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  • Case ID: 289481
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BLE multi-peripheral and peer manager

user94851

Hi,

I need to create a device that can support up to 10 concurrent connection with MITM protection, so I would like to implement bonding with a passkey.

I started my project with the example "ble_app_gls", afterwards added multi-peripheral functionality based on example "ble_app_multiperipheral". Concurrent connections work correct, but I have a few question about peer manager:

1. When will the link not be authenticated and the peer will be removed? (I don't know when this might happen)

case PM_EVT_CONN_SEC_SUCCEEDED:
        {
            pm_conn_sec_status_t conn_sec_status;

            // Check if the link is authenticated (meaning at least MITM).
            err_code = pm_conn_sec_status_get(p_evt->conn_handle, &conn_sec_status);
            APP_ERROR_CHECK(err_code);

            if (conn_sec_status.mitm_protected)
            {
                NRF_LOG_INFO("Link secured. Role: %d. conn_handle: %d, Procedure: %d",
                             ble_conn_state_role(p_evt->conn_handle),
                             p_evt->conn_handle,
                             p_evt->params.conn_sec_succeeded.procedure);
            }
            else
            {
                // The peer did not use MITM, disconnect.
                NRF_LOG_INFO("Collector did not use MITM, disconnecting");
                err_code = pm_peer_id_get(p_evt->conn_handle, &m_peer_to_be_deleted);
                APP_ERROR_CHECK(err_code);
                err_code = sd_ble_gap_disconnect(p_evt->conn_handle,
                                                 BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
                APP_ERROR_CHECK(err_code);
            }
        } break;

2. How should I add this security for multi-peripheral? Whether the following changes are enough?

a) replacement the variable "static pm_peer_id_t m_peer_to_be_deleted = PM_PEER_ID_INVALID" to an array "static pm_peer_id_t m_peer_to_be_deleted[NRF_SDH_BLE_PERIPHERAL_LINK_COUNT]"

b) removal "m_peer_to_be_deleted = PM_PEER_ID_INVALID" from BLE_GAP_EVT_CONNECTED

        case BLE_GAP_EVT_CONNECTED:
        {
            NRF_LOG_INFO("Connection with device %d established.", ((p_ble_evt->evt.gap_evt.conn_handle)+1)); // the +1 so that we start counting from 1 not zero.
            /*deleted*/
            /*m_peer_to_be_deleted = PM_PEER_ID_INVALID;*/

            // Assign connection handle to available instance of QWR module.
            for (uint32_t i = 0; i < NRF_SDH_BLE_PERIPHERAL_LINK_COUNT; i++)
            {
                if (m_qwr[i].conn_handle == BLE_CONN_HANDLE_INVALID)
                {
                    err_code = nrf_ble_qwr_conn_handle_assign(&m_qwr[i], p_ble_evt->evt.gap_evt.conn_handle);
                    APP_ERROR_CHECK(err_code);
                    break;
                }
            }

            //By default advertising stops when BLE_GAP_EVT_CONNECTED is received , however , we need to manually switch it back on, untill all potential-
			// central devices are connected.
            if (periph_link_cnt != NRF_SDH_BLE_PERIPHERAL_LINK_COUNT)
            {
                // Continue advertising. More connections can be established because the maximum link count has not been reached.
                advertising_start(false);
            }
        } break;

c) the following change in the handling of the event PM_EVT_CONN_SEC_SUCCEEDED

if (conn_sec_status.mitm_protected)
            {
                NRF_LOG_INFO("Link secured. Role: %d. conn_handle: %d, Procedure: %d",
                             ble_conn_state_role(p_evt->conn_handle),
                             p_evt->conn_handle,
                             p_evt->params.conn_sec_succeeded.procedure);
            }
            else
            {
                // The peer did not use MITM, disconnect.
                NRF_LOG_INFO("Collector did not use MITM, disconnecting");
                /*Before*/
                /*err_code = pm_peer_id_get(p_evt->conn_handle, &m_peer_to_be_deleted);*/
                /*After*/
                /*err_code = pm_peer_id_get(p_evt->conn_handle, &m_peer_to_be_deleted[p_evt->conn_handle]);*/
                APP_ERROR_CHECK(err_code);
                err_code = sd_ble_gap_disconnect(p_evt->conn_handle,
                                                 BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
                APP_ERROR_CHECK(err_code);
            }

