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Anleitung: Verwenden von benannten Pipes für die Netzwerkkommunikation zwischen Prozessen

Benannte Rohre ermöglichen die Interprocess-Kommunikation zwischen einem Pipeserver und einem oder mehreren Pipeclients. Sie bieten mehr Funktionalität als anonyme Rohre, die die Interprocess-Kommunikation auf einem lokalen Computer ermöglichen. Named pipes unterstützen die vollständige Duplexkommunikation über ein Netzwerk und mehrere Serverinstanzen, die nachrichtenbasierte Kommunikation und den Identitätswechsel des Clients, wodurch Verbindungen mit Prozessen hergestellt werden können, die eigene Berechtigungssätze auf Remoteservern verwenden können.

Von Bedeutung

.NET unter Linux verwendet Unix Domain Sockets (UDS) für die Implementierung dieser APIs.

Verwenden Sie die Klassen NamedPipeServerStream und NamedPipeClientStream, um Namenspipes zu implementieren.

Beispiel 1

Im folgenden Beispiel wird das Erstellen einer benannten Pipe mithilfe der NamedPipeServerStream Klasse veranschaulicht. In diesem Beispiel erstellt der Serverprozess vier Threads. Jeder Thread kann eine Clientverbindung akzeptieren. Der verbundene Clientprozess übermittelt dem Server dann einen Dateinamen. Wenn der Client über ausreichende Berechtigungen verfügt, öffnet der Serverprozess die Datei und sendet den Inhalt an den Client zurück.

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

public class PipeServer
{
    private static int numThreads = 4;

    public static void Main()
    {
        int i;
        Thread?[] servers = new Thread[numThreads];

        Console.WriteLine("\n*** Named pipe server stream with impersonation example ***\n");
        Console.WriteLine("Waiting for client connect...\n");
        for (i = 0; i < numThreads; i++)
        {
            servers[i] = new Thread(ServerThread);
            servers[i]?.Start();
        }
        Thread.Sleep(250);
        while (i > 0)
        {
            for (int j = 0; j < numThreads; j++)
            {
                if (servers[j] != null)
                {
                    if (servers[j]!.Join(250))
                    {
                        Console.WriteLine($"Server thread[{servers[j]!.ManagedThreadId}] finished.");
                        servers[j] = null;
                        i--;    // decrement the thread watch count
                    }
                }
            }
        }
        Console.WriteLine("\nServer threads exhausted, exiting.");
    }

    private static void ServerThread(object? data)
    {
        NamedPipeServerStream pipeServer =
            new NamedPipeServerStream("testpipe", PipeDirection.InOut, numThreads);

        int threadId = Thread.CurrentThread.ManagedThreadId;

        // Wait for a client to connect
        pipeServer.WaitForConnection();

        Console.WriteLine($"Client connected on thread[{threadId}].");
        try
        {
            // Read the request from the client. Once the client has
            // written to the pipe its security token will be available.

            StreamString ss = new StreamString(pipeServer);

            // Verify our identity to the connected client using a
            // string that the client anticipates.

            ss.WriteString("I am the one true server!");
            string filename = ss.ReadString();

            // Read in the contents of the file while impersonating the client.
            ReadFileToStream fileReader = new ReadFileToStream(ss, filename);

            // Display the name of the user we are impersonating.
            Console.WriteLine($"Reading file: {filename} on thread[{threadId}] as user: {pipeServer.GetImpersonationUserName()}.");
            pipeServer.RunAsClient(fileReader.Start);
        }
        // Catch the IOException that is raised if the pipe is broken
        // or disconnected.
        catch (IOException e)
        {
            Console.WriteLine($"ERROR: {e.Message}");
        }
        pipeServer.Close();
    }
}

// Defines the data protocol for reading and writing strings on our stream
public class StreamString
{
    private Stream ioStream;
    private UnicodeEncoding streamEncoding;

    public StreamString(Stream ioStream)
    {
        this.ioStream = ioStream;
        streamEncoding = new UnicodeEncoding();
    }

    public string ReadString()
    {
        int len = 0;

        len = ioStream.ReadByte() * 256;
        len += ioStream.ReadByte();
        byte[] inBuffer = new byte[len];
        ioStream.Read(inBuffer, 0, len);

        return streamEncoding.GetString(inBuffer);
    }

    public int WriteString(string outString)
    {
        byte[] outBuffer = streamEncoding.GetBytes(outString);
        int len = outBuffer.Length;
        if (len > UInt16.MaxValue)
        {
            len = (int)UInt16.MaxValue;
        }
        ioStream.WriteByte((byte)(len / 256));
        ioStream.WriteByte((byte)(len & 255));
        ioStream.Write(outBuffer, 0, len);
        ioStream.Flush();

        return outBuffer.Length + 2;
    }
}

// Contains the method executed in the context of the impersonated user
public class ReadFileToStream
{
    private string fn;
    private StreamString ss;

    public ReadFileToStream(StreamString str, string filename)
    {
        fn = filename;
        ss = str;
    }

    public void Start()
    {
        string contents = File.ReadAllText(fn);
        ss.WriteString(contents);
    }
}

