fusl/src/network/if_nametoindex.c

#define _GNU_SOURCE
#include <net/if.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <string.h>
#include "syscall.h"

unsigned if_nametoindex(const char* name) {
  struct ifreq ifr;
  int fd, r;

  if ((fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0)) < 0)
    return 0;
  strncpy(ifr.ifr_name, name, sizeof ifr.ifr_name);
  r = ioctl(fd, SIOCGIFINDEX, &ifr);
  __syscall(SYS_close, fd);
  return r < 0 ? 0 : ifr.ifr_ifindex;
}