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

Chapter 2, Getting to Grips with Socket APIs

  1. What is a socket?

A socket is an abstraction that represents one endpoint of a communication link between systems.

  1. What is a connectionless protocol? What is a connection-oriented protocol?

A connection-oriented protocol sends data packets in the context of a larger stream of data. A connectionless protocol sends each packet of data independently of any before or after it.

  1. Is UDP a connectionless or connection-oriented protocol?

UDP is considered a connectionless protocol. Each message is sent independently of any before or after it.

  1. Is TCP a connectionless or connection-oriented protocol?

TCP is considered a connection-oriented protocol. Data is sent and received in order as a stream.

  1. What types of applications generally benefit from using the UDP protocol?

UDP applications benefit from better real-time performance while sacrificing reliability. They are also able to take advantage of IP multicasting.

  1. What types of applications generally benefit from using the TCP protocol?

Applications that need a reliable stream of data transfer benefit from the TCP protocol.

  1. Does TCP guarantee that data will be transmitted successfully?

TCP makes some guarantees about reliability, but nothing can truly guarantee that data is transmitted successfully. For example, if someone unplugs your modem, no protocol can overcome that.

  1. What are some of the main differences between Berkeley sockets and Winsock sockets?

The header files are different. Sockets themselves are represented as signed versus unsigned ints. When socket() or accept() calls fail, the return values are different. Berkeley sockets are also standard file descriptions. This isn't always true with Winsock. Error codes are different and retrieved in a different way. There are additional differences, but these are the main ones that affect our programs.

  1. What does the bind() function do? 

The bind() function associates a socket with a particular local network address and port number. Its usage is almost always required for the server, and it's usually not required for the client.

  1. What does the accept() function do?

The accept() function will block until a new TCP client has connected. It then returns the socket for this new connection.

  1. In a TCP connection, does the client or the server send application data first?

Either the client or the server can send data first. They can even send data simultaneously. In practice, many client-server protocols (such as HTTP) work by having the client send a request first and then having the server send a response.