C++ Event Hooks - c++

I'm trying to understand event hooks in C++. I know what an event is, I've used them a lot in Java, C# and Javascript.
What I'm having trouble with is finding the documentation, and tutorials on stuff like global hooks, dll injection, global hooks without a DLL.
Lets say that I wanted to iterate through the browser tabis in FireFox .. would I need to hope that FireFox has an API for C++? Or lets say I wanted to do something when a user opens a new tab would I need to use a hook that FireFox would provide in their API?
The above is just an example so people know what I'm trying to learn/understand. Am I thinking on the right ines?
I seen a post on a forum and for the past 2 hours I've took an interest. I always say that a tricky challange, or a new challange, makes a stronger programmer.
Any resources, or any help, would be very much appreciated.

C++ itself does not have events or hooks, but a lot of C++ libraries and frameworks implement them. For an example of generic events library, see Boost.Signals.
Some of the implementations allow their events to be seen by other applications, but the API is application-specific (e.g. for Firefox, see XPCOM).
Windows has a mechanizm of hooks that allows to monitor various events in its windowing system. However, it is an OS feature, not related to C++. As it's a system mechanizm, all Windows applications are affected even if they don't do anything for it. The documentation for Windows hooks can be found here. Also, since you mentioned "global hooks without a DLL", see SetWinEventHook, which is a higher-level API than Windows hooks linked above and can be used with hook functions both implemented in DLLs or EXEs.

Look up MSDN for SetWindowsHookEx. It should be your entrance in Windows hooks. If you ar etargetting a parituclar window for mthe system then a less intrusive option is SetWindowLongPtr. For the first API you are going to need some Dll injection - which gets automatically for you by the system. Just follow these steps:
Create a Dll that exports a HOOKPROC function (actual type dependent upon the hook tpe - read in the docs)
Load that Dll in your application and retrieve a pointer to the HOOKPROC function. LoadLibrary / GetProcAddress APIs may be used for this.
From your application, make a call to SetWindowsHookEx feeding in the appropriate parameters - this will inject the dll in the target process. So, the dll is now loaded into both your app's process and in the target process. So you will need a mechanism to IPC between the two processes probably. Lots of ways here - sockets, pipes, shared segment in DLL, filesystem, windows messages, COM servers + events, etc etc.
The former API, while less powerful, does not require DLL injection.
Choose wisely & good luck!

I dont think firefox would be having a C++ aPI to find the open tabs....
If you want to find out open tabs or whenever a new tab is open , you can basically hook the firefox window and get all events happening on that window to your hook procedure.
If you open spy++ in VC++ and track firefox window , you can see a new MozillaContentWindowClass gets created every time whenever a new tab is opened. So you can basically iterate through window handles and get information about open tabs.
You can use SetWindowLongPtr to set the subclass procedure for that window.

Related

Embedd an external application in a widget under Qt

I was wondering either it is possible to run an external application inside a QT widget under windows operating system. For example, if I were to write a Qt gui application, where in one of the dialogs user could write some text, I could use a textbox there or something similar. But instead, would it be possible to run Notepad++ or windows notepad application in that dialog?
I would appreciate all help.
It is not really practical to do what you describe at the application level, embedding an entire process into a window of another. (It would be technically difficult and the user experience would likely be pretty bad if you could pull it off.)
Fortunately, this very problem of application components has already been solved!
So it is possible to get the end result you describe via a slightly different mechanism. Many applications expose COM interfaces for automation and embedding, and it is possible to embed COM objects within a Qt application.
(Older technologies such as DDE, OLE and ActiveX provided various aspects of this but are all basically deprecated in favour of COM AFAIK.)
Hopefully you can find a COM object from a third party, or find an app that exposes its components via COM and assemble your app that way.
Have a look at the Qt documentation:
Active Qt - ActiveX and COM support for Qt

How to customize right click with already existing instance of a program?

