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: releng/12.0/sys/net80211/ieee80211_scan_sta.c 327231 2017-12-27 03:23:21Z eadler $");
   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 };
  476 
  477 static void
  478 add_channels(struct ieee80211vap *vap,
  479         struct ieee80211_scan_state *ss,
  480         enum ieee80211_phymode mode, const uint16_t freq[], int nfreq)
  481 {
  482         struct ieee80211com *ic = vap->iv_ic;
  483         struct ieee80211_channel *c, *cg;
  484         u_int modeflags;
  485         int i;
  486 
  487         KASSERT(mode < nitems(chanflags), ("Unexpected mode %u", mode));
  488         modeflags = chanflags[mode];
  489         for (i = 0; i < nfreq; i++) {
  490                 if (ss->ss_last >= IEEE80211_SCAN_MAX)
  491                         break;
  492 
  493                 c = ieee80211_find_channel(ic, freq[i], modeflags);
  494                 if (c == NULL || isexcluded(vap, c))
  495                         continue;
  496                 if (mode == IEEE80211_MODE_AUTO) {
  497                         /*
  498                          * XXX special-case 11b/g channels so we select
  499                          *     the g channel if both are present.
  500                          */
  501                         if (IEEE80211_IS_CHAN_B(c) &&
  502                             (cg = find11gchannel(ic, i, c->ic_freq)) != NULL)
  503                                 c = cg;
  504                 }
  505                 ss->ss_chans[ss->ss_last++] = c;
  506         }
  507 }
  508 
  509 struct scanlist {
  510         uint16_t        mode;
  511         uint16_t        count;
  512         const uint16_t  *list;
  513 };
  514 
  515 static int
  516 checktable(const struct scanlist *scan, const struct ieee80211_channel *c)
  517 {
  518         int i;
  519 
  520         for (; scan->list != NULL; scan++) {
  521                 for (i = 0; i < scan->count; i++)
  522                         if (scan->list[i] == c->ic_freq) 
  523                                 return 1;
  524         }
  525         return 0;
  526 }
  527 
  528 static int
  529 onscanlist(const struct ieee80211_scan_state *ss,
  530         const struct ieee80211_channel *c)
  531 {
  532         int i;
  533 
  534         for (i = 0; i < ss->ss_last; i++)
  535                 if (ss->ss_chans[i] == c)
  536                         return 1;
  537         return 0;
  538 }
  539 
  540 static void
  541 sweepchannels(struct ieee80211_scan_state *ss, struct ieee80211vap *vap,
  542         const struct scanlist table[])
  543 {
  544         struct ieee80211com *ic = vap->iv_ic;
  545         struct ieee80211_channel *c;
  546         int i;
  547 
  548         for (i = 0; i < ic->ic_nchans; i++) {
  549                 if (ss->ss_last >= IEEE80211_SCAN_MAX)
  550                         break;
  551 
  552                 c = &ic->ic_channels[i];
  553                 /*
  554                  * Ignore dynamic turbo channels; we scan them
  555                  * in normal mode (i.e. not boosted).  Likewise
  556                  * for HT/VHT channels, they get scanned using
  557                  * legacy rates.
  558                  */
  559                 if (IEEE80211_IS_CHAN_DTURBO(c) || IEEE80211_IS_CHAN_HT(c) ||
  560                     IEEE80211_IS_CHAN_VHT(c))
  561                         continue;
  562 
  563                 /*
  564                  * If a desired mode was specified, scan only 
  565                  * channels that satisfy that constraint.
  566                  */
  567                 if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
  568                     vap->iv_des_mode != ieee80211_chan2mode(c))
  569                         continue;
  570 
  571                 /*
  572                  * Skip channels excluded by user request.
  573                  */
  574                 if (isexcluded(vap, c))
  575                         continue;
  576 
  577                 /*
  578                  * Add the channel unless it is listed in the
  579                  * fixed scan order tables.  This insures we
  580                  * don't sweep back in channels we filtered out
  581                  * above.
  582                  */
  583                 if (checktable(table, c))
  584                         continue;
  585 
  586                 /* Add channel to scanning list. */
  587                 ss->ss_chans[ss->ss_last++] = c;
  588         }
  589         /*
  590          * Explicitly add any desired channel if:
  591          * - not already on the scan list
  592          * - allowed by any desired mode constraint
  593          * - there is space in the scan list
  594          * This allows the channel to be used when the filtering
  595          * mechanisms would otherwise elide it (e.g HT, turbo).
  596          */
  597         c = vap->iv_des_chan;
  598         if (c != IEEE80211_CHAN_ANYC &&
  599             !onscanlist(ss, c) &&
  600             (vap->iv_des_mode == IEEE80211_MODE_AUTO ||
  601              vap->iv_des_mode == ieee80211_chan2mode(c)) &&
  602             ss->ss_last < IEEE80211_SCAN_MAX)
  603                 ss->ss_chans[ss->ss_last++] = c;
  604 }
  605 
  606 static void
  607 makescanlist(struct ieee80211_scan_state *ss, struct ieee80211vap *vap,
  608         const struct scanlist table[])
  609 {
  610         const struct scanlist *scan;
  611         enum ieee80211_phymode mode;
  612 
  613         ss->ss_last = 0;
  614         /*
  615          * Use the table of ordered channels to construct the list
  616          * of channels for scanning.  Any channels in the ordered
  617          * list not in the master list will be discarded.
  618          */
  619         for (scan = table; scan->list != NULL; scan++) {
  620                 mode = scan->mode;
  621                 if (vap->iv_des_mode != IEEE80211_MODE_AUTO) {
  622                         /*
  623                          * If a desired mode was specified, scan only 
  624                          * channels that satisfy that constraint.
  625                          */
  626                         if (vap->iv_des_mode != mode) {
  627                                 /*
  628                                  * The scan table marks 2.4Ghz channels as b
  629                                  * so if the desired mode is 11g, then use
  630                                  * the 11b channel list but upgrade the mode.
  631                                  */
  632                                 if (vap->iv_des_mode == IEEE80211_MODE_11G) {
  633                                         if (mode == IEEE80211_MODE_11G) /* Skip the G check */
  634                                                 continue;
  635                                         else if (mode == IEEE80211_MODE_11B)
  636                                                 mode = IEEE80211_MODE_11G;      /* upgrade */
  637                                 }
  638                         }
  639                 } else {
  640                         /*
  641                          * This lets add_channels upgrade an 11b channel
  642                          * to 11g if available.
  643                          */
  644                         if (mode == IEEE80211_MODE_11B)
  645                                 mode = IEEE80211_MODE_AUTO;
  646                 }
  647 #ifdef IEEE80211_F_XR
  648                 /* XR does not operate on turbo channels */
  649                 if ((vap->iv_flags & IEEE80211_F_XR) &&
  650                     (mode == IEEE80211_MODE_TURBO_A ||
  651                      mode == IEEE80211_MODE_TURBO_G ||
  652                      mode == IEEE80211_MODE_STURBO_A))
  653                         continue;
  654 #endif
  655                 /*
  656                  * Add the list of the channels; any that are not
  657                  * in the master channel list will be discarded.
  658                  */
  659                 add_channels(vap, ss, mode, scan->list, scan->count);
  660         }
  661 
  662         /*
  663          * Add the channels from the ic that are not present
  664          * in the table.
