/*
 * IBSS mode implementation
 * Copyright 2003-2008, Jouni Malinen <j@w1.fi>
 * Copyright 2004, Instant802 Networks, Inc.
 * Copyright 2005, Devicescape Software, Inc.
 * Copyright 2006-2007  Jiri Benc <jbenc@suse.cz>
 * Copyright 2007, Michael Wu <flamingice@sourmilk.net>
 * Copyright 2009, Johannes Berg <johannes@sipsolutions.net>
 *
 * 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.
 */

#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/if_ether.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/etherdevice.h>
#include <linux/rtnetlink.h>
#include <net/mac80211.h>

#include "ieee80211_i.h"
#include "driver-ops.h"
#include "rate.h"

#define IEEE80211_SCAN_INTERVAL (2 * HZ)
#define IEEE80211_SCAN_INTERVAL_SLOW (15 * HZ)
#define IEEE80211_IBSS_JOIN_TIMEOUT (7 * HZ)

#define IEEE80211_IBSS_MERGE_INTERVAL (30 * HZ)
#define IEEE80211_IBSS_INACTIVITY_LIMIT (60 * HZ)

#define IEEE80211_IBSS_MAX_STA_ENTRIES 128


static void __ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
                                      const u8 *bssid, const int beacon_int,
                                      struct ieee80211_channel *chan,
                                      const u32 basic_rates,
                                      const u16 capability, u64 tsf)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        int rates, i;
        struct sk_buff *skb;
        struct ieee80211_mgmt *mgmt;
        u8 *pos;
        struct ieee80211_supported_band *sband;
        struct cfg80211_bss *bss;
        u32 bss_change;
        u8 supp_rates[IEEE80211_MAX_SUPP_RATES];
        enum nl80211_channel_type channel_type;

        lockdep_assert_held(&ifibss->mtx);

        /* Reset own TSF to allow time synchronization work. */
        drv_reset_tsf(local, sdata);

        skb = ifibss->skb;
        RCU_INIT_POINTER(ifibss->presp, NULL);
        synchronize_rcu();
        skb->data = skb->head;
        skb->len = 0;
        skb_reset_tail_pointer(skb);
        skb_reserve(skb, sdata->local->hw.extra_tx_headroom);

        if (!ether_addr_equal(ifibss->bssid, bssid))
                sta_info_flush(sdata->local, sdata);

        /* if merging, indicate to driver that we leave the old IBSS */
        if (sdata->vif.bss_conf.ibss_joined) {
                sdata->vif.bss_conf.ibss_joined = false;
                netif_carrier_off(sdata->dev);
                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IBSS);
        }

        memcpy(ifibss->bssid, bssid, ETH_ALEN);

        sdata->drop_unencrypted = capability & WLAN_CAPABILITY_PRIVACY ? 1 : 0;

        local->oper_channel = chan;
        channel_type = ifibss->channel_type;
        if (!cfg80211_can_beacon_sec_chan(local->hw.wiphy, chan, channel_type))
                channel_type = NL80211_CHAN_HT20;
        if (!ieee80211_set_channel_type(local, sdata, channel_type)) {
                /* can only fail due to HT40+/- mismatch */
                channel_type = NL80211_CHAN_HT20;
                WARN_ON(!ieee80211_set_channel_type(local, sdata,
                                                    NL80211_CHAN_HT20));
        }
        ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);

        sband = local->hw.wiphy->bands[chan->band];

        /* build supported rates array */
        pos = supp_rates;
        for (i = 0; i < sband->n_bitrates; i++) {
                int rate = sband->bitrates[i].bitrate;
                u8 basic = 0;
                if (basic_rates & BIT(i))
                        basic = 0x80;
                *pos++ = basic | (u8) (rate / 5);
        }

        /* Build IBSS probe response */
        mgmt = (void *) skb_put(skb, 24 + sizeof(mgmt->u.beacon));
        memset(mgmt, 0, 24 + sizeof(mgmt->u.beacon));
        mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                          IEEE80211_STYPE_PROBE_RESP);
        eth_broadcast_addr(mgmt->da);
        memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
        memcpy(mgmt->bssid, ifibss->bssid, ETH_ALEN);
        mgmt->u.beacon.beacon_int = cpu_to_le16(beacon_int);
        mgmt->u.beacon.timestamp = cpu_to_le64(tsf);
        mgmt->u.beacon.capab_info = cpu_to_le16(capability);

        pos = skb_put(skb, 2 + ifibss->ssid_len);
        *pos++ = WLAN_EID_SSID;
        *pos++ = ifibss->ssid_len;
        memcpy(pos, ifibss->ssid, ifibss->ssid_len);

        rates = sband->n_bitrates;
        if (rates > 8)
                rates = 8;
        pos = skb_put(skb, 2 + rates);
        *pos++ = WLAN_EID_SUPP_RATES;
        *pos++ = rates;
        memcpy(pos, supp_rates, rates);

        if (sband->band == IEEE80211_BAND_2GHZ) {
                pos = skb_put(skb, 2 + 1);
                *pos++ = WLAN_EID_DS_PARAMS;
                *pos++ = 1;
                *pos++ = ieee80211_frequency_to_channel(chan->center_freq);
        }

        pos = skb_put(skb, 2 + 2);
        *pos++ = WLAN_EID_IBSS_PARAMS;
        *pos++ = 2;
        /* FIX: set ATIM window based on scan results */
        *pos++ = 0;
        *pos++ = 0;

        if (sband->n_bitrates > 8) {
                rates = sband->n_bitrates - 8;
                pos = skb_put(skb, 2 + rates);
                *pos++ = WLAN_EID_EXT_SUPP_RATES;
                *pos++ = rates;
                memcpy(pos, &supp_rates[8], rates);
        }

        if (ifibss->ie_len)
                memcpy(skb_put(skb, ifibss->ie_len),
                       ifibss->ie, ifibss->ie_len);

