.\"	$OpenBSD: getprotoent.3,v 1.5 1999/07/05 04:40:59 aaron 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. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. 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 June 4, 1993
.Dt GETPROTOENT 3
.Os
.Sh NAME
.Nm getprotoent ,
.Nm getprotobynumber ,
.Nm getprotobyname ,
.Nm setprotoent ,
.Nm endprotoent
.Nd get protocol entry
.Sh SYNOPSIS
.Fd #include <netdb.h>
.Ft struct protoent *
.Fn getprotoent "void"
.Ft struct protoent *
.Fn getprotobyname "char *name"
.Ft struct protoent *
.Fn getprotobynumber "int proto"
.Ft void
.Fn setprotoent "int stayopen"
.Ft void
.Fn endprotoent "void"
.Sh DESCRIPTION
The
.Fn getprotoent ,
.Fn getprotobyname ,
and
.Fn getprotobynumber
functions
each return a pointer to an object with the
following structure
containing the broken-out
fields of a line in the network protocol data base,
.Pa /etc/protocols .
.Bd -literal -offset indent
.Pp
struct	protoent {
	char	*p_name;	/* official name of protocol */
	char	**p_aliases;	/* alias list */
	int	p_proto;	/* protocol number */
};
.Ed
.Pp
The members of this structure are:
.Bl -tag -width p_aliases
.It Fa p_name
The official name of the protocol.
.It Fa p_aliases
A zero-terminated list of alternate names for the protocol.
.It Fa p_proto
The protocol number.
.El
.Pp
The
.Fn getprotoent
function
reads the next line of the file, opening the file if necessary.
.Pp
The
.Fn setprotoent
function
opens and rewinds the file.  If the
.Fa stayopen
flag is non-zero,
the net data base will not be closed after each call to
.Fn getprotobyname
or
.Fn getprotobynumber .
.Pp
The
.Fn endprotoent
function
closes the file.
.Pp
The
.Fn getprotobyname
function
and
.Fn getprotobynumber
sequentially search from the beginning
of the file until a matching
protocol name or
protocol number is found,
or until
.Dv EOF
is encountered.
.Sh RETURN VALUES
Null pointer
(0) returned on
.Dv EOF
or error.
.Sh FILES
.Bl -tag -width /etc/protocols -compact
.It Pa /etc/protocols
.El
.Sh SEE ALSO
.Xr protocols 5
.Sh HISTORY
The
.Fn getprotoent ,
.Fn getprotobynumber ,
.Fn getprotobyname ,
.Fn setprotoent ,
and
.Fn endprotoent
functions appeared in
.Bx 4.2 .
.Sh BUGS
These functions use a static data space;
if the data is needed for future use, it should be
copied before any subsequent calls overwrite it.
Only the Internet protocols are currently understood.