--- /dev/null
+/*
+ * ACS - Automatic Channel Selection module
+ * Copyright (c) 2011, Atheros Communications
+ * Copyright (c) 2013, Qualcomm Atheros, Inc.
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "utils/includes.h"
+#include <math.h>
+
+#include "utils/common.h"
+#include "utils/list.h"
+#include "common/ieee802_11_defs.h"
+#include "common/wpa_ctrl.h"
+#include "drivers/driver.h"
+#include "hostapd.h"
+#include "ap_drv_ops.h"
+#include "ap_config.h"
+#include "hw_features.h"
+#include "acs.h"
+
+/*
+ * Automatic Channel Selection
+ * ===========================
+ *
+ * More info at
+ * ------------
+ * http://wireless.kernel.org/en/users/Documentation/acs
+ *
+ * How to use
+ * ----------
+ * - make sure you have CONFIG_ACS=y in hostapd's .config
+ * - use channel=0 or channel=acs to enable ACS
+ *
+ * How does it work
+ * ----------------
+ * 1. passive scans are used to collect survey data
+ * (it is assumed that scan trigger collection of survey data in driver)
+ * 2. interference factor is calculated for each channel
+ * 3. ideal channel is picked depending on channel width by using adjacent
+ * channel interference factors
+ *
+ * Known limitations
+ * -----------------
+ * - Current implementation depends heavily on the amount of time willing to
+ * spend gathering survey data during hostapd startup. Short traffic bursts
+ * may be missed and a suboptimal channel may be picked.
+ * - Ideal channel may end up overlapping a channel with 40 MHz intolerant BSS
+ *
+ * Todo / Ideas
+ * ------------
+ * - implement other interference computation methods
+ * - BSS/RSSI based
+ * - spectral scan based
+ * (should be possibly to hook this up with current ACS scans)
+ * - add wpa_supplicant support (for P2P)
+ * - collect a histogram of interference over time allowing more educated
+ * guess about an ideal channel (perhaps CSA could be used to migrate AP to a
+ * new "better" channel while running)
+ * - include neighboring BSS scan to avoid conflicts with 40 MHz intolerant BSSs
+ * when choosing the ideal channel
+ *
+ * Survey interference factor implementation details
+ * -------------------------------------------------
+ * Generic interference_factor in struct hostapd_channel_data is used.
+ *
+ * The survey interference factor is defined as the ratio of the
+ * observed busy time over the time we spent on the channel,
+ * this value is then amplified by the observed noise floor on
+ * the channel in comparison to the lowest noise floor observed
+ * on the entire band.
+ *
+ * This corresponds to:
+ * ---
+ * (busy time - tx time) / (active time - tx time) * 2^(chan_nf + band_min_nf)
+ * ---
+ *
+ * The coefficient of 2 reflects the way power in "far-field"
+ * radiation decreases as the square of distance from the antenna [1].
+ * What this does is it decreases the observed busy time ratio if the
+ * noise observed was low but increases it if the noise was high,
+ * proportionally to the way "far field" radiation changes over
+ * distance.
+ *
+ * If channel busy time is not available the fallback is to use channel RX time.
+ *
+ * Since noise floor is in dBm it is necessary to convert it into Watts so that
+ * combined channel interference (e.g., HT40, which uses two channels) can be
+ * calculated easily.
+ * ---
+ * (busy time - tx time) / (active time - tx time) *
+ * 2^(10^(chan_nf/10) + 10^(band_min_nf/10))
+ * ---
+ *
+ * However to account for cases where busy/rx time is 0 (channel load is then
+ * 0%) channel noise floor signal power is combined into the equation so a
+ * channel with lower noise floor is preferred. The equation becomes:
+ * ---
+ * 10^(chan_nf/5) + (busy time - tx time) / (active time - tx time) *
+ * 2^(10^(chan_nf/10) + 10^(band_min_nf/10))
+ * ---
+ *
+ * All this "interference factor" is purely subjective and only time
+ * will tell how usable this is. By using the minimum noise floor we
+ * remove any possible issues due to card calibration. The computation
+ * of the interference factor then is dependent on what the card itself
+ * picks up as the minimum noise, not an actual real possible card
+ * noise value.
+ *
+ * Total interference computation details
+ * --------------------------------------
+ * The above channel interference factor is calculated with no respect to
+ * target operational bandwidth.
