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