hostapd: Add AP DFS support

Add DFS structures/events handlers, CAC handling, and radar detection.
By default, after radar is detected or the channel became unavailable, a
random channel will be chosen.

This patches are based on the original work by Boris Presman and
Victor Goldenshtein. Most of the DFS code is moved to a new dfs.c/dfs.h
files.

Cc: Boris Presman <boris.presman@ti.com>
Cc: Victor Goldenshtein <victorg@ti.com>

Signed-hostap: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-hostap: Janusz Dziedzic <janusz.dziedzic@tieto.com>

hostapd/Makefile

@@ -782,6 +782,7 @@ OBJS += ../src/ap/wmm.o
 OBJS += ../src/ap/ap_list.o
 OBJS += ../src/ap/ieee802_11.o
 OBJS += ../src/ap/hw_features.o
+OBJS += ../src/ap/dfs.o
 CFLAGS += -DNEED_AP_MLME
 endif
 ifdef CONFIG_IEEE80211N

src/ap/ap_drv_ops.c

@@ -699,3 +699,30 @@ int hostapd_drv_send_action(struct hostapd_data *hapd, unsigned int freq,
 					 hapd->own_addr, hapd->own_addr, data,
 					 len, 0);
 }
+
+
+int hostapd_start_dfs_cac(struct hostapd_data *hapd, int freq, int flags)
+{
+	if (!hapd->driver || !hapd->driver->start_dfs_cac)
+		return 0;
+
+	if (!(flags & HOSTAPD_CHAN_RADAR)) {
+		wpa_printf(MSG_ERROR, "Can't start DFS_CAC, the channel %u is "
+			   "not DFS channel", hapd->iconf->channel);
+		return -1;
+	}
+
+	if (!hapd->iface->conf->ieee80211h) {
+		wpa_printf(MSG_ERROR, "Can't start DFS CAC, DFS functionality "
+			   "is not enabled");
+		return -1;
+	}
+
+	if (hapd->iface->conf->secondary_channel) {
+		wpa_printf(MSG_ERROR, "Can't start DFS CAC, DFS functionality "
+			   "on HT40 is not supported");
+		return -1;
+	}
+
+	return hapd->driver->start_dfs_cac(hapd->drv_priv, freq);
+}

src/ap/ap_drv_ops.h

@@ -101,6 +101,7 @@ int hostapd_sta_assoc(struct hostapd_data *hapd, const u8 *addr,
 		      int reassoc, u16 status, const u8 *ie, size_t len);
 int hostapd_add_tspec(struct hostapd_data *hapd, const u8 *addr,
 		      u8 *tspec_ie, size_t tspec_ielen);
+int hostapd_start_dfs_cac(struct hostapd_data *hapd, int freq, int flags);
 
 
 #include "drivers/driver.h"

