libevent_client.c_bkp

#include <sys/socket.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>

#include <event.h>
#include <event2/event.h>
#include <event2/bufferevent.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()将上一个函数发生错误的原因输出到标准错误(stderr); 
        参数 s 所指的字符串会先打印出,后面再加上错误原因字符串;
        此错误原因依照全局变量 errno 的值来决定要输出的字符串。 
    */
    perror(str);
    exit(1); 
}

/* 事件回调函数，连接状态改变时回调的函数 */
void event_cb(struct bufferevent *bev, short events, void *ptr)
{
    struct event_base *tbase = (struct event_base*)ptr;
    if ( events & BEV_EVENT_CONNECTED){
	/* We're connected to server. Ordinarily we'd do
           something here, like start reading or writing. */
	printf("Server is connected!\n");
    }else { //如果连接不成功的消息，就停止事件循环
    	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 
   this callback is invoked when there is data to read on bev.
*/
void sock_readcb(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 std_readcb(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 <IP Address> <Port>");
    }
    /* 初始化连接地址 */
    memset(&servaddr, 0, sizeof(servaddr));    
    servaddr.sin_family = AF_INET;    
    servaddr.sin_port = htons( atoi(argv[2]) );
    /*inet_pton 处理IPv4,将“点分十进制” －> “整数 */
    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 */
       //bufferevent_socket_new创建基于套接字的bufferevent， 参数为-1 表示并不为此 bufferevent 设置 socket
    if ((sockbev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE)) == NULL){
    	error_quit("bufferevent_socket_new error");
    }
      // 建立连接,连接成功返回 0 失败返回 -1
    res = bufferevent_socket_connect(sockbev, (struct sockaddr *)&servaddr, sizeof(servaddr));
    if ( res < 0 ){
	bufferevent_free(sockbev);
        error_quit("connect error");
    }
    //为bufferevent event设置回调函数
    bufferevent_setcb(sockbev, sock_readcb, NULL, event_cb, (void*)base);
    //设置watermark
    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, std_readcb, 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;
}