Share the same radiotap helper implementation

3 files changed, 570 insertions, 0 deletions

diff --git a/src/utils/radiotap.c b/src/utils/radiotap.c
new file mode 100644
index 0000000..804473f
--- /dev/null
+++ b/src/utils/radiotap.c
@@ -0,0 +1,287 @@
+/*
+ * Radiotap parser
+ *
+ * Copyright 2007		Andy Green <andy@warmcat.com>
+ *
+ * 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.
+ *
+ * Alternatively, this software may be distributed under the terms of BSD
+ * license.
+ *
+ * See README and COPYING for more details.
+ *
+ *
+ * Modified for userspace by Johannes Berg <johannes@sipsolutions.net>
+ * I only modified some things on top to ease syncing should bugs be found.
+ */
+
+#include "includes.h"
+
+#include "common.h"
+#include "radiotap_iter.h"
+
+#define le16_to_cpu		le_to_host16
+#define le32_to_cpu		le_to_host32
+#define __le32			uint32_t
+#define ulong			unsigned long
+#define unlikely(cond)		(cond)
+#define get_unaligned(p)					\
+({								\
+	struct packed_dummy_struct {				\
+		typeof(*(p)) __val;				\
+	} __attribute__((packed)) *__ptr = (void *) (p);	\
+								\
+	__ptr->__val;						\
+})
+
+/* function prototypes and related defs are in radiotap_iter.h */
+
+/**
+ * ieee80211_radiotap_iterator_init - radiotap parser iterator initialization
+ * @iterator: radiotap_iterator to initialize
+ * @radiotap_header: radiotap header to parse
+ * @max_length: total length we can parse into (eg, whole packet length)
+ *
+ * Returns: 0 or a negative error code if there is a problem.
+ *
+ * This function initializes an opaque iterator struct which can then
+ * be passed to ieee80211_radiotap_iterator_next() to visit every radiotap
+ * argument which is present in the header.  It knows about extended
+ * present headers and handles them.
+ *
+ * How to use:
+ * call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator
+ * struct ieee80211_radiotap_iterator (no need to init the struct beforehand)
+ * checking for a good 0 return code.  Then loop calling
+ * __ieee80211_radiotap_iterator_next()... it returns either 0,
+ * -ENOENT if there are no more args to parse, or -EINVAL if there is a problem.
+ * The iterator's @this_arg member points to the start of the argument
+ * associated with the current argument index that is present, which can be
+ * found in the iterator's @this_arg_index member.  This arg index corresponds
+ * to the IEEE80211_RADIOTAP_... defines.
+ *
+ * Radiotap header length:
+ * You can find the CPU-endian total radiotap header length in
+ * iterator->max_length after executing ieee80211_radiotap_iterator_init()
+ * successfully.
+ *
+ * Alignment Gotcha:
+ * You must take care when dereferencing iterator.this_arg
+ * for multibyte types... the pointer is not aligned.  Use
+ * get_unaligned((type *)iterator.this_arg) to dereference
+ * iterator.this_arg for type "type" safely on all arches.
+ *
+ * Example code:
+ * See Documentation/networking/radiotap-headers.txt
+ */
+
+int ieee80211_radiotap_iterator_init(
+    struct ieee80211_radiotap_iterator *iterator,
+    struct ieee80211_radiotap_header *radiotap_header,
+    int max_length)
+{
+	/* Linux only supports version 0 radiotap format */
+	if (radiotap_header->it_version)
+		return -EINVAL;
+
+	/* sanity check for allowed length and radiotap length field */
+	if (max_length < le16_to_cpu(get_unaligned(&radiotap_header->it_len)))
+		return -EINVAL;
+
+	iterator->rtheader = radiotap_header;
+	iterator->max_length = le16_to_cpu(get_unaligned(
+						&radiotap_header->it_len));
+	iterator->arg_index = 0;
+	iterator->bitmap_shifter = le32_to_cpu(get_unaligned(
+						&radiotap_header->it_present));
+	iterator->arg = (u8 *)radiotap_header + sizeof(*radiotap_header);
+	iterator->this_arg = NULL;
+
+	/* find payload start allowing for extended bitmap(s) */
+
+	if (unlikely(iterator->bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT))) {
+		while (le32_to_cpu(get_unaligned((__le32 *)iterator->arg)) &
+				   (1<<IEEE80211_RADIOTAP_EXT)) {
+			iterator->arg += sizeof(u32);
+
+			/*
+			 * check for insanity where the present bitmaps
+			 * keep claiming to extend up to or even beyond the
+			 * stated radiotap header length
+			 */
+
+			if (((ulong)iterator->arg - (ulong)iterator->rtheader)
+			    > (ulong)iterator->max_length)
+				return -EINVAL;
+		}
+
+		iterator->arg += sizeof(u32);
+
+		/*
+		 * no need to check again for blowing past stated radiotap
+		 * header length, because ieee80211_radiotap_iterator_next
+		 * checks it before it is dereferenced
+		 */
+	}
+
+	/* we are all initialized happily */
+
+	return 0;
+}
+
+
+/**
+ * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg
+ * @iterator: radiotap_iterator to move to next arg (if any)
+ *
+ * Returns: 0 if there is an argument to handle,
+ * -ENOENT if there are no more args or -EINVAL
+ * if there is something else wrong.
