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. 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.Dd February 28, 2007 32.Dt LINK_ADDR 3 33.Os 34.Sh NAME 35.Nm link_addr , 36.Nm link_ntoa 37.Nd elementary address specification routines for link level access 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In sys/types.h 42.In sys/socket.h 43.In net/if_dl.h 44.Ft void 45.Fn link_addr "const char *addr" "struct sockaddr_dl *sdl" 46.Ft char * 47.Fn link_ntoa "const struct sockaddr_dl *sdl" 48.Sh DESCRIPTION 49The routine 50.Fn link_addr 51interprets character strings representing 52link-level addresses, returning binary information suitable 53for use in system calls. 54The routine 55.Fn link_ntoa 56takes 57a link-level 58address and returns an 59.Tn ASCII 60string representing some of the information present, 61including the link level address itself, and the interface name 62or number, if present. 63This facility is experimental and is 64still subject to change. 65.Pp 66For 67.Fn link_addr , 68the string 69.Fa addr 70may contain 71an optional network interface identifier of the form 72.Dq "name unit-number" , 73suitable for the first argument to 74.Xr ifconfig 8 , 75followed in all cases by a colon and 76an interface address in the form of 77groups of hexadecimal digits 78separated by periods. 79Each group represents a byte of address; 80address bytes are filled left to right from 81low order bytes through high order bytes. 82.Pp 83.\" A regular expression may make this format clearer: 84.\" .Bd -literal -offset indent 85.\" ([a-z]+[0-9]+:)?[0-9a-f]+(\e.[0-9a-f]+)* 86.\" .Ed 87.\" .Pp 88Thus 89.Li le0:8.0.9.13.d.30 90represents an ethernet address 91to be transmitted on the first Lance ethernet interface. 92.Sh RETURN VALUES 93The 94.Fn link_ntoa 95function 96always returns a null terminated string. 97The 98.Fn link_addr 99function 100has no return value. 101(See 102.Sx BUGS . ) 103.Sh SEE ALSO 104.Xr getnameinfo 3 105.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