implement IHalfCloseableProtocol so exim can do its shutdown(fd, SHUT…

…_WR)

closes #5

postfix.py

@@ -27,10 +27,14 @@
 
 from twisted.protocols.basic import LineOnlyReceiver
 from twisted.internet.protocol import Factory
+from twisted.internet.interfaces import IHalfCloseableProtocol
+from zope.interface import implements
 
 class PostfixPolicy(LineOnlyReceiver):
     '''Basic implementation of a Postfix policy service.'''
 
+    implements(IHalfCloseableProtocol)
+
     def __init__(self):
         self.params = {}
         self.delimiter = '\n'
@@ -70,5 +74,12 @@ def send_action (self, action='DUNNO'):
         '''
         self.sendLine('action=%s\n' % action)
 
+    def readConnectionLost(self):
+        pass
+
+    def writeConnectionLost(self):
+        self.transport.loseConnection()
+
+
 class PostfixPolicyFactory(Factory):
     protocol = PostfixPolicy