DFU with extra authentication

RE: DFU with extra authentication

bjorn-spockeli — Thu, 02 Jan 2020 12:21:37 GMT

Great! Glad to hear that your issue has been solved.

RE: DFU with extra authentication

chandan — Thu, 02 Jan 2020 11:18:55 GMT

Yes

RE: DFU with extra authentication

bjorn-spockeli — Thu, 02 Jan 2020 09:15:24 GMT

Hi Chandan, so calling sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_AUTHENTICATION_FAILURE) before ble_advertising_start() resolves the issue with error code 0x12?

RE: DFU with extra authentication

chandan — Thu, 26 Dec 2019 09:18:48 GMT

Hi, For disconnecting I am using sd_ble_gap_disconnect(m_conn_handle, BLE_HCI_AUTHENTICATION_FAILURE) nut getting error as 0x12

RE: DFU with extra authentication

bjorn-spockeli — Mon, 16 Dec 2019 11:23:42 GMT

0x12 corresponds to NRF_ERROR_CONN_COUNT. Looking at the documentation for sd_ble_gap_adv_start which is called by ble_advertising_start

@retval ::NRF_ERROR_CONN_COUNT The limit of available connections for this connection configuration
* tag has been reached; connectable advertiser cannot be started.
* To increase the number of available connections,
* use @ref sd_ble_cfg_set with @ref BLE_GAP_CFG_ROLE_COUNT or @ref BLE_CONN_CFG_GAP.

So you are in a connection when calling ble_advertising_start() and the NRF_SDH_BLE_PERIPHERAL_LINK_COUNT is set 1. So if you want to advertise, you will either have to disconnect the existing connection or increase the peripheral link count. Note you also have to increase the NRF_SDH_BLE_TOTAL_LINK_COUNT if you go for the second option.

RE: DFU with extra authentication

chandan — Mon, 16 Dec 2019 11:07:26 GMT

I am getting error number 0x12 when calling ble_advertising_start().

RE: DFU with extra authentication

bjorn-spockeli — Mon, 16 Dec 2019 10:24:51 GMT

ble_advertising_start() should work just fine.

RE: DFU with extra authentication

chandan — Mon, 16 Dec 2019 05:48:56 GMT

Thanks, I can find only ble_advertising_start, but don't think its correct one. Found ble_advertising_restart_without_whitelist

RE: DFU with extra authentication

bjorn-spockeli — Fri, 13 Dec 2019 13:51:32 GMT

If ble_dfu_buttonless_bootloader_start_prepare returns a non-zero error code, then the ble_dfu_evt_handler() will be called with the as BLE_DFU_EVT_BOOTLOADER_ENTER_FAILED as the event type.

static void on_hvc(ble_evt_t const * p_ble_evt)
{
    uint32_t err_code;
    ble_gatts_evt_hvc_t const * p_hvc = &p_ble_evt->evt.gatts_evt.params.hvc;

    if (p_hvc->handle == m_dfu.control_point_char.value_handle)
    {
        // Enter bootloader if we were waiting for reset after hvc indication confimation.
        if (m_dfu.is_waiting_for_reset)
        {
            err_code = ble_dfu_buttonless_bootloader_start_prepare();
            if (err_code != NRF_SUCCESS)
            {
                m_dfu.evt_handler(BLE_DFU_EVT_BOOTLOADER_ENTER_FAILED);
            }
        }
    }
}

Hence, you can restart advertisment in ble_dfu_evt_handler() under case BLE_DFU_EVT_BOOTLOADER_ENTER_FAILED:

RE: DFU with extra authentication

chandan — Fri, 13 Dec 2019 13:15:56 GMT

I tried below code, when authentication_ok is false, NRF doesn't start DFU and disconnect device but post NRF stop BLE advertisement. I tried calling event handler post authentication check.

uint32_t ble_dfu_buttonless_bootloader_start_prepare(void)
{
    uint32_t err_code;

