Ping with UDP

receiver.cs

using System.Net;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using Udping.Base;

var pingStructSizeOf = Marshal.SizeOf<PingStruct>();

var portStr = args.FirstOrDefault(arg => arg.StartsWith("--port=", StringComparison.OrdinalIgnoreCase)) ?? "--port=16789";
var port = short.Parse(portStr["--port=".Length..]);

var baseReceiveFrom = new IPEndPoint(IPAddress.Any, port);

using var udpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
udpSocket.Bind(baseReceiveFrom);

Span<byte> received = stackalloc byte[pingStructSizeOf * 16];
while (true)
{
    EndPoint receiveFrom = baseReceiveFrom;
    var receivedLength = udpSocket.ReceiveFrom(received, ref receiveFrom);
    if (receivedLength == 0)
        break;

    udpSocket.SendTo(received.Slice(0, receivedLength), receiveFrom);
}

sender.cs

using System.Net;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using Udping.Base;

var pingStructSizeOf = Marshal.SizeOf<PingStruct>();

var addrStr = args.FirstOrDefault(arg => arg.StartsWith("--addr=", StringComparison.OrdinalIgnoreCase)) ?? "--addr=127.0.0.1";
var portStr = args.FirstOrDefault(arg => arg.StartsWith("--port=", StringComparison.OrdinalIgnoreCase)) ?? "--port=16789";

var addr = IPAddress.Parse(addrStr["--addr=".Length..]);
var port = short.Parse(portStr["--port=".Length..]);

var sendTo = new IPEndPoint(addr, port);

using var udpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

var id = 0L;
Span<byte> receiveBuffer = stackalloc byte[pingStructSizeOf * 16];
while (true)
{
    var pingStruct = new PingStruct(++id, DateTime.Now.TimeOfDay);
    var sendBuffer = MemoryMarshal.Cast<PingStruct, byte>(MemoryMarshal.CreateSpan(ref pingStruct, 1));
    udpSocket.SendTo(sendBuffer, sendTo);

    EndPoint receiveFrom = sendTo;
    var totalReceived = udpSocket.ReceiveFrom(receiveBuffer, ref receiveFrom);

    var receiveds = MemoryMarshal.Cast<byte, PingStruct>(receiveBuffer);
    var receivedsLength = totalReceived / pingStructSizeOf;

    var currentTime = DateTime.Now.TimeOfDay;
    for (var i = 0; i < receivedsLength; ++i)
    {
        var received = receiveds[i];
        Console.WriteLine("[{0}] {1}ms", received.Id, (currentTime - received.StartTime).TotalMilliseconds);
    }
    
    Thread.Sleep(1000);
}