The example programs from this chapter can be compiled with any modern C compiler. We recommend MinGW on Windows and GCC on Linux and macOS. See Appendix B, Setting Up Your C Compiler on Windows, Appendix C, Setting Up Your C Compiler on Linux, and Appendix D, Setting Up Your C Compiler on macOS, for compiler setup.

The code for this book can be found at https://github.com/codeplea/Hands-On-Network-Programming-with-C.

From the command line, you can download the code for this chapter with the following command:

git clone https://github.com/codeplea/Hands-On-Network-Programming-with-C
cd Hands-On-Network-Programming-with-C/chap08

Each example program in this chapter runs on Windows, Linux, and macOS. When compiling on Windows, each example program requires linking with the Winsock library. This can be accomplished by passing the -lws2_32 option to gcc.

We provide the exact commands needed to compile each example as they are introduced.

All of the example programs in this chapter require the same header files and C macros that we developed in Chapter 2, Getting to Grips with Socket APIs. For brevity, we put these statements in a separate header file, chap08.h, which we can include in each program. For a detailed explanation of these statements, please refer to Chapter 2, Getting to Grips with Socket APIs.

The first part of chap08.h includes the needed networking headers for each platform. The code for this is as follows:

/*chap08.h*/

#if defined(_WIN32)
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0600
#endif
#include <winsock2.h>
#include <ws2tcpip.h>
#pragma comment(lib, "ws2_32.lib")

#else
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#include <errno.h>

#endif

We also define some macros to make writing portable code easier, and we'll include the additional headers that our programs require:

/*chap08.h continued*/

#if defined(_WIN32)
#define ISVALIDSOCKET(s) ((s) != INVALID_SOCKET)
#define CLOSESOCKET(s) closesocket(s)
#define GETSOCKETERRNO() (WSAGetLastError())

#else
#define ISVALIDSOCKET(s) ((s) >= 0)
#define CLOSESOCKET(s) close(s)
#define SOCKET int
#define GETSOCKETERRNO() (errno)
#endif


#include <stdio.h>
#include <stdlib.h>
#include <string.h>

That concludes chap08.h.