/*

 * Radiotap parser

 *

 * Copyright 2007   Andy Green <andy@warmcat.com>

 * Copyright 2009   Johannes Berg <johannes@sipsolutions.net>

 *

 * SPDX-License-Identifier: (ISC OR GPL-2.0-only)

 */

#include "config.h"

#include <errno.h>

#include <epan/packet.h>

#include <wsutil/pint.h>

#include <wsutil/array.h>

#define le16_to_cpu   GINT16_FROM_LE

#define le32_to_cpu   GINT32_FROM_LE

#define get_unaligned_le16  pletohu16

#define get_unaligned_le32  pletohu32

#include "packet-ieee80211-radiotap-iter.h"

/* function prototypes and related defs are in radiotap_iter.h */

static const struct radiotap_align_size rtap_namespace_sizes[] = {

  /* [IEEE80211_RADIOTAP_TSFT] = 0 */     { 8, 8 },

  /* [IEEE80211_RADIOTAP_FLAGS] = 1 */      { 1, 1 },

  /* [IEEE80211_RADIOTAP_RATE] = 2 */     { 1, 1 },

  /* [IEEE80211_RADIOTAP_CHANNEL] = 3 */      { 2, 4 },

  /* [IEEE80211_RADIOTAP_FHSS] = 4 */     { 2, 2 },

  /* [IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = 5 */    { 1, 1 },

  /* [IEEE80211_RADIOTAP_DBM_ANTNOISE] = 6 */   { 1, 1 },

  /* [IEEE80211_RADIOTAP_LOCK_QUALITY] = 7 */   { 2, 2 },

  /* [IEEE80211_RADIOTAP_TX_ATTENUATION] = 8 */   { 2, 2 },

  /* [IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = 9 */  { 2, 2 },

  /* [IEEE80211_RADIOTAP_DBM_TX_POWER] = 10 */    { 1, 1 },

  /* [IEEE80211_RADIOTAP_ANTENNA] = 11 */     { 1, 1 },

  /* [IEEE80211_RADIOTAP_DB_ANTSIGNAL] = 12 */    { 1, 1 },

  /* [IEEE80211_RADIOTAP_DB_ANTNOISE] = 13 */   { 1, 1 },

  /* [IEEE80211_RADIOTAP_RX_FLAGS] = 14 */    { 2, 2 },

  /* [IEEE80211_RADIOTAP_TX_FLAGS] = 15 */    { 2, 2 },

  /* [IEEE80211_RADIOTAP_RTS_RETRIES] = 16 */   { 1, 1 },

  /* [IEEE80211_RADIOTAP_DATA_RETRIES] = 17 */    { 1, 1 },

  /* [IEEE80211_RADIOTAP_XCHANNEL] = 18 */    { 0, 0 }, /* Unofficial, used by FreeBSD */

  /* [IEEE80211_RADIOTAP_MCS] = 19 */     { 1, 3 },

  /* [IEEE80211_RADIOTAP_AMPDU_STATUS] = 20 */    { 4, 8 },

  /* [IEEE80211_RADIOTAP_VHT] = 21 */     { 2, 12 },

  /* [IEEE80211_RADIOTAP_TIMESTAMP] = 22 */   { 8, 12 },

  /* [IEEE80211_RADIOTAP_HE] = 23 */      { 2, 12 },

  /* [IEEE80211_RADIOTAP_HE_MU] = 24 */     { 2, 12 },

  /* [IEEE80211_RADIOTAP_HE_MU_USER = 25 notdef */  { 0, 0 },

  /* [IEEE80211_RADIOTAP_0_LENGTH_PSDU = 26 */    { 1, 1 },

  /* [IEEE80211_RADIOTAP_L_SIG = 27 */      { 2, 4 },

  /* [IEEE80211_RADIOTAP_TLV = 28 */                      { 4, 10 },

  /*

   * add more here as they are defined in

   * include/net/ieee80211_radiotap.h

   */

};

static const struct ieee80211_radiotap_namespace radiotap_ns = {

  rtap_namespace_sizes,

  (int)array_length(rtap_namespace_sizes),

  0,

  0

};

/*

 * Sanity check.

 */

#define ITERATOR_VALID(iterator, size) \

    (((iterator)->_arg + (size) - (unsigned char *)((iterator)->_rtheader)) <= \

        (ptrdiff_t)(iterator)->_max_length)

/**

 * 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 https://www.kernel.org/doc/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)

{

  /* XXX - in Wireshark, we've already checked for this */

  if (max_length < (int)sizeof(struct ieee80211_radiotap_header))

    return -EINVAL;

  /* Linux only supports version 0 radiotap format */

  /* XXX - this is Wireshark, not Linux, and we should report an expert info */

  if (radiotap_header->it_version)

    return -EINVAL;

  /* sanity check for allowed length and radiotap length field */

  /* XXX - in Wireshark, this compares the length against itself. */

  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_ns_data = NULL;

  iterator->_next_bitmap = &radiotap_header->it_present;

  iterator->_next_bitmap++;

  iterator->_vns = vns;

  iterator->current_namespace = &radiotap_ns;

  iterator->is_radiotap_ns = 1;

  iterator->tlv_mode = 0;

