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Printing to multiple printers from .NET WebBrowser - program hangs unless a MessageBox is used

The WebBrowser.Print method has the limitation of not allowing the caller to specify a printer other than the system's default one. As a workaround, it has been suggested[1], [2] to alter the system's default printer prior to calling Print(), however it's also reported[3] (and I experienced firsthand) that the WebBrowser instance will continue to print to the previously defined printer even after the system default is altered.
To work around that, registering a handler to the PrintTemplateTeardown event by accessing the underlying ActiveX object of the managed WebBrowser instance and waiting for the event to fire before printing further documents has been proposed[4], [5], and that is what I am trying to implement. I simplified what is a much more complex program to the MVCE presented below.
(The program is a .NET Core 3.1 Windows Forms application, with one form containing nothing more than a BackgroundWorker object named bw.)
Form1.cs
using System;
using System.ComponentModel;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;
using System.Drawing.Printing;
using System.Management;
namespace Demo_1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
bw.RunWorkerAsync();
}
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
while (true)
{
BwPolling();
Thread.Sleep(20000);
}
}
private void BwPolling()
{
string[] htmlStrings = { "test1", "test2" };
foreach (string html in htmlStrings)
{
Invoke((MethodInvoker)delegate
{
PrinterSettings.StringCollection installedPrinters = PrinterSettings.InstalledPrinters;
foreach (string printer in installedPrinters)
{
string[] validPrinterNames =
{
"Microsoft Print to PDF",
"Microsoft XPS Document Writer"
};
if ( validPrinterNames.Contains(printer) )
{
SetDefaultPrinter(printer);
var wb = new WebBrowser();
wb.DocumentText = html;
// With inspiration from code by Andrew Nosenko <https://stackoverflow.com/users/1768303/noseratio>
// From: https://stackoverflow.com/a/19737374/3258851
// CC BY-SA 3.0
var wbax = (SHDocVw.WebBrowser)wb.ActiveXInstance;
TaskCompletionSource<bool> printedTcs = null;
SHDocVw.DWebBrowserEvents2_PrintTemplateTeardownEventHandler printTemplateTeardownHandler =
(p)
=> printedTcs.TrySetResult(true); // turn event into awaitable task
printedTcs = new TaskCompletionSource<bool>();
wbax.PrintTemplateTeardown += printTemplateTeardownHandler;
try
{
MessageBox.Show("Printing to " + printer);
wb.Print();
printedTcs.Task.Wait();
}
finally
{
wbax.PrintTemplateTeardown -= printTemplateTeardownHandler;
}
wb.Dispose();
}
}
});
}
}
private static bool SetDefaultPrinter(string name)
{
// With credits to Austin Salonen <https://stackoverflow.com/users/4068/austin-salonen>
// From: https://stackoverflow.com/a/714543/3258851
// CC BY-SA 3.0
using ( ManagementObjectSearcher objectSearcher = new ManagementObjectSearcher("SELECT * FROM Win32_Printer") )
{
using ( ManagementObjectCollection objectCollection = objectSearcher.Get() )
{
foreach (ManagementObject mo in objectCollection)
{
if ( string.Compare(mo["Name"].ToString(), name, true) == 0 )
{
mo.InvokeMethod("SetDefaultPrinter", null);
return true;
}
}
}
}
return false;
}
}
}
The problem being faced is when I remove the message box from the BwPolling() method, right before calling Print(), i.e. when this line is removed:
MessageBox.Show("Printing to " + printer);
then the program freezes, nothing is printed, and the process must eventually be terminated.
I believe I can sort of understand the issue on its surface: WebBrowser requires an STA thread with an active message loop[6], [7]; by calling printedTcs.Task.Wait(); within a Invoke((MethodInvoker)delegate block (called on the Form1 instance; this. is ommited), I am blocking the STA thread and the application hangs waiting for an event that is never fired. This is in fact mentioned in a comment under the answer I credited in my code.
Just can't figure out what a proper solution would be. Got lost in attempts to run the printing routine in a secondary thread. Maybe something wrong in my execution, guess I require assistance in this. Any help?
Thanks.

