails >= STA_FAILS_MAX)
 1108                 fail |= MATCH_FAILS;
 1109         if (se0->se_notseen >= STA_PURGE_SCANS)
 1110                 fail |= MATCH_NOTSEEN;
 1111         if (se->se_rssi < STA_RSSI_MIN)
 1112                 fail |= MATCH_RSSI;
 1113 #ifdef IEEE80211_DEBUG
 1114         if (ieee80211_msg(vap, debug)) {
 1115                 printf(" %c %s",
 1116                     fail & MATCH_FAILS ? '=' :
 1117                     fail & MATCH_NOTSEEN ? '^' :
 1118                     fail & MATCH_CC ? '$' :
 1119 #ifdef IEEE80211_SUPPORT_TDMA
 1120                     fail & MATCH_TDMA_NOIE ? '&' :
 1121                     fail & MATCH_TDMA_VERSION ? 'v' :
 1122                     fail & MATCH_TDMA_NOTMASTER ? 's' :
 1123                     fail & MATCH_TDMA_NOSLOT ? 'f' :
 1124                     fail & MATCH_TDMA_LOCAL ? 'l' :
 1125 #endif
 1126                     fail & MATCH_MESH_NOID ? 'm' :
 1127                     fail ? '-' : '+', ether_sprintf(se->se_macaddr));
 1128                 printf(" %s%c", ether_sprintf(se->se_bssid),
 1129                     fail & MATCH_BSSID ? '!' : ' ');
 1130                 printf(" %3d%c", ieee80211_chan2ieee(ic, se->se_chan),
 1131                         fail & MATCH_CHANNEL ? '!' : ' ');
 1132                 printf(" %+4d%c", se->se_rssi, fail & MATCH_RSSI ? '!' : ' ');
 1133                 printf(" %2dM%c", (rate & IEEE80211_RATE_VAL) / 2,
 1134                     fail & MATCH_RATE ? '!' : ' ');
 1135                 printf(" %4s%c",
 1136                     (se->se_capinfo & IEEE80211_CAPINFO_ESS) ? "ess" :
 1137                     (se->se_capinfo & IEEE80211_CAPINFO_IBSS) ? "ibss" : "",
 1138                     fail & MATCH_CAPINFO ? '!' : ' ');
 1139                 printf(" %3s%c ",
 1140                     (se->se_capinfo & IEEE80211_CAPINFO_PRIVACY) ?
 1141                     "wep" : "no",
 1142                     fail & MATCH_PRIVACY ? '!' : ' ');
 1143                 ieee80211_print_essid(se->se_ssid+2, se->se_ssid[1]);
 1144                 printf("%s\n", fail & (MATCH_SSID | MATCH_MESHID) ? "!" : "");
 1145         }
 1146 #endif
 1147         return fail;
 1148 }
 1149 
 1150 static void
 1151 sta_update_notseen(struct sta_table *st)
 1152 {
 1153         struct sta_entry *se;
 1154 
 1155         IEEE80211_SCAN_TABLE_LOCK(st);
 1156         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1157                 /*
 1158                  * If seen the reset and don't bump the count;
 1159                  * otherwise bump the ``not seen'' count.  Note
 1160                  * that this insures that stations for which we
 1161                  * see frames while not scanning but not during
 1162                  * this scan will not be penalized.
 1163                  */
 1164                 if (se->se_seen)
 1165                         se->se_seen = 0;
 1166                 else
 1167                         se->se_notseen++;
 1168         }
 1169         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1170 }
 1171 
 1172 static void
 1173 sta_dec_fails(struct sta_table *st)
 1174 {
 1175         struct sta_entry *se;
 1176 
 1177         IEEE80211_SCAN_TABLE_LOCK(st);
 1178         TAILQ_FOREACH(se, &st->st_entry, se_list)
 1179                 if (se->se_fails)
 1180                         se->se_fails--;
 1181         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1182 }
 1183 
 1184 static struct sta_entry *
 1185 select_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap, int debug)
 1186 {
 1187         struct sta_table *st = ss->ss_priv;
 1188         struct sta_entry *se, *selbs = NULL;
 1189 
 1190         IEEE80211_DPRINTF(vap, debug, " %s\n",
 1191             "macaddr          bssid         chan  rssi  rate flag  wep  essid");
 1192         IEEE80211_SCAN_TABLE_LOCK(st);
 1193         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1194                 ieee80211_ies_expand(&se->base.se_ies);
 1195                 if (match_bss(vap, ss, se, debug) == 0) {
 1196                         if (selbs == NULL)
 1197                                 selbs = se;
 1198                         else if (sta_compare(se, selbs) > 0)
 1199                                 selbs = se;
 1200                 }
 1201         }
 1202         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1203 
 1204         return selbs;
 1205 }
 1206 
 1207 /*
 1208  * Pick an ap or ibss network to join or find a channel
 1209  * to use to start an ibss network.
