net/mac80211/scan.c - kernel/msm - Gitiles

 /*
  * Scanning implementation
  *
  * Copyright 2003, Jouni Malinen <jkmaline@cc.hut.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>
  *
  * 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.
  */

 /* TODO: figure out how to avoid that the "current BSS" expires */

 #include <linux/wireless.h>
 #include <linux/if_arp.h>
 #include <linux/rtnetlink.h>
 #include <net/mac80211.h>
 #include <net/iw_handler.h>

 #include "ieee80211_i.h"
 #include "mesh.h"

 #define IEEE80211_PROBE_DELAY (HZ / 33)
 #define IEEE80211_CHANNEL_TIME (HZ / 33)
 #define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)

 struct ieee80211_bss *
 ieee80211_rx_bss_get(struct ieee80211_local *local, u8 *bssid, int freq,
 		     u8 *ssid, u8 ssid_len)
 {
 	return (void *)cfg80211_get_bss(local->hw.wiphy,
 					ieee80211_get_channel(local->hw.wiphy,
 							      freq),
 					bssid, ssid, ssid_len,
 					0, 0);
 }

 static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
 {
 	struct ieee80211_bss *bss = (void *)cbss;

 	kfree(bss_mesh_id(bss));
 	kfree(bss_mesh_cfg(bss));
 }

 void ieee80211_rx_bss_put(struct ieee80211_local *local,
 			  struct ieee80211_bss *bss)
 {
 	cfg80211_put_bss((struct cfg80211_bss *)bss);
 }

 struct ieee80211_bss *
 ieee80211_bss_info_update(struct ieee80211_local *local,
 			  struct ieee80211_rx_status *rx_status,
 			  struct ieee80211_mgmt *mgmt,
 			  size_t len,
 			  struct ieee802_11_elems *elems,
 			  struct ieee80211_channel *channel,
 			  bool beacon)
 {
 	struct ieee80211_bss *bss;
 	int clen;
 	enum cfg80211_signal_type sigtype = CFG80211_SIGNAL_TYPE_NONE;
 	s32 signal = 0;

 	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM) {
 		sigtype = CFG80211_SIGNAL_TYPE_MBM;
 		signal = rx_status->signal * 100;
 	} else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC) {
 		sigtype = CFG80211_SIGNAL_TYPE_UNSPEC;
 		signal = (rx_status->signal * 100) / local->hw.max_signal;
 	}

 	bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
 						mgmt, len, signal, sigtype,
 						GFP_ATOMIC);

 	if (!bss)
 		return NULL;

 	bss->cbss.free_priv = ieee80211_rx_bss_free;

 	/* save the ERP value so that it is available at association time */
 	if (elems->erp_info && elems->erp_info_len >= 1) {
 		bss->erp_value = elems->erp_info[0];
 		bss->has_erp_value = 1;
 	}

 	if (elems->tim) {
 		struct ieee80211_tim_ie *tim_ie =
 			(struct ieee80211_tim_ie *)elems->tim;
 		bss->dtim_period = tim_ie->dtim_period;
 	}

 	/* set default value for buggy APs */
 	if (!elems->tim || bss->dtim_period == 0)
 		bss->dtim_period = 1;

 	bss->supp_rates_len = 0;
 	if (elems->supp_rates) {
 		clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 		if (clen > elems->supp_rates_len)
 			clen = elems->supp_rates_len;
 		memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
 		       clen);
 		bss->supp_rates_len += clen;
 	}
 	if (elems->ext_supp_rates) {
 		clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
 		if (clen > elems->ext_supp_rates_len)
 			clen = elems->ext_supp_rates_len;
 		memcpy(&bss->supp_rates[bss->supp_rates_len],
 		       elems->ext_supp_rates, clen);
 		bss->supp_rates_len += clen;
 	}

 	bss->wmm_used = elems->wmm_param || elems->wmm_info;

 	if (!beacon)
 		bss->last_probe_resp = jiffies;

 	return bss;
 }

 void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data *sdata, u8 *bssid,
 			     int freq, u8 *ssid, u8 ssid_len)
 {
 	struct ieee80211_bss *bss;
 	struct ieee80211_local *local = sdata->local;

