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#
# Copyright 2012 New Dream Network, LLC (DreamHost)
#
# 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.
"""Utils for publishers
"""
import hashlib
import hmac
from oslo_config import cfg
from oslo_utils import secretutils
OPTS = [
cfg.StrOpt('telemetry_secret',
secret=True,
default='change this for valid signing',
help='Secret value for signing messages. Set value empty if '
'signing is not required to avoid computational overhead.',
deprecated_opts=[cfg.DeprecatedOpt("metering_secret",
"DEFAULT"),
cfg.DeprecatedOpt("metering_secret",
"publisher_rpc"),
cfg.DeprecatedOpt("metering_secret",
"publisher")]
),
]
def decode_unicode(input):
"""Decode the unicode of the message, and encode it into utf-8."""
if isinstance(input, dict):
temp = {}
# If the input data is a dict, create an equivalent dict with a
# predictable insertion order to avoid inconsistencies in the
# message signature computation for equivalent payloads modulo
# ordering
for key, value in sorted(input.items()):
temp[decode_unicode(key)] = decode_unicode(value)
return temp
elif isinstance(input, (tuple, list)):
# When doing a pair of JSON encode/decode operations to the tuple,
# the tuple would become list. So we have to generate the value as
# list here.
return [decode_unicode(element) for element in input]
elif isinstance(input, str):
return input.encode('utf-8')
elif isinstance(input, bytes):
return input.decode('utf-8')
else:
return input
def recursive_keypairs(d, separator=':'):
"""Generator that produces sequence of keypairs for nested dictionaries."""
for name, value in sorted(d.items()):
if isinstance(value, dict):
for subname, subvalue in recursive_keypairs(value, separator):
yield ('%s%s%s' % (name, separator, subname), subvalue)
elif isinstance(value, (tuple, list)):
yield name, decode_unicode(value)
else:
yield name, value
def compute_signature(message, secret):
"""Return the signature for a message dictionary."""
if not secret:
return ''
if isinstance(secret, str):
secret = secret.encode('utf-8')
digest_maker = hmac.new(secret, b'', hashlib.sha256)
for name, value in recursive_keypairs(message):
if name == 'message_signature':
# Skip any existing signature value, which would not have
# been part of the original message.
continue
digest_maker.update(str(name).encode('utf-8'))
digest_maker.update(str(value).encode('utf-8'))
return digest_maker.hexdigest()
def verify_signature(message, secret):
"""Check the signature in the message.
Message is verified against the value computed from the rest of the
contents.
"""
if not secret:
return True
old_sig = message.get('message_signature', '')
new_sig = compute_signature(message, secret)
if isinstance(old_sig, str):
try:
old_sig = old_sig.encode('ascii')
except UnicodeDecodeError:
return False
new_sig = new_sig.encode('ascii')
return secretutils.constant_time_compare(new_sig, old_sig)
def meter_message_from_counter(sample, secret, publisher_id=None):
"""Make a metering message ready to be published or stored.
Returns a dictionary containing a metering message
for a notification message and a Sample instance.
"""
msg = {'source': sample.source,
'counter_name': sample.name,
'counter_type': sample.type,
'counter_unit': sample.unit,
'counter_volume': sample.volume,
'user_id': sample.user_id,
'user_name': sample.user_name,
'project_id': sample.project_id,
'project_name': sample.project_name,
'resource_id': sample.resource_id,
'timestamp': sample.timestamp,
'resource_metadata': sample.resource_metadata,
'message_id': sample.id,
'monotonic_time': sample.monotonic_time,
}
if publisher_id is not None:
msg['publisher_id'] = publisher_id
msg['message_signature'] = compute_signature(msg, secret)
return msg
def message_from_event(event, secret):
"""Make an event message ready to be published or stored.
Returns a serialized model of Event containing an event message
"""
msg = event.serialize()
msg['message_signature'] = compute_signature(msg, secret)
return msg
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