net/FreeBSD/inet_net.3

   1 .\"     $NetBSD: inet_net.3,v 1.4 1999/03/22 19:44:52 garbled Exp $
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   3 .\" Copyright (c) 1997 The NetBSD Foundation, Inc.
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   7 .\" by Luke Mewburn.
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  37 .\" $FreeBSD: src/lib/libc/net/inet_net.3,v 1.2 2002/12/19 09:40:22 ru Exp $
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  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
  58 The
  59 .Fn inet_net_ntop
  60 function converts an Internet network number from network format (usually a
  61 .Vt "struct in_addr"
  62 or some other binary form, in network byte order) to CIDR presentation format
  63 (suitable for external display purposes).
  64 The
  65 .Fa bits
  66 argument
  67 is the number of bits in
  68 .Fa src
  69 that are the network number.
  70 It returns
  71 .Dv NULL
  72 if a system error occurs (in which case,
  73 .Va errno
  74 will have been set), or it returns a pointer to the destination string.
  75 .Pp
  76 The
  77 .Fn inet_net_pton
  78 function converts a presentation format Internet network number (that is,
  79 printable form as held in a character string) to network format (usually a
  80 .Vt "struct in_addr"
  81 or some other internal binary representation, in network byte order).
  82 It returns the number of bits (either computed based on the class, or
  83 specified with /CIDR), or \-1 if a failure occurred
  84 (in which case
  85 .Va errno
  86 will have been set.
  87 It will be set to
  88 .Er ENOENT
  89 if the Internet network number was not valid).
  90 .Pp
  91 The only value for
  92 .Fa af
  93 currently supported is
  94 .Dv AF_INET .
  95 The
  96 .Fa size
  97 argument
  98 is the size of the result buffer
  99 .Fa dst .
 100 .Pp
 101 .Sh NETWORK NUMBERS (IP VERSION 4)
 102 Internet network numbers may be specified in one of the following forms:
 103 .Bd -literal -offset indent
 104 a.b.c.d/bits
 105 a.b.c.d
 106 a.b.c
 107 a.b
 108 a
 109 .Ed
 110 .Pp
 111 When four parts are specified, each is interpreted
 112 as a byte of data and assigned, from left to right,
 113 to the four bytes of an Internet network number.
 114 Note
 115 that when an Internet network number is viewed as a 32-bit
 116 integer quantity on a system that uses little-endian
 117 byte order (such as the
 118 .Tn Intel 386 , 486 ,
 119 and
 120 .Tn Pentium
 121 processors) the bytes referred to above appear as
 122 .Dq Li d.c.b.a .
 123 That is, little-endian bytes are ordered from right to left.
 124 .Pp
 125 When a three part number is specified, the last
 126 part is interpreted as a 16-bit quantity and placed
 127 in the rightmost two bytes of the Internet network number.
 128 This makes the three part number format convenient
 129 for specifying Class B network numbers as
 130 .Dq Li 128.net.host .
 131 .Pp
 132 When a two part number is supplied, the last part
 133 is interpreted as a 24-bit quantity and placed in
 134 the rightmost three bytes of the Internet network number.
 135 This makes the two part number format convenient
 136 for specifying Class A network numbers as
 137 .Dq Li net.host .
 138 .Pp
 139 When only one part is given, the value is stored
 140 directly in the Internet network number without any byte
 141 rearrangement.
 142 .Pp
 143 All numbers supplied as
 144 .Dq parts
 145 in a
 146 .Ql \&.
 147 notation
 148 may be decimal, octal, or hexadecimal, as specified
 149 in the C language (i.e., a leading 0x or 0X implies
 150 hexadecimal; otherwise, a leading 0 implies octal;
 151 otherwise, 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
 157 The
 158 .Fn inet_net_ntop
 159 and
 160 .Fn inet_net_pton
 161 functions appeared in BIND 4.9.4.