mRemoteNG/ExternalConnectors/DSS/SecretServerInterface.cs

using Microsoft.Win32;
using SecretServerAuthentication.DSS;
using SecretServerRestClient.DSS;

namespace ExternalConnectors.DSS
{
    public class SecretServerInterface
    {
        private static class SSConnectionData
        {
            public static string ssUsername = "";
            public static string ssPassword = "";
            public static string ssUrl = "";
            public static string ssOTP = "";
            public static bool ssSSO = false;
            public static bool initdone = false;

            //token 
            public static string ssTokenBearer = "";
            public static DateTime ssTokenExpiresOn = DateTime.UtcNow;
            public static string ssTokenRefresh = "";

            public static void Init()
            {
                if (initdone == true)
                    return;

                RegistryKey key = Registry.CurrentUser.CreateSubKey(@"SOFTWARE\mRemoteSSInterface");
                try
                {
                    // display gui and ask for data
                    SSConnectionForm f = new SSConnectionForm();
                    string? un = key.GetValue("Username") as string;
                    f.tbUsername.Text = un ?? "";
                    f.tbPassword.Text = SSConnectionData.ssPassword;    // in OTP refresh cases, this value might already be filled

                    string? url = key.GetValue("URL") as string;
                    if (url == null || !url.Contains("://"))
                        url = "https://cred.domain.local/SecretServer";
                    f.tbSSURL.Text = url;

                    var b = key.GetValue("SSO");
                    if (b == null || (string)b != "True")
                        ssSSO = false;
                    else
                        ssSSO = true;
                    f.cbUseSSO.Checked = ssSSO;
                    
                    // show dialog
                    while (true)
                    {
                        _ = f.ShowDialog();

                        if (f.DialogResult != DialogResult.OK)
                            return;

                        // store values to memory
                        ssUsername = f.tbUsername.Text;
                        ssPassword = f.tbPassword.Text;
                        ssUrl = f.tbSSURL.Text;
                        ssSSO = f.cbUseSSO.Checked;
                        ssOTP = f.tbOTP.Text;
                        // check connection first
                        try
                        {
                            if (TestCredentials() == true)
                            {
                                initdone = true;
                                break;
                            }
                        }
                        catch (Exception)
                        {
                            MessageBox.Show("Test Credentials failed - please check your credentials");
                        }
                    }


                    // write values to registry
                    key.SetValue("Username", ssUsername);
                    key.SetValue("URL", ssUrl);
                    key.SetValue("SSO", ssSSO);
                }
                catch (Exception)
                {
                    throw;
                }
                finally
                {
                    key.Close();
                }

            }
        }

        private static bool TestCredentials()
        {
            if (SSConnectionData.ssSSO)
            {
                // checking creds doesn't really make sense here, as we can't modify them anyway if something is wrong
                return true;
            }
            else
            {

                if (!String.IsNullOrEmpty(GetToken()))
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
        }

        private static void FetchSecret(int secretID, out string secretUsername, out string secretPassword, out string secretDomain)
        {
            string baseURL = SSConnectionData.ssUrl;

            SecretModel secret;
            if (SSConnectionData.ssSSO)
            {
                // REQUIRES IIS CONFIG! https://docs.thycotic.com/ss/11.0.0/api-scripting/webservice-iwa-powershell
                var handler = new HttpClientHandler() { UseDefaultCredentials = true };
                using (var httpClient = new HttpClient(handler))
                {
                    // Call REST API:
                    var client = new SecretsServiceClient($"{baseURL}/winauthwebservices/api", httpClient);
                    secret = client.GetSecretAsync(false, true, secretID, null).Result;
                }
            }
            else
            {
                using (var httpClient = new HttpClient())
                {

                    var token = GetToken();
                    // Set credentials (token):
                    httpClient.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token);

                    // Call REST API:
                    var client = new SecretsServiceClient($"{baseURL}/api", httpClient);
                    secret = client.GetSecretAsync(false, true, secretID, null).Result;
                }
            }

            // clear return variables
            secretDomain = "";
            secretUsername = "";
            secretPassword = "";

            // parse data and extract what we need
            foreach (var item in secret.Items)
            {
                if (item.FieldName.ToLower().Equals("domain"))
                    secretDomain = item.ItemValue;
                else if (item.FieldName.ToLower().Equals("username"))
                    secretUsername = item.ItemValue;
                else if (item.FieldName.ToLower().Equals("password"))
                    secretPassword = item.ItemValue;
            }

        }

        private static string GetToken()
        {
            // if there is no token, fetch a fresh one
            if (String.IsNullOrEmpty(SSConnectionData.ssTokenBearer))
            {
                return GetTokenFresh();
            }
            // if there is a token, check if it is valid
            if (SSConnectionData.ssTokenExpiresOn >= DateTime.UtcNow)
            {
                return SSConnectionData.ssTokenBearer;
            }
            else
            {
                // try using refresh token
                using (var httpClient = new HttpClient())
                {
                    var tokenClient = new OAuth2ServiceClient(SSConnectionData.ssUrl, httpClient);
                    TokenResponse token = new();
                    try
                    {
                        token = tokenClient.AuthorizeAsync(Grant_type.Refresh_token, null, null, SSConnectionData.ssTokenRefresh, null).Result;
                        var tokenResult = token.Access_token;

                        SSConnectionData.ssTokenBearer = tokenResult;
                        SSConnectionData.ssTokenRefresh = token.Refresh_token;
                        SSConnectionData.ssTokenExpiresOn = token.Expires_on;
                        return tokenResult;
                    }
                    catch (Exception)
                    {
                        // refresh token failed. clean memory and start fresh
                        SSConnectionData.ssTokenBearer = "";
                        SSConnectionData.ssTokenRefresh = "";
                        SSConnectionData.ssTokenExpiresOn = DateTime.Now;
                        // if OTP is required we need to ask user for a new OTP
                        if (!String.IsNullOrEmpty(SSConnectionData.ssOTP))
                        {
                            SSConnectionData.initdone = false;
                            // the call below executes a connection test, which fetches a valid token
                            SSConnectionData.Init();
                            // we now have a fresh token in memory. return it to caller
                            return SSConnectionData.ssTokenBearer;
                        }
                        else
                        {
                            // no user interaction required. get a fresh token and return it to caller
                            return GetTokenFresh();
                        }
                    }
                }
            }
        }
        static string GetTokenFresh()
        {
            using (var httpClient = new HttpClient())
            {
                // Authenticate:
                var tokenClient = new OAuth2ServiceClient(SSConnectionData.ssUrl, httpClient);
                // call below will throw an exception if the creds are invalid
                var token = tokenClient.AuthorizeAsync(Grant_type.Password, SSConnectionData.ssUsername, SSConnectionData.ssPassword, null, SSConnectionData.ssOTP).Result;
                // here we can be sure the creds are ok - return success state                   
                var tokenResult = token.Access_token;

                SSConnectionData.ssTokenBearer = tokenResult;
                SSConnectionData.ssTokenRefresh = token.Refresh_token;
                SSConnectionData.ssTokenExpiresOn = token.Expires_on;
                return tokenResult;
            }
        }



        // input must be the secret id to fetch
        public static void FetchSecretFromServer(string input, out string username, out string password, out string domain)
        {
            // get secret id
            int secretID = Int32.Parse(input);

            // init connection credentials, display popup if necessary
            SSConnectionData.Init();

            // get the secret
            FetchSecret(secretID, out username, out password, out domain);
        }
    }
}