Add band option (2.4 vs. 5) for filtering scans

[thirdparty/hostap.git] / wpa_supplicant / scan.c

/*
 * WPA Supplicant - Scanning
 * Copyright (c) 2003-2012, 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 "utils/eloop.h"
#include "common/ieee802_11_defs.h"
#include "common/wpa_ctrl.h"
#include "config.h"
#include "wpa_supplicant_i.h"
#include "driver_i.h"
#include "wps_supplicant.h"
#include "p2p_supplicant.h"
#include "p2p/p2p.h"
#include "hs20_supplicant.h"
#include "notify.h"
#include "bss.h"
#include "scan.h"


static void wpa_supplicant_gen_assoc_event(struct wpa_supplicant *wpa_s)
{
        struct wpa_ssid *ssid;
        union wpa_event_data data;

        ssid = wpa_supplicant_get_ssid(wpa_s);
        if (ssid == NULL)
                return;

        if (wpa_s->current_ssid == NULL) {
                wpa_s->current_ssid = ssid;
                if (wpa_s->current_ssid != NULL)
                        wpas_notify_network_changed(wpa_s);
        }
        wpa_supplicant_initiate_eapol(wpa_s);
        wpa_dbg(wpa_s, MSG_DEBUG, "Already associated with a configured "
                "network - generating associated event");
        os_memset(&data, 0, sizeof(data));
        wpa_supplicant_event(wpa_s, EVENT_ASSOC, &data);
}


#ifdef CONFIG_WPS
static int wpas_wps_in_use(struct wpa_supplicant *wpa_s,
                           enum wps_request_type *req_type)
{
        struct wpa_ssid *ssid;
        int wps = 0;

        for (ssid = wpa_s->conf->ssid; ssid; ssid = ssid->next) {
                if (!(ssid->key_mgmt & WPA_KEY_MGMT_WPS))
                        continue;

                wps = 1;
                *req_type = wpas_wps_get_req_type(ssid);
                if (!ssid->eap.phase1)
                        continue;

                if (os_strstr(ssid->eap.phase1, "pbc=1"))
                        return 2;
        }

#ifdef CONFIG_P2P
        if (!wpa_s->global->p2p_disabled && wpa_s->global->p2p &&
            !wpa_s->conf->p2p_disabled) {
                wpa_s->wps->dev.p2p = 1;
                if (!wps) {
                        wps = 1;
                        *req_type = WPS_REQ_ENROLLEE_INFO;
                }
        }
#endif /* CONFIG_P2P */

        return wps;
}
#endif /* CONFIG_WPS */


/**
 * wpa_supplicant_enabled_networks - Check whether there are enabled networks
 * @wpa_s: Pointer to wpa_supplicant data
 * Returns: 0 if no networks are enabled, >0 if networks are enabled
 *
 * This function is used to figure out whether any networks (or Interworking
 * with enabled credentials and auto_interworking) are present in the current
 * configuration.
 */
int wpa_supplicant_enabled_networks(struct wpa_supplicant *wpa_s)
{
        struct wpa_ssid *ssid = wpa_s->conf->ssid;
        int count = 0, disabled = 0;
        while (ssid) {
                if (!wpas_network_disabled(wpa_s, ssid))
                        count++;
                else
                        disabled++;
                ssid = ssid->next;
        }
        if (wpa_s->conf->cred && wpa_s->conf->interworking &&
            wpa_s->conf->auto_interworking)
                count++;
        if (count == 0 && disabled > 0) {
                wpa_dbg(wpa_s, MSG_DEBUG, "No enabled networks (%d disabled "
                        "networks)", disabled);
        }
        return count;
}


static void wpa_supplicant_assoc_try(struct wpa_supplicant *wpa_s,
                                     struct wpa_ssid *ssid)
{
        while (ssid) {
                if (!wpas_network_disabled(wpa_s, ssid))
                        break;
                ssid = ssid->next;
        }

        /* ap_scan=2 mode - try to associate with each SSID. */
        if (ssid == NULL) {
                wpa_dbg(wpa_s, MSG_DEBUG, "wpa_supplicant_assoc_try: Reached "
                        "end of scan list - go back to beginning");
                wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
                wpa_supplicant_req_scan(wpa_s, 0, 0);
                return;
        }
        if (ssid->next) {
                /* Continue from the next SSID on the next attempt. */
                wpa_s->prev_scan_ssid = ssid;
        } else {
                /* Start from the beginning of the SSID list. */
                wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
        }
        wpa_supplicant_associate(wpa_s, NULL, ssid);
}


static int int_array_len(const int *a)
{
        int i;
        for (i = 0; a && a[i]; i++)
                ;
        return i;
}


static void int_array_concat(int **res, const int *a)
{
        int reslen, alen, i;
        int *n;

        reslen = int_array_len(*res);
        alen = int_array_len(a);

        n = os_realloc_array(*res, reslen + alen + 1, sizeof(int));
        if (n == NULL) {
                os_free(*res);
                *res = NULL;
                return;
        }
        for (i = 0; i <= alen; i++)
                n[reslen + i] = a[i];
        *res = n;
}


static int freq_cmp(const void *a, const void *b)
{
        int _a = *(int *) a;
        int _b = *(int *) b;

        if (_a == 0)
                return 1;
        if (_b == 0)
                return -1;
        return _a - _b;
}


static void int_array_sort_unique(int *a)
{
        int alen;
        int i, j;

        if (a == NULL)
                return;

        alen = int_array_len(a);
        qsort(a, alen, sizeof(int), freq_cmp);

        i = 0;
        j = 1;
        while (a[i] && a[j]) {
                if (a[i] == a[j]) {
                        j++;
                        continue;
                }
                a[++i] = a[j++];
        }
        if (a[i])
                i++;
        a[i] = 0;
}


/**
 * wpa_supplicant_trigger_scan - Request driver to start a scan
 * @wpa_s: Pointer to wpa_supplicant data
 * @params: Scan parameters
 * Returns: 0 on success, -1 on failure
 */
int wpa_supplicant_trigger_scan(struct wpa_supplicant *wpa_s,
                                struct wpa_driver_scan_params *params)
{
        int ret;

        wpa_supplicant_notify_scanning(wpa_s, 1);

        ret = wpa_drv_scan(wpa_s, params);
        if (ret) {
                wpa_supplicant_notify_scanning(wpa_s, 0);
                wpas_notify_scan_done(wpa_s, 0);
        } else {
                os_get_time(&wpa_s->scan_trigger_time);
                wpa_s->scan_runs++;
                wpa_s->normal_scans++;
        }

        return ret;
}


static void
wpa_supplicant_delayed_sched_scan_timeout(void *eloop_ctx, void *timeout_ctx)
{
        struct wpa_supplicant *wpa_s = eloop_ctx;

        wpa_dbg(wpa_s, MSG_DEBUG, "Starting delayed sched scan");

        if (wpa_supplicant_req_sched_scan(wpa_s))
                wpa_supplicant_req_scan(wpa_s, 0, 0);
}


static void
wpa_supplicant_sched_scan_timeout(void *eloop_ctx, void *timeout_ctx)
{
        struct wpa_supplicant *wpa_s = eloop_ctx;

        wpa_dbg(wpa_s, MSG_DEBUG, "Sched scan timeout - stopping it");

        wpa_s->sched_scan_timed_out = 1;
        wpa_supplicant_cancel_sched_scan(wpa_s);
}


static int
wpa_supplicant_start_sched_scan(struct wpa_supplicant *wpa_s,
                                struct wpa_driver_scan_params *params,
                                int interval)
{
        int ret;

        wpa_supplicant_notify_scanning(wpa_s, 1);
        ret = wpa_drv_sched_scan(wpa_s, params, interval * 1000);
        if (ret)
                wpa_supplicant_notify_scanning(wpa_s, 0);
        else
                wpa_s->sched_scanning = 1;

        return ret;
}


static int wpa_supplicant_stop_sched_scan(struct wpa_supplicant *wpa_s)
{
        int ret;

        ret = wpa_drv_stop_sched_scan(wpa_s);
        if (ret) {
                wpa_dbg(wpa_s, MSG_DEBUG, "stopping sched_scan failed!");
                /* TODO: what to do if stopping fails? */
                return -1;
        }

        return ret;
}


static struct wpa_driver_scan_filter *
wpa_supplicant_build_filter_ssids(struct wpa_config *conf, size_t *num_ssids)
{
        struct wpa_driver_scan_filter *ssids;
        struct wpa_ssid *ssid;
        size_t count;

