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  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2002-2009 Sam Leffler, Errno Consulting
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   26  */
   27 
   28 #include <sys/cdefs.h>
   29 __FBSDID("$FreeBSD$");
   30 
   31 /*
   32  * IEEE 802.11 station scanning support.
   33  */
   34 #include "opt_wlan.h"
   35 
   36 #include <sys/param.h>
   37 #include <sys/systm.h>
   38 #include <sys/kernel.h>
   39 #include <sys/endian.h>
   40 #include <sys/malloc.h>
   41 #include <sys/module.h>
   42 
   43 #include <sys/socket.h>
   44 
   45 #include <net/if.h>
   46 #include <net/if_var.h>
   47 #include <net/if_media.h>
   48 #include <net/ethernet.h>
   49 
   50 #include <net80211/ieee80211_var.h>
   51 #include <net80211/ieee80211_input.h>
   52 #include <net80211/ieee80211_regdomain.h>
   53 #ifdef IEEE80211_SUPPORT_TDMA
   54 #include <net80211/ieee80211_tdma.h>
   55 #endif
   56 #ifdef IEEE80211_SUPPORT_MESH
   57 #include <net80211/ieee80211_mesh.h>
   58 #endif
   59 #include <net80211/ieee80211_ratectl.h>
   60 #include <net80211/ieee80211_vht.h>
   61 
   62 #include <net/bpf.h>
   63 
   64 /*
   65  * Parameters for managing cache entries:
   66  *
   67  * o a station with STA_FAILS_MAX failures is not considered
   68  *   when picking a candidate
   69  * o a station that hasn't had an update in STA_PURGE_SCANS
   70  *   (background) scans is discarded
   71  * o after STA_FAILS_AGE seconds we clear the failure count
   72  */
   73 #define STA_FAILS_MAX   2               /* assoc failures before ignored */
   74 #define STA_FAILS_AGE   (2*60)          /* time before clearing fails (secs) */
   75 #define STA_PURGE_SCANS 2               /* age for purging entries (scans) */
   76 
   77 /* XXX tunable */
   78 #define STA_RSSI_MIN    8               /* min acceptable rssi */
   79 #define STA_RSSI_MAX    40              /* max rssi for comparison */
   80 
   81 struct sta_entry {
   82         struct ieee80211_scan_entry base;
   83         TAILQ_ENTRY(sta_entry) se_list;
   84         LIST_ENTRY(sta_entry) se_hash;
   85         uint8_t         se_fails;               /* failure to associate count */
   86         uint8_t         se_seen;                /* seen during current scan */
   87         uint8_t         se_notseen;             /* not seen in previous scans */
   88         uint8_t         se_flags;
   89 #define STA_DEMOTE11B   0x01                    /* match w/ demoted 11b chan */
   90         uint32_t        se_avgrssi;             /* LPF rssi state */
   91         unsigned long   se_lastupdate;          /* time of last update */
   92         unsigned long   se_lastfail;            /* time of last failure */
   93         unsigned long   se_lastassoc;           /* time of last association */
   94         u_int           se_scangen;             /* iterator scan gen# */
   95         u_int           se_countrygen;          /* gen# of last cc notify */
   96 };
   97 
   98 #define STA_HASHSIZE    32
   99 /* simple hash is enough for variation of macaddr */
  100 #define STA_HASH(addr)  \
  101         (((const uint8_t *)(addr))[IEEE80211_ADDR_LEN - 1] % STA_HASHSIZE)
  102 
  103 #define MAX_IEEE_CHAN   256                     /* max acceptable IEEE chan # */
  104 CTASSERT(MAX_IEEE_CHAN >= 256);
  105 
  106 struct sta_table {
  107         ieee80211_scan_table_lock_t st_lock;    /* on scan table */
  108         TAILQ_HEAD(, sta_entry) st_entry;       /* all entries */
  109         LIST_HEAD(, sta_entry) st_hash[STA_HASHSIZE];
  110         ieee80211_scan_iter_lock_t st_scanlock;         /* on st_scaniter */
  111         u_int           st_scaniter;            /* gen# for iterator */
  112         u_int           st_scangen;             /* scan generation # */
  113         int             st_newscan;
  114         /* ap-related state */
  115         int             st_maxrssi[MAX_IEEE_CHAN];
  116 };
  117 
  118 static void sta_flush_table(struct sta_table *);
  119 /*
  120  * match_bss returns a bitmask describing if an entry is suitable
  121  * for use.  If non-zero the entry was deemed not suitable and it's
  122  * contents explains why.  The following flags are or'd to this
  123  * mask and can be used to figure out why the entry was rejected.
  124  */
  125 #define MATCH_CHANNEL           0x00001 /* channel mismatch */
  126 #define MATCH_CAPINFO           0x00002 /* capabilities mismatch, e.g. no ess */
  127 #define MATCH_PRIVACY           0x00004 /* privacy mismatch */
  128 #define MATCH_RATE              0x00008 /* rate set mismatch */
  129 #define MATCH_SSID              0x00010 /* ssid mismatch */
  130 #define MATCH_BSSID             0x00020 /* bssid mismatch */
  131 #define MATCH_FAILS             0x00040 /* too many failed auth attempts */
  132 #define MATCH_NOTSEEN           0x00080 /* not seen in recent scans */
  133 #define MATCH_RSSI              0x00100 /* rssi deemed too low to use */
  134 #define MATCH_CC                0x00200 /* country code mismatch */
  135 #ifdef IEEE80211_SUPPORT_TDMA
  136 #define MATCH_TDMA_NOIE         0x00400 /* no TDMA ie */
  137 #define MATCH_TDMA_NOTMASTER    0x00800 /* not TDMA master */
  138 #define MATCH_TDMA_NOSLOT       0x01000 /* all TDMA slots occupied */
  139 #define MATCH_TDMA_LOCAL        0x02000 /* local address */
  140 #define MATCH_TDMA_VERSION      0x04000 /* protocol version mismatch */
  141 #endif
  142 #define MATCH_MESH_NOID         0x10000 /* no MESHID ie */
  143 #define MATCH_MESHID            0x20000 /* meshid mismatch */
  144 static int match_bss(struct ieee80211vap *,
  145         const struct ieee80211_scan_state *, struct sta_entry *, int);
  146 static void adhoc_age(struct ieee80211_scan_state *);
  147 
  148 static __inline int
  149 isocmp(const uint8_t cc1[], const uint8_t cc2[])
  150 {
  151      return (cc1[0] == cc2[0] && cc1[1] == cc2[1]);
  152 }
  153 
  154 /* number of references from net80211 layer */
  155 static  int nrefs = 0;
  156 /*
  157  * Module glue.
  158  */
  159 IEEE80211_SCANNER_MODULE(sta, 1);
  160 
  161 /*
  162  * Attach prior to any scanning work.
  163  */
  164 static int
  165 sta_attach(struct ieee80211_scan_state *ss)
  166 {
  167         struct sta_table *st;
  168 
  169         st = (struct sta_table *) IEEE80211_MALLOC(sizeof(struct sta_table),
  170                 M_80211_SCAN,
  171                 IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
  172         if (st == NULL)
  173                 return 0;
  174         IEEE80211_SCAN_TABLE_LOCK_INIT(st, "scantable");
  175         IEEE80211_SCAN_ITER_LOCK_INIT(st, "scangen");
  176         TAILQ_INIT(&st->st_entry);
  177         ss->ss_priv = st;
  178         nrefs++;                        /* NB: we assume caller locking */
  179         return 1;
  180 }
  181 
  182 /*
  183  * Cleanup any private state.
  184  */
  185 static int
  186 sta_detach(struct ieee80211_scan_state *ss)
  187 {
  188         struct sta_table *st = ss->ss_priv;
  189 
  190         if (st != NULL) {
  191                 sta_flush_table(st);
  192                 IEEE80211_SCAN_TABLE_LOCK_DESTROY(st);
  193                 IEEE80211_SCAN_ITER_LOCK_DESTROY(st);
  194                 IEEE80211_FREE(st, M_80211_SCAN);
  195                 KASSERT(nrefs > 0, ("imbalanced attach/detach"));
  196                 nrefs--;                /* NB: we assume caller locking */
  197         }
  198         return 1;
  199 }
  200 
  201 /*
  202  * Flush all per-scan state.
  203  */
  204 static int
  205 sta_flush(struct ieee80211_scan_state *ss)
  206 {
  207         struct sta_table *st = ss->ss_priv;
  208 
  209         IEEE80211_SCAN_TABLE_LOCK(st);
  210         sta_flush_table(st);
  211         IEEE80211_SCAN_TABLE_UNLOCK(st);
  212         ss->ss_last = 0;
  213         return 0;
  214 }
  215 
  216 /*
  217  * Flush all entries in the scan cache.
  218  */
  219 static void
  220 sta_flush_table(struct sta_table *st)
  221 {
  222         struct sta_entry *se, *next;
  223 
  224         TAILQ_FOREACH_SAFE(se, &st->st_entry, se_list, next) {
  225                 TAILQ_REMOVE(&st->st_entry, se, se_list);
  226                 LIST_REMOVE(se, se_hash);
  227                 ieee80211_ies_cleanup(&se->base.se_ies);
  228                 IEEE80211_FREE(se, M_80211_SCAN);
  229         }
  230         memset(st->st_maxrssi, 0, sizeof(st->st_maxrssi));
  231 }
  232 
  233 /*
  234  * Process a beacon or probe response frame; create an
  235  * entry in the scan cache or update any previous entry.
