This document introduces sockets and socket programming in 3 sentences. It discusses the Endian concept of big and little Endian, provides examples of trivial socket functions like socket(), bind(), connect(), listen(), accept(), send(), and recv(). It also discusses addressing in IP and TCP, and how to create, bind, listen for, accept, and close sockets for client-server programming using TCP/IP sockets.

1. Compiled by: Jayakumar Balasubramanian Web: http://www.jwritings.com Email: [email_address]

2. Introduction Introduction to sockets The “Endian” concept Trivial functions Socket APIs Client server programming using sockets

3. Introduction

4. The “Endian” concept

5. Big-Endian

6. Little-Endian

7. Bit order transformation

8. Trivial functions

9. How does one talk to TCP/IP ?

10. Addressing in IP and TCP

11. Socket address

12. Socket APIs

13. API : Socket () Use to create a socket. fd = socket (family, type, protocol) Family : AF_INET, AF_UNIX, AF_NS Type : SOCK_STREAM, SOCK_DGRAM Protocol : Protocol for a given socket

14. API: bind() [The anchor]

15. API: bind() Attach a transport address to a socket. status = bind (fd, addressp, addrlen); fd : Socket descriptor addressp : Pointer to address structure addrlen : Size of address structure

16. API: connect()

17. API : connect() The connect function is used by a TCP client to establish a connection with a TCP server int fd, status, addrlen; struct sockaddr *addressp; status = connect (fd, addresssp, addrlen);

18. API: listen()

19. API: listen() listen() Prepares a socket to accept connections Must be used only on the server side of the application before any connection request is accepted. int fd, qlen, status; status = listen (fd, qlen); fd : Socket descriptor qlen : Length of the queue

20. API : accept()

21. API : accept() Used in the server side of the connection to accept incoming new connections When requests arrives it creates new socket, accepts the connection on the new socket int newfd, addrlen; struct sockaddr * addressp; newfd = accept (fd, addressp, & addrlen);

22. Connection establishment

23. API : send() Sends data over a communication channel Can be used in server and client side int fd, len, flags; char *buff; sent = send (fd, buff, len, flags); sent can be <= len

24. API : recv() R eceives data over a communication channel Can be used in server and client side int fd, len, flags, received; char *buff; received = recv (fd, buff, len, flags);

25. API: close() Close terminates both directions of data transfer, reading and writing. close( sockfd)

26. Web : http://www.jwritings.com Email: [email_address]