771 lines
25 KiB
C
771 lines
25 KiB
C
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/*
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* ACS - Automatic Channel Selection module
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* Copyright (c) 2011, Atheros Communications
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* Copyright (c) 2013, Qualcomm Atheros, Inc.
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*
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* This software may be distributed under the terms of the BSD license.
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* See README for more details.
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*/
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#include "utils/includes.h"
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#include <math.h>
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#include "utils/common.h"
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#include "utils/list.h"
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#include "common/ieee802_11_defs.h"
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#include "drivers/driver.h"
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#include "hostapd.h"
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#include "ap_drv_ops.h"
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#include "ap_config.h"
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#include "hw_features.h"
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#include "acs.h"
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/*
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* Automatic Channel Selection
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* ===========================
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*
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* More info at
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* ------------
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* http://wireless.kernel.org/en/users/Documentation/acs
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*
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* How to use
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* ----------
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* - make sure you have CONFIG_ACS=y in hostapd's .config
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* - use channel=0 or channel=acs to enable ACS
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*
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* How does it work
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* ----------------
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* 1. passive scans are used to collect survey data
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* (it is assumed that scan trigger collection of survey data in driver)
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* 2. interference factor is calculated for each channel
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* 3. ideal channel is picked depending on channel width by using adjacent
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* channel interference factors
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*
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* Known limitations
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* -----------------
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* - Current implementation depends heavily on the amount of time willing to
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* spend gathering survey data during hostapd startup. Short traffic bursts
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* may be missed and a suboptimal channel may be picked.
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* - Ideal channel may end up overlapping a channel with 40 MHz intolerant BSS
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*
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* Todo / Ideas
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* ------------
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* - implement other interference computation methods
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* - BSS/RSSI based
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* - spectral scan based
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* (should be possibly to hook this up with current ACS scans)
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* - add wpa_supplicant support (for P2P)
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* - collect a histogram of interference over time allowing more educated
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* guess about an ideal channel (perhaps CSA could be used to migrate AP to a
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* new "better" channel while running)
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* - include neighboring BSS scan to avoid conflicts with 40 MHz intolerant BSSs
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* when choosing the ideal channel
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*
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* Survey interference factor implementation details
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* -------------------------------------------------
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* Generic interference_factor in struct hostapd_channel_data is used.
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*
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* The survey interference factor is defined as the ratio of the
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* observed busy time over the time we spent on the channel,
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* this value is then amplified by the observed noise floor on
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* the channel in comparison to the lowest noise floor observed
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* on the entire band.
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*
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* This corresponds to:
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* ---
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* (busy time - tx time) / (active time - tx time) * 2^(chan_nf + band_min_nf)
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* ---
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*
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* The coefficient of 2 reflects the way power in "far-field"
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* radiation decreases as the square of distance from the antenna [1].
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* What this does is it decreases the observed busy time ratio if the
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* noise observed was low but increases it if the noise was high,
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* proportionally to the way "far field" radiation changes over
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* distance.
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*
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* If channel busy time is not available the fallback is to use channel RX time.
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*
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* Since noise floor is in dBm it is necessary to convert it into Watts so that
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* combined channel interference (e.g., HT40, which uses two channels) can be
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* calculated easily.
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* ---
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* (busy time - tx time) / (active time - tx time) *
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* 2^(10^(chan_nf/10) + 10^(band_min_nf/10))
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* ---
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*
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* However to account for cases where busy/rx time is 0 (channel load is then
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* 0%) channel noise floor signal power is combined into the equation so a
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* channel with lower noise floor is preferred. The equation becomes:
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* ---
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* 10^(chan_nf/5) + (busy time - tx time) / (active time - tx time) *
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* 2^(10^(chan_nf/10) + 10^(band_min_nf/10))
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* ---
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*
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* All this "interference factor" is purely subjective and only time
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* will tell how usable this is. By using the minimum noise floor we
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* remove any possible issues due to card calibration. The computation
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* of the interference factor then is dependent on what the card itself
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* picks up as the minimum noise, not an actual real possible card
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* noise value.