 1210  */
 1211 static int
 1212 sta_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1213 {
 1214         struct sta_table *st = ss->ss_priv;
 1215         struct sta_entry *selbs;
 1216         struct ieee80211_channel *chan;
 1217 
 1218         KASSERT(vap->iv_opmode == IEEE80211_M_STA,
 1219                 ("wrong mode %u", vap->iv_opmode));
 1220 
 1221         if (st->st_newscan) {
 1222                 sta_update_notseen(st);
 1223                 st->st_newscan = 0;
 1224         }
 1225         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1226                 /*
 1227                  * Manual/background scan, don't select+join the
 1228                  * bss, just return.  The scanning framework will
 1229                  * handle notification that this has completed.
 1230                  */
 1231                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1232                 return 1;
 1233         }
 1234         /*
 1235          * Automatic sequencing; look for a candidate and
 1236          * if found join the network.
 1237          */
 1238         /* NB: unlocked read should be ok */
 1239         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1240                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1241                         "%s: no scan candidate\n", __func__);
 1242                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1243                         return 0;
 1244 notfound:
 1245                 /*
 1246                  * If nothing suitable was found decrement
 1247                  * the failure counts so entries will be
 1248                  * reconsidered the next time around.  We
 1249                  * really want to do this only for sta's
 1250                  * where we've previously had some success.
 1251                  */
 1252                 sta_dec_fails(st);
 1253                 st->st_newscan = 1;
 1254                 return 0;                       /* restart scan */
 1255         }
 1256         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1257         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1258                 return (selbs != NULL);
 1259         if (selbs == NULL)
 1260                 goto notfound;
 1261         chan = selbs->base.se_chan;
 1262         if (selbs->se_flags & STA_DEMOTE11B)
 1263                 chan = demote11b(vap, chan);
 1264         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1265                 goto notfound;
 1266         return 1;                               /* terminate scan */
 1267 }
 1268 
 1269 /*
 1270  * Lookup an entry in the scan cache.  We assume we're
 1271  * called from the bottom half or such that we don't need
 1272  * to block the bottom half so that it's safe to return
 1273  * a reference to an entry w/o holding the lock on the table.
 1274  */
 1275 static struct sta_entry *
 1276 sta_lookup(struct sta_table *st, const uint8_t macaddr[IEEE80211_ADDR_LEN])
 1277 {
 1278         struct sta_entry *se;
 1279         int hash = STA_HASH(macaddr);
 1280 
 1281         IEEE80211_SCAN_TABLE_LOCK(st);
 1282         LIST_FOREACH(se, &st->st_hash[hash], se_hash)
 1283                 if (IEEE80211_ADDR_EQ(se->base.se_macaddr, macaddr))
 1284                         break;
 1285         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1286 
 1287         return se;              /* NB: unlocked */
 1288 }
 1289 
 1290 static void
 1291 sta_roam_check(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1292 {
 1293         struct ieee80211com *ic = vap->iv_ic;
 1294         struct ieee80211_node *ni = vap->iv_bss;
 1295         struct sta_table *st = ss->ss_priv;
 1296         enum ieee80211_phymode mode;
 1297         struct sta_entry *se, *selbs;
 1298         uint8_t roamRate, curRate, ucastRate;
 1299         int8_t roamRssi, curRssi;
 1300 
 1301         se = sta_lookup(st, ni->ni_macaddr);
 1302         if (se == NULL) {
 1303                 /* XXX something is wrong */
 1304                 return;
 1305         }
 1306 
 1307         mode = ieee80211_chan2mode(ic->ic_bsschan);
 1308         roamRate = vap->iv_roamparms[mode].rate;
 1309         roamRssi = vap->iv_roamparms[mode].rssi;
 1310         ucastRate = vap->iv_txparms[mode].ucastrate;
 1311         /* NB: the most up to date rssi is in the node, not the scan cache */
 1312         curRssi = ic->ic_node_getrssi(ni);
 1313         if (ucastRate == IEEE80211_FIXED_RATE_NONE) {
 1314                 curRate = ni->ni_txrate;
 1315                 roamRate &= IEEE80211_RATE_VAL;
 1316                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_ROAM,
 1317                     "%s: currssi %d currate %u roamrssi %d roamrate %u\n",
 1318                     __func__, curRssi, curRate, roamRssi, roamRate);
 1319         } else {
 1320                 curRate = roamRate;     /* NB: insure compare below fails */
 1321                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_ROAM,
 1322                     "%s: currssi %d roamrssi %d\n", __func__, curRssi, roamRssi);
 1323         }
 1324         /*
 1325          * Check if a new ap should be used and switch.
