applications/create_ap
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Get the current channel with 'iw dev wlanN link'

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With older versions of iw we can not get the channel that we
are currently associated with. So we cannot detect if we have
to fallback to that channel. Because of this, hostapd exits
with the following errors:

    Failed to set beacon parameters
    Interface initialization failed
    ap0: interface state UNINITIALIZED->DISABLED
    ap0: AP-DISABLED
    ap0: Unable to setup interface.
    hostapd_free_hapd_data: Interface ap0 wasn't started

A solution is to get the frequency from 'iw dev wlanN link' and
convert it to the channel number.

Fix #50
This commit is contained in:
oblique 2014-10-01 12:04:57 +03:00
parent bec1513a07
commit 3db732ed50
1 changed files with 26 additions and 5 deletions
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31
create_ap
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@ -162,6 +162,24 @@ can_transmit_to_channel() {
fi
}
# taken from iw/util.c
ieee80211_frequency_to_channel() {
FREQ=$1
if [[ $FREQ -eq 2484 ]]; then
echo 14
elif [[ $FREQ -lt 2484 ]]; then
echo $(( ($FREQ - 2407) / 5 ))
elif [[ $FREQ -ge 4910 && $FREQ -le 4980 ]]; then
echo $(( ($FREQ - 4000) / 5 ))
elif [[ $FREQ -le 45000 ]]; then
echo $(( ($FREQ - 5000) / 5 ))
elif [[ $FREQ -ge 58320 && $FREQ -le 64800 ]]; then
echo $(( ($FREQ - 56160) / 2160 ))
else
echo 0
fi
}
is_wifi_connected() {
if [[ $USE_IWCONFIG -eq 0 ]]; then
iw dev "$1" link 2>&1 | grep -E '^Connected to' > /dev/null 2>&1 && return 0
@ -674,11 +692,14 @@ if [[ $NO_VIRT -eq 0 ]]; then
echo "DONE"
fi
WIFI_IFACE_CHANNEL=$(iw dev ${WIFI_IFACE} info | grep channel | awk '{print $2}')
if [[ -n $WIFI_IFACE_CHANNEL && $WIFI_IFACE_CHANNEL -ne $CHANNEL ]]; then
echo "hostapd will fail to use channel $CHANNEL because $WIFI_IFACE is already set to channel $WIFI_IFACE_CHANNEL, fallback to channel $WIFI_IFACE_CHANNEL."
CHANNEL=$WIFI_IFACE_CHANNEL
if is_wifi_connected ${WIFI_IFACE}; then
WIFI_IFACE_FREQ=$(iw dev ${WIFI_IFACE} link | grep -i freq | awk '{print $2}')
WIFI_IFACE_CHANNEL=$(ieee80211_frequency_to_channel ${WIFI_IFACE_FREQ})
echo "${WIFI_IFACE} is already set at channel ${WIFI_IFACE_CHANNEL} (${WIFI_IFACE_FREQ} MHz)"
if [[ $WIFI_IFACE_CHANNEL -ne $CHANNEL ]]; then
echo "We can not set to channel ${CHANNEL}, fallback to channel ${WIFI_IFACE_CHANNEL}"
CHANNEL=$WIFI_IFACE_CHANNEL
fi
fi
VIRTDIEMSG="Maybe your WiFi adapter does not fully support virtual interfaces.