ipaddr.py 文件源码

def previous_nth_usable(value, offset):
    try:
        vtype = ipaddr(value, 'type')
        if vtype == 'address':
            v = ipaddr(value, 'cidr')
        elif vtype == 'network':
            v = ipaddr(value, 'subnet')

        v = netaddr.IPNetwork(v)
    except:
        return False

    if type(offset) != int:
        raise errors.AnsibleFilterError('Must pass in an interger')
    if v.size > 1:
        first_usable, last_usable = _first_last(v)
        nth_ip = int(netaddr.IPAddress(int(v.ip) - offset))
        if nth_ip >= first_usable and nth_ip <= last_usable:
            return str(netaddr.IPAddress(int(v.ip) - offset))