net/wireless/util.c - maze/linux - Git at Google

 /*
  * Wireless utility functions
  *
  * Copyright 2007-2009	Johannes Berg <johannes@sipsolutions.net>
  */
 #include <linux/bitops.h>
 #include <linux/etherdevice.h>
 #include <net/cfg80211.h>
 #include <net/ip.h>
 #include "core.h"

 struct ieee80211_rate *
 ieee80211_get_response_rate(struct ieee80211_supported_band *sband,
 			    u32 basic_rates, int bitrate)
 {
 	struct ieee80211_rate *result = &sband->bitrates[0];
 	int i;

 	for (i = 0; i < sband->n_bitrates; i++) {
 		if (!(basic_rates & BIT(i)))
 			continue;
 		if (sband->bitrates[i].bitrate > bitrate)
 			continue;
 		result = &sband->bitrates[i];
 	}

 	return result;
 }
 EXPORT_SYMBOL(ieee80211_get_response_rate);

 int ieee80211_channel_to_frequency(int chan)
 {
 	if (chan < 14)
 		return 2407 + chan * 5;

 	if (chan == 14)
 		return 2484;

 	/* FIXME: 802.11j 17.3.8.3.2 */
 	return (chan + 1000) * 5;
 }
 EXPORT_SYMBOL(ieee80211_channel_to_frequency);

 int ieee80211_frequency_to_channel(int freq)
 {
 	if (freq == 2484)
 		return 14;

 	if (freq < 2484)
 		return (freq - 2407) / 5;

 	/* FIXME: 802.11j 17.3.8.3.2 */
 	return freq/5 - 1000;
 }
 EXPORT_SYMBOL(ieee80211_frequency_to_channel);

 struct ieee80211_channel *__ieee80211_get_channel(struct wiphy *wiphy,
 						  int freq)
 {
 	enum ieee80211_band band;
 	struct ieee80211_supported_band *sband;
 	int i;

 	for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
 		sband = wiphy->bands[band];

 		if (!sband)
 			continue;

 		for (i = 0; i < sband->n_channels; i++) {
 			if (sband->channels[i].center_freq == freq)
 				return &sband->channels[i];
 		}
 	}

 	return NULL;
 }
 EXPORT_SYMBOL(__ieee80211_get_channel);

 static void set_mandatory_flags_band(struct ieee80211_supported_band *sband,
 				     enum ieee80211_band band)
 {
 	int i, want;

 	switch (band) {
 	case IEEE80211_BAND_5GHZ:
 		want = 3;
 		for (i = 0; i < sband->n_bitrates; i++) {
 			if (sband->bitrates[i].bitrate == 60 ||
 			    sband->bitrates[i].bitrate == 120 ||
 			    sband->bitrates[i].bitrate == 240) {
 				sband->bitrates[i].flags |=
 					IEEE80211_RATE_MANDATORY_A;
 				want--;
 			}
 		}
 		WARN_ON(want);
 		break;
 	case IEEE80211_BAND_2GHZ:
 		want = 7;
 		for (i = 0; i < sband->n_bitrates; i++) {
 			if (sband->bitrates[i].bitrate == 10) {
 				sband->bitrates[i].flags |=
 					IEEE80211_RATE_MANDATORY_B |
 					IEEE80211_RATE_MANDATORY_G;
 				want--;
 			}

 			if (sband->bitrates[i].bitrate == 20 ||
 			    sband->bitrates[i].bitrate == 55 ||
 			    sband->bitrates[i].bitrate == 110 ||
 			    sband->bitrates[i].bitrate == 60 ||
 			    sband->bitrates[i].bitrate == 120 ||
 			    sband->bitrates[i].bitrate == 240) {
 				sband->bitrates[i].flags |=
 					IEEE80211_RATE_MANDATORY_G;
 				want--;
 			}

 			if (sband->bitrates[i].bitrate != 10 &&
 			    sband->bitrates[i].bitrate != 20 &&
 			    sband->bitrates[i].bitrate != 55 &&
 			    sband->bitrates[i].bitrate != 110)
 				sband->bitrates[i].flags |=
 					IEEE80211_RATE_ERP_G;
 		}
 		WARN_ON(want != 0 && want != 3 && want != 6);
 		break;
 	case IEEE80211_NUM_BANDS:
 		WARN_ON(1);
 		break;
 	}
 }

 void ieee80211_set_bitrate_flags(struct wiphy *wiphy)
 {
 	enum ieee80211_band band;

 	for (band = 0; band < IEEE80211_NUM_BANDS; band++)
 		if (wiphy->bands[band])
 			set_mandatory_flags_band(wiphy->bands[band], band);
 }

 int cfg80211_validate_key_settings(struct key_params *params, int key_idx,
 				   const u8 *mac_addr)
 {
 	if (key_idx > 5)
 		return -EINVAL;