src/ap/dfs.c

@@ -0,0 +1,207 @@
+/*
+ * DFS - Dynamic Frequency Selection
+ * Copyright (c) 2002-2013, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "utils/includes.h"
+
+#include "utils/common.h"
+#include "common/ieee802_11_defs.h"
+#include "hostapd.h"
+#include "hw_features.h"
+#include "ap_drv_ops.h"
+#include "drivers/driver.h"
+#include "dfs.h"
+
+
+static int hostapd_dfs_find_channel(struct hostapd_data *hapd,
+				    struct hostapd_channel_data **ret_chan,
+				    int idx)
+{
+	struct hostapd_hw_modes *mode;
+	struct hostapd_channel_data *chan;
+	int i, channel_idx = 0;
+
+	mode = hapd->iface->current_mode;
+
+	for (i = 0; i < mode->num_channels; i++) {
+		chan = &mode->channels[i];
+
+		if (chan->flag & HOSTAPD_CHAN_DISABLED)
+			continue;
+
+		if (chan->flag & HOSTAPD_CHAN_RADAR &&
+		    chan->flag & HOSTAPD_CHAN_DFS_UNAVAILABLE)
+			continue;
+
+		if (ret_chan && idx == channel_idx) {
+			wpa_printf(MSG_DEBUG, "Selected ch. #%d", chan->chan);
+			*ret_chan = chan;
+			return idx;
+		}
+		channel_idx++;
+	}
+	return channel_idx;
+}
+
+
+struct hostapd_channel_data * hostapd_dfs_get_valid_channel(
+	struct hostapd_data *hapd)
+{
+	struct hostapd_hw_modes *mode;
+	struct hostapd_channel_data *chan = NULL;
+	int channel_idx, new_channel_idx;
+	u32 _rand;
+
+	wpa_printf(MSG_DEBUG, "DFS: Selecting random channel");
+
+	if (hapd->iface->current_mode == NULL)
+		return NULL;
+
+	mode = hapd->iface->current_mode;
+	if (mode->mode != HOSTAPD_MODE_IEEE80211A)
+		return NULL;
+
+	/* get random available channel */
+	channel_idx = hostapd_dfs_find_channel(hapd, NULL, 0);
+	if (channel_idx > 0) {
+		os_get_random((u8 *) &_rand, sizeof(_rand));
+		new_channel_idx = _rand % channel_idx;
+		hostapd_dfs_find_channel(hapd, &chan, new_channel_idx);
+	}
+
+	return chan;
+}
+
+
+int ieee802_11_set_dfs_state(struct hostapd_data *hapd, int freq, u32 state)
+{
+	struct hostapd_hw_modes *mode;
+	struct hostapd_channel_data *chan = NULL;
+	int i;
+
+	mode = hapd->iface->current_mode;
+	if (mode == NULL)
+		return 0;
+
+	if (mode->mode != HOSTAPD_MODE_IEEE80211A) {
+		wpa_printf(MSG_WARNING, "current_mode != IEEE80211A");
+		return 0;
+	}
+
+	for (i = 0; i < hapd->iface->current_mode->num_channels; i++) {
+		chan = &hapd->iface->current_mode->channels[i];
+		if (chan->freq == freq) {
+			if (chan->flag & HOSTAPD_CHAN_RADAR) {
+				chan->flag &= ~HOSTAPD_CHAN_DFS_MASK;
+				chan->flag |= state;
+				return 1; /* Channel found */
+			}
+		}
+	}
+	wpa_printf(MSG_WARNING, "Can't set DFS state for freq %d MHz", freq);
+	return 0;
+}
+
+
+/*
+ * Main DFS handler
+ * 1 - continue channel/ap setup
+ * 0 - channel/ap setup will be continued after CAC
+ * -1 - hit critical error
+ */
+int hostapd_handle_dfs(struct hostapd_data *hapd)
+{
+	int flags;
+	struct hostapd_channel_data *channel;
+
+	/* Handle DFS channel */
+check_dfs_chan_again:
+	flags = hostapd_hw_get_channel_flag(hapd, hapd->iconf->channel);
+	if (flags & HOSTAPD_CHAN_RADAR) {
+		switch (flags & HOSTAPD_CHAN_DFS_MASK) {
+		case HOSTAPD_CHAN_DFS_USABLE:
+			wpa_printf(MSG_DEBUG, "DFS start CAC on %d MHz",
+				   hapd->iface->freq);
+			if (hostapd_start_dfs_cac(hapd,
+						  hapd->iface->freq,
+						  flags)) {
+				wpa_printf(MSG_DEBUG, "DFS start_dfs_cac() failed");
+				return -1;
+			}
+			/* Continue initialisation after CAC */
+			return 0;
+		case HOSTAPD_CHAN_DFS_UNAVAILABLE:
+			wpa_printf(MSG_DEBUG, "HOSTAPD_CHAN_DFS_UNAVAILABLE, get new chan");
+			/* find other channel here */
+			channel = hostapd_dfs_get_valid_channel(hapd);
+			if (!channel) {
+				wpa_printf(MSG_ERROR, "could not get valid channel");
+				return -1;
+			}
+			hapd->iconf->channel = channel->chan;
+			hapd->iface->freq = channel->freq;
+			goto check_dfs_chan_again;
+		case HOSTAPD_CHAN_DFS_AVAILABLE:
+			/* We don't need CAC here */
+			wpa_printf(MSG_DEBUG, "HOSTAPD_CHAN_DFS_AVAILABLE, skip CAC");
+			break;
+		default:
+			break;
+		}
+	}
+
+	return 1;
+}
+
+
+int ieee802_11_complete_cac(struct hostapd_data *hapd, int success, int freq)
+{
+	struct hostapd_channel_data *channel;
+	int err = 1;
+
+	if (success) {
+		/* Complete iface/ap configuration */
+		ieee802_11_set_dfs_state(hapd, freq,
+					 HOSTAPD_CHAN_DFS_AVAILABLE);
+		hostapd_setup_interface_complete(hapd->iface, 0);
+	} else {
+		/* Switch to new channel */
+		ieee802_11_set_dfs_state(hapd, freq,
+					 HOSTAPD_CHAN_DFS_UNAVAILABLE);
+		channel = hostapd_dfs_get_valid_channel(hapd);
+		if (channel) {
+			hapd->iconf->channel = channel->chan;
+			hapd->iface->freq = channel->freq;
+			err = 0;
+		} else
+			wpa_printf(MSG_ERROR, "No valid channel available");
+
+		hostapd_setup_interface_complete(hapd->iface, err);
+	}
+
+	return 0;
+}
+
+
+int ieee802_11_start_channel_switch(struct hostapd_data *hapd)
+{
+	struct hostapd_channel_data *channel;
+	int err = 1;
+
+	wpa_printf(MSG_DEBUG, "%s called", __func__);
+	channel = hostapd_dfs_get_valid_channel(hapd);
+	if (channel) {
+		hapd->iconf->channel = channel->chan;
+		hapd->iface->freq = channel->freq;
+		err = 0;
+	}
+
+	hapd->driver->stop_ap(hapd->drv_priv);
+
+	hostapd_setup_interface_complete(hapd->iface, err);
+	return 0;
+}

