1 files changed, 75 insertions, 1 deletions

diff --git a/tests/test_transport.py b/tests/test_transport.py
index 13fb302e..2b8ee3bc 100644
--- a/tests/test_transport.py
+++ b/tests/test_transport.py
@@ -30,6 +30,7 @@ import threading
 import random
 from hashlib import sha1
 import unittest
+from mock import Mock
 
 from paramiko import (
     Transport,
@@ -41,19 +42,24 @@ from paramiko import (
     ChannelException,
     Packetizer,
     Channel,
+    AuthHandler,
 )
 from paramiko import AUTH_FAILED, AUTH_SUCCESSFUL
 from paramiko import OPEN_SUCCEEDED, OPEN_FAILED_ADMINISTRATIVELY_PROHIBITED
 from paramiko.common import (
     MSG_KEXINIT,
     cMSG_CHANNEL_WINDOW_ADJUST,
+    cMSG_UNIMPLEMENTED,
     MIN_PACKET_SIZE,
     MIN_WINDOW_SIZE,
     MAX_WINDOW_SIZE,
     DEFAULT_WINDOW_SIZE,
     DEFAULT_MAX_PACKET_SIZE,
+    MSG_NAMES,
+    MSG_UNIMPLEMENTED,
+    MSG_USERAUTH_SUCCESS,
 )
-from paramiko.py3compat import bytes
+from paramiko.py3compat import bytes, byte_chr
 from paramiko.message import Message
 
 from .util import needs_builtin, _support, slow
@@ -1027,3 +1033,71 @@ class TransportTest(unittest.TestCase):
             assert "forwarding request denied" in str(e)
         else:
             assert False, "Did not raise SSHException!"
+
+    def _send_unimplemented(self, server_is_sender):
+        self.setup_test_server()
+        sender, recipient = self.tc, self.ts
+        if server_is_sender:
+            sender, recipient = self.ts, self.tc
+        recipient._send_message = Mock()
+        msg = Message()
+        msg.add_byte(cMSG_UNIMPLEMENTED)
+        sender._send_message(msg)
+        # TODO: I hate this but I literally don't see a good way to know when
+        # the recipient has received the sender's message (there are no
+        # existing threading events in play that work for this), esp in this
+        # case where we don't WANT a response (as otherwise we could
+        # potentially try blocking on the sender's receipt of a reply...maybe).
+        time.sleep(0.1)
+        assert not recipient._send_message.called
+
+    def test_server_does_not_respond_to_MSG_UNIMPLEMENTED(self):
+        self._send_unimplemented(server_is_sender=False)
+
+    def test_client_does_not_respond_to_MSG_UNIMPLEMENTED(self):
+        self._send_unimplemented(server_is_sender=True)
+
+    def _send_client_message(self, message_type):
+        self.setup_test_server(connect_kwargs={})
+        self.ts._send_message = Mock()
+        # NOTE: this isn't 100% realistic (most of these message types would
+        # have actual other fields in 'em) but it suffices to test the level of
+        # message dispatch we're interested in here.
+        msg = Message()
+        # TODO: really not liking the whole cMSG_XXX vs MSG_XXX duality right
+        # now, esp since the former is almost always just byte_chr(the
+        # latter)...but since that's the case...
+        msg.add_byte(byte_chr(message_type))
+        self.tc._send_message(msg)
+        # No good way to actually wait for server action (see above tests re:
+        # MSG_UNIMPLEMENTED). Grump.
+        time.sleep(0.1)
+
+    def _expect_unimplemented(self):
+        # Ensure MSG_UNIMPLEMENTED was sent (implies it hit end of loop instead
+        # of truly handling the given message).
+        # NOTE: When bug present, this will actually be the first thing that
+        # fails (since in many cases actual message handling doesn't involve
+        # sending a message back right away).
+        assert self.ts._send_message.call_count == 1
+        reply = self.ts._send_message.call_args[0][0]
+        reply.rewind()  # Because it's pre-send, not post-receive
+        assert reply.get_byte() == cMSG_UNIMPLEMENTED
+
+    def test_server_transports_reject_client_message_types(self):
+        # TODO: handle Transport's own tables too, not just its inner auth
+        # handler's table. See TODOs in auth_handler.py
+        for message_type in AuthHandler._client_handler_table:
+            self._send_client_message(message_type)
+            self._expect_unimplemented()
+            # Reset for rest of loop
+            self.tearDown()
+            self.setUp()
+
+    def test_server_rejects_client_MSG_USERAUTH_SUCCESS(self):
+        self._send_client_message(MSG_USERAUTH_SUCCESS)
+        # Sanity checks
+        assert not self.ts.authenticated
+        assert not self.ts.auth_handler.authenticated
+        # Real fix's behavior
+        self._expect_unimplemented()