1 /* SPDX-License-Identifier: LGPL-2.1-only */
2 /*
3 * Copyright (c) 2018 Avast software
4 */
5
6 #include <netlink/cli/utils.h>
7 #include <netlink/cli/ct.h>
8
9 #include <linux/netlink.h>
10 #include <linux/netfilter/nfnetlink.h>
11 #include <linux/netfilter/nfnetlink_conntrack.h>
12
13 struct private_nl_object
14 {
15 int ce_refcnt;
16 struct nl_object_ops * ce_ops;
17 struct nl_cache * ce_cache;
18 struct nl_list_head ce_list;
19 int ce_msgtype;
20 int ce_flags;
21 uint64_t ce_mask;
22 };
23
nf_conntrack_parse_callback(struct nl_object * obj,void * opaque)24 static void nf_conntrack_parse_callback(struct nl_object *obj, void *opaque)
25 {
26 struct nl_dump_params params = {
27 .dp_fd = stdout,
28 .dp_type = NL_DUMP_DETAILS,
29 };
30
31 nl_object_dump(obj, ¶ms);
32 }
33
nf_conntrack_event_callback(struct nl_msg * msg,void * opaque)34 static int nf_conntrack_event_callback(struct nl_msg *msg, void *opaque)
35 {
36 int err;
37 struct nlmsghdr *hdr = nlmsg_hdr(msg);
38
39 enum cntl_msg_types type = (enum cntl_msg_types) NFNL_MSG_TYPE(hdr->nlmsg_type);
40
41 int flags = hdr->nlmsg_flags;
42
43 if (type == IPCTNL_MSG_CT_DELETE) {
44 printf("DELETE ");
45 } else if (type == IPCTNL_MSG_CT_NEW) {
46 if (flags & (NLM_F_CREATE|NLM_F_EXCL)) {
47 printf("NEW ");
48 } else {
49 printf("UPDATE ");
50 }
51 } else {
52 printf("UNKNOWN ");
53 }
54
55 if ((err = nl_msg_parse(msg, &nf_conntrack_parse_callback, opaque)) < 0) {
56 nl_cli_fatal(err, "nl_msg_parse: %s", nl_geterror(err));
57 }
58 /* Continue with next event */
59 return NL_OK;
60 }
61
main(int argc,char * argv[])62 int main(int argc, char *argv[])
63 {
64 struct nl_sock *socket;
65 int err;
66
67 socket = nl_cli_alloc_socket();
68 if (socket == NULL) {
69 nl_cli_fatal(ENOBUFS, "Unable to allocate netlink socket");
70 }
71
72 /*
73 * Disable sequence number checking.
74 * This is required to allow messages to be processed which were not requested by
75 * a preceding request message, e.g. netlink events.
76 */
77 nl_socket_disable_seq_check(socket);
78
79 /* subscribe conntrack events */
80 nl_join_groups(socket, NF_NETLINK_CONNTRACK_NEW |
81 NF_NETLINK_CONNTRACK_UPDATE |
82 NF_NETLINK_CONNTRACK_DESTROY |
83 NF_NETLINK_CONNTRACK_EXP_NEW |
84 NF_NETLINK_CONNTRACK_EXP_UPDATE |
85 NF_NETLINK_CONNTRACK_EXP_DESTROY);
86
87 nl_cli_connect(socket, NETLINK_NETFILTER);
88
89 nl_socket_modify_cb(socket, NL_CB_VALID, NL_CB_CUSTOM, &nf_conntrack_event_callback, 0);
90
91 while (1) {
92
93 errno = 0;
94 if ((err = nl_recvmsgs_default(socket)) < 0) {
95 switch (errno) {
96 case ENOBUFS:
97 // just print warning
98 fprintf(stderr, "Lost events because of ENOBUFS\n");
99 break;
100 case EAGAIN:
101 case EINTR:
102 // continue reading
103 break;
104 default:
105 nl_cli_fatal(err, "Failed to receive: %s", nl_geterror(err));
106 }
107 }
108 }
109 }
110