Apple Notification Center Service - hard coded max attribute length of 32?

[denis]

nrf_ble_ancs_c.h has hardcoded max attribute length of 32 (BLE_ANCS_ATTR_DATA_MAX).

1) BLE_ANCS_ATTR_DATA_MAX mainly seems to be used to allocate the size of the app_id in ble_ancs_c_evt_t.  So maybe is misnamed?

2) BLE_ANCS_ATTR_DATA_MAX is also used for checking the the length passed to nrf_ble_ancs_c_attr_add.  But that doesn't seem to make sense because the buffers are passed in and can be of any size.  Is this a bug?  I want to be able to pass in a large buffer (say 100 bytes) for the message attribute so I can get more than 32 characters of the notification message attribute.

[denis]

It also looks like the null termination on an attribute writes 1 past the buffer end in ancs_attr_parser.c:

    // We have reached the end of the attribute, or our max allocated internal size.
    // Stop copying data over to our buffer. NUL-terminate at the current index.
    if ( (p_ancs->parse_info.current_attr_index == p_ancs->evt.attr.attr_len) ||
         (p_ancs->parse_info.current_attr_index == p_ancs->parse_info.p_attr_list[p_ancs->evt.attr.attr_id].attr_len - 1))
    {
        if (attr_is_requested(p_ancs, p_ancs->evt.attr))
        {
            p_ancs->evt.attr.p_attr_data[p_ancs->parse_info.current_attr_index] = '\0';
        }

[denis]

One other note:  It looks like in the example nrf_ble_ancs_c_attr_add is called before ble_ancs_c_init.  Seems like it would be safer for ble_ancs_c_init to initialize all the ancs_notif_attr_list values to get = false and then call nrf_ble_ancs_c_attr_add only on the attributes that you want to retrieve.  (As it is now if you comment out any of the nrf_ble_ancs_c_attr_add then you have undefined values, which leads to undefined behavior.)

[Håvard]

You are correct, it would be safer to explicitly set values to 0 first. Here the example assumes that the variables are initialized to 0 by the compiler, and then replaced by the nrf_ble_ancs_c_attr_add() funcitons.