 1326          * XXX deauth current ap
 1327          */
 1328         if (curRate < roamRate || curRssi < roamRssi) {
 1329                 if (time_after(ticks, ic->ic_lastscan + vap->iv_scanvalid)) {
 1330                         /*
 1331                          * Scan cache contents are too old; force a scan now
 1332                          * if possible so we have current state to make a
 1333                          * decision with.  We don't kick off a bg scan if
 1334                          * we're using dynamic turbo and boosted or if the
 1335                          * channel is busy.
 1336                          * XXX force immediate switch on scan complete
 1337                          */
 1338                         if (!IEEE80211_IS_CHAN_DTURBO(ic->ic_curchan) &&
 1339                             time_after(ticks, ic->ic_lastdata + vap->iv_bgscanidle))
 1340                                 ieee80211_bg_scan(vap, 0);
 1341                         return;
 1342                 }
 1343                 se->base.se_rssi = curRssi;
 1344                 selbs = select_bss(ss, vap, IEEE80211_MSG_ROAM);
 1345                 if (selbs != NULL && selbs != se) {
 1346                         struct ieee80211_channel *chan;
 1347 
 1348                         IEEE80211_DPRINTF(vap,
 1349                             IEEE80211_MSG_ROAM | IEEE80211_MSG_DEBUG,
 1350                             "%s: ROAM: curRate %u, roamRate %u, "
 1351                             "curRssi %d, roamRssi %d\n", __func__,
 1352                             curRate, roamRate, curRssi, roamRssi);
 1353 
 1354                         chan = selbs->base.se_chan;
 1355                         if (selbs->se_flags & STA_DEMOTE11B)
 1356                                 chan = demote11b(vap, chan);
 1357                         (void) ieee80211_sta_join(vap, chan, &selbs->base);
 1358                 }
 1359         }
 1360 }
 1361 
 1362 /*
 1363  * Age entries in the scan cache.
 1364  * XXX also do roaming since it's convenient
 1365  */
 1366 static void
 1367 sta_age(struct ieee80211_scan_state *ss)
 1368 {
 1369         struct ieee80211vap *vap = ss->ss_vap;
 1370 
 1371         adhoc_age(ss);
 1372         /*
 1373          * If rate control is enabled check periodically to see if
 1374          * we should roam from our current connection to one that
 1375          * might be better.  This only applies when we're operating
 1376          * in sta mode and automatic roaming is set.
 1377          * XXX defer if busy
 1378          * XXX repeater station
 1379          * XXX do when !bgscan?
 1380          */
 1381         KASSERT(vap->iv_opmode == IEEE80211_M_STA,
 1382                 ("wrong mode %u", vap->iv_opmode));
 1383         if (vap->iv_roaming == IEEE80211_ROAMING_AUTO &&
 1384             (vap->iv_flags & IEEE80211_F_BGSCAN) &&
 1385             vap->iv_state >= IEEE80211_S_RUN)
 1386                 /* XXX vap is implicit */
 1387                 sta_roam_check(ss, vap);
 1388 }
 1389 
 1390 /*
 1391  * Iterate over the entries in the scan cache, invoking
 1392  * the callback function on each one.
