802.11 helper functions

Functions
static void	net80211_add_channels (struct net80211_device *dev, int start, int len, int txpower)
	Add channels to 802.11 device.
static void	net80211_filter_hw_channels (struct net80211_device *dev)
	Filter 802.11 device channels for hardware capabilities.
static void	net80211_set_rtscts_rate (struct net80211_device *dev)
	Pick TX rate for RTS/CTS packets based on data rate.
static int	net80211_process_capab (struct net80211_device *dev, u16 capab)
	Update 802.11 device state to reflect received capabilities field.
static int	net80211_process_ie (struct net80211_device *dev, union ieee80211_ie *ie, void *ie_end)
	Update 802.11 device state to reflect received information elements.
static union ieee80211_ie *	net80211_marshal_request_info (struct net80211_device *dev, union ieee80211_ie *ie)
	Create information elements for outgoing probe or association packet.

Detailed Description

Function Documentation

net80211_add_channels()

void net80211_add_channels ( struct net80211_device * dev, int start, int len, int txpower )

static

Add channels to 802.11 device.

Parameters

dev	802.11 device
start	First channel number to add
len	Number of channels to add
txpower	TX power (dBm) to allow on added channels

To replace the current list of channels instead of adding to it, set the nr_channels field of the 802.11 device to 0 before calling this function.

Definition at line 918 of file net80211.c.

{
        int i, chan = start;
 
        for ( i = dev->nr_channels; len-- && i < NET80211_MAX_CHANNELS; i++ ) {
                dev->channels[i].channel_nr = chan;
                dev->channels[i].maxpower = txpower;
                dev->channels[i].hw_value = 0;
 
                if ( chan >= 1 && chan <= 14 ) {
                        dev->channels[i].band = NET80211_BAND_2GHZ;
                        if ( chan == 14 )
                                dev->channels[i].center_freq = 2484;
                        else
                                dev->channels[i].center_freq = 2407 + 5 * chan;
                        chan++;
                } else {
                        dev->channels[i].band = NET80211_BAND_5GHZ;
                        dev->channels[i].center_freq = 5000 + 5 * chan;
                        chan += 4;
                }
        }
 
        dev->nr_channels = i;
}

References net_device::dev, len, NET80211_BAND_2GHZ, NET80211_BAND_5GHZ, NET80211_MAX_CHANNELS, and start.

Referenced by net80211_prepare_probe(), and net80211_process_ie().

net80211_filter_hw_channels()

void net80211_filter_hw_channels ( struct net80211_device * dev )

static

Filter 802.11 device channels for hardware capabilities.

Parameters

dev	802.11 device

Hardware may support fewer channels than regulatory restrictions allow; this function filters out channels in dev->channels that are not supported by the hardware list in dev->hwinfo. It also copies over the net80211_channel::hw_value and limits maximum TX power appropriately.

Channels are matched based on center frequency, ignoring band and channel number.

If the driver specifies no supported channels, the effect will be as though all were supported.

Definition at line 962 of file net80211.c.

{
        int delta = 0, i = 0;
        int old_freq = dev->channels[dev->channel].center_freq;
        struct net80211_channel *chan, *hwchan;
 
        if ( ! dev->hw->nr_channels )
                return;
 
        dev->channel = 0;
        for ( chan = dev->channels; chan < dev->channels + dev->nr_channels;
              chan++, i++ ) {
                int ok = 0;
                for ( hwchan = dev->hw->channels;
                      hwchan < dev->hw->channels + dev->hw->nr_channels;
                      hwchan++ ) {
                        if ( hwchan->center_freq == chan->center_freq ) {
                                ok = 1;
                                break;
                        }
                }
 
                if ( ! ok )
                        delta++;
                else {
                        chan->hw_value = hwchan->hw_value;
                        if ( hwchan->maxpower != 0 &&
                             chan->maxpower > hwchan->maxpower )
                                chan->maxpower = hwchan->maxpower;
                        if ( old_freq == chan->center_freq )
                                dev->channel = i - delta;
                        if ( delta )
                                chan[-delta] = *chan;
                }
        }
 
        dev->nr_channels -= delta;
 
        if ( dev->channels[dev->channel].center_freq != old_freq )
                dev->op->config ( dev, NET80211_CFG_CHANNEL );
}

References net80211_channel::center_freq, net80211_device::channel, channels, net80211_device::channels, net80211_hw_info::channels, net80211_device_operations::config, net_device::dev, net80211_device::hw, net80211_channel::hw_value, net80211_channel::maxpower, NET80211_CFG_CHANNEL, net80211_device::nr_channels, net80211_hw_info::nr_channels, ok, and net80211_device::op.

