Switch if_nameindex(3) to use the new NET_RT_IFNAMES sysctl to get the

list of interface names. At the same time switch if_nametoindex(3) and
if_indextoname(3) to use if_nameindex(3) instead of getifaddrs(3).
if_nameindex(3) exposes much less then getifaddrs(3) and is allowed by
pledge(2).
With and OK deraadt@

1 files changed, 13 insertions, 18 deletions

diff --git a/src/lib/libc/net/if_nametoindex.c b/src/lib/libc/net/if_nametoindex.c
index 8b2cbf743f..7a4492e37d 100644
--- a/src/lib/libc/net/if_nametoindex.c
+++ b/src/lib/libc/net/if_nametoindex.c
@@ -1,7 +1,8 @@
-/*      $OpenBSD: if_nametoindex.c,v 1.9 2015/09/14 10:47:01 guenther Exp $     */
+/*      $OpenBSD: if_nametoindex.c,v 1.10 2015/10/23 13:09:19 claudio Exp $     */
 /*      $KAME: if_nametoindex.c,v 1.5 2000/11/24 08:04:40 itojun Exp $  */
 
 /*-
+ * Copyright (c) 2015 Claudio Jeker <claudio@openbsd.org>
  * Copyright (c) 1997, 2000
  *      Berkeley Software Design, Inc.  All rights reserved.
  *
@@ -29,8 +30,6 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <net/if.h>
-#include <net/if_dl.h>
-#include <ifaddrs.h>
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
@@ -57,26 +56,22 @@
 unsigned int
 if_nametoindex(const char *ifname)
 {
-        struct ifaddrs *ifaddrs, *ifa;
-        unsigned int ni;
+        struct if_nameindex *ifni, *ifni2;
+        unsigned int index;
 
-        if (getifaddrs(&ifaddrs) < 0)
+        if ((ifni = if_nameindex()) == NULL)
                 return(0);
 
-        ni = 0;
-
-        for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
-                if (ifa->ifa_addr &&
-                    ifa->ifa_addr->sa_family == AF_LINK &&
-                    strcmp(ifa->ifa_name, ifname) == 0) {
-                        ni = ((struct sockaddr_dl*)ifa->ifa_addr)->sdl_index;
-                        break;
+        for (ifni2 = ifni; ifni2->if_index != 0; ifni2++) {
+                if (strcmp(ifni2->if_name, ifname) == 0) {
+                        index = ifni2->if_index;
+                        if_freenameindex(ifni);
+                        return index;
                 }
         }
 
-        freeifaddrs(ifaddrs);
-        if (!ni)
-                errno = ENXIO;
-        return(ni);
+        if_freenameindex(ifni);
+        errno = ENXIO;
+        return 0;
 }
 DEF_WEAK(if_nametoindex);