 1393  */
 1394 static void
 1395 sta_iterate(struct ieee80211_scan_state *ss, 
 1396         ieee80211_scan_iter_func *f, void *arg)
 1397 {
 1398         struct sta_table *st = ss->ss_priv;
 1399         struct sta_entry *se;
 1400         u_int gen;
 1401 
 1402         mtx_lock(&st->st_scanlock);
 1403         gen = st->st_scaniter++;
 1404 restart:
 1405         IEEE80211_SCAN_TABLE_LOCK(st);
 1406         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1407                 if (se->se_scangen != gen) {
 1408                         se->se_scangen = gen;
 1409                         /* update public state */
 1410                         se->base.se_age = ticks - se->se_lastupdate;
 1411                         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1412                         (*f)(arg, &se->base);
 1413                         goto restart;
 1414                 }
 1415         }
 1416         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1417 
 1418         mtx_unlock(&st->st_scanlock);
 1419 }
 1420 
 1421 static void
 1422 sta_assoc_fail(struct ieee80211_scan_state *ss,
 1423         const uint8_t macaddr[IEEE80211_ADDR_LEN], int reason)
 1424 {
 1425         struct sta_table *st = ss->ss_priv;
 1426         struct sta_entry *se;
 1427 
 1428         se = sta_lookup(st, macaddr);
 1429         if (se != NULL) {
 1430                 se->se_fails++;
 1431                 se->se_lastfail = ticks;
 1432                 IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
 1433                     macaddr, "%s: reason %u fails %u",
 1434                     __func__, reason, se->se_fails);
 1435         }
 1436 }
 1437 
 1438 static void
 1439 sta_assoc_success(struct ieee80211_scan_state *ss,
 1440         const uint8_t macaddr[IEEE80211_ADDR_LEN])
 1441 {
 1442         struct sta_table *st = ss->ss_priv;
 1443         struct sta_entry *se;
 1444 
 1445         se = sta_lookup(st, macaddr);
 1446         if (se != NULL) {
 1447 #if 0
 1448                 se->se_fails = 0;
 1449                 IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
 1450                     macaddr, "%s: fails %u",
 1451                     __func__, se->se_fails);
 1452 #endif
 1453                 se->se_lastassoc = ticks;
 1454         }
 1455 }
 1456 
 1457 static const struct ieee80211_scanner sta_default = {
 1458         .scan_name              = "default",
 1459         .scan_attach            = sta_attach,
 1460         .scan_detach            = sta_detach,
 1461         .scan_start             = sta_start,
 1462         .scan_restart           = sta_restart,
 1463         .scan_cancel            = sta_cancel,
 1464         .scan_end               = sta_pick_bss,
 1465         .scan_flush             = sta_flush,
 1466         .scan_add               = sta_add,
 1467         .scan_age               = sta_age,
 1468         .scan_iterate           = sta_iterate,
 1469         .scan_assoc_fail        = sta_assoc_fail,
 1470         .scan_assoc_success     = sta_assoc_success,
 1471 };
 1472 IEEE80211_SCANNER_ALG(sta, IEEE80211_M_STA, sta_default);
 1473 
 1474 /*
 1475  * Adhoc mode-specific support.
 1476  */
 1477 
 1478 static const uint16_t adhocWorld[] =            /* 36, 40, 44, 48 */
 1479 { 5180, 5200, 5220, 5240 };
 1480 static const uint16_t adhocFcc3[] =             /* 36, 40, 44, 48 145, 149, 153, 157, 161, 165 */
 1481 { 5180, 5200, 5220, 5240, 5725, 5745, 5765, 5785, 5805, 5825 };
 1482 static const uint16_t adhocMkk[] =              /* 34, 38, 42, 46 */
 1483 { 5170, 5190, 5210, 5230 };
 1484 static const uint16_t adhoc11b[] =              /* 10, 11 */
 1485 { 2457, 2462 };
 1486 
 1487 static const struct scanlist adhocScanTable[] = {
 1488         { IEEE80211_MODE_11B,           X(adhoc11b) },
 1489         { IEEE80211_MODE_11A,           X(adhocWorld) },
 1490         { IEEE80211_MODE_11A,           X(adhocFcc3) },
 1491         { IEEE80211_MODE_11B,           X(adhocMkk) },
 1492         { .list = NULL }
 1493 };
 1494 #undef X
 1495 
 1496 /*
 1497  * Start an adhoc-mode scan by populating the channel list.
 1498  */
 1499 static int
 1500 adhoc_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1501 {
 1502         struct sta_table *st = ss->ss_priv;
 1503         
 1504         makescanlist(ss, vap, adhocScanTable);
 1505 
 1506         if (ss->ss_mindwell == 0)
 1507                 ss->ss_mindwell = msecs_to_ticks(200);  /* 200ms */
 1508         if (ss->ss_maxdwell == 0)
 1509                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
 1510 
 1511         st->st_scangen++;
 1512         st->st_newscan = 1;
 1513 
 1514         return 0;
 1515 }
 1516 
 1517 /*
 1518  * Select a channel to start an adhoc network on.
