radiotap.c

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/* Copyright 2021 The libwifi Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#include "radiotap.h"
#include "../../core/radiotap/radiotap_iter.h"
 
#include <errno.h>
#include <endian.h>
#include <stdint.h>
 
int libwifi_parse_radiotap_info(struct libwifi_radiotap_info *info, const unsigned char *frame, size_t frame_len) {
    memset(info, 0, sizeof(struct libwifi_radiotap_info));
 
    if (frame_len < sizeof(struct ieee80211_radiotap_header)) {
        return -EINVAL;
    }
 
    struct ieee80211_radiotap_header *rh = (struct ieee80211_radiotap_header *) frame;
    struct ieee80211_radiotap_iterator it = {0};
    int ret = ieee80211_radiotap_iterator_init(&it, (void *) frame, rh->it_len, NULL);
 
    int skipped_antenna = 0;
    info->length = rh->it_len;
 
    while (!ret) {
        switch (it.this_arg_index) {
            case IEEE80211_RADIOTAP_CHANNEL:
                info->channel.freq = le16toh(*(uint16_t *) it.this_arg);
                info->channel.flags = le16toh(*(uint16_t *) (it.this_arg + 2));
                break;
            case IEEE80211_RADIOTAP_RATE:
                info->rate_raw = *it.this_arg;
                info->rate = (*it.this_arg / 2.0);
                break;
            case IEEE80211_RADIOTAP_DBM_ANTSIGNAL:
                // Radiotap Headers will include the ANTSIGNAL without an explicit Antenna definition.
                if (!skipped_antenna) {
                    info->signal = *it.this_arg;
                    skipped_antenna = 1;
                    break;
                }
 
                if (info->antenna_count < LIBWIFI_MAX_RADIOTAP_ANTENNAS) {
                    struct libwifi_radiotap_antenna antenna = {.antenna_number = info->antenna_count,
                                                               .signal = *it.this_arg};
                    info->antennas[info->antenna_count] = antenna;
                    info->antenna_count += 1;
                }
                break;
            case IEEE80211_RADIOTAP_ANTENNA:
                info->antennas[info->antenna_count - 1].antenna_number = *it.this_arg;
                break;
            case IEEE80211_RADIOTAP_DBM_ANTNOISE:
                break;
            case IEEE80211_RADIOTAP_FLAGS:
                info->flags = *it.this_arg;
                break;
            case IEEE80211_RADIOTAP_EXT:
                info->extended_flags = *it.this_arg;
                break;
            case IEEE80211_RADIOTAP_RX_FLAGS:
                info->rx_flags = *it.this_arg;
                break;
            case IEEE80211_RADIOTAP_TX_FLAGS:
                info->tx_flags = *it.this_arg;
                break;
            case IEEE80211_RADIOTAP_MCS:
                info->mcs.known = *(uint8_t *) it.this_arg;
                info->mcs.flags = *(uint8_t *) (it.this_arg + 2);
                info->mcs.mcs = *(uint8_t *) (it.this_arg + 3);
                break;
            case IEEE80211_RADIOTAP_DBM_TX_POWER:
                info->tx_power = *it.this_arg;
                break;
            case IEEE80211_RADIOTAP_TIMESTAMP:
                info->timestamp.timestamp = le64toh(*(uint64_t *) it.this_arg);
                info->timestamp.accuracy = le16toh(*(uint16_t *) (it.this_arg + 2));
                info->timestamp.unit = *(uint8_t *) (it.this_arg + 3);
                info->timestamp.flags = *(uint8_t *) (it.this_arg + 4);
                break;
            case IEEE80211_RADIOTAP_RTS_RETRIES:
                info->rts_retries = *it.this_arg;
                break;
            case IEEE80211_RADIOTAP_DATA_RETRIES:
                info->data_retries = *it.this_arg;
                break;
        }
 
        ret = ieee80211_radiotap_iterator_next(&it);
    }
 
    return 0;
}
 
int8_t libwifi_parse_radiotap_rssi(const unsigned char *frame) {
    struct ieee80211_radiotap_header *rh = (struct ieee80211_radiotap_header *) frame;
 
    int8_t rssi = 0;
 
    struct ieee80211_radiotap_iterator it;
    int ret = ieee80211_radiotap_iterator_init(&it, (void *) frame, rh->it_len, NULL);
 
    while (!ret) {
        if (it.this_arg_index == IEEE80211_RADIOTAP_DBM_ANTSIGNAL) {
            rssi = *it.this_arg;
            break;
        }
 
        ret = ieee80211_radiotap_iterator_next(&it);
    }
 
    return rssi;
}