Align enable-push validation with RFC 9113

Author: Mirochill

src/h2/settings.py

@@ -343,7 +343,10 @@ def _validate_setting(
     If ``client`` is true, the setting originated from a client endpoint.
     """
     if setting == SettingCodes.ENABLE_PUSH:
-        if value not in (0, 1) or (client and value != 0):
+        # RFC 9113 section 6.5.2: "A client MUST treat receipt of a
+        # SETTINGS frame with SETTINGS_ENABLE_PUSH set to 1 as a connection
+        # error (Section 5.4.1) of type PROTOCOL_ERROR."
+        if value not in (0, 1) or (not client and value != 0):
             return ErrorCodes.PROTOCOL_ERROR
     elif setting == SettingCodes.INITIAL_WINDOW_SIZE:
         if not 0 <= value <= 2147483647:  # 2^31 - 1

tests/test_invalid_frame_sequences.py

@@ -267,14 +267,13 @@ def test_reject_invalid_settings_values(self, frame_factory, settings) -> None:
             h2.errors.ErrorCodes.PROTOCOL_ERROR
         )
 
-    def test_reject_client_enable_push_updates(self, frame_factory) -> None:
+    def test_reject_server_enable_push_updates(self, frame_factory) -> None:
         """
-        Servers reject clients that advertise non-zero SETTINGS_ENABLE_PUSH
+        Clients reject servers that advertise non-zero SETTINGS_ENABLE_PUSH
         values in received SETTINGS frames.
         """
-        c = h2.connection.H2Connection(config=self.server_config)
+        c = h2.connection.H2Connection(config=self.client_config)
         c.initiate_connection()
-        c.receive_data(frame_factory.preamble())
 
         f = frame_factory.build_settings_frame(
             settings={h2.settings.SettingCodes.ENABLE_PUSH: 1},