Book Image

Hands-On Network Programming with C

By : Lewis Van Winkle
Book Image

Hands-On Network Programming with C

By: Lewis Van Winkle

Overview of this book

Network programming enables processes to communicate with each other over a computer network, but it is a complex task that requires programming with multiple libraries and protocols. With its support for third-party libraries and structured documentation, C is an ideal language to write network programs. Complete with step-by-step explanations of essential concepts and practical examples, this C network programming book begins with the fundamentals of Internet Protocol, TCP, and UDP. You’ll explore client-server and peer-to-peer models for information sharing and connectivity with remote computers. The book will also cover HTTP and HTTPS for communicating between your browser and website, and delve into hostname resolution with DNS, which is crucial to the functioning of the modern web. As you advance, you’ll gain insights into asynchronous socket programming and streams, and explore debugging and error handling. Finally, you’ll study network monitoring and implement security best practices. By the end of this book, you’ll have experience of working with client-server applications and be able to implement new network programs in C. The code in this book is compatible with the older C99 version as well as the latest C18 and C++17 standards. You’ll work with robust, reliable, and secure code that is portable across operating systems, including Winsock sockets for Windows and POSIX sockets for Linux and macOS.
Table of Contents (26 chapters)
Title Page
About Packt

Multiplexing with a large number of sockets

We've used select() in this book to multiplex between open sockets. The select() function is great because it is available on many platforms. However, if you have a large number of open sockets, you can quickly run into the limitations of select().

There is a maximum number of sockets you can pass to select(). This number is available through the FD_SETSIZE macro.

This chapter's code repository includes a program, setsize.c, which prints the value of FD_SETSIZE.

The following screenshot shows this program being compiled and run on Windows 10:

The preceding screenshot shows FD_SETSIZE is 64 on this system. Although Windows's default size for FD_SETSIZE is quite low, it is common to see higher values on other systems. The default value of FD_SETSIZE on Linux is 1024.

On Windows, it is possible to increase FD_SETSIZE easily. You only need to define FD_SETSIZE yourself before including the winsock2.h header. For example, the following code increases FD_SETSIZE...