Libevent使用实例2 (中等) : bufferevent

￡神魔★判官ぃ 2022-05-11 08:44 331阅读 0赞

客户端：

#include<sys/types.h>
    #include<sys/socket.h>
    #include<netinet/in.h>
    #include<arpa/inet.h>
    #include<errno.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) {
    		printf("please input 2 parameter \n");
    		return -1;
    	}
    
    	//两个参数依次是服务器端的IP地址，端口号
    	int sockfd = tcp_connect_server(argv[1],atoi(argv[2]));
    	if(sockfd == -1) {
    		perror("tcp_connect error");
    		return -1;
    	}
    
    	printf("connect to server successful\n");
    
    	struct event_base* base = event_base_new();
    
    	struct bufferevent* bev = bufferevent_socket_new(base,sockfd,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);
    
    	//当socket关闭时会用到回调参数
    	bufferevent_setcb(bev,server_msg_cb,NULL,event_cb,(void*)ev_cmd);	
    	// read_cb:server_msg_cb,  eventcb:event_cb, cbarg:ev_cmd
    	
    	//bufferevent_setcb函数：bufferevent_setcb(struct bufferevent *bufev,bufferevent_data_cb readcb, 
    	//							bufferevent_data_cb writecb,bufferevent_event_cb eventcb, void *cbarg)
    
    	
    	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)	//fd:STDIN_FILENO, events:EV_READ | EV_PERSIST, arg:bev 从标准输入读并发送到服务器端
    {
    	char msg[1024];
    
    	int ret = read(fd,msg,sizeof(msg));
    	if(ret < 0) {
    		perror("read fail");
    		exit(1);
    	}
    
    	struct bufferevent* bev = (struct bufferevent*)arg;
    
    	//把终端消息发送给服务器端
    	bufferevent_write(bev,msg,ret);
    }
    
    void server_msg_cb(struct bufferevent* bev, void* arg)  //bev:bev, arg:NULL  此回调函数为读事件的回调函数
    {
    	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) { //bev:bev , event:错误回调,告知一些错误, arg: ev_cmd
    	if(event & BEV_EVENT_EOF)
    		printf("connection closed \n");
    	else if (event & 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);
    
    	struct event *ev = (struct event*)arg;
    	//因为socket已经没有，所以这个event也没有存在的必要了
    	event_free(ev);
    }
    
    typedef struct sockaddr SA;
    int tcp_connect_server(const char* server_ip, int port)
    {
    	int sockfd, status, save_errno;
    	struct sockaddr_in server_addr;
    
    	memset(&server_addr,0,sizeof(server_addr));
    
    	server_addr.sin_family = AF_INET;
    	server_addr.sin_port = htons(port);
    	status = inet_aton(server_ip, &server_addr.sin_addr);
    
    	if (status == 0)	//the server_ip is not valid value
    	{
    		errno = EINVAL;
    		return -1;
    	}
    
    	sockfd = socket(PF_INET,SOCK_STREAM,0);
    	if(sockfd == -1)
    		return sockfd;
    
    	status = connect(sockfd, (SA*)&server_addr, sizeof(server_addr));
    
    	if(status == -1)
    	{
    		save_errno = errno;
    		close(sockfd);
    		errno = save_errno;	//the close may be error 
    		return -1;
    	}
    
    	evutil_make_socket_nonblocking(sockfd);
    
    	return sockfd;
    }

服务器端：

#include<stdio.h>
    #include<string.h>
    #include<errno.h>
    
    #include<event.h>
    #include<event2/bufferevent.h>
    
    void accept_cb(int fd, short events, void* arg);
    void socket_read_cb(struct bufferevent *bev, void* arg);
    void event_cb(struct bufferevent *bev, short event, void *arg);
    int tcp_server_init(int port, int listen_num);
    
    int main(int argc, char** argv)
    {
    	int listener = tcp_server_init(9999,10);
    	if(listener == -1) {
    		perror("tcp_server_init error");
    		return -1;
    	}
    
    	struct event_base* base = event_base_new();
    
    	//添加监听客户端请求连接事件
    	struct event* ev_listen = event_new(base, listener, EV_READ | EV_PERSIST, accept_cb, base);
    	event_add(ev_listen, NULL);
    
    	event_base_dispatch(base);
    	event_base_free(base);
    
    	return 0;
    }
    
    
    void accept_cb(int fd, short events, void* arg) {	//fd:listener, events:EV_READ | EV_PERSIST, arg:base
    	evutil_socket_t  sockfd;
    
    	struct sockaddr_in client;
    	socklen_t len = sizeof(client);
    	sockfd = accept(fd,(struct sockaddr*)&client, &len);
    	evutil_make_socket_nonblocking(sockfd);
    
    	printf("accept a client %d \n",sockfd);
    
    	struct event_base* base = (struct event_base*) arg;
    
    	struct bufferevent* bev = bufferevent_socket_new(base,sockfd,BEV_OPT_CLOSE_ON_FREE);
    	bufferevent_setcb(bev, socket_read_cb, NULL, event_cb, arg);	//socket_read_cb是读回调,发生可读事件则调用
    
    	bufferevent_enable(bev,EV_READ | EV_PERSIST);
    }
    
    void socket_read_cb(struct bufferevent* bev, void* arg) // bev:bev , arg:NULL  此回调函数为读事件回调函数
    {
    	char msg[4096];
    
    	size_t len = bufferevent_read(bev,msg,sizeof(msg));
    
    	msg[len] = '\0';
    	printf("recv the client msg: %s",msg);
    
    	char reply_msg[4096] = "I have recieved the msg: ";
    
    	strcat(reply_msg + strlen(reply_msg), msg);		
    	bufferevent_write(bev, reply_msg, strlen(reply_msg));	//读取数据并发送回复消息收到数据
    }
    
    
    void event_cb(struct bufferevent *bev, short event, void *arg) {	//bev:bev, event:错误回调告知一些未知错误
    	if(event & BEV_EVENT_EOF)
    		printf("connection closed \n");
    	else if (event & 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);
    }
    
    typedef struct sockaddr SA;
    int tcp_server_init(int port, int listen_num)
    {
    	int errno_save;
    	evutil_socket_t listener;
    
    	listener = socket(AF_INET, SOCK_STREAM, 0);
    	if(listener == -1)
    		return -1;
    
    	//允许多次绑定同一个地址,要用在socket 和 bind之间
    	evutil_make_listen_socket_reuseable(listener);
    
    	struct sockaddr_in sin;
    	sin.sin_family = AF_INET;
    	sin.sin_addr.s_addr = 0;
    	sin.sin_port = htons(port);
    
    	if(bind(listener, (SA*)&sin,sizeof(sin)) < 0)
    		goto error;
    
    	if(listen(listener, listen_num) < 0)
    		goto error;
    
    	//跨平台统一接口,将套接字设置为非阻塞状态
    	evutil_make_socket_nonblocking(listener);
    
    	return listener;
    
    error:
    	errno_save = errno;
    	evutil_closesocket(listener);
    	errno = errno_save;
    
    	return -1;
    }

同样编译命令：

gcc  -o  xxxx.c   xxxx    -levent    //levent后缀必须要

运行结果：

客户端：

![70][]

服务器端：

![70 1][]

[70]: /images/20220511/ff100167d47c48fda59327c734387b52.png
[70 1]: /images/20220511/2eb772047d344c5280e1896eb4f1bc1b.png