Imports System.IO
Imports System.IO.Pipes
Imports System.Text
Imports System.Threading

Public Class PipeServer
    Private Shared numThreads As Integer = 4

    Public Shared Sub Main()
        Dim i As Integer
        Dim servers(numThreads) As Thread

        Console.WriteLine(vbCrLf + "*** Named pipe server stream with impersonation example ***" + vbCrLf)
        Console.WriteLine("Waiting for client connect..." + vbCrLf)
        For i = 0 To numThreads - 1
            servers(i) = New Thread(AddressOf ServerThread)
            servers(i).Start()
        Next i
        Thread.Sleep(250)
        While i > 0
            For j As Integer = 0 To numThreads - 1
                If Not (servers(j) Is Nothing) Then
                    If servers(j).Join(250) Then
                        Console.WriteLine("Server thread[{0}] finished.", servers(j).ManagedThreadId)
                        servers(j) = Nothing
                        i -= 1    ' decrement the thread watch count
                    End If
                End If
            Next j
        End While
        Console.WriteLine(vbCrLf + "Server threads exhausted, exiting.")
    End Sub

    Private Shared Sub ServerThread(data As Object)
        Dim pipeServer As New _
            NamedPipeServerStream("testpipe", PipeDirection.InOut, numThreads)

        Dim threadId As Integer = Thread.CurrentThread.ManagedThreadId

        ' Wait for a client to connect
        pipeServer.WaitForConnection()

        Console.WriteLine("Client connected on thread[{0}].", threadId)
        Try
            ' Read the request from the client. Once the client has
            ' written to the pipe its security token will be available.

            Dim ss As new StreamString(pipeServer)

            ' Verify our identity to the connected client using a
            ' string that the client anticipates.

            ss.WriteString("I am the one true server!")
            Dim filename As String = ss.ReadString()

            ' Read in the contents of the file while impersonating the client.
            Dim fileReader As New ReadFileToStream(ss, filename)

            ' Display the name of the user we are impersonating.
            Console.WriteLine("Reading file: {0} on thread[{1}] as user: {2}.",
                filename, threadId, pipeServer.GetImpersonationUserName())
            pipeServer.RunAsClient(AddressOf fileReader.Start)
            ' Catch the IOException that is raised if the pipe is broken
            ' or disconnected.
        Catch e As IOException
            Console.WriteLine("ERROR: {0}", e.Message)
        End Try
        pipeServer.Close()
    End Sub
End Class

' Defines the data protocol for reading and writing strings on our stream
Public Class StreamString
    Private ioStream As Stream
    Private streamEncoding As UnicodeEncoding

    Public Sub New(ioStream As Stream)
        Me.ioStream = ioStream
        streamEncoding = New UnicodeEncoding(False, False)
    End Sub

    Public Function ReadString() As String
        Dim len As Integer = 0
        len = CType(ioStream.ReadByte(), Integer) * 256
        len += CType(ioStream.ReadByte(), Integer)
        Dim inBuffer As Array = Array.CreateInstance(GetType(Byte), len)
        ioStream.Read(inBuffer, 0, len)

        Return streamEncoding.GetString(CType(inBuffer, Byte()))
    End Function

    Public Function WriteString(outString As String) As Integer
        Dim outBuffer() As Byte = streamEncoding.GetBytes(outString)
        Dim len As Integer = outBuffer.Length
        If len > UInt16.MaxValue Then
            len = CType(UInt16.MaxValue, Integer)
        End If
        ioStream.WriteByte(CType(len \ 256, Byte))
        ioStream.WriteByte(CType(len And 255, Byte))
        ioStream.Write(outBuffer, 0, outBuffer.Length)
        ioStream.Flush()

        Return outBuffer.Length + 2
    End Function
End Class

' Contains the method executed in the context of the impersonated user
Public Class ReadFileToStream
    Private fn As String
    Private ss As StreamString

    Public Sub New(str As StreamString, filename As String)
        fn = filename
        ss = str
    End Sub

