Named pipe client (c++) with c# server

Question

What I want to do is have a named pipe client written in c++ to be able to communicate with a named pipe server written in C#. I have been unable to accomplish this so far.

CreateFile gives me an invalid handle value, GetLastError returns 2.

Here is the c++ part (client)

#include "stdafx.h"
#include <windows.h> 
#include <stdio.h>
#include <conio.h>
#include <tchar.h>
#include <iostream>

using namespace std;

#define PIPE_NAME L"\\\\.\\pipe\\TestPipe"
#define BUFF_SIZE 512

int main()
{
    HANDLE hPipe;

    hPipe = CreateFile(PIPE_NAME, GENERIC_READ, 0, nullptr, OPEN_EXISTING, 0, nullptr);

    if (hPipe == INVALID_HANDLE_VALUE)
    {
        cout << "INVALID_HANDLE_VALUE" << GetLastError() << endl;
        cin.get();
        return -1;
    }

    cout << hPipe << endl;

    DWORD mode = PIPE_READMODE_MESSAGE;

    SetNamedPipeHandleState(hPipe, &mode, nullptr, nullptr);

    bool success = false;
    DWORD read;

    while(true)
    {
        TCHAR chBuff[BUFF_SIZE];
        do
        {
            success = ReadFile(hPipe, chBuff, BUFF_SIZE*sizeof(TCHAR), &read, nullptr);
        } while (!success);

        _tprintf(TEXT("\"%s\"\n"), chBuff);
    }
}

And here is the server

using System;
using System.IO.Pipes;
using System.Text;

namespace BasicServer
{

    public static class Program
    {
        private static NamedPipeServerStream _server;

        static void Main(string[] args)
        {
            _server = new NamedPipeServerStream(@"\\.\pipe\TestPipe", PipeDirection.Out, 1, PipeTransmissionMode.Message);
            _server.WaitForConnection();
            Console.WriteLine(_server.IsConnected);
            Console.WriteLine("Client connected\n Sending message");
            byte[] buff = Encoding.UTF8.GetBytes("Test message");
            _server.Write(buff, 0, buff.Length);
            while (true)
            {
                Console.ReadKey();
                Console.Write("\b \b");
            }
        }
    }
}

I have been able to connect with a client written in C# but the c++ -> C# communication should be possible as far as I know.

Here was my test client I wrote in c#, which works

using System;
using System.IO.Pipes;
using System.Text;

namespace BasicClientC
{

    public class Program
    {
        private static NamedPipeClientStream client;

        static void Main(string[] args)
        {
            client = new NamedPipeClientStream(@".", @"\\.\pipe\TestPipe", PipeDirection.In);
            client.Connect();
            byte[] buffer = new byte[512];
            client.Read(buffer, 0, 512);
            Console.WriteLine(Encoding.UTF8.GetString(buffer));
            Console.ReadKey();
        }
    }
}

So where is my mistake?

Answer 1

I know why.

1. When creating your pipe in C#, use just "TestPipe" as the name of the pipe, don't include \\\\.\\pipe\\ as a prefix for this pipe's name.

2. From C++, use the full path to the pipe: "\\\\.\\pipe\\TestPipe" . Your C++ logic doesn't need a change for this, as you have defined it just fine: L"\\\\\\\\.\\\\pipe\\\\TestPipe"

This may help, as well . Funny enough, I ran into this three years ago or more, and now its all coming back to me.