Remove disconnected APs from BSS table if likely out-of-range

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

/*
 * BSS table
 * Copyright (c) 2009-2015, 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 "drivers/driver.h"
#include "eap_peer/eap.h"
#include "wpa_supplicant_i.h"
#include "config.h"
#include "notify.h"
#include "scan.h"
#include "bss.h"


#define WPA_BSS_FREQ_CHANGED_FLAG       BIT(0)
#define WPA_BSS_SIGNAL_CHANGED_FLAG     BIT(1)
#define WPA_BSS_PRIVACY_CHANGED_FLAG    BIT(2)
#define WPA_BSS_MODE_CHANGED_FLAG       BIT(3)
#define WPA_BSS_WPAIE_CHANGED_FLAG      BIT(4)
#define WPA_BSS_RSNIE_CHANGED_FLAG      BIT(5)
#define WPA_BSS_WPS_CHANGED_FLAG        BIT(6)
#define WPA_BSS_RATES_CHANGED_FLAG      BIT(7)
#define WPA_BSS_IES_CHANGED_FLAG        BIT(8)


static void wpa_bss_set_hessid(struct wpa_bss *bss)
{
#ifdef CONFIG_INTERWORKING
        const u8 *ie = wpa_bss_get_ie(bss, WLAN_EID_INTERWORKING);
        if (ie == NULL || (ie[1] != 7 && ie[1] != 9)) {
                os_memset(bss->hessid, 0, ETH_ALEN);
                return;
        }
        if (ie[1] == 7)
                os_memcpy(bss->hessid, ie + 3, ETH_ALEN);
        else
                os_memcpy(bss->hessid, ie + 5, ETH_ALEN);
#endif /* CONFIG_INTERWORKING */
}


/**
 * wpa_bss_anqp_alloc - Allocate ANQP data structure for a BSS entry
 * Returns: Allocated ANQP data structure or %NULL on failure
 *
 * The allocated ANQP data structure has its users count set to 1. It may be
 * shared by multiple BSS entries and each shared entry is freed with
 * wpa_bss_anqp_free().
 */
struct wpa_bss_anqp * wpa_bss_anqp_alloc(void)
{
        struct wpa_bss_anqp *anqp;
        anqp = os_zalloc(sizeof(*anqp));
        if (anqp == NULL)
                return NULL;
#ifdef CONFIG_INTERWORKING
        dl_list_init(&anqp->anqp_elems);
#endif /* CONFIG_INTERWORKING */
        anqp->users = 1;
        return anqp;
}


/**
 * wpa_bss_anqp_clone - Clone an ANQP data structure
 * @anqp: ANQP data structure from wpa_bss_anqp_alloc()
 * Returns: Cloned ANQP data structure or %NULL on failure
 */
static struct wpa_bss_anqp * wpa_bss_anqp_clone(struct wpa_bss_anqp *anqp)
{
        struct wpa_bss_anqp *n;

        n = os_zalloc(sizeof(*n));
        if (n == NULL)
                return NULL;

#define ANQP_DUP(f) if (anqp->f) n->f = wpabuf_dup(anqp->f)
#ifdef CONFIG_INTERWORKING
        dl_list_init(&n->anqp_elems);
        ANQP_DUP(capability_list);
        ANQP_DUP(venue_name);
        ANQP_DUP(network_auth_type);
        ANQP_DUP(roaming_consortium);
        ANQP_DUP(ip_addr_type_availability);
        ANQP_DUP(nai_realm);
        ANQP_DUP(anqp_3gpp);
        ANQP_DUP(domain_name);
#endif /* CONFIG_INTERWORKING */
#ifdef CONFIG_HS20
        ANQP_DUP(hs20_capability_list);
        ANQP_DUP(hs20_operator_friendly_name);
        ANQP_DUP(hs20_wan_metrics);
        ANQP_DUP(hs20_connection_capability);
        ANQP_DUP(hs20_operating_class);
        ANQP_DUP(hs20_osu_providers_list);
#endif /* CONFIG_HS20 */
#undef ANQP_DUP

        return n;
}


/**
 * wpa_bss_anqp_unshare_alloc - Unshare ANQP data (if shared) in a BSS entry
 * @bss: BSS entry
 * Returns: 0 on success, -1 on failure
 *
 * This function ensures the specific BSS entry has an ANQP data structure that
 * is not shared with any other BSS entry.
 */
int wpa_bss_anqp_unshare_alloc(struct wpa_bss *bss)
{
        struct wpa_bss_anqp *anqp;

        if (bss->anqp && bss->anqp->users > 1) {
                /* allocated, but shared - clone an unshared copy */
                anqp = wpa_bss_anqp_clone(bss->anqp);
                if (anqp == NULL)
                        return -1;
                anqp->users = 1;
                bss->anqp->users--;
                bss->anqp = anqp;
                return 0;
        }

        if (bss->anqp)
                return 0; /* already allocated and not shared */

        /* not allocated - allocate a new storage area */
        bss->anqp = wpa_bss_anqp_alloc();
        return bss->anqp ? 0 : -1;
}


/**
 * wpa_bss_anqp_free - Free an ANQP data structure
 * @anqp: ANQP data structure from wpa_bss_anqp_alloc() or wpa_bss_anqp_clone()
 */
static void wpa_bss_anqp_free(struct wpa_bss_anqp *anqp)
{
#ifdef CONFIG_INTERWORKING
        struct wpa_bss_anqp_elem *elem;
#endif /* CONFIG_INTERWORKING */

        if (anqp == NULL)
                return;

        anqp->users--;
        if (anqp->users > 0) {
                /* Another BSS entry holds a pointer to this ANQP info */
                return;
        }

