static void relay_packet(dfu_packet_t* p_packet, uint16_t length)
{
    mesh_packet_t* p_mesh_packet = mesh_packet_get_aligned(p_packet);
    if (!p_mesh_packet)
    {
        if (!mesh_packet_acquire(&p_mesh_packet))
        {
            APP_ERROR_CHECK(NRF_ERROR_NO_MEM);
        }
        mesh_packet_build(
            p_mesh_packet,
            p_packet->packet_type,
            p_packet->payload.data.segment,
            (uint8_t*) &p_packet->payload.data.transaction_id,
            length - 4);
    }
    else
    {
        mesh_packet_ref_count_inc(p_mesh_packet);
    }

    mesh_packet_set_local_addr(p_mesh_packet);

    if (transport_tx(p_mesh_packet, TX_REPEATS_DATA, TX_INTERVAL_TYPE_DATA, packet_release_callback))
    {
        mp_sent_packets[(m_sent_packet_index++) & (SENT_PACKET_COUNT - 1)] = p_mesh_packet;
    }
    mesh_packet_ref_count_dec(p_mesh_packet);
}
uint32_t handle_storage_flag_set(uint16_t handle, handle_flag_t flag, bool value)
{
    if (flag >= HANDLE_FLAG__MAX)
    {
        return NRF_ERROR_INVALID_PARAM;
    }
    if (handle == RBC_MESH_INVALID_HANDLE)
    {
        return NRF_ERROR_INVALID_ADDR;
    }

    uint16_t handle_index = handle_entry_get(handle, true);

    switch (flag)
    {
        case HANDLE_FLAG_PERSISTENT:
            if (handle_index == HANDLE_CACHE_ENTRY_INVALID)
            {
                handle_index = handle_entry_to_head(handle);

                if (handle_index == HANDLE_CACHE_ENTRY_INVALID)
                {
                    return NRF_ERROR_NO_MEM;
                }
            }
            m_handle_cache[handle_index].persistent = value;
            break;

        case HANDLE_FLAG_TX_EVENT:
            if (handle_index == HANDLE_CACHE_ENTRY_INVALID)
            {
                handle_index = handle_entry_to_head(handle);

                if (handle_index == HANDLE_CACHE_ENTRY_INVALID)
                {
                    return NRF_ERROR_NO_MEM;
                }
            }
            m_handle_cache[handle_index].tx_event = value;
            break;

        case HANDLE_FLAG_DISABLED:
            if (value)
            {
                if (handle_index == HANDLE_CACHE_ENTRY_INVALID)
                {
                    return NRF_SUCCESS; /* the value is already disabled */
                }
                if (m_handle_cache[handle_index].data_entry == DATA_CACHE_ENTRY_INVALID)
                {
                    return NRF_SUCCESS; /* the value is already disabled */
                }
                trickle_disable(&m_data_cache[m_handle_cache[handle_index].data_entry].trickle);
            }
            else
            {
                uint32_t error_code;
                mesh_packet_t* p_packet = NULL;
                if (!mesh_packet_acquire(&p_packet))
                {
                    return NRF_ERROR_NO_MEM;
                }

                error_code = mesh_packet_build(p_packet,
                        handle,
                        0,
                        NULL,
                        0);
                if (error_code != NRF_SUCCESS)
                {
                    mesh_packet_ref_count_dec(p_packet);
                    return error_code;
                }

                if (handle_index == HANDLE_CACHE_ENTRY_INVALID)
                {
                    /* may safely run this function inline, as we're already in event handler */
                    local_packet_push(p_packet);
                    return NRF_SUCCESS;
                }
                else
                {
                    if (m_handle_cache[handle_index].data_entry == DATA_CACHE_ENTRY_INVALID)
                    {
                        m_handle_cache[handle_index].data_entry = data_entry_allocate();
                        if (m_handle_cache[handle_index].data_entry == DATA_CACHE_ENTRY_INVALID)
                        {
                            return NRF_ERROR_NO_MEM;
                        }
                    }
                    if (m_data_cache[m_handle_cache[handle_index].data_entry].p_packet != NULL)
                    {
                        /* someone set the packet already, let's not overwrite it. */
                        mesh_packet_ref_count_dec(p_packet);
                    }
                    else
                    {
                        m_data_cache[m_handle_cache[handle_index].data_entry].p_packet = p_packet;
                    }
                    trickle_enable(&m_data_cache[m_handle_cache[handle_index].data_entry].trickle);
                }
            }
            break;
        default:
            return NRF_ERROR_INVALID_PARAM;
    }

