C# Signature:
[DllImport("kernel32.dll", SetLastError = true)]
static extern IntPtr CreateNamedPipe(string lpName, uint dwOpenMode,
uint dwPipeMode, uint nMaxInstances, uint nOutBufferSize, uint nInBufferSize,
uint nDefaultTimeOut, IntPtr lpSecurityAttributes);
User-Defined Types:
[Flags]
public enum PipeOpenModeFlags : uint
{
PIPE_ACCESS_DUPLEX = 0x00000003,
PIPE_ACCESS_INBOUND = 0x00000001,
PIPE_ACCESS_OUTBOUND = 0x00000002,
FILE_FLAG_FIRST_PIPE_INSTANCE = 0x00080000,
FILE_FLAG_WRITE_THROUGH = 0x80000000,
FILE_FLAG_OVERLAPPED = 0x40000000,
WRITE_DAC = 0x00040000L,
WRITE_OWNER = 0x00080000L,
ACCESS_SYSTEM_SECURITY = 0x01000000L
}
[Flags]
public enum PipeModeFlags : uint
{
//One of the following type modes can be specified. The same type mode must be specified for each instance of the pipe.
PIPE_TYPE_BYTE = 0x00000000,
PIPE_TYPE_MESSAGE = 0x00000004,
//One of the following read modes can be specified. Different instances of the same pipe can specify different read modes
PIPE_READMODE_BYTE = 0x00000000,
PIPE_READMODE_MESSAGE = 0x00000002,
//One of the following wait modes can be specified. Different instances of the same pipe can specify different wait modes.
PIPE_WAIT = 0x00000000,
PIPE_NOWAIT = 0x00000001,
//One of the following remote-client modes can be specified. Different instances of the same pipe can specify different remote-client modes.
PIPE_ACCEPT_REMOTE_CLIENTS = 0x00000000,
PIPE_REJECT_REMOTE_CLIENTS = 0x00000008
}
Notes:
http://codemortem.blogspot.com/2006/01/creating-null-dacl-in-managed-code.html - Blog post on how to populate the SECURITY_ATTRIBUTES structure from managed code.
Tips & Tricks:
Please add some!
Sample Code:
/* A complete wrapper for named pipes (both client and server sides). Yes, its overkill for this p/invoke entry, but
where else should it be posted then? Les at ivsds dot com. */
using System;
using System.IO;
using System.Runtime.InteropServices;
using System.ComponentModel;
using System.Text;
namespace LibDcAgent
{
/// <summary>
/// NamedPipeStream is an odd little hybrid between the client and server ends of a NamedPipe,
/// and a System.IO.Stream subclass. Basically, it simplifies the unnecessarily horrific process
/// of implementing named pipe support in .Net. (If you doubt this, try it the hard way... we'll wait.)
///
/// Usage idiom:
///
/// Server side
/// -----------
/// 1. Call NamedPipeStream.Create, specify inbound, outbound, or both
/// 2. Call Listen(). This will block until a client connects. Sorry, the alternatives
/// are ugly. Use a thread.
/// 3. Call DataAvailable() in a loop with Read(), Write, ReadLine(), etc. until IsConnected turns false.
/// 4. Call Listen() again to wait for the next client.
///
/// Client side
/// -----------
/// 1. Call Open()
/// 2. Call DataAvailable(), Read(), Write(), etc. until you're done,
/// then call Close();
///
/// And yes, you can attach TextReader and TextWriter instances to this stream.
///
/// Server side caveat:
///
/// The idiom described above only supports a single client at a time. If you need
/// to support multiple clients, multiple calls to Create()/Listen() in separate threads is the
/// recommended approach.
///
/// There is a test driver class at the end of this file which can be cannibalized for sample usage code.
