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