    return NRF_SUCCESS;
}
static void handle_data_packet(dfu_packet_t* p_packet, uint16_t length)
{
    mesh_packet_t* p_cache_packet = packet_cache_entry_get(p_packet);
    if (p_cache_packet)
    {
        transport_tx_skip(p_cache_packet);
    }
    
    bool do_relay = false;
    if (p_packet->payload.data.transaction_id == m_transaction.transaction_id)
    {
        /* check and add to cache */
        if (data_packet_in_cache(p_packet))
        {
            return;
        }
        m_data_cache[(m_data_index++) & (DATA_CACHE_SIZE - 1)] = p_packet->payload.data.segment;
        
        
        if (m_state == BL_STATE_DFU_READY)
        {
            if (p_packet->payload.start.segment == 0)
            {
                bl_info_segment_t* p_segment = NULL;
                switch (m_transaction.type)
                {
                    case DFU_TYPE_APP:
                        p_segment = m_bl_info_pointers.p_segment_app;
                        break;
                    case DFU_TYPE_SD:
                        p_segment = m_bl_info_pointers.p_segment_sd;
                        break;
                    case DFU_TYPE_BOOTLOADER:
                        p_segment = m_bl_info_pointers.p_segment_bl;
                        break;
                    default:
                        APP_ERROR_CHECK(NRF_ERROR_NOT_SUPPORTED);
                }
                
                m_transaction.p_indicated_start_addr = (uint32_t*) p_packet->payload.start.start_address;
                uint32_t start_address = p_packet->payload.start.start_address;
                /* if the host doesn't know the start address, we use start of segment: */
                if (start_address == START_ADDRESS_UNKNOWN)
                {
                    start_address = p_segment->start;
                }

                uint32_t segment_count = ((p_packet->payload.start.length * 4) + (start_address & 0x0F) - 1) / 16 + 1;
                
                if (p_packet->payload.start.signature_length != 0)
                {
                    segment_count += p_packet->payload.start.signature_length / SEGMENT_LENGTH;
                }
                if (segment_count > 0xFFFF)
                {
                    /* can't have more than 65536 segments in a transmission */
                    segment_count = 0xFFFF;
                }

                m_transaction.segments_remaining                = segment_count;
                m_transaction.segment_count                     = segment_count;
                m_transaction.p_start_addr                      = (uint32_t*) start_address;
                m_transaction.length                            = p_packet->payload.start.length * 4;
                m_transaction.signature_length                  = p_packet->payload.start.signature_length;
                m_transaction.segment_is_valid_after_transfer   = p_packet->payload.start.last;
                m_transaction.p_last_requested_entry            = NULL;
                m_transaction.signature_bitmap                  = 0;
                

                if (m_transaction.type == DFU_TYPE_BOOTLOADER)
                {
                    m_transaction.p_bank_addr = (uint32_t*) (
                        (m_bl_info_pointers.p_segment_app->start) +
                        (m_bl_info_pointers.p_segment_app->length) -
                        (m_transaction.length & ((uint32_t) ~(PAGE_SIZE - 1))) -
                        (PAGE_SIZE)
                    );
                }
                else
                {
                    m_transaction.p_bank_addr = m_transaction.p_start_addr;
                }