I need to customize right click so that I can scan a directory with my anti-virus. I know how to do that using registry keys, but the problem is that I don't want to start a new instance of my program every time I want to scan a directory. My anti-virus needs to load some signature databases so it will take around 15 seconds for the program to load those. I need to use the instance of the program which I have already opened and is running for scanning the directory. How can I do that?
I am using C++Builder.
Thanks.
Considering you already know how to add the item to the right click contextual menu, I suggest implementing a client/server set of applications:
A server that loads up when you turn your computer on and does the scanning, and
The client that tells it what to do using IPC - inter-process communication.
You then add the client application to various contextual menus, passing it arguments that indicate what it should get the server to do depending on what you right-clicked on.
IPC is a bit of a pain in the butt, the easiest way is to use TCP/IP to and do local networking using a network library. There are many out there, however given you'll likely want to have other features such as UI elements and a tray icon, I suggest you look at Qt, namely the following components:
QtNetwork: For performing communication between the client and the server executable.
QSystemTrayIcon: For displaying a small icon on the tray.
There are quite a few other little bits of Qt you'll no doubt encounter (like all the fabulous UI stuff), and fortunately Qt is well documented and help is always available here, and from the Qt Developer Network. You can get started with Qt by downloading and installing the SDK:
http://qt.nokia.com/downloads/
Best of luck :).
Implement a DDE server in your anti-virus, and then add a ddeexec subkey to your Registry key. Alternatively, add an OLE Automation object to your app that implements the IDropTarget interface, and then add a DropTarget subkey to your Registry key that specifies the object's CLSID.
Either way, whenever your menu item is then invoked, Windows will call into your existing app instance if it is already running, otherwise it will launch a new instance and then call into it. Either way, Windows is handling all of that for you. All you are doing is providing an entry point for Windows to call into.
I would suggest the IDropTarget method, because DDE is deprecated, and because IDropTarget is more flexible. While your app is running, you could re-use the same IDropTarget object to handle OLE Drag&Drop operations on your app's UI window and Taskbar button, and support automated invokations of your scanner by other apps.

How can I keep track of ActiveX controls created by a process?

I'd like to keep track of the ActiveX controls created by some process. To simplify the problem, I'd first like to monitor the current process only. I want to do this so that I can check whether any ActiveX control supports IOleWindow and if so, whether a given HWND belongs to that ActiveX control (so that I can map HWNDs to ActiveX controls).
Does anybody have experience with this? My first idea was to use API hooking to monitor CoCreateInstance invocations, but I read that this doesn't work in all cases. Some Google research revealed http://www.pocketsoap.com/sf/activation.html which talks about installing a custom class factory - how would this work?
You may find you can find out what you need to know using the UI Automation and Active Accessibility APIs:
http://msdn.microsoft.com/en-us/library/dd317978(VS.85).aspx
If you are sure you need to do this, be aware of the following. CoCreateInstance is essentially a convenience function, which wraps CoGetClassObject and IClassObject::CreateInstance.
If you are going to use that technique you will therefore have to hook CoGetClassObject too, as the process may use it directly.
And of course there is no law saying any library or DLL cannot provide it's own convenience functions which bypass the COM registry altogether. The registry itself is a convenience - if you know where the DLL is you can use LoadLibrary, GetProcAddress to find DllGetClassObject and retrieve the class object without involving the COM libraries, and indeed without the DLL being registered at all.
I ended up hooking CoCreateInstance and CoGetClassObject to track all COM objects being created.

How can I communicate between two C++ MFC plugins?

I have a plugin for a c++ MFC app. I'm working with the developer of another plugin for the same app, that's trying to get notifications of events in my code. Both plugins are in the form of c++ dlls.
How can I pass messages from my plugin to his plugin? The solution needs to be robust to mismatched versions of our two plugins, as well as the host app. The notifications are during control point movement, so several times a second.
I could set up a callback mechanism, where upon load his plugin calls a function in my plugin with a function pointer. We're not guaranteed any loading order, but we could probably just check periodically.
I know Win32 has a messaging system, but I'm not sure how it works, really. We could add a hook, and I could send messages, but I'm a bit fuzzy on how we'd synchronize what the message id is, or any details other than what I said, really.
Any other ideas on how to do this?
I'm a bit fuzzy on how we'd synchronize what the message id
Use the RegisterWindowMessage API.
Take a look at this article here, it shows the available IPC mechanisms in windows. I might try COM, Mailslots, Pipes or Shared Memory (file mapping) in your case, in addition to windows messages which you already mentioned.

Automating VB6 application with ActiveX controls

I have a VB6 application that I don't have source code. This application uses third-party ActiveX controls. I want to automate these ActiveX controls. Is it possible to get the IUnknowns or Object references? For some of these, I can get the underlying HWNDs, but from what I can tell there isn't a generic way to convert these HWNDs to the ActiveX control.
Some testing software allows you to script VB6 applications with ActiveX controls. How do they do it?
Are these ActiveX controls in a separate DLL? If so, you can use OLE View (an VS 6.0 tool) to open the dll and view all the interfaces, coclasse and etc.
You might be able to using DLL injection via Microsoft Research Detours library. Basically you'd want to hook the cocreate for those specific controls. You will need to be ultra careful especially if you do anything cross-thread/cross-process (COM threading rules are vitally important).
On whole Detours is easy to use... but I've never tried it with COM routines. You might want to look at a different solution.
Also note that Detours has some licensing restrictions on it that may affect your ability to distribute it.
Testing software may well just send the appropriate WM_XXX messages to the particular windows in question (eg. WM_MOUSEMOVE).
Sorry to say but the VB6 EXE don't contain the manifests needed to pull out the COM objects it uses. You best bet is trying some of rbobby's suggestions especially about sending WM_XXX messages.