/* Copyright (C) 1997, 1998 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with the GNU C Library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include <errno.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <net/if.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <bits/libc-lock.h> /* Try to get a socket to talk to the kernel. */ #if defined SIOGIFINDEX || defined SIOGIFNAME static int internal_function opensock (void) { /* Cache the last AF that worked, to avoid many redundant calls to socket(). */ static int sock_af = -1; int fd = -1; __libc_lock_define_initialized (static, lock); if (sock_af != -1) { fd = socket (sock_af, SOCK_DGRAM, 0); if (fd != -1) return fd; } __libc_lock_lock (lock); if (sock_af != -1) fd = socket (sock_af, SOCK_DGRAM, 0); if (fd == -1) { fd = socket (sock_af = AF_INET6, SOCK_DGRAM, 0); if (fd < 0) fd = socket (sock_af = AF_INET, SOCK_DGRAM, 0); if (fd < 0) fd = socket (sock_af = AF_IPX, SOCK_DGRAM, 0); if (fd < 0) fd = socket (sock_af = AF_AX25, SOCK_DGRAM, 0); if (fd < 0) fd = socket (sock_af = AF_APPLETALK, SOCK_DGRAM, 0); } __libc_lock_unlock (lock); return fd; } #endif unsigned int if_nametoindex (const char *ifname) { #ifndef SIOGIFINDEX __set_errno (ENOSYS); return 0; #else struct ifreq ifr; int fd = opensock (); if (fd < 0) return 0; strncpy (ifr.ifr_name, ifname, sizeof (ifr.ifr_name)); if (ioctl (fd, SIOGIFINDEX, &ifr) < 0) { int saved_errno = errno; close (fd); if (saved_errno == EINVAL) __set_errno (ENOSYS); return 0; } close (fd); return ifr.ifr_ifindex; #endif } void if_freenameindex (struct if_nameindex *ifn) { struct if_nameindex *ptr = ifn; while (ptr->if_name || ptr->if_index) { if (ptr->if_name) free (ptr->if_name); ++ptr; } free (ifn); } struct if_nameindex * if_nameindex (void) { #ifndef SIOGIFINDEX __set_errno (ENOSYS); return NULL; #else int fd = opensock (); struct ifconf ifc; unsigned int nifs, i; int rq_len; struct if_nameindex *idx = NULL; static int new_siocgifconf = 1; #define RQ_IFS 4 if (fd < 0) return NULL; ifc.ifc_buf = NULL; /* We may be able to get the needed buffer size directly, rather than guessing. */ if (new_siocgifconf) { ifc.ifc_buf = NULL; ifc.ifc_len = 0; if (ioctl (fd, SIOCGIFCONF, &ifc) < 0 || ifc.ifc_len == 0) { new_siocgifconf = 0; rq_len = RQ_IFS * sizeof (struct ifreq); } else rq_len = ifc.ifc_len; } else rq_len = RQ_IFS * sizeof (struct ifreq); /* Read all the interfaces out of the kernel. */ do { ifc.ifc_buf = alloca (ifc.ifc_len = rq_len); if ((ifc.ifc_buf == NULL) || (ioctl (fd, SIOCGIFCONF, &ifc) < 0)) { close (fd); return NULL; } rq_len *= 2; } while (ifc.ifc_len == rq_len && new_siocgifconf == 0); nifs = ifc.ifc_len / sizeof (struct ifreq); idx = malloc ((nifs + 1) * sizeof (struct if_nameindex)); if (idx == NULL) { close (fd); return NULL; } for (i = 0; i < nifs; ++i) { struct ifreq *ifr = &ifc.ifc_req[i]; idx[i].if_name = __strdup (ifr->ifr_name); if (idx[i].if_name == NULL || ioctl (fd, SIOGIFINDEX, ifr) < 0) { int saved_errno = errno; unsigned int j; for (j = 0; j < i; ++j) free (idx[j].if_name); free (idx); close (fd); if (saved_errno == EINVAL) __set_errno (ENOSYS); return NULL; } idx[i].if_index = ifr->ifr_ifindex; } idx[i].if_index = 0; idx[i].if_name = NULL; close (fd); return idx; #endif } char * if_indextoname (unsigned int ifindex, char *ifname) { #ifndef SIOGIFINDEX __set_errno (ENOSYS); return NULL; #else struct if_nameindex *idx; struct if_nameindex *p; char *result = NULL; #ifdef SIOGIFNAME /* We may be able to do the conversion directly, rather than searching a list. This ioctl is not present in kernels before version 2.1.50. */ struct ifreq ifr; int fd; static int siogifname_works = 1; if (siogifname_works) { int serrno = errno; fd = opensock (); if (fd < 0) return NULL; ifr.ifr_ifindex = ifindex; if (ioctl (fd, SIOGIFNAME, &ifr) < 0) { if (errno == EINVAL) siogifname_works = 0; /* Don't make the same mistake twice. */ } else { close (fd); return strncpy (ifname, ifr.ifr_name, IFNAMSIZ); } close (fd); __set_errno (serrno); } #endif idx = if_nameindex (); if (idx != NULL) { for (p = idx; p->if_index || p->if_name; ++p) if (p->if_index == ifindex) { result = strncpy (ifname, p->if_name, IFNAMSIZ); break; } if_freenameindex (idx); } return result; #endif }