LPARAM of user defined message

[shail2k4]

Hi all,

I am working with an external application (not my application)

This application posts a user defined message to perform a task. I have captured the message with help of spy++.

It contains some value in its lparam parameter which remains same during the application life ie. on restarting the application the lparam of the message changes.

If I try to send the same message (with the same value of LPARAM) to that application, it performs the same task.

Now the question is
how to find out that where this LPARAM parameter of the message is pointing to?

Thanx for any kind of help...

[VictorN]

In general it is not possible.

[Alex F]

If application source code is not available, the only way to to read Assembly code.

[Eri523]

The fact that the value changes with every new start of the app in question looks like the LPARAM value is some kind of handle. If it is a window handle, there's a chance that you might find out to which window of the app it belongs using Spy++, and then use FindWindow() or FindWindowEx() in your app to get its current handle.

HTH

[shail2k4]

If application source code is not available, the only way to to read Assembly code.

How can i do it with reading the assembly code.

Can you pls explore it.

Thanx

[shail2k4]

The fact that the value changes with every new start of the app in question looks like the LPARAM value is some kind of handle. If it is a window handle, there's a chance that you might find out to which window of the app it belongs using Spy++, and then use FindWindow() or FindWindowEx() in your app to get its current handle.

I have checked the window handles with spy++, but didnt found any window having the value equal to lparam.

Is it possible that it is pointing to some function in the dll?

Thanx

[Eri523]

Is it possible that it is pointing to some function in the dll?

I think that's unlikely. DLL function pointers are usually obtained using GetProcAddress() (unless the DLL is linked at load time) and I don't see any potential reason to pass them along with a message.

[Alex F]

Program which converts executable to Assembly is called disassembler. You can find free disassemblers making Google search. But if you ask this, I guess you don't know Assembly language, and cannot follow this way.

[OReubens]

It could be a window handle
It could be a pointer to something
It could be a unique random value generated at program startup
it could be a registered message
it could be an Atom handle
it could be god knows what...

Without a description, you're either going to be into a lot of debugging, or going to be stuck on this project.