ap_list.c

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/*
 * hostapd / AP table
 * Copyright (c) 2002-2009, Jouni Malinen <j@w1.fi>
 * Copyright (c) 2003-2004, Instant802 Networks, Inc.
 * Copyright (c) 2006, Devicescape Software, Inc.
 *
 * 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 "common/ieee802_11_common.h"
#include "drivers/driver.h"
#include "hostapd.h"
#include "ap_config.h"
#include "ieee802_11.h"
#include "sta_info.h"
#include "beacon.h"
#include "ap_list.h"


/* AP list is a double linked list with head->prev pointing to the end of the
 * list and tail->next = NULL. Entries are moved to the head of the list
 * whenever a beacon has been received from the AP in question. The tail entry
 * in this link will thus be the least recently used entry. */


static int ap_list_beacon_olbc(struct hostapd_iface *iface, struct ap_info *ap)
{
        int i;

        if (iface->current_mode->mode != HOSTAPD_MODE_IEEE80211G ||
            iface->conf->channel != ap->channel)
                return 0;

        if (ap->erp != -1 && (ap->erp & ERP_INFO_NON_ERP_PRESENT))
                return 1;

        for (i = 0; i < WLAN_SUPP_RATES_MAX; i++) {
                int rate = (ap->supported_rates[i] & 0x7f) * 5;
                if (rate == 60 || rate == 90 || rate > 110)
                        return 0;
        }

        return 1;
}


struct ap_info * ap_get_ap(struct hostapd_iface *iface, const u8 *ap)
{
        struct ap_info *s;

        s = iface->ap_hash[STA_HASH(ap)];
        while (s != NULL && os_memcmp(s->addr, ap, ETH_ALEN) != 0)
                s = s->hnext;
        return s;
}


static void ap_ap_list_add(struct hostapd_iface *iface, struct ap_info *ap)
{
        if (iface->ap_list) {
                ap->prev = iface->ap_list->prev;
                iface->ap_list->prev = ap;
        } else
                ap->prev = ap;
        ap->next = iface->ap_list;
        iface->ap_list = ap;
}


static void ap_ap_list_del(struct hostapd_iface *iface, struct ap_info *ap)
{
        if (iface->ap_list == ap)
                iface->ap_list = ap->next;
        else
                ap->prev->next = ap->next;

        if (ap->next)
                ap->next->prev = ap->prev;
        else if (iface->ap_list)
                iface->ap_list->prev = ap->prev;
}


static void ap_ap_iter_list_add(struct hostapd_iface *iface,
                                struct ap_info *ap)
{
        if (iface->ap_iter_list) {
                ap->iter_prev = iface->ap_iter_list->iter_prev;
                iface->ap_iter_list->iter_prev = ap;
        } else
                ap->iter_prev = ap;
        ap->iter_next = iface->ap_iter_list;
        iface->ap_iter_list = ap;
}


static void ap_ap_iter_list_del(struct hostapd_iface *iface,
                                struct ap_info *ap)
{
        if (iface->ap_iter_list == ap)
                iface->ap_iter_list = ap->iter_next;
        else
                ap->iter_prev->iter_next = ap->iter_next;

        if (ap->iter_next)
                ap->iter_next->iter_prev = ap->iter_prev;
        else if (iface->ap_iter_list)
                iface->ap_iter_list->iter_prev = ap->iter_prev;
}


static void ap_ap_hash_add(struct hostapd_iface *iface, struct ap_info *ap)
{
        ap->hnext = iface->ap_hash[STA_HASH(ap->addr)];
        iface->ap_hash[STA_HASH(ap->addr)] = ap;
}


static void ap_ap_hash_del(struct hostapd_iface *iface, struct ap_info *ap)
{
        struct ap_info *s;

        s = iface->ap_hash[STA_HASH(ap->addr)];
        if (s == NULL) return;
        if (os_memcmp(s->addr, ap->addr, ETH_ALEN) == 0) {
                iface->ap_hash[STA_HASH(ap->addr)] = s->hnext;
                return;
        }