 	/*
 	 * Disallow pairwise keys with non-zero index unless it's WEP
 	 * (because current deployments use pairwise WEP keys with
 	 * non-zero indizes but 802.11i clearly specifies to use zero)
 	 */
 	if (mac_addr && key_idx &&
 	    params->cipher != WLAN_CIPHER_SUITE_WEP40 &&
 	    params->cipher != WLAN_CIPHER_SUITE_WEP104)
 		return -EINVAL;

 	/* TODO: add definitions for the lengths to linux/ieee80211.h */
 	switch (params->cipher) {
 	case WLAN_CIPHER_SUITE_WEP40:
 		if (params->key_len != 5)
 			return -EINVAL;
 		break;
 	case WLAN_CIPHER_SUITE_TKIP:
 		if (params->key_len != 32)
 			return -EINVAL;
 		break;
 	case WLAN_CIPHER_SUITE_CCMP:
 		if (params->key_len != 16)
 			return -EINVAL;
 		break;
 	case WLAN_CIPHER_SUITE_WEP104:
 		if (params->key_len != 13)
 			return -EINVAL;
 		break;
 	case WLAN_CIPHER_SUITE_AES_CMAC:
 		if (params->key_len != 16)
 			return -EINVAL;
 		break;
 	default:
 		return -EINVAL;
 	}

 	if (params->seq) {
 		switch (params->cipher) {
 		case WLAN_CIPHER_SUITE_WEP40:
 		case WLAN_CIPHER_SUITE_WEP104:
 			/* These ciphers do not use key sequence */
 			return -EINVAL;
 		case WLAN_CIPHER_SUITE_TKIP:
 		case WLAN_CIPHER_SUITE_CCMP:
 		case WLAN_CIPHER_SUITE_AES_CMAC:
 			if (params->seq_len != 6)
 				return -EINVAL;
 			break;
 		}
 	}

 	return 0;
 }

 /* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
 /* Ethernet-II snap header (RFC1042 for most EtherTypes) */
 const unsigned char rfc1042_header[] __aligned(2) =
 	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };
 EXPORT_SYMBOL(rfc1042_header);

 /* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
 const unsigned char bridge_tunnel_header[] __aligned(2) =
 	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
 EXPORT_SYMBOL(bridge_tunnel_header);

 unsigned int ieee80211_hdrlen(__le16 fc)
 {
 	unsigned int hdrlen = 24;

 	if (ieee80211_is_data(fc)) {
 		if (ieee80211_has_a4(fc))
 			hdrlen = 30;
 		if (ieee80211_is_data_qos(fc))
 			hdrlen += IEEE80211_QOS_CTL_LEN;
 		goto out;
 	}

 	if (ieee80211_is_ctl(fc)) {
 		/*
 		 * 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 & cpu_to_le16(0x00E0)) == cpu_to_le16(0x00C0))
 			hdrlen = 10;
 		else
 			hdrlen = 16;
 	}
 out:
 	return hdrlen;
 }
 EXPORT_SYMBOL(ieee80211_hdrlen);

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

 	if (unlikely(skb->len < 10))
 		return 0;
 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
 	if (unlikely(hdrlen > skb->len))
 		return 0;
 	return hdrlen;
 }
 EXPORT_SYMBOL(ieee80211_get_hdrlen_from_skb);

 int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
 {
 	int ae = meshhdr->flags & MESH_FLAGS_AE;
 	/* 7.1.3.5a.2 */
 	switch (ae) {
 	case 0:
 		return 6;
 	case 1:
 		return 12;
 	case 2:
 		return 18;
 	case 3:
 		return 24;
 	default:
 		return 6;
 	}
 }

 int ieee80211_data_to_8023(struct sk_buff *skb, u8 *addr,
 			   enum nl80211_iftype iftype)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 	u16 hdrlen, ethertype;
 	u8 *payload;
 	u8 dst[ETH_ALEN];
 	u8 src[ETH_ALEN] __aligned(2);

 	if (unlikely(!ieee80211_is_data_present(hdr->frame_control)))
 		return -1;

 	hdrlen = ieee80211_hdrlen(hdr->frame_control);

