1 /* This example is placed in the public domain. */
2 #include <stdio.h>
3 #include <stdlib.h>
4 #include <unistd.h>
5
6 #include <libmnl/libmnl.h>
7 #include <linux/if.h>
8 #include <linux/if_link.h>
9 #include <linux/rtnetlink.h>
10
data_attr_cb(const struct nlattr * attr,void * data)11 static int data_attr_cb(const struct nlattr *attr, void *data)
12 {
13 const struct nlattr **tb = data;
14 int type = mnl_attr_get_type(attr);
15
16 /* skip unsupported attribute in user-space */
17 if (mnl_attr_type_valid(attr, IFLA_MAX) < 0)
18 return MNL_CB_OK;
19
20 switch(type) {
21 case IFLA_MTU:
22 if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
23 perror("mnl_attr_validate");
24 return MNL_CB_ERROR;
25 }
26 break;
27 case IFLA_IFNAME:
28 if (mnl_attr_validate(attr, MNL_TYPE_STRING) < 0) {
29 perror("mnl_attr_validate");
30 return MNL_CB_ERROR;
31 }
32 break;
33 }
34 tb[type] = attr;
35 return MNL_CB_OK;
36 }
37
data_cb(const struct nlmsghdr * nlh,void * data)38 static int data_cb(const struct nlmsghdr *nlh, void *data)
39 {
40 struct nlattr *tb[IFLA_MAX+1] = {};
41 struct ifinfomsg *ifm = mnl_nlmsg_get_payload(nlh);
42
43 printf("index=%d type=%d flags=%d family=%d ",
44 ifm->ifi_index, ifm->ifi_type,
45 ifm->ifi_flags, ifm->ifi_family);
46
47 if (ifm->ifi_flags & IFF_RUNNING)
48 printf("[RUNNING] ");
49 else
50 printf("[NOT RUNNING] ");
51
52 mnl_attr_parse(nlh, sizeof(*ifm), data_attr_cb, tb);
53 if (tb[IFLA_MTU]) {
54 printf("mtu=%d ", mnl_attr_get_u32(tb[IFLA_MTU]));
55 }
56 if (tb[IFLA_IFNAME]) {
57 printf("name=%s", mnl_attr_get_str(tb[IFLA_IFNAME]));
58 }
59 printf("\n");
60 return MNL_CB_OK;
61 }
62
main(void)63 int main(void)
64 {
65 struct mnl_socket *nl;
66 char buf[MNL_SOCKET_BUFFER_SIZE];
67 int ret;
68
69 nl = mnl_socket_open(NETLINK_ROUTE);
70 if (nl == NULL) {
71 perror("mnl_socket_open");
72 exit(EXIT_FAILURE);
73 }
74
75 if (mnl_socket_bind(nl, RTMGRP_LINK, MNL_SOCKET_AUTOPID) < 0) {
76 perror("mnl_socket_bind");
77 exit(EXIT_FAILURE);
78 }
79
80 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
81 while (ret > 0) {
82 ret = mnl_cb_run(buf, ret, 0, 0, data_cb, NULL);
83 if (ret <= 0)
84 break;
85 ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
86 }
87 if (ret == -1) {
88 perror("error");
89 exit(EXIT_FAILURE);
90 }
91
92 mnl_socket_close(nl);
93
94 return 0;
95 }
96