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

The format of an email

If we make an analogy to physical mail, the SMTP commands MAIL FROM and RCPT TO address the envelope. Those commands give the SMTP server information on how the mail is to be delivered. In this analogy, the DATA command would be the letter inside the envelope. As it's common to address a physical letter inside an envelope, it's also common to repeat the delivery information in the email, even though it was already sent to the SMTP server through the MAIL and RCPT commands.

A simple email may look like the following:

From: Alice Doe <[email protected]>
To: Bob Doe <[email protected]>
Subject: Re: The Cake
Date: Fri, 03 May 2019 02:31:20 +0000

Hi Bob,

Do NOT forget to bring the cake!


The entire email is transmitted to an SMTP server following the DATA command. A single period on an otherwise blank line is transmitted to indicate the end of the email. If the email contains any line beginning with a period, the SMTP client should replace it with two...