conntrack_get.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <arpa/inet.h>

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

static int cb(enum nf_conntrack_msg_type type,
              struct nf_conntrack *ct,
              void *data)
{
        char buf[1024];

        nfct_snprintf(buf, sizeof(buf), ct, NFCT_T_UNKNOWN, NFCT_O_DEFAULT, NFCT_OF_SHOW_LAYER3);
        printf("%s\n", buf);

        return NFCT_CB_CONTINUE;
}

int main(void)
{
        int ret;
        struct nfct_handle *h;
        struct nf_conntrack *ct;

        ct = nfct_new();
        if (!ct) {
                perror("nfct_new");
                return 0;
        }

        nfct_set_attr_u8(ct, ATTR_L3PROTO, AF_INET);
        nfct_set_attr_u32(ct, ATTR_IPV4_SRC, inet_addr("1.1.1.1"));
        nfct_set_attr_u32(ct, ATTR_IPV4_DST, inet_addr("2.2.2.2"));
        
        nfct_set_attr_u8(ct, ATTR_L4PROTO, IPPROTO_TCP);
        nfct_set_attr_u16(ct, ATTR_PORT_SRC, htons(20));
        nfct_set_attr_u16(ct, ATTR_PORT_DST, htons(10));

        h = nfct_open(CONNTRACK, 0);
        if (!h) {
                perror("nfct_open");
                nfct_destroy(ct);
                return -1;
        }

        nfct_callback_register(h, NFCT_T_ALL, cb, NULL);

        ret = nfct_query(h, NFCT_Q_GET, ct);

        printf("TEST: get conntrack ");
        if (ret == -1)
                printf("(%d)(%s)\n", ret, strerror(errno));
        else
                printf("(OK)\n");

        nfct_close(h);

        nfct_destroy(ct);

        ret == -1 ? exit(EXIT_FAILURE) : exit(EXIT_SUCCESS);
}