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#
# 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:
# <https://www.gnu.org/licenses/agpl-3.0.html>.
#
# Originally licensed under the Apache License, Version 2.0:
# <http://www.apache.org/licenses/LICENSE-2.0>.
#
# [This file includes modifications made by New Vector Limited]
#
#
from typing import Generator, 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.server import get_clock
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(
name="one",
server_name="test_server",
) 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]:
reactor, clock = get_clock()
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")
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