1#include <stdio.h>
2#include <stdlib.h>
3#include <unistd.h>
4#include <arpa/inet.h>
5
6#include <libmnl/libmnl.h>
7#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
8
9static int data_cb(const struct nlmsghdr *nlh, void *data)
10{
11	struct nf_conntrack *ct;
12	uint32_t type = NFCT_T_UNKNOWN;
13	char buf[4096];
14
15	switch(nlh->nlmsg_type & 0xFF) {
16	case IPCTNL_MSG_CT_NEW:
17		if (nlh->nlmsg_flags & (NLM_F_CREATE|NLM_F_EXCL))
18			type = NFCT_T_NEW;
19		else
20			type = NFCT_T_UPDATE;
21		break;
22	case IPCTNL_MSG_CT_DELETE:
23		type = NFCT_T_DESTROY;
24		break;
25	}
26
27	ct = nfct_new();
28	if (ct == NULL)
29		return MNL_CB_OK;
30
31	nfct_nlmsg_parse(nlh, ct);
32
33	nfct_snprintf(buf, sizeof(buf), ct,
34			type, NFCT_O_DEFAULT, 0);
35	printf("%s\n", buf);
36
37	nfct_destroy(ct);
38
39	return MNL_CB_OK;
40}
41
42int main(void)
43{
44	struct mnl_socket *nl;
45	char buf[MNL_SOCKET_BUFFER_SIZE];
46	int ret;
47
48	nl = mnl_socket_open(NETLINK_NETFILTER);
49	if (nl == NULL) {
50		perror("mnl_socket_open");
51		exit(EXIT_FAILURE);
52	}
53
54	if (mnl_socket_bind(nl, NF_NETLINK_CONNTRACK_NEW |
55				NF_NETLINK_CONNTRACK_UPDATE |
56				NF_NETLINK_CONNTRACK_DESTROY,
57				MNL_SOCKET_AUTOPID) < 0) {
58		perror("mnl_socket_bind");
59		exit(EXIT_FAILURE);
60	}
61
62	while (1) {
63		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
64		if (ret == -1) {
65			perror("mnl_socket_recvfrom");
66			exit(EXIT_FAILURE);
67		}
68
69		ret = mnl_cb_run(buf, ret, 0, 0, data_cb, NULL);
70		if (ret == -1) {
71			perror("mnl_cb_run");
72			exit(EXIT_FAILURE);
73		}
74	}
75
76	mnl_socket_close(nl);
77
78	return 0;
79}
80