  665          */
  666         sweepchannels(ss, vap, table);
  667 }
  668 
  669 static const uint16_t rcl1[] =          /* 8 FCC channel: 52, 56, 60, 64, 36, 40, 44, 48 */
  670 { 5260, 5280, 5300, 5320, 5180, 5200, 5220, 5240 };
  671 static const uint16_t rcl2[] =          /* 4 MKK channels: 34, 38, 42, 46 */
  672 { 5170, 5190, 5210, 5230 };
  673 static const uint16_t rcl3[] =          /* 2.4Ghz ch: 1,6,11,7,13 */
  674 { 2412, 2437, 2462, 2442, 2472 };
  675 static const uint16_t rcl4[] =          /* 5 FCC channel: 149, 153, 161, 165 */
  676 { 5745, 5765, 5785, 5805, 5825 };
  677 static const uint16_t rcl7[] =          /* 11 ETSI channel: 100,104,108,112,116,120,124,128,132,136,140 */
  678 { 5500, 5520, 5540, 5560, 5580, 5600, 5620, 5640, 5660, 5680, 5700 };
  679 static const uint16_t rcl8[] =          /* 2.4Ghz ch: 2,3,4,5,8,9,10,12 */
  680 { 2417, 2422, 2427, 2432, 2447, 2452, 2457, 2467 };
  681 static const uint16_t rcl9[] =          /* 2.4Ghz ch: 14 */
  682 { 2484 };
  683 static const uint16_t rcl10[] = /* Added Korean channels 2312-2372 */
  684 { 2312, 2317, 2322, 2327, 2332, 2337, 2342, 2347, 2352, 2357, 2362, 2367, 2372 };
  685 static const uint16_t rcl11[] = /* Added Japan channels in 4.9/5.0 spectrum */
  686 { 5040, 5060, 5080, 4920, 4940, 4960, 4980 };
  687 #ifdef ATH_TURBO_SCAN
  688 static const uint16_t rcl5[] =          /* 3 static turbo channels */
  689 { 5210, 5250, 5290 };
  690 static const uint16_t rcl6[] =          /* 2 static turbo channels */
  691 { 5760, 5800 };
  692 static const uint16_t rcl6x[] = /* 4 FCC3 turbo channels */
  693 { 5540, 5580, 5620, 5660 };
  694 static const uint16_t rcl12[] = /* 2.4Ghz Turbo channel 6 */
  695 { 2437 };
  696 static const uint16_t rcl13[] = /* dynamic Turbo channels */
  697 { 5200, 5240, 5280, 5765, 5805 };
  698 #endif /* ATH_TURBO_SCAN */
  699 
  700 #define X(a)    .count = sizeof(a)/sizeof(a[0]), .list = a
  701 
  702 static const struct scanlist staScanTable[] = {
  703         { IEEE80211_MODE_11B,           X(rcl3) },
  704         { IEEE80211_MODE_11A,           X(rcl1) },
  705         { IEEE80211_MODE_11A,           X(rcl2) },
  706         { IEEE80211_MODE_11B,           X(rcl8) },
  707         { IEEE80211_MODE_11B,           X(rcl9) },
  708         { IEEE80211_MODE_11A,           X(rcl4) },
  709 #ifdef ATH_TURBO_SCAN
  710         { IEEE80211_MODE_STURBO_A,      X(rcl5) },
  711         { IEEE80211_MODE_STURBO_A,      X(rcl6) },
  712         { IEEE80211_MODE_TURBO_A,       X(rcl6x) },
  713         { IEEE80211_MODE_TURBO_A,       X(rcl13) },
  714 #endif /* ATH_TURBO_SCAN */
  715         { IEEE80211_MODE_11A,           X(rcl7) },
  716         { IEEE80211_MODE_11B,           X(rcl10) },
  717         { IEEE80211_MODE_11A,           X(rcl11) },
  718 #ifdef ATH_TURBO_SCAN
  719         { IEEE80211_MODE_TURBO_G,       X(rcl12) },
  720 #endif /* ATH_TURBO_SCAN */
  721         { .list = NULL }
  722 };
  723 
  724 /*
  725  * Start a station-mode scan by populating the channel list.
  726  */
  727 static int
  728 sta_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  729 {
  730         struct sta_table *st = ss->ss_priv;
  731 
  732         makescanlist(ss, vap, staScanTable);
  733 
  734         if (ss->ss_mindwell == 0)
  735                 ss->ss_mindwell = msecs_to_ticks(20);   /* 20ms */
  736         if (ss->ss_maxdwell == 0)
  737                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
  738 
  739         st->st_scangen++;
  740         st->st_newscan = 1;
  741 
  742         return 0;
  743 }
  744 
  745 /*
  746  * Restart a scan, typically a bg scan but can
  747  * also be a fg scan that came up empty.
  748  */
  749 static int
  750 sta_restart(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  751 {
  752         struct sta_table *st = ss->ss_priv;
  753 
  754         st->st_newscan = 1;
  755         return 0;
  756 }
  757 
  758 /*
  759  * Cancel an ongoing scan.
  760  */
  761 static int
  762 sta_cancel(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
  763 {
  764         return 0;
  765 }
  766 
  767 /*
  768  * Demote any supplied 11g channel to 11b.  There should
  769  * always be an 11b channel but we check anyway...
  770  */
  771 static struct ieee80211_channel *
  772 demote11b(struct ieee80211vap *vap, struct ieee80211_channel *chan)
  773 {
  774         struct ieee80211_channel *c;
  775 
  776         if (IEEE80211_IS_CHAN_ANYG(chan) &&
  777             vap->iv_des_mode == IEEE80211_MODE_AUTO) {
  778                 c = ieee80211_find_channel(vap->iv_ic, chan->ic_freq,
  779                     (chan->ic_flags &~ (IEEE80211_CHAN_PUREG | IEEE80211_CHAN_G)) |
  780                     IEEE80211_CHAN_B);
  781                 if (c != NULL)
  782                         chan = c;
  783         }
  784         return chan;
  785 }
  786 
  787 static int
  788 maxrate(const struct ieee80211_scan_entry *se)
  789 {
  790         const struct ieee80211_ie_htcap *htcap =
  791             (const struct ieee80211_ie_htcap *) se->se_ies.htcap_ie;
  792         int rmax, r, i, txstream;
  793         uint16_t caps;
  794         uint8_t txparams;
  795 
  796         rmax = 0;
  797         if (htcap != NULL) {
  798                 /*
  799                  * HT station; inspect supported MCS and then adjust
  800                  * rate by channel width.
  801                  */
  802                 txparams = htcap->hc_mcsset[12];
  803                 if (txparams & 0x3) {
  804                         /*
  805                          * TX MCS parameters defined and not equal to RX,
  806                          * extract the number of spartial streams and
  807                          * map it to the highest MCS rate.
  808                          */
  809                         txstream = ((txparams & 0xc) >> 2) + 1;
  810                         i = txstream * 8 - 1;
  811                 } else
  812                         for (i = 31; i >= 0 && isclr(htcap->hc_mcsset, i); i--);
  813                 if (i >= 0) {
  814                         caps = le16dec(&htcap->hc_cap);
  815                         if ((caps & IEEE80211_HTCAP_CHWIDTH40) &&
  816                             (caps & IEEE80211_HTCAP_SHORTGI40))
  817                                 rmax = ieee80211_htrates[i].ht40_rate_400ns;
  818                         else if (caps & IEEE80211_HTCAP_CHWIDTH40)
  819                                 rmax = ieee80211_htrates[i].ht40_rate_800ns;
  820                         else if (caps & IEEE80211_HTCAP_SHORTGI20)
  821                                 rmax = ieee80211_htrates[i].ht20_rate_400ns;
  822                         else
  823                                 rmax = ieee80211_htrates[i].ht20_rate_800ns;
  824                 }
  825         }
  826         for (i = 0; i < se->se_rates[1]; i++) {
  827                 r = se->se_rates[2+i] & IEEE80211_RATE_VAL;
  828                 if (r > rmax)
  829                         rmax = r;
  830         }
  831         for (i = 0; i < se->se_xrates[1]; i++) {
  832                 r = se->se_xrates[2+i] & IEEE80211_RATE_VAL;
  833                 if (r > rmax)
  834                         rmax = r;
  835         }
  836         return rmax;
  837 }
  838 
  839 /*
  840  * Compare the capabilities of two entries and decide which is
  841  * more desirable (return >0 if a is considered better).  Note
  842  * that we assume compatibility/usability has already been checked
  843  * so we don't need to (e.g. validate whether privacy is supported).
  844  * Used to select the best scan candidate for association in a BSS.
  845  *
  846  * TODO: should we take 11n, 11ac into account when selecting the
  847  * best?  Right now it just compares frequency band and RSSI.
