openldap/contrib/slapd-modules/comp_match

Copyright 2004 Sang Seok Lim, IBM . All rights reserved.

Redistribution and use in source and binary forms, with
or without modification, are permitted only as authorized
by the OpenLDAP Public License.

A copy of this license is available in the file LICENSE in
the top-level directory of the distribution or, alternatively,
at <http://www.OpenLDAP.org/license.html>.

This directory contains a Component Matching module and
a X.509 Certificate example.  In order to understand Component
Matching, see RFC 3687 and
http://www.openldap.org/conf/odd-sandiego-2004/Sangseok.pdf

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A) Brief introduction about files in this directory
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1) init.c
module_init() and functions which are dynamically linked
into the main slapd codes.

2) componentlib.c and componentlib.h
GSER and BER decoder library of each primitive ASN.1 type.
They use component representation to store ASN.1 values.

3) certificate.c/.h authorityKeyIdentifier.c/.h
eSNACC generated BER and GSER decoder routines of the X.509
certificate specification and one of its extensions,
authorityKeyIdentifier.

4) asn_to_syn_mr.c asn.h
An mapping table from ASN.1 types to corresponding Syntaxes,
matching rules, and component description in slapd.

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B) How to use Component Matching on X.509 certificates
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1) be sure to configure slapd with enable-modules on.
2) install the GSER-support eSNACC compiler. You can find
only in www.openldap.org. At least, you need the library
(libcasn1.a) and header files for compiling this module.
3) modify Makefile accordingly. then run make.
you will get compmatch.la and other necessary files in ./libs
4) modify slapd.conf to include the following module command
	moduleload <path to>compmatch.la
5) run slapd and perform search operations against
the attribute, userCertificate. You need to read through
RFC 3687 in order to understand how to compose component
filters.
Ex) component search filter examples
"(userCertificate:componentFilterMatch:=item:{ component
\"toBeSigned.serialNumber\", rule integerMatch, value 2 })"
You can find more examples in "test031-component-filter"
in the OpenLDAP source directory.

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C) How to add a new ASN.1 syntax
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1) download and install the eSNACC compiler supporting
Component Matching. You can find the compiler only in
www.openldap.org.  Before compiling, be sure to define
the "LDAP_COMPONENT" macro to obtain component
supported version of C library and back-ends of eSNACC.
Otherwise compiled library will fail to be linked to
the module.
2) using eSNACC, compile your ASN.1 specifications and
copy the generated .c and .h files to this directory
Ex)
$ esnacc -E BER_COMP -E GSER -t -d -f example.asn 
For Component Matching, set BOTH BER_COMP and GSER on.
After compiling, you will get example.c and example.h
3) modify example.c accordingly, seeing certificate.c
and certificate.asn as a reference.
- add init_module_xxx() located in generated .c file
into init_module() in init.c.
- modify the arguments of InstallOidDecoderMapping(...)
accordingly
- in the generated .c file, you need to write
"DecComponentxxxTop(...)" function for yourself.
You can copy BDecComponentCertificateTop in the 
generated .c file and modify it accordingly.
4) register a new attribute syntax with a new OID
in a schema file
5) then goto 3) of B) section.

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D) How to configure Component Indexing
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You can generate indices on each component of
a given attribute whose values are in either GSER or
BER. Currently primitive ASN.1 types, DN, and RDN
can be indexed for equality matching in BDB.
In order to generate indices, put following line
in the slapd configuration file, slapd.conf.

index [attribute name].[component reference] eq

Ex)
index userCertificate eq
index userCertificate.toBeSigned.issuer.rdnSequence eq
index userCertificate.toBeSigned.serialNumber eq
index userCertificate.toBeSigned.version eq

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D) How to configure Attribute Alias
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If your client is unable to use component filters,
attribute aliasing can be used instead. Attribute
Alias maps a virtual attribute type to an attribute
component and a component matching rule.
You can create your own aliases by following steps.

1) register aliasing attributes in the schema file.
Sample aliasing attributes are in test.schema.
2) compose component filters for aliasing attributes
and put them in "preprocessed_comp_filter" array
in "init.c".
3) add "add_aa_entry" function calls in
"init_attribute_aliasing_table()" in "init.c"
4) perform searching against the aliasing attribute
Ex)
"(x509CertificateIssuer:distinguishedNameMatch=
cn=ray,L=yorktown,o=ibm,c=us)"