Remember proxy_ep properly if it was Deferred

test/test_socks.py

@@ -5,9 +5,12 @@
 from twisted.internet import defer
 from twisted.internet.address import IPv4Address
 from twisted.internet.protocol import Protocol
+from twisted.internet.interfaces import IStreamClientEndpoint
 from twisted.test import proto_helpers
 from twisted.test.iosim import connect, FakeTransport
 
+from zope.interface import directlyProvides
+
 from txtorcon import socks
 
 
@@ -511,6 +514,7 @@ def connect(factory):
     @defer.inlineCallbacks
     def test_connect_deferred_proxy(self):
         socks_ep = Mock()
+        directlyProvides(socks_ep, IStreamClientEndpoint)
         transport = proto_helpers.StringTransport()
 
         def connect(factory):
@@ -533,6 +537,25 @@ def connect(factory):
         proto = yield ep.connect(factory)
         self.assertEqual(proto, protocol)
 
+    @defer.inlineCallbacks
+    def test_connect_deferred_proxy_wrong_return(self):
+
+        class NotAnEndpoint(object):
+            "definitely doesn't implement IStreamClientEndpoint"
+        not_an_endpoint = NotAnEndpoint()
+        factory = Mock()
+        ep = socks.TorSocksEndpoint(
+            socks_endpoint=defer.succeed(not_an_endpoint),
+            host=u'meejah.ca',
+            port=443,
+        )
+        with self.assertRaises(ValueError) as ctx:
+            yield ep.connect(factory)
+        self.assertIn(
+            "must resolve to an IStreamClientEndpoint provider",
+            str(ctx.exception),
+        )
+
     @defer.inlineCallbacks
     def test_connect_tls(self):
         socks_ep = Mock()

txtorcon/endpoints.py

@@ -679,6 +679,7 @@ def _create_socks_endpoint(reactor, control_protocol, socks_config=None):
         yield control_protocol.set_conf(*args)
         socks_endpoint = _endpoint_from_socksport_line(reactor, socks_config)
 
+    assert socks_endpoint is not None
     defer.returnValue(socks_endpoint)
 
 

txtorcon/socks.py

@@ -689,6 +689,7 @@ class TorSocksEndpoint(object):
     # IAddress-implementer?
     def __init__(self, socks_endpoint, host, port, tls=False):
         self._proxy_ep = socks_endpoint  # can be Deferred
+        assert self._proxy_ep is not None
         if six.PY2 and isinstance(host, str):
             host = unicode(host)  # noqa
         if six.PY3 and isinstance(host, bytes):
@@ -735,6 +736,11 @@ def connect(self, factory):
         # XXX isn't this just maybeDeferred()
         if isinstance(self._proxy_ep, Deferred):
             proxy_ep = yield self._proxy_ep
+            if not IStreamClientEndpoint.providedBy(proxy_ep):
+                raise ValueError(
+                    "The Deferred provided as 'socks_endpoint' must "
+                    "resolve to an IStreamClientEndpoint provider"
+                )
         else:
             proxy_ep = self._proxy_ep
 

txtorcon/web.py

@@ -6,7 +6,7 @@
 
 from twisted.web.iweb import IAgentEndpointFactory
 from twisted.web.client import Agent
-from twisted.internet.defer import inlineCallbacks, returnValue
+from twisted.internet.defer import inlineCallbacks, returnValue, Deferred
 from twisted.internet.endpoints import TCP4ClientEndpoint, UNIXClientEndpoint
 
 from zope.interface import implementer
@@ -20,8 +20,14 @@ class _AgentEndpointFactoryUsingTor(object):
     def __init__(self, reactor, tor_socks_endpoint):
         self._reactor = reactor
         self._proxy_ep = tor_socks_endpoint
-        # XXX could accept optional "tls=" to do something besides
-        # optionsForClientTLS(hostname)?
+        # if _proxy_ep is Deferred, but we get called twice, we must
+        # remember the resolved object here
+        if isinstance(tor_socks_endpoint, Deferred):
+            self._proxy_ep.addCallback(self._set_proxy)
+
+    def _set_proxy(self, p):
+        self._proxy_ep = p
+        return p
 
     def endpointForURI(self, uri):
         return TorSocksEndpoint(