Ожидание завершения всех асинхронных вызовов Ping.SendAsync - C# - Ответ 2803474

Scanner s = new Scanner();
            List<IPAddress> l = s.ScanLocal(IPAddress.Parse("10.108.1.155"), Console.WriteLine);

class Scanner
    {
        public AutoResetEvent waiter;
        public delegate void Report(string s);
 
        List<IPAddress> result = new List<IPAddress>();
        Report ReportMethod;
 
        public Scanner()
        {
            this.waiter = new AutoResetEvent(false);
        }
 
        public List<IPAddress> ScanLocal(IPAddress hostAddress, Report Method)
        {
            ReportMethod = Method;
 
            IPHostEntry host = Dns.GetHostEntry(hostAddress);
 
            byte[] ip = host.AddressList[4].GetAddressBytes();
            int host_ip = ip[3];
 
            for (ip[3] = 0; ip[3] < host_ip; ip[3]++)
                AddIfAlive(new IPAddress(ip));
 
            for (ip[3] = (byte)(host_ip + 1); ip[3] != 255; ip[3]++)
                AddIfAlive(new IPAddress(ip));
 
            return result;
        }
 
        public void AddIfAlive(IPAddress address)
        {
            Ping pingSender = new Ping();
            PingOptions packetOptions = new PingOptions(50, true);
            byte[] packetData = Encoding.ASCII.GetBytes("....");
 
            pingSender.PingCompleted += new PingCompletedEventHandler(PingCompletedCallback);
 
            pingSender.SendAsync(address, 10, packetData, packetOptions, waiter);
        }
 
        private void PingCompletedCallback(object sender, PingCompletedEventArgs e)
        {
            PingReply reply = e.Reply;
            if (reply.Status == IPStatus.Success)
            {
                result.Add(e.Reply.Address);
                ReportMethod.Invoke(e.Reply.Address.ToString());
            }
        }