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

Multiple connections buffering

One important hurdle to overcome, when implementing any server software, is accepting and parsing requests from multiple clients simultaneously.

Consider a client that sends only the beginning of an HTTP request, followed by a delay, and then the remainder of the HTTP request. In this case, we cannot respond to that client until the entire HTTP request is received. However, at the same time, we do not wish to delay servicing other connected clients while waiting. For this reason, we need to buffer up received data for each client separately. Only once we've received an entire HTTP request from a client can we respond to that client.

It is useful to define a C struct to store information on each connected client. Our program uses the following:

/*web_server.c except*/

#define MAX_REQUEST_SIZE 2047

struct client_info {
    socklen_t address_length;
    struct sockaddr_storage address;
    SOCKET socket;
    char request[MAX_REQUEST_SIZE + 1];
    int received...