 	/* convert IEEE 802.11 header + possible LLC headers into Ethernet
 	 * header
 	 * IEEE 802.11 address fields:
 	 * ToDS FromDS Addr1 Addr2 Addr3 Addr4
 	 *   0     0   DA    SA    BSSID n/a
 	 *   0     1   DA    BSSID SA    n/a
 	 *   1     0   BSSID SA    DA    n/a
 	 *   1     1   RA    TA    DA    SA
 	 */
 	memcpy(dst, ieee80211_get_DA(hdr), ETH_ALEN);
 	memcpy(src, ieee80211_get_SA(hdr), ETH_ALEN);

 	switch (hdr->frame_control &
 		cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) {
 	case cpu_to_le16(IEEE80211_FCTL_TODS):
 		if (unlikely(iftype != NL80211_IFTYPE_AP &&
 			     iftype != NL80211_IFTYPE_AP_VLAN))
 			return -1;
 		break;
 	case cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS):
 		if (unlikely(iftype != NL80211_IFTYPE_WDS &&
 			     iftype != NL80211_IFTYPE_MESH_POINT))
 			return -1;
 		if (iftype == NL80211_IFTYPE_MESH_POINT) {
 			struct ieee80211s_hdr *meshdr =
 				(struct ieee80211s_hdr *) (skb->data + hdrlen);
 			hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
 			if (meshdr->flags & MESH_FLAGS_AE_A5_A6) {
 				memcpy(dst, meshdr->eaddr1, ETH_ALEN);
 				memcpy(src, meshdr->eaddr2, ETH_ALEN);
 			}
 		}
 		break;
 	case cpu_to_le16(IEEE80211_FCTL_FROMDS):
 		if (iftype != NL80211_IFTYPE_STATION ||
 		    (is_multicast_ether_addr(dst) &&
 		     !compare_ether_addr(src, addr)))
 			return -1;
 		break;
 	case cpu_to_le16(0):
 		if (iftype != NL80211_IFTYPE_ADHOC)
 			return -1;
 		break;
 	}

 	if (unlikely(skb->len - hdrlen < 8))
 		return -1;

 	payload = skb->data + hdrlen;
 	ethertype = (payload[6] << 8) | payload[7];

 	if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
 		    ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) ||
 		   compare_ether_addr(payload, bridge_tunnel_header) == 0)) {
 		/* remove RFC1042 or Bridge-Tunnel encapsulation and
 		 * replace EtherType */
 		skb_pull(skb, hdrlen + 6);
 		memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
 		memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
 	} else {
 		struct ethhdr *ehdr;
 		__be16 len;

 		skb_pull(skb, hdrlen);
 		len = htons(skb->len);
 		ehdr = (struct ethhdr *) skb_push(skb, sizeof(struct ethhdr));
 		memcpy(ehdr->h_dest, dst, ETH_ALEN);
 		memcpy(ehdr->h_source, src, ETH_ALEN);
 		ehdr->h_proto = len;
 	}
 	return 0;
 }
 EXPORT_SYMBOL(ieee80211_data_to_8023);

 int ieee80211_data_from_8023(struct sk_buff *skb, u8 *addr,
 			     enum nl80211_iftype iftype, u8 *bssid, bool qos)
 {
 	struct ieee80211_hdr hdr;
 	u16 hdrlen, ethertype;
 	__le16 fc;
 	const u8 *encaps_data;
 	int encaps_len, skip_header_bytes;
 	int nh_pos, h_pos;
 	int head_need;

 	if (unlikely(skb->len < ETH_HLEN))
 		return -EINVAL;

 	nh_pos = skb_network_header(skb) - skb->data;
 	h_pos = skb_transport_header(skb) - skb->data;

