added logic to accept default headers in websocket

docs/settings.md

@@ -67,6 +67,9 @@ For more nuanced control over which file modifications trigger reloads, install
 * `--lifespan <str>` - Set the Lifespan protocol implementation. **Options:** *'auto', 'on', 'off'.* **Default:** *'auto'*.
 * `--h11-max-incomplete-event-size <int>` - Set the maximum number of bytes to buffer of an incomplete event. Only available for `h11` HTTP protocol implementation. **Default:** *'16384'* (16 KB).
 
+!!! note
+    Selecting `websockets` as Websocket protocol doesn't adhere to `--no-server-header` settings of Uvicorn. This is a limitation. 
+
 ## Application Interface
 
 * `--interface` - Select ASGI3, ASGI2, or WSGI as the application interface.

uvicorn/config.py

@@ -468,6 +468,8 @@ def load(self) -> None:
             self.http_protocol_class = self.http
 
         if isinstance(self.ws, str):
+            import websockets.http
+            websockets.http.USER_AGENT = ""
             ws_protocol_class = import_from_string(WS_PROTOCOLS[self.ws])
             self.ws_protocol_class: Optional[Type[asyncio.Protocol]] = ws_protocol_class
         else:

uvicorn/protocols/websockets/websockets_impl.py

@@ -69,6 +69,8 @@ def __init__(
         # Shared server state
         self.connections = server_state.connections
         self.tasks = server_state.tasks
+        self.default_headers = server_state.default_headers
+
 
         # Connection state
         self.transport: asyncio.Transport = None  # type: ignore[assignment]
@@ -260,12 +262,16 @@ async def asgi_send(self, message: "ASGISendEvent") -> None:
                 self.accepted_subprotocol = cast(
                     Optional[Subprotocol], message.get("subprotocol")
                 )
-                if "headers" in message:
-                    self.extra_headers.extend(
+                headers = list(message.get("headers", [])) + self.default_headers
+                _added_names = []
+                for name, value in headers:
+                    if name.lower() in _added_names:
+                        continue
+                    _added_names.append(name.lower())
+                    self.extra_headers.append((
                         # ASGI spec requires bytes
                         # But for compatibility we need to convert it to strings
-                        (name.decode("latin-1"), value.decode("latin-1"))
-                        for name, value in message["headers"]
+                        name.decode("latin-1"), value.decode("latin-1"))
                     )
                 self.handshake_started_event.set()
 

uvicorn/protocols/websockets/wsproto_impl.py

@@ -27,6 +27,8 @@ def __init__(self, config, server_state, _loop=None):
         # Shared server state
         self.connections = server_state.connections
         self.tasks = server_state.tasks
+        self.default_headers = server_state.default_headers
+
 
         # Connection state
         self.transport = None
@@ -133,6 +135,7 @@ def on_task_complete(self, task):
     def handle_connect(self, event):
         self.connect_event = event
         headers = [(b"host", event.host.encode())]
+        headers.extend(self.default_headers)
         headers += [(key.lower(), value) for key, value in event.extra_headers]
         raw_path, _, query_string = event.target.partition("?")
         self.scope = {