libnftnl  1.2.9
nft-chain-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/chain.h>
18 
19 static int table_cb(const struct nlmsghdr *nlh, void *data)
20 {
21  struct nftnl_chain *t;
22  char buf[4096];
23  uint32_t *type = data;
24 
25  t = nftnl_chain_alloc();
26  if (t == NULL) {
27  perror("OOM");
28  goto err;
29  }
30 
31  if (nftnl_chain_nlmsg_parse(nlh, t) < 0) {
32  perror("nftnl_chain_nlmsg_parse");
33  goto err_free;
34  }
35 
36  nftnl_chain_snprintf(buf, sizeof(buf), t, *type, 0);
37  printf("%s\n", buf);
38 
39 err_free:
40  nftnl_chain_free(t);
41 err:
42  return MNL_CB_OK;
43 }
44 
45 int main(int argc, char *argv[])
46 {
47  struct mnl_socket *nl;
48  char buf[MNL_SOCKET_BUFFER_SIZE];
49  struct nlmsghdr *nlh;
50  uint32_t portid, seq, type = NFTNL_OUTPUT_DEFAULT;
51  struct nftnl_chain *t = NULL;
52  int ret, family;
53 
54  seq = time(NULL);
55 
56  if (argc < 2 || argc > 5) {
57  fprintf(stderr, "Usage: %s <family> [<table> <chain>]\n",
58  argv[0]);
59  exit(EXIT_FAILURE);
60  }
61 
62  if (strcmp(argv[1], "ip") == 0)
63  family = NFPROTO_IPV4;
64  else if (strcmp(argv[1], "ip6") == 0)
65  family = NFPROTO_IPV6;
66  else if (strcmp(argv[1], "inet") == 0)
67  family = NFPROTO_INET;
68  else if (strcmp(argv[1], "bridge") == 0)
69  family = NFPROTO_BRIDGE;
70  else if (strcmp(argv[1], "arp") == 0)
71  family = NFPROTO_ARP;
72  else if (strcmp(argv[1], "unspec") == 0)
73  family = NFPROTO_UNSPEC;
74  else {
75  fprintf(stderr, "Unknown family: ip, ip6, inet, bridge, arp, unspec\n");
76  exit(EXIT_FAILURE);
77  }
78 
79  if (argc >= 4) {
80  t = nftnl_chain_alloc();
81  if (t == NULL) {
82  perror("OOM");
83  exit(EXIT_FAILURE);
84  }
85  nlh = nftnl_nlmsg_build_hdr(buf, NFT_MSG_GETCHAIN, family,
86  NLM_F_ACK, seq);
87  nftnl_chain_set_str(t, NFTNL_CHAIN_TABLE, argv[2]);
88  nftnl_chain_set_str(t, NFTNL_CHAIN_NAME, argv[3]);
89  nftnl_chain_nlmsg_build_payload(nlh, t);
90  nftnl_chain_free(t);
91  } else if (argc >= 2) {
92  nlh = nftnl_nlmsg_build_hdr(buf, NFT_MSG_GETCHAIN, family,
93  NLM_F_DUMP, seq);
94  }
95 
96  nl = mnl_socket_open(NETLINK_NETFILTER);
97  if (nl == NULL) {
98  perror("mnl_socket_open");
99  exit(EXIT_FAILURE);
100  }
101 
102  if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
103  perror("mnl_socket_bind");
104  exit(EXIT_FAILURE);
105  }
106  portid = mnl_socket_get_portid(nl);
107 
108  if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
109  perror("mnl_socket_send");
110  exit(EXIT_FAILURE);
111  }
112 
113  ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
114  while (ret > 0) {
115  ret = mnl_cb_run(buf, ret, seq, portid, table_cb, &type);
116  if (ret <= 0)
117  break;
118  ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
119  }
120  if (ret == -1) {
121  perror("error");
122  exit(EXIT_FAILURE);
123  }
124  mnl_socket_close(nl);
125 
126  return EXIT_SUCCESS;
127 }