用libevent实现简易的telnet

    我承认这篇文章有点标题党，呵呵。其实就是一个能和服务器建立全双工通信的客户端而已，用网络库libevent实现。
  

    从这里也可以看出，同样的功能，分别用epoll和libevent来比较，从代码量和代码清晰度来说，libevent完胜，呵呵。
  

    上代码：
  

    #include <sys/socket.h>

#include <string.h>

#include <errno.h>

#include <stdlib.h>

#include <unistd.h>



#include <event.h>

#include <event2/event.h>



//发生了致命错误，输入错误信息，退出程序

void error_quit(const char *str)

{

	perror(str);

	exit(1); 

}



//连接状态改变时回调的函数

void eventcb(struct bufferevent *bev, short events, void *ptr)

{

	struct event_base *tbase = (struct event_base*)ptr;

	//如果不是连接成功的消息，就停止事件循环

	if ( !(events & BEV_EVENT_CONNECTED) ) 

	{

		bufferevent_free(bev);

		event_base_loopbreak(tbase);

		printf("The connect have been shutdown: %X\n", events);

	} 

}



//服务器传信息过来了

void sockreadcb(struct bufferevent *bev, void *ptr)

{

	struct evbuffer *input = bufferevent_get_input(bev);

	evbuffer_write(input, STDOUT_FILENO);

}



//标准输入传消息过来了

void stdreadcb(struct bufferevent *bev, void *ptr)

{

	struct bufferevent *sockbev = (struct bufferevent*)ptr; 

	struct evbuffer *input = bufferevent_get_input(bev);

	bufferevent_write_buffer(sockbev, input);

}



int main(int argc, char **argv)

{

	struct sockaddr_in servaddr;

	struct event *shellev;

	int res;

	struct event_base *base;

	struct bufferevent *sockbev;

	struct bufferevent *stdbev;



	if( argc != 3 )

		error_quit("Using: mytelnet <Address> <Port>");



	memset(&servaddr, 0, sizeof(servaddr));    

	servaddr.sin_family = AF_INET;    

	servaddr.sin_port = htons( atoi(argv[2]) );    

	res = inet_pton(AF_INET, argv[1], &servaddr.sin_addr);  

	if( res != 1 )

		error_quit("inet_pton error");   



	base = event_base_new();



	//连接服务器并监听

	sockbev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);

	res = bufferevent_socket_connect(sockbev,

		(struct sockaddr *)&servaddr, sizeof(servaddr));

	if ( res < 0 ) 

		error_quit("connect error");



	bufferevent_setcb(sockbev, sockreadcb, NULL, eventcb, (void*)base);

	bufferevent_enable(sockbev, EV_READ);

	bufferevent_enable(sockbev, EV_WRITE);



	//监听标准输入

	stdbev = bufferevent_socket_new(base, STDIN_FILENO, BEV_OPT_CLOSE_ON_FREE);

	bufferevent_setcb(stdbev, stdreadcb, NULL, NULL, (void*)sockbev);

	bufferevent_enable(stdbev, EV_READ);

	bufferevent_enable(stdbev, EV_WRITE);



	//开始事件循环

	event_base_dispatch(base);



	return 0;

}
  

    编译与运行命令：

gcc mytelnet.c -o mytelnet -levent

./mytelnet 127.0.0.1 8877
  

    用于测试的服务器：
    
      http://blog.csdn.net/aaa20090987/article/details/8769585
    
  

用libevent实现简易的telnet