Hanging promise in connection.close()

[wemeetagain]

Calling conn.close() twice (without awaiting) will result in the second call hanging.

The problem is that if socket.end(cb) is called multiple times before the callback is executed, only the first callback will be executed.
Since the promise resolves in the callback, only the first conn.close() will resolve.

The socket.on('close', cb) callback will be triggered for both invocations, cancelling the timeout that provides the only other path to resolve the promise.

Here is a realistic-ish testcase showing how this may be an issue:

const Libp2p = require('libp2p')
const TCP = require('libp2p-tcp')
const MPLEX = require('libp2p-mplex')
const { NOISE } = require('libp2p-noise')

async function createNode() {
  return Libp2p.create({
    modules: {
      transport: [TCP],
      streamMuxer: [MPLEX],
      connEncryption: [NOISE],
    },
    addresses: {
      listen: ["/ip4/127.0.0.1/tcp/0"],
    },
  })
}

(async function () {
  // create nodes
  const nodes = await Promise.all(Array.from({length: 2}, createNode))

  // start nodes
  await Promise.all(nodes.map(n => n.start()))

  // connect node 0 to node 1
  nodes[0].peerStore.addressBook.add(nodes[1].peerId, nodes[1].multiaddrs)
  await nodes[0].dial(nodes[1].peerId)

  // hangUp and stop
  nodes[0].hangUp(nodes[1].peerId) // not awaited
  await Promise.all(nodes.map(n => n.stop()))

  // will hang, never complete
  console.log('will hang, never complete')
})()