  236  */
  237 static int
  238 sta_add(struct ieee80211_scan_state *ss, 
  239         struct ieee80211_channel *curchan,
  240         const struct ieee80211_scanparams *sp,
  241         const struct ieee80211_frame *wh,
  242         int subtype, int rssi, int noise)
  243 {
  244 #define ISPROBE(_st)    ((_st) == IEEE80211_FC0_SUBTYPE_PROBE_RESP)
  245 #define PICK1ST(_ss) \
  246         ((ss->ss_flags & (IEEE80211_SCAN_PICK1ST | IEEE80211_SCAN_GOTPICK)) == \
  247         IEEE80211_SCAN_PICK1ST)
  248         struct sta_table *st = ss->ss_priv;
  249         const uint8_t *macaddr = wh->i_addr2;
  250         struct ieee80211vap *vap = ss->ss_vap;
  251         struct ieee80211com *ic = vap->iv_ic;
  252         struct ieee80211_channel *c;
  253         struct sta_entry *se;
  254         struct ieee80211_scan_entry *ise;
  255         int hash;
  256 
  257         hash = STA_HASH(macaddr);
  258 
  259         IEEE80211_SCAN_TABLE_LOCK(st);
  260         LIST_FOREACH(se, &st->st_hash[hash], se_hash)
  261                 if (IEEE80211_ADDR_EQ(se->base.se_macaddr, macaddr))
  262                         goto found;
  263         se = (struct sta_entry *) IEEE80211_MALLOC(sizeof(struct sta_entry),
  264                 M_80211_SCAN, IEEE80211_M_NOWAIT | IEEE80211_M_ZERO);
  265         if (se == NULL) {
  266                 IEEE80211_SCAN_TABLE_UNLOCK(st);
  267                 return 0;
  268         }
  269         se->se_scangen = st->st_scaniter-1;
  270         se->se_avgrssi = IEEE80211_RSSI_DUMMY_MARKER;
  271         IEEE80211_ADDR_COPY(se->base.se_macaddr, macaddr);
  272         TAILQ_INSERT_TAIL(&st->st_entry, se, se_list);
  273         LIST_INSERT_HEAD(&st->st_hash[hash], se, se_hash);
  274 found:
  275         ise = &se->base;
  276         /* XXX ap beaconing multiple ssid w/ same bssid */
  277         if (sp->ssid[1] != 0 &&
  278             (ISPROBE(subtype) || ise->se_ssid[1] == 0))
  279                 memcpy(ise->se_ssid, sp->ssid, 2+sp->ssid[1]);
  280         KASSERT(sp->rates[1] <= IEEE80211_RATE_MAXSIZE,
  281                 ("rate set too large: %u", sp->rates[1]));
  282         memcpy(ise->se_rates, sp->rates, 2+sp->rates[1]);
  283         if (sp->xrates != NULL) {
  284                 /* XXX validate xrates[1] */
  285                 KASSERT(sp->xrates[1] <= IEEE80211_RATE_MAXSIZE,
  286                         ("xrate set too large: %u", sp->xrates[1]));
  287                 memcpy(ise->se_xrates, sp->xrates, 2+sp->xrates[1]);
  288         } else
  289                 ise->se_xrates[1] = 0;
  290         IEEE80211_ADDR_COPY(ise->se_bssid, wh->i_addr3);
  291         if ((sp->status & IEEE80211_BPARSE_OFFCHAN) == 0) {
  292                 /*
  293                  * Record rssi data using extended precision LPF filter.
  294                  *
  295                  * NB: use only on-channel data to insure we get a good
  296                  *     estimate of the signal we'll see when associated.
  297                  */
  298                 IEEE80211_RSSI_LPF(se->se_avgrssi, rssi);
  299                 ise->se_rssi = IEEE80211_RSSI_GET(se->se_avgrssi);
  300                 ise->se_noise = noise;
  301         }
  302         memcpy(ise->se_tstamp.data, sp->tstamp, sizeof(ise->se_tstamp));
  303         ise->se_intval = sp->bintval;
  304         ise->se_capinfo = sp->capinfo;
  305 #ifdef IEEE80211_SUPPORT_MESH
  306         if (sp->meshid != NULL && sp->meshid[1] != 0)
  307                 memcpy(ise->se_meshid, sp->meshid, 2+sp->meshid[1]);
  308 #endif
  309         /*
  310          * Beware of overriding se_chan for frames seen
  311          * off-channel; this can cause us to attempt an
  312          * association on the wrong channel.
  313          */
  314         if (sp->status & IEEE80211_BPARSE_OFFCHAN) {
  315                 /*
  316                  * Off-channel, locate the home/bss channel for the sta
  317                  * using the value broadcast in the DSPARMS ie.  We know
  318                  * sp->chan has this value because it's used to calculate
  319                  * IEEE80211_BPARSE_OFFCHAN.
  320                  */
  321                 c = ieee80211_find_channel_byieee(ic, sp->chan,
  322                     curchan->ic_flags);
  323                 if (c != NULL) {
  324                         ise->se_chan = c;
  325                 } else if (ise->se_chan == NULL) {
  326                         /* should not happen, pick something */
  327                         ise->se_chan = curchan;
  328                 }
  329         } else
  330                 ise->se_chan = curchan;
  331 
  332         /* VHT demotion */
  333         if (IEEE80211_IS_CHAN_VHT(ise->se_chan) && sp->vhtcap == NULL) {
  334                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_11N,
  335                     "%s: demoting VHT->HT %d/0x%08x\n",
  336                     __func__, ise->se_chan->ic_freq, ise->se_chan->ic_flags);
  337                 /* Demote legacy networks to a non-VHT channel. */
  338                 c = ieee80211_find_channel(ic, ise->se_chan->ic_freq,
  339                     ise->se_chan->ic_flags & ~IEEE80211_CHAN_VHT);
  340                 KASSERT(c != NULL,
  341                     ("no non-VHT channel %u", ise->se_chan->ic_ieee));
  342                 ise->se_chan = c;
  343         }
  344 
  345         /* HT demotion */
  346         if (IEEE80211_IS_CHAN_HT(ise->se_chan) && sp->htcap == NULL) {
  347                 /* Demote legacy networks to a non-HT channel. */
  348                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_11N,
  349                     "%s: demoting HT->legacy %d/0x%08x\n",
  350                     __func__, ise->se_chan->ic_freq, ise->se_chan->ic_flags);
  351                 c = ieee80211_find_channel(ic, ise->se_chan->ic_freq,
  352                     ise->se_chan->ic_flags & ~IEEE80211_CHAN_HT);
  353                 KASSERT(c != NULL,
  354                     ("no legacy channel %u", ise->se_chan->ic_ieee));
  355                 ise->se_chan = c;
  356         }
  357 
  358         ise->se_fhdwell = sp->fhdwell;
  359         ise->se_fhindex = sp->fhindex;
  360         ise->se_erp = sp->erp;
  361         ise->se_timoff = sp->timoff;
  362         if (sp->tim != NULL) {
  363                 const struct ieee80211_tim_ie *tim =
  364                     (const struct ieee80211_tim_ie *) sp->tim;
  365                 ise->se_dtimperiod = tim->tim_period;
  366         }
  367         if (sp->country != NULL) {
  368                 const struct ieee80211_country_ie *cie =
  369                     (const struct ieee80211_country_ie *) sp->country;
  370                 /*
  371                  * If 11d is enabled and we're attempting to join a bss
  372                  * that advertises it's country code then compare our
  373                  * current settings to what we fetched from the country ie.
  374                  * If our country code is unspecified or different then
  375                  * dispatch an event to user space that identifies the
  376                  * country code so our regdomain config can be changed.
  377                  */
  378                 /* XXX only for STA mode? */
  379                 if ((IEEE80211_IS_CHAN_11D(ise->se_chan) ||
  380                     (vap->iv_flags_ext & IEEE80211_FEXT_DOTD)) &&
  381                     (ic->ic_regdomain.country == CTRY_DEFAULT ||
  382                      !isocmp(cie->cc, ic->ic_regdomain.isocc))) {
  383                         /* only issue one notify event per scan */
  384                         if (se->se_countrygen != st->st_scangen) {
  385                                 ieee80211_notify_country(vap, ise->se_bssid,
  386                                     cie->cc);
  387                                 se->se_countrygen = st->st_scangen;
  388                         }
  389                 }
  390                 ise->se_cc[0] = cie->cc[0];
  391                 ise->se_cc[1] = cie->cc[1];
  392         }
  393         /* NB: no need to setup ie ptrs; they are not (currently) used */
  394         (void) ieee80211_ies_init(&ise->se_ies, sp->ies, sp->ies_len);
  395 
  396         /* clear failure count after STA_FAIL_AGE passes */
  397         if (se->se_fails && (ticks - se->se_lastfail) > STA_FAILS_AGE*hz) {
  398                 se->se_fails = 0;
  399                 IEEE80211_NOTE_MAC(vap, IEEE80211_MSG_SCAN, macaddr,
  400                     "%s: fails %u", __func__, se->se_fails);
  401         }
  402 
  403         se->se_lastupdate = ticks;              /* update time */
  404         se->se_seen = 1;
  405         se->se_notseen = 0;
  406 
  407         KASSERT(sizeof(sp->bchan) == 1, ("bchan size"));
  408         if (rssi > st->st_maxrssi[sp->bchan])
  409                 st->st_maxrssi[sp->bchan] = rssi;
  410 
  411         IEEE80211_SCAN_TABLE_UNLOCK(st);
  412 
  413         /*
  414          * If looking for a quick choice and nothing's
  415          * been found check here.
  416          */
  417         if (PICK1ST(ss) && match_bss(vap, ss, se, IEEE80211_MSG_SCAN) == 0)
  418                 ss->ss_flags |= IEEE80211_SCAN_GOTPICK;
  419 
  420         return 1;
  421 #undef PICK1ST
  422 #undef ISPROBE
  423 }
  424 
  425 /*
  426  * Check if a channel is excluded by user request.
  427  */
  428 static int
  429 isexcluded(struct ieee80211vap *vap, const struct ieee80211_channel *c)
  430 {
  431         return (isclr(vap->iv_ic->ic_chan_active, c->ic_ieee) ||
  432             (vap->iv_des_chan != IEEE80211_CHAN_ANYC &&
  433              c->ic_freq != vap->iv_des_chan->ic_freq));
  434 }
  435 
  436 static struct ieee80211_channel *
  437 find11gchannel(struct ieee80211com *ic, int i, int freq)
  438 {
  439         struct ieee80211_channel *c;
  440         int j;
  441 
  442         /*
  443          * The normal ordering in the channel list is b channel
  444          * immediately followed by g so optimize the search for
  445          * this.  We'll still do a full search just in case.
  446          */
  447         for (j = i+1; j < ic->ic_nchans; j++) {
  448                 c = &ic->ic_channels[j];
  449                 if (c->ic_freq == freq && IEEE80211_IS_CHAN_G(c))
  450                         return c;
  451         }
  452         for (j = 0; j < i; j++) {
  453                 c = &ic->ic_channels[j];
  454                 if (c->ic_freq == freq && IEEE80211_IS_CHAN_G(c))
  455                         return c;
  456         }
  457         return NULL;
  458 }
  459 
  460 static const u_int chanflags[IEEE80211_MODE_MAX] = {
  461         [IEEE80211_MODE_AUTO]     = IEEE80211_CHAN_B,
  462         [IEEE80211_MODE_11A]      = IEEE80211_CHAN_A,
  463         [IEEE80211_MODE_11B]      = IEEE80211_CHAN_B,
  464         [IEEE80211_MODE_11G]      = IEEE80211_CHAN_G,
  465         [IEEE80211_MODE_FH]       = IEEE80211_CHAN_FHSS,
  466         /* check base channel */
  467         [IEEE80211_MODE_TURBO_A]  = IEEE80211_CHAN_A,
  468         [IEEE80211_MODE_TURBO_G]  = IEEE80211_CHAN_G,
  469         [IEEE80211_MODE_STURBO_A] = IEEE80211_CHAN_ST,
  470         [IEEE80211_MODE_HALF]     = IEEE80211_CHAN_HALF,
  471         [IEEE80211_MODE_QUARTER]  = IEEE80211_CHAN_QUARTER,
  472         /* check legacy */
  473         [IEEE80211_MODE_11NA]     = IEEE80211_CHAN_A,
  474         [IEEE80211_MODE_11NG]     = IEEE80211_CHAN_G,
  475         [IEEE80211_MODE_VHT_5GHZ] = IEEE80211_CHAN_A,
  476         [IEEE80211_MODE_VHT_2GHZ] = IEEE80211_CHAN_G,
  477 };
  478 
  479 static void
  480 add_channels(struct ieee80211vap *vap,
  481         struct ieee80211_scan_state *ss,
  482         enum ieee80211_phymode mode, const uint16_t freq[], int nfreq)
  483 {
  484         struct ieee80211com *ic = vap->iv_ic;
  485         struct ieee80211_channel *c, *cg;
  486         u_int modeflags;
  487         int i;
  488 
  489         KASSERT(mode < nitems(chanflags), ("Unexpected mode %u", mode));
  490         modeflags = chanflags[mode];
  491         for (i = 0; i < nfreq; i++) {
  492                 if (ss->ss_last >= IEEE80211_SCAN_MAX)
  493                         break;
  494 
  495                 c = ieee80211_find_channel(ic, freq[i], modeflags);
  496                 if (c == NULL || isexcluded(vap, c))
  497                         continue;
  498                 if (mode == IEEE80211_MODE_AUTO) {
  499                         KASSERT(IEEE80211_IS_CHAN_B(c),
  500                             ("%s: wrong channel for 'auto' mode %u / %u\n",
  501                             __func__, c->ic_freq, c->ic_flags));
  502 
  503                         /*
  504                          * XXX special-case 11b/g channels so we select
  505                          *     the g channel if both are present.
