# eldap

###
Module

eldap

###
Module Summary

LDAP Client

###
Since

Module eldap was introduced in OTP R15B01.

###
Description

This module provides a client api to the Lightweight Directory Access Protocol (LDAP).

References:

- RFC 4510 - RFC 4519

- RFC 2830

The above publications can be found at IETF.

###
DATA TYPES

Type definitions that are used more than once in this module:

handle()

  Connection handle

attribute() =

  {Type = string(), Values=[string()]}

modify_op()

  See mod_add/2, mod_delete/2, mod_replace/2

scope()

  See baseObject/0, singleLevel/0, wholeSubtree/0

dereference()

  See neverDerefAliases/0, derefInSearching/0, derefFindingBaseObj/0, derefAlways/0

filter()

  See present/1, substrings/2, equalityMatch/2, greaterOrEqual/2, lessOrEqual/2, approxMatch/2, extensibleMatch/2, 'and'/1, 'or'/1, 'not'/1

return_value() =

  ok | {ok, {referral,referrals()}} | {error,Error}

referrals() =

  [Address = string()] The contents of Address is server dependent.

###
Exports

####
open([Host]) -> {ok, Handle} | {error, Reason}
OTP R15B01

### Types

Handle = handle()

Setup a connection to an LDAP server, the HOST's are tried in order.

####
open([Host], [Option]) -> {ok, Handle} | {error, Reason}
OTP R15B01

### Types

Handle = handle()
Option = {port, integer()} | {log, function()} | {timeout, integer()} | {ssl, boolean()} | {sslopts, list()} | {tcpopts, list()}

Setup a connection to an LDAP server, the HOST's are tried in order.

The log function takes three arguments, fun(Level, FormatString, [FormatArg]) end.

Timeout set the maximum time in milliseconds that each server request may take.

All TCP socket options are accepted except active, binary, deliver, list, mode and packet

####
close(Handle) -> ok
OTP R15B01

### Types

Handle = handle()

Shutdown the connection after sending an unbindRequest to the server. If the connection is tls the connection will be closed with ssl:close/1, otherwise with gen_tcp:close/1.

####
start_tls(Handle, Options) -> return_value()
OTP R16B03

Same as start_tls(Handle, Options, infinity)

####
start_tls(Handle, Options, Timeout) -> return_value()
OTP R16B03

### Types

Handle = handle()
Options = ssl:ssl_options()
Timeout = infinity | positive_integer()

Upgrade the connection associated with Handle to a tls connection if possible.

The upgrade is done in two phases: first the server is asked for permission to upgrade. Second, if the request is acknowledged, the upgrade to tls is performed.

Error responses from phase one will not affect the current encryption state of the connection. Those responses are:

tls_already_started
  The connection is already encrypted. The connection is not affected.
{response,ResponseFromServer}
  The upgrade was refused by the LDAP server. The ResponseFromServer is an atom delivered byt the LDAP server explained in section 2.3 of rfc 2830. The connection is not affected, so it is still un-encrypted.

Errors in the second phase will however end the connection:

Error
  Any error responded from ssl:connect/3

The Timeout parameter is for the actual tls upgrade (phase 2) while the timeout in eldap:open/2 is used for the initial negotiation about upgrade (phase 1).

####
simple_bind(Handle, Dn, Password) -> return_value()
OTP R15B01

### Types

Handle = handle()
Dn = string()
Password = string()

Authenticate the connection using simple authentication.

####
add(Handle, Dn, [Attribute]) -> return_value()
OTP R15B01

### Types

Handle = handle()
Dn = string()
Attribute = attribute()

Add an entry. The entry must not exist.

      add(Handle,
          "cn=Bill Valentine, ou=people, o=Example Org, dc=example, dc=com",
           [{"objectclass", ["person"]},
            {"cn", ["Bill Valentine"]},
            {"sn", ["Valentine"]},
            {"telephoneNumber", ["545 555 00"]}]
         )

####
delete(Handle, Dn) -> return_value()
OTP R15B01

### Types

Dn = string()

Delete an entry.

      delete(Handle, "cn=Bill Valentine, ou=people, o=Example Org, dc=example, dc=com")

####
mod_add(Type, [Value]) -> modify_op()
OTP R15B01

### Types

Type = string()
Value = string()

Create an add modification operation.

