.NET 3.5 Adds Named Pipes Support

Thank you for the great example of using managed named pipes with .net 3.5. However I have been runnin into an issue that i have not been able to find any help on. What i am trying to do is (in Vista) run a windows service that has a named piped server and an application that runs under limited permissions as a local user. When the local user app tries to connect to the server an error is thrown that 'Access to the path is denied'. If the app is running under an administrator account it works perfectly. I need my app to be able to communicate with the service. I know there are other possible solutions but i felt that named pipes would be the most secure. Please any help is appreciated.

Can someone tell me how to pass a string from the client and read it on the server? Thanks

Thank you!

Hello,

looks like i have the exact same problem. I hava a PipeServer running on one machine and a PipeClient on another. It is working fine as long as I am running both apps under the same account (Username/Passwort) But if I change the Clients User, I get the "Wrong Username or Password Error" when I try to connect the Client. I just have not figured out, how to pass Userinformations to the Pipe. I am not even sure if I have to set them on the Server or Client. Adding a PipeAccessRule had no effect on the Client Side. On the Server Side i got an Error, that the User i tried to add was unknown (logical, the User does not exist on the Server machine)

My Server: _PipeInServer = New NamedPipeServerStream(_PipeNameIn, PipeDirection.InOut)

My Client: _PipeOutClient = New NamedPipeClientStream(_ServerName, _PipeNameIn, PipeDirection.InOut)

You have any Idea? Thank you mike

Is there anyway to use this to transfer serializable objects through? also what about having multiple clients? the given example only works with 1:1.

when i send a string using the method above, the string is not received by the client untill i close the streamwriter...

I have two winform applications A and B. A has a text box and a button to send the text and B has a list box to collect the received string.

Now when i use the code below , the message is not received. However if i add a sw.Close() below the 'sw.WriteLine(....) function it is working only once. Next message throws a exception stating that pipe has been closed....

using (StreamWriter sw = new StreamWriter(pipeServer)) { sw.AutoFlush = true; Console.Write("Enter text: "); sw.WriteLine(Console.ReadLine()); }

Hi,

How do you do multiple NamedPipeClientStream Connection to One NamedPipeServerStream ?

The thing is, I'm developping a multi-Process application, with a MainProcessManaging Application that is monitoring the other Process States & Use. To communicate between them, and as they all are local Processes, I choose NamedPipes as the most optimized solution.

My problem today is that the MaxInstance parameter you can pass to the NamedPipeServerStream doesn't seem to do the work I was hoping for, that is accept multiple Client connection to my ServerStream.

Does anyone know how I can do the trick, or do I have to create for each of my processes a particular {Server,Client}Stream connection ?

Okay here is the example..It is not very robust such i'm not thread pools or AutoResetEvent etc..To Test them You should have 2 console apps. One for Server and One for Client.

[language] //IPC Server class Program { public const int MAX_CONNECTIONS = 5;

static void Main(string[] args) { Thread[] threads = new Thread[MAX_CONNECTIONS];

AutoResetEvent evt = new AutoResetEvent(true); for (int i=0;i static void StartServer() { Server svr = new Server(); svr.StartService();//will return when client //disconnects. } }

//Server.cs class Server:IDisposable { NamedPipeServerStream pipeServer = new NamedPipeServerStream("MessagingServer", PipeDirection.InOut, Program.MAX_CONNECTIONS);

public void StartService() { System.Console.WriteLine("Server Started");

pipeServer.WaitForConnection();

System.Console.WriteLine("Client Connected");

StreamWriter sw = new StreamWriter(pipeServer); StreamReader sr = new StreamReader(pipeServer); sw.AutoFlush = true; string sMsg = ""; try { while (sMsg != "bye") { sMsg = sr.ReadLine(); Console.WriteLine("Client Message: " + sMsg); sw.WriteLine("Server Echo " + sMsg); }

} catch (Exception ex) { System.Console.WriteLine("Communication Error " + ex.Message); } finally { pipeServer.Close(); }

}

#region IDisposable Members

void IDisposable.Dispose() { pipeServer.Close(); }

#endregion }

//Client.cs class Program { static void Main(string[] args) {

NamedPipeClientStream pipeClient = new NamedPipeClientStream(".", "MessagingServer", PipeDirection.InOut);

pipeClient.Connect();