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*
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* Total interference computation details
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* --------------------------------------
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* The above channel interference factor is calculated with no respect to
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* target operational bandwidth.
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*
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* To find an ideal channel the above data is combined by taking into account
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* the target operational bandwidth and selected band. E.g., on 2.4 GHz channels
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* overlap with 20 MHz bandwidth, but there is no overlap for 20 MHz bandwidth
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* on 5 GHz.
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*
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* Each valid and possible channel spec (i.e., channel + width) is taken and its
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* interference factor is computed by summing up interferences of each channel
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* it overlaps. The one with least total interference is picked up.
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*
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* Note: This implies base channel interference factor must be non-negative
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* allowing easy summing up.
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*
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* Example ACS analysis printout
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* -----------------------------
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*
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* ACS: Trying survey-based ACS
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* ACS: Survey analysis for channel 1 (2412 MHz)
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* ACS: 1: min_nf=-113 interference_factor=0.0802469 nf=-113 time=162 busy=0 rx=13
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* ACS: 2: min_nf=-113 interference_factor=0.0745342 nf=-113 time=161 busy=0 rx=12
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* ACS: 3: min_nf=-113 interference_factor=0.0679012 nf=-113 time=162 busy=0 rx=11
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* ACS: 4: min_nf=-113 interference_factor=0.0310559 nf=-113 time=161 busy=0 rx=5
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* ACS: 5: min_nf=-113 interference_factor=0.0248447 nf=-113 time=161 busy=0 rx=4
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* ACS: * interference factor average: 0.0557166
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* ACS: Survey analysis for channel 2 (2417 MHz)
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* ACS: 1: min_nf=-113 interference_factor=0.0185185 nf=-113 time=162 busy=0 rx=3
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* ACS: 2: min_nf=-113 interference_factor=0.0246914 nf=-113 time=162 busy=0 rx=4
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* ACS: 3: min_nf=-113 interference_factor=0.037037 nf=-113 time=162 busy=0 rx=6
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* ACS: 4: min_nf=-113 interference_factor=0.149068 nf=-113 time=161 busy=0 rx=24
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* ACS: 5: min_nf=-113 interference_factor=0.0248447 nf=-113 time=161 busy=0 rx=4
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* ACS: * interference factor average: 0.050832
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* ACS: Survey analysis for channel 3 (2422 MHz)
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* ACS: 1: min_nf=-113 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
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* ACS: 2: min_nf=-113 interference_factor=0.0185185 nf=-113 time=162 busy=0 rx=3
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* ACS: 3: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
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* ACS: 4: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
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* ACS: 5: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
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* ACS: * interference factor average: 0.0148838
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* ACS: Survey analysis for channel 4 (2427 MHz)
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* ACS: 1: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
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* ACS: 2: min_nf=-114 interference_factor=0.0555556 nf=-114 time=162 busy=0 rx=9
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* ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
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* ACS: 4: min_nf=-114 interference_factor=0.0186335 nf=-114 time=161 busy=0 rx=3
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* ACS: 5: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
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* ACS: * interference factor average: 0.0160801
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* ACS: Survey analysis for channel 5 (2432 MHz)
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* ACS: 1: min_nf=-114 interference_factor=0.409938 nf=-113 time=161 busy=0 rx=66
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* ACS: 2: min_nf=-114 interference_factor=0.0432099 nf=-113 time=162 busy=0 rx=7