+ *
+ * To find an ideal channel the above data is combined by taking into account
+ * the target operational bandwidth and selected band. E.g., on 2.4 GHz channels
+ * overlap with 20 MHz bandwidth, but there is no overlap for 20 MHz bandwidth
+ * on 5 GHz.
+ *
+ * Each valid and possible channel spec (i.e., channel + width) is taken and its
+ * interference factor is computed by summing up interferences of each channel
+ * it overlaps. The one with least total interference is picked up.
+ *
+ * Note: This implies base channel interference factor must be non-negative
+ * allowing easy summing up.
+ *
+ * Example ACS analysis printout
+ * -----------------------------
+ *
+ * ACS: Trying survey-based ACS
+ * ACS: Survey analysis for channel 1 (2412 MHz)
+ * ACS: 1: min_nf=-113 interference_factor=0.0802469 nf=-113 time=162 busy=0 rx=13
+ * ACS: 2: min_nf=-113 interference_factor=0.0745342 nf=-113 time=161 busy=0 rx=12
+ * ACS: 3: min_nf=-113 interference_factor=0.0679012 nf=-113 time=162 busy=0 rx=11
+ * ACS: 4: min_nf=-113 interference_factor=0.0310559 nf=-113 time=161 busy=0 rx=5
+ * ACS: 5: min_nf=-113 interference_factor=0.0248447 nf=-113 time=161 busy=0 rx=4
+ * ACS: * interference factor average: 0.0557166
+ * ACS: Survey analysis for channel 2 (2417 MHz)
+ * ACS: 1: min_nf=-113 interference_factor=0.0185185 nf=-113 time=162 busy=0 rx=3
+ * ACS: 2: min_nf=-113 interference_factor=0.0246914 nf=-113 time=162 busy=0 rx=4
+ * ACS: 3: min_nf=-113 interference_factor=0.037037 nf=-113 time=162 busy=0 rx=6
+ * ACS: 4: min_nf=-113 interference_factor=0.149068 nf=-113 time=161 busy=0 rx=24
+ * ACS: 5: min_nf=-113 interference_factor=0.0248447 nf=-113 time=161 busy=0 rx=4
+ * ACS: * interference factor average: 0.050832
+ * ACS: Survey analysis for channel 3 (2422 MHz)
+ * ACS: 1: min_nf=-113 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
+ * ACS: 2: min_nf=-113 interference_factor=0.0185185 nf=-113 time=162 busy=0 rx=3
+ * ACS: 3: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
+ * ACS: 4: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
+ * ACS: 5: min_nf=-113 interference_factor=0.0186335 nf=-113 time=161 busy=0 rx=3
+ * ACS: * interference factor average: 0.0148838
+ * ACS: Survey analysis for channel 4 (2427 MHz)
+ * ACS: 1: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
+ * ACS: 2: min_nf=-114 interference_factor=0.0555556 nf=-114 time=162 busy=0 rx=9
+ * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
+ * ACS: 4: min_nf=-114 interference_factor=0.0186335 nf=-114 time=161 busy=0 rx=3
+ * ACS: 5: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
+ * ACS: * interference factor average: 0.0160801
+ * ACS: Survey analysis for channel 5 (2432 MHz)
+ * ACS: 1: min_nf=-114 interference_factor=0.409938 nf=-113 time=161 busy=0 rx=66
+ * ACS: 2: min_nf=-114 interference_factor=0.0432099 nf=-113 time=162 busy=0 rx=7
+ * ACS: 3: min_nf=-114 interference_factor=0.0124224 nf=-113 time=161 busy=0 rx=2
+ * ACS: 4: min_nf=-114 interference_factor=0.677019 nf=-113 time=161 busy=0 rx=109
+ * ACS: 5: min_nf=-114 interference_factor=0.0186335 nf=-114 time=161 busy=0 rx=3
+ * ACS: * interference factor average: 0.232244
+ * ACS: Survey analysis for channel 6 (2437 MHz)
+ * ACS: 1: min_nf=-113 interference_factor=0.552795 nf=-113 time=161 busy=0 rx=89
+ * ACS: 2: min_nf=-113 interference_factor=0.0807453 nf=-112 time=161 busy=0 rx=13
+ * ACS: 3: min_nf=-113 interference_factor=0.0310559 nf=-113 time=161 busy=0 rx=5
