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Send code 1012 on shutdown for websockets #1816

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Jan 6, 2023
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2 changes: 1 addition & 1 deletion setup.cfg
Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@ plugins =

[coverage:report]
precision = 2
fail_under = 98.50
fail_under = 98.80
show_missing = true
skip_covered = true
exclude_lines =
Expand Down
34 changes: 28 additions & 6 deletions tests/protocols/test_websocket.py
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
import asyncio
import typing

import httpx
import pytest
Expand Down Expand Up @@ -713,11 +714,22 @@ async def app(scope, receive, send):
message = await receive()
if message["type"] == "websocket.connect":
await send_accept_task.wait()
await send({"type": "websocket.accept"})
disconnect_message = await receive()

response: typing.Optional[httpx.Response] = None

async def websocket_session(uri):
await websockets.client.connect(uri)
nonlocal response
async with httpx.AsyncClient() as client:
response = await client.get(
f"http://127.0.0.1:{unused_tcp_port}",
headers={
"upgrade": "websocket",
"connection": "upgrade",
"sec-websocket-version": "13",
"sec-websocket-key": "dGhlIHNhbXBsZSBub25jZQ==",
},
)

config = Config(
app=app,
Expand All @@ -731,9 +743,12 @@ async def websocket_session(uri):
websocket_session(f"ws://127.0.0.1:{unused_tcp_port}")
)
await asyncio.sleep(0.1)
task.cancel()
send_accept_task.set()

task.cancel()
assert response is not None
assert response.status_code == 500, response.text
assert response.text == "Internal Server Error"
Comment on lines +749 to +751
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We are now testing what the client receives, instead of only the ASGI application.

assert disconnect_message == {"type": "websocket.disconnect", "code": 1006}
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@Kludex Kludex Dec 26, 2022

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Hmm... On a second thought... This doesn't make sense, does it? Why are we even sending a websocket.disconnect when the handshake was not even completed? 🤔

I think this was on purpose because then the application could receive a websocket event, but thinking about it again, does it make sense?

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I need to check the issues/PRs about this decision. It shouldn't be a blocker for this PR tho.

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According to django/asgiref#364 it's fine.



Expand All @@ -744,6 +759,7 @@ async def test_send_close_on_server_shutdown(
ws_protocol_cls, http_protocol_cls, unused_tcp_port: int
):
disconnect_message = {}
server_shutdown_event = asyncio.Event()

async def app(scope, receive, send):
nonlocal disconnect_message
Expand All @@ -755,10 +771,13 @@ async def app(scope, receive, send):
disconnect_message = message
break

websocket: typing.Optional[websockets.client.WebSocketClientProtocol] = None

async def websocket_session(uri):
async with websockets.client.connect(uri):
while True:
await asyncio.sleep(0.1)
nonlocal websocket
async with websockets.client.connect(uri) as ws_connection:
websocket = ws_connection
await server_shutdown_event.wait()

config = Config(
app=app,
Expand All @@ -773,7 +792,10 @@ async def websocket_session(uri):
)
await asyncio.sleep(0.1)
disconnect_message_before_shutdown = disconnect_message
server_shutdown_event.set()

assert websocket is not None
assert websocket.close_code == 1012
assert disconnect_message_before_shutdown == {}
assert disconnect_message == {"type": "websocket.disconnect", "code": 1012}
task.cancel()
Expand Down
5 changes: 4 additions & 1 deletion uvicorn/protocols/websockets/websockets_impl.py
Original file line number Diff line number Diff line change
Expand Up @@ -90,7 +90,6 @@ def __init__(
self.connect_sent = False
self.lost_connection_before_handshake = False
self.accepted_subprotocol: Optional[Subprotocol] = None
self.transfer_data_task: asyncio.Task = None # type: ignore[assignment]
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This is necessary to call fail_connection(), because internally there's a check like if hasattr(self, "transfer_data_task"), which should succeed.


self.ws_server: Server = Server() # type: ignore[assignment]

Expand Down Expand Up @@ -145,6 +144,10 @@ def connection_lost(self, exc: Optional[Exception]) -> None:

def shutdown(self) -> None:
self.ws_server.closing = True
if self.handshake_completed_event.is_set():
self.fail_connection(1012)
else:
self.send_500_response()
Comment on lines +147 to +150
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This is the change that motivated this PR.

We were only sending 1006 to the client, even when the handshake was not completed.

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Why self.fail_connection(1012) instead of just calling self.close(1012)?

I've been look at websockets server.close() and procotol.close() to see why uvicorn isn't calling `close(), but haven't gotten terribly far yet.

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Because close() is async.

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Ahh, missed the lack of async here.

Looking deeper at the difference, it seems like the primary difference is fail_connection will proactively cancel the data transfer task but close will simply send the close frame and then wait.

Is there any consequence to that distinction here? My very, very basic testing seems to suggest with uvicorn tasks are given a chance to shutdown cleanly, but I'm still testing.

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Yeah, this code still waits for it to finish. 👍

self.transport.close()

def on_task_complete(self, task: asyncio.Task) -> None:
Expand Down
18 changes: 7 additions & 11 deletions uvicorn/protocols/websockets/wsproto_impl.py
Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,6 @@
import typing
from urllib.parse import unquote

import h11
import wsproto
from wsproto import ConnectionType, events
from wsproto.connection import ConnectionState
Expand Down Expand Up @@ -232,17 +231,14 @@ def send_500_response(self) -> None:
(b"content-type", b"text/plain; charset=utf-8"),
(b"connection", b"close"),
]
if self.conn.connection is None:
output = self.conn.send(wsproto.events.RejectConnection(status_code=500))
else:
msg = h11.Response(
status_code=500, headers=headers, reason="Internal Server Error"
output = self.conn.send(
wsproto.events.RejectConnection(
status_code=500, headers=headers, has_body=True
)
output = self.conn.send(msg)
msg = h11.Data(data=b"Internal Server Error")
output += self.conn.send(msg)
msg = h11.EndOfMessage()
output += self.conn.send(msg)
)
output += self.conn.send(
wsproto.events.RejectData(data=b"Internal Server Error")
)
Comment on lines -235 to +241
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Don't be afraid here. I'll explain what's happening.

  1. We were sending RejectConnection(status_code=500) without a body, but on websockets implementation we were sending the "Internal Server Error" body on the analogous behavior. The RejectData matches the behavior.
  2. We are removing the conditional because it's never reached, and the reason for it is that we only call send_500_response is we didn't complete the handshake - which makes a lot of sense to remove it.

Hope it's clear.

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Am I missing EndOfMessage? I need to check this.

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No, I'm not missing it. wsproto internally adds the h11.EndOfMessage. 🙏

self.transport.write(output)

async def run_asgi(self) -> None:
Expand Down