net/inet_net.3

   1 .\"     $NetBSD: inet_net.3,v 1.4 1999/03/22 19:44:52 garbled Exp $
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   7 .\" by Luke Mewburn.
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  33 .\" $FreeBSD: src/lib/libc/net/inet_net.3,v 1.4 2007/01/09 00:28:02 imp Exp $
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  35 .Dd February 26, 2006
  36 .Dt INET_NET 3
  37 .Os
  38 .Sh NAME
  39 .Nm inet_net_ntop ,
  40 .Nm inet_net_pton
  41 .Nd Internet network number manipulation routines
  42 .Sh LIBRARY
  43 .Lb libc
  44 .Sh SYNOPSIS
  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
  51 The
  52 .Fn inet_net_ntop
  53 function converts an Internet network number from network format (usually a
  54 .Vt "struct in_addr"
  55 or some other binary form, in network byte order) to CIDR presentation format
  56 (suitable for external display purposes).
  57 The
  58 .Fa bits
  59 argument
  60 is the number of bits in
  61 .Fa src
  62 that are the network number.
  63 It returns
  64 .Dv NULL
  65 if a system error occurs (in which case,
  66 .Va errno
  67 will have been set), or it returns a pointer to the destination string.
  68 .Pp
  69 The
  70 .Fn inet_net_pton
  71 function converts a presentation format Internet network number (that is,
  72 printable form as held in a character string) to network format (usually a
  73 .Vt "struct in_addr"
  74 or some other internal binary representation, in network byte order).
  75 It returns the number of bits (either computed based on the class, or
  76 specified with /CIDR), or \-1 if a failure occurred
  77 (in which case
  78 .Va errno
  79 will have been set.
  80 It will be set to
  81 .Er ENOENT
  82 if the Internet network number was not valid).
  83 .Pp
  84 The currently supported values for
  85 .Fa af
  86 are
  87 .Dv AF_INET
  88 and
  89 .Dv AF_INET6 .
  90 The
  91 .Fa size
  92 argument
  93 is the size of the result buffer
  94 .Fa dst .
  95 .Pp
  96 .Sh NETWORK NUMBERS (IP VERSION 4)
  97 Internet network numbers may be specified in one of the following forms:
  98 .Bd -literal -offset indent
  99 a.b.c.d/bits
 100 a.b.c.d
 101 a.b.c
 102 a.b
 103 a
 104 .Ed
 105 .Pp
 106 When four parts are specified, each is interpreted
 107 as a byte of data and assigned, from left to right,
 108 to the four bytes of an Internet network number.
 109 Note
 110 that when an Internet network number is viewed as a 32-bit
 111 integer quantity on a system that uses little-endian
 112 byte order (such as the
 113 .Tn Intel 386 , 486 ,
 114 and
 115 .Tn Pentium
 116 processors) the bytes referred to above appear as
 117 .Dq Li d.c.b.a .
 118 That is, little-endian bytes are ordered from right to left.
 119 .Pp
 120 When a three part number is specified, the last
 121 part is interpreted as a 16-bit quantity and placed
 122 in the rightmost two bytes of the Internet network number.
 123 This makes the three part number format convenient
 124 for specifying Class B network numbers as
 125 .Dq Li 128.net.host .
 126 .Pp
 127 When a two part number is supplied, the last part
 128 is interpreted as a 24-bit quantity and placed in
 129 the rightmost three bytes of the Internet network number.
 130 This makes the two part number format convenient
 131 for specifying Class A network numbers as
 132 .Dq Li net.host .
 133 .Pp
 134 When only one part is given, the value is stored
 135 directly in the Internet network number without any byte
 136 rearrangement.
 137 .Pp
 138 All numbers supplied as
 139 .Dq parts
 140 in a
 141 .Ql \&.
 142 notation
 143 may be decimal, octal, or hexadecimal, as specified
 144 in the C language (i.e., a leading 0x or 0X implies
 145 hexadecimal; otherwise, a leading 0 implies octal;
 146 otherwise, the number is interpreted as decimal).
 147 .\"
 148 .\" .Sh NETWORK NUMBERS (IP VERSION 6)
 149 .\" XXX - document this!
 150 .\"
 151 .Sh LEGACY SYNOPSIS
 152 .Fd #include <sys/types.h>
 153 .Fd #include <sys/socket.h>
 154 .Fd #include <netinet/in.h>
 155 .Fd #include <arpa/inet.h>
 156 .Pp
 157 These include files were necessary for all functions.
 158 .Sh SEE ALSO
 159 .Xr byteorder 3 ,
 160 .Xr inet 3 ,
 161 .Xr networks 5
 162 .Sh HISTORY
 163 The
 164 .Fn inet_net_ntop
 165 and
 166 .Fn inet_net_pton
 167 functions appeared in BIND 4.9.4.