Howto get domainname from UserPrincipal or PrincipalSearcher

Question

I have the following code which returns me a UserPrincipal but loginname never includes the domainname. There is also no property "Domainname" or similar.

How can i get from a UserPrincipal or PrincipalSearcher the domain to the user/returned user?

    PrincipalContext ctx = new PrincipalContext(ContextType.Domain);
    UserPrincipal user = new UserPrincipal(ctx);
    user.SamAccountName = txtSearch.Text;
    PrincipalSearcher searcher = new PrincipalSearcher(user);

    PrincipalSearchResult<Principal> results = searcher.FindAll();
    foreach (UserPrincipal u in results)
    {
        Response.Write(u.Name + "<br />");
    }

Answer 1

It worked for me by using

usercontext.Sid.Translate(typeof(NTAccount)).ToString();

This returns domain\user.

Answer 2

Necromancing.
Or you could just get the domain from the context of the UserPrincipal...

usr.Domain = user.Context.Name; // + "/" + user.Context.Container;

but I suppose that would be too simple, and not error-prone enough.
You could also get if from the DirectoryEntry path, with LDAP/LDAPS:

using (System.DirectoryServices.DirectoryEntry de = (System.DirectoryServices.DirectoryEntry)user.GetUnderlyingObject())
{
    int i = -1;

    if (de != null && ((i = de.Path.IndexOf("//")) != -1))
    {
        string protocol = de.Path.Substring(0, i + 2);
        usr.Domain = protocol + user.Context.Name; // + "/" + user.Context.Container;
    } // End if (de != null) 
    else
    {
        if ((user.Context.Options & System.DirectoryServices.AccountManagement.ContextOptions.SecureSocketLayer) != 0)
        {
            usr.Domain = "LDAPS://" + user.Context.Name; // + "/" + user.Context.Container;
        }
        else
        {
            usr.Domain = "LDAP://" + user.Context.Name; // + "/" + user.Context.Container;
        }
    }
} // End Using de 

Or you could get the domain by searching all domains for said username:

public string GetFullDomainName(string friendlyOrQualifiedName)
{
    string retValue = null;

    System.DirectoryServices.ActiveDirectory.DirectoryContext context = null;

    if(this.IntegratedSecurity)
    {
        context = new System.DirectoryServices.ActiveDirectory.DirectoryContext(
            System.DirectoryServices.ActiveDirectory.DirectoryContextType.Domain, friendlyOrQualifiedName);
    }
    else
    {
        context = new System.DirectoryServices.ActiveDirectory.DirectoryContext(
            System.DirectoryServices.ActiveDirectory.DirectoryContextType.Domain, friendlyOrQualifiedName, 
            this.Username, this.m_password
        );
    }

    using (System.DirectoryServices.ActiveDirectory.Domain domain =
          System.DirectoryServices.ActiveDirectory.Domain.GetDomain(context))
    {
        retValue = domain.Name;
    }

    return retValue;
} // End Function GetFullDomainName 


public System.Collections.Generic.List<string> 
    GetDomains() 
{
    System.Collections.Generic.List<string> domains = 
        new System.Collections.Generic.List<string>();

    using (System.DirectoryServices.ActiveDirectory.Forest cf = 
        System.DirectoryServices.ActiveDirectory.Forest.GetCurrentForest())
    {

        // Querying the current Forest for the domains within.
        foreach (System.DirectoryServices.ActiveDirectory.Domain d in cf.Domains)
        {
            domains.Add(d.Name);
        } // Next d 

    } // End Using cf 

    return domains;
} // End Function GetDomains 


/// <summary>
/// Escapes the LDAP search filter to prevent LDAP injection attacks.
/// </summary>
/// <param name="searchFilter">The search filter.</param>
/// <see cref="https://blogs.oracle.com/shankar/entry/what_is_ldap_injection" />
/// <see cref="http://msdn.microsoft.com/en-us/library/aa746475.aspx" />
/// <returns>The escaped search filter.</returns>
private static string EscapeLdapSearchFilter(string searchFilter)
{
    string retValue = null;

    // http://web.archive.org/web/20160922224553/http://blogs.oracle.com/shankar/entry/what_is_ldap_injection
    // https://docs.microsoft.com/en-us/windows/win32/adsi/search-filter-syntax#special-characters

    System.Text.StringBuilder escape = new System.Text.StringBuilder(); 

    for (int i = 0; i < searchFilter.Length; ++i)
    {
        char current = searchFilter[i];
        switch (current)
        {
            case '\\':
                escape.Append(@"\5c");
                break;
            case '*':
                escape.Append(@"\2a");
                break;
            case '(':
                escape.Append(@"\28");
                break;
            case ')':
                escape.Append(@"\29");
                break;
            case '\u0000':
                escape.Append(@"\00");
                break;
            case '/':
                escape.Append(@"\2f");
                break;
            default:
                escape.Append(current);
                break;
        } // End Switch 