+ * ACS: 4: min_nf=-113 interference_factor=0.434783 nf=-112 time=161 busy=0 rx=70
+ * ACS: 5: min_nf=-113 interference_factor=0.0621118 nf=-113 time=161 busy=0 rx=10
+ * ACS: * interference factor average: 0.232298
+ * ACS: Survey analysis for channel 7 (2442 MHz)
+ * ACS: 1: min_nf=-113 interference_factor=0.440994 nf=-112 time=161 busy=0 rx=71
+ * ACS: 2: min_nf=-113 interference_factor=0.385093 nf=-113 time=161 busy=0 rx=62
+ * ACS: 3: min_nf=-113 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
+ * ACS: 4: min_nf=-113 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
+ * ACS: 5: min_nf=-113 interference_factor=0.0745342 nf=-113 time=161 busy=0 rx=12
+ * ACS: * interference factor average: 0.195031
+ * ACS: Survey analysis for channel 8 (2447 MHz)
+ * ACS: 1: min_nf=-114 interference_factor=0.0496894 nf=-112 time=161 busy=0 rx=8
+ * ACS: 2: min_nf=-114 interference_factor=0.0496894 nf=-114 time=161 busy=0 rx=8
+ * ACS: 3: min_nf=-114 interference_factor=0.0372671 nf=-113 time=161 busy=0 rx=6
+ * ACS: 4: min_nf=-114 interference_factor=0.12963 nf=-113 time=162 busy=0 rx=21
+ * ACS: 5: min_nf=-114 interference_factor=0.166667 nf=-114 time=162 busy=0 rx=27
+ * ACS: * interference factor average: 0.0865885
+ * ACS: Survey analysis for channel 9 (2452 MHz)
+ * ACS: 1: min_nf=-114 interference_factor=0.0124224 nf=-114 time=161 busy=0 rx=2
+ * ACS: 2: min_nf=-114 interference_factor=0.0310559 nf=-114 time=161 busy=0 rx=5
+ * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
+ * ACS: 4: min_nf=-114 interference_factor=0.00617284 nf=-114 time=162 busy=0 rx=1
+ * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
+ * ACS: * interference factor average: 0.00993022
+ * ACS: Survey analysis for channel 10 (2457 MHz)
+ * ACS: 1: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
+ * ACS: 2: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
+ * ACS: 3: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
+ * ACS: 4: min_nf=-114 interference_factor=0.0493827 nf=-114 time=162 busy=0 rx=8
+ * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
+ * ACS: * interference factor average: 0.0136033
+ * ACS: Survey analysis for channel 11 (2462 MHz)
+ * ACS: 1: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=161 busy=0 rx=0
+ * ACS: 2: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=161 busy=0 rx=0
+ * ACS: 3: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=161 busy=0 rx=0
+ * ACS: 4: min_nf=-114 interference_factor=0.0432099 nf=-114 time=162 busy=0 rx=7
+ * ACS: 5: min_nf=-114 interference_factor=0.0925926 nf=-114 time=162 busy=0 rx=15
+ * ACS: * interference factor average: 0.0271605
+ * ACS: Survey analysis for channel 12 (2467 MHz)
+ * ACS: 1: min_nf=-114 interference_factor=0.0621118 nf=-113 time=161 busy=0 rx=10
+ * ACS: 2: min_nf=-114 interference_factor=0.00621118 nf=-114 time=161 busy=0 rx=1
+ * ACS: 3: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
+ * ACS: 4: min_nf=-114 interference_factor=2.51189e-23 nf=-113 time=162 busy=0 rx=0
+ * ACS: 5: min_nf=-114 interference_factor=0.00617284 nf=-113 time=162 busy=0 rx=1
+ * ACS: * interference factor average: 0.0148992
+ * ACS: Survey analysis for channel 13 (2472 MHz)
+ * ACS: 1: min_nf=-114 interference_factor=0.0745342 nf=-114 time=161 busy=0 rx=12
+ * ACS: 2: min_nf=-114 interference_factor=0.0555556 nf=-114 time=162 busy=0 rx=9
+ * ACS: 3: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
+ * ACS: 4: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
+ * ACS: 5: min_nf=-114 interference_factor=1.58489e-23 nf=-114 time=162 busy=0 rx=0
