C#•3mo ago

SocketException, TCPListener, TCPClient reason?

a) Why do I get a SocketException when opening a TCPListener + TCPClient @ IP 127.0.0.1, Port 5089 (there is only my listener at that port, and only my client sends on it) telling me the system actively refused the connection - however it still goes through and sends everything/gets received?! and the firewall didn't block it b) what information to look at to know such stuff?

62 Replies

Buddy•3mo ago

Port is in use Doesn't have to be your socket Did you try changing port? Or use 0 as port 0 meaning it will use a random available port

stnOP•3mo ago

port isn't in use, since there's only my 1 server and my 1 client

Buddy•3mo ago

Any application on your computer can use the port it doesn't have to be your program

stnOP•3mo ago

Nothing uses the port but these 2 programs - says netstat

Buddy•3mo ago

And what happens if you change the port as previously mentioned? say to 0 so it uses a random available port

stnOP•3mo ago

changing the port didn't help, tried multiple very crazy ones or actually tried several that were ok in netstat

Unknown User•3mo ago

Message Not Public

stnOP•3mo ago

wait I don't use IIS/IIS Express, my original intention for using the TCPClient was just to be able to save some Diagnostic data to disk from a SourceGenerator - which sadly have an Analyzer Rule that prohibits usage of IO and the File- / Path-Namespaces during their activities. [which makes it a bit hard to debug their work] I give you the code in a sec

stnOP•3mo ago

server: https://pastebin.com/FQHQ7AX0 client: https://pastebin.com/LGDpsTcg

Pastebin

using System;using System.Diagnostics;using System.Net;using System...

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Client - Pastebin.com

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stnOP•3mo ago

nope, no firewall because it actually works the send works, but I get an exception every time I do it additionally my firewall hasn't had anything in the blocked log + I found out when the server is configured to use port 0 - this is when the connection won't work (since server port = 0, client port != 0, the connection fails and that is the only time that the exception ever gets caught in my catch (Socketexception ex), clientside the other times when the server is set correctly and when the connection actually works but yet excepts... it doesn't get caught

Unknown User•3mo ago

Message Not Public

333fred•3mo ago

which sadly have an Analyzer Rule that prohibits usage of IO and the File- / Path-Namespaces during their activities

Correct. These things are verbotten. Do not use them

stnOP•3mo ago

back ok I know, but does this relate to the error I'm getting?

Unknown User•3mo ago

Message Not Public

stnOP•3mo ago

it doesn't matter what he says, because there's an analyzer rule that shows you an Error that prevents compilation when you use System.IO or System.IO.Path but it doesn't do so when using the networkstack there's no interference with the network stack to be true the one thing has nothing to do with the other so what they don't want is you spawning your own sourcecode files when using the sourcegenerator, that must have been the initial idea

333fred•3mo ago

@sharwell, this is another thing we apparently need to block

stnOP•3mo ago

of blocking IO

333fred•3mo ago

I cannot say this strongly enough: do not do IO Network calls are IO

stnOP•3mo ago

to be true

333fred•3mo ago

Do not use it We do not want you doing any kind of IO

sharwell•3mo ago

IO, in general, will not work

stnOP•3mo ago

I tried to use the AnalyzerConfigOptions , ..

var options = context.AnalyzerConfigOptions.GlobalOptions;
    if (options.TryGetValue("build_property.MyCustomProperty", out var myValue))
    {
        context.ReportDiagnostic(Diagnostic.Create(new DiagnosticDescriptor(
            "GEN001",
            "Source Generator",
            $"Value from MSBuild: {myValue}",
            "Generator",
            DiagnosticSeverity.Warning,
            true)));
    }

var options = context.AnalyzerConfigOptions.GlobalOptions;
    if (options.TryGetValue("build_property.MyCustomProperty", out var myValue))
    {
        context.ReportDiagnostic(Diagnostic.Create(new DiagnosticDescriptor(
            "GEN001",
            "Source Generator",
            $"Value from MSBuild: {myValue}",
            "Generator",
            DiagnosticSeverity.Warning,
            true)));
    }

but it didn't work, I couldn't get the diagnostic outside using the steps described

sharwell•3mo ago

what do you mean "couldn't get the diagnostic outside"?

