245 lines
9.0 KiB
Python
245 lines
9.0 KiB
Python
# Copyright 2015, 2016 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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import logging
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from io import BytesIO
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from twisted.internet import defer
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from twisted.web.resource import Resource
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from twisted.web.server import NOT_DONE_YET
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from synapse.api.errors import Codes, SynapseError
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from synapse.crypto.keyring import KeyLookupError, ServerKeyFetcher
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from synapse.http.server import respond_with_json_bytes, wrap_json_request_handler
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from synapse.http.servlet import parse_integer, parse_json_object_from_request
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logger = logging.getLogger(__name__)
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class RemoteKey(Resource):
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"""HTTP resource for retreiving the TLS certificate and NACL signature
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verification keys for a collection of servers. Checks that the reported
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X.509 TLS certificate matches the one used in the HTTPS connection. Checks
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that the NACL signature for the remote server is valid. Returns a dict of
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JSON signed by both the remote server and by this server.
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Supports individual GET APIs and a bulk query POST API.
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Requsts:
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GET /_matrix/key/v2/query/remote.server.example.com HTTP/1.1
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GET /_matrix/key/v2/query/remote.server.example.com/a.key.id HTTP/1.1
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POST /_matrix/v2/query HTTP/1.1
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Content-Type: application/json
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{
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"server_keys": {
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"remote.server.example.com": {
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"a.key.id": {
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"minimum_valid_until_ts": 1234567890123
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}
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}
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}
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}
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Response:
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HTTP/1.1 200 OK
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Content-Type: application/json
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{
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"server_keys": [
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{
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"server_name": "remote.server.example.com"
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"valid_until_ts": # posix timestamp
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"verify_keys": {
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"a.key.id": { # The identifier for a key.
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key: "" # base64 encoded verification key.
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}
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}
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"old_verify_keys": {
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"an.old.key.id": { # The identifier for an old key.
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key: "", # base64 encoded key
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"expired_ts": 0, # when the key stop being used.
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}
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}
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"tls_fingerprints": [
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{ "sha256": # fingerprint }
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]
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"signatures": {
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"remote.server.example.com": {...}
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"this.server.example.com": {...}
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}
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}
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]
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}
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"""
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isLeaf = True
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def __init__(self, hs):
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self.fetcher = ServerKeyFetcher(hs)
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self.store = hs.get_datastore()
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self.clock = hs.get_clock()
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self.federation_domain_whitelist = hs.config.federation_domain_whitelist
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def render_GET(self, request):
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self.async_render_GET(request)
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return NOT_DONE_YET
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@wrap_json_request_handler
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@defer.inlineCallbacks
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def async_render_GET(self, request):
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if len(request.postpath) == 1:
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server, = request.postpath
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query = {server.decode('ascii'): {}}
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elif len(request.postpath) == 2:
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server, key_id = request.postpath
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minimum_valid_until_ts = parse_integer(
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request, "minimum_valid_until_ts"
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)
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arguments = {}
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if minimum_valid_until_ts is not None:
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arguments["minimum_valid_until_ts"] = minimum_valid_until_ts
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query = {server.decode('ascii'): {key_id.decode('ascii'): arguments}}
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else:
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raise SynapseError(
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404, "Not found %r" % request.postpath, Codes.NOT_FOUND
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)
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yield self.query_keys(request, query, query_remote_on_cache_miss=True)
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def render_POST(self, request):
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self.async_render_POST(request)
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return NOT_DONE_YET
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@wrap_json_request_handler
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@defer.inlineCallbacks
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def async_render_POST(self, request):
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content = parse_json_object_from_request(request)
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query = content["server_keys"]
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yield self.query_keys(request, query, query_remote_on_cache_miss=True)
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@defer.inlineCallbacks
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def query_keys(self, request, query, query_remote_on_cache_miss=False):
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logger.info("Handling query for keys %r", query)
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store_queries = []
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for server_name, key_ids in query.items():
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if (
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self.federation_domain_whitelist is not None and
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server_name not in self.federation_domain_whitelist
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):
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logger.debug("Federation denied with %s", server_name)
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continue
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if not key_ids:
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key_ids = (None,)
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for key_id in key_ids:
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store_queries.append((server_name, key_id, None))
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cached = yield self.store.get_server_keys_json(store_queries)
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json_results = set()
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time_now_ms = self.clock.time_msec()
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cache_misses = dict()
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for (server_name, key_id, from_server), results in cached.items():
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results = [
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(result["ts_added_ms"], result) for result in results
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]
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if not results and key_id is not None:
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cache_misses.setdefault(server_name, set()).add(key_id)
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continue
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if key_id is not None:
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ts_added_ms, most_recent_result = max(results)
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ts_valid_until_ms = most_recent_result["ts_valid_until_ms"]
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req_key = query.get(server_name, {}).get(key_id, {})
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req_valid_until = req_key.get("minimum_valid_until_ts")
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miss = False
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if req_valid_until is not None:
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if ts_valid_until_ms < req_valid_until:
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logger.debug(
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"Cached response for %r/%r is older than requested"
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": valid_until (%r) < minimum_valid_until (%r)",
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server_name, key_id,
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ts_valid_until_ms, req_valid_until
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)
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miss = True
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else:
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logger.debug(
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"Cached response for %r/%r is newer than requested"
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": valid_until (%r) >= minimum_valid_until (%r)",
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server_name, key_id,
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ts_valid_until_ms, req_valid_until
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)
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elif (ts_added_ms + ts_valid_until_ms) / 2 < time_now_ms:
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logger.debug(
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"Cached response for %r/%r is too old"
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": (added (%r) + valid_until (%r)) / 2 < now (%r)",
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server_name, key_id,
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ts_added_ms, ts_valid_until_ms, time_now_ms
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)
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# We more than half way through the lifetime of the
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# response. We should fetch a fresh copy.
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miss = True
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else:
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logger.debug(
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"Cached response for %r/%r is still valid"
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": (added (%r) + valid_until (%r)) / 2 < now (%r)",
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server_name, key_id,
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ts_added_ms, ts_valid_until_ms, time_now_ms
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)
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if miss:
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cache_misses.setdefault(server_name, set()).add(key_id)
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json_results.add(bytes(most_recent_result["key_json"]))
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else:
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for ts_added, result in results:
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json_results.add(bytes(result["key_json"]))
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if cache_misses and query_remote_on_cache_miss:
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for server_name, key_ids in cache_misses.items():
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try:
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yield self.fetcher.get_server_verify_key_v2_direct(
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server_name, key_ids
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)
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except KeyLookupError as e:
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logger.info("Failed to fetch key: %s", e)
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except Exception:
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logger.exception("Failed to get key for %r", server_name)
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yield self.query_keys(
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request, query, query_remote_on_cache_miss=False
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)
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else:
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result_io = BytesIO()
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result_io.write(b"{\"server_keys\":")
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sep = b"["
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for json_bytes in json_results:
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result_io.write(sep)
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result_io.write(json_bytes)
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sep = b","
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if sep == b"[":
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result_io.write(sep)
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result_io.write(b"]}")
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respond_with_json_bytes(
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request, 200, result_io.getvalue(),
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)
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