System.Runtime.InteropServices.SEHException when trying to run multiple instances.

[alandixon]

Specifically, I'm using the MultipleInstances demo project.

The variable parallelInstances is set to 4 by default. For this value and any other value over 2, I intermittently get the SEHException, usually around the time everything starts to tear down.

After quite a lot of fiddling, I'm fairly sure the problem is to do with the virtual desktops; If I force TorSharpSettings.ToolRunnerType to return ToolRunnerType.Simple, the problem goes away. Of course, if I do that, I get a lot of popup privoxy windows, but it proves the point.

I am using Windows 10 64-bit which is why the ToolRunnerType defaults to VirtualDesktop.

I've tried lock in a few places to force single threading but not managed to isolate a vulnerable area of code.

The message is:

System.Runtime.InteropServices.SEHException
  HResult=0x80004005
  Message=External component has thrown an exception.

and the stack trace in Visual Studio 2022 is:

[Exception] System.Private.CoreLib.dll!Microsoft.Win32.SafeHandles.SafeFileHandle.ReleaseHandle()
[Exception] System.Private.CoreLib.dll!System.Runtime.InteropServices.SafeHandle.InternalRelease(bool disposeOrFinalizeOperation)
[Exception] System.Private.CoreLib.dll!System.Runtime.InteropServices.SafeHandle.Dispose(bool disposing)
[Exception] System.Private.CoreLib.dll!System.Runtime.InteropServices.SafeHandle.~SafeHandle()
[Managed to Native Transition]  
System.Private.CoreLib.dll!Interop.Kernel32.CloseHandle(System.IntPtr handle)
System.Private.CoreLib.dll!Microsoft.Win32.SafeHandles.SafeFileHandle.ReleaseHandle()
System.Private.CoreLib.dll!System.Runtime.InteropServices.SafeHandle.InternalRelease(bool disposeOrFinalizeOperation)
System.Private.CoreLib.dll!System.Runtime.InteropServices.SafeHandle.Dispose(bool disposing)
System.Private.CoreLib.dll!System.Runtime.InteropServices.SafeHandle.~SafeHandle()

[seanstardev]

I think this issue probably emerged immediately after 2.10.0 release. The System.Runtime.InteropServices.SEHException bug can be reproduced just by creating new Tor identities in quick succession, from my studies.

[seanstardev]

I also think I read about an arbitrary crash that can happen when using this library, and I definitely have experience of TorSharp crashing out pretty frequently. May be related to this bug - not sure.

All this said - it is a brilliant library and I really admire the work that has gone into it. Super impressive.

[joelverhagen]

Frankly, I wrote the Virtual Desktop code when I had less experience with PInvoke and Windows APIs. I think there are probably some bad assumptions in the implementation. I have only a little time these days to work on TorSharp due stuff in my personal life so if anyone has a chance to look at a fix or even provide a minimal repro, that might help. I'll leave this open since it appears it's not an isolated problem (4 upvotes).

[itHanVV]

This happened to me in version 2.15.0 as well