Wireguard tunnel source to c#.Net: Service Run troubleshooting

I'm trying to make a simple console app client (starter.exe) on c# .NET Framework 4.6 to make a WireGuard protocol based connection using Wireguard source code.
What is done:
Downloaded wireguard source code from here: git://git.zx2c4.com/wireguard-windows
Successfuly built Tunnel.dll in ..\embeddable-dll-service\amd64\tunnel.dll via build.bat
Created a project in Visual Studio 2015.using the c# code from ..\embeddable-dll-service\csharp
Starting from here some strange thing are happenning:
if launching starter.exe \service <path to *.conf> I receive the
error
Service run error: The service process could not connect to the
service controller.
if launching starter.exe without parameters everything works fine until I remove the if{} block:
Unhandled Exception: System.ComponentModel.Win32Exception: The service
did not respond to the start or control request in a timely fashion
at WireGuardTunnel.Service.Add(String configFile) in
D:\Depository\BitBucket\WireGuard_Tunnel_Repository\WireGuardTunnel_proj\Launcher\Service.cs:line
69 at WireGuardTunnel.Program.Main(String[] args) in
D:\Depository\BitBucket\WireGuard_Tunnel_Repository\WireGuardTunnel_proj\Launcher\Program.cs:line
83
That means even if the code in if{} block is not executed it influencese somehow the application behaviour.
Next, as I want to make my app work with parameters I solved the
issue by removing return afer Service.Run and passing args[1] to Service.Add(args[1]). It works OK, but I have an extra log line (the first one due to Service.Run perpetual error described above) in the log:
Service run error: The service process could not connect to the
service controller. 235660: [TUN] [chicago4] Watching network
interfaces 245661: [TUN] [chicago4] Resolving DNS names
245661: [TUN] [chicago4] Creating Wintun interface 225660: [TUN]
[chicago4] Starting WireGuard/0.3.1 (Windows 6.1.7601; amd64)
So finally the questions:
Why Service.Run(confFile) does not work
Why Service.Run(confFile) influences the Service.Add(confFile)
Why if{} block is executed when I launch starte.exe with no parameters
The original Program.cs without modification:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;
using System.IO;
using System.Runtime.InteropServices;
namespace Tunnel
{
class Program
{
[DllImport("kernel32.dll")]
private static extern bool SetConsoleCtrlHandler(SetConsoleCtrlEventHandler handler, bool add);
private delegate bool SetConsoleCtrlEventHandler(UInt32 signal);
public static void Main(string[] args)
{
string baseDirectory = Path.GetDirectoryName(Process.GetCurrentProcess().MainModule.FileName);
string configFile = Path.Combine(baseDirectory, "demobox.conf");
string logFile = Path.Combine(baseDirectory, "log.bin");
if (args.Length == 2 && args[0] == "/service")
{
configFile = args[1];
Service.Run(configFile);
return;
}
try { File.Delete(logFile); } catch { }
Ringlogger log = new Ringlogger(logFile, "GUI");
var logPrintingThread = new Thread(() =>
{
var cursor = Ringlogger.CursorAll;
while (Thread.CurrentThread.IsAlive)
{
var lines = log.FollowFromCursor(ref cursor);
foreach (var line in lines)
Console.WriteLine(line);
Thread.Sleep(300);
}
});
logPrintingThread.Start();
SetConsoleCtrlHandler(delegate
{
Service.Remove(configFile);
Environment.Exit(0);
return true;
}, true);
try
{
Service.Add(configFile);
logPrintingThread.Join();
}
finally
{
Service.Remove(configFile);
}
}
}
}

Bit late to the party but I was having the exact same issue as above and discovered that in order to get everything working correctly you have to have Tunnel.Service.Run("path to config") defined on application initialization either in your main loop or your constructor then you can run Tunnel.Service.Add("path to config", true) which will create the service and start the VPN connection. It's also good practice to destroy the service on close using Tunnel.Service.Remove("path to config", true) as the service will continue to run and you will still be connected to your VPN until it is stopped manually.

Create Windows Session programmatically from Console or Windows Service

How can I programmatically log in to windows to create a Windows Logon Session?
I need a way that works from a WinForms app, from a Console app, and (most important) from a Windows Service.
One other requirement is that I need it to work on a the local system that the program/service is running on and also for remote systems.
If there's a way to do this using pInvoke/Win32 API I am open to that too.
I found these similar questions/answers in my research:
Programmatically create and launch and RDP session (without gui)
The answer here says it's possible but and gives a link but the sample code from the link doesn't work
Create a Windows Session from a service via the Win32 API
No Solution to the question asked
Create Windows session programmatically
No Solution but the OP mentioned in a comment that http://freerdp.com worked for him.

