utils.py 文件源码

def get_prefix_info(addr):
    """Returns the smallest prefix from the NAVdb that an IP address fits into.

    :param addr: An IP address string.
    :returns: A Prefix object or None if no prefixes matched.

    """
    try:
        return Prefix.objects.select_related().extra(
            select={"mask_size": "masklen(netaddr)"},
            where=["%s << netaddr AND nettype <> 'scope'"],
            order_by=["-mask_size"],
            params=[addr]
        )[0]
    except (IndexError, DatabaseError):
        return None