 	bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
 	if (bss) {
 		cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
 		ieee80211_rx_bss_put(local, bss);
 	}
 }

 ieee80211_rx_result
 ieee80211_scan_rx(struct ieee80211_sub_if_data *sdata, struct sk_buff *skb,
 		  struct ieee80211_rx_status *rx_status)
 {
 	struct ieee80211_mgmt *mgmt;
 	struct ieee80211_bss *bss;
 	u8 *elements;
 	struct ieee80211_channel *channel;
 	size_t baselen;
 	int freq;
 	__le16 fc;
 	bool presp, beacon = false;
 	struct ieee802_11_elems elems;

 	if (skb->len < 2)
 		return RX_DROP_UNUSABLE;

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

 	if (ieee80211_is_ctl(fc))
 		return RX_CONTINUE;

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

 	presp = ieee80211_is_probe_resp(fc);
 	if (presp) {
 		/* ignore ProbeResp to foreign address */
 		if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
 			return RX_DROP_MONITOR;

 		presp = true;
 		elements = mgmt->u.probe_resp.variable;
 		baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
 	} else {
 		beacon = ieee80211_is_beacon(fc);
 		baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
 		elements = mgmt->u.beacon.variable;
 	}

 	if (!presp && !beacon)
 		return RX_CONTINUE;

 	if (baselen > skb->len)
 		return RX_DROP_MONITOR;

 	ieee802_11_parse_elems(elements, skb->len - baselen, &elems);

 	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(sdata->local->hw.wiphy, freq);

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

 	bss = ieee80211_bss_info_update(sdata->local, rx_status,
 					mgmt, skb->len, &elems,
 					channel, beacon);
 	if (bss)
 		ieee80211_rx_bss_put(sdata->local, bss);

 	dev_kfree_skb(skb);
 	return RX_QUEUED;
 }

 void ieee80211_send_nullfunc(struct ieee80211_local *local,
 				    struct ieee80211_sub_if_data *sdata,
 				    int powersave)
 {
 	struct sk_buff *skb;
 	struct ieee80211_hdr *nullfunc;
 	__le16 fc;

 	skb = dev_alloc_skb(local->hw.extra_tx_headroom + 24);
 	if (!skb) {
 		printk(KERN_DEBUG "%s: failed to allocate buffer for nullfunc "
 		       "frame\n", sdata->dev->name);
 		return;
 	}
 	skb_reserve(skb, local->hw.extra_tx_headroom);

 	nullfunc = (struct ieee80211_hdr *) skb_put(skb, 24);
 	memset(nullfunc, 0, 24);
 	fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_NULLFUNC |
 			 IEEE80211_FCTL_TODS);
 	if (powersave)
 		fc |= cpu_to_le16(IEEE80211_FCTL_PM);
 	nullfunc->frame_control = fc;
 	memcpy(nullfunc->addr1, sdata->u.sta.bssid, ETH_ALEN);
 	memcpy(nullfunc->addr2, sdata->dev->dev_addr, ETH_ALEN);
 	memcpy(nullfunc->addr3, sdata->u.sta.bssid, ETH_ALEN);

 	ieee80211_tx_skb(sdata, skb, 0);
 }

 void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct ieee80211_sub_if_data *sdata;

 	if (WARN_ON(!local->hw_scanning && !local->sw_scanning))
 		return;

 	if (WARN_ON(!local->scan_req))
 		return;

 	if (local->scan_req != &local->int_scan_req)
 		cfg80211_scan_done(local->scan_req, aborted);
 	local->scan_req = NULL;

 	local->last_scan_completed = jiffies;

 	if (local->hw_scanning) {
 		local->hw_scanning = false;
 		/*
 		 * Somebody might have requested channel change during scan
 		 * that we won't have acted upon, try now. ieee80211_hw_config
 		 * will set the flag based on actual changes.
 		 */
 		ieee80211_hw_config(local, 0);
 		goto done;
 	}

 	local->sw_scanning = false;
 	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);

 	netif_tx_lock_bh(local->mdev);
 	netif_addr_lock(local->mdev);
 	local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
 	local->ops->configure_filter(local_to_hw(local),
 				     FIF_BCN_PRBRESP_PROMISC,
 				     &local->filter_flags,
 				     local->mdev->mc_count,
 				     local->mdev->mc_list);

 	netif_addr_unlock(local->mdev);
 	netif_tx_unlock_bh(local->mdev);

 	mutex_lock(&local->iflist_mtx);
 	list_for_each_entry(sdata, &local->interfaces, list) {
 		if (!netif_running(sdata->dev))
 			continue;

