ldapx - LDAP extended object interface

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# ldapx(n) 1.2 tcllib "LDAP extended object interface"

## Name

ldapx - LDAP extended object interface

## Synopsis

- package require Tcl 8.5
- package require ldapx ?1.2?

- e reset
- e dn ?newdn?
- e rdn
- e superior
- e print
- se isempty
- se get attr
- se get1 attr
- se set attr values
- se set1 attr value
- se add attr values
- se add1 attr value
- se del attr ?values?
- se del1 attr value
- se getattr
- se getall
- se setall avpairs
- se backup ?other?
- se swap
- se restore ?other?
- se apply centry
- ce change ?new?
- ce diff new ?old?
- la error ?newmsg?
- la connect url ?binddn? ?bindpw? ?starttls?
- la disconnect
- la traverse base filter attrs entry body
- la search base filter attrs
- la read base filter entry ... entry
- la commit entry ... entry
- li channel chan
- li error ?newmsg?
- li read entry
- li write entry

## Description

The ldapx package provides an extended Tcl interface to LDAP directores and LDIF files. The ldapx package is built upon the ldap package in order to get low level LDAP access.

LDAP access is compatible with RFC 2251 (http://www.rfc-editor.org/rfc/rfc2251.txt). LDIF access is compatible with RFC 2849 (http://www.rfc-editor.org/rfc/rfc2849.txt).

## OVERVIEW

The ldapx package provides objects to interact with LDAP directories and LDIF files with an easy to use programming interface. It implements three snit::type classes.

The first class, entry, is used to store individual entries. Two different formats are available: the first one is the standard format, which represents an entry as read from the directory. The second format is the change format, which stores differences between two standard entries.

With these entries, an application which wants to modify an entry in a directory needs to read a (standard) entry from the directory, create a fresh copy into a new (standard) entry, modify the new copy, and then compute the differences between the two entries into a new (change) entry, which may be commited to the directory.

Such kinds of modifications are so heavily used that standard entries may contain their own copy of the original data. With such a copy, the application described above reads a (standard) entry from the directory, backs-up the original data, modifies the entry, and computes the differences between the entry and its backup. These differences are then commited to the directory.

Methods are provided to compute differences between two entries, to apply differences to an entry in order to get a new entry, and to get or set attributes in standard entries.

The second class is the ldap class. It provides a method to connect and bind to the directory with a uniform access to LDAP and LDAPS through an URL (ldap:// or ldaps://). The traverse control structure executes a body for each entry found in the directory. The commit method applies some changes (represented as entry objects) to the directory. Since some attributes are represented as UTF-8 strings, the option -utf8 controls which attributes must be converted and which attributes must not be converted.

The last class is the ldif class. It provides a method to associate a standard Tcl channel to an LDIF object. Then, methods read and write read or write entries from or to this channel. This class can make use of standard or change entries, according to the type of the LDIF file which may contain either standard entries or change entries (but not both at the same time). The option -utf8 works exactly as with the ldap class.

## ENTRY CLASS

### Entry Instance Data

An instance of the entry class keeps the following data:

dn

  This is the DN of the entry, which includes (in LDAP terminology) the RDN (relative DN) and the Superior parts.

format

  The format may be uninitialized (entry not yet used), standard or change. Most methods check the format of the entry, which can be reset with the reset method.

attrvals

  In a standard entry, this is where the attributes and associated values are stored. Many methods provide access to these informations. Attribute names are always converted into lower case.

backup

  In a standard entry, the backup may contain a copy of the dn and all attributes and values. Methods backup and restore manipulate these data, and method diff may use this backup.

change

  In a change entry, these data represent the modifications. Such modifications are handled by specialized methods such as apply or commit. Detailed format should not be used directly by programs.

  Internally, modifications are represented as a list of elements, each element has one of the following formats (which match the corresponding LDAP operations):

  1. {add {attr1 {val1...valn} attr2 {...} ...}}

     Addition of a new entry.

  2. {mod {modop {attr1 ?val1...valn?} attr2 ...} {modop ...} ...}

     Modification of one or more attributes and/or values, where <modop> can be modadd, moddel or modrepl (see the LDAP modify operation).

  3. {del}

     Deletion of an old entry.

  4. {modrdn newrdn deleteoldrdn ?newsuperior?}

     Renaming of an entry.

### Entry Options

No option is defined by this class.

### Methods for all kinds of entries

e reset

  This method resets the entry to an uninitialized state.

e dn ?newdn?

