I have a Windows local service that may spawn off a process to execute a JScript script (in a .js file) via the Windows Script Host. The issue is that I need to notify my service of the results generated by the script in the .js file. A transfer or a simple 32-bit integer, or a string would suffice. What would be the way to do this?
PS. The code must run on Windows XP SP3 or later OS.
Your best bet is to create an out of process COM object that executes within your service. Just implement the necessary scripting interfaces and provide a member function to match the notification and call it from your script as such:
newObj = new ActiveXObject("localserver.mynotify");
newObj.Notify("finished");
Would the exit code of the process be enough?
Windows Scripting host has has a .Quit(errorCode) method that allows you to set the exit code.
You should be able to call WSH directly from the service and get the return code with GetProcessExitCode() by passing the process handle that you received after spawning it.
Note that almost everything you can do from a JScript file can also be done with native code.
Do you have to execute the .js file as an external process? Windows Scripting has COM objects that an app can use to run scripts within its own process. I use this to execute script files within my service processes, and it works fine. The hosting process can even implement its own IDispatch-based classes and pass them to the scripting engine to expose to scripts as global objects so the scripts can communicate with the hosting process without having to use new ActiveXObject or CreateObject() to access those objects.
I see your script is written in JScript and your app in C++.
Perhaps the easiest way to accomplish what you want is by writing a file, say, to programdata folder which your service should have access to. Maybe use a GUID for the particular request, pass that to the JScript so it's guaranteed to be a unique file. Not ideal.
Another way to get JScript output ... Can you call out to managed code (C#)? If so, you could use a .NET-based or .NET-callable JavaScript compiler/interpreter. This would allow you to avoid IActiveScript and also to grab the values right out of the script context or from function return. I've used Jurassic and JavaScriptDotNet, both very easy to use and extend.
This might open a problem if you heavily rely on ActiveXObject calls (ie: FileSystemObject) and don't want to write components. JuraScript wraps the Jurassic engine and add ActiveXObject support to it for COM automation.
I am a C++ newb, so I don't know how much of a leap this is for you although I know it's possible to interop between managed/C++.
Just thought I'd mention these scenarios as I didn't see them listed in answers.
Related
I have a C++ COM (multi-threaded apartment model) application that I build with Visual C++ 2019. I am playing with the COM-based Active Script interfaces and classes. I have a JavaScript ("JScript" really, CLSID {F414C260-6AC0-11CF-B6D1-00AA00BBBB58}) Active Script COM object created and set up. Everything works surprisingly well (for something that is falling into obscurity, unfortunately).
Is there an idiomatic approach to registering and calling event listeners where a script can use an API like like https://dom.spec.whatwg.org/#dom-eventtarget-addeventlistener and where I can dispatch events from the script host (C++)? To clarify, I am well able to call IDispatch interface methods from scripts, I want to call script functions that were passed earlier with such methods to the program, from the program. GetScriptDispatch is something else -- it lets me call methods available in the global script namespace, but I need to call functions that I pass to a proxied (from the script) "addEventListener" method.
I depend on this functionality because I want to dispatch events. Basically I want addEventListener to be available on certain proxied (e.g. objects added to script namespace with AddNamedItem) objects and I need to call event listeners added through calls to that method, when certain events in the C++ application happen.
I have read something about IConnectionPoint, and the Active Script documentation briefly mentions "event sinks" a couple of times, without there being examples on how and for what these can be used for. There is also the IBindEventHandler interface, without much explanation again as to what to use it for.
I understand this is ancient stuff, but I like COM and Active Script interface has several implementations, which to me adds utility.
You need to create an object that implements events (see IConnectionPoint).
After starting the script you can call AddNamedItem. The script now knows the interface of you object. If it implements it can register to this events when the state changes to SCRIPTSTATE_CONNECTED.
If an event is fired, the script will receive the event and will execute the appropriate code section.
There are old samples:
Q168214 SAMPLE: MFCAXS (you might find it in the wayback engine)
And there is a sample here in code project
For ATL samples for Events look here
I need to hook copyfile in order to stop the process whenever a malicious file is being copied. I saw a question asked by Cat Man Do
Hook into the Windows File Copy API from C#
and he mentioned that there is a solution for this problem in c++. I am using embarcadero c++ builder(non-MFC). Is this solution applicable for c++ builder and if it is can anybody post the link or give me a hint on how to hook copyfile in c++?
