Add ENABLE_CONNECT_PROTOCOL setting support

This setting flag is introduced in RFC 8441 to allow websockets over
HTTP/2. It has only recently been added to Hyperframe (hence the
version bump).

Author: pgjones

HISTORY.rst

@@ -20,6 +20,7 @@ API Changes (Backward-Compatible)
   fired when a PING frame with an ACK flag is received.
   ``h2.events.PingAcknowledged`` is deprecated in favour of the identical
   ``h2.events.PingAckReceived``.
+- Added ``ENABLE_CONNECT_PROTOCOL`` to ``h2.settings.SettingCodes``.
 
 Bugfixes
 ~~~~~~~~

h2/settings.py

@@ -55,6 +55,10 @@ class SettingCodes(enum.IntEnum):
     #: and value in octets plus an overhead of 32 octets for each header field.
     MAX_HEADER_LIST_SIZE = SettingsFrame.MAX_HEADER_LIST_SIZE
 
+    #: This setting can be used to enable the connect protocol. To enable on a
+    #: client set this to 1.
+    ENABLE_CONNECT_PROTOCOL = SettingsFrame.ENABLE_CONNECT_PROTOCOL
+
 
 def _setting_code_from_int(code):
     """
@@ -141,6 +145,7 @@ def __init__(self, client=True, initial_values=None):
             SettingCodes.ENABLE_PUSH: collections.deque([int(client)]),
             SettingCodes.INITIAL_WINDOW_SIZE: collections.deque([65535]),
             SettingCodes.MAX_FRAME_SIZE: collections.deque([16384]),
+            SettingCodes.ENABLE_CONNECT_PROTOCOL: collections.deque([0]),
         }
         if initial_values is not None:
             for key, value in initial_values.items():
@@ -249,6 +254,18 @@ def max_header_list_size(self):
     def max_header_list_size(self, value):
         self[SettingCodes.MAX_HEADER_LIST_SIZE] = value
 
+    @property
+    def enable_connect_protocol(self):
+        """
+        The current value of the :data:`ENABLE_CONNECT_PROTOCOL
+        <h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL>` setting.
+        """
+        return self[SettingCodes.ENABLE_CONNECT_PROTOCOL]
+
+    @enable_connect_protocol.setter
+    def enable_connect_protocol(self, value):
+        self[SettingCodes.ENABLE_CONNECT_PROTOCOL] = value
+
     # Implement the MutableMapping API.
     def __getitem__(self, key):
         val = self._settings[key][0]
@@ -298,7 +315,7 @@ def __ne__(self, other):
             return NotImplemented
 
 
-def _validate_setting(setting, value):
+def _validate_setting(setting, value):  # noqa: C901
     """
     Confirms that a specific setting has a well-formed value. If the setting is
     invalid, returns an error code. Otherwise, returns 0 (NO_ERROR).
@@ -315,5 +332,8 @@ def _validate_setting(setting, value):
     elif setting == SettingCodes.MAX_HEADER_LIST_SIZE:
         if value < 0:
             return ErrorCodes.PROTOCOL_ERROR
+    elif setting == SettingCodes.ENABLE_CONNECT_PROTOCOL:
+        if value not in (0, 1):
+            return ErrorCodes.PROTOCOL_ERROR
 
     return 0

setup.py

@@ -62,7 +62,7 @@
         'Programming Language :: Python :: Implementation :: PyPy',
     ],
     install_requires=[
-        'hyperframe>=5.1.0, <6',
+        'hyperframe>=5.2.0, <6',
         'hpack>=2.3,<4',
     ],
     extras_require={

test/test_settings.py

@@ -31,6 +31,7 @@ def test_settings_defaults_client(self):
         assert s[h2.settings.SettingCodes.ENABLE_PUSH] == 1
         assert s[h2.settings.SettingCodes.INITIAL_WINDOW_SIZE] == 65535
         assert s[h2.settings.SettingCodes.MAX_FRAME_SIZE] == 16384
+        assert s[h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL] == 0
 
     def test_settings_defaults_server(self):
         """
@@ -42,6 +43,7 @@ def test_settings_defaults_server(self):
         assert s[h2.settings.SettingCodes.ENABLE_PUSH] == 0
         assert s[h2.settings.SettingCodes.INITIAL_WINDOW_SIZE] == 65535
         assert s[h2.settings.SettingCodes.MAX_FRAME_SIZE] == 16384
+        assert s[h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL] == 0
 
     @pytest.mark.parametrize('client', [True, False])
     def test_can_set_initial_values(self, client):
@@ -54,6 +56,7 @@ def test_can_set_initial_values(self, client):
             h2.settings.SettingCodes.MAX_FRAME_SIZE: 16388,
             h2.settings.SettingCodes.MAX_CONCURRENT_STREAMS: 100,
             h2.settings.SettingCodes.MAX_HEADER_LIST_SIZE: 2**16,
