-.TH SLAPD_META 5 "28 April 2002" "OpenLDAP LDVERSION"
-.\" Copyright 1998-2002 The OpenLDAP Foundation, All Rights Reserved.
+.TH SLAPD-META 5 "RELEASEDATE" "OpenLDAP LDVERSION"
+.\" Copyright 1998-2005 The OpenLDAP Foundation, All Rights Reserved.
.\" Copying restrictions apply. See the COPYRIGHT file.
.\" Copyright 2001, Pierangelo Masarati, All rights reserved. <ando@sys-net.it>
.\" $OpenLDAP$
.\" and maybe manual pages for librewrite.
.\"
.SH NAME
-slapd_meta \- metadirectory backend
+slapd-meta \- metadirectory backend
.SH SYNOPSIS
ETCDIR/slapd.conf
.SH DESCRIPTION
belonging to a single Directory Information Tree (DIT).
.LP
A basic knowledge of the functionality of the
-.BR slapd_ldap (5)
+.BR slapd\-ldap (5)
backend is recommended.
This backend has been designed as an enhancement of the ldap backend.
The two backends share many features (actually they also share
carefully considered.
In the examples section, some typical scenarios will be discussed.
.SH EXAMPLES
-There are examples various places in this document, as well as in the
+There are examples in various places in this document, as well as in the
slapd/back-meta/data/ directory in the OpenLDAP source tree.
.SH CONFIGURATION
-The
-.BR slapd.conf (5)
-options in this category apply to the META backend database.
+These
+.B slapd.conf
+options apply to the META backend database.
That is, they must follow a "database meta" line and come before any
subsequent "backend" or "database" lines.
+Other database options are described in the
+.BR slapd.conf (5)
+manual page.
.LP
-Note: as with the
-.B ldap
-backend, operational attributes related to entry creation/modification
-should not be used, as they would be passed to the target servers,
-generating an error.
-Moreover, it makes little sense to use such attributes in proxying, as
-the proxy server doesn't actually store data, so it should have no
-knowledge of such attributes.
-While code to strip the modification attributes has been put in place
-(and #ifdef'd), it implies unmotivated overhead.
-So it is strongly recommended to set
+Note: In early versions of back-ldap and back-meta it was recommended to always set
.LP
+.RS
.nf
- lastmod off
+lastmod off
.fi
+.RE
.LP
for every
.B ldap
and
.B meta
-backend.
-.SH "SPECIAL CONFIGURATION DIRECTIVES"
+database.
+This is because operational attributes related to entry creation and
+modification should not be proxied, as they could be mistakenly written
+to the target server(s), generating an error.
+The current implementation automatically sets lastmod to off, so its use
+is redundant and should be omitted, because the lastmod directive will
+be deprecated in the future.
+
+.SH SPECIAL CONFIGURATION DIRECTIVES
Target configuration starts with the "uri" directive.
All the configuration directives that are not specific to targets
should be defined first for clarity, including those that are common
to all backends.
They are:
+
.TP
.B default-target none
This directive forces the backend to reject all those operations
They include: add, delete, modify, modrdn; compare is not included, as
well as bind since, as they don't alter entries, in case of multiple
matches an attempt is made to perform the operation on any candidate
-target, with the constraint that at most on must succeed.
+target, with the constraint that at most one must succeed.
This directive can also be used when processing targets to mark a
specific target as default.
+
.TP
.B dncache-ttl {forever|disabled|<ttl>}
-This directive sets the time-to-live of the dn cache.
-This caches the target that holds a given dn to speed up target
+This directive sets the time-to-live of the DN cache.
+This caches the target that holds a given DN to speed up target
selection in case multiple targets would result from an uncached
-search; forever means cache never expires; disabled means no dn
+search; forever means cache never expires; disabled means no DN
caching; otherwise a valid ( > 0 ) ttl in seconds is required.
-.SH "TARGET SPECIFICATION"
+
+.TP
+.B nretries {forever|never|<nretries>}
+This directive defines how many times a bind should be retried
+in case of temporary failure in contacting a target. If defined
+before any target specification, it applies to all targets (by default,
+.BR never );
+the global value can be overridden by redefinitions inside each target
+specification.
+
+.TP
+.B onerr {CONTINUE|stop}
+This directive allows to select the behavior in case an error is returned
+by one target during a search.
+The default, \fBcontinue\fP, consists in continuing the operation,
+trying to return as much data as possible.
+If this statement is set to \fBstop\fP, the search is terminated as soon
+as an error is returned by one target, and the error is immediately
+propagated to the client.
+
+.TP
+.B rebind-as-user {NO|yes}
+If this option is given, the client's bind credentials are remembered
+for rebinds when chasing referrals.
+
+.SH TARGET SPECIFICATION
Target specification starts with a "uri" directive:
+
.TP
.B uri <protocol>://[<host>[:<port>]]/<naming context>
The "server" directive that was allowed in the LDAP backend (although
-deprecated) has been discarded in the Meta backend.
-The <protocol> part can be anything ldap_initialize(3) accepts
-({ldap|ldaps|ldapi} and variants); <host> and <port> may be omitted,
-defaulting to whatever is set in /etc/ldap.conf (correct me!?!).
+deprecated) has been completely discarded in the Meta backend.