  506                          */
  507                         if ((cg = find11gchannel(ic, i, c->ic_freq)) != NULL)
  508                                 c = cg;
  509                 }
  510                 ss->ss_chans[ss->ss_last++] = c;
  511         }
  512 }
  513 
  514 struct scanlist {
  515         uint16_t        mode;
  516         uint16_t        count;
  517         const uint16_t  *list;
  518 };
  519 
  520 static int
  521 checktable(const struct scanlist *scan, const struct ieee80211_channel *c)
  522 {
  523         int i;
  524 
  525         for (; scan->list != NULL; scan++) {
  526                 for (i = 0; i < scan->count; i++)
  527                         if (scan->list[i] == c->ic_freq) 
  528                                 return 1;
  529         }
  530         return 0;
  531 }
  532 
  533 static int
  534 onscanlist(const struct ieee80211_scan_state *ss,
  535         const struct ieee80211_channel *c)
  536 {
  537         int i;
  538 
  539         for (i = 0; i < ss->ss_last; i++)
  540                 if (ss->ss_chans[i] == c)
  541                         return 1;
  542         return 0;
  543 }
  544 
  545 static void
  546 sweepchannels(struct ieee80211_scan_state *ss, struct ieee80211vap *vap,
  547         const struct scanlist table[])
  548 {
  549         struct ieee80211com *ic = vap->iv_ic;
  550         struct ieee80211_channel *c;
  551         int i;
  552 
  553         for (i = 0; i < ic->ic_nchans; i++) {
  554                 if (ss->ss_last >= IEEE80211_SCAN_MAX)
  555                         break;
  556 
  557                 c = &ic->ic_channels[i];
  558                 /*
  559                  * Ignore dynamic turbo channels; we scan them
  560                  * in normal mode (i.e. not boosted).  Likewise
  561                  * for HT/VHT channels, they get scanned using
  562                  * legacy rates.
  563                  */
  564                 if (IEEE80211_IS_CHAN_DTURBO(c) || IEEE80211_IS_CHAN_HT(c) ||
  565                     IEEE80211_IS_CHAN_VHT(c))
  566                         continue;
  567 
  568                 /*
  569                  * If a desired mode was specified, scan only 
  570                  * channels that satisfy that constraint.
  571                  */
  572                 if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
  573                     vap->iv_des_mode != ieee80211_chan2mode(c))
  574                         continue;
  575 
  576                 /*
  577                  * Skip channels excluded by user request.
  578                  */
  579                 if (isexcluded(vap, c))
  580                         continue;
  581 
  582                 /*
  583                  * Add the channel unless it is listed in the
  584                  * fixed scan order tables.  This insures we
  585                  * don't sweep back in channels we filtered out
  586                  * above.
  587                  */
  588                 if (checktable(table, c))
  589                         continue;
  590 
  591                 /* Add channel to scanning list. */
  592                 ss->ss_chans[ss->ss_last++] = c;
  593         }
  594         /*
  595          * Explicitly add any desired channel if:
  596          * - not already on the scan list
  597          * - allowed by any desired mode constraint
  598          * - there is space in the scan list
  599          * This allows the channel to be used when the filtering
  600          * mechanisms would otherwise elide it (e.g HT, turbo).
  601          */
  602         c = vap->iv_des_chan;
  603         if (c != IEEE80211_CHAN_ANYC &&
  604             !onscanlist(ss, c) &&
  605             (vap->iv_des_mode == IEEE80211_MODE_AUTO ||
  606              vap->iv_des_mode == ieee80211_chan2mode(c)) &&
  607             ss->ss_last < IEEE80211_SCAN_MAX)
  608                 ss->ss_chans[ss->ss_last++] = c;
  609 }
  610 
  611 static void
  612 makescanlist(struct ieee80211_scan_state *ss, struct ieee80211vap *vap,
  613         const struct scanlist table[])
  614 {
  615         const struct scanlist *scan;
  616         enum ieee80211_phymode mode;
  617 
  618         ss->ss_last = 0;
  619         /*
  620          * Use the table of ordered channels to construct the list
  621          * of channels for scanning.  Any channels in the ordered
  622          * list not in the master list will be discarded.
  623          */
  624         for (scan = table; scan->list != NULL; scan++) {
  625                 mode = scan->mode;
  626 
  627                 switch (mode) {
  628                 case IEEE80211_MODE_11B:
  629                         if (vap->iv_des_mode == IEEE80211_MODE_11B)
  630                                 break;
  631 
  632                         /*
  633                          * The scan table marks 2.4Ghz channels as b
  634                          * so if the desired mode is 11g / 11ng / 11acg,
  635                          * then use the 11b channel list but upgrade the mode.
  636                          *
  637                          * NB: 11b -> AUTO lets add_channels upgrade an
  638                          * 11b channel to 11g if available.
  639                          */
  640                         if (vap->iv_des_mode == IEEE80211_MODE_AUTO ||
  641                             vap->iv_des_mode == IEEE80211_MODE_11G ||
  642                             vap->iv_des_mode == IEEE80211_MODE_11NG ||
  643                             vap->iv_des_mode == IEEE80211_MODE_VHT_2GHZ) {
  644                                 mode = vap->iv_des_mode;
  645                                 break;
  646                         }
  647 
  648                         continue;
  649                 case IEEE80211_MODE_11A:
  650                         /* Use 11a channel list for 11na / 11ac modes */
  651                         if (vap->iv_des_mode == IEEE80211_MODE_11NA ||
  652                             vap->iv_des_mode == IEEE80211_MODE_VHT_5GHZ) {
  653                                 mode = vap->iv_des_mode;
  654                                 break;
  655                         }
  656 
  657                         /* FALLTHROUGH */
  658                 default:
  659                         /*
  660                          * If a desired mode was specified, scan only
  661                          * channels that satisfy that constraint.
  662                          */
  663                         if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
  664                             vap->iv_des_mode != mode)
  665                                 continue;
  666                 }
  667 
  668 #ifdef IEEE80211_F_XR
  669                 /* XR does not operate on turbo channels */
  670                 if ((vap->iv_flags & IEEE80211_F_XR) &&
  671                     (mode == IEEE80211_MODE_TURBO_A ||
  672                      mode == IEEE80211_MODE_TURBO_G ||
  673                      mode == IEEE80211_MODE_STURBO_A))
  674                         continue;
  675 #endif
  676                 /*
  677                  * Add the list of the channels; any that are not
  678                  * in the master channel list will be discarded.
  679                  */
  680                 add_channels(vap, ss, mode, scan->list, scan->count);
  681         }
  682 
  683         /*
  684          * Add the channels from the ic that are not present
  685          * in the table.
  686          */
  687         sweepchannels(ss, vap, table);
  688 }
  689 
  690 static const uint16_t rcl1[] =          /* 8 FCC channel: 52, 56, 60, 64, 36, 40, 44, 48 */
  691 { 5260, 5280, 5300, 5320, 5180, 5200, 5220, 5240 };
  692 static const uint16_t rcl2[] =          /* 4 MKK channels: 34, 38, 42, 46 */
  693 { 5170, 5190, 5210, 5230 };
  694 static const uint16_t rcl3[] =          /* 2.4Ghz ch: 1,6,11,7,13 */
  695 { 2412, 2437, 2462, 2442, 2472 };
  696 static const uint16_t rcl4[] =          /* 5 FCC channel: 149, 153, 161, 165 */
  697 { 5745, 5765, 5785, 5805, 5825 };
  698 static const uint16_t rcl7[] =          /* 11 ETSI channel: 100,104,108,112,116,120,124,128,132,136,140 */
  699 { 5500, 5520, 5540, 5560, 5580, 5600, 5620, 5640, 5660, 5680, 5700 };
  700 static const uint16_t rcl8[] =          /* 2.4Ghz ch: 2,3,4,5,8,9,10,12 */
  701 { 2417, 2422, 2427, 2432, 2447, 2452, 2457, 2467 };
  702 static const uint16_t rcl9[] =          /* 2.4Ghz ch: 14 */
  703 { 2484 };
  704 static const uint16_t rcl10[] = /* Added Korean channels 2312-2372 */
  705 { 2312, 2317, 2322, 2327, 2332, 2337, 2342, 2347, 2352, 2357, 2362, 2367, 2372 };
  706 static const uint16_t rcl11[] = /* Added Japan channels in 4.9/5.0 spectrum */
  707 { 5040, 5060, 5080, 4920, 4940, 4960, 4980 };
  708 #ifdef ATH_TURBO_SCAN
  709 static const uint16_t rcl5[] =          /* 3 static turbo channels */
  710 { 5210, 5250, 5290 };
  711 static const uint16_t rcl6[] =          /* 2 static turbo channels */
  712 { 5760, 5800 };
  713 static const uint16_t rcl6x[] = /* 4 FCC3 turbo channels */
  714 { 5540, 5580, 5620, 5660 };
  715 static const uint16_t rcl12[] = /* 2.4Ghz Turbo channel 6 */
  716 { 2437 };
  717 static const uint16_t rcl13[] = /* dynamic Turbo channels */
  718 { 5200, 5240, 5280, 5765, 5805 };
  719 #endif /* ATH_TURBO_SCAN */
  720 
  721 #define X(a)    .count = sizeof(a)/sizeof(a[0]), .list = a
  722 
  723 static const struct scanlist staScanTable[] = {
  724         { IEEE80211_MODE_11B,           X(rcl3) },
  725         { IEEE80211_MODE_11A,           X(rcl1) },
  726         { IEEE80211_MODE_11A,           X(rcl2) },
  727         { IEEE80211_MODE_11B,           X(rcl8) },
  728         { IEEE80211_MODE_11B,           X(rcl9) },
  729         { IEEE80211_MODE_11A,           X(rcl4) },
  730 #ifdef ATH_TURBO_SCAN
  731         { IEEE80211_MODE_STURBO_A,      X(rcl5) },
  732         { IEEE80211_MODE_STURBO_A,      X(rcl6) },
  733         { IEEE80211_MODE_TURBO_A,       X(rcl6x) },
  734         { IEEE80211_MODE_TURBO_A,       X(rcl13) },
  735 #endif /* ATH_TURBO_SCAN */
  736         { IEEE80211_MODE_11A,           X(rcl7) },
  737         { IEEE80211_MODE_11B,           X(rcl10) },
  738         { IEEE80211_MODE_11A,           X(rcl11) },
  739 #ifdef ATH_TURBO_SCAN
  740         { IEEE80211_MODE_TURBO_G,       X(rcl12) },
  741 #endif /* ATH_TURBO_SCAN */
  742         { .list = NULL }
  743 };
  744 
  745 /*
  746  * Start a station-mode scan by populating the channel list.
