gen.subproj/getnetent.3

   1 .\" Copyright (c) 1983, 1991, 1993
   2 .\"     The Regents of the University of California.  All rights reserved.
   3 .\"
   4 .\" Redistribution and use in source and binary forms, with or without
   5 .\" modification, are permitted provided that the following conditions
   6 .\" are met:
   7 .\" 1. Redistributions of source code must retain the above copyright
   8 .\"    notice, this list of conditions and the following disclaimer.
   9 .\" 2. Redistributions in binary form must reproduce the above copyright
  10 .\"    notice, this list of conditions and the following disclaimer in the
  11 .\"    documentation and/or other materials provided with the distribution.
  12 .\" 4. Neither the name of the University nor the names of its contributors
  13 .\"    may be used to endorse or promote products derived from this software
  14 .\"    without specific prior written permission.
  15 .\"
  16 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  17 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  20 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26 .\" SUCH DAMAGE.
  27 .\"
  28 .\"     @(#)getnetent.3 8.1 (Berkeley) 6/4/93
  29 .\" $FreeBSD: src/lib/libc/net/getnetent.3,v 1.23 2007/01/09 00:28:02 imp Exp $
  30 .\"
  31 .Dd June 4, 1993
  32 .Dt GETNETENT 3
  33 .Os
  34 .Sh NAME
  35 .Nm getnetent ,
  36 .Nm getnetbyaddr ,
  37 .Nm getnetbyname ,
  38 .Nm setnetent ,
  39 .Nm endnetent
  40 .Nd get network entry
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In netdb.h
  45 .Ft struct netent *
  46 .Fn getnetent void
  47 .Ft struct netent *
  48 .Fn getnetbyname "const char *name"
  49 .Ft struct netent *
  50 .Fn getnetbyaddr "uint32_t net" "int type"
  51 .Ft void
  52 .Fn setnetent "int stayopen"
  53 .Ft void
  54 .Fn endnetent void
  55 .Sh DESCRIPTION
  56 The
  57 .Fn getnetent ,
  58 .Fn getnetbyname ,
  59 and
  60 .Fn getnetbyaddr
  61 functions
  62 each return a pointer to an object with the
  63 following structure describing an internet network.
  64 .\"This structure contains either the information obtained
  65 .\"from the nameserver,
  66 .\".Xr named 8 ,
  67 .\"broken-out fields of a line in the network data base
  68 .\".Pa /etc/networks ,
  69 .\"or entries supplied by the
  70 .\".Xr yp 8
  71 .\"system.
  72 .\"The order of the lookups is controlled by the
  73 .\"`networks' entry in
  74 .\".Xr nsswitch.conf 5 .
  75 This structure contains information obtained from
  76 .Xr opendirectoryd 8 ,
  77 including records in
  78 .Pa /etc/networks .
  79 .Pp
  80 .Bd -literal -offset indent
  81 struct  netent {
  82         char            *n_name;        /* official name of net */
  83         char            **n_aliases;    /* alias list */
  84         int             n_addrtype;     /* net number type */
  85         uint32_t        n_net;          /* net number */
  86 };
  87 .Ed
  88 .Pp
  89 The members of this structure are:
  90 .Bl -tag -width n_addrtype
  91 .It Fa n_name
  92 The official name of the network.
  93 .It Fa n_aliases
  94 A zero terminated list of alternate names for the network.
  95 .It Fa n_addrtype
  96 The type of the network number returned; currently only AF_INET.
  97 .It Fa n_net
  98 The network number.
  99 Network numbers are returned in machine byte
 100 order.
 101 .El
 102 .Pp
 103 The
 104 .Fn getnetent
 105 function
 106 reads the next line of the file, opening the file if necessary.
 107 .Pp
 108 The
 109 .Fn setnetent
 110 function
 111 opens and rewinds the file.
 112 If the
 113 .Fa stayopen
 114 flag is non-zero,
 115 the net data base will not be closed after each call to
 116 .Fn getnetbyname
 117 or
 118 .Fn getnetbyaddr .
 119 .Pp
 120 The
 121 .Fn endnetent
 122 function
 123 closes the file.
 124 .Pp
 125 The
 126 .Fn getnetbyname
 127 function
 128 and
 129 .Fn getnetbyaddr
 130 sequentially search from the beginning
 131 of the file until a matching
 132 net name or
 133 net address and type is found,
 134 or until
 135 .Dv EOF
 136 is encountered.
 137 The
 138 .Fa type
 139 argument
 140 must be
 141 .Dv AF_INET .
 142 Network numbers are supplied in host order.
 143 .Sh FILES
 144 .Bl -tag -width /etc/nsswitch.conf -compact
 145 .It Pa /etc/networks
 146 .\".It Pa /etc/nsswitch.conf
 147 .It Pa /etc/resolv.conf
 148 .El
 149 .Sh DIAGNOSTICS
 150 Null pointer
 151 (0) returned on
 152 .Dv EOF
 153 or error.
 154 .Sh SEE ALSO
 155 .Xr networks 5
 156 .Pp
 157 .%T RFC 1101
 158 .Sh HISTORY
 159 The
 160 .Fn getnetent ,
 161 .Fn getnetbyaddr ,
 162 .Fn getnetbyname ,
 163 .Fn setnetent ,
 164 and
 165 .Fn endnetent
 166 functions appeared in
 167 .Bx 4.2 .
 168 .Sh BUGS
 169 The data space used by
 170 these functions is thread-specific; if future use requires the data, it should be
 171 copied before any subsequent calls to these functions overwrite it.
 172 Only Internet network
 173 numbers are currently understood.
 174 Expecting network numbers to fit
 175 in no more than 32 bits is probably
 176 naive.