/// <summary>
/// Disconnects a server named pipe from the client.
/// </summary>
/// <remarks>
/// Server pipes can be reused by first disconnecting them from the client and then
/// calling the <see cref="AppModule.NamedPipes.NamedPipeWrapper.Connect">Connect</see>
/// method to start listening. This improves the performance as it is not necessary
/// to create new pipe handles.
/// </remarks>
/// <param name="handle">The pipe handle.</param>
#endregion
public static void Disconnect(PipeHandle handle)
{
handle.State = InterProcessConnectionState.Disconnecting;
NamedPipeNative.DisconnectNamedPipe(handle.Handle);
handle.State = InterProcessConnectionState.Disconnected;
}
/// <summary>
/// Reads the bytes from a named pipe.
/// </summary>
/// <param name="handle">The pipe handle.</param>
/// <param name="maxBytes">The maximum bytes to read.</param>
/// <returns>An array of bytes.</returns>
/// <remarks>This method expects that the first four bytes in the pipe define
/// the length of the data to read. If the data length is greater than
/// <b>maxBytes</b> the method returns null.<br/><br/>
/// The first four bytes of the pipe data are expected to contain
/// the data length of the message. This method first reads those four
/// bytes and converts them to integer. It then continues to read from the pipe using
/// the extracted data length.
/// </remarks>
#endregion
public static byte[] ReadBytes(PipeHandle handle, int maxBytes)
{
byte[] numReadWritten = new byte[4];
byte[] intBytes = new byte[4];
byte[] msgBytes = null;
int len;
// Set the Handle state to Reading
handle.State = InterProcessConnectionState.Reading;
// Read the first four bytes and convert them to integer
if (NamedPipeNative.ReadFile(handle.Handle, intBytes, 4, numReadWritten, 0))
{
len = BitConverter.ToInt32(intBytes, 0);
msgBytes = new byte[len];
// Read the rest of the data
if (!NamedPipeNative.ReadFile(handle.Handle, msgBytes, (uint)len, numReadWritten, 0))
{
handle.State = InterProcessConnectionState.Error;
throw new NamedPipeIOException("Error reading from pipe. Internal error: " + NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
else
{
handle.State = InterProcessConnectionState.Error;
throw new NamedPipeIOException("Error reading from pipe. Internal error: " + NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
handle.State = InterProcessConnectionState.ReadData;
if (len > maxBytes)
{
return(null);
}
return(msgBytes);
}
/// <summary>
/// Returns the number of instances of a named pipe.
/// </summary>
/// <param name="handle">The pipe handle.</param>
/// <returns>The number of instances.</returns>
#endregion
public static uint NumberPipeInstances(PipeHandle handle)
{
uint curInstances = 0;
if (NamedPipeNative.GetNamedPipeHandleState(handle.Handle, IntPtr.Zero, ref curInstances,
IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero))
{
return(curInstances);
}
else
{
throw new NamedPipeIOException("Error getting the pipe state. Internal error: " +
NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
/// <summary>
/// Flushes all the data in a named pipe.
/// </summary>
/// <param name="handle">The pipe handle.</param>
#endregion
public static void Flush(PipeHandle handle)
{
handle.State = InterProcessConnectionState.Flushing;
NamedPipeNative.FlushFileBuffers(handle.Handle);
handle.State = InterProcessConnectionState.FlushedData;
}
/// <summary>
/// Starts waiting for client connections.
/// </summary>
/// <remarks>
/// Blocks the current execution until a client pipe attempts to establish a connection.
/// </remarks>
/// <param name="handle">The pipe handle.</param>
#endregion
public static void Connect(PipeHandle handle)
{
handle.State = InterProcessConnectionState.WaitingForClient;
bool connected = NamedPipeNative.ConnectNamedPipe(handle.Handle, null);
handle.State = InterProcessConnectionState.ConnectedToClient;
if (!connected && NamedPipeNative.GetLastError() != NamedPipeNative.ERROR_PIPE_CONNECTED)
{
handle.State = InterProcessConnectionState.Error;
throw new NamedPipeIOException("Error connecting pipe. Internal error: " +
NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
/// <summary>
/// Creates a SECURITY_DESCRIPTOR with DACL = null, which allows full access to Everyone.
