92db021bdc
backend and are more robust against SIOCGIFCONF alignment issue. now getifaddrs always takes care of the issue. (sync with kame tree) use weak symbol just in case.
126 lines
3.8 KiB
Groff
126 lines
3.8 KiB
Groff
.\" $NetBSD: if_indextoname.3,v 1.5 2000/04/24 10:24:47 itojun Exp $
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.\" $KAME: if_indextoname.3,v 1.8 2000/04/24 10:12:36 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 "July 11, 1997"
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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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.Fd #include <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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.Aq Pa 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. 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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A value of 0 is returned if the interface is not found or 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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A NULL pointer is returned if the interface is not found or 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 RFC 2553.
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.Sh HISTORY
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The implementation first appeared in BSDI BSD/OS.
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