Fix invalid WebSocket responses (Fixes #332, Fixes #331, Fixes #338)

src/engineio/async_drivers/asgi.py

@@ -233,9 +233,14 @@ async def __call__(self, environ):
         self.asgi_send = environ['asgi.send']
         await self.asgi_send({'type': 'websocket.accept'})
         await self.handler(self)
+        return ''  # send nothing as response
 
     async def close(self):
-        pass
+        try:
+            await self.asgi_send({'type': 'websocket.close'})
+        except Exception:
+            # if the socket is already close we don't care
+            pass
 
     async def send(self, message):
         msg_bytes = None

src/engineio/async_drivers/gevent_uwsgi.py

@@ -61,6 +61,7 @@ def select_greenlet_runner(fd, event):
 
         self.app(self)
         uwsgi.disconnect()
+        return ''  # send nothing as response
 
     def close(self):
         """Disconnects uWSGI from the client."""

src/engineio/async_drivers/sanic.py

@@ -114,6 +114,7 @@ class WebSocket(object):  # pragma: no cover
     """
     def __init__(self, handler, server):
         self.handler = handler
+        self.server = server
         self._sock = None
 
     async def __call__(self, environ):
@@ -123,6 +124,7 @@ async def __call__(self, environ):
 
         self.environ = environ
         await self.handler(self)
+        return self.server._ok()
 
     async def close(self):
         await self._sock.close()

src/engineio/async_socket.py

@@ -140,7 +140,7 @@ async def _upgrade_websocket(self, environ):
             return self.server._bad_request()
         ws = self.server._async['websocket'](
             self._websocket_handler, self.server)
-        await ws(environ)
+        return await ws(environ)
 
     async def _websocket_handler(self, ws):
         """Engine.IO handler for websocket transport."""

src/engineio/server.py

@@ -306,7 +306,7 @@ def handle_request(self, environ, start_response):
             r = self._method_not_found()
 
         if not isinstance(r, dict):
-            return r or []
+            return r
         if self.http_compression and \
                 len(r['response']) >= self.compression_threshold:
             encodings = [e.split(';')[0].strip() for e in

src/engineio/socket.py

@@ -143,8 +143,7 @@ def _upgrade_websocket(self, environ, start_response):
             return self.server._bad_request()
         ws = self.server._async['websocket'](
             self._websocket_handler, self.server)
-        ws(environ, start_response)
-        return self.server._ok()
+        return ws(environ, start_response)
 
     def _websocket_handler(self, ws):
         """Engine.IO handler for websocket transport."""