ec2-api/ec2api/utils.py
Feodor Tersin b27f4feab5 EC2 metadata implementation
Change-Id: I7d3ba06c420e4f70cc01fd0ec64398a4c3405244
2015-01-16 01:19:26 +04:00

90 lines
2.6 KiB
Python

# Copyright 2014
# The Cloudscaling Group, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Utilities and helper functions."""
import contextlib
import hmac
import shutil
import socket
import tempfile
from oslo.config import cfg
from ec2api.openstack.common.gettextutils import _
from ec2api.openstack.common import log as logging
utils_opts = [
cfg.StrOpt('tempdir',
help='Explicitly specify the temporary working directory'),
]
CONF = cfg.CONF
CONF.register_opts(utils_opts)
LOG = logging.getLogger(__name__)
def _get_my_ip():
"""Returns the actual ip of the local machine.
This code figures out what source address would be used if some traffic
were to be sent out to some well known address on the Internet. In this
case, a Google DNS server is used, but the specific address does not
matter much. No traffic is actually sent.
"""
try:
csock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
csock.connect(('8.8.8.8', 80))
(addr, port) = csock.getsockname()
csock.close()
return addr
except socket.error:
# TODO(Alex) nova's code has a backup plan in this case.
# We might want to move the code here as well
return '127.0.0.1'
@contextlib.contextmanager
def tempdir(**kwargs):
argdict = kwargs.copy()
if 'dir' not in argdict:
argdict['dir'] = CONF.tempdir
tmpdir = tempfile.mkdtemp(**argdict)
try:
yield tmpdir
finally:
try:
shutil.rmtree(tmpdir)
except OSError as e:
LOG.error(_('Could not remove tmpdir: %s'), str(e))
if hasattr(hmac, 'compare_digest'):
constant_time_compare = hmac.compare_digest
else:
def constant_time_compare(first, second):
"""Returns True if both string inputs are equal, otherwise False.
This function should take a constant amount of time regardless of
how many characters in the strings match.
"""
if len(first) != len(second):
return False
result = 0
for x, y in zip(first, second):
result |= ord(x) ^ ord(y)
return result == 0