        while (s->hnext != NULL &&
               os_memcmp(s->hnext->addr, ap->addr, ETH_ALEN) != 0)
                s = s->hnext;
        if (s->hnext != NULL)
                s->hnext = s->hnext->hnext;
        else
                printf("AP: could not remove AP " MACSTR " from hash table\n",
                       MAC2STR(ap->addr));
}


static void ap_free_ap(struct hostapd_iface *iface, struct ap_info *ap)
{
        ap_ap_hash_del(iface, ap);
        ap_ap_list_del(iface, ap);
        ap_ap_iter_list_del(iface, ap);

        iface->num_ap--;
        os_free(ap);
}


static void hostapd_free_aps(struct hostapd_iface *iface)
{
        struct ap_info *ap, *prev;

        ap = iface->ap_list;

        while (ap) {
                prev = ap;
                ap = ap->next;
                ap_free_ap(iface, prev);
        }

        iface->ap_list = NULL;
}


int ap_ap_for_each(struct hostapd_iface *iface,
                   int (*func)(struct ap_info *s, void *data), void *data)
{
        struct ap_info *s;
        int ret = 0;

        s = iface->ap_list;

        while (s) {
                ret = func(s, data);
                if (ret)
                        break;
                s = s->next;
        }

        return ret;
}


static struct ap_info * ap_ap_add(struct hostapd_iface *iface, const u8 *addr)
{
        struct ap_info *ap;

        ap = os_zalloc(sizeof(struct ap_info));
        if (ap == NULL)
                return NULL;

        /* initialize AP info data */
        os_memcpy(ap->addr, addr, ETH_ALEN);
        ap_ap_list_add(iface, ap);
        iface->num_ap++;
        ap_ap_hash_add(iface, ap);
        ap_ap_iter_list_add(iface, ap);

        if (iface->num_ap > iface->conf->ap_table_max_size && ap != ap->prev) {
                wpa_printf(MSG_DEBUG, "Removing the least recently used AP "
                           MACSTR " from AP table", MAC2STR(ap->prev->addr));
                ap_free_ap(iface, ap->prev);
        }

        return ap;
}


void ap_list_process_beacon(struct hostapd_iface *iface,
                            const struct ieee80211_mgmt *mgmt,
                            struct ieee802_11_elems *elems,
                            struct hostapd_frame_info *fi)
{
        struct ap_info *ap;
        int new_ap = 0;
        size_t len;
        int set_beacon = 0;

        if (iface->conf->ap_table_max_size < 1)
                return;

        ap = ap_get_ap(iface, mgmt->bssid);
        if (!ap) {
                ap = ap_ap_add(iface, mgmt->bssid);
                if (!ap) {
                        printf("Failed to allocate AP information entry\n");
                        return;
                }
                new_ap = 1;
        }

        ap->beacon_int = le_to_host16(mgmt->u.beacon.beacon_int);
        ap->capability = le_to_host16(mgmt->u.beacon.capab_info);

        if (elems->ssid) {
                len = elems->ssid_len;
                if (len >= sizeof(ap->ssid))
                        len = sizeof(ap->ssid) - 1;
                os_memcpy(ap->ssid, elems->ssid, len);
                ap->ssid[len] = '\0';
                ap->ssid_len = len;
        }

        os_memset(ap->supported_rates, 0, WLAN_SUPP_RATES_MAX);
        len = 0;
        if (elems->supp_rates) {
                len = elems->supp_rates_len;
                if (len > WLAN_SUPP_RATES_MAX)
                        len = WLAN_SUPP_RATES_MAX;
                os_memcpy(ap->supported_rates, elems->supp_rates, len);
        }
        if (elems->ext_supp_rates) {
                int len2;
                if (len + elems->ext_supp_rates_len > WLAN_SUPP_RATES_MAX)
                        len2 = WLAN_SUPP_RATES_MAX - len;
                else
                        len2 = elems->ext_supp_rates_len;
                os_memcpy(ap->supported_rates + len, elems->ext_supp_rates,
                          len2);
        }