 		/* Tell AP we're back */
 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 			if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
 				ieee80211_send_nullfunc(local, sdata, 0);
 				netif_tx_wake_all_queues(sdata->dev);
 			}
 		} else
 			netif_tx_wake_all_queues(sdata->dev);

 		/* re-enable beaconing */
 		if (sdata->vif.type == NL80211_IFTYPE_AP ||
 		    sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 		    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 			ieee80211_if_config(sdata,
 					    IEEE80211_IFCC_BEACON_ENABLED);
 	}
 	mutex_unlock(&local->iflist_mtx);

  done:
 	ieee80211_mlme_notify_scan_completed(local);
 	ieee80211_mesh_notify_scan_completed(local);
 }
 EXPORT_SYMBOL(ieee80211_scan_completed);

 void ieee80211_scan_work(struct work_struct *work)
 {
 	struct ieee80211_local *local =
 		container_of(work, struct ieee80211_local, scan_work.work);
 	struct ieee80211_sub_if_data *sdata = local->scan_sdata;
 	struct ieee80211_channel *chan;
 	int skip, i;
 	unsigned long next_delay = 0;

 	/*
 	 * Avoid re-scheduling when the sdata is going away.
 	 */
 	if (!netif_running(sdata->dev))
 		return;

 	switch (local->scan_state) {
 	case SCAN_SET_CHANNEL:
 		/* if no more bands/channels left, complete scan */
 		if (local->scan_channel_idx >= local->scan_req->n_channels) {
 			ieee80211_scan_completed(local_to_hw(local), false);
 			return;
 		}
 		skip = 0;
 		chan = local->scan_req->channels[local->scan_channel_idx];

 		if (chan->flags & IEEE80211_CHAN_DISABLED ||
 		    (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
 		     chan->flags & IEEE80211_CHAN_NO_IBSS))
 			skip = 1;

 		if (!skip) {
 			local->scan_channel = chan;
 			if (ieee80211_hw_config(local,
 						IEEE80211_CONF_CHANGE_CHANNEL))
 				skip = 1;
 		}

 		/* advance state machine to next channel/band */
 		local->scan_channel_idx++;

 		if (skip)
 			break;

 		next_delay = IEEE80211_PROBE_DELAY +
 			     usecs_to_jiffies(local->hw.channel_change_time);
 		local->scan_state = SCAN_SEND_PROBE;
 		break;
 	case SCAN_SEND_PROBE:
 		next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
 		local->scan_state = SCAN_SET_CHANNEL;

 		if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN ||
 		    !local->scan_req->n_ssids)
 			break;
 		for (i = 0; i < local->scan_req->n_ssids; i++)
 			ieee80211_send_probe_req(
 				sdata, NULL,
 				local->scan_req->ssids[i].ssid,
 				local->scan_req->ssids[i].ssid_len);
 		next_delay = IEEE80211_CHANNEL_TIME;
 		break;
 	}

 	queue_delayed_work(local->hw.workqueue, &local->scan_work,
 			   next_delay);
 }


 int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
 			 struct cfg80211_scan_request *req)
 {
 	struct ieee80211_local *local = scan_sdata->local;
 	struct ieee80211_sub_if_data *sdata;

 	if (!req)
 		return -EINVAL;

 	if (local->scan_req && local->scan_req != req)
 		return -EBUSY;

 	local->scan_req = req;