+The <protocol> part can be anything
+.BR ldap_initialize (3)
+accepts ({ldap|ldaps|ldapi} and variants); <host> and <port> may be
+omitted, defaulting to whatever is set in
+.BR ldap.conf (5).
The <naming context> part is mandatory.
It must end with one of the naming contexts defined for the backend,
e.g.:
.LP
+.RS
.nf
- suffix "dc=foo,dc=com"
- uri "ldap://x.foo.com/dc=x,dc=foo,dc=com"
+suffix "\fBdc=foo,dc=com\fP"
+uri "ldap://x.foo.com/dc=x,\fBdc=foo,dc=com\fP"
.fi
-.LP
+
+.RE
+.RS
The <naming context> part doesn't need to be unique across the targets;
it may also match one of the values of the "suffix" directive.
+Multiple URIs may be defined in a single argument. The URIs must
+be separated by TABs (e.g. '\\t'; commas or spaces, unlike back-ldap,
+will not work,
+because they are legal in the <naming context>, and we don't want to use
+URL-encoded <naming context>s), and the additional URIs must have
+no <naming context> part. This causes the underlying library
+to contact the first server of the list that responds.
+.RE
+
.TP
.B default-target [<target>]
The "default-target" directive can also be used during target specification.
The optional number marks target <target> as the default one, starting
from 1.
Target <target> must be defined.
+
.TP
-.B binddn <administrative dn for ac purposes>
-This directive, as in the LDAP backend, allows to define the dn that is
-used to query the target server for acl checking; it should have read
-access on the target server to attributes used on the proxy for acl
-checking.
+.B acl-authcDN "<administrative DN for access control purposes>"
+DN which is used to query the target server for acl checking,
+as in the LDAP backend; it is supposed to have read access
+on the target server to attributes used on the proxy for acl checking.
There is no risk of giving away such values; they are only used to
check permissions.
+.B The acl-authcDN identity is by no means implicitly used by the proxy
+.B when the client connects anonymously.
+
+.TP
+.B acl-passwd <password>
+Password used with the
+.B
+acl-authcDN
+above.
+
+.TP
+.B chase-referrals {YES|no}
+enable/disable automatic referral chasing, which is delegated to the
+underlying libldap, with rebinding eventually performed if the
+\fBrebind-as-user\fP directive is used. The default is to chase referrals.
+If set before any target specification, it affects all targets, unless
+overridden by any per-target directive.
+
+.TP
+.B tls {[try-]start|[try-]propagate}
+execute the start TLS extended operation when the connection is initialized;
+only works if the URI directive protocol scheme is not \fBldaps://\fP.
+\fBpropagate\fP issues the Start TLS exop only if the original
+connection did.
+The \fBtry-\fP prefix instructs the proxy to continue operations
+if start TLS failed; its use is highly deprecated.
+If set before any target specification, it affects all targets, unless
+overridden by any per-target directive.
+
+.TP
+.B t-f-support {NO|yes|discover}
+enable if the remote server supports absolute filters
+(see \fIdraft-zeilenga-ldap-t-f\fP for details).
+If set to
+.BR discover ,
+support is detected by reading the remote server's root DSE.
+If set before any target specification, it affects all targets, unless
+overridden by any per-target directive.
+
.TP
-.B bindpw <password for ac purposes>
-This directive sets the password for acl checking in conjunction
-with the above mentioned "binddn" directive.
+.B timeout [{add|delete|modify|modrdn}=]<val> [...]
+This directive allows to set per-database, per-target and per-operation
+timeouts.
+If no operation is specified, it affects all.
+Currently, only write operations are addressed, because searches
+can already be limited by means of the
+.B limits
+directive (see
+.BR slapd.conf (5)
+for details), and other operations are not supposed to incur into the
+need for timeouts.
+Note: if the timelimit is exceeded, the operation is abandoned;
+the protocol does not provide any means to rollback the operation,
+so the client will not know if the operation eventually succeeded or not.
+If set before any target specification, it affects all targets, unless
+overridden by any per-target directive.
+
.TP
-.B pseudorootdn <substitute dn in case of rootdn bind>
-This directive, if present, sets the dn that will be substituted to
-the bind dn if a bind with the backend's "rootdn" succeeds.
+.B pseudorootdn "<substitute DN in case of rootdn bind>"
+This directive, if present, sets the DN that will be substituted to
+the bind DN if a bind with the backend's "rootdn" succeeds.
The true "rootdn" of the target server ought not be used; an arbitrary
-administrative dn should used instead.
+administrative DN should used instead.
+
.TP
-.B pseudorootpw <substitute password in case of rootdn bind>
+.B pseudorootpw "<substitute password in case of rootdn bind>"
This directive sets the credential that will be used in case a bind
with the backend's "rootdn" succeeds, and the bind is propagated to
-the target using the "pseudorootdn" dn.
+the target using the "pseudorootdn" DN.
+
+Note: cleartext credentials must be supplied here; as a consequence,
+using the pseudorootdn/pseudorootpw directives is inherently unsafe.
+
+.TP
+.B pseudoroot-bind-defer {NO|yes}
+This directive, when set to
+.BR yes ,
+causes the authentication to the remote servers with the pseudo-root
+identity to be deferred until actually needed by subsequent operations.
+
.TP
.B rewrite* ...
The rewrite options are described in the "REWRITING" section.
