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RFC2251 - Lightweight Directory Access Protocol (v3)

王朝other·作者佚名  2008-05-31
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Network Working Group M. Wahl

Request for Comments: 2251 Critical Angle Inc.

Category: Standards Track T. Howes

Netscape Communications Corp.

S. Kille

Isode Limited

December 1997

Lightweight Directory Access Protocol (v3)

1. Status of this Memo

This document specifies an Internet standards track protocol for the

Internet community, and requests discussion and suggestions for

improvements. Please refer to the current edition of the "Internet

Official Protocol Standards" (STD 1) for the standardization state

and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1997). All Rights Reserved.

IESG Note

This document describes a directory access protocol that provides

both read and update access. Update access requires secure

authentication, but this document does not mandate implementation of

any satisfactory authentication mechanisms.

In accordance with RFC2026, section 4.4.1, this specification is

being approved by IESG as a Proposed Standard despite this

limitation, for the following reasons:

a. to encourage implementation and interoperability testing of

these protocols (with or without update access) before they

are deployed, and

b. to encourage deployment and use of these protocols in read-only

applications. (e.g. applications where LDAPv3 is used as

a query language for directories which are updated by some

secure mechanism other than LDAP), and

c. to avoid delaying the advancement and deployment of other Internet

standards-track protocols which require the ability to query, but

not update, LDAPv3 directory servers.

Readers are hereby warned that until mandatory authentication

mechanisms are standardized, clients and servers written according to

this specification which make use of update functionality are

UNLIKELY TO INTEROPERATE, or MAY INTEROPERATE ONLY IF AUTHENTICATION

IS REDUCED TO AN UNACCEPTABLY WEAK LEVEL.

Implementors are hereby discouraged from deploying LDAPv3 clients or

servers which implement the update functionality, until a Proposed

Standard for mandatory authentication in LDAPv3 has been approved and

published as an RFC.

Table of Contents

1. Status of this Memo .................................... 1

Copyright Notice ....................................... 1

IESG Note .............................................. 1

2. Abstract ............................................... 3

3. Models ................................................. 4

3.1. Protocol Model ........................................ 4

3.2. Data Model ............................................ 5

3.2.1. Attributes of Entries ............................... 5

3.2.2. Subschema Entries and Subentries .................... 7

3.3. Relationship to X.500 ................................. 8

3.4. Server-specific Data Requirements ..................... 8

4. Elements of Protocol ................................... 9

4.1. Common Elements ....................................... 9

4.1.1. Message Envelope .................................... 9

4.1.1.1. Message ID ........................................ 11

4.1.2. String Types ........................................ 11

4.1.3. Distinguished Name and Relative Distinguished Name .. 11

4.1.4. Attribute Type ...................................... 12

4.1.5. Attribute Description ............................... 13

4.1.5.1. Binary Option ..................................... 14

4.1.6. Attribute Value ..................................... 14

4.1.7. Attribute Value Assertion ........................... 15

4.1.8. Attribute ........................................... 15

4.1.9. Matching Rule Identifier ............................ 15

4.1.10. Result Message ..................................... 16

4.1.11. Referral ........................................... 18

4.1.12. Controls ........................................... 19

4.2. Bind Operation ........................................ 20

4.2.1. Sequencing of the Bind Request ...................... 21

4.2.2. Authentication and Other Security Services .......... 22

4.2.3. Bind Response ....................................... 23

4.3. Unbind Operation ...................................... 24

4.4. Unsolicited Notification .............................. 24

4.4.1. Notice of Disconnection ............................. 24

4.5. Search Operation ...................................... 25

4.5.1. Search Request ...................................... 25

4.5.2. Search Result ....................................... 29

4.5.3. Continuation References in the Search Result ........ 31

4.5.3.1. Example ........................................... 31

4.6. Modify Operation ...................................... 32

4.7. Add Operation ......................................... 34

4.8. Delete Operation ...................................... 35

4.9. Modify DN Operation ................................... 36

4.10. Compare Operation .................................... 37

4.11. Abandon Operation .................................... 38

4.12. Extended Operation ................................... 38

5. Protocol Element Encodings and Transfer ................ 39

5.1. Mapping Onto BER-based Transport Services ............. 39

5.2. Transfer Protocols .................................... 40

5.2.1. Transmission Control Protocol (TCP) ................. 40

6. Implementation Guidelines .............................. 40

6.1. Server Implementations ................................ 40

6.2. Client Implementations ................................ 40

7. Security Considerations ................................ 41

8. Acknowledgements ....................................... 41

9. Bibliography ........................................... 41

10. Authors' Addresses ..................................... 42

Appendix A - Complete ASN.1 Definition ..................... 44

Full Copyright Statement ................................... 50

2. Abstract

The protocol described in this document is designed to provide access

to directories supporting the X.500 models, while not incurring the

resource requirements of the X.500 Directory Access Protocol (DAP).

This protocol is specifically targeted at management applications and

browser applications that provide read/write interactive access to

directories. When used with a directory supporting the X.500

protocols, it is intended to be a complement to the X.500 DAP.

The key Words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",

"SHOULD", "SHOULD NOT", "RECOMMENDED", and "MAY" in this document

are to be interpreted as described in RFC2119 [10].

Key ASPects of this version of LDAP are:

- All protocol elements of LDAPv2 (RFC1777) are supported. The

protocol is carried directly over TCP or other transport, bypassing

much of the session/presentation overhead of X.500 DAP.

- Most protocol data elements can be encoded as ordinary strings

(e.g., Distinguished Names).

- Referrals to other servers may be returned.

- SASL mechanisms may be used with LDAP to provide association

security services.

- Attribute values and Distinguished Names have been

internationalized through the use of the ISO 10646 character set.

- The protocol can be extended to support new operations, and

controls may be used to extend existing operations.

- Schema is published in the directory for use by clients.

3. Models

Interest in X.500 [1] directory technologies in the Internet has led

to efforts to reduce the high cost of entry associated with use of

these technologies. This document continues the efforts to define

directory protocol alternatives, updating the LDAP [2] protocol

specification.

3.1. Protocol Model

The general model adopted by this protocol is one of clients

performing protocol operations against servers. In this model, a

client transmits a protocol request describing the operation to be

performed to a server. The server is then responsible for performing

the necessary operation(s) in the directory. Upon completion of the

operation(s), the server returns a response containing any results or

errors to the requesting client.

In keeping with the goal of easing the costs associated with use of

the directory, it is an objective of this protocol to minimize the

complexity of clients so as to facilitate widespread deployment of

applications capable of using the directory.

Note that although servers are required to return responses whenever

such responses are defined in the protocol, there is no requirement

for synchronous behavior on the part of either clients or servers.

Requests and responses for multiple operations may be exchanged

between a client and server in any order, provided the client

eventually receives a response for every request that requires one.

In LDAP versions 1 and 2, no provision was made for protocol servers

returning referrals to clients. However, for improved performance

and distribution this version of the protocol permits servers to

return to clients referrals to other servers. This allows servers to

offload the work of contacting other servers to progress operations.

Note that the core protocol operations defined in this document can

be mapped to a strict subset of the X.500(1997) directory abstract

service, so it can be cleanly provided by the DAP. However there is

not a one-to-one mapping between LDAP protocol operations and DAP

operations: server implementations acting as a gateway to X.500

directories may need to make multiple DAP requests.

3.2. Data Model

This section provides a brief introduction to the X.500 data model,

as used by LDAP.

The LDAP protocol assumes there are one or more servers which jointly

provide access to a Directory Information Tree (DIT). The tree is

made up of entries. Entries have names: one or more attribute values

from the entry form its relative distinguished name (RDN), which MUST

be unique among all its siblings. The concatenation of the relative

distinguished names of the sequence of entries from a particular

entry to an immediate subordinate of the root of the tree forms that

entry's Distinguished Name (DN), which is unique in the tree. An

example of a Distinguished Name is

CN=Steve Kille, O=Isode Limited, C=GB

Some servers may hold cache or shadow copies of entries, which can be

used to answer search and comparison queries, but will return

referrals or contact other servers if modification operations are

requested.

Servers which perform caching or shadowing MUST ensure that they do

not violate any access control constraints placed on the data by the

originating server.

The largest collection of entries, starting at an entry that is

mastered by a particular server, and including all its subordinates

and their subordinates, down to the entries which are mastered by

different servers, is termed a naming context. The root of the DIT

is a DSA-specific Entry (DSE) and not part of any naming context:

each server has different attribute values in the root DSE. (DSA is

an X.500 term for the directory server).

3.2.1. Attributes of Entries

Entries consist of a set of attributes. An attribute is a type with

one or more associated values. The attribute type is identified by a

short descriptive name and an OID (object identifier). The attribute

type governs whether there can be more than one value of an attribute

of that type in an entry, the syntax to which the values must

conform, the kinds of matching which can be performed on values of

that attribute, and other functions.

An example of an attribute is "mail". There may be one or more values

of this attribute, they must be IA5 (ASCII) strings, and they are

case insensitive (e.g. "foo@bar.com" will match "FOO@BAR.COM").

Schema is the collection of attribute type definitions, object class

definitions and other information which a server uses to determine

how to match a filter or attribute value assertion (in a compare

operation) against the attributes of an entry, and whether to permit

add and modify operations. The definition of schema for use with

LDAP is given in [5] and [6]. Additional schema elements may be

defined in other documents.

Each entry MUST have an objectClass attribute. The objectClass

attribute specifies the object classes of an entry, which along with

the system and user schema determine the permitted attributes of an

entry. Values of this attribute may be modified by clients, but the

objectClass attribute cannot be removed. Servers may restrict the

modifications of this attribute to prevent the basic structural class

of the entry from being changed (e.g. one cannot change a person into

a country). When creating an entry or adding an objectClass value to

an entry, all superclasses of the named classes are implicitly added

as well if not already present, and the client must supply values for

any mandatory attributes of new superclasses.