stnOP•3mo ago

(wherever that was, i suppose microsoft.com) well I don't remember what the goal was whether it was spawning a file or printing it to console or something else I cannot remember but it clearly didn't work, then I went for writing my TCP client / sv that's the big deal? I know this is not a good procedure, since you state, whenever IO happens during SourceGenerators' activities - you cannot guarantee the correct execution and random stuff might happen

333fred•3mo ago

If you're trying to troubleshoot an analyzer, write a unit test Much easier, more repeatable

stnOP•3mo ago

no I am not trying to trouble shoot an analyzer

333fred•3mo ago

And at the end, you have tests

stnOP•3mo ago

I tried to trouble shoot my own code in the sourcegen

333fred•3mo ago

Then why are you putting IO in your source generator?

stnOP•3mo ago

because I cannot use the Debugger inside it?! and the Diagnostic didn't do whatever it was supposed to i'm afraid

333fred•3mo ago

Why do you think you can't debug your source generator? That's what tests are for

stnOP•3mo ago

because it didn't stop on any breakpoints

333fred•3mo ago

Did you write a unit test?

stnOP•3mo ago

nope

333fred•3mo ago

Then... what were you expecting?

sharwell•3mo ago

once you write a unit test, you can debug the test and it will stop at breakpoints

stnOP•3mo ago

since when do you have to write unit-tests to be able to debug VS compilation/compiled runtime

sharwell•3mo ago

that's not the way we look at it writing unit tests is so easy and so reliable for debugging analyzers and source generators that all the work on looking at other approaches became irrelevant basically there is nothing left to gain. it works as close to perfect as anyone could want

stnOP•3mo ago

why do you enforce the usage of unit-tests

333fred•3mo ago

Everyone, and I mean everyone, reacts the same way to our suggestions to write unit tests. With visceral denial. And by the time they're done, almost everyone agrees it was the right approach There are a couple here and there that still disagree. But almost everyone does not

stnOP•3mo ago

thank you for enlightening me regarding the UnitTest. and yet, does anyone of you two smart people, have an idea what the answer to my actual question is?

: a) Why do I get a SocketException when opening a TCPListener + TCPClient @ IP 127.0.0.1, Port 5089 (there is only my listener at that port, and only my client sends on it)  telling me  the system actively refused the connection - however it still goes through and sends everything/gets received?! and the firewall didn't block it
b) what information to look at to know such stuff?

sharwell•3mo ago

what question was that? 1) IO behavior is undefined. SocketException is allowed. Not having a SocketException is also allowed.

stnOP•3mo ago

in regard of 1) ok, what if I repeat it without a sourcegen and the same thing happens?

sharwell•3mo ago

then it would be a question for dotnet/runtime, different team

stnOP•3mo ago

undefined I guess means you're using a not-thread-safe-way of parallel task processing? is that correct? (thread safe for invocation of external code)

sharwell•3mo ago

undefined means you cannot infer anything about the behavior

stnOP•3mo ago

well, but why is it undefined?

sharwell•3mo ago

because we chose to not attempt to define or support it it's fairly common in compiler work to leave things as undefined as soon as we define it, it becomes a guarantee that we have to preserve basically forever

stnOP•3mo ago

https://pasteboard.co/0qGjjSNgmFYE.png

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stnOP•3mo ago

see, I unloaded all sourcegenerator projects, and removed any code that depended on that and yet I get the same message

sharwell•3mo ago

I have no experience with that API

stnOP•3mo ago

it has nothing to do with the API, I can show you what happens: 1/3: Program.Main:

public static void Main(string[] args)
{
    try
    {
        MsgSender.SendLogMessage($"Started.").Wait();
        Console.WriteLine($"Started.");
        Console.ReadKey();
    }
    catch (SocketException ex)
    {
        D.W("SocketException ---> "+ ex.ToString() + $"{ex.ErrorCode} SocketErrorCode: {ex.SocketErrorCode} Inner:{ex.InnerException} ");