Referenced by net80211_prepare_probe(), and net80211_process_ie().

net80211_set_rtscts_rate()

void net80211_set_rtscts_rate ( struct net80211_device * dev )

static

Pick TX rate for RTS/CTS packets based on data rate.

Parameters

dev	802.11 device

The RTS/CTS rate is the fastest TX rate marked as "basic" that is not faster than the data rate.

Definition at line 1968 of file net80211.c.

{
        u16 datarate = dev->rates[dev->rate];
        u16 rtsrate = 0;
        int rts_idx = -1;
        int i;
 
        for ( i = 0; i < dev->nr_rates; i++ ) {
                u16 rate = dev->rates[i];
 
                if ( ! ( dev->basic_rates & ( 1 << i ) ) || rate > datarate )
                        continue;
 
                if ( rate > rtsrate ) {
                        rtsrate = rate;
                        rts_idx = i;
                }
        }
 
        /* If this is in initialization, we might not have any basic
           rates; just use the first data rate in that case. */
        if ( rts_idx < 0 )
                rts_idx = 0;
 
        dev->rtscts_rate = rts_idx;
}

References net80211_device::basic_rates, net80211_device::nr_rates, net80211_device::rate, net80211_device::rates, net80211_device::rtscts_rate, and u16.

Referenced by net80211_process_ie(), and net80211_set_rate_idx().

net80211_process_capab()

int net80211_process_capab ( struct net80211_device * dev, u16 capab )

static

Update 802.11 device state to reflect received capabilities field.

Parameters

dev	802.11 device
capab	Capabilities field in beacon, probe, or association frame

Return values

rc	Return status code

Definition at line 1011 of file net80211.c.

{
        u16 old_phy = dev->phy_flags;
 
        if ( ( capab & ( IEEE80211_CAPAB_MANAGED | IEEE80211_CAPAB_ADHOC ) ) !=
             IEEE80211_CAPAB_MANAGED ) {
                DBGC ( dev, "802.11 %p cannot handle IBSS network\n", dev );
                return -ENOSYS;
        }
 
        dev->phy_flags &= ~( NET80211_PHY_USE_SHORT_PREAMBLE |
                             NET80211_PHY_USE_SHORT_SLOT );
 
        if ( capab & IEEE80211_CAPAB_SHORT_PMBL )
                dev->phy_flags |= NET80211_PHY_USE_SHORT_PREAMBLE;
 
        if ( capab & IEEE80211_CAPAB_SHORT_SLOT )
                dev->phy_flags |= NET80211_PHY_USE_SHORT_SLOT;
 
        if ( old_phy != dev->phy_flags )
                dev->op->config ( dev, NET80211_CFG_PHY_PARAMS );
 
        return 0;
}

References net80211_device_operations::config, DBGC, ENOSYS, IEEE80211_CAPAB_ADHOC, IEEE80211_CAPAB_MANAGED, IEEE80211_CAPAB_SHORT_PMBL, IEEE80211_CAPAB_SHORT_SLOT, NET80211_CFG_PHY_PARAMS, NET80211_PHY_USE_SHORT_PREAMBLE, NET80211_PHY_USE_SHORT_SLOT, net80211_device::op, net80211_device::phy_flags, and u16.

Referenced by net80211_handle_assoc_reply(), and net80211_prepare_assoc().

net80211_process_ie()

int net80211_process_ie ( struct net80211_device * dev, union ieee80211_ie * ie, void * ie_end )

static

Update 802.11 device state to reflect received information elements.

Parameters

dev	802.11 device
ie	Pointer to first information element
ie_end	Pointer to tail of packet I/O buffer

Return values

rc	Return status code

Definition at line 1045 of file net80211.c.

{
        u16 old_rate = dev->rates[dev->rate];
        u16 old_phy = dev->phy_flags;
        int have_rates = 0, i;
        int ds_channel = 0;
        int changed = 0;
        int band = dev->channels[dev->channel].band;
 
        if ( ! ieee80211_ie_bound ( ie, ie_end ) )
                return 0;
 
        for ( ; ie; ie = ieee80211_next_ie ( ie, ie_end ) ) {
                switch ( ie->id ) {
                case IEEE80211_IE_SSID:
                        if ( ie->len <= 32 ) {
                                memcpy ( dev->essid, ie->ssid, ie->len );
                                dev->essid[ie->len] = 0;
                        }
                        break;
 
                case IEEE80211_IE_RATES:
                case IEEE80211_IE_EXT_RATES:
                        if ( ! have_rates ) {
                                dev->nr_rates = 0;
                                dev->basic_rates = 0;
                                have_rates = 1;
                        }
                        for ( i = 0; i < ie->len &&
                              dev->nr_rates < NET80211_MAX_RATES; i++ ) {
                                u8 rid = ie->rates[i];
                                u16 rate = ( rid & 0x7f ) * 5;
 
