ESP32-PaxCounter/src/macsniff.cpp

// Basic Config
#include "globals.h"

#ifdef VENDORFILTER
#include "vendor_array.h"
#endif

// Local logging tag
static const char TAG[] = "wifi";

static wifi_country_t wifi_country = {WIFI_MY_COUNTRY, WIFI_CHANNEL_MIN,
                                      WIFI_CHANNEL_MAX, 0,
                                      WIFI_COUNTRY_POLICY_MANUAL};

// globals
uint16_t salt;

uint16_t reset_salt(void) {
  salt = random(65536); // get new 16bit random for salting hashes
  return salt;
}

bool mac_add(uint8_t *paddr, int8_t rssi, bool sniff_type) {

  char buff[16]; // temporary buffer for printf
  bool added = false;
  uint32_t addr2int, vendor2int; // temporary buffer for MAC and Vendor OUI
  uint16_t hashedmac;            // temporary buffer for generated hash value

  // only last 3 MAC Address bytes are used for MAC address anonymization
  // but since it's uint32 we take 4 bytes to avoid 1st value to be 0
  addr2int = ((uint32_t)paddr[2]) | ((uint32_t)paddr[3] << 8) |
             ((uint32_t)paddr[4] << 16) | ((uint32_t)paddr[5] << 24);

#ifdef VENDORFILTER
  vendor2int = ((uint32_t)paddr[2]) | ((uint32_t)paddr[1] << 8) |
               ((uint32_t)paddr[0] << 16);
  // use OUI vendor filter list only on Wifi, not on BLE
  if ((sniff_type == MAC_SNIFF_BLE) ||
      std::find(vendors.begin(), vendors.end(), vendor2int) != vendors.end()) {
#endif

    // salt and hash MAC, and if new unique one, store identifier in container
    // and increment counter on display
    // https://en.wikipedia.org/wiki/MAC_Address_Anonymization

    addr2int += (uint32_t)salt; // add 16-bit salt to pseudo MAC
    snprintf(
        buff, sizeof(buff), "%08X",
        addr2int); // convert unsigned 32-bit salted MAC to 8 digit hex string
    hashedmac = rokkit(&buff[3], 5); // hash MAC last string value, use 5 chars
                                     // to fit hash in uint16_t container
    auto newmac = macs.insert(hashedmac); // add hashed MAC, if new unique
    added = newmac.second ? true
                          : false; // true if hashed MAC is unique in container

    // Count only if MAC was not yet seen
    if (added) {
      // increment counter and one blink led
      if (sniff_type == MAC_SNIFF_WIFI) {
        macs_wifi++; // increment Wifi MACs counter
#if (HAS_LED != NOT_A_PIN) || defined(HAS_RGB_LED)
        blink_LED(COLOR_GREEN, 50);
#endif
      }
#ifdef BLECOUNTER
      else if (sniff_type == MAC_SNIFF_BLE) {
        macs_ble++; // increment BLE Macs counter
#if (HAS_LED != NOT_A_PIN) || defined(HAS_RGB_LED)
        blink_LED(COLOR_MAGENTA, 50);
#endif
      }
#endif
    }

    // Log scan result
    ESP_LOGD(TAG,
             "%s %s RSSI %ddBi -> MAC %s -> Hash %04X -> WiFi:%d  BLTH:%d -> "
             "%d Bytes left",
             added ? "new  " : "known",
             sniff_type == MAC_SNIFF_WIFI ? "WiFi" : "BLTH", rssi, buff,
             hashedmac, macs_wifi, macs_ble, ESP.getFreeHeap());

#ifdef VENDORFILTER
  } else {
    // Very noisy
    // ESP_LOGD(TAG, "Filtered MAC %02X:%02X:%02X:%02X:%02X:%02X",
    // paddr[0],paddr[1],paddr[2],paddr[3],paddr[5],paddr[5]);
  }
#endif

  // True if MAC WiFi/BLE was new
  return added; // function returns bool if a new and unique Wifi or BLE mac was
                // counted (true) or not (false)
}

void wifi_sniffer_init(void) {
  wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
  cfg.nvs_enable = 0; // we don't need any wifi settings from NVRAM
  wifi_promiscuous_filter_t filter = {
      .filter_mask = WIFI_PROMIS_FILTER_MASK_MGMT}; // we need only MGMT frames
  ESP_ERROR_CHECK(esp_wifi_init(&cfg));             // configure Wifi with cfg
  ESP_ERROR_CHECK(
      esp_wifi_set_country(&wifi_country)); // set locales for RF and channels
  ESP_ERROR_CHECK(
      esp_wifi_set_storage(WIFI_STORAGE_RAM)); // we don't need NVRAM
  ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_NULL));
  ESP_ERROR_CHECK(
      esp_wifi_set_promiscuous_filter(&filter)); // set MAC frame filter
  ESP_ERROR_CHECK(esp_wifi_set_promiscuous_rx_cb(&wifi_sniffer_packet_handler));
  ESP_ERROR_CHECK(esp_wifi_set_promiscuous(true)); // now switch on monitor mode
}

void wifi_sniffer_set_channel(uint8_t channel) {
  esp_wifi_set_channel(channel, WIFI_SECOND_CHAN_NONE);
}

// using IRAM_:ATTR here to speed up callback function
IRAM_ATTR void wifi_sniffer_packet_handler(void *buff,
                                           wifi_promiscuous_pkt_type_t type) {
  const wifi_promiscuous_pkt_t *ppkt = (wifi_promiscuous_pkt_t *)buff;
  const wifi_ieee80211_packet_t *ipkt =
      (wifi_ieee80211_packet_t *)ppkt->payload;
  const wifi_ieee80211_mac_hdr_t *hdr = &ipkt->hdr;

  if ((cfg.rssilimit) &&
      (ppkt->rx_ctrl.rssi < cfg.rssilimit)) { // rssi is negative value
    ESP_LOGI(TAG, "WiFi RSSI %d -> ignoring (limit: %d)", ppkt->rx_ctrl.rssi,
             cfg.rssilimit);
  } else {
    uint8_t *p = (uint8_t *)hdr->addr2;
    mac_add(p, ppkt->rx_ctrl.rssi, MAC_SNIFF_WIFI);
  }
}