4 * Copyright 2007 Andy Green <andy@warmcat.com>
5 * Copyright 2009 Johannes Berg <johannes@sipsolutions.net>
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.
11 * Alternatively, this software may be distributed under the terms of BSD
14 * See COPYING for more details.
16 #include "radiotap_iter.h"
19 /* function prototypes and related defs are in radiotap_iter.h */
21 static const struct radiotap_align_size rtap_namespace_sizes
[] = {
22 [IEEE80211_RADIOTAP_TSFT
] = { .align
= 8, .size
= 8, },
23 [IEEE80211_RADIOTAP_FLAGS
] = { .align
= 1, .size
= 1, },
24 [IEEE80211_RADIOTAP_RATE
] = { .align
= 1, .size
= 1, },
25 [IEEE80211_RADIOTAP_CHANNEL
] = { .align
= 2, .size
= 4, },
26 [IEEE80211_RADIOTAP_FHSS
] = { .align
= 2, .size
= 2, },
27 [IEEE80211_RADIOTAP_DBM_ANTSIGNAL
] = { .align
= 1, .size
= 1, },
28 [IEEE80211_RADIOTAP_DBM_ANTNOISE
] = { .align
= 1, .size
= 1, },
29 [IEEE80211_RADIOTAP_LOCK_QUALITY
] = { .align
= 2, .size
= 2, },
30 [IEEE80211_RADIOTAP_TX_ATTENUATION
] = { .align
= 2, .size
= 2, },
31 [IEEE80211_RADIOTAP_DB_TX_ATTENUATION
] = { .align
= 2, .size
= 2, },
32 [IEEE80211_RADIOTAP_DBM_TX_POWER
] = { .align
= 1, .size
= 1, },
33 [IEEE80211_RADIOTAP_ANTENNA
] = { .align
= 1, .size
= 1, },
34 [IEEE80211_RADIOTAP_DB_ANTSIGNAL
] = { .align
= 1, .size
= 1, },
35 [IEEE80211_RADIOTAP_DB_ANTNOISE
] = { .align
= 1, .size
= 1, },
36 [IEEE80211_RADIOTAP_RX_FLAGS
] = { .align
= 2, .size
= 2, },
37 [IEEE80211_RADIOTAP_TX_FLAGS
] = { .align
= 2, .size
= 2, },
38 [IEEE80211_RADIOTAP_RTS_RETRIES
] = { .align
= 1, .size
= 1, },
39 [IEEE80211_RADIOTAP_DATA_RETRIES
] = { .align
= 1, .size
= 1, },
40 [IEEE80211_RADIOTAP_MCS
] = { .align
= 1, .size
= 3, },
41 [IEEE80211_RADIOTAP_AMPDU_STATUS
] = { .align
= 4, .size
= 8, },
43 * add more here as they are defined in radiotap.h
47 static const struct ieee80211_radiotap_namespace radiotap_ns
= {
48 .n_bits
= sizeof(rtap_namespace_sizes
) / sizeof(rtap_namespace_sizes
[0]),
49 .align_size
= rtap_namespace_sizes
,
53 * ieee80211_radiotap_iterator_init - radiotap parser iterator initialization
54 * @iterator: radiotap_iterator to initialize
55 * @radiotap_header: radiotap header to parse
56 * @max_length: total length we can parse into (eg, whole packet length)
58 * Returns: 0 or a negative error code if there is a problem.
60 * This function initializes an opaque iterator struct which can then
61 * be passed to ieee80211_radiotap_iterator_next() to visit every radiotap
62 * argument which is present in the header. It knows about extended
63 * present headers and handles them.
66 * call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator
67 * struct ieee80211_radiotap_iterator (no need to init the struct beforehand)
68 * checking for a good 0 return code. Then loop calling
69 * __ieee80211_radiotap_iterator_next()... it returns either 0,
70 * -ENOENT if there are no more args to parse, or -EINVAL if there is a problem.
71 * The iterator's @this_arg member points to the start of the argument
72 * associated with the current argument index that is present, which can be
73 * found in the iterator's @this_arg_index member. This arg index corresponds
74 * to the IEEE80211_RADIOTAP_... defines.
76 * Radiotap header length:
77 * You can find the CPU-endian total radiotap header length in
78 * iterator->max_length after executing ieee80211_radiotap_iterator_init()
82 * You must take care when dereferencing iterator.this_arg
83 * for multibyte types... the pointer is not aligned. Use
84 * get_unaligned((type *)iterator.this_arg) to dereference
85 * iterator.this_arg for type "type" safely on all arches.
