net/mac80211/util.c - SHIFTPHONES/mainline/linux - Gitiles

 /*
  * Copyright 2002-2005, Instant802 Networks, Inc.
  * Copyright 2005-2006, Devicescape Software, Inc.
  * Copyright 2006-2007	Jiri Benc <jbenc@suse.cz>
  * Copyright 2007	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.
  *
  * utilities for mac80211
  */

 #include <net/mac80211.h>
 #include <linux/netdevice.h>
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/skbuff.h>
 #include <linux/etherdevice.h>
 #include <linux/if_arp.h>
 #include <linux/wireless.h>
 #include <linux/bitmap.h>
 #include <net/net_namespace.h>
 #include <net/cfg80211.h>
 #include <net/rtnetlink.h>

 #include "ieee80211_i.h"
 #include "ieee80211_rate.h"
 #ifdef CONFIG_MAC80211_MESH
 #include "mesh.h"
 #endif
 #include "wme.h"

 /* privid for wiphys to determine whether they belong to us or not */
 void *mac80211_wiphy_privid = &mac80211_wiphy_privid;

 /* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
 /* Ethernet-II snap header (RFC1042 for most EtherTypes) */
 const unsigned char rfc1042_header[] =
 	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };

 /* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
 const unsigned char bridge_tunnel_header[] =
 	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };


 u8 *ieee80211_get_bssid(struct ieee80211_hdr *hdr, size_t len,
 			enum ieee80211_if_types type)
 {
 	u16 fc;

 	 /* drop ACK/CTS frames and incorrect hdr len (ctrl) */
 	if (len < 16)
 		return NULL;

 	fc = le16_to_cpu(hdr->frame_control);

 	switch (fc & IEEE80211_FCTL_FTYPE) {
 	case IEEE80211_FTYPE_DATA:
 		if (len < 24) /* drop incorrect hdr len (data) */
 			return NULL;
 		switch (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
 		case IEEE80211_FCTL_TODS:
 			return hdr->addr1;
 		case (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS):
 			return NULL;
 		case IEEE80211_FCTL_FROMDS:
 			return hdr->addr2;
 		case 0:
 			return hdr->addr3;
 		}
 		break;
 	case IEEE80211_FTYPE_MGMT:
 		if (len < 24) /* drop incorrect hdr len (mgmt) */
 			return NULL;
 		return hdr->addr3;
 	case IEEE80211_FTYPE_CTL:
 		if ((fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PSPOLL)
 			return hdr->addr1;
 		else if ((fc & IEEE80211_FCTL_STYPE) ==
 						IEEE80211_STYPE_BACK_REQ) {
 			switch (type) {
 			case IEEE80211_IF_TYPE_STA:
 				return hdr->addr2;
 			case IEEE80211_IF_TYPE_AP:
 			case IEEE80211_IF_TYPE_VLAN:
 				return hdr->addr1;
 			default:
 				return NULL;
 			}
 		}
 		else
 			return NULL;
 	}

 	return NULL;
 }

 int ieee80211_get_hdrlen(u16 fc)
 {
 	int hdrlen = 24;

 	switch (fc & IEEE80211_FCTL_FTYPE) {
 	case IEEE80211_FTYPE_DATA:
 		if ((fc & IEEE80211_FCTL_FROMDS) && (fc & IEEE80211_FCTL_TODS))
 			hdrlen = 30; /* Addr4 */
 		/*
 		 * The QoS Control field is two bytes and its presence is
 		 * indicated by the IEEE80211_STYPE_QOS_DATA bit. Add 2 to
 		 * hdrlen if that bit is set.
 		 * This works by masking out the bit and shifting it to
 		 * bit position 1 so the result has the value 0 or 2.
 		 */
 		hdrlen += (fc & IEEE80211_STYPE_QOS_DATA)
 				>> (ilog2(IEEE80211_STYPE_QOS_DATA)-1);
 		break;
 	case IEEE80211_FTYPE_CTL:
 		/*
 		 * ACK and CTS are 10 bytes, all others 16. To see how
 		 * to get this condition consider
 		 *   subtype mask:   0b0000000011110000 (0x00F0)
 		 *   ACK subtype:    0b0000000011010000 (0x00D0)
 		 *   CTS subtype:    0b0000000011000000 (0x00C0)
 		 *   bits that matter:         ^^^      (0x00E0)
 		 *   value of those: 0b0000000011000000 (0x00C0)
 		 */
 		if ((fc & 0xE0) == 0xC0)
 			hdrlen = 10;
 		else
 			hdrlen = 16;
 		break;
 	}