I've created a simple utility that I believe meets all the requirements in the question. You'll need to add a COM reference to Microsoft Terminal Services Active Client 1.0 Type Library (ActiveX).
I thought it might not work for creating a session on the local machine but I tested in in 2012R2 running as a Service and it actually can. The same exact method can be called from a WinForms app or from a Console app. When launched from a WinForms or Console app, the a form is shown for a few seconds so I made sure to set the control to enabled = false so it can't be interacted with.
using System;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using AxMSTSCLib;
namespace Utility.RemoteDesktop
{
public class Client
{
private int LogonErrorCode { get; set; }
public void CreateRdpConnection(string server, string user, string domain, string password)
{
void ProcessTaskThread()
{
var form = new Form();
form.Load += (sender, args) =>
{
var rdpConnection = new AxMSTSCLib.AxMsRdpClient9NotSafeForScripting();
form.Controls.Add(rdpConnection);
rdpConnection.Server = server;
rdpConnection.Domain = domain;
rdpConnection.UserName = user;
rdpConnection.AdvancedSettings9.ClearTextPassword = password;
rdpConnection.AdvancedSettings9.EnableCredSspSupport = true;
if (true)
{
rdpConnection.OnDisconnected += RdpConnectionOnOnDisconnected;
rdpConnection.OnLoginComplete += RdpConnectionOnOnLoginComplete;
rdpConnection.OnLogonError += RdpConnectionOnOnLogonError;
}
rdpConnection.Connect();
rdpConnection.Enabled = false;
rdpConnection.Dock = DockStyle.Fill;
Application.Run(form);
};
form.Show();
}
var rdpClientThread = new Thread(ProcessTaskThread) { IsBackground = true };
rdpClientThread.SetApartmentState(ApartmentState.STA);
rdpClientThread.Start();
while (rdpClientThread.IsAlive)
{
Task.Delay(500).GetAwaiter().GetResult();
}
}
private void RdpConnectionOnOnLogonError(object sender, IMsTscAxEvents_OnLogonErrorEvent e)
{
LogonErrorCode = e.lError;
}
private void RdpConnectionOnOnLoginComplete(object sender, EventArgs e)
{
if (LogonErrorCode == -2)
{
Debug.WriteLine($" ## New Session Detected ##");
Task.Delay(10000).GetAwaiter().GetResult();
}
var rdpSession = (AxMsRdpClient9NotSafeForScripting)sender;
rdpSession.Disconnect();
}
private void RdpConnectionOnOnDisconnected(object sender, IMsTscAxEvents_OnDisconnectedEvent e)
{
Environment.Exit(0);
}
}
}
On a side note I found this question that says there may be a way to use the ActiveX control (for RDP) without using a windows form at all. I saw the example they gave and I was unsure hot to use their code for this situation.
ActiveX control without a form
If there's anyone out there who understands how to do this without hosting the ActiveX control on a Form please post an example.

C# Skype API Video Call

I was working on a security monitor application and the best approach i found was Skype.
when a possible intrusion occurs the application calls a specified Skype ID which is probably my android phone i am done with all the image processing stuff. But i am stuck with this Skype API i wrote this piece of code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using SKYPE4COMLib;
namespace SkypeCall
{
class Program
{
static void Main(string[] args)
{
Skype skype;
skype = new Skype("Skype4COM.Skype", "Skype_");
Call call = skype.PlaceCall(SkypeID);
call.StartVideoSend();
}
}
}
This initiates a voice call but in the call.StartVideoSend(); shows an error
An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in SkypeCall.exe
Additional information: CALL: Action failed
i even tried this but i guess that's old API and couldn't get anything out of it.
And not even by sending commands .
if somebody would help me out i'll be grateful.

I think you need to wait until the call is connected.
easiest way would be to test the call.Status
class Program
{
static void Main(string[] args)
{
Skype skype;
skype = new SKYPE4COMLib.Skype();
string SkypeID = args[1];
Call call = skype.PlaceCall(SkypeID);
do
{
System.Threading.Thread.Sleep(1);
} while (call.Status != TCallStatus.clsInProgress);
call.StartVideoSend();
}
}
You could also add an event, however I think this will fire on every call so unless you are only using it for this project it might be too much.
class Program
{
static string SkypeID = "";
static void Main(string[] args)
{
Skype skype;
skype = new SKYPE4COMLib.Skype();
skype.CallStatus += new _ISkypeEvents_CallStatusEventHandler(skype_CallStatus);
Call call = skype.PlaceCall(SkypeID);
Console.ReadKey();
}
static void skype_CallStatus(Call pCall, TCallStatus Status)
{
if (Status == TCallStatus.clsInProgress && pCall.PartnerHandle == SkypeID) { pCall.StartVideoSend(); }
}
}

How to pass arguments to a console application if it is already running?

