1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <unistd.h>
4 #include <time.h>
5 #include <arpa/inet.h>
6
7 #include <libmnl/libmnl.h>
8 #include <libnetfilter_conntrack/libnetfilter_conntrack.h>
9
data_cb(const struct nlmsghdr * nlh,void * data)10 static int data_cb(const struct nlmsghdr *nlh, void *data)
11 {
12 struct nf_expect *exp;
13 uint32_t type = NFCT_T_UNKNOWN;
14 char buf[4096];
15
16 exp = nfexp_new();
17 if (exp == NULL)
18 return MNL_CB_OK;
19
20 if (nfexp_nlmsg_parse(nlh, exp) < 0) {
21 perror("failed to parse message from kernel");
22 return MNL_CB_ERROR;
23 }
24
25 nfexp_snprintf(buf, sizeof(buf), exp, type, NFCT_O_DEFAULT, 0);
26 printf("%s\n", buf);
27
28 nfexp_destroy(exp);
29
30 return MNL_CB_OK;
31 }
32
main(void)33 int main(void)
34 {
35 struct mnl_socket *nl;
36 char buf[MNL_SOCKET_BUFFER_SIZE];
37 struct nlmsghdr *nlh;
38 struct nfgenmsg *nfh;
39 uint32_t seq, portid;
40 int ret;
41
42 nl = mnl_socket_open(NETLINK_NETFILTER);
43 if (nl == NULL) {
44 perror("mnl_socket_open");
45 exit(EXIT_FAILURE);
46 }
47
48 if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
49 perror("mnl_socket_bind");
50 exit(EXIT_FAILURE);
51 }
52
53 portid = mnl_socket_get_portid(nl);
54
55 nlh = mnl_nlmsg_put_header(buf);
56 nlh->nlmsg_type = (NFNL_SUBSYS_CTNETLINK_EXP << 8) | IPCTNL_MSG_EXP_GET;
57 nlh->nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP|NLM_F_ACK;
58 nlh->nlmsg_seq = seq = time(NULL);
59
60 nfh = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg));
61 nfh->nfgen_family = AF_INET;
62 nfh->version = NFNETLINK_V0;
63 nfh->res_id = 0;
64
65 ret = mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
66 if (ret == -1) {
67 perror("mnl_socket_recvfrom");
68 exit(EXIT_FAILURE);
69 }
70
71 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
72 while (1) {
73 ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL);
74 if (ret <= MNL_CB_STOP)
75 break;
76
77 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
78 }
79 if (ret == -1) {
80 perror("mnl_socket_recvfrom");
81 exit(EXIT_FAILURE);
82 }
83
84 mnl_socket_close(nl);
85
86 return 0;
87 }
88