        *num_ssids = 0;
        if (!conf->filter_ssids)
                return NULL;

        for (count = 0, ssid = conf->ssid; ssid; ssid = ssid->next) {
                if (ssid->ssid && ssid->ssid_len)
                        count++;
        }
        if (count == 0)
                return NULL;
        ssids = os_zalloc(count * sizeof(struct wpa_driver_scan_filter));
        if (ssids == NULL)
                return NULL;

        for (ssid = conf->ssid; ssid; ssid = ssid->next) {
                if (!ssid->ssid || !ssid->ssid_len)
                        continue;
                os_memcpy(ssids[*num_ssids].ssid, ssid->ssid, ssid->ssid_len);
                ssids[*num_ssids].ssid_len = ssid->ssid_len;
                (*num_ssids)++;
        }

        return ssids;
}


static void wpa_supplicant_optimize_freqs(
        struct wpa_supplicant *wpa_s, struct wpa_driver_scan_params *params)
{
#ifdef CONFIG_P2P
        if (params->freqs == NULL && wpa_s->p2p_in_provisioning &&
            wpa_s->go_params) {
                /* Optimize provisioning state scan based on GO information */
                if (wpa_s->p2p_in_provisioning < 5 &&
                    wpa_s->go_params->freq > 0) {
                        wpa_dbg(wpa_s, MSG_DEBUG, "P2P: Scan only GO "
                                "preferred frequency %d MHz",
                                wpa_s->go_params->freq);
                        params->freqs = os_zalloc(2 * sizeof(int));
                        if (params->freqs)
                                params->freqs[0] = wpa_s->go_params->freq;
                } else if (wpa_s->p2p_in_provisioning < 8 &&
                           wpa_s->go_params->freq_list[0]) {
                        wpa_dbg(wpa_s, MSG_DEBUG, "P2P: Scan only common "
                                "channels");
                        int_array_concat(&params->freqs,
                                         wpa_s->go_params->freq_list);
                        if (params->freqs)
                                int_array_sort_unique(params->freqs);
                }
                wpa_s->p2p_in_provisioning++;
        }
#endif /* CONFIG_P2P */

#ifdef CONFIG_WPS
        if (params->freqs == NULL && wpa_s->after_wps && wpa_s->wps_freq) {
                /*
                 * Optimize post-provisioning scan based on channel used
                 * during provisioning.
                 */
                wpa_dbg(wpa_s, MSG_DEBUG, "WPS: Scan only frequency %u MHz "
                        "that was used during provisioning", wpa_s->wps_freq);
                params->freqs = os_zalloc(2 * sizeof(int));
                if (params->freqs)
                        params->freqs[0] = wpa_s->wps_freq;
                wpa_s->after_wps--;
        }

        if (params->freqs == NULL && wpa_s->known_wps_freq && wpa_s->wps_freq)
        {
                /* Optimize provisioning scan based on already known channel */
                wpa_dbg(wpa_s, MSG_DEBUG, "WPS: Scan only frequency %u MHz",
                        wpa_s->wps_freq);
                params->freqs = os_zalloc(2 * sizeof(int));
                if (params->freqs)
                        params->freqs[0] = wpa_s->wps_freq;
                wpa_s->known_wps_freq = 0; /* only do this once */
        }
#endif /* CONFIG_WPS */
}


#ifdef CONFIG_INTERWORKING
static void wpas_add_interworking_elements(struct wpa_supplicant *wpa_s,
                                           struct wpabuf *buf)
{
        if (wpa_s->conf->interworking == 0)
                return;

        wpabuf_put_u8(buf, WLAN_EID_EXT_CAPAB);
        wpabuf_put_u8(buf, 4);
        wpabuf_put_u8(buf, 0x00);
        wpabuf_put_u8(buf, 0x00);
        wpabuf_put_u8(buf, 0x00);
        wpabuf_put_u8(buf, 0x80); /* Bit 31 - Interworking */

        wpabuf_put_u8(buf, WLAN_EID_INTERWORKING);
        wpabuf_put_u8(buf, is_zero_ether_addr(wpa_s->conf->hessid) ? 1 :
                      1 + ETH_ALEN);
        wpabuf_put_u8(buf, wpa_s->conf->access_network_type);
        /* No Venue Info */
        if (!is_zero_ether_addr(wpa_s->conf->hessid))
                wpabuf_put_data(buf, wpa_s->conf->hessid, ETH_ALEN);
}
#endif /* CONFIG_INTERWORKING */


static struct wpabuf * wpa_supplicant_extra_ies(struct wpa_supplicant *wpa_s)
{
        struct wpabuf *extra_ie = NULL;
#ifdef CONFIG_WPS
        int wps = 0;
        enum wps_request_type req_type = WPS_REQ_ENROLLEE_INFO;
#endif /* CONFIG_WPS */

#ifdef CONFIG_INTERWORKING
        if (wpa_s->conf->interworking &&
            wpabuf_resize(&extra_ie, 100) == 0)
                wpas_add_interworking_elements(wpa_s, extra_ie);
#endif /* CONFIG_INTERWORKING */

#ifdef CONFIG_WPS
        wps = wpas_wps_in_use(wpa_s, &req_type);

        if (wps) {
                struct wpabuf *wps_ie;
                wps_ie = wps_build_probe_req_ie(wps == 2 ? DEV_PW_PUSHBUTTON :
                                                DEV_PW_DEFAULT,
                                                &wpa_s->wps->dev,
                                                wpa_s->wps->uuid, req_type,
                                                0, NULL);
                if (wps_ie) {
                        if (wpabuf_resize(&extra_ie, wpabuf_len(wps_ie)) == 0)
                                wpabuf_put_buf(extra_ie, wps_ie);
                        wpabuf_free(wps_ie);
                }
        }

#ifdef CONFIG_P2P
        if (wps) {
                size_t ielen = p2p_scan_ie_buf_len(wpa_s->global->p2p);
                if (wpabuf_resize(&extra_ie, ielen) == 0)
                        wpas_p2p_scan_ie(wpa_s, extra_ie);
        }
#endif /* CONFIG_P2P */

