1 /* $OpenBSD: if_indextoname.c,v 1.9 2002/03/07 22:40:23 millert Exp $ */ 2 /* $KAME: if_indextoname.c,v 1.6 2000/11/07 22:33:25 jinmei Exp $ */ 3 4 /*- 5 * Copyright (c) 1997, 2000 6 * Berkeley Software Design, Inc. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 14 * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * BSDI Id: if_indextoname.c,v 2.3 2000/04/17 22:38:05 dab Exp 27 */ 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <net/if_dl.h> 32 #include <net/if.h> 33 #include <ifaddrs.h> 34 #include <stdlib.h> 35 #include <string.h> 36 #include <errno.h> 37 38 /* 39 * From RFC 2533: 40 * 41 * The second function maps an interface index into its corresponding 42 * name. 43 * 44 * #include <net/if.h> 45 * 46 * char *if_indextoname(unsigned int ifindex, char *ifname); 47 * 48 * The ifname argument must point to a buffer of at least IF_NAMESIZE 49 * bytes into which the interface name corresponding to the specified 50 * index is returned. (IF_NAMESIZE is also defined in <net/if.h> and 51 * its value includes a terminating null byte at the end of the 52 * interface name.) This pointer is also the return value of the 53 * function. If there is no interface corresponding to the specified 54 * index, NULL is returned, and errno is set to ENXIO, if there was a 55 * system error (such as running out of memory), if_indextoname returns 56 * NULL and errno would be set to the proper value (e.g., ENOMEM). 57 */ 58 59 char * 60 if_indextoname(unsigned int ifindex, char *ifname) 61 { 62 struct ifaddrs *ifaddrs, *ifa; 63 int error = 0; 64 65 if (getifaddrs(&ifaddrs) < 0) 66 return(NULL); /* getifaddrs properly set errno */ 67 68 for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) { 69 if (ifa->ifa_addr && 70 ifa->ifa_addr->sa_family == AF_LINK && 71 ifindex == ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index) 72 break; 73 } 74 75 if (ifa == NULL) { 76 error = ENXIO; 77 ifname = NULL; 78 } 79 else 80 strlcpy(ifname, ifa->ifa_name, IFNAMSIZ); 81 82 freeifaddrs(ifaddrs); 83 84 errno = error; 85 return(ifname); 86 } 87