code: func newListenContext(stack *stack.Stack, rcvWnd seqnum.Size, v6only bool, netProto tcpip.NetworkProtocolNumber) *listenContext {
  	l := &listenContext{
  		stack:    stack,
  		rcvWnd:   rcvWnd,
  		hasher:   sha1.New(),
  		v6only:   v6only,
  		netProto: netProto,
  	}
  
  	rand.Read(l.nonce[0][:])
  	rand.Read(l.nonce[1][:])
  
  	return l
  }
docs: // newListenContext creates a new listen context.