mirror of
https://mau.dev/maunium/synapse.git
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99 lines
3.5 KiB
Python
99 lines
3.5 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014 OpenMarket Ltd
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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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from synapse.api.events.utils import prune_event
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from syutil.jsonutil import encode_canonical_json
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from syutil.base64util import encode_base64, decode_base64
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from syutil.crypto.jsonsign import sign_json
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import hashlib
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import logging
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logger = logging.getLogger(__name__)
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def check_event_content_hash(event, hash_algorithm=hashlib.sha256):
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"""Check whether the hash for this PDU matches the contents"""
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computed_hash = _compute_content_hash(event, hash_algorithm)
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if computed_hash.name not in event.hashes:
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raise Exception("Algorithm %s not in hashes %s" % (
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computed_hash.name, list(event.hashes)
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))
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message_hash_base64 = event.hashes[computed_hash.name]
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try:
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message_hash_bytes = decode_base64(message_hash_base64)
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except:
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raise Exception("Invalid base64: %s" % (message_hash_base64,))
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return message_hash_bytes == computed_hash.digest()
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def _compute_content_hash(event, hash_algorithm):
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event_json = event.get_full_dict()
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# TODO: We need to sign the JSON that is going out via fedaration.
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event_json.pop("age_ts", None)
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event_json.pop("unsigned", None)
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event_json.pop("signatures", None)
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event_json.pop("hashes", None)
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event_json_bytes = encode_canonical_json(event_json)
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return hash_algorithm(event_json_bytes)
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def compute_event_reference_hash(event, hash_algorithm=hashlib.sha256):
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tmp_event = prune_event(event)
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event_json = tmp_event.get_dict()
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event_json.pop("signatures", None)
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event_json.pop("age_ts", None)
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event_json.pop("unsigned", None)
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event_json_bytes = encode_canonical_json(event_json)
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hashed = hash_algorithm(event_json_bytes)
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return (hashed.name, hashed.digest())
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def compute_event_signature(event, signature_name, signing_key):
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tmp_event = prune_event(event)
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redact_json = tmp_event.get_full_dict()
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redact_json.pop("signatures", None)
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redact_json.pop("age_ts", None)
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redact_json.pop("unsigned", None)
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logger.debug("Signing event: %s", redact_json)
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redact_json = sign_json(redact_json, signature_name, signing_key)
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return redact_json["signatures"]
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def add_hashes_and_signatures(event, signature_name, signing_key,
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hash_algorithm=hashlib.sha256):
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if hasattr(event, "old_state_events"):
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state_json_bytes = encode_canonical_json(
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[e.event_id for e in event.old_state_events.values()]
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)
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hashed = hash_algorithm(state_json_bytes)
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event.state_hash = {
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hashed.name: encode_base64(hashed.digest())
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}
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hashed = _compute_content_hash(event, hash_algorithm=hash_algorithm)
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if not hasattr(event, "hashes"):
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event.hashes = {}
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event.hashes[hashed.name] = encode_base64(hashed.digest())
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event.signatures = compute_event_signature(
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event,
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signature_name=signature_name,
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signing_key=signing_key,
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)
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