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
10 #include <linux/netfilter/nf_conntrack_tcp.h>
11
data_cb(const struct nlmsghdr * nlh,void * data)12 static int data_cb(const struct nlmsghdr *nlh, void *data)
13 {
14 struct nf_conntrack *ct;
15 char buf[4096];
16
17 ct = nfct_new();
18 if (ct == NULL)
19 return MNL_CB_OK;
20
21 nfct_nlmsg_parse(nlh, ct);
22
23 nfct_snprintf(buf, sizeof(buf), ct, NFCT_T_UNKNOWN, NFCT_O_DEFAULT, 0);
24 printf("%s\n", buf);
25
26 nfct_destroy(ct);
27
28 return MNL_CB_OK;
29 }
30
main(void)31 int main(void)
32 {
33 struct mnl_socket *nl;
34 struct nlmsghdr *nlh;
35 struct nfgenmsg *nfh;
36 char buf[MNL_SOCKET_BUFFER_SIZE];
37 unsigned int seq, portid;
38 struct nf_conntrack *ct;
39 int ret;
40
41 nl = mnl_socket_open(NETLINK_NETFILTER);
42 if (nl == NULL) {
43 perror("mnl_socket_open");
44 exit(EXIT_FAILURE);
45 }
46
47 if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
48 perror("mnl_socket_bind");
49 exit(EXIT_FAILURE);
50 }
51 portid = mnl_socket_get_portid(nl);
52
53 nlh = mnl_nlmsg_put_header(buf);
54 nlh->nlmsg_type = (NFNL_SUBSYS_CTNETLINK << 8) | IPCTNL_MSG_CT_GET;
55 nlh->nlmsg_flags = NLM_F_REQUEST|NLM_F_ACK;
56 nlh->nlmsg_seq = seq = time(NULL);
57
58 nfh = mnl_nlmsg_put_extra_header(nlh, sizeof(struct nfgenmsg));
59 nfh->nfgen_family = AF_INET;
60 nfh->version = NFNETLINK_V0;
61 nfh->res_id = 0;
62
63 ct = nfct_new();
64 if (ct == NULL) {
65 perror("nfct_new");
66 return 0;
67 }
68
69 nfct_set_attr_u8(ct, ATTR_L3PROTO, AF_INET);
70 nfct_set_attr_u32(ct, ATTR_IPV4_SRC, inet_addr("1.1.1.1"));
71 nfct_set_attr_u32(ct, ATTR_IPV4_DST, inet_addr("2.2.2.2"));
72
73 nfct_set_attr_u8(ct, ATTR_L4PROTO, IPPROTO_TCP);
74 nfct_set_attr_u16(ct, ATTR_PORT_SRC, htons(20));
75 nfct_set_attr_u16(ct, ATTR_PORT_DST, htons(10));
76
77 nfct_nlmsg_build(nlh, ct);
78
79 ret = mnl_socket_sendto(nl, nlh, nlh->nlmsg_len);
80 if (ret == -1) {
81 perror("mnl_socket_recvfrom");
82 exit(EXIT_FAILURE);
83 }
84
85 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
86 while (ret > 0) {
87 ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL);
88 if (ret <= MNL_CB_STOP)
89 break;
90 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
91 }
92 if (ret == -1) {
93 perror("mnl_socket_recvfrom");
94 exit(EXIT_FAILURE);
95 }
96
97 mnl_socket_close(nl);
98
99 return 0;
100 }
101