libnl: /data/src/libnl3/src/nf-ct-events.c Source File

libnl 3.7.0

nf-ct-events.c
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
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, &params);
32 }
33
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
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 }
NL_OK
@ NL_OK
Proceed with whatever would come next.
Definition: handlers.h:58
NL_CB_VALID
@ NL_CB_VALID
Message is valid.
Definition: handlers.h:89
NL_CB_CUSTOM
@ NL_CB_CUSTOM
Customized handler specified by the user.
Definition: handlers.h:77
nl_cli_fatal
void nl_cli_fatal(int err, const char *fmt,...)
Print error message and quit application.
Definition: utils.c:71
nlmsg_hdr
struct nlmsghdr * nlmsg_hdr(struct nl_msg *n)
Return actual netlink message.
Definition: msg.c:536
nl_object_dump
void nl_object_dump(struct nl_object *obj, struct nl_dump_params *params)
Dump this object according to the specified parameters.
Definition: object.c:287
nl_recvmsgs_default
int nl_recvmsgs_default(struct nl_sock *sk)
Receive a set of message from a netlink socket using handlers in nl_sock.
Definition: nl.c:1087
nl_join_groups
void nl_join_groups(struct nl_sock *sk, int groups)
Join multicast groups (deprecated)
Definition: socket.c:527
nl_socket_disable_seq_check
void nl_socket_disable_seq_check(struct nl_sock *sk)
Disable sequence number checking.
Definition: socket.c:277
nl_socket_modify_cb
int nl_socket_modify_cb(struct nl_sock *sk, enum nl_cb_type type, enum nl_cb_kind kind, nl_recvmsg_msg_cb_t func, void *arg)
Modify the callback handler associated with the socket.
Definition: socket.c:765
NL_DUMP_DETAILS
@ NL_DUMP_DETAILS
Dump all attributes but no statistics.
Definition: types.h:17
nl_dump_params
Dumping parameters.
Definition: types.h:28
nl_dump_params::dp_fd
FILE * dp_fd
File descriptor the dumping output should go to.
Definition: types.h:77
nl_list_head
Definition: list.h:12
private_nl_object
Definition: nf-ct-events.c:14