 	/* convert Ethernet header to proper 802.11 header (based on
 	 * operation mode) */
 	ethertype = (skb->data[12] << 8) | skb->data[13];
 	fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA);

 	switch (iftype) {
 	case NL80211_IFTYPE_AP:
 	case NL80211_IFTYPE_AP_VLAN:
 		fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
 		/* DA BSSID SA */
 		memcpy(hdr.addr1, skb->data, ETH_ALEN);
 		memcpy(hdr.addr2, addr, ETH_ALEN);
 		memcpy(hdr.addr3, skb->data + ETH_ALEN, ETH_ALEN);
 		hdrlen = 24;
 		break;
 	case NL80211_IFTYPE_STATION:
 		fc |= cpu_to_le16(IEEE80211_FCTL_TODS);
 		/* BSSID SA DA */
 		memcpy(hdr.addr1, bssid, ETH_ALEN);
 		memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
 		memcpy(hdr.addr3, skb->data, ETH_ALEN);
 		hdrlen = 24;
 		break;
 	case NL80211_IFTYPE_ADHOC:
 		/* DA SA BSSID */
 		memcpy(hdr.addr1, skb->data, ETH_ALEN);
 		memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
 		memcpy(hdr.addr3, bssid, ETH_ALEN);
 		hdrlen = 24;
 		break;
 	default:
 		return -EOPNOTSUPP;
 	}

 	if (qos) {
 		fc |= cpu_to_le16(IEEE80211_STYPE_QOS_DATA);
 		hdrlen += 2;
 	}

 	hdr.frame_control = fc;
 	hdr.duration_id = 0;
 	hdr.seq_ctrl = 0;

 	skip_header_bytes = ETH_HLEN;
 	if (ethertype == ETH_P_AARP || ethertype == ETH_P_IPX) {
 		encaps_data = bridge_tunnel_header;
 		encaps_len = sizeof(bridge_tunnel_header);
 		skip_header_bytes -= 2;
 	} else if (ethertype > 0x600) {
 		encaps_data = rfc1042_header;
 		encaps_len = sizeof(rfc1042_header);
 		skip_header_bytes -= 2;
 	} else {
 		encaps_data = NULL;
 		encaps_len = 0;
 	}

 	skb_pull(skb, skip_header_bytes);
 	nh_pos -= skip_header_bytes;
 	h_pos -= skip_header_bytes;

 	head_need = hdrlen + encaps_len - skb_headroom(skb);

 	if (head_need > 0 || skb_cloned(skb)) {
 		head_need = max(head_need, 0);
 		if (head_need)
 			skb_orphan(skb);

 		if (pskb_expand_head(skb, head_need, 0, GFP_ATOMIC)) {
 			printk(KERN_ERR "failed to reallocate Tx buffer\n");
 			return -ENOMEM;
 		}
 		skb->truesize += head_need;
 	}

 	if (encaps_data) {
 		memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len);
 		nh_pos += encaps_len;
 		h_pos += encaps_len;
 	}

 	memcpy(skb_push(skb, hdrlen), &hdr, hdrlen);

 	nh_pos += hdrlen;
 	h_pos += hdrlen;

 	/* Update skb pointers to various headers since this modified frame
 	 * is going to go through Linux networking code that may potentially
 	 * need things like pointer to IP header. */
 	skb_set_mac_header(skb, 0);
 	skb_set_network_header(skb, nh_pos);
 	skb_set_transport_header(skb, h_pos);

 	return 0;
 }
 EXPORT_SYMBOL(ieee80211_data_from_8023);

 /* Given a data frame determine the 802.1p/1d tag to use. */
 unsigned int cfg80211_classify8021d(struct sk_buff *skb)
 {
 	unsigned int dscp;

 	/* skb->priority values from 256->263 are magic values to
 	 * directly indicate a specific 802.1d priority.  This is used
 	 * to allow 802.1d priority to be passed directly in from VLAN
 	 * tags, etc.
 	 */
 	if (skb->priority >= 256 && skb->priority <= 263)
 		return skb->priority - 256;

 	switch (skb->protocol) {
 	case htons(ETH_P_IP):
 		dscp = ip_hdr(skb)->tos & 0xfc;
 		break;
 	default:
 		return 0;
 	}