Some attributes, termed operational attributes, are used by servers

for administering the directory system itself. They are not returned

in search results unless eXPlicitly requested by name. Attributes

which are not operational, such as "mail", will have their schema and

syntax constraints enforced by servers, but servers will generally

not make use of their values.

Servers MUST NOT permit clients to add attributes to an entry unless

those attributes are permitted by the object class definitions, the

schema controlling that entry (specified in the subschema - see

below), or are operational attributes known to that server and used

for administrative purposes. Note that there is a particular

objectClass 'extensibleObject' defined in [5] which permits all user

attributes to be present in an entry.

Entries MAY contain, among others, the following operational

attributes, defined in [5]. These attributes are maintained

automatically by the server and are not modifiable by clients:

- creatorsName: the Distinguished Name of the user who added this

entry to the directory.

- createTimestamp: the time this entry was added to the directory.

- modifiersName: the Distinguished Name of the user who last modified

this entry.

- modifyTimestamp: the time this entry was last modified.

- subschemaSubentry: the Distinguished Name of the subschema entry

(or subentry) which controls the schema for this entry.

3.2.2. Subschema Entries and Subentries

Subschema entries are used for administering information about the

directory schema, in particular the object classes and attribute

types supported by directory servers. A single subschema entry

contains all schema definitions used by entries in a particular part

of the directory tree.

Servers which follow X.500(93) models SHOULD implement subschema

using the X.500 subschema mechanisms, and so these subschemas are not

ordinary entries. LDAP clients SHOULD NOT assume that servers

implement any of the other aspects of X.500 subschema. A server

which masters entries and permits clients to modify these entries

MUST implement and provide access to these subschema entries, so that

its clients may discover the attributes and object classes which are

permitted to be present. It is strongly recommended that all other

servers implement this as well.

The following four attributes MUST be present in all subschema

entries:

- cn: this attribute MUST be used to form the RDN of the subschema

entry.

- objectClass: the attribute MUST have at least the values "top" and

"subschema".

- objectClasses: each value of this attribute specifies an object

class known to the server.

- attributeTypes: each value of this attribute specifies an attribute

type known to the server.

These are defined in [5]. Other attributes MAY be present in

subschema entries, to reflect additional supported capabilities.

These include matchingRules, matchingRuleUse, dITStructureRules,

dITContentRules, nameForms and ldapSyntaxes.

Servers SHOULD provide the attributes createTimestamp and

modifyTimestamp in subschema entries, in order to allow clients to

maintain their caches of schema information.

Clients MUST only retrieve attributes from a subschema entry by

requesting a base object search of the entry, where the search filter

is "(objectClass=subschema)". (This will allow LDAPv3 servers which

gateway to X.500(93) to detect that subentry information is being

requested.)

3.3. Relationship to X.500

This document defines LDAP in terms of X.500 as an X.500 access

mechanism. An LDAP server MUST act in accordance with the

X.500(1993) series of ITU recommendations when providing the service.

However, it is not required that an LDAP server make use of any X.500

protocols in providing this service, e.g. LDAP can be mapped onto any

other directory system so long as the X.500 data and service model as

used in LDAP is not violated in the LDAP interface.

3.4. Server-specific Data Requirements

An LDAP server MUST provide information about itself and other

information that is specific to each server. This is represented as

a group of attributes located in the root DSE (DSA-Specific Entry),

which is named with the zero-length LDAPDN. These attributes are

retrievable if a client performs a base object search of the root

with filter "(objectClass=*)", however they are subject to access

control restrictions. The root DSE MUST NOT be included if the

client performs a suBTree search starting from the root.

Servers may allow clients to modify these attributes.

The following attributes of the root DSE are defined in section 5 of

[5]. Additional attributes may be defined in other documents.

- namingContexts: naming contexts held in the server. Naming contexts

are defined in section 17 of X.501 [6].

- subschemaSubentry: subschema entries (or subentries) known by this

server.

- altServer: alternative servers in case this one is later

unavailable.

- supportedExtension: list of supported extended operations.

- supportedControl: list of supported controls.

- supportedSASLMechanisms: list of supported SASL security features.

- supportedLDAPVersion: LDAP versions implemented by the server.

If the server does not master entries and does not know the locations

of schema information, the subschemaSubentry attribute is not present

in the root DSE. If the server masters directory entries under one

or more schema rules, there may be any number of values of the

subschemaSubentry attribute in the root DSE.

4. Elements of Protocol

The LDAP protocol is described using Abstract Syntax Notation 1

(ASN.1) [3], and is typically transferred using a subset of ASN.1

Basic Encoding Rules [11]. In order to support future extensions to

this protocol, clients and servers MUST ignore elements of SEQUENCE

encodings whose tags they do not recognize.

Note that unlike X.500, each change to the LDAP protocol other than

through the extension mechanisms will have a different version

number. A client will indicate the version it supports as part of

the bind request, described in section 4.2. If a client has not sent

a bind, the server MUST assume that version 3 is supported in the

client (since version 2 required that the client bind first).

Clients may determine the protocol version a server supports by

reading the supportedLDAPVersion attribute from the root DSE. Servers

which implement version 3 or later versions MUST provide this

attribute. Servers which only implement version 2 may not provide

this attribute.

4.1. Common Elements

This section describes the LDAPMessage envelope PDU (Protocol Data

Unit) format, as well as data type definitions which are used in the

protocol operations.

4.1.1. Message Envelope

For the purposes of protocol exchanges, all protocol operations are

encapsulated in a common envelope, the LDAPMessage, which is defined

as follows:

LDAPMessage ::= SEQUENCE {

messageID MessageID,

protocolOp CHOICE {

bindRequest BindRequest,

bindResponse BindResponse,

unbindRequest UnbindRequest,

searchRequest SearchRequest,

searchResEntry SearchResultEntry,

searchResDone SearchResultDone,

searchResRef SearchResultReference,

modifyRequest ModifyRequest,

modifyResponse ModifyResponse,

addRequest AddRequest,

addResponse AddResponse,

delRequest DelRequest,

delResponse DelResponse,

modDNRequest ModifyDNRequest,

modDNResponse ModifyDNResponse,

compareRequest CompareRequest,

compareResponse CompareResponse,

abandonRequest AbandonRequest,

extendedReq ExtendedRequest,

extendedResp ExtendedResponse },

controls [0] Controls OPTIONAL }

MessageID ::= INTEGER (0 .. maxInt)

maxInt INTEGER ::= 2147483647 -- (2^^31 - 1) --

The function of the LDAPMessage is to provide an envelope containing

common fields required in all protocol exchanges. At this time the

only common fields are the message ID and the controls.

If the server receives a PDU from the client in which the LDAPMessage

SEQUENCE tag cannot be recognized, the messageID cannot be parsed,

the tag of the protocolOp is not recognized as a request, or the

encoding structures or lengths of data fields are found to be

incorrect, then the server MUST return the notice of disconnection

described in section 4.4.1, with resultCode protocolError, and

immediately close the connection. In other cases that the server

cannot parse the request received by the client, the server MUST

return an appropriate response to the request, with the resultCode

set to protocolError.

If the client receives a PDU from the server which cannot be parsed,

the client may discard the PDU, or may abruptly close the connection.

The ASN.1 type Controls is defined in section 4.1.12.

4.1.1.1. Message ID

All LDAPMessage envelopes encapsulating responses contain the

messageID value of the corresponding request LDAPMessage.

The message ID of a request MUST have a value different from the

values of any other requests outstanding in the LDAP session of which

this message is a part.

A client MUST NOT send a second request with the same message ID as

an earlier request on the same connection if the client has not

received the final response from the earlier request. Otherwise the

behavior is undefined. Typical clients increment a counter for each

request.

A client MUST NOT reuse the message id of an abandonRequest or of the

abandoned operation until it has received a response from the server

for another request invoked subsequent to the abandonRequest, as the

abandonRequest itself does not have a response.

4.1.2. String Types

The LDAPString is a notational convenience to indicate that, although

strings of LDAPString type encode as OCTET STRING types, the ISO

10646 [13] character set (a superset of Unicode) is used, encoded

following the UTF-8 algorithm [14]. Note that in the UTF-8 algorithm

characters which are the same as ASCII (0x0000 through 0x007F) are

represented as that same ASCII character in a single byte. The other

byte values are used to form a variable-length encoding of an

arbitrary character.

LDAPString ::= OCTET STRING

The LDAPOID is a notational convenience to indicate that the

permitted value of this string is a (UTF-8 encoded) dotted-decimal

representation of an OBJECT IDENTIFIER.

LDAPOID ::= OCTET STRING

For example,

1.3.6.1.4.1.1466.1.2.3

4.1.3. Distinguished Name and Relative Distinguished Name

An LDAPDN and a RelativeLDAPDN are respectively defined to be the

representation of a Distinguished Name and a Relative Distinguished

Name after encoding according to the specification in [4], such that

<distinguished-name> ::= <name>

<relative-distinguished-name> ::= <name-component>

where <name> and <name-component> are as defined in [4].

LDAPDN ::= LDAPString

RelativeLDAPDN ::= LDAPString

Only Attribute Types can be present in a relative distinguished name

component; the options of Attribute Descriptions (next section) MUST

NOT be used in specifying distinguished names.

4.1.4. Attribute Type

An AttributeType takes on as its value the textual string associated

with that AttributeType in its specification.

AttributeType ::= LDAPString

Each attribute type has a unique OBJECT IDENTIFIER which has been

assigned to it. This identifier may be written as decimal digits

with components separated by periods, e.g. "2.5.4.10".

A specification may also assign one or more textual names for an

attribute type. These names MUST begin with a letter, and only

contain ASCII letters, digit characters and hyphens. They are case

insensitive. (These ASCII characters are identical to ISO 10646

characters whose UTF-8 encoding is a single byte between 0x00 and

0x7F.)

If the server has a textual name for an attribute type, it MUST use a

textual name for attributes returned in search results. The dotted-

decimal OBJECT IDENTIFIER is only used if there is no textual name

for an attribute type.

