2010-10-14 17:56:06 +00:00
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/*
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* Radiotap parser
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*
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* Copyright 2007 Andy Green <andy@warmcat.com>
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* Copyright 2009 Johannes Berg <johannes@sipsolutions.net>
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*
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2010-10-18 13:26:35 +00:00
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* $Id$
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*
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2010-10-14 17:56:06 +00:00
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Alternatively, this software may be distributed under the terms of BSD
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* license.
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*
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* See COPYING for more details.
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*/
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#include <stddef.h>
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#include <errno.h>
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#include <glib.h>
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#include "pint.h"
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#define le16_to_cpu GINT16_FROM_LE
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#define le32_to_cpu GINT32_FROM_LE
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#define get_unaligned_le16 pletohs
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#define get_unaligned_le32 pletohl
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2012-05-02 04:03:49 +00:00
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#include "packet-ieee80211-radiotap-iter.h"
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2010-10-14 17:56:06 +00:00
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/* function prototypes and related defs are in radiotap_iter.h */
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static const struct radiotap_align_size rtap_namespace_sizes[] = {
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/* [IEEE80211_RADIOTAP_TSFT] = 0 */ { 8, 8 },
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/* [IEEE80211_RADIOTAP_FLAGS] = 1 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_RATE] = 2 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_CHANNEL] = 3 */ { 2, 4 },
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/* [IEEE80211_RADIOTAP_FHSS] = 4 */ { 2, 2 },
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/* [IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = 5 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_DBM_ANTNOISE] = 6 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_LOCK_QUALITY] = 7 */ { 2, 2 },
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/* [IEEE80211_RADIOTAP_TX_ATTENUATION] = 8 */ { 2, 2 },
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/* [IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = 9 */ { 2, 2 },
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/* [IEEE80211_RADIOTAP_DBM_TX_POWER] = 10 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_ANTENNA] = 11 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_DB_ANTSIGNAL] = 12 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_DB_ANTNOISE] = 13 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_RX_FLAGS] = 14 */ { 2, 2 },
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/* [IEEE80211_RADIOTAP_TX_FLAGS] = 15 */ { 2, 2 },
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/* [IEEE80211_RADIOTAP_RTS_RETRIES] = 16 */ { 1, 1 },
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2011-01-27 17:45:45 +00:00
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/* [IEEE80211_RADIOTAP_DATA_RETRIES] = 17 */ { 1, 1 },
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/* [IEEE80211_RADIOTAP_XCHANNEL] = 18 */ { 0, 0 }, /* Unofficial, used by FreeBSD */
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2012-08-08 08:16:34 +00:00
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/* [IEEE80211_RADIOTAP_MCS] = 19 */ { 1, 3 },
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2012-09-18 20:46:05 +00:00
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/* [IEEE80211_RADIOTAP_AMPDU_STATUS] = 20 */ { 4, 8 },
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/* [IEEE80211_RADIOTAP_VHT] = 21 */ { 2, 12 }
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2010-10-14 17:56:06 +00:00
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/*
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* add more here as they are defined in
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* include/net/ieee80211_radiotap.h
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*/
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};
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static const struct ieee80211_radiotap_namespace radiotap_ns = {
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rtap_namespace_sizes,
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(int)(sizeof(rtap_namespace_sizes) / sizeof(rtap_namespace_sizes[0])),
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0,
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0
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};
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2012-12-21 10:26:52 +00:00
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/*
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* Sanity check.
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*/
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#define ITERATOR_VALID(iterator, size) \
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(((iterator)->_arg + (size) - (unsigned char *)((iterator)->_rtheader)) <= \
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(ptrdiff_t)(iterator)->_max_length)
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2010-10-14 17:56:06 +00:00
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/**
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* ieee80211_radiotap_iterator_init - radiotap parser iterator initialization
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* @iterator: radiotap_iterator to initialize
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* @radiotap_header: radiotap header to parse
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* @max_length: total length we can parse into (eg, whole packet length)
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*
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* Returns: 0 or a negative error code if there is a problem.
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*
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* This function initializes an opaque iterator struct which can then
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* be passed to ieee80211_radiotap_iterator_next() to visit every radiotap
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* argument which is present in the header. It knows about extended
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* present headers and handles them.
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*
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* How to use:
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* call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator
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* struct ieee80211_radiotap_iterator (no need to init the struct beforehand)
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* checking for a good 0 return code. Then loop calling
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* __ieee80211_radiotap_iterator_next()... it returns either 0,
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* -ENOENT if there are no more args to parse, or -EINVAL if there is a problem.
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* The iterator's @this_arg member points to the start of the argument
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* associated with the current argument index that is present, which can be
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* found in the iterator's @this_arg_index member. This arg index corresponds
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* to the IEEE80211_RADIOTAP_... defines.
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*
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* Radiotap header length:
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* You can find the CPU-endian total radiotap header length in
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* iterator->max_length after executing ieee80211_radiotap_iterator_init()
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* successfully.