#endif /* CONFIG_WPS */

#ifdef CONFIG_HS20
        if (wpa_s->conf->hs20 && wpabuf_resize(&extra_ie, 7) == 0)
                wpas_hs20_add_indication(extra_ie);
#endif /* CONFIG_HS20 */

        return extra_ie;
}


#ifdef CONFIG_P2P

/*
 * Check whether there are any enabled networks or credentials that could be
 * used for a non-P2P connection.
 */
static int non_p2p_network_enabled(struct wpa_supplicant *wpa_s)
{
        struct wpa_ssid *ssid;

        for (ssid = wpa_s->conf->ssid; ssid; ssid = ssid->next) {
                if (wpas_network_disabled(wpa_s, ssid))
                        continue;
                if (!ssid->p2p_group)
                        return 1;
        }

        if (wpa_s->conf->cred && wpa_s->conf->interworking &&
            wpa_s->conf->auto_interworking)
                return 1;

        return 0;
}

#endif /* CONFIG_P2P */

/*
 * Find the operating frequency of any other virtual interface that is using
 * the same radio concurrently.
 */
static int shared_vif_oper_freq(struct wpa_supplicant *wpa_s)
{
        const char *rn, *rn2;
        struct wpa_supplicant *ifs;
        u8 bssid[ETH_ALEN];

        if (!wpa_s->driver->get_radio_name)
                return -1;

        rn = wpa_s->driver->get_radio_name(wpa_s->drv_priv);
        if (rn == NULL || rn[0] == '\0')
                return -1;

        for (ifs = wpa_s->global->ifaces; ifs; ifs = ifs->next) {
                if (ifs == wpa_s || !ifs->driver->get_radio_name)
                        continue;

                rn2 = ifs->driver->get_radio_name(ifs->drv_priv);
                if (!rn2 || os_strcmp(rn, rn2) != 0)
                        continue;

                if (ifs->current_ssid == NULL || ifs->assoc_freq == 0)
                        continue;

                if (ifs->current_ssid->mode == WPAS_MODE_AP ||
                    ifs->current_ssid->mode == WPAS_MODE_P2P_GO)
                        return ifs->current_ssid->frequency;
                if (wpa_drv_get_bssid(ifs, bssid) == 0)
                        return ifs->assoc_freq;
        }

        return 0;
}


static struct hostapd_hw_modes * get_mode(struct hostapd_hw_modes *modes,
                                          u16 num_modes,
                                          enum hostapd_hw_mode mode)
{
        u16 i;

        for (i = 0; i < num_modes; i++) {
                if (modes[i].mode == mode)
                        return &modes[i];
        }

        return NULL;
}


static void wpa_setband_scan_freqs_list(struct wpa_supplicant *wpa_s,
                                        enum hostapd_hw_mode band,
                                        struct wpa_driver_scan_params *params)
{
        /* Include only supported channels for the specified band */
        struct hostapd_hw_modes *mode;
        int count, i;

        mode = get_mode(wpa_s->hw.modes, wpa_s->hw.num_modes, band);
        if (mode == NULL) {
                /* No channels supported in this band - use empty list */
                params->freqs = os_zalloc(sizeof(int));
                return;
        }

        params->freqs = os_zalloc((mode->num_channels + 1) * sizeof(int));
        if (params->freqs == NULL)
                return;
        for (count = 0, i = 0; i < mode->num_channels; i++) {
                if (mode->channels[i].flag & HOSTAPD_CHAN_DISABLED)
                        continue;
                params->freqs[count++] = mode->channels[i].freq;
        }
}


static void wpa_setband_scan_freqs(struct wpa_supplicant *wpa_s,
                                   struct wpa_driver_scan_params *params)
{
        if (wpa_s->hw.modes == NULL)
                return; /* unknown what channels the driver supports */
        if (params->freqs)
                return; /* already using a limited channel set */
        if (wpa_s->setband == WPA_SETBAND_5G)
                wpa_setband_scan_freqs_list(wpa_s, HOSTAPD_MODE_IEEE80211A,
                                            params);
        else if (wpa_s->setband == WPA_SETBAND_2G)
                wpa_setband_scan_freqs_list(wpa_s, HOSTAPD_MODE_IEEE80211G,
                                            params);
}


static void wpa_supplicant_scan(void *eloop_ctx, void *timeout_ctx)
{
        struct wpa_supplicant *wpa_s = eloop_ctx;
        struct wpa_ssid *ssid;
        enum scan_req_type scan_req = NORMAL_SCAN_REQ;
        int ret;
        struct wpabuf *extra_ie = NULL;
        struct wpa_driver_scan_params params;
        struct wpa_driver_scan_params *scan_params;
        size_t max_ssids;
        enum wpa_states prev_state;

        if (wpa_s->wpa_state == WPA_INTERFACE_DISABLED) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Skip scan - interface disabled");
                wpas_p2p_continue_after_scan(wpa_s);
                return;
        }

        if (wpa_s->disconnected && wpa_s->scan_req == NORMAL_SCAN_REQ) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Disconnected - do not scan");
                wpa_supplicant_set_state(wpa_s, WPA_DISCONNECTED);
                wpas_p2p_continue_after_scan(wpa_s);
                return;
        }

        if (!wpa_supplicant_enabled_networks(wpa_s) &&
            wpa_s->scan_req == NORMAL_SCAN_REQ) {
                wpa_dbg(wpa_s, MSG_DEBUG, "No enabled networks - do not scan");
                wpa_supplicant_set_state(wpa_s, WPA_INACTIVE);
                wpas_p2p_continue_after_scan(wpa_s);
                return;
        }

        if (wpa_s->conf->ap_scan != 0 &&
            (wpa_s->drv_flags & WPA_DRIVER_FLAGS_WIRED)) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Using wired authentication - "
                        "overriding ap_scan configuration");
                wpa_s->conf->ap_scan = 0;
                wpas_notify_ap_scan_changed(wpa_s);
        }

        if (wpa_s->conf->ap_scan == 0) {
                wpa_supplicant_gen_assoc_event(wpa_s);
                return;
        }

#ifdef CONFIG_P2P
        if (wpas_p2p_in_progress(wpa_s) || wpas_wpa_is_in_progress(wpa_s)) {
                if (wpa_s->sta_scan_pending &&
                    wpas_p2p_in_progress(wpa_s) == 2 &&
                    wpa_s->global->p2p_cb_on_scan_complete) {
                        wpa_dbg(wpa_s, MSG_DEBUG, "Process pending station "
                                "mode scan during P2P search");
                } else {
                        wpa_dbg(wpa_s, MSG_DEBUG, "Delay station mode scan "
                                "while P2P operation is in progress");
                        wpa_s->sta_scan_pending = 1;
                        wpa_supplicant_req_scan(wpa_s, 5, 0);
                        return;
                }
        }
#endif /* CONFIG_P2P */

        if (wpa_s->conf->ap_scan == 2)
                max_ssids = 1;
        else {
                max_ssids = wpa_s->max_scan_ssids;
                if (max_ssids > WPAS_MAX_SCAN_SSIDS)
                        max_ssids = WPAS_MAX_SCAN_SSIDS;
        }

        scan_req = wpa_s->scan_req;
        wpa_s->scan_req = NORMAL_SCAN_REQ;

        os_memset(&params, 0, sizeof(params));

        prev_state = wpa_s->wpa_state;
        if (wpa_s->wpa_state == WPA_DISCONNECTED ||
            wpa_s->wpa_state == WPA_INACTIVE)
                wpa_supplicant_set_state(wpa_s, WPA_SCANNING);

        /*
         * If autoscan has set its own scanning parameters
         */
        if (wpa_s->autoscan_params != NULL) {
                scan_params = wpa_s->autoscan_params;
                goto scan;
        }

        if (scan_req != MANUAL_SCAN_REQ && wpa_s->connect_without_scan) {
                for (ssid = wpa_s->conf->ssid; ssid; ssid = ssid->next) {
                        if (ssid == wpa_s->connect_without_scan)
                                break;
                }
                wpa_s->connect_without_scan = NULL;
                if (ssid) {
                        wpa_printf(MSG_DEBUG, "Start a pre-selected network "
                                   "without scan step");
                        wpa_supplicant_associate(wpa_s, NULL, ssid);
                        return;
                }
        }