/// </summary>
/// <param name="sd">The SECURITY_DESCRIPTOR structure.</param>
#endregion
public static void GetNullDaclSecurityDescriptor(out SECURITY_DESCRIPTOR sd)
{
if (NamedPipeNative.InitializeSecurityDescriptor(out sd, 1))
{
if (!NamedPipeNative.SetSecurityDescriptorDacl(ref sd, true, IntPtr.Zero, false))
{
throw new NamedPipeIOException("Error setting SECURITY_DESCRIPTOR attributes. Internal error: " +
NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
else
{
throw new NamedPipeIOException("Error setting SECURITY_DESCRIPTOR attributes. Internal error: " +
NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
/// <summary>
/// Creates a server named pipe.
/// </summary>
/// <param name="name">The name of the pipe.</param>
/// <param name="outBuffer">The size of the outbound buffer.</param>
/// <param name="inBuffer">The size of the inbound buffer.</param>
/// <param name="secure">Specifies whether to make the pipe secure.</param>
/// <returns>The pipe handle.</returns>
/// <remarks>You can specify a security descriptor for a named pipe when you call the CreateNamedPipe function. The security descriptor controls access to both client and server ends of the named pipe. If NULL is specified, the named pipe gets a default security descriptor. The ACLs in the default security descriptor for a named pipe grant full control to the LocalSystem account, administrators, and the creator owner. They also grant read access to members of the Everyone group and the anonymous account.
/// <br/><br/>
/// If the <b>secure</b> parameter is false the method creates a security descriptor that grants full access to Everyone.
/// </remarks>
#endregion
public static PipeHandle Create(string name, uint outBuffer, uint inBuffer, bool secure)
{
name = @"\\.\pipe\" + name;
PipeHandle handle = new PipeHandle();
IntPtr secAttr = IntPtr.Zero;
SECURITY_ATTRIBUTES sa = new SECURITY_ATTRIBUTES();
if (!secure)
{
SECURITY_DESCRIPTOR sd;
GetNullDaclSecurityDescriptor(out sd);
sa.lpSecurityDescriptor = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(SECURITY_DESCRIPTOR)));
Marshal.StructureToPtr(sd, sa.lpSecurityDescriptor, false);
sa.bInheritHandle = false;
sa.nLength = Marshal.SizeOf(typeof(SECURITY_ATTRIBUTES));
secAttr = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(SECURITY_ATTRIBUTES)));
Marshal.StructureToPtr(sa, secAttr, false);
}
try
{
for (int i = 1; i <= ATTEMPTS; i++)
{
handle.State = InterProcessConnectionState.Creating;
handle.Handle = NamedPipeNative.CreateNamedPipe(
name,
NamedPipeNative.PIPE_ACCESS_DUPLEX,
NamedPipeNative.PIPE_TYPE_MESSAGE | NamedPipeNative.PIPE_READMODE_MESSAGE | NamedPipeNative.PIPE_WAIT,
NamedPipeNative.PIPE_UNLIMITED_INSTANCES,
outBuffer,
inBuffer,
NamedPipeNative.NMPWAIT_WAIT_FOREVER,
secAttr);
if (handle.Handle.ToInt32() != NamedPipeNative.INVALID_HANDLE_VALUE)
{
handle.State = InterProcessConnectionState.Created;
break;
}
if (i >= ATTEMPTS)
{
handle.State = InterProcessConnectionState.Error;
throw new NamedPipeIOException("Error creating named pipe " + name + " . Internal error: " +
NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
}
finally
{
if (!secure)
{
Marshal.FreeHGlobal(sa.lpSecurityDescriptor);
Marshal.FreeHGlobal(secAttr);
}
}
return(handle);
}
/// <summary>
/// Connects to a server named pipe.