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*
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* Alignment Gotcha:
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* You must take care when dereferencing iterator.this_arg
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* for multibyte types... the pointer is not aligned. Use
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* get_unaligned((type *)iterator.this_arg) to dereference
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* iterator.this_arg for type "type" safely on all arches.
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*
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* Example code:
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* See Documentation/networking/radiotap-headers.txt
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*/
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int ieee80211_radiotap_iterator_init(
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struct ieee80211_radiotap_iterator *iterator,
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struct ieee80211_radiotap_header *radiotap_header,
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int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns)
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{
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/* Linux only supports version 0 radiotap format */
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if (radiotap_header->it_version)
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return -EINVAL;
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/* sanity check for allowed length and radiotap length field */
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if (max_length < get_unaligned_le16(&radiotap_header->it_len))
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return -EINVAL;
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iterator->_rtheader = radiotap_header;
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iterator->_max_length = get_unaligned_le16(&radiotap_header->it_len);
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iterator->_arg_index = 0;
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iterator->_bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present);
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iterator->_arg = (guint8 *)radiotap_header + sizeof(*radiotap_header);
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iterator->_reset_on_ext = 0;
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iterator->_next_bitmap = &radiotap_header->it_present;
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iterator->_next_bitmap++;
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iterator->_vns = vns;
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iterator->current_namespace = &radiotap_ns;
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iterator->is_radiotap_ns = 1;
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#ifdef RADIOTAP_SUPPORT_OVERRIDES
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iterator->n_overrides = 0;
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iterator->overrides = NULL;
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#endif
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/* find payload start allowing for extended bitmap(s) */
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if (iterator->_bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT)) {
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while (get_unaligned_le32(iterator->_arg) &
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(1 << IEEE80211_RADIOTAP_EXT)) {
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iterator->_arg += sizeof(guint32);
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/*
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* check for insanity where the present bitmaps
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* keep claiming to extend up to or even beyond the
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* stated radiotap header length
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*/
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2012-12-21 10:26:52 +00:00
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if (!ITERATOR_VALID(iterator, 0))
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2010-10-14 17:56:06 +00:00
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return -EINVAL;
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}
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iterator->_arg += sizeof(guint32);
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/*
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* no need to check again for blowing past stated radiotap
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* header length, because ieee80211_radiotap_iterator_next
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* checks it before it is dereferenced
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*/
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}
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iterator->this_arg = iterator->_arg;
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/* we are all initialized happily */
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return 0;
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}
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static void find_ns(struct ieee80211_radiotap_iterator *iterator,
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guint32 oui, guint8 subns)
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{
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int i;
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iterator->current_namespace = NULL;
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if (!iterator->_vns)
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return;
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for (i = 0; i < iterator->_vns->n_ns; i++) {
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if (iterator->_vns->ns[i].oui != oui)
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continue;
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if (iterator->_vns->ns[i].subns != subns)
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continue;
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iterator->current_namespace = &iterator->_vns->ns[i];
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break;
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}
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}
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#ifdef RADIOTAP_SUPPORT_OVERRIDES
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static int find_override(struct ieee80211_radiotap_iterator *iterator,
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int *align, int *size)
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{
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int i;
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if (!iterator->overrides)
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return 0;
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for (i = 0; i < iterator->n_overrides; i++) {
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if (iterator->_arg_index == iterator->overrides[i].field) {
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*align = iterator->overrides[i].align;
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*size = iterator->overrides[i].size;
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if (!*align) /* erroneous override */
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return 0;
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return 1;
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}
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}
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return 0;
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}
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#endif
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/**
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* ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg
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* @iterator: radiotap_iterator to move to next arg (if any)
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*
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* Returns: 0 if there is an argument to handle,
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* -ENOENT if there are no more args or -EINVAL
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* if there is something else wrong.
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*
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* This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*)
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* in @this_arg_index and sets @this_arg to point to the
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* payload for the field. It takes care of alignment handling and extended
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* present fields. @this_arg can be changed by the caller (eg,
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* incremented to move inside a compound argument like
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* IEEE80211_RADIOTAP_CHANNEL). The args pointed to are in
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* little-endian format whatever the endianess of your CPU.
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*
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* Alignment Gotcha:
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* You must take care when dereferencing iterator.this_arg
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* for multibyte types... the pointer is not aligned. Use
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* get_unaligned((type *)iterator.this_arg) to dereference
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* iterator.this_arg for type "type" safely on all arches.
