[linux.git] / net / wireless / radiotap.c

/*
 * Radiotap parser
 *
 * Copyright 2007		Andy Green <[email protected]>
 * Copyright 2009		Johannes Berg <[email protected]>
 *
 * 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 COPYING for more details.
 */

#include <linux/kernel.h>
#include <net/cfg80211.h>
#include <net/ieee80211_radiotap.h>
#include <asm/unaligned.h>

/* function prototypes and related defs are in include/net/cfg80211.h */

static const struct radiotap_align_size rtap_namespace_sizes[] = {
	[IEEE80211_RADIOTAP_TSFT] = { .align = 8, .size = 8, },
	[IEEE80211_RADIOTAP_FLAGS] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_RATE] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_CHANNEL] = { .align = 2, .size = 4, },
	[IEEE80211_RADIOTAP_FHSS] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_DBM_ANTNOISE] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_LOCK_QUALITY] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_TX_ATTENUATION] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_DBM_TX_POWER] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_ANTENNA] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_DB_ANTSIGNAL] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_DB_ANTNOISE] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_RX_FLAGS] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_TX_FLAGS] = { .align = 2, .size = 2, },
	[IEEE80211_RADIOTAP_RTS_RETRIES] = { .align = 1, .size = 1, },
	[IEEE80211_RADIOTAP_DATA_RETRIES] = { .align = 1, .size = 1, },
	/*
	 * add more here as they are defined in radiotap.h
	 */
};

static const struct ieee80211_radiotap_namespace radiotap_ns = {
	.n_bits = ARRAY_SIZE(rtap_namespace_sizes),
	.align_size = rtap_namespace_sizes,
};

/**
 * 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, const struct ieee80211_radiotap_vendor_namespaces *vns)
{
	/* 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 < get_unaligned_le16(&radiotap_header->it_len))
		return -EINVAL;

	iterator->_rtheader = radiotap_header;
	iterator->_max_length = get_unaligned_le16(&radiotap_header->it_len);
	iterator->_arg_index = 0;
	iterator->_bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present);
	iterator->_arg = (uint8_t *)radiotap_header + sizeof(*radiotap_header);
	iterator->_reset_on_ext = 0;
	iterator->_next_bitmap = &radiotap_header->it_present;
	iterator->_next_bitmap++;
	iterator->_vns = vns;
	iterator->current_namespace = &radiotap_ns;
	iterator->is_radiotap_ns = 1;

	/* find payload start allowing for extended bitmap(s) */

	if (iterator->_bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT)) {
		while (get_unaligned_le32(iterator->_arg) &
					(1 << IEEE80211_RADIOTAP_EXT)) {
			iterator->_arg += sizeof(uint32_t);

			/*
			 * check for insanity where the present bitmaps
			 * keep claiming to extend up to or even beyond the
			 * stated radiotap header length
			 */

			if ((unsigned long)iterator->_arg -
			    (unsigned long)iterator->_rtheader >
			    (unsigned long)iterator->_max_length)
				return -EINVAL;
		}

		iterator->_arg += sizeof(uint32_t);

		/*
		 * no need to check again for blowing past stated radiotap
		 * header length, because ieee80211_radiotap_iterator_next
		 * checks it before it is dereferenced
		 */
	}

	iterator->this_arg = iterator->_arg;

	/* we are all initialized happily */

	return 0;
}
EXPORT_SYMBOL(ieee80211_radiotap_iterator_init);

static void find_ns(struct ieee80211_radiotap_iterator *iterator,
		    uint32_t oui, uint8_t subns)
{
	int i;

	iterator->current_namespace = NULL;

	if (!iterator->_vns)
		return;

	for (i = 0; i < iterator->_vns->n_ns; i++) {
		if (iterator->_vns->ns[i].oui != oui)
			continue;
		if (iterator->_vns->ns[i].subns != subns)
			continue;

		iterator->current_namespace = &iterator->_vns->ns[i];
		break;
	}
}


/**
 * 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)
{
	while (1) {
		int hit = 0;
		int pad, align, size, subns;
		uint32_t oui;

