ConsoleApp1 echo request octets

ConsoleApp1.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>

</Project>

Program.cs

using System;
using System.Globalization;
using System.Net.Http;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            MainAsync(args).GetAwaiter().GetResult();
        }

        static async Task MainAsync(string[] args)
        {
            var listener = new TcpListener(4321);
            listener.Start();

            Tangent();

            while (true)
            {
                var client = await listener.AcceptTcpClientAsync();
                HandleAsync(client);
            }
        }

        private static async void HandleAsync(TcpClient client)
        {
            var stream = client.GetStream();

            var buffer = new byte[50 << 10];
            var offset = 0;

            var sb = new StringBuilder();
            sb.Append($"HTTP/1.1 200 OK\r\n");
            sb.Append($"Server: ConsoleApp2\r\n");
            sb.Append($"Connection: close\r\n");
            sb.Append($"Content-Type: text/plain\r\n");
            sb.Append("\r\n");
            stream.Write(Encoding.ASCII.GetBytes(sb.ToString()));

            var cts = new CancellationTokenSource(TimeSpan.FromMilliseconds(500));
            try
            {
                while (true)
                {
                    var bytes = await stream.ReadAsync(buffer, offset, buffer.Length - offset, cts.Token);
                    var part1 = "";
                    var part2 = "";
                    for (var i = 0; i != bytes; ++i)
                    {
                        var ch = buffer[offset + i];
                        if (ch >= 0x20 && ch < 0x80)
                        {
                            part2 += (char)ch;
                        }
                        else
                        {
                            part2 += $"[{ch:x2}]";
                        }
                        part1 += ($" {buffer[offset + i]:x2}");
                        if ((i % 32) == 31)
                        {
                            var line = $"{part1.PadRight(100)}{part2}\r\n";
                            Console.Write(line);
                            stream.Write(Encoding.ASCII.GetBytes(line));
                            part1 = "";
                            part2 = "";
                        }
                    }
                    offset += bytes;
                    var partial = $"{part1.PadRight(100)}{part2}\r\n";
                    Console.Write(partial);
                    stream.Write(Encoding.ASCII.GetBytes(partial));
                    if (bytes == 0)
                    {
                        break;
                    }
                }
            }
            catch
            {
                stream.Close();
                client.Close();
            }
        }

        private static async void Tangent()
        {
            var client = new HttpClient();
            var x = await client.GetAsync("http://localhost:4321/q=robé");
        }
    }
}