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* ACS: 3: min_nf=-114 interference_factor=0.0124224 nf=-113 time=161 busy=0 rx=2
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* ACS: 4: min_nf=-114 interference_factor=0.677019 nf=-113 time=161 busy=0 rx=109
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* ACS: 5: min_nf=-114 interference_factor=0.0186335 nf=-114 time=161 busy=0 rx=3
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* ACS: * interference factor average: 0.232244
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* ACS: Survey analysis for channel 6 (2437 MHz)
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* ACS: 1: min_nf=-113 interference_factor=0.552795 nf=-113 time=161 busy=0 rx=89
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* ACS: 2: min_nf=-113 interference_factor=0.0807453 nf=-112 time=161 busy=0 rx=13
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* ACS: 3: min_nf=-113 interference_factor=0.0310559 nf=-113 time=161 busy=0 rx=5
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* ACS: 4: min_nf=-113 interference_factor=0.434783 nf=-112 time=161 busy=0 rx=70
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* ACS: 5: min_nf=-113 interference_factor=0.0621118 nf=-113 time=161 busy=0 rx=10
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* ACS: * interference factor average: 0.232298
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* ACS: Survey analysis for channel 7 (2442 MHz)
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* ACS: 1: min_nf=-113 interference_factor=0.440994 nf=-112 time=161 busy=0 rx=71
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* ACS: 2: min_nf=-113 interference_factor=0.385093 nf=-113 time=161 busy=0 rx=62
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* ACS: 3: min_nf=-113 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
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* ACS: 4: min_nf=-113 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
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* ACS: 5: min_nf=-113 interference_factor=0.0745342 nf=-113 time=161 busy=0 rx=12
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* ACS: * interference factor average: 0.195031
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* ACS: Survey analysis for channel 8 (2447 MHz)
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* ACS: 1: min_nf=-114 interference_factor=0.0496894 nf=-112 time=161 busy=0 rx=8
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* ACS: 2: min_nf=-114 interference_factor=0.0496894 nf=-114 time=161 busy=0 rx=8
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* ACS: 3: min_nf=-114 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
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* ACS: 4: min_nf=-114 interference_factor=0.12963 nf=-113 time=162 busy=0 rx=21
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* ACS: 5: min_nf=-114 interference_factor=0.166667 nf=-114 time=162 busy=0 rx=27
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* ACS: * interference factor average: 0.0865885
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* ACS: Survey analysis for channel 9 (2452 MHz)
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* ACS: 1: min_nf=-114 interference_factor=0.0124224 nf=-114 time=161 busy=0 rx=2
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* ACS: 2: min_nf=-114 interference_factor=0.0310559 nf=-114 time=161 busy=0 rx=5
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* ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
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* ACS: 4: min_nf=-114 interference_factor=0.00617284 nf=-114 time=162 busy=0 rx=1
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* ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
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* ACS: * interference factor average: 0.00993022
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* ACS: Survey analysis for channel 10 (2457 MHz)
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* ACS: 1: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
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* ACS: 2: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
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* ACS: 3: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
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* ACS: 4: min_nf=-114 interference_factor=0.0493827 nf=-114 time=162 busy=0 rx=8
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* ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
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* ACS: * interference factor average: 0.0136033
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* ACS: Survey analysis for channel 11 (2462 MHz)
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* ACS: 1: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
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* ACS: 2: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=161 busy=0 rx=0
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* ACS: 3: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=161 busy=0 rx=0
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* ACS: 4: min_nf=-114 interference_factor=0.0432099 nf=-114 time=162 busy=0 rx=7
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* ACS: 5: min_nf=-114 interference_factor=0.0925926 nf=-114 time=162 busy=0 rx=15
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* ACS: * interference factor average: 0.0271605
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* ACS: Survey analysis for channel 12 (2467 MHz)
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* ACS: 1: min_nf=-114 interference_factor=0.0621118 nf=-113 time=161 busy=0 rx=10