/// </summary>
/// <param name="pipeName">The pipe name.</param>
/// <param name="serverName">The server name.</param>
/// <returns>The pipe handle, which also contains the pipe state.</returns>
/// <remarks>This method is used by clients to establish a pipe connection with a server pipe.</remarks>
#endregion
public static PipeHandle ConnectToPipe(string pipeName, string serverName)
{
PipeHandle handle = new PipeHandle();
// Build the name of the pipe.
string name = @"\\" + serverName + @"\pipe\" + pipeName;
for (int i = 1; i <= ATTEMPTS; i++)
{
handle.State = InterProcessConnectionState.ConnectingToServer;
// Try to connect to the server
handle.Handle = NamedPipeNative.CreateFile(name, NamedPipeNative.GENERIC_READ |
NamedPipeNative.GENERIC_WRITE, 0, null, NamedPipeNative.OPEN_EXISTING, 0, 0);
if (handle.Handle.ToInt32() != NamedPipeNative.INVALID_HANDLE_VALUE)
{
// The client managed to connect to the server pipe
handle.State = InterProcessConnectionState.ConnectedToServer;
// Set the read mode of the pipe channel
uint mode = NamedPipeNative.PIPE_READMODE_MESSAGE;
if (NamedPipeNative.SetNamedPipeHandleState(handle.Handle, ref mode, IntPtr.Zero, IntPtr.Zero))
{
break;
}
if (i >= ATTEMPTS)
{
handle.State = InterProcessConnectionState.Error;
throw new NamedPipeIOException("Error setting read mode on pipe " + name + " . Internal error: " +
NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
if (i >= ATTEMPTS)
{
if (NamedPipeNative.GetLastError() != NamedPipeNative.ERROR_PIPE_BUSY)
{
handle.State = InterProcessConnectionState.Error;
// After a certain number of unsuccessful attempt raise an exception
throw new NamedPipeIOException("Error connecting to pipe " + name + " . Internal error: " +
NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
else
{
handle.State = InterProcessConnectionState.Error;
throw new NamedPipeIOException("Pipe " + name + " is too busy. Internal error: " +
NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
else
{
// The pipe is busy so lets wait for some time and try again
if (NamedPipeNative.GetLastError() == NamedPipeNative.ERROR_PIPE_BUSY)
{
NamedPipeNative.WaitNamedPipe(name, WAIT_TIME);
}
}
}
return(handle);
}
/// <summary>
/// Writes an array of bytes to a named pipe.
/// </summary>
/// <param name="handle">The pipe handle.</param>
/// <param name="bytes">The bytes to write.</param>
/// <remarks>If we try bytes array we attempt to write is empty then this method write a space character to the pipe. This is necessary because the other end of the pipe uses a blocking Read operation so we must write someting.<br/><br/>
/// The bytes length is restricted by the <b>maxBytes</b> parameter, which is done primarily for security reasons.<br/><br/>
/// When writing to a pipe the method first writes four bytes that define the data length.
/// It then writes the whole message.</remarks>
#endregion
public static void WriteBytes(PipeHandle handle, byte[] bytes)
{
byte[] numReadWritten = new byte[4];
uint len;
if (bytes == null)
{
bytes = new byte[0];
}
if (bytes.Length == 0)
{
bytes = new byte[1];
bytes = System.Text.Encoding.UTF8.GetBytes(" ");
}
// Get the message length
len = (uint)bytes.Length;
handle.State = InterProcessConnectionState.Writing;
// Write four bytes that define the message length
if (NamedPipeNative.WriteFile(handle.Handle, BitConverter.GetBytes(len), 4, numReadWritten, 0))
{
// Write the whole message
if (!NamedPipeNative.WriteFile(handle.Handle, bytes, len, numReadWritten, 0))
{
handle.State = InterProcessConnectionState.Error;
throw new NamedPipeIOException("Error writing to pipe. Internal error: " + NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
}
else
{
handle.State = InterProcessConnectionState.Error;
throw new NamedPipeIOException("Error writing to pipe. Internal error: " + NamedPipeNative.GetLastError().ToString(), NamedPipeNative.GetLastError());
}
handle.State = InterProcessConnectionState.Flushing;
Flush(handle);
handle.State = InterProcessConnectionState.FlushedData;
}