Fix recv() errors when closing during handshake

Fixes encode#244. The unit test already existed, but it logged exceptions that
weren't being noticed.

* websockets_impl: `transfer_data_task` is unset if the handshake fails,
  so we can't call recv().
* wsproto_impl: `h11.Reject` is invalid during handshake; send
  `RejectConnection` instead.

tests/protocols/test_websocket.py

@@ -1,5 +1,6 @@
 import asyncio
 import functools
+import logging
 import threading
 import time
 from contextlib import contextmanager
@@ -118,7 +119,9 @@ async def open_connection(url):
 
 
 @pytest.mark.parametrize("protocol_cls", WS_PROTOCOLS)
-def test_close_connection(protocol_cls):
+def test_close_connection(protocol_cls, caplog):
+    caplog.set_level(logging.ERROR)
+
     class App(WebSocketResponse):
         async def websocket_connect(self, message):
             await self.send({"type": "websocket.close"})
@@ -136,6 +139,8 @@ async def open_connection(url):
         assert not is_open
         loop.close()
 
+    assert not [r.message for r in caplog.records]
+
 
 @pytest.mark.parametrize("protocol_cls", WS_PROTOCOLS)
 def test_headers(protocol_cls):

uvicorn/protocols/websockets/websockets_impl.py

@@ -50,7 +50,6 @@ def __init__(self, config, server_state, _loop=None):
         self.initial_response = None
         self.connect_sent = False
         self.accepted_subprotocol = None
-        self.transfer_data_task = None
 
         self.ws_server = Server()
 
@@ -230,6 +229,12 @@ async def asgi_receive(self):
             return {"type": "websocket.connect"}
 
         await self.handshake_completed_event.wait()
+        if not hasattr(self, "transfer_data_task"):
+            # If the handshake completed and there's no data-transfer task,
+            # that means the handshake failed.
+            assert self.closed_event.is_set()
+            return {"type": "websocket.disconnect", "code": self.initial_response[0]}
+
         try:
             data = await self.recv()
         except websockets.ConnectionClosed as exc:

uvicorn/protocols/websockets/wsproto_impl.py

@@ -255,10 +255,8 @@ async def send(self, message):
                 )
                 self.handshake_complete = True
                 self.close_sent = True
-                msg = h11.Response(status_code=403, headers=[])
+                msg = events.RejectConnection(status_code=403, headers=[])
                 output = self.conn.send(msg)
-                msg = h11.EndOfMessage()
-                output += self.conn.send(msg)
                 self.transport.write(output)
                 self.transport.close()