 	return hdrlen;
 }
 EXPORT_SYMBOL(ieee80211_get_hdrlen);

 int ieee80211_get_hdrlen_from_skb(const struct sk_buff *skb)
 {
 	const struct ieee80211_hdr *hdr = (const struct ieee80211_hdr *) skb->data;
 	int hdrlen;

 	if (unlikely(skb->len < 10))
 		return 0;
 	hdrlen = ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_control));
 	if (unlikely(hdrlen > skb->len))
 		return 0;
 	return hdrlen;
 }
 EXPORT_SYMBOL(ieee80211_get_hdrlen_from_skb);

 #ifdef CONFIG_MAC80211_MESH
 int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
 {
 	int ae = meshhdr->flags & IEEE80211S_FLAGS_AE;
 	/* 7.1.3.5a.2 */
 	switch (ae) {
 	case 0:
 		return 5;
 	case 1:
 		return 11;
 	case 2:
 		return 17;
 	case 3:
 		return 23;
 	default:
 		return 5;
 	}
 }
 #endif

 void ieee80211_tx_set_iswep(struct ieee80211_txrx_data *tx)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) tx->skb->data;

 	hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 	if (tx->u.tx.extra_frag) {
 		struct ieee80211_hdr *fhdr;
 		int i;
 		for (i = 0; i < tx->u.tx.num_extra_frag; i++) {
 			fhdr = (struct ieee80211_hdr *)
 				tx->u.tx.extra_frag[i]->data;
 			fhdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 		}
 	}
 }

 int ieee80211_frame_duration(struct ieee80211_local *local, size_t len,
 			     int rate, int erp, int short_preamble)
 {
 	int dur;

 	/* calculate duration (in microseconds, rounded up to next higher
 	 * integer if it includes a fractional microsecond) to send frame of
 	 * len bytes (does not include FCS) at the given rate. Duration will
 	 * also include SIFS.
 	 *
 	 * rate is in 100 kbps, so divident is multiplied by 10 in the
 	 * DIV_ROUND_UP() operations.
 	 */

 	if (local->hw.conf.channel->band == IEEE80211_BAND_5GHZ || erp) {
 		/*
 		 * OFDM:
 		 *
 		 * N_DBPS = DATARATE x 4
 		 * N_SYM = Ceiling((16+8xLENGTH+6) / N_DBPS)
 		 *	(16 = SIGNAL time, 6 = tail bits)
 		 * TXTIME = T_PREAMBLE + T_SIGNAL + T_SYM x N_SYM + Signal Ext
 		 *
 		 * T_SYM = 4 usec
 		 * 802.11a - 17.5.2: aSIFSTime = 16 usec
 		 * 802.11g - 19.8.4: aSIFSTime = 10 usec +
 		 *	signal ext = 6 usec
 		 */
 		dur = 16; /* SIFS + signal ext */
 		dur += 16; /* 17.3.2.3: T_PREAMBLE = 16 usec */
 		dur += 4; /* 17.3.2.3: T_SIGNAL = 4 usec */
 		dur += 4 * DIV_ROUND_UP((16 + 8 * (len + 4) + 6) * 10,
 					4 * rate); /* T_SYM x N_SYM */
 	} else {
 		/*
 		 * 802.11b or 802.11g with 802.11b compatibility:
 		 * 18.3.4: TXTIME = PreambleLength + PLCPHeaderTime +
 		 * Ceiling(((LENGTH+PBCC)x8)/DATARATE). PBCC=0.
 		 *
 		 * 802.11 (DS): 15.3.3, 802.11b: 18.3.4
 		 * aSIFSTime = 10 usec
 		 * aPreambleLength = 144 usec or 72 usec with short preamble
 		 * aPLCPHeaderLength = 48 usec or 24 usec with short preamble
 		 */
 		dur = 10; /* aSIFSTime = 10 usec */
 		dur += short_preamble ? (72 + 24) : (144 + 48);