    }
    catch(Exception ex ) { 
        D.W($"{ex}");
    }
}

public static void Main(string[] args)
{
    try
    {
        MsgSender.SendLogMessage($"Started.").Wait();
        Console.WriteLine($"Started.");
        Console.ReadKey();
    }
    catch (SocketException ex)
    {
        D.W("SocketException ---> "+ ex.ToString() + $"{ex.ErrorCode} SocketErrorCode: {ex.SocketErrorCode} Inner:{ex.InnerException} ");

    }
    catch(Exception ex ) { 
        D.W($"{ex}");
    }
}

2/3: Client:

public class MsgSender
{
    public static MsgMode Mode = MsgMode.TCP;
    public static int     Port = 7334;
    public static async Task SendLogMessage(string msg)
    {
        await Task.Delay(500);
        switch (Mode) {
            case MsgMode.TCP: {
                try {
                    await SendTcpMsg(msg).ConfigureAwait(false);
                }
                catch (SocketException ex) {
                    // this should now catch any socket-related exceptions
                    Console.WriteLine($"SocketException: {ex.Message} SocketError: {ex.SocketErrorCode} Msg:{ex.Message} ErrCode:{ex.ErrorCode} NativeErrCode:{ex.NativeErrorCode} ");
                    D.W($"SocketException: {ex.Message}");
                }
                catch (Exception ex)
                {
                    Console.WriteLine(".." +ex);
                } 

                break;
            }
            case MsgMode.NamedPipe:
            {
                SendNamedPipeMsg(msg);

                break;
            }
        }
    }

public class MsgSender
{
    public static MsgMode Mode = MsgMode.TCP;
    public static int     Port = 7334;
    public static async Task SendLogMessage(string msg)
    {
        await Task.Delay(500);
        switch (Mode) {
            case MsgMode.TCP: {
                try {
                    await SendTcpMsg(msg).ConfigureAwait(false);
                }
                catch (SocketException ex) {
                    // this should now catch any socket-related exceptions
                    Console.WriteLine($"SocketException: {ex.Message} SocketError: {ex.SocketErrorCode} Msg:{ex.Message} ErrCode:{ex.ErrorCode} NativeErrCode:{ex.NativeErrorCode} ");
                    D.W($"SocketException: {ex.Message}");
                }
                catch (Exception ex)
                {
                    Console.WriteLine(".." +ex);
                } 

                break;
            }
            case MsgMode.NamedPipe:
            {
                SendNamedPipeMsg(msg);

                break;
            }
        }
    }

    [NoDebug]
    private async static Task SendTcpMsg(string msg)
    {
        await Task.Delay(100);
        try
        {
            // Ensure all connection and stream activities are inside the try-catch
            using (TcpClient client = new TcpClient("localhost", Port))
            {
                Console.WriteLine($"Sending Message: {msg}");

                client.NoDelay = true;

                byte[] data = Encoding.UTF8.GetBytes(msg);
                using (NetworkStream stream = client.GetStream())
                {
                    
                    stream.Write(data, 0, data.Length);
                    //stream.Close(); // Close the stream explicitly
                }


