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/* $OpenBSD: if_indextoname.c,v 1.9 2002/03/07 22:40:23 millert Exp $ */
/* $KAME: if_indextoname.c,v 1.6 2000/11/07 22:33:25 jinmei 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_indextoname.c,v 2.3 2000/04/17 22:38:05 dab Exp
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <net/if_dl.h>
#include <net/if.h>
#include <ifaddrs.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
/*
* From RFC 2533:
*
* The second function maps an interface index into its corresponding
* name.
*
* #include <net/if.h>
*
* char *if_indextoname(unsigned int ifindex, char *ifname);
*
* The ifname argument must point to a buffer of at least IF_NAMESIZE
* bytes into which the interface name corresponding to the specified
* index is returned. (IF_NAMESIZE is also defined in <net/if.h> and
* its value includes a terminating null byte at the end of the
* interface name.) This pointer is also the return value of the
* function. If there is no interface corresponding to the specified
* index, NULL is returned, and errno is set to ENXIO, if there was a
* system error (such as running out of memory), if_indextoname returns
* NULL and errno would be set to the proper value (e.g., ENOMEM).
*/
char *
if_indextoname(unsigned int ifindex, char *ifname)
{
struct ifaddrs *ifaddrs, *ifa;
int error = 0;
if (getifaddrs(&ifaddrs) < 0)
return(NULL); /* getifaddrs properly set errno */
for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
if (ifa->ifa_addr &&
ifa->ifa_addr->sa_family == AF_LINK &&
ifindex == ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index)
break;
}
if (ifa == NULL) {
error = ENXIO;
ifname = NULL;
}
else
strlcpy(ifname, ifa->ifa_name, IFNAMSIZ);
freeifaddrs(ifaddrs);
errno = error;
return(ifname);
}
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