1.\" $NetBSD: inet_net.3,v 1.5 2012/07/20 20:48:59 wiz 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.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd July 20, 2012 31.Dt INET_NET 3 32.Os 33.Sh NAME 34.Nm inet_net_ntop , 35.Nm inet_net_pton 36.Nd Internet network number manipulation routines 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In sys/socket.h 41.In netinet/in.h 42.In arpa/inet.h 43.Ft char * 44.Fn inet_net_ntop "int af" "const void *src" "int bits" "char *dst" "size_t size" 45.Ft int 46.Fn inet_net_pton "int af" "const char *src" "void *dst" "size_t size" 47.Sh DESCRIPTION 48The 49.Fn inet_net_ntop 50function converts an Internet network number from network format (usually a 51.Vt struct in_addr 52or some other binary form, in network byte order) to CIDR presentation format 53(suitable for external display purposes). 54The 55.Fa bits 56argument is the number of bits in 57.Fa src 58that are the network number. 59It returns 60.Dv NULL 61if an error occurs (in which case 62.Va errno 63will have been set), or it returns a pointer to the destination string. 64.Pp 65The 66.Fn inet_net_pton 67function converts a presentation format Internet network number (that is, 68printable form as held in a character string) to network format (usually a 69.Vt struct in_addr 70or some other internal binary representation, in network byte order). 71It returns the number of bits (either computed based on the class, or 72specified with /CIDR), or \-1 if a failure occurred 73(in which case 74.Va errno 75will have been set). 76.Pp 77The currently supported values for 78.Fa af 79are 80.Dv AF_INET 81and 82.Dv AF_INET6 . 83The 84.Fa size 85argument is the size of the result buffer 86.Fa dst . 87.Sh NETWORK NUMBERS (IP VERSION 4) 88Internet network numbers may be specified in one of the following forms: 89.Bd -literal -offset indent 90a.b.c.d/bits 91a.b.c.d 92a.b.c 93a.b 94a 95.Ed 96.Pp 97When four parts are specified, each is interpreted 98as a byte of data and assigned, from left to right, 99to the four bytes of an Internet network number. 100Note that when an Internet network number is viewed as a 32-bit 101integer quantity on a system that uses little-endian 102byte order (such as the 103.Tn Intel 386 , 486 , 104and 105.Tn Pentium 106processors) the bytes referred to above appear as 107.Dq Li d.c.b.a . 108That is, little-endian bytes are ordered from right to left. 109.Pp 110When a three part number is specified, the last 111part is interpreted as a 16-bit quantity and placed 112in the rightmost two bytes of the Internet network number. 113This makes the three part number format convenient 114for specifying Class B network numbers as 115.Dq Li 128.net.host . 116.Pp 117When a two part number is supplied, the last part 118is interpreted as a 24-bit quantity and placed in 119the rightmost three bytes of the Internet network number. 120This makes the two part number format convenient 121for specifying Class A network numbers as 122.Dq Li net.host . 123.Pp 124When only one part is given, the value is stored 125directly in the Internet network number without any byte 126rearrangement. 127.Pp 128All numbers supplied as 129.Dq parts 130in a 131.Ql \&. 132notation 133may be decimal, octal, or hexadecimal, as specified 134in the C language (i.e., a leading 0x or 0X implies 135hexadecimal; otherwise, a leading 0 implies octal; 136otherwise, the number is interpreted as decimal). 137.\" 138.\" .Sh NETWORK NUMBERS (IP VERSION 6) 139.\" XXX - document this! 140.\" 141.Sh ERRORS 142The 143.Fn inet_net_ntop 144and 145.Fn inet_net_pton 146functions may fail with 147.Bl -tag -width Er 148.It Bq Er EAFNOSUPPORT 149The value of 150.Fa af 151was not 152.Dv AF_INET 153or 154.Dv AF_INET6 . 155.It Bq Er EMSGSIZE 156The conversion of 157.Fa src 158overflows 159.Fa size 160of 161.Fa dst . 162.El 163.Pp 164The 165.Fn inet_net_ntop 166function may fail with 167.Bl -tag -width Er 168.It Bq Er EINVAL 169The 170.Fa bits 171argument contains an invalid number of bits 172for the requested address family. 173.El 174.Pp 175The 176.Fn inet_net_pton 177function may fail with 178.Bl -tag -width Er 179.It Bq Er ENOENT 180The 181.Fa src 182was not a valid Internet network number. 183.El 184.Sh SEE ALSO 185.Xr byteorder 3 , 186.Xr inet 3 , 187.Xr networks 5 188.Sh HISTORY 189The 190.Fn inet_net_ntop 191and 192.Fn inet_net_pton 193functions appeared in BIND 4.9.4 and thence 194.Nx 1.3 . 195Support for 196.Dv AF_INET6 197appeared in 198.Nx 1.6 . 199