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.Dd $Mdocdate: May 31 2007 $
.Dt GETPROTOENT 3
.Os
.Sh NAME
.Nm getprotoent ,
.Nm getprotoent_r ,
.Nm getprotobynumber ,
.Nm getprotobynumber_r ,
.Nm getprotobyname ,
.Nm getprotobyname_r ,
.Nm setprotoent ,
.Nm setprotoent_r ,
.Nm endprotoent ,
.Nm endprotoent_r
.Nd get protocol entry
.Sh SYNOPSIS
.Fd #include <netdb.h>
.Ft struct protoent *
.Fn getprotoent "void"
.Ft int
.Fn getprotoent_r "struct protoent *protoent" "struct protoent_data *protoent_data"
.Ft struct protoent *
.Fn getprotobyname "const char *name"
.Ft int
.Fn getprotobyname_r "const char *name" "struct protoent *protoent" "struct protoent_data *protoent_data"
.Ft struct protoent *
.Fn getprotobynumber "int proto"
.Ft int
.Fn getprotobynumber_r "int proto" "struct protoent *protoent" "struct protoent_data *protoent_data"
.Ft void
.Fn setprotoent "int stayopen"
.Ft void
.Fn setprotoent_r "int stayopen" "struct protoent_data *protoent_data"
.Ft void
.Fn endprotoent "void"
.Ft void
.Fn endprotoent_r "struct protoent_data *protoent_data"
.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 database,
.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 null-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 protocol database 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
and
.Fn getprotobynumber
functions sequentially search from the beginning of the file until a
matching protocol name or protocol number is found, or until
.Dv EOF
is encountered.
.Pp
The
.Fn getprotoent_r ,
.Fn getprotobyport_r ,
.Fn getprotobyname_r ,
.Fn setprotoent_r ,
and
.Fn endprotoent_r
functions are reentrant versions of the above functions that take a
pointer to a
.Vt protoent_data
structure which is used to store state information.
The structure must be zero-filled before it is used
and should be considered opaque for the sake of portability.
.Pp
The
.Fn getprotoent_r ,
.Fn getprotobyport_r ,
and
.Fn getprotobyname_r
functions
also take a pointer to a
.Vt protoent
structure which is used to store the results of the database lookup.
.Sh RETURN VALUES
The
.Fn getprotoent ,
.Fn getprotobyport ,
and
.Fn getprotobyname
functions return a pointer to a
.Vt protoent
structure on success or a null pointer if end-of-file
is reached or an error occurs.
.Pp
The
.Fn getprotoent_r ,
.Fn getprotobyport_r ,
and
.Fn getprotobyname_r
functions return 0 on success or \-1 if end-of-file
is reached or an error occurs.
.Sh FILES
.Bl -tag -width /etc/protocols -compact
.It Pa /etc/protocols
.El
.Sh SEE ALSO
.Xr protocols 5
.Sh STANDARDS
The
.Fn getprotoent ,
.Fn getprotobynumber ,
.Fn getprotobyname ,
.Fn setprotoent ,
and
.Fn endprotoent
functions conform to
.St -p1003.1-2004 .
.Pp
The
.Fn getprotoent_r ,
.Fn getprotobyport_r ,
.Fn getprotobyname_r ,
.Fn setprotoent_r ,
and
.Fn endprotoent_r
functions are not currently standardized.
This implementation follows the API used by HP, IBM, and Digital.
.Sh HISTORY
The
.Fn getprotoent ,
.Fn getprotobynumber ,
.Fn getprotobyname ,
.Fn setprotoent ,
and
.Fn endprotoent
functions appeared in
.Bx 4.2 .
.Pp
The
.Fn getprotoent_r ,
.Fn getprotobyport_r ,
.Fn getprotobyname_r ,
.Fn setprotoent_r ,
and
.Fn endprotoent_r
functions appeared in
.Ox 3.7 .
.Sh BUGS
The non-reentrant 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.