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DFS offload: Use hostapd_is_dfs_required() to check if DFS required

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hostapd_handle_dfs_offload() is the DFS handler for the offloaded case,
in which ieee80211_is_dfs() is used to check if the configured frequency
requires DFS or not.

When the configured channel width is not 20 (e.g., 160),
ieee80211_is_dfs() will not checked adjacent freqs, so it possibly makes
wrong conclusion for whether DFS is required.

hostapd_is_dfs_required() does similar thing with ieee80211_is_dfs()
except it supports checking whether the configured frequency and its
adjacent frequencies require DFS. So hostapd_is_dfs_required() is a more
robust and better option than ieee80211_is_dfs() to check DFS.

The issue is hostapd_is_dfs_required() is for non-offload case due to
the check of the configuration parameter ieee80211h. Add a check for
WPA_DRIVER_FLAGS_DFS_OFFLOAD to make it support the DFS offload case
(i.e., ieee80211h=0) as well.

For example, configuring the AP to start at freq=5240 with channel width
160:
- Existing hostapd checks freq=5240 is non-DFS, hence skip DFS CAC and
  transition to AP-Enabled which volatiles DFS-RADAR detection.

  LOG: "hostapd : hostapd_handle_dfs_offload: freq 5240 MHz does not
        require DFS. Continue channel/AP setup"

- This commit checks freq=5240 and its adjacent freqs are DFS required,
  hence remains in DFS state until DFS CAC completed.

  LOG: "hostapd : hostapd_handle_dfs_offload: freq 5240 MHz requires
        DFS for 4 chans"

Signed-off-by: Hu Wang <huw@codeaurora.org>
This commit is contained in:
Hu Wang 2021-04-27 16:41:13 +08:00 committed by Jouni Malinen
parent e8662e9d44
commit 09fb9b0cb0
1 changed files with 10 additions and 5 deletions
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15
src/ap/dfs.c
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@ -1228,7 +1228,9 @@ int hostapd_is_dfs_required(struct hostapd_iface *iface)
{
int n_chans, n_chans1, start_chan_idx, start_chan_idx1, res;
if (!iface->conf->ieee80211h || !iface->current_mode ||
if ((!(iface->drv_flags & WPA_DRIVER_FLAGS_DFS_OFFLOAD) &&
!iface->conf->ieee80211h) ||
!iface->current_mode ||
iface->current_mode->mode != HOSTAPD_MODE_IEEE80211A)
return 0;
@ -1279,6 +1281,8 @@ int hostapd_dfs_start_cac(struct hostapd_iface *iface, int freq,
*/
int hostapd_handle_dfs_offload(struct hostapd_iface *iface)
{
int dfs_res;
wpa_printf(MSG_DEBUG, "%s: iface->cac_started: %d",
__func__, iface->cac_started);
@ -1294,10 +1298,11 @@ int hostapd_handle_dfs_offload(struct hostapd_iface *iface)
return 1;
}
if (ieee80211_is_dfs(iface->freq, iface->hw_features,
iface->num_hw_features)) {
wpa_printf(MSG_DEBUG, "%s: freq %d MHz requires DFS",
__func__, iface->freq);
dfs_res = hostapd_is_dfs_required(iface);
if (dfs_res > 0) {
wpa_printf(MSG_DEBUG,
"%s: freq %d MHz requires DFS for %d chans",
__func__, iface->freq, dfs_res);
return 0;
}