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 June 18, 1997 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 only value for 92.Fa af 93currently supported is 94.Dv AF_INET . 95The 96.Fa size 97argument 98is the size of the result buffer 99.Fa dst . 100.Pp 101.Sh NETWORK NUMBERS (IP VERSION 4) 102Internet network numbers may be specified in one of the following forms: 103.Bd -literal -offset indent 104a.b.c.d/bits 105a.b.c.d 106a.b.c 107a.b 108a 109.Ed 110.Pp 111When four parts are specified, each is interpreted 112as a byte of data and assigned, from left to right, 113to the four bytes of an Internet network number. 114Note 115that when an Internet network number is viewed as a 32-bit 116integer quantity on a system that uses little-endian 117byte order (such as the 118.Tn Intel 386 , 486 , 119and 120.Tn Pentium 121processors) the bytes referred to above appear as 122.Dq Li d.c.b.a . 123That is, little-endian bytes are ordered from right to left. 124.Pp 125When a three part number is specified, the last 126part is interpreted as a 16-bit quantity and placed 127in the rightmost two bytes of the Internet network number. 128This makes the three part number format convenient 129for specifying Class B network numbers as 130.Dq Li 128.net.host . 131.Pp 132When a two part number is supplied, the last part 133is interpreted as a 24-bit quantity and placed in 134the rightmost three bytes of the Internet network number. 135This makes the two part number format convenient 136for specifying Class A network numbers as 137.Dq Li net.host . 138.Pp 139When only one part is given, the value is stored 140directly in the Internet network number without any byte 141rearrangement. 142.Pp 143All numbers supplied as 144.Dq parts 145in a 146.Ql \&. 147notation 148may be decimal, octal, or hexadecimal, as specified 149in the C language (i.e., a leading 0x or 0X implies 150hexadecimal; otherwise, a leading 0 implies octal; 151otherwise, the number is interpreted as decimal). 152.Sh SEE ALSO 153.Xr byteorder 3 , 154.Xr inet 3 , 155.Xr networks 5 156.Sh HISTORY 157The 158.Fn inet_net_ntop 159and 160.Fn inet_net_pton 161functions appeared in BIND 4.9.4. 162