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

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    1 /*-
    2  * Copyright (c) 2005-2009 Sam Leffler, Errno Consulting
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   24  *
   25  * $FreeBSD: stable/9/sys/net80211/ieee80211_scan.h 195618 2009-07-11 15:02:45Z rpaulo $
   26  */
   27 #ifndef _NET80211_IEEE80211_SCAN_H_
   28 #define _NET80211_IEEE80211_SCAN_H_
   29 
   30 /*
   31  * 802.11 scanning support.
   32  *
   33  * Scanning is the procedure by which a station locates a bss to join
   34  * (infrastructure/ibss mode), or a channel to use (when operating as
   35  * an ap or ibss master).  Scans are either "active" or "passive".  An
   36  * active scan causes one or more probe request frames to be sent on
   37  * visiting each channel.  A passive request causes each channel in the
   38  * scan set to be visited but no frames to be transmitted; the station
   39  * only listens for traffic.  Note that active scanning may still need
   40  * to listen for traffic before sending probe request frames depending
   41  * on regulatory constraints; the 802.11 layer handles this by generating
   42  * a callback when scanning on a ``passive channel'' when the
   43  * IEEE80211_FEXT_PROBECHAN flag is set.
   44  *
   45  * A scan operation involves constructing a set of channels to inspect
   46  * (the scan set), visiting each channel and collecting information
   47  * (e.g. what bss are present), and then analyzing the results to make
   48  * decisions like which bss to join.  This process needs to be as fast
   49  * as possible so we do things like intelligently construct scan sets
   50  * and dwell on a channel only as long as necessary.  The scan code also
   51  * maintains a cache of recent scan results and uses it to bypass scanning
   52  * whenever possible.  The scan cache is also used to enable roaming
   53  * between access points when operating in infrastructure mode.
   54  *
   55  * Scanning is handled with pluggable modules that implement "policy"
   56  * per-operating mode.  The core scanning support provides an
   57  * instrastructure to support these modules and exports a common api
   58  * to the rest of the 802.11 layer.  Policy modules decide what
   59  * channels to visit, what state to record to make decisions (e.g. ap
   60  * mode scanning for auto channel selection keeps significantly less
   61  * state than sta mode scanning for an ap to associate to), and selects
   62  * the final station/channel to return as the result of a scan.
   63  *
   64  * Scanning is done synchronously when initially bringing a vap to an
   65  * operational state and optionally in the background to maintain the
   66  * scan cache for doing roaming and rogue ap monitoring.  Scanning is
   67  * not tied to the 802.11 state machine that governs vaps though there
   68  * is linkage to the IEEE80211_SCAN state.  Only one vap at a time may
   69  * be scanning; this scheduling policy is handled in ieee80211_new_state
   70  * and is invisible to the scanning code.
   71 */
   72 #define IEEE80211_SCAN_MAX      IEEE80211_CHAN_MAX
   73 
   74 struct ieee80211_scanner;                       /* scan policy state */
   75 
   76 struct ieee80211_scan_ssid {
   77         int      len;                           /* length in bytes */
   78         uint8_t ssid[IEEE80211_NWID_LEN];       /* ssid contents */
   79 };
   80 #define IEEE80211_SCAN_MAX_SSID 1               /* max # ssid's to probe */
   81 
   82 /*
   83  * Scan state visible to the 802.11 layer.  Scan parameters and
   84  * results are stored in this data structure.  The ieee80211_scan_state
   85  * structure is extended with space that is maintained private to
   86  * the core scanning support.  We allocate one instance and link it
   87  * to the ieee80211com structure; then share it between all associated
   88  * vaps.  We could allocate multiple of these, e.g. to hold multiple
   89  * scan results, but this is sufficient for current needs.