        /* add HT capability and information IEs */
        if (channel_type && sband->ht_cap.ht_supported) {
                pos = skb_put(skb, 4 +
                                   sizeof(struct ieee80211_ht_cap) +
                                   sizeof(struct ieee80211_ht_operation));
                pos = ieee80211_ie_build_ht_cap(pos, &sband->ht_cap,
                                                sband->ht_cap.cap);
                /*
                 * Note: According to 802.11n-2009 9.13.3.1, HT Protection
                 * field and RIFS Mode are reserved in IBSS mode, therefore
                 * keep them at 0
                 */
                pos = ieee80211_ie_build_ht_oper(pos, &sband->ht_cap,
                                                 chan, channel_type, 0);
        }

        if (local->hw.queues >= IEEE80211_NUM_ACS) {
                pos = skb_put(skb, 9);
                *pos++ = WLAN_EID_VENDOR_SPECIFIC;
                *pos++ = 7; /* len */
                *pos++ = 0x00; /* Microsoft OUI 00:50:F2 */
                *pos++ = 0x50;
                *pos++ = 0xf2;
                *pos++ = 2; /* WME */
                *pos++ = 0; /* WME info */
                *pos++ = 1; /* WME ver */
                *pos++ = 0; /* U-APSD no in use */
        }

        rcu_assign_pointer(ifibss->presp, skb);

        sdata->vif.bss_conf.beacon_int = beacon_int;
        sdata->vif.bss_conf.basic_rates = basic_rates;
        bss_change = BSS_CHANGED_BEACON_INT;
        bss_change |= ieee80211_reset_erp_info(sdata);
        bss_change |= BSS_CHANGED_BSSID;
        bss_change |= BSS_CHANGED_BEACON;
        bss_change |= BSS_CHANGED_BEACON_ENABLED;
        bss_change |= BSS_CHANGED_BASIC_RATES;
        bss_change |= BSS_CHANGED_HT;
        bss_change |= BSS_CHANGED_IBSS;
        sdata->vif.bss_conf.ibss_joined = true;
        ieee80211_bss_info_change_notify(sdata, bss_change);

        ieee80211_sta_def_wmm_params(sdata, sband->n_bitrates, supp_rates);

        ifibss->state = IEEE80211_IBSS_MLME_JOINED;
        mod_timer(&ifibss->timer,
                  round_jiffies(jiffies + IEEE80211_IBSS_MERGE_INTERVAL));

        bss = cfg80211_inform_bss_frame(local->hw.wiphy, chan,
                                        mgmt, skb->len, 0, GFP_KERNEL);
        cfg80211_put_bss(bss);
        netif_carrier_on(sdata->dev);
        cfg80211_ibss_joined(sdata->dev, ifibss->bssid, GFP_KERNEL);
}

static void ieee80211_sta_join_ibss(struct ieee80211_sub_if_data *sdata,
                                    struct ieee80211_bss *bss)
{
        struct cfg80211_bss *cbss =
                container_of((void *)bss, struct cfg80211_bss, priv);
        struct ieee80211_supported_band *sband;
        u32 basic_rates;
        int i, j;
        u16 beacon_int = cbss->beacon_interval;

        lockdep_assert_held(&sdata->u.ibss.mtx);

        if (beacon_int < 10)
                beacon_int = 10;

        sband = sdata->local->hw.wiphy->bands[cbss->channel->band];

        basic_rates = 0;

        for (i = 0; i < bss->supp_rates_len; i++) {
                int rate = (bss->supp_rates[i] & 0x7f) * 5;
                bool is_basic = !!(bss->supp_rates[i] & 0x80);

                for (j = 0; j < sband->n_bitrates; j++) {
                        if (sband->bitrates[j].bitrate == rate) {
                                if (is_basic)
                                        basic_rates |= BIT(j);
                                break;
                        }
                }
        }

        __ieee80211_sta_join_ibss(sdata, cbss->bssid,
                                  beacon_int,
                                  cbss->channel,
                                  basic_rates,
                                  cbss->capability,
                                  cbss->tsf);
}

static struct sta_info *ieee80211_ibss_finish_sta(struct sta_info *sta,
                                                  bool auth)
        __acquires(RCU)
{
        struct ieee80211_sub_if_data *sdata = sta->sdata;
        u8 addr[ETH_ALEN];

        memcpy(addr, sta->sta.addr, ETH_ALEN);

        ibss_dbg(sdata, "Adding new IBSS station %pM\n", addr);

        sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
        sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
        /* authorize the station only if the network is not RSN protected. If
         * not wait for the userspace to authorize it */
        if (!sta->sdata->u.ibss.control_port)
                sta_info_pre_move_state(sta, IEEE80211_STA_AUTHORIZED);

        rate_control_rate_init(sta);