 1519  * The channel list was populated with appropriate
 1520  * channels so select one that looks least occupied.
 1521  */
 1522 static struct ieee80211_channel *
 1523 adhoc_pick_channel(struct ieee80211_scan_state *ss, int flags)
 1524 {
 1525         struct sta_table *st = ss->ss_priv;
 1526         struct sta_entry *se;
 1527         struct ieee80211_channel *c, *bestchan;
 1528         int i, bestrssi, maxrssi;
 1529 
 1530         bestchan = NULL;
 1531         bestrssi = -1;
 1532 
 1533         IEEE80211_SCAN_TABLE_LOCK(st);
 1534         for (i = 0; i < ss->ss_last; i++) {
 1535                 c = ss->ss_chans[i];
 1536                 /* never consider a channel with radar */
 1537                 if (IEEE80211_IS_CHAN_RADAR(c))
 1538                         continue;
 1539                 /* skip channels disallowed by regulatory settings */
 1540                 if (IEEE80211_IS_CHAN_NOADHOC(c))
 1541                         continue;
 1542                 /* check channel attributes for band compatibility */
 1543                 if (flags != 0 && (c->ic_flags & flags) != flags)
 1544                         continue;
 1545                 maxrssi = 0;
 1546                 TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1547                         if (se->base.se_chan != c)
 1548                                 continue;
 1549                         if (se->base.se_rssi > maxrssi)
 1550                                 maxrssi = se->base.se_rssi;
 1551                 }
 1552                 if (bestchan == NULL || maxrssi < bestrssi)
 1553                         bestchan = c;
 1554         }
 1555         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1556 
 1557         return bestchan;
 1558 }
 1559 
 1560 /*
 1561  * Pick an ibss network to join or find a channel
 1562  * to use to start an ibss network.
 1563  */
 1564 static int
 1565 adhoc_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1566 {
 1567         struct sta_table *st = ss->ss_priv;
 1568         struct sta_entry *selbs;
 1569         struct ieee80211_channel *chan;
 1570 
 1571         KASSERT(vap->iv_opmode == IEEE80211_M_IBSS ||
 1572                 vap->iv_opmode == IEEE80211_M_AHDEMO ||
 1573                 vap->iv_opmode == IEEE80211_M_MBSS,
 1574                 ("wrong opmode %u", vap->iv_opmode));
 1575 
 1576         if (st->st_newscan) {
 1577                 sta_update_notseen(st);
 1578                 st->st_newscan = 0;
 1579         }
 1580         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1581                 /*
 1582                  * Manual/background scan, don't select+join the
 1583                  * bss, just return.  The scanning framework will
 1584                  * handle notification that this has completed.
 1585                  */
 1586                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1587                 return 1;
 1588         }
 1589         /*
 1590          * Automatic sequencing; look for a candidate and
 1591          * if found join the network.
 1592          */
 1593         /* NB: unlocked read should be ok */
 1594         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1595                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1596                         "%s: no scan candidate\n", __func__);
 1597                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1598                         return 0;
 1599 notfound:
 1600                 /* NB: never auto-start a tdma network for slot !0 */
 1601 #ifdef IEEE80211_SUPPORT_TDMA
 1602                 if (vap->iv_des_nssid &&
 1603                     ((vap->iv_caps & IEEE80211_C_TDMA) == 0 ||
 1604                      ieee80211_tdma_getslot(vap) == 0)) {
 1605 #else
 1606                 if (vap->iv_des_nssid) {
 1607 #endif
 1608                         /*
 1609                          * No existing adhoc network to join and we have
 1610                          * an ssid; start one up.  If no channel was
 1611                          * specified, try to select a channel.
 1612                          */
 1613                         if (vap->iv_des_chan == IEEE80211_CHAN_ANYC ||
 1614                             IEEE80211_IS_CHAN_RADAR(vap->iv_des_chan)) {
 1615                                 struct ieee80211com *ic = vap->iv_ic;
 1616 
 1617                                 chan = adhoc_pick_channel(ss, 0);
 1618                                 if (chan != NULL)
 1619                                         chan = ieee80211_ht_adjust_channel(ic,
 1620                                             chan, vap->iv_flags_ht);
 1621                         } else
 1622                                 chan = vap->iv_des_chan;
 1623                         if (chan != NULL) {
 1624                                 ieee80211_create_ibss(vap, chan);
 1625                                 return 1;
 1626                         }
 1627                 }
 1628                 /*
 1629                  * If nothing suitable was found decrement
 1630                  * the failure counts so entries will be
 1631                  * reconsidered the next time around.  We
 1632                  * really want to do this only for sta's
 1633                  * where we've previously had some success.
