1#define _GNU_SOURCE
2#include <net/if.h>
3#include <string.h>
4#include <sys/ioctl.h>
5#include <sys/socket.h>
6#include <unistd.h>
7
8unsigned if_nametoindex(const char* name) {
9    struct ifreq ifr;
10    int fd, r;
11
12    if ((fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0)) < 0)
13        return 0;
14    strncpy(ifr.ifr_name, name, sizeof ifr.ifr_name);
15    r = ioctl(fd, SIOCGIFINDEX, &ifr);
16    close(fd);
17    return r < 0 ? 0 : ifr.ifr_ifindex;
18}
19