  747  */
  748 static int
  749 sta_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  750 {
  751         struct sta_table *st = ss->ss_priv;
  752 
  753         makescanlist(ss, vap, staScanTable);
  754 
  755         if (ss->ss_mindwell == 0)
  756                 ss->ss_mindwell = msecs_to_ticks(20);   /* 20ms */
  757         if (ss->ss_maxdwell == 0)
  758                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
  759 
  760         st->st_scangen++;
  761         st->st_newscan = 1;
  762 
  763         return 0;
  764 }
  765 
  766 /*
  767  * Restart a scan, typically a bg scan but can
  768  * also be a fg scan that came up empty.
  769  */
  770 static int
  771 sta_restart(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  772 {
  773         struct sta_table *st = ss->ss_priv;
  774 
  775         st->st_newscan = 1;
  776         return 0;
  777 }
  778 
  779 /*
  780  * Cancel an ongoing scan.
  781  */
  782 static int
  783 sta_cancel(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  784 {
  785         return 0;
  786 }
  787 
  788 /*
  789  * Demote any supplied 11g channel to 11b.  There should
  790  * always be an 11b channel but we check anyway...
  791  */
  792 static struct ieee80211_channel *
  793 demote11b(struct ieee80211vap *vap, struct ieee80211_channel *chan)
  794 {
  795         struct ieee80211_channel *c;
  796 
  797         if (IEEE80211_IS_CHAN_ANYG(chan) &&
  798             vap->iv_des_mode == IEEE80211_MODE_AUTO) {
  799                 c = ieee80211_find_channel(vap->iv_ic, chan->ic_freq,
  800                     (chan->ic_flags &~ (IEEE80211_CHAN_PUREG | IEEE80211_CHAN_G)) |
  801                     IEEE80211_CHAN_B);
  802                 if (c != NULL)
  803                         chan = c;
  804         }
  805         return chan;
  806 }
  807 
  808 static int
  809 maxrate(const struct ieee80211_scan_entry *se)
  810 {
  811         const struct ieee80211_ie_htcap *htcap =
  812             (const struct ieee80211_ie_htcap *) se->se_ies.htcap_ie;
  813         int rmax, r, i, txstream;
  814         uint16_t caps;
  815         uint8_t txparams;
  816 
  817         rmax = 0;
  818         if (htcap != NULL) {
  819                 /*
  820                  * HT station; inspect supported MCS and then adjust
  821                  * rate by channel width.
  822                  */
  823                 txparams = htcap->hc_mcsset[12];
  824                 if (txparams & 0x3) {
  825                         /*
  826                          * TX MCS parameters defined and not equal to RX,
  827                          * extract the number of spartial streams and
  828                          * map it to the highest MCS rate.
  829                          */
  830                         txstream = ((txparams & 0xc) >> 2) + 1;
  831                         i = txstream * 8 - 1;
  832                 } else
  833                         for (i = 31; i >= 0 && isclr(htcap->hc_mcsset, i); i--);
  834                 if (i >= 0) {
  835                         caps = le16dec(&htcap->hc_cap);
  836                         if ((caps & IEEE80211_HTCAP_CHWIDTH40) &&
  837                             (caps & IEEE80211_HTCAP_SHORTGI40))
  838                                 rmax = ieee80211_htrates[i].ht40_rate_400ns;
  839                         else if (caps & IEEE80211_HTCAP_CHWIDTH40)
  840                                 rmax = ieee80211_htrates[i].ht40_rate_800ns;
  841                         else if (caps & IEEE80211_HTCAP_SHORTGI20)
  842                                 rmax = ieee80211_htrates[i].ht20_rate_400ns;
  843                         else
  844                                 rmax = ieee80211_htrates[i].ht20_rate_800ns;
  845                 }
  846         }
  847         for (i = 0; i < se->se_rates[1]; i++) {
  848                 r = se->se_rates[2+i] & IEEE80211_RATE_VAL;
  849                 if (r > rmax)
  850                         rmax = r;
  851         }
  852         for (i = 0; i < se->se_xrates[1]; i++) {
  853                 r = se->se_xrates[2+i] & IEEE80211_RATE_VAL;
  854                 if (r > rmax)
  855                         rmax = r;
  856         }
  857         return rmax;
  858 }
  859 
  860 /*
  861  * Compare the capabilities of two entries and decide which is
  862  * more desirable (return >0 if a is considered better).  Note
  863  * that we assume compatibility/usability has already been checked
  864  * so we don't need to (e.g. validate whether privacy is supported).
  865  * Used to select the best scan candidate for association in a BSS.
  866  *
  867  * TODO: should we take 11n, 11ac into account when selecting the
  868  * best?  Right now it just compares frequency band and RSSI.
  869  */
  870 static int
  871 sta_compare(const struct sta_entry *a, const struct sta_entry *b)
  872 {
  873 #define PREFER(_a,_b,_what) do {                        \
  874         if (((_a) ^ (_b)) & (_what))                    \
  875                 return ((_a) & (_what)) ? 1 : -1;       \
  876 } while (0)
  877         int maxa, maxb;
  878         int8_t rssia, rssib;
  879         int weight;
  880 
  881         /* privacy support */
  882         PREFER(a->base.se_capinfo, b->base.se_capinfo,
  883                 IEEE80211_CAPINFO_PRIVACY);
  884 
  885         /* compare count of previous failures */
  886         weight = b->se_fails - a->se_fails;
  887         if (abs(weight) > 1)
  888                 return weight;
  889 
  890         /*
  891          * Compare rssi.  If the two are considered equivalent
  892          * then fallback to other criteria.  We threshold the
  893          * comparisons to avoid selecting an ap purely by rssi
  894          * when both values may be good but one ap is otherwise
  895          * more desirable (e.g. an 11b-only ap with stronger
  896          * signal than an 11g ap).
  897          */
  898         rssia = MIN(a->base.se_rssi, STA_RSSI_MAX);
  899         rssib = MIN(b->base.se_rssi, STA_RSSI_MAX);
  900         if (abs(rssib - rssia) < 5) {
  901                 /* best/max rate preferred if signal level close enough XXX */
  902                 maxa = maxrate(&a->base);
  903                 maxb = maxrate(&b->base);
  904                 if (maxa != maxb)
  905                         return maxa - maxb;
  906                 /* XXX use freq for channel preference */
  907                 /* for now just prefer 5Ghz band to all other bands */
  908                 PREFER(IEEE80211_IS_CHAN_5GHZ(a->base.se_chan),
  909                        IEEE80211_IS_CHAN_5GHZ(b->base.se_chan), 1);
  910         }
  911         /* all things being equal, use signal level */
  912         return a->base.se_rssi - b->base.se_rssi;
  913 #undef PREFER
  914 }
  915 
  916 /*
  917  * Check rate set suitability and return the best supported rate.
  918  * XXX inspect MCS for HT
  919  */
  920 static int
  921 check_rate(struct ieee80211vap *vap, const struct ieee80211_channel *chan,
  922     const struct ieee80211_scan_entry *se)
  923 {
  924         const struct ieee80211_rateset *srs;
  925         int i, j, nrs, r, okrate, badrate, fixedrate, ucastrate;
  926         const uint8_t *rs;
  927 
  928         okrate = badrate = 0;
  929 
  930         srs = ieee80211_get_suprates(vap->iv_ic, chan);
  931         nrs = se->se_rates[1];
  932         rs = se->se_rates+2;
  933         /* XXX MCS */
  934         ucastrate = vap->iv_txparms[ieee80211_chan2mode(chan)].ucastrate;
  935         fixedrate = IEEE80211_FIXED_RATE_NONE;
  936 again:
  937         for (i = 0; i < nrs; i++) {
  938                 r = IEEE80211_RV(rs[i]);
  939                 badrate = r;
  940                 /*
  941                  * Check any fixed rate is included. 
  942                  */
  943                 if (r == ucastrate)
  944                         fixedrate = r;
  945                 /*
  946                  * Check against our supported rates.
  947                  */
  948                 for (j = 0; j < srs->rs_nrates; j++)
  949                         if (r == IEEE80211_RV(srs->rs_rates[j])) {
  950                                 if (r > okrate)         /* NB: track max */
  951                                         okrate = r;
  952                                 break;
  953                         }
  954 
  955                 if (j == srs->rs_nrates && (rs[i] & IEEE80211_RATE_BASIC)) {
  956                         /*
  957                          * Don't try joining a BSS, if we don't support
  958                          * one of its basic rates.
  959                          */
  960                         okrate = 0;
  961                         goto back;
  962                 }
  963         }
  964         if (rs == se->se_rates+2) {
  965                 /* scan xrates too; sort of an algol68-style for loop */
  966                 nrs = se->se_xrates[1];
  967                 rs = se->se_xrates+2;
  968                 goto again;
  969         }
  970 
  971 back:
  972         if (okrate == 0 || ucastrate != fixedrate)
  973                 return badrate | IEEE80211_RATE_BASIC;
  974         else
  975                 return IEEE80211_RV(okrate);
  976 }
  977 
  978 static __inline int
  979 match_id(const uint8_t *ie, const uint8_t *val, int len)
  980 {
  981         return (ie[1] == len && memcmp(ie+2, val, len) == 0);
  982 }
  983 
  984 static int
  985 match_ssid(const uint8_t *ie,
  986         int nssid, const struct ieee80211_scan_ssid ssids[])
  987 {
  988         int i;
  989 
  990         for (i = 0; i < nssid; i++) {
  991                 if (match_id(ie, ssids[i].ssid, ssids[i].len))
  992                         return 1;
  993         }
  994         return 0;
  995 }
  996 
  997 #ifdef IEEE80211_SUPPORT_TDMA
  998 static int
  999 tdma_isfull(const struct ieee80211_tdma_param *tdma)
 1000 {
 1001         int slot, slotcnt;
 1002 
 1003         slotcnt = tdma->tdma_slotcnt;
 1004         for (slot = slotcnt-1; slot >= 0; slot--)
 1005                 if (isclr(tdma->tdma_inuse, slot))
 1006                         return 0;
 1007         return 1;
 1008 }
 1009 #endif /* IEEE80211_SUPPORT_TDMA */
 1010 
 1011 /*
 1012  * Test a scan candidate for suitability/compatibility.
