/// <summary>
/// The CreateMailslotSecurity function creates and initializes a new
/// SECURITY_ATTRIBUTES object to allow Authenticated Users read and
/// write access to a mailslot, and to allow the Administrators group full
/// access to the mailslot.
/// </summary>
/// <returns>
/// A SECURITY_ATTRIBUTES object that allows Authenticated Users read and
/// write access to a mailslot, and allows the Administrators group full
/// access to the mailslot.
/// </returns>
/// <see cref="http://msdn.microsoft.com/en-us/library/aa365600.aspx"/>
static NativeMethods.SECURITY_ATTRIBUTES CreateMailslotSecurity()
{
// Define the SDDL for the security descriptor.
string sddl = "D:" + // Discretionary ACL
"(A;OICI;GRGW;;;AU)" + // Allow read/write to authenticated users
"(A;OICI;GA;;;BA)"; // Allow full control to administrators
NativeMethods.SafeLocalMemHandle pSecurityDescriptor = null;
if (!NativeMethods.ConvertStringSecurityDescriptorToSecurityDescriptor(
sddl, 1, out pSecurityDescriptor, IntPtr.Zero))
{
throw new Win32Exception();
}
NativeMethods.SECURITY_ATTRIBUTES sa = new NativeMethods.SECURITY_ATTRIBUTES();
sa.nLength = Marshal.SizeOf(sa);
sa.lpSecurityDescriptor = pSecurityDescriptor;
sa.bInheritHandle = false;
return sa;
}
static void Main(string[] args)
{
NativeMethods.SafeMailslotHandle hMailslot = null;
try
{
// Prepare the security attributes (the lpSecurityAttributes parameter
// in CreateMailslot) for the mailslot. This is optional. If the
// lpSecurityAttributes parameter of CreateMailslot is NULL, the
// mailslot gets a default security descriptor and the handle cannot
// be inherited. The ACLs in the default security descriptor of a
// mailslot grant full control to the LocalSystem account, (elevated)
// administrators, and the creator owner. They also give only read
// access to members of the Everyone group and the anonymous account.
// However, if you want to customize the security permission of the
// mailslot, (e.g. to allow Authenticated Users to read from and
// write to the mailslot), you need to create a SECURITY_ATTRIBUTES
// structure.
NativeMethods.SECURITY_ATTRIBUTES sa = null;
sa = CreateMailslotSecurity();
// Create the mailslot.
hMailslot = NativeMethods.CreateMailslot(
MailslotName, // The name of the mailslot
0, // No maximum message size
NativeMethods.MAILSLOT_WAIT_FOREVER, // Waits forever for a message
sa // Mailslot security attributes
);
if (hMailslot.IsInvalid)
{
throw new Win32Exception();
}
Console.WriteLine("The mailslot ({0}) is created.", MailslotName);
// Check messages in the mailslot.
Console.Write("Press ENTER to check new messages or press Q to quit ...");
string cmd = Console.ReadLine();
while (!cmd.Equals("Q", StringComparison.OrdinalIgnoreCase))
{
Console.WriteLine("Checking new messages...");
ReadMailslot(hMailslot);
Console.Write("Press ENTER to check new messages or press Q to quit ...");
cmd = Console.ReadLine();
}
}
catch (Win32Exception ex)
{
Console.WriteLine("The server throws the error: {0}", ex.Message);
}
finally
{
if (hMailslot != null)
{
hMailslot.Close();
hMailslot = null;
}
}
}