 	return dscp >> 5;
 }
 EXPORT_SYMBOL(cfg80211_classify8021d);
	/*
	* Wireless utility functions
	*
	* Copyright 2007-2009 Johannes Berg <johannes@sipsolutions.net>
	*/
	#include <linux/bitops.h>
	#include <linux/etherdevice.h>
	#include <net/cfg80211.h>
	#include <net/ip.h>
	#include "core.h"

	struct ieee80211_rate *
	ieee80211_get_response_rate(struct ieee80211_supported_band *sband,
	u32 basic_rates, int bitrate)
	{
	struct ieee80211_rate *result = &sband->bitrates[0];
	int i;

	for (i = 0; i < sband->n_bitrates; i++) {
	if (!(basic_rates & BIT(i)))
	continue;
	if (sband->bitrates[i].bitrate > bitrate)
	continue;
	result = &sband->bitrates[i];
	}

	return result;
	}
	EXPORT_SYMBOL(ieee80211_get_response_rate);

	int ieee80211_channel_to_frequency(int chan)
	{
	if (chan < 14)
	return 2407 + chan * 5;

	if (chan == 14)
	return 2484;

	/* FIXME: 802.11j 17.3.8.3.2 */
	return (chan + 1000) * 5;
	}
	EXPORT_SYMBOL(ieee80211_channel_to_frequency);

	int ieee80211_frequency_to_channel(int freq)
	{
	if (freq == 2484)
	return 14;

	if (freq < 2484)
	return (freq - 2407) / 5;

	/* FIXME: 802.11j 17.3.8.3.2 */
	return freq/5 - 1000;
	}
	EXPORT_SYMBOL(ieee80211_frequency_to_channel);

	struct ieee80211_channel __ieee80211_get_channel(struct wiphy wiphy,
	int freq)
	{
	enum ieee80211_band band;
	struct ieee80211_supported_band *sband;
	int i;

	for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
	sband = wiphy->bands[band];

	if (!sband)
	continue;

	for (i = 0; i < sband->n_channels; i++) {
	if (sband->channels[i].center_freq == freq)
	return &sband->channels[i];
	}
	}

	return NULL;
	}
	EXPORT_SYMBOL(__ieee80211_get_channel);

	static void set_mandatory_flags_band(struct ieee80211_supported_band *sband,
	enum ieee80211_band band)
	{
	int i, want;

	switch (band) {
	case IEEE80211_BAND_5GHZ:
	want = 3;
	for (i = 0; i < sband->n_bitrates; i++) {
	if (sband->bitrates[i].bitrate == 60 \|\|
	sband->bitrates[i].bitrate == 120 \|\|
	sband->bitrates[i].bitrate == 240) {
	sband->bitrates[i].flags \|=
	IEEE80211_RATE_MANDATORY_A;
	want--;
	}
	}
	WARN_ON(want);
	break;
	case IEEE80211_BAND_2GHZ:
	want = 7;
	for (i = 0; i < sband->n_bitrates; i++) {
	if (sband->bitrates[i].bitrate == 10) {
	sband->bitrates[i].flags \|=
	IEEE80211_RATE_MANDATORY_B \|
	IEEE80211_RATE_MANDATORY_G;
	want--;
	}

	if (sband->bitrates[i].bitrate == 20 \|\|
	sband->bitrates[i].bitrate == 55 \|\|
	sband->bitrates[i].bitrate == 110 \|\|
	sband->bitrates[i].bitrate == 60 \|\|
	sband->bitrates[i].bitrate == 120 \|\|
	sband->bitrates[i].bitrate == 240) {
	sband->bitrates[i].flags \|=
	IEEE80211_RATE_MANDATORY_G;
	want--;
	}

	if (sband->bitrates[i].bitrate != 10 &&
	sband->bitrates[i].bitrate != 20 &&
	sband->bitrates[i].bitrate != 55 &&
	sband->bitrates[i].bitrate != 110)
	sband->bitrates[i].flags \|=
	IEEE80211_RATE_ERP_G;
	}
	WARN_ON(want != 0 && want != 3 && want != 6);
	break;
	case IEEE80211_NUM_BANDS:
	WARN_ON(1);
	break;
	}
	}

	void ieee80211_set_bitrate_flags(struct wiphy *wiphy)
	{
	enum ieee80211_band band;

	for (band = 0; band < IEEE80211_NUM_BANDS; band++)
	if (wiphy->bands[band])
	set_mandatory_flags_band(wiphy->bands[band], band);
	}

	int cfg80211_validate_key_settings(struct key_params *params, int key_idx,
	const u8 *mac_addr)
	{
	if (key_idx > 5)
	return -EINVAL;

