Linux Network Programming Video Tutorial317

Linux network programming is a powerful tool that allows programmers to create applications that can communicate with other computers over a network. This can be useful for a variety of purposes, such as:

Creating web servers
Developing chat applications
Writing distributed systems
Building network monitoring tools

In this tutorial, we will cover the basics of Linux network programming, including how to create sockets, send and receive data, and handle network errors. We will also provide a number of code examples to help you get started with Linux network programming.

Creating Sockets

The first step in network programming is to create a socket. A socket is a software endpoint through which data can be sent and received. There are two main types of sockets: stream sockets and datagram sockets.
Stream sockets are used for reliable, ordered data delivery. They are typically used for applications that need to send large amounts of data, such as web servers and file transfer applications.
Datagram sockets are used for unreliable, unordered data delivery. They are typically used for applications that need to send small amounts of data, such as chat applications and network monitoring tools.

To create a socket, you can use the socket() system call. The socket() system call takes three arguments:

domain: The address family of the socket. This can be either AF_INET (for IPv4 addresses) or AF_INET6 (for IPv6 addresses).
type: The type of socket to create. This can be either SOCK_STREAM (for stream sockets) or SOCK_DGRAM (for datagram sockets).
protocol: The protocol to use for the socket. This can be either 0 (for the default protocol) or a specific protocol number, such as IPPROTO_TCP (for TCP) or IPPROTO_UDP (for UDP).

The following code example shows how to create a stream socket:
```c
int sockfd;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == -1) {
perror("socket() failed");
exit(1);
}
```

The sockfd variable now contains a file descriptor that can be used to identify the socket.

Binding Sockets

Once you have created a socket, you need to bind it to a specific network address and port. This is done using the bind() system call. The bind() system call takes two arguments:

sockfd: The file descriptor of the socket to bind.
addr: A pointer to a sockaddr structure that contains the address and port to bind to.

The following code example shows how to bind a socket to the IP address 127.0.0.1 and port 8080:
```c
struct sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_port = htons(8080);
addr.sin_addr.s_addr = inet_addr("127.0.0.1");
if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
perror("bind() failed");
exit(1);
}
```

The bind() system call will return 0 if the socket was successfully bound to the specified address and port. Otherwise, it will return -1 and set errno to indicate the error.

Listening for Connections

If you are creating a server application, you will need to listen for incoming connections on a specific port. This is done using the listen() system call. The listen() system call takes two arguments:

sockfd: The file descriptor of the socket to listen on.
backlog: The maximum number of connections that the socket can queue.

The following code example shows how to listen for incoming connections on port 8080:
```c
if (listen(sockfd, 5) == -1) {
perror("listen() failed");
exit(1);
}
```

The listen() system call will return 0 if the socket was successfully put into listen mode. Otherwise, it will return -1 and set errno to indicate the error.

Accepting Connections

When a client connects to the server, the server will need to accept the connection. This is done using the accept() system call. The accept() system call takes two arguments:

sockfd: The file descriptor of the socket to accept the connection on.
addr: A pointer to a sockaddr structure that will be filled with the address of the client that connected.

The following code example shows how to accept a connection on a socket:
```c
int newsockfd;
newsockfd = accept(sockfd, (struct sockaddr *)&addr, &addrlen);
if (newsockfd == -1) {
perror("accept() failed");
exit(1);
}
```

2024-11-05

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