ibss.c 32.1 KB
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/*
 * 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>
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#include <linux/slab.h>
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#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"
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#include "driver-ops.h"
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#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


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

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	/* Reset own TSF to allow time synchronization work. */
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	drv_reset_tsf(local, sdata);
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	skb = ifibss->skb;
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	RCU_INIT_POINTER(ifibss->presp, NULL);
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	synchronize_rcu();
	skb->data = skb->head;
	skb->len = 0;
	skb_reset_tail_pointer(skb);
	skb_reserve(skb, sdata->local->hw.extra_tx_headroom);
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	if (!ether_addr_equal(ifibss->bssid, bssid))
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		sta_info_flush(sdata->local, sdata);
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	/* 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;
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		netif_carrier_off(sdata->dev);
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		ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_IBSS);
	}

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

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	sdata->drop_unencrypted = capability & WLAN_CAPABILITY_PRIVACY ? 1 : 0;
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	local->oper_channel = chan;
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	channel_type = ifibss->channel_type;
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	if (!cfg80211_can_beacon_sec_chan(local->hw.wiphy, chan, channel_type))
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		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));
	}
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	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
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	sband = local->hw.wiphy->bands[chan->band];
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	/* 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);
	}

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	/* Build IBSS probe response */
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	mgmt = (void *) skb_put(skb, 24 + sizeof(mgmt->u.beacon));
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	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);
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	memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
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	memcpy(mgmt->bssid, ifibss->bssid, ETH_ALEN);
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	mgmt->u.beacon.beacon_int = cpu_to_le16(beacon_int);
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	mgmt->u.beacon.timestamp = cpu_to_le64(tsf);
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	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);

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	rates = sband->n_bitrates;
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	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;
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		*pos++ = ieee80211_frequency_to_channel(chan->center_freq);
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	}

	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;

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

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

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	/* add HT capability and information IEs */
	if (channel_type && sband->ht_cap.ht_supported) {
		pos = skb_put(skb, 4 +
				   sizeof(struct ieee80211_ht_cap) +
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				   sizeof(struct ieee80211_ht_operation));
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		pos = ieee80211_ie_build_ht_cap(pos, &sband->ht_cap,
						sband->ht_cap.cap);
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		/*
		 * 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
		 */
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		pos = ieee80211_ie_build_ht_oper(pos, &sband->ht_cap,
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						 chan, channel_type, 0);
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	}

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	if (local->hw.queues >= IEEE80211_NUM_ACS) {
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		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 */
	}

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	rcu_assign_pointer(ifibss->presp, skb);
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	sdata->vif.bss_conf.beacon_int = beacon_int;
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	sdata->vif.bss_conf.basic_rates = basic_rates;
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	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;
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	bss_change |= BSS_CHANGED_BASIC_RATES;
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	bss_change |= BSS_CHANGED_HT;
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	bss_change |= BSS_CHANGED_IBSS;
	sdata->vif.bss_conf.ibss_joined = true;
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	ieee80211_bss_info_change_notify(sdata, bss_change);
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	ieee80211_sta_def_wmm_params(sdata, sband->n_bitrates, supp_rates);
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	ifibss->state = IEEE80211_IBSS_MLME_JOINED;
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	mod_timer(&ifibss->timer,
		  round_jiffies(jiffies + IEEE80211_IBSS_MERGE_INTERVAL));
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	bss = cfg80211_inform_bss_frame(local->hw.wiphy, local->hw.conf.channel,
					mgmt, skb->len, 0, GFP_KERNEL);
	cfg80211_put_bss(bss);
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	netif_carrier_on(sdata->dev);
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	cfg80211_ibss_joined(sdata->dev, ifibss->bssid, GFP_KERNEL);
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}

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

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	if (beacon_int < 10)
		beacon_int = 10;

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

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

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

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

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

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	sta_info_pre_move_state(sta, IEEE80211_STA_AUTH);
	sta_info_pre_move_state(sta, IEEE80211_STA_ASSOC);
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	/* 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);
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	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);
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	if (auth) {
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		ibss_vdbg("TX Auth SA=%pM DA=%pM BSSID=%pM (auth_transaction=1)\n",
			  sdata->vif.addr, sdata->u.ibss.bssid, addr);
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		ieee80211_send_auth(sdata, 1, WLAN_AUTH_OPEN, NULL, 0,
				    addr, sdata->u.ibss.bssid, NULL, 0, 0);
	}
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	return sta;
}

static struct sta_info *
ieee80211_ibss_add_sta(struct ieee80211_sub_if_data *sdata,
		       const u8 *bssid, const u8 *addr,
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		       u32 supp_rates, bool auth)
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	__acquires(RCU)
{
	struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;
	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) {
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		net_dbg_ratelimited("%s: No room for a new IBSS STA entry %pM\n",
				    sdata->name, addr);
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		rcu_read_lock();
		return NULL;
	}