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* ACS: 2: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
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* ACS: 3: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
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* ACS: 4: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
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* ACS: 5: min_nf=-114 interference_factor=0.00617284 nf=-113 time=162 busy=0 rx=1
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* ACS: * interference factor average: 0.0148992
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* ACS: Survey analysis for channel 13 (2472 MHz)
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* ACS: 1: min_nf=-114 interference_factor=0.0745342 nf=-114 time=161 busy=0 rx=12
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* ACS: 2: min_nf=-114 interference_factor=0.0555556 nf=-114 time=162 busy=0 rx=9
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* ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
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* ACS: 4: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
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* ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
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* ACS: * interference factor average: 0.0260179
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* ACS: Survey analysis for selected bandwidth 20MHz
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* ACS: * channel 1: total interference = 0.121432
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* ACS: * channel 2: total interference = 0.137512
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* ACS: * channel 3: total interference = 0.369757
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* ACS: * channel 4: total interference = 0.546338
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* ACS: * channel 5: total interference = 0.690538
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* ACS: * channel 6: total interference = 0.762242
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* ACS: * channel 7: total interference = 0.756092
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* ACS: * channel 8: total interference = 0.537451
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* ACS: * channel 9: total interference = 0.332313
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* ACS: * channel 10: total interference = 0.152182
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* ACS: * channel 11: total interference = 0.0916111
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* ACS: * channel 12: total interference = 0.0816809
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* ACS: * channel 13: total interference = 0.0680776
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* ACS: Ideal channel is 13 (2472 MHz) with total interference factor of 0.0680776
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*
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* [1] http://en.wikipedia.org/wiki/Near_and_far_field
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*/
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static int acs_request_scan(struct hostapd_iface *iface);
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static void acs_clean_chan_surveys(struct hostapd_channel_data *chan)
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{
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struct freq_survey *survey, *tmp;
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if (dl_list_empty(&chan->survey_list))
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return;
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dl_list_for_each_safe(survey, tmp, &chan->survey_list,
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struct freq_survey, list) {
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dl_list_del(&survey->list);
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os_free(survey);
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}
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}
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static void acs_cleanup(struct hostapd_iface *iface)
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{
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int i;
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struct hostapd_channel_data *chan;
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for (i = 0; i < iface->current_mode->num_channels; i++) {
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chan = &iface->current_mode->channels[i];
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if (chan->flag & HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED)
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acs_clean_chan_surveys(chan);
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dl_list_init(&chan->survey_list);
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chan->flag |= HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED;
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chan->min_nf = 0;
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}
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iface->chans_surveyed = 0;
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iface->acs_num_completed_scans = 0;
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}
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void acs_fail(struct hostapd_iface *iface)
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{
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wpa_printf(MSG_ERROR, "ACS: Failed to start");
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acs_cleanup(iface);
