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.\" 4. Neither the name of The NetBSD Foundation nor the names of its 18.\" contributors may be used to endorse or promote products derived 19.\" from this software without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 22.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 23.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 24.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 25.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 26.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 27.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 28.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 29.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 30.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 31.\" POSSIBILITY OF SUCH DAMAGE. 32.\" 33.\" $FreeBSD: src/lib/libc/net/inet_net.3,v 1.4 2007/01/09 00:28:02 imp Exp $ 34.\" 35.Dd February 26, 2006 36.Dt INET_NET 3 37.Os 38.Sh NAME 39.Nm inet_net_ntop , 40.Nm inet_net_pton 41.Nd Internet network number manipulation routines 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In sys/types.h 46.In sys/socket.h 47.In netinet/in.h 48.In arpa/inet.h 49.Ft char * 50.Fn inet_net_ntop "int af" "const void *src" "int bits" "char *dst" "size_t size" 51.Ft int 52.Fn inet_net_pton "int af" "const char *src" "void *dst" "size_t size" 53.Sh DESCRIPTION 54The 55.Fn inet_net_ntop 56function converts an Internet network number from network format (usually a 57.Vt "struct in_addr" 58or some other binary form, in network byte order) to CIDR presentation format 59(suitable for external display purposes). 60The 61.Fa bits 62argument 63is the number of bits in 64.Fa src 65that are the network number. 66It returns 67.Dv NULL 68if a system error occurs (in which case, 69.Va errno 70will have been set), or it returns a pointer to the destination string. 71.Pp 72The 73.Fn inet_net_pton 74function converts a presentation format Internet network number (that is, 75printable form as held in a character string) to network format (usually a 76.Vt "struct in_addr" 77or some other internal binary representation, in network byte order). 78It returns the number of bits (either computed based on the class, or 79specified with /CIDR), or \-1 if a failure occurred 80(in which case 81.Va errno 82will have been set. 83It will be set to 84.Er ENOENT 85if the Internet network number was not valid). 86.Pp 87The currently supported values for 88.Fa af 89are 90.Dv AF_INET 91and 92.Dv AF_INET6 . 93The 94.Fa size 95argument 96is the size of the result buffer 97.Fa dst . 98.Sh NETWORK NUMBERS (IP VERSION 4) 99Internet network numbers may be specified in one of the following forms: 100.Bd -literal -offset indent 101a.b.c.d/bits 102a.b.c.d 103a.b.c 104a.b 105a 106.Ed 107.Pp 108When four parts are specified, each is interpreted 109as a byte of data and assigned, from left to right, 110to the four bytes of an Internet network number. 111Note 112that when an Internet network number is viewed as a 32-bit 113integer quantity on a system that uses little-endian 114byte order (such as the 115.Tn Intel 386 , 486 , 116and 117.Tn Pentium 118processors) the bytes referred to above appear as 119.Dq Li d.c.b.a . 120That is, little-endian bytes are ordered from right to left. 121.Pp 122When a three part number is specified, the last 123part is interpreted as a 16-bit quantity and placed 124in the rightmost two bytes of the Internet network number. 125This makes the three part number format convenient 126for specifying Class B network numbers as 127.Dq Li 128.net.host . 128.Pp 129When a two part number is supplied, the last part 130is interpreted as a 24-bit quantity and placed in 131the rightmost three bytes of the Internet network number. 132This makes the two part number format convenient 133for specifying Class A network numbers as 134.Dq Li net.host . 135.Pp 136When only one part is given, the value is stored 137directly in the Internet network number without any byte 138rearrangement. 139.Pp 140All numbers supplied as 141.Dq parts 142in a 143.Ql \&. 144notation 145may be decimal, octal, or hexadecimal, as specified 146in the C language (i.e., a leading 0x or 0X implies 147hexadecimal; otherwise, a leading 0 implies octal; 148otherwise, the number is interpreted as decimal). 149.\" 150.\" .Sh NETWORK NUMBERS (IP VERSION 6) 151.\" XXX - document this! 152.\" 153.Sh SEE ALSO 154.Xr byteorder 3 , 155.Xr inet 3 , 156.Xr networks 5 157.Sh HISTORY 158The 159.Fn inet_net_ntop 160and 161.Fn inet_net_pton 162functions appeared in BIND 4.9.4. 163