ACS: Add supported channel bandwidth checking

While doing automatic channel selection we need to take into account
supported bandwidth for each channel provided via nl80211. Without this
modification hostapd might select an unsupported channel which would
fail during AP startup.

Signed-off-by: Dmitry Lebed <dlebed@quantenna.com>

diff --git a/src/ap/acs.c b/src/ap/acs.c
index 129ee46ec253ccb9775cb9d188f3a206dabee743..3b4507575328a842f4307db32fdc7769b10c47a7 100644 (file)
--- a/src/ap/acs.c
+++ b/src/ap/acs.c
@@ -13,6 +13,7 @@
 #include "utils/common.h"
 #include "utils/list.h"
 #include "common/ieee802_11_defs.h"
+#include "common/hw_features_common.h"
 #include "common/wpa_ctrl.h"
 #include "drivers/driver.h"
 #include "hostapd.h"
@@ -578,6 +579,7 @@ acs_find_ideal_chan(struct hostapd_iface *iface)
        long double factor, ideal_factor = 0;
        int i, j;
        int n_chans = 1;
+       u32 bw;
        unsigned int k;
 
        /* TODO: HT40- support */
@@ -603,10 +605,12 @@ acs_find_ideal_chan(struct hostapd_iface *iface)
                }
        }
 
+       bw = num_chan_to_bw(n_chans);
+
        /* TODO: VHT80+80. Update acs_adjust_vht_center_freq() too. */
 
-       wpa_printf(MSG_DEBUG, "ACS: Survey analysis for selected bandwidth %d MHz",
-                  n_chans * 20);
+       wpa_printf(MSG_DEBUG,
+                  "ACS: Survey analysis for selected bandwidth %d MHz", bw);
 
        for (i = 0; i < iface->current_mode->num_channels; i++) {
                double total_weight;
@@ -614,12 +618,23 @@ acs_find_ideal_chan(struct hostapd_iface *iface)
 
                chan = &iface->current_mode->channels[i];
 
-               if (chan->flag & HOSTAPD_CHAN_DISABLED)
+               /* Since in the current ACS implementation the first channel is
+                * always a primary channel, skip channels not available as
+                * primary until more sophisticated channel selection is
+                * implemented. */
+               if (!chan_pri_allowed(chan))
                        continue;
 
                if (!is_in_chanlist(iface, chan))
                        continue;
 
+               if (!chan_bw_allowed(chan, bw, 1, 1)) {
+                       wpa_printf(MSG_DEBUG,
+                                  "ACS: Channel %d: BW %u is not supported",
+                                  chan->chan, bw);
+                       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 &&
@@ -662,6 +677,13 @@ acs_find_ideal_chan(struct hostapd_iface *iface)
                        if (!adj_chan)
                                break;
 
+                       if (!chan_bw_allowed(adj_chan, bw, 1, 0)) {
+                               wpa_printf(MSG_DEBUG,
+                                          "ACS: PRI Channel %d: secondary channel %d BW %u is not supported",
+                                          chan->chan, adj_chan->chan, bw);
+                               break;
+                       }
+
                        if (acs_usable_chan(adj_chan)) {
                                factor += adj_chan->interference_factor;
                                total_weight += 1;