Fixing bug terminating connection prematurely

This change fixes a bug with the KmipSession connection handling logic
that would terminate the connection before actually receiving a
termination from the client. The corresponding unit tests have been
updated to reflect this fix.

kmip/core/exceptions.py

@@ -211,6 +211,14 @@ class ConfigurationError(Exception):
     pass
 
 
+class ConnectionClosed(Exception):
+    """
+    An exception generated when attempting to use a connection that has been
+    closed.
+    """
+    pass
+
+
 class NetworkingError(Exception):
     """
     An error generated when a problem occurs with client or server networking

kmip/services/server/session.py

@@ -70,15 +70,18 @@ class KmipSession(threading.Thread):
         """
         self._logger.info("Starting session: {0}".format(self.name))
 
-        try:
-            self._handle_message_loop()
-        except Exception as e:
-            self._logger.info("Failure handling message loop")
-            self._logger.exception(e)
-        finally:
-            self._connection.shutdown(socket.SHUT_RDWR)
-            self._connection.close()
-            self._logger.info("Stopping session: {0}".format(self.name))
+        while True:
+            try:
+                self._handle_message_loop()
+            except exceptions.ConnectionClosed as e:
+                break
+            except Exception as e:
+                self._logger.info("Failure handling message loop")
+                self._logger.exception(e)
+
+        self._connection.shutdown(socket.SHUT_RDWR)
+        self._connection.close()
+        self._logger.info("Stopping session: {0}".format(self.name))
 
     def _handle_message_loop(self):
         request_data = self._receive_request()
@@ -164,6 +167,8 @@ class KmipSession(threading.Thread):
 
             if partial_message is None:
                 break
+            elif len(partial_message) == 0:
+                raise exceptions.ConnectionClosed()
             else:
                 bytes_received += len(partial_message)
                 message += partial_message

kmip/tests/unit/services/server/test_session.py

@@ -19,6 +19,7 @@ import testtools
 import time
 
 from kmip.core import enums
+from kmip.core import exceptions
 from kmip.core import utils
 
 from kmip.core.messages import contents
@@ -58,13 +59,18 @@ class TestKmipSession(testtools.TestCase):
         """
         kmip_session = session.KmipSession(None, None, 'name')
         kmip_session._logger = mock.MagicMock()
-        kmip_session._handle_message_loop = mock.MagicMock()
+        kmip_session._handle_message_loop = mock.MagicMock(
+            side_effect=[
+                None,
+                exceptions.ConnectionClosed()
+            ]
+        )
         kmip_session._connection = mock.MagicMock()
 
         kmip_session.run()
 
         kmip_session._logger.info.assert_any_call("Starting session: name")
-        kmip_session._handle_message_loop.assert_called_once_with()
+        self.assertTrue(kmip_session._handle_message_loop.called)
         kmip_session._connection.shutdown.assert_called_once_with(
             socket.SHUT_RDWR
         )
@@ -82,13 +88,16 @@ class TestKmipSession(testtools.TestCase):
 
         test_exception = Exception("test")
         kmip_session._handle_message_loop = mock.MagicMock(
-            side_effect=test_exception
+            side_effect=[
+                test_exception,
+                exceptions.ConnectionClosed()
+            ]
         )
 
         kmip_session.run()
 
         kmip_session._logger.info.assert_any_call("Starting session: name")
-        kmip_session._handle_message_loop.assert_called_once_with()
+        self.assertTrue(kmip_session._handle_message_loop.called)
         kmip_session._logger.info.assert_any_call(
             "Failure handling message loop"
         )
@@ -267,6 +276,17 @@ class TestKmipSession(testtools.TestCase):
         kmip_session._connection.recv.assert_called_with(8)
         self.assertEqual(content + content, observed)
 
+        kmip_session._connection.recv = mock.MagicMock(
+            side_effect=['']
+        )
+
+        args = (8, )
+        self.assertRaises(
+            exceptions.ConnectionClosed,
+            kmip_session._receive_bytes,
+            *args
+        )
+
     def test_receive_bytes_with_bad_length(self):
         """
         Test that the session generates an error on an incorrectly sized