DFS: Fix HT40/VHT calculation

Decouple HT/VHT offset/center-freq calculations from channel lookup.
This will be necessary for further improvements on the DFS codebase.

Signed-hostap: Michal Kazior <michal.kazior@tieto.com>

diff --git a/src/ap/dfs.c b/src/ap/dfs.c
index a30861fa8f6ff0b53eabc899e212867c6be4dcd7..6a16306c5c825d4fb507df3a31ef78e89fb50866 100644 (file)
--- a/src/ap/dfs.c
+++ b/src/ap/dfs.c
@@ -94,6 +94,13 @@ static int dfs_is_chan_allowed(struct hostapd_channel_data *chan, int n_chans)
 }
 
 
+/*
+ * The function assumes HT40+ operation.
+ * Make sure to adjust the following variables after calling this:
+ *  - hapd->secondary_channel
+ *  - hapd->vht_oper_centr_freq_seg0_idx
+ *  - hapd->vht_oper_centr_freq_seg1_idx
+ */
 static int dfs_find_channel(struct hostapd_data *hapd,
                            struct hostapd_channel_data **ret_chan,
                            int idx)
@@ -126,9 +133,6 @@ static int dfs_find_channel(struct hostapd_data *hapd,
                        }
                        if (j != n_chans)
                                continue;
-
-                       /* Set HT40+ */
-                       hapd->iconf->secondary_channel = 1;
                }
 
                if (ret_chan && idx == channel_idx) {
@@ -144,7 +148,9 @@ static int dfs_find_channel(struct hostapd_data *hapd,
 
 
 static void dfs_adjust_vht_center_freq(struct hostapd_data *hapd,
-                                      struct hostapd_channel_data *chan)
+                                      struct hostapd_channel_data *chan,
+                                      u8 *vht_oper_centr_freq_seg0_idx,
+                                      u8 *vht_oper_centr_freq_seg1_idx)
 {
        if (!hapd->iconf->ieee80211ac)
                return;
@@ -152,31 +158,31 @@ static void dfs_adjust_vht_center_freq(struct hostapd_data *hapd,
        if (!chan)
                return;
 
+       *vht_oper_centr_freq_seg1_idx = 0;
+
        switch (hapd->iconf->vht_oper_chwidth) {
        case VHT_CHANWIDTH_USE_HT:
                if (hapd->iconf->secondary_channel == 1)
-                       hapd->iconf->vht_oper_centr_freq_seg0_idx =
-                               chan->chan + 2;
+                       *vht_oper_centr_freq_seg0_idx = chan->chan + 2;
                else if (hapd->iconf->secondary_channel == -1)
-                       hapd->iconf->vht_oper_centr_freq_seg0_idx =
-                               chan->chan - 2;
+                       *vht_oper_centr_freq_seg0_idx = chan->chan - 2;
                else
-                       hapd->iconf->vht_oper_centr_freq_seg0_idx = chan->chan;
+                       *vht_oper_centr_freq_seg0_idx = chan->chan;
                break;
        case VHT_CHANWIDTH_80MHZ:
-               hapd->iconf->vht_oper_centr_freq_seg0_idx = chan->chan + 6;
+               *vht_oper_centr_freq_seg0_idx = chan->chan + 6;
                break;
        case VHT_CHANWIDTH_160MHZ:
-               hapd->iconf->vht_oper_centr_freq_seg0_idx =
-                                               chan->chan + 14;
+               *vht_oper_centr_freq_seg0_idx = chan->chan + 14;
                break;
        default:
                wpa_printf(MSG_INFO, "DFS only VHT20/40/80/160 is supported now");
                break;
        }
 
-       wpa_printf(MSG_DEBUG, "DFS adjusting VHT center frequency: %d",
-                  hapd->iconf->vht_oper_centr_freq_seg0_idx);
+       wpa_printf(MSG_DEBUG, "DFS adjusting VHT center frequency: %d, %d",
+                  *vht_oper_centr_freq_seg0_idx,
+                  *vht_oper_centr_freq_seg1_idx);
 }
 
 
@@ -295,12 +301,16 @@ static int dfs_check_chans_unavailable(struct hostapd_data *hapd,
 }
 
