def get_seq_diff(seq_tuple):
    """Returns the difference between two TCP sequence numbers."""

    (seq_min, seq_max) = seq_tuple

    if None in (seq_min, seq_max) or 0 in (seq_min, seq_max):
        return None

    # Seq wrap-around
    diff = seq_max - seq_min
    if diff < 0:
        diff += 2 ** 32

    return diff