d) the following change in the handling of the event BLE_GAP_EVT_DISCONNECTED

        case BLE_GAP_EVT_DISCONNECTED:
        {
            NRF_LOG_INFO("Connection with device %d has been disconnected. Reason: 0x%X",
                         ((p_ble_evt->evt.gap_evt.conn_handle)+1),// the +1 so that we start counting from 1 not zero.
                         p_ble_evt->evt.gap_evt.params.disconnected.reason);

            //This is in case one of the centrals decided to disconnect, we restart advertising to indicate an available link
            if (periph_link_cnt == (NRF_SDH_BLE_PERIPHERAL_LINK_COUNT - 1))
            {
                // Advertising is not running when all connections are taken, and must therefore be started.
                advertising_start(false);
            }

            // Check if the last connected peer had not used MITM, if so, delete its bond information.
            /*Before*/
            /*if (m_peer_to_be_deleted != PM_PEER_ID_INVALID)
            {
                err_code = pm_peer_delete(m_peer_to_be_deleted);
                APP_ERROR_CHECK(err_code);
                NRF_LOG_DEBUG("Collector's bond deleted");
                m_peer_to_be_deleted = PM_PEER_ID_INVALID;
            }*/
            /*After*/
            for (uint32_t i = 0; i < NRF_SDH_BLE_PERIPHERAL_LINK_COUNT; i++)
            {
                if ((i==p_ble_evt->evt.gap_evt.conn_handle) && (m_peer_to_be_deleted[i] != PM_PEER_ID_INVALID))
                {
                    err_code = pm_peer_delete(m_peer_to_be_deleted[i]);
                    APP_ERROR_CHECK(err_code);
                    NRF_LOG_DEBUG("Collector's bond deleted");
                    m_peer_to_be_deleted[i] = PM_PEER_ID_INVALID;
                    break;
                }
            }
        } break;

Best regards,

KaEd1705

Parents
  • 0
    1. When will the link not be authenticated and the peer will be removed? (I don't know when this might happen)

    You need to do that yourself in the application by manually calling pm_peer_delete.
    An example can be found in SDK\examples\ble_peripheral\ble_app_bms\main.c:bond_delete()

    a) replacement the variable "static pm_peer_id_t m_peer_to_be_deleted = PM_PEER_ID_INVALID" to an array "static pm_peer_id_t m_peer_to_be_deleted[NRF_SDH_BLE_PERIPHERAL_LINK_COUNT]"

    I do not think this is needed, the peer to be deleted is extracted using pm_peer_id_get into one entry and you do not need an array to delete a peer from peer manager once instance at a time.

    It looks like you are asking us to review the changes without showing us if you have compiled and run your changes on the chip? We do not have the capacity to review the changes for you, but I will try to assist you in the issues you see in your debugging you see with our API. 

    Please compile, flash and run your application and try to debug it a bit to see if the changes you made are behaving the way you intended them to be.

Reply
  • 0
    1. When will the link not be authenticated and the peer will be removed? (I don't know when this might happen)

    You need to do that yourself in the application by manually calling pm_peer_delete.
    An example can be found in SDK\examples\ble_peripheral\ble_app_bms\main.c:bond_delete()

    a) replacement the variable "static pm_peer_id_t m_peer_to_be_deleted = PM_PEER_ID_INVALID" to an array "static pm_peer_id_t m_peer_to_be_deleted[NRF_SDH_BLE_PERIPHERAL_LINK_COUNT]"

    I do not think this is needed, the peer to be deleted is extracted using pm_peer_id_get into one entry and you do not need an array to delete a peer from peer manager once instance at a time.

    It looks like you are asking us to review the changes without showing us if you have compiled and run your changes on the chip? We do not have the capacity to review the changes for you, but I will try to assist you in the issues you see in your debugging you see with our API. 

    Please compile, flash and run your application and try to debug it a bit to see if the changes you made are behaving the way you intended them to be.

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