linux下使用libevent库实现简单TCP服务器和客户端

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server.c

#include <stdio.h>
#include <event2/event.h>
#include <event2/bufferevent.h>
#include <event2/listener.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#define PORT 9999
#define IP "127.0.0.1"
void read_cb(struct bufferevent *bev, void *arg)
{
  char buf[1024];
  memset(buf, '\0', sizeof(buf));
  //从缓冲区读取数据
  bufferevent_read(bev, buf, sizeof(buf));
  printf("client send data: %s\n", buf);
  char *p = "i am server, i got you.\n";
  //注意数据向缓冲区写完，才会回调write_cb
  bufferevent_write(bev, p, strlen(p));
}
void write_cb(struct bufferevent *bev, void *arg)
{
  printf("i am server, write data.... done!\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("error\n");
  }
  bufferevent_free(bev);
}
void listen_cb(struct evconnlistener *listener, evutil_socket_t sock, struct sockaddr *addr, int len, void *ptr)
{
  char ip[16];
  memset(&ip, '\0', sizeof(ip));
  struct sockaddr_in *client_addr = (struct sockaddr_in*)&addr;
  printf("receive connection from ip:%s port:%d\n", inet_ntop(AF_INET, &client_addr->sin_addr.s_addr, ip, sizeof(ip)), ntohs(client_addr->sin_port));

  struct event_base *base = (struct event_base*) ptr;
  struct bufferevent *bev = bufferevent_socket_new(base, sock, BEV_OPT_CLOSE_ON_FREE);

  bufferevent_setcb(bev, read_cb, write_cb, event_cb, NULL);
  //启用bufferevent读缓冲，（默认创建时，读缓冲处于关闭状态，写缓冲处于开启状态）
  bufferevent_enable(bev, EV_READ);
}
int main()
{
  struct event_base *base = event_base_new();
  
  //初始化地址结构
  struct sockaddr_in serv_addr;
  memset(&serv_addr, 0, sizeof(serv_addr));
  serv_addr.sin_family = AF_INET;
  serv_addr.sin_port = htons(PORT);
  //创建监听服务器
  struct evconnlistener *evl = evconnlistener_new_bind(base,
      listen_cb,
      base,
      LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE,
      -1,
      (struct sockaddr*)&serv_addr,
      sizeof(serv_addr));
  //释放资源
  event_base_dispatch(base);
  evconnlistener_free(evl);
  event_base_free(base);
  return 0;
}

client.c

#include <stdio.h>
#include <event2/event.h>
#include <event2/bufferevent.h>
#include <event2/listener.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#define PORT 9999
#define IP "127.0.0.1"
void read_cb(struct bufferevent *bev, void *arg)
{
  char buf[1024] = {0};
  //memset(buf, '\0', sizeof(buf));
  bufferevent_read(bev, buf, sizeof(buf));
  printf("server send data: %s\n", buf);	
}
void write_cb(struct bufferevent *bev, void *arg)
{
  printf("i am client,write data.... done!\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("error\n");
  }
  else if(events & BEV_EVENT_CONNECTED)
  {
    printf("已经连接服务器\n");
    return;
  }
  printf("free bufferevent...\n");
  bufferevent_free(bev);
}


void read_terminal_cb(evutil_socket_t fd, short what, void *arg)
{
  char buf[BUFSIZ] = {0};
  int len = read(fd, buf, sizeof(buf));
  struct bufferevent *bev = (struct bufferevent*) arg;
  bufferevent_write(bev, buf, len);
}
int main()
{
  int fd = socket(AF_INET, SOCK_STREAM, 0);
  struct event_base *base = event_base_new();
  struct bufferevent *bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
  
  struct sockaddr_in serv_addr;
  memset(&serv_addr, 0, sizeof(serv_addr));
  serv_addr.sin_family = AF_INET;
  serv_addr.sin_port = htons(PORT);
  inet_pton(AF_INET, IP, &serv_addr.sin_addr.s_addr);
  
  int ret = bufferevent_socket_connect(bev, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
  
  bufferevent_setcb(bev, read_cb, write_cb, event_cb, NULL);
//	bufferevent_setcb(bev, read_cb, write_cb, NULL, NULL);
  //启用bufferevent读缓冲，（默认创建时，读缓冲处于关闭状态，写缓冲处于开启状态）
  bufferevent_enable(bev, EV_READ);

  if(ret < 0)
  {
    perror("bufferevent_socket_connect error");
    return -1;
  }
  //设置并监听终端输入事件
  struct event *ev = event_new(base,
      STDIN_FILENO,
      EV_READ | EV_PERSIST,
      read_terminal_cb, bev);
  //添加事件
  event_add(ev, NULL);

  event_base_dispatch(base);
  //释放资源
  event_free(ev);
  bufferevent_free(bev);
  event_base_free(base);
  return 0;
}

其他示例：linux下使用libevent库实现简单TCP服务器和客户端_吃错药的博客-CSDN博客_libevent tcpserver