        /* If it fails, maybe we raced another insertion? */
        if (sta_info_insert_rcu(sta))
                return sta_info_get(sdata, addr);
        if (auth && !sdata->u.ibss.auth_frame_registrations) {
                ibss_dbg(sdata,
                         "TX Auth SA=%pM DA=%pM BSSID=%pM (auth_transaction=1)\n",
                         sdata->vif.addr, addr, sdata->u.ibss.bssid);
                ieee80211_send_auth(sdata, 1, WLAN_AUTH_OPEN, NULL, 0,
                                    addr, sdata->u.ibss.bssid, NULL, 0, 0);
        }
        return sta;
}

static struct sta_info *
ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
                       const u8 *bssid, const u8 *addr,
                       u32 supp_rates, bool auth)
        __acquires(RCU)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;
        int band = local->oper_channel->band;

        /*
         * XXX: Consider removing the least recently used entry and
         *      allow new one to be added.
         */
        if (local->num_sta >= IEEE80211_IBSS_MAX_STA_ENTRIES) {
                net_info_ratelimited("%s: No room for a new IBSS STA entry %pM\n",
                                    sdata->name, addr);
                rcu_read_lock();
                return NULL;
        }

        if (ifibss->state == IEEE80211_IBSS_MLME_SEARCH) {
                rcu_read_lock();
                return NULL;
        }

        if (!ether_addr_equal(bssid, sdata->u.ibss.bssid)) {
                rcu_read_lock();
                return NULL;
        }

        sta = sta_info_alloc(sdata, addr, GFP_KERNEL);
        if (!sta) {
                rcu_read_lock();
                return NULL;
        }

        sta->last_rx = jiffies;

        /* make sure mandatory rates are always added */
        sta->sta.supp_rates[band] = supp_rates |
                        ieee80211_mandatory_rates(local, band);

        return ieee80211_ibss_finish_sta(sta, auth);
}

static void ieee80211_rx_mgmt_deauth_ibss(struct ieee80211_sub_if_data *sdata,
                                          struct ieee80211_mgmt *mgmt,
                                          size_t len)
{
        u16 reason = le16_to_cpu(mgmt->u.deauth.reason_code);

        if (len < IEEE80211_DEAUTH_FRAME_LEN)
                return;

        ibss_dbg(sdata, "RX DeAuth SA=%pM DA=%pM BSSID=%pM (reason: %d)\n",
                 mgmt->sa, mgmt->da, mgmt->bssid, reason);
        sta_info_destroy_addr(sdata, mgmt->sa);
}

static void ieee80211_rx_mgmt_auth_ibss(struct ieee80211_sub_if_data *sdata,
                                        struct ieee80211_mgmt *mgmt,
                                        size_t len)
{
        u16 auth_alg, auth_transaction;
        struct sta_info *sta;
        u8 deauth_frame_buf[IEEE80211_DEAUTH_FRAME_LEN];

        lockdep_assert_held(&sdata->u.ibss.mtx);

        if (len < 24 + 6)
                return;

        auth_alg = le16_to_cpu(mgmt->u.auth.auth_alg);
        auth_transaction = le16_to_cpu(mgmt->u.auth.auth_transaction);

        if (auth_alg != WLAN_AUTH_OPEN || auth_transaction != 1)
                return;
        ibss_dbg(sdata,
                 "RX Auth SA=%pM DA=%pM BSSID=%pM (auth_transaction=%d)\n",
                 mgmt->sa, mgmt->da, mgmt->bssid, auth_transaction);
        sta_info_destroy_addr(sdata, mgmt->sa);
        sta = ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa, 0, false);
        rcu_read_unlock();

        /*
         * if we have any problem in allocating the new station, we reply with a
         * DEAUTH frame to tell the other end that we had a problem
         */
        if (!sta) {
                ieee80211_send_deauth_disassoc(sdata, sdata->u.ibss.bssid,
                                               IEEE80211_STYPE_DEAUTH,
                                               WLAN_REASON_UNSPECIFIED, true,
                                               deauth_frame_buf);
                return;
        }

        /*
         * IEEE 802.11 standard does not require authentication in IBSS
         * networks and most implementations do not seem to use it.
         * However, try to reply to authentication attempts if someone
         * has actually implemented this.
         */
        ieee80211_send_auth(sdata, 2, WLAN_AUTH_OPEN, NULL, 0,
                            mgmt->sa, sdata->u.ibss.bssid, NULL, 0, 0);
}

static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
                                  struct ieee80211_mgmt *mgmt,
                                  size_t len,
                                  struct ieee80211_rx_status *rx_status,
                                  struct ieee802_11_elems *elems,
                                  bool beacon)
{
        struct ieee80211_local *local = sdata->local;
        int freq;
        struct cfg80211_bss *cbss;
        struct ieee80211_bss *bss;
        struct sta_info *sta;
        struct ieee80211_channel *channel;
        u64 beacon_timestamp, rx_timestamp;
        u32 supp_rates = 0;
        enum ieee80211_band band = rx_status->band;
        struct ieee80211_supported_band *sband = local->hw.wiphy->bands[band];
        bool rates_updated = false;

        if (elems->ds_params && elems->ds_params_len == 1)
                freq = ieee80211_channel_to_frequency(elems->ds_params[0],
                                                      band);
        else
                freq = rx_status->freq;

        channel = ieee80211_get_channel(local->hw.wiphy, freq);

        if (!channel || channel->flags & IEEE80211_CHAN_DISABLED)
                return;

        if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
            ether_addr_equal(mgmt->bssid, sdata->u.ibss.bssid)) {

                rcu_read_lock();
                sta = sta_info_get(sdata, mgmt->sa);

                if (elems->supp_rates) {
                        supp_rates = ieee80211_sta_get_rates(local, elems,
                                                             band, NULL);
                        if (sta) {
                                u32 prev_rates;