		/* if no more EXT bits, that's it */
		if ((iterator->_arg_index % 32) == IEEE80211_RADIOTAP_EXT &&
		    !(iterator->_bitmap_shifter & 1))
			return -ENOENT;

		if (!(iterator->_bitmap_shifter & 1))
			goto next_entry; /* arg not present */

		/* get alignment/size of data */
		switch (iterator->_arg_index % 32) {
		case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
		case IEEE80211_RADIOTAP_EXT:
			align = 1;
			size = 0;
			break;
		case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
			align = 2;
			size = 6;
			break;
		default:
			if (!iterator->current_namespace ||
			    iterator->_arg_index >= iterator->current_namespace->n_bits) {
				if (iterator->current_namespace == &radiotap_ns)
					return -ENOENT;
				align = 0;
			} else {
				align = iterator->current_namespace->align_size[iterator->_arg_index].align;
				size = iterator->current_namespace->align_size[iterator->_arg_index].size;
			}
			if (!align) {
				/* skip all subsequent data */
				iterator->_arg = iterator->_next_ns_data;
				/* give up on this namespace */
				iterator->current_namespace = NULL;
				goto next_entry;
			}
			break;
		}

		/*
		 * arg is present, account for alignment padding
		 *
		 * Note that 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 = ((unsigned long)iterator->_arg -
		       (unsigned long)iterator->_rtheader) & (align - 1);

		if (pad)
			iterator->_arg += align - pad;

		if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE) {
			int vnslen;

			if ((unsigned long)iterator->_arg + size -
			    (unsigned long)iterator->_rtheader >
			    (unsigned long)iterator->_max_length)
				return -EINVAL;

			oui = (*iterator->_arg << 16) |
				(*(iterator->_arg + 1) << 8) |
				*(iterator->_arg + 2);
			subns = *(iterator->_arg + 3);

			find_ns(iterator, oui, subns);

			vnslen = get_unaligned_le16(iterator->_arg + 4);
			iterator->_next_ns_data = iterator->_arg + size + vnslen;
			if (!iterator->current_namespace)
				size += vnslen;
		}

		/*
		 * 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;
		iterator->this_arg_size = size;

		/* internally move on the size of this arg */
		iterator->_arg += size;

