1 /*selcet服务器客户端模型: 2 1.客户端关闭后，服务器再向客户端发送信息，第一次会收到一个RST复位报文，第二次会收到SIGPIPE信号，导致服务器关闭，必须对这个信号进行处理： 3     1.在服务器对read返回值为0的情况进行处理，不向客户端发送信息 4     2.signal函数: signal(SIGPIPE, handle) 或者直接忽略signal(SIGPIPE, SIG_IGN) 5 */ 6 #include <stdio.h> 7 #include <stdlib.h> 8 #include <string.h> 9 #include <unistd.h>10 #include <errno.h>11 #include <sys/types.h>12 #include <sys/stat.h>13 #include <sys/socket.h>14 #include <arpa/inet.h>15 #include <signal.h>16 17 #define ERR_EXIT(m) 18     do { 19         perror(m);20         exit(EXIT_FAILURE);21     }while(0)//宏定义的错误处理22 23 static void do_service(int fd)24 {25     char recvbuf[1024] = {0};26     int ret;27     while(1)28     {29         memset(recvbuf, 0, sizeof recvbuf);30         ret = read(&rt, recvbuf, 1024);31         sleep(3);32         if(ret == 0)//关闭客户端时会导致ret == 033             printf("no message\n");34         else if(ret == -1)35         {36             if(errno == EINTR)37                 continue;38             return ;39         }   40         rio_writen(fd, recvbuf, 5);41     }42 }43 44 void handle(int signum)//SIGPIPE信号处理函数45 {46 printf("hello\n");47 }48 49 int main(int argc, const char *argv[])50 {51     if(signal(SIGPIPE, handle) == SIG_ERR)52         ERR_EXIT("signal");    53 54     int listenfd = socket(AF_INET, SOCK_STREAM, 0);//准备一个socketfd55     if(listenfd == -1 )56         ERR_EXIT("listen");57 58     int on = 1;59     if(setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) == -1)//setsockopt设置端口复用60     {61         close(listenfd);62         ERR_EXIT("setsockopt");63     }64 65     struct sockaddr_in seraddr;66     seraddr.sin_family = AF_INET;67     seraddr.sin_port = htons(8888);68     seraddr.sin_addr.s_addr = htonl(INADDR_ANY);69     socklen_t len = sizeof(seraddr);70     if(bind(listenfd, (struct sockaddr*)&seraddr, len) == -1)//监听socket端口，71     {72         close(listenfd);73         ERR_EXIT("bind");74     }75 //上述过程可以封装到起来，不用全部写入main76     if(listen(listenfd, 6) == -1)77     {78         close(listenfd);79         ERR_EXIT("listen");80     }81 82     struct sockaddr_in cliaddr;83     bzero(&cliaddr, sizeof(cliaddr));84     socklen_t cli_len = sizeof cliaddr;85 86     int clientfd;87     clientfd = accept(listenfd, (struct sockaddr*)&cliaddr, &cli_len);88 89     if(clientfd == -1)  90     {91         close(listenfd);92         ERR_EXIT("accept");93     }94     do_service(clientfd);95 96     close(clientfd);97     close(listenfd);98     return 0;99 }

 1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <string.h> 4 #include <errno.h> 5 #include <sys/types.h> 6 #include <sys/socket.h> 7 #include <netinet/in.h> 8 #include <arpa/inet.h> 9 #include <sys/select.h>10 11 #define ERR_EXIT(m) 12     do { 13         perror(m);14         exit(EXIT_FAILURE);15     }while(0)16 17 static void do_client(int fd)18 {19     char recvbuf[MAXLINE + 1] = {0};20     char sendbuf[MAXLINE + 1] = {0};21 22     fd_set reade, ready;//将ready集合放入select轮询，每次轮询前将reade赋值给ready23     FD_ZERO(&reade);//清空reade集合24     int fd_stdin = fileno(stdin);25     FD_SET(fd_stdin, &reade);26     FD_SET(fd, &reade);//将需要监听的文件描述符加入集合27     int fd_max = (fd_stdin > fd) ? fd_stdin : fd;//select轮询的最大文件描述符28 29     int ret;30     while(1)31     {32         ready = reade;33         ret = select( fd_max+1, &ready, NULL, NULL, NULL);//轮询，最后一个参数struct *timeval设置为NULL表示即时轮询（每次轮询间没时间间隔）34         if(ret < 0)35         {36             if(errno == EINTR)37                 continue;38             ERR_EXIT("select");39         }else if(ret ==  0)//监听的文件描述符状态未发生变化40         {41             continue;42         }43 44         if(FD_ISSET(fd_stdin, &ready))45         {46             if(fgets(sendbuf, sizeof(sendbuf), stdin) == NULL)47             {48                 shutdown(fd, SHUT_WR);//关闭fd的写端，close关闭时关闭整个描述符,若再写的话会导致write返回-1，系统会向客户端进程发送一个SIGPIPE信号，
               导致关闭，可以对信号进行signal(SIGPIPE, SIG_IGN)处理，也可将fd_stdin从监听队列删除49                // close(fd);50                 exit(EXIT_SUCCESS);51                 //break;
52                   }else53                 write(fd, sendbuf, strlen(sendbuf));           54         }55 56         if(FD_ISSET(fd, &ready))57         {58             int nread = read(fd, recvbuf, MAXLINE);59             if(nread < 0)60                 ERR_EXIT("read");61             if(nread == 0)//如果没接收到消息，打印关闭描述符，退出循环62             {63                 fprintf(stdout, "fd close\n");64                 break;65             }66             fprintf(stdout, "receive:%s\n", recvbuf);//注意要刷新67         }68         memset(recvbuf, 0, sizeof recvbuf);69         memset(sendbuf, 0, sizeof sendbuf);70     }71 }72 73 int main(int argc, const char *argv[])74 {75     int fd = socket(AF_INET, SOCK_STREAM, 0);76     if(fd < 0)77         ERR_EXIT("socket");78 79     struct sockaddr_in cliaddr;80     cliaddr.sin_family = AF_INET;81     cliaddr.sin_port = htons(8888);82     cliaddr.sin_addr.s_addr = inet_addr("127.0.0.1");83     socklen_t len = sizeof cliaddr;84 85     int ret ;86     if((ret = connect(fd, (struct sockaddr*)&cliaddr, len)) == -1)87     {88         close(fd);89         ERR_EXIT("connect");90     }91     do_client(fd);92     close(fd);93     printf("123\n");94     return 0;95 }

