IdentityServer4 Refresh Token Is Null

Question

I've been scratching my head on this problem for quite a few days already. I have a problem with IdentityServer4 where the token response does not contain a refresh token. The code I have already works fine regarding getting the access token - it's just the refresh token that I cannot seem to figure out.

In my project.json file, I have added the following entries:

"IdentityServer4": "1.0.0-rc3",
"IdentityServer4.AccessTokenValidation": "1.0.1-rc3"

My Startup.cs file contains the following:

public void ConfigureServices(IServiceCollection services)
{
    services.AddIdentityServer()
        .AddInMemoryClients(Config.Clients.Get())
        .AddInMemoryScopes(Config.Scopes.Get())
        .AddInMemoryUsers(Config.Users.Get())
        .AddTemporarySigningCredential();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    app.UseIdentityServer();
}

You may have noticed that I am using Config.Clients, Config.Scope, and Config.Users. Here is the code for those (Config.cs):

public class Config
{
    internal class Clients
    {
        public static IEnumerable<Client> Get()
        {
            return new List<Client> {
                new Client
                {
                    ClientId = "client",
                    ClientName = "Authentication Client",
                    AllowedGrantTypes = GrantTypes.HybridAndClientCredentials,
                    AccessTokenLifetime = 1800,
                    RefreshTokenExpiration = TokenExpiration.Absolute,
                    AbsoluteRefreshTokenLifetime = 1800,
                    ClientSecrets = new List<Secret> {
                        new Secret("secret".Sha256())
                    },
                    AllowedScopes = new List<string>
                    {
                        "api",
                        StandardScopes.OfflineAccess.Name, //For refresh tokens

                    }
                }
            };
        }
    }

    internal class Scopes
    {
        public static IEnumerable<Scope> Get()
        {
            return new List<Scope>
            {
                StandardScopes.OfflineAccess, //For refresh tokens
                new Scope {
                    Name = "api",
                    DisplayName = "API",
                    Description = "API scope",
                    Type = ScopeType.Resource,
                    Claims = new List<ScopeClaim> {
                        new ScopeClaim(JwtClaimTypes.Role)
                    },
                    ScopeSecrets =  new List<Secret> {
                        new Secret("secret".Sha256())
                    }
                }
            };
        }
    }

    internal class Users
    {
        public static List<InMemoryUser> Get()
        {
            return new List<InMemoryUser>
            {
                new InMemoryUser {
                    Subject = "5BE86359-073C-434B-AD2D-A3932222DABE",
                    Username = "admin",
                    Password = "admin",
                    Claims = new List<Claim> {
                        new Claim(JwtClaimTypes.Role, "admin")
                    }
                }
            };
        }
    }
}

And I am calling this IdentityController.cs in order to get the Token:

[Route("api/[controller]")]
public class IdentityController : ControllerBase
{
    [HttpPost("GetToken")]
    public string GetToken()
    {
        DiscoveryResponse dr = new DiscoveryClient("http://localhost:5000").GetAsync().Result;
        TokenClient tokenClient = new TokenClient(dr.TokenEndpoint, "client", "secret", AuthenticationStyle.BasicAuthentication);
        TokenResponse tokenResponse = tokenClient.RequestClientCredentialsAsync("api").Result;

        return tokenResponse.AccessToken; //"tokenResponse" does not contain the refresh token!?
    }
}

I have read quite a few articles, but no where could I find a place where they focus on the Refresh Token alone. They all seem to focus just on basic code that returns the Access Token.

Can someone tell me what I am missing, and maybe show/point me in the right direction? Any help will be greatly appreciated!

Answer 1

You need to include the offline_access scope when requesting the token.

But the client credentials flow does not have support for refresh tokens - so this will not work.