+
.TP
-.B suffixmassage <virtual naming context> <real naming context>
+.B suffixmassage "<virtual naming context>" "<real naming context>"
All the directives starting with "rewrite" refer to the rewrite engine
that has been added to slapd.
The "suffixmassage" directive was introduced in the LDAP backend to
However, both for backward compatibility and for ease of configuration
when simple suffix massage is required, it has been preserved.
It wraps the basic rewriting instructions that perform suffix
-massaging.
+massaging. See the "REWRITING" section for a detailed list
+of the rewrite rules it implies.
.LP
Note: this also fixes a flaw in suffix massaging, which operated
on (case insensitive) DNs instead of normalized DNs,
so "dc=foo, dc=com" would not match "dc=foo,dc=com".
.LP
See the "REWRITING" section.
+
.TP
-.B map {objectClass|attribute} {<source>|*} [<dest>|*]
+.B map "{attribute|objectclass} [<local name>|*] {<foreign name>|*}"
This maps object classes and attributes as in the LDAP backend.
See
.BR slapd-ldap (5).
-.SH "SCENARIOS"
+.SH SCENARIOS
A powerful (and in some sense dangerous) rewrite engine has been added
to both the LDAP and Meta backends.
While the former can gain limited beneficial effects from rewriting
say "dc=a,dc=foo,dc=com" and "dc=b,dc=foo,dc=com".
Then, an unambiguous Meta database can be configured as:
.LP
+.RS
.nf
- database meta
- suffix "dc=foo,dc=com"
- uri "ldap://a.foo.com/dc=a,dc=foo,dc=com"
- uri "ldap://b.foo.com/dc=b,dc=foo,dc=com"
+database meta
+suffix "\fBdc=foo,dc=com\fP"
+uri "ldap://a.foo.com/dc=a,\fBdc=foo,dc=com\fP"
+uri "ldap://b.foo.com/dc=b,\fBdc=foo,dc=com\fP"
.fi
+.RE
.LP
Operations directed to a specific target can be easily resolved
because there are no ambiguities.
spawning two searches to the targets.
.LP
2a) Two directory servers don't share any portion of naming context,
-but they'd present as a single DIT.
+but they'd present as a single DIT
[Caveat: uniqueness of (massaged) entries among the two servers is
assumed; integrity checks risk to incur in excessive overhead and have
-not been implemented.] Say we have "dc=bar,dc=org" and "o=Foo,c=US",
+not been implemented].
+Say we have "dc=bar,dc=org" and "o=Foo,c=US",
and we'd like them to appear as branches of "dc=foo,dc=com", say
"dc=a,dc=foo,dc=com" and "dc=b,dc=foo,dc=com".
Then we need to configure our Meta backend as:
.LP
+.RS
.nf
- database meta
- suffix "dc=foo,dc=com"
-
- uri "ldap://a.bar.com/dc=a,dc=foo,dc=com"
- suffixmassage "dc=a,dc=foo,dc=com" "dc=bar,dc=org"
-
- uri "ldap://b.foo.com/dc=b,dc=foo,dc=com"
- suffixmassage "dc=b,dc=foo,dc=com" "o=Foo,c=US"
+database meta
+suffix "dc=foo,dc=com"
+
+uri "ldap://a.bar.com/\fBdc=a,dc=foo,dc=com\fP"
+suffixmassage "\fBdc=a,dc=foo,dc=com\fP" "dc=bar,dc=org"
+
+uri "ldap://b.foo.com/\fBdc=b,dc=foo,dc=com\fP"
+suffixmassage "\fBdc=b,dc=foo,dc=com\fP" "o=Foo,c=US"
.fi
+.RE
.LP
Again, operations can be resolved without ambiguity, although
some rewriting is required.
2b) Consider the above reported scenario with the two servers
sharing the same naming context:
.LP
+.RS
.nf
- database meta
- suffix "dc=foo,dc=com"
-
- uri "ldap://a.bar.com/dc=foo,dc=com"
- suffixmassage "dc=foo,dc=com" "dc=bar,dc=org"
-
- uri "ldap://b.foo.com/dc=foo,dc=com"
- suffixmassage "dc=foo,dc=com" "o=Foo,c=US"
+database meta
+suffix "\fBdc=foo,dc=com\fP"
+
+uri "ldap://a.bar.com/\fBdc=foo,dc=com\fP"
+suffixmassage "\fBdc=foo,dc=com\fP" "dc=bar,dc=org"
+
+uri "ldap://b.foo.com/\fBdc=foo,dc=com\fP"
+suffixmassage "\fBdc=foo,dc=com\fP" "o=Foo,c=US"
.fi
+.RE
.LP
All the previous considerations hold, except that now there is
no way to unambiguously resolve a DN.
In this case, all the operations that require an unambiguous target
-selection will fail unless the dn is already cached or a default
+selection will fail unless the DN is already cached or a default
target has been set.
+Practical configurations may result as a combination of all the
+above scenarios.
.SH ACLs
Note on ACLs: at present you may add whatever ACL rule you desire
to to the Meta (and LDAP) backends.
find other exceptions: <ando@openldap.org>).
