98 lines
3.3 KiB
Python
98 lines
3.3 KiB
Python
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# Copyright 2020-present MongoDB, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Utilities for caching OCSP responses."""
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from collections import namedtuple
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from datetime import datetime as _datetime
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from datetime import timezone
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from pymongo.lock import _create_lock
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class _OCSPCache:
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"""A cache for OCSP responses."""
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CACHE_KEY_TYPE = namedtuple( # type: ignore
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"OcspResponseCacheKey",
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["hash_algorithm", "issuer_name_hash", "issuer_key_hash", "serial_number"],
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)
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def __init__(self):
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self._data = {}
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# Hold this lock when accessing _data.
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self._lock = _create_lock()
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def _get_cache_key(self, ocsp_request):
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return self.CACHE_KEY_TYPE(
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hash_algorithm=ocsp_request.hash_algorithm.name.lower(),
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issuer_name_hash=ocsp_request.issuer_name_hash,
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issuer_key_hash=ocsp_request.issuer_key_hash,
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serial_number=ocsp_request.serial_number,
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)
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def __setitem__(self, key, value):
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"""Add/update a cache entry.
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'key' is of type cryptography.x509.ocsp.OCSPRequest
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'value' is of type cryptography.x509.ocsp.OCSPResponse
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Validity of the OCSP response must be checked by caller.
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"""
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with self._lock:
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cache_key = self._get_cache_key(key)
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# As per the OCSP protocol, if the response's nextUpdate field is
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# not set, the responder is indicating that newer revocation
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# information is available all the time.
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if value.next_update is None:
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self._data.pop(cache_key, None)
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return
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# Do nothing if the response is invalid.
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if not (
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value.this_update
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<= _datetime.now(tz=timezone.utc).replace(tzinfo=None)
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< value.next_update
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):
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return
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# Cache new response OR update cached response if new response
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# has longer validity.
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cached_value = self._data.get(cache_key, None)
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if cached_value is None or cached_value.next_update < value.next_update:
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self._data[cache_key] = value
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def __getitem__(self, item):
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"""Get a cache entry if it exists.
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'item' is of type cryptography.x509.ocsp.OCSPRequest
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Raises KeyError if the item is not in the cache.
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"""
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with self._lock:
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cache_key = self._get_cache_key(item)
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value = self._data[cache_key]
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# Return cached response if it is still valid.
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if (
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value.this_update
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<= _datetime.now(tz=timezone.utc).replace(tzinfo=None)
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< value.next_update
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):
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return value
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self._data.pop(cache_key, None)
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raise KeyError(cache_key)
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