MM_VARIABLE_GET_NEXT_HEADER_SIZE
if (in_name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE)
if (out_name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE)
max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE;
payload_size = MM_VARIABLE_GET_NEXT_HEADER_SIZE + out_name_size;