  This method returns the current DN of the entry. If the optional newdn is specified, it replaces the current DN of the entry.

e rdn

  This method returns the RDN part of the DN of the entry.

e superior

  This method returns the superior part of the DN of the entry.

e print

  This method returns the entry as a string ready to be printed.

### Methods for standard entries only

In all methods, attribute names are converted in lower case.

se isempty

  This method returns 1 if the entry is empty (i.e. without any attribute).

se get attr

  This method returns all values of the attribute attr, or the empty list if the attribute is not fond.

se get1 attr

  This method returns the first value of the attribute.

se set attr values

  This method sets the values (list values) of the attribute attr. If the list is empty, this method deletes all

se set1 attr value

  This method sets the values of the attribute attr to be an unique value value. Previous values, if any, are replaced by the new value.

se add attr values

  This method adds all elements the list values to the values of the attribute attr.

se add1 attr value

  This method adds a single value given by the parameter value to the attribute attr.

se del attr ?values?

  If the optional list values is specified, this method deletes all specified values from the attribute attr. If the argument values is not specified, this method deletes all values.

se del1 attr value

  This method deletes a unique value from the attribute attr.

se getattr

  This method returns all attributes names.

se getall

  This method returns all attributes and values from the entry, packed in a list of pairs <attribute, list of values>.

se setall avpairs

  This method sets at once all attributes and values. The format of the avpairs argument is the same as the one returned by method getall.

se backup ?other?

  This method stores in an other standard entry object a copy of the current DN and attributes/values. If the optional other argument is not specified, copy is done in the current entry (in a specific place, see section OVERVIEW).

se swap

  This method swaps the current and backup contexts of the entry.

se restore ?other?

  If the optional argument other is given, which must then be a standard entry, this method restores the current entry into the other entry. If the argument other argument is not specified, this methods restores the current entry from its internal backup (see section OVERVIEW).

se apply centry

  This method applies changes defined in the centry argument, which must be a change entry.

### Methods for change entries only

ce change ?new?

  If the optional argument new is specified, this method modifies the change list (see subsection Entry Instance Data for the exact format). In both cases, current change list is returned. Warning: values returned by this method should only be used by specialized methods such as apply or commit.

ce diff new ?old?

  This method computes the differences between the new and old entries under the form of a change list, and stores this list into the current change entry. If the optional argument old is not specified, difference is computed from the entry and its internal backup (see section OVERVIEW). Return value is the computed change list.

### Entry Example

        package require ldapx
        #
        # Create an entry and fill it as a standard entry with
        # attributes and values
        #
        ::ldapx::entry create e
        e dn "uid=joe,ou=people,o=mycomp"
        e set1 "uid"             "joe"
        e set  "objectClass"     {person anotherObjectClass}
        e set1 "givenName"       "Joe"
        e set1 "sn"              "User"
        e set  "telephoneNumber" {+31415926535 +2182818}
        e set1 "anotherAttr"     "This is a beautiful day, isn't it?"
        puts stdout "e\n[e print]"
        #
        # Create a second entry as a backup of the first, and
        # make some changes on it.
        # Entry is named automatically by snit.
        #
        set b [::ldapx::entry create %AUTO%]
        e backup $b
        puts stdout "$b\n[$b print]"
        $b del  "anotherAttr"
        $b del1 "objectClass" "anotherObjectClass"
        #
        # Create a change entry, a compute differences between first
        # and second entry.
        #
        ::ldapx::entry create c
        c diff e $b
        puts stdout "$c\n[$c print]"
        #
        # Apply changes to first entry. It should be the same as the
        # second entry, now.
        #
        e apply c
        ::ldapx::entry create nc
        nc diff e $b
        puts stdout "nc\n[nc print]"
        #
        # Clean-up
        #
        e destroy
        $b destroy
        c destroy
        nc destroy

## LDAP CLASS

### Ldap Instance Data

An instance of the ldap class keeps the following data:

channel

  This is the channel used by the ldap package for communication with the LDAP server.

lastError

  This variable contains the error message which appeared in the last method of the ldap class (this string is modified in nearly all methods). The error method may be used to fetch this message.

### Ldap Options

Options are configured on ldap instances using the configure method.

The first option is used for TLS parameters:

-tlsoptions list

  Specify the set of TLS options to use when connecting to the LDAP server (see the connect method). For the list of valid options, see the LDAP package documentation.