#ifdef CONFIG_INTERWORKING
        wpabuf_free(anqp->capability_list);
        wpabuf_free(anqp->venue_name);
        wpabuf_free(anqp->network_auth_type);
        wpabuf_free(anqp->roaming_consortium);
        wpabuf_free(anqp->ip_addr_type_availability);
        wpabuf_free(anqp->nai_realm);
        wpabuf_free(anqp->anqp_3gpp);
        wpabuf_free(anqp->domain_name);

        while ((elem = dl_list_first(&anqp->anqp_elems,
                                     struct wpa_bss_anqp_elem, list))) {
                dl_list_del(&elem->list);
                wpabuf_free(elem->payload);
                os_free(elem);
        }
#endif /* CONFIG_INTERWORKING */
#ifdef CONFIG_HS20
        wpabuf_free(anqp->hs20_capability_list);
        wpabuf_free(anqp->hs20_operator_friendly_name);
        wpabuf_free(anqp->hs20_wan_metrics);
        wpabuf_free(anqp->hs20_connection_capability);
        wpabuf_free(anqp->hs20_operating_class);
        wpabuf_free(anqp->hs20_osu_providers_list);
#endif /* CONFIG_HS20 */

        os_free(anqp);
}


static void wpa_bss_update_pending_connect(struct wpa_supplicant *wpa_s,
                                           struct wpa_bss *old_bss,
                                           struct wpa_bss *new_bss)
{
        struct wpa_radio_work *work;
        struct wpa_connect_work *cwork;

        work = radio_work_pending(wpa_s, "sme-connect");
        if (!work)
                work = radio_work_pending(wpa_s, "connect");
        if (!work)
                return;

        cwork = work->ctx;
        if (cwork->bss != old_bss)
                return;

        wpa_printf(MSG_DEBUG,
                   "Update BSS pointer for the pending connect radio work");
        cwork->bss = new_bss;
        if (!new_bss)
                cwork->bss_removed = 1;
}


void wpa_bss_remove(struct wpa_supplicant *wpa_s, struct wpa_bss *bss,
                    const char *reason)
{
        if (wpa_s->last_scan_res) {
                unsigned int i;
                for (i = 0; i < wpa_s->last_scan_res_used; i++) {
                        if (wpa_s->last_scan_res[i] == bss) {
                                os_memmove(&wpa_s->last_scan_res[i],
                                           &wpa_s->last_scan_res[i + 1],
                                           (wpa_s->last_scan_res_used - i - 1)
                                           * sizeof(struct wpa_bss *));
                                wpa_s->last_scan_res_used--;
                                break;
                        }
                }
        }
        wpa_bss_update_pending_connect(wpa_s, bss, NULL);
        dl_list_del(&bss->list);
        dl_list_del(&bss->list_id);
        wpa_s->num_bss--;
        wpa_dbg(wpa_s, MSG_DEBUG, "BSS: Remove id %u BSSID " MACSTR
                " SSID '%s' due to %s", bss->id, MAC2STR(bss->bssid),
                wpa_ssid_txt(bss->ssid, bss->ssid_len), reason);
        wpas_notify_bss_removed(wpa_s, bss->bssid, bss->id);
        wpa_bss_anqp_free(bss->anqp);
        os_free(bss);
}


/**
 * wpa_bss_get - Fetch a BSS table entry based on BSSID and SSID
 * @wpa_s: Pointer to wpa_supplicant data
 * @bssid: BSSID
 * @ssid: SSID
 * @ssid_len: Length of @ssid
 * Returns: Pointer to the BSS entry or %NULL if not found
 */
struct wpa_bss * wpa_bss_get(struct wpa_supplicant *wpa_s, const u8 *bssid,
                             const u8 *ssid, size_t ssid_len)
{
        struct wpa_bss *bss;
        if (!wpa_supplicant_filter_bssid_match(wpa_s, bssid))
                return NULL;
        dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
                if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0 &&
                    bss->ssid_len == ssid_len &&
                    os_memcmp(bss->ssid, ssid, ssid_len) == 0)
                        return bss;
        }
        return NULL;
}


static void calculate_update_time(const struct os_reltime *fetch_time,
                                  unsigned int age_ms,
                                  struct os_reltime *update_time)
{
        os_time_t usec;

        update_time->sec = fetch_time->sec;
        update_time->usec = fetch_time->usec;
        update_time->sec -= age_ms / 1000;
        usec = (age_ms % 1000) * 1000;
        if (update_time->usec < usec) {
                update_time->sec--;
                update_time->usec += 1000000;
        }
        update_time->usec -= usec;
}


static void wpa_bss_copy_res(struct wpa_bss *dst, struct wpa_scan_res *src,
                             struct os_reltime *fetch_time)
{
        dst->flags = src->flags;
        os_memcpy(dst->bssid, src->bssid, ETH_ALEN);
        dst->freq = src->freq;
        dst->beacon_int = src->beacon_int;
        dst->caps = src->caps;
        dst->qual = src->qual;
        dst->noise = src->noise;
        dst->level = src->level;
        dst->tsf = src->tsf;
        dst->est_throughput = src->est_throughput;
        dst->snr = src->snr;