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

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

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	return ieee80211_ibss_finish_sta(sta, auth);
}

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;

	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;
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	ibss_vdbg("%s: RX Auth SA=%pM DA=%pM BSSID=%pM (auth_transaction=%d)\n",
		  sdata->name, mgmt->sa, mgmt->da, mgmt->bssid,
		  auth_transaction);
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	sta_info_destroy_addr(sdata, mgmt->sa);
	ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa, 0, false);
	rcu_read_unlock();

	/*
	 * 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);
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}

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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;
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	struct cfg80211_bss *cbss;
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	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;
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	struct ieee80211_supported_band *sband = local->hw.wiphy->bands[band];
	bool rates_updated = false;
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	if (elems->ds_params && elems->ds_params_len == 1)
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		freq = ieee80211_channel_to_frequency(elems->ds_params[0],
						      band);
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	else
		freq = rx_status->freq;

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

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

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	if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
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	    ether_addr_equal(mgmt->bssid, sdata->u.ibss.bssid)) {
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		rcu_read_lock();
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		sta = sta_info_get(sdata, mgmt->sa);
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		if (elems->supp_rates) {
			supp_rates = ieee80211_sta_get_rates(local, elems,
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							     band, NULL);
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			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);
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				if (sta->sta.supp_rates[band] != prev_rates) {
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					ibss_vdbg("%s: updated supp_rates set for %pM based on beacon/probe_resp (0x%x -> 0x%x)\n",
						  sdata->name, sta->sta.addr,
						  prev_rates,
						  sta->sta.supp_rates[band]);
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					rates_updated = true;
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				}
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			} else {
				rcu_read_unlock();
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				sta = ieee80211_ibss_add_sta(sdata, mgmt->bssid,
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						mgmt->sa, supp_rates, true);
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			}
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		}
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		if (sta && elems->wmm_info)
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			set_sta_flag(sta, WLAN_STA_WME);
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		if (sta && elems->ht_operation && elems->ht_cap_elem &&
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		    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 =
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				ieee80211_ht_oper_to_channel_type(
							elems->ht_operation);
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			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
			 */
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			if (!(channel_type == NL80211_CHAN_HT40MINUS ||
			      channel_type == NL80211_CHAN_HT40PLUS) ||
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			    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)
			rate_control_rate_init(sta);

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		rcu_read_unlock();
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	}

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

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

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	/* was just updated in ieee80211_bss_info_update */
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	beacon_timestamp = cbss->tsf;
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	/* check if we need to merge IBSS */

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

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

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

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

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	if (rx_status->flag & RX_FLAG_MACTIME_MPDU) {
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		/*
		 * 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);
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	} else {
		/*
		 * second best option: get current TSF
		 * (will return -1 if not supported)
		 */
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		rx_timestamp = drv_get_tsf(local, sdata);
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	}
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	ibss_vdbg("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);
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	if (beacon_timestamp > rx_timestamp) {
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		ibss_vdbg("%s: beacon TSF higher than local TSF - IBSS merge with BSSID %pM\n",
			  sdata->name, mgmt->bssid);
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		ieee80211_sta_join_ibss(sdata, bss);
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		supp_rates = ieee80211_sta_get_rates(local, elems, band, NULL);
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		ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa,
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				       supp_rates, true);
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		rcu_read_unlock();
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	}

 put_bss:
	ieee80211_rx_bss_put(local, bss);
}

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

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

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	if (ifibss->state == IEEE80211_IBSS_MLME_SEARCH)
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		return;
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	if (!ether_addr_equal(bssid, sdata->u.ibss.bssid))
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		return;
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	sta = sta_info_alloc(sdata, addr, GFP_ATOMIC);
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	if (!sta)
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		return;
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	sta->last_rx = jiffies;
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	/* make sure mandatory rates are always added */
	sta->sta.supp_rates[band] = supp_rates |
			ieee80211_mandatory_rates(local, band);

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

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;

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

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	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;
}

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/*
 * This function is called with state == IEEE80211_IBSS_MLME_JOINED
 */
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static void ieee80211_sta_merge_ibss(struct ieee80211_sub_if_data *sdata)
{
	struct ieee80211_if_ibss *ifibss = &sdata->u.ibss;

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	lockdep_assert_held(&ifibss->mtx);

