ESP32-PaxCounter/src/blecsan.cpp

// some code snippets taken from
// https://github.com/nkolban/esp32-snippets/tree/master/BLE/scanner

#include "blescan.h"

#define BT_BD_ADDR_HEX(addr)                                                   \
  addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]

// local Tag for logging
static const char TAG[] = "bluetooth";

#ifdef VERBOSE
const char *bt_addr_t_to_string(esp_ble_addr_type_t type) {
  switch (type) {
  case BLE_ADDR_TYPE_PUBLIC:
    return "BLE_ADDR_TYPE_PUBLIC";
  case BLE_ADDR_TYPE_RANDOM:
    return "BLE_ADDR_TYPE_RANDOM";
  case BLE_ADDR_TYPE_RPA_PUBLIC:
    return "BLE_ADDR_TYPE_RPA_PUBLIC";
  case BLE_ADDR_TYPE_RPA_RANDOM:
    return "BLE_ADDR_TYPE_RPA_RANDOM";
  default:
    return "Unknown addr_t";
  }
} // bt_addr_t_to_string

const char *btsig_gap_type(uint32_t gap_type) {
  switch (gap_type) {
  case 0x01:
    return "Flags";
  case 0x02:
    return "Incomplete List of 16-bit Service Class UUIDs";
  case 0x03:
    return "Complete List of 16-bit Service Class UUIDs";
  case 0x04:
    return "Incomplete List of 32-bit Service Class UUIDs";
  case 0x05:
    return "Complete List of 32-bit Service Class UUIDs";
  case 0x06:
    return "Incomplete List of 128-bit Service Class UUIDs";
  case 0x07:
    return "Complete List of 128-bit Service Class UUIDs";
  case 0x08:
    return "Shortened Local Name";
  case 0x09:
    return "Complete Local Name";
  case 0x0A:
    return "Tx Power Level";
  case 0x0D:
    return "Class of Device";
  case 0x0E:
    return "Simple Pairing Hash C/C-192";
  case 0x0F:
    return "Simple Pairing Randomizer R/R-192";
  case 0x10:
    return "Device ID/Security Manager TK Value";
  case 0x11:
    return "Security Manager Out of Band Flags";
  case 0x12:
    return "Slave Connection Interval Range";
  case 0x14:
    return "List of 16-bit Service Solicitation UUIDs";
  case 0x1F:
    return "List of 32-bit Service Solicitation UUIDs";
  case 0x15:
    return "List of 128-bit Service Solicitation UUIDs";
  case 0x16:
    return "Service Data - 16-bit UUID";
  case 0x20:
    return "Service Data - 32-bit UUID";
  case 0x21:
    return "Service Data - 128-bit UUID";
  case 0x22:
    return "LE Secure Connections Confirmation Value";
  case 0x23:
    return "LE Secure Connections Random Value";
  case 0x24:
    return "URI";
  case 0x25:
    return "Indoor Positioning";
  case 0x26:
    return "Transport Discovery Data";
  case 0x17:
    return "Public Target Address";
  case 0x18:
    return "Random Target Address";
  case 0x19:
    return "Appearance";
  case 0x1A:
    return "Advertising Interval";
  case 0x1B:
    return "LE Bluetooth Device Address";
  case 0x1C:
    return "LE Role";
  case 0x1D:
    return "Simple Pairing Hash C-256";
  case 0x1E:
    return "Simple Pairing Randomizer R-256";
  case 0x3D:
    return "3D Information Data";
  case 0xFF:
    return "Manufacturer Specific Data";

  default:
    return "Unknown type";
  }
} // btsig_gap_type
#endif

// using IRAM_ATTR here to speed up callback function
IRAM_ATTR void gap_callback_handler(esp_gap_ble_cb_event_t event,
                                    esp_ble_gap_cb_param_t *param) {

  esp_ble_gap_cb_param_t *p = (esp_ble_gap_cb_param_t *)param;

#if (COUNT_ENS)
  // UUID of Exposure Notification Service (ENS)
  // https://blog.google/documents/70/Exposure_Notification_-_Bluetooth_Specification_v1.2.2.pdf
  static const char ensMagicBytes[] = "\x16\x6f\xfd";
#endif

#ifdef VERBOSE
  ESP_LOGV(TAG, "BT payload rcvd -> type: 0x%.2x -> %s", *p->scan_rst.ble_adv,
           btsig_gap_type(*p->scan_rst.ble_adv));
#endif

  switch (event) {
  case ESP_GAP_BLE_SCAN_PARAM_SET_COMPLETE_EVT:
    // restart scan
    esp_ble_gap_start_scanning(BLESCANTIME);
    break;

  case ESP_GAP_BLE_SCAN_RESULT_EVT:
    // evaluate scan results
    if (p->scan_rst.search_evt ==
        ESP_GAP_SEARCH_INQ_CMPL_EVT) // Inquiry complete, scan is done
    {                                // restart scan
      esp_ble_gap_start_scanning(BLESCANTIME);
      return;
    }

    if (p->scan_rst.search_evt ==
        ESP_GAP_SEARCH_INQ_RES_EVT) // Inquiry result for a peer device
    {                               // evaluate sniffed packet
#ifdef VERBOSE
      ESP_LOGV(TAG, "Device address (bda): %02x:%02x:%02x:%02x:%02x:%02x",
               BT_BD_ADDR_HEX(p->scan_rst.bda));
      ESP_LOGV(TAG, "Addr_type           : %s",
               bt_addr_t_to_string(p->scan_rst.ble_addr_type));
      ESP_LOGV(TAG, "RSSI                : %d", p->scan_rst.rssi);
#endif

