1.\" $NetBSD: linkaddr.3,v 1.8 2002/02/07 07:00:21 ross Exp $ 2.\" 3.\" Copyright (c) 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Donn Seeley at BSDI. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the University of 20.\" California, Berkeley and its contributors. 21.\" 4. Neither the name of the University nor the names of its contributors 22.\" may be used to endorse or promote products derived from this software 23.\" without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35.\" SUCH DAMAGE. 36.\" 37.\" @(#)linkaddr.3 8.1 (Berkeley) 7/28/93 38.\" 39.Dd July 28, 1993 40.Dt LINK_ADDR 3 41.Os 42.Sh NAME 43.Nm link_addr , 44.Nm link_ntoa 45.Nd elementary address specification routines for link level access 46.Sh LIBRARY 47.Lb libc 48.Sh SYNOPSIS 49.Fd #include \*[Lt]sys/types.h\*[Gt] 50.Fd #include \*[Lt]sys/socket.h\*[Gt] 51.Fd #include \*[Lt]net/if_dl.h\*[Gt] 52.Ft void 53.Fn link_addr "const char *addr" "struct sockaddr_dl *sdl" 54.Ft char * 55.Fn link_ntoa "const struct sockaddr_dl *sdl" 56.Sh DESCRIPTION 57The routine 58.Fn link_addr 59interprets character strings representing link-level addresses, 60returning binary information suitable for use in system calls. 61The routine 62.Fn link_ntoa 63takes a link-level address and returns an 64.Tn ASCII 65string representing some of the information present, including the 66link level address itself, and the interface name or number, if present. 67This facility is experimental and is still subject to change. 68.Pp 69Prior to a call to 70.Fn link_addr , 71.Fa sdl-\*[Gt]sdl_len 72must be initialized to the size of the link-level socket structure, 73typically 74.Fa sizeof(struct sockaddr_dl) . 75.Pp 76For 77.Fn link_addr , 78the string 79.Fa addr 80may contain 81an optional network interface identifier of the form 82.Dq "name unit-number" , 83suitable for the first argument to 84.Xr ifconfig 8 , 85followed in all cases by a colon and 86an interface address in the form of 87groups of hexadecimal digits 88separated by periods. 89Each group represents a byte of address; 90address bytes are filled left to right from 91low order bytes through high order bytes. 92.Pp 93.\" A regular expression may make this format clearer: 94.\" .Bd -literal -offset indent 95.\" ([a-z]+[0-9]+:)?[0-9a-f]+(\e.[0-9a-f]+)* 96.\" .Ed 97.\" .Pp 98Thus 99.Li le0:8.0.9.13.d.30 100represents an ethernet address 101to be transmitted on the first Lance ethernet interface. 102.Sh RETURN VALUES 103.Fn link_ntoa 104always returns a null terminated string. 105.Fn link_addr 106has no return value (See 107.Sx BUGS ) . 108.Sh SEE ALSO 109.Xr ethers 3 , 110.Xr iso 4 111.Sh HISTORY 112The 113.Fn link_addr 114and 115.Fn link_ntoa 116functions appeared in 117.Bx 4.3 Reno . 118.Sh BUGS 119The returned values for 120.Fn link_ntoa 121reside in a static memory area. 122.Pp 123The function 124.Fn link_addr 125should diagnose improperly formed input, and there should be an unambiguous 126way to recognize this. 127.Pp 128If the 129.Va sdl_len 130field of the link socket address 131.Fa sdl 132is 0, 133.Fn link_ntoa 134will not insert a colon before the interface address bytes. 135If this translated address is given to 136.Fn link_addr 137without inserting an initial colon, 138the latter will not interpret it correctly. 139