        calculate_update_time(fetch_time, src->age, &dst->last_update);
}


static int wpa_bss_is_wps_candidate(struct wpa_supplicant *wpa_s,
                                    struct wpa_bss *bss)
{
#ifdef CONFIG_WPS
        struct wpa_ssid *ssid;
        struct wpabuf *wps_ie;
        int pbc = 0, ret;

        wps_ie = wpa_bss_get_vendor_ie_multi(bss, WPS_IE_VENDOR_TYPE);
        if (!wps_ie)
                return 0;

        if (wps_is_selected_pbc_registrar(wps_ie)) {
                pbc = 1;
        } else if (!wps_is_addr_authorized(wps_ie, wpa_s->own_addr, 1)) {
                wpabuf_free(wps_ie);
                return 0;
        }

        for (ssid = wpa_s->conf->ssid; ssid; ssid = ssid->next) {
                if (!(ssid->key_mgmt & WPA_KEY_MGMT_WPS))
                        continue;
                if (ssid->ssid_len &&
                    (ssid->ssid_len != bss->ssid_len ||
                     os_memcmp(ssid->ssid, bss->ssid, ssid->ssid_len) != 0))
                        continue;

                if (pbc)
                        ret = eap_is_wps_pbc_enrollee(&ssid->eap);
                else
                        ret = eap_is_wps_pin_enrollee(&ssid->eap);
                wpabuf_free(wps_ie);
                return ret;
        }
        wpabuf_free(wps_ie);
#endif /* CONFIG_WPS */

        return 0;
}


static int wpa_bss_known(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
{
        struct wpa_ssid *ssid;

        for (ssid = wpa_s->conf->ssid; ssid; ssid = ssid->next) {
                if (ssid->ssid == NULL || ssid->ssid_len == 0)
                        continue;
                if (ssid->ssid_len == bss->ssid_len &&
                    os_memcmp(ssid->ssid, bss->ssid, ssid->ssid_len) == 0)
                        return 1;
        }

        return 0;
}


static int wpa_bss_in_use(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
{
        if (bss == wpa_s->current_bss)
                return 1;

        if (wpa_s->current_bss &&
            (bss->ssid_len != wpa_s->current_bss->ssid_len ||
             os_memcmp(bss->ssid, wpa_s->current_bss->ssid,
                       bss->ssid_len) != 0))
                return 0; /* SSID has changed */

        return !is_zero_ether_addr(bss->bssid) &&
                (os_memcmp(bss->bssid, wpa_s->bssid, ETH_ALEN) == 0 ||
                 os_memcmp(bss->bssid, wpa_s->pending_bssid, ETH_ALEN) == 0);
}


static int wpa_bss_remove_oldest_unknown(struct wpa_supplicant *wpa_s)
{
        struct wpa_bss *bss;

        dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
                if (!wpa_bss_known(wpa_s, bss) &&
                    !wpa_bss_is_wps_candidate(wpa_s, bss)) {
                        wpa_bss_remove(wpa_s, bss, __func__);
                        return 0;
                }
        }

        return -1;
}


static int wpa_bss_remove_oldest(struct wpa_supplicant *wpa_s)
{
        struct wpa_bss *bss;

        /*
         * Remove the oldest entry that does not match with any configured
         * network.
         */
        if (wpa_bss_remove_oldest_unknown(wpa_s) == 0)
                return 0;

        /*
         * Remove the oldest entry that isn't currently in use.
         */
        dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
                if (!wpa_bss_in_use(wpa_s, bss)) {
                        wpa_bss_remove(wpa_s, bss, __func__);
                        return 0;
                }
        }

        return -1;
}


static struct wpa_bss * wpa_bss_add(struct wpa_supplicant *wpa_s,
                                    const u8 *ssid, size_t ssid_len,
                                    struct wpa_scan_res *res,
                                    struct os_reltime *fetch_time)
{
        struct wpa_bss *bss;

        bss = os_zalloc(sizeof(*bss) + res->ie_len + res->beacon_ie_len);
        if (bss == NULL)
                return NULL;
        bss->id = wpa_s->bss_next_id++;
        bss->last_update_idx = wpa_s->bss_update_idx;
        wpa_bss_copy_res(bss, res, fetch_time);
        os_memcpy(bss->ssid, ssid, ssid_len);
        bss->ssid_len = ssid_len;
        bss->ie_len = res->ie_len;
        bss->beacon_ie_len = res->beacon_ie_len;
        os_memcpy(bss + 1, res + 1, res->ie_len + res->beacon_ie_len);
        wpa_bss_set_hessid(bss);

        if (wpa_s->num_bss + 1 > wpa_s->conf->bss_max_count &&
            wpa_bss_remove_oldest(wpa_s) != 0) {
                wpa_printf(MSG_ERROR, "Increasing the MAX BSS count to %d "
                           "because all BSSes are in use. We should normally "
                           "not get here!", (int) wpa_s->num_bss + 1);
                wpa_s->conf->bss_max_count = wpa_s->num_bss + 1;
        }

        dl_list_add_tail(&wpa_s->bss, &bss->list);
        dl_list_add_tail(&wpa_s->bss_id, &bss->list_id);
        wpa_s->num_bss++;
        wpa_dbg(wpa_s, MSG_DEBUG, "BSS: Add new id %u BSSID " MACSTR
                " SSID '%s' freq %d",
                bss->id, MAC2STR(bss->bssid), wpa_ssid_txt(ssid, ssid_len),
                bss->freq);
        wpas_notify_bss_added(wpa_s, bss->bssid, bss->id);
        return bss;
}