 		dur += DIV_ROUND_UP(8 * (len + 4) * 10, rate);
 	}

 	return dur;
 }

 /* Exported duration function for driver use */
 __le16 ieee80211_generic_frame_duration(struct ieee80211_hw *hw,
 					struct ieee80211_vif *vif,
 					size_t frame_len,
 					struct ieee80211_rate *rate)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 	u16 dur;
 	int erp;

 	erp = 0;
 	if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
 		erp = rate->flags & IEEE80211_RATE_ERP_G;

 	dur = ieee80211_frame_duration(local, frame_len, rate->bitrate, erp,
 				       sdata->bss_conf.use_short_preamble);

 	return cpu_to_le16(dur);
 }
 EXPORT_SYMBOL(ieee80211_generic_frame_duration);

 __le16 ieee80211_rts_duration(struct ieee80211_hw *hw,
 			      struct ieee80211_vif *vif, size_t frame_len,
 			      const struct ieee80211_tx_control *frame_txctl)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct ieee80211_rate *rate;
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 	bool short_preamble;
 	int erp;
 	u16 dur;

 	short_preamble = sdata->bss_conf.use_short_preamble;

 	rate = frame_txctl->rts_cts_rate;

 	erp = 0;
 	if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
 		erp = rate->flags & IEEE80211_RATE_ERP_G;

 	/* CTS duration */
 	dur = ieee80211_frame_duration(local, 10, rate->bitrate,
 				       erp, short_preamble);
 	/* Data frame duration */
 	dur += ieee80211_frame_duration(local, frame_len, rate->bitrate,
 					erp, short_preamble);
 	/* ACK duration */
 	dur += ieee80211_frame_duration(local, 10, rate->bitrate,
 					erp, short_preamble);

 	return cpu_to_le16(dur);
 }
 EXPORT_SYMBOL(ieee80211_rts_duration);

 __le16 ieee80211_ctstoself_duration(struct ieee80211_hw *hw,
 				    struct ieee80211_vif *vif,
 				    size_t frame_len,
 				    const struct ieee80211_tx_control *frame_txctl)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct ieee80211_rate *rate;
 	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
 	bool short_preamble;
 	int erp;
 	u16 dur;

 	short_preamble = sdata->bss_conf.use_short_preamble;

 	rate = frame_txctl->rts_cts_rate;
 	erp = 0;
 	if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
 		erp = rate->flags & IEEE80211_RATE_ERP_G;

 	/* Data frame duration */
 	dur = ieee80211_frame_duration(local, frame_len, rate->bitrate,
 				       erp, short_preamble);
 	if (!(frame_txctl->flags & IEEE80211_TXCTL_NO_ACK)) {
 		/* ACK duration */
 		dur += ieee80211_frame_duration(local, 10, rate->bitrate,
 						erp, short_preamble);
 	}

 	return cpu_to_le16(dur);
 }
 EXPORT_SYMBOL(ieee80211_ctstoself_duration);

 void ieee80211_wake_queue(struct ieee80211_hw *hw, int queue)
 {
 	struct ieee80211_local *local = hw_to_local(hw);

