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alistair23-linux/include/net/ieee80211_radiotap.h
Johannes Berg 6a86b9c78e mac80211: fix radiotap header generation 
In

  commit 601ae7f25a
  Author: Bruno Randolf <br1@einfach.org>
  Date:   Thu May 8 19:22:43 2008 +0200

      mac80211: make rx radiotap header more flexible

code was added that tried to align the radiotap header
position in memory based on the radiotap header length.
Quite obviously, that is completely useless.

Instead of trying to do that, use unaligned accesses
to generate the radiotap header. To properly do that,
we also need to mark struct ieee80211_radiotap_header
packed, but that is fine since it's already packed
(and it should be marked packed anyway since its a
wire format).

Cc: Bruno Randolf <br1@einfach.org>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2009-10-30 16:49:20 -04:00

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/*
* Copyright (c) 2003, 2004 David Young. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of David Young may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY DAVID YOUNG ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL DAVID
* YOUNG BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*/
/*
* Modifications to fit into the linux IEEE 802.11 stack,
* Mike Kershaw (dragorn@kismetwireless.net)
*/
#ifndef IEEE80211RADIOTAP_H
#define IEEE80211RADIOTAP_H
#include <linux/if_ether.h>
#include <linux/kernel.h>
#include <asm/unaligned.h>
/* Base version of the radiotap packet header data */
#define PKTHDR_RADIOTAP_VERSION 0
/* A generic radio capture format is desirable. There is one for
* Linux, but it is neither rigidly defined (there were not even
* units given for some fields) nor easily extensible.
*
* I suggest the following extensible radio capture format. It is
* based on a bitmap indicating which fields are present.
*
* I am trying to describe precisely what the application programmer
* should expect in the following, and for that reason I tell the
* units and origin of each measurement (where it applies), or else I
* use sufficiently weaselly language ("is a monotonically nondecreasing
* function of...") that I cannot set false expectations for lawyerly
* readers.
*/
/*
* The radio capture header precedes the 802.11 header.
* All data in the header is little endian on all platforms.
*/
struct ieee80211_radiotap_header {
u8 it_version; /* Version 0. Only increases
* for drastic changes,
* introduction of compatible
* new fields does not count.
*/
u8 it_pad;
__le16 it_len; /* length of the whole
* header in bytes, including
* it_version, it_pad,
* it_len, and data fields.
*/
__le32 it_present; /* A bitmap telling which
* fields are present. Set bit 31
* (0x80000000) to extend the
* bitmap by another 32 bits.
* Additional extensions are made
* by setting bit 31.
*/
} __packed;
/* Name Data type Units
* ---- --------- -----
*
* IEEE80211_RADIOTAP_TSFT __le64 microseconds
*
* Value in microseconds of the MAC's 64-bit 802.11 Time
* Synchronization Function timer when the first bit of the
* MPDU arrived at the MAC. For received frames, only.
*
* IEEE80211_RADIOTAP_CHANNEL 2 x __le16 MHz, bitmap
*
* Tx/Rx frequency in MHz, followed by flags (see below).
*
* IEEE80211_RADIOTAP_FHSS __le16 see below
*
* For frequency-hopping radios, the hop set (first byte)
* and pattern (second byte).
*
* IEEE80211_RADIOTAP_RATE u8 500kb/s
*
* Tx/Rx data rate
*
* IEEE80211_RADIOTAP_DBM_ANTSIGNAL s8 decibels from
* one milliwatt (dBm)
*
* RF signal power at the antenna, decibel difference from
* one milliwatt.
*
* IEEE80211_RADIOTAP_DBM_ANTNOISE s8 decibels from
* one milliwatt (dBm)
*
* RF noise power at the antenna, decibel difference from one
* milliwatt.
*
* IEEE80211_RADIOTAP_DB_ANTSIGNAL u8 decibel (dB)
*
* RF signal power at the antenna, decibel difference from an
* arbitrary, fixed reference.
*
* IEEE80211_RADIOTAP_DB_ANTNOISE u8 decibel (dB)
*
* RF noise power at the antenna, decibel difference from an
* arbitrary, fixed reference point.
*
* IEEE80211_RADIOTAP_LOCK_QUALITY __le16 unitless
*
* Quality of Barker code lock. Unitless. Monotonically
* nondecreasing with "better" lock strength. Called "Signal