+ * ACS: * interference factor average: 0.0260179
+ * ACS: Survey analysis for selected bandwidth 20MHz
+ * ACS: * channel 1: total interference = 0.121432
+ * ACS: * channel 2: total interference = 0.137512
+ * ACS: * channel 3: total interference = 0.369757
+ * ACS: * channel 4: total interference = 0.546338
+ * ACS: * channel 5: total interference = 0.690538
+ * ACS: * channel 6: total interference = 0.762242
+ * ACS: * channel 7: total interference = 0.756092
+ * ACS: * channel 8: total interference = 0.537451
+ * ACS: * channel 9: total interference = 0.332313
+ * ACS: * channel 10: total interference = 0.152182
+ * ACS: * channel 11: total interference = 0.0916111
+ * ACS: * channel 12: total interference = 0.0816809
+ * ACS: * channel 13: total interference = 0.0680776
+ * ACS: Ideal channel is 13 (2472 MHz) with total interference factor of 0.0680776
+ *
+ * [1] http://en.wikipedia.org/wiki/Near_and_far_field
+ */
+
+
+static int acs_request_scan(struct hostapd_iface *iface);
+static int acs_survey_is_sufficient(struct freq_survey *survey);
+
+
+static void acs_clean_chan_surveys(struct hostapd_channel_data *chan)
+{
+ struct freq_survey *survey, *tmp;
+
+ if (dl_list_empty(&chan->survey_list))
+ return;
+
+ dl_list_for_each_safe(survey, tmp, &chan->survey_list,
+ struct freq_survey, list) {
+ dl_list_del(&survey->list);
+ os_free(survey);
+ }
+}
+
+
+static void acs_cleanup(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 (chan->flag & HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED)
+ acs_clean_chan_surveys(chan);
+
+ dl_list_init(&chan->survey_list);
+ chan->flag |= HOSTAPD_CHAN_SURVEY_LIST_INITIALIZED;
+ chan->min_nf = 0;
+ }
+
+ iface->chans_surveyed = 0;
+ iface->acs_num_completed_scans = 0;
+}
+
+
+static void acs_fail(struct hostapd_iface *iface)
+{
+ wpa_printf(MSG_ERROR, "ACS: Failed to start");
+ acs_cleanup(iface);
+ hostapd_disable_iface(iface);
+}
+
+
+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;
+ unsigned count = 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)
+ {
+ i++;
+
+ if (!acs_survey_is_sufficient(survey)) {
+ wpa_printf(MSG_DEBUG, "ACS: %d: insufficient data", i);
+ continue;
+ }
+
+ count++;
+ 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);
+ }
+
+ if (!count)
+ return;
+ chan->interference_factor /= count;
+}
+
+
+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 < ARRAY_SIZE(allowed); i++)
+ if (chan->chan == allowed[i])
+ return 1;
+
+ return 0;
+}
+
+
+static int acs_usable_vht80_chan(struct hostapd_channel_data *chan)
+{
+ const int allowed[] = { 36, 52, 100, 116, 132, 149 };
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(allowed); 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_INFO, "ACS: Survey is missing noise floor");
+ return 0;
+ }
+
+ if (!(survey->filled & SURVEY_HAS_CHAN_TIME)) {
+ wpa_printf(MSG_INFO, "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_INFO,
+ "ACS: Survey is missing RX and busy time (at least one is required)");
+ return 0;
+ }
+
+ return 1;
+}
+
+
+static int acs_survey_list_is_sufficient(struct hostapd_channel_data *chan)
+{
+ struct freq_survey *survey;
+ int ret = -1;
+
+ dl_list_for_each(survey, &chan->survey_list, struct freq_survey, list)
+ {
+ if (acs_survey_is_sufficient(survey)) {
+ ret = 1;
+ break;
+ }
+ ret = 0;
+ }
+
+ if (ret == -1)
+ ret = 1; /* no survey list entries */
+
+ if (!ret) {
+ wpa_printf(MSG_INFO,
+ "ACS: Channel %d has insufficient survey data",
+ chan->chan);
+ }
+
+ return ret;
+}
+