87 * Example code: parse.c
90 int ieee80211_radiotap_iterator_init(
91 struct ieee80211_radiotap_iterator
*iterator
,
92 struct ieee80211_radiotap_header
*radiotap_header
,
93 int max_length
, const struct ieee80211_radiotap_vendor_namespaces
*vns
)
95 /* must at least have the radiotap header */
96 if (max_length
< (int)sizeof(struct ieee80211_radiotap_header
))
99 /* Linux only supports version 0 radiotap format */
100 if (radiotap_header
->it_version
)
103 /* sanity check for allowed length and radiotap length field */
104 if (max_length
< get_unaligned_le16(&radiotap_header
->it_len
))
107 iterator
->_rtheader
= radiotap_header
;
108 iterator
->_max_length
= get_unaligned_le16(&radiotap_header
->it_len
);
109 iterator
->_arg_index
= 0;
110 iterator
->_bitmap_shifter
= get_unaligned_le32(&radiotap_header
->it_present
);
111 iterator
->_arg
= (uint8_t *)radiotap_header
+ sizeof(*radiotap_header
);
112 iterator
->_next_ns_data
= NULL
;
113 iterator
->_reset_on_ext
= 0;
114 iterator
->_next_bitmap
= &radiotap_header
->it_present
;
115 iterator
->_next_bitmap
++;
116 iterator
->_vns
= vns
;
117 iterator
->current_namespace
= &radiotap_ns
;
118 iterator
->is_radiotap_ns
= 1;
119 #ifdef RADIOTAP_SUPPORT_OVERRIDES
120 iterator
->n_overrides
= 0;
121 iterator
->overrides
= NULL
;
124 /* find payload start allowing for extended bitmap(s) */
126 if (iterator
->_bitmap_shifter
& BIT(IEEE80211_RADIOTAP_EXT
)) {
127 if ((unsigned long)iterator
->_arg
-
128 (unsigned long)iterator
->_rtheader
+ sizeof(uint32_t) >
129 (unsigned long)iterator
->_max_length
)
131 while (get_unaligned_le32(iterator
->_arg
) &
132 BIT(IEEE80211_RADIOTAP_EXT
)) {
133 iterator
->_arg
+= sizeof(uint32_t);
136 * check for insanity where the present bitmaps
137 * keep claiming to extend up to or even beyond the
138 * stated radiotap header length
141 if ((unsigned long)iterator
->_arg
-
142 (unsigned long)iterator
->_rtheader
+
144 (unsigned long)iterator
->_max_length
)
148 iterator
->_arg
+= sizeof(uint32_t);
151 * no need to check again for blowing past stated radiotap
152 * header length, because ieee80211_radiotap_iterator_next
153 * checks it before it is dereferenced
157 iterator
->this_arg
= iterator
->_arg
;
158 iterator
->this_arg_index
= 0;
159 iterator
->this_arg_size
= 0;
161 /* we are all initialized happily */
166 static void find_ns(struct ieee80211_radiotap_iterator
*iterator
,
167 uint32_t oui
, uint8_t subns
)
171 iterator
->current_namespace
= NULL
;
176 for (i
= 0; i
< iterator
->_vns
->n_ns
; i
++) {
177 if (iterator
->_vns
->ns
[i
].oui
!= oui
)
179 if (iterator
->_vns
->ns
[i
].subns
!= subns
)
182 iterator
->current_namespace
= &iterator
->_vns
->ns
[i
];
187 #ifdef RADIOTAP_SUPPORT_OVERRIDES
188 static int find_override(struct ieee80211_radiotap_iterator
*iterator
,
189 int *align
, int *size
)
193 if (!iterator
->overrides
)
196 for (i
= 0; i
< iterator
->n_overrides
; i
++) {
197 if (iterator
->_arg_index
== iterator
->overrides
[i
].field
) {
198 *align
= iterator
->overrides
[i
].align
;
199 *size
= iterator
->overrides
[i
].size
;
200 if (!*align
) /* erroneous override */
212 * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg
213 * @iterator: radiotap_iterator to move to next arg (if any)
215 * Returns: 0 if there is an argument to handle,
216 * -ENOENT if there are no more args or -EINVAL
217 * if there is something else wrong.
219 * This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*)
220 * in @this_arg_index and sets @this_arg to point to the
221 * payload for the field. It takes care of alignment handling and extended
222 * present fields. @this_arg can be changed by the caller (eg,
223 * incremented to move inside a compound argument like
224 * IEEE80211_RADIOTAP_CHANNEL). The args pointed to are in
225 * little-endian format whatever the endianess of your CPU.
228 * You must take care when dereferencing iterator.this_arg
229 * for multibyte types... the pointer is not aligned. Use
230 * get_unaligned((type *)iterator.this_arg) to dereference
231 * iterator.this_arg for type "type" safely on all arches.
