141 lines
4.4 KiB
Groff
141 lines
4.4 KiB
Groff
.\" Copyright (c) 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" Donn Seeley at BSDI.
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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: @(#)linkaddr.3 8.1 (Berkeley) 7/28/93
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.\" $FreeBSD$
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.\"
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.Dd June 17, 1996
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.Dt LINK_ADDR 3
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.Os BSD 4.4
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.Sh NAME
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.Nm link_addr ,
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.Nm link_ntoa
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.Nd elementary address specification routines for link level access
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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_dl.h>
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.Ft void
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.Fn link_addr "const char *addr" "struct sockaddr_dl *sdl"
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.Ft char *
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.Fn link_ntoa "const struct sockaddr_dl *sdl"
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.Sh DESCRIPTION
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The routine
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.Fn link_addr
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interprets character strings representing
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link-level addresses, returning binary information suitable
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for use in system calls.
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The routine
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.Fn link_ntoa
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takes
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a link-level
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address and returns an
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.Tn ASCII
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string representing some of the information present,
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including the link level address itself, and the interface name
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or number, if present.
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This facility is experimental and is
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still subject to change.
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.Pp
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For
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.Fn link_addr ,
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the string
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.Fa addr
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may contain
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an optional network interface identifier of the form
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.Dq "name unit-number" ,
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suitable for the first argument to
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.Xr ifconfig 8 ,
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followed in all cases by a colon and
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an interface address in the form of
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groups of hexadecimal digits
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separated by periods.
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Each group represents a byte of address;
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address bytes are filled left to right from
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low order bytes through high order bytes.
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.Pp
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.\" A regular expression may make this format clearer:
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.\" .Bd -literal -offset indent
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.\" ([a-z]+[0-9]+:)?[0-9a-f]+(\e.[0-9a-f]+)*
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.\" .Ed
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.\" .Pp
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Thus
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.Li le0:8.0.9.13.d.30
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represents an ethernet address
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to be transmitted on the first Lance ethernet interface.
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.Pp
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The direct use of these functions is deprecated in favor of the
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.Xr addr2ascii 3
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interface; however, portable programs cannot rely on the latter as it is
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not yet widely implemented.
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.Sh RETURN VALUES
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.Fn link_ntoa
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always returns a null terminated string.
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.Fn link_addr
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has no return value.
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(See
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.Sx BUGS . )
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.Sh SEE ALSO
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.Xr addr2ascii 3
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.\" .Xr iso 4
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.Sh HISTORY
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The
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.Fn link_addr
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and
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.Fn link_ntoa
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functions appeared in
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.Bx 4.3 Reno .
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.Sh BUGS
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The returned values for link_ntoa
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reside in a static memory area.
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.Pp
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The function
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.Fn link_addr
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should diagnose improperly formed input, and there should be an unambiguous
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way to recognize this.
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.Pp
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If the
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.Va sdl_len
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field of the link socket address
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.Fa sdl
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is 0,
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.Fn link_ntoa
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will not insert a colon before the interface address bytes.
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If this translated address is given to
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.Fn link_addr
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without inserting an initial colon,
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the latter will not interpret it correctly.
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