		/*
		 * 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 ((unsigned long)iterator->_arg -
		    (unsigned long)iterator->_rtheader >
		    (unsigned long)iterator->_max_length)
			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;
	}
}
EXPORT_SYMBOL(ieee80211_radiotap_iterator_next);
Commit	Line	Data
179f831b AG	1	/*
	2	* Radiotap parser
	3	*
	4	* Copyright 2007 Andy Green <[email protected]>
33e5a2f7 JB	5	* Copyright 2009 Johannes Berg <[email protected]>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
	10	*
	11	* Alternatively, this software may be distributed under the terms of BSD
	12	* license.
	13	*
	14	* See COPYING for more details.
179f831b AG	15	*/
179f831b AG	16
94262316	17	#include <linux/kernel.h>
179f831b AG	18	#include <net/cfg80211.h>
	19	#include <net/ieee80211_radiotap.h>
	20	#include <asm/unaligned.h>
	21
	22	/* function prototypes and related defs are in include/net/cfg80211.h */
	23
33e5a2f7 JB	24	static const struct radiotap_align_size rtap_namespace_sizes[] = {
	25	[IEEE80211_RADIOTAP_TSFT] = { .align = 8, .size = 8, },
	26	[IEEE80211_RADIOTAP_FLAGS] = { .align = 1, .size = 1, },
	27	[IEEE80211_RADIOTAP_RATE] = { .align = 1, .size = 1, },
	28	[IEEE80211_RADIOTAP_CHANNEL] = { .align = 2, .size = 4, },
	29	[IEEE80211_RADIOTAP_FHSS] = { .align = 2, .size = 2, },
	30	[IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = { .align = 1, .size = 1, },
	31	[IEEE80211_RADIOTAP_DBM_ANTNOISE] = { .align = 1, .size = 1, },
	32	[IEEE80211_RADIOTAP_LOCK_QUALITY] = { .align = 2, .size = 2, },
	33	[IEEE80211_RADIOTAP_TX_ATTENUATION] = { .align = 2, .size = 2, },
	34	[IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = { .align = 2, .size = 2, },
	35	[IEEE80211_RADIOTAP_DBM_TX_POWER] = { .align = 1, .size = 1, },
	36	[IEEE80211_RADIOTAP_ANTENNA] = { .align = 1, .size = 1, },
	37	[IEEE80211_RADIOTAP_DB_ANTSIGNAL] = { .align = 1, .size = 1, },
	38	[IEEE80211_RADIOTAP_DB_ANTNOISE] = { .align = 1, .size = 1, },
	39	[IEEE80211_RADIOTAP_RX_FLAGS] = { .align = 2, .size = 2, },
	40	[IEEE80211_RADIOTAP_TX_FLAGS] = { .align = 2, .size = 2, },
	41	[IEEE80211_RADIOTAP_RTS_RETRIES] = { .align = 1, .size = 1, },
	42	[IEEE80211_RADIOTAP_DATA_RETRIES] = { .align = 1, .size = 1, },
	43	/*
	44	* add more here as they are defined in radiotap.h
	45	*/
	46	};
	47
	48	static const struct ieee80211_radiotap_namespace radiotap_ns = {
94262316	49	.n_bits = ARRAY_SIZE(rtap_namespace_sizes),
33e5a2f7 JB	50	.align_size = rtap_namespace_sizes,
	51	};
	52
179f831b AG	53	/**
	54	* ieee80211_radiotap_iterator_init - radiotap parser iterator initialization
	55	* @iterator: radiotap_iterator to initialize
	56	* @radiotap_header: radiotap header to parse
	57	* @max_length: total length we can parse into (eg, whole packet length)
	58	*
	59	* Returns: 0 or a negative error code if there is a problem.
	60	*
	61	* This function initializes an opaque iterator struct which can then
	62	* be passed to ieee80211_radiotap_iterator_next() to visit every radiotap
	63	* argument which is present in the header. It knows about extended
	64	* present headers and handles them.
	65	*
	66	* How to use:
	67	* call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator
	68	* struct ieee80211_radiotap_iterator (no need to init the struct beforehand)
	69	* checking for a good 0 return code. Then loop calling
	70	* __ieee80211_radiotap_iterator_next()... it returns either 0,
	71	* -ENOENT if there are no more args to parse, or -EINVAL if there is a problem.
	72	* The iterator's @this_arg member points to the start of the argument
	73	* associated with the current argument index that is present, which can be
	74	* found in the iterator's @this_arg_index member. This arg index corresponds
	75	* to the IEEE80211_RADIOTAP_... defines.
	76	*
	77	* Radiotap header length:
	78	* You can find the CPU-endian total radiotap header length in
	79	* iterator->max_length after executing ieee80211_radiotap_iterator_init()
	80	* successfully.
	81	*
	82	* Alignment Gotcha:
	83	* You must take care when dereferencing iterator.this_arg
	84	* for multibyte types... the pointer is not aligned. Use
	85	* get_unaligned((type *)iterator.this_arg) to dereference
	86	* iterator.this_arg for type "type" safely on all arches.
	87	*
	88	* Example code:
	89	* See Documentation/networking/radiotap-headers.txt
	90	*/
	91
	92	int ieee80211_radiotap_iterator_init(
33e5a2f7 JB	93	struct ieee80211_radiotap_iterator *iterator,
	94	struct ieee80211_radiotap_header *radiotap_header,