static int are_ies_equal(const struct wpa_bss *old,
                         const struct wpa_scan_res *new_res, u32 ie)
{
        const u8 *old_ie, *new_ie;
        struct wpabuf *old_ie_buff = NULL;
        struct wpabuf *new_ie_buff = NULL;
        int new_ie_len, old_ie_len, ret, is_multi;

        switch (ie) {
        case WPA_IE_VENDOR_TYPE:
                old_ie = wpa_bss_get_vendor_ie(old, ie);
                new_ie = wpa_scan_get_vendor_ie(new_res, ie);
                is_multi = 0;
                break;
        case WPS_IE_VENDOR_TYPE:
                old_ie_buff = wpa_bss_get_vendor_ie_multi(old, ie);
                new_ie_buff = wpa_scan_get_vendor_ie_multi(new_res, ie);
                is_multi = 1;
                break;
        case WLAN_EID_RSN:
        case WLAN_EID_SUPP_RATES:
        case WLAN_EID_EXT_SUPP_RATES:
                old_ie = wpa_bss_get_ie(old, ie);
                new_ie = wpa_scan_get_ie(new_res, ie);
                is_multi = 0;
                break;
        default:
                wpa_printf(MSG_DEBUG, "bss: %s: cannot compare IEs", __func__);
                return 0;
        }

        if (is_multi) {
                /* in case of multiple IEs stored in buffer */
                old_ie = old_ie_buff ? wpabuf_head_u8(old_ie_buff) : NULL;
                new_ie = new_ie_buff ? wpabuf_head_u8(new_ie_buff) : NULL;
                old_ie_len = old_ie_buff ? wpabuf_len(old_ie_buff) : 0;
                new_ie_len = new_ie_buff ? wpabuf_len(new_ie_buff) : 0;
        } else {
                /* in case of single IE */
                old_ie_len = old_ie ? old_ie[1] + 2 : 0;
                new_ie_len = new_ie ? new_ie[1] + 2 : 0;
        }

        if (!old_ie || !new_ie)
                ret = !old_ie && !new_ie;
        else
                ret = (old_ie_len == new_ie_len &&
                       os_memcmp(old_ie, new_ie, old_ie_len) == 0);

        wpabuf_free(old_ie_buff);
        wpabuf_free(new_ie_buff);

        return ret;
}


static u32 wpa_bss_compare_res(const struct wpa_bss *old,
                               const struct wpa_scan_res *new_res)
{
        u32 changes = 0;
        int caps_diff = old->caps ^ new_res->caps;

        if (old->freq != new_res->freq)
                changes |= WPA_BSS_FREQ_CHANGED_FLAG;

        if (old->level != new_res->level)
                changes |= WPA_BSS_SIGNAL_CHANGED_FLAG;

        if (caps_diff & IEEE80211_CAP_PRIVACY)
                changes |= WPA_BSS_PRIVACY_CHANGED_FLAG;

        if (caps_diff & IEEE80211_CAP_IBSS)
                changes |= WPA_BSS_MODE_CHANGED_FLAG;

        if (old->ie_len == new_res->ie_len &&
            os_memcmp(old + 1, new_res + 1, old->ie_len) == 0)
                return changes;
        changes |= WPA_BSS_IES_CHANGED_FLAG;

        if (!are_ies_equal(old, new_res, WPA_IE_VENDOR_TYPE))
                changes |= WPA_BSS_WPAIE_CHANGED_FLAG;

        if (!are_ies_equal(old, new_res, WLAN_EID_RSN))
                changes |= WPA_BSS_RSNIE_CHANGED_FLAG;

        if (!are_ies_equal(old, new_res, WPS_IE_VENDOR_TYPE))
                changes |= WPA_BSS_WPS_CHANGED_FLAG;

        if (!are_ies_equal(old, new_res, WLAN_EID_SUPP_RATES) ||
            !are_ies_equal(old, new_res, WLAN_EID_EXT_SUPP_RATES))
                changes |= WPA_BSS_RATES_CHANGED_FLAG;

        return changes;
}


static void notify_bss_changes(struct wpa_supplicant *wpa_s, u32 changes,
                               const struct wpa_bss *bss)
{
        if (changes & WPA_BSS_FREQ_CHANGED_FLAG)
                wpas_notify_bss_freq_changed(wpa_s, bss->id);

        if (changes & WPA_BSS_SIGNAL_CHANGED_FLAG)
                wpas_notify_bss_signal_changed(wpa_s, bss->id);

        if (changes & WPA_BSS_PRIVACY_CHANGED_FLAG)
                wpas_notify_bss_privacy_changed(wpa_s, bss->id);

        if (changes & WPA_BSS_MODE_CHANGED_FLAG)
                wpas_notify_bss_mode_changed(wpa_s, bss->id);

        if (changes & WPA_BSS_WPAIE_CHANGED_FLAG)
                wpas_notify_bss_wpaie_changed(wpa_s, bss->id);

        if (changes & WPA_BSS_RSNIE_CHANGED_FLAG)
                wpas_notify_bss_rsnie_changed(wpa_s, bss->id);

        if (changes & WPA_BSS_WPS_CHANGED_FLAG)
                wpas_notify_bss_wps_changed(wpa_s, bss->id);