#ifdef RADIOTAP_SUPPORT_OVERRIDES

  iterator->n_overrides = 0;

  iterator->overrides = NULL;

#endif

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

  if (iterator->_bitmap_shifter & (1U << IEEE80211_RADIOTAP_EXT)) {

    /* XXX - we should report an expert info here */

    if (!ITERATOR_VALID(iterator, sizeof(uint32_t)))

      return -EINVAL;

    while (get_unaligned_le32(iterator->_arg) &

          (1U << 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

       */

      /* XXX - we should report an expert info here */

      if (!ITERATOR_VALID(iterator, sizeof(uint32_t)))

        return -EINVAL;

      /* XXX - we should report an expert info here */

      if ((get_unaligned_le32(iterator->_arg) &

          (1U << IEEE80211_RADIOTAP_TLVS)) &&

          (get_unaligned_le32(iterator->_arg) &

          (1U << IEEE80211_RADIOTAP_EXT)))

        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;

}

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;

  }

}

#ifdef RADIOTAP_SUPPORT_OVERRIDES

static int find_override(struct ieee80211_radiotap_iterator *iterator,

       int *align, int *size)

{

  int i;

  if (!iterator->overrides)

    return 0;

  for (i = 0; i < iterator->n_overrides; i++) {

    if (iterator->_arg_index == iterator->overrides[i].field) {

      *align = iterator->overrides[i].align;

      *size = iterator->overrides[i].size;

      if (!*align) /* erroneous override */

        return 0;

      return 1;

    }

  }

  return 0;

}

#endif

/**

 * 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)

{

  if (iterator->tlv_mode) {

    struct ieee80211_radiotap_tlv *tlv;

    uint32_t size;

#define TLV_LEN_ALIGN(x) ((x + 3) & ~3)

    size = sizeof(*tlv) + TLV_LEN_ALIGN(iterator->this_arg_size);

    /*

     * We know that without the alignment padding it was valid, so

     * ignore arbitrary padding and return that we finished if no

     * further TLV could fit.

     */

    if (!ITERATOR_VALID(iterator, size))

      return -ENOENT;

    /* move to next entry */

    iterator->_arg += sizeof(*tlv) + TLV_LEN_ALIGN(iterator->this_arg_size);

return_tlv:

    /* and check again if we reached the end */

    if (!ITERATOR_VALID(iterator, 1))

      return -ENOENT;

    /* if it's not the end but a new TLV won't fit - error out */

    if (!ITERATOR_VALID(iterator, sizeof(*tlv)))

      return -EINVAL;

    tlv = (struct ieee80211_radiotap_tlv *)iterator->_arg;

    iterator->this_arg_index = get_unaligned_le16(&tlv->type);

    iterator->this_arg_size = get_unaligned_le16(&tlv->datalen);

    iterator->this_arg = tlv->data;

    iterator->is_radiotap_ns =

      iterator->this_arg_index != IEEE80211_RADIOTAP_VENDOR_NAMESPACE;

    if (!ITERATOR_VALID(iterator, sizeof(*tlv) + iterator->this_arg_size))

      return -EINVAL;

    return 0;

  }

  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_TLVS:

      align = 4;

      size = 0;

      break;

    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:

#ifdef RADIOTAP_SUPPORT_OVERRIDES

      if (find_override(iterator, &align, &size)) {

        /* all set */

      } else

#endif

      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 */

        int skip_size = IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE - (iterator->_arg_index % 32);

        /* XXX - we should report an expert info here */

        if (!iterator->_next_ns_data)

          return -EINVAL;

        iterator->_arg = iterator->_next_ns_data;

        /* give up on this namespace */

        iterator->current_namespace = NULL;

        iterator->_next_ns_data = NULL;

        // Remove 1 because jump to next_entry will also shift bitmap by 1

        iterator->_bitmap_shifter >>= skip_size - 1;

        iterator->_arg_index += skip_size - 1;

        /* XXX - we should report an expert info here */

        if (!ITERATOR_VALID(iterator, 0))

          return -EINVAL;

        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 = (int)((iterator->_arg - (unsigned char *)iterator->_rtheader) & (align - 1));

    if (pad)

      iterator->_arg += align - pad;

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

      int vnslen;

      /* XXX - we should report an expert info here */

      if (!ITERATOR_VALID(iterator, size))

        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;

    } else if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_TLVS) {

      iterator->tlv_mode = 1;

      goto return_tlv;

    }

    /*

     * 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.

     */

    /* XXX - we should report an expert info here */

    if (!ITERATOR_VALID(iterator, 0))

      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;

  }

}

/*

 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html

 *

 * Local variables:

 * c-basic-offset: 8

 * tab-width: 8

 * indent-tabs-mode: t

 * End:

 *

 * vi: set shiftwidth=8 tabstop=8 noexpandtab:

 * :indentSize=8:tabSize=8:noTabs=false:

 */