50c317ac7c
Point out that FreeBSD libc has compat stubs for GNU glibc NSS modules which access NSDB_PASSWD/NSDB_GROUP, but not NSDB_HOSTS; based on painful experience porting nss_mdns. Reviewed by: ru
261 lines
6.3 KiB
Groff
261 lines
6.3 KiB
Groff
.\" $NetBSD: nsdispatch.3,v 1.8 1999/03/22 19:44:53 garbled Exp $
|
|
.\"
|
|
.\" 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.
|
|
.\" 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.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd January 22, 2007
|
|
.Dt NSDISPATCH 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm nsdispatch
|
|
.Nd name-service switch dispatcher routine
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In sys/types.h
|
|
.In stdarg.h
|
|
.In nsswitch.h
|
|
.Ft int
|
|
.Fo nsdispatch
|
|
.Fa "void *retval"
|
|
.Fa "const ns_dtab dtab[]"
|
|
.Fa "const char *database"
|
|
.Fa "const char *method_name"
|
|
.Fa "const ns_src defaults[]"
|
|
.Fa "..."
|
|
.Fc
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn nsdispatch
|
|
function invokes the methods specified in
|
|
.Va dtab
|
|
in the order given by
|
|
.Xr nsswitch.conf 5
|
|
for the database
|
|
.Va database
|
|
until a successful entry is found.
|
|
.Pp
|
|
.Va retval
|
|
is passed to each method to modify as necessary, to pass back results to
|
|
the caller of
|
|
.Fn nsdispatch .
|
|
.Pp
|
|
Each method has the function signature described by the typedef:
|
|
.Pp
|
|
.Ft typedef int
|
|
.Fn \*(lp*nss_method\*(rp "void *retval" "void *mdata" "va_list *ap" ;
|
|
.Pp
|
|
.Va dtab
|
|
is an array of
|
|
.Va ns_dtab
|
|
structures, which have the following format:
|
|
.Bd -literal -offset indent
|
|
typedef struct _ns_dtab {
|
|
const char *src;
|
|
nss_method method;
|
|
void *mdata;
|
|
} ns_dtab;
|
|
.Ed
|
|
.Pp
|
|
.Bd -ragged -offset indent
|
|
The
|
|
.Fa dtab
|
|
array should consist of one entry for each source type that is
|
|
implemented, with
|
|
.Va src
|
|
as the name of the source,
|
|
.Va method
|
|
as a function which handles that source, and
|
|
.Va mdata
|
|
as a handle on arbitrary data to be passed to the method.
|
|
The last entry in
|
|
.Va dtab
|
|
should contain
|
|
.Dv NULL
|
|
values for
|
|
.Va src ,
|
|
.Va method ,
|
|
and
|
|
.Va mdata .
|
|
.Ed
|
|
.Pp
|
|
Additionally, methods may be implemented in NSS modules, in
|
|
which case they are selected using the
|
|
.Fa database
|
|
and
|
|
.Fa method_name
|
|
arguments along with the configured source.
|
|
(The methods supplied via
|
|
.Fa dtab
|
|
take priority over those implemented in NSS modules in the event
|
|
of a conflict.)
|
|
.Pp
|
|
.Va defaults
|
|
contains a list of default sources to try if
|
|
.Xr nsswitch.conf 5
|
|
is missing or corrupted, or if there is no 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 _ns_src {
|
|
const char *src;
|
|
u_int32_t flags;
|
|
} ns_src;
|
|
.Ed
|
|
.Pp
|
|
.Bd -ragged -offset indent
|
|
The
|
|
.Fa defaults
|
|
array should consist of one entry for each source to be configured by
|
|
default indicated by
|
|
.Va src ,
|
|
and
|
|
.Va flags
|
|
set to the criterion desired
|
|
(usually
|
|
.Dv NS_SUCCESS ;
|
|
refer to
|
|
.Sx Method 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 the source
|
|
.Sq files
|
|
that may be used by callers which do not require complicated default
|
|
rules.
|
|
.Ed
|
|
.Pp
|
|
.Sq Va ...
|
|
are optional extra arguments, which are passed to the appropriate method
|
|
as a variable argument list of the type
|
|
.Vt va_list .
|
|
.Ss Valid source types
|
|
While there is support for arbitrary sources, the following
|
|
#defines for commonly implemented sources are available:
|
|
.Bl -column NSSRC_COMPAT compat -offset indent
|
|
.It Sy "#define value"
|
|
.It Dv NSSRC_FILES Ta """files""
|
|
.It Dv NSSRC_DNS Ta """dns""
|
|
.It Dv NSSRC_NIS Ta """nis""
|
|
.It Dv NSSRC_COMPAT Ta """compat""
|
|
.El
|
|
.Pp
|
|
Refer to
|
|
.Xr nsswitch.conf 5
|
|
for a complete description of what each source type is.
|
|
.Pp
|
|
.Ss Method return values
|
|
The
|
|
.Vt nss_method
|
|
functions must return one of the following values depending upon status
|
|
of the lookup:
|
|
.Bl -column "Return value" "Status code"
|
|
.It Sy "Return value Status code"
|
|
.It Dv NS_SUCCESS Ta success
|
|
.It Dv NS_NOTFOUND Ta notfound
|
|
.It Dv NS_UNAVAIL Ta unavail
|
|
.It Dv NS_TRYAGAIN Ta tryagain
|
|
.It Dv NS_RETURN Ta -none-
|
|
.El
|
|
.Pp
|
|
Refer to
|
|
.Xr nsswitch.conf 5
|
|
for a complete description of each status code.
|
|
.Pp
|
|
The
|
|
.Fn nsdispatch
|
|
function returns the value of the method that caused the dispatcher to
|
|
terminate, or
|
|
.Dv NS_NOTFOUND
|
|
otherwise.
|
|
.Sh NOTES
|
|
.Fx Ns 's
|
|
.Lb libc
|
|
provides stubs for compatibility with NSS modules
|
|
written for the
|
|
.Tn GNU
|
|
C Library
|
|
.Nm nsswitch
|
|
interface.
|
|
However, these stubs only support the use of the
|
|
.Dq Li passwd
|
|
and
|
|
.Dq Li group
|
|
databases.
|
|
.Sh SEE ALSO
|
|
.Xr hesiod 3 ,
|
|
.Xr stdarg 3 ,
|
|
.Xr nsswitch.conf 5 ,
|
|
.Xr yp 8
|
|
.Sh HISTORY
|
|
The
|
|
.Fn nsdispatch
|
|
function first appeared in
|
|
.Fx 5.0 .
|
|
It was imported from the
|
|
.Nx
|
|
Project,
|
|
where it appeared first in
|
|
.Nx 1.4 .
|
|
Support for NSS modules first appeared in
|
|
.Fx 5.1 .
|
|
.Sh AUTHORS
|
|
Luke Mewburn
|
|
.Aq lukem@netbsd.org
|
|
wrote this freely-distributable name-service switch implementation,
|
|
using ideas from the
|
|
.Tn ULTRIX
|
|
svc.conf(5)
|
|
and
|
|
.Tn Solaris
|
|
nsswitch.conf(4)
|
|
manual pages.
|
|
The
|
|
.Fx
|
|
Project
|
|
added the support for threads and NSS modules, and normalized the uses
|
|
of
|
|
.Fn nsdispatch
|
|
within the standard C library.
|