utils.py 文件源码

def hostname(ip):
    """
    Performs a DNS reverse lookup for an IP address and caches the result in
    a global variable, which is really, really stupid.

    :param ip: And IP address string.
    :returns: A hostname string or a False value if the lookup failed.

    """
    addr = unicode(ip)
    if addr in _cached_hostname:
        return _cached_hostname[addr]

    try:
        dns = gethostbyaddr(addr)
    except herror:
        return False

    _cached_hostname[addr] = dns[0]
    return dns[0]