///
/// </summary>
public class NamedPipeStream : Stream
{
[DllImport("kernel32.dll", EntryPoint = "CreateFile", SetLastError = true)]
private static extern IntPtr CreateFile(String lpFileName,
UInt32 dwDesiredAccess, UInt32 dwShareMode,
IntPtr lpSecurityAttributes, UInt32 dwCreationDisposition,
UInt32 dwFlagsAndAttributes,
IntPtr hTemplateFile);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern IntPtr CreateNamedPipe(
String lpName, // pipe name
uint dwOpenMode, // pipe open mode
uint dwPipeMode, // pipe-specific modes
uint nMaxInstances, // maximum number of instances
uint nOutBufferSize, // output buffer size
uint nInBufferSize, // input buffer size
uint nDefaultTimeOut, // time-out interval
IntPtr pipeSecurityDescriptor // SD
);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool DisconnectNamedPipe(
IntPtr hHandle);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ConnectNamedPipe(
IntPtr hHandle, // handle to named pipe
IntPtr lpOverlapped // overlapped structure
);
[DllImport("kernel32.dll", EntryPoint = "PeekNamedPipe", SetLastError = true)]
private static extern bool PeekNamedPipe(IntPtr handle,
byte[] buffer, uint nBufferSize, ref uint bytesRead,
ref uint bytesAvail, ref uint BytesLeftThisMessage);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool ReadFile(IntPtr handle,
byte[] buffer, uint toRead, ref uint read, IntPtr lpOverLapped);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool WriteFile(IntPtr handle,
byte[] buffer, uint count, ref uint written, IntPtr lpOverlapped);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool CloseHandle(IntPtr handle);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool FlushFileBuffers(IntPtr handle);
/*[DllImport("kernel32.dll", SetLastError = true)]
private static extern uint GetLastError();*/
//Constants for dwDesiredAccess:
private const UInt32 GENERIC_READ = 0x80000000;
private const UInt32 GENERIC_WRITE = 0x40000000;
//Constants for return value:
private const Int32 INVALID_HANDLE_VALUE = -1;
//Constants for dwFlagsAndAttributes:
private const UInt32 FILE_FLAG_OVERLAPPED = 0x40000000;
private const UInt32 FILE_FLAG_NO_BUFFERING = 0x20000000;
//Constants for dwCreationDisposition:
private const UInt32 OPEN_EXISTING = 3;
#region Comments
/// <summary>
/// Outbound pipe access.
/// </summary>
#endregion
private const uint PIPE_ACCESS_OUTBOUND = 0x00000002;
#region Comments
/// <summary>
/// Duplex pipe access.
/// </summary>
#endregion
private const uint PIPE_ACCESS_DUPLEX = 0x00000003;
#region Comments
/// <summary>
/// Inbound pipe access.
/// </summary>
#endregion
private const uint PIPE_ACCESS_INBOUND = 0x00000001;
#region Comments
/// <summary>
/// Pipe blocking mode.
/// </summary>
#endregion
private const uint PIPE_WAIT = 0x00000000;
#region Comments
/// <summary>
/// Pipe non-blocking mode.
/// </summary>
#endregion
private const uint PIPE_NOWAIT = 0x00000001;
#region Comments
/// <summary>
/// Pipe read mode of type Byte.
/// </summary>
#endregion
private const uint PIPE_READMODE_BYTE = 0x00000000;
#region Comments
/// <summary>
/// Pipe read mode of type Message.
/// </summary>
#endregion
private const uint PIPE_READMODE_MESSAGE = 0x00000002;
#region Comments
/// <summary>
/// Byte pipe type.
/// </summary>
#endregion
private const uint PIPE_TYPE_BYTE = 0x00000000;
#region Comments
/// <summary>
/// Message pipe type.
/// </summary>
#endregion
private const uint PIPE_TYPE_MESSAGE = 0x00000004;
#region Comments
/// <summary>
/// Pipe client end.
/// </summary>
#endregion
private const uint PIPE_CLIENT_END = 0x00000000;
#region Comments
/// <summary>
/// Pipe server end.
/// </summary>
#endregion
private const uint PIPE_SERVER_END = 0x00000001;
#region Comments
/// <summary>
/// Unlimited server pipe instances.
/// </summary>
#endregion
private const uint PIPE_UNLIMITED_INSTANCES = 255;
#region Comments
/// <summary>
/// Waits indefinitely when connecting to a pipe.
/// </summary>
#endregion
private const uint NMPWAIT_WAIT_FOREVER = 0xffffffff;
#region Comments
/// <summary>
/// Does not wait for the named pipe.
/// </summary>
#endregion
private const uint NMPWAIT_NOWAIT = 0x00000001;
#region Comments
/// <summary>
/// Uses the default time-out specified in a call to the CreateNamedPipe method.
/// </summary>
#endregion
private const uint NMPWAIT_USE_DEFAULT_WAIT = 0x00000000;
private const ulong ERROR_PIPE_CONNECTED = 535;
/// <summary>
/// Server side creation option:
/// </summary>
public enum ServerMode
{
InboundOnly = (int)PIPE_ACCESS_INBOUND,
OutboundOnly = (int)PIPE_ACCESS_OUTBOUND,
Bidirectional = (int)(PIPE_ACCESS_INBOUND+PIPE_ACCESS_OUTBOUND)
};
public enum PeerType
{
Client = 0,
Server = 1
};
IntPtr _handle;
FileAccess _mode;
PeerType _peerType;
protected NamedPipeStream()
{
_handle = IntPtr.Zero;
_mode = (FileAccess)0;
_peerType = PeerType.Server;
}
public NamedPipeStream(string pipename, FileAccess mode)
{
_handle = IntPtr.Zero;
_peerType = PeerType.Client;
Open(pipename, mode);
}
public NamedPipeStream(IntPtr handle, FileAccess mode)
{
_handle = handle;
_mode = mode;
_peerType = PeerType.Client;
}
/// <summary>
/// Opens the client side of a pipe.
