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/* This example is placed in the public domain. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <time.h>
#include <arpa/inet.h>
#include <libmnl/libmnl.h>
#include <linux/if.h>
#include <linux/if_link.h>
#include <linux/rtnetlink.h>
static int data_attr_cb(const struct nlattr *attr, void *data)
{
const struct nlattr **tb = data;
int type = mnl_attr_get_type(attr);
/* skip unsupported attribute in user-space */
if (mnl_attr_type_valid(attr, IFA_MAX) < 0)
return MNL_CB_OK;
switch(type) {
case NDA_DST:
if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0) {
perror("mnl_attr_validate");
return MNL_CB_ERROR;
}
break;
case NDA_LLADDR:
if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0) {
perror("mnl_attr_validate");
return MNL_CB_ERROR;
}
break;
}
tb[type] = attr;
return MNL_CB_OK;
}
static int data_cb(const struct nlmsghdr *nlh, void *data)
{
struct nlattr *tb[IFA_MAX + 1] = {};
struct ndmsg *ndm = mnl_nlmsg_get_payload(nlh);
printf("index=%d family=%d ", ndm->ndm_ifindex, ndm->ndm_family);
mnl_attr_parse(nlh, sizeof(*ndm), data_attr_cb, tb);
printf("dst=");
if (tb[NDA_DST]) {
void *addr = mnl_attr_get_payload(tb[NDA_DST]);
char out[INET6_ADDRSTRLEN];
if (inet_ntop(ndm->ndm_family, addr, out, sizeof(out)))
printf("%s ", out);
}
mnl_attr_parse(nlh, sizeof(*ndm), data_attr_cb, tb);
printf("lladdr=");
if (tb[NDA_LLADDR]) {
void *addr = mnl_attr_get_payload(tb[NDA_LLADDR]);
unsigned char lladdr[6] = {0};
if (memcpy(&lladdr, addr, 6))
printf("%02x:%02x:%02x:%02x:%02x:%02x ", lladdr[0], lladdr[1], lladdr[2], lladdr[3], lladdr[4], lladdr[5]);
}
printf("state=");
switch(ndm->ndm_state) {
case NUD_INCOMPLETE:
printf("incomplete ");
break;
case NUD_REACHABLE:
printf("reachable ");
break;
case NUD_STALE:
printf("stale ");
break;
case NUD_DELAY:
printf("delay ");
break;
case NUD_PROBE:
printf("probe ");
break;
case NUD_FAILED:
printf("failed ");
break;
case NUD_NOARP:
printf("noarp ");
break;
case NUD_PERMANENT:
printf("permanent ");
break;
default:
printf("%d ", ndm->ndm_state);
break;
}
printf("\n");
return MNL_CB_OK;
}
int main(int argc, char *argv[])
{
struct mnl_socket *nl;
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
struct rtgenmsg *rt;
int ret;
unsigned int seq, portid;
if (argc != 2) {
fprintf(stderr, "Usage: %s <inet|inet6>\n", argv[0]);
exit(EXIT_FAILURE);
}
nlh = mnl_nlmsg_put_header(buf);
nlh->nlmsg_type = RTM_GETNEIGH;
nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
nlh->nlmsg_seq = seq = time(NULL);
rt = mnl_nlmsg_put_extra_header(nlh, sizeof(struct rtgenmsg));
if (strcmp(argv[1], "inet") == 0)
rt->rtgen_family = AF_INET;
else if (strcmp(argv[1], "inet6") == 0)
rt->rtgen_family = AF_INET6;
nl = mnl_socket_open(NETLINK_ROUTE);
if (nl == NULL) {
perror("mnl_socket_open");
exit(EXIT_FAILURE);
}
if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0) {
perror("mnl_socket_bind");
exit(EXIT_FAILURE);
}
portid = mnl_socket_get_portid(nl);
if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
perror("mnl_socket_sendto");
exit(EXIT_FAILURE);
}
ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
while (ret > 0) {
ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL);
if (ret <= MNL_CB_STOP)
break;
ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
}
if (ret == -1) {
perror("error");
exit(EXIT_FAILURE);
}
mnl_socket_close(nl);
return 0;
}
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