C Language Socket Programming Video Tutorial20

In this video tutorial, we will learn about socket programming in C language. Socket programming is a way of establishing communication between two or more computers over a network. It involves creating a socket, binding it to a specific port, and then listening for incoming connections. Once a connection is established, data can be exchanged between the two computers.

We will start by discussing the basics of socket programming, including the different types of sockets and the different protocols that can be used. We will then show you how to create a simple client-server application using sockets. This application will allow you to send and receive messages between two computers.

By the end of this tutorial, you will have a basic understanding of socket programming in C language. You will be able to create simple client-server applications and use sockets to communicate between computers over a network.## Prerequisites
* A basic understanding of C language
* A text editor or IDE
* A compiler
## Getting Started
To get started, we need to create a new project in our text editor or IDE. We will then need to include the following header files in our program:```c
#include
#include
#include
#include
#include
```
These header files contain the declarations for the socket programming functions that we will be using in our program.
Next, we need to create a socket. A socket is a communication endpoint that is used to send and receive data. We can create a socket using the `socket()` function. The `socket()` function takes three arguments: the domain of the socket, the type of the socket, and the protocol of the socket.
The domain of the socket specifies the network that the socket will be used on. The most common domains are `AF_INET` for IPv4 addresses and `AF_INET6` for IPv6 addresses.
The type of the socket specifies the type of communication that the socket will be used for. The most common types of sockets are `SOCK_STREAM` for TCP connections and `SOCK_DGRAM` for UDP connections.
The protocol of the socket specifies the protocol that will be used to communicate with the socket. The most common protocols are `IPPROTO_TCP` for TCP connections and `IPPROTO_UDP` for UDP connections.
Here is an example of how to create a socket:```c
int sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (sockfd == -1) {
perror("socket");
exit(EXIT_FAILURE);
}
```
## Binding a Socket to a Port
Once we have created a socket, we need to bind it to a specific port. A port is a number that is used to identify a specific application on a computer. When a client connects to a server, it specifies the port number of the server that it wants to connect to.
We can bind a socket to a port using the `bind()` function. The `bind()` function takes two arguments: the socket that we want to bind, and the address of the port that we want to bind the socket to.
Here is an example of how to bind a socket to a port:```c
struct sockaddr_in sockaddr;
sockaddr.sin_family = AF_INET;
sockaddr.sin_port = htons(8080);
sockaddr.sin_addr.s_addr = htonl(INADDR_ANY);
if (bind(sockfd, (struct sockaddr *)&sockaddr, sizeof(sockaddr)) == -1) {
perror("bind");
exit(EXIT_FAILURE);
}
```
## Listening for Incoming Connections
Once we have bound a socket to a port, we need to listen for incoming connections. We can do this using the `listen()` function. The `listen()` function takes two arguments: the socket that we want to listen on, and the maximum number of connections that the socket can accept.
Here is an example of how to listen for incoming connections:```c
if (listen(sockfd, 5) == -1) {
perror("listen");
exit(EXIT_FAILURE);
}
```
## Accepting a Connection
When a client connects to our server, the `accept()` function will return a new socket that is connected to the client. We can use this new socket to send and receive data from the client.
Here is an example of how to accept a connection:```c
int newsockfd = accept(sockfd, NULL, NULL);
if (newsockfd == -1) {
perror("accept");
exit(EXIT_FAILURE);
}
```
## Sending and Receiving Data
Once we have accepted a connection, we can send and receive data from the client using the `send()` and `recv()` functions. The `send()` function takes three arguments: the socket that we want to send data on, the data that we want to send, and the length of the data. The `recv()` function takes three arguments: the socket that we want to receive data from, the buffer that we want to store the data in, and the length of the buffer.
Here is an example of how to send data to a client:```c
char buffer[] = "Hello, world!";
if (send(newsockfd, buffer, sizeof(buffer)) == -1) {
perror("send");
exit(EXIT_FAILURE);
}
```
Here is an example of how to receive data from a client:```c
char buffer[1024];
if (recv(newsockfd, buffer, sizeof(buffer), 0) == -1) {
perror("recv");
exit(EXIT_FAILURE);
}
```
## Closing a Socket
When we are finished using a socket, we need to close it using the `close()` function. The `close()` function takes one argument: the socket that we want to close.
Here is an example of how to close a socket:```c
close(sockfd);
```