DFS: Handle pre-CAC expired event

As FCC DFS requirement does not explicitly mention about the validity of
the (pre-)CAC when channel is switched, it is safe to assume that the
pre-CAC result will not be valid once the CAC completed channel is
switched or radar detection is not active on the (CAC completed) channel
within a time period which is allowed (10 seconds - channel switch time)
as per FCC DFS requirement.

Use the new driver event to allow the driver to notify expiry of the CAC
result on a channel. Move the DFS state of the channel to 'usable' when
processing pre-CAC expired event.  This means any future operation on
that channel will require a new CAC to be completed. This event is
applicable only when DFS is not offloaded to the kernel driver.

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qti.qualcomm.com>

src/ap/dfs.c

@@ -1,7 +1,7 @@
 /*
  * DFS - Dynamic Frequency Selection
  * Copyright (c) 2002-2013, Jouni Malinen <j@w1.fi>
- * Copyright (c) 2013-2015, Qualcomm Atheros, Inc.
+ * Copyright (c) 2013-2017, Qualcomm Atheros, Inc.
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -806,6 +806,25 @@ int hostapd_dfs_complete_cac(struct hostapd_iface *iface, int success, int freq,
 }
 
 
+int hostapd_dfs_pre_cac_expired(struct hostapd_iface *iface, int freq,
+				int ht_enabled, int chan_offset, int chan_width,
+				int cf1, int cf2)
+{
+	wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, DFS_EVENT_PRE_CAC_EXPIRED
+		"freq=%d ht_enabled=%d chan_offset=%d chan_width=%d cf1=%d cf2=%d",
+		freq, ht_enabled, chan_offset, chan_width, cf1, cf2);
+
+	/* Proceed only if DFS is not offloaded to the driver */
+	if (iface->drv_flags & WPA_DRIVER_FLAGS_DFS_OFFLOAD)
+		return 0;
+
+	set_dfs_state(iface, freq, ht_enabled, chan_offset, chan_width,
+		      cf1, cf2, HOSTAPD_CHAN_DFS_USABLE);
+
+	return 0;
+}
+
+
 static int hostapd_dfs_start_channel_switch_cac(struct hostapd_iface *iface)
 {
 	struct hostapd_channel_data *channel;

src/ap/dfs.h

@@ -1,7 +1,7 @@
 /*
  * DFS - Dynamic Frequency Selection
  * Copyright (c) 2002-2013, Jouni Malinen <j@w1.fi>
- * Copyright (c) 2013, Qualcomm Atheros, Inc.
+ * Copyright (c) 2013-2017, Qualcomm Atheros, Inc.
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -14,6 +14,9 @@ int hostapd_handle_dfs(struct hostapd_iface *iface);
 int hostapd_dfs_complete_cac(struct hostapd_iface *iface, int success, int freq,
 			     int ht_enabled, int chan_offset, int chan_width,
 			     int cf1, int cf2);
+int hostapd_dfs_pre_cac_expired(struct hostapd_iface *iface, int freq,
+				int ht_enabled, int chan_offset, int chan_width,
+				int cf1, int cf2);
 int hostapd_dfs_radar_detected(struct hostapd_iface *iface, int freq,
 			       int ht_enabled,
 			       int chan_offset, int chan_width,

src/ap/drv_callbacks.c

@@ -1121,6 +1121,16 @@ static void hostapd_event_dfs_radar_detected(struct hostapd_data *hapd,
 }
 
 
+static void hostapd_event_dfs_pre_cac_expired(struct hostapd_data *hapd,
+					      struct dfs_event *radar)
+{
+	wpa_printf(MSG_DEBUG, "DFS Pre-CAC expired on %d MHz", radar->freq);
+	hostapd_dfs_pre_cac_expired(hapd->iface, radar->freq, radar->ht_enabled,
+				    radar->chan_offset, radar->chan_width,
+				    radar->cf1, radar->cf2);
+}
+
+
 static void hostapd_event_dfs_cac_finished(struct hostapd_data *hapd,
 					   struct dfs_event *radar)
 {
@@ -1313,6 +1323,11 @@ void wpa_supplicant_event(void *ctx, enum wpa_event_type event,
 			break;
 		hostapd_event_dfs_radar_detected(hapd, &data->dfs_event);
 		break;
+	case EVENT_DFS_PRE_CAC_EXPIRED:
+		if (!data)
+			break;
+		hostapd_event_dfs_pre_cac_expired(hapd, &data->dfs_event);
+		break;
 	case EVENT_DFS_CAC_FINISHED:
 		if (!data)
 			break;

src/common/wpa_ctrl.h

@@ -275,6 +275,7 @@ extern "C" {
 #define DFS_EVENT_CAC_START "DFS-CAC-START "
 #define DFS_EVENT_CAC_COMPLETED "DFS-CAC-COMPLETED "
 #define DFS_EVENT_NOP_FINISHED "DFS-NOP-FINISHED "
+#define DFS_EVENT_PRE_CAC_EXPIRED "DFS-PRE-CAC-EXPIRED "
 
 #define AP_CSA_FINISHED "AP-CSA-FINISHED "