09libevent库服务端与客户端的TCP通信流程和代码示例
以下是关于libevent学习的相关文章:
01libevent库的下载与安装并且测试是否安装成功
02libevent库的整体框架思想
03libevent下通信的主要函数
04libevent库下fifo作为通信的套接字
05libevent库下未决与非未决的解释
06libevent下通信中bufferevent缓冲区的特性介绍
07libevent库下bufferevent事件的相关函数
08libevent库下通信服务端与客户端的主要函数
09libevent库服务端与客户端的TCP通信流程和代码示例
1 服务端主要流程
1 创建event_base()
2 创建服务器连接监听器evconnlistener_new_bind()
3 新连接到来，开始通信：
//1) 先添加bufferevent事件
//2) 给bufferevent缓冲区设置三种回调
//3) 启动bufferevent的读监听(因为bufferevent读监听事件是禁用的)
4 创建event普通事件
5 添加事件到base
6 循环监听事件==>epoll_wait+while(1)
7 释放相关资源
2 客户端主要流程
1 创建event_base()
2 使用bufferevent_socket_new()创建一个用跟服务器通信的bufferevent事件对象
3 使用bufferevent_socket_connect()连接服务器
4 使用bufferevent_setcb()给bufferevent对象的读、写、异常设置回调
5 设置bufferevent对象的读写缓冲区enable、diasble
6 接收、发送数据bufferevent_read()、bufferevent_write()
7 释放资源
3 服务端的代码
//server.c
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <event2/event.h>
#include <event2/listener.h>
#include <event2/bufferevent.h>
void send_cb(evutil_socket_t fd, short what, void *arg);
// 读缓冲区回调
void read_cb(struct bufferevent *bev, void *arg)
{
char buf[1024] = {
0};
bufferevent_read(bev, buf, sizeof(buf));
char* p = "我已经收到了你发送的数据!";
printf("client say: %s\n", buf);
}
// 写缓冲区回调
void write_cb(struct bufferevent *bev, void *arg)
{
printf("我是写缓冲区的回调函数...您已发送\n");
}
// 事件
void 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");
}
//每次发生异常时都要是否buffevent
bufferevent_free(bev);
printf("buffevent 资源已经被释放...\n");
}
void cb_listener(
struct evconnlistener *listener,
evutil_socket_t fd,
struct sockaddr *addr,
int len, void *ptr)
{
printf("connect new client\n");
struct event_base* base = (struct event_base*)ptr;
//3 新连接到来，开始通信
//1) 先添加bufferevent事件
struct bufferevent *bev;
bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
//2) 给bufferevent缓冲区设置三种回调
bufferevent_setcb(bev, read_cb, write_cb, event_cb, NULL);
//3) 启动bufferevent的读监听(因为bufferevent读监听事件是禁用的)
bufferevent_enable(bev, EV_READ);
//4 创建event普通事件(参2为int型句柄,需与FILE*类型的stdin区分)
struct event* ev = event_new(base, STDIN_FILENO,
EV_READ | EV_PERSIST,
send_cb, bev);
//5 添加事件到base
event_add(ev, NULL);
}
void send_cb(evutil_socket_t fd, short what, void *arg)
{
char buf[1024] = {
0};
struct bufferevent* bev = (struct bufferevent*)arg;
// printf("请输入要发送的数据: \n");
read(fd, buf, sizeof(buf));
bufferevent_write(bev, buf, strlen(buf)+1);
}
int main(int argc, const char* argv[])
{
// init server
struct sockaddr_in serv;
memset(&serv, 0, sizeof(serv));
serv.sin_family = AF_INET;
serv.sin_port = htons(9876);
serv.sin_addr.s_addr = htonl(INADDR_ANY);
//1 创建base
struct event_base* base;
base = event_base_new();
//2 创建listener(相当于socket,bind,listen,accept)，并设置监听回调
struct evconnlistener* listener;
listener = evconnlistener_new_bind(base, cb_listener, base, LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE, 36, (struct sockaddr*)&serv, sizeof(serv));//参4代表端口复用并且关闭bufferevent时释放底层端口和套接字,36为listen的监听数
//6 循环监听事件==>epoll_wait+while(1)
event_base_dispatch(base);
//7 释放相关资源
evconnlistener_free(listener);
event_base_free(base);
return 0;
}
4 客户端的代码
//client.c
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <event2/event.h>
#include <event2/bufferevent.h>
void read_cb(struct bufferevent *bev, void *arg)
{
char buf[1024] = {
0};
bufferevent_read(bev, buf, sizeof(buf));
printf("Server say: %s\n", buf);
}
void write_cb(struct bufferevent *bev, void *arg)
{
printf("我是写缓冲区的回调函数...您已发送\n");
}
void 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");
}
else if(events & BEV_EVENT_CONNECTED)
{
printf("服务器已连接\n");
return;
}
bufferevent_free(bev);
printf("free bufferevent...\n");
}
void send_cb(evutil_socket_t fd, short what, void *arg)
{
char buf[1024] = {
0};
struct bufferevent* bev = (struct bufferevent*)arg;
// printf("请输入要发送的数据: \n");
read(fd, buf, sizeof(buf));
bufferevent_write(bev, buf, strlen(buf)+1);
}
int main(int argc, const char* argv[])
{
struct event_base* base;
base = event_base_new();
struct bufferevent* bev;
bev = bufferevent_socket_new(base, -1, BEV_OPT_CLOSE_ON_FREE);
// 连接服务器
struct sockaddr_in serv;
memset(&serv, 0, sizeof(serv));
serv.sin_family = AF_INET;
serv.sin_port = htons(9876);
evutil_inet_pton(AF_INET, "127.0.0.1", &serv.sin_addr.s_addr);
bufferevent_socket_connect(bev, (struct sockaddr*)&serv, sizeof(serv));
// 设置回调
bufferevent_setcb(bev, read_cb, write_cb, event_cb, NULL);
bufferevent_enable(bev, EV_READ | EV_PERSIST);
// 创建一个事件
struct event* ev = event_new(base, STDIN_FILENO, EV_READ | EV_PERSIST, send_cb, bev);
//添加一个事件
event_add(ev, NULL);
//循环监听事件==>epoll_wait+while(1)
event_base_dispatch(base);
event_base_free(base);
return 0;
}