36dcd97de3
If the index we're trying to convert is 0 we can avoid a potentially expensive call to getifaddrs(). No interface has an ifindex of zero, so we can handle this as an error: set the errno to ENXIO and return NULL. Submitted by: Nick Rogers Reviewed by: lutz at donnerhacke.de MFC after: 2 weeks Sponsored by: RG Nets Differential Revision: https://reviews.freebsd.org/D24524
96 lines
2.9 KiB
C
96 lines
2.9 KiB
C
/* $KAME: if_indextoname.c,v 1.7 2000/11/08 03:09:30 itojun Exp $ */
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/*-
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* SPDX-License-Identifier: BSD-1-Clause
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*
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* Copyright (c) 1997, 2000
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* Berkeley Software Design, Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* BSDI Id: if_indextoname.c,v 2.3 2000/04/17 22:38:05 dab Exp
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <net/if_dl.h>
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#include <net/if.h>
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#include <ifaddrs.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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/*
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* From RFC 2533:
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*
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* The second function maps an interface index into its corresponding
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* name.
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*
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* #include <net/if.h>
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*
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* char *if_indextoname(unsigned int ifindex, char *ifname);
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*
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* The ifname argument must point to a buffer of at least IF_NAMESIZE
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* bytes into which the interface name corresponding to the specified
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* index is returned. (IF_NAMESIZE is also defined in <net/if.h> and
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* its value includes a terminating null byte at the end of the
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* interface name.) This pointer is also the return value of the
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* function. If there is no interface corresponding to the specified
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* index, NULL is returned, and errno is set to ENXIO, if there was a
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* system error (such as running out of memory), if_indextoname returns
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* NULL and errno would be set to the proper value (e.g., ENOMEM).
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*/
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char *
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if_indextoname(unsigned int ifindex, char *ifname)
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{
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struct ifaddrs *ifaddrs, *ifa;
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int error = 0;
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if (ifindex == 0) {
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errno = ENXIO;
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return(NULL);
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}
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if (getifaddrs(&ifaddrs) < 0)
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return(NULL); /* getifaddrs properly set errno */
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for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
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if (ifa->ifa_addr &&
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ifa->ifa_addr->sa_family == AF_LINK &&
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ifindex == LLINDEX((struct sockaddr_dl*)ifa->ifa_addr))
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break;
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}
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if (ifa == NULL) {
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error = ENXIO;
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ifname = NULL;
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}
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else
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strncpy(ifname, ifa->ifa_name, IFNAMSIZ);
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freeifaddrs(ifaddrs);
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errno = error;
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return(ifname);
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}
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