 	/* MLME-SCAN.request (page 118)  page 144 (11.1.3.1)
 	 * BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
 	 * BSSID: MACAddress
 	 * SSID
 	 * ScanType: ACTIVE, PASSIVE
 	 * ProbeDelay: delay (in microseconds) to be used prior to transmitting
 	 *    a Probe frame during active scanning
 	 * ChannelList
 	 * MinChannelTime (>= ProbeDelay), in TU
 	 * MaxChannelTime: (>= MinChannelTime), in TU
 	 */

 	 /* MLME-SCAN.confirm
 	  * BSSDescriptionSet
 	  * ResultCode: SUCCESS, INVALID_PARAMETERS
 	 */

 	if (local->sw_scanning || local->hw_scanning) {
 		if (local->scan_sdata == scan_sdata)
 			return 0;
 		return -EBUSY;
 	}

 	if (local->ops->hw_scan) {
 		int rc;

 		local->hw_scanning = true;
 		rc = local->ops->hw_scan(local_to_hw(local), req);
 		if (rc) {
 			local->hw_scanning = false;
 			return rc;
 		}
 		local->scan_sdata = scan_sdata;
 		return 0;
 	}

 	local->sw_scanning = true;

 	mutex_lock(&local->iflist_mtx);
 	list_for_each_entry(sdata, &local->interfaces, list) {
 		if (!netif_running(sdata->dev))
 			continue;

 		/* disable beaconing */
 		if (sdata->vif.type == NL80211_IFTYPE_AP ||
 		    sdata->vif.type == NL80211_IFTYPE_ADHOC ||
 		    sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
 			ieee80211_if_config(sdata,
 					    IEEE80211_IFCC_BEACON_ENABLED);

 		if (sdata->vif.type == NL80211_IFTYPE_STATION) {
 			if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
 				netif_tx_stop_all_queues(sdata->dev);
 				ieee80211_send_nullfunc(local, sdata, 1);
 			}
 		} else
 			netif_tx_stop_all_queues(sdata->dev);
 	}
 	mutex_unlock(&local->iflist_mtx);

 	local->scan_state = SCAN_SET_CHANNEL;
 	local->scan_channel_idx = 0;
 	local->scan_sdata = scan_sdata;
 	local->scan_req = req;

 	netif_addr_lock_bh(local->mdev);
 	local->filter_flags |= FIF_BCN_PRBRESP_PROMISC;
 	local->ops->configure_filter(local_to_hw(local),
 				     FIF_BCN_PRBRESP_PROMISC,
 				     &local->filter_flags,
 				     local->mdev->mc_count,
 				     local->mdev->mc_list);
 	netif_addr_unlock_bh(local->mdev);

 	/* TODO: start scan as soon as all nullfunc frames are ACKed */
 	queue_delayed_work(local->hw.workqueue, &local->scan_work,
 			   IEEE80211_CHANNEL_TIME);

 	return 0;
 }


 int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
 			   struct cfg80211_scan_request *req)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_if_sta *ifsta;

 	if (!req)
 		return -EINVAL;

 	if (local->scan_req && local->scan_req != req)
 		return -EBUSY;

 	local->scan_req = req;

 	if (sdata->vif.type != NL80211_IFTYPE_STATION)
 		return ieee80211_start_scan(sdata, req);

 	/*
 	 * STA has a state machine that might need to defer scanning
 	 * while it's trying to associate/authenticate, therefore we
 	 * queue it up to the state machine in that case.
 	 */

 	if (local->sw_scanning || local->hw_scanning) {
 		if (local->scan_sdata == sdata)
 			return 0;
 		return -EBUSY;
 	}

 	ifsta = &sdata->u.sta;
 	set_bit(IEEE80211_STA_REQ_SCAN, &ifsta->request);
 	queue_work(local->hw.workqueue, &ifsta->work);

 	return 0;
 }
	/*
	* Scanning implementation
	*
	* Copyright 2003, Jouni Malinen <jkmaline@cc.hut.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>
	*
	* 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.
	*/

	/* TODO: figure out how to avoid that the "current BSS" expires */

	#include <linux/wireless.h>
	#include <linux/if_arp.h>
	#include <linux/rtnetlink.h>
	#include <net/mac80211.h>
	#include <net/iw_handler.h>