static void do_client(int fd){    char recvbuf[MAXLINE + 1] = {0};    char sendbuf[MAXLINE + 1] = {0};     struct pollfd pfd[2];//struct pollfd数组，里面存放监听描述符相关信息，供poll轮询使用     pfd[0].fd = fileno(stdin);     pfd[0].events = POLLIN;     pfd[1].fd = fd;     pfd[1].events = POLLIN;     int ret;    while(1)    {        ret = poll( pfd, 2, -1);//轮询，-1和select中的时间结构体指针为NULL的效果一样        if(ret < 0)        {            if(errno == EINTR)                continue;            ERR_EXIT("select");        }else if(ret ==  0)        {            continue;        }        if(pfd[0].revents & POLLIN)        {            if(fgets(sendbuf, sizeof(sendbuf), stdin) == NULL)            {                shutdown(fd, SHUT_WR);//关闭fd的写端                pfd[0].fd = -1;            }else                write(fd, sendbuf, strlen(sendbuf));                   }        if(pfd[1].revents & POLLIN)        {            int nread = read(fd, recvbuf, MAXLINE);            if(nread < 0)                ERR_EXIT("read");            if(nread == 0)//如果没接收到消息，打印关闭描述符，退出循环            {                fprintf(stdout, "fd close\n");                break;            }            fprintf(stdout, "receive:%s\n", recvbuf);//注意要刷新        }        memset(recvbuf, 0, sizeof recvbuf);        memset(sendbuf, 0, sizeof sendbuf);    }}

static void do_client(int fd){    char recvbuf[MAXLINE + 1] = {0};    char sendbuf[MAXLINE + 1] = {0};    int epollfd = epoll_create(2);//返回值也是一个文件描述符，记得要关闭，不然会导致fd耗尽    if(epollfd == -1)        ERR_EXIT("epoll_create");    struct epoll_event events[2];    struct epoll_event ev;    int ret;    ev.data.fd = fd;    ev.events = EPOLLIN;    ret = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);//注册fd    if(ret == -1)        ERR_EXIT("epoll_ctl");    ev.data.fd = fileno(stdin);    ev.events = EPOLLIN;    ret = epoll_ctl(epollfd, EPOLL_CTL_ADD, STDIN_FILENO, &ev);//注册fd    if(ret == -1)        ERR_EXIT("epoll_ctl");    int nready;    while(1)    {        nready = epoll_wait(epollfd, events, 2, -1);        if(nready < 0)        {            if(errno == EINTR)                continue;            ERR_EXIT("select");        }else if(nready  ==  0)        {            continue;        }        int i;        for(i = 0; i < nready; i++)            {            int nfd = events[i].data.fd;            if(nfd == STDIN_FILENO)            {                if(fgets(sendbuf, 1024, stdin) == NULL)                {                    shutdown(fd, SHUT_WR);                    struct epoll_event ee;                    ee.data.fd = STDIN_FILENO;                    if(epoll_ctl(epollfd, EPOLL_CTL_DEL, STDIN_FILENO, &ee) == -1)                        ERR_EXIT("epoll_ctl");                }else                    write(fd, sendbuf, strlen(sendbuf));            }            if(nfd == fd)            {                int ret = read(fd, recvbuf, 1024);                if(ret == -1)                    ERR_EXIT("readline");                else if(ret == -1)                 {                    close(fd);                    printf("fd close\n");                    exit(EXIT_SUCCESS);                }                printf("recv data :%s\n", recvbuf);            }        }    }    memset(recvbuf, 0, sizeof recvbuf);    memset(sendbuf, 0, sizeof sendbuf);}