1. #include <stdio.h>
    2. #include <sys/types.h>
    3. #include <sys/socket.h>
    4. #include <errno.h>
    5. #include <string.h>
    6. #include <stdlib.h>
    7. #include <unistd.h>
    8. #include <netinet/in.h>
    9. #include <ctype.h>
    10. #include <poll.h> //poll头文件
    12. #define MAXSIZE 1024
    13. #define IP_ADDR "127.0.0.1"
    14. #define IP_PORT 8888
    16. int main()
    17. {
    18.     int i_listenfd, i_connfd;
    19.     struct sockaddr_in st_sersock;
    20.     char msg[MAXSIZE];
    21.     int nrecvSize = 0;
    23.     int index = 0;                //记录fd数组中最大fd对应的下标
    24.     struct pollfd pofds[MAXSIZE]; //结构体数组
    26.     for (n : pofds) //将所有数组中的fd设为-1，方便以后填充
    27.     {
    28.         n.fd = -1;
    29.     }
    31.     if ((i_listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) //建立socket套接字
    32.     {
    33.         printf("socket Error: %s (errno: %d)\n", strerror(errno), errno);
    34.         exit(0);
    35.     }
    37.     memset(&st_sersock, 0, sizeof(st_sersock));
    38.     st_sersock.sin_family = AF_INET;                //IPv4协议
    39.     st_sersock.sin_addr.s_addr = htonl(INADDR_ANY); //INADDR_ANY转换过来就是0.0.0.0，泛指本机的意思，也就是表示本机的所有IP，因为有些机子不止一块网卡，多网卡的情况下，这个就表示所有网卡ip地址的意思。
    40.     st_sersock.sin_port = htons(IP_PORT);
    42.     if (bind(i_listenfd, (struct sockaddr *)&st_sersock, sizeof(st_sersock)) < 0) //将套接字绑定IP和端口用于监听
    43.     {
    44.         printf("bind Error: %s (errno: %d)\n", strerror(errno), errno);
    45.         exit(0);
    46.     }
    48.     if (listen(i_listenfd, 20) < 0) //设定可同时排队的客户端最大连接个数
    49.     {
    50.         printf("listen Error: %s (errno: %d)\n", strerror(errno), errno);
    51.         exit(0);
    52.     }
    53.     printf("listen fd: %d\n", i_listenfd);
    55.     pofds[index].fd = i_listenfd; //先赋值
    56.     pofds[index].events = POLLIN;
    57.     printf("======waiting for client's request======\n");
    58.     //准备接受客户端连接
    59.     while (1)
    60.     {
    61.         int nCount = poll(pofds, index + 1, -1); //阻塞监听
    62.         printf("----------poll监听到可读事件计数:%d\n", nCount);
    64.         for (int i = 0; i < MAXSIZE; i++)
    65.         {
    66.             if (nCount == 0)
    67.             {
    68.                 break;
    69.             }
    70.             if (!(pofds[i].revents & POLLIN))
    71.             {
    72.                 continue; //不在监听事件中则跳过
    73.             }
    74.             printf("----------即将处理监听到的 pofds[%d]: %d\n", i, pofds[i].fd);
    75.             nCount--;                      //每处理一次就自减1
    76.             if (pofds[i].fd == i_listenfd) //监听到有客户端连接
    77.             {
    78.                 if ((i_connfd = accept(i_listenfd, (struct sockaddr *)NULL, NULL)) < 0) //阻塞等待客户端连接
    79.                 {
    80.                     printf("accept Error: %s (errno: %d)\n", strerror(errno), errno);
    81.                     //    continue;
    82.                 }
    83.                 else
    84.                 {
    85.                     printf("Client[%d], welcome!\n", i_connfd);
    86.                 }
    88.                 for (int n = 0; n < MAXSIZE; n++)
    89.                 {
    90.                     if (pofds[n].fd == -1) //将新客户端fd加入数组中
    91.                     {
    92.                         pofds[n].fd = i_connfd;
    93.                         pofds[n].events = POLLIN;
    94.                         index < n ? index = n : true;
    95.                         printf("将新客户端fd加入数组中. fd:%d, index:%d\n", pofds[n].fd, index);
    96.                         break;
    97.                     }
    98.                 }
    99.             }
    100.             else //监听到已连接的客户端发来的数据
    101.             {
    102.                 //接受客户端发来的消息并作处理(小写转大写)后回写给客户端
    103.                 memset(msg, 0, sizeof(msg));
    104.                 if ((nrecvSize = read(pofds[i].fd, msg, MAXSIZE)) < 0)
    105.                 {
    106.                     printf("accept Error: %s (errno: %d)\n", strerror(errno), errno);
    107.                     continue;
    108.                 }
    109.                 else if (nrecvSize == 0) //read返回0代表对方已close断开连接。
    110.                 {
    111.                     printf("client has disconnected!\n");
    112.                     if (index == i) //如果是最大的下标的客户端退出，则index-1
    113.                     {
    114.                         index--;
    115.                     }
    116.                     pofds[i].fd = -1; //清除数组中相应位置
    117.                     close(pofds[i].fd);
    119.                     continue;
    120.                 }
    121.                 else
    122.                 {
    123.                     printf("recvMsg:%s", msg);
    124.                     for (int i = 0; msg[i] != '\0'; i++)
    125.                     {
    126.                         msg[i] = toupper(msg[i]);
    127.                     }
    128.                     if (write(pofds[i].fd, msg, strlen(msg) + 1) < 0)
    129.                     {
    130.                         printf("accept Error: %s (errno: %d)\n", strerror(errno), errno);
    131.                     }
    132.                 }
    133.             }
    134.         }
    135.     } //while
    136.     close(i_listenfd);
    138.     return 0;
    139. }