The rule
.LP
+.RS
.nf
-
access to dn="<dn>" attr=<attr>
- by dnattr=<dnattr> read
- by * none
+access to dn="<dn>" attr=<attr>
+ by dnattr=<dnattr> read
+ by * none
.fi
+.RE
.LP
cannot be matched iff the attribute that is being requested, <attr>,
is NOT <dnattr>, and the attribute that determines membership,
.SH REWRITING
A string is rewritten according to a set of rules, called a `rewrite
context'.
-The rules are based on Regular Expressions (POSIX regex) with
-substring matching; extensions are planned to allow basic variable
-substitution and map resolution of substrings.
+The rules are based on POSIX (''extended'') regular expressions (regex)
+with substring matching; basic variable substitution and map resolution
+of substrings is allowed by specific mechanisms detailed in the following.
The behavior of pattern matching/substitution can be altered by a set
of flags.
.LP
The underlying concept is to build a lightweight rewrite module
for the slapd server (initially dedicated to the LDAP backend).
.SH Passes
-An incoming string is matched agains a set of rules.
-Rules are made of a match pattern, a substitution pattern and a set of
-actions.
+An incoming string is matched against a set of rules.
+Rules are made of a regex match pattern, a substitution pattern
+and a set of actions, described by a set of flags.
In case of match a string rewriting is performed according to the
substitution pattern that allows to refer to substrings matched in the
incoming string.
The actions, if any, are finally performed.
The substitution pattern allows map resolution of substrings.
A map is a generic object that maps a substitution pattern to a value.
+The flags are divided in "Pattern matching Flags" and "Action Flags";
+the former alter the regex match pattern behavior while the latter
+alter the action that is taken after substitution.
.SH "Pattern Matching Flags"
.TP
.B `C'
honors case in matching (default is case insensitive)
.TP
.B `R'
-use POSIX Basic Regular Expressions (default is Extended)
+use POSIX ''basic'' regular expressions (default is ''extended'')
+.TP
+.B `M{n}'
+allow no more than
+.B n
+recursive passes for a specific rule; does not alter the max total count
+of passes, so it can only enforce a stricter limit for a specific rule.
.SH "Action Flags"
.TP
.B `:'
apply the rule once only (default is recursive)
.TP
.B `@'
-stop applying rules in case of match.
+stop applying rules in case of match; the current rule is still applied
+recursively; combine with `:' to apply the current rule only once
+and then stop.
.TP
.B `#'
stop current operation if the rule matches, and issue an `unwilling to
perform' error.
.TP
.B `G{n}'
-jump n rules back and forth (watch for loops!).
+jump
+.B n
+rules back and forth (watch for loops!).
Note that `G{1}' is implicit in every rule.
.TP
.B `I'
ignores errors in rule; this means, in case of error, e.g. issued by a
map, the error is treated as a missed match.
The `unwilling to perform' is not overridden.
-.LP
-The ordering of the flags is significant.
+.TP
+.B `U{n}'
+uses
+.B
+n
+as return code if the rule matches; the flag does not alter the recursive
+behavior of the rule, so, to have it performed only once, it must be used
+in combination with `:', e.g.
+.B `:U{16}'
+returns the value `16' after exactly one execution of the rule, if the
+pattern matches.
+As a consequence, its behavior is equivalent to `@', with the return
+code set to
+.BR n ;
+or, in other words, `@' is equivalent to `U{0}'.
+By convention, the freely available codes are above 16 included;
+the others are reserved.
+.LP
+The ordering of the flags can be significant.
For instance: `IG{2}' means ignore errors and jump two lines ahead
both in case of match and in case of error, while `G{2}I' means ignore
-errors, but jump thwo lines ahead only in case of match.
+errors, but jump two lines ahead only in case of match.
.LP
More flags (mainly Action Flags) will be added as needed.
.SH "Pattern matching:"
See
-.BR regex (7).
-.SH "String Substitution:"
-The string substitution happens according to a substitution pattern.
-.TP
-.B -
-substring substitution is allowed with the syntax `\\d' where `d' is a
-digit ranging 0-9 (0 is the full match).
-I see that 0-9 digit expansion is a widely accepted practise; however
-there is no technical reason to use such a strict limit.
-A syntax of the form `\\{ddd}' should be fine if there is any need to
-use a higher number of possible submatches.
-.TP
-.B -
-variable substitution will be allowed (at least when I figure out
-which kind of variable could be proficiently substituted)
-.TP
-.B -
-map lookup will be allowed (map lookup of substring matches in gdbm,
-ldap(!), math(?) and so on maps `a la sendmail'.
-.TP
-.B -
-subroutine invocation will make it possible to rewrite a submatch in
-terms of the output of another rewriteContext.
-.Sh "Old syntax:"
-.TP
-.B `\\' {0-9} [ `{' <name> [ `(' <args> `)' ] `}' ]
-where <name> is the name of a built-in map, and <args> are optional
-arguments to the map, if the map <name> requires them.
-The following experimental maps have been implemented:
-.TP
-.B \\n{xpasswd}
-maps the n-th substring match as uid to the gecos field in
-/etc/passwd;
-.TP
-.B \\n{xfile(/absolute/path)}
-maps the n-th substring match to a `key value' style plain text file.
-.TP
-.B \\n{xldap(ldap://url/with?%0?in?filter)
-maps the n-th substring match to an attribute retrieved by means of an
-LDAP url with substitution of %0 in the filter (NOT IMPL.)