/// </summary>
/// <param name="pipe">Full path to the pipe, e.g. '\\.\pipe\mypipe'</param>
/// <param name="mode">Read,Write, or ReadWrite - must be compatible with server-side creation mode</param>
public void Open(string pipename, FileAccess mode)
{
uint pipemode = 0;
if ((mode & FileAccess.Read) > 0)
pipemode |= GENERIC_READ;
if ((mode & FileAccess.Write) > 0)
pipemode |= GENERIC_WRITE;
IntPtr handle = CreateFile(pipename, pipemode,
0, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero);
if (handle.ToInt32() == INVALID_HANDLE_VALUE)
{
int err = Marshal.GetLastWin32Error();
throw new Win32Exception(err,
string.Format("NamedPipeStream.Open failed, win32 error code {0}, pipename '{1}' ",err,pipename));
}
_mode = mode;
_handle = handle;
}
/// <summary>
/// Create a named pipe instance.
/// </summary>
/// <param name="pipeName">Local name (the part after \\.\pipe\)</param>
public static NamedPipeStream Create(string pipeName, ServerMode mode)
{
IntPtr handle = IntPtr.Zero;
string name = @"\\.\pipe\" + pipeName;
handle = CreateNamedPipe(
name,
(uint)mode,
PIPE_TYPE_BYTE | PIPE_WAIT,
PIPE_UNLIMITED_INSTANCES,
0, // outBuffer,
1024, // inBuffer,
NMPWAIT_WAIT_FOREVER,
IntPtr.Zero);
if (handle.ToInt32() == INVALID_HANDLE_VALUE)
{
throw new Win32Exception("Error creating named pipe " + name + " . Internal error: " + Marshal.GetLastWin32Error().ToString());
}
// Set members persistently...
NamedPipeStream self = new NamedPipeStream();
self._handle = handle;
switch (mode)
{
case ServerMode.InboundOnly:
self._mode = FileAccess.Read;
break;
case ServerMode.OutboundOnly:
self._mode = FileAccess.Write;
break;
case ServerMode.Bidirectional:
self._mode = FileAccess.ReadWrite;
break;
}
return self;
}
/// <summary>
/// Server only: block until client connects
/// </summary>
/// <returns></returns>
public bool Listen()
{
if (_peerType != PeerType.Server)
throw new Exception("Listen() is only for server-side streams");
DisconnectNamedPipe(_handle);
if (ConnectNamedPipe(_handle, IntPtr.Zero) != true)
{
uint lastErr = (uint)Marshal.GetLastWin32Error();
if (lastErr == ERROR_PIPE_CONNECTED)
return true;
return false;
}
return true;
}
/// <summary>
/// Server only: disconnect the pipe. For most applications, you should just call Listen()
/// instead, which automatically does a disconnect of any old connection.
/// </summary>
public void Disconnect()
{
if (_peerType != PeerType.Server)
throw new Exception("Disconnect() is only for server-side streams");
DisconnectNamedPipe(_handle);
}
/// <summary>
/// Returns true if client is connected. Should only be called after Listen() succeeds.