+ *
+ * This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*)
+ * in @this_arg_index and sets @this_arg to point to the
+ * payload for the field.  It takes care of alignment handling and extended
+ * present fields.  @this_arg can be changed by the caller (eg,
+ * incremented to move inside a compound argument like
+ * IEEE80211_RADIOTAP_CHANNEL).  The args pointed to are in
+ * little-endian format whatever the endianess of your CPU.
+ *
+ * Alignment Gotcha:
+ * You must take care when dereferencing iterator.this_arg
+ * for multibyte types... the pointer is not aligned.  Use
+ * get_unaligned((type *)iterator.this_arg) to dereference
+ * iterator.this_arg for type "type" safely on all arches.
+ */
+
+int ieee80211_radiotap_iterator_next(
+    struct ieee80211_radiotap_iterator *iterator)
+{
+
+	/*
+	 * small length lookup table for all radiotap types we heard of
+	 * starting from b0 in the bitmap, so we can walk the payload
+	 * area of the radiotap header
+	 *
+	 * There is a requirement to pad args, so that args
+	 * of a given length must begin at a boundary of that length
+	 * -- but note that compound args are allowed (eg, 2 x u16
+	 * for IEEE80211_RADIOTAP_CHANNEL) so total arg length is not
+	 * a reliable indicator of alignment requirement.
+	 *
+	 * upper nybble: content alignment for arg
+	 * lower nybble: content length for arg
+	 */
+
+	static const u8 rt_sizes[] = {
+		[IEEE80211_RADIOTAP_TSFT] = 0x88,
+		[IEEE80211_RADIOTAP_FLAGS] = 0x11,
+		[IEEE80211_RADIOTAP_RATE] = 0x11,
+		[IEEE80211_RADIOTAP_CHANNEL] = 0x24,
+		[IEEE80211_RADIOTAP_FHSS] = 0x22,
+		[IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = 0x11,
+		[IEEE80211_RADIOTAP_DBM_ANTNOISE] = 0x11,
+		[IEEE80211_RADIOTAP_LOCK_QUALITY] = 0x22,
+		[IEEE80211_RADIOTAP_TX_ATTENUATION] = 0x22,
+		[IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = 0x22,
+		[IEEE80211_RADIOTAP_DBM_TX_POWER] = 0x11,
+		[IEEE80211_RADIOTAP_ANTENNA] = 0x11,
+		[IEEE80211_RADIOTAP_DB_ANTSIGNAL] = 0x11,
+		[IEEE80211_RADIOTAP_DB_ANTNOISE] = 0x11,
+		[IEEE80211_RADIOTAP_RX_FLAGS] = 0x22,
+		[IEEE80211_RADIOTAP_TX_FLAGS] = 0x22,
+		[IEEE80211_RADIOTAP_RTS_RETRIES] = 0x11,
+		[IEEE80211_RADIOTAP_DATA_RETRIES] = 0x11,
+		/*
+		 * add more here as they are defined in
+		 * include/net/ieee80211_radiotap.h
+		 */
+	};
+
+	/*
+	 * for every radiotap entry we can at
+	 * least skip (by knowing the length)...
+	 */
+
+	while (iterator->arg_index < (int) sizeof(rt_sizes)) {
+		int hit = 0;
+		int pad;
+
+		if (!(iterator->bitmap_shifter & 1))
+			goto next_entry; /* arg not present */
+
+		/*
+		 * arg is present, account for alignment padding
+		 *  8-bit args can be at any alignment
+		 * 16-bit args must start on 16-bit boundary
+		 * 32-bit args must start on 32-bit boundary
+		 * 64-bit args must start on 64-bit boundary
+		 *
+		 * note that total arg size can differ from alignment of
+		 * elements inside arg, so we use upper nybble of length
+		 * table to base alignment on
+		 *
+		 * also note: these alignments are ** relative to the
+		 * start of the radiotap header **.  There is no guarantee
+		 * that the radiotap header itself is aligned on any
+		 * kind of boundary.