Attribute type textual names are non-unique, as two different

specifications (neither in standards track RFCs) may choose the same

name.

A server which masters or shadows entries SHOULD list all the

attribute types it supports in the subschema entries, using the

attributeTypes attribute. Servers which support an open-ended set of

attributes SHOULD include at least the attributeTypes value for the

'objectClass' attribute. Clients MAY retrieve the attributeTypes

value from subschema entries in order to obtain the OBJECT IDENTIFIER

and other information associated with attribute types.

Some attribute type names which are used in this version of LDAP are

described in [5]. Servers may implement additional attribute types.

4.1.5. Attribute Description

An AttributeDescription is a superset of the definition of the

AttributeType. It has the same ASN.1 definition, but allows

additional options to be specified. They are also case insensitive.

AttributeDescription ::= LDAPString

A value of AttributeDescription is based on the following BNF:

<AttributeDescription> ::= <AttributeType> [ ";" <options> ]

<options> ::= <option> <option> ";" <options>

<option> ::= <opt-char> <opt-char>*

<opt-char> ::= ASCII-equivalent letters, numbers and hyphen

Examples of valid AttributeDescription:

cn

userCertificate;binary

One option, "binary", is defined in this document. Additional

options may be defined in IETF standards-track and experimental RFCs.

Options beginning with "x-" are reserved for private experiments.

Any option could be associated with any AttributeType, although not

all combinations may be supported by a server.

An AttributeDescription with one or more options is treated as a

subtype of the attribute type without any options. Options present

in an AttributeDescription are never mutually exclusive.

Implementations MUST generate the <options> list sorted in ascending

order, and servers MUST treat any two AttributeDescription with the

same AttributeType and options as equivalent. A server will treat an

AttributeDescription with any options it does not implement as an

unrecognized attribute type.

The data type "AttributeDescriptionList" describes a list of 0 or

more attribute types. (A list of zero elements has special

significance in the Search request.)

AttributeDescriptionList ::= SEQUENCE OF

AttributeDescription

4.1.5.1. Binary Option

If the "binary" option is present in an AttributeDescription, it

overrides any string-based encoding representation defined for that

attribute in [5]. Instead the attribute is to be transferred as a

binary value encoded using the Basic Encoding Rules [11]. The syntax

of the binary value is an ASN.1 data type definition which is

referenced by the "SYNTAX" part of the attribute type definition.

The presence or absence of the "binary" option only affects the

transfer of attribute values in protocol; servers store any

particular attribute in a single format. If a client requests that a

server return an attribute in the binary format, but the server

cannot generate that format, the server MUST treat this attribute

type as an unrecognized attribute type. Similarly, clients MUST NOT

expect servers to return an attribute in binary format if the client

requested that attribute by name without the binary option.

This option is intended to be used with attributes whose syntax is a

complex ASN.1 data type, and the structure of values of that type is

needed by clients. Examples of this kind of syntax are "Certificate"

and "CertificateList".

4.1.6. Attribute Value

A field of type AttributeValue takes on as its value either a string

encoding of a AttributeValue data type, or an OCTET STRING containing

an encoded binary value, depending on whether the "binary" option is

present in the companion AttributeDescription to this AttributeValue.

The definition of string encodings for different syntaxes and types

may be found in other documents, and in particular [5].

AttributeValue ::= OCTET STRING

Note that there is no defined limit on the size of this encoding;

thus protocol values may include multi-megabyte attributes (e.g.

photographs).

Attributes may be defined which have arbitrary and non-printable

syntax. Implementations MUST NEITHER simply display nor attempt to

decode as ASN.1 a value if its syntax is not known. The

implementation may attempt to discover the subschema of the source

entry, and retrieve the values of attributeTypes from it.

Clients MUST NOT send attribute values in a request which are not

valid according to the syntax defined for the attributes.

4.1.7. Attribute Value Assertion

The AttributeValueAssertion type definition is similar to the one in

the X.500 directory standards. It contains an attribute description

and a matching rule assertion value suitable for that type.

AttributeValueAssertion ::= SEQUENCE {

attributeDesc AttributeDescription,

assertionValue AssertionValue }

AssertionValue ::= OCTET STRING

If the "binary" option is present in attributeDesc, this signals to

the server that the assertionValue is a binary encoding of the

assertion value.

For all the string-valued user attributes described in [5], the

assertion value syntax is the same as the value syntax. Clients may

use attribute values as assertion values in compare requests and

search filters.

Note however that the assertion syntax may be different from the

value syntax for other attributes or for non-equality matching rules.

These may have an assertion syntax which contains only part of the

value. See section 20.2.1.8 of X.501 [6] for examples.

4.1.8. Attribute

An attribute consists of a type and one or more values of that type.

(Though attributes MUST have at least one value when stored, due to

access control restrictions the set may be empty when transferred in

protocol. This is described in section 4.5.2, concerning the

PartialAttributeList type.)

Attribute ::= SEQUENCE {

type AttributeDescription,

vals SET OF AttributeValue }

Each attribute value is distinct in the set (no duplicates). The

order of attribute values within the vals set is undefined and

implementation-dependent, and MUST NOT be relied upon.

4.1.9. Matching Rule Identifier

A matching rule is a means of expressing how a server should compare

an AssertionValue received in a search filter with an abstract data

value. The matching rule defines the syntax of the assertion value

and the process to be performed in the server.

An X.501(1993) Matching Rule is identified in the LDAP protocol by

the printable representation of its OBJECT IDENTIFIER, either as one

of the strings given in [5], or as decimal digits with components

separated by periods, e.g. "caseIgnoreIA5Match" or

"1.3.6.1.4.1.453.33.33".

MatchingRuleId ::= LDAPString

Servers which support matching rules for use in the extensibleMatch

search filter MUST list the matching rules they implement in

subschema entries, using the matchingRules attributes. The server

SHOULD also list there, using the matchingRuleUse attribute, the

attribute types with which each matching rule can be used. More

information is given in section 4.4 of [5].

4.1.10. Result Message

The LDAPResult is the construct used in this protocol to return

success or failure indications from servers to clients. In response

to various requests servers will return responses containing fields

of type LDAPResult to indicate the final status of a protocol

operation request.

LDAPResult ::= SEQUENCE {

resultCode ENUMERATED {

success (0),

operationsError (1),

protocolError (2),

timeLimitExceeded (3),

sizeLimitExceeded (4),

compareFalse (5),

compareTrue (6),

authMethodNotSupported (7),

strongAuthRequired (8),

-- 9 reserved --

referral (10), -- new

adminLimitExceeded (11), -- new

unavailableCriticalExtension (12), -- new

confidentialityRequired (13), -- new

saslBindInProgress (14), -- new

noSuchAttribute (16),

undefinedAttributeType (17),

inappropriateMatching (18),

constraintViolation (19),

attributeOrValueExists (20),

invalidAttributeSyntax (21),

-- 22-31 unused --

noSuchObject (32),

aliasProblem (33),

invalidDNSyntax (34),

-- 35 reserved for undefined isLeaf --

aliasDereferencingProblem (36),

-- 37-47 unused --

inappropriateAuthentication (48),

invalidCredentials (49),

insufficientAccessRights (50),

busy (51),

unavailable (52),

unwillingToPerform (53),

loopDetect (54),

-- 55-63 unused --

namingViolation (64),

objectClassViolation (65),

notAllowedOnNonLeaf (66),

notAllowedOnRDN (67),

entryAlreadyExists (68),

objectClassModsProhibited (69),

-- 70 reserved for CLDAP --

affectsMultipleDSAs (71), -- new

-- 72-79 unused --

other (80) },

-- 81-90 reserved for APIs --

matchedDN LDAPDN,

errorMessage LDAPString,

referral [3] Referral OPTIONAL }

All the result codes with the exception of success, compareFalse and

compareTrue are to be treated as meaning the operation could not be

completed in its entirety.

Most of the result codes are based on problem indications from X.511

error data types. Result codes from 16 to 21 indicate an

AttributeProblem, codes 32, 33, 34 and 36 indicate a NameProblem,

codes 48, 49 and 50 indicate a SecurityProblem, codes 51 to 54

indicate a ServiceProblem, and codes 64 to 69 and 71 indicates an

UpdateProblem.

If a client receives a result code which is not listed above, it is

to be treated as an unknown error condition.

The errorMessage field of this construct may, at the server's option,

be used to return a string containing a textual, human-readable

(terminal control and page formatting characters should be avoided)

error diagnostic. As this error diagnostic is not standardized,

implementations MUST NOT rely on the values returned. If the server

chooses not to return a textual diagnostic, the errorMessage field of

the LDAPResult type MUST contain a zero length string.

For result codes of noSuchObject, aliasProblem, invalidDNSyntax and

aliasDereferencingProblem, the matchedDN field is set to the name of

the lowest entry (object or alias) in the directory that was matched.

If no aliases were dereferenced while attempting to locate the entry,

this will be a truncated form of the name provided, or if aliases

were dereferenced, of the resulting name, as defined in section 12.5

of X.511 [8]. The matchedDN field is to be set to a zero length

string with all other result codes.

4.1.11. Referral

The referral error indicates that the contacted server does not hold

the target entry of the request. The referral field is present in an

LDAPResult if the LDAPResult.resultCode field value is referral, and

absent with all other result codes. It contains a reference to

another server (or set of servers) which may be accessed via LDAP or

other protocols. Referrals can be returned in response to any

operation request (except unbind and abandon which do not have

responses). At least one URL MUST be present in the Referral.

The referral is not returned for a singleLevel or wholeSubtree search

in which the search scope spans multiple naming contexts, and several

different servers would need to be contacted to complete the

operation. Instead, continuation references, described in section

4.5.3, are returned.