    Public Sub Start()
        Dim contents As String = File.ReadAllText(fn)
        ss.WriteString(contents)
    End Sub
End Class

Beispiel 2

Das folgende Beispiel zeigt den Clientprozess, der die NamedPipeClientStream Klasse verwendet. Der Client stellt eine Verbindung mit dem Serverprozess und sendet einen Dateinamen an den Server. Im Beispiel wird der Identitätswechsel verwendet, daher muss die Identität, unter der die Clientanwendung läuft, über die Berechtigung zum Zugriff auf die Datei verfügen. Der Server sendet dann den Inhalt der Datei zurück an den Client. Die Dateiinhalte werden dann in der Konsole angezeigt.

using System;
using System.Diagnostics;
using System.IO;
using System.IO.Pipes;
using System.Security.Principal;
using System.Text;
using System.Threading;

public class PipeClient
{
    private static int numClients = 4;

    public static void Main(string[] args)
    {
        if (args.Length > 0)
        {
            if (args[0] == "spawnclient")
            {
                var pipeClient =
                    new NamedPipeClientStream(".", "testpipe",
                        PipeDirection.InOut, PipeOptions.None,
                        TokenImpersonationLevel.Impersonation);

                Console.WriteLine("Connecting to server...\n");
                pipeClient.Connect();

                var ss = new StreamString(pipeClient);
                // Validate the server's signature string.
                if (ss.ReadString() == "I am the one true server!")
                {
                    // The client security token is sent with the first write.
                    // Send the name of the file whose contents are returned
                    // by the server.
                    ss.WriteString("c:\\textfile.txt");

                    // Print the file to the screen.
                    Console.Write(ss.ReadString());
                }
                else
                {
                    Console.WriteLine("Server could not be verified.");
                }
                pipeClient.Close();
                // Give the client process some time to display results before exiting.
                Thread.Sleep(4000);
            }
        }
        else
        {
            Console.WriteLine("\n*** Named pipe client stream with impersonation example ***\n");
            StartClients();
        }
    }

    // Helper function to create pipe client processes
    private static void StartClients()
    {
        string currentProcessName = Environment.CommandLine;

        // Remove extra characters when launched from Visual Studio
        currentProcessName = currentProcessName.Trim('"', ' ');

        currentProcessName = Path.ChangeExtension(currentProcessName, ".exe");
        Process?[] plist = new Process?[numClients];

        Console.WriteLine("Spawning client processes...\n");

        if (currentProcessName.Contains(Environment.CurrentDirectory))
        {
            currentProcessName = currentProcessName.Replace(Environment.CurrentDirectory, String.Empty);
        }

        // Remove extra characters when launched from Visual Studio
        currentProcessName = currentProcessName.Replace("\\", String.Empty);
        currentProcessName = currentProcessName.Replace("\"", String.Empty);

        int i;
        for (i = 0; i < numClients; i++)
        {
            // Start 'this' program but spawn a named pipe client.
            plist[i] = Process.Start(currentProcessName, "spawnclient");
        }
        while (i > 0)
        {
            for (int j = 0; j < numClients; j++)
            {
                if (plist[j] != null)
                {
                    if (plist[j]!.HasExited)
                    {
                        Console.WriteLine($"Client process[{plist[j]?.Id}] has exited.");
                        plist[j] = null;
                        i--;    // decrement the process watch count
                    }
                    else
                    {
                        Thread.Sleep(250);
                    }
                }
            }
        }
        Console.WriteLine("\nClient processes finished, exiting.");
    }
}

// Defines the data protocol for reading and writing strings on our stream.
public class StreamString
{
    private Stream ioStream;
    private UnicodeEncoding streamEncoding;

    public StreamString(Stream ioStream)
    {
        this.ioStream = ioStream;
        streamEncoding = new UnicodeEncoding();
    }

    public string ReadString()
    {
        int len;
        len = ioStream.ReadByte() * 256;
        len += ioStream.ReadByte();
        var inBuffer = new byte[len];
        ioStream.Read(inBuffer, 0, len);

        return streamEncoding.GetString(inBuffer);
    }

    public int WriteString(string outString)
    {
        byte[] outBuffer = streamEncoding.GetBytes(outString);
        int len = outBuffer.Length;
        if (len > UInt16.MaxValue)
        {
            len = (int)UInt16.MaxValue;
        }
        ioStream.WriteByte((byte)(len / 256));
        ioStream.WriteByte((byte)(len & 255));
        ioStream.Write(outBuffer, 0, len);
        ioStream.Flush();

        return outBuffer.Length + 2;
    }
}

Imports System.Diagnostics
Imports System.IO
Imports System.IO.Pipes
Imports System.Security.Principal
Imports System.Text
Imports System.Threading

