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# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2019 New Vector 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 unittest.mock import Mock
from twisted.internet import defer
from twisted.internet.defer import Deferred
from twisted.internet.error import ConnectError
from twisted.names import dns, error
from synapse.http.federation.srv_resolver import SrvResolver
from synapse.logging.context import LoggingContext, current_context
from tests import unittest
from tests.utils import MockClock
class SrvResolverTestCase(unittest.TestCase):
def test_resolve(self):
dns_client_mock = Mock()
service_name = b"test_service.example.com"
host_name = b"example.com"
answer_srv = dns.RRHeader(
type=dns.SRV, payload=dns.Record_SRV(target=host_name)
)
result_deferred = Deferred()
dns_client_mock.lookupService.return_value = result_deferred
cache = {}
resolver = SrvResolver(dns_client=dns_client_mock, cache=cache)
@defer.inlineCallbacks
def do_lookup():
with LoggingContext("one") as ctx:
resolve_d = resolver.resolve_service(service_name)
result = yield defer.ensureDeferred(resolve_d)
# should have restored our context
self.assertIs(current_context(), ctx)
return result
test_d = do_lookup()
self.assertNoResult(test_d)
dns_client_mock.lookupService.assert_called_once_with(service_name)
result_deferred.callback(([answer_srv], None, None))
servers = self.successResultOf(test_d)
self.assertEqual(len(servers), 1)
self.assertEqual(servers, cache[service_name])
self.assertEqual(servers[0].host, host_name)
@defer.inlineCallbacks
def test_from_cache_expired_and_dns_fail(self):
dns_client_mock = Mock()
dns_client_mock.lookupService.return_value = defer.fail(error.DNSServerError())
service_name = b"test_service.example.com"
entry = Mock(spec_set=["expires", "priority", "weight"])
entry.expires = 0
entry.priority = 0
entry.weight = 0
cache = {service_name: [entry]}
resolver = SrvResolver(dns_client=dns_client_mock, cache=cache)
servers = yield defer.ensureDeferred(resolver.resolve_service(service_name))
dns_client_mock.lookupService.assert_called_once_with(service_name)
self.assertEqual(len(servers), 1)
self.assertEqual(servers, cache[service_name])
@defer.inlineCallbacks
def test_from_cache(self):
clock = MockClock()
dns_client_mock = Mock(spec_set=["lookupService"])
dns_client_mock.lookupService = Mock(spec_set=[])
service_name = b"test_service.example.com"
entry = Mock(spec_set=["expires", "priority", "weight"])
entry.expires = 999999999
entry.priority = 0
entry.weight = 0
cache = {service_name: [entry]}
resolver = SrvResolver(
dns_client=dns_client_mock, cache=cache, get_time=clock.time
)
servers = yield defer.ensureDeferred(resolver.resolve_service(service_name))
self.assertFalse(dns_client_mock.lookupService.called)
self.assertEqual(len(servers), 1)
self.assertEqual(servers, cache[service_name])
@defer.inlineCallbacks
def test_empty_cache(self):
dns_client_mock = Mock()
dns_client_mock.lookupService.return_value = defer.fail(error.DNSServerError())
service_name = b"test_service.example.com"
cache = {}
resolver = SrvResolver(dns_client=dns_client_mock, cache=cache)
with self.assertRaises(error.DNSServerError):
yield defer.ensureDeferred(resolver.resolve_service(service_name))
@defer.inlineCallbacks
def test_name_error(self):
dns_client_mock = Mock()
dns_client_mock.lookupService.return_value = defer.fail(error.DNSNameError())
service_name = b"test_service.example.com"
cache = {}
resolver = SrvResolver(dns_client=dns_client_mock, cache=cache)
servers = yield defer.ensureDeferred(resolver.resolve_service(service_name))
self.assertEqual(len(servers), 0)
self.assertEqual(len(cache), 0)
def test_disabled_service(self):
"""
test the behaviour when there is a single record which is ".".
"""
service_name = b"test_service.example.com"
lookup_deferred = Deferred()
dns_client_mock = Mock()
dns_client_mock.lookupService.return_value = lookup_deferred
cache = {}
resolver = SrvResolver(dns_client=dns_client_mock, cache=cache)
# Old versions of Twisted don't have an ensureDeferred in failureResultOf.
resolve_d = defer.ensureDeferred(resolver.resolve_service(service_name))
# returning a single "." should make the lookup fail with a ConenctError
lookup_deferred.callback(
(
[dns.RRHeader(type=dns.SRV, payload=dns.Record_SRV(target=b"."))],
None,
None,
)
)
self.failureResultOf(resolve_d, ConnectError)
def test_non_srv_answer(self):
"""
test the behaviour when the dns server gives us a spurious non-SRV response
"""
service_name = b"test_service.example.com"
lookup_deferred = Deferred()
dns_client_mock = Mock()
dns_client_mock.lookupService.return_value = lookup_deferred
cache = {}
resolver = SrvResolver(dns_client=dns_client_mock, cache=cache)
# Old versions of Twisted don't have an ensureDeferred in successResultOf.
resolve_d = defer.ensureDeferred(resolver.resolve_service(service_name))
lookup_deferred.callback(
(
[
dns.RRHeader(type=dns.A, payload=dns.Record_A()),
dns.RRHeader(type=dns.SRV, payload=dns.Record_SRV(target=b"host")),
],
None,
None,
)
)
servers = self.successResultOf(resolve_d)
self.assertEqual(len(servers), 1)
self.assertEqual(servers, cache[service_name])
self.assertEqual(servers[0].host, b"host")
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