    } // Next i 

    retValue = escape.ToString();
    escape.Clear();
    escape = null;

    return retValue;
} // End Function EscapeLdapSearchFilter


private static string EscapeDN(string name)
{
    System.Text.StringBuilder escape = new System.Text.StringBuilder();

    if ((name.Length > 0) && ((name[0] == ' ') || (name[0] == '#')))
    {
        escape.Append(@"\"); // add the leading backslash if needed
    }

    for (int i = 0; i < name.Length; i++)
    {
        char curChar = name[i];
        switch (curChar)
        {
            case '\\':
                escape.Append(@"\\");
                break;
            case ',':
                escape.Append(@"\,");
                break;
            case '+':
                escape.Append(@"\+");
                break;
            case '"':
                escape.Append(@"\""");
                break;
            case '<':
                escape.Append(@"\<");
                break;
            case '>':
                escape.Append(@"\>");
                break;
            case ';':
                escape.Append(@"\;");
                break;
            default:
                escape.Append(curChar);
                break;
        } // End Switch 

    } // Next i 

    if ((name.Length > 1) && (name[name.Length-1] == ' '))
    {
        escape.Insert(escape.Length - 1, '\\'); // add the trailing backslash if needed
    } // End if ((name.Length > 1) && (name[name.Length-1] == ' ')) 

    return escape.ToString();
} // End Function EscapeDN 




public string GetUserDomain(string userNameOrEmail)
{
    System.Collections.Generic.List<string> ls =
        new System.Collections.Generic.List<string>();

    userNameOrEmail = EscapeLdapSearchFilter(userNameOrEmail);

    foreach (string thisDomain in this.GetDomains())
    {
        // string ldapPath = this.Protocol + "://" + thisDomain;

        using (System.DirectoryServices.DirectoryEntry domain = new System.DirectoryServices.DirectoryEntry(thisDomain)) // ldapPath))
        {
            using (System.DirectoryServices.DirectorySearcher searcher = new System.DirectoryServices.DirectorySearcher())
            {
                searcher.SearchRoot = domain;
                searcher.SearchScope = System.DirectoryServices.SearchScope.Subtree;
                searcher.PropertiesToLoad.Add("sAMAccountName");
                searcher.PropertiesToLoad.Add("mail");
                searcher.PropertiesToLoad.Add("proxyAddresses");

                // The Filter is very important, so is its query string. The 'objectClass' parameter is mandatory.
                // Once we specified the 'objectClass', we want to look for the user whose login
                // login is userName.
                // searcher.Filter = $"(&(objectClass=user)(sAMAccountName={userName}))";

                // string email = "";
                // searcher.Filter = $"(&(ObjectClass=user)(mail={email}))";

                // Another example is "(&(objectClass=printer)(|(building=42)(building=43)))"
                //searcher.Filter = $"(&(objectClass=user)(|(sAMAccountName={userNameOrEmail})(mail={userNameOrEmail})))";

                // case insensitive !
                searcher.Filter = $"(&(objectClass=user)(|(sAMAccountName={userNameOrEmail})(mail={userNameOrEmail})(proxyAddresses=smtp:{userNameOrEmail})))";

                try
                {
                    using (System.DirectoryServices.SearchResultCollection results = searcher.FindAll())
                    {
                        // If the user cannot be found, then let's check next domain.
                        if (results == null || results.Count == 0)
                            continue;
                    } // End Using results 

                    // Here, we yield return for we want all of the domain which this userName is authenticated.
                    // yield return domain.Path;

                    // string serv = domain.Options.GetCurrentServerName();
                    // System.Console.WriteLine(serv);

                    // ls.Add(domain.Path); 
                    ls.Add(domain.Name); // Full domain name (non-friendly)

                    // Friendly domain name 
                    // if (domain.Properties.Contains("Name")) ls.Add(System.Convert.ToString(domain.Properties["Name"].Value));



                    //foreach (System.DirectoryServices.PropertyValueCollection p in domain.Properties)
                    //{
                    //    System.Console.WriteLine(p.PropertyName);
                    //    System.Console.WriteLine(p.Value);
                    //}

                } // End Try
                catch (System.Exception)
                { }

            } // End Using searcher 

        } // End Using domain 

    } // Next thisDomain

    // But hey, you said domain, not domains ;)
    if(ls.Count > 0)
        return ls[0];

    return null;
} // End Function GetUserDomain