	#include "ieee80211_i.h"
	#include "mesh.h"

	#define IEEE80211_PROBE_DELAY (HZ / 33)
	#define IEEE80211_CHANNEL_TIME (HZ / 33)
	#define IEEE80211_PASSIVE_CHANNEL_TIME (HZ / 5)

	struct ieee80211_bss *
	ieee80211_rx_bss_get(struct ieee80211_local local, u8 bssid, int freq,
	u8 *ssid, u8 ssid_len)
	{
	return (void *)cfg80211_get_bss(local->hw.wiphy,
	ieee80211_get_channel(local->hw.wiphy,
	freq),
	bssid, ssid, ssid_len,
	0, 0);
	}

	static void ieee80211_rx_bss_free(struct cfg80211_bss *cbss)
	{
	struct ieee80211_bss bss = (void )cbss;

	kfree(bss_mesh_id(bss));
	kfree(bss_mesh_cfg(bss));
	}

	void ieee80211_rx_bss_put(struct ieee80211_local *local,
	struct ieee80211_bss *bss)
	{
	cfg80211_put_bss((struct cfg80211_bss *)bss);
	}

	struct ieee80211_bss *
	ieee80211_bss_info_update(struct ieee80211_local *local,
	struct ieee80211_rx_status *rx_status,
	struct ieee80211_mgmt *mgmt,
	size_t len,
	struct ieee802_11_elems *elems,
	struct ieee80211_channel *channel,
	bool beacon)
	{
	struct ieee80211_bss *bss;
	int clen;
	enum cfg80211_signal_type sigtype = CFG80211_SIGNAL_TYPE_NONE;
	s32 signal = 0;

	if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM) {
	sigtype = CFG80211_SIGNAL_TYPE_MBM;
	signal = rx_status->signal * 100;
	} else if (local->hw.flags & IEEE80211_HW_SIGNAL_UNSPEC) {
	sigtype = CFG80211_SIGNAL_TYPE_UNSPEC;
	signal = (rx_status->signal * 100) / local->hw.max_signal;
	}

	bss = (void *)cfg80211_inform_bss_frame(local->hw.wiphy, channel,
	mgmt, len, signal, sigtype,
	GFP_ATOMIC);

	if (!bss)
	return NULL;

	bss->cbss.free_priv = ieee80211_rx_bss_free;

	/* save the ERP value so that it is available at association time */
	if (elems->erp_info && elems->erp_info_len >= 1) {
	bss->erp_value = elems->erp_info[0];
	bss->has_erp_value = 1;
	}

	if (elems->tim) {
	struct ieee80211_tim_ie *tim_ie =
	(struct ieee80211_tim_ie *)elems->tim;
	bss->dtim_period = tim_ie->dtim_period;
	}

	/* set default value for buggy APs */
	if (!elems->tim \|\| bss->dtim_period == 0)
	bss->dtim_period = 1;

	bss->supp_rates_len = 0;
	if (elems->supp_rates) {
	clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
	if (clen > elems->supp_rates_len)
	clen = elems->supp_rates_len;
	memcpy(&bss->supp_rates[bss->supp_rates_len], elems->supp_rates,
	clen);
	bss->supp_rates_len += clen;
	}
	if (elems->ext_supp_rates) {
	clen = IEEE80211_MAX_SUPP_RATES - bss->supp_rates_len;
	if (clen > elems->ext_supp_rates_len)
	clen = elems->ext_supp_rates_len;
	memcpy(&bss->supp_rates[bss->supp_rates_len],
	elems->ext_supp_rates, clen);
	bss->supp_rates_len += clen;
	}

	bss->wmm_used = elems->wmm_param \|\| elems->wmm_info;

	if (!beacon)
	bss->last_probe_resp = jiffies;

	return bss;
	}

	void ieee80211_rx_bss_remove(struct ieee80211_sub_if_data sdata, u8 bssid,
	int freq, u8 *ssid, u8 ssid_len)
	{
	struct ieee80211_bss *bss;
	struct ieee80211_local *local = sdata->local;

