Fix stanza clobbering when replying to errors.sleek-1.0.0-beta5sleek-1.0-Beta51.0.0-beta51.0-Beta5

If a stanza handler raised an exception, the exception was processed
and replied by the modified stanza, not a stanza with the original
content.

A copy is now made before handler processing, and if an exception occurs
it is the copy that processes the exception using the original content.

3 files changed, 38 insertions, 6 deletions

diff --git a/sleekxmpp/stanza/message.py b/sleekxmpp/stanza/message.py
index cb3d344c..3518fc7a 100644
--- a/sleekxmpp/stanza/message.py
+++ b/sleekxmpp/stanza/message.py
@@ -97,7 +97,7 @@ class Message(RootStanza):
             clear -- Indicates if existing content should be removed
                      before replying. Defaults to True.
         """
-        StanzaBase.reply(self)
+        StanzaBase.reply(self, clear)
         if self['type'] == 'groupchat':
             self['to'] = self['to'].bare
 
diff --git a/sleekxmpp/xmlstream/xmlstream.py b/sleekxmpp/xmlstream/xmlstream.py
index 5bc71f04..6282c8d0 100644
--- a/sleekxmpp/xmlstream/xmlstream.py
+++ b/sleekxmpp/xmlstream/xmlstream.py
@@ -944,13 +944,14 @@ class XMLStream(object):
             func -- The event handler to execute.
             args -- Arguments to the event handler.
         """
+        orig = copy.copy(args[0])
         try:
             func(*args)
         except Exception as e:
             error_msg = 'Error processing event handler: %s'
             log.exception(error_msg % str(func))
-            if hasattr(args[0], 'exception'):
-                args[0].exception(e)
+            if hasattr(orig, 'exception'):
+                orig.exception(e)
 
     def _event_runner(self):
         """
@@ -973,6 +974,7 @@ class XMLStream(object):
 
                 etype, handler = event[0:2]
                 args = event[2:]
+                orig = copy.copy(args[0])
 
                 if etype == 'stanza':
                     try:
@@ -980,7 +982,7 @@ class XMLStream(object):
                     except Exception as e:
                         error_msg = 'Error processing stream handler: %s'
                         log.exception(error_msg % handler.name)
-                        args[0].exception(e)
+                        orig.exception(e)
                 elif etype == 'schedule':
                     try:
                         log.debug('Scheduled event: %s' % args)
@@ -989,6 +991,7 @@ class XMLStream(object):
                         log.exception('Error processing scheduled task')
                 elif etype == 'event':
                     func, threaded, disposable = handler
+                    orig = copy.copy(args[0])
                     try:
                         if threaded:
                             x = threading.Thread(
@@ -1001,8 +1004,8 @@ class XMLStream(object):
                     except Exception as e:
                         error_msg = 'Error processing event handler: %s'
                         log.exception(error_msg % str(func))
-                        if hasattr(args[0], 'exception'):
-                            args[0].exception(e)
+                        if hasattr(orig, 'exception'):
+                            orig.exception(e)
                 elif etype == 'quit':
                     log.debug("Quitting event runner thread")
                     return False
diff --git a/tests/test_stream_exceptions.py b/tests/test_stream_exceptions.py
index bc01c2a7..1143ce28 100644
--- a/tests/test_stream_exceptions.py
+++ b/tests/test_stream_exceptions.py
@@ -15,6 +15,35 @@ class TestStreamExceptions(SleekTest):
         sys.excepthook = sys.__excepthook__
         self.stream_close()
 
+    def testExceptionReply(self):
+        """Test that raising an exception replies with the original stanza."""
+
+        def message(msg):
+            msg.reply()
+            msg['body'] = 'Body changed'
+            raise XMPPError(clear=False)
+
+
+        sys.excepthook = lambda *args, **kwargs: None
+        self.stream_start()
+        self.xmpp.add_event_handler('message', message)
+
+        self.recv("""
+          <message>
+            <body>This is going to cause an error.</body>
+          </message>
+        """)
+
+        self.send("""
+          <message type="error">
+            <body>This is going to cause an error.</body>
+            <error type="cancel" code="500">
+              <undefined-condition
+                  xmlns="urn:ietf:params:xml:ns:xmpp-stanzas" />
+            </error>
+          </message>
+        """)
+
     def testXMPPErrorException(self):
         """Test raising an XMPPError exception."""