libnl 3.5.0

nf-monitor.c
1 /* SPDX-License-Identifier: LGPL-2.1-only */
2 /*
3 * src/nf-monitor.c Monitor netfilter events
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation version 2.1
8 * of the License.
9 *
10 * Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
11 * Copyright (c) 2007 Philip Craig <philipc@snapgear.com>
12 * Copyright (c) 2007 Secure Computing Corporation
13 */
14
15 #include <netlink/cli/utils.h>
16 #include <netlink/netfilter/nfnl.h>
17
18 #include <linux/netlink.h>
19 #include <linux/netfilter/nfnetlink.h>
20
21 static void obj_input(struct nl_object *obj, void *arg)
22 {
23 struct nl_dump_params dp = {
24 .dp_type = NL_DUMP_STATS,
25 .dp_fd = stdout,
26 .dp_dump_msgtype = 1,
27 };
28
29 nl_object_dump(obj, &dp);
30 }
31
32 static int event_input(struct nl_msg *msg, void *arg)
33 {
34 if (nl_msg_parse(msg, &obj_input, NULL) < 0)
35 fprintf(stderr, "<<EVENT>> Unknown message type\n");
36
37 /* Exit nl_recvmsgs_def() and return to the main select() */
38 return NL_STOP;
39 }
40
41 int main(int argc, char *argv[])
42 {
43 struct nl_sock *sock;
44 int err;
45 int i, idx;
46
47 static const struct {
48 enum nfnetlink_groups gr_id;
49 const char* gr_name;
50 } groups[] = {
51 { NFNLGRP_CONNTRACK_NEW, "ct-new" },
52 { NFNLGRP_CONNTRACK_UPDATE, "ct-update" },
53 { NFNLGRP_CONNTRACK_DESTROY, "ct-destroy" },
54 { NFNLGRP_NONE, NULL }
55 };
56
57 sock = nl_cli_alloc_socket();
58 nl_socket_disable_seq_check(sock);
59 nl_socket_modify_cb(sock, NL_CB_VALID, NL_CB_CUSTOM, event_input, NULL);
60
61 if (argc > 1 && !strcasecmp(argv[1], "-h")) {
62 printf("Usage: nf-monitor [<groups>]\n");
63
64 printf("Known groups:");
65 for (i = 0; groups[i].gr_id != NFNLGRP_NONE; i++)
66 printf(" %s", groups[i].gr_name);
67 printf("\n");
68 return 2;
69 }
70
71 nl_cli_connect(sock, NETLINK_NETFILTER);
72
73 for (idx = 1; argc > idx; idx++) {
74 for (i = 0; groups[i].gr_id != NFNLGRP_NONE; i++) {
75 if (strcmp(argv[idx], groups[i].gr_name))
76 continue;
77
78 err = nl_socket_add_membership(sock, groups[i].gr_id);
79 if (err < 0)
80 nl_cli_fatal(err,
81 "Unable to add membership: %s",
82 nl_geterror(err));
83 break;
84 }
85
86 if (groups[i].gr_id == NFNLGRP_NONE)
87 nl_cli_fatal(NLE_OBJ_NOTFOUND, "Unknown group: \"%s\"",
88 argv[idx]);
89 }
90
91 while (1) {
92 fd_set rfds;
93 int fd, retval;
94
95 fd = nl_socket_get_fd(sock);
96
97 FD_ZERO(&rfds);
98 FD_SET(fd, &rfds);
99 /* wait for an incoming message on the netlink socket */
100 retval = select(fd+1, &rfds, NULL, NULL, NULL);
101
102 if (retval) {
103 /* FD_ISSET(fd, &rfds) will be true */
104 nl_recvmsgs_default(sock);
105 }
106 }
107
108 return 0;
109 }
NL_CB_CUSTOM
Customized handler specified by the user.
Definition: handlers.h:83
nl_socket_get_fd
int nl_socket_get_fd(const struct nl_sock *sk)
Return the file descriptor of the backing socket.
Definition: socket.c:584
nl_dump_params::dp_type
enum nl_dump_type dp_type
Specifies the type of dump that is requested.
Definition: types.h:38
NL_STOP
Stop parsing altogether and discard remaining messages.
Definition: handlers.h:68
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:771
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:289
nl_socket_disable_seq_check
void nl_socket_disable_seq_check(struct nl_sock *sk)
Disable sequence number checking.
Definition: socket.c:283
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:1094
NL_CB_VALID
Message is valid.
Definition: handlers.h:95
nl_cli_fatal
void nl_cli_fatal(int err, const char *fmt,...)
Print error message and quit application.
Definition: utils.c:78
nl_dump_params
Dumping parameters.
Definition: types.h:33
NL_DUMP_STATS
Dump all attributes including statistics.
Definition: types.h:24