/*      $NetBSD: if_nametoindex.c,v 1.6 2018/08/22 03:12:31 msaitoh Exp $       */
/*      $KAME: if_nametoindex.c,v 1.6 2000/11/24 08:18:54 itojun Exp $  */

/*-
* Copyright (c) 1997, 2000
*      Berkeley Software Design, Inc.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*      BSDI Id: if_nametoindex.c,v 2.3 2000/04/17 22:38:05 dab Exp
*/

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: if_nametoindex.c,v 1.6 2018/08/22 03:12:31 msaitoh Exp $");
#endif /* LIBC_SCCS and not lint */

#ifndef RUMP_ACTION
#include "namespace.h"
#endif
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <ifaddrs.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#ifndef RUMP_ACTION
#ifdef __weak_alias
__weak_alias(if_nametoindex,_if_nametoindex)
#endif
#endif

/*
* From RFC 2553:
*
* 4.1 Name-to-Index
*
*
*    The first function maps an interface name into its corresponding
*    index.
*
*       #include <net/if.h>
*
*       unsigned int  if_nametoindex(const char *ifname);
*
*    If the specified interface name does not exist, the return value is
*    0, and errno is set to ENXIO.  If there was a system error (such as
*    running out of memory), the return value is 0 and errno is set to the
*    proper value (e.g., ENOMEM).
*/

unsigned int
if_nametoindex(const char *ifname)
{
       int s;
       struct ifreq ifr;
       struct ifaddrs *ifaddrs, *ifa;
       unsigned int ni;

       s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
       if (s != -1) {
               memset(&ifr, 0, sizeof(ifr));
               strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
               if (ioctl(s, SIOCGIFINDEX, &ifr) != -1) {
                       close(s);
                       return (ifr.ifr_index);
               }
               close(s);
       }

       if (getifaddrs(&ifaddrs) < 0)
               return 0;

       ni = 0;

       for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
               if (ifa->ifa_addr &&
                   ifa->ifa_addr->sa_family == AF_LINK &&
                   strcmp(ifa->ifa_name, ifname) == 0) {
                       ni = ((struct sockaddr_dl*)
                           (void *)ifa->ifa_addr)->sdl_index;
                       break;
               }
       }

       freeifaddrs(ifaddrs);
       if (!ni)
               errno = ENXIO;
       return ni;
}