159 lines
4.3 KiB
Groff
159 lines
4.3 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getnetent.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd June 4, 1993
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.Dt GETNETENT 3
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.Os BSD 4.2
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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 network 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 void
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.Ft struct netent *
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.Fn getnetbyname "const 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 void
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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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functions
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each return a pointer to an object with the
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following structure
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containing the broken-out
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fields of a line in the network data base,
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.Pa /etc/networks .
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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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unsigned 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 Fa n_name
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The official name of the network.
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.It Fa n_aliases
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A zero terminated list of alternate names for the network.
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.It Fa n_addrtype
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The type of the network number returned; currently only AF_INET.
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.It Fa 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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The
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.Fn getnetent
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function
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reads the next line of the file, opening the file if necessary.
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.Pp
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The
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.Fn setnetent
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function
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opens and rewinds the file. If the
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.Fa stayopen
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flag is non-zero,
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the net data base will not be closed after each call to
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.Fn getnetbyname
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or
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.Fn getnetbyaddr .
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.Pp
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The
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.Fn endnetent
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function
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closes the file.
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.Pp
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The
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.Fn getnetbyname
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function
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and
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.Fn getnetbyaddr
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sequentially search from the beginning
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of the file until a matching
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net name or
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net address and type 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
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must be
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.Dv AF_INET .
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Network numbers are supplied in host order.
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.Sh FILES
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.Bl -tag -width /etc/networks -compact
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.It Pa /etc/networks
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.El
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.Sh DIAGNOSTICS
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Null pointer
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(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 5
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.Pp
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.%T 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
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.Bx 4.2 .
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.Sh BUGS
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The data space used by
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these functions is static; if future use requires the data, it should be
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copied before any subsequent calls to these functions overwrite it.
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Only Internet network
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numbers are currently understood.
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Expecting network numbers to fit
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in no more than 32 bits is probably
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naive.
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