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linux/net/mac80211/util.c
Daniel Drake 7e9ed18874 [MAC80211]: improved short preamble handling 
Similarly to CTS protection, whether short preambles are used for 802.11b
transmissions should be a per-subif setting, not device global.

For STAs, this patch makes short preamble handling automatic based on the ERP
IE. For APs, hostapd still uses the prism ioctls, but the write ioctl has been
restricted to AP-only subifs.

ieee80211_txrx_data.short_preamble (an unused field) was removed.

Unfortunately, some API changes were required for the following functions:
 - ieee80211_generic_frame_duration
 - ieee80211_rts_duration
 - ieee80211_ctstoself_duration
 - ieee80211_rts_get
 - ieee80211_ctstoself_get
Affected drivers were updated accordingly.

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: Jiri Benc <jbenc@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2007-10-10 16:47:38 -07:00

489 lines
13 KiB
C
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/*
* 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/cfg80211.h>
#include "ieee80211_i.h"
#include "ieee80211_rate.h"
#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 };
/* No encapsulation header if EtherType < 0x600 (=length) */
static const unsigned char eapol_header[] =
{ 0xaa, 0xaa, 0x03, 0x00, 0x00, 0x00, 0x88, 0x8e };
static int rate_list_match(const int *rate_list, int rate)
{
int i;
if (!rate_list)
return 0;
for (i = 0; rate_list[i] >= 0; i++)
if (rate_list[i] == rate)
return 1;
return 0;
}
void ieee80211_prepare_rates(struct ieee80211_local *local,
struct ieee80211_hw_mode *mode)
{
int i;
for (i = 0; i < mode->num_rates; i++) {
struct ieee80211_rate *rate = &mode->rates[i];
rate->flags &= ~(IEEE80211_RATE_SUPPORTED |
IEEE80211_RATE_BASIC);
if (local->supp_rates[mode->mode]) {
if (!rate_list_match(local->supp_rates[mode->mode],
rate->rate))
continue;
}
rate->flags |= IEEE80211_RATE_SUPPORTED;
/* Use configured basic rate set if it is available. If not,
* use defaults that are sane for most cases. */
if (local->basic_rates[mode->mode]) {
if (rate_list_match(local->basic_rates[mode->mode],
rate->rate))
rate->flags |= IEEE80211_RATE_BASIC;
} else switch (mode->mode) {
case MODE_IEEE80211A:
if (rate->rate == 60 || rate->rate == 120 ||
rate->rate == 240)
rate->flags |= IEEE80211_RATE_BASIC;
break;
case MODE_IEEE80211B:
if (rate->rate == 10 || rate->rate == 20)
rate->flags |= IEEE80211_RATE_BASIC;
break;
case MODE_ATHEROS_TURBO:
if (rate->rate == 120 || rate->rate == 240 ||
rate->rate == 480)
rate->flags |= IEEE80211_RATE_BASIC;
break;
case MODE_IEEE80211G:
if (rate->rate == 10 || rate->rate == 20 ||
rate->rate == 55 || rate->rate == 110)
rate->flags |= IEEE80211_RATE_BASIC;
break;
}
/* Set ERP and MANDATORY flags based on phymode */
switch (mode->mode) {
case MODE_IEEE80211A:
if (rate->rate == 60 || rate->rate == 120 ||
rate->rate == 240)
rate->flags |= IEEE80211_RATE_MANDATORY;
break;
case MODE_IEEE80211B:
if (rate->rate == 10)
rate->flags |= IEEE80211_RATE_MANDATORY;
break;
case MODE_ATHEROS_TURBO:
break;
case MODE_IEEE80211G:
if (rate->rate == 10 || rate->rate == 20 ||
rate->rate == 55 || rate->rate == 110 ||
rate->rate == 60 || rate->rate == 120 ||
rate->rate == 240)
rate->flags |= IEEE80211_RATE_MANDATORY;
break;
}
if (ieee80211_is_erp_rate(mode->mode, rate->rate))
rate->flags |= IEEE80211_RATE_ERP;
}
}
u8 *ieee80211_get_bssid(struct ieee80211_hdr *hdr, size_t len)
{
u16 fc;
if (len < 24)
return NULL;
fc = le16_to_cpu(hdr->frame_control);
switch (fc & IEEE80211_FCTL_FTYPE) {
case IEEE80211_FTYPE_DATA:
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:
return hdr->addr3;
case IEEE80211_FTYPE_CTL:
if ((fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_PSPOLL)
return hdr->addr1;
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);
int ieee80211_is_eapol(const struct sk_buff *skb)
{
const struct ieee80211_hdr *hdr;
u16 fc;
int hdrlen;
if (unlikely(skb->len < 10))
return 0;
hdr = (const struct ieee80211_hdr *) skb->data;
fc = le16_to_cpu(hdr->frame_control);
if (unlikely(!WLAN_FC_DATA_PRESENT(fc)))
return 0;
hdrlen = ieee80211_get_hdrlen(fc);
if (unlikely(skb->len >= hdrlen + sizeof(eapol_header) &&
memcmp(skb->data + hdrlen, eapol_header,
sizeof(eapol_header)) == 0))
return 1;
return 0;
}
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.phymode == MODE_IEEE80211A || erp ||
local->hw.conf.phymode == MODE_ATHEROS_TURBO) {
/*
* 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
*/
/* FIX: Atheros Turbo may have different (shorter) duration? */
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, int if_id,
size_t frame_len, int rate)
{
struct ieee80211_local *local = hw_to_local(hw);
struct net_device *bdev = dev_get_by_index(if_id);
struct ieee80211_sub_if_data *sdata;
u16 dur;
int erp;
if (unlikely(!bdev))
return 0;
sdata = IEEE80211_DEV_TO_SUB_IF(bdev);
erp = ieee80211_is_erp_rate(hw->conf.phymode, rate);
dur = ieee80211_frame_duration(local, frame_len, rate,
erp, sdata->short_preamble);
dev_put(bdev);
return cpu_to_le16(dur);
}
EXPORT_SYMBOL(ieee80211_generic_frame_duration);
__le16 ieee80211_rts_duration(struct ieee80211_hw *hw, int if_id,
size_t frame_len,
const struct ieee80211_tx_control *frame_txctl)
{
struct ieee80211_local *local = hw_to_local(hw);
struct ieee80211_rate *rate;
struct net_device *bdev = dev_get_by_index(if_id);
struct ieee80211_sub_if_data *sdata;
int short_preamble;
int erp;
u16 dur;
if (unlikely(!bdev))
return 0;
sdata = IEEE80211_DEV_TO_SUB_IF(bdev);
short_preamble = sdata->short_preamble;
rate = frame_txctl->rts_rate;
erp = !!(rate->flags & IEEE80211_RATE_ERP);
/* CTS duration */
dur = ieee80211_frame_duration(local, 10, rate->rate,
erp, short_preamble);
/* Data frame duration */
dur += ieee80211_frame_duration(local, frame_len, rate->rate,
erp, short_preamble);
/* ACK duration */
dur += ieee80211_frame_duration(local, 10, rate->rate,
erp, short_preamble);
dev_put(bdev);
return cpu_to_le16(dur);
}
EXPORT_SYMBOL(ieee80211_rts_duration);
__le16 ieee80211_ctstoself_duration(struct ieee80211_hw *hw, int if_id,
size_t frame_len,
const struct ieee80211_tx_control *frame_txctl)
{
struct ieee80211_local *local = hw_to_local(hw);
struct ieee80211_rate *rate;
struct net_device *bdev = dev_get_by_index(if_id);
struct ieee80211_sub_if_data *sdata;
int short_preamble;
int erp;
u16 dur;
if (unlikely(!bdev))
return 0;
sdata = IEEE80211_DEV_TO_SUB_IF(bdev);
short_preamble = sdata->short_preamble;
rate = frame_txctl->rts_rate;
erp = !!(rate->flags & IEEE80211_RATE_ERP);
/* Data frame duration */
dur = ieee80211_frame_duration(local, frame_len, rate->rate,
erp, short_preamble);
if (!(frame_txctl->flags & IEEE80211_TXCTL_NO_ACK)) {
/* ACK duration */
dur += ieee80211_frame_duration(local, 10, rate->rate,
erp, short_preamble);
}
dev_put(bdev);
return cpu_to_le16(dur);
}
EXPORT_SYMBOL(ieee80211_ctstoself_duration);
struct ieee80211_rate *
ieee80211_get_rate(struct ieee80211_local *local, int phymode, int hw_rate)
{
struct ieee80211_hw_mode *mode;
int r;
list_for_each_entry(mode, &local->modes_list, list) {
if (mode->mode != phymode)
continue;
for (r = 0; r < mode->num_rates; r++) {
struct ieee80211_rate *rate = &mode->rates[r];
if (rate->val == hw_rate ||
(rate->flags & IEEE80211_RATE_PREAMBLE2 &&
rate->val2 == hw_rate))
return rate;
}
}
return NULL;
}
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);
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