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device: Workaround for 0 oper class in Neighbor Report 

Some APs respond to Neighbor Report Requests with neighbor reports that
have a zero operating class value and a non-zero channel number.  This
does not mean that the channel is in the same band that the reporting
AP operates in.  Try to guess the band that the channel refers to out of
2.4 and 5GHz -- the bands supported by those APs.

wpa_supplicant also has this workaround in place.
This commit is contained in:
Andrew Zaborowski 2018-02-13 18:43:56 +01:00 committed by Denis Kenzior
parent e348c8e0ce
commit d42e848567
1 changed files with 24 additions and 4 deletions
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28
src/device.c
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@ -1184,11 +1184,31 @@ static uint32_t device_freq_from_neighbor_report(const uint8_t *country,
enum scan_band band;
uint32_t freq;
band = scan_oper_class_to_band(country, info->oper_class);
if (!band) {
l_debug("Ignored: unsupported oper class");
if (info->oper_class == 0) {
/*
* Some Cisco APs report all operating class values as 0
* in the Neighbor Report Responses. Work around this by
* using the most likely operating class for the channel
* number as the 2.4GHz and 5GHz bands happen to mostly
* use channels in two disjoint ranges.
*/
if (info->channel_num >= 1 && info->channel_num <= 14)
band = SCAN_BAND_2_4_GHZ;
else if (info->channel_num >= 36 && info->channel_num <= 169)
band = SCAN_BAND_5_GHZ;
else {
l_debug("Ignored: 0 oper class with an unusual "
"channel number");
return 0;
return 0;
}
} else {
band = scan_oper_class_to_band(country, info->oper_class);
if (!band) {
l_debug("Ignored: unsupported oper class");
return 0;
}
}
freq = scan_channel_to_freq(info->channel_num, band);