You're not being specific about what you mean by "stop the process" - whether there is a specific process you are interested in, or whether you want to block all file copies throughout the entire system. If you want to block all file copies throughout the system, then what you're looking for is a file system filter driver. This is extremely advanced, since you will be writing a kernel-mode driver. Not for the faint of heart. Note also that you may end up being flagged as malware yourself, since malware will try to hook the file system in order to hide themselves.
I recommend using Deviare API hook to do it. You can use its COM objects to intercept CopyFile and CopyFileEx APIs and prevent the call returning ACCESS DENIED in the last error.
Our app is ran from SU or normal user. We have a library we have connected to our project. In that library there is a function we want to call. We have a folder called notRestricted in the directory where we run application from. We have created a new thread. We want to limit access of the thread to file system. What we want to do is simple - call that function but limit its access to write only to that folder (we prefer to let it read from anywhere app can read from).
Update:
So I see that there is no way to disable only one thread from all FS but one folder...
I read your propositions dear SO users and posted some kind of analog to this question here so in there thay gave us a link to sandbox with not a bad api, but I do not really know if it would work on anething but GentOS (but any way such script looks quite intresting in case of using Boost.Process command line to run it and than run desired ex-thread (which migrated to seprate application=)).
There isn't really any way you can prevent a single thread, because its in the same process space as you are, except for hacking methods like function hooking to detect any kind of file system access.
Perhaps you might like to rethink how you're implementing your application - having native untrusted code run as su isn't exactly a good idea. Perhaps use another process and communicate via. RPC, or use a interpreted language that you can check against at run time.
In my opinion, the best strategy would be:
Don't run this code in a different thread, but run it in a different process.
When you create this process (after the fork but before any call to execve), use chroot to change the root of the filesystem.
This will give you some good isolation... However doing so will make your code require root... Don't run the child process as root since root can trivially work around this.
Inject a replacement for open(2) that checks the arguments and returns -EACCES as appropriate.
This doesn't sound like the right thing to do. If you think about it, what you are trying to prevent is a problem well known to the computer games industry. The most common approach to deal with this problem is simply encoding or encrypting the data you don't want others to have access to, in such a way that only you know how to read/understand it.
I'm trying to find an easy way to execute a java vm in windows using a C++ wrapper. I can use CreateProcess() to launch java.exe directly with all of my parameters that I need to give it. The problem is this now shows up as two processes in process manager. So, if I kill the parent process, the java.exe instance still sticks around.
The reason I need to do this is that we have a few java programs, all of which will be running concurrently. I want to be able to give them distinguishable names in the process explorer, so that if a user has trouble with one of them, they don't have to guess which java.exe process that corresponds to.
You can replace java.exe with your own executable. This article from the Java Glossary discusses how java.exe works and where to find the source for it. It's possible that you could get by simply by copying and then renaming java.exe
I'm reading through a tutorial on using voice commands to control applications and, in an example of controlling rhythmbox, it suggests commands such as the following can be executed:
rhythmbox-client --play
rhythmbox-client --pause
Why does this not simply open a new instance of the program, and how can I emulate the functionality in my own programs? For example, how could I pass a string to a particular instance of a program?
Thanks
Rhythmbox uses inter-process communictation to achieve this type of functionality, and this can be implemented in a number of different ways. One of them is to use D-Bus, like Rhythmbox does.
Using D-Bus is not very easy, but the basic idea is that you register your application in D-Bus, so other applications can call different procedures your app exports (for example play/stop actions), and then in the same application implement a client. This way, if arguments like --play are passed, you don't run the usual code, but just check for an instance of the running app and send a command to your already running program.
On the other hand, when no arguments are passed, your program just starts and registers the proper triggers, so that a later called instance can control it.
Here is a tutorial on dbus, and the DBus homepage
There are several techniques to have only one application instance running. In these terms calling yyy --play would generally mean the same as
INSTANCE = GET_RUNNING_INSTANCE()
IF INSTANCE == NULL
INSTANCE = CREATE_NEW_INSTANCE()
SEND_MESSAGE(INSTANCE, PLAY)
For example, how could I pass a string to a particular instance of a program?
You'll need to use whatever interprocess communication facilities your operating system offers. Sockets or named pipes, for example, or messages.