  848  */
  849 static int
  850 sta_compare(const struct sta_entry *a, const struct sta_entry *b)
  851 {
  852 #define PREFER(_a,_b,_what) do {                        \
  853         if (((_a) ^ (_b)) & (_what))                    \
  854                 return ((_a) & (_what)) ? 1 : -1;       \
  855 } while (0)
  856         int maxa, maxb;
  857         int8_t rssia, rssib;
  858         int weight;
  859 
  860         /* privacy support */
  861         PREFER(a->base.se_capinfo, b->base.se_capinfo,
  862                 IEEE80211_CAPINFO_PRIVACY);
  863 
  864         /* compare count of previous failures */
  865         weight = b->se_fails - a->se_fails;
  866         if (abs(weight) > 1)
  867                 return weight;
  868 
  869         /*
  870          * Compare rssi.  If the two are considered equivalent
  871          * then fallback to other criteria.  We threshold the
  872          * comparisons to avoid selecting an ap purely by rssi
  873          * when both values may be good but one ap is otherwise
  874          * more desirable (e.g. an 11b-only ap with stronger
  875          * signal than an 11g ap).
  876          */
  877         rssia = MIN(a->base.se_rssi, STA_RSSI_MAX);
  878         rssib = MIN(b->base.se_rssi, STA_RSSI_MAX);
  879         if (abs(rssib - rssia) < 5) {
  880                 /* best/max rate preferred if signal level close enough XXX */
  881                 maxa = maxrate(&a->base);
  882                 maxb = maxrate(&b->base);
  883                 if (maxa != maxb)
  884                         return maxa - maxb;
  885                 /* XXX use freq for channel preference */
  886                 /* for now just prefer 5Ghz band to all other bands */
  887                 PREFER(IEEE80211_IS_CHAN_5GHZ(a->base.se_chan),
  888                        IEEE80211_IS_CHAN_5GHZ(b->base.se_chan), 1);
  889         }
  890         /* all things being equal, use signal level */
  891         return a->base.se_rssi - b->base.se_rssi;
  892 #undef PREFER
  893 }
  894 
  895 /*
  896  * Check rate set suitability and return the best supported rate.
  897  * XXX inspect MCS for HT
  898  */
  899 static int
  900 check_rate(struct ieee80211vap *vap, const struct ieee80211_channel *chan,
  901     const struct ieee80211_scan_entry *se)
  902 {
  903         const struct ieee80211_rateset *srs;
  904         int i, j, nrs, r, okrate, badrate, fixedrate, ucastrate;
  905         const uint8_t *rs;
  906 
  907         okrate = badrate = 0;
  908 
  909         srs = ieee80211_get_suprates(vap->iv_ic, chan);
  910         nrs = se->se_rates[1];
  911         rs = se->se_rates+2;
  912         /* XXX MCS */
  913         ucastrate = vap->iv_txparms[ieee80211_chan2mode(chan)].ucastrate;
  914         fixedrate = IEEE80211_FIXED_RATE_NONE;
  915 again:
  916         for (i = 0; i < nrs; i++) {
  917                 r = IEEE80211_RV(rs[i]);
  918                 badrate = r;
  919                 /*
  920                  * Check any fixed rate is included. 
  921                  */
  922                 if (r == ucastrate)
  923                         fixedrate = r;
  924                 /*
  925                  * Check against our supported rates.
  926                  */
  927                 for (j = 0; j < srs->rs_nrates; j++)
  928                         if (r == IEEE80211_RV(srs->rs_rates[j])) {
  929                                 if (r > okrate)         /* NB: track max */
  930                                         okrate = r;
  931                                 break;
  932                         }
  933 
  934                 if (j == srs->rs_nrates && (rs[i] & IEEE80211_RATE_BASIC)) {
  935                         /*
  936                          * Don't try joining a BSS, if we don't support
  937                          * one of its basic rates.
  938                          */
  939                         okrate = 0;
  940                         goto back;
  941                 }
  942         }
  943         if (rs == se->se_rates+2) {
  944                 /* scan xrates too; sort of an algol68-style for loop */
  945                 nrs = se->se_xrates[1];
  946                 rs = se->se_xrates+2;
  947                 goto again;
  948         }
  949 
  950 back:
  951         if (okrate == 0 || ucastrate != fixedrate)
  952                 return badrate | IEEE80211_RATE_BASIC;
  953         else
  954                 return IEEE80211_RV(okrate);
  955 }
  956 
  957 static __inline int
  958 match_id(const uint8_t *ie, const uint8_t *val, int len)
  959 {
  960         return (ie[1] == len && memcmp(ie+2, val, len) == 0);
  961 }
  962 
  963 static int
  964 match_ssid(const uint8_t *ie,
  965         int nssid, const struct ieee80211_scan_ssid ssids[])
  966 {
  967         int i;
  968 
  969         for (i = 0; i < nssid; i++) {
  970                 if (match_id(ie, ssids[i].ssid, ssids[i].len))
  971                         return 1;
  972         }
  973         return 0;
  974 }
  975 
  976 #ifdef IEEE80211_SUPPORT_TDMA
  977 static int
  978 tdma_isfull(const struct ieee80211_tdma_param *tdma)
  979 {
  980         int slot, slotcnt;
  981 
  982         slotcnt = tdma->tdma_slotcnt;
  983         for (slot = slotcnt-1; slot >= 0; slot--)
  984                 if (isclr(tdma->tdma_inuse, slot))
  985                         return 0;
  986         return 1;
  987 }
  988 #endif /* IEEE80211_SUPPORT_TDMA */
  989 
  990 /*
  991  * Test a scan candidate for suitability/compatibility.
  992  */
  993 static int
  994 match_bss(struct ieee80211vap *vap,
  995         const struct ieee80211_scan_state *ss, struct sta_entry *se0,
  996         int debug)
  997 {
  998         struct ieee80211com *ic = vap->iv_ic;
  999         struct ieee80211_scan_entry *se = &se0->base;
 1000         uint8_t rate;
 1001         int fail;
 1002 
 1003         fail = 0;
 1004         if (isclr(ic->ic_chan_active, ieee80211_chan2ieee(ic, se->se_chan)))
 1005                 fail |= MATCH_CHANNEL;
 1006         /*
 1007          * NB: normally the desired mode is used to construct
 1008          * the channel list, but it's possible for the scan
 1009          * cache to include entries for stations outside this
 1010          * list so we check the desired mode here to weed them
 1011          * out.
 1012          */
 1013         if (vap->iv_des_mode != IEEE80211_MODE_AUTO &&
 1014             (se->se_chan->ic_flags & IEEE80211_CHAN_ALLTURBO) !=
 1015             chanflags[vap->iv_des_mode])
 1016                 fail |= MATCH_CHANNEL;
 1017         if (vap->iv_opmode == IEEE80211_M_IBSS) {
 1018                 if ((se->se_capinfo & IEEE80211_CAPINFO_IBSS) == 0)
 1019                         fail |= MATCH_CAPINFO;
 1020 #ifdef IEEE80211_SUPPORT_TDMA
 1021         } else if (vap->iv_opmode == IEEE80211_M_AHDEMO) {
 1022                 /*
 1023                  * Adhoc demo network setup shouldn't really be scanning
 1024                  * but just in case skip stations operating in IBSS or
 1025                  * BSS mode.
 1026                  */
 1027                 if (se->se_capinfo & (IEEE80211_CAPINFO_IBSS|IEEE80211_CAPINFO_ESS))
 1028                         fail |= MATCH_CAPINFO;
 1029                 /*
 1030                  * TDMA operation cannot coexist with a normal 802.11 network;
 1031                  * skip if IBSS or ESS capabilities are marked and require
 1032                  * the beacon have a TDMA ie present.
 1033                  */
 1034                 if (vap->iv_caps & IEEE80211_C_TDMA) {
 1035                         const struct ieee80211_tdma_param *tdma =
 1036                             (const struct ieee80211_tdma_param *)se->se_ies.tdma_ie;
 1037                         const struct ieee80211_tdma_state *ts = vap->iv_tdma;
 1038 
 1039                         if (tdma == NULL)
 1040                                 fail |= MATCH_TDMA_NOIE;
 1041                         else if (tdma->tdma_version != ts->tdma_version)
 1042                                 fail |= MATCH_TDMA_VERSION;
 1043                         else if (tdma->tdma_slot != 0)
 1044                                 fail |= MATCH_TDMA_NOTMASTER;
 1045                         else if (tdma_isfull(tdma))
 1046                                 fail |= MATCH_TDMA_NOSLOT;
 1047 #if 0
 1048                         else if (ieee80211_local_address(se->se_macaddr))
 1049                                 fail |= MATCH_TDMA_LOCAL;
 1050 #endif
 1051                 }
 1052 #endif /* IEEE80211_SUPPORT_TDMA */
 1053 #ifdef IEEE80211_SUPPORT_MESH
 1054         } else if (vap->iv_opmode == IEEE80211_M_MBSS) {
 1055                 const struct ieee80211_mesh_state *ms = vap->iv_mesh;
 1056                 /*
 1057                  * Mesh nodes have IBSS & ESS bits in capinfo turned off
 1058                  * and two special ie's that must be present.
