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 
19 static 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 
39 err_free:
40  nftnl_rule_free(t);
41 err:
42  return MNL_CB_OK;
43 }
44 
45 static 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 
70 int 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 }