139 lines
3.9 KiB
Groff
139 lines
3.9 KiB
Groff
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.\" $NetBSD: if_indextoname.3,v 1.12 2010/03/22 19:30:54 joerg Exp $
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.\" $KAME: if_indextoname.3,v 1.10 2000/11/24 08:13:51 itojun Exp $
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.\" BSDI Id: if_indextoname.3,v 2.2 2000/04/17 22:38:05 dab Exp
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.\"
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.\" Copyright (c) 1997, 2000
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.\" Berkeley Software Design, Inc. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd March 11, 2005
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.Dt IF_NAMETOINDEX 3
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.Os
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.Sh NAME
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.Nm if_nametoindex ,
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.Nm if_indextoname ,
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.Nm if_nameindex ,
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.Nm if_freenameindex
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.Nd provide mappings between interface names and indexes
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.Sh SYNOPSIS
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.In net/if.h
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.Ft unsigned int
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.Fn if_nametoindex "const char *ifname"
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.Ft char *
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.Fn if_indextoname "unsigned int ifindex" "char *ifname"
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.Ft struct if_nameindex *
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.Fn if_nameindex "void"
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.Ft void
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.Fn if_freenameindex "struct if_nameindex *ptr"
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.Sh DESCRIPTION
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The
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.Fn if_nametoindex
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function maps the interface name specified in
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.Ar ifname
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to its corresponding index.
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If the specified interface does not exist, it returns 0.
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.Pp
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The
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.Fn if_indextoname
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function maps the interface index specified in
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.Ar ifindex
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to it corresponding name, which is copied into the
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buffer pointed to by
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.Ar ifname ,
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which must be of at least IFNAMSIZ bytes.
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This pointer is also the return value of the function.
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If there is no interface corresponding to the specified
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index, NULL is returned.
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.Pp
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The
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.Fn if_nameindex
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function returns an array of
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.Nm if_nameindex
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structures, one structure per interface, as
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defined in the include file
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.In net/if.h .
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The
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.Nm if_nameindex
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structure contains at least the following entries:
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.Bd -literal
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unsigned int if_index; /* 1, 2, ... */
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char *if_name; /* null terminated name: "le0", ... */
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.Ed
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.Pp
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The end of the array of structures is indicated by a structure with an
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.Nm if_index
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of 0 and an
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.Nm if_name
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of NULL.
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A NULL pointer is returned upon an error.
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.Pp
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The
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.Fn if_freenameindex
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function frees the dynamic memory that was
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allocated by
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.Fn if_nameindex .
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.Sh RETURN VALUES
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Upon successful completion,
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.Fn if_nametoindex
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returns the index number of the interface.
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If the interface is not found, a value of 0 is returned and
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.Va errno
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is set to
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.Er ENXIO .
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A value of 0 is also returned if an error
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occurs while retrieving the list of interfaces via
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.Xr getifaddrs 3 .
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.Pp
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Upon successful completion,
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.Fn if_indextoname
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returns
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.Ar ifname .
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If the interface is not found, a NULL pointer is returned and
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.Va errno
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is set to
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.Er ENXIO .
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A NULL pointer is also returned if an error
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occurs while retrieving the list of interfaces via
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.Xr getifaddrs 3 .
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.Pp
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The
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.Fn if_nameindex
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returns a NULL pointer if an error
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occurs while retrieving the list of interfaces via
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.Xr getifaddrs 3 ,
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or if sufficient memory cannot be allocated.
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.Sh SEE ALSO
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.Xr getifaddrs 3 ,
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.Xr networking 4
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.Sh STANDARDS
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The
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.Fn if_nametoindex ,
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.Fn if_indextoname ,
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.Fn if_nameindex ,
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and
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.Fn if_freenameindex
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functions conform to
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.St -p1003.1-2001 ,
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.St -xns5.2 ,
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and RFC 3493.
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.Sh HISTORY
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The implementation first appeared in
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.Bsx .
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