#ifdef CONFIG_P2P
        if ((wpa_s->p2p_in_provisioning || wpa_s->show_group_started) &&
            wpa_s->go_params) {
                wpa_printf(MSG_DEBUG, "P2P: Use specific SSID for scan during "
                           "P2P group formation");
                params.ssids[0].ssid = wpa_s->go_params->ssid;
                params.ssids[0].ssid_len = wpa_s->go_params->ssid_len;
                params.num_ssids = 1;
                goto ssid_list_set;
        }
#endif /* CONFIG_P2P */

        /* Find the starting point from which to continue scanning */
        ssid = wpa_s->conf->ssid;
        if (wpa_s->prev_scan_ssid != WILDCARD_SSID_SCAN) {
                while (ssid) {
                        if (ssid == wpa_s->prev_scan_ssid) {
                                ssid = ssid->next;
                                break;
                        }
                        ssid = ssid->next;
                }
        }

        if (scan_req != MANUAL_SCAN_REQ && wpa_s->conf->ap_scan == 2) {
                wpa_s->connect_without_scan = NULL;
                wpa_s->prev_scan_wildcard = 0;
                wpa_supplicant_assoc_try(wpa_s, ssid);
                return;
        } else if (wpa_s->conf->ap_scan == 2) {
                /*
                 * User-initiated scan request in ap_scan == 2; scan with
                 * wildcard SSID.
                 */
                ssid = NULL;
        } else {
                struct wpa_ssid *start = ssid, *tssid;
                int freqs_set = 0;
                if (ssid == NULL && max_ssids > 1)
                        ssid = wpa_s->conf->ssid;
                while (ssid) {
                        if (!wpas_network_disabled(wpa_s, ssid) &&
                            ssid->scan_ssid) {
                                wpa_hexdump_ascii(MSG_DEBUG, "Scan SSID",
                                                  ssid->ssid, ssid->ssid_len);
                                params.ssids[params.num_ssids].ssid =
                                        ssid->ssid;
                                params.ssids[params.num_ssids].ssid_len =
                                        ssid->ssid_len;
                                params.num_ssids++;
                                if (params.num_ssids + 1 >= max_ssids)
                                        break;
                        }
                        ssid = ssid->next;
                        if (ssid == start)
                                break;
                        if (ssid == NULL && max_ssids > 1 &&
                            start != wpa_s->conf->ssid)
                                ssid = wpa_s->conf->ssid;
                }

                for (tssid = wpa_s->conf->ssid; tssid; tssid = tssid->next) {
                        if (wpas_network_disabled(wpa_s, tssid))
                                continue;
                        if ((params.freqs || !freqs_set) && tssid->scan_freq) {
                                int_array_concat(&params.freqs,
                                                 tssid->scan_freq);
                        } else {
                                os_free(params.freqs);
                                params.freqs = NULL;
                        }
                        freqs_set = 1;
                }
                int_array_sort_unique(params.freqs);
        }

        if (ssid && max_ssids == 1) {
                /*
                 * If the driver is limited to 1 SSID at a time interleave
                 * wildcard SSID scans with specific SSID scans to avoid
                 * waiting a long time for a wildcard scan.
                 */
                if (!wpa_s->prev_scan_wildcard) {
                        params.ssids[0].ssid = NULL;
                        params.ssids[0].ssid_len = 0;
                        wpa_s->prev_scan_wildcard = 1;
                        wpa_dbg(wpa_s, MSG_DEBUG, "Starting AP scan for "
                                "wildcard SSID (Interleave with specific)");
                } else {
                        wpa_s->prev_scan_ssid = ssid;
                        wpa_s->prev_scan_wildcard = 0;
                        wpa_dbg(wpa_s, MSG_DEBUG,
                                "Starting AP scan for specific SSID: %s",
                                wpa_ssid_txt(ssid->ssid, ssid->ssid_len));
                }
        } else if (ssid) {
                /* max_ssids > 1 */

                wpa_s->prev_scan_ssid = ssid;
                wpa_dbg(wpa_s, MSG_DEBUG, "Include wildcard SSID in "
                        "the scan request");
                params.num_ssids++;
        } else {
                wpa_s->prev_scan_ssid = WILDCARD_SSID_SCAN;
                params.num_ssids++;
                wpa_dbg(wpa_s, MSG_DEBUG, "Starting AP scan for wildcard "
                        "SSID");
        }
#ifdef CONFIG_P2P
ssid_list_set:
#endif /* CONFIG_P2P */

        wpa_supplicant_optimize_freqs(wpa_s, &params);
        extra_ie = wpa_supplicant_extra_ies(wpa_s);

        if (params.freqs == NULL && wpa_s->next_scan_freqs) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Optimize scan based on previously "
                        "generated frequency list");
                params.freqs = wpa_s->next_scan_freqs;
        } else
                os_free(wpa_s->next_scan_freqs);
        wpa_s->next_scan_freqs = NULL;
        wpa_setband_scan_freqs(wpa_s, &params);

        /* See if user specified frequencies. If so, scan only those. */
        if (wpa_s->conf->freq_list && !params.freqs) {
                wpa_dbg(wpa_s, MSG_DEBUG,
                        "Optimize scan based on conf->freq_list");
                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) {
                params.extra_ies = wpabuf_head(extra_ie);
                params.extra_ies_len = wpabuf_len(extra_ie);
        }

#ifdef CONFIG_P2P
        if (wpa_s->p2p_in_provisioning ||
            (wpa_s->show_group_started && wpa_s->go_params)) {
                /*
                 * The interface may not yet be in P2P mode, so we have to
                 * explicitly request P2P probe to disable CCK rates.
                 */
                params.p2p_probe = 1;
        }
#endif /* CONFIG_P2P */

        scan_params = &params;

scan:
#ifdef CONFIG_P2P
        /*
         * If the driver does not support multi-channel concurrency and a
         * virtual interface that shares the same radio with the wpa_s interface
         * is operating there may not be need to scan other channels apart from
         * the current operating channel on the other virtual interface. Filter
         * out other channels in case we are trying to find a connection for a
         * station interface when we are not configured to prefer station
         * connection and a concurrent operation is already in process.
         */
        if (wpa_s->scan_for_connection && scan_req == NORMAL_SCAN_REQ &&
            !scan_params->freqs && !params.freqs &&
            wpas_is_p2p_prioritized(wpa_s) &&
            !(wpa_s->drv_flags & WPA_DRIVER_FLAGS_MULTI_CHANNEL_CONCURRENT) &&
            wpa_s->p2p_group_interface == NOT_P2P_GROUP_INTERFACE &&
            non_p2p_network_enabled(wpa_s)) {
                int freq = shared_vif_oper_freq(wpa_s);
                if (freq > 0) {
                        wpa_dbg(wpa_s, MSG_DEBUG, "P2P: Scan only the current "
                                "operating channel (%d MHz) since driver does "
                                "not support multi-channel concurrency", freq);
                        params.freqs = os_zalloc(sizeof(int) * 2);
                        if (params.freqs)
                                params.freqs[0] = freq;
                        scan_params->freqs = params.freqs;
                }
        }
#endif /* CONFIG_P2P */

        ret = wpa_supplicant_trigger_scan(wpa_s, scan_params);

        wpabuf_free(extra_ie);
        os_free(params.freqs);
        os_free(params.filter_ssids);