-.SH "New scheme:"
-everything starting with `\\' requires substitution;
-.LP
-the only obvious exception is `\\\\', which is left as is;
-.LP
-the basic substitution is `\\d', where `d' is a digit;
-0 means the whole string, while 1-9 is a submatch;
+.BR regex (7)
+and/or
+.BR re_format (7).
+.SH "Substitution Pattern Syntax:"
+Everything starting with `%' requires substitution;
.LP
-in the outdated schema, the digit may be optionally
-followed by a `{', which means pipe the submatch into
-the map described by the string up to the following `}';
+the only obvious exception is `%%', which is left as is;
.LP
-the output of the map is used instead of the submatch;
+the basic substitution is `%d', where `d' is a digit;
+0 means the whole string, while 1-9 is a submatch;
.LP
-in the new schema, a `\\' followed by a `{' invokes an
-advanced substitution scheme.
+a `%' followed by a `{' invokes an advanced substitution.
The pattern is:
.LP
-.nf
- `\\' `{' [{ <op> }] <name> `(' <substitution schema> `)' `}'
-.fi
+.RS
+`%' `{' [ <op> ] <name> `(' <substitution> `)' `}'
+.RE
.LP
where <name> must be a legal name for the map, i.e.
.LP
+.RS
.nf
- <name> ::= [a-z][a-z0-9]* (case insensitive)
- <op> ::= `>' `|' `&' `&&' `*' `**' `$'
+<name> ::= [a-z][a-z0-9]* (case insensitive)
+<op> ::= `>' `|' `&' `&&' `*' `**' `$'
.fi
+.RE
.LP
-and <substitution schema> must be a legal substitution
-schema, with no limits on the nesting level.
+and <substitution> must be a legal substitution
+pattern, with no limits on the nesting level.
.LP
The operators are:
.TP
.TP
.B &
variable assignment; <name> defines a variable in the running
-operation structure which can be dereferenced later (NOT IMPL.)
+operation structure which can be dereferenced later; operator
+.B &
+assigns a variable in the rewrite context scope; operator
+.B &&
+assigns a variable that scopes the entire session, e.g. its value
+can be dereferenced later by other rewrite contexts
.TP
.B *
variable dereferencing; <name> must refer to a variable that is
-defined and assigned for the running operation (NOT IMPL.)
+defined and assigned for the running operation; operator
+.B *
+dereferences a variable scoping the rewrite context; operator
+.B **
+dereferences a variable scoping the whole session, e.g. the value
+is passed across rewrite contexts
.TP
.B $
parameter dereferencing; <name> must refer to an existing parameter;
the idea is to make some run-time parameters set by the system
-available to the rewrite engine, as the client host name, the bind dn
-if any, constant parameters initialized at config time, and so on (NOT
-IMPL.)
-.LP
-Note: as the slapd parsing routines escape backslashes ('\\'),
-a double backslash is required inside substitution patterns.
-To overcome the resulting heavy notation, the substitution escaping
-has been delegated to the `%' symbol, which should be used
-instead of `\\' in string substitution patterns.
-The symbol can be altered at will by redefining the related macro in
-"rewrite-int.h".
-In the current snapshot, all the `\\' on the left side of each rule
-(the regex pattern) must be converted in `\\\\'; all the `\\' on the
-right side of the rule (the substitution pattern) must be turned into
-`%'.
-In the following examples, the original (more readable) syntax is
-used.
+available to the rewrite engine, as the client host name, the bind DN
+if any, constant parameters initialized at config time, and so on;
+no parameter is currently set by either
+.B back\-ldap
+or
+.BR back\-meta ,
+but constant parameters can be defined in the configuration file
+by using the
+.B rewriteParam
+directive.
+.LP
+Substitution escaping has been delegated to the `%' symbol,
+which is used instead of `\e' in string substitution patterns
+because `\e' is already escaped by slapd's low level parsing routines;
+as a consequence, regex escaping requires two `\e' symbols,
+e.g. `\fB.*\e.foo\e.bar\fP' must be written as `\fB.*\e\e.foo\e\e.bar\fP'.
+.\"
+.\" The symbol can be altered at will by redefining the related macro in
+.\" "rewrite-int.h".
+.\"
.SH "Rewrite context:"
A rewrite context is a set of rules which are applied in sequence.
The basic idea is to have an application initialize a rewrite
appropriate rewrite context with the input string and obtains the
newly rewritten one if no errors occur.
.LP
-An interesting application, in the LDAP backend or in slapd itself,
-could associate each basic server operation to a rewrite context
-(most of them possibly aliasing the default one).
-Then, DN rewriting could take place at any invocation of a backend
-operation.
+Each basic server operation is associated to a rewrite context;
+they are divided in two main groups: client \-> server and
+server \-> client rewriting.
