race condition causes @libp2p/tcp close method to hang

[tabcat]

• Version: latest

• Subsystem: @libp2p/tcp

Severity: Low

Description

The hanging promise is to do with shutting down the tcp server

js-libp2p/packages/transport-tcp/src/listener.ts

Lines 364 to 372 in 1cbfd6c

	await new Promise<void>((resolve, reject) => {
	this.server.close(err => {
	if (err != null) {
	reject(err)
	return
	}
	resolve()
	})

For server.close to resolve all socket connections must be closed.
The connections are closed inside of the close method.

js-libp2p/packages/transport-tcp/src/listener.ts

Lines 306 to 308 in 1cbfd6c

	this.connections.forEach(conn => {
	conn.abort(err)
	})

The connections are tracked in the onSocket listener method with the property this.connections.

js-libp2p/packages/transport-tcp/src/listener.ts

Lines 197 to 202 in 1cbfd6c

	this.log('new inbound connection %s', maConn.remoteAddr)
	this.context.upgrader.upgradeInbound(maConn)
	.then((conn) => {
	this.log('inbound connection upgraded %s', maConn.remoteAddr)
	this.connections.add(maConn)

The race condition is triggered when close is called before the connection is upgraded. At that point the socket is not added to this.connections.

Steps to reproduce the error:

https://github.com/tabcat/delay5