Referral ::= SEQUENCE OF LDAPURL -- one or more

LDAPURL ::= LDAPString -- limited to characters permitted in URLs

If the client wishes to progress the operation, it MUST follow the

referral by contacting any one of servers. All the URLs MUST be

equally capable of being used to progress the operation. (The

mechanisms for how this is achieved by multiple servers are outside

the scope of this document.)

URLs for servers implementing the LDAP protocol are written according

to [9]. If an alias was dereferenced, the <dn> part of the URL MUST

be present, with the new target object name. If the <dn> part is

present, the client MUST use this name in its next request to

progress the operation, and if it is not present the client will use

the same name as in the original request. Some servers (e.g.

participating in distributed indexing) may provide a different filter

in a referral for a search operation. If the filter part of the URL

is present in an LDAPURL, the client MUST use this filter in its next

request to progress this search, and if it is not present the client

MUST use the same filter as it used for that search. Other aspects

of the new request may be the same or different as the request which

generated the referral.

Note that UTF-8 characters appearing in a DN or search filter may not

be legal for URLs (e.g. spaces) and MUST be escaped using the %

method in RFC1738 [7].

Other kinds of URLs may be returned, so long as the operation could

be performed using that protocol.

4.1.12. Controls

A control is a way to specify extension information. Controls which

are sent as part of a request apply only to that request and are not

saved.

Controls ::= SEQUENCE OF Control

Control ::= SEQUENCE {

controlType LDAPOID,

criticality BOOLEAN DEFAULT FALSE,

controlValue OCTET STRING OPTIONAL }

The controlType field MUST be a UTF-8 encoded dotted-decimal

representation of an OBJECT IDENTIFIER which uniquely identifies the

control. This prevents conflicts between control names.

The criticality field is either TRUE or FALSE.

If the server recognizes the control type and it is appropriate for

the operation, the server will make use of the control when

performing the operation.

If the server does not recognize the control type and the criticality

field is TRUE, the server MUST NOT perform the operation, and MUST

instead return the resultCode unsupportedCriticalExtension.

If the control is not appropriate for the operation and criticality

field is TRUE, the server MUST NOT perform the operation, and MUST

instead return the resultCode unsupportedCriticalExtension.

If the control is unrecognized or inappropriate but the criticality

field is FALSE, the server MUST ignore the control.

The controlValue contains any information associated with the

control, and its format is defined for the control. The server MUST

be prepared to handle arbitrary contents of the controlValue octet

string, including zero bytes. It is absent only if there is no value

information which is associated with a control of its type.

This document does not define any controls. Controls may be defined

in other documents. The definition of a control consists of:

- the OBJECT IDENTIFIER assigned to the control,

- whether the control is always noncritical, always critical, or

critical at the client's option,

- the format of the controlValue contents of the control.

Servers list the controls which they recognize in the

supportedControl attribute in the root DSE.

4.2. Bind Operation

The function of the Bind Operation is to allow authentication

information to be exchanged between the client and server.

The Bind Request is defined as follows:

BindRequest ::= [APPLICATION 0] SEQUENCE {

version INTEGER (1 .. 127),

name LDAPDN,

authentication AuthenticationChoice }

AuthenticationChoice ::= CHOICE {

simple [0] OCTET STRING,

-- 1 and 2 reserved

sasl [3] SaslCredentials }

SaslCredentials ::= SEQUENCE {

mechanism LDAPString,

credentials OCTET STRING OPTIONAL }

Parameters of the Bind Request are:

- version: A version number indicating the version of the protocol to

be used in this protocol session. This document describes version

3 of the LDAP protocol. Note that there is no version negotiation,

and the client just sets this parameter to the version it desires.

If the client requests protocol version 2, a server that supports

the version 2 protocol as described in [2] will not return any v3-

specific protocol fields. (Note that not all LDAP servers will

support protocol version 2, since they may be unable to generate

the attribute syntaxes associated with version 2.)

- name: The name of the directory object that the client wishes to

bind as. This field may take on a null value (a zero length

string) for the purposes of anonymous binds, when authentication

has been performed at a lower layer, or when using SASL credentials

with a mechanism that includes the LDAPDN in the credentials.

- authentication: information used to authenticate the name, if any,

provided in the Bind Request.

Upon receipt of a Bind Request, a protocol server will authenticate

the requesting client, if necessary. The server will then return a

Bind Response to the client indicating the status of the

authentication.

Authorization is the use of this authentication information when

performing operations. Authorization MAY be affected by factors

outside of the LDAP Bind request, such as lower layer security

services.

4.2.1. Sequencing of the Bind Request

For some SASL authentication mechanisms, it may be necessary for the

client to invoke the BindRequest multiple times. If at any stage the

client wishes to abort the bind process it MAY unbind and then drop

the underlying connection. Clients MUST NOT invoke operations

between two Bind requests made as part of a multi-stage bind.

A client may abort a SASL bind negotiation by sending a BindRequest

with a different value in the mechanism field of SaslCredentials, or

an AuthenticationChoice other than sasl.

If the client sends a BindRequest with the sasl mechanism field as an

empty string, the server MUST return a BindResponse with

authMethodNotSupported as the resultCode. This will allow clients to

abort a negotiation if it wishes to try again with the same SASL

mechanism.

Unlike LDAP v2, the client need not send a Bind Request in the first

PDU of the connection. The client may request any operations and the

server MUST treat these as unauthenticated. If the server requires

that the client bind before browsing or modifying the directory, the

server MAY reject a request other than binding, unbinding or an

extended request with the "operationsError" result.

If the client did not bind before sending a request and receives an

operationsError, it may then send a Bind Request. If this also fails

or the client chooses not to bind on the existing connection, it will

close the connection, reopen it and begin again by first sending a

PDU with a Bind Request. This will aid in interoperating with

servers implementing other versions of LDAP.

Clients MAY send multiple bind requests on a connection to change

their credentials. A subsequent bind process has the effect of

abandoning all operations outstanding on the connection. (This

simplifies server implementation.) Authentication from earlier binds

are subsequently ignored, and so if the bind fails, the connection

will be treated as anonymous. If a SASL transfer encryption or

integrity mechanism has been negotiated, and that mechanism does not

support the changing of credentials from one identity to another,

then the client MUST instead establish a new connection.

4.2.2. Authentication and Other Security Services

The simple authentication option provides minimal authentication

facilities, with the contents of the authentication field consisting

only of a cleartext password. Note that the use of cleartext

passwords is not recommended over open networks when there is no

authentication or encryption being performed by a lower layer; see

the "Security Considerations" section.

If no authentication is to be performed, then the simple

authentication option MUST be chosen, and the password be of zero

length. (This is often done by LDAPv2 clients.) Typically the DN is

also of zero length.

The sasl choice allows for any mechanism defined for use with SASL

[12]. The mechanism field contains the name of the mechanism. The

credentials field contains the arbitrary data used for

authentication, inside an OCTET STRING wrapper. Note that unlike

some Internet application protocols where SASL is used, LDAP is not

text-based, thus no base64 transformations are performed on the

credentials.

If any SASL-based integrity or confidentiality services are enabled,

they take effect following the transmission by the server and

reception by the client of the final BindResponse with resultCode

success.

The client can request that the server use authentication information

from a lower layer protocol by using the SASL EXTERNAL mechanism.

4.2.3. Bind Response

The Bind Response is defined as follows.

BindResponse ::= [APPLICATION 1] SEQUENCE {

COMPONENTS OF LDAPResult,

serverSaslCreds [7] OCTET STRING OPTIONAL }

BindResponse consists simply of an indication from the server of he

status of the client's request for authentication.

f the bind was successful, the resultCode will be success, therwise

it will be one of:

- operationsError: server encountered an internal error,

- protocolError: unrecognized version number or incorrect PDU

structure,

- authMethodNotSupported: unrecognized SASL mechanism name,

- strongAuthRequired: the server requires authentication be

performed with a SASL mechanism,

- referral: this server cannot accept this bind and the client

should try another,

- saslBindInProgress: the server requires the client to send a

new bind request, with the same sasl mechanism, to continue the

authentication process,

- inappropriateAuthentication: the server requires the client

which had attempted to bind anonymously or without supplying

credentials to provide some form of credentials,

- invalidCredentials: the wrong password was supplied or the SASL

credentials could not be processed,

- unavailable: the server is shutting down.

If the server does not support the client's requested protocol

version, it MUST set the resultCode to protocolError.

If the client receives a BindResponse response where the resultCode

was protocolError, it MUST close the connection as the server will be

unwilling to accept further operations. (This is for compatibility

with earlier versions of LDAP, in which the bind was always the first

operation, and there was no negotiation.)

The serverSaslCreds are used as part of a SASL-defined bind mechanism

to allow the client to authenticate the server to which it is

communicating, or to perform "challenge-response" authentication. If

the client bound with the password choice, or the SASL mechanism does

not require the server to return information to the client, then this

field is not to be included in the result.

4.3. Unbind Operation

The function of the Unbind Operation is to terminate a protocol

session. The Unbind Operation is defined as follows:

UnbindRequest ::= [APPLICATION 2] NULL

The Unbind Operation has no response defined. Upon transmission of an

UnbindRequest, a protocol client may assume that the protocol session

is terminated. Upon receipt of an UnbindRequest, a protocol server

may assume that the requesting client has terminated the session and

that all outstanding requests may be discarded, and may close the

connection.

4.4. Unsolicited Notification

An unsolicited notification is an LDAPMessage sent from the server to

the client which is not in response to any LDAPMessage received by

the server. It is used to signal an extraordinary condition in the

server or in the connection between the client and the server. The

notification is of an advisory nature, and the server will not expect

any response to be returned from the client.

The unsolicited notification is structured as an LDAPMessage in which

the messageID is 0 and protocolOp is of the extendedResp form. The

responseName field of the ExtendedResponse is present. The LDAPOID

value MUST be unique for this notification, and not be used in any

other situation.

One unsolicited notification is defined in this document.