        if (changes & WPA_BSS_IES_CHANGED_FLAG)
                wpas_notify_bss_ies_changed(wpa_s, bss->id);

        if (changes & WPA_BSS_RATES_CHANGED_FLAG)
                wpas_notify_bss_rates_changed(wpa_s, bss->id);

        wpas_notify_bss_seen(wpa_s, bss->id);
}


static struct wpa_bss *
wpa_bss_update(struct wpa_supplicant *wpa_s, struct wpa_bss *bss,
               struct wpa_scan_res *res, struct os_reltime *fetch_time)
{
        u32 changes;

        changes = wpa_bss_compare_res(bss, res);
        if (changes & WPA_BSS_FREQ_CHANGED_FLAG)
                wpa_printf(MSG_DEBUG, "BSS: " MACSTR " changed freq %d --> %d",
                           MAC2STR(bss->bssid), bss->freq, res->freq);
        bss->scan_miss_count = 0;
        bss->last_update_idx = wpa_s->bss_update_idx;
        wpa_bss_copy_res(bss, res, fetch_time);
        /* Move the entry to the end of the list */
        dl_list_del(&bss->list);
#ifdef CONFIG_P2P
        if (wpa_bss_get_vendor_ie(bss, P2P_IE_VENDOR_TYPE) &&
            !wpa_scan_get_vendor_ie(res, P2P_IE_VENDOR_TYPE)) {
                /*
                 * This can happen when non-P2P station interface runs a scan
                 * without P2P IE in the Probe Request frame. P2P GO would reply
                 * to that with a Probe Response that does not include P2P IE.
                 * Do not update the IEs in this BSS entry to avoid such loss of
                 * information that may be needed for P2P operations to
                 * determine group information.
                 */
                wpa_dbg(wpa_s, MSG_DEBUG, "BSS: Do not update scan IEs for "
                        MACSTR " since that would remove P2P IE information",
                        MAC2STR(bss->bssid));
        } else
#endif /* CONFIG_P2P */
        if (bss->ie_len + bss->beacon_ie_len >=
            res->ie_len + res->beacon_ie_len) {
                os_memcpy(bss + 1, res + 1, res->ie_len + res->beacon_ie_len);
                bss->ie_len = res->ie_len;
                bss->beacon_ie_len = res->beacon_ie_len;
        } else {
                struct wpa_bss *nbss;
                struct dl_list *prev = bss->list_id.prev;
                dl_list_del(&bss->list_id);
                nbss = os_realloc(bss, sizeof(*bss) + res->ie_len +
                                  res->beacon_ie_len);
                if (nbss) {
                        unsigned int i;
                        for (i = 0; i < wpa_s->last_scan_res_used; i++) {
                                if (wpa_s->last_scan_res[i] == bss) {
                                        wpa_s->last_scan_res[i] = nbss;
                                        break;
                                }
                        }
                        if (wpa_s->current_bss == bss)
                                wpa_s->current_bss = nbss;
                        wpa_bss_update_pending_connect(wpa_s, bss, nbss);
                        bss = nbss;
                        os_memcpy(bss + 1, res + 1,
                                  res->ie_len + res->beacon_ie_len);
                        bss->ie_len = res->ie_len;
                        bss->beacon_ie_len = res->beacon_ie_len;
                }
                dl_list_add(prev, &bss->list_id);
        }
        if (changes & WPA_BSS_IES_CHANGED_FLAG)
                wpa_bss_set_hessid(bss);
        dl_list_add_tail(&wpa_s->bss, &bss->list);

        notify_bss_changes(wpa_s, changes, bss);

        return bss;
}


/**
 * wpa_bss_update_start - Start a BSS table update from scan results
 * @wpa_s: Pointer to wpa_supplicant data
 *
 * This function is called at the start of each BSS table update round for new
 * scan results. The actual scan result entries are indicated with calls to
 * wpa_bss_update_scan_res() and the update round is finished with a call to
 * wpa_bss_update_end().
 */
void wpa_bss_update_start(struct wpa_supplicant *wpa_s)
{
        wpa_s->bss_update_idx++;
        wpa_dbg(wpa_s, MSG_DEBUG, "BSS: Start scan result update %u",
                wpa_s->bss_update_idx);
        wpa_s->last_scan_res_used = 0;
}


/**
 * wpa_bss_update_scan_res - Update a BSS table entry based on a scan result
 * @wpa_s: Pointer to wpa_supplicant data
 * @res: Scan result
 * @fetch_time: Time when the result was fetched from the driver
 *
 * This function updates a BSS table entry (or adds one) based on a scan result.
 * This is called separately for each scan result between the calls to
 * wpa_bss_update_start() and wpa_bss_update_end().
 */
void wpa_bss_update_scan_res(struct wpa_supplicant *wpa_s,
                             struct wpa_scan_res *res,
                             struct os_reltime *fetch_time)
{
        const u8 *ssid, *p2p, *mesh;
        struct wpa_bss *bss;

        if (wpa_s->conf->ignore_old_scan_res) {
                struct os_reltime update;
                calculate_update_time(fetch_time, res->age, &update);
                if (os_reltime_before(&update, &wpa_s->scan_trigger_time)) {
                        struct os_reltime age;
                        os_reltime_sub(&wpa_s->scan_trigger_time, &update,
                                       &age);
                        wpa_dbg(wpa_s, MSG_DEBUG, "BSS: Ignore driver BSS "
                                "table entry that is %u.%06u seconds older "
                                "than our scan trigger",
                                (unsigned int) age.sec,
                                (unsigned int) age.usec);
                        return;
                }
        }

