232 lines
6.1 KiB
Groff
232 lines
6.1 KiB
Groff
.\" $NetBSD: nsdispatch.3,v 1.8 1999/03/22 19:44:53 garbled Exp $
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.\" Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to The NetBSD Foundation
|
|
.\" by Luke Mewburn.
|
|
.\"
|
|
.\" 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 NetBSD
|
|
.\" Foundation, Inc. and its contributors.
|
|
.\" 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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 January 19, 1999
|
|
.Dt NSDISPATCH 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm nsdispatch
|
|
.Nd name-service switch dispatcher routine
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.Fd #include <nsswitch.h>
|
|
.Ft int
|
|
.Fo nsdispatch
|
|
.Fa "void *retval"
|
|
.Fa "const ns_dtab dtab[]"
|
|
.Fa "const char *database"
|
|
.Fa "const char *method"
|
|
.Fa "const ns_src defaults[]"
|
|
.Fa "..."
|
|
.Fc
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn nsdispatch
|
|
function invokes the callback functions specified in
|
|
.Va dtab
|
|
in the order given in
|
|
.Pa /etc/nsswitch.conf
|
|
for the database
|
|
.Va database
|
|
until a successful entry is found.
|
|
.Pp
|
|
.Va retval
|
|
is passed to each callback function to modify as necessary
|
|
(to pass back to the caller of
|
|
.Fn nsdispatch )
|
|
.Pp
|
|
.Va dtab
|
|
is an array of
|
|
.Va ns_dtab
|
|
structures, which have the following format:
|
|
.Bd -literal -offset indent
|
|
typedef struct {
|
|
const char *src;
|
|
int (*cb)(void *retval, void *cb_data, va_list ap);
|
|
void *cb_data;
|
|
} ns_dtab;
|
|
.Ed
|
|
.Pp
|
|
.Bd -ragged -offset indent
|
|
For each source type that is implemented, an entry with
|
|
.Va src
|
|
set to the name of the source,
|
|
.Va cb
|
|
defined as a function which handles that source, and
|
|
.Va cb_data
|
|
is used to pass arbritrary data to the callback function.
|
|
The last entry in
|
|
.Va dtab
|
|
should contain
|
|
.Dv NULL
|
|
values for
|
|
.Va src ,
|
|
.Va cb ,
|
|
and
|
|
.Va cb_data .
|
|
.Ed
|
|
.Pp
|
|
.Va method
|
|
is usually the name of the function calling
|
|
.Fn nsdispatch .
|
|
When dynamic loading is supported, a symbol constructed from
|
|
.Va database ,
|
|
the current source, and
|
|
.Va method
|
|
will be used as the name to invoke the dynamically loaded function.
|
|
.Pp
|
|
.Va defaults
|
|
contains a list of default sources to try in the case of
|
|
a missing or corrupt
|
|
.Xr nsswitch.conf 5 ,
|
|
or if there isn't a relevant entry for
|
|
.Va database .
|
|
It is an array of
|
|
.Va ns_src
|
|
structures, which have the following format:
|
|
.Bd -literal -offset indent
|
|
typedef struct {
|
|
const char *src;
|
|
u_int32_t flags;
|
|
} ns_src;
|
|
.Ed
|
|
.Pp
|
|
.Bd -ragged -offset indent
|
|
For each default source type, an entry with
|
|
.Va src
|
|
set to the name of the source, and
|
|
.Va flags
|
|
set to the relevant flags
|
|
(usually
|
|
.Dv NS_SUCCESS ;
|
|
refer to
|
|
.Sx Callback return values
|
|
for more information).
|
|
The last entry in
|
|
.Va defaults
|
|
should have
|
|
.Va src
|
|
set to
|
|
.Dv NULL
|
|
and
|
|
.Va flags
|
|
set to 0.
|
|
.Pp
|
|
For convenience, a global variable defined as:
|
|
.Dl extern const ns_src __nsdefaultsrc[];
|
|
exists which contains a single default entry for
|
|
.Sq files
|
|
for use by callers which don't require complicated default rules.
|
|
.Ed
|
|
.Pp
|
|
.Sq Va ...
|
|
are optional extra arguments, which
|
|
are passed to the appropriate callback function as a variable argument
|
|
list of the type
|
|
.Va va_list .
|
|
.Ss Valid source types
|
|
Whilst there is support for arbitrary sources, the following
|
|
#defines for commonly implementated sources are available:
|
|
.Bl -column NS_COMPAT COMPAT -offset indent
|
|
.It Sy "#define value"
|
|
.It "NSSRC_FILES ""files"""
|
|
.It "NSSRC_DNS ""dns"""
|
|
.It "NSSRC_NIS ""nis"""
|
|
.It "NSSRC_COMPAT ""compat"""
|
|
.El
|
|
.Pp
|
|
Refer to
|
|
.Xr nsswitch.conf 5
|
|
for a complete description of what each source type is.
|
|
.Pp
|
|
.Ss Callback return values
|
|
The callback functions should return one of the following values
|
|
depending upon status of the lookup:
|
|
.Bl -column NS_NOTFOUND -offset indent
|
|
.It Sy "Return value Status code"
|
|
.It "NS_SUCCESS success"
|
|
.It "NS_NOTFOUND notfound"
|
|
.It "NS_UNAVAIL unavail"
|
|
.It "NS_TRYAGAIN tryagain"
|
|
.El
|
|
.Pp
|
|
Refer to
|
|
.Xr nsswitch.conf 5
|
|
for a complete description of what each status code is.
|
|
.Pp
|
|
.Nm
|
|
returns the value of the callback that caused the dispatcher to finish,
|
|
or NS_NOTFOUND otherwise.
|
|
.Sh SEE ALSO
|
|
.Xr hesiod 3 ,
|
|
.Xr stdarg 3 ,
|
|
.Xr ypclnt 3 ,
|
|
.Xr nsswitch.conf 5
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
routines first appeared in
|
|
.Fx 4.1 .
|
|
They were imported from the
|
|
.Nx
|
|
Project,
|
|
where they appeared first in
|
|
.Nx 1.4 .
|
|
.Sh AUTHORS
|
|
Luke Mewburn
|
|
.Aq lukem@netbsd.org
|
|
wrote this freely distributable name-service switch implementation,
|
|
using ideas from the
|
|
.Tn ULTRIX
|
|
.Xr svc.conf 5
|
|
and
|
|
.Tn Solaris
|
|
.Xr nsswitch.conf 4
|
|
manual pages.
|
|
.Sh BUGS
|
|
The
|
|
.Nm
|
|
routines are not thread safe.
|
|
This will be rectified in the future.
|
|
.Pp
|
|
Currently there is no support for dynamically loadable dispatcher callback
|
|
functions.
|
|
It is anticipated that this will be added in the future in the back-end
|
|
without requiring changes to code that invokes
|
|
.Fn nsdispatch .
|