                                if ( rid & 0x80 )
                                        dev->basic_rates |=
                                                ( 1 << dev->nr_rates );
 
                                dev->rates[dev->nr_rates++] = rate;
                        }
 
                        break;
 
                case IEEE80211_IE_DS_PARAM:
                        if ( dev->channel < dev->nr_channels && ds_channel ==
                             dev->channels[dev->channel].channel_nr )
                                break;
                        ds_channel = ie->ds_param.current_channel;
                        net80211_change_channel ( dev, ds_channel );
                        break;
 
                case IEEE80211_IE_COUNTRY:
                        dev->nr_channels = 0;
 
                        DBGC ( dev, "802.11 %p setting country regulations "
                               "for %c%c\n", dev, ie->country.name[0],
                               ie->country.name[1] );
                        for ( i = 0; i < ( ie->len - 3 ) / 3; i++ ) {
                                union ieee80211_ie_country_triplet *t =
                                        &ie->country.triplet[i];
                                if ( t->first > 200 ) {
                                        DBGC ( dev, "802.11 %p ignoring regulatory "
                                               "extension information\n", dev );
                                } else {
                                        net80211_add_channels ( dev,
                                                        t->band.first_channel,
                                                        t->band.nr_channels,
                                                        t->band.max_txpower );
                                }
                        }
                        net80211_filter_hw_channels ( dev );
                        break;
 
                case IEEE80211_IE_ERP_INFO:
                        dev->phy_flags &= ~( NET80211_PHY_USE_PROTECTION |
                                             NET80211_PHY_USE_SHORT_PREAMBLE );
                        if ( ie->erp_info & IEEE80211_ERP_USE_PROTECTION )
                                dev->phy_flags |= NET80211_PHY_USE_PROTECTION;
                        if ( ! ( ie->erp_info & IEEE80211_ERP_BARKER_LONG ) )
                                dev->phy_flags |= NET80211_PHY_USE_SHORT_PREAMBLE;
                        break;
                }
        }
 
        if ( have_rates ) {
                /* Allow only those rates that are also supported by
                   the hardware. */
                int delta = 0, j;
 
                dev->rate = 0;
                for ( i = 0; i < dev->nr_rates; i++ ) {
                        int ok = 0;
                        for ( j = 0; j < dev->hw->nr_rates[band]; j++ ) {
                                if ( dev->hw->rates[band][j] == dev->rates[i] ){
                                        ok = 1;
                                        break;
                                }
                        }
 
                        if ( ! ok )
                                delta++;
                        else {
                                dev->rates[i - delta] = dev->rates[i];
                                if ( old_rate == dev->rates[i] )
                                        dev->rate = i - delta;
                        }
                }
 
                dev->nr_rates -= delta;
 
                /* Sort available rates - sorted subclumps tend to already
                   exist, so insertion sort works well. */
                for ( i = 1; i < dev->nr_rates; i++ ) {
                        u16 rate = dev->rates[i];
                        u32 tmp, br, mask;
 
                        for ( j = i - 1; j >= 0 && dev->rates[j] >= rate; j-- )
                                dev->rates[j + 1] = dev->rates[j];
                        dev->rates[j + 1] = rate;
 
                        /* Adjust basic_rates to match by rotating the
                           bits from bit j+1 to bit i left one position. */
                        mask = ( ( 1 << i ) - 1 ) & ~( ( 1 << ( j + 1 ) ) - 1 );
                        br = dev->basic_rates;
                        tmp = br & ( 1 << i );
                        br = ( br & ~( mask | tmp ) ) | ( ( br & mask ) << 1 );
                        br |= ( tmp >> ( i - j - 1 ) );
                        dev->basic_rates = br;
                }
 
                net80211_set_rtscts_rate ( dev );
 
                if ( dev->rates[dev->rate] != old_rate )
                        changed |= NET80211_CFG_RATE;
        }
 
        if ( dev->hw->flags & NET80211_HW_NO_SHORT_PREAMBLE )
                dev->phy_flags &= ~NET80211_PHY_USE_SHORT_PREAMBLE;
        if ( dev->hw->flags & NET80211_HW_NO_SHORT_SLOT )
                dev->phy_flags &= ~NET80211_PHY_USE_SHORT_SLOT;
 
        if ( old_phy != dev->phy_flags )
                changed |= NET80211_CFG_PHY_PARAMS;
 
        if ( changed )
                dev->op->config ( dev, changed );
 
