Libevent使用实例3 (高级) : evconnlistenner监听器_libevent evconnlistener 获得fd

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:

服务器端：