####
mod_delete(Type, [Value]) -> modify_op()
OTP R15B01

### Types

Type = string()
Value = string()

Create a delete modification operation.

####
mod_replace(Type, [Value]) -> modify_op()
OTP R15B01

### Types

Type = string()
Value = string()

Create a replace modification operation.

####
modify(Handle, Dn, [ModifyOp]) -> return_value()
OTP R15B01

### Types

Dn = string()
ModifyOp = modify_op()

Modify an entry.

      modify(Handle, "cn=Bill Valentine, ou=people, o=Example Org, dc=example, dc=com",
             [eldap:mod_replace("telephoneNumber", ["555 555 00"]),
    	  eldap:mod_add("description", ["LDAP Hacker"]) ])

####
modify_password(Handle, Dn, NewPasswd) -> return_value() | {ok, GenPasswd}
OTP 18.0

### Types

Dn = string()
NewPasswd = string()

Modify the password of a user. See modify_password/4.

####
modify_password(Handle, Dn, NewPasswd, OldPasswd) -> return_value() | {ok, GenPasswd}
OTP 18.0

### Types

Dn = string()
NewPasswd = string()
OldPasswd = string()
GenPasswd = string()

Modify the password of a user.

- Dn. The user to modify. Should be "" if the modify request is for the user of the LDAP session.

- NewPasswd. The new password to set. Should be "" if the server is to generate the password. In this case, the result will be {ok, GenPasswd}.

- OldPasswd. Sometimes required by server policy for a user to change their password. If not required, use modify_password/3.

####
modify_dn(Handle, Dn, NewRDN, DeleteOldRDN, NewSupDN) -> return_value()
OTP R15B01

### Types

Dn = string()
NewRDN = string()
DeleteOldRDN = boolean()
NewSupDN = string()

Modify the DN of an entry. DeleteOldRDN indicates whether the current RDN should be removed from the attribute list after the operation. NewSupDN is the new parent that the RDN shall be moved to. If the old parent should remain as parent, NewSupDN shall be "".

      modify_dn(Handle, "cn=Bill Valentine, ou=people, o=Example Org, dc=example, dc=com ",
                "cn=Bill Jr Valentine", true, "")

####
search(Handle, SearchOptions) -> {ok, #eldap_search_result{}} | {ok, {referral,referrals()}} | {error, Reason}
OTP R15B01

### Types

SearchOptions = #eldap_search{} | [SearchOption]
SearchOption = {base, string()} | {filter, filter()} | {scope, scope()} | {attributes, [string()]} | {deref, dereference()} | | {types_only, boolean()} | {timeout, integer()}

Search the directory with the supplied the SearchOptions. The base and filter options must be supplied. Default values: scope is wholeSubtree(), deref is derefAlways(), types_only is false and timeout is 0 (meaning infinity).

      Filter = eldap:substrings("cn", [{any,"V"}]),
      search(Handle, [{base, "dc=example, dc=com"}, {filter, Filter}, {attributes, ["cn"]}]),

The timeout option in the SearchOptions is for the ldap server, while the timeout in eldap:open/2 is used for each individual request in the search operation.

####
baseObject() -> scope()
OTP R15B01

Search baseobject only.

####
singleLevel() -> scope()
OTP R15B01

Search the specified level only, i.e. do not recurse.

####
wholeSubtree() -> scope()
OTP R15B01

Search the entire subtree.

####
neverDerefAliases() -> dereference()
OTP R15B01

Never dereference aliases, treat aliases as entries.

####
derefAlways() -> dereference()
OTP R15B01

Always dereference aliases.