234 int ieee80211_radiotap_iterator_next(
235 struct ieee80211_radiotap_iterator
*iterator
)
239 int pad
, align
, size
, subns
;
242 /* if no more EXT bits, that's it */
243 if ((iterator
->_arg_index
% 32) == IEEE80211_RADIOTAP_EXT
&&
244 !(iterator
->_bitmap_shifter
& 1))
247 if (!(iterator
->_bitmap_shifter
& 1))
248 goto next_entry
; /* arg not present */
250 /* get alignment/size of data */
251 switch (iterator
->_arg_index
% 32) {
252 case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE
:
253 case IEEE80211_RADIOTAP_EXT
:
257 case IEEE80211_RADIOTAP_VENDOR_NAMESPACE
:
262 #ifdef RADIOTAP_SUPPORT_OVERRIDES
263 if (find_override(iterator
, &align
, &size
)) {
267 if (!iterator
->current_namespace
||
268 iterator
->_arg_index
>= iterator
->current_namespace
->n_bits
) {
269 if (iterator
->current_namespace
== &radiotap_ns
)
273 align
= iterator
->current_namespace
->align_size
[iterator
->_arg_index
].align
;
274 size
= iterator
->current_namespace
->align_size
[iterator
->_arg_index
].size
;
277 /* skip all subsequent data */
278 iterator
->_arg
= iterator
->_next_ns_data
;
279 /* give up on this namespace */
280 iterator
->current_namespace
= NULL
;
287 * arg is present, account for alignment padding
289 * Note that these alignments are relative to the start
290 * of the radiotap header. There is no guarantee
291 * that the radiotap header itself is aligned on any
294 * The above is why get_unaligned() is used to dereference
295 * multibyte elements from the radiotap area.
298 pad
= ((unsigned long)iterator
->_arg
-
299 (unsigned long)iterator
->_rtheader
) & (align
- 1);
302 iterator
->_arg
+= align
- pad
;
304 if (iterator
->_arg_index
% 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE
) {
307 if ((unsigned long)iterator
->_arg
+ size
-
308 (unsigned long)iterator
->_rtheader
>
309 (unsigned long)iterator
->_max_length
)
312 oui
= (*iterator
->_arg
<< 16) |
313 (*(iterator
->_arg
+ 1) << 8) |
314 *(iterator
->_arg
+ 2);
315 subns
= *(iterator
->_arg
+ 3);
317 find_ns(iterator
, oui
, subns
);
319 vnslen
= get_unaligned_le16(iterator
->_arg
+ 4);
320 iterator
->_next_ns_data
= iterator
->_arg
+ size
+ vnslen
;
321 if (!iterator
->current_namespace
)
326 * this is what we will return to user, but we need to
327 * move on first so next call has something fresh to test
329 iterator
->this_arg_index
= iterator
->_arg_index
;
330 iterator
->this_arg
= iterator
->_arg
;
331 iterator
->this_arg_size
= size
;
333 /* internally move on the size of this arg */
334 iterator
->_arg
+= size
;
337 * check for insanity where we are given a bitmap that
338 * claims to have more arg content than the length of the
339 * radiotap section. We will normally end up equalling this
340 * max_length on the last arg, never exceeding it.
343 if ((unsigned long)iterator
->_arg
-
344 (unsigned long)iterator
->_rtheader
>
345 (unsigned long)iterator
->_max_length
)
348 /* these special ones are valid in each bitmap word */
349 switch (iterator
->_arg_index
% 32) {
350 case IEEE80211_RADIOTAP_VENDOR_NAMESPACE
:
351 iterator
->_reset_on_ext
= 1;
353 iterator
->is_radiotap_ns
= 0;
355 * If parser didn't register this vendor
356 * namespace with us, allow it to show it
357 * as 'raw. Do do that, set argument index
358 * to vendor namespace.
360 iterator
->this_arg_index
=
361 IEEE80211_RADIOTAP_VENDOR_NAMESPACE
;
362 if (!iterator
->current_namespace
)
365 case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE
:
366 iterator
->_reset_on_ext
= 1;
367 iterator
->current_namespace
= &radiotap_ns
;
368 iterator
->is_radiotap_ns
= 1;
370 case IEEE80211_RADIOTAP_EXT
:
372 * bit 31 was set, there is more
373 * -- move to next u32 bitmap
375 iterator
->_bitmap_shifter
=
376 get_unaligned_le32(iterator
->_next_bitmap
);
377 iterator
->_next_bitmap
++;
378 if (iterator
->_reset_on_ext
)
379 iterator
->_arg_index
= 0;
381 iterator
->_arg_index
++;
382 iterator
->_reset_on_ext
= 0;
385 /* we've got a hit! */
388 iterator
->_bitmap_shifter
>>= 1;
389 iterator
->_arg_index
++;
392 /* if we found a valid arg earlier, return it now */