	bss = ieee80211_rx_bss_get(local, bssid, freq, ssid, ssid_len);
	if (bss) {
	cfg80211_unlink_bss(local->hw.wiphy, (void *)bss);
	ieee80211_rx_bss_put(local, bss);
	}
	}

	ieee80211_rx_result
	ieee80211_scan_rx(struct ieee80211_sub_if_data sdata, struct sk_buff skb,
	struct ieee80211_rx_status *rx_status)
	{
	struct ieee80211_mgmt *mgmt;
	struct ieee80211_bss *bss;
	u8 *elements;
	struct ieee80211_channel *channel;
	size_t baselen;
	int freq;
	__le16 fc;
	bool presp, beacon = false;
	struct ieee802_11_elems elems;

	if (skb->len < 2)
	return RX_DROP_UNUSABLE;

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

	if (ieee80211_is_ctl(fc))
	return RX_CONTINUE;

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

	presp = ieee80211_is_probe_resp(fc);
	if (presp) {
	/* ignore ProbeResp to foreign address */
	if (memcmp(mgmt->da, sdata->dev->dev_addr, ETH_ALEN))
	return RX_DROP_MONITOR;

	presp = true;
	elements = mgmt->u.probe_resp.variable;
	baselen = offsetof(struct ieee80211_mgmt, u.probe_resp.variable);
	} else {
	beacon = ieee80211_is_beacon(fc);
	baselen = offsetof(struct ieee80211_mgmt, u.beacon.variable);
	elements = mgmt->u.beacon.variable;
	}

	if (!presp && !beacon)
	return RX_CONTINUE;

	if (baselen > skb->len)
	return RX_DROP_MONITOR;

	ieee802_11_parse_elems(elements, skb->len - baselen, &elems);

	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(sdata->local->hw.wiphy, freq);

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

	bss = ieee80211_bss_info_update(sdata->local, rx_status,
	mgmt, skb->len, &elems,
	channel, beacon);
	if (bss)
	ieee80211_rx_bss_put(sdata->local, bss);

	dev_kfree_skb(skb);
	return RX_QUEUED;
	}

	void ieee80211_send_nullfunc(struct ieee80211_local *local,
	struct ieee80211_sub_if_data *sdata,
	int powersave)
	{
	struct sk_buff *skb;
	struct ieee80211_hdr *nullfunc;
	__le16 fc;

	skb = dev_alloc_skb(local->hw.extra_tx_headroom + 24);
	if (!skb) {
	printk(KERN_DEBUG "%s: failed to allocate buffer for nullfunc "
	"frame\n", sdata->dev->name);
	return;
	}
	skb_reserve(skb, local->hw.extra_tx_headroom);

	nullfunc = (struct ieee80211_hdr *) skb_put(skb, 24);
	memset(nullfunc, 0, 24);
	fc = cpu_to_le16(IEEE80211_FTYPE_DATA \| IEEE80211_STYPE_NULLFUNC \|
	IEEE80211_FCTL_TODS);
	if (powersave)
	fc \|= cpu_to_le16(IEEE80211_FCTL_PM);
	nullfunc->frame_control = fc;
	memcpy(nullfunc->addr1, sdata->u.sta.bssid, ETH_ALEN);
	memcpy(nullfunc->addr2, sdata->dev->dev_addr, ETH_ALEN);
	memcpy(nullfunc->addr3, sdata->u.sta.bssid, ETH_ALEN);

	ieee80211_tx_skb(sdata, skb, 0);
	}

	void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
	{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_sub_if_data *sdata;

	if (WARN_ON(!local->hw_scanning && !local->sw_scanning))
	return;

	if (WARN_ON(!local->scan_req))
	return;

	if (local->scan_req != &local->int_scan_req)
	cfg80211_scan_done(local->scan_req, aborted);
	local->scan_req = NULL;

	local->last_scan_completed = jiffies;

	if (local->hw_scanning) {
	local->hw_scanning = false;
	/*
	* Somebody might have requested channel change during scan
	* that we won't have acted upon, try now. ieee80211_hw_config
	* will set the flag based on actual changes.
	*/
	ieee80211_hw_config(local, 0);
	goto done;
	}

	local->sw_scanning = false;
	ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);