I use a Console Application in Windows Mobile to handle incoming message interception. In the same console application i accept parameters (string args[]) which based on the parameters, register the message interceptor.
InterceptorType is a enum
static void Main(string[] args)
{
if (args[0] == "Location")
{
addInterception(InterceptorType.Location, args[1],args[2]);
}
}
private static void addInterception(InterceptorType type, string Location, string Number )
{
if (type == InterceptorType.Location)
{
using (MessageInterceptor interceptor = new MessageInterceptor(InterceptionAction.NotifyAndDelete, false))
{
interceptor.MessageCondition = new MessageCondition(MessageProperty.Sender, MessagePropertyComparisonType.Contains, Number, false);
string myAppPath = Assembly.GetExecutingAssembly().GetName().CodeBase;
interceptor.EnableApplicationLauncher("Location", myAppPath);
interceptor.MessageReceived += new MessageInterceptorEventHandler(interceptor_MessageReceived);
}
}
}
static void interceptor_MessageReceived(object sender, MessageInterceptorEventArgs e)
{
//Do something
}
I made this a console application because i want it keep running in the background and intercept incoming messages.
This works fine for the first time. But the problem is that I have to keep calling the addInterception method to add subsequent interception rules. This makes the console application start again and again for each time i add a rule. How do i make this run only once and add more message interceptor rules?

Since you already have a method in place to call the command prompt once, update your logic with some simple looping so you can pass N commands.
EDIT: I wrote it a fully compileable example to show you exactly what I am talking about. Note how the child process can be called any number of times without re-launching. This is not just a simple command line launch with arguments being passed because that idea will lead to X processes which is exactly what you do not want.
PARENT PROCESS: (The one with System.Diagnostics.Process)
/// <summary>
/// This is the calling application. The one where u currently have System.Diagnostics.Process
/// </summary>
class Program
{
static void Main(string[] args)
{
System.Diagnostics.Process p = new Process();
p.StartInfo.CreateNoWindow = false;
p.StartInfo.UseShellExecute = false;
p.StartInfo.FileName = #"C:\AppfolderThing\ConsoleApplication1.exe";
p.StartInfo.RedirectStandardError = true;
p.StartInfo.RedirectStandardInput = true;
p.StartInfo.RedirectStandardOutput = true;
p.Start();
p.OutputDataReceived += delegate(object sender, DataReceivedEventArgs e)
{
Console.WriteLine("Output received from application: {0}", e.Data);
};
p.ErrorDataReceived += delegate(object sender, DataReceivedEventArgs e)
{
Console.WriteLine("Output received from application: {0}", e.Data);
};
p.BeginErrorReadLine();
p.BeginOutputReadLine();
StreamWriter inputStream = p.StandardInput;
inputStream.WriteLine(1);
inputStream.WriteLine(2);
inputStream.WriteLine(-1);//tell it to exit
p.WaitForExit();
}
}
CHILD PROCESS:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication3
{
enum InterceptorType
{
foo,
bar,
zee,
brah
}
/// <summary>
/// This is the child process called by System.Diagnostics.Process
/// </summary>
class Program
{
public static void Main()
{
while (true)
{
int command = int.Parse(Console.ReadLine());
if (command == -1)
Environment.Exit(0);
else
addInterception((InterceptorType)command, "some location", "0");
}
}
private static void addInterception(InterceptorType type, string Location, string Number)
{
switch (type)
{
case InterceptorType.foo: Console.WriteLine("bind foo"); break;
case InterceptorType.bar: Console.WriteLine("bind bar"); break;
default: Console.WriteLine("default bind zee"); break;
}
}
static void interceptor_MessageReceived(object sender, EventArgs e)
{
//Do something
}
}
}
Note that codeplex has a managed service library.

EDIT
It seems that people are misunterstanding your question (or I am) so here's some clarification on how I'm seeing the problem.
You have an console app that takes in command-line parameters. These parameters are used for something (the what is irrelevant actually). You want to be able to add parameters after the app is already running by calling the app with new command line args.
What is happening is that when you call the app any time after teh first, a new instance of the process starts up instead of the command-line arguments going to the existing, already running application.
END EDIT
The solution is fairly straightforward and requires two pieces.
You need a named mutex. For whatever (poor) reason, the CF doesn't expose a version of a mutex that takes a name, so you have to P/Invoke CreateMutex or use a library (like the SDF) that already has it. Your app needs to create the mutex at startup and check to see if it already exists. if it doesn't you're the first running instance and run as normal. If the mutex exists, you need to pass your command line args to the one that is already running via a P2P queue then simply exits.
After checking the mutex, the first instance spawns a worker thread. This thread listens on a P2P queue for messages. When they come in, you handle them.