Fix failed websocket handshake leaving connection hanging

CHANGES/3380.bugfix

@@ -0,0 +1 @@
+Fix failed websocket handshake leaving connection hanging.

aiohttp/_http_parser.pyx

@@ -533,6 +533,9 @@ cdef class HttpParser:
         else:
             return messages, False, b''
 
+    def set_upgraded(self, val):
+        self._upgraded = val
+
 
 cdef class HttpRequestParser(HttpParser):
 

aiohttp/http_parser.py

@@ -411,6 +411,13 @@ def parse_headers(
 
         return (headers, raw_headers, close_conn, encoding, upgrade, chunked)
 
+    def set_upgraded(self, val: bool) -> None:
+        """Set connection upgraded (to websocket) mode.
+
+        :param bool val: new state.
+        """
+        self._upgraded = val
+
 
 class HttpRequestParser(HttpParser):
     """Read request status line. Exception .http_exceptions.BadStatusLine

aiohttp/web_protocol.py

@@ -549,6 +549,12 @@ async def finish_response(self,
         can get exception information. Returns True if the client disconnects
         prematurely.
         """
+        if self._request_parser is not None:
+            self._request_parser.set_upgraded(False)
+            self._upgrade = False
+            if self._message_tail:
+                self._request_parser.feed_data(self._message_tail)
+                self._message_tail = b''
         try:
             prepare_meth = resp.prepare
         except AttributeError:

tests/test_web_websocket_functional.py

@@ -5,7 +5,7 @@
 import pytest
 
 import aiohttp
-from aiohttp import web
+from aiohttp import WSServerHandshakeError, web
 from aiohttp.http import WSMsgType
 
 
@@ -827,3 +827,29 @@ async def handler(request):
     ws = await client.ws_connect('/')
     with pytest.raises(TypeError):
         await ws.receive_bytes()
+
+
+async def test_bug3380(loop, aiohttp_client) -> None:
+
+    async def handle_null(request):
+        return aiohttp.web.json_response({'err': None})
+
+    async def ws_handler(request):
+        return web.Response(status=401)
+
+    app = web.Application()
+    app.router.add_route('GET', '/ws', ws_handler)
+    app.router.add_route('GET', '/api/null', handle_null)
+
+    client = await aiohttp_client(app)
+
+    resp = await client.get('/api/null')
+    assert (await resp.json()) == {'err': None}
+    resp.close()
+
+    with pytest.raises(WSServerHandshakeError):
+        await client.ws_connect('/ws')
+
+    resp = await client.get('/api/null', timeout=1)
+    assert (await resp.json()) == {'err': None}
+    resp.close()