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typedef

Joined: 25 Jul 2010
Posts: 2893
Location: 0x77760000

typedef 29 Jul 2010, 06:07

Hie all, i would like some help converting the following C code into ASM thanks

Code:


typedef int( *tempFunc )(int a, int b);

HINSTANCE hInst = LoadLibrary( "MyLibrary.DLL" );

tempFunc Func = (tempFunc)GetProcAddress( hInst, " MyFunctionName");

Func( 1, 2 );

i know i can just use

Code:


library lib,'myLib'

import lib,\
          myFunc,'myFunc'

but i wanted to do it the other way...can you pls help..thanks

29 Jul 2010, 06:07

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20759
Location: In your JS exploiting you and your system

revolution 29 Jul 2010, 06:13

Code:

 invoke  LoadLibrary,'MyLibrary.DLL'
       invoke  GetProcAddress,eax,'MyFunctionName'
       stdcall eax,1,2

29 Jul 2010, 06:13

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4623
Location: Argentina

LocoDelAssembly 29 Jul 2010, 06:14

Code:

include 'win32ax.inc'

proc start
local Func: DWORD,\
      hInst: DWORD

        invoke  LoadLibrary, "MyLibrary.DLL"
        mov     [hInst], eax

        invoke  GetProcAddress, [hInst], "MyFunctionName"
        mov     [Func], eax

        invoke  Func, 1, 2 ; If the function is not stdcall but cdecl then use cinvoke instead
        ; Alternate form: stdcall [Func], 1, 2 (or "ccall [Func], 1, 2" if it is cdecl)

        invoke  ExitProcess, 0
endp

.end start

29 Jul 2010, 06:14

typedef

Joined: 25 Jul 2010
Posts: 2893
Location: 0x77760000

typedef 29 Jul 2010, 06:30

thanks.....and btw, bfore i posted my question i tried the second one (without the procedure though) and i got windows error 'mem at such such addr could not be read' lol...i like the 1st one by revolution. i can understand it better. the second one is uhmm...fair..lol
otherwise i would say question answered and thanks to you guys. peace

29 Jul 2010, 06:30

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4623
Location: Argentina

LocoDelAssembly 29 Jul 2010, 19:59

Forgot to tell yesterday, revolution version is indeed easily to see but take in mind that it is equivalent to this:

Code:

typedef int( *tempFunc )(int a, int b); 

(tempFunc)GetProcAddress(LoadLibrary("MyLibrary.DLL"), " MyFunctionName")(1, 2);

If you have to call it a second time you better save EAX somewhere first and if you have to get more addresses from that DLL then again you better save EAX after LoadLibrary call.

29 Jul 2010, 19:59

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20759
Location: In your JS exploiting you and your system

revolution 30 Jul 2010, 02:09

Yes, my example was merely to illustrate how to get the handle and procedure address. Any extra requirements like saving and closing handles will need to be added.

30 Jul 2010, 02:09

typedef

Joined: 25 Jul 2010
Posts: 2893
Location: 0x77760000

typedef 30 Jul 2010, 03:14

LocoDelAssembly wrote:

Forgot to tell yesterday, revolution version is indeed easily to see but take in mind that it is equivalent to this:
Code:
typedef int( *tempFunc )(int a, int b); 

(tempFunc)GetProcAddress(LoadLibrary("MyLibrary.DLL"), " MyFunctionName")(1, 2);    
If you have to call it a second time you better save EAX somewhere first and if you have to get more addresses from that DLL then again you better save EAX after LoadLibrary call.

Oh! I see what you mean, i get it. thanks man. big time. Very Happy

30 Jul 2010, 03:14

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