Simple DLL template?

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AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 19 Dec 2007, 23:55

I have never needed to make a library before, but could somebody please direct me to some code or tutorial of how to make a simple DLL template? I have seen several before, but I never use proc or struc or any of that. I just need a simple dll which will allow me to call the functions from the main program written in C or asm. There will be over a dozen functions contained in the DLL, quite a bit of data, and I was wondering how you would go about importing/exporting the functions to be called in the main program. Could somebody give me a simple template or explanation please?

19 Dec 2007, 23:55

kohlrak

Joined: 21 Jul 2006
Posts: 1421
Location: Uncle Sam's Pad

kohlrak 20 Dec 2007, 01:19

Erm, you want a DLL that calls procedures from an EXE?

20 Dec 2007, 01:19

AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 20 Dec 2007, 01:22

no, I just want a simple dll - I have a lot of asm code that I do not want in the program, so I want to know how to create a dll in assembly, call that dll from a program in assembly (just how to import it) and that is it. Sry for unclear-ness

20 Dec 2007, 01:22

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 20 Dec 2007, 01:41

Have you checked the examples on the package? (EXAMPLES\DLL)

20 Dec 2007, 01:41

AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 20 Dec 2007, 01:46

Yes, they are for gui things, I'll look over -it- again but I got a little lost when they started calling proc. Do you need to have your dll functions declared as proc for them to be exported? or can you just export a label? All I have is raw assembly, no structures, proc, or anything like that. Just a simple, few-line template of how to make the library and anything special that is needed.

PS: do I need to declare .reloc like the example does? Just wonderin.
Is this it?

Code:

format PE DLL ;Don't know if console or gui
entry MyLabel

include '%fasminc%\win32ax.inc'

section '.code' code readable executable
        MyLabel:
                ;?? why does a dll need an entry??
                ;Couldn't I just place all my functions
                ;In here and declare no entry??
                ;Or is it just for show?
        OneOfMyFunctions:
                ;LALALALA

section '.idata' import data readable writeable

        ;Nothing to import!!! all my code i have
        ;But I think windows always needs an import..

section '.edata' export data readable

        export 'MYLIB.DLL',\
               ;All my labels here that represent functions
               MyFunction,'OneOfMyFunctions'

section '.reloc' fixups data discardable
        ;Do I really need to include this section?

20 Dec 2007, 01:46

kohlrak

Joined: 21 Jul 2006
Posts: 1421
Location: Uncle Sam's Pad

kohlrak 20 Dec 2007, 05:00

Proc is just a fancy lable and local variable set. You don't have to use proc, but it does make it easier. As for the reloc, i heard you do, but i never tested to find out what happens if you don't have it.

20 Dec 2007, 05:00

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20343
Location: In your JS exploiting you and your system

revolution 20 Dec 2007, 05:13

kohlrak wrote:

As for the reloc, i heard you do, but i never tested to find out what happens if you don't have it.

Relocations are important in DLL's. They are used when there is a clash between two or more DLL's/EXE's that load at the same address.

In many cases the DLL will still load and work without the relocations but it is not possible to guarantee it will work in all cases.

20 Dec 2007, 05:13

AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 20 Dec 2007, 22:16

Yes, I have known that the reloc in DLL's are needed, but I didn't think that in Windows a program with one dll would need it. I will include it anyway, justfor good practice

NEW QUESTION: Does the entry point in a DLL get executed whenever a function in the dll is called? How does that work? Would this work?

Code:

format PE GUI 4.0 DLL 
entry Init 

;Later 
Init: 
       push ebp 
       mov ebp,esp 
       pusha 
       ret 

;All my functions already have above code done for them?

[/code]

20 Dec 2007, 22:16

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