 1059                  */
 1060                 if (se->se_capinfo & (IEEE80211_CAPINFO_IBSS|IEEE80211_CAPINFO_ESS))
 1061                         fail |= MATCH_CAPINFO;
 1062                 else if (se->se_meshid[0] != IEEE80211_ELEMID_MESHID)
 1063                         fail |= MATCH_MESH_NOID;
 1064                 else if (ms->ms_idlen != 0 &&
 1065                     match_id(se->se_meshid, ms->ms_id, ms->ms_idlen))
 1066                         fail |= MATCH_MESHID;
 1067 #endif
 1068         } else {
 1069                 if ((se->se_capinfo & IEEE80211_CAPINFO_ESS) == 0)
 1070                         fail |= MATCH_CAPINFO;
 1071                 /*
 1072                  * If 11d is enabled and we're attempting to join a bss
 1073                  * that advertises it's country code then compare our
 1074                  * current settings to what we fetched from the country ie.
 1075                  * If our country code is unspecified or different then do
 1076                  * not attempt to join the bss.  We should have already
 1077                  * dispatched an event to user space that identifies the
 1078                  * new country code so our regdomain config should match.
 1079                  */
 1080                 if ((IEEE80211_IS_CHAN_11D(se->se_chan) ||
 1081                     (vap->iv_flags_ext & IEEE80211_FEXT_DOTD)) &&
 1082                     se->se_cc[0] != 0 &&
 1083                     (ic->ic_regdomain.country == CTRY_DEFAULT ||
 1084                      !isocmp(se->se_cc, ic->ic_regdomain.isocc)))
 1085                         fail |= MATCH_CC;
 1086         }
 1087         if (vap->iv_flags & IEEE80211_F_PRIVACY) {
 1088                 if ((se->se_capinfo & IEEE80211_CAPINFO_PRIVACY) == 0)
 1089                         fail |= MATCH_PRIVACY;
 1090         } else {
 1091                 /* XXX does this mean privacy is supported or required? */
 1092                 if (se->se_capinfo & IEEE80211_CAPINFO_PRIVACY)
 1093                         fail |= MATCH_PRIVACY;
 1094         }
 1095         se0->se_flags &= ~STA_DEMOTE11B;
 1096         rate = check_rate(vap, se->se_chan, se);
 1097         if (rate & IEEE80211_RATE_BASIC) {
 1098                 fail |= MATCH_RATE;
 1099                 /*
 1100                  * An 11b-only ap will give a rate mismatch if there is an
 1101                  * OFDM fixed tx rate for 11g.  Try downgrading the channel
 1102                  * in the scan list to 11b and retry the rate check.
 1103                  */
 1104                 if (IEEE80211_IS_CHAN_ANYG(se->se_chan)) {
 1105                         rate = check_rate(vap, demote11b(vap, se->se_chan), se);
 1106                         if ((rate & IEEE80211_RATE_BASIC) == 0) {
 1107                                 fail &= ~MATCH_RATE;
 1108                                 se0->se_flags |= STA_DEMOTE11B;
 1109                         }
 1110                 }
 1111         } else if (rate < 2*24) {
 1112                 /*
 1113                  * This is an 11b-only ap.  Check the desired mode in
 1114                  * case that needs to be honored (mode 11g filters out
 1115                  * 11b-only ap's).  Otherwise force any 11g channel used
 1116                  * in scanning to be demoted.
 1117                  *
 1118                  * NB: we cheat a bit here by looking at the max rate;
 1119                  *     we could/should check the rates.
 1120                  */
 1121                 if (!(vap->iv_des_mode == IEEE80211_MODE_AUTO ||
 1122                       vap->iv_des_mode == IEEE80211_MODE_11B))
 1123                         fail |= MATCH_RATE;
 1124                 else
 1125                         se0->se_flags |= STA_DEMOTE11B;
 1126         }
 1127         if (ss->ss_nssid != 0 &&
 1128             !match_ssid(se->se_ssid, ss->ss_nssid, ss->ss_ssid))
 1129                 fail |= MATCH_SSID;
 1130         if ((vap->iv_flags & IEEE80211_F_DESBSSID) &&
 1131             !IEEE80211_ADDR_EQ(vap->iv_des_bssid, se->se_bssid))
 1132                 fail |= MATCH_BSSID;
 1133         if (se0->se_fails >= STA_FAILS_MAX)
 1134                 fail |= MATCH_FAILS;
 1135         if (se0->se_notseen >= STA_PURGE_SCANS)
 1136                 fail |= MATCH_NOTSEEN;
 1137         if (se->se_rssi < STA_RSSI_MIN)
 1138                 fail |= MATCH_RSSI;
 1139 #ifdef IEEE80211_DEBUG
 1140         if (ieee80211_msg(vap, debug)) {
 1141                 printf(" %c %s",
 1142                     fail & MATCH_FAILS ? '=' :
 1143                     fail & MATCH_NOTSEEN ? '^' :
 1144                     fail & MATCH_CC ? '$' :
 1145 #ifdef IEEE80211_SUPPORT_TDMA
 1146                     fail & MATCH_TDMA_NOIE ? '&' :
 1147                     fail & MATCH_TDMA_VERSION ? 'v' :
 1148                     fail & MATCH_TDMA_NOTMASTER ? 's' :
 1149                     fail & MATCH_TDMA_NOSLOT ? 'f' :
 1150                     fail & MATCH_TDMA_LOCAL ? 'l' :
 1151 #endif
 1152                     fail & MATCH_MESH_NOID ? 'm' :
 1153                     fail ? '-' : '+', ether_sprintf(se->se_macaddr));
 1154                 printf(" %s%c", ether_sprintf(se->se_bssid),
 1155                     fail & MATCH_BSSID ? '!' : ' ');
 1156                 printf(" %3d%c", ieee80211_chan2ieee(ic, se->se_chan),
 1157                         fail & MATCH_CHANNEL ? '!' : ' ');
 1158                 printf(" %+4d%c", se->se_rssi, fail & MATCH_RSSI ? '!' : ' ');
 1159                 printf(" %2dM%c", (rate & IEEE80211_RATE_VAL) / 2,
 1160                     fail & MATCH_RATE ? '!' : ' ');
 1161                 printf(" %4s%c",
 1162                     (se->se_capinfo & IEEE80211_CAPINFO_ESS) ? "ess" :
 1163                     (se->se_capinfo & IEEE80211_CAPINFO_IBSS) ? "ibss" : "",
 1164                     fail & MATCH_CAPINFO ? '!' : ' ');
 1165                 printf(" %3s%c ",
 1166                     (se->se_capinfo & IEEE80211_CAPINFO_PRIVACY) ?
 1167                     "wep" : "no",
 1168                     fail & MATCH_PRIVACY ? '!' : ' ');
 1169                 ieee80211_print_essid(se->se_ssid+2, se->se_ssid[1]);
 1170                 printf("%s\n", fail & (MATCH_SSID | MATCH_MESHID) ? "!" : "");
 1171         }
 1172 #endif
 1173         return fail;
 1174 }
 1175 
 1176 static void
 1177 sta_update_notseen(struct sta_table *st)
 1178 {
 1179         struct sta_entry *se;
 1180 
 1181         IEEE80211_SCAN_TABLE_LOCK(st);
 1182         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1183                 /*
 1184                  * If seen the reset and don't bump the count;
 1185                  * otherwise bump the ``not seen'' count.  Note
 1186                  * that this insures that stations for which we
 1187                  * see frames while not scanning but not during
 1188                  * this scan will not be penalized.
