res.cork(() => res.upgrade()) in Upgrade handler with ws.send() in Open handler = close connection

[e3dio]

Doing as described in title can result in websocket dirty close connection, to prevent this can do setTimeout(() => ws.send('msg'), 0) if need to send message in Open handler after async Upgrade. I think calling res.upgrade() while corked calls the Open handler still corked and ws.send inside the upgrade cork can cause some tcp or protocol error. Removing res.cork() fixes connection error but displays warnings that cork is missing

[uNetworkingAB]

Do you have a full reproducer?

[e3dio]

Here is example it causes issue like 50% of the time, look for immediate socket close after open

import { App } from 'uWebSockets.js';

const port = 80;

App()

.get('/', r => r.end(`<script>
   ws = new WebSocket('ws'+location.protocol.slice(4,-1)+'://'+location.host+'/ws');
   ws.onopen = e => console.log('open');
   ws.onmessage = e => console.log('message', e.data);
   ws.onclose = e => console.log('close');
</script>`))

.ws('/ws', {
   upgrade: async (res, req, context) => {
      const wsHeaders = [ req.getHeader('sec-websocket-key'), req.getHeader('sec-websocket-protocol'), req.getHeader('sec-websocket-extensions') ];
      res.onAborted(() => res.aborted = true);
      await new Promise(r => setTimeout(r, 100));
      res.cork(() => res.upgrade({}, ...wsHeaders, context));
   },
   open: ws => console.log('open') || ws.send('w'.repeat(56)),
   message: ws => console.log('message'),
   close: ws => console.log('close'),
})

.listen(port, s => s && console.log(`http://localhost:${port}`));

[e3dio]