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. 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.Dd November 9, 2021 34.Dt INET_NET 3 35.Os 36.Sh NAME 37.Nm inet_net_ntop , 38.Nm inet_net_pton 39.Nd Internet network number manipulation routines 40.Sh LIBRARY 41.Lb libc 42.Sh SYNOPSIS 43.In sys/socket.h 44.In netinet/in.h 45.In arpa/inet.h 46.Ft char * 47.Fn inet_net_ntop "int af" "const void *src" "int bits" "char *dst" "size_t size" 48.Ft int 49.Fn inet_net_pton "int af" "const char *src" "void *dst" "size_t size" 50.Sh DESCRIPTION 51The 52.Fn inet_net_ntop 53function converts an Internet network number from network format (usually a 54.Vt "struct in_addr" 55or some other binary form, in network byte order) to CIDR presentation format 56(suitable for external display purposes). 57The 58.Fa bits 59argument 60is the number of bits in 61.Fa src 62that are the network number. 63It returns 64.Dv NULL 65if a system error occurs (in which case, 66.Va errno 67will have been set), or it returns a pointer to the destination string. 68.Pp 69The 70.Fn inet_net_pton 71function converts a presentation format Internet network number (that is, 72printable form as held in a character string) to network format (usually a 73.Vt "struct in_addr" 74or some other internal binary representation, in network byte order). 75It returns the number of bits (either computed based on the class, or 76specified with /CIDR), or \-1 if a failure occurred 77(in which case 78.Va errno 79will have been set. 80It will be set to 81.Er ENOENT 82if the Internet network number was not valid). 83.Pp 84The currently supported values for 85.Fa af 86are 87.Dv AF_INET 88and 89.Dv AF_INET6 . 90The 91.Fa size 92argument 93is the size of the result buffer 94.Fa dst . 95.Sh NETWORK NUMBERS (IP VERSION 4) 96Internet network numbers may be specified in one of the following forms: 97.Bd -literal -offset indent 98a.b.c.d/bits 99a.b.c.d 100a.b.c 101a.b 102a 103.Ed 104.Pp 105When four parts are specified, each is interpreted 106as a byte of data and assigned, from left to right, 107to the four bytes of an Internet network number. 108Note 109that when an Internet network number is viewed as a 32-bit 110integer quantity on a system that uses little-endian 111byte order (such as the 112.Tn Intel 386 , 486 , 113and 114.Tn Pentium 115processors) the bytes referred to above appear as 116.Dq Li d.c.b.a . 117That is, little-endian bytes are ordered from right to left. 118.Pp 119When a three part number is specified, the last 120part is interpreted as a 16-bit quantity and placed 121in the least significant two bytes of the Internet network number. 122.Pp 123When a two part number is supplied, the last part 124is interpreted as a 24-bit quantity and placed in 125the least significant three bytes of the Internet network number. 126.Pp 127When only one part is given, the value is stored 128directly in the Internet network number without any byte 129rearrangement. 130.Pp 131All numbers supplied as 132.Dq parts 133in a 134.Ql \&. 135notation 136may be decimal, octal, or hexadecimal, as specified 137in the C language (i.e., a leading 0x or 0X implies 138hexadecimal; otherwise, a leading 0 implies octal; 139otherwise, the number is interpreted as decimal). 140.\" 141.\" .Sh NETWORK NUMBERS (IP VERSION 6) 142.\" XXX - document this! 143.\" 144.Sh SEE ALSO 145.Xr byteorder 3 , 146.Xr inet 3 , 147.Xr networks 5 148.Sh HISTORY 149The 150.Fn inet_net_ntop 151and 152.Fn inet_net_pton 153functions appeared in BIND 4.9.4. 154