用epoll提供telnet服务的代码

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这是之前写的用epoll提供telnet服务的代码。

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <sys/epoll.h>
#include <stdlib.h>
#include <netinet/tcp.h> 
#include <ctype.h>
#include <assert.h>
#define MAX_EVENTS 10
#define PORT 9999
//从buf中得到命令
void _get_command(char *buf, char *cmd) {
    int i = 0;
    int j = 0;
    while (!isalpha(buf[i]))
        i++;
    while (buf[i] != '\0' && buf[i] != ' ' && buf[i] != '\r' && buf[i] != '\n') {
        cmd[j++] = buf[i];
        i++;
    }
    cmd[j] = '\0';
}
// 返回成功发送的字节数
int Send(int sock, void *buffer, int size){

    int nsend = 0, total = 0;
    int err;
    if(NULL == buffer || 0 == size) {
        return 0;
    }
    while(size > 0) {
        nsend = write(sock, (char*)buffer + total, size);
        if(nsend == -1) {
            err = errno;
            if(EINTR == err) {
                printf("send data to socket[%d], error is %s[%d]\n", 
                            sock, strerror(err), err);
            } else {
                printf("Fail to send data to socket[%d], error is %s[%d]", 
                            sock, strerror(err), err);
                return -1;    
            }
        } else {
            total += nsend;
            size -= nsend;
        }
    }
    return total;
}
//处理重置命令
void process_reset(int sock){
    char mess[] = "reset successful\r\n";
    Send(sock, mess, strlen(mess));
    return;
}
//处理错误命令
void process_error(int sock) {
    char error[] = "ERROR\r\n";
    Send(sock, error, strlen(error));
    return;
}
void process_stats(int sock){
    char mess[] = "stats successful\r\n";
    Send(sock, mess, strlen(mess));
    return;
}

//处理退出命令
void process_quit(int sock) {
    close(sock);
}

int process_command(int sock, char *buf) {
    assert(buf != NULL);

    /*char cmd[BUFSIZ];    _get_command(buf, cmd);        printf("command: %s\n", cmd);    if (strcmp("stats",cmd) == 0) {        process_stats(sock);    } else if (strcmp("reset", cmd) == 0) {        process_reset(sock);    } else if (strcmp("quit", cmd) == 0){        process_quit(sock);    } else {        process_error(sock);    }*/
    _get_command(buf, cmd);    
    printf("command: %s\n", cmd);

    if (strcmp("stats",cmd) == 0) {
        process_stats(sock);
    } else if (strcmp("reset", cmd) == 0) {
        process_reset(sock);
    } else if (strcmp("quit", cmd) == 0){
        process_quit(sock);
    } else {
        process_error(sock);
    }*/
    Send(sock, buf, strlen(buf));

    return 0;
}

//设置socket为非阻塞
void setnonblocking(int sockfd) {
    int opts;
    opts = fcntl(sockfd, F_GETFL);
    if (opts < 0) {
        perror("fcntl(F_GETFL)\n");
        exit(1);
    }
    opts = (opts | O_NONBLOCK);
    if (fcntl(sockfd, F_SETFL, opts) < 0) {
        perror("fcntl(F_SETFL)\n");
        exit(1);
    }
}
int main() {
    int listenfd, conn_sock, epfd;
    char buf[BUFSIZ];
    socklen_t clilen;
    struct sockaddr_in cliaddr, servaddr;
    struct epoll_event ev, events[MAX_EVENTS];
    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    if (listenfd < 0) {
        printf("create socket error\n");
        return -1;
    }
    int on = 1;
    setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
    setnonblocking(listenfd);
    struct linger {
        int l_onoff; /* 0 = off, nozero = on */
        int l_linger; /* linger time */
    }lin;
    lin.l_onoff = 1;
    lin.l_linger = 0;
    setsockopt(listenfd, SOL_SOCKET, SO_LINGER, (char*)&lin, sizeof(lin));
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(PORT);

    if(bind(listenfd,(struct sockaddr*)&servaddr,sizeof(struct sockaddr))<0){
        printf("bind error\n");
        close(listenfd);
        return -1;
    }

    if(listen(listenfd, 5) < 0) {
        printf("listen error\n");
        close(listenfd);
        return -1; 
    }
    epfd = epoll_create(MAX_EVENTS); //生成epoll专用的文件描述符
    if (epfd == -1) {
        printf("epoll_create\n");
        return -1;
    }
    ev.events = EPOLLIN | EPOLLET; //设置处理的事件类型,设置为边沿触发
    ev.data.fd = listenfd;
    if (epoll_ctl(epfd, EPOLL_CTL_ADD, listenfd, &ev) == -1) {
        printf("epoll_ctl add listen_sock fail\n");
        close(listenfd);
        return -1;
    }
    while (1) {
        int timeout = 1000; 
        int nfds = epoll_wait(epfd, events, MAX_EVENTS, timeout);
        if (nfds == -1) {
            printf("epoll_wait\n");
            return -1;
        }
        for (int i = 0;i < nfds; ++i) {
            int fd = events[i].data.fd;
            if (fd == listenfd) { //监听事件
                while ((conn_sock = accept(listenfd, NULL, NULL)) > 0) {//循环处理accept,这样可以处理多个连接在就绪队列中的情况
                    printf("accept %d\n", conn_sock);
                    setnonblocking(conn_sock);
                    ev.events = EPOLLIN | EPOLLET; //设置为边沿触发
                    ev.data.fd = conn_sock;
                    if (epoll_ctl(epfd, EPOLL_CTL_ADD, conn_sock, &ev) == -1) {
                        printf("epoll_ctl: add fail\n");
                        close(conn_sock);
                        return -1;
                    }
                }
            } else if (events[i].events & EPOLLIN) {//读事件，说明有数据从客户端发来
                int n = 0;
                int nread = 0;
                while ((nread = read(fd, buf + n, BUFSIZ - n)) > 0) {
                    n += nread;
                }
                if (nread == -1 && errno != EAGAIN) {//读数据错误,关闭描述符
                    printf("read error\n");
                    close(fd); //关闭一个描述符，它会从epoll描述符集合中自动删除
                    continue;
                }
                if(nread == 0) { //客户端关闭连接，关闭相应的描述符
                    close(fd);
                    continue;
                }
                if( n > 0) {
                    process_command(fd, buf);
                    memset(buf, 0, sizeof(buf));
                }
            }
        }
    }
}