setsockopt函数服务端怎么使用例子c语言

下面是一个简单的例子，展示了如何在服务端使用setsockopt函数：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define PORT 8080
#define MAX_CLIENTS 10

int main(int argc, char const *argv[]) {

    int server_fd, new_socket, valread;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);
    char buffer[1024] = {0};
    char* hello = "Hello from server";

    // Creating socket file descriptor
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // Attaching socket to the port 8080
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
        perror("setsockopt");
        exit(EXIT_FAILURE);
    }
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    // Binding socket to the address and port
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // Listening for incoming connections
    if (listen(server_fd, MAX_CLIENTS) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }

    // Accepting incoming connections
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    }

    // Reading data from the client
    valread = read(new_socket, buffer, 1024);
    printf("%s\n", buffer);

    // Sending data to the client
    send(new_socket, hello, strlen(hello), 0);
    printf("Hello message sent\n");

    return 0;
}

在这个例子中，我们使用了setsockopt函数来设置socket的选项。我们设置了SO_REUSEADDR和SO_REUSEPORT选项，这允许我们在同一端口上重新启动服务器，而无需等待几分钟以使先前的套接字关闭。这是一个非常有用的选项，因为在调试和开发时，我们经常需要重新启动服务器。

此外，在这个例子中，我们还使用了bind、listen和accept函数来绑定、监听和接受客户端的连接。我们还使用了read和send函数来读取和发送数据。