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Odecey
Master Cheater
 Reputation: 1
Joined: 19 Apr 2007
Posts: 259
Location: Scandinavia
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 Posted: Tue Nov 11, 2008 1:45 pm Post subject: Problem with building .dll |
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After receiving no reply in my other thread where I asked if it was possible to hook a function in C#, i tried searching a bit it seems that this would be impossible . I then looked for a solution in C++, and came across this code which I tried to compile: | Code: |
#include <windows.h>
#define SIZE 6
typedef int (WINAPI *pMessageBoxW)(HWND, LPCWSTR, LPCWSTR, UINT);
int WINAPI MyMessageBoxW(HWND, LPCWSTR, LPCWSTR, UINT);
void BeginRedirect(LPVOID);
pMessageBoxW pOrigMBAddress = NULL;
BYTE oldBytes[SIZE] = {0};
BYTE JMP[SIZE] = {0};
DWORD oldProtect, myProtect = PAGE_EXECUTE_READWRITE;
INT APIENTRY DllMain(HMODULE hDLL, DWORD Reason, LPVOID Reserved)
{
switch(Reason)
{
case DLL_PROCESS_ATTACH:
pOrigMBAddress = (pMessageBoxW)
GetProcAddress(GetModuleHandle("user32.dll"),
"MessageBoxW");
if(pOrigMBAddress != NULL)
BeginRedirect(MyMessageBoxW);
break;
case DLL_PROCESS_DETACH:
memcpy(pOrigMBAddress, oldBytes, SIZE);
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
break;
}
return TRUE;
}
void BeginRedirect(LPVOID newFunction)
{
BYTE tempJMP[SIZE] = {0xE9, 0x90, 0x90, 0x90, 0x90, 0xC3};
memcpy(JMP, tempJMP, SIZE);
DWORD JMPSize = ((DWORD)newFunction - (DWORD)pOrigMBAddress - 5);
VirtualProtect((LPVOID)pOrigMBAddress, SIZE,
PAGE_EXECUTE_READWRITE, &oldProtect);
memcpy(oldBytes, pOrigMBAddress, SIZE);
memcpy(&JMP[1], &JMPSize, 4);
memcpy(pOrigMBAddress, JMP, SIZE);
VirtualProtect((LPVOID)pOrigMBAddress, SIZE, oldProtect, NULL);
}
int WINAPI MyMessageBoxW(HWND hWnd, LPCWSTR lpText, LPCWSTR lpCaption, UINT uiType)
{
VirtualProtect((LPVOID)pOrigMBAddress, SIZE, myProtect, NULL);
memcpy(pOrigMBAddress, oldBytes, SIZE);
int retValue = MessageBoxW(hWnd, lpText, lpCaption, uiType);
memcpy(pOrigMBAddress, JMP, SIZE);
VirtualProtect((LPVOID)pOrigMBAddress, SIZE, oldProtect, NULL);
return retValue;
} |
When I try to build this in an otherwise empty project, I get the error:"Fatal error LNK1561: entry point must be defined", I was bewildered at this, since i thought DllMain was the entry point. How can I make this build? Any help is as alway appreciated =).
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hcavolsdsadgadsg
I'm a spammer
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Joined: 11 Jun 2007
Posts: 5801
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| Posted: Tue Nov 11, 2008 2:02 pm Post subject: |
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| Code: | | #pragma comment(linker, "/ENTRY:DllMain") |
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Noz3001
I'm a spammer
 Reputation: 26
Joined: 29 May 2006
Posts: 6220
Location: /dev/null
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| Posted: Tue Nov 11, 2008 2:15 pm Post subject: |
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Or try defining it like this:
| Code: | BOOL WINAPI DllMain( HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved );
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lurc
Grandmaster Cheater Supreme
 Reputation: 2
Joined: 13 Nov 2006
Posts: 1900
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| Posted: Tue Nov 11, 2008 2:17 pm Post subject: |
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Are you compiling under the DLL subsystem?
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Odecey
Master Cheater
Reputation: 1
Joined: 19 Apr 2007
Posts: 259
Location: Scandinavia
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| Posted: Tue Nov 11, 2008 2:21 pm Post subject: |
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Adding that resulted in a new error: Fatal error LNK1276: Invalid directive 'DllMain' found; does not start with '/'. I tried randomly adding/subtracting '/' and spaces to see if you could have mistyped, but to no avail =/.
Edit: Lurc what do you mean? I made a new empty project, added a .cpp file and pasted the code within it.
Edit 2: I'll try what you suggested noz. *Edit* Did not work =(.
Thanks for the replies ^_^.
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BanMe
Master Cheater
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Joined: 29 Nov 2005
Posts: 375
Location: Farmington NH, USA
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| Posted: Tue Nov 11, 2008 4:00 pm Post subject: |
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what are you compiling with? VC++ GCC codeblox ?
if you are using VC++ a empty project will not compile a dll u have to direct the compiler to compile a dll o0.. if you dont know these small simple facts.. you need to play with you compiler options more before asking simple questions
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hcavolsdsadgadsg
I'm a spammer
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Joined: 11 Jun 2007
Posts: 5801
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| Posted: Tue Nov 11, 2008 4:40 pm Post subject: |
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| Are you building with the switch?
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BirdsEye
Advanced Cheater
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Joined: 05 Apr 2008
Posts: 94
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| Posted: Tue Nov 11, 2008 4:54 pm Post subject: |
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| Odecey wrote: | | Edit: Lurc what do you mean? I made a new empty project, added a .cpp file and pasted the code within it. |
Okay. So re-open your IDE and assuming you have Visual C++ 2008, select a new 'Win32 Project.' Before going any furthur, tick 'DLL' radiobox under the 'Application type:' text. Now just select your previous options and have fun.
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Odecey
Master Cheater
Reputation: 1
Joined: 19 Apr 2007
Posts: 259
Location: Scandinavia
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| Posted: Wed Nov 12, 2008 4:08 am Post subject: |
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Thanks BirdsEye, that did the trick =).
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