.lf 1 stdin
.TH SLAPO-DYNLIST 5 "2020/04/28" "OpenLDAP 2.4.50"
.\" Copyright 1998-2020 The OpenLDAP Foundation, All Rights Reserved.
.\" Copying restrictions apply.  See the COPYRIGHT file.
.\" $OpenLDAP$
.SH NAME
slapo\-dynlist \- Dynamic List overlay to slapd
.SH SYNOPSIS
/etc/openldap/slapd.conf
.SH DESCRIPTION
The
.B dynlist
overlay to
.BR slapd (8)
allows expansion of dynamic groups and more.
Any time an entry with a specific objectClass (defined in the overlay configuration) is being returned,
the LDAP URI-valued occurrences of a specific attribute (also defined in the overlay configuration) are
expanded into the corresponding entries, and the values
of the attributes listed in the URI are added to the original
entry.
No recursion is allowed, to avoid potential infinite loops.

Since the resulting entry is dynamically constructed,
it does not exist until it is constructed while being returned.
As a consequence, dynamically added attributes do not participate
in the filter matching phase of the search request handling.
In other words, \fIfiltering for dynamically added attributes always fails\fP.

The resulting entry must comply with the LDAP data model, so constraints
are enforced.
For example, if a \fISINGLE\-VALUE\fP attribute is listed,
only the first value found during the list expansion appears in the final entry.
The above described behavior is disabled when the \fImanageDSAit\fP
control (RFC 3296) is used.
In that case, the contents of the dynamic group entry is returned;
namely, the URLs are returned instead of being expanded.

.SH CONFIGURATION
The config directives that are specific to the
.B dynlist
overlay must be prefixed by
.BR dynlist\- ,
to avoid potential conflicts with directives specific to the underlying 
database or to other stacked overlays.

.TP
.B overlay dynlist
This directive adds the dynlist overlay to the current database,
or to the frontend, if used before any database instantiation; see
.BR slapd.conf (5)
for details.

.LP
This
.B slapd.conf
configuration option is defined for the dynlist overlay. It may have multiple 
occurrences, and it must appear after the
.B overlay
directive.
.TP
.B dynlist\-attrset <group-oc> [<URI>] <URL-ad> [[<mapped-ad>:]<member-ad> ...]
The value 
.B group\-oc
is the name of the objectClass that triggers the dynamic expansion of the
data.

The optional
.B URI
restricts expansion only to entries matching the \fIDN\fP,
the \fIscope\fP and the \fIfilter\fP portions of the URI.

The value
.B URL-ad
is the name of the attributeDescription that contains the URI that is 
expanded by the overlay; if none is present, no expansion occurs.
If the intersection of the attributes requested by the search operation 
(or the asserted attribute for compares) and the attributes listed 
in the URI is empty, no expansion occurs for that specific URI.
It must be a subtype of \fIlabeledURI\fP.

The value
.B member-ad
is optional; if present, the overlay behaves as a dynamic group: this
attribute will list the DN of the entries resulting from the internal search.
In this case, the \fIattrs\fP portion of the URIs in the
.B URL-ad
attribute must be absent, and the \fIDN\fPs 
of all the entries resulting from the expansion of the URIs are listed
as values of this attribute.
Compares that assert the value of the
.B member-ad
attribute of entries with 
.B group-oc
objectClass apply as if the DN of the entries resulting from the expansion 
of the URI were present in the 
.B group-oc 
entry as values of the
.B member-ad
attribute.

Alternatively, 
.B mapped-ad
can be used to remap attributes obtained through expansion. 
.B member-ad
attributes are not filled by expanded DN, but are remapped as
.B mapped-ad 
attributes.  Multiple mapping statements can be used.

.LP
The dynlist overlay may be used with any backend, but it is mainly 
intended for use with local storage backends.
In case the URI expansion is very resource-intensive and occurs frequently
with well-defined patterns, one should consider adding a proxycache
later on in the overlay stack.

.SH AUTHORIZATION
By default the expansions are performed using the identity of the current
LDAP user.
This identity may be overridden by setting the
.B dgIdentity
attribute in the group's entry to the DN of another LDAP user.
In that case the dgIdentity will be used when expanding the URIs in the object.
Setting the dgIdentity to a zero-length string will cause the expansions
to be performed anonymously.
Note that the dgIdentity attribute is defined in the
.B dyngroup
schema, and this schema must be loaded before the dgIdentity
authorization feature may be used.
If the
.B dgAuthz
attribute is also present in the group's entry, its values are used
to determine what identities are authorized to use the
.B dgIdentity
to expand the group.
Values of the 
.B dgAuthz
attribute must conform to the (experimental) \fIOpenLDAP authz\fP syntax.

.SH EXAMPLE
This example collects all the email addresses of a database into a single
entry; first of all, make sure that slapd.conf contains the directives:

.LP
.nf
    include /path/to/dyngroup.schema
    # ...

    database <database>
    # ...

    overlay dynlist
    dynlist\-attrset groupOfURLs memberURL
.fi
.LP
and that slapd loads dynlist.la, if compiled as a run-time module;
then add to the database an entry like
.LP
.nf
    dn: cn=Dynamic List,ou=Groups,dc=example,dc=com
    objectClass: groupOfURLs
    cn: Dynamic List
    memberURL: ldap:///ou=People,dc=example,dc=com?mail?sub?(objectClass=person)
.fi

If no <attrs> are provided in the URI, all (non-operational) attributes are
collected.

This example implements the dynamic group feature on the 
.B member
attribute:

.LP
.nf
    include /path/to/dyngroup.schema
    # ...

    database <database>
    # ...

    overlay dynlist
    dynlist\-attrset groupOfURLs memberURL member
.fi
.LP

A dynamic group with dgIdentity authorization could be created with an
entry like
.LP
.nf
    dn: cn=Dynamic Group,ou=Groups,dc=example,dc=com
    objectClass: groupOfURLs
    objectClass: dgIdentityAux
    cn: Dynamic Group
    memberURL: ldap:///ou=People,dc=example,dc=com??sub?(objectClass=person)
    dgIdentity: cn=Group Proxy,ou=Services,dc=example,dc=com
.fi

.SH FILES
.TP
/etc/openldap/slapd.conf
default slapd configuration file
.SH SEE ALSO
.BR slapd.conf (5),
.BR slapd\-config (5),
.BR slapd (8).
The
.BR slapo\-dynlist (5)
overlay supports dynamic configuration via
.BR back-config .
.SH ACKNOWLEDGEMENTS
.P
This module was written in 2004 by Pierangelo Masarati for SysNet s.n.c.
.P
Attribute remapping was contributed in 2008 by Emmanuel Dreyfus.