focal (9) ieee80211_alloc_countryie.9freebsd.gz

NAME

     ieee80211_regdomain — 802.11 regulatory support

SYNOPSIS

     #include <net80211/ieee80211_var.h>
     #include <net80211/ieee80211_regdomain.h>

     int
     ieee80211_init_channels(struct ieee80211com *, const struct ieee80211_regdomain *, const uint8_t bands[]);

     void
     ieee80211_sort_channels(struct ieee80211_channel *, int nchans);

     struct ieee80211_appie *
     ieee80211_alloc_countryie(struct ieee80211com *);

DESCRIPTION

     The net80211 software layer provides a support framework for drivers that includes comprehensive regulatory
     support.  net80211 provides mechanisms that enforce regulatory policy by privileged user applications.

     Drivers define a device's capabilities and can intercept and control regulatory changes requested through
     net80211.  The initial regulatory state, including the channel list, must be filled in by the driver before
     calling ieee80211_ifattach().  The channel list should reflect the set of channels the device is calibrated
     for use on.  This list may also be requested later through the ic_getradiocaps method in the ieee80211com
     structure.  The ieee80211_init_channels() function is provided as a rudimentary fallback for drivers that
     do not (or cannot) fill in a proper channel list.  Default regulatory state is supplied such as the
     regulatory SKU, ISO country code, location (e.g. indoor, outdoor), and a set of frequency bands the device
     is capable of operating on.  net80211 populates the channel table in ic_channels with a default set of
     channels and capabilities.  Note this mechanism should be used with care as any mismatch between the
     channel list created and the device's capabilities can result in runtime errors (e.g. a request to operate
     on a channel the device does not support).  The SKU and country information are used for generating 802.11h
     protocol elements and related operation such as for 802.11d; mis-setup by a driver is not fatal, only
     potentially confusing.

     Devices that do not have a fixed/default regulatory state can set the regulatory SKU to SKU_DEBUG and
     country code to CTRY_DEFAULT and leave proper setup to user applications.  If default settings are known
     they can be installed and/or an event can be dispatched to user space using ieee80211_notify_country() so
     that devd(8) will do the appropriate setup work at system boot (or device insertion).

     The channel table is sorted to optimize lookups using the ieee80211_sort_channels() routine.  This should
     be done whenever the channel table contents are modified.

     The ieee80211_alloc_countryie() function allocates an information element as specified by 802.11h.  Because
     this is expensive to generate it is cached in ic_countryie and generated only when regulatory state
     changes.  Drivers that call ieee80211_alloc_countryie() directly should not help with this caching; doing
     so may confuse the net80211 layer.

DRIVER REGULATORY CONTROL

     Drivers can control regulatory change requests by overriding the ic_setregdomain method that checks change
     requests.  While drivers can reject any request that does not meet its requirements it is recommended that
     one be lenient in what is accepted and, whenever possible, instead of rejecting a request, alter it to be
     correct.  For example, if the transmit power cap for a channel is too high the driver can either reject the
     request or (better) reduce the cap to be compliant.  Requests that include unacceptable channels should
     cause the request to be rejected as otherwise a mismatch may be created between application state and the
     state managed by net80211.  The exact rules by which to operate are still being codified.

SEE ALSO

     regdomain(5), ifconfig(8), ieee80211(9)