104 lines
2.5 KiB
C
104 lines
2.5 KiB
C
/* Copyright (C) 1999 Free Software Foundation, Inc.
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Contributed by Andreas Jaeger <aj@suse.de>.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <net/if.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include "kernel-features.h"
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/* Variable to signal whether SIOCGIFCONF is not available. */
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#if __ASSUME_SIOCGIFNAME == 0
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static int old_siocgifconf;
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#else
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# define old_siocgifconf 0
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#endif
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static inline void
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__ifreq (struct ifreq **ifreqs, int *num_ifs)
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{
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int fd = __opensock ();
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struct ifconf ifc;
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int rq_len;
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int nifs;
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# define RQ_IFS 4
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if (fd < 0)
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{
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*num_ifs = 0;
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*ifreqs = NULL;
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return;
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}
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ifc.ifc_buf = NULL;
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/* We may be able to get the needed buffer size directly, rather than
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guessing. */
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if (! old_siocgifconf)
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{
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ifc.ifc_buf = NULL;
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ifc.ifc_len = 0;
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if (__ioctl (fd, SIOCGIFCONF, &ifc) < 0 || ifc.ifc_len == 0)
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{
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# if __ASSUME_SIOCGIFNAME == 0
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old_siocgifconf = 1;
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# endif
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rq_len = RQ_IFS * sizeof (struct ifreq);
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}
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else
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rq_len = ifc.ifc_len;
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}
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else
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rq_len = RQ_IFS * sizeof (struct ifreq);
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/* Read all the interfaces out of the kernel. */
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do
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{
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ifc.ifc_len = rq_len;
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ifc.ifc_buf = realloc (ifc.ifc_buf, ifc.ifc_len);
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if (ifc.ifc_buf == NULL || __ioctl (fd, SIOCGIFCONF, &ifc) < 0)
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{
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if (ifc.ifc_buf)
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free (ifc.ifc_buf);
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__close (fd);
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*num_ifs = 0;
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*ifreqs = NULL;
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return;
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}
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rq_len *= 2;
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}
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while (ifc.ifc_len == rq_len && old_siocgifconf);
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nifs = ifc.ifc_len / sizeof (struct ifreq);
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__close (fd);
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*num_ifs = nifs;
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*ifreqs = realloc (ifc.ifc_buf, nifs * sizeof (struct ifreq));
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}
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static inline void
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__if_freereq (struct ifreq *ifreqs)
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{
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free (ifreqs);
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}
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