.\"	$OpenBSD: getnetent.3,v 1.19 2019/08/30 20:20:51 jmc Exp $
.\"
.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.Dd $Mdocdate: August 30 2019 $
.Dt GETNETENT 3
.Os
.Sh NAME
.Nm getnetent ,
.Nm getnetbyaddr ,
.Nm getnetbyname ,
.Nm setnetent ,
.Nm endnetent
.Nd get network entry
.Sh SYNOPSIS
.In netdb.h
.Ft struct netent *
.Fn getnetent "void"
.Ft struct netent *
.Fn getnetbyname "const char *name"
.Ft struct netent *
.Fn getnetbyaddr "in_addr_t net" "int type"
.Ft void
.Fn setnetent "int stayopen"
.Ft void
.Fn endnetent "void"
.Sh DESCRIPTION
The
.Fn getnetbyname
and
.Fn getnetbyaddr
functions return a pointer to an object with the following structure:
.Bd -literal -offset indent
struct	netent {
	char		*n_name;	/* official name of net */
	char		**n_aliases;	/* alias list */
	int		n_addrtype;	/* net number type */
	in_addr_t	n_net;		/* net number */
};
.Ed
.Pp
The members of this structure are:
.Bl -tag -width n_addrtype
.It Fa n_name
The official name of the network.
.It Fa n_aliases
A null-terminated list of alternate names for the network.
.It Fa n_addrtype
The type of the network number returned; it is always
.Dv AF_INET .
.It Fa n_net
The network number.
Network numbers are returned in machine byte order.
.El
.Pp
On
.Ox ,
these legacy functions perform a lookup in a similar fashion as
.Xr gethostbyname 3
and
.Xr gethostbyaddr 3 ,
respectively.
On other systems, they may use a separate network database file,
.Pa /etc/networks .
.Pp
In contrast to
.Xr gethostbyaddr 3 ,
the
.Fa net
argument is expected in machine byte order.
.Pp
The
.Fn setnetent ,
.Fn getnetent ,
and
.Fn endnetent
functions are deprecated and no longer have any effect.
They could be used in the past to iterate over entries in the former file
.Pa /etc/networks .
.Sh RETURN VALUES
The
.Fn getnetbyaddr
and
.Fn getnetbyname
functions return
.Dv NULL
if the requested entry is not found.
.Pp
The
.Fn getnetent
function always returns
.Dv NULL .
.Sh FILES
.Bl -tag -width /etc/hosts -compact
.It Pa /etc/hosts
The local host and network name database.
.El
.Sh SEE ALSO
.Xr getaddrinfo 3 ,
.Xr gethostbyname 3 ,
.Xr getnameinfo 3 ,
.Xr res_init 3 ,
.Xr hosts 5
.Sh STANDARDS
These functions conform to
.St -p1003.1-2008 .
.Sh HISTORY
The
.Fn getnetent ,
.Fn getnetbyaddr ,
.Fn getnetbyname ,
.Fn setnetent ,
and
.Fn endnetent
functions appeared in
.Bx 4.2 .
.Sh BUGS
The data space used by these functions is static; if future use
requires the data, it should be copied before any subsequent calls
to these functions overwrite it.
Only Internet network numbers are currently understood.
Expecting network numbers to fit in no more than 32 bits is naive.