Added

C#/forSpbu/ConsoleNetChat/AsyncConsole.cs

@@ -0,0 +1,31 @@
+namespace ConsoleNetChat;
+
+/// <summary>
+/// Represents asynchronous console
+/// </summary>
+public static class AsyncConsole
+{
+    private static readonly Mutex ConsoleMutex = new ();
+
+    /// <summary>
+    /// Async version of Console.WriteLine
+    /// </summary>
+    /// <param name="message">Message to write</param>
+    public static void WriteLine(string message)
+    {
+        ConsoleMutex.WaitOne();
+        Console.WriteLine(message);
+        ConsoleMutex.ReleaseMutex();
+    }
+
+    /// <summary>
+    /// Async version of Console.Write
+    /// </summary>
+    /// <param name="message">Message to write</param>
+    public static void Write(string message)
+    {
+        ConsoleMutex.WaitOne();
+        Console.Write(message);
+        ConsoleMutex.ReleaseMutex();
+    }
+}

C#/forSpbu/ConsoleNetChat/Chatter.cs

@@ -0,0 +1,95 @@
+using System.Net.Sockets;
+using System.Net;
+using System.Net.NetworkInformation;
+
+namespace ConsoleNetChat;
+
+/// <summary>
+/// Class for chat member
+/// </summary>
+public class Chatter
+{
+    protected TcpClient Client = new ();
+    protected StreamWriter? Writer;
+
+    /// <summary>
+    /// Sends message into chat
+    /// </summary>
+    /// <param name="message">Message to send</param>
+    /// <exception cref="ChatterException">If connection is close</exception>
+    public async Task SendMessage(string message)
+    {
+        if (Writer == null)
+        {
+            throw new ChatterException("Not started");
+        }
+        await Writer.WriteLineAsync(message);
+    }
+
+    private static async Task HandleClient(TcpClient client)
+    {
+        using var reader = new StreamReader(client.GetStream());
+
+        while (IsConnected(client))
+        {
+            try
+            {
+                var data = await reader.ReadLineAsync();
+                if (string.IsNullOrEmpty(data))
+                {
+                    continue;
+                }
+
+                AsyncConsole.Write($"External: {data}\n");
+            }
+            catch (Exception e) when (e is ArgumentOutOfRangeException or ObjectDisposedException or InvalidOperationException)
+            {
+            }
+        }
+
+        AsyncConsole.WriteLine("Disconnected");
+        Environment.Exit(0);
+    }
+
+    private static bool IsConnected(TcpClient client)
+    {
+        return GetState(client) == TcpState.Established;
+    }
+
+    private static TcpState GetState(TcpClient tcpClient)
+    {
+        try
+        {
+            var connectionInfo = IPGlobalProperties.GetIPGlobalProperties()
+                .GetActiveTcpConnections()
+                .SingleOrDefault(x => x.LocalEndPoint.Equals(tcpClient.Client.LocalEndPoint));
+            return connectionInfo?.State ?? TcpState.Unknown;
+        }
+        catch (ObjectDisposedException)
+        {
+            return TcpState.Closed;
+        }
+    } 
+
+    /// <summary>
+    /// Finishes the chat
+    /// </summary>
+    public void Disconnect()
+    {
+        Client.Close();
+        AsyncConsole.WriteLine("Disconnected");
+    }
+
+    /// <summary>
+    /// Listens for external messages
+    /// </summary>
+    /// <exception cref="ChatterException">If connection is closed</exception>
+    public async Task Listen()
+    {
+        if (!IsConnected(Client))
+        {
+            throw new ChatterException("Cant listen: no connection");
+        }
+        await HandleClient(Client);
+    }
+} 

C#/forSpbu/ConsoleNetChat/ChatterException.cs

@@ -0,0 +1,12 @@
+namespace ConsoleNetChat;
+
+public class ChatterException : Exception
+{
+    public ChatterException()
+    {
+    }
+
+    public ChatterException(string message) : base(message)
+    {
+    }
+}