    // Indicate to main app that DFU mode is starting.
    mp_dfu->evt_handler(BLE_DFU_EVT_BOOTLOADER_ENTER_PREPARE);
    
    if(authentication_ok)
    {
        err_code = ble_dfu_buttonless_bootloader_start_finalize();
        return err_code;
    }else
    {
        //Authentication failed. Do not enter bootloader mode
        return NRF_ERROR_FORBIDDEN;
    }
}

RE: DFU with extra authentication

bjorn-spockeli — Fri, 13 Dec 2019 12:17:15 GMT

Hi Chandan,

from the point you receive the BLE_DFU_EVT_BOOTLOADER_ENTER_PREPARE event, then there is no way to halt the reset process with out modifying the SDK source as ble_dfu_buttonless_bootloader_start_finalize will be called immediately after the evt_handler, i.e. ble_dfu_evt_handler() returns. As you see below ble_dfu_buttonless_bootloader_start_finalize() calls nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_DFU) and there is no API in the power management module to abort this.

uint32_t ble_dfu_buttonless_bootloader_start_finalize(void)
{
    uint32_t err_code;

    NRF_LOG_DEBUG("In ble_dfu_buttonless_bootloader_start_finalize\r\n");

    err_code = sd_power_gpregret_clr(0, 0xffffffff);
    VERIFY_SUCCESS(err_code);

    err_code = sd_power_gpregret_set(0, BOOTLOADER_DFU_START);
    VERIFY_SUCCESS(err_code);

    // Indicate that the Secure DFU bootloader will be entered
    m_dfu.evt_handler(BLE_DFU_EVT_BOOTLOADER_ENTER);

    // Signal that DFU mode is to be enter to the power management module
    nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_DFU);

    return NRF_SUCCESS;
}

So its not possible to prevent the reset, but it is possible to make the device boot straight back to the application by calling sd_power_gpregret_clr(0, 0xffffffff) when you get the BLE_DFU_EVT_BOOTLOADER_ENTER event. The GPREGRET register is checked by the bootloader and if it does not contain the BOOTLOADER_DFU_START value, then the bootloader will jump to the application.

Best regards

Bjørn

RE: DFU with extra authentication

chandan — Fri, 13 Dec 2019 10:51:36 GMT

Thanks for quick reply.

I don't want to make change in any SDK file. Its difficult to update same change in all member's SDK file. Please suggest similar to callback function change.

RE: DFU with extra authentication

bjorn-spockeli — Fri, 13 Dec 2019 10:38:20 GMT

HI Chandan,

the BLE_DFU_EVT_BOOTLOADER_ENTER_PREPARE event will be generated when ble_dfu_buttonless_bootloader_start_prepare is called.

uint32_t ble_dfu_buttonless_bootloader_start_prepare(void)
{
    uint32_t err_code;

    // Indicate to main app that DFU mode is starting.
    mp_dfu->evt_handler(BLE_DFU_EVT_BOOTLOADER_ENTER_PREPARE);

    err_code = ble_dfu_buttonless_bootloader_start_finalize();
    return err_code;
}

As you can see ble_dfu_buttonless_bootloader_start_finalize() is called when the evt_handler has returned. So if you want to prevent the device from entering bootloader moder, then you will have to set a flag or similar when the extra authentication fails and then check this in ble_dfu_buttonless_bootloader_start_prepare() after the evt_handler has returned. One way to do this is as follows:

uint32_t ble_dfu_buttonless_bootloader_start_prepare(void)
{
    uint32_t err_code;

    // Indicate to main app that DFU mode is starting.
    mp_dfu->evt_handler(BLE_DFU_EVT_BOOTLOADER_ENTER_PREPARE);
    
    if(authentication_ok)
    {
        err_code = ble_dfu_buttonless_bootloader_start_finalize();
        return err_code;
    }else
    {
        //Authentication failed. Do not enter bootloader mode
        return NRF_ERROR_FORBIDDEN;
    }
}

Best regards

Bjørn