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.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" From: @(#)linkaddr.3 8.1 (Berkeley) 7/28/93 36.\" $FreeBSD$ 37.\" 38.Dd June 17, 1996 39.Dt LINK_ADDR 3 40.Os 41.Sh NAME 42.Nm link_addr , 43.Nm link_ntoa 44.Nd elementary address specification routines for link level access 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.In sys/types.h 49.In sys/socket.h 50.In net/if_dl.h 51.Ft void 52.Fn link_addr "const char *addr" "struct sockaddr_dl *sdl" 53.Ft char * 54.Fn link_ntoa "const struct sockaddr_dl *sdl" 55.Sh DESCRIPTION 56The routine 57.Fn link_addr 58interprets character strings representing 59link-level addresses, returning binary information suitable 60for use in system calls. 61The routine 62.Fn link_ntoa 63takes 64a link-level 65address and returns an 66.Tn ASCII 67string representing some of the information present, 68including the link level address itself, and the interface name 69or number, if present. 70This facility is experimental and is 71still subject to change. 72.Pp 73For 74.Fn link_addr , 75the string 76.Fa addr 77may contain 78an optional network interface identifier of the form 79.Dq "name unit-number" , 80suitable for the first argument to 81.Xr ifconfig 8 , 82followed in all cases by a colon and 83an interface address in the form of 84groups of hexadecimal digits 85separated by periods. 86Each group represents a byte of address; 87address bytes are filled left to right from 88low order bytes through high order bytes. 89.Pp 90.\" A regular expression may make this format clearer: 91.\" .Bd -literal -offset indent 92.\" ([a-z]+[0-9]+:)?[0-9a-f]+(\e.[0-9a-f]+)* 93.\" .Ed 94.\" .Pp 95Thus 96.Li le0:8.0.9.13.d.30 97represents an ethernet address 98to be transmitted on the first Lance ethernet interface. 99.Pp 100The direct use of these functions is deprecated in favor of the 101.Xr addr2ascii 3 102interface; however, portable programs cannot rely on the latter as it is 103not yet widely implemented. 104.Sh RETURN VALUES 105The 106.Fn link_ntoa 107function 108always returns a null terminated string. 109The 110.Fn link_addr 111function 112has no return value. 113(See 114.Sx BUGS . ) 115.Sh SEE ALSO 116.Xr addr2ascii 3 117.\" .Xr iso 4 118.Sh HISTORY 119The 120.Fn link_addr 121and 122.Fn link_ntoa 123functions appeared in 124.Bx 4.3 Reno . 125.Sh BUGS 126The returned values for link_ntoa 127reside in a static memory area. 128.Pp 129The function 130.Fn link_addr 131should diagnose improperly formed input, and there should be an unambiguous 132way to recognize this. 133.Pp 134If the 135.Va sdl_len 136field of the link socket address 137.Fa sdl 138is 0, 139.Fn link_ntoa 140will not insert a colon before the interface address bytes. 141If this translated address is given to 142.Fn link_addr 143without inserting an initial colon, 144the latter will not interpret it correctly. 145