Visual Studio 2017开发linux程序之libevent使用实例

下载源码编译安装后，samle里面有个hello-world.c就是最简单的一个tcp server端程序了

/*
  This example program provides a trivial server program that listens for TCP
  connections on port 9995.  When they arrive, it writes a short message to
  each client connection, and closes each connection once it is flushed.

  Where possible, it exits cleanly in response to a SIGINT (ctrl-c).
*/


#include 
#include 
#include 
#include 
#ifndef _WIN32
#include 
# ifdef _XOPEN_SOURCE_EXTENDED
#  include 
# endif
#include 
#endif

#include 
#include 
#include 
#include 
#include 

static const char MESSAGE[] = "Hello, World!\n";

static const int PORT = 9995;

static void listener_cb(struct evconnlistener *, evutil_socket_t,
    struct sockaddr *, int socklen, void *);
static void conn_writecb(struct bufferevent *, void *);
static void conn_eventcb(struct bufferevent *, short, void *);
static void signal_cb(evutil_socket_t, short, void *);

int
main(int argc, char **argv)
{
	struct event_base *base;
	struct evconnlistener *listener;
	struct event *signal_event;

	struct sockaddr_in sin;
#ifdef _WIN32
	WSADATA wsa_data;
	WSAStartup(0x0201, &wsa_data);
#endif

	base = event_base_new();
	if (!base) {
		fprintf(stderr, "Could not initialize libevent!\n");
		return 1;
	}

	memset(&sin, 0, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_port = htons(PORT);

	listener = evconnlistener_new_bind(base, listener_cb, (void *)base,
	    LEV_OPT_REUSEABLE|LEV_OPT_CLOSE_ON_FREE, -1,
	    (struct sockaddr*)&sin,
	    sizeof(sin));

	if (!listener) {
		fprintf(stderr, "Could not create a listener!\n");
		return 1;
	}

	signal_event = evsignal_new(base, SIGINT, signal_cb, (void *)base);

	if (!signal_event || event_add(signal_event, NULL)<0) {
		fprintf(stderr, "Could not create/add a signal event!\n");
		return 1;
	}

	event_base_dispatch(base);

	evconnlistener_free(listener);
	event_free(signal_event);
	event_base_free(base);

	printf("done\n");
	return 0;
}

static void
listener_cb(struct evconnlistener *listener, evutil_socket_t fd,
    struct sockaddr *sa, int socklen, void *user_data)
{
	struct event_base *base = user_data;
	struct bufferevent *bev;

	bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
	if (!bev) {
		fprintf(stderr, "Error constructing bufferevent!");
		event_base_loopbreak(base);
		return;
	}
	bufferevent_setcb(bev, NULL, conn_writecb, conn_eventcb, NULL);
	bufferevent_enable(bev, EV_WRITE);
	bufferevent_disable(bev, EV_READ);

	bufferevent_write(bev, MESSAGE, strlen(MESSAGE));
}

static void
conn_writecb(struct bufferevent *bev, void *user_data)
{
	struct evbuffer *output = bufferevent_get_output(bev);
	if (evbuffer_get_length(output) == 0) {
		printf("flushed answer\n");
		bufferevent_free(bev);
	}
}

static void
conn_eventcb(struct bufferevent *bev, short events, void *user_data)
{
	if (events & BEV_EVENT_EOF) {
		printf("Connection closed.\n");
	} else if (events & BEV_EVENT_ERROR) {
		printf("Got an error on the connection: %s\n",
		    strerror(errno));/*XXX win32*/
	}
	/* None of the other events can happen here, since we haven't enabled
	 * timeouts */
	bufferevent_free(bev);
}

static void
signal_cb(evutil_socket_t sig, short events, void *user_data)
{
	struct event_base *base = user_data;
	struct timeval delay = { 2, 0 };

	printf("Caught an interrupt signal; exiting cleanly in two seconds.\n");

	event_base_loopexit(base, &delay);
}

设置好链接库的路径和链接库

写一个简单的client端，代码如下：

// sample_tcpclient.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"


#include 
#include 
#include 

#pragma comment(lib,"ws2_32.lib")

#define _WINSOCK_DEPRECATED_NO_WARNINGS

int main(int argc, char* argv[])
{
	WORD wVersionRequested;
	WSADATA wsaData;
	int err;

	wVersionRequested = MAKEWORD(1, 1);

	err = WSAStartup(wVersionRequested, &wsaData);
	if (err != 0) {
		printf("WSAStartup failed:%d\n", err);
		getchar();
		exit(0);
	}

	if (LOBYTE(wsaData.wVersion) != 1 ||
		HIBYTE(wsaData.wVersion) != 1) {
		WSACleanup();
		printf("version error\n");
		getchar();
		exit(0);
	}
lab_start:
	SOCKET sockClient = socket(AF_INET, SOCK_STREAM, 0);

	SOCKADDR_IN addrSrv;
	addrSrv.sin_addr.S_un.S_addr = inet_addr("192.168.2.41");
	addrSrv.sin_family = AF_INET;
	addrSrv.sin_port = htons(9995);
	int ret = connect(sockClient, (SOCKADDR*)&addrSrv, sizeof(SOCKADDR));
	if (ret != 0)
	{
		printf("connect failed:%d\n", ret);
		return -1;
	}

	// 开启KeepAlive
	BOOL bKeepAlive = TRUE;
	int nRet = ::setsockopt(sockClient, SOL_SOCKET, SO_KEEPALIVE, (char*)&bKeepAlive, sizeof(bKeepAlive));
	if (nRet == SOCKET_ERROR)
	{
		printf("setsockopt error:%d\n", nRet);
		return -1;
	}
	// 设置KeepAlive参数
	tcp_keepalive alive_in = { 0 };
	tcp_keepalive alive_out = { 0 };
	alive_in.keepalivetime = 5000;                // 开始首次KeepAlive探测前的TCP空闭时间
	alive_in.keepaliveinterval = 1000;                // 两次KeepAlive探测间的时间间隔
	alive_in.onoff = TRUE;

	unsigned long ulBytesReturn = 0;
	nRet = WSAIoctl(sockClient, SIO_KEEPALIVE_VALS, &alive_in, sizeof(alive_in),
		&alive_out, sizeof(alive_out), &ulBytesReturn, NULL, NULL);
	if (nRet == SOCKET_ERROR)
	{
		printf("WSAIoctl error:%d\n", nRet);
		return -1;
	}

	//disable nagle
	int on = 1;
	/* make socket here */
#ifdef WIN32  
	setsockopt(sockClient, IPPROTO_TCP, TCP_NODELAY, (const char *)&on, sizeof(on));
#else  
	setsockopt(sockClient, IPPROTO_TCP, TCP_NODELAY, (void *)&on, sizeof(on));
#endif  

	const char *data_str = "hello world, i am client";
	int data_len = strlen(data_str)+1;
	for (int i = 0; i < 10; i++)
	{
		ret = send(sockClient, data_str + (data_len - data_len % 1024), data_len % 1024, 0);
		if (ret < 0)
		{
			printf("send error:%d\n", ret);
			break;
		}
		printf("data_len:%d count:%d ret:%d\n", data_len, i, ret);

		char recvBuf[256];
		ret = ::recv(sockClient, recvBuf, 256, 0);
		if (ret < 0)
		{
			printf("recv error:%d\n", ret);
			break;
		}
		recvBuf[ret] = '\0';
		printf("ret:%d recv:%s\n", ret, recvBuf);

		Sleep(3000);
	}

	closesocket(sockClient);
	getchar();

	closesocket(sockClient);
	WSACleanup();
}

然后就是连接成功了：