 1189                  */
 1190                 if (se->se_seen)
 1191                         se->se_seen = 0;
 1192                 else
 1193                         se->se_notseen++;
 1194         }
 1195         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1196 }
 1197 
 1198 static void
 1199 sta_dec_fails(struct sta_table *st)
 1200 {
 1201         struct sta_entry *se;
 1202 
 1203         IEEE80211_SCAN_TABLE_LOCK(st);
 1204         TAILQ_FOREACH(se, &st->st_entry, se_list)
 1205                 if (se->se_fails)
 1206                         se->se_fails--;
 1207         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1208 }
 1209 
 1210 static struct sta_entry *
 1211 select_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap, int debug)
 1212 {
 1213         struct sta_table *st = ss->ss_priv;
 1214         struct sta_entry *se, *selbs = NULL;
 1215 
 1216         IEEE80211_DPRINTF(vap, debug, " %s\n",
 1217             "macaddr          bssid         chan  rssi  rate flag  wep  essid");
 1218         IEEE80211_SCAN_TABLE_LOCK(st);
 1219         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1220                 ieee80211_ies_expand(&se->base.se_ies);
 1221                 if (match_bss(vap, ss, se, debug) == 0) {
 1222                         if (selbs == NULL)
 1223                                 selbs = se;
 1224                         else if (sta_compare(se, selbs) > 0)
 1225                                 selbs = se;
 1226                 }
 1227         }
 1228         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1229 
 1230         return selbs;
 1231 }
 1232 
 1233 /*
 1234  * Pick an ap or ibss network to join or find a channel
 1235  * to use to start an ibss network.
 1236  */
 1237 static int
 1238 sta_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1239 {
 1240         struct sta_table *st = ss->ss_priv;
 1241         struct sta_entry *selbs;
 1242         struct ieee80211_channel *chan;
 1243 
 1244         KASSERT(vap->iv_opmode == IEEE80211_M_STA,
 1245                 ("wrong mode %u", vap->iv_opmode));
 1246 
 1247         if (st->st_newscan) {
 1248                 sta_update_notseen(st);
 1249                 st->st_newscan = 0;
 1250         }
 1251         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1252                 /*
 1253                  * Manual/background scan, don't select+join the
 1254                  * bss, just return.  The scanning framework will
 1255                  * handle notification that this has completed.
 1256                  */
 1257                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1258                 return 1;
 1259         }
 1260         /*
 1261          * Automatic sequencing; look for a candidate and
 1262          * if found join the network.
 1263          */
 1264         /* NB: unlocked read should be ok */
 1265         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1266                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1267                         "%s: no scan candidate\n", __func__);
 1268                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1269                         return 0;
 1270 notfound:
 1271                 /*
 1272                  * If nothing suitable was found decrement
 1273                  * the failure counts so entries will be
 1274                  * reconsidered the next time around.  We
 1275                  * really want to do this only for sta's
 1276                  * where we've previously had some success.
 1277                  */
 1278                 sta_dec_fails(st);
 1279                 st->st_newscan = 1;
 1280                 return 0;                       /* restart scan */
 1281         }
 1282         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1283         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1284                 return (selbs != NULL);
 1285         if (selbs == NULL)
 1286                 goto notfound;
 1287         chan = selbs->base.se_chan;
 1288         if (selbs->se_flags & STA_DEMOTE11B)
 1289                 chan = demote11b(vap, chan);
 1290         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1291                 goto notfound;
 1292         return 1;                               /* terminate scan */
 1293 }
 1294 
 1295 /*
 1296  * Lookup an entry in the scan cache.  We assume we're
 1297  * called from the bottom half or such that we don't need
 1298  * to block the bottom half so that it's safe to return
 1299  * a reference to an entry w/o holding the lock on the table.
 1300  */
 1301 static struct sta_entry *
 1302 sta_lookup(struct sta_table *st, const uint8_t macaddr[IEEE80211_ADDR_LEN])
 1303 {
 1304         struct sta_entry *se;
 1305         int hash = STA_HASH(macaddr);
 1306 
 1307         IEEE80211_SCAN_TABLE_LOCK(st);
 1308         LIST_FOREACH(se, &st->st_hash[hash], se_hash)
 1309                 if (IEEE80211_ADDR_EQ(se->base.se_macaddr, macaddr))
 1310                         break;
 1311         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1312 
 1313         return se;              /* NB: unlocked */
 1314 }
 1315 
 1316 static void
 1317 sta_roam_check(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1318 {
 1319         struct ieee80211com *ic = vap->iv_ic;
 1320         struct ieee80211_node *ni = vap->iv_bss;
 1321         struct sta_table *st = ss->ss_priv;
 1322         enum ieee80211_phymode mode;
 1323         struct sta_entry *se, *selbs;
 1324         uint8_t roamRate, curRate, ucastRate;
 1325         int8_t roamRssi, curRssi;
 1326 
 1327         se = sta_lookup(st, ni->ni_macaddr);
 1328         if (se == NULL) {
 1329                 /* XXX something is wrong */
 1330                 return;
 1331         }
 1332 
 1333         mode = ieee80211_chan2mode(ic->ic_bsschan);
 1334         roamRate = vap->iv_roamparms[mode].rate;
 1335         roamRssi = vap->iv_roamparms[mode].rssi;
 1336         ucastRate = vap->iv_txparms[mode].ucastrate;
 1337         /* NB: the most up to date rssi is in the node, not the scan cache */
 1338         curRssi = ic->ic_node_getrssi(ni);
 1339         if (ucastRate == IEEE80211_FIXED_RATE_NONE) {
 1340                 curRate = ni->ni_txrate;
 1341                 roamRate &= IEEE80211_RATE_VAL;
 1342                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_ROAM,
 1343                     "%s: currssi %d currate %u roamrssi %d roamrate %u\n",
 1344                     __func__, curRssi, curRate, roamRssi, roamRate);
 1345         } else {
 1346                 curRate = roamRate;     /* NB: insure compare below fails */
 1347                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_ROAM,
 1348                     "%s: currssi %d roamrssi %d\n", __func__, curRssi, roamRssi);
 1349         }
 1350         /*
 1351          * Check if a new ap should be used and switch.
 1352          * XXX deauth current ap
 1353          */
 1354         if (curRate < roamRate || curRssi < roamRssi) {
 1355                 if (ieee80211_time_after(ticks, ic->ic_lastscan + vap->iv_scanvalid)) {
 1356                         /*
 1357                          * Scan cache contents are too old; force a scan now
 1358                          * if possible so we have current state to make a
 1359                          * decision with.  We don't kick off a bg scan if
 1360                          * we're using dynamic turbo and boosted or if the
 1361                          * channel is busy.
 1362                          * XXX force immediate switch on scan complete
 1363                          */
 1364                         if (!IEEE80211_IS_CHAN_DTURBO(ic->ic_curchan) &&
 1365                             ((vap->iv_flags_ext & IEEE80211_FEXT_SCAN_OFFLOAD) ||
 1366                              ieee80211_time_after(ticks, ic->ic_lastdata + vap->iv_bgscanidle)))
 1367                                 ieee80211_bg_scan(vap, 0);
 1368                         return;
 1369                 }
 1370                 se->base.se_rssi = curRssi;
 1371                 selbs = select_bss(ss, vap, IEEE80211_MSG_ROAM);
 1372                 if (selbs != NULL && selbs != se) {
 1373                         struct ieee80211_channel *chan;
 1374 
 1375                         IEEE80211_DPRINTF(vap,
 1376                             IEEE80211_MSG_ROAM | IEEE80211_MSG_DEBUG,
 1377                             "%s: ROAM: curRate %u, roamRate %u, "
 1378                             "curRssi %d, roamRssi %d\n", __func__,
 1379                             curRate, roamRate, curRssi, roamRssi);
 1380 
 1381                         chan = selbs->base.se_chan;
 1382                         if (selbs->se_flags & STA_DEMOTE11B)
 1383                                 chan = demote11b(vap, chan);
 1384                         (void) ieee80211_sta_join(vap, chan, &selbs->base);
 1385                 }
 1386         }
 1387 }
 1388 
 1389 /*
 1390  * Age entries in the scan cache.
