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.\" @(#)linkaddr.3 8.1 (Berkeley) 7/28/93 36.\" 37.Dd July 28, 1993 38.Dt LINK_ADDR 3 39.Os BSD 4.4 40.Sh NAME 41.Nm link_addr , 42.Nm link_ntoa 43.Nd elementary address specification routines for link level access 44.Sh SYNOPSIS 45.Fd #include <sys/types.h> 46.Fd #include <sys/socket.h> 47.Fd #include <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 4 , 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 97.Fn link_ntoa 98always returns a null terminated string. 99.Fn link_addr 100has no return value. 101(See 102.Sx BUGS . ) 103.Sh SEE ALSO 104.Xr iso 4 , 105.Sh HISTORY 106The 107.Fn link_addr 108and 109.Fn link_ntoa 110functions appeared in 111.Bx 4.3 Reno . 112.Sh BUGS 113The returned values for link_ntoa 114reside in a static memory area. 115.Pp 116The function 117.Fn link_addr 118should diagnose improperly formed input, and there should be an unambiguous 119way to recognize this. 120.Pp 121If the 122.Va sdl_len 123field of the link socket address 124.Fa sdl 125is 0, 126.Fn link_ntoa 127will not insert a colon before the interface address bytes. 128If this translated address is given to 129.Fn link_addr 130without inserting an initial colon, 131the latter will not interpret it correctly. 132