Get UPN or email for logged in user in a .NET web application

Question

I'm not a .NET developer, and I have a feeling this would be trivial for someone who is:

I have a C# web application that makes user of the user credentials of the logged in user. Currently it uses the SID which comes from

System.Security.Principal.WindowsIdentity.GetCurrent().User.Value

I need to get either the users UPN login or email address (as defined in active directory) instead of the SID. GetCurrent() returns an object of type WindowsIdentity; looking in the details for WindowsIdentity Members:

MSDN: WindowsIdentity Members

I can't see anything that looks like it would give me either the UPN or email in there. How can I pull up that information to use, either by feeding the SID into some other function or calling something different in the first place.

Answer 1

Try:

System.Security.Principal.WindowsIdentity.GetCurrent().Name

Answer 2

To query active directory using a directory searcher you need to do something like this (totally untested code):

    string userName = System.Security.Principal.WindowsIdentity.GetCurrent().Name;
    string ldapPath = "LDAP://domain.company.com";

    public string GetEmail(string userName, string ldapPath)
    {
        using (DirectoryEntry root = new DirectoryEntry(ldapPath))
        {
            DirectorySearcher searcher = new DirectorySearcher(root);
            searcher.Filter = string.Format(@"(&(sAMAccountName={0}))", userName);
            searcher.PropertiesToLoad = "mail";

            SearchResult result = searcher.FindOne();

            if (result != null)
            {
                PropertyValueCollection property = result.Properties["mail"];
                return (string)property.Value;
            }
            else
            { 
                // something bad happened
            }
        }
    }