rtnl-link-set.c

/* This example is placed in the public domain. */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <time.h>

#include <libmnl/libmnl.h>
#include <linux/if.h>
#include <linux/if_link.h>
#include <linux/rtnetlink.h>

int main(int argc, char *argv[])
{
        struct mnl_socket *nl;
        char buf[MNL_SOCKET_BUFFER_SIZE];
        struct nlmsghdr *nlh;
        struct ifinfomsg *ifm;
        int ret;
        unsigned int seq, portid, change = 0, flags = 0;

        if (argc != 3) {
                printf("Usage: %s [ifname] [up|down]\n", argv[0]);
                exit(EXIT_FAILURE);
        }

        if (strncasecmp(argv[2], "up", strlen("up")) == 0) {
                change |= IFF_UP;
                flags |= IFF_UP;
        } else if (strncasecmp(argv[2], "down", strlen("down")) == 0) {
                change |= IFF_UP;
                flags &= ~IFF_UP;
        } else {
                fprintf(stderr, "%s is not `up' nor `down'\n", argv[2]);
                exit(EXIT_FAILURE);
        }

        nlh = mnl_nlmsg_put_header(buf);
        nlh->nlmsg_type = RTM_NEWLINK;
        nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
        nlh->nlmsg_seq = seq = time(NULL);
        ifm = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifm));
        ifm->ifi_family = AF_UNSPEC;
        ifm->ifi_change = change;
        ifm->ifi_flags = flags;

        mnl_attr_put_str(nlh, IFLA_IFNAME, argv[1]);

        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);

        mnl_nlmsg_fprintf(stdout, nlh, nlh->nlmsg_len,
                          sizeof(struct ifinfomsg));

        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));
        if (ret == -1) {
                perror("mnl_socket_recvfrom");
                exit(EXIT_FAILURE);
        }

        ret = mnl_cb_run(buf, ret, seq, portid, NULL, NULL);
        if (ret == -1){
                perror("mnl_cb_run");
                exit(EXIT_FAILURE);
        }

        mnl_socket_close(nl);

        return 0;
}