        if (ret) {
                wpa_msg(wpa_s, MSG_WARNING, "Failed to initiate AP scan");
                if (prev_state != wpa_s->wpa_state)
                        wpa_supplicant_set_state(wpa_s, prev_state);
                /* Restore scan_req since we will try to scan again */
                wpa_s->scan_req = scan_req;
                wpa_supplicant_req_scan(wpa_s, 1, 0);
        } else {
                wpa_s->scan_for_connection = 0;
        }
}


void wpa_supplicant_update_scan_int(struct wpa_supplicant *wpa_s, int sec)
{
        struct os_time remaining, new_int;
        int cancelled;

        cancelled = eloop_cancel_timeout_one(wpa_supplicant_scan, wpa_s, NULL,
                                             &remaining);

        new_int.sec = sec;
        new_int.usec = 0;
        if (cancelled && os_time_before(&remaining, &new_int)) {
                new_int.sec = remaining.sec;
                new_int.usec = remaining.usec;
        }

        eloop_register_timeout(new_int.sec, new_int.usec, wpa_supplicant_scan,
                               wpa_s, NULL);
        wpa_s->scan_interval = sec;
}


/**
 * wpa_supplicant_req_scan - Schedule a scan for neighboring access points
 * @wpa_s: Pointer to wpa_supplicant data
 * @sec: Number of seconds after which to scan
 * @usec: Number of microseconds after which to scan
 *
 * This function is used to schedule a scan for neighboring access points after
 * the specified time.
 */
void wpa_supplicant_req_scan(struct wpa_supplicant *wpa_s, int sec, int usec)
{
        /* If there's at least one network that should be specifically scanned
         * then don't cancel the scan and reschedule.  Some drivers do
         * background scanning which generates frequent scan results, and that
         * causes the specific SSID scan to get continually pushed back and
         * never happen, which causes hidden APs to never get probe-scanned.
         */
        if (eloop_is_timeout_registered(wpa_supplicant_scan, wpa_s, NULL) &&
            wpa_s->conf->ap_scan == 1) {
                struct wpa_ssid *ssid = wpa_s->conf->ssid;

                while (ssid) {
                        if (!wpas_network_disabled(wpa_s, ssid) &&
                            ssid->scan_ssid)
                                break;
                        ssid = ssid->next;
                }
                if (ssid) {
                        wpa_dbg(wpa_s, MSG_DEBUG, "Not rescheduling scan to "
                                "ensure that specific SSID scans occur");
                        return;
                }
        }

        wpa_dbg(wpa_s, MSG_DEBUG, "Setting scan request: %d sec %d usec",
                sec, usec);
        eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
        eloop_register_timeout(sec, usec, wpa_supplicant_scan, wpa_s, NULL);
}


/**
 * wpa_supplicant_delayed_sched_scan - Request a delayed scheduled scan
 * @wpa_s: Pointer to wpa_supplicant data
 * @sec: Number of seconds after which to scan
 * @usec: Number of microseconds after which to scan
 * Returns: 0 on success or -1 otherwise
 *
 * This function is used to schedule periodic scans for neighboring
 * access points after the specified time.
 */
int wpa_supplicant_delayed_sched_scan(struct wpa_supplicant *wpa_s,
                                      int sec, int usec)
{
        if (!wpa_s->sched_scan_supported)
                return -1;

        eloop_register_timeout(sec, usec,
                               wpa_supplicant_delayed_sched_scan_timeout,
                               wpa_s, NULL);

        return 0;
}


/**
 * wpa_supplicant_req_sched_scan - Start a periodic scheduled scan
 * @wpa_s: Pointer to wpa_supplicant data
 * Returns: 0 is sched_scan was started or -1 otherwise
 *
 * This function is used to schedule periodic scans for neighboring
 * access points repeating the scan continuously.
 */
int wpa_supplicant_req_sched_scan(struct wpa_supplicant *wpa_s)
{
        struct wpa_driver_scan_params params;
        struct wpa_driver_scan_params *scan_params;
        enum wpa_states prev_state;
        struct wpa_ssid *ssid = NULL;
        struct wpabuf *extra_ie = NULL;
        int ret;
        unsigned int max_sched_scan_ssids;
        int wildcard = 0;
        int need_ssids;

        if (!wpa_s->sched_scan_supported)
                return -1;

        if (wpa_s->max_sched_scan_ssids > WPAS_MAX_SCAN_SSIDS)
                max_sched_scan_ssids = WPAS_MAX_SCAN_SSIDS;
        else
                max_sched_scan_ssids = wpa_s->max_sched_scan_ssids;
        if (max_sched_scan_ssids < 1 || wpa_s->conf->disable_scan_offload)
                return -1;

        if (wpa_s->sched_scanning) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Already sched scanning");
                return 0;
        }

        need_ssids = 0;
        for (ssid = wpa_s->conf->ssid; ssid; ssid = ssid->next) {
                if (!wpas_network_disabled(wpa_s, ssid) && !ssid->scan_ssid) {
                        /* Use wildcard SSID to find this network */
                        wildcard = 1;
                } else if (!wpas_network_disabled(wpa_s, ssid) &&
                           ssid->ssid_len)
                        need_ssids++;

#ifdef CONFIG_WPS
                if (!wpas_network_disabled(wpa_s, ssid) &&
                    ssid->key_mgmt == WPA_KEY_MGMT_WPS) {
                        /*
                         * Normal scan is more reliable and faster for WPS
                         * operations and since these are for short periods of
                         * time, the benefit of trying to use sched_scan would
                         * be limited.
                         */
                        wpa_dbg(wpa_s, MSG_DEBUG, "Use normal scan instead of "
                                "sched_scan for WPS");
                        return -1;
                }
#endif /* CONFIG_WPS */
        }
        if (wildcard)
                need_ssids++;

        if (wpa_s->normal_scans < 3 &&
            (need_ssids <= wpa_s->max_scan_ssids ||
             wpa_s->max_scan_ssids >= (int) max_sched_scan_ssids)) {
                /*
                 * When normal scan can speed up operations, use that for the
                 * first operations before starting the sched_scan to allow
                 * user space sleep more. We do this only if the normal scan
                 * has functionality that is suitable for this or if the
                 * sched_scan does not have better support for multiple SSIDs.
                 */
                wpa_dbg(wpa_s, MSG_DEBUG, "Use normal scan instead of "
                        "sched_scan for initial scans (normal_scans=%d)",
                        wpa_s->normal_scans);
                return -1;
        }

        os_memset(&params, 0, sizeof(params));

        /* If we can't allocate space for the filters, we just don't filter */
        params.filter_ssids = os_zalloc(wpa_s->max_match_sets *
                                        sizeof(struct wpa_driver_scan_filter));

        prev_state = wpa_s->wpa_state;
        if (wpa_s->wpa_state == WPA_DISCONNECTED ||
            wpa_s->wpa_state == WPA_INACTIVE)
                wpa_supplicant_set_state(wpa_s, WPA_SCANNING);

        if (wpa_s->autoscan_params != NULL) {
                scan_params = wpa_s->autoscan_params;
                goto scan;
        }

