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). 64.Fa bits 65is the number of bits in 66.Fa src 67that are the network number. 68It returns 69.Dv NULL 70if a system error occurs (in which case, 71.Va errno 72will have been set), or it returns a pointer to the destination string. 73.Pp 74The 75.Fn inet_net_pton 76function converts a presentation format Internet network number (that is, 77printable form as held in a character string) to network format (usually a 78.Vt "struct in_addr" 79or some other internal binary representation, in network byte order). 80It returns the number of bits (either computed based on the class, or 81specified with /CIDR), or \-1 if a failure occurred 82(in which case 83.Va errno 84will have been set. 85It will be set to 86.Er ENOENT 87if the Internet network number was not valid). 88.Pp 89The only value for 90.Fa af 91currently supported is 92.Dv AF_INET . 93.Fa size 94is the size of the result buffer 95.Fa dst . 96.Pp 97.Sh NETWORK NUMBERS (IP VERSION 4) 98Internet network numbers may be specified in one of the following forms: 99.Bd -literal -offset indent 100a.b.c.d/bits 101a.b.c.d 102a.b.c 103a.b 104a 105.Ed 106.Pp 107When four parts are specified, each is interpreted 108as a byte of data and assigned, from left to right, 109to the four bytes of an Internet network number. 110Note 111that when an Internet network number is viewed as a 32-bit 112integer quantity on a system that uses little-endian 113byte order (such as the 114.Tn Intel 386 , 486 , 115and 116.Tn Pentium 117processors) the bytes referred to above appear as 118.Dq Li d.c.b.a . 119That is, little-endian bytes are ordered from right to left. 120.Pp 121When a three part number is specified, the last 122part is interpreted as a 16-bit quantity and placed 123in the rightmost two bytes of the Internet network number. 124This makes the three part number format convenient 125for specifying Class B network numbers as 126.Dq Li 128.net.host . 127.Pp 128When a two part number is supplied, the last part 129is interpreted as a 24-bit quantity and placed in 130the rightmost three bytes of the Internet network number. 131This makes the two part number format convenient 132for specifying Class A network numbers as 133.Dq Li net.host . 134.Pp 135When only one part is given, the value is stored 136directly in the Internet network number without any byte 137rearrangement. 138.Pp 139All numbers supplied as 140.Dq parts 141in a 142.Ql \&. 143notation 144may be decimal, octal, or hexadecimal, as specified 145in the C language (i.e., a leading 0x or 0X implies 146hexadecimal; otherwise, a leading 0 implies octal; 147otherwise, the number is interpreted as decimal). 148.Sh SEE ALSO 149.Xr byteorder 3 , 150.Xr inet 3 , 151.Xr networks 5 152.Sh HISTORY 153The 154.Fn inet_net_ntop 155and 156.Fn inet_net_pton 157functions appeared in BIND 4.9.4. 158