libevent example: echo server

libevent_echo_server.cpp

#include <WinSock2.h>
#include <event.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <iostream>
#include <thread>

#pragma comment(lib, "libevent.lib")
#pragma comment(lib, "libevent_core.lib")
#pragma comment(lib, "libevent_extras.lib")
#pragma comment (lib, "Ws2_32.lib")
#pragma comment (lib, "Mswsock.lib")
#pragma comment (lib, "AdvApi32.lib")

using namespace std;

static void echo_read_cb(struct bufferevent *bev, void *ctx)
{
	/* This callback is invoked when there is data to read on bev. */
	struct evbuffer *input = bufferevent_get_input(bev);
	struct evbuffer *output = bufferevent_get_output(bev);
	size_t len = evbuffer_get_length(input);
	char *data;
	data = (char*)malloc(len);
	evbuffer_copyout(input, data, len);

	printf("we got some data: %s\n", data);

	/* Copy all the data from the input buffer to the output buffer. */
	evbuffer_add_buffer(output, input);
	free(data);
}

static void echo_event_cb(struct bufferevent *bev, short events, void *ctx)
{
	if (events & BEV_EVENT_ERROR)
		perror("Error from bufferevent");
	if (events & (BEV_EVENT_EOF | BEV_EVENT_ERROR)) {
		bufferevent_free(bev);
	}
}

void bufferevent_getcb(struct bufferevent *bufev,
	bufferevent_data_cb *readcb_ptr,
	bufferevent_data_cb *writecb_ptr,
	bufferevent_event_cb *eventcb_ptr,
	void **cbarg_ptr);

static void
accept_conn_cb(struct evconnlistener *listener, evutil_socket_t fd, struct sockaddr *address, int socklen, void *ctx)
{
	/* We got a new connection! Set up a bufferevent for it. */
	struct event_base *base = evconnlistener_get_base(listener);
	struct bufferevent *bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
	bufferevent_setcb(bev, echo_read_cb, NULL, echo_event_cb, NULL);

	bufferevent_enable(bev, EV_READ | EV_WRITE);
}

static void accept_error_cb(struct evconnlistener *listener, void *ctx)
{
	struct event_base *base = evconnlistener_get_base(listener);
	int err = EVUTIL_SOCKET_ERROR();
	fprintf(stderr, "Got an error %d (%s) on the listener. "
		"Shutting down.\n", err, evutil_socket_error_to_string(err));

	event_base_loopexit(base, NULL);
}

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

	WSADATA wsaData;
	auto opt = MAKEWORD(2, 1);
	WSAStartup(opt, &wsaData);

	/* Create new event base */
	base = event_base_new();
	if (!base) {
		puts("Couldn't open event base");
		return 1;
	}

	/* Clear the sockaddr before using it, in case there are extra
	* platform-specific fields that can mess us up. */
	memset(&sin, 0, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_port = htons(30001);

	/* Create a new listener */
	listener = evconnlistener_new_bind(base, accept_conn_cb, (void*)base,
		LEV_OPT_CLOSE_ON_FREE | LEV_OPT_REUSEABLE, -1,
		(struct sockaddr *) &sin, sizeof(sin));
	if (!listener) {
		perror("Couldn't create listener");
		return 1;
	}
	evconnlistener_set_error_cb(listener, accept_error_cb);

	/* Lets rock */
	event_base_dispatch(base);
	return 0;
}