Simplified LDAP/AD Server on C#

Question

I've searched without much success to the simplest (and yet working) example of an LDAP/AD Server for C#. Many libraries exist to connect to LDAP servers, but not the LDAP Server by itself (on C#).

I found however some information about it and even a post requesting a simple LDAP server that was answered "LDAP isn't simple"; and yet i read a lot of the RFC4511 and this sample code at GitHub Flexinet LDAP Server, but unfortunatly i don't have yet the knowledge to complete it's code.

My goal is not to make a fully functional LDAP server, but one that can at least do:

1. Serve as a login pool for softwares that allow it's users to be registered and log on a AD/LDAP server (just check for login and password for authentication).
2. Allow softwares like Outlook and Thunderbird to get a list of users (without passwords) with first and last name, e-mail address, phone number and department for contact list model.
3. No delete, add (or create), move, and other functions are required since the main software that i aim to integrate it with will do all the user and group management.

UPDATE

I'm trying to implement the Flexinet sample and adjust to that functionalities; as form of a question what should i do to change this function to prevent it from causing an exception (on the "var filter = searchRequest.ChildAttributes[6];" line it always breaks) when i call from a LDAP client software:

private void HandleSearchRequest(NetworkStream stream, LdapPacket requestPacket)
        {
            var searchRequest = requestPacket.ChildAttributes.SingleOrDefault(o => o.LdapOperation == LdapOperation.SearchRequest);
            var filter = searchRequest.ChildAttributes[6];

            if ((LdapFilterChoice)filter.ContextType == LdapFilterChoice.equalityMatch && filter.ChildAttributes[0].GetValue<String>() == "sAMAccountName" && filter.ChildAttributes[1].GetValue<String>() == "testuser") // equalityMatch
            {
                var responseEntryPacket = new LdapPacket(requestPacket.MessageId);
                var searchResultEntry = new LdapAttribute(LdapOperation.SearchResultEntry);
                searchResultEntry.ChildAttributes.Add(new LdapAttribute(UniversalDataType.OctetString, "cn=testuser,cn=Users,dc=dev,dc=company,dc=com"));
                searchResultEntry.ChildAttributes.Add(new LdapAttribute(UniversalDataType.Sequence));
                responseEntryPacket.ChildAttributes.Add(searchResultEntry);
                var responsEntryBytes = responseEntryPacket.GetBytes();
                stream.Write(responsEntryBytes, 0, responsEntryBytes.Length);
            }

            var responseDonePacket = new LdapPacket(requestPacket.MessageId);
            responseDonePacket.ChildAttributes.Add(new LdapResultAttribute(LdapOperation.SearchResultDone, LdapResult.success));
            var responseDoneBytes = responseDonePacket.GetBytes();
            stream.Write(responseDoneBytes, 0, responseDoneBytes.Length);
        }

The code is on the github link.

Answer 1

Finally i made a fork of the Flexinet LDAP Server on @Sammuel-Miranda/LdapServerLib and with the author's support and some changes and adaptations i completed this implementation. It responds to the bind and search calls and works perfectly for Outlook and Thunderbird to use as a shared address book.

I did not implemente however any ADD/MODIFY/DELETE request (but would not be hard to do) since i don't need then.