Parse subject alternative directory address of an X509 certificate

Here is an example of extracting the common name of the directory address of the subject alternative name of a certificate using the bouncycastle library

X509Certificate cert = ...

foreach (ArrayList sName in cert.GetSubjectAlternativeNames() as ArrayList)
{
    if ((int)sName[0] == 4) //tag 4 is for DirectoryAddress
    {
        string dirName = sName[1].ToString();

        X509Name x500Name = new (dirName);
        string altCn = x500Name.GetValues(X509Name.CN)[0].ToString();

        Console.WriteLine(altCn);
    }
}

Other possible general names:

public const int OtherName                  = 0;
public const int Rfc822Name                 = 1;
public const int DnsName                    = 2;
public const int X400Address                = 3;
public const int DirectoryName              = 4;
public const int EdiPartyName               = 5;
public const int UniformResourceIdentifier  = 6;
public const int IPAddress                  = 7;
public const int RegisteredID               = 8;