src/ap/dfs.h

@@ -0,0 +1,18 @@
+/*
+ * DFS - Dynamic Frequency Selection
+ * Copyright (c) 2002-2013, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+#ifndef DFS_H
+#define DFS_H
+
+struct hostapd_channel_data * hostapd_dfs_get_valid_channel(
+	struct hostapd_data *hapd);
+int ieee802_11_complete_cac(struct hostapd_data *hapd, int success, int freq);
+int ieee802_11_set_dfs_state(struct hostapd_data *hapd, int freq, u32 state);
+int ieee802_11_start_channel_switch(struct hostapd_data *hapd);
+int hostapd_handle_dfs(struct hostapd_data *hapd);
+
+#endif /* DFS_H */

src/ap/drv_callbacks.c

@@ -29,6 +29,7 @@
 #include "ap_drv_ops.h"
 #include "ap_config.h"
 #include "hw_features.h"
+#include "dfs.h"
 
 
 int hostapd_notif_assoc(struct hostapd_data *hapd, const u8 *addr,
@@ -785,6 +786,61 @@ static void hostapd_event_get_survey(struct hostapd_data *hapd,
 }
 
 
+#ifdef NEED_AP_MLME
+
+static void hostapd_event_dfs_radar_detected(struct hostapd_data *hapd,
+					     struct dfs_event *radar)
+{
+	int res;
+
+	wpa_printf(MSG_DEBUG, "DFS radar detected on %d MHz", radar->freq);
+
+	if (!hapd->iconf->ieee80211h)
+		return;
+
+	/* mark radar frequency as invalid */
+	res = ieee802_11_set_dfs_state(hapd, radar->freq,
+				       HOSTAPD_CHAN_DFS_UNAVAILABLE);
+
+	/* other frequency, just mark it and return. */
+	if (hapd->iface->freq != radar->freq)
+		return;
+
+	/* we are working on non-DFS channel - skip event */
+	if (res == 0)
+		return;
+
+	/* radar detected while operating, switch the channel. */
+	ieee802_11_start_channel_switch(hapd);
+}
+
+
+static void hostapd_event_dfs_cac_finished(struct hostapd_data *hapd,
+					   struct dfs_event *radar)
+{
+	wpa_printf(MSG_DEBUG, "DFS CAC finished on %d MHz", radar->freq);
+	ieee802_11_complete_cac(hapd, 1, radar->freq);
+}
+
+
+static void hostapd_event_dfs_cac_aborted(struct hostapd_data *hapd,
+					  struct dfs_event *radar)
+{
+	wpa_printf(MSG_DEBUG, "DFS CAC aborted on %d MHz", radar->freq);
+	ieee802_11_complete_cac(hapd, 0, radar->freq);
+}
+
+
+static void hostapd_event_dfs_nop_finished(struct hostapd_data *hapd,
+					   struct dfs_event *radar)
+{
+	wpa_printf(MSG_DEBUG, "DFS NOP finished on %d MHz", radar->freq);
+	ieee802_11_set_dfs_state(hapd, radar->freq, HOSTAPD_CHAN_DFS_USABLE);
+}
+
+#endif /* NEED_AP_MLME */
+
+
 void wpa_supplicant_event(void *ctx, enum wpa_event_type event,
 			  union wpa_event_data *data)
 {
@@ -929,6 +985,34 @@ void wpa_supplicant_event(void *ctx, enum wpa_event_type event,
 	case EVENT_SURVEY:
 		hostapd_event_get_survey(hapd, &data->survey_results);
 		break;
+#ifdef NEED_AP_MLME
+	case EVENT_DFS_RADAR_DETECTED:
+		if (!data)
+			break;
+		hostapd_event_dfs_radar_detected(hapd, &data->dfs_event);
+		break;
+	case EVENT_DFS_CAC_FINISHED:
+		if (!data)
+			break;
+		hostapd_event_dfs_cac_finished(hapd, &data->dfs_event);
+		break;
+	case EVENT_DFS_CAC_ABORTED:
+		if (!data)
+			break;
+		hostapd_event_dfs_cac_aborted(hapd, &data->dfs_event);
+		break;
+	case EVENT_DFS_NOP_FINISHED:
+		if (!data)
+			break;
+		hostapd_event_dfs_nop_finished(hapd, &data->dfs_event);
+		break;
+	case EVENT_CHANNEL_LIST_CHANGED:
+		/* channel list changed (regulatory?), update channel list */
+		/* TODO: check this. hostapd_get_hw_features() initializes
+		 * too much stuff. */
+		/* hostapd_get_hw_features(hapd->iface); */
+		break;
+#endif /* NEED_AP_MLME */
 	default:
 		wpa_printf(MSG_DEBUG, "Unknown event %d", event);
 		break;