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*/
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int ieee80211_radiotap_iterator_next(
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struct ieee80211_radiotap_iterator *iterator)
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{
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while (1) {
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int hit = 0;
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int pad, align, size, subns;
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guint32 oui;
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/* if no more EXT bits, that's it */
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if ((iterator->_arg_index % 32) == IEEE80211_RADIOTAP_EXT &&
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!(iterator->_bitmap_shifter & 1))
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return -ENOENT;
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if (!(iterator->_bitmap_shifter & 1))
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goto next_entry; /* arg not present */
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/* get alignment/size of data */
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switch (iterator->_arg_index % 32) {
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case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
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case IEEE80211_RADIOTAP_EXT:
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align = 1;
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size = 0;
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break;
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case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
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align = 2;
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size = 6;
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break;
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default:
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#ifdef RADIOTAP_SUPPORT_OVERRIDES
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if (find_override(iterator, &align, &size)) {
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/* all set */
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} else
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#endif
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if (!iterator->current_namespace ||
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iterator->_arg_index >= iterator->current_namespace->n_bits) {
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if (iterator->current_namespace == &radiotap_ns)
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return -ENOENT;
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align = 0;
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} else {
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align = iterator->current_namespace->align_size[iterator->_arg_index].align;
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size = iterator->current_namespace->align_size[iterator->_arg_index].size;
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}
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if (!align) {
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/* skip all subsequent data */
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iterator->_arg = iterator->_next_ns_data;
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/* give up on this namespace */
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iterator->current_namespace = NULL;
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goto next_entry;
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}
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break;
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}
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/*
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* arg is present, account for alignment padding
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*
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* Note that these alignments are relative to the start
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* of the radiotap header. There is no guarantee
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* that the radiotap header itself is aligned on any
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* kind of boundary.
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*
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* The above is why get_unaligned() is used to dereference
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* multibyte elements from the radiotap area.
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*/
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2012-12-21 10:26:52 +00:00
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pad = (int)((iterator->_arg - (unsigned char *)iterator->_rtheader) & (align - 1));
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2010-10-14 17:56:06 +00:00
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if (pad)
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iterator->_arg += align - pad;
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if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE) {
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int vnslen;
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2012-12-21 10:26:52 +00:00
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if (!ITERATOR_VALID(iterator, size))
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2010-10-14 17:56:06 +00:00
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return -EINVAL;
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oui = (*iterator->_arg << 16) |
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(*(iterator->_arg + 1) << 8) |
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*(iterator->_arg + 2);
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subns = *(iterator->_arg + 3);
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find_ns(iterator, oui, subns);
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vnslen = get_unaligned_le16(iterator->_arg + 4);
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iterator->_next_ns_data = iterator->_arg + size + vnslen;
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if (!iterator->current_namespace)
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size += vnslen;
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}
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/*
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* this is what we will return to user, but we need to
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* move on first so next call has something fresh to test
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*/
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iterator->this_arg_index = iterator->_arg_index;
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iterator->this_arg = iterator->_arg;
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iterator->this_arg_size = size;
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/* internally move on the size of this arg */
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iterator->_arg += size;
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/*
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* check for insanity where we are given a bitmap that
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* claims to have more arg content than the length of the
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|
|
* radiotap section. We will normally end up equalling this
|
|
|
|
* max_length on the last arg, never exceeding it.
|
|
|
|
*/
|
|
|
|
|
2012-12-21 10:26:52 +00:00
|
|
|
if (!ITERATOR_VALID(iterator, 0))
|
2010-10-14 17:56:06 +00:00
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
/* these special ones are valid in each bitmap word */
|
|
|
|
switch (iterator->_arg_index % 32) {
|
|
|
|
case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
|
|
|
|
iterator->_reset_on_ext = 1;
|
|
|
|
|
|
|
|
iterator->is_radiotap_ns = 0;
|
|
|
|
/*
|
|
|
|
* If parser didn't register this vendor
|
|
|
|
* namespace with us, allow it to show it
|
|
|
|
* as 'raw. Do do that, set argument index
|
|
|
|
* to vendor namespace.
|
|
|
|
*/
|
|
|
|
iterator->this_arg_index =
|
|
|
|
IEEE80211_RADIOTAP_VENDOR_NAMESPACE;
|
|
|
|
if (!iterator->current_namespace)
|
|
|
|
hit = 1;
|
|
|
|
goto next_entry;
|
|
|
|
case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
|
|
|
|
iterator->_reset_on_ext = 1;
|
|
|
|
iterator->current_namespace = &radiotap_ns;
|
|
|
|
iterator->is_radiotap_ns = 1;
|
|
|
|
goto next_entry;
|
|
|
|
case IEEE80211_RADIOTAP_EXT:
|
|
|
|
/*
|
|
|
|
* bit 31 was set, there is more
|
|
|
|
* -- move to next u32 bitmap
|
|
|
|
*/
|
|
|
|
iterator->_bitmap_shifter =
|
|
|
|
get_unaligned_le32(iterator->_next_bitmap);
|
|
|
|
iterator->_next_bitmap++;
|
|
|
|
if (iterator->_reset_on_ext)
|
|
|
|
iterator->_arg_index = 0;
|
|
|
|
else
|
|
|
|
iterator->_arg_index++;
|
|
|
|
iterator->_reset_on_ext = 0;
|
|
|
|
break;
|
|
|
|
default:
|
|
|
|
/* we've got a hit! */
|
|
|
|
hit = 1;
|
|
|
|
next_entry:
|
|
|
|
iterator->_bitmap_shifter >>= 1;
|
|
|
|
iterator->_arg_index++;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* if we found a valid arg earlier, return it now */
|
|
|
|
if (hit)
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
}
|