Socket Programming(1)

1. What is Socket Programming?

• Socket Programming is an interface between the application layer and the transport layer (TCP/UDP).
• It is a programming interface provided by the operation system (OS) to enable communication between networked processes.
• It allows developers to implement client-server communication models over networks.

2. Socket Key Concepts

• A socket acts as an endpoint for sending and receiving data across a network.
• The OS provides socket API, which allows applications to interact with lower-layer protocols like TCP or UDP.
• Socket programming is essential for building networked applications, such as servers, chat programs, and file transfer tools.

3. Common Operations in Socket Programming

Function	Description
socket()	Create a new socket
bind()	Bind the socket to an IP address and port
listen()	Listen for incoming connections (server-side)
accept()	Accept a connection request
connect()	Connect to a remote server (client-side)
send() / recv()	Send or receive data
close()	Close the socket

4. Create Socket

Use the socket() function to create a new socket.

int socket(int domain, int type, int protocol);

Parameter	Description
domain	Address family (e.g., IPv4: AF_INET, IPv6: AF_INET6)
type	Communication type (e.g., TCP: SOCK_STREAM, UDP: SOCK_DGRAM)
protocol	Usually set to 0 to automatically select the appropriate protocol

5. Bind the Socket

Use the bind() function to associate the socket with a specific IP address and port number.
bind() assigns a local address (IP + port) to the socket so it can receive incoming connections or data.

int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);

Parameter	Description
sockfd	The socket file descriptor returned by socket()
addr	A pointer to a sockaddr structure containing the desired IP address and port
addrlen	The size of the sockaddr structure

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