empty client_authz extension from RFC 5878

prober.py

@@ -170,7 +170,10 @@
     UserMappingNull12PFS(),
     UserMappingOverflow(),
     UserMappingOverflow12(),
-    UserMappingOverflow12PFS()
+    UserMappingOverflow12PFS(),
+    ClientAuthzNull(),
+    ClientAuthzNull12(),
+    ClientAuthzNull12PFS()
 ]
 
 def probe(ipaddress, port, starttls, specified_probe):

probes.py

@@ -1629,3 +1629,28 @@ class UserMappingOverflow12(UserMappingOverflow, NormalHandshake12):
 class UserMappingOverflow12PFS(UserMappingOverflow, NormalHandshake12PFS):
     '''As with UserMappingOverflow but in PFS TLSv1.2 hello'''
     pass
+
+
+class ClientAuthzNull(NormalHandshake):
+    '''Send empty client authz extension in hello'''
+
+    def make_client_authz_hello(self, value):
+        client_authz_ext = Extension.create(
+            extension_type=7,
+            data=value)
+        return self.make_hello([client_authz_ext])
+
+    def test(self, sock):
+        logging.debug('Sending Client Hello...')
+        # normal extension has an array, don't send anything
+        sock.write(self.make_client_authz_hello(b''))
+
+
+class ClientAuthzNull12(ClientAuthzNull, NormalHandshake12):
+    '''Send empty client authz extension in TLSv1.2 hello'''
+    pass
+
+
+class ClientAuthzNull12PFS(ClientAuthzNull, NormalHandshake12PFS):
+    '''Send empty client authz extension in PFS TLSv1.2 hello'''
+    pass

tests/test_probes.py

@@ -3139,3 +3139,64 @@ def test_test(self):
                           b'\x00\x06'
                           b'\x00\x06\x00\x02'
                           b'\x02\x40'])
+
+
+class TestClientAuthzNull(unittest.TestCase):
+    def test_test(self):
+        probe = ClientAuthzNull()
+        sock = MockSock()
+
+        probe.test(sock)
+
+        self.assertEqual(sock.sent_data,
+                         [b'\x16\x03\x01\x00?'
+                          b'\x01\x00\x00;'
+                          b'\x03\x01' +
+                          RANDOM_STR +
+                          b'\x00'
+                          b'\x00\x0e' +
+                          DEFAULT_CIPHERS_STR +
+                          b'\x01\x00'
+                          b'\x00\x04'
+                          b'\x00\x07\x00\x00'])
+
+
+class TestClientAuthzNull12(unittest.TestCase):
+    def test_test(self):
+        probe = ClientAuthzNull12()
+        sock = MockSock()
+
+        probe.test(sock)
+
+        self.assertEqual(sock.sent_data,
+                         [b'\x16\x03\x01\x00W'
+                          b'\x01\x00\x00S'
+                          b'\x03\x03' +
+                          RANDOM_STR +
+                          b'\x00'
+                          b'\x00&' +
+                          DEFAULT_12_CIPHERS_STR +
+                          b'\x01\x00'
+                          b'\x00\x04'
+                          b'\x00\x07\x00\x00'])
+
+
+class TestClientAuthzNull12PFS(unittest.TestCase):
+    def test_test(self):
+        probe = ClientAuthzNull12PFS()
+        sock = MockSock()
+
+        probe.test(sock)
+
+        self.maxDiff = None
+        self.assertEqual(sock.sent_data,
+                         [b"\x16\x03\x01\x00\x8f"
+                          b"\x01\x00\x00\x8b"
+                          b"\x03\x03" +
+                          RANDOM_STR +
+                          b"\x00"
+                          b"\x00^" +
+                          DEFAULT_PFS_CIPHERS_STR +
+                          b"\x01\x00"
+                          b'\x00\x04'
+                          b'\x00\x07\x00\x00'])