 
-static struct hostapd_channel_data * dfs_get_valid_channel(
-       struct hostapd_data *hapd)
+static struct hostapd_channel_data *
+dfs_get_valid_channel(struct hostapd_data *hapd,
+                     int *secondary_channel,
+                     u8 *vht_oper_centr_freq_seg0_idx,
+                     u8 *vht_oper_centr_freq_seg1_idx)
 {
        struct hostapd_hw_modes *mode;
        struct hostapd_channel_data *chan = NULL;
-       int channel_idx, new_channel_idx;
+       int num_available_chandefs;
+       int chan_idx;
        u32 _rand;
 
        wpa_printf(MSG_DEBUG, "DFS: Selecting random channel");
@@ -312,16 +322,24 @@ static struct hostapd_channel_data * dfs_get_valid_channel(
        if (mode->mode != HOSTAPD_MODE_IEEE80211A)
                return NULL;
 
-       /* get random available channel */
-       channel_idx = dfs_find_channel(hapd, NULL, 0);
-       if (channel_idx > 0) {
-               os_get_random((u8 *) &_rand, sizeof(_rand));
-               new_channel_idx = _rand % channel_idx;
-               dfs_find_channel(hapd, &chan, new_channel_idx);
-       }
+       /* Get the count first */
+       num_available_chandefs = dfs_find_channel(hapd, NULL, 0);
+       if (num_available_chandefs == 0)
+               return NULL;
 
-       /* VHT */
-       dfs_adjust_vht_center_freq(hapd, chan);
+       os_get_random((u8 *) &_rand, sizeof(_rand));
+       chan_idx = _rand % num_available_chandefs;
+       dfs_find_channel(hapd, &chan, chan_idx);
+
+       /* dfs_find_channel() calculations assume HT40+ */
+       if (hapd->iconf->secondary_channel)
+               *secondary_channel = 1;
+       else
+               *secondary_channel = 0;
+
+       dfs_adjust_vht_center_freq(hapd, chan,
+                                  vht_oper_centr_freq_seg0_idx,
+                                  vht_oper_centr_freq_seg1_idx);
 
        return chan;
 }
@@ -513,13 +531,20 @@ int hostapd_handle_dfs(struct hostapd_data *hapd)
                wpa_printf(MSG_DEBUG, "DFS %d chans unavailable - choose other channel: %s",
                           res, res ? "yes": "no");
                if (res) {
-                       channel = dfs_get_valid_channel(hapd);
+                       int sec;
+                       u8 cf1, cf2;
+
+                       channel = dfs_get_valid_channel(hapd, &sec, &cf1, &cf2);
                        if (!channel) {
                                wpa_printf(MSG_ERROR, "could not get valid channel");
                                return -1;
                        }
-                       hapd->iconf->channel = channel->chan;
+
                        hapd->iface->freq = channel->freq;
+                       hapd->iconf->channel = channel->chan;
+                       hapd->iconf->secondary_channel = sec;
+                       hapd->iconf->vht_oper_centr_freq_seg0_idx = cf1;
+                       hapd->iconf->vht_oper_centr_freq_seg1_idx = cf2;
                }
        } while (res);
 
@@ -563,13 +588,24 @@ static int hostapd_dfs_start_channel_switch(struct hostapd_data *hapd)
 {
        struct hostapd_channel_data *channel;
        int err = 1;
+       int secondary_channel;
+       u8 vht_oper_centr_freq_seg0_idx;
+       u8 vht_oper_centr_freq_seg1_idx;
 
        wpa_printf(MSG_DEBUG, "%s called", __func__);
-       channel = dfs_get_valid_channel(hapd);
+       channel = dfs_get_valid_channel(hapd, &secondary_channel,
+                                       &vht_oper_centr_freq_seg0_idx,
+                                       &vht_oper_centr_freq_seg1_idx);
        if (channel) {
                hapd->iconf->channel = channel->chan;
-               hapd->iface->freq = channel->freq;
+               hapd->iconf->secondary_channel = secondary_channel;
+               hapd->iconf->vht_oper_centr_freq_seg0_idx =
+                                       vht_oper_centr_freq_seg0_idx;
+               hapd->iconf->vht_oper_centr_freq_seg1_idx =
+                                       vht_oper_centr_freq_seg1_idx;
                err = 0;
+       } else {
+               wpa_printf(MSG_ERROR, "No valid channel available");
        }
 
        if (!hapd->cac_started) {