Merge lp:~blake-rouse/maas/fix-1628213-1628213 into lp:~maas-committers/maas/trunk

[Blake Rouse]

Fix websocket protocol in Twisted 16.3+.

[Andres Rodriguez (andreserl)]

lgtm!, but there's a comment inline that needs to be addressed before landing.

review: Approve

=== modified file 'src/maasserver/websockets/tests/test_websockets.py'
--- src/maasserver/websockets/tests/test_websockets.py	2016-02-23 00:06:54 +0000
+++ src/maasserver/websockets/tests/test_websockets.py	2016-09-30 13:23:49 +0000
@@ -50,12 +50,21 @@
 )
 from twisted.web.test.test_web import (
     DummyChannel,
-    DummyRequest,
+    DummyRequest as DummyRequestBase,
 )
 from zope.interface import implementer
 from zope.interface.verify import verifyObject
 
 
+class DummyRequest(DummyRequestBase):
+
+    content = None
+
+    def _cleanup(self):
+        """Called to cleanup the request."""
+        pass
+
+
 class TestFrameHelpers(MAASTestCase):
     """
     Test functions helping building and parsing WebSockets frames.

=== modified file 'src/maasserver/websockets/websockets.py'
--- src/maasserver/websockets/websockets.py	2015-11-29 23:59:47 +0000
+++ src/maasserver/websockets/websockets.py	2016-09-30 13:23:49 +0000
@@ -719,6 +719,24 @@
             transport.protocol = protocol
         protocol.makeConnection(transport)
 
+        # Starting with Twisted 16.3+ `_cleanup` must be called on the request
+        # so the socket is placed back into the reactor. `_cleanup` has always
+        # existed, but was not required to be called until Twisted 16.3+.
+        # `_cleanup` in Twisted 16.3+ checks to ensure that if content is None
+        # to not call close, in previous versions it does not. To make this
+        # code work on both all Twisted versions we must set content to
+        # EmptyContent so an `AttributeError` is not raied when the content is
+        # None. Only then can `_cleanup` be called safely. `finalize` also
+        # exists on the request and is actually the public API, but this
+        # method cannot be called because it will write invalid content to the
+        # socket which will break the websocket connection.
+        if request.content is None:
+            class EmptyContent:
+                def close(*args, **kwargs):
+                    pass
+            request.content = EmptyContent()
+        request._cleanup()
+
         return NOT_DONE_YET