   90  */
   91 struct ieee80211_scan_state {
   92         struct ieee80211vap *ss_vap;
   93         struct ieee80211com *ss_ic;
   94         const struct ieee80211_scanner *ss_ops; /* policy hookup, see below */
   95         void            *ss_priv;               /* scanner private state */
   96         uint16_t        ss_flags;
   97 #define IEEE80211_SCAN_NOPICK   0x0001          /* scan only, no selection */
   98 #define IEEE80211_SCAN_ACTIVE   0x0002          /* active scan (probe req) */
   99 #define IEEE80211_SCAN_PICK1ST  0x0004          /* ``hey sailor'' mode */
  100 #define IEEE80211_SCAN_BGSCAN   0x0008          /* bg scan, exit ps at end */
  101 #define IEEE80211_SCAN_ONCE     0x0010          /* do one complete pass */
  102 #define IEEE80211_SCAN_NOBCAST  0x0020          /* no broadcast probe req */
  103 #define IEEE80211_SCAN_NOJOIN   0x0040          /* no auto-sequencing */
  104 #define IEEE80211_SCAN_GOTPICK  0x1000          /* got candidate, can stop */
  105         uint8_t         ss_nssid;               /* # ssid's to probe/match */
  106         struct ieee80211_scan_ssid ss_ssid[IEEE80211_SCAN_MAX_SSID];
  107                                                 /* ssid's to probe/match */
  108                                                 /* ordered channel set */
  109         struct ieee80211_channel *ss_chans[IEEE80211_SCAN_MAX];
  110         uint16_t        ss_next;                /* ix of next chan to scan */
  111         uint16_t        ss_last;                /* ix+1 of last chan to scan */
  112         unsigned long   ss_mindwell;            /* min dwell on channel */
  113         unsigned long   ss_maxdwell;            /* max dwell on channel */
  114 };
  115 
  116 /*
  117  * The upper 16 bits of the flags word is used to communicate
  118  * information to the scanning code that is NOT recorded in
  119  * ss_flags.  It might be better to split this stuff out into
  120  * a separate variable to avoid confusion.
  121  */
  122 #define IEEE80211_SCAN_FLUSH    0x00010000      /* flush candidate table */
  123 #define IEEE80211_SCAN_NOSSID   0x80000000      /* don't update ssid list */
  124 
  125 struct ieee80211com;
  126 void    ieee80211_scan_attach(struct ieee80211com *);
  127 void    ieee80211_scan_detach(struct ieee80211com *);
  128 void    ieee80211_scan_vattach(struct ieee80211vap *);
  129 void    ieee80211_scan_vdetach(struct ieee80211vap *);
  130 
  131 void    ieee80211_scan_dump_channels(const struct ieee80211_scan_state *);
  132 
  133 #define IEEE80211_SCAN_FOREVER  0x7fffffff
  134 int     ieee80211_start_scan(struct ieee80211vap *, int flags,
  135                 u_int duration, u_int mindwell, u_int maxdwell,
  136                 u_int nssid, const struct ieee80211_scan_ssid ssids[]);
  137 int     ieee80211_check_scan(struct ieee80211vap *, int flags,
  138                 u_int duration, u_int mindwell, u_int maxdwell,
  139                 u_int nssid, const struct ieee80211_scan_ssid ssids[]);
  140 int     ieee80211_check_scan_current(struct ieee80211vap *);
  141 int     ieee80211_bg_scan(struct ieee80211vap *, int);
  142 void    ieee80211_cancel_scan(struct ieee80211vap *);
  143 void    ieee80211_cancel_anyscan(struct ieee80211vap *);
  144 void    ieee80211_scan_next(struct ieee80211vap *);
  145 void    ieee80211_scan_done(struct ieee80211vap *);
  146 void    ieee80211_probe_curchan(struct ieee80211vap *, int);
  147 struct ieee80211_channel *ieee80211_scan_pickchannel(struct ieee80211com *, int);
  148 
  149 struct ieee80211_scanparams;
  150 void    ieee80211_add_scan(struct ieee80211vap *,