                                prev_rates = sta->sta.supp_rates[band];
                                /* make sure mandatory rates are always added */
                                sta->sta.supp_rates[band] = supp_rates |
                                        ieee80211_mandatory_rates(local, band);

                                if (sta->sta.supp_rates[band] != prev_rates) {
                                        ibss_dbg(sdata,
                                                 "updated supp_rates set for %pM based on beacon/probe_resp (0x%x -> 0x%x)\n",
                                                 sta->sta.addr, prev_rates,
                                                 sta->sta.supp_rates[band]);
                                        rates_updated = true;
                                }
                        } else {
                                rcu_read_unlock();
                                sta = ieee80211_ibss_add_sta(sdata, mgmt->bssid,
                                                mgmt->sa, supp_rates, true);
                        }
                }

                if (sta && elems->wmm_info)
                        set_sta_flag(sta, WLAN_STA_WME);

                if (sta && elems->ht_operation && elems->ht_cap_elem &&
                    sdata->u.ibss.channel_type != NL80211_CHAN_NO_HT) {
                        /* we both use HT */
                        struct ieee80211_sta_ht_cap sta_ht_cap_new;
                        enum nl80211_channel_type channel_type =
                                ieee80211_ht_oper_to_channel_type(
                                                        elems->ht_operation);

                        ieee80211_ht_cap_ie_to_sta_ht_cap(sdata, sband,
                                                          elems->ht_cap_elem,
                                                          &sta_ht_cap_new);

                        /*
                         * fall back to HT20 if we don't use or use
                         * the other extension channel
                         */
                        if (!(channel_type == NL80211_CHAN_HT40MINUS ||
                              channel_type == NL80211_CHAN_HT40PLUS) ||
                            channel_type != sdata->u.ibss.channel_type)
                                sta_ht_cap_new.cap &=
                                        ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;

                        if (memcmp(&sta->sta.ht_cap, &sta_ht_cap_new,
                                   sizeof(sta_ht_cap_new))) {
                                memcpy(&sta->sta.ht_cap, &sta_ht_cap_new,
                                       sizeof(sta_ht_cap_new));
                                rates_updated = true;
                        }
                }

                if (sta && rates_updated) {
                        drv_sta_rc_update(local, sdata, &sta->sta,
                                          IEEE80211_RC_SUPP_RATES_CHANGED);
                        rate_control_rate_init(sta);
                }

                rcu_read_unlock();
        }

        bss = ieee80211_bss_info_update(local, rx_status, mgmt, len, elems,
                                        channel, beacon);
        if (!bss)
                return;

        cbss = container_of((void *)bss, struct cfg80211_bss, priv);

        /* was just updated in ieee80211_bss_info_update */
        beacon_timestamp = cbss->tsf;

        /* check if we need to merge IBSS */

        /* we use a fixed BSSID */
        if (sdata->u.ibss.fixed_bssid)
                goto put_bss;

        /* not an IBSS */
        if (!(cbss->capability & WLAN_CAPABILITY_IBSS))
                goto put_bss;

        /* different channel */
        if (cbss->channel != local->oper_channel)
                goto put_bss;

        /* different SSID */
        if (elems->ssid_len != sdata->u.ibss.ssid_len ||
            memcmp(elems->ssid, sdata->u.ibss.ssid,
                                sdata->u.ibss.ssid_len))
                goto put_bss;

        /* same BSSID */
        if (ether_addr_equal(cbss->bssid, sdata->u.ibss.bssid))
                goto put_bss;

        if (rx_status->flag & RX_FLAG_MACTIME_MPDU) {
                /*
                 * For correct IBSS merging we need mactime; since mactime is
                 * defined as the time the first data symbol of the frame hits
                 * the PHY, and the timestamp of the beacon is defined as "the
                 * time that the data symbol containing the first bit of the
                 * timestamp is transmitted to the PHY plus the transmitting
                 * STA's delays through its local PHY from the MAC-PHY
                 * interface to its interface with the WM" (802.11 11.1.2)
                 * - equals the time this bit arrives at the receiver - we have
                 * to take into account the offset between the two.
                 *
                 * E.g. at 1 MBit that means mactime is 192 usec earlier
                 * (=24 bytes * 8 usecs/byte) than the beacon timestamp.
                 */
                int rate;

                if (rx_status->flag & RX_FLAG_HT)
                        rate = 65; /* TODO: HT rates */
                else
                        rate = local->hw.wiphy->bands[band]->
                                bitrates[rx_status->rate_idx].bitrate;

                rx_timestamp = rx_status->mactime + (24 * 8 * 10 / rate);
        } else {
                /*
                 * second best option: get current TSF
                 * (will return -1 if not supported)
                 */
                rx_timestamp = drv_get_tsf(local, sdata);
        }

        ibss_dbg(sdata,
                 "RX beacon SA=%pM BSSID=%pM TSF=0x%llx BCN=0x%llx diff=%lld @%lu\n",
                 mgmt->sa, mgmt->bssid,
                 (unsigned long long)rx_timestamp,
                 (unsigned long long)beacon_timestamp,
                 (unsigned long long)(rx_timestamp - beacon_timestamp),
                 jiffies);

        if (beacon_timestamp > rx_timestamp) {
                ibss_dbg(sdata,
                         "beacon TSF higher than local TSF - IBSS merge with BSSID %pM\n",
                         mgmt->bssid);
                ieee80211_sta_join_ibss(sdata, bss);
                supp_rates = ieee80211_sta_get_rates(local, elems, band, NULL);
                ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa,
                                       supp_rates, true);
                rcu_read_unlock();
        }

 put_bss:
        ieee80211_rx_bss_put(local, bss);
}

void ieee80211_ibss_rx_no_sta(struct ieee80211_sub_if_data *sdata,
                              const u8 *bssid, const u8 *addr,
                              u32 supp_rates)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;
        int band = local->oper_channel->band;

