libnftnl 1.2.9
nft-rule-get.c
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
4 *
5 * This software has been sponsored by Sophos Astaro <http://www.sophos.com>
6 */
7
8#include <stdlib.h>
9#include <time.h>
10#include <string.h>
11#include <netinet/in.h>
12
13#include <linux/netfilter.h>
14#include <linux/netfilter/nf_tables.h>
15
16#include <libmnl/libmnl.h>
17#include <libnftnl/rule.h>
18
19static int table_cb(const struct nlmsghdr *nlh, void *data)
20{
21 struct nftnl_rule *t;
22 char buf[4096];
23 uint32_t *type = data;
24
25 t = nftnl_rule_alloc();
26 if (t == NULL) {
27 perror("OOM");
28 goto err;
29 }
30
31 if (nftnl_rule_nlmsg_parse(nlh, t) < 0) {
32 perror("nftnl_rule_nlmsg_parse");
33 goto err_free;
34 }
35
36 nftnl_rule_snprintf(buf, sizeof(buf), t, *type, 0);
37 printf("%s\n", buf);
38
39err_free:
40 nftnl_rule_free(t);
41err:
42 return MNL_CB_OK;
43}
44
45static struct nftnl_rule *setup_rule(uint8_t family, const char *table,
46 const char *chain, const char *handle)
47{
48 struct nftnl_rule *r;
49 uint64_t handle_num;
50
51 r = nftnl_rule_alloc();
52 if (r == NULL)
53 return NULL;
54
55 if (table != NULL)
56 nftnl_rule_set_str(r, NFTNL_RULE_TABLE, table);
57 if (chain != NULL)
58 nftnl_rule_set_str(r, NFTNL_RULE_CHAIN, chain);
59
60 nftnl_rule_set_u32(r, NFTNL_RULE_FAMILY, family);
61
62 if (handle != NULL) {
63 handle_num = atoll(handle);
64 nftnl_rule_set_u64(r, NFTNL_RULE_POSITION, handle_num);
65 }
66
67 return r;
68}
69
70int main(int argc, char *argv[])
71{
72 struct mnl_socket *nl;
73 char buf[MNL_SOCKET_BUFFER_SIZE];
74 struct nlmsghdr *nlh;
75 uint32_t portid, seq, type = NFTNL_OUTPUT_DEFAULT;
76 const char *table = NULL, *chain = NULL;
77 struct nftnl_rule *r;
78 int ret, family;
79
80 if (argc < 2 || argc > 5) {
81 fprintf(stderr, "Usage: %s <family> [<table> <chain>]\n",
82 argv[0]);
83 exit(EXIT_FAILURE);
84 }
85
86 if (strcmp(argv[1], "ip") == 0)
87 family = NFPROTO_IPV4;
88 else if (strcmp(argv[1], "ip6") == 0)
89 family = NFPROTO_IPV6;
90 else if (strcmp(argv[1], "inet") == 0)
91 family = NFPROTO_INET;
92 else if (strcmp(argv[1], "bridge") == 0)
93 family = NFPROTO_BRIDGE;
94 else if (strcmp(argv[1], "arp") == 0)
95 family = NFPROTO_ARP;
96 else if (strcmp(argv[1], "unspec") == 0)
97 family = NFPROTO_UNSPEC;
98 else {
99 fprintf(stderr, "Unknown family: ip, ip6, inet, bridge, arp, unspec\n");
100 exit(EXIT_FAILURE);
101 }
102
103 /* at least [<table> <chain>] specified */
104 if (argc >= 4) {
105 table = argv[2];
106 chain = argv[3];
107 }
108
109 seq = time(NULL);
110 nlh = nftnl_nlmsg_build_hdr(buf, NFT_MSG_GETRULE, family,
111 NLM_F_DUMP, seq);
112
113 r = setup_rule(family, table, chain, NULL);
114 if (!r) {
115 perror("setup_rule");
116 exit(EXIT_FAILURE);
117 }
118 nftnl_rule_nlmsg_build_payload(nlh, r);
119
120 nl = mnl_socket_open(NETLINK_NETFILTER);
121 if (nl == NULL) {
122 perror("mnl_socket_open");
123 exit(EXIT_FAILURE);
124 }
125
126 if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
127 perror("mnl_socket_bind");
128 exit(EXIT_FAILURE);
129 }
130 portid = mnl_socket_get_portid(nl);
131
132 if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
133 perror("mnl_socket_send");
134 exit(EXIT_FAILURE);
135 }
136
137 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
138 while (ret > 0) {
139 ret = mnl_cb_run(buf, ret, seq, portid, table_cb, &type);
140 if (ret <= 0)
141 break;
142 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
143 }
144 if (ret == -1) {
145 perror("error");
146 exit(EXIT_FAILURE);
147 }
148 mnl_socket_close(nl);
149
150 return EXIT_SUCCESS;
151}