 	if (test_and_clear_bit(IEEE80211_LINK_STATE_XOFF,
 			       &local->state[queue])) {
 		if (test_bit(IEEE80211_LINK_STATE_PENDING,
 			     &local->state[queue]))
 			tasklet_schedule(&local->tx_pending_tasklet);
 		else
 			if (!ieee80211_qdisc_installed(local->mdev)) {
 				if (queue == 0)
 					netif_wake_queue(local->mdev);
 			} else
 				__netif_schedule(local->mdev);
 	}
 }
 EXPORT_SYMBOL(ieee80211_wake_queue);

 void ieee80211_stop_queue(struct ieee80211_hw *hw, int queue)
 {
 	struct ieee80211_local *local = hw_to_local(hw);

 	if (!ieee80211_qdisc_installed(local->mdev) && queue == 0)
 		netif_stop_queue(local->mdev);
 	set_bit(IEEE80211_LINK_STATE_XOFF, &local->state[queue]);
 }
 EXPORT_SYMBOL(ieee80211_stop_queue);

 void ieee80211_start_queues(struct ieee80211_hw *hw)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	int i;

 	for (i = 0; i < local->hw.queues; i++)
 		clear_bit(IEEE80211_LINK_STATE_XOFF, &local->state[i]);
 	if (!ieee80211_qdisc_installed(local->mdev))
 		netif_start_queue(local->mdev);
 }
 EXPORT_SYMBOL(ieee80211_start_queues);

 void ieee80211_stop_queues(struct ieee80211_hw *hw)
 {
 	int i;

 	for (i = 0; i < hw->queues; i++)
 		ieee80211_stop_queue(hw, i);
 }
 EXPORT_SYMBOL(ieee80211_stop_queues);

 void ieee80211_wake_queues(struct ieee80211_hw *hw)
 {
 	int i;

 	for (i = 0; i < hw->queues; i++)
 		ieee80211_wake_queue(hw, i);
 }
 EXPORT_SYMBOL(ieee80211_wake_queues);

 void ieee80211_iterate_active_interfaces(
 	struct ieee80211_hw *hw,
 	void (*iterator)(void *data, u8 *mac,
 			 struct ieee80211_vif *vif),
 	void *data)
 {
 	struct ieee80211_local *local = hw_to_local(hw);
 	struct ieee80211_sub_if_data *sdata;

 	rcu_read_lock();

 	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
 		switch (sdata->vif.type) {
 		case IEEE80211_IF_TYPE_INVALID:
 		case IEEE80211_IF_TYPE_MNTR:
 		case IEEE80211_IF_TYPE_VLAN:
 			continue;
 		case IEEE80211_IF_TYPE_AP:
 		case IEEE80211_IF_TYPE_STA:
 		case IEEE80211_IF_TYPE_IBSS:
 		case IEEE80211_IF_TYPE_WDS:
 		case IEEE80211_IF_TYPE_MESH_POINT:
 			break;
 		}
 		if (sdata->dev == local->mdev)
 			continue;
 		if (netif_running(sdata->dev))
 			iterator(data, sdata->dev->dev_addr,
 				 &sdata->vif);
 	}

 	rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(ieee80211_iterate_active_interfaces);

 #ifdef CONFIG_MAC80211_MESH
 /**
  * ieee80211_new_mesh_header - create a new mesh header
  * @meshhdr:    uninitialized mesh header
  * @sdata:	mesh interface to be used
  *
  * Return the header length.
  */
 int ieee80211_new_mesh_header(struct ieee80211s_hdr *meshhdr,
 		struct ieee80211_sub_if_data *sdata)
 {
 	meshhdr->flags = 0;
 	meshhdr->ttl = sdata->u.sta.mshcfg.dot11MeshTTL;

 	meshhdr->seqnum[0] = sdata->u.sta.mesh_seqnum[0]++;
 	meshhdr->seqnum[1] = sdata->u.sta.mesh_seqnum[1];
 	meshhdr->seqnum[2] = sdata->u.sta.mesh_seqnum[2];

 	if (sdata->u.sta.mesh_seqnum[0] == 0) {
 		sdata->u.sta.mesh_seqnum[1]++;
 		if (sdata->u.sta.mesh_seqnum[1] == 0)
 			sdata->u.sta.mesh_seqnum[2]++;
 	}

 	return 5;
 }
 #endif
	/*
	* Copyright 2002-2005, Instant802 Networks, Inc.
	* Copyright 2005-2006, Devicescape Software, Inc.
	* Copyright 2006-2007 Jiri Benc <jbenc@suse.cz>
	* Copyright 2007 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.
	*
	* utilities for mac80211
	*/

