154 lines
3.5 KiB
Groff
154 lines
3.5 KiB
Groff
.\" $Id: getnetent.3,v 8.3 1997/03/14 02:29:43 vixie Exp $
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.\"
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.\"Copyright (c) 1995, 1996 by Internet Software Consortium
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.\"
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.\"Permission to use, copy, modify, and distribute this software for any
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.\"purpose with or without fee is hereby granted, provided that the above
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.\"copyright notice and this permission notice appear in all copies.
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.\"
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.\"THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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.\"ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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.\"OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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.\"CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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.\"DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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.\"PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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.\"ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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.\"SOFTWARE.
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.\"
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.Dd May 20, 1996
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.Dt GETNETENT @LIB_NETWORK_EXT_U@
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.Os BSD 4
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.Sh NAME
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.Nm getnetent ,
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.Nm getnetbyaddr ,
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.Nm getnetbyname ,
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.Nm setnetent ,
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.Nm endnetent
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.Nd get networks entry
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.Sh SYNOPSIS
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.Fd #include <netdb.h>
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.Ft struct netent *
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.Fn getnetent
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.Ft struct netent *
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.Fn getnetbyname "char name";
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.Ft struct netent *
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.Fn getnetbyaddr "unsigned long net" "int type";
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.Ft void
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.Fn setnetent "int stayopen";
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.Ft void
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.Fn endnetent
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.Sh DESCRIPTION
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The
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.Fn getnetent ,
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.Fn getnetbyname ,
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and
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.Fn getnetbyaddr
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subroutines
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each return a pointer to an object with the following structure
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containing the broken-out fields of a line in the
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.Pa networks
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database.
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.Bd -literal -offset indent
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struct netent {
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char *n_name; /* official name of net */
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char **n_aliases; /* alias list */
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int n_addrtype; /* net number type */
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long n_net; /* net number */
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};
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.Ed
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.Pp
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The members of this structure are:
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.Bl -tag -width "n_addrtype"
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.It n_name
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The official name of the network.
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.It n_aliases
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A zero-terminated list of alternate names for the network.
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.It n_addrtype
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The type of the network number returned:
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.Dv AF_INET .
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.It n_net
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The network number. Network numbers are returned in machine byte
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order.
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.El
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.Pp
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If the
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.Fa stayopen
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flag on a
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.Fn setnetent
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subroutine is NULL, the
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.Pa networks
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database is opened. Otherwise, the
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.Fn setnetent
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has the effect of rewinding the
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.Pa networks
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database.
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The
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.Fn endnetent
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subroutine may be called to
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close the
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.Pa networks
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database when processing is complete.
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.Pp
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The
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.Fn getnetent
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subroutine simply reads the next
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line while
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.Fn getnetbyname
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and
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.Fn getnetbyaddr
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search until a matching
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.Fa name
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or
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.Fa net
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number is found
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(or until
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.Dv EOF
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is encountered). The
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.Fa type must be
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.Dv AF_INET .
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The
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.Fn getnetent
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subroutine keeps a pointer in the database, allowing
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successive calls to be used to search the entire file.
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.Pp
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Before a
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.Ic while
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loop using
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.Fn getnetent ,
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a call to
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.Fn setnetent
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must be made
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in order to perform initialization; a call to
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.Fn endnetent
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must be used after the loop. Both
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.Fn getnetbyname
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and
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.Fn getnetbyaddr
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make calls to
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.Fn setnetent
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and
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.Fn endnetent .
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.Sh FILES
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.Pa /etc/networks
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.Sh DIAGNOSTICS
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Null pointer (0) returned on
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.Dv EOF
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or error.
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.Sh SEE ALSO
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.Xr networks @FORMAT_EXT@ ,
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RFC 1101.
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.Sh HISTORY
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The
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.Fn "getnetent" ,
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.Fn "getnetbyaddr" ,
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.Fn "getnetbyname" ,
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.Fn "setnetent" ,
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and
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.Fn "endnetent"
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functions appeared in 4.2BSD.
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.Sh BUGS
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The data space used by these functions is static; if future use requires the
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data, it should be copied before any subsequent calls to these functions
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overwrite it. Only Internet network numbers are currently understood.
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Expecting network numbers to fit in no more than 32 bits is probably naive.
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