nfct-mnl-dump-labels.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

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

static void print_label(struct nf_conntrack *ct, struct nfct_labelmap *map)
{
        unsigned int i, max;
        const struct nfct_bitmask *b = nfct_get_attr(ct, ATTR_CONNLABELS);
        if (!b)
                return;

        puts("labels:");
        max = nfct_bitmask_maxbit(b);
        for (i = 0; i <= max; i++) {
                if (nfct_bitmask_test_bit(b, i))
                        printf("\t'%s' (%d)\n", map ? nfct_labelmap_get_name(map, i) : "", i);
        }
}

static int data_cb(const struct nlmsghdr *nlh, void *data)
{
        struct nf_conntrack *ct;
        char buf[4096];

        ct = nfct_new();
        if (ct == NULL)
                return MNL_CB_OK;

        nfct_nlmsg_parse(nlh, ct);

        nfct_snprintf(buf, sizeof(buf), ct, NFCT_T_UNKNOWN, NFCT_O_DEFAULT, 0);
        printf("%s\n", buf);

        print_label(ct, data);

        nfct_destroy(ct);

        return MNL_CB_OK;
}

int main(void)
{
        struct mnl_socket *nl;
        struct nlmsghdr *nlh;
        struct nfgenmsg *nfh;
        char buf[MNL_SOCKET_BUFFER_SIZE];
        unsigned int seq, portid;
        int ret;
        struct nfct_labelmap *l = nfct_labelmap_new(NULL);

        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);

        nlh = mnl_nlmsg_put_header(buf);
        nlh->nlmsg_type = (NFNL_SUBSYS_CTNETLINK << 8) | IPCTNL_MSG_CT_GET;
        nlh->nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP;
        nlh->nlmsg_seq = seq = time(NULL);

        nfh = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg));
        nfh->nfgen_family = AF_UNSPEC;
        nfh->version = NFNETLINK_V0;
        nfh->res_id = 0;


        ret = mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
        if (ret == -1) {
                perror("mnl_socket_sendto");
                exit(EXIT_FAILURE);
        }

        ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));


        while (ret > 0) {
                ret = mnl_cb_run(buf, ret, seq, portid, data_cb, l);
                if (ret <= MNL_CB_STOP)
                        break;
                ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
        }
        if (ret == -1) {
                perror("mnl_socket_recvfrom");
                exit(EXIT_FAILURE);
        }

        if (l)
                nfct_labelmap_destroy(l);

        mnl_socket_close(nl);

        return 0;
}