	95	int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns)
179f831b AG	96	{
	97	/* Linux only supports version 0 radiotap format */
	98	if (radiotap_header->it_version)
	99	return -EINVAL;
	100
	101	/* sanity check for allowed length and radiotap length field */
ae7245cb	102	if (max_length < get_unaligned_le16(&radiotap_header->it_len))
179f831b AG	103	return -EINVAL;
179f831b AG	104
33e5a2f7 JB	105	iterator->_rtheader = radiotap_header;
	106	iterator->_max_length = get_unaligned_le16(&radiotap_header->it_len);
	107	iterator->_arg_index = 0;
	108	iterator->_bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present);
	109	iterator->_arg = (uint8_t )radiotap_header + sizeof(radiotap_header);
	110	iterator->_reset_on_ext = 0;
	111	iterator->_next_bitmap = &radiotap_header->it_present;
	112	iterator->_next_bitmap++;
	113	iterator->_vns = vns;
	114	iterator->current_namespace = &radiotap_ns;
	115	iterator->is_radiotap_ns = 1;
179f831b AG	116
	117	/* find payload start allowing for extended bitmap(s) */
	118
33e5a2f7 JB	119	if (iterator->_bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT)) {
	120	while (get_unaligned_le32(iterator->_arg) &
	121	(1 << IEEE80211_RADIOTAP_EXT)) {
	122	iterator->_arg += sizeof(uint32_t);
179f831b AG	123
	124	/*
	125	* check for insanity where the present bitmaps
	126	* keep claiming to extend up to or even beyond the
	127	* stated radiotap header length
	128	*/
	129
33e5a2f7 JB	130	if ((unsigned long)iterator->_arg -
	131	(unsigned long)iterator->_rtheader >
	132	(unsigned long)iterator->_max_length)
179f831b AG	133	return -EINVAL;
	134	}
	135
33e5a2f7	136	iterator->_arg += sizeof(uint32_t);
179f831b AG	137
	138	/*
	139	* no need to check again for blowing past stated radiotap
	140	* header length, because ieee80211_radiotap_iterator_next
	141	* checks it before it is dereferenced
	142	*/
	143	}
	144
33e5a2f7 JB	145	iterator->this_arg = iterator->_arg;
33e5a2f7 JB	146
179f831b AG	147	/* we are all initialized happily */
	148
	149	return 0;
	150	}
	151	EXPORT_SYMBOL(ieee80211_radiotap_iterator_init);
	152
33e5a2f7 JB	153	static void find_ns(struct ieee80211_radiotap_iterator *iterator,
	154	uint32_t oui, uint8_t subns)
	155	{
	156	int i;
	157
	158	iterator->current_namespace = NULL;
	159
	160	if (!iterator->_vns)
	161	return;
	162
	163	for (i = 0; i < iterator->_vns->n_ns; i++) {
	164	if (iterator->_vns->ns[i].oui != oui)
	165	continue;
	166	if (iterator->_vns->ns[i].subns != subns)
	167	continue;
	168
	169	iterator->current_namespace = &iterator->_vns->ns[i];
	170	break;
	171	}
	172	}
	173
	174
179f831b AG	175
	176	/**
	177	* ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg
	178	* @iterator: radiotap_iterator to move to next arg (if any)
	179	*
	180	* Returns: 0 if there is an argument to handle,
	181	* -ENOENT if there are no more args or -EINVAL
	182	* if there is something else wrong.
	183	*
	184	* This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*)
	185	* in @this_arg_index and sets @this_arg to point to the
	186	* payload for the field. It takes care of alignment handling and extended
	187	* present fields. @this_arg can be changed by the caller (eg,
	188	* incremented to move inside a compound argument like
	189	* IEEE80211_RADIOTAP_CHANNEL). The args pointed to are in
	190	* little-endian format whatever the endianess of your CPU.
	191	*
	192	* Alignment Gotcha:
	193	* You must take care when dereferencing iterator.this_arg
	194	* for multibyte types... the pointer is not aligned. Use
	195	* get_unaligned((type *)iterator.this_arg) to dereference
	196	* iterator.this_arg for type "type" safely on all arches.
	197	*/
	198
	199	int ieee80211_radiotap_iterator_next(
33e5a2f7	200	struct ieee80211_radiotap_iterator *iterator)
179f831b	201	{
33e5a2f7	202	while (1) {
179f831b	203	int hit = 0;
9ebad4ab	204	int pad, align, size, subns;
33e5a2f7	205	uint32_t oui;
179f831b	206
33e5a2f7 JB	207	/* if no more EXT bits, that's it */
	208	if ((iterator->_arg_index % 32) == IEEE80211_RADIOTAP_EXT &&
	209	!(iterator->_bitmap_shifter & 1))
	210	return -ENOENT;
	211
	212	if (!(iterator->_bitmap_shifter & 1))
179f831b AG	213	goto next_entry; /* arg not present */
179f831b AG	214
33e5a2f7 JB	215	/* get alignment/size of data */
	216	switch (iterator->_arg_index % 32) {
	217	case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
	218	case IEEE80211_RADIOTAP_EXT:
	219	align = 1;
	220	size = 0;
	221	break;
	222	case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
