1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
|
# Copyright 2015, 2016 OpenMarket Ltd
#
# 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.
import logging
from typing import Dict, Set
from signedjson.sign import sign_json
from synapse.api.errors import Codes, SynapseError
from synapse.crypto.keyring import ServerKeyFetcher
from synapse.http.server import DirectServeJsonResource, respond_with_json
from synapse.http.servlet import parse_integer, parse_json_object_from_request
from synapse.util import json_decoder
logger = logging.getLogger(__name__)
class RemoteKey(DirectServeJsonResource):
"""HTTP resource for retrieving the TLS certificate and NACL signature
verification keys for a collection of servers. Checks that the reported
X.509 TLS certificate matches the one used in the HTTPS connection. Checks
that the NACL signature for the remote server is valid. Returns a dict of
JSON signed by both the remote server and by this server.
Supports individual GET APIs and a bulk query POST API.
Requests:
GET /_matrix/key/v2/query/remote.server.example.com HTTP/1.1
GET /_matrix/key/v2/query/remote.server.example.com/a.key.id HTTP/1.1
POST /_matrix/v2/query HTTP/1.1
Content-Type: application/json
{
"server_keys": {
"remote.server.example.com": {
"a.key.id": {
"minimum_valid_until_ts": 1234567890123
}
}
}
}
Response:
HTTP/1.1 200 OK
Content-Type: application/json
{
"server_keys": [
{
"server_name": "remote.server.example.com"
"valid_until_ts": # posix timestamp
"verify_keys": {
"a.key.id": { # The identifier for a key.
key: "" # base64 encoded verification key.
}
}
"old_verify_keys": {
"an.old.key.id": { # The identifier for an old key.
key: "", # base64 encoded key
"expired_ts": 0, # when the key stop being used.
}
}
"tls_fingerprints": [
{ "sha256": # fingerprint }
]
"signatures": {
"remote.server.example.com": {...}
"this.server.example.com": {...}
}
}
]
}
"""
isLeaf = True
def __init__(self, hs):
super().__init__()
self.fetcher = ServerKeyFetcher(hs)
self.store = hs.get_datastore()
self.clock = hs.get_clock()
self.federation_domain_whitelist = hs.config.federation_domain_whitelist
self.config = hs.config
async def _async_render_GET(self, request):
if len(request.postpath) == 1:
(server,) = request.postpath
query = {server.decode("ascii"): {}} # type: dict
elif len(request.postpath) == 2:
server, key_id = request.postpath
minimum_valid_until_ts = parse_integer(request, "minimum_valid_until_ts")
arguments = {}
if minimum_valid_until_ts is not None:
arguments["minimum_valid_until_ts"] = minimum_valid_until_ts
query = {server.decode("ascii"): {key_id.decode("ascii"): arguments}}
else:
raise SynapseError(404, "Not found %r" % request.postpath, Codes.NOT_FOUND)
await self.query_keys(request, query, query_remote_on_cache_miss=True)
async def _async_render_POST(self, request):
content = parse_json_object_from_request(request)
query = content["server_keys"]
await self.query_keys(request, query, query_remote_on_cache_miss=True)
async def query_keys(self, request, query, query_remote_on_cache_miss=False):
logger.info("Handling query for keys %r", query)
store_queries = []
for server_name, key_ids in query.items():
if (
self.federation_domain_whitelist is not None
and server_name not in self.federation_domain_whitelist
):
logger.debug("Federation denied with %s", server_name)
continue
if not key_ids:
key_ids = (None,)
for key_id in key_ids:
store_queries.append((server_name, key_id, None))
cached = await self.store.get_server_keys_json(store_queries)
json_results = set()
time_now_ms = self.clock.time_msec()
cache_misses = {} # type: Dict[str, Set[str]]
for (server_name, key_id, from_server), results in cached.items():
results = [(result["ts_added_ms"], result) for result in results]
if not results and key_id is not None:
cache_misses.setdefault(server_name, set()).add(key_id)
continue
if key_id is not None:
ts_added_ms, most_recent_result = max(results)
ts_valid_until_ms = most_recent_result["ts_valid_until_ms"]
req_key = query.get(server_name, {}).get(key_id, {})
req_valid_until = req_key.get("minimum_valid_until_ts")
miss = False
if req_valid_until is not None:
if ts_valid_until_ms < req_valid_until:
logger.debug(
"Cached response for %r/%r is older than requested"
": valid_until (%r) < minimum_valid_until (%r)",
server_name,
key_id,
ts_valid_until_ms,
req_valid_until,
)
miss = True
else:
logger.debug(
"Cached response for %r/%r is newer than requested"
": valid_until (%r) >= minimum_valid_until (%r)",
server_name,
key_id,
ts_valid_until_ms,
req_valid_until,
)
elif (ts_added_ms + ts_valid_until_ms) / 2 < time_now_ms:
logger.debug(
"Cached response for %r/%r is too old"
": (added (%r) + valid_until (%r)) / 2 < now (%r)",
server_name,
key_id,
ts_added_ms,
ts_valid_until_ms,
time_now_ms,
)
# We more than half way through the lifetime of the
# response. We should fetch a fresh copy.
miss = True
else:
logger.debug(
"Cached response for %r/%r is still valid"
": (added (%r) + valid_until (%r)) / 2 < now (%r)",
server_name,
key_id,
ts_added_ms,
ts_valid_until_ms,
time_now_ms,
)
if miss:
cache_misses.setdefault(server_name, set()).add(key_id)
# Cast to bytes since postgresql returns a memoryview.
json_results.add(bytes(most_recent_result["key_json"]))
else:
for ts_added, result in results:
# Cast to bytes since postgresql returns a memoryview.
json_results.add(bytes(result["key_json"]))
# If there is a cache miss, request the missing keys, then recurse (and
# ensure the result is sent).
if cache_misses and query_remote_on_cache_miss:
await self.fetcher.get_keys(cache_misses)
await self.query_keys(request, query, query_remote_on_cache_miss=False)
else:
signed_keys = []
for key_json in json_results:
key_json = json_decoder.decode(key_json.decode("utf-8"))
for signing_key in self.config.key_server_signing_keys:
key_json = sign_json(key_json, self.config.server_name, signing_key)
signed_keys.append(key_json)
results = {"server_keys": signed_keys}
respond_with_json(request, 200, results, canonical_json=True)
|