	#include <net/mac80211.h>
	#include <linux/netdevice.h>
	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/skbuff.h>
	#include <linux/etherdevice.h>
	#include <linux/if_arp.h>
	#include <linux/wireless.h>
	#include <linux/bitmap.h>
	#include <net/net_namespace.h>
	#include <net/cfg80211.h>
	#include <net/rtnetlink.h>

	#include "ieee80211_i.h"
	#include "ieee80211_rate.h"
	#ifdef CONFIG_MAC80211_MESH
	#include "mesh.h"
	#endif
	#include "wme.h"

	/* privid for wiphys to determine whether they belong to us or not */
	void *mac80211_wiphy_privid = &mac80211_wiphy_privid;

	/* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
	/* Ethernet-II snap header (RFC1042 for most EtherTypes) */
	const unsigned char rfc1042_header[] =
	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };

	/* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
	const unsigned char bridge_tunnel_header[] =
	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };


	u8 ieee80211_get_bssid(struct ieee80211_hdr hdr, size_t len,
	enum ieee80211_if_types type)
	{
	u16 fc;

	/* drop ACK/CTS frames and incorrect hdr len (ctrl) */
	if (len < 16)
	return NULL;

	fc = le16_to_cpu(hdr->frame_control);

	switch (fc & IEEE80211_FCTL_FTYPE) {
	case IEEE80211_FTYPE_DATA:
	if (len < 24) /* drop incorrect hdr len (data) */
	return NULL;
	switch (fc & (IEEE80211_FCTL_TODS \| IEEE80211_FCTL_FROMDS)) {
	case IEEE80211_FCTL_TODS:
	return hdr->addr1;
	case (IEEE80211_FCTL_TODS \| IEEE80211_FCTL_FROMDS):
	return NULL;
	case IEEE80211_FCTL_FROMDS:
	return hdr->addr2;
	case 0:
	return hdr->addr3;
	}
	break;
	case IEEE80211_FTYPE_MGMT:
	if (len < 24) /* drop incorrect hdr len (mgmt) */
	return NULL;
	return hdr->addr3;
	case IEEE80211_FTYPE_CTL:
	if ((fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PSPOLL)
	return hdr->addr1;
	else if ((fc & IEEE80211_FCTL_STYPE) ==
	IEEE80211_STYPE_BACK_REQ) {
	switch (type) {
	case IEEE80211_IF_TYPE_STA:
	return hdr->addr2;
	case IEEE80211_IF_TYPE_AP:
	case IEEE80211_IF_TYPE_VLAN:
	return hdr->addr1;
	default:
	return NULL;
	}
	}
	else
	return NULL;
	}

	return NULL;
	}

	int ieee80211_get_hdrlen(u16 fc)
	{
	int hdrlen = 24;

	switch (fc & IEEE80211_FCTL_FTYPE) {
	case IEEE80211_FTYPE_DATA:
	if ((fc & IEEE80211_FCTL_FROMDS) && (fc & IEEE80211_FCTL_TODS))
	hdrlen = 30; /* Addr4 */
	/*
	* The QoS Control field is two bytes and its presence is
	* indicated by the IEEE80211_STYPE_QOS_DATA bit. Add 2 to
	* hdrlen if that bit is set.
	* This works by masking out the bit and shifting it to
	* bit position 1 so the result has the value 0 or 2.
	*/
	hdrlen += (fc & IEEE80211_STYPE_QOS_DATA)
	>> (ilog2(IEEE80211_STYPE_QOS_DATA)-1);
	break;
	case IEEE80211_FTYPE_CTL:
	/*
	* ACK and CTS are 10 bytes, all others 16. To see how
	* to get this condition consider
	* subtype mask: 0b0000000011110000 (0x00F0)
	* ACK subtype: 0b0000000011010000 (0x00D0)
	* CTS subtype: 0b0000000011000000 (0x00C0)
	* bits that matter: ^^^ (0x00E0)
	* value of those: 0b0000000011000000 (0x00C0)
	*/
	if ((fc & 0xE0) == 0xC0)
	hdrlen = 10;
	else
	hdrlen = 16;
	break;
	}

