x/net/websocket: hangs when connecting to a plain TCP socket

[jurisbu]

What version of Go are you using (go version)?

$ go version
go version go1.20.1 linux/amd64

golang.org/x/net v0.7.0

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

go env Output

$ go env

What did you do?

Given a dumb TCP server emulated by socat STDIO TCP4-LISTEN:12345,fork, creating a websocket client by dialing to this server locks up the "dialing routine" and I can observe 1 CPU thread use 100%.

// main.go
package main

import (
	"log"
	
	"golang.org/x/net/websocket"
)

func main() {
	origin := "http://localhost/"
	url := "ws://localhost:12345"

	log.Println("Dial ...")

	websocket.Dial(url, "", origin)

	log.Println("Done")
}

What did you expect to see?

• A failure in WebSocket handshake/upgrade attempt, maybe after a timeout.
• A way to control network read vi say SetReadDeadline(...) or alike.

What did you see instead?

A thread lockup waiting for network read, probably.