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
36 /*
37 * Map an interface name into its corresponding index.
38 * Returns 0 on error, as 0 is not a valid index.
39 */
if_nametoindex(const char * ifname)40 unsigned int if_nametoindex(const char *ifname)
41 {
42 int index;
43 int ctl_sock;
44 struct ifreq ifr;
45
46 memset(&ifr, 0, sizeof(struct ifreq));
47 strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
48 ifr.ifr_name[IFNAMSIZ - 1] = 0;
49
50 index = 0;
51 if ((ctl_sock = socket(AF_INET, SOCK_DGRAM, 0)) >= 0) {
52 if (ioctl(ctl_sock, SIOCGIFINDEX, &ifr) >= 0) {
53 index = ifr.ifr_ifindex;
54 }
55 close(ctl_sock);
56 }
57 return index;
58 }
59