using System;

using System.Linq;

using System.DirectoryServices.AccountManagement;

​

public class Program

{

    public static void Main()

    {

        VerifyCredential("test)=x", "test");

    }

​

​

    public class LdapIdentity

    {

        public string Name { get; set; }

​

        public IdentityType Type { get; set; }

​

        public string TypeName

        {

            get

            {

                switch (Type)

                {

                    case IdentityType.DistinguishedName:

                        return "distinguishedName";

                    case IdentityType.SamAccountName:

                        return "sAMAccountName";

                    case IdentityType.UserPrincipalName:

                        return "userPrincipalName";

                    default:

                        return "name";

                }

            }

        }

​

        public static LdapIdentity ParseUser(string name)

        {

            return Parse(name, true);

        }

​

        public static LdapIdentity ParseGroup(string name)

        {

            return Parse(name, false);

        }

​

        /// <summary>

        /// Converts domain.local to DC=domain,DC=local

        /// </summary>

        public static LdapIdentity FqdnToDn(string name)

        {

            if (string.IsNullOrEmpty(name))

                throw new ArgumentNullException(nameof(name));

            var portIndex = name.IndexOf(":");

            if (portIndex > 0)

            {

                name = name.Substring(0, portIndex);

            }

​

            var domains = name.Split(new[]{'.'}, StringSplitOptions.RemoveEmptyEntries);

            var dn = domains.Select(p => $"DC={p}").ToArray();

            return new LdapIdentity{Name = string.Join(",", dn), Type = IdentityType.DistinguishedName};

        }

​

        /// <summary>

        /// DC part from DN

        /// </summary>

        public static LdapIdentity BaseDn(string dn)

        {

            var ncs = dn.Split(new[]{','}, StringSplitOptions.RemoveEmptyEntries);

            var baseDn = ncs.Where(nc => nc.ToLower().StartsWith("dc="));

            return new LdapIdentity{Type = IdentityType.DistinguishedName, Name = string.Join(",", baseDn)};

        }

​

        private static LdapIdentity Parse(string name, bool isUser)

        {

            if (string.IsNullOrEmpty(name))

                throw new ArgumentNullException(nameof(name));

            var identity = name.ToLower();

            //remove DOMAIN\\ prefix

            var index = identity.IndexOf("\\");

            if (index > 0)

            {

                identity = identity.Substring(index + 1);

            }

​

            var type = isUser ? IdentityType.SamAccountName : IdentityType.Name;

            if (identity.Contains("="))

            {

                type = IdentityType.DistinguishedName;

            }

            else if (identity.Contains("@"))

            {

                type = IdentityType.UserPrincipalName;

            }

​

            return new LdapIdentity{Name = identity, Type = type};

        }

​

        public string DnToFqdn()

        {

            var ncs = Name.Split(new[]{","}, StringSplitOptions.RemoveEmptyEntries);

            var fqdn = ncs.Select(nc => nc.Split(new[]{'='}, StringSplitOptions.RemoveEmptyEntries)[1].TrimEnd(','));

            return string.Join(".", fqdn);

        }

​

        public bool IsChildOf(LdapIdentity parent)

        {

            return Name != parent.Name && Name.EndsWith(parent.Name);

        }

​

        public string UpnToSuffix()

        {

            if (Type != IdentityType.UserPrincipalName)

            {

                throw new InvalidOperationException($"Invalid username format: {Name}. Expected UPN");

            }

​

            var index = Name.IndexOf("@");

            return Name.Substring(index + 1).ToLower();

        }

    }

        public class Configuration

    {

        public bool IsPermittedDomain(String domain)

        {

            return true;

        }

​

        public bool RequiresUpn = false;

        public string Domain = "rdleas";

    }

​

​

    static Configuration _configuration = new Configuration();

    static void VerifyCredential(string userName, string password)

    {

        if (string.IsNullOrEmpty(userName))

        {

            throw new ArgumentNullException(nameof(userName));

        }

​

        if (string.IsNullOrEmpty(password))

        {

            Console.WriteLine("Invalid credentials");

        }

​

        var user = LdapIdentity.ParseUser(userName);

        //check UPN requirements

        if (user.Type == IdentityType.UserPrincipalName)

        {

            var suffix = user.UpnToSuffix();

            if (!_configuration.IsPermittedDomain(suffix))

            {

                Console.WriteLine("Domain not permitted");

            }

        }

        else

        {

            if (_configuration.RequiresUpn)

            {

                Console.WriteLine("Invalid username format");

            }

        }

        var domain = LdapIdentity.FqdnToDn(_configuration.Domain);

        var attributes = new[] { "DistinguishedName", "displayName", "mail", "telephoneNumber", "mobile", "userPrincipalName" };

        var searchFilter = $"(&(objectClass=user)({user.TypeName}={user.Name}))";

        Console.WriteLine(searchFilter);

    }

}