nfct-helper-get.c

/* This example is in the public domain. */
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <libmnl/libmnl.h>
#include <libnetfilter_cthelper/libnetfilter_cthelper.h>

static int nfct_helper_cb(const struct nlmsghdr *nlh, void *data)
{
        struct nfct_helper *nfct_helper;
        char buf[4096];

        nfct_helper = nfct_helper_alloc();
        if (nfct_helper == NULL) {
                perror("OOM");
                goto err;
        }

        if (nfct_helper_nlmsg_parse_payload(nlh, nfct_helper) < 0) {
                perror("nfct_helper_parse_nl_msg");
                goto err_free;
        }

        nfct_helper_snprintf(buf, sizeof(buf), nfct_helper, 0, 0);
        printf("%s\n", buf);

err_free:
        nfct_helper_free(nfct_helper);
err:
        return MNL_CB_OK;
}

int main(int argc, char *argv[])
{
        struct mnl_socket *nl;
        char buf[MNL_SOCKET_BUFFER_SIZE];
        struct nlmsghdr *nlh;
        uint32_t portid, seq;
        int ret, full = 1;

        if (argc != 1) {
                fprintf(stderr, "Usage: %s\n", argv[0]);
                exit(EXIT_FAILURE);
        }

        seq = time(NULL);
        nlh = nfct_helper_nlmsg_build_hdr(buf, NFNL_MSG_CTHELPER_GET,
                                        NLM_F_DUMP, seq);

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

        if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
                perror("mnl_socket_bind");
                exit(EXIT_FAILURE);
        }
        portid = mnl_socket_get_portid(nl);

        if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
                perror("mnl_socket_send");
                exit(EXIT_FAILURE);
        }

        ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
        while (ret > 0) {
                ret = mnl_cb_run(buf, ret, seq, portid, nfct_helper_cb, &full);
                if (ret <= 0)
                        break;
                ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
        }
        if (ret == -1) {
                perror("error");
                exit(EXIT_FAILURE);
        }
        mnl_socket_close(nl);

        return EXIT_SUCCESS;
}