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}
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|
static long double
|
||
|
|
acs_survey_interference_factor(struct freq_survey *survey, s8 min_nf)
|
||
|
|
{
|
||
|
|
long double factor, busy, total;
|
||
|
|
|
||
|
|
if (survey->filled & SURVEY_HAS_CHAN_TIME_BUSY)
|
||
|
|
busy = survey->channel_time_busy;
|
||
|
|
else if (survey->filled & SURVEY_HAS_CHAN_TIME_RX)
|
||
|
|
busy = survey->channel_time_rx;
|
||
|
|
else {
|
||
|
|
/* This shouldn't really happen as survey data is checked in
|
||
|
|
* acs_sanity_check() */
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Survey data missing");
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
total = survey->channel_time;
|
||
|
|
|
||
|
|
if (survey->filled & SURVEY_HAS_CHAN_TIME_TX) {
|
||
|
|
busy -= survey->channel_time_tx;
|
||
|
|
total -= survey->channel_time_tx;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* TODO: figure out the best multiplier for noise floor base */
|
||
|
|
factor = pow(10, survey->nf / 5.0L) +
|
||
|
|
(busy / total) *
|
||
|
|
pow(2, pow(10, (long double) survey->nf / 10.0L) -
|
||
|
|
pow(10, (long double) min_nf / 10.0L));
|
||
|
|
|
||
|
|
return factor;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static void
|
||
|
|
acs_survey_chan_interference_factor(struct hostapd_iface *iface,
|
||
|
|
struct hostapd_channel_data *chan)
|
||
|
|
{
|
||
|
|
struct freq_survey *survey;
|
||
|
|
unsigned int i = 0;
|
||
|
|
long double int_factor = 0;
|
||
|
|
|
||
|
|
if (dl_list_empty(&chan->survey_list))
|
||
|
|
return;
|
||
|
|
|
||
|
|
if (chan->flag & HOSTAPD_CHAN_DISABLED)
|
||
|
|
return;
|
||
|
|
|
||
|
|
chan->interference_factor = 0;
|
||
|
|
|
||
|
|
dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
|
||
|
|
{
|
||
|
|
int_factor = acs_survey_interference_factor(survey,
|
||
|
|
iface->lowest_nf);
|
||
|
|
chan->interference_factor += int_factor;
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: %d: min_nf=%d interference_factor=%Lg nf=%d time=%lu busy=%lu rx=%lu",
|
||
|
|
++i, chan->min_nf, int_factor,
|
||
|
|
survey->nf, (unsigned long) survey->channel_time,
|
||
|
|
(unsigned long) survey->channel_time_busy,
|
||
|
|
(unsigned long) survey->channel_time_rx);
|
||
|
|
}
|
||
|
|
|
||
|
|
chan->interference_factor = chan->interference_factor /
|
||
|
|
dl_list_len(&chan->survey_list);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static int acs_usable_chan(struct hostapd_channel_data *chan)
|
||
|
|
{
|
||
|
|
if (dl_list_empty(&chan->survey_list))
|
||
|
|
return 0;
|
||
|
|
if (chan->flag & HOSTAPD_CHAN_DISABLED)
|
||
|
|
return 0;
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static int acs_usable_ht40_chan(struct hostapd_channel_data *chan)
|
||
|
|
{
|
||
|
|
const int allowed[] = { 36, 44, 52, 60, 100, 108, 116, 124, 132, 149,
|
||
|
|
157, 184, 192 };
|
||
|
|
unsigned int i;
|
||
|
|
|
||
|
|
for (i = 0; i < sizeof(allowed) / sizeof(allowed[0]); i++)
|
||
|
|
if (chan->chan == allowed[i])
|
||
|
|
return 1;
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static int acs_survey_is_sufficient(struct freq_survey *survey)
|
||
|
|
{
|
||
|
|
if (!(survey->filled & SURVEY_HAS_NF)) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Survey is missing noise floor");
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Survey is missing channel time");
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (!(survey->filled & SURVEY_HAS_CHAN_TIME_BUSY) &&
|
||
|
|
!(survey->filled & SURVEY_HAS_CHAN_TIME_RX)) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Survey is missing RX and busy time (at least one is required)");
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static int acs_surveys_are_sufficient(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
int i;
|
||
|
|
struct hostapd_channel_data *chan;
|
||
|
|
struct freq_survey *survey;
|
||
|
|
|
||
|
|
for (i = 0; i < iface->current_mode->num_channels; i++) {
|
||
|
|
chan = &iface->current_mode->channels[i];
|
||
|
|
if (chan->flag & HOSTAPD_CHAN_DISABLED)
|
||
|
|
continue;
|
||
|
|
|
||
|
|
dl_list_for_each(survey, &chan->survey_list,
|
||
|
|
struct freq_survey, list)
|
||
|
|
{
|
||
|
|
if (!acs_survey_is_sufficient(survey)) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Channel %d has insufficient survey data",
|
||
|
|
chan->chan);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static void acs_survey_all_chans_intereference_factor(
|
||
|
|
struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
int i;
|
||
|
|
struct hostapd_channel_data *chan;
|
||
|
|
|
||
|
|
for (i = 0; i < iface->current_mode->num_channels; i++) {
|
||
|
|
chan = &iface->current_mode->channels[i];
|
||
|
|
|
||
|
|
if (!acs_usable_chan(chan))
|
||
|
|
continue;
|
||
|
|
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Survey analysis for channel %d (%d MHz)",
|
||
|
|
chan->chan, chan->freq);
|
||
|
|
|
||
|
|
acs_survey_chan_interference_factor(iface, chan);
|
||
|
|
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: * interference factor average: %Lg",
|
||
|
|
chan->interference_factor);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static struct hostapd_channel_data *acs_find_chan(struct hostapd_iface *iface,
|
||
|
|
int freq)
|
||
|
|
{
|
||
|
|
struct hostapd_channel_data *chan;
|
||
|
|
int i;
|
||
|
|
|
||
|
|
for (i = 0; i < iface->current_mode->num_channels; i++) {
|
||
|
|
chan = &iface->current_mode->channels[i];
|
||
|
|
|
||
|
|
if (!acs_usable_chan(chan))
|
||
|
|
continue;
|
||
|
|
|
||
|
|
if (chan->freq == freq)
|
||
|
|
return chan;
|
||
|
|
}
|
||
|
|
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*
|
||
|
|
* At this point it's assumed chan->interface_factor has been computed.
