121 lines
4.0 KiB
Python
121 lines
4.0 KiB
Python
#
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# Copyright 2012 New Dream Network, LLC (DreamHost)
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Utils for publishers
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"""
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import hashlib
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import hmac
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from oslo_config import cfg
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import six
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from ceilometer import utils
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OPTS = [
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cfg.StrOpt('metering_secret',
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secret=True,
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default='change this or be hacked',
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help='Secret value for signing metering messages.',
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deprecated_opts=[cfg.DeprecatedOpt("metering_secret",
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"DEFAULT"),
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cfg.DeprecatedOpt("metering_secret",
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"publisher_rpc")]
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),
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]
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cfg.CONF.register_opts(OPTS, group="publisher")
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def compute_signature(message, secret):
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"""Return the signature for a message dictionary."""
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digest_maker = hmac.new(secret, '', hashlib.sha256)
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for name, value in utils.recursive_keypairs(message):
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if name == 'message_signature':
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# Skip any existing signature value, which would not have
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# been part of the original message.
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continue
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digest_maker.update(six.text_type(name).encode('utf-8'))
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digest_maker.update(six.text_type(value).encode('utf-8'))
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return digest_maker.hexdigest()
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def besteffort_compare_digest(first, second):
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"""Returns True if both string inputs are equal, otherwise False.
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This function should take a constant amount of time regardless of
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how many characters in the strings match.
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"""
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# NOTE(sileht): compare_digest method protected for timing-attacks
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# exists since python >= 2.7.7 and python >= 3.3
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# this a bit less-secure python fallback version
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# taken from https://github.com/openstack/python-keystoneclient/blob/
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# master/keystoneclient/middleware/memcache_crypt.py#L88
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if len(first) != len(second):
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return False
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result = 0
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if six.PY3 and isinstance(first, bytes) and isinstance(second, bytes):
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for x, y in zip(first, second):
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result |= x ^ y
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else:
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for x, y in zip(first, second):
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result |= ord(x) ^ ord(y)
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return result == 0
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if hasattr(hmac, 'compare_digest'):
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compare_digest = hmac.compare_digest
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else:
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compare_digest = besteffort_compare_digest
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def verify_signature(message, secret):
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"""Check the signature in the message.
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Message is verified against the value computed from the rest of the
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contents.
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"""
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old_sig = message.get('message_signature', '')
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new_sig = compute_signature(message, secret)
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if isinstance(old_sig, six.text_type):
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try:
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old_sig = old_sig.encode('ascii')
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except UnicodeDecodeError:
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return False
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return compare_digest(new_sig, old_sig)
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def meter_message_from_counter(sample, secret):
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"""Make a metering message ready to be published or stored.
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Returns a dictionary containing a metering message
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for a notification message and a Sample instance.
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"""
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msg = {'source': sample.source,
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'counter_name': sample.name,
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'counter_type': sample.type,
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'counter_unit': sample.unit,
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'counter_volume': sample.volume,
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'user_id': sample.user_id,
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'project_id': sample.project_id,
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'resource_id': sample.resource_id,
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'timestamp': sample.timestamp,
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'resource_metadata': sample.resource_metadata,
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'message_id': sample.id,
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}
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msg['message_signature'] = compute_signature(msg, secret)
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return msg
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