System.IO.StreamWriter sw = new StreamWriter(pipeClient); System.IO.StreamReader sr = new StreamReader(pipeClient); sw.AutoFlush = true;//otherwise, writer will not write to the underlying stream intime. string sMsg = ""; Console.WriteLine(pipeClient.NumberOfServerInstances); try { while (sMsg != "Bye") { Console.WriteLine("Enter command for the Server"); sMsg = Console.ReadLine(); sw.WriteLine(sMsg); Console.WriteLine("Server Response: " + sr.ReadLine()); } } catch (Exception ex) { Console.WriteLine("Exception occurred: " + ex.Message);

}

finally { pipeClient.Close(); }

} } [/language]

I would like to restrict access to a named pipe, so that it can only be used within a Windows logon session (on the same machine).

In C++ I can use the logon SID on the DACL for the pipe but how can that be done in C#?

I realize that this is an old thread but I hope someone is still listening.

Regards, Brian

using a named pipe between a service and an application seems to give "Access denied" when client calls CallNamedPipe, ON WINDOWS 7 (was working fine on XP at least)

it seems that even if I set (in the service properties) the same logon account as the one where the client application is started, I have this error code 5 "Access Denied".

any idea ?? thx

Hello, I'm trying to write a thin shim in C# that exposes a single named pipe (only one client at a time) but that client is written in Win32 unmanaged C++. I'm starting to suspect that pipes created with the .NET 3.5 classes aren't visible to processes that don't contain a CLR in them? The reason I say this is the Win32 client doesn't ever find the pipe no matter how many different variations I decorate the name with (e.g. "PIPENAME", "\\PIPENAME", "\\\\.\\PIPENAME", etc.). When I fire up the Winternals SysObj utility, I can't find the pipe listed anywhere. What am I missing? Thank you.

I'm having a problem Where the first time I use the piping it works perfectly, but every subsequent message to the pipe will return an exception: IOException - Pipe is broken.I feel like I'm doing everything correctly so help would be GREATLY appreciated.

Summarized, my code looks like this:

PipeServer
-----------

// Done once
m_pipeServer = new NamedPipeServerStream(pipeName,                             PipeDirection.InOut,                                    1,                                                      PipeTransmissionMode.Message,                           PipeOptions.Asynchronous); // Have also tried PipeOptions.None

m_mySR = new StreamReader(m_pipeServer);
m_mySW = new StreamWriter(m_pipeServer);
int count = 0;

// In a loop
while (someCondition...) {
 try
 {                
     m_pipeServer.WaitForConnection();

     // *Don't* set AutoFlush until AFTER you've connected or you'll throw an exception and be sorry!
     m_mySW.AutoFlush = true;

     // Read the message sent to the pipe
     int peekInt = m_mySR.Peek();

     while (peekInt != -1)
     {
         msg = m_mySR.ReadLine();
         ProcessMessage(msg);

         peekInt = m_mySR.Peek();
     }

     m_mySW.WriteLine("Message received!" + count++);
}
// catch exceptions


PipeClient
------------

// Done once
m_pipeClient = new NamedPipeClientStream("localhost",
pipeName,                                         PipeDirection.InOut,                              PipeOptions.None,                            System.Security.Principal.TokenImpersonationLevel.Impersonation);

m_pipeClient.Connect(timeout);
m_mySR = new StreamReader(m_pipeClient);
m_mySW = new StreamWriter(m_pipeClient);
m_mySW.AutoFlush = true;

// Now, my test app has a button. When I click it, the client should send a message and display the response.
m_mySW.WriteLine(msg);
m_pipeClient.WaitForPipeDrain();

// Read response from server, if there is any.
int peekChar = m_mySR.Peek();
if (peekChar != -1)
{
     retString = m_mySR.ReadLine();

     Debug.WriteLine("Received from server: " + retString);                    
}

So, I expect to see "Received from server: 1", "Received from server: 2", "Received from server: 3"...

But the attempt to m_mySW.WriteLine(msg) fails because the pipe is broken (note: I *can* see that the pipe client is actually connected (IsConnected == true), so I don't know what the StreamWriter's problem is).

Tips & suggestions greatly appreciated!