4.4.1. Notice of Disconnection

This notification may be used by the server to advise the client that

the server is about to close the connection due to an error

condition. Note that this notification is NOT a response to an

unbind requested by the client: the server MUST follow the procedures

of section 4.3. This notification is intended to assist clients in

distinguishing between an error condition and a transient network

failure. As with a connection close due to network failure, the

client MUST NOT assume that any outstanding requests which modified

the directory have succeeded or failed.

The responseName is 1.3.6.1.4.1.1466.20036, the response field is

absent, and the resultCode is used to indicate the reason for the

disconnection.

The following resultCode values are to be used in this notification:

- protocolError: The server has received data from the client in

which

the LDAPMessage structure could not be parsed.

- strongAuthRequired: The server has detected that an established

underlying security association protecting communication between

the client and server has unexpectedly failed or been compromised.

- unavailable: This server will stop accepting new connections and

operations on all existing connections, and be unavailable for an

extended period of time. The client may make use of an alternative

server.

After sending this notice, the server MUST close the connection.

After receiving this notice, the client MUST NOT transmit any further

on the connection, and may abruptly close the connection.

4.5. Search Operation

The Search Operation allows a client to request that a search be

performed on its behalf by a server. This can be used to read

attributes from a single entry, from entries immediately below a

particular entry, or a whole subtree of entries.

4.5.1. Search Request

The Search Request is defined as follows:

SearchRequest ::= [APPLICATION 3] SEQUENCE {

baseObject LDAPDN,

scope ENUMERATED {

baseObject (0),

singleLevel (1),

wholeSubtree (2) },

derefAliases ENUMERATED {

neverDerefAliases (0),

derefInSearching (1),

derefFindingBaseObj (2),

derefAlways (3) },

sizeLimit INTEGER (0 .. maxInt),

timeLimit INTEGER (0 .. maxInt),

typesOnly BOOLEAN,

filter Filter,

attributes AttributeDescriptionList }

Filter ::= CHOICE {

and [0] SET OF Filter,

or [1] SET OF Filter,

not [2] Filter,

equalityMatch [3] AttributeValueAssertion,

substrings [4] SubstringFilter,

greaterOrEqual [5] AttributeValueAssertion,

lessOrEqual [6] AttributeValueAssertion,

present [7] AttributeDescription,

approxMatch [8] AttributeValueAssertion,

extensibleMatch [9] MatchingRuleAssertion }

SubstringFilter ::= SEQUENCE {

type AttributeDescription,

-- at least one must be present

substrings SEQUENCE OF CHOICE {

initial [0] LDAPString,

any [1] LDAPString,

final [2] LDAPString } }

MatchingRuleAssertion ::= SEQUENCE {

matchingRule [1] MatchingRuleId OPTIONAL,

type [2] AttributeDescription OPTIONAL,

matchValue [3] AssertionValue,

dnAttributes [4] BOOLEAN DEFAULT FALSE }

Parameters of the Search Request are:

- baseObject: An LDAPDN that is the base object entry relative to

which the search is to be performed.

- scope: An indicator of the scope of the search to be performed. The

semantics of the possible values of this field are identical to the

semantics of the scope field in the X.511 Search Operation.

- derefAliases: An indicator as to how alias objects (as defined in

X.501) are to be handled in searching. The semantics of the

possible values of this field are:

neverDerefAliases: do not dereference aliases in searching

or in locating the base object of the search;

derefInSearching: dereference aliases in subordinates of

the base object in searching, but not in locating the

base object of the search;

derefFindingBaseObj: dereference aliases in locating

the base object of the search, but not when searching

subordinates of the base object;

derefAlways: dereference aliases both in searching and in

locating the base object of the search.

- sizelimit: A sizelimit that restricts the maximum number of entries

to be returned as a result of the search. A value of 0 in this

field indicates that no client-requested sizelimit restrictions are

in effect for the search. Servers may enforce a maximum number of

entries to return.

- timelimit: A timelimit that restricts the maximum time (in seconds)

allowed for a search. A value of 0 in this field indicates that no

client-requested timelimit restrictions are in effect for the

search.

- typesOnly: An indicator as to whether search results will contain

both attribute types and values, or just attribute types. Setting

this field to TRUE causes only attribute types (no values) to be

returned. Setting this field to FALSE causes both attribute types

and values to be returned.

- filter: A filter that defines the conditions that must be fulfilled

in order for the search to match a given entry.

The 'and', 'or' and 'not' choices can be used to form combinations of

filters. At least one filter element MUST be present in an 'and' or

'or' choice. The others match against individual attribute values of

entries in the scope of the search. (Implementor's note: the 'not'

filter is an example of a tagged choice in an implicitly-tagged

module. In BER this is treated as if the tag was explicit.)

A server MUST evaluate filters according to the three-valued logic

of X.511(93) section 7.8.1. In summary, a filter is evaluated to

either "TRUE", "FALSE" or "Undefined". If the filter evaluates

to TRUE for a particular entry, then the attributes of that entry

are returned as part of the search result (subject to any applicable

access control restrictions). If the filter evaluates to FALSE or

Undefined, then the entry is ignored for the search.

A filter of the "and" choice is TRUE if all the filters in the SET

OF evaluate to TRUE, FALSE if at least one filter is FALSE, and

otherwise Undefined. A filter of the "or" choice is FALSE if all

of the filters in the SET OF evaluate to FALSE, TRUE if at least

one filter is TRUE, and Undefined otherwise. A filter of the "not"

choice is TRUE if the filter being negated is FALSE, FALSE if it is

TRUE, and Undefined if it is Undefined.

The present match evaluates to TRUE where there is an attribute or

subtype of the specified attribute description present in an entry,

and FALSE otherwise (including a presence test with an unrecognized

attribute description.)

The extensibleMatch is new in this version of LDAP. If the

matchingRule field is absent, the type field MUST be present, and

the equality match is performed for that type. If the type field is

absent and matchingRule is present, the matchValue is compared

against all attributes in an entry which support that matchingRule,

and the matchingRule determines the syntax for the assertion value

(the filter item evaluates to TRUE if it matches with at least

one attribute in the entry, FALSE if it does not match any attribute

in the entry, and Undefined if the matchingRule is not recognized

or the assertionValue cannot be parsed.) If the type field is

present and matchingRule is present, the matchingRule MUST be one

permitted for use with that type, otherwise the filter item is

undefined. If the dnAttributes field is set to TRUE, the match is

applied against all the attributes in an entry's distinguished name

as well, and also evaluates to TRUE if there is at least one

attribute in the distinguished name for which the filter item

evaluates to TRUE. (Editors note: The dnAttributes field is present

so that there does not need to be multiple versions of generic

matching rules such as for word matching, one to apply to entries

and another to apply to entries and dn attributes as well).

A filter item evaluates to Undefined when the server would not

be able to determine whether the assertion value matches an

entry. If an attribute description in an equalityMatch, substrings,

greaterOrEqual, lessOrEqual, approxMatch or extensibleMatch

filter is not recognized by the server, a matching rule id in the

extensibleMatch is not recognized by the server, the assertion

value cannot be parsed, or the type of filtering requested is not

implemented, then the filter is Undefined. Thus for example if a

server did not recognize the attribute type shoeSize, a filter of

(shoeSize=*) would evaluate to FALSE, and the filters (shoeSize=12),

(shoeSize>=12) and (shoeSize<=12) would evaluate to Undefined.

Servers MUST NOT return errors if attribute descriptions or matching

rule ids are not recognized, or assertion values cannot be parsed.

More details of filter processing are given in section 7.8 of X.511

[8].

- attributes: A list of the attributes to be returned from each entry

which matches the search filter. There are two special values which

may be used: an empty list with no attributes, and the attribute

description string "*". Both of these signify that all user

attributes are to be returned. (The "*" allows the client to

request all user attributes in addition to specific operational

attributes).

Attributes MUST be named at most once in the list, and are returned

at most once in an entry. If there are attribute descriptions in

the list which are not recognized, they are ignored by the server.

If the client does not want any attributes returned, it can specify

a list containing only the attribute with OID "1.1". This OID was

chosen arbitrarily and does not correspond to any attribute in use.

Client implementors should note that even if all user attributes are

requested, some attributes of the entry may not be included in

search results due to access control or other restrictions.

Furthermore, servers will not return operational attributes, such

as objectClasses or attributeTypes, unless they are listed by name,

since there may be extremely large number of values for certain

operational attributes. (A list of operational attributes for use

in LDAP is given in [5].)

Note that an X.500 "list"-like operation can be emulated by the client

requesting a one-level LDAP search operation with a filter checking

for the existence of the objectClass attribute, and that an X.500

"read"-like operation can be emulated by a base object LDAP search

operation with the same filter. A server which provides a gateway to

X.500 is not required to use the Read or List operations, although it

may choose to do so, and if it does must provide the same semantics

as the X.500 search operation.

4.5.2. Search Result

The results of the search attempted by the server upon receipt of a

Search Request are returned in Search Responses, which are LDAP

messages containing either SearchResultEntry, SearchResultReference,

ExtendedResponse or SearchResultDone data types.

SearchResultEntry ::= [APPLICATION 4] SEQUENCE {

objectName LDAPDN,

attributes PartialAttributeList }

PartialAttributeList ::= SEQUENCE OF SEQUENCE {

type AttributeDescription,

vals SET OF AttributeValue }

-- implementors should note that the PartialAttributeList may

-- have zero elements (if none of the attributes of that entry

-- were requested, or could be returned), and that the vals set

-- may also have zero elements (if types only was requested, or

-- all values were excluded from the result.)

SearchResultReference ::= [APPLICATION 19] SEQUENCE OF LDAPURL

-- at least one LDAPURL element must be present

SearchResultDone ::= [APPLICATION 5] LDAPResult

Upon receipt of a Search Request, a server will perform the necessary

search of the DIT.

