#!/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"]
[docs]
@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()