1.\" $NetBSD: inet_net.3,v 1.4 1999/03/22 19:44:52 garbled Exp $ 2.\" 3.\" Copyright (c) 1997 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Luke Mewburn. 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 NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.\" $FreeBSD$ 38.\" 39.Dd February 26, 2006 40.Dt INET_NET 3 41.Os 42.Sh NAME 43.Nm inet_net_ntop , 44.Nm inet_net_pton 45.Nd Internet network number manipulation routines 46.Sh LIBRARY 47.Lb libc 48.Sh SYNOPSIS 49.In sys/types.h 50.In sys/socket.h 51.In netinet/in.h 52.In arpa/inet.h 53.Ft char * 54.Fn inet_net_ntop "int af" "const void *src" "int bits" "char *dst" "size_t size" 55.Ft int 56.Fn inet_net_pton "int af" "const char *src" "void *dst" "size_t size" 57.Sh DESCRIPTION 58The 59.Fn inet_net_ntop 60function converts an Internet network number from network format (usually a 61.Vt "struct in_addr" 62or some other binary form, in network byte order) to CIDR presentation format 63(suitable for external display purposes). 64The 65.Fa bits 66argument 67is the number of bits in 68.Fa src 69that are the network number. 70It returns 71.Dv NULL 72if a system error occurs (in which case, 73.Va errno 74will have been set), or it returns a pointer to the destination string. 75.Pp 76The 77.Fn inet_net_pton 78function converts a presentation format Internet network number (that is, 79printable form as held in a character string) to network format (usually a 80.Vt "struct in_addr" 81or some other internal binary representation, in network byte order). 82It returns the number of bits (either computed based on the class, or 83specified with /CIDR), or \-1 if a failure occurred 84(in which case 85.Va errno 86will have been set. 87It will be set to 88.Er ENOENT 89if the Internet network number was not valid). 90.Pp 91The currently supported values for 92.Fa af 93are 94.Dv AF_INET 95and 96.Dv AF_INET6 . 97The 98.Fa size 99argument 100is the size of the result buffer 101.Fa dst . 102.Pp 103.Sh NETWORK NUMBERS (IP VERSION 4) 104Internet network numbers may be specified in one of the following forms: 105.Bd -literal -offset indent 106a.b.c.d/bits 107a.b.c.d 108a.b.c 109a.b 110a 111.Ed 112.Pp 113When four parts are specified, each is interpreted 114as a byte of data and assigned, from left to right, 115to the four bytes of an Internet network number. 116Note 117that when an Internet network number is viewed as a 32-bit 118integer quantity on a system that uses little-endian 119byte order (such as the 120.Tn Intel 386 , 486 , 121and 122.Tn Pentium 123processors) the bytes referred to above appear as 124.Dq Li d.c.b.a . 125That is, little-endian bytes are ordered from right to left. 126.Pp 127When a three part number is specified, the last 128part is interpreted as a 16-bit quantity and placed 129in the rightmost two bytes of the Internet network number. 130This makes the three part number format convenient 131for specifying Class B network numbers as 132.Dq Li 128.net.host . 133.Pp 134When a two part number is supplied, the last part 135is interpreted as a 24-bit quantity and placed in 136the rightmost three bytes of the Internet network number. 137This makes the two part number format convenient 138for specifying Class A network numbers as 139.Dq Li net.host . 140.Pp 141When only one part is given, the value is stored 142directly in the Internet network number without any byte 143rearrangement. 144.Pp 145All numbers supplied as 146.Dq parts 147in a 148.Ql \&. 149notation 150may be decimal, octal, or hexadecimal, as specified 151in the C language (i.e., a leading 0x or 0X implies 152hexadecimal; otherwise, a leading 0 implies octal; 153otherwise, the number is interpreted as decimal). 154.\" 155.\" .Sh NETWORK NUMBERS (IP VERSION 6) 156.\" XXX - document this! 157.\" 158.Sh SEE ALSO 159.Xr byteorder 3 , 160.Xr inet 3 , 161.Xr networks 5 162.Sh HISTORY 163The 164.Fn inet_net_ntop 165and 166.Fn inet_net_pton 167functions appeared in BIND 4.9.4. 168