 1013  */
 1014 static int
 1015 match_bss(struct ieee80211vap *vap,
 1016         const struct ieee80211_scan_state *ss, struct sta_entry *se0,
 1017         int debug)
 1018 {
 1019         struct ieee80211com *ic = vap->iv_ic;
 1020         struct ieee80211_scan_entry *se = &se0->base;
 1021         uint8_t rate;
 1022         int fail;
 1023 
 1024         fail = 0;
 1025         if (isclr(ic->ic_chan_active, ieee80211_chan2ieee(ic, se->se_chan)))
 1026                 fail |= MATCH_CHANNEL;
 1027         /*
 1028          * NB: normally the desired mode is used to construct
 1029          * the channel list, but it's possible for the scan
 1030          * cache to include entries for stations outside this
 1031          * list so we check the desired mode here to weed them
 1032          * out.
 1033          */
 1034         if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
 1035             (se->se_chan->ic_flags & IEEE80211_CHAN_ALLTURBO) !=
 1036             chanflags[vap->iv_des_mode])
 1037                 fail |= MATCH_CHANNEL;
 1038         if (vap->iv_opmode == IEEE80211_M_IBSS) {
 1039                 if ((se->se_capinfo & IEEE80211_CAPINFO_IBSS) == 0)
 1040                         fail |= MATCH_CAPINFO;
 1041 #ifdef IEEE80211_SUPPORT_TDMA
 1042         } else if (vap->iv_opmode == IEEE80211_M_AHDEMO) {
 1043                 /*
 1044                  * Adhoc demo network setup shouldn't really be scanning
 1045                  * but just in case skip stations operating in IBSS or
 1046                  * BSS mode.
 1047                  */
 1048                 if (se->se_capinfo & (IEEE80211_CAPINFO_IBSS|IEEE80211_CAPINFO_ESS))
 1049                         fail |= MATCH_CAPINFO;
 1050                 /*
 1051                  * TDMA operation cannot coexist with a normal 802.11 network;
 1052                  * skip if IBSS or ESS capabilities are marked and require
 1053                  * the beacon have a TDMA ie present.
 1054                  */
 1055                 if (vap->iv_caps & IEEE80211_C_TDMA) {
 1056                         const struct ieee80211_tdma_param *tdma =
 1057                             (const struct ieee80211_tdma_param *)se->se_ies.tdma_ie;
 1058                         const struct ieee80211_tdma_state *ts = vap->iv_tdma;
 1059 
 1060                         if (tdma == NULL)
 1061                                 fail |= MATCH_TDMA_NOIE;
 1062                         else if (tdma->tdma_version != ts->tdma_version)
 1063                                 fail |= MATCH_TDMA_VERSION;
 1064                         else if (tdma->tdma_slot != 0)
 1065                                 fail |= MATCH_TDMA_NOTMASTER;
 1066                         else if (tdma_isfull(tdma))
 1067                                 fail |= MATCH_TDMA_NOSLOT;
 1068 #if 0
 1069                         else if (ieee80211_local_address(se->se_macaddr))
 1070                                 fail |= MATCH_TDMA_LOCAL;
 1071 #endif
 1072                 }
 1073 #endif /* IEEE80211_SUPPORT_TDMA */
 1074 #ifdef IEEE80211_SUPPORT_MESH
 1075         } else if (vap->iv_opmode == IEEE80211_M_MBSS) {
 1076                 const struct ieee80211_mesh_state *ms = vap->iv_mesh;
 1077                 /*
 1078                  * Mesh nodes have IBSS & ESS bits in capinfo turned off
 1079                  * and two special ie's that must be present.
 1080                  */
 1081                 if (se->se_capinfo & (IEEE80211_CAPINFO_IBSS|IEEE80211_CAPINFO_ESS))
 1082                         fail |= MATCH_CAPINFO;
 1083                 else if (se->se_meshid[0] != IEEE80211_ELEMID_MESHID)
 1084                         fail |= MATCH_MESH_NOID;
 1085                 else if (ms->ms_idlen != 0 &&
 1086                     match_id(se->se_meshid, ms->ms_id, ms->ms_idlen))
 1087                         fail |= MATCH_MESHID;
 1088 #endif
 1089         } else {
 1090                 if ((se->se_capinfo & IEEE80211_CAPINFO_ESS) == 0)
 1091                         fail |= MATCH_CAPINFO;
 1092                 /*
 1093                  * If 11d is enabled and we're attempting to join a bss
 1094                  * that advertises it's country code then compare our
 1095                  * current settings to what we fetched from the country ie.
 1096                  * If our country code is unspecified or different then do
 1097                  * not attempt to join the bss.  We should have already
 1098                  * dispatched an event to user space that identifies the
 1099                  * new country code so our regdomain config should match.
 1100                  */
 1101                 if ((IEEE80211_IS_CHAN_11D(se->se_chan) ||
 1102                     (vap->iv_flags_ext & IEEE80211_FEXT_DOTD)) &&
 1103                     se->se_cc[0] != 0 &&
 1104                     (ic->ic_regdomain.country == CTRY_DEFAULT ||
 1105                      !isocmp(se->se_cc, ic->ic_regdomain.isocc)))
 1106                         fail |= MATCH_CC;
 1107         }
 1108         if (vap->iv_flags & IEEE80211_F_PRIVACY) {
 1109                 if ((se->se_capinfo & IEEE80211_CAPINFO_PRIVACY) == 0)
 1110                         fail |= MATCH_PRIVACY;
 1111         } else {
 1112                 /* XXX does this mean privacy is supported or required? */
 1113                 if (se->se_capinfo & IEEE80211_CAPINFO_PRIVACY)
 1114                         fail |= MATCH_PRIVACY;
 1115         }
 1116         se0->se_flags &= ~STA_DEMOTE11B;
 1117         rate = check_rate(vap, se->se_chan, se);
 1118         if (rate & IEEE80211_RATE_BASIC) {
 1119                 fail |= MATCH_RATE;
 1120                 /*
 1121                  * An 11b-only ap will give a rate mismatch if there is an
 1122                  * OFDM fixed tx rate for 11g.  Try downgrading the channel
 1123                  * in the scan list to 11b and retry the rate check.
 1124                  */
 1125                 if (IEEE80211_IS_CHAN_ANYG(se->se_chan)) {
 1126                         rate = check_rate(vap, demote11b(vap, se->se_chan), se);
 1127                         if ((rate & IEEE80211_RATE_BASIC) == 0) {
 1128                                 fail &= ~MATCH_RATE;
 1129                                 se0->se_flags |= STA_DEMOTE11B;
 1130                         }
 1131                 }
 1132         } else if (rate < 2*24) {
 1133                 /*
 1134                  * This is an 11b-only ap.  Check the desired mode in
 1135                  * case that needs to be honored (mode 11g filters out
 1136                  * 11b-only ap's).  Otherwise force any 11g channel used
 1137                  * in scanning to be demoted.
 1138                  *
 1139                  * NB: we cheat a bit here by looking at the max rate;
 1140                  *     we could/should check the rates.
 1141                  */
 1142                 if (!(vap->iv_des_mode == IEEE80211_MODE_AUTO ||
 1143                       vap->iv_des_mode == IEEE80211_MODE_11B))
 1144                         fail |= MATCH_RATE;
 1145                 else
 1146                         se0->se_flags |= STA_DEMOTE11B;
 1147         }
 1148         if (ss->ss_nssid != 0 &&
 1149             !match_ssid(se->se_ssid, ss->ss_nssid, ss->ss_ssid))
 1150                 fail |= MATCH_SSID;
 1151         if ((vap->iv_flags & IEEE80211_F_DESBSSID) &&
 1152             !IEEE80211_ADDR_EQ(vap->iv_des_bssid, se->se_bssid))
 1153                 fail |= MATCH_BSSID;
 1154         if (se0->se_fails >= STA_FAILS_MAX)
 1155                 fail |= MATCH_FAILS;
 1156         if (se0->se_notseen >= STA_PURGE_SCANS)
 1157                 fail |= MATCH_NOTSEEN;
 1158         if (se->se_rssi < STA_RSSI_MIN)
 1159                 fail |= MATCH_RSSI;
 1160 #ifdef IEEE80211_DEBUG
 1161         if (ieee80211_msg(vap, debug)) {
 1162                 printf(" %c %s",
 1163                     fail & MATCH_FAILS ? '=' :
 1164                     fail & MATCH_NOTSEEN ? '^' :
 1165                     fail & MATCH_CC ? '$' :
 1166 #ifdef IEEE80211_SUPPORT_TDMA
 1167                     fail & MATCH_TDMA_NOIE ? '&' :
 1168                     fail & MATCH_TDMA_VERSION ? 'v' :
 1169                     fail & MATCH_TDMA_NOTMASTER ? 's' :
 1170                     fail & MATCH_TDMA_NOSLOT ? 'f' :
 1171                     fail & MATCH_TDMA_LOCAL ? 'l' :
 1172 #endif
 1173                     fail & MATCH_MESH_NOID ? 'm' :
 1174                     fail ? '-' : '+', ether_sprintf(se->se_macaddr));
 1175                 printf(" %s%c", ether_sprintf(se->se_bssid),
 1176                     fail & MATCH_BSSID ? '!' : ' ');
 1177                 printf(" %3d%c", ieee80211_chan2ieee(ic, se->se_chan),
 1178                         fail & MATCH_CHANNEL ? '!' : ' ');
 1179                 printf(" %+4d%c", se->se_rssi, fail & MATCH_RSSI ? '!' : ' ');
 1180                 printf(" %2dM%c", (rate & IEEE80211_RATE_VAL) / 2,
 1181                     fail & MATCH_RATE ? '!' : ' ');
 1182                 printf(" %4s%c",
 1183                     (se->se_capinfo & IEEE80211_CAPINFO_ESS) ? "ess" :
 1184                     (se->se_capinfo & IEEE80211_CAPINFO_IBSS) ? "ibss" : "",
 1185                     fail & MATCH_CAPINFO ? '!' : ' ');
 1186                 printf(" %3s%c ",
 1187                     (se->se_capinfo & IEEE80211_CAPINFO_PRIVACY) ?