|
||
|
|
* This function should be reusable regardless of interference computation
|
||
|
|
* option (survey, BSS, spectral, ...). chan->interference factor must be
|
||
|
|
* summable (i.e., must be always greater than zero).
|
||
|
|
*/
|
||
|
|
static struct hostapd_channel_data *
|
||
|
|
acs_find_ideal_chan(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
struct hostapd_channel_data *chan, *adj_chan, *ideal_chan = NULL;
|
||
|
|
long double factor, ideal_factor = 0;
|
||
|
|
int i, j;
|
||
|
|
int n_chans = 1;
|
||
|
|
|
||
|
|
/* TODO: HT40- support */
|
||
|
|
|
||
|
|
if (iface->conf->ieee80211n &&
|
||
|
|
iface->conf->secondary_channel == -1) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: HT40- is not supported yet. Please try HT40+");
|
||
|
|
return NULL;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (iface->conf->ieee80211n &&
|
||
|
|
iface->conf->secondary_channel)
|
||
|
|
n_chans = 2;
|
||
|
|
|
||
|
|
if (iface->conf->ieee80211ac &&
|
||
|
|
iface->conf->vht_oper_chwidth == 1)
|
||
|
|
n_chans = 4;
|
||
|
|
|
||
|
|
/* TODO: VHT80+80, VHT160. Update acs_adjust_vht_center_freq() too. */
|
||
|
|
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Survey analysis for selected bandwidth %d MHz",
|
||
|
|
n_chans == 1 ? 20 :
|
||
|
|
n_chans == 2 ? 40 :
|
||
|
|
n_chans == 4 ? 80 :
|
||
|
|
-1);
|
||
|
|
|
||
|
|
for (i = 0; i < iface->current_mode->num_channels; i++) {
|
||
|
|
chan = &iface->current_mode->channels[i];
|
||
|
|
|
||
|
|
if (!acs_usable_chan(chan))
|
||
|
|
continue;
|
||
|
|
|
||
|
|
/* HT40 on 5 GHz has a limited set of primary channels as per
|
||
|
|
* 11n Annex J */
|
||
|
|
if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
|
||
|
|
iface->conf->ieee80211n &&
|
||
|
|
iface->conf->secondary_channel &&
|
||
|
|
!acs_usable_ht40_chan(chan)) {
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for HT40",
|
||
|
|
chan->chan);
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
|
||
|
|
factor = chan->interference_factor;
|
||
|
|
|
||
|
|
for (j = 1; j < n_chans; j++) {
|
||
|
|
adj_chan = acs_find_chan(iface, chan->freq + (j * 20));
|
||
|
|
if (!adj_chan)
|
||
|
|
break;
|
||
|
|
|
||
|
|
factor += adj_chan->interference_factor;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (j != n_chans) {
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Channel %d: not enough bandwidth",
|
||
|
|
chan->chan);
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* 2.4 GHz has overlapping 20 MHz channels. Include adjacent
|
||
|
|
* channel interference factor. */
|
||
|
|
if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211B ||
|
||
|
|
iface->current_mode->mode == HOSTAPD_MODE_IEEE80211G) {
|
||
|
|
for (j = 0; j < n_chans; j++) {
|
||
|
|
/* TODO: perhaps a multiplier should be used
|
||
|
|
* here? */
|
||
|
|
|
||
|
|
adj_chan = acs_find_chan(iface, chan->freq +
|
||
|
|
(j * 20) - 5);
|
||
|
|
if (adj_chan)
|
||
|
|
factor += adj_chan->interference_factor;
|
||
|
|
|
||
|
|
adj_chan = acs_find_chan(iface, chan->freq +
|
||
|
|
(j * 20) - 10);
|
||
|
|
if (adj_chan)
|
||
|
|
factor += adj_chan->interference_factor;
|
||
|
|
|
||
|
|
adj_chan = acs_find_chan(iface, chan->freq +
|
||
|
|