	/*
	* Disallow pairwise keys with non-zero index unless it's WEP
	* (because current deployments use pairwise WEP keys with
	* non-zero indizes but 802.11i clearly specifies to use zero)
	*/
	if (mac_addr && key_idx &&
	params->cipher != WLAN_CIPHER_SUITE_WEP40 &&
	params->cipher != WLAN_CIPHER_SUITE_WEP104)
	return -EINVAL;

	/* TODO: add definitions for the lengths to linux/ieee80211.h */
	switch (params->cipher) {
	case WLAN_CIPHER_SUITE_WEP40:
	if (params->key_len != 5)
	return -EINVAL;
	break;
	case WLAN_CIPHER_SUITE_TKIP:
	if (params->key_len != 32)
	return -EINVAL;
	break;
	case WLAN_CIPHER_SUITE_CCMP:
	if (params->key_len != 16)
	return -EINVAL;
	break;
	case WLAN_CIPHER_SUITE_WEP104:
	if (params->key_len != 13)
	return -EINVAL;
	break;
	case WLAN_CIPHER_SUITE_AES_CMAC:
	if (params->key_len != 16)
	return -EINVAL;
	break;
	default:
	return -EINVAL;
	}

	if (params->seq) {
	switch (params->cipher) {
	case WLAN_CIPHER_SUITE_WEP40:
	case WLAN_CIPHER_SUITE_WEP104:
	/* These ciphers do not use key sequence */
	return -EINVAL;
	case WLAN_CIPHER_SUITE_TKIP:
	case WLAN_CIPHER_SUITE_CCMP:
	case WLAN_CIPHER_SUITE_AES_CMAC:
	if (params->seq_len != 6)
	return -EINVAL;
	break;
	}
	}

	return 0;
	}

	/* See IEEE 802.1H for LLC/SNAP encapsulation/decapsulation */
	/* Ethernet-II snap header (RFC1042 for most EtherTypes) */
	const unsigned char rfc1042_header[] __aligned(2) =
	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00 };
	EXPORT_SYMBOL(rfc1042_header);

	/* Bridge-Tunnel header (for EtherTypes ETH_P_AARP and ETH_P_IPX) */
	const unsigned char bridge_tunnel_header[] __aligned(2) =
	{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0xf8 };
	EXPORT_SYMBOL(bridge_tunnel_header);

	unsigned int ieee80211_hdrlen(__le16 fc)
	{
	unsigned int hdrlen = 24;

	if (ieee80211_is_data(fc)) {
	if (ieee80211_has_a4(fc))
	hdrlen = 30;
	if (ieee80211_is_data_qos(fc))
	hdrlen += IEEE80211_QOS_CTL_LEN;
	goto out;
	}

	if (ieee80211_is_ctl(fc)) {
	/*
	* 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 & cpu_to_le16(0x00E0)) == cpu_to_le16(0x00C0))
	hdrlen = 10;
	else
	hdrlen = 16;
	}
	out:
	return hdrlen;
	}
	EXPORT_SYMBOL(ieee80211_hdrlen);

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

	if (unlikely(skb->len < 10))
	return 0;
	hdrlen = ieee80211_hdrlen(hdr->frame_control);
	if (unlikely(hdrlen > skb->len))
	return 0;
	return hdrlen;
	}
	EXPORT_SYMBOL(ieee80211_get_hdrlen_from_skb);

	int ieee80211_get_mesh_hdrlen(struct ieee80211s_hdr *meshhdr)
	{
	int ae = meshhdr->flags & MESH_FLAGS_AE;
	/* 7.1.3.5a.2 */
	switch (ae) {
	case 0:
	return 6;
	case 1:
	return 12;
	case 2:
	return 18;
	case 3:
	return 24;
	default:
	return 6;
	}
	}

	int ieee80211_data_to_8023(struct sk_buff skb, u8 addr,
	enum nl80211_iftype iftype)
	{
	struct ieee80211_hdr hdr = (struct ieee80211_hdr ) skb->data;
	u16 hdrlen, ethertype;
	u8 *payload;
	u8 dst[ETH_ALEN];
	u8 src[ETH_ALEN] __aligned(2);

	if (unlikely(!ieee80211_is_data_present(hdr->frame_control)))
	return -1;

	hdrlen = ieee80211_hdrlen(hdr->frame_control);

