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.\" $FreeBSD$ 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.Pp 99.Sh NETWORK NUMBERS (IP VERSION 4) 100Internet network numbers may be specified in one of the following forms: 101.Bd -literal -offset indent 102a.b.c.d/bits 103a.b.c.d 104a.b.c 105a.b 106a 107.Ed 108.Pp 109When four parts are specified, each is interpreted 110as a byte of data and assigned, from left to right, 111to the four bytes of an Internet network number. 112Note 113that when an Internet network number is viewed as a 32-bit 114integer quantity on a system that uses little-endian 115byte order (such as the 116.Tn Intel 386 , 486 , 117and 118.Tn Pentium 119processors) the bytes referred to above appear as 120.Dq Li d.c.b.a . 121That is, little-endian bytes are ordered from right to left. 122.Pp 123When a three part number is specified, the last 124part is interpreted as a 16-bit quantity and placed 125in the rightmost two bytes of the Internet network number. 126This makes the three part number format convenient 127for specifying Class B network numbers as 128.Dq Li 128.net.host . 129.Pp 130When a two part number is supplied, the last part 131is interpreted as a 24-bit quantity and placed in 132the rightmost three bytes of the Internet network number. 133This makes the two part number format convenient 134for specifying Class A network numbers as 135.Dq Li net.host . 136.Pp 137When only one part is given, the value is stored 138directly in the Internet network number without any byte 139rearrangement. 140.Pp 141All numbers supplied as 142.Dq parts 143in a 144.Ql \&. 145notation 146may be decimal, octal, or hexadecimal, as specified 147in the C language (i.e., a leading 0x or 0X implies 148hexadecimal; otherwise, a leading 0 implies octal; 149otherwise, the number is interpreted as decimal). 150.\" 151.\" .Sh NETWORK NUMBERS (IP VERSION 6) 152.\" XXX - document this! 153.\" 154.Sh SEE ALSO 155.Xr byteorder 3 , 156.Xr inet 3 , 157.Xr networks 5 158.Sh HISTORY 159The 160.Fn inet_net_ntop 161and 162.Fn inet_net_pton 163functions appeared in BIND 4.9.4. 164