#if (MACFILTER)
      if ((p->scan_rst.ble_addr_type == BLE_ADDR_TYPE_RANDOM) ||
          (p->scan_rst.ble_addr_type == BLE_ADDR_TYPE_RPA_RANDOM)) {
#ifdef VERBOSE
        ESP_LOGV(TAG, "BT device filtered");
#endif
        break;
      }
#endif

      // add this device mac to processing queue

#if (COUNT_ENS)
      // check for ens signature
      if (cfg.enscount) {
        if (strstr((const char *)p->scan_rst.ble_adv, ensMagicBytes) != NULL)
          mac_add((uint8_t *)p->scan_rst.bda, p->scan_rst.rssi,
                  MAC_SNIFF_BLE_ENS);
        else
          mac_add((uint8_t *)p->scan_rst.bda, p->scan_rst.rssi, MAC_SNIFF_BLE);
      }
#else
      mac_add((uint8_t *)p->scan_rst.bda, p->scan_rst.rssi, MAC_SNIFF_BLE);
#endif

      /* to be improved in macfilter:
      // you can search for elements in the payload using the
      // function esp_ble_resolve_adv_data()
      //
      // Like this, that scans for the "Complete name" (looking inside the
      payload buffer)
      // uint8_t len;
      // uint8_t *data = esp_ble_resolve_adv_data(p->scan_rst.ble_adv,
      ESP_BLE_AD_TYPE_NAME_CMPL, &len);

      filter BLE devices using their advertisements to get filter alternative
      to vendor OUI if macfiltering is on, we ...
      - want to count: mobile phones and tablets
      - don't want to count: beacons, peripherals (earphones, headsets,
      printers), cars and machines see
      https://github.com/nkolban/ESP32_BLE_Arduino/blob/master/src/BLEAdvertisedDevice.cpp

      http://www.libelium.com/products/meshlium/smartphone-detection/

      https://www.question-defense.com/2013/01/12/bluetooth-cod-bluetooth-class-of-deviceclass-of-service-explained

      https://www.bluetooth.com/specifications/assigned-numbers/baseband

      "The Class of Device (CoD) in case of Bluetooth which allows us to
      differentiate the type of device (smartphone, handsfree, computer,
      LAN/network AP). With this parameter we can differentiate among
      pedestrians and vehicles."

      */

    } // evaluate sniffed packet
    break;

  default:
    break;
  } // switch
} // gap_callback_handler

esp_err_t register_ble_callback(bool unregister = false) {

  if (unregister) {

    ESP_LOGI(TAG, "Unregister GAP callback...");
    esp_ble_gap_stop_scanning();
    esp_ble_gap_register_callback(NULL);

  }

  else {

    ESP_LOGI(TAG, "Register GAP callback...");

    // This function is called when gap event occurs, such as scan result.
    // register the scan callback function to the gap module
    esp_ble_gap_register_callback(&gap_callback_handler);

    static esp_ble_scan_params_t ble_scan_params = {
        .scan_type = BLE_SCAN_TYPE_PASSIVE,
        .own_addr_type = BLE_ADDR_TYPE_RANDOM,
        .scan_filter_policy = BLE_SCAN_FILTER_ALLOW_ALL,

        /*
                #if (MACFILTER)
                      .scan_filter_policy = BLE_SCAN_FILTER_ALLOW_WLIST_PRA_DIR,
                    // ADV_IND, ADV_NONCONN_IND, ADV_SCAN_IND packets are used
           for broadcasting
                    // data in broadcast applications (e.g., Beacons), so we
           don't want them in
                    // macfilter mode
                #else
                      .scan_filter_policy = BLE_SCAN_FILTER_ALLOW_ALL,
                #endif
        */

        .scan_interval =
            (uint16_t)(cfg.blescantime * 10 / 0.625), // Time = N * 0.625 msec
        .scan_window =
            (uint16_t)(BLESCANWINDOW / 0.625), // Time = N * 0.625 msec
        .scan_duplicate = BLE_SCAN_DUPLICATE_ENABLE};

    ESP_LOGI(TAG, "Set GAP scan parameters");

    // This function is called to set scan parameters.
    esp_ble_gap_set_scan_params(&ble_scan_params);
  }

  return ESP_OK;

} // register_ble_callback

void start_BLEscan(void) {
#if (BLECOUNTER)
  ESP_LOGI(TAG, "Initializing bluetooth scanner ...");
  // Initialize BT controller to allocate task and other resource.
  if (btStart()) { // enable bt_controller
    esp_coex_preference_set(ESP_COEX_PREFER_BT);
    esp_bluedroid_init();
    esp_bluedroid_enable();
    // Register callback function for capturing bluetooth packets
    register_ble_callback(false);
    ESP_LOGI(TAG, "Bluetooth scanner started");
#endif // BLECOUNTER
  } else {
    ESP_LOGE(TAG, "Bluetooth controller start failed. Resetting device");
    do_reset(true);
  }

} // start_BLEscan

void stop_BLEscan(void) {
#if (BLECOUNTER)
  ESP_LOGI(TAG, "Shutting down bluetooth scanner ...");
  register_ble_callback(true); // unregister capture function
  ESP_LOGD(TAG, "bluedroid disable...");
  esp_bluedroid_disable();
  ESP_LOGD(TAG, "bluedroid deinit...");
  esp_bluedroid_deinit();
  if (!btStop()) { // disable bt_controller
    ESP_LOGE(TAG, "Bluetooth controller stop failed. Resetting device");
    do_reset(true);
  }
  esp_coex_preference_set(ESP_COEX_PREFER_WIFI);
  ESP_LOGI(TAG, "Bluetooth scanner stopped");
#endif // BLECOUNTER
} // stop_BLEscan