libevent-tutorial/hello-world.c at master · NicoleRobin/libevent-tutorial · GitHub

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/*
* gcc -g -o hello-world hello-world.c -levent_core
*/
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>

#include <event2/bufferevent.h>
#include <event2/buffer.h>
#include <event2/listener.h>
#include <event2/util.h>
#include <event2/event.h>

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(void)
{
	struct event_base *base;
	struct evconnlistener *listener;
	struct event *signal_event;

	struct sockaddr_in sin;

	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;
	}
	printf("Listening on %d\n", PORT);

	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;
	struct sockaddr_in *sa_in = (struct sockaddr_in*)sa;

	bev = bufferevent_socket_new(base, fd, BEV_OPT_CLOSE_ON_FREE);
	if (!bev)
	{
		fprintf(stderr, "Error construction bufferevent!");
		event_base_loopbreak(base);
		return;
	}
	printf("Recv a new connection, ip[%s], port[%d]\n", inet_ntoa(sa_in->sin_addr), ntohs(sa_in->sin_port));
	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));
	}

	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);
}