 1634                  */
 1635                 sta_dec_fails(st);
 1636                 st->st_newscan = 1;
 1637                 return 0;                       /* restart scan */
 1638         }
 1639         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1640         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1641                 return (selbs != NULL);
 1642         if (selbs == NULL)
 1643                 goto notfound;
 1644         chan = selbs->base.se_chan;
 1645         if (selbs->se_flags & STA_DEMOTE11B)
 1646                 chan = demote11b(vap, chan);
 1647         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1648                 goto notfound;
 1649         return 1;                               /* terminate scan */
 1650 }
 1651 
 1652 /*
 1653  * Age entries in the scan cache.
 1654  */
 1655 static void
 1656 adhoc_age(struct ieee80211_scan_state *ss)
 1657 {
 1658         struct sta_table *st = ss->ss_priv;
 1659         struct sta_entry *se, *next;
 1660 
 1661         IEEE80211_SCAN_TABLE_LOCK(st);
 1662         TAILQ_FOREACH_SAFE(se, &st->st_entry, se_list, next) {
 1663                 if (se->se_notseen > STA_PURGE_SCANS) {
 1664                         TAILQ_REMOVE(&st->st_entry, se, se_list);
 1665                         LIST_REMOVE(se, se_hash);
 1666                         ieee80211_ies_cleanup(&se->base.se_ies);
 1667                         free(se, M_80211_SCAN);
 1668                 }
 1669         }
 1670         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1671 }
 1672 
 1673 static const struct ieee80211_scanner adhoc_default = {
 1674         .scan_name              = "default",
 1675         .scan_attach            = sta_attach,
 1676         .scan_detach            = sta_detach,
 1677         .scan_start             = adhoc_start,
 1678         .scan_restart           = sta_restart,
 1679         .scan_cancel            = sta_cancel,
 1680         .scan_end               = adhoc_pick_bss,
 1681         .scan_flush             = sta_flush,
 1682         .scan_pickchan          = adhoc_pick_channel,
 1683         .scan_add               = sta_add,
 1684         .scan_age               = adhoc_age,
 1685         .scan_iterate           = sta_iterate,
 1686         .scan_assoc_fail        = sta_assoc_fail,
 1687         .scan_assoc_success     = sta_assoc_success,
 1688 };
 1689 IEEE80211_SCANNER_ALG(ibss, IEEE80211_M_IBSS, adhoc_default);
 1690 IEEE80211_SCANNER_ALG(ahdemo, IEEE80211_M_AHDEMO, adhoc_default);
 1691 
 1692 static void
 1693 ap_force_promisc(struct ieee80211com *ic)
 1694 {
 1695         struct ifnet *ifp = ic->ic_ifp;
 1696 
 1697         IEEE80211_LOCK(ic);
 1698         /* set interface into promiscuous mode */
 1699         ifp->if_flags |= IFF_PROMISC;
 1700         ieee80211_runtask(ic, &ic->ic_promisc_task);
 1701         IEEE80211_UNLOCK(ic);
 1702 }
 1703 
 1704 static void
 1705 ap_reset_promisc(struct ieee80211com *ic)
 1706 {
 1707         IEEE80211_LOCK(ic);
 1708         ieee80211_syncifflag_locked(ic, IFF_PROMISC);
 1709         IEEE80211_UNLOCK(ic);
 1710 }
 1711 
 1712 static int
 1713 ap_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1714 {
 1715         struct sta_table *st = ss->ss_priv;
 1716 
 1717         makescanlist(ss, vap, staScanTable);
 1718 
 1719         if (ss->ss_mindwell == 0)
 1720                 ss->ss_mindwell = msecs_to_ticks(200);  /* 200ms */
 1721         if (ss->ss_maxdwell == 0)
 1722                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
 1723 
 1724         st->st_scangen++;
 1725         st->st_newscan = 1;
 1726 
 1727         ap_force_promisc(vap->iv_ic);
 1728         return 0;
 1729 }
 1730 
 1731 /*
 1732  * Cancel an ongoing scan.
 1733  */
 1734 static int
 1735 ap_cancel(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1736 {
 1737         ap_reset_promisc(vap->iv_ic);
 1738         return 0;
 1739 }
 1740 
 1741 /*
 1742  * Pick a quiet channel to use for ap operation.
