How to get new refresh token - Identity Server 4

Question

I'm currently making a WPF app and am using Identity Server 4 for authentication stuff. Right now I have it all working so that the user gets a new token when the old one expires using the refresh token:

            //request new token
            using (var newAccessTokenClient = new HttpClient())
            {
                var newAccessTokenResponse = await newAccessTokenClient.RequestRefreshTokenAsync(new RefreshTokenRequest
                {
                    Address = App.Current.Properties["IdentityServerAPIAddress"].ToString() + "connect/token",

                    ClientId = "wpf",
                    ClientSecret = "secret",
                    GrantType = "refresh_token",
                    Scope = "openid offline_access WebAPI",

                    RefreshToken = ReadRefreshToken()
                });

                if (newAccessTokenResponse.IsError)
                {
                    throw new Exception(newAccessTokenResponse.Exception.ToString());
                }
                else
                {
                    //refresh token was success, write new tokens
                    WriteTokens(newAccessTokenResponse.AccessToken, newAccessTokenResponse.RefreshToken);
                    App.Current.Properties["AccessToken"] = newAccessTokenResponse.AccessToken;
                }
            }

The problem is whenever it happens a second time, the Identity Server 4 API complains that the refresh token has been used already. How do I get a new refresh token?

I've seen this documentation about an interface I can implement but I don't know how to use it.

Any help is appreciated. Thanks.

Answer 1

when you request a new access-token using your refresh-token, you should get back a new refresh-token in the same response. Do check the request in Fiddler.

you can also control how IdentityServer deals with refresh-tokens using this client setting:

            RefreshTokenUsage = TokenUsage.OneTimeOnly,