        return 0;
}

References ieee80211_ie_country_triplet::band, net80211_channel::band, net80211_device::basic_rates, net80211_device::channel, net80211_channel::channel_nr, net80211_device::channels, net80211_device_operations::config, ieee80211_ie::country, ieee80211_ie_ds_param::current_channel, DBGC, ieee80211_ie::ds_param, ieee80211_ie::erp_info, net80211_device::essid, ieee80211_ie_country_triplet::first, ieee80211_ie_country_band_triplet::first_channel, net80211_hw_info::flags, net80211_device::hw, ieee80211_ie::id, IEEE80211_ERP_BARKER_LONG, IEEE80211_ERP_USE_PROTECTION, ieee80211_ie_bound(), IEEE80211_IE_COUNTRY, IEEE80211_IE_DS_PARAM, IEEE80211_IE_ERP_INFO, IEEE80211_IE_EXT_RATES, IEEE80211_IE_RATES, IEEE80211_IE_SSID, ieee80211_next_ie(), ieee80211_ie::len, ieee80211_ie_country_band_triplet::max_txpower, memcpy(), ieee80211_ie_country::name, net80211_add_channels(), NET80211_CFG_PHY_PARAMS, NET80211_CFG_RATE, net80211_change_channel(), net80211_filter_hw_channels(), NET80211_MAX_RATES, NET80211_PHY_USE_PROTECTION, NET80211_PHY_USE_SHORT_PREAMBLE, NET80211_PHY_USE_SHORT_SLOT, net80211_set_rtscts_rate(), ieee80211_ie_country_band_triplet::nr_channels, net80211_device::nr_channels, net80211_device::nr_rates, net80211_hw_info::nr_rates, ok, net80211_device::op, net80211_device::phy_flags, net80211_device::rate, ieee80211_ie::rates, net80211_device::rates, net80211_hw_info::rates, ieee80211_ie::ssid, tmp, ieee80211_ie_country::triplet, u16, u32, and u8.

Referenced by net80211_handle_assoc_reply(), and net80211_prepare_assoc().

net80211_marshal_request_info()

union ieee80211_ie * net80211_marshal_request_info ( struct net80211_device * dev, union ieee80211_ie * ie )

static

Create information elements for outgoing probe or association packet.

Parameters

dev	802.11 device
ie	Pointer to start of information element area

Return values

next_ie

Pointer to first byte after added information elements

Definition at line 1203 of file net80211.c.

{
        int i;
 
        ie->id = IEEE80211_IE_SSID;
        ie->len = strlen ( dev->essid );
        memcpy ( ie->ssid, dev->essid, ie->len );
 
        ie = ieee80211_next_ie ( ie, NULL );
 
        ie->id = IEEE80211_IE_RATES;
        ie->len = dev->nr_rates;
        if ( ie->len > 8 )
                ie->len = 8;
 
        for ( i = 0; i < ie->len; i++ ) {
                ie->rates[i] = dev->rates[i] / 5;
                if ( dev->basic_rates & ( 1 << i ) )
                        ie->rates[i] |= 0x80;
        }
 
        ie = ieee80211_next_ie ( ie, NULL );
 
        if ( dev->rsn_ie && dev->rsn_ie->id == IEEE80211_IE_RSN ) {
                memcpy ( ie, dev->rsn_ie, dev->rsn_ie->len + 2 );
                ie = ieee80211_next_ie ( ie, NULL );
        }
 
        if ( dev->nr_rates > 8 ) {
                /* 802.11 requires we use an Extended Basic Rates IE
                   for the rates beyond the eighth. */
 
                ie->id = IEEE80211_IE_EXT_RATES;
                ie->len = dev->nr_rates - 8;
 
                for ( ; i < dev->nr_rates; i++ ) {
                        ie->rates[i - 8] = dev->rates[i] / 5;
                        if ( dev->basic_rates & ( 1 << i ) )
                                ie->rates[i - 8] |= 0x80;
                }
 
                ie = ieee80211_next_ie ( ie, NULL );
        }
 
        if ( dev->rsn_ie && dev->rsn_ie->id == IEEE80211_IE_VENDOR ) {
                memcpy ( ie, dev->rsn_ie, dev->rsn_ie->len + 2 );
                ie = ieee80211_next_ie ( ie, NULL );
        }
 
        return ie;
}

References net80211_device::basic_rates, net80211_device::essid, ieee80211_ie::id, IEEE80211_IE_EXT_RATES, IEEE80211_IE_RATES, IEEE80211_IE_RSN, IEEE80211_IE_SSID, IEEE80211_IE_VENDOR, ieee80211_next_ie(), ieee80211_ie::len, memcpy(), net80211_device::nr_rates, NULL, ieee80211_ie::rates, net80211_device::rates, net80211_device::rsn_ie, ieee80211_ie::ssid, and strlen().

Referenced by net80211_probe_start(), and net80211_send_assoc().