.LP
client -> server:
.LP
+.RS
.nf
- default if defined and no specific
- context is available
- bindDn bind
- searchBase search
- searchFilter search
- compareDn compare
- addDn add
- modifyDn modify
- modrDn modrdn
- newSuperiorDn modrdn
- deleteDn delete
+(default) if defined and no specific context
+ is available
+bindDN bind
+searchBase search
+searchFilter search
+searchFilterAttrDN search
+compareDN compare
+compareAttrDN compare AVA
+addDN add
+addAttrDN add AVA
+modifyDN modify
+modifyAttrDN modify AVA
+modrDN modrdn
+newSuperiorDN modrdn
+deleteDN delete
+exopPasswdDN passwd exop DN if proxy
.fi
+.RE
.LP
server -> client:
.LP
+.RS
.nf
- searchResult search (only if defined; no default)
+searchResult search (only if defined; no default;
+ acts on DN and DN-syntax attributes
+ of search results)
+searchAttrDN search AVA
+matchedDN all ops (only if applicable)
.fi
+.RE
.LP
.SH "Basic configuration syntax"
.TP
rewriting takes place (an easy way to stop rewriting without
altering too much the configuration file).
.TP
-.B rewriteContext <context name> [ alias <aliased context name> ]
+.B rewriteContext <context name> "[ alias <aliased context name> ]"
<Context name> is the name that identifies the context, i.e. the name
used by the application to refer to the set of rules it contains.
It is used also to reference sub contexts in string rewriting.
-A context may aliase another one.
+A context may alias another one.
In this case the alias context contains no rule, and any reference to
it will result in accessing the aliased one.
.TP
-.B rewriteRule <regex pattern> <substitution pattern> [ <flags> ]
-Determines how a tring can be rewritten if a pattern is matched.
+.B rewriteRule "<regex match pattern>" "<substitution pattern>" "[ <flags> ]"
+Determines how a string can be rewritten if a pattern is matched.
Examples are reported below.
.SH "Additional configuration syntax:"
.TP
-.B rewriteMap <map name> <map type> [ <map attrs> ]
+.B rewriteMap "<map type>" "<map name>" "[ <map attrs> ]"
Allows to define a map that transforms substring rewriting into
something else.
The map is referenced inside the substitution pattern of a rule.
.TP
.B rewriteParam <param name> <param value>
Sets a value with global scope, that can be dereferenced by the
-command `\\{$paramName}'.
-.TP
-.B rewriteMaxPasses <number of passes>
-Sets the maximum number of total rewriting passes taht can be
-performed in a signle rewriting operation (to avoid loops).
+command `%{$paramName}'.
+.TP
+.B rewriteMaxPasses <number of passes> [<number of passes per rule>]
+Sets the maximum number of total rewriting passes that can be
+performed in a single rewrite operation (to avoid loops).
+A safe default is set to 100; note that reaching this limit is still
+treated as a success; recursive invocation of rules is simply
+interrupted.
+The count applies to the rewriting operation as a whole, not
+to any single rule; an optional per-rule limit can be set.
+This limit is overridden by setting specific per-rule limits
+with the `M{n}' flag.
.SH "Configuration examples:"
.nf
- # set to `off' to disable rewriting
- rewriteEngine on
-
- # Everything defined here goes into the `default' context.
- # This rule changes the naming context of anything sent
- # to `dc=home,dc=net' to `dc=OpenLDAP, dc=org'
-
- rewriteRule "(.*)dc=home,[ ]?dc=net"
- "\\1dc=OpenLDAP, dc=org" ":"
-
- # Start a new context (ends input of the previous one).
- # This rule adds blancs between dn parts if not present.
- rewriteContext addBlancs
- rewriteRule "(.*),([^ ].*)" "\\1, \\2"
-
- # This one eats blancs
- rewriteContext eatBlancs
- rewriteRule "(.*),[ ](.*)" "\\1,\\2"
-
- # Here control goes back to the default rewrite
- # context; rules are appended to the existing ones.
- # anything that gets here is piped into rule `addBlancs'
- rewriteContext default
- rewriteRule ".*" "\\{>addBlancs(\\0)}" ":"
-
- # Anything with `uid=username' is looked up in
- # /etc/passwd for gecos (I know it's nearly useless,
- # but it is there just to test something fancy!). Note
- # the `I' flag that leaves `uid=username' in place if
- # `username' does not have a valid account, and the
- # `:' that forces the rule to be processed exactly once.
- rewriteContext uid2Gecos
- rewriteRule "(.*)uid=([a-z0-9]+),(.+)"
- "\\1cn=\\2{xpasswd},\\3" "I:"
-
- # Finally, in a bind, if one uses a `uid=username' dn,
- # it is rewritten in `cn=name surname' if possible.
- rewriteContext bindDn
- rewriteRule ".*" "\\{>addBlancs(\\{>uid2Gecos(\\0)})}" ":"
-
- # Rewrite the search base according to `default' rules.
- rewriteContext searchBase alias default
-
- # Search results with OpenLDAP dn are rewritten back with
- # `dc=home,dc=net' naming context, with spaces eaten.
- rewriteContext searchResult
- rewriteRule "(.*[^ ]?)[ ]?dc=OpenLDAP,[ ]?dc=org"
- "\\{>eatBlancs(\\1)}dc=home,dc=net" ":"
-
- # Bind with email instead of full dn: we first need
- # an ldap map that turns attributes into a dn (the
- # filter is provided by the substitution string):
- rewriteMap ldap attr2dn "ldap://host/dc=my,dc=org?dn?sub"
-
- # Then we need to detect emails; note that the rule
- # in case of match stops rewriting; in case of error,
- # it is ignored. In case we are mapping virtual
- # to real naming contexts, we also need to rewrite
- # regular DNs, because the definition of a bindDn
- # rewrite context overrides the default definition.