        /*
         * XXX: Consider removing the least recently used entry and
         *      allow new one to be added.
         */
        if (local->num_sta >= IEEE80211_IBSS_MAX_STA_ENTRIES) {
                net_info_ratelimited("%s: No room for a new IBSS STA entry %pM\n",
                                    sdata->name, addr);
                return;
        }

        if (ifibss->state == IEEE80211_IBSS_MLME_SEARCH)
                return;

        if (!ether_addr_equal(bssid, sdata->u.ibss.bssid))
                return;

        sta = sta_info_alloc(sdata, addr, GFP_ATOMIC);
        if (!sta)
                return;

        sta->last_rx = jiffies;

        /* make sure mandatory rates are always added */
        sta->sta.supp_rates[band] = supp_rates |
                        ieee80211_mandatory_rates(local, band);

        spin_lock(&ifibss->incomplete_lock);
        list_add(&sta->list, &ifibss->incomplete_stations);
        spin_unlock(&ifibss->incomplete_lock);
        ieee80211_queue_work(&local->hw, &sdata->work);
}

static int ieee80211_sta_active_ibss(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_local *local = sdata->local;
        int active = 0;
        struct sta_info *sta;

        lockdep_assert_held(&sdata->u.ibss.mtx);

        rcu_read_lock();

        list_for_each_entry_rcu(sta, &local->sta_list, list) {
                if (sta->sdata == sdata &&
                    time_after(sta->last_rx + IEEE80211_IBSS_MERGE_INTERVAL,
                               jiffies)) {
                        active++;
                        break;
                }
        }

        rcu_read_unlock();

        return active;
}

/*
 * This function is called with state == IEEE80211_IBSS_MLME_JOINED
 */

static void ieee80211_sta_merge_ibss(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

        lockdep_assert_held(&ifibss->mtx);

        mod_timer(&ifibss->timer,
                  round_jiffies(jiffies + IEEE80211_IBSS_MERGE_INTERVAL));

        ieee80211_sta_expire(sdata, IEEE80211_IBSS_INACTIVITY_LIMIT);

        if (time_before(jiffies, ifibss->last_scan_completed +
                       IEEE80211_IBSS_MERGE_INTERVAL))
                return;

        if (ieee80211_sta_active_ibss(sdata))
                return;

        if (ifibss->fixed_channel)
                return;

        sdata_info(sdata,
                   "No active IBSS STAs - trying to scan for other IBSS networks with same SSID (merge)\n");

        ieee80211_request_ibss_scan(sdata, ifibss->ssid, ifibss->ssid_len,
                                    NULL);
}

static void ieee80211_sta_create_ibss(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        u8 bssid[ETH_ALEN];
        u16 capability;
        int i;

        lockdep_assert_held(&ifibss->mtx);

        if (ifibss->fixed_bssid) {
                memcpy(bssid, ifibss->bssid, ETH_ALEN);
        } else {
                /* Generate random, not broadcast, locally administered BSSID. Mix in
                 * own MAC address to make sure that devices that do not have proper
                 * random number generator get different BSSID. */
                get_random_bytes(bssid, ETH_ALEN);
                for (i = 0; i < ETH_ALEN; i++)
                        bssid[i] ^= sdata->vif.addr[i];
                bssid[0] &= ~0x01;
                bssid[0] |= 0x02;
        }

        sdata_info(sdata, "Creating new IBSS network, BSSID %pM\n", bssid);

        capability = WLAN_CAPABILITY_IBSS;

        if (ifibss->privacy)
                capability |= WLAN_CAPABILITY_PRIVACY;
        else
                sdata->drop_unencrypted = 0;

        __ieee80211_sta_join_ibss(sdata, bssid, sdata->vif.bss_conf.beacon_int,
                                  ifibss->channel, ifibss->basic_rates,
                                  capability, 0);
}

/*
 * This function is called with state == IEEE80211_IBSS_MLME_SEARCH
 */

static void ieee80211_sta_find_ibss(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        struct cfg80211_bss *cbss;
        struct ieee80211_channel *chan = NULL;
        const u8 *bssid = NULL;
        int active_ibss;
        u16 capability;

        lockdep_assert_held(&ifibss->mtx);

        active_ibss = ieee80211_sta_active_ibss(sdata);
        ibss_dbg(sdata, "sta_find_ibss (active_ibss=%d)\n", active_ibss);

        if (active_ibss)
                return;

        capability = WLAN_CAPABILITY_IBSS;
        if (ifibss->privacy)
                capability |= WLAN_CAPABILITY_PRIVACY;
        if (ifibss->fixed_bssid)
                bssid = ifibss->bssid;
        if (ifibss->fixed_channel)
                chan = ifibss->channel;
        if (!is_zero_ether_addr(ifibss->bssid))
                bssid = ifibss->bssid;
        cbss = cfg80211_get_bss(local->hw.wiphy, chan, bssid,
                                ifibss->ssid, ifibss->ssid_len,
                                WLAN_CAPABILITY_IBSS | WLAN_CAPABILITY_PRIVACY,
                                capability);

