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 #include <sys/types.h> 32 #include <sys/socket.h> 33 #include <net/if_dl.h> 34 #include <net/if.h> 35 #include <ifaddrs.h> 36 #include <stdlib.h> 37 #include <string.h> 38 #include <errno.h> 39 40 /* 41 * From RFC 2553: 42 * 43 * The second function maps an interface index into its corresponding 44 * name. 45 * 46 * #include <net/if.h> 47 * 48 * char *if_indextoname(unsigned int ifindex, char *ifname); 49 * 50 * The ifname argument must point to a buffer of at least IF_NAMESIZE 51 * bytes into which the interface name corresponding to the specified 52 * index is returned. (IF_NAMESIZE is also defined in <net/if.h> and 53 * its value includes a terminating null byte at the end of the 54 * interface name.) This pointer is also the return value of the 55 * function. If there is no interface corresponding to the specified 56 * index, NULL is returned, and errno is set to ENXIO, if there was a 57 * system error (such as running out of memory), if_indextoname returns 58 * NULL and errno would be set to the proper value (e.g., ENOMEM). 59 */ 60 61 char * 62 if_indextoname(unsigned int ifindex, char *ifname) 63 { 64 struct ifaddrs *ifaddrs, *ifa; 65 int error = 0; 66 67 if (ifindex == 0) { 68 errno = ENXIO; 69 return(NULL); 70 } 71 72 if (getifaddrs(&ifaddrs) < 0) 73 return(NULL); /* getifaddrs properly set errno */ 74 75 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { 76 if (ifa->ifa_addr && 77 ifa->ifa_addr->sa_family == AF_LINK && 78 ifindex == LLINDEX((struct sockaddr_dl*)ifa->ifa_addr)) 79 break; 80 } 81 82 if (ifa == NULL) { 83 error = ENXIO; 84 ifname = NULL; 85 } 86 else 87 strncpy(ifname, ifa->ifa_name, IFNAMSIZ); 88 89 freeifaddrs(ifaddrs); 90 91 errno = error; 92 return(ifname); 93 } 94