(j * 20) + 5);
|
||
|
|
if (adj_chan)
|
||
|
|
factor += adj_chan->interference_factor;
|
||
|
|
|
||
|
|
adj_chan = acs_find_chan(iface, chan->freq +
|
||
|
|
(j * 20) + 10);
|
||
|
|
if (adj_chan)
|
||
|
|
factor += adj_chan->interference_factor;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: * channel %d: total interference = %Lg",
|
||
|
|
chan->chan, factor);
|
||
|
|
|
||
|
|
if (!ideal_chan || factor < ideal_factor) {
|
||
|
|
ideal_factor = factor;
|
||
|
|
ideal_chan = chan;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if (ideal_chan)
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Ideal channel is %d (%d MHz) with total interference factor of %Lg",
|
||
|
|
ideal_chan->chan, ideal_chan->freq, ideal_factor);
|
||
|
|
|
||
|
|
return ideal_chan;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static void acs_adjust_vht_center_freq(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency");
|
||
|
|
|
||
|
|
switch (iface->conf->vht_oper_chwidth) {
|
||
|
|
case VHT_CHANWIDTH_USE_HT:
|
||
|
|
iface->conf->vht_oper_centr_freq_seg0_idx =
|
||
|
|
iface->conf->channel + 2;
|
||
|
|
break;
|
||
|
|
case VHT_CHANWIDTH_80MHZ:
|
||
|
|
iface->conf->vht_oper_centr_freq_seg0_idx =
|
||
|
|
iface->conf->channel + 6;
|
||
|
|
break;
|
||
|
|
default:
|
||
|
|
/* TODO: How can this be calculated? Adjust
|
||
|
|
* acs_find_ideal_chan() */
|
||
|
|
wpa_printf(MSG_INFO, "ACS: Only VHT20/40/80 is supported now");
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static int acs_study_survey_based(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Trying survey-based ACS");
|
||
|
|
|
||
|
|
if (!iface->chans_surveyed) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Unable to collect survey data");
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (!acs_surveys_are_sufficient(iface)) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Surveys have insufficient data");
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
|
||
|
|
acs_survey_all_chans_intereference_factor(iface);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static int acs_study_options(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
int err;
|
||
|
|
|
||
|
|
err = acs_study_survey_based(iface);
|
||
|
|
if (err == 0)
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
/* TODO: If no surveys are available/sufficient this is a good
|
||
|
|
* place to fallback to BSS-based ACS */
|
||
|
|
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static void acs_study(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
struct hostapd_channel_data *ideal_chan;
|
||
|
|
int err;
|
||
|
|
|
||
|
|
err = acs_study_options(iface);
|
||
|
|
if (err < 0) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: All study options have failed");
|
||
|
|
goto fail;
|
||
|
|
}
|
||
|
|
|
||
|
|
ideal_chan = acs_find_ideal_chan(iface);
|
||
|
|
if (!ideal_chan) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Failed to compute ideal channel");
|
||
|
|
goto fail;
|
||
|
|
}
|
||
|
|
|
||
|
|
iface->conf->channel = ideal_chan->chan;
|
||
|
|
|
||
|
|
if (iface->conf->ieee80211ac)
|
||
|
|
acs_adjust_vht_center_freq(iface);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* hostapd_setup_interface_complete() will return -1 on failure,