- rewriteContext bindDn
- rewriteRule "(mail=[^,]+@[^,]+)" "\\{attr2dn(\\1)}" "@I"
-
- # This is a rather sophisticate example. It massages a
- # search filter in case who performs the search has
- # administrative privileges. First we need to keep
- # track of the bind dn of the incoming request:
- rewriteContext bindDn
- rewriteRule ".+" "\\{**&binddn(\\0)}" ":"
-
- # A search filter containing `uid=' is rewritten only
- # if an appropriate dn is bound.
- # To do this, in the first rule the bound dn is
- # dereferenced, while the filter is decomposed in a
- # prefix, the argument of the `uid=', and in a
- # suffix. A tag `<>' is appended to the DN. If the DN
- # refers to an entry in the `ou=admin' subtree, the
- # filter is rewritten OR-ing the `uid=<arg>' with
- # `cn=<arg>'; otherwise it is left as is. This could be
- # useful, for instance, to allow apache's auth_ldap-1.4
- # module to authenticate users with both `uid' and
- # `cn', but only if the request comes from a possible
- # `dn: cn=Web auth, ou=admin, dc=home, dc=net' user.
- rewriteContext searchFilter
- rewriteRule "(.*\\()uid=([a-z0-9_]+)(\\).*)"
- "\\{**binddn}<>\\{&prefix(\\1)}\\{&arg(\\2)}\\{&suffix(\\3)}"
- ":I"
- rewriteRule "[^,]+,[ ]?ou=admin,[ ]?dc=home,[ ]?dc=net"
- "\\{*prefix}|(uid=\\{*arg})(cn=\\{*arg})\\{*suffix}" "@I"
- rewriteRule ".*<>" "\\{*prefix}uid=\\{*arg}\\{*suffix}"
+# set to `off' to disable rewriting
+rewriteEngine on
+
+# the rules the "suffixmassage" directive implies
+rewriteEngine on
+# all dataflow from client to server referring to DNs
+rewriteContext default
+rewriteRule "(.*)<virtualnamingcontext>$" "%1<realnamingcontext>" ":"
+# empty filter rule
+rewriteContext searchFilter
+# all dataflow from server to client
+rewriteContext searchResult
+rewriteRule "(.*)<realnamingcontext>$" "%1<virtualnamingcontext>" ":"
+rewriteContext searchAttrDN alias searchResult
+rewriteContext matchedDN alias searchResult
+
+# Everything defined here goes into the `default' context.
+# This rule changes the naming context of anything sent
+# to `dc=home,dc=net' to `dc=OpenLDAP, dc=org'
+
+rewriteRule "(.*)dc=home,[ ]?dc=net"
+ "%1dc=OpenLDAP, dc=org" ":"
+
+# since a pretty/normalized DN does not include spaces
+# after rdn separators, e.g. `,', this rule suffices:
+
+rewriteRule "(.*)dc=home,dc=net"
+ "%1dc=OpenLDAP,dc=org" ":"
+
+# Start a new context (ends input of the previous one).
+# This rule adds blanks between DN parts if not present.
+rewriteContext addBlanks
+rewriteRule "(.*),([^ ].*)" "%1, %2"
+
+# This one eats blanks
+rewriteContext eatBlanks
+rewriteRule "(.*),[ ](.*)" "%1,%2"
+
+# Here control goes back to the default rewrite
+# context; rules are appended to the existing ones.
+# anything that gets here is piped into rule `addBlanks'
+rewriteContext default
+rewriteRule ".*" "%{>addBlanks(%0)}" ":"
+
+.\" # Anything with `uid=username' is looked up in
+.\" # /etc/passwd for gecos (I know it's nearly useless,
+.\" # but it is there just as a guideline to implementing
+.\" # custom maps).
+.\" # Note the `I' flag that leaves `uid=username' in place
+.\" # if `username' does not have a valid account, and the
+.\" # `:' that forces the rule to be processed exactly once.
+.\" rewriteContext uid2Gecos
+.\" rewriteRule "(.*)uid=([a-z0-9]+),(.+)"
+.\" "%1cn=%2{xpasswd},%3" "I:"
+.\"
+.\" # Finally, in a bind, if one uses a `uid=username' DN,
+.\" # it is rewritten in `cn=name surname' if possible.
+.\" rewriteContext bindDN
+.\" rewriteRule ".*" "%{>addBlanks(%{>uid2Gecos(%0)})}" ":"
+.\"
+# Rewrite the search base according to `default' rules.
+rewriteContext searchBase alias default
+
+# Search results with OpenLDAP DN are rewritten back with
+# `dc=home,dc=net' naming context, with spaces eaten.
+rewriteContext searchResult
+rewriteRule "(.*[^ ]?)[ ]?dc=OpenLDAP,[ ]?dc=org"
+ "%{>eatBlanks(%1)}dc=home,dc=net" ":"
+
+# Bind with email instead of full DN: we first need
+# an ldap map that turns attributes into a DN (the
+# argument used when invoking the map is appended to
+# the URI and acts as the filter portion)
+rewriteMap ldap attr2dn "ldap://host/dc=my,dc=org?dn?sub"
+
+# Then we need to detect DN made up of a single email,
+# e.g. `mail=someone@example.com'; note that the rule
+# in case of match stops rewriting; in case of error,
+# it is ignored. In case we are mapping virtual
+# to real naming contexts, we also need to rewrite
+# regular DNs, because the definition of a bindDn
+# rewrite context overrides the default definition.