 1391  * XXX also do roaming since it's convenient
 1392  */
 1393 static void
 1394 sta_age(struct ieee80211_scan_state *ss)
 1395 {
 1396         struct ieee80211vap *vap = ss->ss_vap;
 1397 
 1398         adhoc_age(ss);
 1399         /*
 1400          * If rate control is enabled check periodically to see if
 1401          * we should roam from our current connection to one that
 1402          * might be better.  This only applies when we're operating
 1403          * in sta mode and automatic roaming is set.
 1404          * XXX defer if busy
 1405          * XXX repeater station
 1406          * XXX do when !bgscan?
 1407          */
 1408         KASSERT(vap->iv_opmode == IEEE80211_M_STA,
 1409                 ("wrong mode %u", vap->iv_opmode));
 1410         if (vap->iv_roaming == IEEE80211_ROAMING_AUTO &&
 1411             (vap->iv_flags & IEEE80211_F_BGSCAN) &&
 1412             vap->iv_state >= IEEE80211_S_RUN)
 1413                 /* XXX vap is implicit */
 1414                 sta_roam_check(ss, vap);
 1415 }
 1416 
 1417 /*
 1418  * Iterate over the entries in the scan cache, invoking
 1419  * the callback function on each one.
 1420  */
 1421 static void
 1422 sta_iterate(struct ieee80211_scan_state *ss, 
 1423         ieee80211_scan_iter_func *f, void *arg)
 1424 {
 1425         struct sta_table *st = ss->ss_priv;
 1426         struct sta_entry *se;
 1427         u_int gen;
 1428 
 1429         IEEE80211_SCAN_ITER_LOCK(st);
 1430         gen = st->st_scaniter++;
 1431 restart:
 1432         IEEE80211_SCAN_TABLE_LOCK(st);
 1433         TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1434                 if (se->se_scangen != gen) {
 1435                         se->se_scangen = gen;
 1436                         /* update public state */
 1437                         se->base.se_age = ticks - se->se_lastupdate;
 1438                         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1439                         (*f)(arg, &se->base);
 1440                         goto restart;
 1441                 }
 1442         }
 1443         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1444 
 1445         IEEE80211_SCAN_ITER_UNLOCK(st);
 1446 }
 1447 
 1448 static void
 1449 sta_assoc_fail(struct ieee80211_scan_state *ss,
 1450         const uint8_t macaddr[IEEE80211_ADDR_LEN], int reason)
 1451 {
 1452         struct sta_table *st = ss->ss_priv;
 1453         struct sta_entry *se;
 1454 
 1455         se = sta_lookup(st, macaddr);
 1456         if (se != NULL) {
 1457                 se->se_fails++;
 1458                 se->se_lastfail = ticks;
 1459                 IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
 1460                     macaddr, "%s: reason %u fails %u",
 1461                     __func__, reason, se->se_fails);
 1462         }
 1463 }
 1464 
 1465 static void
 1466 sta_assoc_success(struct ieee80211_scan_state *ss,
 1467         const uint8_t macaddr[IEEE80211_ADDR_LEN])
 1468 {
 1469         struct sta_table *st = ss->ss_priv;
 1470         struct sta_entry *se;
 1471 
 1472         se = sta_lookup(st, macaddr);
 1473         if (se != NULL) {
 1474 #if 0
 1475                 se->se_fails = 0;
 1476                 IEEE80211_NOTE_MAC(ss->ss_vap, IEEE80211_MSG_SCAN,
 1477                     macaddr, "%s: fails %u",
 1478                     __func__, se->se_fails);
 1479 #endif
 1480                 se->se_lastassoc = ticks;
 1481         }
 1482 }
 1483 
 1484 static const struct ieee80211_scanner sta_default = {
 1485         .scan_name              = "default",
 1486         .scan_attach            = sta_attach,
 1487         .scan_detach            = sta_detach,
 1488         .scan_start             = sta_start,
 1489         .scan_restart           = sta_restart,
 1490         .scan_cancel            = sta_cancel,
 1491         .scan_end               = sta_pick_bss,
 1492         .scan_flush             = sta_flush,
 1493         .scan_add               = sta_add,
 1494         .scan_age               = sta_age,
 1495         .scan_iterate           = sta_iterate,
 1496         .scan_assoc_fail        = sta_assoc_fail,
 1497         .scan_assoc_success     = sta_assoc_success,
 1498 };
 1499 IEEE80211_SCANNER_ALG(sta, IEEE80211_M_STA, sta_default);
 1500 
 1501 /*
 1502  * Adhoc mode-specific support.
 1503  */
 1504 
 1505 static const uint16_t adhocWorld[] =            /* 36, 40, 44, 48 */
 1506 { 5180, 5200, 5220, 5240 };
 1507 static const uint16_t adhocFcc3[] =             /* 36, 40, 44, 48 145, 149, 153, 157, 161, 165 */
 1508 { 5180, 5200, 5220, 5240, 5725, 5745, 5765, 5785, 5805, 5825 };
 1509 static const uint16_t adhocMkk[] =              /* 34, 38, 42, 46 */
 1510 { 5170, 5190, 5210, 5230 };
 1511 static const uint16_t adhoc11b[] =              /* 10, 11 */
 1512 { 2457, 2462 };
 1513 
 1514 static const struct scanlist adhocScanTable[] = {
 1515         { IEEE80211_MODE_11B,           X(adhoc11b) },
 1516         { IEEE80211_MODE_11A,           X(adhocWorld) },
 1517         { IEEE80211_MODE_11A,           X(adhocFcc3) },
 1518         { IEEE80211_MODE_11B,           X(adhocMkk) },
 1519         { .list = NULL }
 1520 };
 1521 #undef X
 1522 
 1523 /*
 1524  * Start an adhoc-mode scan by populating the channel list.
 1525  */
 1526 static int
 1527 adhoc_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1528 {
 1529         struct sta_table *st = ss->ss_priv;
 1530         
 1531         makescanlist(ss, vap, adhocScanTable);
 1532 
 1533         if (ss->ss_mindwell == 0)
 1534                 ss->ss_mindwell = msecs_to_ticks(200);  /* 200ms */
 1535         if (ss->ss_maxdwell == 0)
 1536                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
 1537 
 1538         st->st_scangen++;
 1539         st->st_newscan = 1;
 1540 
 1541         return 0;
 1542 }
 1543 
 1544 /*
 1545  * Select a channel to start an adhoc network on.
 1546  * The channel list was populated with appropriate
 1547  * channels so select one that looks least occupied.
 1548  */
 1549 static struct ieee80211_channel *
 1550 adhoc_pick_channel(struct ieee80211_scan_state *ss, int flags)
 1551 {
 1552         struct sta_table *st = ss->ss_priv;
 1553         struct sta_entry *se;
 1554         struct ieee80211_channel *c, *bestchan;
 1555         int i, bestrssi, maxrssi;
 1556 
 1557         bestchan = NULL;
 1558         bestrssi = -1;
 1559 
 1560         IEEE80211_SCAN_TABLE_LOCK(st);
 1561         for (i = 0; i < ss->ss_last; i++) {
 1562                 c = ss->ss_chans[i];
 1563                 /* never consider a channel with radar */
 1564                 if (IEEE80211_IS_CHAN_RADAR(c))
 1565                         continue;
 1566                 /* skip channels disallowed by regulatory settings */
 1567                 if (IEEE80211_IS_CHAN_NOADHOC(c))
 1568                         continue;
 1569                 /* check channel attributes for band compatibility */
 1570                 if (flags != 0 && (c->ic_flags & flags) != flags)
 1571                         continue;
 1572                 maxrssi = 0;
 1573                 TAILQ_FOREACH(se, &st->st_entry, se_list) {
 1574                         if (se->base.se_chan != c)
 1575                                 continue;
 1576                         if (se->base.se_rssi > maxrssi)
 1577                                 maxrssi = se->base.se_rssi;
 1578                 }
 1579                 if (bestchan == NULL || maxrssi < bestrssi)
 1580                         bestchan = c;
 1581         }
 1582         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1583 
 1584         return bestchan;
 1585 }
 1586 
 1587 /*
 1588  * Pick an ibss network to join or find a channel
 1589  * to use to start an ibss network.
