ieee80211_radiotap.h

/*
 * 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.
				 */
};

/* 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)
						 */
/* For IEEE80211_RADIOTAP_RX_FLAGS */
#define IEEE80211_RADIOTAP_F_RX_BADFCS	0x0001	/* frame failed crc check */

/* 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 */