AP MLD: Track radar detection in offloaded DFS case

Add a new flag radar_detected which is used in the following cases
when setting up a link on a DFS channel while the interface is not yet
enabled:
    1. DFS link received CAC start event
    2. If no radar detected, link setup succeeeds after CAC end
       event is received. Else go to 3.
    3. Radar detected on this link -> set radar_detected bit
    4. CAC end received for the current freq -> Do not setup interface
       as radar already detected. Clear radar_detected bit.
    5. The driver sends channel switch event to switch to another channel
        a. Switch to another DFS channel -> go to 1
        b. Switch to non-DFS channel -> proceed to set up interface

Or when receiving a CAC start event when the interface is already set up:
    1. DFS link already set up successfully
    2. Radar detected on this link -> set radar_detected bit
       a. Switch to DFS channel
           a.1. CAC start -> clear radar_detected bit and partner RNR
           a.2. If radar detected, go to 2.
           a.3. CAC end -> clear radar_detected bit
           a.4. Link enabled successfully
       b. Switch to non-DFS channel
           b.1  No op and the driver handles this

Signed-off-by: Chenming Huang <quic_chenhuan@quicinc.com>

src/ap/dfs.c

@@ -14,6 +14,7 @@
 #include "common/hw_features_common.h"
 #include "common/wpa_ctrl.h"
 #include "hostapd.h"
+#include "beacon.h"
 #include "ap_drv_ops.h"
 #include "drivers/driver.h"
 #include "dfs.h"
@@ -1143,14 +1144,23 @@ int hostapd_dfs_complete_cac(struct hostapd_iface *iface, int success, int freq,
 			     int cf1, int cf2)
 {
 	wpa_msg(iface->bss[0]->msg_ctx, MSG_INFO, DFS_EVENT_CAC_COMPLETED
-		"success=%d freq=%d ht_enabled=%d chan_offset=%d chan_width=%d cf1=%d cf2=%d",
+		"success=%d freq=%d ht_enabled=%d chan_offset=%d chan_width=%d cf1=%d cf2=%d radar_detected=%d",
-		success, freq, ht_enabled, chan_offset, chan_width, cf1, cf2);
+		success, freq, ht_enabled, chan_offset, chan_width, cf1, cf2,
+		iface->radar_detected);
 
 	if (success) {
 		/* Complete iface/ap configuration */
 		if (iface->drv_flags & WPA_DRIVER_FLAGS_DFS_OFFLOAD) {
-			/* Complete AP configuration for the first bring up. */
+			/* Complete AP configuration for the first bring up. If
-			if (iface->state != HAPD_IFACE_ENABLED)
+			 * a radar was detected in this channel, interface setup
+			 * will be handled in
+			 * 1. hostapd_event_ch_switch() if switching to a
+			 *    non-DFS channel
+			 * 2. on next CAC complete event if switching to another
+			 *    DFS channel.
+			 */
+			if (iface->state != HAPD_IFACE_ENABLED &&
+			    !iface->radar_detected)
 				hostapd_setup_interface_complete(iface, 0);
 			else
 				iface->cac_started = 0;
@@ -1195,6 +1205,7 @@ int hostapd_dfs_complete_cac(struct hostapd_iface *iface, int success, int freq,
 		hostapd_dfs_update_background_chain(iface);
 	}
 
+	iface->radar_detected = false;
 	return 0;
 }
 
@@ -1438,6 +1449,8 @@ int hostapd_dfs_radar_detected(struct hostapd_iface *iface, int freq,
 		"freq=%d ht_enabled=%d chan_offset=%d chan_width=%d cf1=%d cf2=%d",
 		freq, ht_enabled, chan_offset, chan_width, cf1, cf2);
 
+	iface->radar_detected = true;
+
 	/* Proceed only if DFS is not offloaded to the driver */
 	if (iface->drv_flags & WPA_DRIVER_FLAGS_DFS_OFFLOAD)
 		return 0;
@@ -1531,9 +1544,17 @@ int hostapd_dfs_start_cac(struct hostapd_iface *iface, int freq,
 		iface->radar_background.cac_started = 1;
 	} else {
 		/* This is called when the driver indicates that an offloaded
-		 * DFS has started CAC. */
+		 * DFS has started CAC. radar_detected might be set for previous
+		 * DFS channel. Clear it for this new CAC process. */
 		hostapd_set_state(iface, HAPD_IFACE_DFS);
 		iface->cac_started = 1;
+
+		/* Clear radar_detected in case it is for the previous
+		 * frequency. Also remove disabled link's information in RNR
+		 * element from other links. */
+		iface->radar_detected = false;
+		if (iface->interfaces && iface->interfaces->count > 1)
+			ieee802_11_set_beacons(iface);
 	}
 	/* TODO: How to check CAC time for ETSI weather channels? */
 	iface->dfs_cac_ms = 60000;

src/ap/hostapd.h

@@ -602,6 +602,8 @@ struct hostapd_iface {
 	int *basic_rates;
 	int freq;
 
+	bool radar_detected;
+
 	/* Background radar configuration */
 	struct {
 		int channel;