* Quality" in datasheets. (Is there a standard way to measure
* this?)
*
* IEEE80211_RADIOTAP_TX_ATTENUATION __le16 unitless
*
* Transmit power expressed as unitless distance from max
* power set at factory calibration. 0 is max power.
* Monotonically nondecreasing with lower power levels.
*
* IEEE80211_RADIOTAP_DB_TX_ATTENUATION __le16 decibels (dB)
*
* Transmit power expressed as decibel distance from max power
* set at factory calibration. 0 is max power. Monotonically
* nondecreasing with lower power levels.
*
* IEEE80211_RADIOTAP_DBM_TX_POWER s8 decibels from
* one milliwatt (dBm)
*
* Transmit power expressed as dBm (decibels from a 1 milliwatt
* reference). This is the absolute power level measured at
* the antenna port.
*
* IEEE80211_RADIOTAP_FLAGS u8 bitmap
*
* Properties of transmitted and received frames. See flags
* defined below.
*
* IEEE80211_RADIOTAP_ANTENNA u8 antenna index
*
* Unitless indication of the Rx/Tx antenna for this packet.
* The first antenna is antenna 0.
*
* IEEE80211_RADIOTAP_RX_FLAGS __le16 bitmap
*
* Properties of received frames. See flags defined below.
*
* IEEE80211_RADIOTAP_TX_FLAGS __le16 bitmap
*
* Properties of transmitted frames. See flags defined below.
*
* IEEE80211_RADIOTAP_RTS_RETRIES u8 data
*
* Number of rts retries a transmitted frame used.
*
* IEEE80211_RADIOTAP_DATA_RETRIES u8 data
*
* Number of unicast retries a transmitted frame used.
*
*/
enum ieee80211_radiotap_type {
IEEE80211_RADIOTAP_TSFT = 0,
IEEE80211_RADIOTAP_FLAGS = 1,
IEEE80211_RADIOTAP_RATE = 2,
IEEE80211_RADIOTAP_CHANNEL = 3,
IEEE80211_RADIOTAP_FHSS = 4,
IEEE80211_RADIOTAP_DBM_ANTSIGNAL = 5,
IEEE80211_RADIOTAP_DBM_ANTNOISE = 6,
IEEE80211_RADIOTAP_LOCK_QUALITY = 7,
IEEE80211_RADIOTAP_TX_ATTENUATION = 8,
IEEE80211_RADIOTAP_DB_TX_ATTENUATION = 9,
IEEE80211_RADIOTAP_DBM_TX_POWER = 10,
IEEE80211_RADIOTAP_ANTENNA = 11,
IEEE80211_RADIOTAP_DB_ANTSIGNAL = 12,
IEEE80211_RADIOTAP_DB_ANTNOISE = 13,
IEEE80211_RADIOTAP_RX_FLAGS = 14,
IEEE80211_RADIOTAP_TX_FLAGS = 15,
IEEE80211_RADIOTAP_RTS_RETRIES = 16,
IEEE80211_RADIOTAP_DATA_RETRIES = 17,
IEEE80211_RADIOTAP_EXT = 31
};
/* Channel flags. */
#define IEEE80211_CHAN_TURBO 0x0010 /* Turbo channel */
#define IEEE80211_CHAN_CCK 0x0020 /* CCK channel */
#define IEEE80211_CHAN_OFDM 0x0040 /* OFDM channel */
#define IEEE80211_CHAN_2GHZ 0x0080 /* 2 GHz spectrum channel. */
#define IEEE80211_CHAN_5GHZ 0x0100 /* 5 GHz spectrum channel */
#define IEEE80211_CHAN_PASSIVE 0x0200 /* Only passive scan allowed */
#define IEEE80211_CHAN_DYN 0x0400 /* Dynamic CCK-OFDM channel */
#define IEEE80211_CHAN_GFSK 0x0800 /* GFSK channel (FHSS PHY) */
/* For IEEE80211_RADIOTAP_FLAGS */
#define IEEE80211_RADIOTAP_F_CFP 0x01 /* sent/received
* during CFP
*/
#define IEEE80211_RADIOTAP_F_SHORTPRE 0x02 /* sent/received
* with short
* preamble
*/
#define IEEE80211_RADIOTAP_F_WEP 0x04 /* sent/received
* with WEP encryption
*/
#define IEEE80211_RADIOTAP_F_FRAG 0x08 /* sent/received
* with fragmentation
*/
#define IEEE80211_RADIOTAP_F_FCS 0x10 /* frame includes FCS */
#define IEEE80211_RADIOTAP_F_DATAPAD 0x20 /* frame has padding between
* 802.11 header and payload
* (to 32-bit boundary)
*/
#define IEEE80211_RADIOTAP_F_BADFCS 0x40 /* bad FCS */
/* For IEEE80211_RADIOTAP_RX_FLAGS */
#define IEEE80211_RADIOTAP_F_RX_BADPLCP 0x0002 /* frame has bad PLCP */
/* For IEEE80211_RADIOTAP_TX_FLAGS */
#define IEEE80211_RADIOTAP_F_TX_FAIL 0x0001 /* failed due to excessive
* retries */
#define IEEE80211_RADIOTAP_F_TX_CTS 0x0002 /* used cts 'protection' */
#define IEEE80211_RADIOTAP_F_TX_RTS 0x0004 /* used rts/cts handshake */
/* Ugly macro to convert literal channel numbers into their mhz equivalents
* There are certianly some conditions that will break this (like feeding it '30')
* but they shouldn't arise since nothing talks on channel 30. */
#define ieee80211chan2mhz(x) \
(((x) <= 14) ? \
(((x) == 14) ? 2484 : ((x) * 5) + 2407) : \
((x) + 1000) * 5)
/* helpers */
static inline int ieee80211_get_radiotap_len(unsigned char *data)
{
struct ieee80211_radiotap_header *hdr =
(struct ieee80211_radiotap_header *)data;
return get_unaligned_le16(&hdr->it_len);
}
#endif /* IEEE80211_RADIOTAP_H */
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