####
derefInSearching() -> dereference()
OTP R15B01

Dereference aliases only when searching.

####
derefFindingBaseObj() -> dereference()
OTP R15B01

Dereference aliases only in finding the base.

####
present(Type) -> filter()
OTP R15B01

### Types

Type = string()

Create a filter which filters on attribute type presence.

####
substrings(Type, [SubString]) -> filter()
OTP R15B01

### Types

Type = string()
SubString = {StringPart, string()}
StringPart = initial | any | final

Create a filter which filters on substrings.

####
equalityMatch(Type, Value) -> filter()
OTP R15B01

### Types

Type = string()
Value = string()

Create a equality filter.

####
greaterOrEqual(Type, Value) -> filter()
OTP R15B01

### Types

Type = string()
Value = string()

Create a greater or equal filter.

####
lessOrEqual(Type, Value) -> filter()
OTP R15B01

### Types

Type = string()
Value = string()

Create a less or equal filter.

####
approxMatch(Type, Value) -> filter()
OTP R15B01

### Types

Type = string()
Value = string()

Create a approximation match filter.

####
extensibleMatch(MatchValue, OptionalAttrs) -> filter()
OTP 17.4

### Types

MatchValue = string()
OptionalAttrs = [Attr]
Attr = {matchingRule,string()} | {type,string()} | {dnAttributes,boolean()}

Creates an extensible match filter. For example,

      eldap:extensibleMatch("Bar", [{type,"sn"}, {matchingRule,"caseExactMatch"}]))

creates a filter which performs a caseExactMatch on the attribute sn and matches with the value "Bar". The default value of dnAttributes is false.

####
'and'([Filter]) -> filter()
OTP R15B01

### Types

Filter = filter()

Creates a filter where all Filter must be true.

####
'or'([Filter]) -> filter()
OTP R15B01

### Types

Filter = filter()

Create a filter where at least one of the Filter must be true.

####
'not'(Filter) -> filter()
OTP R15B01

### Types

Filter = filter()

Negate a filter.

####
paged_result_control(PageSize) -> {control, "1.2.840.113556.1.4.319", true, binary()}
OTP 24.3

### Types

PageSize = positive_integer()

Paged results is an extension to the LDAP protocol specified by RFC2696

This function creates a control with the specified page size for use in search/3, for example:

    Control = eldap:paged_result_control(50),
    {ok, SearchResults} = search(Handle, [{base, "dc=example, dc=com"}], [Control]),

####
paged_result_control(PageSize, Cookie) -> {control, "1.2.840.113556.1.4.319", true, binary()}
OTP 24.3

### Types

PageSize = positive_integer()
Cookie = binary()

Paged results is an extension to the LDAP protocol specified by RFC2696

This function creates a control with the specified page size and cookie for use in search/3 to retrieve the next results page.

For example:

    PageSize = 50,
    Control1 = eldap:paged_result_control(PageSize),
    {ok, SearchResults1} = search(Handle, [{base, "dc=example, dc=com"}], [Control1]),
    %% retrieve the returned cookie from the search results
    {ok, Cookie1} = eldap:paged_result_cookie(SearchResults1),
    Control2 = eldap:paged_result_control(PageSize, Cookie1),
    {ok, SearchResults2} = eldap:search(Handle, [{base, "dc=example,dc=com"}], [Control2]),
    %% etc

####
paged_result_cookie(SearchResult) -> binary()
OTP 24.3

### Types

SearchResult = #eldap_search_result{}

Paged results is an extension to the LDAP protocol specified by RFC2696.

This function extracts the cookie returned from the server as a result of a paged search result.

If the returned cookie is the empty string "", then these search results represent the last in the series.

####
info(Handle) -> connection_info()
OTP 25.3.1

### Types

connection_info() = #{socket := Socket, socket_type := tcp | ssl}
Socket = ssl:sslsocket() | gen_tcp:socket()

Currently available information reveals the socket and the transport protocol, TCP or TLS (SSL), used by the LDAP connection.