How do C++ functions establish and manage server-side sockets in network programming?

C provides establishment and management functions for server-side sockets, including creating sockets through socket(), binding addresses and ports through bind(), and listening for connections through listen(). Once established, you can use accept() to accept the connection, send()/recv() to send/receive data, and finally close the socket with close().

How C function creates and manages server-side sockets in network programming

In network programming, server-side sockets Words are the key to communication between processes and clients. C provides a rich set of functions for developing network applications that can be used to establish and manage sockets on the server side.

Establishing a server-side socket

To establish a server-side socket, you need to call the following steps:

1. Using The socket() function creates a socket.
2. Use the bind() function to bind the socket to an address and port number.
3. Use the listen() function to put the socket in the listening state.

#include <iostream>
#include <sys/socket.h>
#include <netinet/in.h>

int main() {
  // 创建套接字
  int server_fd = socket(AF_INET, SOCK_STREAM, 0);
  if (server_fd == -1) {
    std::cerr << "socket() failed" << std::endl;
    return -1;
  }

  // 绑定套接字
  struct sockaddr_in server_addr;
  server_addr.sin_family = AF_INET;
  server_addr.sin_port = htons(8080);
  server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
  int bind_result = bind(server_fd, (struct sockaddr *) &server_addr, sizeof(server_addr));
  if (bind_result == -1) {
    std::cerr << "bind() failed" << std::endl;
    return -1;
  }

  // 监听套接字
  int listen_result = listen(server_fd, 5);
  if (listen_result == -1) {
    std::cerr << "listen() failed" << std::endl;
    return -1;
  }

  // ... // 处理客户端连接的代码
}

Manage server-side sockets

Once the socket is established, it can be used to communicate with the client. Here are the main ways on how to manage server-side sockets:

• Use the accept() function to accept connections from clients.
• Use the send() and recv() functions to send and receive data.
• Use the close() function to close the socket.

Practical case: TCP server

The following is a simple C TCP server example that demonstrates how to establish and manage server-side sockets :

#include <iostream>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>  // for close()

int main() {
  // 创建套接字
  int server_fd = socket(AF_INET, SOCK_STREAM, 0);
  if (server_fd == -1) {
    std::cerr << "socket() failed" << std::endl;
    return -1;
  }

  // 绑定套接字
  struct sockaddr_in server_addr;
  server_addr.sin_family = AF_INET;
  server_addr.sin_port = htons(8080);
  server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
  int bind_result = bind(server_fd, (struct sockaddr *) &server_addr, sizeof(server_addr));
  if (bind_result == -1) {
    std::cerr << "bind() failed" << std::endl;
    return -1;
  }

  // 监听套接字
  int listen_result = listen(server_fd, 5);
  if (listen_result == -1) {
    std::cerr << "listen() failed" << std::endl;
    return -1;
  }

  // 接受客户端连接
  int client_fd;
  while ((client_fd = accept(server_fd, (struct sockaddr *) NULL, NULL)) != -1) {
    // 为客户端创建子进程进行处理
    if (fork() == 0) {
      // ... // 处理客户端连接的代码
      close(client_fd);
      exit(0);
    }
  }

  // 关闭套接字
  close(server_fd);

  return 0;
}

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