linux C语言循环监听

#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define PORT 8080
#define MAX_CLIENTS 10

int main() {
    int server_fd, new_socket, max_sd, activity, valread, sd;
    int client_sockets[MAX_CLIENTS] = {0};
    struct sockaddr_in address;
    int addrlen = sizeof(address);
    char buffer[1024] = {0};

    // 创建socket文件描述符
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置socket选项
    int opt = 1;
    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);

    // 绑定
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // 监听
    if (listen(server_fd, 3) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }

    fd_set readfds;
    while (1) {
        FD_ZERO(&readfds);
        FD_SET(server_fd, &readfds);
        max_sd = server_fd;

        // 添加子socket到集合
        for (int i = 0; i < MAX_CLIENTS; i++) {
            sd = client_sockets[i];
            if (sd > 0)
                FD_SET(sd, &readfds);
            if (sd > max_sd)
                max_sd = sd;
        }

        // 等待活动
        activity = select(max_sd + 1, &readfds, NULL, NULL, NULL);
        if ((activity < 0) && (errno != EINTR)) {
            printf("select error");
        }

        // 如果有新的连接
        if (FD_ISSET(server_fd, &readfds)) {
            if ((new_socket = accept(server_fd, (struct sockaddr *)&address,
                                     (socklen_t*)&addrlen)) < 0) {
                perror("accept");
                exit(EXIT_FAILURE);
            }

            // 添加新的socket到数组
            for (int i = 0; i < MAX_CLIENTS; i++) {
                if (client_sockets[i] == 0) {
                    client_sockets[i] = new_socket;
                    printf("Adding to list of sockets as %d\n", i);
                    break;
                }
            }
        }

        // 处理客户端数据
        for (int i = 0; i < MAX_CLIENTS; i++) {
            sd = client_sockets[i];
            if (FD_ISSET(sd, &readfds)) {
                if ((valread = read(sd, buffer, 1024)) == 0) {
                    // 客户端断开连接
                    getpeername(sd, (struct sockaddr*)&address, \
                                (socklen_t*)&addrlen);
                    printf("Host disconnected, ip %s, port %d\n", \
                           inet_ntoa(address.sin_addr), ntohs(address.sin_port));
                    close(sd);
                    client_sockets[i] = 0;
                } else {
                    // 处理数据
                    buffer[valread] = '\0';
                    printf("Received: %s\n", buffer);
                }
            }
        }
    }

    return 0;
}