        if (cbss) {
                struct ieee80211_bss *bss;

                bss = (void *)cbss->priv;
                ibss_dbg(sdata,
                         "sta_find_ibss: selected %pM current %pM\n",
                         cbss->bssid, ifibss->bssid);
                sdata_info(sdata,
                           "Selected IBSS BSSID %pM based on configured SSID\n",
                           cbss->bssid);

                ieee80211_sta_join_ibss(sdata, bss);
                ieee80211_rx_bss_put(local, bss);
                return;
        }

        ibss_dbg(sdata, "sta_find_ibss: did not try to join ibss\n");

        /* Selected IBSS not found in current scan results - try to scan */
        if (time_after(jiffies, ifibss->last_scan_completed +
                                        IEEE80211_SCAN_INTERVAL)) {
                sdata_info(sdata, "Trigger new scan to find an IBSS to join\n");

                ieee80211_request_ibss_scan(sdata, ifibss->ssid,
                                            ifibss->ssid_len, chan);
        } else {
                int interval = IEEE80211_SCAN_INTERVAL;

                if (time_after(jiffies, ifibss->ibss_join_req +
                               IEEE80211_IBSS_JOIN_TIMEOUT)) {
                        if (!(local->oper_channel->flags & IEEE80211_CHAN_NO_IBSS)) {
                                ieee80211_sta_create_ibss(sdata);
                                return;
                        }
                        sdata_info(sdata, "IBSS not allowed on %d MHz\n",
                                   local->oper_channel->center_freq);

                        /* No IBSS found - decrease scan interval and continue
                         * scanning. */
                        interval = IEEE80211_SCAN_INTERVAL_SLOW;
                }

                mod_timer(&ifibss->timer,
                          round_jiffies(jiffies + interval));
        }
}

static void ieee80211_rx_mgmt_probe_req(struct ieee80211_sub_if_data *sdata,
                                        struct sk_buff *req)
{
        struct ieee80211_mgmt *mgmt = (void *)req->data;
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        int tx_last_beacon, len = req->len;
        struct sk_buff *skb;
        struct ieee80211_mgmt *resp;
        struct sk_buff *presp;
        u8 *pos, *end;

        lockdep_assert_held(&ifibss->mtx);

        presp = rcu_dereference_protected(ifibss->presp,
                                          lockdep_is_held(&ifibss->mtx));

        if (ifibss->state != IEEE80211_IBSS_MLME_JOINED ||
            len < 24 + 2 || !presp)
                return;

        tx_last_beacon = drv_tx_last_beacon(local);

        ibss_dbg(sdata,
                 "RX ProbeReq SA=%pM DA=%pM BSSID=%pM (tx_last_beacon=%d)\n",
                 mgmt->sa, mgmt->da, mgmt->bssid, tx_last_beacon);

        if (!tx_last_beacon && is_multicast_ether_addr(mgmt->da))
                return;

        if (!ether_addr_equal(mgmt->bssid, ifibss->bssid) &&
            !is_broadcast_ether_addr(mgmt->bssid))
                return;

        end = ((u8 *) mgmt) + len;
        pos = mgmt->u.probe_req.variable;
        if (pos[0] != WLAN_EID_SSID ||
            pos + 2 + pos[1] > end) {
                ibss_dbg(sdata, "Invalid SSID IE in ProbeReq from %pM\n",
                         mgmt->sa);
                return;
        }
        if (pos[1] != 0 &&
            (pos[1] != ifibss->ssid_len ||
             memcmp(pos + 2, ifibss->ssid, ifibss->ssid_len))) {
                /* Ignore ProbeReq for foreign SSID */
                return;
        }

        /* Reply with ProbeResp */
        skb = skb_copy(presp, GFP_KERNEL);
        if (!skb)
                return;

        resp = (struct ieee80211_mgmt *) skb->data;
        memcpy(resp->da, mgmt->sa, ETH_ALEN);
        ibss_dbg(sdata, "Sending ProbeResp to %pM\n", resp->da);
        IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT;
        ieee80211_tx_skb(sdata, skb);
}

static void ieee80211_rx_mgmt_probe_resp(struct ieee80211_sub_if_data *sdata,
                                         struct ieee80211_mgmt *mgmt,
                                         size_t len,
                                         struct ieee80211_rx_status *rx_status)
{
        size_t baselen;
        struct ieee802_11_elems elems;

        baselen = (u8 *) mgmt->u.probe_resp.variable - (u8 *) mgmt;
        if (baselen > len)
                return;

        ieee802_11_parse_elems(mgmt->u.probe_resp.variable, len - baselen,
                                &elems);

        ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems, false);
}

static void ieee80211_rx_mgmt_beacon(struct ieee80211_sub_if_data *sdata,
                                     struct ieee80211_mgmt *mgmt,
                                     size_t len,
                                     struct ieee80211_rx_status *rx_status)
{
        size_t baselen;
        struct ieee802_11_elems elems;

