From 63b51ef3fbb548cdc7899720f8c40bb65756f655 Mon Sep 17 00:00:00 2001 From: Evilham Date: Tue, 29 Aug 2023 15:33:58 +0200 Subject: [PATCH] Support IPv6-only SMTP servers (#16155) Use Twisted HostnameEndpoint to connect to SMTP servers (instead of connectTCP/connectSSL) which properly supports IPv6-only servers. --- changelog.d/16155.bugfix | 1 + synapse/handlers/send_email.py | 28 +++++-------- tests/handlers/test_send_email.py | 69 ++++++++++++++++++++++++++----- tests/server.py | 54 +++++++++++++++++++++++- tests/unittest.py | 2 +- 5 files changed, 125 insertions(+), 29 deletions(-) create mode 100644 changelog.d/16155.bugfix diff --git a/changelog.d/16155.bugfix b/changelog.d/16155.bugfix new file mode 100644 index 000000000..8b2dc0400 --- /dev/null +++ b/changelog.d/16155.bugfix @@ -0,0 +1 @@ +Fix IPv6-related bugs on SMTP settings, adding groundwork to fix similar issues. Contributed by @evilham and @telmich (ungleich.ch). diff --git a/synapse/handlers/send_email.py b/synapse/handlers/send_email.py index 804cc6e81..05e21509d 100644 --- a/synapse/handlers/send_email.py +++ b/synapse/handlers/send_email.py @@ -23,9 +23,11 @@ from pkg_resources import parse_version import twisted from twisted.internet.defer import Deferred -from twisted.internet.interfaces import IOpenSSLContextFactory +from twisted.internet.endpoints import HostnameEndpoint +from twisted.internet.interfaces import IOpenSSLContextFactory, IProtocolFactory from twisted.internet.ssl import optionsForClientTLS from twisted.mail.smtp import ESMTPSender, ESMTPSenderFactory +from twisted.protocols.tls import TLSMemoryBIOFactory from synapse.logging.context import make_deferred_yieldable from synapse.types import ISynapseReactor @@ -97,6 +99,7 @@ async def _sendmail( **kwargs, ) + factory: IProtocolFactory if _is_old_twisted: # before twisted 21.2, we have to override the ESMTPSender protocol to disable # TLS @@ -110,22 +113,13 @@ async def _sendmail( factory = build_sender_factory(hostname=smtphost if enable_tls else None) if force_tls: - reactor.connectSSL( - smtphost, - smtpport, - factory, - optionsForClientTLS(smtphost), - timeout=30, - bindAddress=None, - ) - else: - reactor.connectTCP( - smtphost, - smtpport, - factory, - timeout=30, - bindAddress=None, - ) + factory = TLSMemoryBIOFactory(optionsForClientTLS(smtphost), True, factory) + + endpoint = HostnameEndpoint( + reactor, smtphost, smtpport, timeout=30, bindAddress=None + ) + + await make_deferred_yieldable(endpoint.connect(factory)) await make_deferred_yieldable(d) diff --git a/tests/handlers/test_send_email.py b/tests/handlers/test_send_email.py index 8b6e4a40b..a066745d7 100644 --- a/tests/handlers/test_send_email.py +++ b/tests/handlers/test_send_email.py @@ -13,19 +13,40 @@ # limitations under the License. -from typing import Callable, List, Tuple +from typing import Callable, List, Tuple, Type, Union +from unittest.mock import patch from zope.interface import implementer from twisted.internet import defer -from twisted.internet.address import IPv4Address +from twisted.internet._sslverify import ClientTLSOptions +from twisted.internet.address import IPv4Address, IPv6Address from twisted.internet.defer import ensureDeferred +from twisted.internet.interfaces import IProtocolFactory +from twisted.internet.ssl import ContextFactory from twisted.mail import interfaces, smtp from tests.server import FakeTransport from tests.unittest import HomeserverTestCase, override_config +def TestingESMTPTLSClientFactory( + contextFactory: ContextFactory, + _connectWrapped: bool, + wrappedProtocol: IProtocolFactory, +) -> IProtocolFactory: + """We use this to pass through in testing without using TLS, but + saving the context information to check that it would have happened. + + Note that this is what the MemoryReactor does on connectSSL. + It only saves the contextFactory, but starts the connection with the + underlying Factory. + See: L{twisted.internet.testing.MemoryReactor.connectSSL}""" + + wrappedProtocol._testingContextFactory = contextFactory # type: ignore[attr-defined] + return wrappedProtocol + + @implementer(interfaces.IMessageDelivery) class _DummyMessageDelivery: def __init__(self) -> None: @@ -75,7 +96,13 @@ class _DummyMessage: pass -class SendEmailHandlerTestCase(HomeserverTestCase): +class SendEmailHandlerTestCaseIPv4(HomeserverTestCase): + ip_class: Union[Type[IPv4Address], Type[IPv6Address]] = IPv4Address + + def setUp(self) -> None: + super().setUp() + self.reactor.lookups["localhost"] = "127.0.0.1" + def test_send_email(self) -> None: """Happy-path test that we can send email to a non-TLS server.""" h = self.hs.get_send_email_handler() @@ -89,7 +116,7 @@ class SendEmailHandlerTestCase(HomeserverTestCase): (host, port, client_factory, _timeout, _bindAddress) = self.reactor.tcpClients[ 0 ] - self.assertEqual(host, "localhost") + self.assertEqual(host, self.reactor.lookups["localhost"]) self.assertEqual(port, 25) # wire it up to an SMTP server @@ -105,7 +132,9 @@ class SendEmailHandlerTestCase(HomeserverTestCase): FakeTransport( client_protocol, self.reactor, - peer_address=IPv4Address("TCP", "127.0.0.1", 1234), + peer_address=self.ip_class( + "TCP", self.reactor.lookups["localhost"], 1234 + ), ) ) @@ -118,6 +147,10 @@ class SendEmailHandlerTestCase(HomeserverTestCase): self.assertEqual(str(user), "foo@bar.com") self.assertIn(b"Subject: test subject", msg) + @patch( + "synapse.handlers.send_email.TLSMemoryBIOFactory", + TestingESMTPTLSClientFactory, + ) @override_config( { "email": { @@ -135,17 +168,23 @@ class SendEmailHandlerTestCase(HomeserverTestCase): ) ) # there should be an attempt to connect to localhost:465 - self.assertEqual(len(self.reactor.sslClients), 1) + self.assertEqual(len(self.reactor.tcpClients), 1) ( host, port, client_factory, - contextFactory, _timeout, _bindAddress, - ) = self.reactor.sslClients[0] - self.assertEqual(host, "localhost") + ) = self.reactor.tcpClients[0] + self.assertEqual(host, self.reactor.lookups["localhost"]) self.assertEqual(port, 465) + # We need to make sure that TLS is happenning + self.assertIsInstance( + client_factory._wrappedFactory._testingContextFactory, + ClientTLSOptions, + ) + # And since we use endpoints, they go through reactor.connectTCP + # which works differently to connectSSL on the testing reactor # wire it up to an SMTP server message_delivery = _DummyMessageDelivery() @@ -160,7 +199,9 @@ class SendEmailHandlerTestCase(HomeserverTestCase): FakeTransport( client_protocol, self.reactor, - peer_address=IPv4Address("TCP", "127.0.0.1", 1234), + peer_address=self.ip_class( + "TCP", self.reactor.lookups["localhost"], 1234 + ), ) ) @@ -172,3 +213,11 @@ class SendEmailHandlerTestCase(HomeserverTestCase): user, msg = message_delivery.messages.pop() self.assertEqual(str(user), "foo@bar.com") self.assertIn(b"Subject: test subject", msg) + + +class SendEmailHandlerTestCaseIPv6(SendEmailHandlerTestCaseIPv4): + ip_class = IPv6Address + + def setUp(self) -> None: + super().setUp() + self.reactor.lookups["localhost"] = "::1" diff --git a/tests/server.py b/tests/server.py index ff03d2886..659ccce83 100644 --- a/tests/server.py +++ b/tests/server.py @@ -12,6 +12,7 @@ # See the License for the specific language governing permissions and # limitations under the License. import hashlib +import ipaddress import json import logging import os @@ -45,7 +46,7 @@ import attr from typing_extensions import ParamSpec from zope.interface import implementer -from twisted.internet import address, threads, udp +from twisted.internet import address, tcp, threads, udp from twisted.internet._resolver import SimpleResolverComplexifier from twisted.internet.defer import Deferred, fail, maybeDeferred, succeed from twisted.internet.error import DNSLookupError @@ -567,6 +568,8 @@ class ThreadedMemoryReactorClock(MemoryReactorClock): conn = super().connectTCP( host, port, factory, timeout=timeout, bindAddress=None ) + if self.lookups and host in self.lookups: + validate_connector(conn, self.lookups[host]) callback = self._tcp_callbacks.get((host, port)) if callback: @@ -599,6 +602,55 @@ class ThreadedMemoryReactorClock(MemoryReactorClock): super().advance(0) +def validate_connector(connector: tcp.Connector, expected_ip: str) -> None: + """Try to validate the obtained connector as it would happen when + synapse is running and the conection will be established. + + This method will raise a useful exception when necessary, else it will + just do nothing. + + This is in order to help catch quirks related to reactor.connectTCP, + since when called directly, the connector's destination will be of type + IPv4Address, with the hostname as the literal host that was given (which + could be an IPv6-only host or an IPv6 literal). + + But when called from reactor.connectTCP *through* e.g. an Endpoint, the + connector's destination will contain the specific IP address with the + correct network stack class. + + Note that testing code paths that use connectTCP directly should not be + affected by this check, unless they specifically add a test with a + matching reactor.lookups[HOSTNAME] = "IPv6Literal", where reactor is of + type ThreadedMemoryReactorClock. + For an example of implementing such tests, see test/handlers/send_email.py. + """ + destination = connector.getDestination() + + # We use address.IPv{4,6}Address to check what the reactor thinks it is + # is sending but check for validity with ipaddress.IPv{4,6}Address + # because they fail with IPs on the wrong network stack. + cls_mapping = { + address.IPv4Address: ipaddress.IPv4Address, + address.IPv6Address: ipaddress.IPv6Address, + } + + cls = cls_mapping.get(destination.__class__) + + if cls is not None: + try: + cls(expected_ip) + except Exception as exc: + raise ValueError( + "Invalid IP type and resolution for %s. Expected %s to be %s" + % (destination, expected_ip, cls.__name__) + ) from exc + else: + raise ValueError( + "Unknown address type %s for %s" + % (destination.__class__.__name__, destination) + ) + + class ThreadPool: """ Threadless thread pool. diff --git a/tests/unittest.py b/tests/unittest.py index b0721e060..40672a441 100644 --- a/tests/unittest.py +++ b/tests/unittest.py @@ -313,7 +313,7 @@ class HomeserverTestCase(TestCase): servlets: List of servlet registration function. user_id (str): The user ID to assume if auth is hijacked. hijack_auth: Whether to hijack auth to return the user specified - in user_id. + in user_id. """ hijack_auth: ClassVar[bool] = True