+
+static int acs_surveys_are_sufficient(struct hostapd_iface *iface)
+{
+ int i;
+ struct hostapd_channel_data *chan;
+ int valid = 0;
+
+ for (i = 0; i < iface->current_mode->num_channels; i++) {
+ chan = &iface->current_mode->channels[i];
+ if (chan->flag & HOSTAPD_CHAN_DISABLED)
+ continue;
+
+ if (!acs_survey_list_is_sufficient(chan))
+ continue;
+
+ valid++;
+ }
+
+ /* We need at least survey data for one channel */
+ return !!valid;
+}
+
+
+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;
+ if (!acs_survey_list_is_sufficient(chan))
+ return 0;
+ return 1;
+}
+
+
+static int is_in_chanlist(struct hostapd_iface *iface,
+ struct hostapd_channel_data *chan)
+{
+ if (!iface->conf->acs_ch_list.num)
+ return 1;
+
+ return freq_range_list_includes(&iface->conf->acs_ch_list, chan->chan);
+}
+
+
+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;
+
+ if (!is_in_chanlist(iface, 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 (chan->flag & HOSTAPD_CHAN_DISABLED)
+ continue;
+
+ if (chan->freq == freq)
+ return chan;
+ }
+
+ return NULL;
+}
+
+
+static int is_24ghz_mode(enum hostapd_hw_mode mode)
+{
+ return mode == HOSTAPD_MODE_IEEE80211B ||
+ mode == HOSTAPD_MODE_IEEE80211G;
+}
+
+
+static int is_common_24ghz_chan(int chan)
+{
+ return chan == 1 || chan == 6 || chan == 11;
+}
+
+
+#ifndef ACS_ADJ_WEIGHT
+#define ACS_ADJ_WEIGHT 0.85
+#endif /* ACS_ADJ_WEIGHT */
+
+#ifndef ACS_NEXT_ADJ_WEIGHT
+#define ACS_NEXT_ADJ_WEIGHT 0.55
+#endif /* ACS_NEXT_ADJ_WEIGHT */
+
+#ifndef ACS_24GHZ_PREFER_1_6_11
+/*
+ * Select commonly used channels 1, 6, 11 by default even if a neighboring
+ * channel has a smaller interference factor as long as it is not better by more
+ * than this multiplier.
+ */
+#define ACS_24GHZ_PREFER_1_6_11 0.8
+#endif /* ACS_24GHZ_PREFER_1_6_11 */
+
+/*
+ * 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,
+ *rand_chan = NULL;
+ long double factor, ideal_factor = 0;
+ int i, j;
+ int n_chans = 1;
+ unsigned int k;
+
+ /* 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 :
+ 80);
+
+ for (i = 0; i < iface->current_mode->num_channels; i++) {
+ double total_weight;
+ struct acs_bias *bias, tmp_bias;
+
+ chan = &iface->current_mode->channels[i];
+
+ if (chan->flag & HOSTAPD_CHAN_DISABLED)
+ continue;
+
+ if (!is_in_chanlist(iface, 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;
+ }
+
+ if (iface->current_mode->mode == HOSTAPD_MODE_IEEE80211A &&
+ iface->conf->ieee80211ac &&
+ iface->conf->vht_oper_chwidth == 1 &&
+ !acs_usable_vht80_chan(chan)) {
+ wpa_printf(MSG_DEBUG, "ACS: Channel %d: not allowed as primary channel for VHT80",
+ chan->chan);
+ continue;
+ }
+
+ factor = 0;
+ if (acs_usable_chan(chan))
+ factor = chan->interference_factor;
+ total_weight = 1;
+
+ for (j = 1; j < n_chans; j++) {
+ adj_chan = acs_find_chan(iface, chan->freq + (j * 20));
+ if (!adj_chan)
+ break;
+
+ if (acs_usable_chan(adj_chan)) {
+ factor += adj_chan->interference_factor;
+ total_weight += 1;
+ }
+ }
+
+ 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 (is_24ghz_mode(iface->current_mode->mode)) {
+ for (j = 0; j < n_chans; j++) {
+ adj_chan = acs_find_chan(iface, chan->freq +
+ (j * 20) - 5);
+ if (adj_chan && acs_usable_chan(adj_chan)) {
+ factor += ACS_ADJ_WEIGHT *
+ adj_chan->interference_factor;
+ total_weight += ACS_ADJ_WEIGHT;
+ }
+
+ adj_chan = acs_find_chan(iface, chan->freq +
+ (j * 20) - 10);
+ if (adj_chan && acs_usable_chan(adj_chan)) {
+ factor += ACS_NEXT_ADJ_WEIGHT *
+ adj_chan->interference_factor;
+ total_weight += ACS_NEXT_ADJ_WEIGHT;