 1188                     "wep" : "no",
 1189                     fail & MATCH_PRIVACY ? '!' : ' ');
 1190                 ieee80211_print_essid(se->se_ssid+2, se->se_ssid[1]);
 1191                 printf("%s\n", fail & (MATCH_SSID | MATCH_MESHID) ? "!" : "");
 1192         }
 1193 #endif
 1194         return fail;
 1195 }
 1196 
 1197 static void
 1198 sta_update_notseen(struct sta_table *st)
 1199 {
 1200         struct sta_entry *se;
 1201 
 1202         IEEE80211_SCAN_TABLE_LOCK(st);
 1203         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1204                 /*
 1205                  * If seen the reset and don't bump the count;
 1206                  * otherwise bump the ``not seen'' count.  Note
 1207                  * that this insures that stations for which we
 1208                  * see frames while not scanning but not during
 1209                  * this scan will not be penalized.
 1210                  */
 1211                 if (se->se_seen)
 1212                         se->se_seen = 0;
 1213                 else
 1214                         se->se_notseen++;
 1215         }
 1216         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1217 }
 1218 
 1219 static void
 1220 sta_dec_fails(struct sta_table *st)
 1221 {
 1222         struct sta_entry *se;
 1223 
 1224         IEEE80211_SCAN_TABLE_LOCK(st);
 1225         TAILQ_FOREACH(se, &st->st_entry, se_list)
 1226                 if (se->se_fails)
 1227                         se->se_fails--;
 1228         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1229 }
 1230 
 1231 static struct sta_entry *
 1232 select_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap, int debug)
 1233 {
 1234         struct sta_table *st = ss->ss_priv;
 1235         struct sta_entry *se, *selbs = NULL;
 1236 
 1237         IEEE80211_DPRINTF(vap, debug, " %s\n",
 1238             "macaddr          bssid         chan  rssi  rate flag  wep  essid");
 1239         IEEE80211_SCAN_TABLE_LOCK(st);
 1240         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1241                 ieee80211_ies_expand(&se->base.se_ies);
 1242                 if (match_bss(vap, ss, se, debug) == 0) {
 1243                         if (selbs == NULL)
 1244                                 selbs = se;
 1245                         else if (sta_compare(se, selbs) > 0)
 1246                                 selbs = se;
 1247                 }
 1248         }
 1249         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1250 
 1251         return selbs;
 1252 }
 1253 
 1254 /*
 1255  * Pick an ap or ibss network to join or find a channel
 1256  * to use to start an ibss network.
 1257  */
 1258 static int
 1259 sta_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1260 {
 1261         struct sta_table *st = ss->ss_priv;
 1262         struct sta_entry *selbs;
 1263         struct ieee80211_channel *chan;
 1264 
 1265         KASSERT(vap->iv_opmode == IEEE80211_M_STA,
 1266                 ("wrong mode %u", vap->iv_opmode));
 1267 
 1268         if (st->st_newscan) {
 1269                 sta_update_notseen(st);
 1270                 st->st_newscan = 0;
 1271         }
 1272         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1273                 /*
 1274                  * Manual/background scan, don't select+join the
 1275                  * bss, just return.  The scanning framework will
 1276                  * handle notification that this has completed.
 1277                  */
 1278                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1279                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1280                     "%s: nopick; return 1\n", __func__);
 1281                 return 1;
 1282         }
 1283         /*
 1284          * Automatic sequencing; look for a candidate and
 1285          * if found join the network.
 1286          */
 1287         /* NB: unlocked read should be ok */
 1288         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1289                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1290                         "%s: no scan candidate, join=%d, return 0\n",
 1291                         __func__,
 1292                         !! (ss->ss_flags & IEEE80211_SCAN_NOJOIN));
 1293                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1294                         return 0;
 1295 notfound:
 1296                 /*
 1297                  * If nothing suitable was found decrement
 1298                  * the failure counts so entries will be
 1299                  * reconsidered the next time around.  We
 1300                  * really want to do this only for sta's
 1301                  * where we've previously had some success.
 1302                  */
 1303                 sta_dec_fails(st);
 1304                 st->st_newscan = 1;
 1305                 return 0;                       /* restart scan */
 1306         }
 1307         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1308         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1309                 return (selbs != NULL);
 1310         if (selbs == NULL)
 1311                 goto notfound;
 1312         chan = selbs->base.se_chan;
 1313         if (selbs->se_flags & STA_DEMOTE11B)
 1314                 chan = demote11b(vap, chan);
 1315         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1316                 goto notfound;
 1317         IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1318             "%s: terminate scan; return 1\n", __func__);
 1319         return 1;                               /* terminate scan */
 1320 }
 1321 
 1322 /*
 1323  * Lookup an entry in the scan cache.  We assume we're
 1324  * called from the bottom half or such that we don't need
 1325  * to block the bottom half so that it's safe to return
 1326  * a reference to an entry w/o holding the lock on the table.
 1327  */
 1328 static struct sta_entry *
 1329 sta_lookup(struct sta_table *st, const uint8_t macaddr[IEEE80211_ADDR_LEN])
 1330 {
 1331         struct sta_entry *se;
 1332         int hash = STA_HASH(macaddr);
 1333 
 1334         IEEE80211_SCAN_TABLE_LOCK(st);
 1335         LIST_FOREACH(se, &st->st_hash[hash], se_hash)
 1336                 if (IEEE80211_ADDR_EQ(se->base.se_macaddr, macaddr))
 1337                         break;
 1338         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1339 
 1340         return se;              /* NB: unlocked */
 1341 }
 1342 
 1343 static void
 1344 sta_roam_check(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1345 {
 1346         struct ieee80211com *ic = vap->iv_ic;
 1347         struct ieee80211_node *ni = vap->iv_bss;
 1348         struct sta_table *st = ss->ss_priv;
 1349         enum ieee80211_phymode mode;
 1350         struct sta_entry *se, *selbs;
 1351         uint8_t roamRate, curRate, ucastRate;
 1352         int8_t roamRssi, curRssi;
 1353 
 1354         se = sta_lookup(st, ni->ni_macaddr);
 1355         if (se == NULL) {
 1356                 /* XXX something is wrong */
 1357                 return;
 1358         }
 1359 
 1360         mode = ieee80211_chan2mode(ic->ic_bsschan);
 1361         roamRate = vap->iv_roamparms[mode].rate;
 1362         roamRssi = vap->iv_roamparms[mode].rssi;
 1363         KASSERT(roamRate != 0 && roamRssi != 0, ("iv_roamparms are not"
 1364             "initialized for %s mode!", ieee80211_phymode_name[mode]));
 1365 
 1366         ucastRate = vap->iv_txparms[mode].ucastrate;
 1367         /* NB: the most up to date rssi is in the node, not the scan cache */
 1368         curRssi = ic->ic_node_getrssi(ni);
 1369         if (ucastRate == IEEE80211_FIXED_RATE_NONE) {
 1370                 curRate = ni->ni_txrate;
 1371                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_ROAM,
 1372                     "%s: currssi %d currate %u roamrssi %d roamrate %u\n",
 1373                     __func__, curRssi, curRate, roamRssi, roamRate);
 1374         } else {
 1375                 curRate = roamRate;     /* NB: insure compare below fails */
 1376                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_ROAM,
 1377                     "%s: currssi %d roamrssi %d\n", __func__, curRssi, roamRssi);
 1378         }
 1379         /*
 1380          * Check if a new ap should be used and switch.
 1381          * XXX deauth current ap
 1382          */
 1383         if (curRate < roamRate || curRssi < roamRssi) {
 1384                 if (ieee80211_time_after(ticks, ic->ic_lastscan + vap->iv_scanvalid)) {
 1385                         /*
 1386                          * Scan cache contents are too old; force a scan now
 1387                          * if possible so we have current state to make a
 1388                          * decision with.  We don't kick off a bg scan if
 1389                          * we're using dynamic turbo and boosted or if the
 1390                          * channel is busy.
 1391                          * XXX force immediate switch on scan complete
 1392                          */
 1393                         if (!IEEE80211_IS_CHAN_DTURBO(ic->ic_curchan) &&
 1394                             ((vap->iv_flags_ext & IEEE80211_FEXT_SCAN_OFFLOAD) ||
 1395                              ieee80211_time_after(ticks, ic->ic_lastdata + vap->iv_bgscanidle)))
 1396                                 ieee80211_bg_scan(vap, 0);
 1397                         return;
 1398                 }
 1399                 se->base.se_rssi = curRssi;
 1400                 selbs = select_bss(ss, vap, IEEE80211_MSG_ROAM);
 1401                 if (selbs != NULL && selbs != se) {
 1402                         struct ieee80211_channel *chan;
 1403 
 1404                         IEEE80211_DPRINTF(vap,
 1405                             IEEE80211_MSG_ROAM | IEEE80211_MSG_DEBUG,
 1406                             "%s: ROAM: curRate %u, roamRate %u, "
 1407                             "curRssi %d, roamRssi %d\n", __func__,
 1408                             curRate, roamRate, curRssi, roamRssi);
 1409 
 1410                         chan = selbs->base.se_chan;
 1411                         if (selbs->se_flags & STA_DEMOTE11B)
 1412                                 chan = demote11b(vap, chan);
 1413                         (void) ieee80211_sta_join(vap, chan, &selbs->base);
 1414                 }
 1415         }
 1416 }
 1417 
 1418 /*
 1419  * Age entries in the scan cache.
 1420  * XXX also do roaming since it's convenient
 1421  */
 1422 static void
 1423 sta_age(struct ieee80211_scan_state *ss)
 1424 {
 1425         struct ieee80211vap *vap = ss->ss_vap;
 1426 
 1427         adhoc_age(ss);
 1428         /*
 1429          * If rate control is enabled check periodically to see if
 1430          * we should roam from our current connection to one that
 1431          * might be better.  This only applies when we're operating
 1432          * in sta mode and automatic roaming is set.
 1433          * XXX defer if busy
 1434          * XXX repeater station
 1435          * XXX do when !bgscan?
 1436          */
 1437         KASSERT(vap->iv_opmode == IEEE80211_M_STA,
 1438                 ("wrong mode %u", vap->iv_opmode));
 1439         if (vap->iv_roaming == IEEE80211_ROAMING_AUTO &&
 1440             (vap->iv_flags & IEEE80211_F_BGSCAN) &&
 1441             vap->iv_state >= IEEE80211_S_RUN)
 1442                 /* XXX vap is implicit */
 1443                 sta_roam_check(ss, vap);
 1444 }
 1445 
 1446 /*
 1447  * Iterate over the entries in the scan cache, invoking
 1448  * the callback function on each one.