        /* Process beacon from the current BSS */
        baselen = (u8 *) mgmt->u.beacon.variable - (u8 *) mgmt;
        if (baselen > len)
                return;

        ieee802_11_parse_elems(mgmt->u.beacon.variable, len - baselen, &elems);

        ieee80211_rx_bss_info(sdata, mgmt, len, rx_status, &elems, true);
}

void ieee80211_ibss_rx_queued_mgmt(struct ieee80211_sub_if_data *sdata,
                                   struct sk_buff *skb)
{
        struct ieee80211_rx_status *rx_status;
        struct ieee80211_mgmt *mgmt;
        u16 fc;

        rx_status = IEEE80211_SKB_RXCB(skb);
        mgmt = (struct ieee80211_mgmt *) skb->data;
        fc = le16_to_cpu(mgmt->frame_control);

        mutex_lock(&sdata->u.ibss.mtx);

        if (!sdata->u.ibss.ssid_len)
                goto mgmt_out; /* not ready to merge yet */

        switch (fc & IEEE80211_FCTL_STYPE) {
        case IEEE80211_STYPE_PROBE_REQ:
                ieee80211_rx_mgmt_probe_req(sdata, skb);
                break;
        case IEEE80211_STYPE_PROBE_RESP:
                ieee80211_rx_mgmt_probe_resp(sdata, mgmt, skb->len,
                                             rx_status);
                break;
        case IEEE80211_STYPE_BEACON:
                ieee80211_rx_mgmt_beacon(sdata, mgmt, skb->len,
                                         rx_status);
                break;
        case IEEE80211_STYPE_AUTH:
                ieee80211_rx_mgmt_auth_ibss(sdata, mgmt, skb->len);
                break;
        case IEEE80211_STYPE_DEAUTH:
                ieee80211_rx_mgmt_deauth_ibss(sdata, mgmt, skb->len);
                break;
        }

 mgmt_out:
        mutex_unlock(&sdata->u.ibss.mtx);
}

void ieee80211_ibss_work(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct sta_info *sta;

        mutex_lock(&ifibss->mtx);

        /*
         * Work could be scheduled after scan or similar
         * when we aren't even joined (or trying) with a
         * network.
         */
        if (!ifibss->ssid_len)
                goto out;

        spin_lock_bh(&ifibss->incomplete_lock);
        while (!list_empty(&ifibss->incomplete_stations)) {
                sta = list_first_entry(&ifibss->incomplete_stations,
                                       struct sta_info, list);
                list_del(&sta->list);
                spin_unlock_bh(&ifibss->incomplete_lock);

                ieee80211_ibss_finish_sta(sta, true);
                rcu_read_unlock();
                spin_lock_bh(&ifibss->incomplete_lock);
        }
        spin_unlock_bh(&ifibss->incomplete_lock);

        switch (ifibss->state) {
        case IEEE80211_IBSS_MLME_SEARCH:
                ieee80211_sta_find_ibss(sdata);
                break;
        case IEEE80211_IBSS_MLME_JOINED:
                ieee80211_sta_merge_ibss(sdata);
                break;
        default:
                WARN_ON(1);
                break;
        }

 out:
        mutex_unlock(&ifibss->mtx);
}

static void ieee80211_ibss_timer(unsigned long data)
{
        struct ieee80211_sub_if_data *sdata =
                (struct ieee80211_sub_if_data *) data;
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;

        if (local->quiescing) {
                ifibss->timer_running = true;
                return;
        }

        ieee80211_queue_work(&local->hw, &sdata->work);
}

#ifdef CONFIG_PM

void ieee80211_ibss_quiesce(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

        if (del_timer_sync(&ifibss->timer))
                ifibss->timer_running = true;
}

void ieee80211_ibss_restart(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

        if (ifibss->timer_running) {
                add_timer(&ifibss->timer);
                ifibss->timer_running = false;
        }
}
#endif

void ieee80211_ibss_setup_sdata(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

        setup_timer(&ifibss->timer, ieee80211_ibss_timer,
                    (unsigned long) sdata);
        mutex_init(&ifibss->mtx);
        INIT_LIST_HEAD(&ifibss->incomplete_stations);
        spin_lock_init(&ifibss->incomplete_lock);
}

/* scan finished notification */
void ieee80211_ibss_notify_scan_completed(struct ieee80211_local *local)
{
        struct ieee80211_sub_if_data *sdata;

        mutex_lock(&local->iflist_mtx);
        list_for_each_entry(sdata, &local->interfaces, list) {
                if (!ieee80211_sdata_running(sdata))
                        continue;
                if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
                        continue;
                sdata->u.ibss.last_scan_completed = jiffies;
                ieee80211_queue_work(&local->hw, &sdata->work);
        }
        mutex_unlock(&local->iflist_mtx);
}

int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
                        struct cfg80211_ibss_params *params)
{
        struct sk_buff *skb;
        u32 changed = 0;

        skb = dev_alloc_skb(sdata->local->hw.extra_tx_headroom +
                            sizeof(struct ieee80211_hdr_3addr) +
                            12 /* struct ieee80211_mgmt.u.beacon */ +
                            2 + IEEE80211_MAX_SSID_LEN /* max SSID */ +
                            2 + 8 /* max Supported Rates */ +
                            3 /* max DS params */ +
                            4 /* IBSS params */ +
                            2 + (IEEE80211_MAX_SUPP_RATES - 8) +
                            2 + sizeof(struct ieee80211_ht_cap) +
                            2 + sizeof(struct ieee80211_ht_operation) +
                            params->ie_len);
        if (!skb)
                return -ENOMEM;

        mutex_lock(&sdata->u.ibss.mtx);

        if (params->bssid) {
                memcpy(sdata->u.ibss.bssid, params->bssid, ETH_ALEN);
                sdata->u.ibss.fixed_bssid = true;
        } else
                sdata->u.ibss.fixed_bssid = false;

        sdata->u.ibss.privacy = params->privacy;
        sdata->u.ibss.control_port = params->control_port;
        sdata->u.ibss.basic_rates = params->basic_rates;
        memcpy(sdata->vif.bss_conf.mcast_rate, params->mcast_rate,
               sizeof(params->mcast_rate));

        sdata->vif.bss_conf.beacon_int = params->beacon_interval;

        sdata->u.ibss.channel = params->channel;
        sdata->u.ibss.channel_type = params->channel_type;
        sdata->u.ibss.fixed_channel = params->channel_fixed;