If the LDAP session is operating over a connection-oriented transport

such as TCP, the server will return to the client a sequence of

responses in separate LDAP messages. There may be zero or more

responses containing SearchResultEntry, one for each entry found

during the search. There may also be zero or more responses

containing SearchResultReference, one for each area not explored by

this server during the search. The SearchResultEntry and

SearchResultReference PDUs may come in any order. Following all the

SearchResultReference responses and all SearchResultEntry responses

to be returned by the server, the server will return a response

containing the SearchResultDone, which contains an indication of

success, or detailing any errors that have occurred.

Each entry returned in a SearchResultEntry will contain all

attributes, complete with associated values if necessary, as

specified in the attributes field of the Search Request. Return of

attributes is subject to access control and other administrative

policy. Some attributes may be returned in binary format (indicated

by the AttributeDescription in the response having the binary option

present).

Some attributes may be constructed by the server and appear in a

SearchResultEntry attribute list, although they are not stored

attributes of an entry. Clients MUST NOT assume that all attributes

can be modified, even if permitted by access control.

LDAPMessage responses of the ExtendedResponse form are reserved for

returning information associated with a control requested by the

client. These may be defined in future versions of this document.

4.5.3. Continuation References in the Search Result

If the server was able to locate the entry referred to by the

baseObject but was unable to search all the entries in the scope at

and under the baseObject, the server may return one or more

SearchResultReference, each containing a reference to another set of

servers for continuing the operation. A server MUST NOT return any

SearchResultReference if it has not located the baseObject and

thus has not searched any entries; in this case it would return a

SearchResultDone containing a referral resultCode.

In the absence of indexing information provided to a server from

servers holding subordinate naming contexts, SearchResultReference

responses are not affected by search filters and are always returned

when in scope.

The SearchResultReference is of the same data type as the Referral.

URLs for servers implementing the LDAP protocol are written according

to [9]. The <dn> part MUST be present in the URL, with the new target

object name. The client MUST use this name in its next request.

Some servers (e.g. part of a distributed index exchange system) may

provide a different filter in the URLs of the SearchResultReference.

If the filter part of the URL is present in an LDAP URL, the client

MUST use the new filter in its next request to progress the search,

and if the filter part is absent the client will use again the same

filter. Other aspects of the new search request may be the same or

different as the search which generated the continuation references.

Other kinds of URLs may be returned so long as the operation could be

performed using that protocol.

The name of an unexplored subtree in a SearchResultReference need not

be subordinate to the base object.

In order to complete the search, the client MUST issue a new search

operation for each SearchResultReference that is returned. Note that

the abandon operation described in section 4.11 applies only to a

particular operation sent on a connection between a client and server,

and if the client has multiple outstanding search operations to

different servers, it MUST abandon each operation individually.

4.5.3.1. Example

For example, suppose the contacted server (hosta) holds the entry

"O=MNN,C=WW" and the entry "CN=Manager,O=MNN,C=WW". It knows that

either LDAP-capable servers (hostb) or (hostc) hold

"OU=People,O=MNN,C=WW" (one is the master and the other server a

shadow), and that LDAP-capable server (hostd) holds the subtree

"OU=Roles,O=MNN,C=WW". If a subtree search of "O=MNN,C=WW" is

requested to the contacted server, it may return the following:

SearchResultEntry for O=MNN,C=WW

SearchResultEntry for CN=Manager,O=MNN,C=WW

SearchResultReference {

ldap://hostb/OU=People,O=MNN,C=WW

ldap://hostc/OU=People,O=MNN,C=WW

}

SearchResultReference {

ldap://hostd/OU=Roles,O=MNN,C=WW

}

SearchResultDone (success)

Client implementors should note that when following a

SearchResultReference, additional SearchResultReference may be

generated. Continuing the example, if the client contacted the

server (hostb) and issued the search for the subtree

"OU=People,O=MNN,C=WW", the server might respond as follows:

SearchResultEntry for OU=People,O=MNN,C=WW

SearchResultReference {

ldap://hoste/OU=Managers,OU=People,O=MNN,C=WW

}

SearchResultReference {

ldap://hostf/OU=Consultants,OU=People,O=MNN,C=WW

}

SearchResultDone (success)

If the contacted server does not hold the base object for the search,

then it will return a referral to the client. For example, if the

client requests a subtree search of "O=XYZ,C=US" to hosta, the server

may return only a SearchResultDone containing a referral.

SearchResultDone (referral) {

ldap://hostg/

}

4.6. Modify Operation

The Modify Operation allows a client to request that a modification

of an entry be performed on its behalf by a server. The Modify

Request is defined as follows:

ModifyRequest ::= [APPLICATION 6] SEQUENCE {

object LDAPDN,

modification SEQUENCE OF SEQUENCE {

operation ENUMERATED {

add (0),

delete (1),

replace (2) },

modification AttributeTypeAndValues } }

AttributeTypeAndValues ::= SEQUENCE {

type AttributeDescription,

vals SET OF AttributeValue }

Parameters of the Modify Request are:

- object: The object to be modified. The value of this field contains

the DN of the entry to be modified. The server will not perform

any alias dereferencing in determining the object to be modified.

- modification: A list of modifications to be performed on the entry.

The entire list of entry modifications MUST be performed

in the order they are listed, as a single atomic operation. While

individual modifications may violate the directory schema, the

resulting entry after the entire list of modifications is performed

MUST conform to the requirements of the directory schema. The

values that may be taken on by the 'operation' field in each

modification construct have the following semantics respectively:

add: add values listed to the given attribute, creating

the attribute if necessary;

delete: delete values listed from the given attribute,

removing the entire attribute if no values are listed, or

if all current values of the attribute are listed for

deletion;

replace: replace all existing values of the given attribute

with the new values listed, creating the attribute if it

did not already exist. A replace with no value will delete

the entire attribute if it exists, and is ignored if the

attribute does not exist.

The result of the modify attempted by the server upon receipt of a

Modify Request is returned in a Modify Response, defined as follows:

ModifyResponse ::= [APPLICATION 7] LDAPResult

Upon receipt of a Modify Request, a server will perform the necessary

modifications to the DIT.

The server will return to the client a single Modify Response

indicating either the successful completion of the DIT modification,

or the reason that the modification failed. Note that due to the

requirement for atomicity in applying the list of modifications in

the Modify Request, the client may expect that no modifications of

the DIT have been performed if the Modify Response received indicates

any sort of error, and that all requested modifications have been

performed if the Modify Response indicates successful completion of

the Modify Operation. If the connection fails, whether the

modification occurred or not is indeterminate.

The Modify Operation cannot be used to remove from an entry any of

its distinguished values, those values which form the entry's

relative distinguished name. An attempt to do so will result in the

server returning the error notAllowedOnRDN. The Modify DN Operation

described in section 4.9 is used to rename an entry.

If an equality match filter has not been defined for an attribute type,

clients MUST NOT attempt to delete individual values of that attribute

from an entry using the "delete" form of a modification, and MUST

instead use the "replace" form.

Note that due to the simplifications made in LDAP, there is not a

direct mapping of the modifications in an LDAP ModifyRequest onto the

EntryModifications of a DAP ModifyEntry operation, and different

implementations of LDAP-DAP gateways may use different means of

representing the change. If successful, the final effect of the

operations on the entry MUST be identical.

4.7. Add Operation

The Add Operation allows a client to request the addition of an entry

into the directory. The Add Request is defined as follows:

AddRequest ::= [APPLICATION 8] SEQUENCE {

entry LDAPDN,

attributes AttributeList }

AttributeList ::= SEQUENCE OF SEQUENCE {

type AttributeDescription,

vals SET OF AttributeValue }

Parameters of the Add Request are:

- entry: the Distinguished Name of the entry to be added. Note that

the server will not dereference any aliases in locating the entry

to be added.

- attributes: the list of attributes that make up the content of the

entry being added. Clients MUST include distinguished values

(those forming the entry's own RDN) in this list, the objectClass

attribute, and values of any mandatory attributes of the listed

object classes. Clients MUST NOT supply the createTimestamp or

creatorsName attributes, since these will be generated

automatically by the server.

The entry named in the entry field of the AddRequest MUST NOT exist

for the AddRequest to succeed. The parent of the entry to be added

MUST exist. For example, if the client attempted to add

"CN=JS,O=Foo,C=US", the "O=Foo,C=US" entry did not exist, and the

"C=US" entry did exist, then the server would return the error

noSuchObject with the matchedDN field containing "C=US". If the

parent entry exists but is not in a naming context held by the

server, the server SHOULD return a referral to the server holding the

parent entry.

Servers implementations SHOULD NOT restrict where entries can be

located in the directory. Some servers MAY allow the administrator

to restrict the classes of entries which can be added to the

directory.

Upon receipt of an Add Request, a server will attempt to perform the

add requested. The result of the add attempt will be returned to the

client in the Add Response, defined as follows:

AddResponse ::= [APPLICATION 9] LDAPResult

A response of success indicates that the new entry is present in the

directory.

4.8. Delete Operation

The Delete Operation allows a client to request the removal of an

entry from the directory. The Delete Request is defined as follows:

DelRequest ::= [APPLICATION 10] LDAPDN

The Delete Request consists of the Distinguished Name of the entry to

be deleted. Note that the server will not dereference aliases while

resolving the name of the target entry to be removed, and that only

leaf entries (those with no subordinate entries) can be deleted with

this operation.

The result of the delete attempted by the server upon receipt of a

Delete Request is returned in the Delete Response, defined as

follows:

DelResponse ::= [APPLICATION 11] LDAPResult

Upon receipt of a Delete Request, a server will attempt to perform

the entry removal requested. The result of the delete attempt will be

returned to the client in the Delete Response.

4.9. Modify DN Operation

The Modify DN Operation allows a client to change the leftmost (least

significant) component of the name of an entry in the directory, or

to move a subtree of entries to a new location in the directory. The

Modify DN Request is defined as follows:

ModifyDNRequest ::= [APPLICATION 12] SEQUENCE {

entry LDAPDN,

newrdn RelativeLDAPDN,

deleteoldrdn BOOLEAN,

newSuperior [0] LDAPDN OPTIONAL }

Parameters of the Modify DN Request are:

- entry: the Distinguished Name of the entry to be changed. This

entry may or may not have subordinate entries.

