nl80211: Try running without mgmt frame subscription (driver AP SME)

One of supported code paths already allows this scenario. It is used if
driver doesn't report NL80211_ATTR_DEVICE_AP_SME and doesn't support
monitor interface. In such situation:
1) We don't quit if subscribing for WLAN_FC_STYPE_PROBE_REQ fails
2) We don't try subscribing for WLAN_FC_STYPE_ACTION
3) We fallback to AP SME mode after failing to create monitor interface
4) We don't quit if subscribing for WLAN_FC_STYPE_PROBE_REQ fails
Above scenario is used, e.g., with brcmfmac. As you can see - thanks to
events provided by cfg80211 - it's not really required to receive Probe
Request or action frames.

However, the previous implementation did not allow using hostapd with
drivers that:
1) Report NL80211_ATTR_DEVICE_AP_SME
2) Don't support subscribing for PROBE_REQ and/or ACTION frames
In case of using such a driver hostapd will cancel setup after failing
to subscribe for WLAN_FC_STYPE_ACTION. I noticed it after setting flag
WIPHY_FLAG_HAVE_AP_SME in brcmfmac driver for my experiments.

This patch allows working with such drivers with just a small warning
printed as debug message.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 7e8d579..db7dafe 100644 (file)
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -4302,7 +4302,8 @@ static int nl80211_setup_ap(struct i802_bss *bss)
 
        if (drv->device_ap_sme && !drv->use_monitor)
                if (nl80211_mgmt_subscribe_ap_dev_sme(bss))
-                       return -1;
+                       wpa_printf(MSG_DEBUG,
+                                  "nl80211: Failed to subscribe for mgmt frames from SME driver - trying to run without it");
 
        if (!drv->device_ap_sme && drv->use_monitor &&
            nl80211_create_monitor_interface(drv) &&