1 /* $KAME: if_indextoname.c,v 1.7 2000/11/08 03:09:30 itojun Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-1-Clause 5 * 6 * Copyright (c) 1997, 2000 7 * Berkeley Software Design, Inc. All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 * BSDI Id: if_indextoname.c,v 2.3 2000/04/17 22:38:05 dab Exp 28 */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/types.h> 34 #include <sys/socket.h> 35 #include <net/if_dl.h> 36 #include <net/if.h> 37 #include <ifaddrs.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <errno.h> 41 42 /* 43 * From RFC 2553: 44 * 45 * The second function maps an interface index into its corresponding 46 * name. 47 * 48 * #include <net/if.h> 49 * 50 * char *if_indextoname(unsigned int ifindex, char *ifname); 51 * 52 * The ifname argument must point to a buffer of at least IF_NAMESIZE 53 * bytes into which the interface name corresponding to the specified 54 * index is returned. (IF_NAMESIZE is also defined in <net/if.h> and 55 * its value includes a terminating null byte at the end of the 56 * interface name.) This pointer is also the return value of the 57 * function. If there is no interface corresponding to the specified 58 * index, NULL is returned, and errno is set to ENXIO, if there was a 59 * system error (such as running out of memory), if_indextoname returns 60 * NULL and errno would be set to the proper value (e.g., ENOMEM). 61 */ 62 63 char * 64 if_indextoname(unsigned int ifindex, char *ifname) 65 { 66 struct ifaddrs *ifaddrs, *ifa; 67 int error = 0; 68 69 if (ifindex == 0) { 70 errno = ENXIO; 71 return(NULL); 72 } 73 74 if (getifaddrs(&ifaddrs) < 0) 75 return(NULL); /* getifaddrs properly set errno */ 76 77 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { 78 if (ifa->ifa_addr && 79 ifa->ifa_addr->sa_family == AF_LINK && 80 ifindex == LLINDEX((struct sockaddr_dl*)ifa->ifa_addr)) 81 break; 82 } 83 84 if (ifa == NULL) { 85 error = ENXIO; 86 ifname = NULL; 87 } 88 else 89 strncpy(ifname, ifa->ifa_name, IFNAMSIZ); 90 91 freeifaddrs(ifaddrs); 92 93 errno = error; 94 return(ifname); 95 } 96