	223	align = 2;
	224	size = 6;
	225	break;
	226	default:
	227	if (!iterator->current_namespace \|\|
	228	iterator->_arg_index >= iterator->current_namespace->n_bits) {
	229	if (iterator->current_namespace == &radiotap_ns)
	230	return -ENOENT;
	231	align = 0;
	232	} else {
	233	align = iterator->current_namespace->align_size[iterator->_arg_index].align;
	234	size = iterator->current_namespace->align_size[iterator->_arg_index].size;
	235	}
	236	if (!align) {
	237	/* skip all subsequent data */
	238	iterator->_arg = iterator->_next_ns_data;
	239	/* give up on this namespace */
	240	iterator->current_namespace = NULL;
	241	goto next_entry;
	242	}
	243	break;
	244	}
	245
179f831b AG	246	/*
179f831b AG	247	* arg is present, account for alignment padding
179f831b	248	*
33e5a2f7 JB	249	* Note that these alignments are relative to the start
33e5a2f7 JB	250	* of the radiotap header. There is no guarantee
179f831b AG	251	* that the radiotap header itself is aligned on any
	252	* kind of boundary.
	253	*
33e5a2f7 JB	254	* The above is why get_unaligned() is used to dereference
33e5a2f7 JB	255	* multibyte elements from the radiotap area.
179f831b AG	256	*/
179f831b AG	257
33e5a2f7 JB	258	pad = ((unsigned long)iterator->_arg -
33e5a2f7 JB	259	(unsigned long)iterator->_rtheader) & (align - 1);
179f831b AG	260
179f831b AG	261	if (pad)
33e5a2f7	262	iterator->_arg += align - pad;
179f831b	263
9ebad4ab JB	264	if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE) {
	265	int vnslen;
	266
	267	if ((unsigned long)iterator->_arg + size -
	268	(unsigned long)iterator->_rtheader >
	269	(unsigned long)iterator->_max_length)
	270	return -EINVAL;
	271
	272	oui = (*iterator->_arg << 16) \|
	273	(*(iterator->_arg + 1) << 8) \|
	274	*(iterator->_arg + 2);
	275	subns = *(iterator->_arg + 3);
	276
	277	find_ns(iterator, oui, subns);
	278
	279	vnslen = get_unaligned_le16(iterator->_arg + 4);
	280	iterator->_next_ns_data = iterator->_arg + size + vnslen;
	281	if (!iterator->current_namespace)
	282	size += vnslen;
	283	}
	284
179f831b AG	285	/*
	286	* this is what we will return to user, but we need to
	287	* move on first so next call has something fresh to test
	288	*/
33e5a2f7 JB	289	iterator->this_arg_index = iterator->_arg_index;
	290	iterator->this_arg = iterator->_arg;
	291	iterator->this_arg_size = size;
179f831b AG	292
179f831b AG	293	/* internally move on the size of this arg */
33e5a2f7	294	iterator->_arg += size;
179f831b AG	295
	296	/*
	297	* check for insanity where we are given a bitmap that
	298	* claims to have more arg content than the length of the
	299	* radiotap section. We will normally end up equalling this
	300	* max_length on the last arg, never exceeding it.
	301	*/
	302
33e5a2f7 JB	303	if ((unsigned long)iterator->_arg -
	304	(unsigned long)iterator->_rtheader >
	305	(unsigned long)iterator->_max_length)
179f831b AG	306	return -EINVAL;
179f831b AG	307
33e5a2f7 JB	308	/* these special ones are valid in each bitmap word */
	309	switch (iterator->_arg_index % 32) {
	310	case IEEE80211_RADIOTAP_VENDOR_NAMESPACE:
33e5a2f7 JB	311	iterator->_reset_on_ext = 1;
33e5a2f7 JB	312
33e5a2f7	313	iterator->is_radiotap_ns = 0;
9ebad4ab JB	314	/*
	315	* If parser didn't register this vendor
	316	* namespace with us, allow it to show it
	317	* as 'raw. Do do that, set argument index
	318	* to vendor namespace.
	319	*/
33e5a2f7 JB	320	iterator->this_arg_index =
33e5a2f7 JB	321	IEEE80211_RADIOTAP_VENDOR_NAMESPACE;
9ebad4ab JB	322	if (!iterator->current_namespace)
	323	hit = 1;
	324	goto next_entry;
33e5a2f7	325	case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE:
33e5a2f7 JB	326	iterator->_reset_on_ext = 1;
	327	iterator->current_namespace = &radiotap_ns;
	328	iterator->is_radiotap_ns = 1;
9ebad4ab	329	goto next_entry;
33e5a2f7 JB	330	case IEEE80211_RADIOTAP_EXT:
	331	/*
	332	* bit 31 was set, there is more
	333	* -- move to next u32 bitmap
	334	*/
	335	iterator->_bitmap_shifter =
	336	get_unaligned_le32(iterator->_next_bitmap);
	337	iterator->_next_bitmap++;
	338	if (iterator->_reset_on_ext)
	339	iterator->_arg_index = 0;
	340	else
	341	iterator->_arg_index++;
	342	iterator->_reset_on_ext = 0;
	343	break;
	344	default:
	345	/* we've got a hit! */
	346	hit = 1;
	347	next_entry:
	348	iterator->_bitmap_shifter >>= 1;
	349	iterator->_arg_index++;
	350	}
179f831b AG	351
	352	/* if we found a valid arg earlier, return it now */
	353	if (hit)
	354	return 0;
	355	}
179f831b AG	356	}
179f831b AG	357	EXPORT_SYMBOL(ieee80211_radiotap_iterator_next);