/// </summary>
/// <returns></returns>
public bool IsConnected
{
get
{
if (_peerType != PeerType.Server)
throw new Exception("IsConnected() is only for server-side streams");
if (ConnectNamedPipe(_handle, IntPtr.Zero) == false)
{
if ((uint)Marshal.GetLastWin32Error() == ERROR_PIPE_CONNECTED)
return true;
}
return false;
}
}
public bool DataAvailable
{
get
{
uint bytesRead = 0, avail = 0, thismsg = 0;
bool result = PeekNamedPipe(_handle,
null, 0, ref bytesRead, ref avail, ref thismsg);
return (result == true && avail > 0);
}
}
public override bool CanRead
{
get { return (_mode & FileAccess.Read) > 0; }
}
public override bool CanWrite
{
get { return (_mode & FileAccess.Write) > 0; }
}
public override bool CanSeek
{
get { return false; }
}
public override long Length
{
get { throw new NotSupportedException("NamedPipeStream does not support seeking"); }
}
public override long Position
{
get { throw new NotSupportedException("NamedPipeStream does not support seeking"); }
set { }
}
public override void Flush()
{
if (_handle == IntPtr.Zero)
throw new ObjectDisposedException("NamedPipeStream", "The stream has already been closed");
FlushFileBuffers(_handle);
}
public override int Read(byte[] buffer, int offset, int count)
{
if (buffer == null)
throw new ArgumentNullException("buffer", "The buffer to read into cannot be null");
if (buffer.Length < (offset + count))
throw new ArgumentException("Buffer is not large enough to hold requested data", "buffer");
if (offset < 0)
throw new ArgumentOutOfRangeException("offset", offset, "Offset cannot be negative");
if (count < 0)
throw new ArgumentOutOfRangeException("count", count, "Count cannot be negative");
if (!CanRead)
throw new NotSupportedException("The stream does not support reading");
if (_handle == IntPtr.Zero)
throw new ObjectDisposedException("NamedPipeStream", "The stream has already been closed");
// first read the data into an internal buffer since ReadFile cannot read into a buf at
// a specified offset
uint read = 0;
byte[] buf = buffer;
if (offset != 0)
{
buf = new byte[count];
}
bool f = ReadFile(_handle, buf, (uint)count, ref read, IntPtr.Zero);
if (!f)
{
throw new Win32Exception(Marshal.GetLastWin32Error(), "ReadFile failed");
}
if (offset != 0)
{
for (int x = 0; x < read; x++)
{
buffer[offset + x] = buf[x];
}
}
return (int)read;
}
public override void Close()
{
CloseHandle(_handle);
_handle = IntPtr.Zero;
}
public override void SetLength(long length)
{
throw new NotSupportedException("NamedPipeStream doesn't support SetLength");
}
public override void Write(byte[] buffer, int offset, int count)
{
if (buffer == null)
throw new ArgumentNullException("buffer", "The buffer to write into cannot be null");
if (buffer.Length < (offset + count))
throw new ArgumentException("Buffer does not contain amount of requested data", "buffer");
if (offset < 0)
throw new ArgumentOutOfRangeException("offset", offset, "Offset cannot be negative");
if (count < 0)
throw new ArgumentOutOfRangeException("count", count, "Count cannot be negative");
if (!CanWrite)
throw new NotSupportedException("The stream does not support writing");
if (_handle == IntPtr.Zero)
throw new ObjectDisposedException("NamedPipeStream", "The stream has already been closed");
// copy data to internal buffer to allow writing from a specified offset
if (offset != 0)
{
byte[] buf = new Byte[count];
for (int x = 0; x < count; x++)
{
buf[x] = buffer[offset + x];
}
buffer = buf;
}
uint written = 0;
bool result = WriteFile(_handle, buffer, (uint)count, ref written, IntPtr.Zero);
if (!result)
{
int err = (int)Marshal.GetLastWin32Error();
throw new Win32Exception(err,"Writing to the stream failed");
}
if (written < count)
throw new IOException("Unable to write entire buffer to stream");
}
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException("NamedPipeStream doesn't support seeking");
}
}
public class NamedPipeTest
{
/// <summary>
/// Test / demo code:
/// </summary>
/// <param name="args"></param>
public static void Main(string[] args)
{
if (args.Length == 0)
{
/*
* Server-side sample code:
*/
NamedPipeStream stream = NamedPipeStream.Create("testpipe", NamedPipeStream.ServerMode.Bidirectional);
StreamReader sr = new StreamReader(stream,Encoding.Unicode);
Console.WriteLine("Listening...");
do
{
stream.Listen();
do
{
bool dataRead = false;
while (stream.DataAvailable)
{
try
{
string s = sr.ReadLine();
if (s != null && s.Length > 0)
{
StreamWriter sw = new StreamWriter(stream, Encoding.Unicode);
sw.WriteLine(s);
sw.Flush();
Console.WriteLine(s);
dataRead = true;
}
}
catch { }
}
System.Threading.Thread.Sleep(dataRead ? 50 : 1000);
} while (stream.IsConnected);
} while (true);
}
else
{
/*
// Client side sample code:
*/
NamedPipeStream stream = new NamedPipeStream(@"\\.\pipe\testpipe", FileAccess.ReadWrite);
StreamWriter sw = new StreamWriter(stream, Encoding.Unicode);
sw.AutoFlush = true;
for (int i = 0; i < 500; i++)
{
sw.WriteLine("Hello world {0}", i);
System.Threading.Thread.Sleep(1000);
if (stream.DataAvailable)
{
StreamReader sr = new StreamReader(stream);
Console.WriteLine(sr.ReadLine());
}
}
sw.Write("Final line");
sw.Close();
}
}
}
}
Alternative Managed API:
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