147 lines
4.5 KiB
Groff
147 lines
4.5 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. 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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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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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.\" From: @(#)rcmd.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd May 21, 1998
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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 convert interface index to name, and vice versa
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/socket.h>
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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 functions map interface index to readable interface name
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.Po
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such as
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.Li ``lo0''
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.Pc
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, and vice versa.
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.Pp
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.Fn if_nametoindex
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converts readable interface name to interface index
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.Pp positive integer value .
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If the specified interface does not exist, 0 will be returned.
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.Pp
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.Fn if_indextoname
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converts interface index to readable interface name.
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The
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.Fa ifname
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argument must point to a buffer of at least
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.Dv IF_NAMESIZE
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bytes into which the interface name corresponding to the specified index is
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returned.
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.Po
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.Dv IF_NAMESIZE
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is also defined in
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.Li <net/if.h>
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and its value includes a terminating null byte at the end of the
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interface name.
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.Pc
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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 index,
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.Dv NULL
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is returned.
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.Pp
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.Fn if_nameindex
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returns an array of
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.Fa if_nameindex
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structures.
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.Fa if_nametoindex
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is also defined in
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.Li <net/if.h> ,
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and is as follows:
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.Bd -literal -offset
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struct if_nameindex {
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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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};
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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
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an
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.Fa if_index
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of 0 and an
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.Fa if_name
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of
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.Dv NULL .
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The function returns a
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.Dv NULL
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pointer upon an error.
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The memory used for this array of structures along with the interface
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names pointed to by the
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.Fa if_name
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members is obtained dynamically.
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This memory is freed by the
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.Fn if_freenameindex
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function.
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.Pp
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.Fn if_freenameindex
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takes a pointer that was returned by
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.Fn if_nameindex
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as argument
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.Pq Fa ptr ,
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and it reclaims the region allocated.
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.Sh DIAGNOSTICS
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.Fn if_nametoindex
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returns 0 on error, positive integer on success.
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.Fn if_indextoname
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and
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.Fn if_nameindex
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return
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.Dv NULL
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on errors.
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.Sh SEE ALSO
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R. Gilligan, S. Thomson, J. Bound, and W. Stevens,
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``Basic Socket Interface Extensions for IPv6,'' RFC2553, March 1999.
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.Sh HISTORY
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The implementation first appeared in WIDE Hydrangea IPv6 protocol stack kit.
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.Sh STANDARDS
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These functions are defined in ``Basic Socket Interface Extensions for IPv6''
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.Pq RFC2533 .
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