	return hdrlen;
	}
	EXPORT_SYMBOL(ieee80211_get_hdrlen);

	int ieee80211_get_hdrlen_from_skb(const struct sk_buff *skb)
	{
	const struct ieee80211_hdr hdr = (const struct ieee80211_hdr ) skb->data;
	int hdrlen;

	if (unlikely(skb->len < 10))
	return 0;
	hdrlen = ieee80211_get_hdrlen(le16_to_cpu(hdr->frame_control));
	if (unlikely(hdrlen > skb->len))
	return 0;
	return hdrlen;
	}
	EXPORT_SYMBOL(ieee80211_get_hdrlen_from_skb);

	#ifdef CONFIG_MAC80211_MESH
	int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
	{
	int ae = meshhdr->flags & IEEE80211S_FLAGS_AE;
	/* 7.1.3.5a.2 */
	switch (ae) {
	case 0:
	return 5;
	case 1:
	return 11;
	case 2:
	return 17;
	case 3:
	return 23;
	default:
	return 5;
	}
	}
	#endif

	void ieee80211_tx_set_iswep(struct ieee80211_txrx_data *tx)
	{
	struct ieee80211_hdr hdr = (struct ieee80211_hdr ) tx->skb->data;

	hdr->frame_control \|= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
	if (tx->u.tx.extra_frag) {
	struct ieee80211_hdr *fhdr;
	int i;
	for (i = 0; i < tx->u.tx.num_extra_frag; i++) {
	fhdr = (struct ieee80211_hdr *)
	tx->u.tx.extra_frag[i]->data;
	fhdr->frame_control \|= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
	}
	}
	}

	int ieee80211_frame_duration(struct ieee80211_local *local, size_t len,
	int rate, int erp, int short_preamble)
	{
	int dur;

	/* calculate duration (in microseconds, rounded up to next higher
	* integer if it includes a fractional microsecond) to send frame of
	* len bytes (does not include FCS) at the given rate. Duration will
	* also include SIFS.
	*
	* rate is in 100 kbps, so divident is multiplied by 10 in the
	* DIV_ROUND_UP() operations.
	*/

	if (local->hw.conf.channel->band == IEEE80211_BAND_5GHZ \|\| erp) {
	/*
	* OFDM:
	*
	* N_DBPS = DATARATE x 4
	* N_SYM = Ceiling((16+8xLENGTH+6) / N_DBPS)
	* (16 = SIGNAL time, 6 = tail bits)
	* TXTIME = T_PREAMBLE + T_SIGNAL + T_SYM x N_SYM + Signal Ext
	*
	* T_SYM = 4 usec
	* 802.11a - 17.5.2: aSIFSTime = 16 usec
	* 802.11g - 19.8.4: aSIFSTime = 10 usec +
	* signal ext = 6 usec
	*/
	dur = 16; /* SIFS + signal ext */
	dur += 16; /* 17.3.2.3: T_PREAMBLE = 16 usec */
	dur += 4; /* 17.3.2.3: T_SIGNAL = 4 usec */
	dur += 4 * DIV_ROUND_UP((16 + 8 * (len + 4) + 6) * 10,
	4 * rate); /* T_SYM x N_SYM */
	} else {
	/*
	* 802.11b or 802.11g with 802.11b compatibility:
	* 18.3.4: TXTIME = PreambleLength + PLCPHeaderTime +
	* Ceiling(((LENGTH+PBCC)x8)/DATARATE). PBCC=0.
	*
	* 802.11 (DS): 15.3.3, 802.11b: 18.3.4
	* aSIFSTime = 10 usec
	* aPreambleLength = 144 usec or 72 usec with short preamble
	* aPLCPHeaderLength = 48 usec or 24 usec with short preamble
	*/
	dur = 10; /* aSIFSTime = 10 usec */
	dur += short_preamble ? (72 + 24) : (144 + 48);

