1.\" $OpenBSD: inet_lnaof.3,v 1.4 2019/08/30 20:06:07 jmc Exp $ 2.\" $NetBSD: inet.3,v 1.7 1997/06/18 02:25:24 lukem Exp $ 3.\" 4.\" Copyright (c) 1983, 1990, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 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.\" @(#)inet.3 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: August 30 2019 $ 34.Dt INET_LNAOF 3 35.Os 36.Sh NAME 37.Nm inet_makeaddr , 38.Nm inet_netof , 39.Nm inet_lnaof 40.Nd routines for manipulating classful Internet Protocol version 4 (IPv4) addresses 41.Sh SYNOPSIS 42.In arpa/inet.h 43.Ft struct in_addr 44.Fn inet_makeaddr "in_addr_t net" "in_addr_t lna" 45.Ft in_addr_t 46.Fn inet_netof "struct in_addr in" 47.Ft in_addr_t 48.Fn inet_lnaof "struct in_addr in" 49.Sh DESCRIPTION 50As originally designed, 51IP version 4 split each address into a network part and local network 52address part, encoding that split into the address itself. 53It is frequency-encoded; 54the most-significant bit is clear in Class A addresses, 55in which the high-order 8 bits are the network number. 56Class B addresses use the high-order 16 bits as the network field, 57and Class C addresses have a 24-bit network part. 58.Pp 59The routine 60.Fn inet_makeaddr 61takes an Internet network number and a local 62network address and constructs an Internet address 63from it. 64.Pp 65The routines 66.Fn inet_netof 67and 68.Fn inet_lnaof 69break apart Internet host addresses, returning 70the network number and local network address part, 71respectively. 72.Pp 73All Internet addresses are returned in network 74order (bytes ordered from left to right). 75All network numbers and local address parts are 76returned as machine format integer values. 77.Sh SEE ALSO 78.Xr gethostbyname 3 , 79.Xr inet_addr 3 , 80.Xr inet_net_ntop 3 , 81.Xr hosts 5 82.Sh HISTORY 83The 84.Nm inet_makeaddr , 85.Nm inet_lnaof , 86and 87.Nm inet_netof 88functions appeared in 89.Bx 4.2 . 90