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

HTTPS and OpenSSL summary

We begin with a quick review of the HTTPS protocol, as covered in Chapter 9, Loading Secure Web Pages with HTTPS and OpenSSL. However, we do recommend that you work through Chapter 9Loading Secure Web Pages with HTTPS and OpenSSL, before beginning this chapter.

HTTPS uses TLS to add security to HTTP. You will recall from Chapter 6, Building a Simple Web Client, and Chapter 7, Building a Simple Web Server, that HTTP is a text-based protocol that works over TCP on port 80. The TLS protocol can be used to add security to any TCP-based protocol. Specifically, TLS is used to provide security for HTTPS. So in a nutshell, HTTPS is simply HTTP with TLS. The default HTTPS port is 443.

OpenSSL is a popular open source library that provides functionality for TLS/SSL and HTTPS. We use it in this book to provide the methods needed to implement HTTPS clients and servers.

Generally, HTTPS connections are first made using TCP sockets. Once the TCP connection is established, OpenSSL...