        ssid = wpa_scan_get_ie(res, WLAN_EID_SSID);
        if (ssid == NULL) {
                wpa_dbg(wpa_s, MSG_DEBUG, "BSS: No SSID IE included for "
                        MACSTR, MAC2STR(res->bssid));
                return;
        }
        if (ssid[1] > SSID_MAX_LEN) {
                wpa_dbg(wpa_s, MSG_DEBUG, "BSS: Too long SSID IE included for "
                        MACSTR, MAC2STR(res->bssid));
                return;
        }

        p2p = wpa_scan_get_vendor_ie(res, P2P_IE_VENDOR_TYPE);
#ifdef CONFIG_P2P
        if (p2p == NULL &&
            wpa_s->p2p_group_interface != NOT_P2P_GROUP_INTERFACE) {
                /*
                 * If it's a P2P specific interface, then don't update
                 * the scan result without a P2P IE.
                 */
                wpa_printf(MSG_DEBUG, "BSS: No P2P IE - skipping BSS " MACSTR
                           " update for P2P interface", MAC2STR(res->bssid));
                return;
        }
#endif /* CONFIG_P2P */
        if (p2p && ssid[1] == P2P_WILDCARD_SSID_LEN &&
            os_memcmp(ssid + 2, P2P_WILDCARD_SSID, P2P_WILDCARD_SSID_LEN) == 0)
                return; /* Skip P2P listen discovery results here */

        /* TODO: add option for ignoring BSSes we are not interested in
         * (to save memory) */

        mesh = wpa_scan_get_ie(res, WLAN_EID_MESH_ID);
        if (mesh && mesh[1] <= SSID_MAX_LEN)
                ssid = mesh;

        bss = wpa_bss_get(wpa_s, res->bssid, ssid + 2, ssid[1]);
        if (bss == NULL)
                bss = wpa_bss_add(wpa_s, ssid + 2, ssid[1], res, fetch_time);
        else {
                bss = wpa_bss_update(wpa_s, bss, res, fetch_time);
                if (wpa_s->last_scan_res) {
                        unsigned int i;
                        for (i = 0; i < wpa_s->last_scan_res_used; i++) {
                                if (bss == wpa_s->last_scan_res[i]) {
                                        /* Already in the list */
                                        return;
                                }
                        }
                }
        }

        if (bss == NULL)
                return;
        if (wpa_s->last_scan_res_used >= wpa_s->last_scan_res_size) {
                struct wpa_bss **n;
                unsigned int siz;
                if (wpa_s->last_scan_res_size == 0)
                        siz = 32;
                else
                        siz = wpa_s->last_scan_res_size * 2;
                n = os_realloc_array(wpa_s->last_scan_res, siz,
                                     sizeof(struct wpa_bss *));
                if (n == NULL)
                        return;
                wpa_s->last_scan_res = n;
                wpa_s->last_scan_res_size = siz;
        }

        if (wpa_s->last_scan_res)
                wpa_s->last_scan_res[wpa_s->last_scan_res_used++] = bss;
}


static int wpa_bss_included_in_scan(const struct wpa_bss *bss,
                                    const struct scan_info *info)
{
        int found;
        size_t i;

        if (info == NULL)
                return 1;

        if (info->num_freqs) {
                found = 0;
                for (i = 0; i < info->num_freqs; i++) {
                        if (bss->freq == info->freqs[i]) {
                                found = 1;
                                break;
                        }
                }
                if (!found)
                        return 0;
        }

        if (info->num_ssids) {
                found = 0;
                for (i = 0; i < info->num_ssids; i++) {
                        const struct wpa_driver_scan_ssid *s = &info->ssids[i];
                        if ((s->ssid == NULL || s->ssid_len == 0) ||
                            (s->ssid_len == bss->ssid_len &&
                             os_memcmp(s->ssid, bss->ssid, bss->ssid_len) ==
                             0)) {
                                found = 1;
                                break;
                        }
                }
                if (!found)
                        return 0;
        }

        return 1;
}


/**
 * wpa_bss_update_end - End a BSS table update from scan results
 * @wpa_s: Pointer to wpa_supplicant data
 * @info: Information about scan parameters
 * @new_scan: Whether this update round was based on a new scan
 *
 * This function is called at the end of each BSS table update round for new
 * scan results. The start of the update was indicated with a call to
 * wpa_bss_update_start().
 */
void wpa_bss_update_end(struct wpa_supplicant *wpa_s, struct scan_info *info,
                        int new_scan)
{
        struct wpa_bss *bss, *n;

        os_get_reltime(&wpa_s->last_scan);
        if ((info && info->aborted) || !new_scan)
                return; /* do not expire entries without new scan */

        dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list) {
                if (wpa_bss_in_use(wpa_s, bss))
                        continue;
                if (!wpa_bss_included_in_scan(bss, info))
                        continue; /* expire only BSSes that were scanned */
                if (bss->last_update_idx < wpa_s->bss_update_idx)
                        bss->scan_miss_count++;
                if (bss->scan_miss_count >=
                    wpa_s->conf->bss_expiration_scan_count) {
                        wpa_bss_remove(wpa_s, bss, "no match in scan");
                }
        }

        wpa_printf(MSG_DEBUG, "BSS: last_scan_res_used=%u/%u",
                   wpa_s->last_scan_res_used, wpa_s->last_scan_res_size);
}