                
                await Task.Delay(10);
            }
        }
        catch (SocketException ex)
        {
            // this should now catch any socket-related exceptions
            Console.WriteLine($"SocketException: {ex.Message} SocketError: {ex.SocketErrorCode} Msg:{ex.Message} ErrCode:{ex.ErrorCode} NativeErrCode:{ex.NativeErrorCode} ");
            D.W($"SocketException: {ex.Message}");
        }
        catch (IOException ex)
        {
            // catch any IO exceptions, e.g., from stream handling issues
            Console.WriteLine($"IOException: {ex.Message}");
            D.W($"IOException: {ex.Message}");
        }
        catch (Exception ex)
        {
            // catch any other exceptions
            Console.WriteLine($"Error: {ex.Message}");
            D.W($"Error: {ex.Message}");
        }
    }

    [NoDebug]
    private async static Task SendTcpMsg(string msg)
    {
        await Task.Delay(100);
        try
        {
            // Ensure all connection and stream activities are inside the try-catch
            using (TcpClient client = new TcpClient("localhost", Port))
            {
                Console.WriteLine($"Sending Message: {msg}");

                client.NoDelay = true;

                byte[] data = Encoding.UTF8.GetBytes(msg);
                using (NetworkStream stream = client.GetStream())
                {
                    
                    stream.Write(data, 0, data.Length);
                    //stream.Close(); // Close the stream explicitly
                }


                
                await Task.Delay(10);
            }
        }
        catch (SocketException ex)
        {
            // this should now catch any socket-related exceptions
            Console.WriteLine($"SocketException: {ex.Message} SocketError: {ex.SocketErrorCode} Msg:{ex.Message} ErrCode:{ex.ErrorCode} NativeErrCode:{ex.NativeErrorCode} ");
            D.W($"SocketException: {ex.Message}");
        }
        catch (IOException ex)
        {
            // catch any IO exceptions, e.g., from stream handling issues
            Console.WriteLine($"IOException: {ex.Message}");
            D.W($"IOException: {ex.Message}");
        }
        catch (Exception ex)
        {
            // catch any other exceptions
            Console.WriteLine($"Error: {ex.Message}");
            D.W($"Error: {ex.Message}");
        }
    }

3/3 Server:

public class Program
{

    public static void Main()
    {
        Console.WriteLine($"Opening TCP Server @ {TCPServer.Port}");
        TCPServer.CreateTCPServer();

        Console.ReadKey();
    }
}


public class TCPServer
{
    private static bool isRunning = true;   
    public static  int  Port      = 7334;

    public static void CreateTCPServer()
    {
        TcpListener server = new TcpListener(IPAddress.Loopback, Port);
        try
        {   server.Start();
            Console.WriteLine($"Server started (Port:{Port})...");
            while (isRunning)
            {
                TcpClient client = server.AcceptTcpClient();
                Console.WriteLine("Client connected...");
                Task.Run(async () => await HandleClient(client));
            }
        }
        catch (Exception ex) { Debug.WriteLine($"EX: {ex}"); }
        finally        { server.Stop(); Console.WriteLine("Server stopped."); }
}
private async static  Task HandleClient(TcpClient client

public class Program
{

    public static void Main()
    {
        Console.WriteLine($"Opening TCP Server @ {TCPServer.Port}");
        TCPServer.CreateTCPServer();

        Console.ReadKey();
    }
}


public class TCPServer
{
    private static bool isRunning = true;   
    public static  int  Port      = 7334;

    public static void CreateTCPServer()
    {
        TcpListener server = new TcpListener(IPAddress.Loopback, Port);
        try
        {   server.Start();
            Console.WriteLine($"Server started (Port:{Port})...");
            while (isRunning)
            {
                TcpClient client = server.AcceptTcpClient();
                Console.WriteLine("Client connected...");
                Task.Run(async () => await HandleClient(client));
            }
        }
        catch (Exception ex) { Debug.WriteLine($"EX: {ex}"); }
        finally        { server.Stop(); Console.WriteLine("Server stopped."); }
}
private async static  Task HandleClient(TcpClient client

 private async static  Task HandleClient(TcpClient client)
 {
     try
     {
         await using (NetworkStream stream = client.GetStream())
         {
             byte[] buffer = new byte[1024];
             int    bytesRead;

             while ((bytesRead = stream.Read(buffer, 0, buffer.Length)) > 0)
             {
                 string message = Encoding.UTF8.GetString(buffer, 0, bytesRead).Trim();
                 Console.WriteLine($"MSG: {message}");