                if ((uint32_t) m_transaction.p_start_addr >= p_segment->start &&
                    (uint32_t) m_transaction.p_start_addr + m_transaction.length <= p_segment->start + p_segment->length)
                {
                    start_target();
                    do_relay = true;
                }
            }
            else
            {
                m_tid_cache[(m_tid_index++) & (TRANSACTION_ID_CACHE_SIZE - 1)] = m_transaction.transaction_id;
                start_req(m_transaction.type, true); /* go back to req, we've missed packet 0 */
            }
        }
        else if (m_state == BL_STATE_DFU_TARGET)
        {
            if (p_packet->payload.data.segment > 0 &&
                p_packet->payload.data.segment <= m_transaction.segment_count)
            {
                uint32_t* p_addr = NULL; 
                uint32_t error_code = NRF_ERROR_NULL;
                
                if (p_packet->payload.data.segment <= 
                    m_transaction.segment_count - m_transaction.signature_length / SEGMENT_LENGTH)
                {
                    p_addr = addr_from_seg(p_packet->payload.data.segment);
                    error_code  = dfu_data((uint32_t) p_addr,
                                               p_packet->payload.data.data,
                                               length - (DFU_PACKET_LEN_DATA - SEGMENT_LENGTH));
                }
                else /* treat signature packets at the end */
                {
                    uint32_t index = p_packet->payload.data.segment - (m_transaction.segment_count - m_transaction.signature_length / SEGMENT_LENGTH) - 1;
                    if (index >= m_transaction.signature_length / SEGMENT_LENGTH || 
                        m_transaction.signature_bitmap & (1 << index))
                    {
                        error_code = NRF_ERROR_INVALID_STATE;
                    }
                    else
                    {
                        memcpy(&m_transaction.signature[index * SEGMENT_LENGTH], 
                               p_packet->payload.data.data, 
                               length - (DFU_PACKET_LEN_DATA - SEGMENT_LENGTH));
                        
                        m_transaction.signature_bitmap |= (1 << index);
                        error_code = NRF_SUCCESS;
                    }
                }
                
                if (error_code == NRF_SUCCESS)
                {
                    set_timeout(STATE_TIMEOUT_TARGET);
                    m_transaction.segments_remaining--;
                    do_relay = true;
                    /* check whether we've lost any entries, and request them */
                    uint32_t* p_req_entry = NULL;
                    uint32_t req_entry_len = 0;
                    mesh_packet_t* p_req_packet;
                    
                    if (dfu_get_oldest_missing_entry(
                            m_transaction.p_last_requested_entry,
                            &p_req_entry,
                            &req_entry_len) &&
                        (
                         /* don't request the previous packet yet */
                         ADDR_SEGMENT(p_req_entry, m_transaction.p_start_addr) < p_packet->payload.data.segment - 1 ||
                         m_transaction.segment_count == p_packet->payload.data.segment
                        ) 
                       )
                    {
                        if(!mesh_packet_acquire(&p_req_packet))
                        {
                            return;
                        }
                        if (mesh_packet_build(p_req_packet,
                                DFU_PACKET_TYPE_DATA_REQ,
                                ADDR_SEGMENT(p_req_entry, m_transaction.p_start_addr),
                                (uint8_t*) &m_transaction.transaction_id,
                                4) == NRF_SUCCESS &&
                            transport_tx(p_req_packet, TX_REPEATS_REQ, TX_INTERVAL_TYPE_REQ, NULL))
                        {
                            m_transaction.p_last_requested_entry = (uint32_t*) p_req_entry;
                        }
                        mesh_packet_ref_count_dec(p_req_packet);
                    }
                }
            }

            /* ending the DFU */
            if (m_transaction.segments_remaining == 0)
            {
                dfu_end();
                start_rampdown();
            }
        }
        else if (m_state == BL_STATE_RELAY_CANDIDATE || 
                 m_state == BL_STATE_RELAY)
        {
            m_state = BL_STATE_RELAY;
            transport_tx_abort(mp_beacon);
            set_timeout(STATE_TIMEOUT_RELAY);
            do_relay = true;
        }
    }

    if (do_relay)
    {
        relay_packet(p_packet, length);
    }
}