	dur += DIV_ROUND_UP(8 * (len + 4) * 10, rate);
	}

	return dur;
	}

	/* Exported duration function for driver use */
	__le16 ieee80211_generic_frame_duration(struct ieee80211_hw *hw,
	struct ieee80211_vif *vif,
	size_t frame_len,
	struct ieee80211_rate *rate)
	{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	u16 dur;
	int erp;

	erp = 0;
	if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
	erp = rate->flags & IEEE80211_RATE_ERP_G;

	dur = ieee80211_frame_duration(local, frame_len, rate->bitrate, erp,
	sdata->bss_conf.use_short_preamble);

	return cpu_to_le16(dur);
	}
	EXPORT_SYMBOL(ieee80211_generic_frame_duration);

	__le16 ieee80211_rts_duration(struct ieee80211_hw *hw,
	struct ieee80211_vif *vif, size_t frame_len,
	const struct ieee80211_tx_control *frame_txctl)
	{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_rate *rate;
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	bool short_preamble;
	int erp;
	u16 dur;

	short_preamble = sdata->bss_conf.use_short_preamble;

	rate = frame_txctl->rts_cts_rate;

	erp = 0;
	if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
	erp = rate->flags & IEEE80211_RATE_ERP_G;

	/* CTS duration */
	dur = ieee80211_frame_duration(local, 10, rate->bitrate,
	erp, short_preamble);
	/* Data frame duration */
	dur += ieee80211_frame_duration(local, frame_len, rate->bitrate,
	erp, short_preamble);
	/* ACK duration */
	dur += ieee80211_frame_duration(local, 10, rate->bitrate,
	erp, short_preamble);

	return cpu_to_le16(dur);
	}
	EXPORT_SYMBOL(ieee80211_rts_duration);

	__le16 ieee80211_ctstoself_duration(struct ieee80211_hw *hw,
	struct ieee80211_vif *vif,
	size_t frame_len,
	const struct ieee80211_tx_control *frame_txctl)
	{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_rate *rate;
	struct ieee80211_sub_if_data *sdata = vif_to_sdata(vif);
	bool short_preamble;
	int erp;
	u16 dur;

	short_preamble = sdata->bss_conf.use_short_preamble;

	rate = frame_txctl->rts_cts_rate;
	erp = 0;
	if (sdata->flags & IEEE80211_SDATA_OPERATING_GMODE)
	erp = rate->flags & IEEE80211_RATE_ERP_G;

	/* Data frame duration */
	dur = ieee80211_frame_duration(local, frame_len, rate->bitrate,
	erp, short_preamble);
	if (!(frame_txctl->flags & IEEE80211_TXCTL_NO_ACK)) {
	/* ACK duration */
	dur += ieee80211_frame_duration(local, 10, rate->bitrate,
	erp, short_preamble);
	}

	return cpu_to_le16(dur);
	}
	EXPORT_SYMBOL(ieee80211_ctstoself_duration);

	void ieee80211_wake_queue(struct ieee80211_hw *hw, int queue)
	{
	struct ieee80211_local *local = hw_to_local(hw);

	if (test_and_clear_bit(IEEE80211_LINK_STATE_XOFF,
	&local->state[queue])) {
	if (test_bit(IEEE80211_LINK_STATE_PENDING,
	&local->state[queue]))
	tasklet_schedule(&local->tx_pending_tasklet);
	else
	if (!ieee80211_qdisc_installed(local->mdev)) {
	if (queue == 0)
	netif_wake_queue(local->mdev);
	} else
	__netif_schedule(local->mdev);
	}
	}
	EXPORT_SYMBOL(ieee80211_wake_queue);

