WNM: Optimize BSS transition management scans

When the list of preferred transition candidates is received, use the
identified channels to optimize the following scan so that no time is
wasted on other channels.

Signed-off-by: Jouni Malinen <j@w1.fi>

wpa_supplicant/wnm_sta.c

@@ -10,6 +10,7 @@
 
 #include "utils/common.h"
 #include "common/ieee802_11_defs.h"
+#include "common/ieee802_11_common.h"
 #include "common/wpa_ctrl.h"
 #include "rsn_supp/wpa.h"
 #include "wpa_supplicant_i.h"
@@ -406,6 +407,12 @@ static void wnm_parse_neighbor_report_elem(struct neighbor_report *rep,
 }
 
 
+static int wnm_nei_get_chan(struct wpa_supplicant *wpa_s, u8 op_class, u8 chan)
+{
+	return ieee80211_chan_to_freq(NULL, op_class, chan);
+}
+
+
 static void wnm_parse_neighbor_report(struct wpa_supplicant *wpa_s,
 				      const u8 *pos, u8 len,
 				      struct neighbor_report *rep)
@@ -442,6 +449,9 @@ static void wnm_parse_neighbor_report(struct wpa_supplicant *wpa_s,
 		left -= elen;
 		pos += elen;
 	}
+
+	rep->freq = wnm_nei_get_chan(wpa_s, rep->regulatory_class,
+				     rep->channel_number);
 }
 
 
@@ -673,12 +683,82 @@ static void wnm_dump_cand_list(struct wpa_supplicant *wpa_s)
 
 		nei = &wpa_s->wnm_neighbor_report_elements[i];
 		wpa_printf(MSG_DEBUG, "%u: " MACSTR
-			   " info=0x%x op_class=%u chan=%u phy=%u pref=%d",
+			   " info=0x%x op_class=%u chan=%u phy=%u pref=%d freq=%d",
 			   i, MAC2STR(nei->bssid), nei->bssid_info,
 			   nei->regulatory_class,
 			   nei->channel_number, nei->phy_type,
-			   nei->preference_present ? nei->preference : -1);
+			   nei->preference_present ? nei->preference : -1,
+			   nei->freq);
+	}
+}
+
+
+static int chan_supported(struct wpa_supplicant *wpa_s, int freq)
+{
+	unsigned int i;
+
+	for (i = 0; i < wpa_s->hw.num_modes; i++) {
+		struct hostapd_hw_modes *mode = &wpa_s->hw.modes[i];
+		int j;
+
+		for (j = 0; j < mode->num_channels; j++) {
+			struct hostapd_channel_data *chan;
+
+			chan = &mode->channels[j];
+			if (chan->freq == freq &&
+			    !(chan->flag & HOSTAPD_CHAN_DISABLED))
+				return 1;
+		}
+	}
+
+	return 0;
+}
+
+
+static void wnm_set_scan_freqs(struct wpa_supplicant *wpa_s)
+{
+	int *freqs;
+	int num_freqs = 0;
+	unsigned int i;
+
+	if (!wpa_s->wnm_neighbor_report_elements)
+		return;
+
+	if (wpa_s->hw.modes == NULL)
+		return;
+
+	os_free(wpa_s->next_scan_freqs);
+	wpa_s->next_scan_freqs = NULL;
+
+	freqs = os_calloc(wpa_s->wnm_num_neighbor_report + 1, sizeof(int));
+	if (freqs == NULL)
+		return;
+
+	for (i = 0; i < wpa_s->wnm_num_neighbor_report; i++) {
+		struct neighbor_report *nei;
+
+		nei = &wpa_s->wnm_neighbor_report_elements[i];
+		if (nei->freq <= 0) {
+			wpa_printf(MSG_DEBUG,
+				   "WNM: Unknown neighbor operating frequency for "
+				   MACSTR " - scan all channels",
+				   MAC2STR(nei->bssid));
+			os_free(freqs);
+			return;
+		}
+		if (chan_supported(wpa_s, nei->freq))
+			add_freq(freqs, &num_freqs, nei->freq);
 	}
+
+	if (num_freqs == 0) {
+		os_free(freqs);
+		return;
+	}
+
+	wpa_printf(MSG_DEBUG,
+		   "WNM: Scan %d frequencies based on transition candidate list",
+		   num_freqs);
+	wpa_s->next_scan_freqs = freqs;
 }
 
 
@@ -794,6 +874,7 @@ static void ieee802_11_rx_bss_trans_mgmt_req(struct wpa_supplicant *wpa_s,
 		wpa_s->wnm_cand_valid_until.usec %= 1000000;
 		os_memcpy(wpa_s->wnm_cand_from_bss, wpa_s->bssid, ETH_ALEN);
 
+		wnm_set_scan_freqs(wpa_s);
 		wpa_supplicant_req_scan(wpa_s, 0, 0);
 	} else if (reply) {
 		enum bss_trans_mgmt_status_code status;

wpa_supplicant/wnm_sta.h

@@ -45,6 +45,7 @@ struct neighbor_report {
 	unsigned int bss_term_present:1;
 	struct measurement_pilot *meas_pilot;
 	struct multiple_bssid *mul_bssid;
+	int freq;
 };
 
 

wpa_supplicant/wpa_supplicant.c

@@ -4402,7 +4402,7 @@ void wpa_supplicant_update_config(struct wpa_supplicant *wpa_s)
 }
 
 
-static void add_freq(int *freqs, int *num_freqs, int freq)
+void add_freq(int *freqs, int *num_freqs, int freq)
 {
 	int i;
 

wpa_supplicant/wpa_supplicant_i.h

@@ -992,6 +992,7 @@ void wpas_request_connection(struct wpa_supplicant *wpa_s);
 int wpas_build_ext_capab(struct wpa_supplicant *wpa_s, u8 *buf, size_t buflen);
 int wpas_update_random_addr(struct wpa_supplicant *wpa_s, int style);
 int wpas_update_random_addr_disassoc(struct wpa_supplicant *wpa_s);
+void add_freq(int *freqs, int *num_freqs, int freq);
 
 /**
  * wpa_supplicant_ctrl_iface_ctrl_rsp_handle - Handle a control response