C#/forSpbu/ConsoleNetChat/Client.cs

@@ -0,0 +1,32 @@
+using System.Net;
+using System.Net.Sockets;
+
+namespace ConsoleNetChat;
+
+/// <summary>
+/// Represents chat client
+/// </summary>
+public class Client : Chatter
+{
+    /// <summary>
+    /// Connects to the server
+    /// </summary>
+    /// <param name="addr">Server address</param>
+    /// <param name="port">Server port</param>
+    /// <exception cref="ChatterException">If error occured(e.g. no server on that address</exception>
+    public async Task Connect(IPAddress addr, int port)
+    {
+        try
+        {
+            await Client.ConnectAsync(addr, port);
+        }
+        catch (Exception e) when (e is ArgumentNullException or ArgumentOutOfRangeException or SocketException or ObjectDisposedException)
+        {
+            throw new ChatterException("Connection impossible");
+        }
+
+        Writer = new StreamWriter(Client.GetStream());
+        Writer.AutoFlush = true;
+        AsyncConsole.WriteLine("Connected");
+    }
+}

C#/forSpbu/ConsoleNetChat/ConsoleNetChat.csproj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net6.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+</Project>

C#/forSpbu/ConsoleNetChat/Program.cs

@@ -0,0 +1,110 @@
+using System.Net;
+using ConsoleNetChat;
+
+switch (args.Length)
+{
+    case < 1 or > 2:
+        AsyncConsole.WriteLine("Incorrect arguments");
+        return;
+    case 1:
+    {
+        if (!int.TryParse(args[0], out var port))
+        {
+            AsyncConsole.WriteLine("Incorrect port");
+            return;
+        }
+
+        var server = new Server();
+        try
+        {
+            await server.Connect(port);
+        }
+        catch (ChatterException e)
+        {
+            AsyncConsole.WriteLine(e.Message);
+            return;
+        }
+
+        try
+        {
+#pragma warning disable CS4014 // This is started in background thread
+            server.Listen();
+#pragma warning restore CS4014 // This is started in background thread
+        }
+        catch (ChatterException e)
+        {
+            AsyncConsole.WriteLine(e.Message);
+            return;
+        }
+
+        while (true)
+        {
+            var message = Console.ReadLine();
+            if (string.IsNullOrEmpty(message))
+            {
+                continue;
+            }
+            await server.SendMessage(message);
+            if (message == "exit")
+            {
+                server.Disconnect();
+                return;
+            }
+        }
+
+        break;
+    }
+    default:
+    {
+        if (!int.TryParse(args[1], out var port))
+        {
+            AsyncConsole.WriteLine("Incorrect port");
+            return;
+        }
+        if (!IPAddress.TryParse(args[0], out var addr))
+        {
+            AsyncConsole.WriteLine("Incorrect address");
+            return;
+        }
+
+        var client = new Client();
+        try
+        {
+            await client.Connect(addr, port);
+        }
+        catch (ChatterException e)
+        {
+            AsyncConsole.WriteLine(e.Message);
+            return;
+        }
+
+        try
+        {
+#pragma warning disable CS4014 // This is started in background thread
+            client.Listen();
+#pragma warning restore CS4014 // This is started in background thread
+        }
+        catch (ChatterException e)
+        {
+            AsyncConsole.WriteLine(e.Message);
+            return;
+        }
+
+        while (true)
+        {
+            var message = Console.ReadLine();
+            if (string.IsNullOrEmpty(message))
+            {
+                continue;
+            }
+            await client.SendMessage(message);
+            if (message == "exit")
+            {
+                client.Disconnect();
+                return;
+            }
+        }
+
+        break;
+    }
+}

