Detours

[MAUROW]

DWORD E9Detours( DWORD SrcVA, DWORD DstVA, DWORD Size )
{
DWORD DetourVA, dwProtect, i;

#define SIZEOF_JMP_REL 5

if ( SrcVA && DstVA && Size >= SIZEOF_JMP_REL )
{
DetourVA = (DWORD) VirtualAlloc(
NULL, Size + SIZEOF_JMP_REL,
MEM_COMMIT, PAGE_EXECUTE_READWRITE );

if ( DetourVA && VirtualProtect( (VOID*)SrcVA, Size, PAGE_EXECUTE_READWRITE, &dwProtect ) )
{
for ( i=0; i < Size; i++ ) {
*(BYTE*)( DetourVA + i ) = *(BYTE*)( SrcVA + i );
}

*(BYTE*)( DetourVA + Size + 0 ) = 0xE9;
*(DWORD*)( DetourVA + Size + 1 ) = ( SrcVA - DetourVA - SIZEOF_JMP_REL );

*(BYTE*)( SrcVA + 0 ) = 0xE9;
*(DWORD*)( SrcVA + 1 ) = ( DstVA - SrcVA - SIZEOF_JMP_REL );

VirtualProtect( (VOID*)SrcVA, Size, dwProtect, &dwProtect );

VirtualProtect( (VOID*)DetourVA, Size +
SIZEOF_JMP_REL, PAGE_EXECUTE_READ, &dwProtect );

return DetourVA;
}
}
return (0);
}

crediti : ExoduS