 1590  */
 1591 static int
 1592 adhoc_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1593 {
 1594         struct sta_table *st = ss->ss_priv;
 1595         struct sta_entry *selbs;
 1596         struct ieee80211_channel *chan;
 1597         struct ieee80211com *ic = vap->iv_ic;
 1598 
 1599         KASSERT(vap->iv_opmode == IEEE80211_M_IBSS ||
 1600                 vap->iv_opmode == IEEE80211_M_AHDEMO ||
 1601                 vap->iv_opmode == IEEE80211_M_MBSS,
 1602                 ("wrong opmode %u", vap->iv_opmode));
 1603 
 1604         if (st->st_newscan) {
 1605                 sta_update_notseen(st);
 1606                 st->st_newscan = 0;
 1607         }
 1608         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1609                 /*
 1610                  * Manual/background scan, don't select+join the
 1611                  * bss, just return.  The scanning framework will
 1612                  * handle notification that this has completed.
 1613                  */
 1614                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1615                 return 1;
 1616         }
 1617         /*
 1618          * Automatic sequencing; look for a candidate and
 1619          * if found join the network.
 1620          */
 1621         /* NB: unlocked read should be ok */
 1622         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1623                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1624                         "%s: no scan candidate\n", __func__);
 1625                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1626                         return 0;
 1627 notfound:
 1628                 /* NB: never auto-start a tdma network for slot !0 */
 1629 #ifdef IEEE80211_SUPPORT_TDMA
 1630                 if (vap->iv_des_nssid &&
 1631                     ((vap->iv_caps & IEEE80211_C_TDMA) == 0 ||
 1632                      ieee80211_tdma_getslot(vap) == 0)) {
 1633 #else
 1634                 if (vap->iv_des_nssid) {
 1635 #endif
 1636                         /*
 1637                          * No existing adhoc network to join and we have
 1638                          * an ssid; start one up.  If no channel was
 1639                          * specified, try to select a channel.
 1640                          */
 1641                         if (vap->iv_des_chan == IEEE80211_CHAN_ANYC ||
 1642                             IEEE80211_IS_CHAN_RADAR(vap->iv_des_chan)) {
 1643                                 chan = adhoc_pick_channel(ss, 0);
 1644                         } else
 1645                                 chan = vap->iv_des_chan;
 1646                         if (chan != NULL) {
 1647                                 /*
 1648                                  * Create a HT capable IBSS; the per-node
 1649                                  * probe request/response will result in
 1650                                  * "correct" rate control capabilities being
 1651                                  * negotiated.
 1652                                  */
 1653                                 chan = ieee80211_ht_adjust_channel(ic,
 1654                                     chan, vap->iv_flags_ht);
 1655                                 chan = ieee80211_vht_adjust_channel(ic,
 1656                                     chan, vap->iv_flags_vht);
 1657                                 ieee80211_create_ibss(vap, chan);
 1658                                 return 1;
 1659                         }
 1660                 }
 1661                 /*
 1662                  * If nothing suitable was found decrement
 1663                  * the failure counts so entries will be
 1664                  * reconsidered the next time around.  We
 1665                  * really want to do this only for sta's
 1666                  * where we've previously had some success.
 1667                  */
 1668                 sta_dec_fails(st);
 1669                 st->st_newscan = 1;
 1670                 return 0;                       /* restart scan */
 1671         }
 1672         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1673         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1674                 return (selbs != NULL);
 1675         if (selbs == NULL)
 1676                 goto notfound;
 1677         chan = selbs->base.se_chan;
 1678         if (selbs->se_flags & STA_DEMOTE11B)
 1679                 chan = demote11b(vap, chan);
 1680         /*
 1681          * If HT is available, make it a possibility here.
 1682          * The intent is to enable HT20/HT40 when joining a non-HT
 1683          * IBSS node; we can then advertise HT IEs and speak HT
 1684          * to any subsequent nodes that support it.
 1685          */
 1686         chan = ieee80211_ht_adjust_channel(ic,
 1687             chan, vap->iv_flags_ht);
 1688         chan = ieee80211_vht_adjust_channel(ic,
 1689             chan, vap->iv_flags_vht);
 1690         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1691                 goto notfound;
 1692         return 1;                               /* terminate scan */
 1693 }
 1694 
 1695 /*
 1696  * Age entries in the scan cache.
 1697  */
 1698 static void
 1699 adhoc_age(struct ieee80211_scan_state *ss)
 1700 {
 1701         struct sta_table *st = ss->ss_priv;
 1702         struct sta_entry *se, *next;
 1703 
 1704         IEEE80211_SCAN_TABLE_LOCK(st);
 1705         TAILQ_FOREACH_SAFE(se, &st->st_entry, se_list, next) {
 1706                 if (se->se_notseen > STA_PURGE_SCANS) {
 1707                         TAILQ_REMOVE(&st->st_entry, se, se_list);
 1708                         LIST_REMOVE(se, se_hash);
 1709                         ieee80211_ies_cleanup(&se->base.se_ies);
 1710                         IEEE80211_FREE(se, M_80211_SCAN);
 1711                 }
 1712         }
 1713         IEEE80211_SCAN_TABLE_UNLOCK(st);
 1714 }
 1715 
 1716 static const struct ieee80211_scanner adhoc_default = {
 1717         .scan_name              = "default",
 1718         .scan_attach            = sta_attach,
 1719         .scan_detach            = sta_detach,
 1720         .scan_start             = adhoc_start,
 1721         .scan_restart           = sta_restart,
 1722         .scan_cancel            = sta_cancel,
 1723         .scan_end               = adhoc_pick_bss,
 1724         .scan_flush             = sta_flush,
 1725         .scan_pickchan          = adhoc_pick_channel,
 1726         .scan_add               = sta_add,
 1727         .scan_age               = adhoc_age,
 1728         .scan_iterate           = sta_iterate,
 1729         .scan_assoc_fail        = sta_assoc_fail,
 1730         .scan_assoc_success     = sta_assoc_success,
 1731 };
 1732 IEEE80211_SCANNER_ALG(ibss, IEEE80211_M_IBSS, adhoc_default);
 1733 IEEE80211_SCANNER_ALG(ahdemo, IEEE80211_M_AHDEMO, adhoc_default);
 1734 
 1735 static int
 1736 ap_start(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1737 {
 1738         struct sta_table *st = ss->ss_priv;
 1739 
 1740         makescanlist(ss, vap, staScanTable);
 1741 
 1742         if (ss->ss_mindwell == 0)
 1743                 ss->ss_mindwell = msecs_to_ticks(200);  /* 200ms */
 1744         if (ss->ss_maxdwell == 0)
 1745                 ss->ss_maxdwell = msecs_to_ticks(200);  /* 200ms */
 1746 
 1747         st->st_scangen++;
 1748         st->st_newscan = 1;
 1749 
 1750         return 0;
 1751 }
 1752 
 1753 /*
 1754  * Cancel an ongoing scan.
 1755  */
 1756 static int
 1757 ap_cancel(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1758 {
 1759         return 0;
 1760 }
 1761 
 1762 /*
 1763  * Pick a quiet channel to use for ap operation.
 1764  */
 1765 static struct ieee80211_channel *
 1766 ap_pick_channel(struct ieee80211_scan_state *ss, int flags)
 1767 {
 1768         struct sta_table *st = ss->ss_priv;
 1769         struct ieee80211_channel *bestchan = NULL;
 1770         int i;
 1771 
 1772         /* XXX select channel more intelligently, e.g. channel spread, power */
 1773         /* NB: use scan list order to preserve channel preference */
 1774         for (i = 0; i < ss->ss_last; i++) {
 1775                 struct ieee80211_channel *chan = ss->ss_chans[i];
 1776                 /*
 1777                  * If the channel is unoccupied the max rssi
 1778                  * should be zero; just take it.  Otherwise
 1779                  * track the channel with the lowest rssi and
 1780                  * use that when all channels appear occupied.
