summary refs log tree commit diff
path: root/synapse/federation/federation_base.py
blob: f0430b2cb1164f4fc4c228bdadd3e2c480d661bd (plain) (blame)
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
# -*- coding: utf-8 -*-
# Copyright 2015 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.


from twisted.internet import defer

from synapse.events.utils import prune_event

from syutil.jsonutil import encode_canonical_json

from synapse.crypto.event_signing import check_event_content_hash

from synapse.api.errors import SynapseError

from synapse.util import unwrapFirstError

import logging


logger = logging.getLogger(__name__)


class FederationBase(object):
    @defer.inlineCallbacks
    def _check_sigs_and_hash_and_fetch(self, origin, pdus, outlier=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.
        """

        signed_pdus = []

        @defer.inlineCallbacks
        def do(pdu):
            try:
                new_pdu = yield self._check_sigs_and_hash(pdu)
                signed_pdus.append(new_pdu)
            except SynapseError:
                # FIXME: We should handle signature failures more gracefully.

                # Check local db.
                new_pdu = yield self.store.get_event(
                    pdu.event_id,
                    allow_rejected=True,
                    allow_none=True,
                )
                if new_pdu:
                    signed_pdus.append(new_pdu)
                    return

                # Check pdu.origin
                if pdu.origin != origin:
                    try:
                        new_pdu = yield self.get_pdu(
                            destinations=[pdu.origin],
                            event_id=pdu.event_id,
                            outlier=outlier,
                            timeout=10000,
                        )

                        if new_pdu:
                            signed_pdus.append(new_pdu)
                            return
                    except:
                        pass

                logger.warn(
                    "Failed to find copy of %s with valid signature",
                    pdu.event_id,
                )

        yield defer.gatherResults(
            [do(pdu) for pdu in pdus],
            consumeErrors=True
        ).addErrback(unwrapFirstError)

        defer.returnValue(signed_pdus)

    @defer.inlineCallbacks
    def _check_sigs_and_hash(self, pdu):
        """Throws a SynapseError if the PDU does not have the correct
        signatures.

        Returns:
            FrozenEvent: Either the given event or it redacted if it failed the
            content hash check.
        """
        # Check signatures are correct.
        redacted_event = prune_event(pdu)
        redacted_pdu_json = redacted_event.get_pdu_json()

        try:
            yield self.keyring.verify_json_for_server(
                pdu.origin, redacted_pdu_json
            )
        except SynapseError:
            logger.warn(
                "Signature check failed for %s redacted to %s",
                encode_canonical_json(pdu.get_pdu_json()),
                encode_canonical_json(redacted_pdu_json),
            )
            raise

        if not check_event_content_hash(pdu):
            logger.warn(
                "Event content has been tampered, redacting %s, %s",
                pdu.event_id, encode_canonical_json(pdu.get_dict())
            )
            defer.returnValue(redacted_event)

        defer.returnValue(pdu)