  The default is -request 1 -require 1 -ssl2 no -ssl3 no -tls1 yes -tls1.1 yes -tls1.2 yes.

  Example:

      $l configure -tlsoptions {-request yes -require yes}

A set of options of the ldap class is used during search operations (methods traverse, search and read, see below).

-scope base|one|sub

  Specify the scope of the LDAP search to be one of base, one or sub to specify a base object, one-level or subtree search.

  The default is sub.

-derefaliases never|seach|find|always

  Specify how aliases dereferencing is handled: never is used to specify that aliases are never derefenced, always that aliases are always derefenced, search that aliases are dereferenced when searching, or find that aliases are dereferenced only when locating the base object for the search.

  The default is never.

-sizelimit integer

  Specify the maximum number of entries to be retreived during a search. A value of 0 means no limit.

  Default is 0.

-timelimit integer

  Specify the time limit for a search to complete. A value of 0 means no limit.

  Default is 0.

-attrsonly 0|1

  Specify if only attribute names are to be retrieved (value 1). Normally (value 0), attribute values are also retrieved.

  Default is 0.

The last option is used when getting entries or committing changes in the directory:

-utf8 pattern-yes pattern-no

  Specify which attribute values are encoded in UTF-8. This information is specific to the LDAP schema in use by the application, since some attributes such as jpegPhoto, for example, are not encoded in UTF-8. This option takes the form of a list with two regular expressions suitable for the regexp command (anchored by ^ and $). The first specifies which attribute names are to be UTF-8 encoded, and the second selects, among those, the attribute names which will not be UTF-8 encoded. It is thus possible to say: convert all attributes, except jpegPhoto.

  Default is {{.*} {}}, meaning: all attributes are converted, without exception.

### Ldap Methods

la error ?newmsg?

  This method returns the error message that occurred in the last call to a ldap class method. If the optional argument newmsg is supplied, it becomes the last error message.

la connect url ?binddn? ?bindpw? ?starttls?

  This method connects to the LDAP server using given URL (which can be of the form ldap://host:port or ldaps://host:port). If an optional binddn argument is given together with the bindpw argument, the connect binds to the LDAP server using the specified DN and password.

  If the starttls argument is given a true value (1, yes, etc.) and the URL uses the ldap:// scheme, a TLS negotiation is initiated with the newly created connection, before LDAP binding. Default value: no.

  This method returns 1 if connection was successful, or 0 if an error occurred (use the error method to get the message).

la disconnect

  This method disconnects (and unbinds, if necessary) from the LDAP server.

la traverse base filter attrs entry body

  This method is a new control structure. It searches the LDAP directory from the specified base DN (given by the base argument) and selects entries based on the argument filter. For each entry found, this method fetches attributes specified by the attrs argument (or all attributes if it is an empty list), stores them in the entry instance of class entry and executes the script defined by the argument body. Options are used to refine the search.

  Caution: when this method is used, the script body cannot perform another LDAP search (methods traverse, search or read).

la search base filter attrs

  This method searches the directory using the same way as method traverse. All found entries are stored in newly created instances of class entry, which are returned in a list. The newly created instances should be destroyed when they are no longer used.

la read base filter entry ... entry

  This method reads one or more entries, using the same search criteria as methods traverse and search. All attributes are stored in the entries. This method provides a quick way to read some entries. It returns the number of entries found in the directory (which may be more than the number of read entries). If called without any entry argument, this method just returns the number of entries found, without returning any data.

la commit entry ... entry

  This method commits the changes stored in the entry arguments. Each entry may be either a change entry, or a standard entry with a backup.

  Note: in the future, this method should use the LDAP transaction extension provided by OpenLDAP 2.3 and later.

### Ldap Example

        package require ldapx
        #
        # Connects to the LDAP directory using StartTLS
        #
        ::ldapx::ldap create l
        l configure -tlsoptions {-cadir /etc/ssl/certs -request yes -require yes}
        set url "ldap://server.mycomp.com"
        if {! [l connect $url "cn=admin,o=mycomp" "mypasswd" yes]} then {
    	puts stderr "error: [l error]"
    	exit 1
        }
        #
        # Search all entries matching some criterion
        #
        l configure -scope one
        ::ldapx::entry create e
        set n 0
        l traverse "ou=people,o=mycomp" "(sn=Joe*)" {sn givenName} e {
    	puts "dn: [e dn]"
    	puts "  sn:        [e get1 sn]"
    	puts "  givenName: [e get1 givenName]"
    	incr n
        }
        puts "$n entries found"
        e destroy
        #
        # Add a telephone number to some entries
        # Note this modification cannot be done in the "traverse" operation.
        #
        set lent [l search "ou=people,o=mycomp" "(sn=Joe*)" {}]
        ::ldapx::entry create c
        foreach e $lent {
    	$e backup
    	$e add1 "telephoneNumber" "+31415926535"
    	c diff $e
    	if {! [l commit c]} then {
    	    puts stderr "error: [l error]"
    	    exit 1
    	}
    	$e destroy
        }
        c destroy