  151                 const struct ieee80211_scanparams *,
  152                 const struct ieee80211_frame *,
  153                 int subtype, int rssi, int noise);
  154 void    ieee80211_scan_timeout(struct ieee80211com *);
  155 
  156 void    ieee80211_scan_assoc_success(struct ieee80211vap *,
  157                 const uint8_t mac[IEEE80211_ADDR_LEN]);
  158 enum {
  159         IEEE80211_SCAN_FAIL_TIMEOUT     = 1,    /* no response to mgmt frame */
  160         IEEE80211_SCAN_FAIL_STATUS      = 2     /* negative response to " " */
  161 };
  162 void    ieee80211_scan_assoc_fail(struct ieee80211vap *,
  163                 const uint8_t mac[IEEE80211_ADDR_LEN], int reason);
  164 void    ieee80211_scan_flush(struct ieee80211vap *);
  165 
  166 struct ieee80211_scan_entry;
  167 typedef void ieee80211_scan_iter_func(void *,
  168                 const struct ieee80211_scan_entry *);
  169 void    ieee80211_scan_iterate(struct ieee80211vap *,
  170                 ieee80211_scan_iter_func, void *);
  171 enum {
  172         IEEE80211_BPARSE_BADIELEN       = 0x01, /* ie len past end of frame */
  173         IEEE80211_BPARSE_RATES_INVALID  = 0x02, /* invalid RATES ie */
  174         IEEE80211_BPARSE_XRATES_INVALID = 0x04, /* invalid XRATES ie */
  175         IEEE80211_BPARSE_SSID_INVALID   = 0x08, /* invalid SSID ie */
  176         IEEE80211_BPARSE_CHAN_INVALID   = 0x10, /* invalid FH/DSPARMS chan */
  177         IEEE80211_BPARSE_OFFCHAN        = 0x20, /* DSPARMS chan != curchan */
  178         IEEE80211_BPARSE_BINTVAL_INVALID= 0x40, /* invalid beacon interval */
  179         IEEE80211_BPARSE_CSA_INVALID    = 0x80, /* invalid CSA ie */
  180 };
  181 
  182 /*
  183  * Parameters supplied when adding/updating an entry in a
  184  * scan cache.  Pointer variables should be set to NULL
  185  * if no data is available.  Pointer references can be to
  186  * local data; any information that is saved will be copied.
  187  * All multi-byte values must be in host byte order.
  188  */
  189 struct ieee80211_scanparams {
  190         uint8_t         status;         /* bitmask of IEEE80211_BPARSE_* */
  191         uint8_t         chan;           /* channel # from FH/DSPARMS */
  192         uint8_t         bchan;          /* curchan's channel # */
  193         uint8_t         fhindex;
  194         uint16_t        fhdwell;        /* FHSS dwell interval */
  195         uint16_t        capinfo;        /* 802.11 capabilities */
  196         uint16_t        erp;            /* NB: 0x100 indicates ie present */
  197         uint16_t        bintval;
  198         uint8_t         timoff;
  199         uint8_t         *ies;           /* all captured ies */
  200         size_t          ies_len;        /* length of all captured ies */
  201         uint8_t         *tim;
  202         uint8_t         *tstamp;
  203         uint8_t         *country;
  204         uint8_t         *ssid;
  205         uint8_t         *rates;
  206         uint8_t         *xrates;
  207         uint8_t         *doth;
  208         uint8_t         *wpa;
  209         uint8_t         *rsn;
  210         uint8_t         *wme;
  211         uint8_t         *htcap;
  212         uint8_t         *htinfo;
  213         uint8_t         *ath;
  214         uint8_t         *tdma;
  215         uint8_t         *csa;
  216         uint8_t         *meshid;
  217         uint8_t         *meshconf;
  218         uint8_t         *spare[3];
  219 };
  220 
  221 /*
  222  * Scan cache entry format used when exporting data from a policy
  223  * module; this data may be represented some other way internally.
