epan/dissectors/packet-ieee80211-radiotap-iter.h

   1 /*
   2  * Radiotap parser
   3  *
   4  * Copyright 2007               Andy Green <andy@warmcat.com>
   5  * Copyright 2009               Johannes Berg <johannes@sipsolutions.net>
   6  *
   7  * SPDX-License-Identifier: (ISC OR GPL-2.0-only)
   8  */
   9
  10 #ifndef __RADIOTAP_ITER_H
  11 #define __RADIOTAP_ITER_H
  12
  13 #define RADIOTAP_SUPPORT_OVERRIDES
  14
  15 #include "packet-ieee80211-radiotap-defs.h"
  16
  17 /* Radiotap header iteration
  18  *   implemented in radiotap.c
  19  */
  20
  21 struct radiotap_override {
  22         uint8_t field;
  23         unsigned align:4, size:4;
  24 };
  25
  26 struct radiotap_align_size {
  27         unsigned align:4, size:4;
  28 };
  29
  30 struct ieee80211_radiotap_namespace {
  31         const struct radiotap_align_size *align_size;
  32         int n_bits;
  33         uint32_t oui;
  34         uint8_t subns;
  35 };
  36
  37 struct ieee80211_radiotap_vendor_namespaces {
  38         const struct ieee80211_radiotap_namespace *ns;
  39         int n_ns;
  40 };
  41
  42 /**
  43  * struct ieee80211_radiotap_iterator - tracks walk thru present radiotap args
  44  *
  45  * Describes the radiotap parser state. Fields prefixed with an underscore
  46  * must not be used by users of the parser, only by the parser internally.
  47  */
  48
  49 struct ieee80211_radiotap_iterator {
  50         struct ieee80211_radiotap_header *_rtheader;                            /**< pointer to the radiotap header we are walking through */
  51         const struct ieee80211_radiotap_vendor_namespaces *_vns;                /**< vendor namespace definitions*/
  52         const struct ieee80211_radiotap_namespace *current_namespace;           /**< pointer to the current namespace definition (or internally
  53                                                                                         %NULL if the current namespace is unknown)*/
  54
  55         unsigned char *_arg, *_next_ns_data;                                    /**< beginning of the next namespace's data */
  56         uint32_t *_next_bitmap;                                                 /**< internal pointer to next present u32 */
  57
  58         unsigned char *this_arg;                                                /**< pointer to current radiotap arg; it is valid after each call
  59                                                                                         to ieee80211_radiotap_iterator_next() but also after
  60                                                                                         ieee80211_radiotap_iterator_init() where it will point to
  61                                                                                         the beginning of the actual data portion */
  62 #ifdef RADIOTAP_SUPPORT_OVERRIDES
  63         const struct radiotap_override *overrides;                              /**< override standard radiotap fields */
  64         int n_overrides;                                                        /**< number of overrides */
  65 #endif
  66         int this_arg_index;                                                     /**< index of current arg, valid after each successful call to
  67                                                                                 ieee80211_radiotap_iterator_next() */
  68         int this_arg_size;                                                      /**< length of the current arg, for convenience*/
  69
  70         int is_radiotap_ns;
  71         int tlv_mode;
  72
  73         int _max_length;                                                        /**< length of radiotap header in cpu byte ordering */
  74         int _arg_index;                                                         /**< next argument index */
  75         uint32_t _bitmap_shifter;                                               /**< internal shifter for curr u32 bitmap, b0 set == arg present */
  76         int _reset_on_ext;                                                      /**< internal; reset the arg index to 0 when going to the next bitmap word */
  77 };
  78
  79 extern int ieee80211_radiotap_iterator_init(
  80         struct ieee80211_radiotap_iterator *iterator,
  81         struct ieee80211_radiotap_header *radiotap_header,
  82         int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns);
  83
  84 extern int ieee80211_radiotap_iterator_next(
  85         struct ieee80211_radiotap_iterator *iterator);
  86
  87 #endif /* __RADIOTAP_ITER_H */