                 // write msg 2 Log
                 await File.AppendAllTextAsync("D:\\Junction\\generator7.log", message + "\n");

                 // check: quit command?
                 if (message == "!q")
                 {
                     StopServer();
                     break; // Exit
                 }
             }
         }
     }
     catch (Exception ex)
     {
         Console.WriteLine($"Error handling client: {ex.Message}");
     }
     finally
     {
         // Ensure the client connection is closed
         client.Close();
         Console.WriteLine("Client connection closed.");
     }
 }


 // stop the server
 public static void StopServer()
 { 
     Console.WriteLine("Shutdown command received. Stopping the server...");
     isRunning = false;
 }

 private async static  Task HandleClient(TcpClient client)
 {
     try
     {
         await using (NetworkStream stream = client.GetStream())
         {
             byte[] buffer = new byte[1024];
             int    bytesRead;

             while ((bytesRead = stream.Read(buffer, 0, buffer.Length)) > 0)
             {
                 string message = Encoding.UTF8.GetString(buffer, 0, bytesRead).Trim();
                 Console.WriteLine($"MSG: {message}");

                 // write msg 2 Log
                 await File.AppendAllTextAsync("D:\\Junction\\generator7.log", message + "\n");

                 // check: quit command?
                 if (message == "!q")
                 {
                     StopServer();
                     break; // Exit
                 }
             }
         }
     }
     catch (Exception ex)
     {
         Console.WriteLine($"Error handling client: {ex.Message}");
     }
     finally
     {
         // Ensure the client connection is closed
         client.Close();
         Console.WriteLine("Client connection closed.");
     }
 }


 // stop the server
 public static void StopServer()
 { 
     Console.WriteLine("Shutdown command received. Stopping the server...");
     isRunning = false;
 }

sorry - just realized the last few lines were missing that's trivial code, I mean it should be possible to read it in discord and make assumptions @sharwell , @333fred

333fred•3mo ago

Like Sam, I don't have much experience with sockets

sharwell•3mo ago

I won't be able to help with this as I'm not familiar with these APIs. I haven't done any network I/O in probably almost 10 years

stnOP•3mo ago

me neither just this

stnOP•3mo ago

it's absolutely trivial, I took the example from the Microsoft-page even for writing the client and the server https://learn.microsoft.com/en-us/dotnet/fundamentals/networking/sockets/tcp-classes

Use TcpClient and TcpListener - .NET

Learn how to use the TcpClient class to create a socket to request and receive data using TCP in .NET.

333fred•3mo ago

I would close this thread and start over; just use your sample code above, and then hopefully someone who can actually help you will

stnOP•3mo ago

so it was actually just a goto-quicker completed coding work?

333fred•3mo ago

This thread has too much cruft in it

stnOP•3mo ago

because nobody could appear on the stage and say :) hey I have an error,... using IO and a sourcegen, right? to be fair, it's a good choice, since it prevents people from spawning actual sourcefiles then just tell me how to correctly use the diagnostic?

333fred•3mo ago

Let us know when you've written a unit test 🙂

stnOP•2mo ago

actually I gave up on that project since then but it makes no sense for me to quickly hack something together and write a unit-test for ensuring it works correctly when I just want to try something out a Unit-Test,... that's what I write when I want to ensure it works forever so I see any issues in the CI So the answer was ... someone is running a Virtual Machine on my computer (and probably I am in a VM right now) - since after uninstalling the Hypervisor in Add/Remove Programs -> Windows Features -> []Hypervisor, reboot .... but doing /systeminfo still gives me 'A hypervisor has been detected.' closing/closed the post

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SocketException, TCPListener, TCPClient reason?