wpa_supplicant: Allow vifs to scan only current channel

If a VIF is already associated, then only scan on the associated
frequency if user requests such. This is a big help when using
lots of virtual stations.

Signed-hostap: Ben Greear <greearb@candelatech.com>
Signed-off-by: Ben Greear <greearb@candelatech.com>

wpa_supplicant/config.c

@@ -2584,6 +2584,7 @@ struct wpa_config * wpa_config_alloc_empty(const char *ctrl_interface,
 	config->bss_expiration_scan_count = DEFAULT_BSS_EXPIRATION_SCAN_COUNT;
 	config->max_num_sta = DEFAULT_MAX_NUM_STA;
 	config->access_network_type = DEFAULT_ACCESS_NETWORK_TYPE;
+	config->scan_cur_freq = DEFAULT_SCAN_CUR_FREQ;
 	config->wmm_ac_params[0] = ac_be;
 	config->wmm_ac_params[1] = ac_bk;
 	config->wmm_ac_params[2] = ac_vi;
@@ -3105,6 +3106,7 @@ static const struct global_parse_data global_fields[] = {
 	{ FUNC(ap_vendor_elements), 0 },
 	{ INT_RANGE(ignore_old_scan_res, 0, 1), 0 },
 	{ FUNC(freq_list), 0 },
+	{ INT(scan_cur_freq), 0 },
 	{ INT(sched_scan_interval), 0 },
 };
 

wpa_supplicant/config.h

@@ -24,6 +24,7 @@
 #define DEFAULT_BSS_EXPIRATION_SCAN_COUNT 2
 #define DEFAULT_MAX_NUM_STA 128
 #define DEFAULT_ACCESS_NETWORK_TYPE 15
+#define DEFAULT_SCAN_CUR_FREQ 0
 
 #include "config_ssid.h"
 #include "wps/wps.h"
@@ -652,6 +653,14 @@ struct wpa_config {
 	 */
 	int *freq_list;
 
+	/**
+	 * scan_cur_freq - Whether to scan only the current channel
+	 *
+	 * If true, attempt to scan only the current channel if any other
+	 * VIFs on this radio are already associated on a particular channel.
+	 */
+	int scan_cur_freq;
+
 	/**
 	 * changed_parameters - Bitmap of changed parameters since last update
 	 */

wpa_supplicant/config_file.c

@@ -1025,6 +1025,8 @@ static void wpa_config_write_global(FILE *f, struct wpa_config *config)
 		}
 		fprintf(f, "\n");
 	}
+	if (config->scan_cur_freq != DEFAULT_SCAN_CUR_FREQ)
+		fprintf(f, "scan_cur_freq=%d\n", config->scan_cur_freq);
 
 	if (config->sched_scan_interval)
 		fprintf(f, "sched_scan_interval=%u\n",

wpa_supplicant/scan.c

@@ -481,6 +481,7 @@ static int non_p2p_network_enabled(struct wpa_supplicant *wpa_s)
 	return 0;
 }
 
+#endif /* CONFIG_P2P */
 
 /*
  * Find the operating frequency of any other virtual interface that is using
@@ -520,8 +521,6 @@ static int shared_vif_oper_freq(struct wpa_supplicant *wpa_s)
 	return 0;
 }
 
-#endif /* CONFIG_P2P */
-
 
 static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
 {
@@ -756,6 +755,19 @@ ssid_list_set:
 		int_array_concat(&params.freqs, wpa_s->conf->freq_list);
 	}
 
+	/* Use current associated channel? */
+	if (wpa_s->conf->scan_cur_freq && !params.freqs) {
+		int freq = shared_vif_oper_freq(wpa_s);
+		if (freq > 0) {
+			wpa_dbg(wpa_s, MSG_DEBUG, "Scan only the current "
+				"operating channel (%d MHz) since "
+				"scan_cur_freq is enabled", freq);
+			params.freqs = os_zalloc(sizeof(int) * 2);
+			if (params.freqs)
+				params.freqs[0] = freq;
+		}
+	}
+
 	params.filter_ssids = wpa_supplicant_build_filter_ssids(
 		wpa_s->conf, &params.num_filter_ssids);
 	if (extra_ie) {

wpa_supplicant/wpa_supplicant.conf

@@ -310,6 +310,10 @@ fast_reauth=1
 # allowing it to update the internal BSS table.
 #ignore_old_scan_res=0
 
+# scan_cur_freq: Whether to scan only the current frequency
+# 0:  Scan all available frequencies. (Default)
+# 1:  Scan current operating frequency if another VIF on the same radio
+#     is already associated.
 
 # Interworking (IEEE 802.11u)