Fix some type hinting issues

sanic/server/protocols/websocket_protocol.py

@@ -1,7 +1,8 @@
-from typing import TYPE_CHECKING, Optional, Sequence
+from typing import TYPE_CHECKING, Optional, Sequence, cast
 
 from websockets.connection import CLOSED, CLOSING, OPEN
 from websockets.server import ServerConnection
+from websockets.typing import Subprotocol
 
 from sanic.exceptions import ServerError
 from sanic.log import error_logger
@@ -15,13 +16,6 @@
 
 
 class WebSocketProtocol(HttpProtocol):
-
-    websocket: Optional[WebsocketImplProtocol]
-    websocket_timeout: float
-    websocket_max_size = Optional[int]
-    websocket_ping_interval = Optional[float]
-    websocket_ping_timeout = Optional[float]
-
     def __init__(
         self,
         *args,
@@ -35,7 +29,7 @@ def __init__(
         **kwargs,
     ):
         super().__init__(*args, **kwargs)
-        self.websocket = None
+        self.websocket: Optional[WebsocketImplProtocol] = None
         self.websocket_timeout = websocket_timeout
         self.websocket_max_size = websocket_max_size
         if websocket_max_queue is not None and websocket_max_queue > 0:
@@ -116,7 +110,15 @@ async def websocket_handshake(
             if subprotocols is not None:
                 # subprotocols can be a set or frozenset,
                 # but ServerConnection needs a list
-                subprotocols = list(subprotocols)
+                subprotocols = cast(
+                    Optional[Sequence[Subprotocol]],
+                    list(
+                        [
+                            Subprotocol(subprotocol)
+                            for subprotocol in subprotocols
+                        ]
+                    ),
+                )
             ws_conn = ServerConnection(
                 max_size=self.websocket_max_size,
                 subprotocols=subprotocols,
@@ -142,7 +144,7 @@ async def websocket_handshake(
             )
             rbody += "".join(f"{k}: {v}\r\n" for k, v in resp.headers.items())
             if resp.body is not None:
-                rbody += f"\r\n{resp.body}\r\n\r\n"
+                rbody += f"\r\n{resp.body.decode('utf-8')}\r\n\r\n"
             else:
                 rbody += "\r\n"
             await super().send(rbody.encode())