	/* convert IEEE 802.11 header + possible LLC headers into Ethernet
	* header
	* IEEE 802.11 address fields:
	* ToDS FromDS Addr1 Addr2 Addr3 Addr4
	* 0 0 DA SA BSSID n/a
	* 0 1 DA BSSID SA n/a
	* 1 0 BSSID SA DA n/a
	* 1 1 RA TA DA SA
	*/
	memcpy(dst, ieee80211_get_DA(hdr), ETH_ALEN);
	memcpy(src, ieee80211_get_SA(hdr), ETH_ALEN);

	switch (hdr->frame_control &
	cpu_to_le16(IEEE80211_FCTL_TODS \| IEEE80211_FCTL_FROMDS)) {
	case cpu_to_le16(IEEE80211_FCTL_TODS):
	if (unlikely(iftype != NL80211_IFTYPE_AP &&
	iftype != NL80211_IFTYPE_AP_VLAN))
	return -1;
	break;
	case cpu_to_le16(IEEE80211_FCTL_TODS \| IEEE80211_FCTL_FROMDS):
	if (unlikely(iftype != NL80211_IFTYPE_WDS &&
	iftype != NL80211_IFTYPE_MESH_POINT))
	return -1;
	if (iftype == NL80211_IFTYPE_MESH_POINT) {
	struct ieee80211s_hdr *meshdr =
	(struct ieee80211s_hdr *) (skb->data + hdrlen);
	hdrlen += ieee80211_get_mesh_hdrlen(meshdr);
	if (meshdr->flags & MESH_FLAGS_AE_A5_A6) {
	memcpy(dst, meshdr->eaddr1, ETH_ALEN);
	memcpy(src, meshdr->eaddr2, ETH_ALEN);
	}
	}
	break;
	case cpu_to_le16(IEEE80211_FCTL_FROMDS):
	if (iftype != NL80211_IFTYPE_STATION \|\|
	(is_multicast_ether_addr(dst) &&
	!compare_ether_addr(src, addr)))
	return -1;
	break;
	case cpu_to_le16(0):
	if (iftype != NL80211_IFTYPE_ADHOC)
	return -1;
	break;
	}

	if (unlikely(skb->len - hdrlen < 8))
	return -1;

	payload = skb->data + hdrlen;
	ethertype = (payload[6] << 8) \| payload[7];

	if (likely((compare_ether_addr(payload, rfc1042_header) == 0 &&
	ethertype != ETH_P_AARP && ethertype != ETH_P_IPX) \|\|
	compare_ether_addr(payload, bridge_tunnel_header) == 0)) {
	/* remove RFC1042 or Bridge-Tunnel encapsulation and
	* replace EtherType */
	skb_pull(skb, hdrlen + 6);
	memcpy(skb_push(skb, ETH_ALEN), src, ETH_ALEN);
	memcpy(skb_push(skb, ETH_ALEN), dst, ETH_ALEN);
	} else {
	struct ethhdr *ehdr;
	__be16 len;

	skb_pull(skb, hdrlen);
	len = htons(skb->len);
	ehdr = (struct ethhdr *) skb_push(skb, sizeof(struct ethhdr));
	memcpy(ehdr->h_dest, dst, ETH_ALEN);
	memcpy(ehdr->h_source, src, ETH_ALEN);
	ehdr->h_proto = len;
	}
	return 0;
	}
	EXPORT_SYMBOL(ieee80211_data_to_8023);

	int ieee80211_data_from_8023(struct sk_buff skb, u8 addr,
	enum nl80211_iftype iftype, u8 *bssid, bool qos)
	{
	struct ieee80211_hdr hdr;
	u16 hdrlen, ethertype;
	__le16 fc;
	const u8 *encaps_data;
	int encaps_len, skip_header_bytes;
	int nh_pos, h_pos;
	int head_need;

	if (unlikely(skb->len < ETH_HLEN))
	return -EINVAL;

	nh_pos = skb_network_header(skb) - skb->data;
	h_pos = skb_transport_header(skb) - skb->data;

