After the band is established we check the e4 table for the channel
that matches. The problem here is we will end up checking all the
operating classes, even those that are not within the band that was
determined. This could result in false positives and return a
channel that doesn't make sense.
The "UK" alpha2 code is not the official code for the United Kingdom
but is a "reserved" code for compatibility. The official alpha2 is
"GB" which is being added to the EU list. This fixes issues parsing
neighbor reports, for example:
src/station.c:parse_neighbor_report() Neighbor report received for xx:xx:xx:xx:xx:xx: ch 136 (oper class 3), MD not set
Failed to find band with country string 'GB 32' and oper class 3, trying fallback
src/station.c:station_add_neighbor_report_freqs() Ignored: unsupported oper class
Its been seen that some vendors incorrectly set the 3rd byte of the
country code which causes the band lookup to fail with the provided
operating class. This isn't compliant with the spec, but its been
seen out in the wild and it causes IWD to behave poorly, specifically
with roaming since it cannot parse neighbor reports. This then
requires IWD to do a full scan on each roam.
Instead of a hard rejection, IWD can instead attempt to determine
the band by ignoring that 3rd byte and only use the alpha2 string.
This makes IWD slightly less strict but at the advantage of not being
crippled when exposed to poor AP configurations.
This was overlooked in a prior patch and causes warnings to be
printed when the RSSI is too low to estimate an HE data rate or
due to incompatible local capabilities (e.g. MCS support).
Similar to the other estimations, return -ENETUNREACH if the IE
was valid but incompatible.
width must be initialized since it depends on best not being NULL. If
best passes the non-NULL check above, then width must be initialized
since both width and best are set at the same time.
The HT40+/- flags were reversed when checking against the 802.11
behavior flags.
HT40+ means the secondary channel is above (+) the primary channel
therefore corresponds to the PRIMARY_CHANNEL_LOWER behavior. And
the opposite for HT40-.
Reported-By: Alagu Sankar <alagusankar@gmail.com>
IWD's channel/frequency conversions use simple math to convert and
have very minimal checks to ensure the input is valid. This can
lead to some channels/frequencies being calculated which are not
in IWD's E-4 table, specifically in the 5GHz band.
This is especially noticable using mac80211_hwsim which includes
some obscure high 5ghz frequencies which are not part of the 802.11
spec.
To fix this calculate the frequency or channel then iterate E-4
operating classes to check that the value actually matches a class.
For AP mode its convenient for IWD to choose an appropriate
channel definition rather than require the user provide very
low level parameters such as channel width, center1 frequency
etc. For now only HT is supported as VHT/HE etc. require
additional secondary channel frequencies.
The HT API tries to find an operating class using 40Mhz which
complies with any hardware restrictions. If an operating class is
found that is supported/not restricted it is marked as 'best' until
a better one is found. In this case 'better' is a larger channel
width. Since this is HT only 20mhz and 40mhz widths are checked.
Currently the wiphy object keeps track of supported and disabled
frequencies as two separate scan_freq_set's. This is very expensive
and limiting since we have to add more sets in order to track
additional frequency flags (no-IR, no-HT, no-HE etc).
Instead we can refactor how frequencies are stored. They will now
be part of the band object and stored as a list of flag structures
where each index corresponds to a channel
Similar to the HT/VHT APIs, this estimates the data rate based on the
HE Capabilities element, in addition to our own capabilities. The
logic is much the same as HT/VHT. The major difference being that HE
uses several MCS tables depending on the channel width. Each width
MCS set is checked (if supported) and the highest estimated rate out
of all the MCS sets is used.
This is a general way of finding the best MCS/NSS values which will work
for HT, VHT, and HE by passing in the max MCS values for each value which
the MCS map could contain (0, 1, or 2).
This queue will hold iftype(s) specific data for HE capabilities. Since
the capabilities may differ per-iftype the data is stored as such. Iftypes
may share a configuration so the band_he_capabilities structure has a
mask for each iftype using that configuration.
This is a new band defined in the WiFi 6E (ax) amendment. A completely
new value is needed due to channel reuse between 2.4/5 and 6GHz.
util.c needed minimal updating to prevent compile errors which will
be fixed later to actually handle this band. WSC also needed a case
added for 6GHz but the spec does not outline any RF Band value for
6GHz so the 5GHz value will be returned in this case.
- Mostly problems with whitespace:
- Use of spaces instead of tabs
- Stray spaces before closing ')
- Missing spaces
- Missing 'void' from function declarations & definitions that
take no arguments.
- Wrong indentation level
This adds a utility to convert a chandef obtained from the kernel into a
3 byte OCI element format containing the operating class, primary
channel and secondary channel center frequency index.
This adds a utility that can convert an operating class + channel
combination to a frequency. Operating class is assumed to be a global
operating class from 802.11 Appendix E4.
This information can be found in Operating Channel Information (OCI) IEs,
as well as OWE Transition Mode IEs.
Under certain conditions, access points with very low signal could be
detected. This signal is too low to estimate a data rate and causes
this L_WARN to fire. Fix this by returning a -ENETUNREACH error code in
case the signal is too low for any of the supported rates.
Similarly to commit
27d302a0 ("band: Add a utility to estimate VHT rx data rate"), this
commit adds an RX data rate estimation utility for HT connections.
This function is meant to supercede a similar function in ie.c. The
current approach results in very optimistic data rate estimates since it
only takes into account the VHT/HT Capabilities IEs. It does not take
into account any local hardware limitations (such as no VHT/HT support),
limited RX MCS sets & number of spatial streams. It also does not take
into account that the AP might not be actually operating on higher
bandwidth channels.
This function is meant to address that by matching peer TX MCS sets with
the local hardware RX MCS set capability. It also takes into account
channel bandwidth capabilities of the local hardware, as well as whether
the AP is actually operating on a wider channel.
Move the band definition out of wiphy.c and into band.[ch]. This is
done to make certain utilities that depend on band information capable
of being tested from unit tests.
The band concept will most likely grow over time. For now, the only
user will be wiphy.c and unit tests, so the structures are kept public.
