// 简单的单线程TCP服务器
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>                
#include <arpa/inet.h>     
                                                
#define PORT 8888
#define BUFFER_SIZE 1024
                                                                                                 
int main() {
    int server_fd, client_fd;
    struct sockaddr_in server_addr, client_addr; 
    socklen_t addr_len = sizeof(client_addr);                                                    
    char buffer[BUFFER_SIZE];
    int opt = -1;                  
                     
    // 创建socket
    server_fd = socket(AF_INET, SOCK_STREAM, 0); 
    if (server_fd < 0) {                
        perror("socket创建失败");                                                                
        return 1;                           
    }    
                                                
    // 设置SO_REUSEADDR选项 - 允许地址重用
/*    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
        perror("setsockopt(SO_REUSEADDR)失败");                                                  
        close(server_fd);     
        return -1;
    }                                  
*/                                                                                               
    // 设置端口重用选项
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEPORT, &opt, sizeof(opt)) < 0) {
        perror("setsockopt(SO_REUSEPORT)失败");
        close(server_fd);
        return 1;
    }
    // 配置服务器地址                                                                                                                                                              19:27:25 [1/86]
    server_addr.sin_family = AF_INET;                                                                                                                                                             
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(PORT);
     
    // 绑定
    if (bind(server_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0) {
        perror("绑定失败");
        return 1;
    }
     
    // 监听
    if (listen(server_fd, 5) < 0) {
        perror("监听失败");
        return 1;
    }
     
    printf("TCP服务器启动，监听端口 %d\n", PORT);
     
    while (1) {
        // 接受连接
        client_fd = accept(server_fd, (struct sockaddr*)&client_addr, &addr_len);
        if (client_fd < 0) {
            perror("接受连接失败");
            continue;
        }
         
        printf("客户端已连接: %s:%d\n", 
               inet_ntoa(client_addr.sin_addr),  
               ntohs(client_addr.sin_port));
         
        // 处理客户端
        while (1) {
            memset(buffer, 0, BUFFER_SIZE);
            int n = recv(client_fd, buffer, BUFFER_SIZE - 1, 0);
            if (n <= 0) break;
             
            printf("收到: %s", buffer);
            send(client_fd, buffer, strlen(buffer), 0);
        }
         
        printf("客户端断开连接\n");
        close(client_fd);
    }
     
    close(server_fd);
    return 0;
}