/*
 * 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/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 <asm/unaligned.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_MERGE_DELAY 0x400000
#define IEEE80211_IBSS_INACTIVITY_LIMIT (60 * HZ)

#define IEEE80211_IBSS_MAX_STA_ENTRIES 128


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, status_code;

        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);
        status_code = le16_to_cpu(mgmt->u.auth.status_code);

        /*
         * 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.
         */
        if (auth_alg == WLAN_AUTH_OPEN && auth_transaction == 1)
                ieee80211_send_auth(sdata, 2, WLAN_AUTH_OPEN, NULL, 0,
                                    sdata->u.ibss.bssid, NULL, 0, 0);
}

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];

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

        skb = ifibss->skb;
        rcu_assign_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 (memcmp(ifibss->bssid, bssid, ETH_ALEN))
                sta_info_flush(sdata->local, sdata);

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

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

        local->oper_channel = chan;
        local->oper_channel_type = NL80211_CHAN_NO_HT;
        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);
        memset(mgmt->da, 0xff, ETH_ALEN);
        memcpy(mgmt->sa, sdata->dev->dev_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);

        rcu_assign_pointer(ifibss->presp, skb);

        sdata->vif.bss_conf.beacon_int = beacon_int;
        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;
        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, local->hw.conf.channel,
                                        mgmt, skb->len, 0, GFP_KERNEL);
        cfg80211_put_bss(bss);
        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 ieee80211_supported_band *sband;
        u32 basic_rates;
        int i, j;
        u16 beacon_int = bss->cbss.beacon_interval;

        if (beacon_int < 10)
                beacon_int = 10;

        sband = sdata->local->hw.wiphy->bands[bss->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, bss->cbss.bssid,
                                  beacon_int,
                                  bss->cbss.channel,
                                  basic_rates,
                                  bss->cbss.capability,
                                  bss->cbss.tsf);
}

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 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;

        if (elems->ds_params && elems->ds_params_len == 1)
                freq = ieee80211_channel_to_frequency(elems->ds_params[0]);
        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 && elems->supp_rates &&
            memcmp(mgmt->bssid, sdata->u.ibss.bssid, ETH_ALEN) == 0) {
                supp_rates = ieee80211_sta_get_rates(local, elems, band);

                rcu_read_lock();

                sta = sta_info_get(local, mgmt->sa);
                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);

#ifdef CONFIG_MAC80211_IBSS_DEBUG
                        if (sta->sta.supp_rates[band] != prev_rates)
                                printk(KERN_DEBUG "%s: updated supp_rates set "
                                    "for %pM based on beacon info (0x%llx | "
                                    "0x%llx -> 0x%llx)\n",
                                    sdata->dev->name,
                                    sta->sta.addr,
                                    (unsigned long long) prev_rates,
                                    (unsigned long long) supp_rates,
                                    (unsigned long long) sta->sta.supp_rates[band]);
#endif
                } else
                        ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa, supp_rates);

                rcu_read_unlock();
        }

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

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

        /* check if we need to merge IBSS */

        /* merge only on beacons (???) */
        if (!beacon)
                goto put_bss;

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

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

        /* different channel */
        if (bss->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 (memcmp(bss->cbss.bssid, sdata->u.ibss.bssid, ETH_ALEN) == 0)
                goto put_bss;

        if (rx_status->flag & RX_FLAG_TSFT) {
                /*
                 * 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);
        }

#ifdef CONFIG_MAC80211_IBSS_DEBUG
        printk(KERN_DEBUG "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);
#endif

