Source code for jfscripts.dns_ipv6_prefix

#! /usr/bin/env python3

from jfscripts import __version__
import argparse
import ipaddress
import socket


def get_ipv6(dns_name):
    result = socket.getaddrinfo(dns_name, port=None)

    for entry in result:
        #
        # entry:
        #
        # (family, type, proto, canonname, sockaddr)
        #
        # (
        #     <AddressFamily.AF_INET6: 10>,
        #     <SocketKind.SOCK_RAW: 3>,
        #     0,
        #     '',
        #     ('2003:68:4c06:3300:1e98:ecff:fe0f:d330', 0, 0, 0)
        # )
        if entry[0] == 10 and entry[2] == 0:
            return entry[4][0]


def get_parser():
    """The argument parser for the command line interface.

    :return: A ArgumentParser object.
    :rtype: argparse.ArgumentParser
    """
    parser = argparse.ArgumentParser(
        description='Get the ipv6 prefix from a DNS name.'
    )

    parser.add_argument(
        'dnsname',
        help='The DNS name, e. g. josef-friedrich.de',
    )

    parser.add_argument(
        '-V',
        '--version',
        action='version',
        version='%(prog)s {version}'.format(version=__version__),
    )

    return parser


def main():
    args = get_parser().parse_args()

    ipv6 = get_ipv6(args.dnsname)

    prefix = ipaddress.ip_network(ipv6 + '/64', strict=False)

    print(prefix)


if __name__ == '__main__':
    main()