	void ieee80211_stop_queue(struct ieee80211_hw *hw, int queue)
	{
	struct ieee80211_local *local = hw_to_local(hw);

	if (!ieee80211_qdisc_installed(local->mdev) && queue == 0)
	netif_stop_queue(local->mdev);
	set_bit(IEEE80211_LINK_STATE_XOFF, &local->state[queue]);
	}
	EXPORT_SYMBOL(ieee80211_stop_queue);

	void ieee80211_start_queues(struct ieee80211_hw *hw)
	{
	struct ieee80211_local *local = hw_to_local(hw);
	int i;

	for (i = 0; i < local->hw.queues; i++)
	clear_bit(IEEE80211_LINK_STATE_XOFF, &local->state[i]);
	if (!ieee80211_qdisc_installed(local->mdev))
	netif_start_queue(local->mdev);
	}
	EXPORT_SYMBOL(ieee80211_start_queues);

	void ieee80211_stop_queues(struct ieee80211_hw *hw)
	{
	int i;

	for (i = 0; i < hw->queues; i++)
	ieee80211_stop_queue(hw, i);
	}
	EXPORT_SYMBOL(ieee80211_stop_queues);

	void ieee80211_wake_queues(struct ieee80211_hw *hw)
	{
	int i;

	for (i = 0; i < hw->queues; i++)
	ieee80211_wake_queue(hw, i);
	}
	EXPORT_SYMBOL(ieee80211_wake_queues);

	void ieee80211_iterate_active_interfaces(
	struct ieee80211_hw *hw,
	void (iterator)(void data, u8 *mac,
	struct ieee80211_vif *vif),
	void *data)
	{
	struct ieee80211_local *local = hw_to_local(hw);
	struct ieee80211_sub_if_data *sdata;

	rcu_read_lock();

	list_for_each_entry_rcu(sdata, &local->interfaces, list) {
	switch (sdata->vif.type) {
	case IEEE80211_IF_TYPE_INVALID:
	case IEEE80211_IF_TYPE_MNTR:
	case IEEE80211_IF_TYPE_VLAN:
	continue;
	case IEEE80211_IF_TYPE_AP:
	case IEEE80211_IF_TYPE_STA:
	case IEEE80211_IF_TYPE_IBSS:
	case IEEE80211_IF_TYPE_WDS:
	case IEEE80211_IF_TYPE_MESH_POINT:
	break;
	}
	if (sdata->dev == local->mdev)
	continue;
	if (netif_running(sdata->dev))
	iterator(data, sdata->dev->dev_addr,
	&sdata->vif);
	}

	rcu_read_unlock();
	}
	EXPORT_SYMBOL_GPL(ieee80211_iterate_active_interfaces);

	#ifdef CONFIG_MAC80211_MESH
	/**
	* ieee80211_new_mesh_header - create a new mesh header
	* @meshhdr: uninitialized mesh header
	* @sdata: mesh interface to be used
	*
	* Return the header length.
	*/
	int ieee80211_new_mesh_header(struct ieee80211s_hdr *meshhdr,
	struct ieee80211_sub_if_data *sdata)
	{
	meshhdr->flags = 0;
	meshhdr->ttl = sdata->u.sta.mshcfg.dot11MeshTTL;

	meshhdr->seqnum[0] = sdata->u.sta.mesh_seqnum[0]++;
	meshhdr->seqnum[1] = sdata->u.sta.mesh_seqnum[1];
	meshhdr->seqnum[2] = sdata->u.sta.mesh_seqnum[2];

	if (sdata->u.sta.mesh_seqnum[0] == 0) {
	sdata->u.sta.mesh_seqnum[1]++;
	if (sdata->u.sta.mesh_seqnum[1] == 0)
	sdata->u.sta.mesh_seqnum[2]++;
	}

	return 5;
	}
	#endif