+ }
+
+ adj_chan = acs_find_chan(iface, chan->freq +
+ (j * 20) + 5);
+ if (adj_chan && acs_usable_chan(adj_chan)) {
+ factor += ACS_ADJ_WEIGHT *
+ adj_chan->interference_factor;
+ total_weight += ACS_ADJ_WEIGHT;
+ }
+
+ adj_chan = acs_find_chan(iface, chan->freq +
+ (j * 20) + 10);
+ if (adj_chan && acs_usable_chan(adj_chan)) {
+ factor += ACS_NEXT_ADJ_WEIGHT *
+ adj_chan->interference_factor;
+ total_weight += ACS_NEXT_ADJ_WEIGHT;
+ }
+ }
+ }
+
+ factor /= total_weight;
+
+ bias = NULL;
+ if (iface->conf->acs_chan_bias) {
+ for (k = 0; k < iface->conf->num_acs_chan_bias; k++) {
+ bias = &iface->conf->acs_chan_bias[k];
+ if (bias->channel == chan->chan)
+ break;
+ bias = NULL;
+ }
+ } else if (is_24ghz_mode(iface->current_mode->mode) &&
+ is_common_24ghz_chan(chan->chan)) {
+ tmp_bias.channel = chan->chan;
+ tmp_bias.bias = ACS_24GHZ_PREFER_1_6_11;
+ bias = &tmp_bias;
+ }
+
+ if (bias) {
+ factor *= bias->bias;
+ wpa_printf(MSG_DEBUG,
+ "ACS: * channel %d: total interference = %Lg (%f bias)",
+ chan->chan, factor, bias->bias);
+ } else {
+ wpa_printf(MSG_DEBUG,
+ "ACS: * channel %d: total interference = %Lg",
+ chan->chan, factor);
+ }
+
+ if (acs_usable_chan(chan) &&
+ (!ideal_chan || factor < ideal_factor)) {
+ ideal_factor = factor;
+ ideal_chan = chan;
+ }
+
+ /* This channel would at least be usable */
+ if (!rand_chan)
+ rand_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;
+ }
+
+ return rand_chan;
+}
+
+
+static void acs_adjust_vht_center_freq(struct hostapd_iface *iface)
+{
+ int offset;
+
+ wpa_printf(MSG_DEBUG, "ACS: Adjusting VHT center frequency");
+
+ switch (iface->conf->vht_oper_chwidth) {
+ case VHT_CHANWIDTH_USE_HT:
+ offset = 2 * iface->conf->secondary_channel;
+ break;
+ case VHT_CHANWIDTH_80MHZ:
+ offset = 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");
+ return;
+ }
+
+ iface->conf->vht_oper_centr_freq_seg0_idx =
+ iface->conf->channel + offset;
+}
+
+
+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");
+ err = -1;
+ goto fail;
+ }
+
+ iface->conf->channel = ideal_chan->chan;
+
+ if (iface->conf->ieee80211ac)
+ acs_adjust_vht_center_freq(iface);
+
+ err = 0;
+fail:
+ /*
+ * hostapd_setup_interface_complete() will return -1 on failure,
+ * 0 on success and 0 is HOSTAPD_CHAN_VALID :)
+ */
+ if (hostapd_acs_completed(iface, err) == HOSTAPD_CHAN_VALID) {
+ acs_cleanup(iface);
+ return;
+ }
+
+ /* 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.");
+ 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");
+ goto fail;
+ }
+
+ 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");
+ goto fail;
+ }
+
+ return;
+ }
+
+ acs_study(iface);
+ return;
+fail:
+ hostapd_acs_completed(iface, 1);
+ acs_fail(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;
+
+ if (!is_in_chanlist(iface, chan))
+ 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);
+ os_free(params.freqs);
+ 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");
+
+ if (iface->drv_flags & WPA_DRIVER_FLAGS_ACS_OFFLOAD) {
+ wpa_printf(MSG_INFO, "ACS: Offloading to driver");
+ err = hostapd_drv_do_acs(iface->bss[0]);
+ if (err)
+ return HOSTAPD_CHAN_INVALID;
+ return HOSTAPD_CHAN_ACS;
+ }
+
+ if (!iface->current_mode)
+ return HOSTAPD_CHAN_INVALID;
+
+ acs_cleanup(iface);
+
+ err = acs_request_scan(iface);
+ if (err < 0)
+ return HOSTAPD_CHAN_INVALID;
+
+ hostapd_set_state(iface, HAPD_IFACE_ACS);
+ wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, ACS_EVENT_STARTED);
+
+ return HOSTAPD_CHAN_ACS;
+}
projects / mech_eap.git / blobdiff