  224  */
  225 struct ieee80211_scan_entry {
  226         uint8_t         se_macaddr[IEEE80211_ADDR_LEN];
  227         uint8_t         se_bssid[IEEE80211_ADDR_LEN];
  228         /* XXX can point inside se_ies */
  229         uint8_t         se_ssid[2+IEEE80211_NWID_LEN];
  230         uint8_t         se_rates[2+IEEE80211_RATE_MAXSIZE];
  231         uint8_t         se_xrates[2+IEEE80211_RATE_MAXSIZE];
  232         union {
  233                 uint8_t         data[8];
  234                 u_int64_t       tsf;
  235         } se_tstamp;                    /* from last rcv'd beacon */
  236         uint16_t        se_intval;      /* beacon interval (host byte order) */
  237         uint16_t        se_capinfo;     /* capabilities (host byte order) */
  238         struct ieee80211_channel *se_chan;/* channel where sta found */
  239         uint16_t        se_timoff;      /* byte offset to TIM ie */
  240         uint16_t        se_fhdwell;     /* FH only (host byte order) */
  241         uint8_t         se_fhindex;     /* FH only */
  242         uint8_t         se_dtimperiod;  /* DTIM period */
  243         uint16_t        se_erp;         /* ERP from beacon/probe resp */
  244         int8_t          se_rssi;        /* avg'd recv ssi */
  245         int8_t          se_noise;       /* noise floor */
  246         uint8_t         se_cc[2];       /* captured country code */
  247         uint8_t         se_meshid[2+IEEE80211_MESHID_LEN];
  248         struct ieee80211_ies se_ies;    /* captured ie's */
  249         u_int           se_age;         /* age of entry (0 on create) */
  250 };
  251 MALLOC_DECLARE(M_80211_SCAN);
  252 
  253 /*
  254  * Template for an in-kernel scan policy module.
  255  * Modules register with the scanning code and are
  256  * typically loaded as needed.
  257  */
  258 struct ieee80211_scanner {
  259         const char *scan_name;          /* printable name */
  260         int     (*scan_attach)(struct ieee80211_scan_state *);
  261         int     (*scan_detach)(struct ieee80211_scan_state *);
  262         int     (*scan_start)(struct ieee80211_scan_state *,
  263                         struct ieee80211vap *);
  264         int     (*scan_restart)(struct ieee80211_scan_state *,
  265                         struct ieee80211vap *);
  266         int     (*scan_cancel)(struct ieee80211_scan_state *,
  267                         struct ieee80211vap *);
  268         int     (*scan_end)(struct ieee80211_scan_state *,
  269                         struct ieee80211vap *);
  270         int     (*scan_flush)(struct ieee80211_scan_state *);
  271         struct ieee80211_channel *(*scan_pickchan)(
  272                         struct ieee80211_scan_state *, int);
  273         /* add an entry to the cache */
  274         int     (*scan_add)(struct ieee80211_scan_state *,
  275                         const struct ieee80211_scanparams *,
  276                         const struct ieee80211_frame *,
  277                         int subtype, int rssi, int noise);
  278         /* age and/or purge entries in the cache */
  279         void    (*scan_age)(struct ieee80211_scan_state *);
  280         /* note that association failed for an entry */
  281         void    (*scan_assoc_fail)(struct ieee80211_scan_state *,
  282                         const uint8_t macaddr[IEEE80211_ADDR_LEN],
  283                         int reason);
  284         /* note that association succeed for an entry */
  285         void    (*scan_assoc_success)(struct ieee80211_scan_state *,
  286                         const uint8_t macaddr[IEEE80211_ADDR_LEN]);
  287         /* iterate over entries in the scan cache */
  288         void    (*scan_iterate)(struct ieee80211_scan_state *,
  289                         ieee80211_scan_iter_func *, void *);
  290         void    (*scan_spare0)(void);
  291         void    (*scan_spare1)(void);
  292         void    (*scan_spare2)(void);
  293         void    (*scan_spare4)(void);
  294 };
  295 void    ieee80211_scanner_register(enum ieee80211_opmode,
  296                 const struct ieee80211_scanner *);
  297 void    ieee80211_scanner_unregister(enum ieee80211_opmode,
  298                 const struct ieee80211_scanner *);
  299 void    ieee80211_scanner_unregister_all(const struct ieee80211_scanner *);
  300 const struct ieee80211_scanner *ieee80211_scanner_get(enum ieee80211_opmode);
  301 #endif /* _NET80211_IEEE80211_SCAN_H_ */

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