	netif_tx_lock_bh(local->mdev);
	netif_addr_lock(local->mdev);
	local->filter_flags &= ~FIF_BCN_PRBRESP_PROMISC;
	local->ops->configure_filter(local_to_hw(local),
	FIF_BCN_PRBRESP_PROMISC,
	&local->filter_flags,
	local->mdev->mc_count,
	local->mdev->mc_list);

	netif_addr_unlock(local->mdev);
	netif_tx_unlock_bh(local->mdev);

	mutex_lock(&local->iflist_mtx);
	list_for_each_entry(sdata, &local->interfaces, list) {
	if (!netif_running(sdata->dev))
	continue;

	/* Tell AP we're back */
	if (sdata->vif.type == NL80211_IFTYPE_STATION) {
	if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
	ieee80211_send_nullfunc(local, sdata, 0);
	netif_tx_wake_all_queues(sdata->dev);
	}
	} else
	netif_tx_wake_all_queues(sdata->dev);

	/* re-enable beaconing */
	if (sdata->vif.type == NL80211_IFTYPE_AP \|\|
	sdata->vif.type == NL80211_IFTYPE_ADHOC \|\|
	sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
	ieee80211_if_config(sdata,
	IEEE80211_IFCC_BEACON_ENABLED);
	}
	mutex_unlock(&local->iflist_mtx);

	done:
	ieee80211_mlme_notify_scan_completed(local);
	ieee80211_mesh_notify_scan_completed(local);
	}
	EXPORT_SYMBOL(ieee80211_scan_completed);

	void ieee80211_scan_work(struct work_struct *work)
	{
	struct ieee80211_local *local =
	container_of(work, struct ieee80211_local, scan_work.work);
	struct ieee80211_sub_if_data *sdata = local->scan_sdata;
	struct ieee80211_channel *chan;
	int skip, i;
	unsigned long next_delay = 0;

	/*
	* Avoid re-scheduling when the sdata is going away.
	*/
	if (!netif_running(sdata->dev))
	return;

	switch (local->scan_state) {
	case SCAN_SET_CHANNEL:
	/* if no more bands/channels left, complete scan */
	if (local->scan_channel_idx >= local->scan_req->n_channels) {
	ieee80211_scan_completed(local_to_hw(local), false);
	return;
	}
	skip = 0;
	chan = local->scan_req->channels[local->scan_channel_idx];

	if (chan->flags & IEEE80211_CHAN_DISABLED \|\|
	(sdata->vif.type == NL80211_IFTYPE_ADHOC &&
	chan->flags & IEEE80211_CHAN_NO_IBSS))
	skip = 1;

	if (!skip) {
	local->scan_channel = chan;
	if (ieee80211_hw_config(local,
	IEEE80211_CONF_CHANGE_CHANNEL))
	skip = 1;
	}

	/* advance state machine to next channel/band */
	local->scan_channel_idx++;

	if (skip)
	break;

	next_delay = IEEE80211_PROBE_DELAY +
	usecs_to_jiffies(local->hw.channel_change_time);
	local->scan_state = SCAN_SEND_PROBE;
	break;
	case SCAN_SEND_PROBE:
	next_delay = IEEE80211_PASSIVE_CHANNEL_TIME;
	local->scan_state = SCAN_SET_CHANNEL;

	if (local->scan_channel->flags & IEEE80211_CHAN_PASSIVE_SCAN \|\|
	!local->scan_req->n_ssids)
	break;
	for (i = 0; i < local->scan_req->n_ssids; i++)
	ieee80211_send_probe_req(
	sdata, NULL,
	local->scan_req->ssids[i].ssid,
	local->scan_req->ssids[i].ssid_len);
	next_delay = IEEE80211_CHANNEL_TIME;
	break;
	}

	queue_delayed_work(local->hw.workqueue, &local->scan_work,
	next_delay);
	}


	int ieee80211_start_scan(struct ieee80211_sub_if_data *scan_sdata,
	struct cfg80211_scan_request *req)
	{
	struct ieee80211_local *local = scan_sdata->local;
	struct ieee80211_sub_if_data *sdata;

	if (!req)
	return -EINVAL;

	if (local->scan_req && local->scan_req != req)
	return -EBUSY;

	local->scan_req = req;