        /* fix ourselves to that channel now already */
        if (params->channel_fixed) {
                sdata->local->oper_channel = params->channel;
                if (!ieee80211_set_channel_type(sdata->local, sdata,
                                               params->channel_type)) {
                        mutex_unlock(&sdata->u.ibss.mtx);
                        kfree_skb(skb);
                        return -EINVAL;
                }
        }

        if (params->ie) {
                sdata->u.ibss.ie = kmemdup(params->ie, params->ie_len,
                                           GFP_KERNEL);
                if (sdata->u.ibss.ie)
                        sdata->u.ibss.ie_len = params->ie_len;
        }

        sdata->u.ibss.skb = skb;
        sdata->u.ibss.state = IEEE80211_IBSS_MLME_SEARCH;
        sdata->u.ibss.ibss_join_req = jiffies;

        memcpy(sdata->u.ibss.ssid, params->ssid, params->ssid_len);
        sdata->u.ibss.ssid_len = params->ssid_len;

        mutex_unlock(&sdata->u.ibss.mtx);

        mutex_lock(&sdata->local->mtx);
        ieee80211_recalc_idle(sdata->local);
        mutex_unlock(&sdata->local->mtx);

        /*
         * 802.11n-2009 9.13.3.1: In an IBSS, the HT Protection field is
         * reserved, but an HT STA shall protect HT transmissions as though
         * the HT Protection field were set to non-HT mixed mode.
         *
         * In an IBSS, the RIFS Mode field of the HT Operation element is
         * also reserved, but an HT STA shall operate as though this field
         * were set to 1.
         */

        sdata->vif.bss_conf.ht_operation_mode |=
                  IEEE80211_HT_OP_MODE_PROTECTION_NONHT_MIXED
                | IEEE80211_HT_PARAM_RIFS_MODE;

        changed |= BSS_CHANGED_HT;
        ieee80211_bss_info_change_notify(sdata, changed);

        ieee80211_queue_work(&sdata->local->hw, &sdata->work);

        return 0;
}

int ieee80211_ibss_leave(struct ieee80211_sub_if_data *sdata)
{
        struct sk_buff *skb;
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        struct cfg80211_bss *cbss;
        u16 capability;
        int active_ibss;
        struct sta_info *sta;

        mutex_lock(&sdata->u.ibss.mtx);

        active_ibss = ieee80211_sta_active_ibss(sdata);

        if (!active_ibss && !is_zero_ether_addr(ifibss->bssid)) {
                capability = WLAN_CAPABILITY_IBSS;

                if (ifibss->privacy)
                        capability |= WLAN_CAPABILITY_PRIVACY;

                cbss = cfg80211_get_bss(local->hw.wiphy, ifibss->channel,
                                        ifibss->bssid, ifibss->ssid,
                                        ifibss->ssid_len, WLAN_CAPABILITY_IBSS |
                                        WLAN_CAPABILITY_PRIVACY,
                                        capability);

                if (cbss) {
                        cfg80211_unlink_bss(local->hw.wiphy, cbss);
                        cfg80211_put_bss(cbss);
                }
        }

        ifibss->state = IEEE80211_IBSS_MLME_SEARCH;
        memset(ifibss->bssid, 0, ETH_ALEN);
        ifibss->ssid_len = 0;

        sta_info_flush(sdata->local, sdata);

        spin_lock_bh(&ifibss->incomplete_lock);
        while (!list_empty(&ifibss->incomplete_stations)) {
                sta = list_first_entry(&ifibss->incomplete_stations,
                                       struct sta_info, list);
                list_del(&sta->list);
                spin_unlock_bh(&ifibss->incomplete_lock);

                sta_info_free(local, sta);
                spin_lock_bh(&ifibss->incomplete_lock);
        }
        spin_unlock_bh(&ifibss->incomplete_lock);

        netif_carrier_off(sdata->dev);

        /* remove beacon */
        kfree(sdata->u.ibss.ie);
        skb = rcu_dereference_protected(sdata->u.ibss.presp,
                                        lockdep_is_held(&sdata->u.ibss.mtx));
        RCU_INIT_POINTER(sdata->u.ibss.presp, NULL);
        sdata->vif.bss_conf.ibss_joined = false;
        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED |
                                                BSS_CHANGED_IBSS);
        synchronize_rcu();
        kfree_skb(skb);

        skb_queue_purge(&sdata->skb_queue);

        del_timer_sync(&sdata->u.ibss.timer);

        mutex_unlock(&sdata->u.ibss.mtx);

        mutex_lock(&local->mtx);
        ieee80211_recalc_idle(sdata->local);
        mutex_unlock(&local->mtx);

        return 0;
}