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
|
# -*- coding: utf-8 -*-
# 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
import six
from twisted.internet import defer
from synapse.api.constants import MAX_DEPTH
from synapse.api.errors import Codes, SynapseError
from synapse.crypto.event_signing import check_event_content_hash
from synapse.events import FrozenEvent
from synapse.events.utils import prune_event
from synapse.http.servlet import assert_params_in_request
from synapse.util import logcontext, unwrapFirstError
logger = logging.getLogger(__name__)
class FederationBase(object):
def __init__(self, hs):
self.hs = hs
self.server_name = hs.hostname
self.keyring = hs.get_keyring()
self.spam_checker = hs.get_spam_checker()
self.store = hs.get_datastore()
self._clock = hs.get_clock()
@defer.inlineCallbacks
def _check_sigs_and_hash_and_fetch(self, origin, pdus, outlier=False,
include_none=False):
"""Takes a list of PDUs and checks the signatures and hashs of each
one. If a PDU fails its signature check then we check if we have it in
the database and if not then request if from the originating server of
that PDU.
If a PDU fails its content hash check then it is redacted.
The given list of PDUs are not modified, instead the function returns
a new list.
Args:
pdu (list)
outlier (bool)
Returns:
Deferred : A list of PDUs that have valid signatures and hashes.
"""
deferreds = self._check_sigs_and_hashes(pdus)
@defer.inlineCallbacks
def handle_check_result(pdu, deferred):
try:
res = yield logcontext.make_deferred_yieldable(deferred)
except SynapseError:
res = None
if not res:
# Check local db.
res = yield self.store.get_event(
pdu.event_id,
allow_rejected=True,
allow_none=True,
)
if not res and pdu.origin != origin:
try:
res = yield self.get_pdu(
destinations=[pdu.origin],
event_id=pdu.event_id,
outlier=outlier,
timeout=10000,
)
except SynapseError:
pass
if not res:
logger.warn(
"Failed to find copy of %s with valid signature",
pdu.event_id,
)
defer.returnValue(res)
handle = logcontext.preserve_fn(handle_check_result)
deferreds2 = [
handle(pdu, deferred)
for pdu, deferred in zip(pdus, deferreds)
]
valid_pdus = yield logcontext.make_deferred_yieldable(
defer.gatherResults(
deferreds2,
consumeErrors=True,
)
).addErrback(unwrapFirstError)
if include_none:
defer.returnValue(valid_pdus)
else:
defer.returnValue([p for p in valid_pdus if p])
def _check_sigs_and_hash(self, pdu):
return logcontext.make_deferred_yieldable(
self._check_sigs_and_hashes([pdu])[0],
)
def _check_sigs_and_hashes(self, pdus):
"""Checks that each of the received events is correctly signed by the
sending server.
Args:
pdus (list[FrozenEvent]): the events to be checked
Returns:
list[Deferred]: for each input event, a deferred which:
* returns the original event if the checks pass
* returns a redacted version of the event (if the signature
matched but the hash did not)
* throws a SynapseError if the signature check failed.
The deferreds run their callbacks in the sentinel logcontext.
"""
redacted_pdus = [
prune_event(pdu)
for pdu in pdus
]
deferreds = self.keyring.verify_json_objects_for_server([
(p.origin, p.get_pdu_json())
for p in redacted_pdus
])
ctx = logcontext.LoggingContext.current_context()
def callback(_, pdu, redacted):
with logcontext.PreserveLoggingContext(ctx):
if not check_event_content_hash(pdu):
logger.warn(
"Event content has been tampered, redacting %s: %s",
pdu.event_id, pdu.get_pdu_json()
)
return redacted
if self.spam_checker.check_event_for_spam(pdu):
logger.warn(
"Event contains spam, redacting %s: %s",
pdu.event_id, pdu.get_pdu_json()
)
return redacted
return pdu
def errback(failure, pdu):
failure.trap(SynapseError)
with logcontext.PreserveLoggingContext(ctx):
logger.warn(
"Signature check failed for %s",
pdu.event_id,
)
return failure
for deferred, pdu, redacted in zip(deferreds, pdus, redacted_pdus):
deferred.addCallbacks(
callback, errback,
callbackArgs=[pdu, redacted],
errbackArgs=[pdu],
)
return deferreds
def event_from_pdu_json(pdu_json, outlier=False):
"""Construct a FrozenEvent from an event json received over federation
Args:
pdu_json (object): pdu as received over federation
outlier (bool): True to mark this event as an outlier
Returns:
FrozenEvent
Raises:
SynapseError: if the pdu is missing required fields or is otherwise
not a valid matrix event
"""
# we could probably enforce a bunch of other fields here (room_id, sender,
# origin, etc etc)
assert_params_in_request(pdu_json, ('event_id', 'type', 'depth'))
depth = pdu_json['depth']
if not isinstance(depth, six.integer_types):
raise SynapseError(400, "Depth %r not an intger" % (depth, ),
Codes.BAD_JSON)
if depth < 0:
raise SynapseError(400, "Depth too small", Codes.BAD_JSON)
elif depth > MAX_DEPTH:
raise SynapseError(400, "Depth too large", Codes.BAD_JSON)
event = FrozenEvent(
pdu_json
)
event.internal_metadata.outlier = outlier
return event
|