 1743  */
 1744 static struct ieee80211_channel *
 1745 ap_pick_channel(struct ieee80211_scan_state *ss, int flags)
 1746 {
 1747         struct sta_table *st = ss->ss_priv;
 1748         struct ieee80211_channel *bestchan = NULL;
 1749         int i;
 1750 
 1751         /* XXX select channel more intelligently, e.g. channel spread, power */
 1752         /* NB: use scan list order to preserve channel preference */
 1753         for (i = 0; i < ss->ss_last; i++) {
 1754                 struct ieee80211_channel *chan = ss->ss_chans[i];
 1755                 /*
 1756                  * If the channel is unoccupied the max rssi
 1757                  * should be zero; just take it.  Otherwise
 1758                  * track the channel with the lowest rssi and
 1759                  * use that when all channels appear occupied.
 1760                  */
 1761                 if (IEEE80211_IS_CHAN_RADAR(chan))
 1762                         continue;
 1763                 if (IEEE80211_IS_CHAN_NOHOSTAP(chan))
 1764                         continue;
 1765                 /* check channel attributes for band compatibility */
 1766                 if (flags != 0 && (chan->ic_flags & flags) != flags)
 1767                         continue;
 1768                 KASSERT(sizeof(chan->ic_ieee) == 1, ("ic_chan size"));
 1769                 /* XXX channel have interference */
 1770                 if (st->st_maxrssi[chan->ic_ieee] == 0) {
 1771                         /* XXX use other considerations */
 1772                         return chan;
 1773                 }
 1774                 if (bestchan == NULL ||
 1775                     st->st_maxrssi[chan->ic_ieee] < st->st_maxrssi[bestchan->ic_ieee])
 1776                         bestchan = chan;
 1777         }
 1778         return bestchan;
 1779 }
 1780 
 1781 /*
 1782  * Pick a quiet channel to use for ap operation.
 1783  */
 1784 static int
 1785 ap_end(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1786 {
 1787         struct ieee80211com *ic = vap->iv_ic;
 1788         struct ieee80211_channel *bestchan;
 1789 
 1790         KASSERT(vap->iv_opmode == IEEE80211_M_HOSTAP,
 1791                 ("wrong opmode %u", vap->iv_opmode));
 1792         bestchan = ap_pick_channel(ss, 0);
 1793         if (bestchan == NULL) {
 1794                 /* no suitable channel, should not happen */
 1795                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1796                     "%s: no suitable channel! (should not happen)\n", __func__);
 1797                 /* XXX print something? */
 1798                 return 0;                       /* restart scan */
 1799         }
 1800         /*
 1801          * If this is a dynamic turbo channel, start with the unboosted one.
 1802          */
 1803         if (IEEE80211_IS_CHAN_TURBO(bestchan)) {
 1804                 bestchan = ieee80211_find_channel(ic, bestchan->ic_freq,
 1805                         bestchan->ic_flags & ~IEEE80211_CHAN_TURBO);
 1806                 if (bestchan == NULL) {
 1807                         /* should never happen ?? */
 1808                         return 0;
 1809                 }
 1810         }
 1811         ap_reset_promisc(ic);
 1812         if (ss->ss_flags & (IEEE80211_SCAN_NOPICK | IEEE80211_SCAN_NOJOIN)) {
 1813                 /*
 1814                  * Manual/background scan, don't select+join the
 1815                  * bss, just return.  The scanning framework will
 1816                  * handle notification that this has completed.
 1817                  */
 1818                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1819                 return 1;
 1820         }
 1821         ieee80211_create_ibss(vap,
 1822             ieee80211_ht_adjust_channel(ic, bestchan, vap->iv_flags_ht));
 1823         return 1;
 1824 }
 1825 
 1826 static const struct ieee80211_scanner ap_default = {
 1827         .scan_name              = "default",
 1828         .scan_attach            = sta_attach,
 1829         .scan_detach            = sta_detach,
 1830         .scan_start             = ap_start,
 1831         .scan_restart           = sta_restart,
 1832         .scan_cancel            = ap_cancel,
 1833         .scan_end               = ap_end,
 1834         .scan_flush             = sta_flush,
 1835         .scan_pickchan          = ap_pick_channel,
 1836         .scan_add               = sta_add,
 1837         .scan_age               = adhoc_age,
 1838         .scan_iterate           = sta_iterate,
 1839         .scan_assoc_success     = sta_assoc_success,
 1840         .scan_assoc_fail        = sta_assoc_fail,
 1841 };
 1842 IEEE80211_SCANNER_ALG(ap, IEEE80211_M_HOSTAP, ap_default);
 1843 
 1844 #ifdef IEEE80211_SUPPORT_MESH
 1845 /*
 1846  * Pick an mbss network to join or find a channel
 1847  * to use to start an mbss network.