|
||
|
|
* 0 on success and 0 is HOSTAPD_CHAN_VALID :)
|
||
|
|
*/
|
||
|
|
switch (hostapd_acs_completed(iface)) {
|
||
|
|
case HOSTAPD_CHAN_VALID:
|
||
|
|
acs_cleanup(iface);
|
||
|
|
return;
|
||
|
|
case HOSTAPD_CHAN_INVALID:
|
||
|
|
case HOSTAPD_CHAN_ACS:
|
||
|
|
default:
|
||
|
|
/* This can possibly happen if channel parameters (secondary
|
||
|
|
* channel, center frequencies) are misconfigured */
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Possibly channel configuration is invalid, please report this along with your config file.");
|
||
|
|
goto fail;
|
||
|
|
}
|
||
|
|
|
||
|
|
fail:
|
||
|
|
acs_fail(iface);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static void acs_scan_complete(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
int err;
|
||
|
|
|
||
|
|
iface->scan_cb = NULL;
|
||
|
|
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Using survey based algorithm (acs_num_scans=%d)",
|
||
|
|
iface->conf->acs_num_scans);
|
||
|
|
|
||
|
|
err = hostapd_drv_get_survey(iface->bss[0], 0);
|
||
|
|
if (err) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Failed to get survey data");
|
||
|
|
acs_fail(iface);
|
||
|
|
}
|
||
|
|
|
||
|
|
if (++iface->acs_num_completed_scans < iface->conf->acs_num_scans) {
|
||
|
|
err = acs_request_scan(iface);
|
||
|
|
if (err) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Failed to request scan");
|
||
|
|
acs_fail(iface);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
acs_study(iface);
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
static int acs_request_scan(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
struct wpa_driver_scan_params params;
|
||
|
|
struct hostapd_channel_data *chan;
|
||
|
|
int i, *freq;
|
||
|
|
|
||
|
|
os_memset(¶ms, 0, sizeof(params));
|
||
|
|
params.freqs = os_calloc(iface->current_mode->num_channels + 1,
|
||
|
|
sizeof(params.freqs[0]));
|
||
|
|
if (params.freqs == NULL)
|
||
|
|
return -1;
|
||
|
|
|
||
|
|
freq = params.freqs;
|
||
|
|
for (i = 0; i < iface->current_mode->num_channels; i++) {
|
||
|
|
chan = &iface->current_mode->channels[i];
|
||
|
|
if (chan->flag & HOSTAPD_CHAN_DISABLED)
|
||
|
|
continue;
|
||
|
|
|
||
|
|
*freq++ = chan->freq;
|
||
|
|
}
|
||
|
|
*freq = 0;
|
||
|
|
|
||
|
|
iface->scan_cb = acs_scan_complete;
|
||
|
|
|
||
|
|
wpa_printf(MSG_DEBUG, "ACS: Scanning %d / %d",
|
||
|
|
iface->acs_num_completed_scans + 1,
|
||
|
|
iface->conf->acs_num_scans);
|
||
|
|
|
||
|
|
if (hostapd_driver_scan(iface->bss[0], ¶ms) < 0) {
|
||
|
|
wpa_printf(MSG_ERROR, "ACS: Failed to request initial scan");
|
||
|
|
acs_cleanup(iface);
|
||
|
|
return -1;
|
||
|
|
}
|
||
|
|
|
||
|
|
os_free(params.freqs);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
enum hostapd_chan_status acs_init(struct hostapd_iface *iface)
|
||
|
|
{
|
||
|
|
int err;
|
||
|
|
|
||
|
|
wpa_printf(MSG_INFO, "ACS: Automatic channel selection started, this may take a bit");
|
||
|
|
|
||
|
|
acs_cleanup(iface);
|
||
|
|
|
||
|
|
err = acs_request_scan(iface);
|
||
|
|
if (err < 0)
|
||
|
|
return HOSTAPD_CHAN_INVALID;
|
||
|
|
|
||
|
|
return HOSTAPD_CHAN_ACS;
|
||
|
|
}
|