Concurrency issues when using websockets + proxies

[sleeyax]

For some reason connections start to fail when using a (rotating) proxy over websockets. Mostly weird EOF errors.

There's some progress being made on this issue in this branch, including a mechanism to reconnect on failure, though it's far from perfect:

2022/05/15 17:44:37 main 1: server is starting
2022/05/15 17:44:39 main 0: server is starting
2022/05/15 17:44:41 main 2: server is starting
2022/05/15 17:44:42 reader: server closed the connection unexpectedly [websocket: close 1006 (abnormal closure): unexpected EOF], reconnecting...
2022/05/15 17:44:44 reader: server closed the connection unexpectedly [websocket: close 1006 (abnormal closure): unexpected EOF], reconnecting...
2022/05/15 17:44:46 reader: server closed the connection unexpectedly [websocket: close 1006 (abnormal closure): unexpected EOF], reconnecting...
2022/05/15 17:44:49 reader: server closed the connection unexpectedly [websocket: close 1006 (abnormal closure): unexpected EOF], reconnecting...
2022/05/15 17:44:51 reader: server closed the connection unexpectedly [websocket: close 1006 (abnormal closure): unexpected EOF], reconnecting...
2022/05/15 17:44:53 reader: server closed the connection unexpectedly [websocket: close 1006 (abnormal closure): unexpected EOF], reconnecting...

The issue is likely any of the following:

• deadlock in a goroutine somewhere (although go's race detector can't find anything in particular)
• the underlying connection getting abruptly closed due to some bug/issue in gorilla websockets, gotcha, fhttp, utls or even the Go language itself (yes, there's lots of possible points of failure!).
• the remote server actually refusing the connection due to some detection mechanism

I've already wasted a ton of time working on this issue and unfortunately it's not worth my time anymore at this point. Up for grabs if anyone wants to work on this.