1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Donn Seeley at BSDI. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 4. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" From: @(#)linkaddr.3 8.1 (Berkeley) 7/28/93 32.\" $FreeBSD: src/lib/libc/net/linkaddr.3,v 1.16 2007/02/28 21:18:38 bms Exp $ 33.\" $DragonFly: src/lib/libc/net/linkaddr.3,v 1.3 2008/11/23 21:55:52 swildner Exp $ 34.\" 35.Dd February 28, 2007 36.Dt LINK_ADDR 3 37.Os 38.Sh NAME 39.Nm link_addr , 40.Nm link_ntoa 41.Nd elementary address specification routines for link level access 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In sys/types.h 46.In sys/socket.h 47.In net/if_dl.h 48.Ft void 49.Fn link_addr "const char *addr" "struct sockaddr_dl *sdl" 50.Ft char * 51.Fn link_ntoa "const struct sockaddr_dl *sdl" 52.Sh DESCRIPTION 53The routine 54.Fn link_addr 55interprets character strings representing 56link-level addresses, returning binary information suitable 57for use in system calls. 58The routine 59.Fn link_ntoa 60takes 61a link-level 62address and returns an 63.Tn ASCII 64string representing some of the information present, 65including the link level address itself, and the interface name 66or number, if present. 67This facility is experimental and is 68still subject to change. 69.Pp 70For 71.Fn link_addr , 72the string 73.Fa addr 74may contain 75an optional network interface identifier of the form 76.Dq "name unit-number" , 77suitable for the first argument to 78.Xr ifconfig 8 , 79followed in all cases by a colon and 80an interface address in the form of 81groups of hexadecimal digits 82separated by periods. 83Each group represents a byte of address; 84address bytes are filled left to right from 85low order bytes through high order bytes. 86.Pp 87.\" A regular expression may make this format clearer: 88.\" .Bd -literal -offset indent 89.\" ([a-z]+[0-9]+:)?[0-9a-f]+(\e.[0-9a-f]+)* 90.\" .Ed 91.\" .Pp 92Thus 93.Li le0:8.0.9.13.d.30 94represents an ethernet address 95to be transmitted on the first Lance ethernet interface. 96.Sh RETURN VALUES 97The 98.Fn link_ntoa 99function 100always returns a null terminated string. 101The 102.Fn link_addr 103function 104has no return value. 105(See 106.Sx BUGS . ) 107.Sh SEE ALSO 108.Xr getnameinfo 3 109.Sh HISTORY 110The 111.Fn link_addr 112and 113.Fn link_ntoa 114functions appeared in 115.Bx 4.3 Reno . 116.Sh BUGS 117The returned values for 118.Fn link_ntoa 119reside in a static memory area. 120.Pp 121The function 122.Fn link_addr 123should diagnose improperly formed input, and there should be an unambiguous 124way to recognize this. 125.Pp 126If the 127.Va sdl_len 128field of the link socket address 129.Fa sdl 130is 0, 131.Fn link_ntoa 132will not insert a colon before the interface address bytes. 133If this translated address is given to 134.Fn link_addr 135without inserting an initial colon, 136the latter will not interpret it correctly. 137