 1449  */
 1450 static void
 1451 sta_iterate(struct ieee80211_scan_state *ss, 
 1452         ieee80211_scan_iter_func *f, void *arg)
 1453 {
 1454         struct sta_table *st = ss->ss_priv;
 1455         struct sta_entry *se;
 1456         u_int gen;
 1457 
 1458         IEEE80211_SCAN_ITER_LOCK(st);
 1459         gen = st->st_scaniter++;
 1460 restart:
 1461         IEEE80211_SCAN_TABLE_LOCK(st);
 1462         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1463                 if (se->se_scangen != gen) {
 1464                         se->se_scangen = gen;
 1465                         /* update public state */
 1466                         se->base.se_age = ticks - se->se_lastupdate;
 1467                         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1468                         (*f)(arg, &se->base);
 1469                         goto restart;
 1470                 }
 1471         }
 1472         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1473 
 1474         IEEE80211_SCAN_ITER_UNLOCK(st);
 1475 }
 1476 
 1477 static void
 1478 sta_assoc_fail(struct ieee80211_scan_state *ss,
 1479         const uint8_t macaddr[IEEE80211_ADDR_LEN], int reason)
 1480 {
 1481         struct sta_table *st = ss->ss_priv;
 1482         struct sta_entry *se;
 1483 
 1484         se = sta_lookup(st, macaddr);
 1485         if (se != NULL) {
 1486                 se->se_fails++;
 1487                 se->se_lastfail = ticks;
 1488                 IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
 1489                     macaddr, "%s: reason %u fails %u",
 1490                     __func__, reason, se->se_fails);
 1491         }
 1492 }
 1493 
 1494 static void
 1495 sta_assoc_success(struct ieee80211_scan_state *ss,
 1496         const uint8_t macaddr[IEEE80211_ADDR_LEN])
 1497 {
 1498         struct sta_table *st = ss->ss_priv;
 1499         struct sta_entry *se;
 1500 
 1501         se = sta_lookup(st, macaddr);
 1502         if (se != NULL) {
 1503 #if 0
 1504                 se->se_fails = 0;
 1505                 IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
 1506                     macaddr, "%s: fails %u",
 1507                     __func__, se->se_fails);
 1508 #endif
 1509                 se->se_lastassoc = ticks;
 1510         }
 1511 }
 1512 
 1513 static const struct ieee80211_scanner sta_default = {
 1514         .scan_name              = "default",
 1515         .scan_attach            = sta_attach,
 1516         .scan_detach            = sta_detach,
 1517         .scan_start             = sta_start,
 1518         .scan_restart           = sta_restart,
 1519         .scan_cancel            = sta_cancel,
 1520         .scan_end               = sta_pick_bss,
 1521         .scan_flush             = sta_flush,
 1522         .scan_add               = sta_add,
 1523         .scan_age               = sta_age,
 1524         .scan_iterate           = sta_iterate,
 1525         .scan_assoc_fail        = sta_assoc_fail,
 1526         .scan_assoc_success     = sta_assoc_success,
 1527 };
 1528 IEEE80211_SCANNER_ALG(sta, IEEE80211_M_STA, sta_default);
 1529 
 1530 /*
 1531  * Adhoc mode-specific support.
 1532  */
 1533 
 1534 static const uint16_t adhocWorld[] =            /* 36, 40, 44, 48 */
 1535 { 5180, 5200, 5220, 5240 };
 1536 static const uint16_t adhocFcc3[] =             /* 36, 40, 44, 48 145, 149, 153, 157, 161, 165 */
 1537 { 5180, 5200, 5220, 5240, 5725, 5745, 5765, 5785, 5805, 5825 };
 1538 static const uint16_t adhocMkk[] =              /* 34, 38, 42, 46 */
 1539 { 5170, 5190, 5210, 5230 };
 1540 static const uint16_t adhoc11b[] =              /* 10, 11 */
 1541 { 2457, 2462 };
 1542 
 1543 static const struct scanlist adhocScanTable[] = {
 1544         { IEEE80211_MODE_11B,           X(adhoc11b) },
 1545         { IEEE80211_MODE_11A,           X(adhocWorld) },
 1546         { IEEE80211_MODE_11A,           X(adhocFcc3) },
 1547         { IEEE80211_MODE_11B,           X(adhocMkk) },
 1548         { .list = NULL }
 1549 };
 1550 #undef X
 1551 
 1552 /*
 1553  * Start an adhoc-mode scan by populating the channel list.
 1554  */
 1555 static int
 1556 adhoc_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1557 {
 1558         struct sta_table *st = ss->ss_priv;
 1559 
 1560         makescanlist(ss, vap, adhocScanTable);
 1561 
 1562         if (ss->ss_mindwell == 0)
 1563                 ss->ss_mindwell = msecs_to_ticks(200);  /* 200ms */
 1564         if (ss->ss_maxdwell == 0)
 1565                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
 1566 
 1567         st->st_scangen++;
 1568         st->st_newscan = 1;
 1569 
 1570         return 0;
 1571 }
 1572 
 1573 /*
 1574  * Select a channel to start an adhoc network on.
 1575  * The channel list was populated with appropriate
 1576  * channels so select one that looks least occupied.
 1577  */
 1578 static struct ieee80211_channel *
 1579 adhoc_pick_channel(struct ieee80211_scan_state *ss, int flags)
 1580 {
 1581         struct sta_table *st = ss->ss_priv;
 1582         struct sta_entry *se;
 1583         struct ieee80211_channel *c, *bestchan;
 1584         int i, bestrssi, maxrssi;
 1585 
 1586         bestchan = NULL;
 1587         bestrssi = -1;
 1588 
 1589         IEEE80211_SCAN_TABLE_LOCK(st);
 1590         for (i = 0; i < ss->ss_last; i++) {
 1591                 c = ss->ss_chans[i];
 1592                 /* never consider a channel with radar */
 1593                 if (IEEE80211_IS_CHAN_RADAR(c))
 1594                         continue;
 1595                 /* skip channels disallowed by regulatory settings */
 1596                 if (IEEE80211_IS_CHAN_NOADHOC(c))
 1597                         continue;
 1598                 /* check channel attributes for band compatibility */
 1599                 if (flags != 0 && (c->ic_flags & flags) != flags)
 1600                         continue;
 1601                 maxrssi = 0;
 1602                 TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1603                         if (se->base.se_chan != c)
 1604                                 continue;
 1605                         if (se->base.se_rssi > maxrssi)
 1606                                 maxrssi = se->base.se_rssi;
 1607                 }
 1608                 if (bestchan == NULL || maxrssi < bestrssi)
 1609                         bestchan = c;
 1610         }
 1611         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1612 
 1613         return bestchan;
 1614 }
 1615 
 1616 /*
 1617  * Pick an ibss network to join or find a channel
 1618  * to use to start an ibss network.
 1619  */
 1620 static int
 1621 adhoc_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1622 {
 1623         struct sta_table *st = ss->ss_priv;
 1624         struct sta_entry *selbs;
 1625         struct ieee80211_channel *chan;
 1626         struct ieee80211com *ic = vap->iv_ic;
 1627 
 1628         KASSERT(vap->iv_opmode == IEEE80211_M_IBSS ||
 1629                 vap->iv_opmode == IEEE80211_M_AHDEMO ||
 1630                 vap->iv_opmode == IEEE80211_M_MBSS,
 1631                 ("wrong opmode %u", vap->iv_opmode));
 1632 
 1633         if (st->st_newscan) {
 1634                 sta_update_notseen(st);
 1635                 st->st_newscan = 0;
 1636         }
 1637         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1638                 /*
 1639                  * Manual/background scan, don't select+join the
 1640                  * bss, just return.  The scanning framework will
 1641                  * handle notification that this has completed.
 1642                  */
 1643                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1644                 return 1;
 1645         }
 1646         /*
 1647          * Automatic sequencing; look for a candidate and
 1648          * if found join the network.
 1649          */
 1650         /* NB: unlocked read should be ok */
 1651         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1652                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1653                         "%s: no scan candidate\n", __func__);
 1654                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1655                         return 0;
 1656 notfound:
 1657                 /* NB: never auto-start a tdma network for slot !0 */
 1658 #ifdef IEEE80211_SUPPORT_TDMA
 1659                 if (vap->iv_des_nssid &&
 1660                     ((vap->iv_caps & IEEE80211_C_TDMA) == 0 ||
 1661                      ieee80211_tdma_getslot(vap) == 0)) {
 1662 #else
 1663                 if (vap->iv_des_nssid) {
 1664 #endif
 1665                         /*
 1666                          * No existing adhoc network to join and we have
 1667                          * an ssid; start one up.  If no channel was
 1668                          * specified, try to select a channel.
 1669                          */
 1670                         if (vap->iv_des_chan == IEEE80211_CHAN_ANYC ||
 1671                             IEEE80211_IS_CHAN_RADAR(vap->iv_des_chan)) {
 1672                                 chan = adhoc_pick_channel(ss, 0);
 1673                         } else
 1674                                 chan = vap->iv_des_chan;
 1675                         if (chan != NULL) {
 1676                                 /*
 1677                                  * Create a HT capable IBSS; the per-node
 1678                                  * probe request/response will result in
 1679                                  * "correct" rate control capabilities being
 1680                                  * negotiated.
 1681                                  */
 1682                                 chan = ieee80211_ht_adjust_channel(ic,
 1683                                     chan, vap->iv_flags_ht);
 1684                                 chan = ieee80211_vht_adjust_channel(ic,
 1685                                     chan, vap->iv_flags_vht);
 1686                                 ieee80211_create_ibss(vap, chan);
 1687                                 return 1;
 1688                         }
 1689                 }
 1690                 /*
 1691                  * If nothing suitable was found decrement
 1692                  * the failure counts so entries will be
 1693                  * reconsidered the next time around.  We
 1694                  * really want to do this only for sta's
 1695                  * where we've previously had some success.
 1696                  */
 1697                 sta_dec_fails(st);
 1698                 st->st_newscan = 1;
 1699                 return 0;                       /* restart scan */
 1700         }
 1701         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1702         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1703                 return (selbs != NULL);
 1704         if (selbs == NULL)
 1705                 goto notfound;
 1706         chan = selbs->base.se_chan;
 1707         if (selbs->se_flags & STA_DEMOTE11B)
 1708                 chan = demote11b(vap, chan);
 1709         /*
 1710          * If HT is available, make it a possibility here.
 1711          * The intent is to enable HT20/HT40 when joining a non-HT
 1712          * IBSS node; we can then advertise HT IEs and speak HT
 1713          * to any subsequent nodes that support it.
 1714          */
 1715         chan = ieee80211_ht_adjust_channel(ic,
 1716             chan, vap->iv_flags_ht);
 1717         chan = ieee80211_vht_adjust_channel(ic,
 1718             chan, vap->iv_flags_vht);
 1719         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1720                 goto notfound;
 1721         return 1;                               /* terminate scan */
 1722 }
 1723 
 1724 /*
 1725  * Age entries in the scan cache.