        /* give slow hardware some time to do the TSF sync */
        if (rx_timestamp < IEEE80211_IBSS_MERGE_DELAY)
                goto put_bss;

        if (beacon_timestamp > rx_timestamp) {
#ifdef CONFIG_MAC80211_IBSS_DEBUG
                printk(KERN_DEBUG "%s: beacon TSF higher than "
                       "local TSF - IBSS merge with BSSID %pM\n",
                       sdata->dev->name, mgmt->bssid);
#endif
                ieee80211_sta_join_ibss(sdata, bss);
                ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa, supp_rates);
        }

 put_bss:
        ieee80211_rx_bss_put(local, bss);
}

/*
 * Add a new IBSS station, will also be called by the RX code when,
 * in IBSS mode, receiving a frame from a yet-unknown station, hence
 * must be callable in atomic context.
 */
struct sta_info *ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
                                        u8 *bssid,u8 *addr, u32 supp_rates)
{
        struct ieee80211_local *local = sdata->local;
        struct sta_info *sta;
        int band = local->hw.conf.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) {
                if (net_ratelimit())
                        printk(KERN_DEBUG "%s: No room for a new IBSS STA entry %pM\n",
                               sdata->dev->name, addr);
                return NULL;
        }

        if (compare_ether_addr(bssid, sdata->u.ibss.bssid))
                return NULL;

#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
        printk(KERN_DEBUG "%s: Adding new IBSS station %pM (dev=%s)\n",
               wiphy_name(local->hw.wiphy), addr, sdata->dev->name);
#endif

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

        set_sta_flags(sta, WLAN_STA_AUTHORIZED);

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

        rate_control_rate_init(sta);

        if (sta_info_insert(sta))
                return NULL;

        return sta;
}

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;

        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;
}


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

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

        ieee80211_sta_expire(sdata, IEEE80211_IBSS_INACTIVITY_LIMIT);

        if (ieee80211_sta_active_ibss(sdata))
                return;

        if (ifibss->fixed_channel)
                return;

        printk(KERN_DEBUG "%s: No active IBSS STAs - trying to scan for other "
               "IBSS networks with same SSID (merge)\n", sdata->dev->name);

        ieee80211_request_internal_scan(sdata, ifibss->ssid, ifibss->ssid_len);
}

static void ieee80211_sta_create_ibss(struct ieee80211_sub_if_data *sdata)
{
        struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_supported_band *sband;
        u8 bssid[ETH_ALEN];
        u16 capability;
        int i;

        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->dev->dev_addr[i];
                bssid[0] &= ~0x01;
                bssid[0] |= 0x02;
        }

        printk(KERN_DEBUG "%s: Creating new IBSS network, BSSID %pM\n",
               sdata->dev->name, bssid);

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

        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, 3, /* first two are basic */
                                  capability, 0);
}

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 ieee80211_bss *bss;
        struct ieee80211_channel *chan = NULL;
        const u8 *bssid = NULL;
        int active_ibss;
        u16 capability;

        active_ibss = ieee80211_sta_active_ibss(sdata);
#ifdef CONFIG_MAC80211_IBSS_DEBUG
        printk(KERN_DEBUG "%s: sta_find_ibss (active_ibss=%d)\n",
               sdata->dev->name, active_ibss);
#endif /* CONFIG_MAC80211_IBSS_DEBUG */

        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;
        bss = (void *)cfg80211_get_bss(local->hw.wiphy, chan, bssid,
                                       ifibss->ssid, ifibss->ssid_len,
                                       WLAN_CAPABILITY_IBSS |
                                       WLAN_CAPABILITY_PRIVACY,
                                       capability);

        if (bss) {
#ifdef CONFIG_MAC80211_IBSS_DEBUG
                printk(KERN_DEBUG "   sta_find_ibss: selected %pM current "
                       "%pM\n", bss->cbss.bssid, ifibss->bssid);
#endif /* CONFIG_MAC80211_IBSS_DEBUG */

                printk(KERN_DEBUG "%s: Selected IBSS BSSID %pM"
                       " based on configured SSID\n",
                       sdata->dev->name, bss->cbss.bssid);

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

#ifdef CONFIG_MAC80211_IBSS_DEBUG
        printk(KERN_DEBUG "   did not try to join ibss\n");
#endif /* CONFIG_MAC80211_IBSS_DEBUG */

