1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <string.h> 30 #include <unistd.h> 31 #include <linux/sockios.h> 32 #include <net/if.h> 33 #include <sys/socket.h> 34 #include <sys/ioctl.h> 35 #include <errno.h> 36 37 /* 38 * Map an interface index into its name. 39 * Returns NULL on error. 40 */ 41 char* 42 if_indextoname(unsigned ifindex, char *ifname) 43 { 44 int index; 45 int ctl_sock; 46 struct ifreq ifr; 47 char* ret = NULL; 48 49 memset(&ifr, 0, sizeof(struct ifreq)); 50 ifr.ifr_ifindex = ifindex; 51 52 if ((ctl_sock = socket(AF_INET, SOCK_DGRAM, 0)) >= 0) { 53 if (ioctl(ctl_sock, SIOCGIFNAME, &ifr) >= 0) { 54 ret = strncpy (ifname, ifr.ifr_name, IFNAMSIZ); 55 } else { 56 /* Posix requires ENXIO */ 57 if (errno == ENODEV) 58 errno = ENXIO; 59 } 60 close(ctl_sock); 61 } 62 return ret; 63 } 64