	/* MLME-SCAN.request (page 118) page 144 (11.1.3.1)
	* BSSType: INFRASTRUCTURE, INDEPENDENT, ANY_BSS
	* BSSID: MACAddress
	* SSID
	* ScanType: ACTIVE, PASSIVE
	* ProbeDelay: delay (in microseconds) to be used prior to transmitting
	* a Probe frame during active scanning
	* ChannelList
	* MinChannelTime (>= ProbeDelay), in TU
	* MaxChannelTime: (>= MinChannelTime), in TU
	*/

	/* MLME-SCAN.confirm
	* BSSDescriptionSet
	* ResultCode: SUCCESS, INVALID_PARAMETERS
	*/

	if (local->sw_scanning \|\| local->hw_scanning) {
	if (local->scan_sdata == scan_sdata)
	return 0;
	return -EBUSY;
	}

	if (local->ops->hw_scan) {
	int rc;

	local->hw_scanning = true;
	rc = local->ops->hw_scan(local_to_hw(local), req);
	if (rc) {
	local->hw_scanning = false;
	return rc;
	}
	local->scan_sdata = scan_sdata;
	return 0;
	}

	local->sw_scanning = true;

	mutex_lock(&local->iflist_mtx);
	list_for_each_entry(sdata, &local->interfaces, list) {
	if (!netif_running(sdata->dev))
	continue;

	/* disable beaconing */
	if (sdata->vif.type == NL80211_IFTYPE_AP \|\|
	sdata->vif.type == NL80211_IFTYPE_ADHOC \|\|
	sdata->vif.type == NL80211_IFTYPE_MESH_POINT)
	ieee80211_if_config(sdata,
	IEEE80211_IFCC_BEACON_ENABLED);

	if (sdata->vif.type == NL80211_IFTYPE_STATION) {
	if (sdata->u.sta.flags & IEEE80211_STA_ASSOCIATED) {
	netif_tx_stop_all_queues(sdata->dev);
	ieee80211_send_nullfunc(local, sdata, 1);
	}
	} else
	netif_tx_stop_all_queues(sdata->dev);
	}
	mutex_unlock(&local->iflist_mtx);

	local->scan_state = SCAN_SET_CHANNEL;
	local->scan_channel_idx = 0;
	local->scan_sdata = scan_sdata;
	local->scan_req = req;

	netif_addr_lock_bh(local->mdev);
	local->filter_flags \|= FIF_BCN_PRBRESP_PROMISC;
	local->ops->configure_filter(local_to_hw(local),
	FIF_BCN_PRBRESP_PROMISC,
	&local->filter_flags,
	local->mdev->mc_count,
	local->mdev->mc_list);
	netif_addr_unlock_bh(local->mdev);

	/* TODO: start scan as soon as all nullfunc frames are ACKed */
	queue_delayed_work(local->hw.workqueue, &local->scan_work,
	IEEE80211_CHANNEL_TIME);

	return 0;
	}


	int ieee80211_request_scan(struct ieee80211_sub_if_data *sdata,
	struct cfg80211_scan_request *req)
	{
	struct ieee80211_local *local = sdata->local;
	struct ieee80211_if_sta *ifsta;

	if (!req)
	return -EINVAL;

	if (local->scan_req && local->scan_req != req)
	return -EBUSY;

	local->scan_req = req;

	if (sdata->vif.type != NL80211_IFTYPE_STATION)
	return ieee80211_start_scan(sdata, req);

	/*
	* STA has a state machine that might need to defer scanning
	* while it's trying to associate/authenticate, therefore we
	* queue it up to the state machine in that case.
	*/

	if (local->sw_scanning \|\| local->hw_scanning) {
	if (local->scan_sdata == sdata)
	return 0;
	return -EBUSY;
	}

	ifsta = &sdata->u.sta;
	set_bit(IEEE80211_STA_REQ_SCAN, &ifsta->request);
	queue_work(local->hw.workqueue, &ifsta->work);

	return 0;
	}