C#/forSpbu/ConsoleNetChat/Server.cs

@@ -0,0 +1,36 @@
+using System.Diagnostics;
+using System.Net;
+using System.Net.NetworkInformation;
+using System.Net.Sockets;
+
+namespace ConsoleNetChat;
+
+/// <summary>
+/// Represents chat server
+/// </summary>
+public class Server : Chatter
+{
+    private TcpListener? _listener;
+
+    /// <summary>
+    /// Waits for chat client
+    /// </summary>
+    /// <param name="port">Port to open connection onto</param>
+    /// <exception cref="ChatterException">If error occured(e.g. port was occupied)</exception>
+    public async Task Connect(int port)
+    {
+        try
+        {
+            _listener = new TcpListener(IPAddress.Any, port);
+            _listener.Start();
+            Client = await _listener.AcceptTcpClientAsync();
+        }
+        catch (Exception e) when (e is ArgumentNullException or ArgumentOutOfRangeException or SocketException or InvalidOperationException)
+        {
+            throw new ChatterException("Connection interrupted");
+        }
+        Writer = new StreamWriter(Client.GetStream());
+        Writer.AutoFlush = true;
+        AsyncConsole.WriteLine("Connected");
+    }
+}

C#/forSpbu/forSpbu.sln

@@ -10,6 +10,12 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "03.03", "03.03", "{882A9B9C
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "10.03", "10.03", "{EA6FC7D9-BDFB-49CD-AC00-FC5DDC5274B0}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "2023", "2023", "{6EA2679E-EBFE-46CA-ACD5-0B9F756FF69C}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "02.11", "02.11", "{1A79381A-96DE-408C-A93E-225A594FDB00}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ConsoleNetChat", "ConsoleNetChat\ConsoleNetChat.csproj", "{3689A376-E83D-4C8B-804B-876E9CE7C881}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -21,12 +27,18 @@ Global
 		{E007586F-9760-4744-BB25-EDEFD6BA860C}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{E007586F-9760-4744-BB25-EDEFD6BA860C}.Release|Any CPU.Build.0 = Release|Any CPU
 		{A4F6ADD5-85FD-4F67-8B29-549DDDF6F82E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-       	{A4F6ADD5-85FD-4F67-8B29-549DDDF6F82E}.Debug|Any CPU.Build.0 = Debug|Any CPU
-       	{A4F6ADD5-85FD-4F67-8B29-549DDDF6F82E}.Release|Any CPU.ActiveCfg = Release|Any CPU
-       	{A4F6ADD5-85FD-4F67-8B29-549DDDF6F82E}.Release|Any CPU.Build.0 = Release|Any CPU
+								{A4F6ADD5-85FD-4F67-8B29-549DDDF6F82E}.Debug|Any CPU.Build.0 = Debug|Any CPU
+								{A4F6ADD5-85FD-4F67-8B29-549DDDF6F82E}.Release|Any CPU.ActiveCfg = Release|Any CPU
+								{A4F6ADD5-85FD-4F67-8B29-549DDDF6F82E}.Release|Any CPU.Build.0 = Release|Any CPU
+		{3689A376-E83D-4C8B-804B-876E9CE7C881}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{3689A376-E83D-4C8B-804B-876E9CE7C881}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{3689A376-E83D-4C8B-804B-876E9CE7C881}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{3689A376-E83D-4C8B-804B-876E9CE7C881}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
-	    {E007586F-9760-4744-BB25-EDEFD6BA860C} = {D3FCB669-E93F-4F0B-B9C5-6592CE93AC7F}
+					{E007586F-9760-4744-BB25-EDEFD6BA860C} = {D3FCB669-E93F-4F0B-B9C5-6592CE93AC7F}
 		{A4F6ADD5-85FD-4F67-8B29-549DDDF6F82E} = {D3FCB669-E93F-4F0B-B9C5-6592CE93AC7F}
+		{1A79381A-96DE-408C-A93E-225A594FDB00} = {6EA2679E-EBFE-46CA-ACD5-0B9F756FF69C}
+		{3689A376-E83D-4C8B-804B-876E9CE7C881} = {1A79381A-96DE-408C-A93E-225A594FDB00}
 	EndGlobalSection
 EndGlobal