Procedura: utilizzare le named pipe per la comunicazione interprocesso in rete
Le named pipe forniscono la comunicazione interprocesso tra un server pipe e uno o più client pipe. Offrono maggiori funzionalità rispetto alle pipe anonime che forniscono la comunicazione interprocesso in un computer locale. Le named pipe supportano la comunicazione full duplex in una rete e in più istanze server, la comunicazione basata su messaggi e la rappresentazione client che consente ai processi di connessione di utilizzare il proprio set di autorizzazioni nei server remoti.
Importante
.NET in Linux usa socket di dominio Unix per l'implementazione di queste API.
Per implementare le named pipe, utilizzare le classi NamedPipeServerStream e NamedPipeClientStream.
Esempio 1
L'esempio seguente illustra come creare una named pipe usando la classe NamedPipeServerStream. In questo esempio il processo server crea quattro thread. Ogni thread può accettare una connessione client. Il processo client connesso fornisce quindi al server un nome file. Se il client ha autorizzazioni sufficienti, il processo server apre il file e invia il contenuto al client.
#using <System.Core.dll>
using namespace System;
using namespace System::IO;
using namespace System::IO::Pipes;
using namespace System::Text;
using namespace System::Threading;
// Defines the data protocol for reading and writing strings on our stream
public ref class StreamString
{
private:
Stream^ ioStream;
UnicodeEncoding^ streamEncoding;
public:
StreamString(Stream^ ioStream)
{
this->ioStream = ioStream;
streamEncoding = gcnew UnicodeEncoding();
}
String^ ReadString()
{
int len;
len = ioStream->ReadByte() * 256;
len += ioStream->ReadByte();
array<Byte>^ inBuffer = gcnew array<Byte>(len);
ioStream->Read(inBuffer, 0, len);
return streamEncoding->GetString(inBuffer);
}
int WriteString(String^ outString)
{
array<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 ref class ReadFileToStream
{
private:
String^ fn;
StreamString ^ss;
public:
ReadFileToStream(StreamString^ str, String^ filename)
{
fn = filename;
ss = str;
}
void Start()
{
String^ contents = File::ReadAllText(fn);
ss->WriteString(contents);
}
};
public ref class PipeServer
{
private:
static int numThreads = 4;
public:
static void Main()
{
int i;
array<Thread^>^ servers = gcnew array<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] = gcnew Thread(gcnew ThreadStart(&ServerThread));
servers[i]->Start();
}
Thread::Sleep(250);
while (i > 0)
{
for (int j = 0; j < numThreads; j++)
{
if (servers[j] != nullptr)
{
if (servers[j]->Join(250))
{
Console::WriteLine("Server thread[{0}] finished.", servers[j]->ManagedThreadId);
servers[j] = nullptr;
i--; // decrement the thread watch count
}
}
}
}
Console::WriteLine("\nServer threads exhausted, exiting.");
}
private:
static void ServerThread()
{
NamedPipeServerStream^ pipeServer =
gcnew NamedPipeServerStream("testpipe", PipeDirection::InOut, numThreads);
int threadId = 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.
StreamString^ ss = gcnew 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 = gcnew 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(gcnew PipeStreamImpersonationWorker(fileReader, &ReadFileToStream::Start));
}
// Catch the IOException that is raised if the pipe is broken
// or disconnected.
catch (IOException^ e)
{
Console::WriteLine("ERROR: {0}", e->Message);
}
pipeServer->Close();
}
};
int main()
{
PipeServer::Main();
}
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[{0}] finished.", servers[j]!.ManagedThreadId);
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[{0}].", 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: {0} on thread[{1}] as user: {2}.",
filename, threadId, 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: {0}", 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
Esempio 2
L'esempio seguente mostra il processo client, che usa la classe NamedPipeClientStream. Il client si connette al processo server e invia un nome file al server. L'esempio usa la rappresentazione, quindi l'identità che esegue l'applicazione client deve avere l'autorizzazione per accedere al file. Il server invia quindi il contenuto del file al client. Il contenuto del file viene quindi visualizzato nella console.
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
Programmazione efficiente
I processi client e server in questo esempio sono in esecuzione nello stesso computer, quindi il nome del server fornito all'oggetto NamedPipeClientStream è ".". Se i processi client e server fossero in computer distinti, "." verrebbe sostituito dal nome di rete del computer che esegue il processo server.
Vedi anche
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