# Source code for taurus.core.util.fqdn

    #!/usr/bin/env python

    # ###########################################################################
    #
    # This file is part of Taurus
    #
    # http://taurus-scada.org
    #
    # Copyright 2011 CELLS / ALBA Synchrotron, Bellaterra, Spain
    #
    # Taurus is free software: you can redistribute it and/or modify
    # it under the terms of the GNU Lesser General Public License as published by
    # the Free Software Foundation, either version 3 of the License, or
    # (at your option) any later version.
    #
    # Taurus is distributed in the hope that it will be useful,
    # but WITHOUT ANY WARRANTY; without even the implied warranty of
    # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    # GNU Lesser General Public License for more details.
    #
    # You should have received a copy of the GNU Lesser General Public License
    # along with Taurus.  If not, see <http://www.gnu.org/licenses/>.
    #
    # ###########################################################################
    """
    This module contains provides the fqdn_no_alias function.
    """

    import socket
    from taurus import warning
    from functools import lru_cache

    __all__ = ["fqdn_no_alias"]

    @lru_cache(maxsize=64)
    def fqdn_no_alias(hostname):
        """
        Normalize hostname so that it is a full name (including domain name).

        .. note:: this is similar to socket.getfqdn, but it avoids translating
                  aliases into their "real" address.
        """
        if hostname == "localhost" or "." in hostname:
            # optimization: leave localhost or names including domain as they are
            return hostname
        try:
            real, aliases, _ = socket.gethostbyname_ex(hostname)
        except (socket.gaierror, socket.herror):
            # return the given hostname in case of error
            return hostname

        if aliases:
            if hostname == real or hostname in aliases:
                # in some corner cases (e.g. when defining several aliases in a
                # hosts file), the hostname may be one of the aliases.
                return hostname

            # return alias if it exists
            if len(aliases) > 1:
                # warn in the (unusual) case that there is more than 1 alias
                warning(
                    "fqdn_no_alias: %s has %d aliases. Using the first one",
                    hostname,
                    len(aliases),
                )
            return aliases[0]
        else:
            # if there are no aliases, return real
            return real

    if __name__ == "__main__":

        # TODO: once we move to PyTest, test_fqdn_no_alias could be put in the
        #       official tests (test_fqdn_no_alias_local would require to be
        #       generalized)

        def test_fqdn_no_alias():
            """tests for test_fqdn_no_alias"""
            assert fqdn_no_alias("NONEXISTENT") == "NONEXISTENT"
            # test localhost
            assert fqdn_no_alias("localhost") == "localhost"
            # test with an aliased full hostname+domain (alias should not resolv!)
            print(socket.gethostbyname_ex("mail.google.com"))
            print("socket.getfqdn:", socket.getfqdn("mail.google.com"))
            assert fqdn_no_alias("mail.google.com") == "mail.google.com"

        def test_fqdn_no_alias_local(name="www"):
            import re

            # test with an existent host in your domain
            print(socket.gethostbyname_ex(name))
            print("socket.getfqdn:", socket.getfqdn(name))
            assert re.match(name + r"\.[a-zA-Z0-9\.-]+", fqdn_no_alias(name))

        test_fqdn_no_alias()
        test_fqdn_no_alias_local()