1.\" $OpenBSD: htonl.3,v 1.6 2022/09/11 06:38:10 jmc Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.Dd $Mdocdate: September 11 2022 $ 31.Dt HTONL 3 32.Os 33.Sh NAME 34.Nm htonl , 35.Nm htons , 36.Nm ntohl , 37.Nm ntohs 38.Nd convert values between host and network byte orderings 39.Sh SYNOPSIS 40.In arpa/inet.h 41.Ft uint32_t 42.Fn htonl "uint32_t host32" 43.Ft uint16_t 44.Fn htons "uint16_t host16" 45.Ft uint32_t 46.Fn ntohl "uint32_t net32" 47.Ft uint16_t 48.Fn ntohs "uint16_t net16" 49.Sh DESCRIPTION 50These routines convert 16 and 32-bit quantities between different 51byte orderings. 52.Pp 53The 54.Fn htonl 55and 56.Fn htons 57functions convert quantities from host to network byte order while the 58.Fn ntohl 59and 60.Fn ntohs 61functions convert in the other direction. 62.Pp 63The last letter 64.Pf ( Sq s 65or 66.Sq l ) 67is a mnemonic 68for the traditional names for such quantities, 69short and long, respectively. 70Today, the C concept of 71.Vt short 72and 73.Vt long 74integers need not coincide with this traditional misunderstanding. 75On machines which have a byte order which is the same as the network 76order, routines are defined as null macros. 77.Pp 78These routines are most often used in conjunction with Internet 79addresses and ports as returned by 80.Xr gethostbyname 3 81and 82.Xr getservent 3 . 83.Sh SEE ALSO 84.Xr gethostbyname 3 , 85.Xr getservent 3 , 86.Xr htobe64 3 87.Sh STANDARDS 88The 89.Fn htonl , 90.Fn htons , 91.Fn ntohl , 92and 93.Fn ntohs 94functions conform to 95.St -p1003.1 . 96.Sh HISTORY 97These functions appeared in 98.Bx 4.2 . 99.Sh BUGS 100On the alpha, amd64, i386, and some mips and arm architectures, 101bytes are handled backwards from most everyone else in the world. 102This is not expected to be fixed in the near future. 103