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/* This example is placed in the public domain. */
#include <stdio.h>
#include <stdlib.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_cb2(const struct nlattr *attr, void *data)
{
/* skip unsupported attribute in user-space */
if (mnl_attr_type_valid(attr, RTAX_MAX) < 0)
return MNL_CB_OK;
if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
perror("mnl_attr_validate");
return MNL_CB_ERROR;
}
return MNL_CB_OK;
}
static void attributes_show_ipv4(struct nlattr *tb[])
{
if (tb[RTA_TABLE]) {
printf("table=%u ", mnl_attr_get_u32(tb[RTA_TABLE]));
}
if (tb[RTA_DST]) {
struct in_addr *addr = mnl_attr_get_payload(tb[RTA_DST]);
printf("dst=%s ", inet_ntoa(*addr));
}
if (tb[RTA_SRC]) {
struct in_addr *addr = mnl_attr_get_payload(tb[RTA_SRC]);
printf("src=%s ", inet_ntoa(*addr));
}
if (tb[RTA_OIF]) {
printf("oif=%u ", mnl_attr_get_u32(tb[RTA_OIF]));
}
if (tb[RTA_FLOW]) {
printf("flow=%u ", mnl_attr_get_u32(tb[RTA_FLOW]));
}
if (tb[RTA_PREFSRC]) {
struct in_addr *addr = mnl_attr_get_payload(tb[RTA_PREFSRC]);
printf("prefsrc=%s ", inet_ntoa(*addr));
}
if (tb[RTA_GATEWAY]) {
struct in_addr *addr = mnl_attr_get_payload(tb[RTA_GATEWAY]);
printf("gw=%s ", inet_ntoa(*addr));
}
if (tb[RTA_METRICS]) {
int i;
struct nlattr *tbx[RTAX_MAX+1] = {};
mnl_attr_parse_nested(tb[RTA_METRICS], data_attr_cb2, tbx);
for (i=0; i<RTAX_MAX; i++) {
if (tbx[i]) {
printf("metrics[%d]=%u ",
i, mnl_attr_get_u32(tbx[i]));
}
}
}
printf("\n");
}
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, RTA_MAX) < 0)
return MNL_CB_OK;
switch(type) {
case RTA_TABLE:
case RTA_DST:
case RTA_SRC:
case RTA_OIF:
case RTA_FLOW:
case RTA_PREFSRC:
case RTA_GATEWAY:
if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0) {
perror("mnl_attr_validate");
return MNL_CB_ERROR;
}
break;
case RTA_METRICS:
if (mnl_attr_validate(attr, MNL_TYPE_NESTED) < 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[RTA_MAX+1] = {};
struct rtmsg *rm = mnl_nlmsg_get_payload(nlh);
/* protocol family = AF_INET | AF_INET6 */
printf("family=%u ", rm->rtm_family);
/* destination CIDR, eg. 24 or 32 for IPv4 */
printf("dst_len=%u ", rm->rtm_dst_len);
/* source CIDR */
printf("src_len=%u ", rm->rtm_src_len);
/* type of service (TOS), eg. 0 */
printf("tos=%u ", rm->rtm_tos);
/* table id:
* RT_TABLE_UNSPEC = 0
*
* ... user defined values ...
*
* RT_TABLE_COMPAT = 252
* RT_TABLE_DEFAULT = 253
* RT_TABLE_MAIN = 254
* RT_TABLE_LOCAL = 255
* RT_TABLE_MAX = 0xFFFFFFFF
*
* Synonimous attribute: RTA_TABLE.
*/
printf("table=%u ", rm->rtm_table);
/* type:
* RTN_UNSPEC = 0
* RTN_UNICAST = 1
* RTN_LOCAL = 2
* RTN_BROADCAST = 3
* RTN_ANYCAST = 4
* RTN_MULTICAST = 5
* RTN_BLACKHOLE = 6
* RTN_UNREACHABLE = 7
* RTN_PROHIBIT = 8
* RTN_THROW = 9
* RTN_NAT = 10
* RTN_XRESOLVE = 11
* __RTN_MAX = 12
*/
printf("type=%u ", rm->rtm_type);
/* scope:
* RT_SCOPE_UNIVERSE = 0 : everywhere in the universe
*
* ... user defined values ...
*
* RT_SCOPE_SITE = 200
* RT_SCOPE_LINK = 253 : destination attached to link
* RT_SCOPE_HOST = 254 : local address
* RT_SCOPE_NOWHERE = 255 : not existing destination
*/
printf("scope=%u ", rm->rtm_scope);
/* protocol:
* RTPROT_UNSPEC = 0
* RTPROT_REDIRECT = 1
* RTPROT_KERNEL = 2 : route installed by kernel
* RTPROT_BOOT = 3 : route installed during boot
* RTPROT_STATIC = 4 : route installed by administrator
*
* Values >= RTPROT_STATIC are not interpreted by kernel, they are
* just user-defined.
*/
printf("proto=%u ", rm->rtm_protocol);
/* flags:
* RTM_F_NOTIFY = 0x100: notify user of route change
* RTM_F_CLONED = 0x200: this route is cloned
* RTM_F_EQUALIZE = 0x400: Multipath equalizer: NI
* RTM_F_PREFIX = 0x800: Prefix addresses
*/
printf("flags=%x\n", rm->rtm_flags);
mnl_attr_parse(nlh, sizeof(*rm), data_attr_cb, tb);
switch(rm->rtm_family) {
case AF_INET:
attributes_show_ipv4(tb);
break;
}
return MNL_CB_OK;
}
int main(void)
{
struct mnl_socket *nl;
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
struct rtmsg *rtm;
int ret;
unsigned int seq, portid;
nlh = mnl_nlmsg_put_header(buf);
nlh->nlmsg_type = RTM_GETROUTE;
nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
nlh->nlmsg_seq = seq = time(NULL);
rtm = mnl_nlmsg_put_extra_header(nlh, sizeof(struct rtmsg));
rtm->rtm_family = AF_INET;
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_send");
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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