        /* Find the starting point from which to continue scanning */
        ssid = wpa_s->conf->ssid;
        if (wpa_s->prev_sched_ssid) {
                while (ssid) {
                        if (ssid == wpa_s->prev_sched_ssid) {
                                ssid = ssid->next;
                                break;
                        }
                        ssid = ssid->next;
                }
        }

        if (!ssid || !wpa_s->prev_sched_ssid) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Beginning of SSID list");
                if (wpa_s->conf->sched_scan_interval)
                        wpa_s->sched_scan_interval =
                                wpa_s->conf->sched_scan_interval;
                if (wpa_s->sched_scan_interval == 0)
                        wpa_s->sched_scan_interval = 10;
                wpa_s->sched_scan_timeout = max_sched_scan_ssids * 2;
                wpa_s->first_sched_scan = 1;
                ssid = wpa_s->conf->ssid;
                wpa_s->prev_sched_ssid = ssid;
        }

        if (wildcard) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Add wildcard SSID to sched_scan");
                params.num_ssids++;
        }

        while (ssid) {
                if (wpas_network_disabled(wpa_s, ssid))
                        goto next;

                if (params.num_filter_ssids < wpa_s->max_match_sets &&
                    params.filter_ssids && ssid->ssid && ssid->ssid_len) {
                        wpa_dbg(wpa_s, MSG_DEBUG, "add to filter ssid: %s",
                                wpa_ssid_txt(ssid->ssid, ssid->ssid_len));
                        os_memcpy(params.filter_ssids[params.num_filter_ssids].ssid,
                                  ssid->ssid, ssid->ssid_len);
                        params.filter_ssids[params.num_filter_ssids].ssid_len =
                                ssid->ssid_len;
                        params.num_filter_ssids++;
                } else if (params.filter_ssids && ssid->ssid && ssid->ssid_len)
                {
                        wpa_dbg(wpa_s, MSG_DEBUG, "Not enough room for SSID "
                                "filter for sched_scan - drop filter");
                        os_free(params.filter_ssids);
                        params.filter_ssids = NULL;
                        params.num_filter_ssids = 0;
                }

                if (ssid->scan_ssid && ssid->ssid && ssid->ssid_len) {
                        if (params.num_ssids == max_sched_scan_ssids)
                                break; /* only room for broadcast SSID */
                        wpa_dbg(wpa_s, MSG_DEBUG,
                                "add to active scan ssid: %s",
                                wpa_ssid_txt(ssid->ssid, ssid->ssid_len));
                        params.ssids[params.num_ssids].ssid =
                                ssid->ssid;
                        params.ssids[params.num_ssids].ssid_len =
                                ssid->ssid_len;
                        params.num_ssids++;
                        if (params.num_ssids >= max_sched_scan_ssids) {
                                wpa_s->prev_sched_ssid = ssid;
                                do {
                                        ssid = ssid->next;
                                } while (ssid &&
                                         (wpas_network_disabled(wpa_s, ssid) ||
                                          !ssid->scan_ssid));
                                break;
                        }
                }

        next:
                wpa_s->prev_sched_ssid = ssid;
                ssid = ssid->next;
        }

        if (params.num_filter_ssids == 0) {
                os_free(params.filter_ssids);
                params.filter_ssids = NULL;
        }

        extra_ie = wpa_supplicant_extra_ies(wpa_s);
        if (extra_ie) {
                params.extra_ies = wpabuf_head(extra_ie);
                params.extra_ies_len = wpabuf_len(extra_ie);
        }

        scan_params = &params;

scan:
        if (ssid || !wpa_s->first_sched_scan) {
                wpa_dbg(wpa_s, MSG_DEBUG,
                        "Starting sched scan: interval %d timeout %d",
                        wpa_s->sched_scan_interval, wpa_s->sched_scan_timeout);
        } else {
                wpa_dbg(wpa_s, MSG_DEBUG,
                        "Starting sched scan: interval %d (no timeout)",
                        wpa_s->sched_scan_interval);
        }

        wpa_setband_scan_freqs(wpa_s, scan_params);

        ret = wpa_supplicant_start_sched_scan(wpa_s, scan_params,
                                              wpa_s->sched_scan_interval);
        wpabuf_free(extra_ie);
        os_free(params.filter_ssids);
        if (ret) {
                wpa_msg(wpa_s, MSG_WARNING, "Failed to initiate sched scan");
                if (prev_state != wpa_s->wpa_state)
                        wpa_supplicant_set_state(wpa_s, prev_state);
                return ret;
        }

        /* If we have more SSIDs to scan, add a timeout so we scan them too */
        if (ssid || !wpa_s->first_sched_scan) {
                wpa_s->sched_scan_timed_out = 0;
                eloop_register_timeout(wpa_s->sched_scan_timeout, 0,
                                       wpa_supplicant_sched_scan_timeout,
                                       wpa_s, NULL);
                wpa_s->first_sched_scan = 0;
                wpa_s->sched_scan_timeout /= 2;
                wpa_s->sched_scan_interval *= 2;
                if (wpa_s->sched_scan_timeout < wpa_s->sched_scan_interval) {
                        wpa_s->sched_scan_interval = 10;
                        wpa_s->sched_scan_timeout = max_sched_scan_ssids * 2;
                }
        }

        /* If there is no more ssids, start next time from the beginning */
        if (!ssid)
                wpa_s->prev_sched_ssid = NULL;

        return 0;
}


/**
 * wpa_supplicant_cancel_scan - Cancel a scheduled scan request
 * @wpa_s: Pointer to wpa_supplicant data
 *
 * This function is used to cancel a scan request scheduled with
 * wpa_supplicant_req_scan().
 */
void wpa_supplicant_cancel_scan(struct wpa_supplicant *wpa_s)
{
        wpa_dbg(wpa_s, MSG_DEBUG, "Cancelling scan request");
        eloop_cancel_timeout(wpa_supplicant_scan, wpa_s, NULL);
        wpas_p2p_continue_after_scan(wpa_s);
}


/**
 * wpa_supplicant_cancel_sched_scan - Stop running scheduled scans
 * @wpa_s: Pointer to wpa_supplicant data
 *
 * This function is used to stop a periodic scheduled scan.
 */
void wpa_supplicant_cancel_sched_scan(struct wpa_supplicant *wpa_s)
{
        if (!wpa_s->sched_scanning)
                return;

        wpa_dbg(wpa_s, MSG_DEBUG, "Cancelling sched scan");
        eloop_cancel_timeout(wpa_supplicant_sched_scan_timeout, wpa_s, NULL);
        wpa_supplicant_stop_sched_scan(wpa_s);
}


/**
 * wpa_supplicant_notify_scanning - Indicate possible scan state change
 * @wpa_s: Pointer to wpa_supplicant data
 * @scanning: Whether scanning is currently in progress
 *
 * This function is to generate scanning notifycations. It is called whenever
 * there may have been a change in scanning (scan started, completed, stopped).
 * wpas_notify_scanning() is called whenever the scanning state changed from the
 * previously notified state.
 */
void wpa_supplicant_notify_scanning(struct wpa_supplicant *wpa_s,
                                    int scanning)
{
        if (wpa_s->scanning != scanning) {
                wpa_s->scanning = scanning;
                wpas_notify_scanning(wpa_s);
        }
}


static int wpa_scan_get_max_rate(const struct wpa_scan_res *res)
{
        int rate = 0;
        const u8 *ie;
        int i;

        ie = wpa_scan_get_ie(res, WLAN_EID_SUPP_RATES);
        for (i = 0; ie && i < ie[1]; i++) {
                if ((ie[i + 2] & 0x7f) > rate)
                        rate = ie[i + 2] & 0x7f;
        }

        ie = wpa_scan_get_ie(res, WLAN_EID_EXT_SUPP_RATES);
        for (i = 0; ie && i < ie[1]; i++) {
                if ((ie[i + 2] & 0x7f) > rate)
                        rate = ie[i + 2] & 0x7f;
        }

