Wednesday, July 27, 2011

LINQ To LDAP: (C)RUD

Just like any other data store you can create, update, and delete data in a directory.

Here's how you create entries using S.DS.P:

LdapConnection connection = new LdapConnection("localhost");

string distinguishedName = "CN=John Doe,CN=Users,CN=Employees,DC=Northwind,DC=local";
AddRequest request = new AddRequest(distinguishedName, "User");

request.Attributes.Add(new DirectoryAttribute("givenname", "John"));
request.Attributes.Add(new DirectoryAttribute("sn", "Doe"));
request.Attributes.Add(new DirectoryAttribute("employeeid", "1"));

connection.SendRequest(request);

Looks pretty straightforward. You give your entry a primary key (distinguished name), an object class, and then populate the attributes for the new entry and submit it to the directory.

So here's how you do it with mapped classes:
public abstract class DirectoryObject
{
    [DistinguishedName]
    public string DistinguishedName { get; set; }

    [DirectoryAttribute(StoreGenerated = true)]
    public DateTime? WhenChanged { get; set; }

    [DirectoryAttribute("cn")]
    public string CommonName { get; set; }

    [DirectoryAttribute(StoreGenerated = true)]
    public DateTime? WhenCreated { get; set; }

    [DirectoryAttribute("objectguid", StoreGenerated = true)]
    public Guid Guid { get; set; }

    [DirectoryAttribute]
    public string Name { get; set; }
}

[DirectorySchema(NamingContext, ObjectCategory = "Person", ObjectClass = "user")]
public class User : DirectoryObject
{
    private const string NamingContext = "CN=Users 1,CN=TestContainer,CN=Employees,DC=Northwind,DC=local";

    [DirectoryAttribute("objectsid", StoreGenerated = true)]
    public SecurityIdentifier SID { get; set; }

    [DirectoryAttribute("givenname")]
    public string FirstName { get; set; }

    [DirectoryAttribute("sn")]
    public string LastName { get; set; }

    [DirectoryAttribute("directreports")]
    public string[] Employees { get; set; }

    [DirectoryAttribute]
    public string Title { get; set; }

    [DirectoryAttribute]
    public string PostalCode { get; set; }

    [DirectoryAttribute(ImageFormat = ImageType.Png)]
    public Bitmap Photo { get; set; }

    [DirectoryAttribute("l")]
    public string City { get; set; }

    [DirectoryAttribute("c")]
    public string Country { get; set; }

    [DirectoryAttribute]
    public string EmployeeID { get; set; }

    [DirectoryAttribute]
    public string TelephoneNumber { get; set; }

    [DirectoryAttribute("pwdlastset", DateTimeFormat = null, StoreGenerated = true)]
    public DateTime? PasswordLastSet { get; set; }

    [DirectoryAttribute]
    public string Street { get; set; }

    public void SetDistinguishedName()
    {
        DistinguishedName = "CN=" + CommonName + "," + NamingContext;
    }
}

There are a few items to note here. First is the StoreGenerated property of DirectoryAttribute. This allows the DirectoryContext to only update attributes that the store doesn't manage. The second is the DistinguishedName attribute which mainly helps when calling Add and Update. The third is the DirectoryObject which isn't a part of LINQ to LDAP, but is an example abstract base class that all directory objects can sub-type.
User user = new User
                {
                    City = "Some City",
                    CommonName = "John Doe",
                    Country = "US",
                    EmployeeID = "1",
                    FirstName = "John",
                    LastName = "Doe",
                    Name = "Doe, John",
                    Street = "1234 Street",
                    Title = "Unknown",
                    PostalCode = "12345",
                    TelephoneNumber = "123-456-7890"
                };

user.SetDistinguishedName();
var factory = new LdapConnectionFactory("localhost");
using (var context = new DirectoryContext(factory.GetConnection(), true))
{
    User added = context.Add(user);
}

I create a new user and initialize its properties. Whenever an object is added or updated, a fresh version is retrieved using GetByDN.

Alternatively, you can perform the same operation using a dictionary:
string dn = "CN=John Doe,CN=Users 1,CN=TestContainer,CN=Employees,DC=Northwind,DC=local";
var attributes = new Dictionary<string, object>
                        {
                            {"l", "Some City"},
                            {"cn", "John Doe"},
                            {"c", "US"},
                            {"EmployeeID", "1"},
                            {"givenname", "John"},
                            {"sn", "Doe"},
                            {"Name", "Doe, John"},
                            {"Street", "1234 Street"},
                            {"Title", "Unknown"},
                            {"PostalCode", "12345"},
                            {"TelephoneNumber", "123-456-7890"}
                        };

var factory = new LdapConnectionFactory("localhost");
using (var context = new DirectoryContext(factory.GetConnection(), true))
{
    IDictionary<string, object> added = context.Add(dn, "User", attributes);
}

Or by converting an anonymous object to a dictionary:
string dn = "CN=John Doe,CN=Users 1,CN=TestContainer,CN=Employees,DC=Northwind,DC=local";
var user = new
                {
                    City = "Some City",
                    CommonName = "John Doe",
                    Country = "US",
                    EmployeeID = "1",
                    FirstName = "John",
                    LastName = "Doe",
                    Name = "Doe, John",
                    Street = "1234 Street",
                    Title = "Unknown",
                    PostalCode = "12345",
                    TelephoneNumber = "123-456-7890"
                };

var factory = new LdapConnectionFactory("localhost");
using (var context = new DirectoryContext(factory.GetConnection(), true))
{
    IDictionary<string, object> added = context.Add(dn, "User", user.ToDictionary());
}

ToDictionary is just an extension method that reflects over an attribute and creates a dictionary from its properties.

So I think that covers how to add new entries. Questions, thoughts, improvements?