	/* convert Ethernet header to proper 802.11 header (based on
	* operation mode) */
	ethertype = (skb->data[12] << 8) \| skb->data[13];
	fc = cpu_to_le16(IEEE80211_FTYPE_DATA \| IEEE80211_STYPE_DATA);

	switch (iftype) {
	case NL80211_IFTYPE_AP:
	case NL80211_IFTYPE_AP_VLAN:
	fc \|= cpu_to_le16(IEEE80211_FCTL_FROMDS);
	/* DA BSSID SA */
	memcpy(hdr.addr1, skb->data, ETH_ALEN);
	memcpy(hdr.addr2, addr, ETH_ALEN);
	memcpy(hdr.addr3, skb->data + ETH_ALEN, ETH_ALEN);
	hdrlen = 24;
	break;
	case NL80211_IFTYPE_STATION:
	fc \|= cpu_to_le16(IEEE80211_FCTL_TODS);
	/* BSSID SA DA */
	memcpy(hdr.addr1, bssid, ETH_ALEN);
	memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
	memcpy(hdr.addr3, skb->data, ETH_ALEN);
	hdrlen = 24;
	break;
	case NL80211_IFTYPE_ADHOC:
	/* DA SA BSSID */
	memcpy(hdr.addr1, skb->data, ETH_ALEN);
	memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
	memcpy(hdr.addr3, bssid, ETH_ALEN);
	hdrlen = 24;
	break;
	default:
	return -EOPNOTSUPP;
	}

	if (qos) {
	fc \|= cpu_to_le16(IEEE80211_STYPE_QOS_DATA);
	hdrlen += 2;
	}

	hdr.frame_control = fc;
	hdr.duration_id = 0;
	hdr.seq_ctrl = 0;

	skip_header_bytes = ETH_HLEN;
	if (ethertype == ETH_P_AARP \|\| ethertype == ETH_P_IPX) {
	encaps_data = bridge_tunnel_header;
	encaps_len = sizeof(bridge_tunnel_header);
	skip_header_bytes -= 2;
	} else if (ethertype > 0x600) {
	encaps_data = rfc1042_header;
	encaps_len = sizeof(rfc1042_header);
	skip_header_bytes -= 2;
	} else {
	encaps_data = NULL;
	encaps_len = 0;
	}

	skb_pull(skb, skip_header_bytes);
	nh_pos -= skip_header_bytes;
	h_pos -= skip_header_bytes;

	head_need = hdrlen + encaps_len - skb_headroom(skb);

	if (head_need > 0 \|\| skb_cloned(skb)) {
	head_need = max(head_need, 0);
	if (head_need)
	skb_orphan(skb);

	if (pskb_expand_head(skb, head_need, 0, GFP_ATOMIC)) {
	printk(KERN_ERR "failed to reallocate Tx buffer\n");
	return -ENOMEM;
	}
	skb->truesize += head_need;
	}

	if (encaps_data) {
	memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len);
	nh_pos += encaps_len;
	h_pos += encaps_len;
	}

	memcpy(skb_push(skb, hdrlen), &hdr, hdrlen);

	nh_pos += hdrlen;
	h_pos += hdrlen;

	/* Update skb pointers to various headers since this modified frame
	* is going to go through Linux networking code that may potentially
	* need things like pointer to IP header. */
	skb_set_mac_header(skb, 0);
	skb_set_network_header(skb, nh_pos);
	skb_set_transport_header(skb, h_pos);

	return 0;
	}
	EXPORT_SYMBOL(ieee80211_data_from_8023);

	/* Given a data frame determine the 802.1p/1d tag to use. */
	unsigned int cfg80211_classify8021d(struct sk_buff *skb)
	{
	unsigned int dscp;

	/* skb->priority values from 256->263 are magic values to
	* directly indicate a specific 802.1d priority. This is used
	* to allow 802.1d priority to be passed directly in from VLAN
	* tags, etc.
	*/
	if (skb->priority >= 256 && skb->priority <= 263)
	return skb->priority - 256;

	switch (skb->protocol) {
	case htons(ETH_P_IP):
	dscp = ip_hdr(skb)->tos & 0xfc;
	break;
	default:
	return 0;
	}

	return dscp >> 5;
	}
	EXPORT_SYMBOL(cfg80211_classify8021d);