title: openLDAP post-read control: value is absent
body: <p>I'm trying to implement LDAP post-read control in my LDAP client application, and currently I can't figure out exactly how packet with controls has to be coded, so that openLDAP can recognize it. Being more specific - I have problem with controlValue field of postRead control.  </p>
  
  <p>According to RFC4527 - "controlValue, an OCTET STRING, contains a BER-encoded AttributeSelection [RFC4511],".
  From RFC4511 -   </p>
  
  <pre><code>AttributeSelection ::= SEQUENCE OF selector LDAPString
                          -- The LDAPString is constrained to
                          -- &lt;attributeSelector&gt; in Section 4.5.1.8
  </code></pre>
  
  <p>So, this means (if I get it right) that controlValue is a "SEQUENCE OF LDAPStrings", and each LDAPStrings is a OCTET STRING containing name of some attribute. However, it seems that I've misunderstanded something, but can't figure out what.  </p>
  
  <p>Here is packet, that I send to openLDAP server:
     <img src="https://i.stack.imgur.com/Ngde8.png" alt="packet being sent">
  Here is DUMP of packet, that I send to openLDAP server:
  <img src="https://i.stack.imgur.com/F6r0a.png" alt="dump of packet being sent">
  Below is the answear of server:
  <img src="https://i.stack.imgur.com/L1Ies.png" alt="packet received"></p>
  
  <p>What is wrong?</p>