if_nametoindex.c raw

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