+            h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL: 1,
         }
         s = h2.settings.Settings(client=client, initial_values=overrides)
 
@@ -63,6 +66,7 @@ def test_can_set_initial_values(self, client):
         assert s[h2.settings.SettingCodes.MAX_FRAME_SIZE] == 16388
         assert s[h2.settings.SettingCodes.MAX_CONCURRENT_STREAMS] == 100
         assert s[h2.settings.SettingCodes.MAX_HEADER_LIST_SIZE] == 2**16
+        assert s[h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL] == 1
 
     @pytest.mark.parametrize(
         'setting,value',
@@ -74,6 +78,7 @@ def test_can_set_initial_values(self, client):
             (h2.settings.SettingCodes.MAX_FRAME_SIZE, 1),
             (h2.settings.SettingCodes.MAX_FRAME_SIZE, 2**30),
             (h2.settings.SettingCodes.MAX_HEADER_LIST_SIZE, -1),
+            (h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL, -1),
         ]
     )
     def test_cannot_set_invalid_initial_values(self, setting, value):
@@ -108,6 +113,7 @@ def test_acknowledging_values(self):
             h2.settings.SettingCodes.ENABLE_PUSH: 0,
             h2.settings.SettingCodes.INITIAL_WINDOW_SIZE: 60,
             h2.settings.SettingCodes.MAX_FRAME_SIZE: 16385,
+            h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL: 1,
         }
         s.update(new_settings)
 
@@ -171,16 +177,16 @@ def test_length_correctly_reported(self):
         Length is related only to the number of keys.
         """
         s = h2.settings.Settings(client=True)
-        assert len(s) == 4
+        assert len(s) == 5
 
         s[h2.settings.SettingCodes.HEADER_TABLE_SIZE] == 8000
-        assert len(s) == 4
+        assert len(s) == 5
 
         s.acknowledge()
-        assert len(s) == 4
+        assert len(s) == 5
 
         del s[h2.settings.SettingCodes.HEADER_TABLE_SIZE]
-        assert len(s) == 3
+        assert len(s) == 4
 
     def test_new_values_work(self):
         """
@@ -234,6 +240,9 @@ def test_settings_getters(self):
         assert s.max_frame_size == s[h2.settings.SettingCodes.MAX_FRAME_SIZE]
         assert s.max_concurrent_streams == 2**32 + 1  # A sensible default.
         assert s.max_header_list_size is None
+        assert s.enable_connect_protocol == s[
+            h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL
+        ]
 
     def test_settings_setters(self):
         """
@@ -247,6 +256,7 @@ def test_settings_setters(self):
         s.max_frame_size = 16385
         s.max_concurrent_streams = 4
         s.max_header_list_size = 2**16
+        s.enable_connect_protocol = 1
 
         s.acknowledge()
         assert s[h2.settings.SettingCodes.HEADER_TABLE_SIZE] == 0
@@ -255,6 +265,7 @@ def test_settings_setters(self):
         assert s[h2.settings.SettingCodes.MAX_FRAME_SIZE] == 16385
         assert s[h2.settings.SettingCodes.MAX_CONCURRENT_STREAMS] == 4
         assert s[h2.settings.SettingCodes.MAX_HEADER_LIST_SIZE] == 2**16
+        assert s[h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL] == 1
 
     @given(integers())
     def test_cannot_set_invalid_values_for_enable_push(self, val):
@@ -363,6 +374,28 @@ def test_cannot_set_invalid_values_for_max_header_list_size(self, val):
             with pytest.raises(KeyError):
                 s[h2.settings.SettingCodes.MAX_HEADER_LIST_SIZE]
 
+    @given(integers())
+    def test_cannot_set_invalid_values_for_enable_connect_protocol(self, val):
+        """
+        SETTINGS_ENABLE_CONNECT_PROTOCOL only allows two values: 0, 1.
+        """
+        assume(val not in (0, 1))
+        s = h2.settings.Settings()
+
+        with pytest.raises(h2.exceptions.InvalidSettingsValueError) as e:
+            s.enable_connect_protocol = val
+
+        s.acknowledge()
+        assert e.value.error_code == h2.errors.ErrorCodes.PROTOCOL_ERROR
+        assert s.enable_connect_protocol == 0
+
+        with pytest.raises(h2.exceptions.InvalidSettingsValueError) as e:
+            s[h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL] = val
+
+        s.acknowledge()
+        assert e.value.error_code == h2.errors.ErrorCodes.PROTOCOL_ERROR
+        assert s[h2.settings.SettingCodes.ENABLE_CONNECT_PROTOCOL] == 0
+
 
 class TestSettingsEquality(object):
     """