Revert "TODO epan/dissectors/asn1/kerberos/packet-kerberos-template.c new GSS flags"

[wireshark-sm.git] / epan / dissectors / packet-ieee80211-radiotap-iter.c

/*
 * 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      pletoh16
#define get_unaligned_le32      pletoh32

#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:
 */