Libevent例子(二)

2021年09月15日 阅读数:3
这篇文章主要向大家介绍Libevent例子(二),主要内容包括基础应用、实用技巧、原理机制等方面,希望对大家有所帮助。

服务端服务器

#include<netinet/in.h>
#include<stdio.h>
#include<string.h>
#include<event.h>
#include<event2/listener.h>
#include<event2/bufferevent.h>
#include<event2/thread.h>


void listener_cb(struct evconnlistener *listener, evutil_socket_t fd, struct sockaddr *sock, int socklen, void *arg);
void socket_read_cb(struct bufferevent *bev, void *arg);
void socket_event_cb(struct bufferevent *bev, short events, void *arg);

int main() {
    //evthread_use_pthreads();//enable threads
    struct sockaddr_in sin;
    memset(&sin, 0, sizeof(struct sockaddr_in));
    sin.sin_family = AF_INET;
    sin.sin_port = htons(18001);

    struct event_base *base = event_base_new();
    struct evconnlistener *listener = evconnlistener_new_bind(
            base, listener_cb, base, LEV_OPT_REUSEABLE | LEV_OPT_CLOSE_ON_FREE, 10, (struct sockaddr *) &sin, sizeof(struct sockaddr_in));
    event_base_dispatch(base);
    evconnlistener_free(listener);
    event_base_free(base);
    return 0;
}

//一个新客户端链接上服务器了
//当此函数被调用时,libevent已经帮咱们accept了这个客户端。该客户端的
//文件描述符为fd
void listener_cb(struct evconnlistener *listener, evutil_socket_t fd, struct sockaddr *sock, int socklen, void *arg) {
    printf("accept a client %d\n", fd);
    struct event_base *base = (struct event_base *) arg;
    //为这个客户端分配一个bufferevent
    struct bufferevent *bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
    bufferevent_setcb(bev, socket_read_cb, NULL, socket_event_cb, NULL);
    bufferevent_enable(bev, EV_READ | EV_PERSIST);
}

void socket_read_cb(struct bufferevent *bev, void *arg) {
    char msg[4096];
    size_t len = bufferevent_read(bev, msg, sizeof(msg) - 1);
    msg[len] = '\0';
    printf("server read the data %s\n", msg);
    char reply[] = "I has read your data";
    bufferevent_write(bev, reply, strlen(reply));
}

void socket_event_cb(struct bufferevent *bev, short events, void *arg) {
    if (events & BEV_EVENT_EOF) {
        printf("connection closed\n");
    } else if (events & BEV_EVENT_ERROR) {
        printf("some other error\n");
    }
    //这将自动close套接字和free读写缓冲区
    bufferevent_free(bev);
}

客户端socket

#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<event.h>
#include<event2/bufferevent.h>
#include<event2/buffer.h>
#include<event2/util.h>


int tcp_connect_server(const char *server_ip, int port);
void cmd_msg_cb(int fd, short events, void *arg);
void server_msg_cb(struct bufferevent *bev, void *arg);
void event_cb(struct bufferevent *bev, short event, void *arg);

int main(int argc, char **argv) {
    if (argc < 3) {
        //两个参数依次是服务器端的IP地址、端口号
        printf("please input 2 parameter\n");
        return -1;
    }
    struct event_base *base = event_base_new();
    struct bufferevent *bev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);

    //监听终端输入事件
    struct event *ev_cmd = event_new(
            base, STDIN_FILENO, EV_READ | EV_PERSIST, cmd_msg_cb, (void *) bev);

    event_add(ev_cmd, NULL);

    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(atoi(argv[2]));
    inet_aton(argv[1], &server_addr.sin_addr);
    bufferevent_socket_connect(
            bev, (struct sockaddr *) &server_addr, sizeof(server_addr));
    bufferevent_setcb(bev, server_msg_cb, NULL, event_cb, (void *) ev_cmd);
    bufferevent_enable(bev, EV_READ | EV_PERSIST);
    event_base_dispatch(base);
    printf("finished \n");
    return 0;
}

void cmd_msg_cb(int fd, short events, void *arg) {
    char msg[1024];
    int ret = read(fd, msg, sizeof(msg));
    if (ret < 0) {
        perror("read fail ");
        exit(1);
    }
    struct bufferevent *bev = (struct bufferevent *) arg;
    //把终端的消息发送给服务器端
    bufferevent_write(bev, msg, ret);
}

void server_msg_cb(struct bufferevent *bev, void *arg) {
    char msg[1024];
    size_t len = bufferevent_read(bev, msg, sizeof(msg));
    msg[len] = '\0';
    printf("recv %s from server\n", msg);
}

void event_cb(struct bufferevent *bev, short event, void *arg) {
    if (event & BEV_EVENT_EOF) {
        printf("connection closed\n");
    } else if (event & BEV_EVENT_ERROR) {
        printf("some other error\n");
    } else if (event & BEV_EVENT_CONNECTED) {
        printf("the client has connected to server\n");
        return;
    }
    //这将自动close套接字和free读写缓冲区
    bufferevent_free(bev);
    struct event *ev = (struct event *) arg;
    event_free(ev);
}