src/ap/hostapd.c

@@ -32,6 +32,7 @@
 #include "ap_config.h"
 #include "p2p_hostapd.h"
 #include "gas_serv.h"
+#include "dfs.h"
 
 
 static int hostapd_flush_old_stations(struct hostapd_data *hapd, u16 reason);
@@ -931,6 +932,9 @@ static int setup_interface(struct hostapd_iface *iface)
 				   "be completed in a callback");
 			return 0;
 		}
+
+		if (iface->conf->ieee80211h)
+			wpa_printf(MSG_DEBUG, "DFS support is enabled");
 	}
 	return hostapd_setup_interface_complete(iface, 0);
 }
@@ -950,12 +954,23 @@ int hostapd_setup_interface_complete(struct hostapd_iface *iface, int err)
 
 	wpa_printf(MSG_DEBUG, "Completing interface initialization");
 	if (hapd->iconf->channel) {
+#ifdef NEED_AP_MLME
+		int res;
+#endif /* NEED_AP_MLME */
+
 		iface->freq = hostapd_hw_get_freq(hapd, hapd->iconf->channel);
 		wpa_printf(MSG_DEBUG, "Mode: %s  Channel: %d  "
 			   "Frequency: %d MHz",
 			   hostapd_hw_mode_txt(hapd->iconf->hw_mode),
 			   hapd->iconf->channel, iface->freq);
 
+#ifdef NEED_AP_MLME
+		/* Check DFS */
+		res = hostapd_handle_dfs(hapd);
+		if (res <= 0)
+			return res;
+#endif /* NEED_AP_MLME */
+
 		if (hostapd_set_freq(hapd, hapd->iconf->hw_mode, iface->freq,
 				     hapd->iconf->channel,
 				     hapd->iconf->ieee80211n,

src/ap/hw_features.c

@@ -45,6 +45,36 @@ void hostapd_free_hw_features(struct hostapd_hw_modes *hw_features,
 }
 
 
+#ifndef CONFIG_NO_STDOUT_DEBUG
+static char * dfs_info(struct hostapd_channel_data *chan)
+{
+	static char info[256];
+	char *state;
+
+	switch (chan->flag & HOSTAPD_CHAN_DFS_MASK) {
+	case HOSTAPD_CHAN_DFS_UNKNOWN:
+		state = "unknown";
+		break;
+	case HOSTAPD_CHAN_DFS_USABLE:
+		state = "usable";
+		break;
+	case HOSTAPD_CHAN_DFS_UNAVAILABLE:
+		state = "unavailable";
+		break;
+	case HOSTAPD_CHAN_DFS_AVAILABLE:
+		state = "available";
+		break;
+	default:
+		return "";
+	}
+	os_snprintf(info, sizeof(info), " (DFS state = %s)", state);
+	info[sizeof(info) - 1] = '\0';
+
+	return info;
+}
+#endif /* CONFIG_NO_STDOUT_DEBUG */
+
+
 int hostapd_get_hw_features(struct hostapd_iface *iface)
 {
 	struct hostapd_data *hapd = iface->bss[0];
@@ -71,30 +101,40 @@ int hostapd_get_hw_features(struct hostapd_iface *iface)
 
