nft-event.c

/* This example is placed in the public domain. */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>

#include <libmnl/libmnl.h>
#include <linux/netfilter/nfnetlink.h>
#include <linux/netfilter/nfnetlink_conntrack.h>

static int data_cb(const struct nlmsghdr *nlh, void *data)
{
        printf("nft event\n");
}

int main(void)
{
        struct mnl_socket *nl;
        char buf[MNL_SOCKET_BUFFER_SIZE];
        int ret;

        nl = mnl_socket_open(NETLINK_NETFILTER);
        if (nl == NULL) {
                perror("mnl_socket_open");
                exit(EXIT_FAILURE);
        }

        if (mnl_socket_bind(nl, (1 << NFNLGRP_NFTABLES-1),
                                MNL_SOCKET_AUTOPID) < 0) {
                perror("mnl_socket_bind");
                exit(EXIT_FAILURE);
        }

        while (1) {
                ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
                if (ret == -1) {
                        perror("mnl_socket_recvfrom");
                        exit(EXIT_FAILURE);
                }

                ret = mnl_cb_run(buf, ret, 0, 0, data_cb, NULL);
                if (ret == -1) {
                        perror("mnl_cb_run");
                        exit(EXIT_FAILURE);
                }
        }

        mnl_socket_close(nl);

        return 0;
}