+rewriteContext bindDN
+rewriteRule "^mail=[^,]+@[^,]+$" "%{attr2dn(%0)}" ":@I"
+
+# This is a rather sophisticated example. It massages a
+# search filter in case who performs the search has
+# administrative privileges. First we need to keep
+# track of the bind DN of the incoming request, which is
+# stored in a variable called `binddn' with session scope,
+# and left in place to allow regular binding:
+rewriteContext bindDN
+rewriteRule ".+" "%{&&binddn(%0)}%0" ":"
+
+# A search filter containing `uid=' is rewritten only
+# if an appropriate DN is bound.
+# To do this, in the first rule the bound DN is
+# dereferenced, while the filter is decomposed in a
+# prefix, in the value of the `uid=<arg>' AVA, and
+# in a suffix. A tag `<>' is appended to the DN.
+# If the DN refers to an entry in the `ou=admin' subtree,
+# the filter is rewritten OR-ing the `uid=<arg>' with
+# `cn=<arg>'; otherwise it is left as is. This could be
+# useful, for instance, to allow apache's auth_ldap-1.4
+# module to authenticate users with both `uid' and
+# `cn', but only if the request comes from a possible
+# `cn=Web auth,ou=admin,dc=home,dc=net' user.
+rewriteContext searchFilter
+rewriteRule "(.*\e\e()uid=([a-z0-9_]+)(\e\e).*)"
+ "%{**binddn}<>%{&prefix(%1)}%{&arg(%2)}%{&suffix(%3)}"
+ ":I"
+rewriteRule "[^,]+,ou=admin,dc=home,dc=net"
+ "%{*prefix}|(uid=%{*arg})(cn=%{*arg})%{*suffix}" ":@I"
+rewriteRule ".*<>" "%{*prefix}uid=%{*arg}%{*suffix}" ":"
+
+# This example shows how to strip unwanted DN-valued
+# attribute values from a search result; the first rule
+# matches DN values below "ou=People,dc=example,dc=com";
+# in case of match the rewriting exits successfully.
+# The second rule matches everything else and causes
+# the value to be rejected.
+rewriteContext searchResult
+rewriteRule ".*,ou=People,dc=example,dc=com" "%0" ":@"
+rewriteRule ".*" "" "#"
.fi
-.SH "LDAP Proxy resolution (a possible evolution of slapd-ldap(5):"
-In case the rewritten dn is an LDAP URL, the operation is initiated
-towards the host[:port] indicated in the url, if it does not refer
+.SH "LDAP Proxy resolution (a possible evolution of slapd\-ldap(5)):"
+In case the rewritten DN is an LDAP URI, the operation is initiated
+towards the host[:port] indicated in the uri, if it does not refer
to the local server.
E.g.:
.LP
.nf
- rewriteRule \'^cn=root,.*\' \'\\0\' \'G{3}\'
- rewriteRule \'^cn=[a-l].*\' \'ldap://ldap1.my.org/\\0\' \'@\'
- rewriteRule \'^cn=[m-z].*\' \'ldap://ldap2.my.org/\\0\' \'@\'
- rewriteRule \'.*\' \'ldap://ldap3.my.org/\\0\' \'@\'
+ rewriteRule '^cn=root,.*' '%0' 'G{3}'
+ rewriteRule '^cn=[a-l].*' 'ldap://ldap1.my.org/%0' ':@'
+ rewriteRule '^cn=[m-z].*' 'ldap://ldap2.my.org/%0' ':@'
+ rewriteRule '.*' 'ldap://ldap3.my.org/%0' ':@'
.fi
.LP
(Rule 1 is simply there to illustrate the `G{n}' action; it could have
been written:
.LP
.nf
- rewriteRule \'^cn=root,.*\' \'ldap://ldap3.my.org/\\0\' \'@\'
+ rewriteRule '^cn=root,.*' 'ldap://ldap3.my.org/%0' ':@'
.fi
.LP
with the advantage of saving one rewrite pass ...)
-.SH "SEE ALSO"
+
+.SH ACCESS CONTROL
+The
+.B meta
+backend does not honor all ACL semantics as described in
+.BR slapd.access (5).
+In general, access checking is delegated to the remote server(s).
+Only
+.B read (=r)
+access to the
+.B entry
+pseudo-attribute and to the other attribute values of the entries
+returned by the
+.B search
+operation is honored, which is performed by the frontend.
+
+.SH PROXY CACHE OVERLAY
+The proxy cache overlay
+allows caching of LDAP search requests (queries) in a local database.
+See
+.BR slapo-pcache (5)
+for details.
+.SH FILES
+.TP
+ETCDIR/slapd.conf
+default slapd configuration file
+.SH SEE ALSO
.BR slapd.conf (5),
+.BR slapd\-ldap (5),
+.BR slapo\-pcache (5),
.BR slapd (8),
-.BR regex (7).
+.BR regex (7),
+.BR re_format (7).
+.SH AUTHOR
+Pierangelo Masarati, based on back-ldap by Howard Chu
projects / openldap / blobdiff