ldapx - LDAP extended object interface
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).
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.
An instance of the entry class keeps the following data:
This is the DN of the entry, which includes (in LDAP terminology) the RDN (relative DN) and the Superior parts.
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.
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.
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.
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):
{add {attr1 {val1...valn} attr2 {...} ...}}
Addition of a new entry.
{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).
{del}
Deletion of an old entry.
{modrdn newrdn deleteoldrdn ?newsuperior?}
Renaming of an entry.
No option is defined by this class.
This method resets the entry to an uninitialized state.
This method returns the current DN of the entry. If the optional newdn is specified, it replaces the current DN of the entry.
This method returns the RDN part of the DN of the entry.
This method returns the superior part of the DN of the entry.
This method returns the entry as a string ready to be printed.
In all methods, attribute names are converted in lower case.
This method returns 1 if the entry is empty (i.e. without any attribute).
This method returns all values of the attribute attr, or the empty list if the attribute is not fond.
This method returns the first value of the attribute.
This method sets the values (list values) of the attribute attr. If the list is empty, this method deletes all
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.
This method adds all elements the list values to the values of the attribute attr.
This method adds a single value given by the parameter value to the attribute attr.
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.
This method deletes a unique value from the attribute attr.
This method returns all attributes names.
This method returns all attributes and values from the entry, packed in a list of pairs <attribute, list of values>.
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.
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).
This method swaps the current and backup contexts of the entry.
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).
This method applies changes defined in the centry argument, which must be a change entry.
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.
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.
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
An instance of the ldap class keeps the following data:
This is the channel used by the ldap package for communication with the LDAP server.
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.
A first set of options of the ldap class is used during search operations (methods traverse, search and read, see below).
The last option is used when getting entries or committing changes in the directory:
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.
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.
This method disconnects (and unbinds, if necessary) from the LDAP server.
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).
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.
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.
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.
package require ldapx
#
# Connects to the LDAP directory
#
::ldapx::ldap create l
set url "ldap://server.mycomp.com"
if {! [l connect $url "cn=admin,o=mycomp" "mypasswd"]} then {
puts stderr "error: [l error]"
exit 1
}
#
# Search all entries matching some criterion
#
l configure -scope one
::ldapx::ldap create e
set n 0
l traverse "ou=people,o=mycomp" "(sn=Joe*)" {sn givenName} e {
puts "dn: [e dn]"
puts " sn: [e get1 sn]"
puts " givenName: [e get1 givenName]"
incr n
}
puts "$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::ldap 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
}
l disconnect
l destroy
An instance of the ldif class keeps the following data:
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.
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).
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.
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.
This class defines two options:
This method associates the Tcl channel named chan with the LDIF instance. It resets the type of LDIF object to uninitialized.
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.
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.
This method writes the entry given in the argument entry to the LDIF file.
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
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.
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Copyright © 2006 Pierre David <pdav@users.sourceforge.net>