 1781                  */
 1782                 if (IEEE80211_IS_CHAN_RADAR(chan))
 1783                         continue;
 1784                 if (IEEE80211_IS_CHAN_NOHOSTAP(chan))
 1785                         continue;
 1786                 /* check channel attributes for band compatibility */
 1787                 if (flags != 0 && (chan->ic_flags & flags) != flags)
 1788                         continue;
 1789                 KASSERT(sizeof(chan->ic_ieee) == 1, ("ic_chan size"));
 1790                 /* XXX channel have interference */
 1791                 if (st->st_maxrssi[chan->ic_ieee] == 0) {
 1792                         /* XXX use other considerations */
 1793                         return chan;
 1794                 }
 1795                 if (bestchan == NULL ||
 1796                     st->st_maxrssi[chan->ic_ieee] < st->st_maxrssi[bestchan->ic_ieee])
 1797                         bestchan = chan;
 1798         }
 1799         return bestchan;
 1800 }
 1801 
 1802 /*
 1803  * Pick a quiet channel to use for ap operation.
 1804  */
 1805 static int
 1806 ap_end(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1807 {
 1808         struct ieee80211com *ic = vap->iv_ic;
 1809         struct ieee80211_channel *bestchan, *chan;
 1810 
 1811         KASSERT(vap->iv_opmode == IEEE80211_M_HOSTAP,
 1812                 ("wrong opmode %u", vap->iv_opmode));
 1813         bestchan = ap_pick_channel(ss, 0);
 1814         if (bestchan == NULL) {
 1815                 /* no suitable channel, should not happen */
 1816                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1817                     "%s: no suitable channel! (should not happen)\n", __func__);
 1818                 /* XXX print something? */
 1819                 return 0;                       /* restart scan */
 1820         }
 1821         /*
 1822          * If this is a dynamic turbo channel, start with the unboosted one.
 1823          */
 1824         if (IEEE80211_IS_CHAN_TURBO(bestchan)) {
 1825                 bestchan = ieee80211_find_channel(ic, bestchan->ic_freq,
 1826                         bestchan->ic_flags & ~IEEE80211_CHAN_TURBO);
 1827                 if (bestchan == NULL) {
 1828                         /* should never happen ?? */
 1829                         return 0;
 1830                 }
 1831         }
 1832         if (ss->ss_flags & (IEEE80211_SCAN_NOPICK | IEEE80211_SCAN_NOJOIN)) {
 1833                 /*
 1834                  * Manual/background scan, don't select+join the
 1835                  * bss, just return.  The scanning framework will
 1836                  * handle notification that this has completed.
 1837                  */
 1838                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1839                 return 1;
 1840         }
 1841         chan = ieee80211_ht_adjust_channel(ic, bestchan, vap->iv_flags_ht);
 1842         chan = ieee80211_vht_adjust_channel(ic, chan, vap->iv_flags_vht);
 1843         ieee80211_create_ibss(vap, chan);
 1844 
 1845         return 1;
 1846 }
 1847 
 1848 static const struct ieee80211_scanner ap_default = {
 1849         .scan_name              = "default",
 1850         .scan_attach            = sta_attach,
 1851         .scan_detach            = sta_detach,
 1852         .scan_start             = ap_start,
 1853         .scan_restart           = sta_restart,
 1854         .scan_cancel            = ap_cancel,
 1855         .scan_end               = ap_end,
 1856         .scan_flush             = sta_flush,
 1857         .scan_pickchan          = ap_pick_channel,
 1858         .scan_add               = sta_add,
 1859         .scan_age               = adhoc_age,
 1860         .scan_iterate           = sta_iterate,
 1861         .scan_assoc_success     = sta_assoc_success,
 1862         .scan_assoc_fail        = sta_assoc_fail,
 1863 };
 1864 IEEE80211_SCANNER_ALG(ap, IEEE80211_M_HOSTAP, ap_default);
 1865 
 1866 #ifdef IEEE80211_SUPPORT_MESH
 1867 /*
 1868  * Pick an mbss network to join or find a channel
 1869  * to use to start an mbss network.
 1870  */
 1871 static int
 1872 mesh_pick_bss(struct ieee80211_scan_state *ss, struct ieee80211vap *vap)
 1873 {
 1874         struct sta_table *st = ss->ss_priv;
 1875         struct ieee80211_mesh_state *ms = vap->iv_mesh;
 1876         struct sta_entry *selbs;
 1877         struct ieee80211_channel *chan;
 1878 
 1879         KASSERT(vap->iv_opmode == IEEE80211_M_MBSS,
 1880                 ("wrong opmode %u", vap->iv_opmode));
 1881 
 1882         if (st->st_newscan) {
 1883                 sta_update_notseen(st);
 1884                 st->st_newscan = 0;
 1885         }
 1886         if (ss->ss_flags & IEEE80211_SCAN_NOPICK) {
 1887                 /*
 1888                  * Manual/background scan, don't select+join the
 1889                  * bss, just return.  The scanning framework will
 1890                  * handle notification that this has completed.
 1891                  */
 1892                 ss->ss_flags &= ~IEEE80211_SCAN_NOPICK;
 1893                 return 1;
 1894         }
 1895         /*
 1896          * Automatic sequencing; look for a candidate and
 1897          * if found join the network.
 1898          */
 1899         /* NB: unlocked read should be ok */
 1900         if (TAILQ_FIRST(&st->st_entry) == NULL) {
 1901                 IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN,
 1902                         "%s: no scan candidate\n", __func__);
 1903                 if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1904                         return 0;
 1905 notfound:
 1906                 if (ms->ms_idlen != 0) {
 1907                         /*
 1908                          * No existing mbss network to join and we have
 1909                          * a meshid; start one up.  If no channel was
 1910                          * specified, try to select a channel.
 1911                          */
 1912                         if (vap->iv_des_chan == IEEE80211_CHAN_ANYC ||
 1913                             IEEE80211_IS_CHAN_RADAR(vap->iv_des_chan)) {
 1914                                 struct ieee80211com *ic = vap->iv_ic;
 1915 
 1916                                 /* XXX VHT */
 1917                                 chan = adhoc_pick_channel(ss, 0);
 1918                                 if (chan != NULL) {
 1919                                         chan = ieee80211_ht_adjust_channel(ic,
 1920                                             chan, vap->iv_flags_ht);
 1921                                         chan = ieee80211_vht_adjust_channel(ic,
 1922                                             chan, vap->iv_flags_vht);
 1923                                         }
 1924                         } else
 1925                                 chan = vap->iv_des_chan;
 1926                         if (chan != NULL) {
 1927                                 ieee80211_create_ibss(vap, chan);
 1928                                 return 1;
 1929                         }
 1930                 }
 1931                 /*
 1932                  * If nothing suitable was found decrement
 1933                  * the failure counts so entries will be
 1934                  * reconsidered the next time around.  We
 1935                  * really want to do this only for sta's
 1936                  * where we've previously had some success.
 1937                  */
 1938                 sta_dec_fails(st);
 1939                 st->st_newscan = 1;
 1940                 return 0;                       /* restart scan */
 1941         }
 1942         selbs = select_bss(ss, vap, IEEE80211_MSG_SCAN);
 1943         if (ss->ss_flags & IEEE80211_SCAN_NOJOIN)
 1944                 return (selbs != NULL);
 1945         if (selbs == NULL)
 1946                 goto notfound;
 1947         chan = selbs->base.se_chan;
 1948         if (selbs->se_flags & STA_DEMOTE11B)
 1949                 chan = demote11b(vap, chan);
 1950         if (!ieee80211_sta_join(vap, chan, &selbs->base))
 1951                 goto notfound;
 1952         return 1;                               /* terminate scan */
 1953 }
 1954 
 1955 static const struct ieee80211_scanner mesh_default = {
 1956         .scan_name              = "default",
 1957         .scan_attach            = sta_attach,
 1958         .scan_detach            = sta_detach,
 1959         .scan_start             = adhoc_start,
 1960         .scan_restart           = sta_restart,
 1961         .scan_cancel            = sta_cancel,
 1962         .scan_end               = mesh_pick_bss,
 1963         .scan_flush             = sta_flush,
 1964         .scan_pickchan          = adhoc_pick_channel,
 1965         .scan_add               = sta_add,
 1966         .scan_age               = adhoc_age,
 1967         .scan_iterate           = sta_iterate,
 1968         .scan_assoc_fail        = sta_assoc_fail,
 1969         .scan_assoc_success     = sta_assoc_success,
 1970 };
 1971 IEEE80211_SCANNER_ALG(mesh, IEEE80211_M_MBSS, mesh_default);
 1972 #endif /* IEEE80211_SUPPORT_MESH */

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