        ap->wpa = elems->wpa_ie != NULL;

        if (elems->erp_info && elems->erp_info_len == 1)
                ap->erp = elems->erp_info[0];
        else
                ap->erp = -1;

        if (elems->ds_params && elems->ds_params_len == 1)
                ap->channel = elems->ds_params[0];
        else if (fi)
                ap->channel = fi->channel;

        if (elems->ht_capabilities)
                ap->ht_support = 1;
        else
                ap->ht_support = 0;

        ap->num_beacons++;
        time(&ap->last_beacon);
        if (fi) {
                ap->ssi_signal = fi->ssi_signal;
                ap->datarate = fi->datarate;
        }

        if (!new_ap && ap != iface->ap_list) {
                /* move AP entry into the beginning of the list so that the
                 * oldest entry is always in the end of the list */
                ap_ap_list_del(iface, ap);
                ap_ap_list_add(iface, ap);
        }

        if (!iface->olbc &&
            ap_list_beacon_olbc(iface, ap)) {
                iface->olbc = 1;
                wpa_printf(MSG_DEBUG, "OLBC AP detected: " MACSTR " - enable "
                           "protection", MAC2STR(ap->addr));
                set_beacon++;
        }

#ifdef CONFIG_IEEE80211N
        if (!iface->olbc_ht && !ap->ht_support) {
                iface->olbc_ht = 1;
                hostapd_ht_operation_update(iface);
                wpa_printf(MSG_DEBUG, "OLBC HT AP detected: " MACSTR
                           " - enable protection", MAC2STR(ap->addr));
                set_beacon++;
        }
#endif /* CONFIG_IEEE80211N */

        if (set_beacon)
                ieee802_11_set_beacons(iface);
}


static void ap_list_timer(void *eloop_ctx, void *timeout_ctx)
{
        struct hostapd_iface *iface = eloop_ctx;
        time_t now;
        struct ap_info *ap;
        int set_beacon = 0;

        eloop_register_timeout(10, 0, ap_list_timer, iface, NULL);

        if (!iface->ap_list)
                return;

        time(&now);

        while (iface->ap_list) {
                ap = iface->ap_list->prev;
                if (ap->last_beacon + iface->conf->ap_table_expiration_time >=
                    now)
                        break;

                ap_free_ap(iface, ap);
        }

        if (iface->olbc || iface->olbc_ht) {
                int olbc = 0;
                int olbc_ht = 0;

                ap = iface->ap_list;
                while (ap && (olbc == 0 || olbc_ht == 0)) {
                        if (ap_list_beacon_olbc(iface, ap))
                                olbc = 1;
                        if (!ap->ht_support)
                                olbc_ht = 1;
                        ap = ap->next;
                }
                if (!olbc && iface->olbc) {
                        wpa_printf(MSG_DEBUG, "OLBC not detected anymore");
                        iface->olbc = 0;
                        set_beacon++;
                }
#ifdef CONFIG_IEEE80211N
                if (!olbc_ht && iface->olbc_ht) {
                        wpa_printf(MSG_DEBUG, "OLBC HT not detected anymore");
                        iface->olbc_ht = 0;
                        hostapd_ht_operation_update(iface);
                        set_beacon++;
                }
#endif /* CONFIG_IEEE80211N */
        }

        if (set_beacon)
                ieee802_11_set_beacons(iface);
}


int ap_list_init(struct hostapd_iface *iface)
{
        eloop_register_timeout(10, 0, ap_list_timer, iface, NULL);
        return 0;
}


void ap_list_deinit(struct hostapd_iface *iface)
{
        eloop_cancel_timeout(ap_list_timer, iface, NULL);
        hostapd_free_aps(iface);
}