        l disconnect
        l destroy

## LDIF CLASS

### Ldif Instance Data

An instance of the ldif class keeps the following data:

channel

  This is the Tcl channel used to retrieve or store LDIF file contents. The association between an instance and a channel is made by the method channel. There is no need to disrupt this association when the LDIF file operation has ended.

format

  LDIF files may contain standard entries or change entries, but not both. This variable contains the detected format of the file (when reading) or the format of entries written to the file (when writing).

lastError

  This variable contains the error message which appeared in the last method of the ldif class (this string is modified in nearly all methods). The error method may be used to fetch this message.

version

  This is the version of the LDIF file. Only version 1 is supported: the method read can only read from version 1 files, and method write only creates version 1 files.

### Ldif Options

This class defines two options:

-ignore list-of-attributes

  This option is used to ignore certain attribute names on reading. For example, to read OpenLDAP replica files (replog), one must ignore replica and time attributes since they do not conform to the RFC 2849 standard for LDIF files.

  Default is empty list: no attribute is ignored.

-utf8 pattern-yes pattern-no

  Specify which attribute values are encoded in UTF-8. This information is specific to the LDAP schema in use by the application, since some attributes such as jpegPhoto, for example, are not encoded in UTF-8. This option takes the form of a list with two regular expressions suitable for the regexp command (anchored by ^ and $). The first specifies which attribute names are to be UTF-8 encoded, and the second selects, among those, the attribute names which will not be UTF-8 encoded. It is thus possible to say: convert all attributes, except jpegPhoto.

  Default is {{.*} {}}, meaning: all attributes are converted, without exception.

### Ldif Methods

li channel chan

  This method associates the Tcl channel named chan with the LDIF instance. It resets the type of LDIF object to uninitialized.

li error ?newmsg?

  This method returns the error message that occurred in the last call to a ldif class method. If the optional argument newmsg is supplied, it becomes the last error message.

li read entry

  This method reads the next entry from the LDIF file and stores it in the entry object of class entry. The entry may be a standard or change entry.

li write entry

  This method writes the entry given in the argument entry to the LDIF file.

### Ldif Example

        package require ldapx
        # This examples reads a LDIF file containing entries,
        # compare them to a LDAP directory, and writes on standard
        # output an LDIF file containing changes to apply to the
        # LDAP directory to match exactly the LDIF file.
        ::ldapx::ldif create liin
        liin channel stdin
        ::ldapx::ldif create liout
        liout channel stdout
        ::ldapx::ldap create la
        if {! [la connect "ldap://server.mycomp.com"]} then {
    	puts stderr "error: [la error]"
    	exit 1
        }
        la configure -scope one
        # Reads LDIF file
        ::ldapx::entry create e1
        ::ldapx::entry create e2
        ::ldapx::entry create c
        while {[liin read e1] != 0} {
    	set base [e1 superior]
    	set id [e1 rdn]
    	if {[la read $base "($id)" e2] == 0} then {
    	    e2 reset
    	}
    	c diff e1 e2
    	if {[llength [c change]] != 0} then {
    	    liout write c
    	}
        }
        la disconnect
        la destroy
        e1 destroy
        e2 destroy
        c destroy
        liout destroy
        liin destroy

## References

## Bugs, Ideas, Feedback

This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category ldap of the Tcllib Trackers. Please also report any ideas for enhancements you may have for either package and/or documentation.

When proposing code changes, please provide unified diffs, i.e the output of diff -u.

Note further that attachments are strongly preferred over inlined patches. Attachments can be made by going to the Edit form of the ticket immediately after its creation, and then using the left-most button in the secondary navigation bar.

## Keywords

directory access, internet, ldap, ldap client, ldif, protocol, rfc 2251, rfc 2849

## Category

Networking

## Copyright

Copyright © 2006-2018 Pierre David <pdav@users.sourceforge.net>