/**
 * wpa_bss_flush_by_age - Flush old BSS entries
 * @wpa_s: Pointer to wpa_supplicant data
 * @age: Maximum entry age in seconds
 *
 * Remove BSS entries that have not been updated during the last @age seconds.
 */
void wpa_bss_flush_by_age(struct wpa_supplicant *wpa_s, int age)
{
        struct wpa_bss *bss, *n;
        struct os_reltime t;

        if (dl_list_empty(&wpa_s->bss))
                return;

        os_get_reltime(&t);
        t.sec -= age;

        dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list) {
                if (wpa_bss_in_use(wpa_s, bss))
                        continue;

                if (os_reltime_before(&bss->last_update, &t)) {
                        wpa_bss_remove(wpa_s, bss, __func__);
                } else
                        break;
        }
}


/**
 * wpa_bss_init - Initialize BSS table
 * @wpa_s: Pointer to wpa_supplicant data
 * Returns: 0 on success, -1 on failure
 *
 * This prepares BSS table lists and timer for periodic updates. The BSS table
 * is deinitialized with wpa_bss_deinit() once not needed anymore.
 */
int wpa_bss_init(struct wpa_supplicant *wpa_s)
{
        dl_list_init(&wpa_s->bss);
        dl_list_init(&wpa_s->bss_id);
        return 0;
}


/**
 * wpa_bss_flush - Flush all unused BSS entries
 * @wpa_s: Pointer to wpa_supplicant data
 */
void wpa_bss_flush(struct wpa_supplicant *wpa_s)
{
        struct wpa_bss *bss, *n;

        wpa_s->clear_driver_scan_cache = 1;

        if (wpa_s->bss.next == NULL)
                return; /* BSS table not yet initialized */

        dl_list_for_each_safe(bss, n, &wpa_s->bss, struct wpa_bss, list) {
                if (wpa_bss_in_use(wpa_s, bss))
                        continue;
                wpa_bss_remove(wpa_s, bss, __func__);
        }
}


/**
 * wpa_bss_deinit - Deinitialize BSS table
 * @wpa_s: Pointer to wpa_supplicant data
 */
void wpa_bss_deinit(struct wpa_supplicant *wpa_s)
{
        wpa_bss_flush(wpa_s);
}


/**
 * wpa_bss_get_bssid - Fetch a BSS table entry based on BSSID
 * @wpa_s: Pointer to wpa_supplicant data
 * @bssid: BSSID
 * Returns: Pointer to the BSS entry or %NULL if not found
 */
struct wpa_bss * wpa_bss_get_bssid(struct wpa_supplicant *wpa_s,
                                   const u8 *bssid)
{
        struct wpa_bss *bss;
        if (!wpa_supplicant_filter_bssid_match(wpa_s, bssid))
                return NULL;
        dl_list_for_each_reverse(bss, &wpa_s->bss, struct wpa_bss, list) {
                if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
                        return bss;
        }
        return NULL;
}


/**
 * wpa_bss_get_bssid_latest - Fetch the latest BSS table entry based on BSSID
 * @wpa_s: Pointer to wpa_supplicant data
 * @bssid: BSSID
 * Returns: Pointer to the BSS entry or %NULL if not found
 *
 * This function is like wpa_bss_get_bssid(), but full BSS table is iterated to
 * find the entry that has the most recent update. This can help in finding the
 * correct entry in cases where the SSID of the AP may have changed recently
 * (e.g., in WPS reconfiguration cases).
 */
struct wpa_bss * wpa_bss_get_bssid_latest(struct wpa_supplicant *wpa_s,
                                          const u8 *bssid)
{
        struct wpa_bss *bss, *found = NULL;
        if (!wpa_supplicant_filter_bssid_match(wpa_s, bssid))
                return NULL;
        dl_list_for_each_reverse(bss, &wpa_s->bss, struct wpa_bss, list) {
                if (os_memcmp(bss->bssid, bssid, ETH_ALEN) != 0)
                        continue;
                if (found == NULL ||
                    os_reltime_before(&found->last_update, &bss->last_update))
                        found = bss;
        }
        return found;
}


#ifdef CONFIG_P2P
/**
 * wpa_bss_get_p2p_dev_addr - Fetch a BSS table entry based on P2P Device Addr
 * @wpa_s: Pointer to wpa_supplicant data
 * @dev_addr: P2P Device Address of the GO
 * Returns: Pointer to the BSS entry or %NULL if not found
 */
struct wpa_bss * wpa_bss_get_p2p_dev_addr(struct wpa_supplicant *wpa_s,
                                          const u8 *dev_addr)
{
        struct wpa_bss *bss;
        dl_list_for_each_reverse(bss, &wpa_s->bss, struct wpa_bss, list) {
                u8 addr[ETH_ALEN];
                if (p2p_parse_dev_addr((const u8 *) (bss + 1), bss->ie_len,
                                       addr) == 0 &&
                    os_memcmp(addr, dev_addr, ETH_ALEN) == 0)
                        return bss;
        }
        return NULL;
}
#endif /* CONFIG_P2P */


/**
 * wpa_bss_get_id - Fetch a BSS table entry based on identifier
 * @wpa_s: Pointer to wpa_supplicant data
 * @id: Unique identifier (struct wpa_bss::id) assigned for the entry
 * Returns: Pointer to the BSS entry or %NULL if not found
 */
struct wpa_bss * wpa_bss_get_id(struct wpa_supplicant *wpa_s, unsigned int id)
{
        struct wpa_bss *bss;
        dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
                if (bss->id == id)
                        return bss;
        }
        return NULL;
}