- newrdn: the RDN that will form the leftmost component of the new

name of the entry.

- deleteoldrdn: a boolean parameter that controls whether the old RDN

attribute values are to be retained as attributes of the entry, or

deleted from the entry.

- newSuperior: if present, this is the Distinguished Name of the entry

which becomes the immediate superior of the existing entry.

The result of the name change attempted by the server upon receipt of

a Modify DN Request is returned in the Modify DN Response, defined

as follows:

ModifyDNResponse ::= [APPLICATION 13] LDAPResult

Upon receipt of a ModifyDNRequest, a server will attempt to

perform the name change. The result of the name change attempt will

be returned to the client in the Modify DN Response.

For example, if the entry named in the "entry" parameter was

"cn=John Smith,c=US", the newrdn parameter was "cn=John Cougar Smith",

and the newSuperior parameter was absent, then this operation would

attempt to rename the entry to be "cn=John Cougar Smith,c=US". If

there was already an entry with that name, the operation would fail

with error code entryAlreadyExists.

If the deleteoldrdn parameter is TRUE, the values forming the old

RDN are deleted from the entry. If the deleteoldrdn parameter is

FALSE, the values forming the old RDN will be retained as

non-distinguished attribute values of the entry. The server may

not perform the operation and return an error code if the setting of

the deleteoldrdn parameter would cause a schema inconsistency in the

entry.

Note that X.500 restricts the ModifyDN operation to only affect

entries that are contained within a single server. If the LDAP

server is mapped onto DAP, then this restriction will apply, and the

resultCode affectsMultipleDSAs will be returned if this error

occurred. In general clients MUST NOT expect to be able to perform

arbitrary movements of entries and subtrees between servers.

4.10. Compare Operation

The Compare Operation allows a client to compare an assertion

provided with an entry in the directory. The Compare Request is

defined as follows:

CompareRequest ::= [APPLICATION 14] SEQUENCE {

entry LDAPDN,

ava AttributeValueAssertion }

Parameters of the Compare Request are:

- entry: the name of the entry to be compared with.

- ava: the assertion with which an attribute in the entry is to be

compared.

The result of the compare attempted by the server upon receipt of a

Compare Request is returned in the Compare Response, defined as

follows:

CompareResponse ::= [APPLICATION 15] LDAPResult

Upon receipt of a Compare Request, a server will attempt to perform

the requested comparison. The result of the comparison will be

returned to the client in the Compare Response. Note that errors and

the result of comparison are all returned in the same construct.

Note that some directory systems may establish access controls which

permit the values of certain attributes (such as userPassword) to be

compared but not read. In a search result, it may be that an

attribute of that type would be returned, but with an empty set of

values.

4.11. Abandon Operation

The function of the Abandon Operation is to allow a client to request

that the server abandon an outstanding operation. The Abandon

Request is defined as follows:

AbandonRequest ::= [APPLICATION 16] MessageID

The MessageID MUST be that of a an operation which was requested

earlier in this connection.

(The abandon request itself has its own message id. This is distinct

from the id of the earlier operation being abandoned.)

There is no response defined in the Abandon Operation. Upon

transmission of an Abandon Operation, a client may expect that the

operation identified by the Message ID in the Abandon Request has

been abandoned. In the event that a server receives an Abandon

Request on a Search Operation in the midst of transmitting responses

to the search, that server MUST cease transmitting entry responses to

the abandoned request immediately, and MUST NOT send the

SearchResponseDone. Of course, the server MUST ensure that only

properly encoded LDAPMessage PDUs are transmitted.

Clients MUST NOT send abandon requests for the same operation

multiple times, and MUST also be prepared to receive results from

operations it has abandoned (since these may have been in transit

when the abandon was requested).

Servers MUST discard abandon requests for message IDs they do not

recognize, for operations which cannot be abandoned, and for

operations which have already been abandoned.

4.12. Extended Operation

An extension mechanism has been added in this version of LDAP, in

order to allow additional operations to be defined for services not

available elsewhere in this protocol, for instance digitally signed

operations and results.

The extended operation allows clients to make requests and receive

responses with predefined syntaxes and semantics. These may be

defined in RFCs or be private to particular implementations. Each

request MUST have a unique OBJECT IDENTIFIER assigned to it.

ExtendedRequest ::= [APPLICATION 23] SEQUENCE {

requestName [0] LDAPOID,

requestValue [1] OCTET STRING OPTIONAL }

The requestName is a dotted-decimal representation of the OBJECT

IDENTIFIER corresponding to the request. The requestValue is

information in a form defined by that request, encapsulated inside an

OCTET STRING.

The server will respond to this with an LDAPMessage containing the

ExtendedResponse.

ExtendedResponse ::= [APPLICATION 24] SEQUENCE {

COMPONENTS OF LDAPResult,

responseName [10] LDAPOID OPTIONAL,

response [11] OCTET STRING OPTIONAL }

If the server does not recognize the request name, it MUST return

only the response fields from LDAPResult, containing the

protocolError result code.

5. Protocol Element Encodings and Transfer

One underlying service is defined here. Clients and servers SHOULD

implement the mapping of LDAP over TCP described in 5.2.1.

5.1. Mapping Onto BER-based Transport Services

The protocol elements of LDAP are encoded for exchange using the

Basic Encoding Rules (BER) [11] of ASN.1 [3]. However, due to the

high overhead involved in using certain elements of the BER, the

following additional restrictions are placed on BER-encodings of LDAP

protocol elements:

(1) Only the definite form of length encoding will be used.

(2) OCTET STRING values will be encoded in the primitive form only.

(3) If the value of a BOOLEAN type is true, the encoding MUST have

its contents octets set to hex "FF".

(4) If a value of a type is its default value, it MUST be absent.

Only some BOOLEAN and INTEGER types have default values in this

protocol definition.

These restrictions do not apply to ASN.1 types encapsulated inside of

OCTET STRING values, such as attribute values, unless otherwise

noted.

5.2. Transfer Protocols

This protocol is designed to run over connection-oriented, reliable

transports, with all 8 bits in an octet being significant in the data

stream.

5.2.1. Transmission Control Protocol (TCP)

The LDAPMessage PDUs are mapped directly onto the TCP bytestream. It

is recommended that server implementations running over the TCP MAY

provide a protocol listener on the assigned port, 389. Servers may

instead provide a listener on a different port number. Clients MUST

support contacting servers on any valid TCP port.

6. Implementation Guidelines

This document describes an Internet protocol.

6.1. Server Implementations

The server MUST be capable of recognizing all the mandatory attribute

type names and implement the syntaxes specified in [5]. Servers MAY

also recognize additional attribute type names.

6.2. Client Implementations

Clients which request referrals MUST ensure that they do not loop

between servers. They MUST NOT repeatedly contact the same server for

the same request with the same target entry name, scope and filter.

Some clients may be using a counter that is incremented each time

referral handling occurs for an operation, and these kinds of clients

MUST be able to handle a DIT with at least ten layers of naming

contexts between the root and a leaf entry.

In the absence of prior agreements with servers, clients SHOULD NOT

assume that servers support any particular schemas beyond those

referenced in section 6.1. Different schemas can have different

attribute types with the same names. The client can retrieve the

subschema entries referenced by the subschemaSubentry attribute in

the server's root DSE or in entries held by the server.

7. Security Considerations

When used with a connection-oriented transport, this version of the

protocol provides facilities for the LDAP v2 authentication

mechanism, simple authentication using a cleartext password, as well

as any SASL mechanism [12]. SASL allows for integrity and privacy

services to be negotiated.

It is also permitted that the server can return its credentials to

the client, if it chooses to do so.

Use of cleartext password is strongly discouraged where the

underlying transport service cannot guarantee confidentiality and may

result in disclosure of the password to unauthorized parties.

When used with SASL, it should be noted that the name field of the

BindRequest is not protected against modification. Thus if the

distinguished name of the client (an LDAPDN) is agreed through the

negotiation of the credentials, it takes precedence over any value in

the unprotected name field.

Implementations which cache attributes and entries obtained via LDAP

MUST ensure that access controls are maintained if that information

is to be provided to multiple clients, since servers may have access

control policies which prevent the return of entries or attributes in

search results except to particular authenticated clients. For

example, caches could serve result information only to the client

whose request caused it to be cache.

8. Acknowledgements

This document is an update to RFC1777, by Wengyik Yeong, Tim Howes,

and Steve Kille. Design ideas included in this document are based on

those discussed in ASID and other IETF Working Groups. The

contributions of individuals in these working groups is gratefully

acknowledged.

9. Bibliography

[1] ITU-T Rec. X.500, "The Directory: Overview of Concepts, Models

and Service", 1993.

[2] Yeong, W., Howes, T., and S. Kille, "Lightweight Directory Access

Protocol", RFC1777, March 1995.

[3] ITU-T Rec. X.680, "Abstract Syntax Notation One (ASN.1) -

Specification of Basic Notation", 1994.

[4] Kille, S., Wahl, M., and T. Howes, "Lightweight Directory Access

Protocol (v3): UTF-8 String Representation of Distinguished

Names", RFC2253, December 1997.

[5] Wahl, M., Coulbeck, A., Howes, T., and S. Kille, "Lightweight

Directory Access Protocol (v3): Attribute Syntax Definitions",

RFC2252, December 1997.

[6] ITU-T Rec. X.501, "The Directory: Models", 1993.

[7] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform

Resource Locators (URL)", RFC1738, December 1994.

[8] ITU-T Rec. X.511, "The Directory: Abstract Service Definition",

1993.

[9] Howes, T., and M. Smith, "The LDAP URL Format", RFC2255,

December 1997.

[10] Bradner, S., "Key words for use in RFCs to Indicate Requirement

Levels", RFC2119, March 1997.

