Retrieving a user principal object using down-level user name

Question

I'm having problems retrieving the User Principal object from AD as follows:

public static UserPrincipal GetUserPrincipalByUserName(string userName, IdentityType identityType, string adUsername, string adPassword, string adDomain)
{
    UserPrincipal result;
    try
    {
        using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, adDomain, adUsername, adPassword))
        {
            result = UserPrincipal.FindByIdentity(pc, identityType, userName);
        }
    }
    catch
    {
        result = null;
    }
    return result;
}

All pretty normal right? However, in my web application, I'm pulling out the username from User.Identity.Name, which gives me the username in the down-level format (domain\username), not my UPN (username@domain.com). My unit tests (1 and 2) pass on the UPN or SAM IdentityTypes, but not on the down-level name provided (3), nor the unqualified username (4), using IdentityType.Name:

[TestClass]
public class ActiveDirectoryTests
{
    public const string Username = "jdoe";
    public const string DownLevelUsername = "DOMAIN\\jdoe";
    public const string Upn = "jdoe@domain.com";
    public const string AdUsername = "username";
    public const string AdPassword = "password";
    public const string AdDomain = "domain";

    [TestMethod]
    public void SearchByUpn()
    {
        Assert.IsNotNull(ActiveDirectory.SafeGetUserPrincipalByUserName(Upn, IdentityType.UserPrincipalName, AdUsername, AdPassword, AdDomain));
    }

    [TestMethod]
    public void SearchBySamUsername()
    {
        Assert.IsNotNull(ActiveDirectory.SafeGetUserPrincipalByUserName(Username, IdentityType.SamAccountName, AdUsername, AdPassword, AdDomain));
    }

    [TestMethod]
    public void SearchByDownLevelUsername()
    {
        Assert.IsNotNull(ActiveDirectory.SafeGetUserPrincipalByUserName(DownLevelUsername, IdentityType.Name, AdUsername, AdPassword, AdDomain));
    }

    [TestMethod]
    public void SearchByUnqualifiedUsername()
    {
        Assert.IsNotNull(ActiveDirectory.SafeGetUserPrincipalByUserName(Username, IdentityType.Name, AdUsername, AdPassword, AdDomain));
    }
}

Can I do this task without just doing some arbitrary string parsing on the down-level name that I get from User.Identity.Name? Can/should I just dig the SID out of the user object and use that instead?

Answer 1

I fixed my own problem just by using the SID, but for info:

• The down-level domain name doesn't directly map to a UPN (missing info on the domain suffix), so basically you can't do text transforms between the two
• The User.Identity.Name is still a mystery - see my other question here: What does System.DirectoryServices.AccountManagement.IdentityType.Name specify?