bss.c

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/*
 * BSS table
 * Copyright (c) 2009-2010, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING 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 "wpa_supplicant_i.h"
#include "config.h"
#include "notify.h"
#include "scan.h"
#include "bss.h"


#define WPA_BSS_EXPIRATION_PERIOD 10

#define WPA_BSS_EXPIRATION_AGE 180

#define WPA_BSS_EXPIRATION_SCAN_COUNT 2

#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_remove(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
{
        dl_list_del(&bss->list);
        dl_list_del(&bss->list_id);
        wpa_s->num_bss--;
        wpa_printf(MSG_DEBUG, "BSS: Remove id %u BSSID " MACSTR " SSID '%s'",
                   bss->id, MAC2STR(bss->bssid),
                   wpa_ssid_txt(bss->ssid, bss->ssid_len));
        wpas_notify_bss_removed(wpa_s, bss->bssid, bss->id);
        os_free(bss);
}


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;
        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 wpa_bss_copy_res(struct wpa_bss *dst, struct wpa_scan_res *src)
{
        os_time_t usec;

        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;

        os_get_time(&dst->last_update);
        dst->last_update.sec -= src->age / 1000;
        usec = (src->age % 1000) * 1000;
        if (dst->last_update.usec < usec) {
                dst->last_update.sec--;
                dst->last_update.usec += 1000000;
        }
        dst->last_update.usec -= usec;
}


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

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

        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_printf(MSG_DEBUG, "BSS: Add new id %u BSSID " MACSTR " SSID '%s'",
                   bss->id, MAC2STR(bss->bssid), wpa_ssid_txt(ssid, ssid_len));
        wpas_notify_bss_added(wpa_s, bss->bssid, bss->id);
        if (wpa_s->num_bss > wpa_s->conf->bss_max_count) {
                /* Remove the oldest entry */
                wpa_bss_remove(wpa_s, dl_list_first(&wpa_s->bss,
                                                    struct wpa_bss, list));
        }
}


static int are_ies_equal(const struct wpa_bss *old,
                         const struct wpa_scan_res *new, 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, 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, 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, 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;
        }

        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)
{
        u32 changes = 0;
        int caps_diff = old->caps ^ new->caps;

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

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

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

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

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

        if (!are_ies_equal(old, new, WLAN_EID_SUPP_RATES) ||
            !are_ies_equal(old, new, 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);
}


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

        changes = wpa_bss_compare_res(bss, res);
        bss->scan_miss_count = 0;
        bss->last_update_idx = wpa_s->bss_update_idx;
        wpa_bss_copy_res(bss, res);
        /* Move the entry to the end of the list */
        dl_list_del(&bss->list);
        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) {
                        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);
        }
        dl_list_add_tail(&wpa_s->bss, &bss->list);

        notify_bss_changes(wpa_s, changes, bss);
}


static int wpa_bss_in_use(struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
{
        return bss == wpa_s->current_bss ||
                os_memcmp(bss->bssid, wpa_s->bssid, ETH_ALEN) == 0 ||
                os_memcmp(bss->bssid, wpa_s->pending_bssid, ETH_ALEN) == 0;
}


void wpa_bss_update_start(struct wpa_supplicant *wpa_s)
{
        wpa_s->bss_update_idx++;
        wpa_printf(MSG_DEBUG, "BSS: Start scan result update %u",
                   wpa_s->bss_update_idx);
}


void wpa_bss_update_scan_res(struct wpa_supplicant *wpa_s,
                             struct wpa_scan_res *res)
{
        const u8 *ssid;
        struct wpa_bss *bss;

        ssid = wpa_scan_get_ie(res, WLAN_EID_SSID);
        if (ssid == NULL) {
                wpa_printf(MSG_DEBUG, "BSS: No SSID IE included for " MACSTR,
                           MAC2STR(res->bssid));
                return;
        }
        if (ssid[1] > 32) {
                wpa_printf(MSG_DEBUG, "BSS: Too long SSID IE included for "
                           MACSTR, MAC2STR(res->bssid));
                return;
        }

        /* TODO: add option for ignoring BSSes we are not interested in
         * (to save memory) */
        bss = wpa_bss_get(wpa_s, res->bssid, ssid + 2, ssid[1]);
        if (bss == NULL)
                wpa_bss_add(wpa_s, ssid + 2, ssid[1], res);
        else
                wpa_bss_update(wpa_s, bss, res);
}


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;
}


void wpa_bss_update_end(struct wpa_supplicant *wpa_s, struct scan_info *info,
                        int new_scan)
{
        struct wpa_bss *bss, *n;

        if (!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_BSS_EXPIRATION_SCAN_COUNT) {
                        wpa_printf(MSG_DEBUG, "BSS: Expire BSS %u due to no "
                                   "match in scan", bss->id);
                        wpa_bss_remove(wpa_s, bss);
                }
        }
}


static void wpa_bss_timeout(void *eloop_ctx, void *timeout_ctx)
{
        struct wpa_supplicant *wpa_s = eloop_ctx;
        struct wpa_bss *bss, *n;
        struct os_time t;

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

        os_get_time(&t);
        t.sec -= WPA_BSS_EXPIRATION_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_time_before(&bss->last_update, &t)) {
                        wpa_printf(MSG_DEBUG, "BSS: Expire BSS %u due to age",
                                   bss->id);
                        wpa_bss_remove(wpa_s, bss);
                } else
                        break;
        }
        eloop_register_timeout(WPA_BSS_EXPIRATION_PERIOD, 0,
                               wpa_bss_timeout, wpa_s, NULL);
}


int wpa_bss_init(struct wpa_supplicant *wpa_s)
{
        dl_list_init(&wpa_s->bss);
        dl_list_init(&wpa_s->bss_id);
        eloop_register_timeout(WPA_BSS_EXPIRATION_PERIOD, 0,
                               wpa_bss_timeout, wpa_s, NULL);
        return 0;
}


void wpa_bss_deinit(struct wpa_supplicant *wpa_s)
{
        struct wpa_bss *bss, *n;
        eloop_cancel_timeout(wpa_bss_timeout, wpa_s, NULL);
        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)
                wpa_bss_remove(wpa_s, bss);
}


struct wpa_bss * wpa_bss_get_bssid(struct wpa_supplicant *wpa_s,
                                   const u8 *bssid)
{
        struct wpa_bss *bss;
        dl_list_for_each(bss, &wpa_s->bss, struct wpa_bss, list) {
                if (os_memcmp(bss->bssid, bssid, ETH_ALEN) == 0)
                        return bss;
        }
        return NULL;
}


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;
}


const u8 * wpa_bss_get_ie(const struct wpa_bss *bss, u8 ie)
{
        const u8 *end, *pos;

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


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 (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;
}


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 (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;
}


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;
}


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;
}