# # This file is licensed under the Affero General Public License (AGPL) version 3. # # Copyright 2014-2016 OpenMarket Ltd # Copyright (C) 2023 New Vector, Ltd # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU Affero General Public License as # published by the Free Software Foundation, either version 3 of the # License, or (at your option) any later version. # # See the GNU Affero General Public License for more details: # . # # Originally licensed under the Apache License, Version 2.0: # . # # [This file includes modifications made by New Vector Limited] # # from typing import Dict, Generator, List, Tuple, cast 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 Server, 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) -> None: 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[Tuple[List[dns.RRHeader], None, None]]" = Deferred() dns_client_mock.lookupService.return_value = result_deferred cache: Dict[bytes, List[Server]] = {} resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) @defer.inlineCallbacks def do_lookup() -> Generator["Deferred[object]", object, List[Server]]: with LoggingContext("one") as ctx: resolve_d = resolver.resolve_service(service_name) result: List[Server] result = yield defer.ensureDeferred(resolve_d) # type: ignore[assignment] # 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, ) -> Generator["Deferred[object]", object, None]: 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: [cast(Server, entry)]} resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) servers: List[Server] servers = yield defer.ensureDeferred( resolver.resolve_service(service_name) ) # type: ignore[assignment] 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) -> Generator["Deferred[object]", object, None]: 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: [cast(Server, entry)]} resolver = SrvResolver( dns_client=dns_client_mock, cache=cache, get_time=clock.time ) servers: List[Server] servers = yield defer.ensureDeferred( resolver.resolve_service(service_name) ) # type: ignore[assignment] 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) -> Generator["Deferred[object]", object, None]: dns_client_mock = Mock() dns_client_mock.lookupService.return_value = defer.fail(error.DNSServerError()) service_name = b"test_service.example.com" cache: Dict[bytes, List[Server]] = {} 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) -> Generator["Deferred[object]", object, None]: dns_client_mock = Mock() dns_client_mock.lookupService.return_value = defer.fail(error.DNSNameError()) service_name = b"test_service.example.com" cache: Dict[bytes, List[Server]] = {} resolver = SrvResolver(dns_client=dns_client_mock, cache=cache) servers: List[Server] servers = yield defer.ensureDeferred( resolver.resolve_service(service_name) ) # type: ignore[assignment] self.assertEqual(len(servers), 0) self.assertEqual(len(cache), 0) def test_disabled_service(self) -> None: """ test the behaviour when there is a single record which is ".". """ service_name = b"test_service.example.com" lookup_deferred: "Deferred[Tuple[List[dns.RRHeader], None, None]]" = Deferred() dns_client_mock = Mock() dns_client_mock.lookupService.return_value = lookup_deferred cache: Dict[bytes, List[Server]] = {} 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) -> None: """ test the behaviour when the dns server gives us a spurious non-SRV response """ service_name = b"test_service.example.com" lookup_deferred: "Deferred[Tuple[List[dns.RRHeader], None, None]]" = Deferred() dns_client_mock = Mock() dns_client_mock.lookupService.return_value = lookup_deferred cache: Dict[bytes, List[Server]] = {} 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")