+		 *
+		 * the above is why get_unaligned() is used to dereference
+		 * multibyte elements from the radiotap area
+		 */
+
+		pad = (((ulong)iterator->arg) -
+			((ulong)iterator->rtheader)) &
+			((rt_sizes[iterator->arg_index] >> 4) - 1);
+
+		if (pad)
+			iterator->arg +=
+				(rt_sizes[iterator->arg_index] >> 4) - pad;
+
+		/*
+		 * this is what we will return to user, but we need to
+		 * move on first so next call has something fresh to test
+		 */
+		iterator->this_arg_index = iterator->arg_index;
+		iterator->this_arg = iterator->arg;
+		hit = 1;
+
+		/* internally move on the size of this arg */
+		iterator->arg += rt_sizes[iterator->arg_index] & 0x0f;
+
+		/*
+		 * check for insanity where we are given a bitmap that
+		 * claims to have more arg content than the length of the
+		 * radiotap section.  We will normally end up equalling this
+		 * max_length on the last arg, never exceeding it.
+		 */
+
+		if (((ulong)iterator->arg - (ulong)iterator->rtheader) >
+		    (ulong) iterator->max_length)
+			return -EINVAL;
+
+	next_entry:
+		iterator->arg_index++;
+		if (unlikely((iterator->arg_index & 31) == 0)) {
+			/* completed current u32 bitmap */
+			if (iterator->bitmap_shifter & 1) {
+				/* b31 was set, there is more */
+				/* move to next u32 bitmap */
+				iterator->bitmap_shifter = le32_to_cpu(
+					get_unaligned(iterator->next_bitmap));
+				iterator->next_bitmap++;
+			} else
+				/* no more bitmaps: end */
+				iterator->arg_index = sizeof(rt_sizes);
+		} else /* just try the next bit */
+			iterator->bitmap_shifter >>= 1;
+
+		/* if we found a valid arg earlier, return it now */
+		if (hit)
+			return 0;
+	}
+
+	/* we don't know how to handle any more args, we're done */
+	return -ENOENT;
+}
diff --git a/src/utils/radiotap.h b/src/utils/radiotap.h
new file mode 100644
index 0000000..508264c
--- /dev/null
+++ b/src/utils/radiotap.h
@@ -0,0 +1,242 @@
+/* $FreeBSD: src/sys/net80211/ieee80211_radiotap.h,v 1.5 2005/01/22 20:12:05 sam Exp $ */
+/* $NetBSD: ieee80211_radiotap.h,v 1.11 2005/06/22 06:16:02 dyoung Exp $ */
+
+/*-
+ * 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 <stdint.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 {
+	uint8_t it_version;	/* Version 0. Only increases
+				 * for drastic changes,
+				 * introduction of compatible
+				 * new fields does not count.
+				 */
+	uint8_t it_pad;
+	uint16_t it_len;	/* length of the whole
+				 * header in bytes, including
+				 * it_version, it_pad,
+				 * it_len, and data fields.
+				 */
+	uint32_t 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 uint16_t   MHz, bitmap
+ *
+ *      Tx/Rx frequency in MHz, followed by flags (see below).
+ *
+ * IEEE80211_RADIOTAP_FHSS              uint16_t       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      uint16_t       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    uint16_t       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 uint16_t       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          uint16_t       bitmap
+ *
+ *     Properties of received frames. See flags defined below.
+ *
+ * IEEE80211_RADIOTAP_TX_FLAGS          uint16_t       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 */
+
+#endif				/* IEEE80211_RADIOTAP_H */
diff --git a/src/utils/radiotap_iter.h b/src/utils/radiotap_iter.h
new file mode 100644
index 0000000..92a798a
--- /dev/null
+++ b/src/utils/radiotap_iter.h
@@ -0,0 +1,41 @@
+#ifndef __RADIOTAP_ITER_H
+#define __RADIOTAP_ITER_H
+
+#include "radiotap.h"
+
+/* Radiotap header iteration
+ *   implemented in radiotap.c
+ */
+/**
+ * struct ieee80211_radiotap_iterator - tracks walk thru present radiotap args
+ * @rtheader: pointer to the radiotap header we are walking through
+ * @max_length: length of radiotap header in cpu byte ordering
+ * @this_arg_index: IEEE80211_RADIOTAP_... index of current arg
+ * @this_arg: pointer to current radiotap arg
+ * @arg_index: internal next argument index
+ * @arg: internal next argument pointer
+ * @next_bitmap: internal pointer to next present u32
+ * @bitmap_shifter: internal shifter for curr u32 bitmap, b0 set == arg present
+ */
+
+struct ieee80211_radiotap_iterator {
+	struct ieee80211_radiotap_header *rtheader;
+	int max_length;
+	int this_arg_index;
+	unsigned char *this_arg;
+
+	int arg_index;
+	unsigned char *arg;
+	uint32_t *next_bitmap;
+	uint32_t bitmap_shifter;
+};
+
+extern int ieee80211_radiotap_iterator_init(
+   struct ieee80211_radiotap_iterator *iterator,
+   struct ieee80211_radiotap_header *radiotap_header,
+   int max_length);
+
+extern int ieee80211_radiotap_iterator_next(
+   struct ieee80211_radiotap_iterator *iterator);
+
+#endif /* __RADIOTAP_ITER_H */