        return rate;
}


/**
 * wpa_scan_get_ie - Fetch a specified information element from a scan result
 * @res: Scan result entry
 * @ie: Information element identitifier (WLAN_EID_*)
 * Returns: Pointer to the information element (id field) or %NULL if not found
 *
 * This function returns the first matching information element in the scan
 * result.
 */
const u8 * wpa_scan_get_ie(const struct wpa_scan_res *res, u8 ie)
{
        const u8 *end, *pos;

        pos = (const u8 *) (res + 1);
        end = pos + res->ie_len;

        while (pos + 1 < end) {
                if (pos + 2 + pos[1] > end)
                        break;
                if (pos[0] == ie)
                        return pos;
                pos += 2 + pos[1];
        }

        return NULL;
}


/**
 * wpa_scan_get_vendor_ie - Fetch vendor information element from a scan result
 * @res: Scan result entry
 * @vendor_type: Vendor type (four octets starting the IE payload)
 * Returns: Pointer to the information element (id field) or %NULL if not found
 *
 * This function returns the first matching information element in the scan
 * result.
 */
const u8 * wpa_scan_get_vendor_ie(const struct wpa_scan_res *res,
                                  u32 vendor_type)
{
        const u8 *end, *pos;

        pos = (const u8 *) (res + 1);
        end = pos + res->ie_len;

        while (pos + 1 < end) {
                if (pos + 2 + pos[1] > end)
                        break;
                if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
                    vendor_type == WPA_GET_BE32(&pos[2]))
                        return pos;
                pos += 2 + pos[1];
        }

        return NULL;
}


/**
 * wpa_scan_get_vendor_ie_multi - Fetch vendor IE data from a scan result
 * @res: Scan result entry
 * @vendor_type: Vendor type (four octets starting the IE payload)
 * Returns: Pointer to the information element payload or %NULL if not found
 *
 * This function returns concatenated payload of possibly fragmented vendor
 * specific information elements in the scan result. The caller is responsible
 * for freeing the returned buffer.
 */
struct wpabuf * wpa_scan_get_vendor_ie_multi(const struct wpa_scan_res *res,
                                             u32 vendor_type)
{
        struct wpabuf *buf;
        const u8 *end, *pos;

        buf = wpabuf_alloc(res->ie_len);
        if (buf == NULL)
                return NULL;

        pos = (const u8 *) (res + 1);
        end = pos + res->ie_len;

        while (pos + 1 < end) {
                if (pos + 2 + pos[1] > end)
                        break;
                if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
                    vendor_type == WPA_GET_BE32(&pos[2]))
                        wpabuf_put_data(buf, pos + 2 + 4, pos[1] - 4);
                pos += 2 + pos[1];
        }

        if (wpabuf_len(buf) == 0) {
                wpabuf_free(buf);
                buf = NULL;
        }

        return buf;
}


/*
 * Channels with a great SNR can operate at full rate. What is a great SNR?
 * This doc https://supportforums.cisco.com/docs/DOC-12954 says, "the general
 * rule of thumb is that any SNR above 20 is good." This one
 * http://www.cisco.com/en/US/tech/tk722/tk809/technologies_q_and_a_item09186a00805e9a96.shtml#qa23
 * recommends 25 as a minimum SNR for 54 Mbps data rate. 30 is chosen here as a
 * conservative value.
 */
#define GREAT_SNR 30

/* Compare function for sorting scan results. Return >0 if @b is considered
 * better. */
static int wpa_scan_result_compar(const void *a, const void *b)
{
#define IS_5GHZ(n) (n > 4000)
#define MIN(a,b) a < b ? a : b
        struct wpa_scan_res **_wa = (void *) a;
        struct wpa_scan_res **_wb = (void *) b;
        struct wpa_scan_res *wa = *_wa;
        struct wpa_scan_res *wb = *_wb;
        int wpa_a, wpa_b, maxrate_a, maxrate_b;
        int snr_a, snr_b;

        /* WPA/WPA2 support preferred */
        wpa_a = wpa_scan_get_vendor_ie(wa, WPA_IE_VENDOR_TYPE) != NULL ||
                wpa_scan_get_ie(wa, WLAN_EID_RSN) != NULL;
        wpa_b = wpa_scan_get_vendor_ie(wb, WPA_IE_VENDOR_TYPE) != NULL ||
                wpa_scan_get_ie(wb, WLAN_EID_RSN) != NULL;

        if (wpa_b && !wpa_a)
                return 1;
        if (!wpa_b && wpa_a)
                return -1;

        /* privacy support preferred */
        if ((wa->caps & IEEE80211_CAP_PRIVACY) == 0 &&
            (wb->caps & IEEE80211_CAP_PRIVACY))
                return 1;
        if ((wa->caps & IEEE80211_CAP_PRIVACY) &&
            (wb->caps & IEEE80211_CAP_PRIVACY) == 0)
                return -1;

        if ((wa->flags & wb->flags & WPA_SCAN_LEVEL_DBM) &&
            !((wa->flags | wb->flags) & WPA_SCAN_NOISE_INVALID)) {
                snr_a = MIN(wa->level - wa->noise, GREAT_SNR);
                snr_b = MIN(wb->level - wb->noise, GREAT_SNR);
        } else {
                /* Not suitable information to calculate SNR, so use level */
                snr_a = wa->level;
                snr_b = wb->level;
        }

        /* best/max rate preferred if SNR close enough */
        if ((snr_a && snr_b && abs(snr_b - snr_a) < 5) ||
            (wa->qual && wb->qual && abs(wb->qual - wa->qual) < 10)) {
                maxrate_a = wpa_scan_get_max_rate(wa);
                maxrate_b = wpa_scan_get_max_rate(wb);
                if (maxrate_a != maxrate_b)
                        return maxrate_b - maxrate_a;
                if (IS_5GHZ(wa->freq) ^ IS_5GHZ(wb->freq))
                        return IS_5GHZ(wa->freq) ? -1 : 1;
        }

        /* use freq for channel preference */

        /* all things being equal, use SNR; if SNRs are
         * identical, use quality values since some drivers may only report
         * that value and leave the signal level zero */
        if (snr_b == snr_a)
                return wb->qual - wa->qual;
        return snr_b - snr_a;
#undef MIN
#undef IS_5GHZ
}


#ifdef CONFIG_WPS
/* Compare function for sorting scan results when searching a WPS AP for
 * provisioning. Return >0 if @b is considered better. */
static int wpa_scan_result_wps_compar(const void *a, const void *b)
{
        struct wpa_scan_res **_wa = (void *) a;
        struct wpa_scan_res **_wb = (void *) b;
        struct wpa_scan_res *wa = *_wa;
        struct wpa_scan_res *wb = *_wb;
        int uses_wps_a, uses_wps_b;
        struct wpabuf *wps_a, *wps_b;
        int res;

        /* Optimization - check WPS IE existence before allocated memory and
         * doing full reassembly. */
        uses_wps_a = wpa_scan_get_vendor_ie(wa, WPS_IE_VENDOR_TYPE) != NULL;
        uses_wps_b = wpa_scan_get_vendor_ie(wb, WPS_IE_VENDOR_TYPE) != NULL;
        if (uses_wps_a && !uses_wps_b)
                return -1;
        if (!uses_wps_a && uses_wps_b)
                return 1;

        if (uses_wps_a && uses_wps_b) {
                wps_a = wpa_scan_get_vendor_ie_multi(wa, WPS_IE_VENDOR_TYPE);
                wps_b = wpa_scan_get_vendor_ie_multi(wb, WPS_IE_VENDOR_TYPE);
                res = wps_ap_priority_compar(wps_a, wps_b);
                wpabuf_free(wps_a);
                wpabuf_free(wps_b);
                if (res)
                        return res;
        }