/**
 * wpa_bss_get_id_range - Fetch a BSS table entry based on identifier range
 * @wpa_s: Pointer to wpa_supplicant data
 * @idf: Smallest allowed identifier assigned for the entry
 * @idf: Largest allowed identifier assigned for the entry
 * Returns: Pointer to the BSS entry or %NULL if not found
 *
 * This function is similar to wpa_bss_get_id() but allows a BSS entry with the
 * smallest id value to be fetched within the specified range without the
 * caller having to know the exact id.
 */
struct wpa_bss * wpa_bss_get_id_range(struct wpa_supplicant *wpa_s,
                                      unsigned int idf, unsigned int idl)
{
        struct wpa_bss *bss;
        dl_list_for_each(bss, &wpa_s->bss_id, struct wpa_bss, list_id) {
                if (bss->id >= idf && bss->id <= idl)
                        return bss;
        }
        return NULL;
}


/**
 * wpa_bss_get_ie - Fetch a specified information element from a BSS entry
 * @bss: BSS table 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 BSS
 * entry.
 */
const u8 * wpa_bss_get_ie(const struct wpa_bss *bss, u8 ie)
{
        return get_ie((const u8 *) (bss + 1), bss->ie_len, ie);
}


/**
 * wpa_bss_get_vendor_ie - Fetch a vendor information element from a BSS entry
 * @bss: BSS table 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 BSS
 * entry.
 */
const u8 * wpa_bss_get_vendor_ie(const struct wpa_bss *bss, u32 vendor_type)
{
        const u8 *end, *pos;

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

        while (end - pos > 1) {
                if (2 + pos[1] > end - pos)
                        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_bss_get_vendor_ie_beacon - Fetch a vendor information from a BSS entry
 * @bss: BSS table 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 BSS
 * entry.
 *
 * This function is like wpa_bss_get_vendor_ie(), but uses IE buffer only
 * from Beacon frames instead of either Beacon or Probe Response frames.
 */
const u8 * wpa_bss_get_vendor_ie_beacon(const struct wpa_bss *bss,
                                        u32 vendor_type)
{
        const u8 *end, *pos;

        if (bss->beacon_ie_len == 0)
                return NULL;

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

        while (end - pos > 1) {
                if (2 + pos[1] > end - pos)
                        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_bss_get_vendor_ie_multi - Fetch vendor IE data from a BSS entry
 * @bss: BSS table 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 BSS entry. The caller is responsible for
 * freeing the returned buffer.
 */
struct wpabuf * wpa_bss_get_vendor_ie_multi(const struct wpa_bss *bss,
                                            u32 vendor_type)
{
        struct wpabuf *buf;
        const u8 *end, *pos;

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

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

        while (end - pos > 1) {
                if (2 + pos[1] > end - pos)
                        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;
}


/**
 * wpa_bss_get_vendor_ie_multi_beacon - Fetch vendor IE data from a BSS entry
 * @bss: BSS table 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 BSS entry. The caller is responsible for
 * freeing the returned buffer.
 *
 * This function is like wpa_bss_get_vendor_ie_multi(), but uses IE buffer only
 * from Beacon frames instead of either Beacon or Probe Response frames.
 */
struct wpabuf * wpa_bss_get_vendor_ie_multi_beacon(const struct wpa_bss *bss,
                                                   u32 vendor_type)
{
        struct wpabuf *buf;
        const u8 *end, *pos;

        buf = wpabuf_alloc(bss->beacon_ie_len);
        if (buf == NULL)
                return NULL;

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

        while (end - pos > 1) {
                if (2 + pos[1] > end - pos)
                        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;
}


/**
 * wpa_bss_get_max_rate - Get maximum legacy TX rate supported in a BSS
 * @bss: BSS table entry
 * Returns: Maximum legacy rate in units of 500 kbps
 */
int wpa_bss_get_max_rate(const struct wpa_bss *bss)
{
        int rate = 0;
        const u8 *ie;
        int i;

        ie = wpa_bss_get_ie(bss, 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_bss_get_ie(bss, 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_bss_get_bit_rates - Get legacy TX rates supported in a BSS
 * @bss: BSS table entry
 * @rates: Buffer for returning a pointer to the rates list (units of 500 kbps)
 * Returns: number of legacy TX rates or -1 on failure
 *
 * The caller is responsible for freeing the returned buffer with os_free() in
 * case of success.
 */
int wpa_bss_get_bit_rates(const struct wpa_bss *bss, u8 **rates)
{
        const u8 *ie, *ie2;
        int i, j;
        unsigned int len;
        u8 *r;

        ie = wpa_bss_get_ie(bss, WLAN_EID_SUPP_RATES);
        ie2 = wpa_bss_get_ie(bss, WLAN_EID_EXT_SUPP_RATES);

        len = (ie ? ie[1] : 0) + (ie2 ? ie2[1] : 0);

        r = os_malloc(len);
        if (!r)
                return -1;

        for (i = 0; ie && i < ie[1]; i++)
                r[i] = ie[i + 2] & 0x7f;

        for (j = 0; ie2 && j < ie2[1]; j++)
                r[i + j] = ie2[j + 2] & 0x7f;

        *rates = r;
        return len;
}