        /* Selected IBSS not found in current scan results - try to scan */
        if (ifibss->state == IEEE80211_IBSS_MLME_JOINED &&
            !ieee80211_sta_active_ibss(sdata)) {
                mod_timer(&ifibss->timer,
                          round_jiffies(jiffies + IEEE80211_IBSS_MERGE_INTERVAL));
        } else if (time_after(jiffies, ifibss->last_scan_completed +
                                        IEEE80211_SCAN_INTERVAL)) {
                printk(KERN_DEBUG "%s: Trigger new scan to find an IBSS to "
                       "join\n", sdata->dev->name);

                ieee80211_request_internal_scan(sdata, ifibss->ssid,
                                                ifibss->ssid_len);
        } else if (ifibss->state != IEEE80211_IBSS_MLME_JOINED) {
                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;
                        }
                        printk(KERN_DEBUG "%s: IBSS not allowed on"
                               " %d MHz\n", sdata->dev->name,
                               local->hw.conf.channel->center_freq);

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

                ifibss->state = IEEE80211_IBSS_MLME_SEARCH;
                mod_timer(&ifibss->timer,
                          round_jiffies(jiffies + interval));
        }
}

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

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

        tx_last_beacon = drv_tx_last_beacon(local);

#ifdef CONFIG_MAC80211_IBSS_DEBUG
        printk(KERN_DEBUG "%s: RX ProbeReq SA=%pM DA=%pM BSSID=%pM"
               " (tx_last_beacon=%d)\n",
               sdata->dev->name, mgmt->sa, mgmt->da,
               mgmt->bssid, tx_last_beacon);
#endif /* CONFIG_MAC80211_IBSS_DEBUG */

        if (!tx_last_beacon)
                return;

        if (memcmp(mgmt->bssid, ifibss->bssid, ETH_ALEN) != 0 &&
            memcmp(mgmt->bssid, "\xff\xff\xff\xff\xff\xff", ETH_ALEN) != 0)
                return;

        end = ((u8 *) mgmt) + len;
        pos = mgmt->u.probe_req.variable;
        if (pos[0] != WLAN_EID_SSID ||
            pos + 2 + pos[1] > end) {
#ifdef CONFIG_MAC80211_IBSS_DEBUG
                printk(KERN_DEBUG "%s: Invalid SSID IE in ProbeReq "
                       "from %pM\n",
                       sdata->dev->name, mgmt->sa);
#endif
                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(ifibss->presp, GFP_KERNEL);
        if (!skb)
                return;

        resp = (struct ieee80211_mgmt *) skb->data;
        memcpy(resp->da, mgmt->sa, ETH_ALEN);
#ifdef CONFIG_MAC80211_IBSS_DEBUG
        printk(KERN_DEBUG "%s: Sending ProbeResp to %pM\n",
               sdata->dev->name, resp->da);
#endif /* CONFIG_MAC80211_IBSS_DEBUG */
        ieee80211_tx_skb(sdata, skb, 0);
}

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;

        if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
                return; /* ignore ProbeResp to foreign address */

        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);
}

static 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);

        switch (fc & IEEE80211_FCTL_STYPE) {
        case IEEE80211_STYPE_PROBE_REQ:
                ieee80211_rx_mgmt_probe_req(sdata, mgmt, skb->len);
                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;
        }

        kfree_skb(skb);
}

static void ieee80211_ibss_work(struct work_struct *work)
{
        struct ieee80211_sub_if_data *sdata =
                container_of(work, struct ieee80211_sub_if_data, u.ibss.work);
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_if_ibss *ifibss;
        struct sk_buff *skb;

        if (WARN_ON(local->suspended))
                return;

        if (!netif_running(sdata->dev))
                return;

        if (local->scanning)
                return;

        if (WARN_ON(sdata->vif.type != NL80211_IFTYPE_ADHOC))
                return;
        ifibss = &sdata->u.ibss;

        while ((skb = skb_dequeue(&ifibss->skb_queue)))
                ieee80211_ibss_rx_queued_mgmt(sdata, skb);

        if (!test_and_clear_bit(IEEE80211_IBSS_REQ_RUN, &ifibss->request))
                return;