 	for (i = 0; i < num_modes; i++) {
 		struct hostapd_hw_modes *feature = &modes[i];
+		int dfs_enabled = hapd->iconf->ieee80211h &&
+			(iface->drv_flags & WPA_DRIVER_FLAGS_RADAR);
+
 		/* set flag for channels we can use in current regulatory
 		 * domain */
 		for (j = 0; j < feature->num_channels; j++) {
+			int dfs = 0;
+
 			/*
 			 * Disable all channels that are marked not to allow
-			 * IBSS operation or active scanning. In addition,
-			 * disable all channels that require radar detection,
-			 * since that (in addition to full DFS) is not yet
-			 * supported.
+			 * IBSS operation or active scanning.
+			 * Use radar channels only if the driver supports DFS.
 			 */
-			if (feature->channels[j].flag &
-			    (HOSTAPD_CHAN_NO_IBSS |
-			     HOSTAPD_CHAN_PASSIVE_SCAN |
-			     HOSTAPD_CHAN_RADAR))
+			if ((feature->channels[j].flag &
+			     HOSTAPD_CHAN_RADAR) && dfs_enabled) {
+				dfs = 1;
+			} else if (feature->channels[j].flag &
+				   (HOSTAPD_CHAN_NO_IBSS |
+				    HOSTAPD_CHAN_PASSIVE_SCAN |
+				    HOSTAPD_CHAN_RADAR)) {
 				feature->channels[j].flag |=
 					HOSTAPD_CHAN_DISABLED;
+			}
+
 			if (feature->channels[j].flag & HOSTAPD_CHAN_DISABLED)
 				continue;
+
 			wpa_printf(MSG_MSGDUMP, "Allowed channel: mode=%d "
-				   "chan=%d freq=%d MHz max_tx_power=%d dBm",
+				   "chan=%d freq=%d MHz max_tx_power=%d dBm%s",
 				   feature->mode,
 				   feature->channels[j].chan,
 				   feature->channels[j].freq,
-				   feature->channels[j].max_tx_power);
+				   feature->channels[j].max_tx_power,
+				   dfs ? dfs_info(&feature->channels[j]) : "");
 		}
 	}
 
@@ -849,3 +889,21 @@ int hostapd_hw_get_channel(struct hostapd_data *hapd, int freq)
 
 	return 0;
 }
+
+
+int hostapd_hw_get_channel_flag(struct hostapd_data *hapd, int chan)
+{
+	int i;
+
+	if (!hapd->iface->current_mode)
+		return 0;
+
+	for (i = 0; i < hapd->iface->current_mode->num_channels; i++) {
+		struct hostapd_channel_data *ch =
+			&hapd->iface->current_mode->channels[i];
+		if (ch->chan == chan)
+			return ch->flag;
+	}
+
+	return 0;
+}

src/ap/hw_features.h

@@ -28,6 +28,7 @@ int hostapd_hw_get_channel(struct hostapd_data *hapd, int freq);
 int hostapd_check_ht_capab(struct hostapd_iface *iface);
 int hostapd_prepare_rates(struct hostapd_iface *iface,
 			  struct hostapd_hw_modes *mode);
+int hostapd_hw_get_channel_flag(struct hostapd_data *hapd, int chan);
 #else /* NEED_AP_MLME */
 static inline void
 hostapd_free_hw_features(struct hostapd_hw_modes *hw_features,

wpa_supplicant/Makefile

@@ -772,6 +772,7 @@ OBJS += ../src/ap/wmm.o
 OBJS += ../src/ap/ap_list.o
 OBJS += ../src/ap/ieee802_11.o
 OBJS += ../src/ap/hw_features.o
+OBJS += ../src/ap/dfs.o
 CFLAGS += -DNEED_AP_MLME
 endif
 ifdef CONFIG_WPS