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	mod_timer(&ifibss->timer,
		  round_jiffies(jiffies + IEEE80211_IBSS_MERGE_INTERVAL));
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	ieee80211_sta_expire(sdata, IEEE80211_IBSS_INACTIVITY_LIMIT);
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	if (time_before(jiffies, ifibss->last_scan_completed +
		       IEEE80211_IBSS_MERGE_INTERVAL))
		return;

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	if (ieee80211_sta_active_ibss(sdata))
		return;

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	if (ifibss->fixed_channel)
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		return;

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	pr_debug("%s: No active IBSS STAs - trying to scan for other IBSS networks with same SSID (merge)\n",
		 sdata->name);
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	ieee80211_request_internal_scan(sdata,
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			ifibss->ssid, ifibss->ssid_len, NULL);
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}

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

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	lockdep_assert_held(&ifibss->mtx);

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	if (ifibss->fixed_bssid) {
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		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++)
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			bssid[i] ^= sdata->vif.addr[i];
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		bssid[0] &= ~0x01;
		bssid[0] |= 0x02;
	}

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	pr_debug("%s: Creating new IBSS network, BSSID %pM\n",
		 sdata->name, bssid);
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	capability = WLAN_CAPABILITY_IBSS;

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

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

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

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

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	active_ibss = ieee80211_sta_active_ibss(sdata);
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	ibss_vdbg("%s: sta_find_ibss (active_ibss=%d)\n",
		  sdata->name, active_ibss);
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	if (active_ibss)
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		return;
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	capability = WLAN_CAPABILITY_IBSS;
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	if (ifibss->privacy)
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		capability |= WLAN_CAPABILITY_PRIVACY;
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	if (ifibss->fixed_bssid)
		bssid = ifibss->bssid;
	if (ifibss->fixed_channel)
		chan = ifibss->channel;
	if (!is_zero_ether_addr(ifibss->bssid))
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		bssid = ifibss->bssid;
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	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;
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		bss = (void *)cbss->priv;
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		ibss_vdbg("   sta_find_ibss: selected %pM current %pM\n",
			  cbss->bssid, ifibss->bssid);
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		pr_debug("%s: Selected IBSS BSSID %pM based on configured SSID\n",
			 sdata->name, cbss->bssid);
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		ieee80211_sta_join_ibss(sdata, bss);
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		ieee80211_rx_bss_put(local, bss);
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		return;
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	}
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	ibss_vdbg("   did not try to join ibss\n");
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	/* Selected IBSS not found in current scan results - try to scan */
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	if (time_after(jiffies, ifibss->last_scan_completed +
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					IEEE80211_SCAN_INTERVAL)) {
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		pr_debug("%s: Trigger new scan to find an IBSS to join\n",
			 sdata->name);
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		ieee80211_request_internal_scan(sdata,
				ifibss->ssid, ifibss->ssid_len,
				ifibss->fixed_channel ? ifibss->channel : NULL);
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	} else {
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		int interval = IEEE80211_SCAN_INTERVAL;

		if (time_after(jiffies, ifibss->ibss_join_req +
			       IEEE80211_IBSS_JOIN_TIMEOUT)) {
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			if (!(local->oper_channel->flags & IEEE80211_CHAN_NO_IBSS)) {
				ieee80211_sta_create_ibss(sdata);
				return;
			}
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			pr_debug("%s: IBSS not allowed on %d MHz\n",
				 sdata->name,
				 local->hw.conf.channel->center_freq);
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			/* No IBSS found - decrease scan interval and continue
			 * scanning. */
			interval = IEEE80211_SCAN_INTERVAL_SLOW;
		}

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

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

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	lockdep_assert_held(&ifibss->mtx);

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

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

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	tx_last_beacon = drv_tx_last_beacon(local);
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	ibss_vdbg("%s: RX ProbeReq SA=%pM DA=%pM BSSID=%pM (tx_last_beacon=%d)\n",
		  sdata->name, mgmt->sa, mgmt->da,
		  mgmt->bssid, tx_last_beacon);
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	if (!tx_last_beacon && is_multicast_ether_addr(mgmt->da))
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		return;

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

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

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

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

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);
}

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

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

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

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

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	switch (fc & IEEE80211_FCTL_STYPE) {
	case IEEE80211_STYPE_PROBE_REQ:
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		ieee80211_rx_mgmt_probe_req(sdata, skb);
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		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;
	}
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 mgmt_out:
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	mutex_unlock(&sdata->u.ibss.mtx);
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}

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

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

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	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;
	}

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

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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;

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

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

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#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