When are peer managers connection handles invalidated?

Hi,

The Peer Manager uses the Connection state module to check this. Snippet from ble_conn_state.c where connection handles are invalidated:

        case BLE_GAP_EVT_DISCONNECTED:
            record_set_disconnected(conn_handle);
            break;

What SDK version are you using?

When do you call pm_conn_handle_get() ? On BLE_GAP_EVT_DISCONNECTED or some other events?

Hi,

I am using SDK version 17.0.2. I don't call pm_conn_handle_get() on BLE_GAP_EVT_DISCONNECTED.

After disconnect I send an command via BLE nus service to the central to remove the bonds.

I can verify that this code exists on my side. I guess it is called via

NRF_SDH_BLE_OBSERVER(m_ble_evt_observer, BLE_CONN_STATE_BLE_OBSERVER_PRIO, ble_evt_handler, NULL);

mgux said:

After disconnect I send an command via BLE nus service to the central to remove the bonds.

 1)So you are in a active connection to another device when you try to delete the bond from the previously connected device?

 2) Can you post the code you use to delete the bond ? 

user15146 said:

 1)So you are in a active connection to another device when you try to delete the bond from the previously connected device?

Sorry I was wrong. The command is sent via USB CDC. But it is possible to be connected to another peer while I delete the bond to another one.

I use this snippet to disconnect (if still connected) and remove the bond:

// disconnect and remove peer
uint16_t connHandle = BLE_CONN_HANDLE_INVALID;
auto ret = pm_conn_handle_get(peerId, &connHandle);
APP_ERROR_CHECK(ret);

if(connectionHandle == BLE_CONN_HANDLE_INVALID)
{
    return;
}
ret = sd_ble_gap_disconnect(connectionHandle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);

APP_ERROR_CHECK(ret);
// The peer got removed from the list of bonds.
ret = pm_peer_delete(peerId);
APP_ERROR_CHECK(ret);

I can confirm that

record_set_disconnected(conn_handle);

is called in ble_conn_state.c.

I found some more:

in ble_conn_state.c:

typedef struct
{
    nrf_atflags_t valid_flags;                                 /**< Flags indicating which connection handles are valid. */
    nrf_atflags_t connected_flags;                             /**< Flags indicating which connections are connected, since disconnected connection handles will not immediately be invalidated. */
    nrf_atflags_t central_flags;                               /**< Flags indicating in which connections the local device is the central. */
    nrf_atflags_t encrypted_flags;                             /**< Flags indicating which connections are encrypted. */
    nrf_atflags_t mitm_protected_flags;                        /**< Flags indicating which connections have encryption with protection from man-in-the-middle attacks. */
    nrf_atflags_t lesc_flags;                                  /**< Flags indicating which connections have bonded using LE Secure Connections (LESC). */
    nrf_atflags_t user_flags[BLE_CONN_STATE_USER_FLAG_COUNT];  /**< Flags that can be reserved by the user. The flags will be cleared when a connection is invalidated, otherwise, the user is wholly responsible for the flag states. */
} ble_conn_state_flag_collections_t;

static void record_set_disconnected(uint16_t conn_handle)
{
    nrf_atflags_clear(&m_bcs.flags.connected_flags, conn_handle);
}

bool ble_conn_state_valid(uint16_t conn_handle)
{
    if (conn_handle >= BLE_CONN_STATE_MAX_CONNECTIONS)
    {
        return false;
    }
    return nrf_atflags_get(&m_bcs.flags.valid_flags, conn_handle);
}

ble_conn_state_valid() is used in pm_conn_handle_get() and checks the valid_flags.. But record_set_disconnected() clears the connected flag not the valid_flags.

Also the comment for connected_flags says that connection handles will no immediately be invalidated.

So maybe one should check the connected flag in pm_conn_handle_get()?

mgux said:

I use this snippet to disconnect

Seems like you are using both connectionHandle and connHandle?

Try this instead:

// disconnect and remove peer
uint16_t connHandle = BLE_CONN_HANDLE_INVALID;
auto ret = pm_conn_handle_get(peerId, &connHandle);
APP_ERROR_CHECK(ret);

if(connHandle == BLE_CONN_HANDLE_INVALID)
{
    return;
}
ret = sd_ble_gap_disconnect(connHandle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);

APP_ERROR_CHECK(ret);
// The peer got removed from the list of bonds.
ret = pm_peer_delete(peerId);
APP_ERROR_CHECK(ret);

mgux said:

I use this snippet to disconnect

Seems like you are using both connectionHandle and connHandle?

Try this instead:

// disconnect and remove peer
uint16_t connHandle = BLE_CONN_HANDLE_INVALID;
auto ret = pm_conn_handle_get(peerId, &connHandle);
APP_ERROR_CHECK(ret);

if(connHandle == BLE_CONN_HANDLE_INVALID)
{
    return;
}
ret = sd_ble_gap_disconnect(connHandle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);

APP_ERROR_CHECK(ret);
// The peer got removed from the list of bonds.
ret = pm_peer_delete(peerId);
APP_ERROR_CHECK(ret);

Sorry, that was a copy&paste error.

I use connHandle everywhere.

I tried to change im__conn_handle_get to the following:

uint16_t im_conn_handle_get(pm_peer_id_t peer_id)
{
    if (peer_id == PM_PEER_ID_INVALID)
    {
        return BLE_CONN_HANDLE_INVALID;
    }

    for (uint16_t conn_handle = 0; conn_handle < IM_MAX_CONN_HANDLES; conn_handle++)
    {
        if ((m_connections[conn_handle].peer_id == peer_id) && ble_conn_state_status(conn_handle) == BLE_CONN_STATUS_CONNECTED)
        {
            return conn_handle;
        }
    }
    return BLE_CONN_HANDLE_INVALID;
}

ble_conn_state_status() checks the valid_flags and connected_flags. This fixes my problem.

Please find the patch attached.