[11] ITU-T Rec. X.690, "Specification of ASN.1 encoding rules: Basic,

Canonical, and Distinguished Encoding Rules", 1994.

[12] Meyers, J., "Simple Authentication and Security Layer",

RFC2222, October 1997.

[13] Universal Multiple-Octet Coded Character Set (UCS) -

Architecture and Basic Multilingual Plane, ISO/IEC 10646-1 :

1993.

[14] Yergeau, F., "UTF-8, a transformation format of Unicode and ISO

10646", RFC2044, October 1996.

10. Authors' Addresses

Mark Wahl

Critical Angle Inc.

4815 W Braker Lane #502-385

Austin, TX 78759

USA

Phone: +1 512 372-3160

EMail: M.Wahl@critical-angle.com

Tim Howes

Netscape Communications Corp.

501 E. Middlefield Rd., MS MV068

Mountain View, CA 94043

USA

Phone: +1 650 937-3419

EMail: howes@netscape.com

Steve Kille

Isode Limited

The Dome, The Square

Richmond

TW9 1DT

UK

Phone: +44-181-332-9091

EMail: S.Kille@isode.com

Appendix A - Complete ASN.1 Definition

Lightweight-Directory-Access-Protocol-V3 DEFINITIONS

IMPLICIT TAGS ::=

BEGIN

LDAPMessage ::= SEQUENCE {

messageID MessageID,

protocolOp CHOICE {

bindRequest BindRequest,

bindResponse BindResponse,

unbindRequest UnbindRequest,

searchRequest SearchRequest,

searchResEntry SearchResultEntry,

searchResDone SearchResultDone,

searchResRef SearchResultReference,

modifyRequest ModifyRequest,

modifyResponse ModifyResponse,

addRequest AddRequest,

addResponse AddResponse,

delRequest DelRequest,

delResponse DelResponse,

modDNRequest ModifyDNRequest,

modDNResponse ModifyDNResponse,

compareRequest CompareRequest,

compareResponse CompareResponse,

abandonRequest AbandonRequest,

extendedReq ExtendedRequest,

extendedResp ExtendedResponse },

controls [0] Controls OPTIONAL }

MessageID ::= INTEGER (0 .. maxInt)

maxInt INTEGER ::= 2147483647 -- (2^^31 - 1) --

LDAPString ::= OCTET STRING

LDAPOID ::= OCTET STRING

LDAPDN ::= LDAPString

RelativeLDAPDN ::= LDAPString

AttributeType ::= LDAPString

AttributeDescription ::= LDAPString

AttributeDescriptionList ::= SEQUENCE OF

AttributeDescription

AttributeValue ::= OCTET STRING

AttributeValueAssertion ::= SEQUENCE {

attributeDesc AttributeDescription,

assertionValue AssertionValue }

AssertionValue ::= OCTET STRING

Attribute ::= SEQUENCE {

type AttributeDescription,

vals SET OF AttributeValue }

MatchingRuleId ::= LDAPString

LDAPResult ::= SEQUENCE {

resultCode ENUMERATED {

success (0),

operationsError (1),

protocolError (2),

timeLimitExceeded (3),

sizeLimitExceeded (4),

compareFalse (5),

compareTrue (6),

authMethodNotSupported (7),

strongAuthRequired (8),

-- 9 reserved --

referral (10), -- new

adminLimitExceeded (11), -- new

unavailableCriticalExtension (12), -- new

confidentialityRequired (13), -- new

saslBindInProgress (14), -- new

noSuchAttribute (16),

undefinedAttributeType (17),

inappropriateMatching (18),

constraintViolation (19),

attributeOrValueExists (20),

invalidAttributeSyntax (21),

-- 22-31 unused --

noSuchObject (32),

aliasProblem (33),

invalidDNSyntax (34),

-- 35 reserved for undefined isLeaf --

aliasDereferencingProblem (36),

-- 37-47 unused --

inappropriateAuthentication (48),

invalidCredentials (49),

insufficientAccessRights (50),

busy (51),

unavailable (52),

unwillingToPerform (53),

loopDetect (54),

-- 55-63 unused --

namingViolation (64),

objectClassViolation (65),

notAllowedOnNonLeaf (66),

notAllowedOnRDN (67),

entryAlreadyExists (68),

objectClassModsProhibited (69),

-- 70 reserved for CLDAP --

affectsMultipleDSAs (71), -- new

-- 72-79 unused --

other (80) },

-- 81-90 reserved for APIs --

matchedDN LDAPDN,

errorMessage LDAPString,

referral [3] Referral OPTIONAL }

Referral ::= SEQUENCE OF LDAPURL

LDAPURL ::= LDAPString -- limited to characters permitted in URLs

Controls ::= SEQUENCE OF Control

Control ::= SEQUENCE {

controlType LDAPOID,

criticality BOOLEAN DEFAULT FALSE,

controlValue OCTET STRING OPTIONAL }

BindRequest ::= [APPLICATION 0] SEQUENCE {

version INTEGER (1 .. 127),

name LDAPDN,

authentication AuthenticationChoice }

AuthenticationChoice ::= CHOICE {

simple [0] OCTET STRING,

-- 1 and 2 reserved

sasl [3] SaslCredentials }

SaslCredentials ::= SEQUENCE {

mechanism LDAPString,

credentials OCTET STRING OPTIONAL }

BindResponse ::= [APPLICATION 1] SEQUENCE {

COMPONENTS OF LDAPResult,

serverSaslCreds [7] OCTET STRING OPTIONAL }

UnbindRequest ::= [APPLICATION 2] NULL

SearchRequest ::= [APPLICATION 3] SEQUENCE {

baseObject LDAPDN,

scope ENUMERATED {

baseObject (0),

singleLevel (1),

wholeSubtree (2) },

derefAliases ENUMERATED {

neverDerefAliases (0),

derefInSearching (1),

derefFindingBaseObj (2),

derefAlways (3) },

sizeLimit INTEGER (0 .. maxInt),

timeLimit INTEGER (0 .. maxInt),

typesOnly BOOLEAN,

filter Filter,

attributes AttributeDescriptionList }

Filter ::= CHOICE {

and [0] SET OF Filter,

or [1] SET OF Filter,

not [2] Filter,

equalityMatch [3] AttributeValueAssertion,

substrings [4] SubstringFilter,

greaterOrEqual [5] AttributeValueAssertion,

lessOrEqual [6] AttributeValueAssertion,

present [7] AttributeDescription,

approxMatch [8] AttributeValueAssertion,

extensibleMatch [9] MatchingRuleAssertion }

SubstringFilter ::= SEQUENCE {

type AttributeDescription,

-- at least one must be present

substrings SEQUENCE OF CHOICE {

initial [0] LDAPString,

any [1] LDAPString,

final [2] LDAPString } }

MatchingRuleAssertion ::= SEQUENCE {

matchingRule [1] MatchingRuleId OPTIONAL,

type [2] AttributeDescription OPTIONAL,

matchValue [3] AssertionValue,

dnAttributes [4] BOOLEAN DEFAULT FALSE }

SearchResultEntry ::= [APPLICATION 4] SEQUENCE {

objectName LDAPDN,

attributes PartialAttributeList }

PartialAttributeList ::= SEQUENCE OF SEQUENCE {

type AttributeDescription,

vals SET OF AttributeValue }

SearchResultReference ::= [APPLICATION 19] SEQUENCE OF LDAPURL

SearchResultDone ::= [APPLICATION 5] LDAPResult

ModifyRequest ::= [APPLICATION 6] SEQUENCE {

object LDAPDN,

modification SEQUENCE OF SEQUENCE {

operation ENUMERATED {

add (0),

delete (1),

replace (2) },

modification AttributeTypeAndValues } }

AttributeTypeAndValues ::= SEQUENCE {

type AttributeDescription,

vals SET OF AttributeValue }

ModifyResponse ::= [APPLICATION 7] LDAPResult

AddRequest ::= [APPLICATION 8] SEQUENCE {

entry LDAPDN,

attributes AttributeList }

AttributeList ::= SEQUENCE OF SEQUENCE {

type AttributeDescription,

vals SET OF AttributeValue }

AddResponse ::= [APPLICATION 9] LDAPResult

DelRequest ::= [APPLICATION 10] LDAPDN

DelResponse ::= [APPLICATION 11] LDAPResult

ModifyDNRequest ::= [APPLICATION 12] SEQUENCE {

entry LDAPDN,

newrdn RelativeLDAPDN,

deleteoldrdn BOOLEAN,

newSuperior [0] LDAPDN OPTIONAL }

ModifyDNResponse ::= [APPLICATION 13] LDAPResult

CompareRequest ::= [APPLICATION 14] SEQUENCE {

entry LDAPDN,

ava AttributeValueAssertion }

CompareResponse ::= [APPLICATION 15] LDAPResult

AbandonRequest ::= [APPLICATION 16] MessageID

ExtendedRequest ::= [APPLICATION 23] SEQUENCE {

requestName [0] LDAPOID,

requestValue [1] OCTET STRING OPTIONAL }

ExtendedResponse ::= [APPLICATION 24] SEQUENCE {

COMPONENTS OF LDAPResult,

responseName [10] LDAPOID OPTIONAL,

response [11] OCTET STRING OPTIONAL }

END

Full Copyright Statement

Copyright (C) The Internet Society (1997). All Rights Reserved.

This document and translations of it may be copied and furnished to

others, and derivative works that comment on or otherwise explain it

or assist in its implementation may be prepared, copied, published

and distributed, in whole or in part, without restriction of any

kind, provided that the above copyright notice and this paragraph are

included on all such copies and derivative works. However, this

document itself may not be modified in any way, such as by removing

the copyright notice or references to the Internet Society or other

Internet organizations, except as needed for the purpose of

developing Internet standards in which case the procedures for

copyrights defined in the Internet Standards process must be

followed, or as required to translate it into languages other than

English.

The limited permissions granted above are perpetual and will not be

revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an

"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING

TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING

BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION

HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF

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