Get all groups for a user using LDAP

Question

I've tried to load all groups for a user from LDAP.

Currently I'm testing on our local AD. With the following code I can load all groups of the given user:

public IEnumerable<String> GetUserGroups( String userName )
{ 
    using ( var domainContext = new PrincipalContext( ContextType.Domain, Name ) )
    {
        var user = UserPrincipal.FindByIdentity( domainContext, userName );
        return user.GetAuthorizationGroups().Select( x => x.Name} ).ToList();
    }
}

But I fail to get the same result using LDAP.

Code using LDAP:

public IEnumerable<String> GetUserGroups1(String userName)
{
    //returns the container name of the given user
    var containerName = GetUserContainerName(userName); 
    var groups = new List<String>();
    if (containerName == null)
        return groups;

    var entry = new DirectoryEntry(String.Format("LDAP://{0}", "DC=example,DC=com"));

    var searcher = new DirectorySearcher(entry)
    {
        Filter = String.Format("(member:{0}:=CN={1},{2},{3})",
                               "1.2.840.113556.1.4.1941",
                               containerName, "CN=Users", "DC=example,DC=com"),
        SearchScope = SearchScope.Subtree
    };

    var result = searcher.FindAll();
    for (var i = 0; i < result.Count; i++)
    {
        var path = result[i].Path;
        var startIndex = path.IndexOf("CN=", StringComparison.Ordinal) + 3;
        groups.Add(path.Substring(startIndex, path.IndexOf(",", startIndex + 1,
                   StringComparison.Ordinal) - startIndex));
     }
     return groups;
}

How can I get all groups for a user using LDAP?

Answer 1

I’ve ended up with this code. It returns the name of each group containing a given user.

private IEnumerable<String> GetGroupsOfUser( String userName )
{
    var groupNames = new List<String>();

    // Open a LDAP connection
    using ( var ldapConnection = OpenLdapConnection() )
    {
        // Configuration (should work for an AD with default settings):
        // MemberOfAttributeKey => "memberOf"
        // UserFilterDn => "DC=domain1,DC=domain2,DC=domain3"
        // UserFilter => "(&(objectCategory=person)(sAMAccountName={0}))"
        // ProtocolVersion => 3


        // Search for the user data in the directory
        var ldapFilter = SecurityConfiguration.LdapConfiguration.UserFilter.F( userName );
        String[] attributesToReturn = { SecurityConfiguration.LdapConfiguration.MemberOfAttributeKey };
        var searchRequest = new SearchRequest( SecurityConfiguration.LdapConfiguration.UserFilterDn,
                                                ldapFilter,
                                                SearchScope.Subtree,
                                                attributesToReturn );

        // Check if the response is valid
        var searchResponse = ldapConnection.SendRequest( searchRequest ) as SearchResponse;
        if ( searchResponse?.Entries?.Count != 1 )
            throw new DirectoryException( "Invalid search response received from the directory." );

        var entry = searchResponse.Entries[0];
        if ( !entry.Attributes.Contains( SecurityConfiguration.LdapConfiguration.MemberOfAttributeKey ) )
            Logger.Warn( "Entry does not contain a member of attribute." );
        else
            for ( var index = 0; index < entry.Attributes[SecurityConfiguration.LdapConfiguration.MemberOfAttributeKey]
                                                .Count; index++ )
            {
                // Extract the group name
                var groupName = entry.Attributes[SecurityConfiguration.LdapConfiguration.MemberOfAttributeKey][index]
                                        .ToString();
                var name = groupName.Substring( 3, Math.Min( groupName.IndexOf( ",", StringComparison.InvariantCultureIgnoreCase ) - 3, groupName.Length - 3 ) );
                groupNames.Add( name );
            }
    }

    return groupNames;
}

private LdapConnection OpenLdapConnection()
{
    // Use the server name and port to setup an LDAP Directory Service
    var directoryIdentifier = new LdapDirectoryIdentifier( SecurityConfiguration.LdapConfiguration.Server, SecurityConfiguration.LdapConfiguration.Port );
    var ldapConnection = new LdapConnection( directoryIdentifier );

    // Set the protocol version
    ldapConnection.SessionOptions.ProtocolVersion = SecurityConfiguration.LdapConfiguration.ProtocolVersion;

    // If user name parameter present set connection credentials
    if ( SecurityConfiguration.LdapConfiguration.UserName.IsNotEmpty() )
    {
        // Set connection credentials
        var networkCredential = new NetworkCredential( SecurityConfiguration.LdapConfiguration.UserName,
                                                        SecurityConfiguration.LdapConfiguration.Password );

        if ( SecurityConfiguration.LdapConfiguration.UserDomain.IsNotEmpty() )
            networkCredential.Domain = SecurityConfiguration.LdapConfiguration.UserDomain;
        ldapConnection.Credential = networkCredential;

        // Set connection authentication type
        ldapConnection.AuthType = SecurityConfiguration.LdapConfiguration.AuthType;
    }

    // Connection establishment
    ldapConnection.Bind();

    return ldapConnection;
}

Answer 2

My first advice is you should split your method in sort of having a better overview:

1. Get your user.

You could use something like that:

/// <summary>
/// Return the user by the user name
/// </summary>
/// <param name="userName_">Username to base search on</param>
/// <returns>
/// User Manager or null if not found
/// </returns>
public static DirectoryEntry SearchForUser(string userName_)
{
    DirectoryEntry de = null;
    DirectorySearcher directorySearcher = null;
    Domain domain = null;
    try
    {
        if (String.IsNullOrEmpty(userName_))
            return null;

        string userName = userName_.StartsWith("CN=") ? userName_.Replace("CN=", String.Empty) : userName_;

        de = new DirectoryEntry("LDAP://" + Domain.GetCurrentDomain().Name);
        directorySearcher = new DirectorySearcher(de);
        directorySearcher.Filter = string.Format("(&(objectClass=person)(objectCategory=user)(sAMAccountname={0}))", userName);
        SearchResult searchResult = directorySearcher.FindOne();

        return searchResult != null ? searchResult_.GetDirectoryEntry() : null;
    }
    finally
    {
        if (de != null)
            de.Dispose();
        if (directorySearcher != null)
            directorySearcher.Dispose();
        if (domain != null)
            domain.Dispose();
    }
}

This way, you can valid the LDAP path, domain name, domain

1. Get all its groups.

Use a second method to clearly and simply get the groups.

/// <summary>
///Returns a list with the groups where this user is a member of. 
/// </summary>
/// <remarks>The members in the returned list are instances of Group.</remarks>
/// <returns>Groups where this user is member of.</returns>
public List<DirectoryEntry> GetGroups()
{
    return (from object o in Entry.Properties["memberOf"]
            select new DirectoryEntry(path)
            into dirEntry
            where dirEntry.SchemaClassName == "group"
            select {DirectoryEntry = dirEntry}).ToList();
}

Where path is your OU path (root, or not).

The biggest challenge is managing and building the LDAP path.

I hope that helped.