Sockets, Shellcode, Porting, and Coding: Reverse Engineering Exploits and Tool Coding for Security Professionals

16 /* print out if compiled on Win32 */

17 printf("WIN32\n" );

18 #else

19 printf("?\n");

20 #endif

21

22

return(0);

23 }

Example Execution

Let’s look at the Win32 and UNIX output.

Win32 Output

C:\>ifdef1.exe

WIN32

UNIX Output

obsd32# gcc –o ifdef1 ifdef1.c

obsd32# ./ifdef1

OpenBSD

Analysis

■

At line 12, an ifdef pre-compiler directive is used to determine if the operating

system that the program is being compiled on is OpenBSD. If it is, the code at

line 14 will be compiled, not the code at line 17.

■

At line 15, an ifdef pre-compiler directive is used to determine if the operating

system that the program is being compiled on is a Win32 platform. If it is, the

code at line 17 will be compiled, not the code at line 14.

■

At lines 14 and 16, the printf() function is called ...