Public Class PipeClient
    Private Shared numClients As Integer = 4

    Public Shared Sub Main(args() As String)
        If args.Length > 0 Then
            If args(0) = "spawnclient" Then
                Dim pipeClient As New NamedPipeClientStream( _
                    ".", "testpipe", _
                    PipeDirection.InOut, PipeOptions.None, _
                    TokenImpersonationLevel.Impersonation)

                Console.WriteLine("Connecting to server..." + vbCrLf)
                pipeClient.Connect()

                Dim ss As New StreamString(pipeClient)
                ' Validate the server's signature string.
                If ss.ReadString() = "I am the one true server!" Then
                    ' The client security token is sent with the first write.
                    ' Send the name of the file whose contents are returned
                    ' by the server.
                    ss.WriteString("c:\textfile.txt")

                    ' Print the file to the screen.
                    Console.Write(ss.ReadString())
                Else
                    Console.WriteLine("Server could not be verified.")
                End If
                pipeClient.Close()
                ' Give the client process some time to display results before exiting.
                Thread.Sleep(4000)
            End If
        Else
            Console.WriteLine(vbCrLf + "*** Named pipe client stream with impersonation example ***" + vbCrLf)
            StartClients()
        End If
    End Sub

    ' Helper function to create pipe client processes
    Private Shared Sub StartClients()
        Dim currentProcessName As String = Environment.CommandLine
        Dim plist(numClients - 1) As Process

        Console.WriteLine("Spawning client processes..." + vbCrLf)

        If currentProcessName.Contains(Environment.CurrentDirectory) Then
            currentProcessName = currentProcessName.Replace(Environment.CurrentDirectory, String.Empty)
        End If

        ' Remove extra characters when launched from Visual Studio.
        currentProcessName = currentProcessName.Replace("\", String.Empty)
        currentProcessName = currentProcessName.Replace("""", String.Empty)

        ' Change extension for .NET Core "dotnet run" returns the DLL, not the host exe.
        currentProcessName = Path.ChangeExtension(currentProcessName, ".exe")

        Dim i As Integer
        For i = 0 To numClients - 1
            ' Start 'this' program but spawn a named pipe client.
            plist(i) = Process.Start(currentProcessName, "spawnclient")
        Next
        While i > 0
            For j As Integer = 0 To numClients - 1
                If plist(j) IsNot Nothing Then
                    If plist(j).HasExited Then
                        Console.WriteLine($"Client process[{plist(j).Id}] has exited.")
                        plist(j) = Nothing
                        i -= 1    ' decrement the process watch count
                    Else
                        Thread.Sleep(250)
                    End If
                End If
            Next
        End While
        Console.WriteLine(vbCrLf + "Client processes finished, exiting.")
    End Sub
End Class

' Defines the data protocol for reading and writing strings on our stream
Public Class StreamString
    Private ioStream As Stream
    Private streamEncoding As UnicodeEncoding

    Public Sub New(ioStream As Stream)
        Me.ioStream = ioStream
        streamEncoding = New UnicodeEncoding(False, False)
    End Sub

    Public Function ReadString() As String
        Dim len As Integer = 0
        len = CType(ioStream.ReadByte(), Integer) * 256
        len += CType(ioStream.ReadByte(), Integer)
        Dim inBuffer As Array = Array.CreateInstance(GetType(Byte), len)
        ioStream.Read(inBuffer, 0, len)

        Return streamEncoding.GetString(CType(inBuffer, Byte()))
    End Function

    Public Function WriteString(outString As String) As Integer
        Dim outBuffer As Byte() = streamEncoding.GetBytes(outString)
        Dim len As Integer = outBuffer.Length
        If len > UInt16.MaxValue Then
            len = CType(UInt16.MaxValue, Integer)
        End If
        ioStream.WriteByte(CType(len \ 256, Byte))
        ioStream.WriteByte(CType(len And 255, Byte))
        ioStream.Write(outBuffer, 0, outBuffer.Length)
        ioStream.Flush()

        Return outBuffer.Length + 2
    End Function
End Class

Robuste Programmierung

Die Client- und Serverprozesse in diesem Beispiel sollen auf demselben Computer ausgeführt werden, sodass der servername, der für das NamedPipeClientStream Objekt bereitgestellt wird ".". Wenn sich die Client- und Serverprozesse auf separaten Computern befinden, "." würde durch den Netzwerknamen des Computers ersetzt, auf dem der Serverprozess ausgeführt wird.

Siehe auch