Technical requirements

The example programs in 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 in this book's GitHub repository: 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/chap04

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

We provide the exact commands that are 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, chap04.h, which we can include in each program. For an explanation of these statements, please refer to Chapter 2, Getting to Grips with Socket APIs.

The content of chap04.h is shown in the following code:

#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


#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 <string.h>