#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <signal.h>

#include <libnfnetlink/libnfnetlink.h>
#include <libnetfilter_conntrack/libnetfilter_conntrack.h>


volatile sig_atomic_t terminate;


static void __sig_handler(int sig)
{
	switch (sig) {
		case SIGTERM:
		case SIGINT:
			terminate = 1;
			break;
	}
}

int main(int argc, char* argv[])
{
	struct nfct_handle *h;
	struct sigaction sigact;
	char buf[NFNL_BUFFSIZE] __attribute__ ((aligned));
	int len;
	int events = 0;
	int overflows = 0;

	terminate = 0;
	sigact.sa_handler = &__sig_handler;
	sigaction(SIGINT, &sigact, NULL);
	sigaction(SIGTERM, &sigact, NULL);

	h = nfct_open(NFNL_SUBSYS_CTNETLINK,
			NF_NETLINK_CONNTRACK_NEW | NF_NETLINK_CONNTRACK_DESTROY);
	if (h == NULL) {
		perror("opening ctnetlink failed");
		exit(EXIT_FAILURE);
	}
	
	while (!terminate) {
		len = recv(nfct_fd(h), buf, sizeof(buf), 0);
		if (len < 0) {
			if (errno == ENOBUFS) {
				overflows++;
			} else if (errno != EINTR) {
				perror("recv failed");
				nfct_close(h);
				exit(EXIT_FAILURE);
			}
		} else {
			events++;
		}
	}

	printf("%d events received (%d overflows)\n", events, overflows);

	nfct_close(h);

	exit(EXIT_SUCCESS);
}