        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;
        }
}

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;
        }

        set_bit(IEEE80211_IBSS_REQ_RUN, &ifibss->request);
        ieee80211_queue_work(&local->hw, &ifibss->work);
}

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

        cancel_work_sync(&ifibss->work);
        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;

        INIT_WORK(&ifibss->work, ieee80211_ibss_work);
        setup_timer(&ifibss->timer, ieee80211_ibss_timer,
                    (unsigned long) sdata);
        skb_queue_head_init(&ifibss->skb_queue);
}

/* 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 (!netif_running(sdata->dev))
                        continue;
                if (sdata->vif.type != NL80211_IFTYPE_ADHOC)
                        continue;
                if (!sdata->u.ibss.ssid_len)
                        continue;
                sdata->u.ibss.last_scan_completed = jiffies;
                mod_timer(&sdata->u.ibss.timer, 0);
        }
        mutex_unlock(&local->iflist_mtx);
}

ieee80211_rx_result
ieee80211_ibss_rx_mgmt(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb)
{
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_mgmt *mgmt;
        u16 fc;

        if (skb->len < 24)
                return RX_DROP_MONITOR;

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

        switch (fc & IEEE80211_FCTL_STYPE) {
        case IEEE80211_STYPE_PROBE_RESP:
        case IEEE80211_STYPE_BEACON:
        case IEEE80211_STYPE_PROBE_REQ:
        case IEEE80211_STYPE_AUTH:
                skb_queue_tail(&sdata->u.ibss.skb_queue, skb);
                ieee80211_queue_work(&local->hw, &sdata->u.ibss.work);
                return RX_QUEUED;
        }

        return RX_DROP_MONITOR;
}

int ieee80211_ibss_join(struct ieee80211_sub_if_data *sdata,
                        struct cfg80211_ibss_params *params)
{
        struct sk_buff *skb;

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

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

        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;
        }

        skb = dev_alloc_skb(sdata->local->hw.extra_tx_headroom +
                            36 /* bitrates */ +
                            34 /* SSID */ +
                            3  /* DS params */ +
                            4  /* IBSS params */ +
                            params->ie_len);
        if (!skb)
                return -ENOMEM;

        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, IEEE80211_MAX_SSID_LEN);

        /*
         * The ssid_len setting below is used to see whether
         * we are active, and we need all other settings
         * before that may get visible.
         */
        mb();

        sdata->u.ibss.ssid_len = params->ssid_len;

        ieee80211_recalc_idle(sdata->local);

        set_bit(IEEE80211_IBSS_REQ_RUN, &sdata->u.ibss.request);
        ieee80211_queue_work(&sdata->local->hw, &sdata->u.ibss.work);

        return 0;
}

int ieee80211_ibss_leave(struct ieee80211_sub_if_data *sdata)
{
        struct sk_buff *skb;

        del_timer_sync(&sdata->u.ibss.timer);
        clear_bit(IEEE80211_IBSS_REQ_RUN, &sdata->u.ibss.request);
        cancel_work_sync(&sdata->u.ibss.work);
        clear_bit(IEEE80211_IBSS_REQ_RUN, &sdata->u.ibss.request);

        sta_info_flush(sdata->local, sdata);

        /* remove beacon */
        kfree(sdata->u.ibss.ie);
        skb = sdata->u.ibss.presp;
        rcu_assign_pointer(sdata->u.ibss.presp, NULL);
        ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED);
        synchronize_rcu();
        kfree_skb(skb);

        skb_queue_purge(&sdata->u.ibss.skb_queue);
        memset(sdata->u.ibss.bssid, 0, ETH_ALEN);
        sdata->u.ibss.ssid_len = 0;

        ieee80211_recalc_idle(sdata->local);

        return 0;
}