 1726  */
 1727 static void
 1728 adhoc_age(struct ieee80211_scan_state *ss)
 1729 {
 1730         struct sta_table *st = ss->ss_priv;
 1731         struct sta_entry *se, *next;
 1732 
 1733         IEEE80211_SCAN_TABLE_LOCK(st);
 1734         TAILQ_FOREACH_SAFE(se, &st->st_entry, se_list, next) {
 1735                 if (se->se_notseen > STA_PURGE_SCANS) {
 1736                         TAILQ_REMOVE(&st->st_entry, se, se_list);
 1737                         LIST_REMOVE(se, se_hash);
 1738                         ieee80211_ies_cleanup(&se->base.se_ies);
 1739                         IEEE80211_FREE(se, M_80211_SCAN);
 1740                 }
 1741         }
 1742         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1743 }
 1744 
 1745 static const struct ieee80211_scanner adhoc_default = {
 1746         .scan_name              = "default",
 1747         .scan_attach            = sta_attach,
 1748         .scan_detach            = sta_detach,
 1749         .scan_start             = adhoc_start,
 1750         .scan_restart           = sta_restart,
 1751         .scan_cancel            = sta_cancel,
 1752         .scan_end               = adhoc_pick_bss,
 1753         .scan_flush             = sta_flush,
 1754         .scan_pickchan          = adhoc_pick_channel,
 1755         .scan_add               = sta_add,
 1756         .scan_age               = adhoc_age,
 1757         .scan_iterate           = sta_iterate,
 1758         .scan_assoc_fail        = sta_assoc_fail,
 1759         .scan_assoc_success     = sta_assoc_success,
 1760 };
 1761 IEEE80211_SCANNER_ALG(ibss, IEEE80211_M_IBSS, adhoc_default);
 1762 IEEE80211_SCANNER_ALG(ahdemo, IEEE80211_M_AHDEMO, adhoc_default);
 1763 
 1764 static int
 1765 ap_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1766 {
 1767         struct sta_table *st = ss->ss_priv;
 1768 
 1769         makescanlist(ss, vap, staScanTable);
 1770 
 1771         if (ss->ss_mindwell == 0)
 1772                 ss->ss_mindwell = msecs_to_ticks(200);  /* 200ms */
 1773         if (ss->ss_maxdwell == 0)
 1774                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
 1775 
 1776         st->st_scangen++;
 1777         st->st_newscan = 1;
 1778 
 1779         return 0;
 1780 }
 1781 
 1782 /*
 1783  * Cancel an ongoing scan.
 1784  */
 1785 static int
 1786 ap_cancel(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1787 {
 1788         return 0;
 1789 }
 1790 
 1791 /*
 1792  * Pick a quiet channel to use for ap operation.
 1793  */
 1794 static struct ieee80211_channel *
 1795 ap_pick_channel(struct ieee80211_scan_state *ss, int flags)
 1796 {
 1797         struct sta_table *st = ss->ss_priv;
 1798         struct ieee80211_channel *bestchan = NULL;
 1799         int i;
 1800 
 1801         /* XXX select channel more intelligently, e.g. channel spread, power */
 1802         /* NB: use scan list order to preserve channel preference */
 1803         for (i = 0; i < ss->ss_last; i++) {
 1804                 struct ieee80211_channel *chan = ss->ss_chans[i];
 1805                 /*
 1806                  * If the channel is unoccupied the max rssi
 1807                  * should be zero; just take it.  Otherwise
 1808                  * track the channel with the lowest rssi and
 1809                  * use that when all channels appear occupied.
 1810                  */
 1811                 if (IEEE80211_IS_CHAN_RADAR(chan))
 1812                         continue;
 1813                 if (IEEE80211_IS_CHAN_NOHOSTAP(chan))
 1814                         continue;
 1815                 /* check channel attributes for band compatibility */
 1816                 if (flags != 0 && (chan->ic_flags & flags) != flags)
 1817                         continue;
 1818                 KASSERT(sizeof(chan->ic_ieee) == 1, ("ic_chan size"));
 1819                 /* XXX channel have interference */
 1820                 if (st->st_maxrssi[chan->ic_ieee] == 0) {
 1821                         /* XXX use other considerations */
 1822                         return chan;
 1823                 }
 1824                 if (bestchan == NULL ||
 1825                     st->st_maxrssi[chan->ic_ieee] < st->st_maxrssi[bestchan->ic_ieee])
 1826                         bestchan = chan;
 1827         }
 1828         return bestchan;
 1829 }
 1830 
 1831 /*
 1832  * Pick a quiet channel to use for ap operation.
 1833  */
 1834 static int
 1835 ap_end(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1836 {
 1837         struct ieee80211com *ic = vap->iv_ic;
 1838         struct ieee80211_channel *bestchan, *chan;
 1839 
 1840         KASSERT(vap->iv_opmode == IEEE80211_M_HOSTAP,
 1841                 ("wrong opmode %u", vap->iv_opmode));
 1842         bestchan = ap_pick_channel(ss, 0);
 1843         if (bestchan == NULL) {
 1844                 /* no suitable channel, should not happen */
 1845                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1846                     "%s: no suitable channel! (should not happen)\n", __func__);
 1847                 /* XXX print something? */
 1848                 return 0;                       /* restart scan */
 1849         }
 1850         /*
 1851          * If this is a dynamic turbo channel, start with the unboosted one.
 1852          */
 1853         if (IEEE80211_IS_CHAN_TURBO(bestchan)) {
 1854                 bestchan = ieee80211_find_channel(ic, bestchan->ic_freq,
 1855                         bestchan->ic_flags & ~IEEE80211_CHAN_TURBO);
 1856                 if (bestchan == NULL) {
 1857                         /* should never happen ?? */
 1858                         return 0;
 1859                 }
 1860         }
 1861         if (ss->ss_flags & (IEEE80211_SCAN_NOPICK | IEEE80211_SCAN_NOJOIN)) {
 1862                 /*
 1863                  * Manual/background scan, don't select+join the
 1864                  * bss, just return.  The scanning framework will
 1865                  * handle notification that this has completed.
 1866                  */
 1867                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1868                 return 1;
 1869         }
 1870         chan = ieee80211_ht_adjust_channel(ic, bestchan, vap->iv_flags_ht);
 1871         chan = ieee80211_vht_adjust_channel(ic, chan, vap->iv_flags_vht);
 1872         ieee80211_create_ibss(vap, chan);
 1873 
 1874         return 1;
 1875 }
 1876 
 1877 static const struct ieee80211_scanner ap_default = {
 1878         .scan_name              = "default",
 1879         .scan_attach            = sta_attach,
 1880         .scan_detach            = sta_detach,
 1881         .scan_start             = ap_start,
 1882         .scan_restart           = sta_restart,
 1883         .scan_cancel            = ap_cancel,
 1884         .scan_end               = ap_end,
 1885         .scan_flush             = sta_flush,
 1886         .scan_pickchan          = ap_pick_channel,
 1887         .scan_add               = sta_add,
 1888         .scan_age               = adhoc_age,
 1889         .scan_iterate           = sta_iterate,
 1890         .scan_assoc_success     = sta_assoc_success,
 1891         .scan_assoc_fail        = sta_assoc_fail,
 1892 };
 1893 IEEE80211_SCANNER_ALG(ap, IEEE80211_M_HOSTAP, ap_default);
 1894 
 1895 #ifdef IEEE80211_SUPPORT_MESH
 1896 /*
 1897  * Pick an mbss network to join or find a channel
 1898  * to use to start an mbss network.
 1899  */
 1900 static int
 1901 mesh_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1902 {
 1903         struct sta_table *st = ss->ss_priv;
 1904         struct ieee80211_mesh_state *ms = vap->iv_mesh;
 1905         struct sta_entry *selbs;
 1906         struct ieee80211_channel *chan;
 1907 
 1908         KASSERT(vap->iv_opmode == IEEE80211_M_MBSS,
 1909                 ("wrong opmode %u", vap->iv_opmode));
 1910 
 1911         if (st->st_newscan) {
 1912                 sta_update_notseen(st);
 1913                 st->st_newscan = 0;
 1914         }
 1915         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1916                 /*
 1917                  * Manual/background scan, don't select+join the
 1918                  * bss, just return.  The scanning framework will
 1919                  * handle notification that this has completed.
 1920                  */
 1921                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1922                 return 1;
 1923         }
 1924         /*
 1925          * Automatic sequencing; look for a candidate and
 1926          * if found join the network.
 1927          */
 1928         /* NB: unlocked read should be ok */
 1929         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1930                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1931                         "%s: no scan candidate\n", __func__);
 1932                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1933                         return 0;
 1934 notfound:
 1935                 if (ms->ms_idlen != 0) {
 1936                         /*
 1937                          * No existing mbss network to join and we have
 1938                          * a meshid; start one up.  If no channel was
 1939                          * specified, try to select a channel.
 1940                          */
 1941                         if (vap->iv_des_chan == IEEE80211_CHAN_ANYC ||
 1942                             IEEE80211_IS_CHAN_RADAR(vap->iv_des_chan)) {
 1943                                 struct ieee80211com *ic = vap->iv_ic;
 1944 
 1945                                 /* XXX VHT */
 1946                                 chan = adhoc_pick_channel(ss, 0);
 1947                                 if (chan != NULL) {
 1948                                         chan = ieee80211_ht_adjust_channel(ic,
 1949                                             chan, vap->iv_flags_ht);
 1950                                         chan = ieee80211_vht_adjust_channel(ic,
 1951                                             chan, vap->iv_flags_vht);
 1952                                         }
 1953                         } else
 1954                                 chan = vap->iv_des_chan;
 1955                         if (chan != NULL) {
 1956                                 ieee80211_create_ibss(vap, chan);
 1957                                 return 1;
 1958                         }
 1959                 }
 1960                 /*
 1961                  * If nothing suitable was found decrement
 1962                  * the failure counts so entries will be
 1963                  * reconsidered the next time around.  We
 1964                  * really want to do this only for sta's
 1965                  * where we've previously had some success.
 1966                  */
 1967                 sta_dec_fails(st);
 1968                 st->st_newscan = 1;
 1969                 return 0;                       /* restart scan */
 1970         }
 1971         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1972         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1973                 return (selbs != NULL);
 1974         if (selbs == NULL)
 1975                 goto notfound;
 1976         chan = selbs->base.se_chan;
 1977         if (selbs->se_flags & STA_DEMOTE11B)
 1978                 chan = demote11b(vap, chan);
 1979         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1980                 goto notfound;
 1981         return 1;                               /* terminate scan */
 1982 }
 1983 
 1984 static const struct ieee80211_scanner mesh_default = {
 1985         .scan_name              = "default",
 1986         .scan_attach            = sta_attach,
 1987         .scan_detach            = sta_detach,
 1988         .scan_start             = adhoc_start,
 1989         .scan_restart           = sta_restart,
 1990         .scan_cancel            = sta_cancel,
 1991         .scan_end               = mesh_pick_bss,
 1992         .scan_flush             = sta_flush,
 1993         .scan_pickchan          = adhoc_pick_channel,
 1994         .scan_add               = sta_add,
 1995         .scan_age               = adhoc_age,
 1996         .scan_iterate           = sta_iterate,
 1997         .scan_assoc_fail        = sta_assoc_fail,
 1998         .scan_assoc_success     = sta_assoc_success,
 1999 };
 2000 IEEE80211_SCANNER_ALG(mesh, IEEE80211_M_MBSS, mesh_default);
 2001 #endif /* IEEE80211_SUPPORT_MESH */

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