        /*
         * Do not use current AP security policy as a sorting criteria during
         * WPS provisioning step since the AP may get reconfigured at the
         * completion of provisioning.
         */

        /* all things being equal, use signal level; if signal levels are
         * identical, use quality values since some drivers may only report
         * that value and leave the signal level zero */
        if (wb->level == wa->level)
                return wb->qual - wa->qual;
        return wb->level - wa->level;
}
#endif /* CONFIG_WPS */


static void dump_scan_res(struct wpa_scan_results *scan_res)
{
#ifndef CONFIG_NO_STDOUT_DEBUG
        size_t i;

        if (scan_res->res == NULL || scan_res->num == 0)
                return;

        wpa_printf(MSG_EXCESSIVE, "Sorted scan results");

        for (i = 0; i < scan_res->num; i++) {
                struct wpa_scan_res *r = scan_res->res[i];
                u8 *pos;
                if ((r->flags & (WPA_SCAN_LEVEL_DBM | WPA_SCAN_NOISE_INVALID))
                    == WPA_SCAN_LEVEL_DBM) {
                        int snr = r->level - r->noise;
                        wpa_printf(MSG_EXCESSIVE, MACSTR " freq=%d qual=%d "
                                   "noise=%d level=%d snr=%d%s flags=0x%x "
                                   "age=%u",
                                   MAC2STR(r->bssid), r->freq, r->qual,
                                   r->noise, r->level, snr,
                                   snr >= GREAT_SNR ? "*" : "", r->flags,
                                   r->age);
                } else {
                        wpa_printf(MSG_EXCESSIVE, MACSTR " freq=%d qual=%d "
                                   "noise=%d level=%d flags=0x%x age=%u",
                                   MAC2STR(r->bssid), r->freq, r->qual,
                                   r->noise, r->level, r->flags, r->age);
                }
                pos = (u8 *) (r + 1);
                if (r->ie_len)
                        wpa_hexdump(MSG_EXCESSIVE, "IEs", pos, r->ie_len);
                pos += r->ie_len;
                if (r->beacon_ie_len)
                        wpa_hexdump(MSG_EXCESSIVE, "Beacon IEs",
                                    pos, r->beacon_ie_len);
        }
#endif /* CONFIG_NO_STDOUT_DEBUG */
}


/**
 * wpa_supplicant_filter_bssid_match - Is the specified BSSID allowed
 * @wpa_s: Pointer to wpa_supplicant data
 * @bssid: BSSID to check
 * Returns: 0 if the BSSID is filtered or 1 if not
 *
 * This function is used to filter out specific BSSIDs from scan reslts mainly
 * for testing purposes (SET bssid_filter ctrl_iface command).
 */
int wpa_supplicant_filter_bssid_match(struct wpa_supplicant *wpa_s,
                                      const u8 *bssid)
{
        size_t i;

        if (wpa_s->bssid_filter == NULL)
                return 1;

        for (i = 0; i < wpa_s->bssid_filter_count; i++) {
                if (os_memcmp(wpa_s->bssid_filter + i * ETH_ALEN, bssid,
                              ETH_ALEN) == 0)
                        return 1;
        }

        return 0;
}


static void filter_scan_res(struct wpa_supplicant *wpa_s,
                            struct wpa_scan_results *res)
{
        size_t i, j;

        if (wpa_s->bssid_filter == NULL)
                return;

        for (i = 0, j = 0; i < res->num; i++) {
                if (wpa_supplicant_filter_bssid_match(wpa_s,
                                                      res->res[i]->bssid)) {
                        res->res[j++] = res->res[i];
                } else {
                        os_free(res->res[i]);
                        res->res[i] = NULL;
                }
        }

        if (res->num != j) {
                wpa_printf(MSG_DEBUG, "Filtered out %d scan results",
                           (int) (res->num - j));
                res->num = j;
        }
}


/**
 * wpa_supplicant_get_scan_results - Get scan results
 * @wpa_s: Pointer to wpa_supplicant data
 * @info: Information about what was scanned or %NULL if not available
 * @new_scan: Whether a new scan was performed
 * Returns: Scan results, %NULL on failure
 *
 * This function request the current scan results from the driver and updates
 * the local BSS list wpa_s->bss. The caller is responsible for freeing the
 * results with wpa_scan_results_free().
 */
struct wpa_scan_results *
wpa_supplicant_get_scan_results(struct wpa_supplicant *wpa_s,
                                struct scan_info *info, int new_scan)
{
        struct wpa_scan_results *scan_res;
        size_t i;
        int (*compar)(const void *, const void *) = wpa_scan_result_compar;

        scan_res = wpa_drv_get_scan_results2(wpa_s);
        if (scan_res == NULL) {
                wpa_dbg(wpa_s, MSG_DEBUG, "Failed to get scan results");
                return NULL;
        }
        if (scan_res->fetch_time.sec == 0) {
                /*
                 * Make sure we have a valid timestamp if the driver wrapper
                 * does not set this.
                 */
                os_get_time(&scan_res->fetch_time);
        }
        filter_scan_res(wpa_s, scan_res);

#ifdef CONFIG_WPS
        if (wpas_wps_in_progress(wpa_s)) {
                wpa_dbg(wpa_s, MSG_DEBUG, "WPS: Order scan results with WPS "
                        "provisioning rules");
                compar = wpa_scan_result_wps_compar;
        }
#endif /* CONFIG_WPS */

        qsort(scan_res->res, scan_res->num, sizeof(struct wpa_scan_res *),
              compar);
        dump_scan_res(scan_res);

        wpa_bss_update_start(wpa_s);
        for (i = 0; i < scan_res->num; i++)
                wpa_bss_update_scan_res(wpa_s, scan_res->res[i],
                                        &scan_res->fetch_time);
        wpa_bss_update_end(wpa_s, info, new_scan);

        return scan_res;
}


/**
 * wpa_supplicant_update_scan_results - Update scan results from the driver
 * @wpa_s: Pointer to wpa_supplicant data
 * Returns: 0 on success, -1 on failure
 *
 * This function updates the BSS table within wpa_supplicant based on the
 * currently available scan results from the driver without requesting a new
 * scan. This is used in cases where the driver indicates an association
 * (including roaming within ESS) and wpa_supplicant does not yet have the
 * needed information to complete the connection (e.g., to perform validation
 * steps in 4-way handshake).
 */
int wpa_supplicant_update_scan_results(struct wpa_supplicant *wpa_s)
{
        struct wpa_scan_results *scan_res;
        scan_res = wpa_supplicant_get_scan_results(wpa_s, NULL, 0);
        if (scan_res == NULL)
                return -1;
        wpa_scan_results_free(scan_res);

        return 0;
}


/**
 * scan_only_handler - Reports scan results
 */
void scan_only_handler(struct wpa_supplicant *wpa_s,
                       struct wpa_scan_results *scan_res)
{
        wpa_dbg(wpa_s, MSG_DEBUG, "Scan-only results received");
        wpa_msg_ctrl(wpa_s, MSG_INFO, WPA_EVENT_SCAN_RESULTS);
        wpas_notify_scan_results(wpa_s);
        wpas_notify_scan_done(wpa_s, 1);
}


int wpas_scan_scheduled(struct wpa_supplicant *wpa_s)
{
        return eloop_is_timeout_registered(wpa_supplicant_scan, wpa_s, NULL);
}