 1848  */
 1849 static int
 1850 mesh_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1851 {
 1852         struct sta_table *st = ss->ss_priv;
 1853         struct ieee80211_mesh_state *ms = vap->iv_mesh;
 1854         struct sta_entry *selbs;
 1855         struct ieee80211_channel *chan;
 1856 
 1857         KASSERT(vap->iv_opmode == IEEE80211_M_MBSS,
 1858                 ("wrong opmode %u", vap->iv_opmode));
 1859 
 1860         if (st->st_newscan) {
 1861                 sta_update_notseen(st);
 1862                 st->st_newscan = 0;
 1863         }
 1864         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1865                 /*
 1866                  * Manual/background scan, don't select+join the
 1867                  * bss, just return.  The scanning framework will
 1868                  * handle notification that this has completed.
 1869                  */
 1870                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1871                 return 1;
 1872         }
 1873         /*
 1874          * Automatic sequencing; look for a candidate and
 1875          * if found join the network.
 1876          */
 1877         /* NB: unlocked read should be ok */
 1878         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1879                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1880                         "%s: no scan candidate\n", __func__);
 1881                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1882                         return 0;
 1883 notfound:
 1884                 if (ms->ms_idlen != 0) {
 1885                         /*
 1886                          * No existing mbss network to join and we have
 1887                          * a meshid; start one up.  If no channel was
 1888                          * specified, try to select a channel.
 1889                          */
 1890                         if (vap->iv_des_chan == IEEE80211_CHAN_ANYC ||
 1891                             IEEE80211_IS_CHAN_RADAR(vap->iv_des_chan)) {
 1892                                 struct ieee80211com *ic = vap->iv_ic;
 1893 
 1894                                 chan = adhoc_pick_channel(ss, 0);
 1895                                 if (chan != NULL)
 1896                                         chan = ieee80211_ht_adjust_channel(ic,
 1897                                             chan, vap->iv_flags_ht);
 1898                         } else
 1899                                 chan = vap->iv_des_chan;
 1900                         if (chan != NULL) {
 1901                                 ieee80211_create_ibss(vap, chan);
 1902                                 return 1;
 1903                         }
 1904                 }
 1905                 /*
 1906                  * If nothing suitable was found decrement
 1907                  * the failure counts so entries will be
 1908                  * reconsidered the next time around.  We
 1909                  * really want to do this only for sta's
 1910                  * where we've previously had some success.
 1911                  */
 1912                 sta_dec_fails(st);
 1913                 st->st_newscan = 1;
 1914                 return 0;                       /* restart scan */
 1915         }
 1916         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1917         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1918                 return (selbs != NULL);
 1919         if (selbs == NULL)
 1920                 goto notfound;
 1921         chan = selbs->base.se_chan;
 1922         if (selbs->se_flags & STA_DEMOTE11B)
 1923                 chan = demote11b(vap, chan);
 1924         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1925                 goto notfound;
 1926         return 1;                               /* terminate scan */
 1927 }
 1928 
 1929 static const struct ieee80211_scanner mesh_default = {
 1930         .scan_name              = "default",
 1931         .scan_attach            = sta_attach,
 1932         .scan_detach            = sta_detach,
 1933         .scan_start             = adhoc_start,
 1934         .scan_restart           = sta_restart,
 1935         .scan_cancel            = sta_cancel,
 1936         .scan_end               = mesh_pick_bss,
 1937         .scan_flush             = sta_flush,
 1938         .scan_pickchan          = adhoc_pick_channel,
 1939         .scan_add               = sta_add,
 1940         .scan_age               = adhoc_age,
 1941         .scan_iterate           = sta_iterate,
 1942         .scan_assoc_fail        = sta_assoc_fail,
 1943         .scan_assoc_success     = sta_assoc_success,
 1944 };
 1945 IEEE80211_SCANNER_ALG(mesh, IEEE80211_M_MBSS, mesh_default);
 1946 #endif /* IEEE80211_SUPPORT_MESH */

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