Libevent使用实例3 (高级) : evconnlistenner监听器

r囧r小猫 2022-05-11 08:48 330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) {
    		//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) {	//fd:STDIN_FILENO, events:EV_READ | EV_PERSIST, arg:bev 
    	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) {	//读取服务器发送的消息,打印到标准输出
    	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);
    }

服务器端：

#include<netinet/in.h>
    #include<sys/socket.h>
    #include<unistd.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(9999);
    
    	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;
    }
    
    //一个新客户端连接上服务器了
    //当此函数被调用时，libevent已经帮我们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) {	//bev:bev, arg:NULL 
    	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) );	//读取客户端发送的消息，并回复客户端
    }
    
    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);
    }

服务器端使用evconnlistener监听器来接受客户端的连接,封装了连接过程。 用户只需初始化struct sockaddr\_in结构体变量，然后把它作为参数传给函数evconnlistener\_new\_bind即可。

同样编译：

gcc -o xxx.c  xxx   -levent

运行结果：  
客户端:

![70][]

服务器端：

![70 1][]

[70]: /images/20220511/42790731f21244008ca64a1ed17666c8.png
[70 1]: /images/20220511/43a0045156a8468a9600e8ccfc1dbfd4.png