Blazor WebAssembly App with Individual Accounts and ASP.NET Core Hosted - Token request - "error": "unauthorized_client"

Question

Creating a new Blazor WebAssembly App with Microsoft Visual Studio 2019 Version 16.9.4 with these specifications: Target Framework .NET 5.0 , Authentication Type Individual Accounts and ASP.NET Core Hosted :

Gives a Server project with these NuGet s at version 5.0.5 :

• Microsoft.AspNetCore.ApiAuthorization.IdentityServer
• Microsoft.AspNetCore.Identity.EntityFrameworkCore
• Microsoft.AspNetCore.Identity.UI

Startup.cs contains this code:

services.AddIdentityServer()
    .AddApiAuthorization<ApplicationUser, ApplicationDbContext>();

services.AddAuthentication()
    .AddIdentityServerJwt();

Reading the blog post ASP.NET Core Authentication with IdentityServer4 from Microsoft I should be able to retrieve a token with a sample request that looks like this:

POST /connect/token HTTP/1.1
Host: localhost:5000
Cache-Control: no-cache
Postman-Token: 958df72b-663c-5638-052a-aed41ba0dbd1
Content-Type: application/x-www-form-urlencoded

grant_type=password&username=Mike%40Contoso.com&password=MikesPassword1!&client_id=myClient&scope=myAPIs

https://devblogs.microsoft.com/aspnet/asp-net-core-authentication-with-identityserver4/

Creating a request that looks like that but for the solution created:

POST /connect/token HTTP/1.1
Host: localhost:44388
Content-Type: application/x-www-form-urlencoded
Content-Length: 153

grant_type=password&username=example%40example.com&password=Password1&client_id=WebApplication4.Client&scope=WebApplication4.ServerAPI%20openid%20profile

This request returns HTTP Status 400 Bad Request with body:

{
    "error": "unauthorized_client"
}

I'm pretty sure the values are correct since I got client_id and scope from the request used to sign in to the web application. That flow does not use grant_type=password though. Example request from login:

https://localhost:44388/Identity/Account/Login?ReturnUrl=/connect/authorize/callback?client_id=WebApplication4.Client&redirect_uri=https%3A%2F%2Flocalhost%3A44388%2Fauthentication%2Flogin-callback&response_type=code&scope=WebApplication4.ServerAPI%20openid%20profile&state=12345&code_challenge=12345&code_challenge_method=S256&response_mode=query

Confirmation that the user exists and works:

What am I missing?

Answer 1

TLDR:

Remove this from appsettings.json :

"Clients": {
  "WebApplication4.Client": {
    "Profile": "IdentityServerSPA"
  }
}

Edit Startup.cs :

services.AddIdentityServer()
    .AddApiAuthorization<ApplicationUser, ApplicationDbContext>(options =>
    {
        options.Clients.AddIdentityServerSPA("WebApplication4.Client", builder =>
        {
            builder.WithRedirectUri("/authentication/login-callback");
            builder.WithLogoutRedirectUri("/authentication/logout-callback");
        });
        options.Clients.Add(new IdentityServer4.Models.Client
        {
            ClientId = "WebApplication4.Integration",
            AllowedGrantTypes = { GrantType.ResourceOwnerPassword },
            //Use Configuration.GetSection("MySecretValue").Value; to get a value from appsettings.json
            ClientSecrets = { new Secret("MySecretValue".Sha256()) },
            AllowedScopes = { "WebApplication4.ServerAPI", "openid", "profile" }
        });
    });

This request will work:

POST /connect/token HTTP/1.1
Host: localhost:44388
Content-Type: application/x-www-form-urlencoded
Content-Length: 168

grant_type=password&username=example%40example.com&password=Password1!&client_id=WebApplication4.Integration&scope=WebApplication4.ServerAPI&client_secret=MySecretValue

Long answer:

I started out with trying to get a better error messages with Logging.

I added the code below to public static IHostBuilder CreateHostBuilder(string[] args) in Program.cs :

.ConfigureLogging(logging =>
{
    logging.ClearProviders();
    logging.AddConsole();
})

https://docs.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-5.0

When debugging I could then show output from the Server application when I made the request. It looked like this:

info: IdentityServer4.Hosting.IdentityServerMiddleware[0]
      Invoking IdentityServer endpoint: IdentityServer4.Endpoints.TokenEndpoint for /connect/token
info: IdentityServer4.Events.DefaultEventService[0]
      {
        "ClientId": "WebApplication4.Client",
        "AuthenticationMethod": "NoSecret",
        "Category": "Authentication",
        "Name": "Client Authentication Success",
        "EventType": "Success",
        "Id": 1010,
        "ActivityId": "8000000a-0000-8f00-b63f-84710c7967bb",
        "TimeStamp": "2021-04-29T11:47:07Z",
        "ProcessId": 8436,
        "LocalIpAddress": "::1:44388",
        "RemoteIpAddress": "::1"
      }
fail: IdentityServer4.Validation.TokenRequestValidator[0]
      Client not authorized for resource owner flow, check the AllowedGrantTypes setting{ client_id = WebApplication4.Client }, details: {
        "ClientId": "WebApplication4.Client",
        "ClientName": "WebApplication4.Client",
        "GrantType": "password",
        "Raw": {
          "grant_type": "password",
          "username": "example@example.com",
          "password": "***REDACTED***",
          "client_id": "WebApplication4.Client",
          "scope": "WebApplication4.ServerAPI"
        }
      }
info: IdentityServer4.Events.DefaultEventService[0]
      {
        "ClientId": "WebApplication4.Client",
        "ClientName": "WebApplication4.Client",
        "Endpoint": "Token",
        "GrantType": "password",
        "Error": "unauthorized_client",
        "Category": "Token",
        "Name": "Token Issued Failure",
        "EventType": "Failure",
        "Id": 2001,
        "ActivityId": "8000000a-0000-8f00-b63f-84710c7967bb",
        "TimeStamp": "2021-04-29T11:47:07Z",
        "ProcessId": 8436,
        "LocalIpAddress": "::1:44388",
        "RemoteIpAddress": "::1"
      }

The error message to look at is Client not authorized for resource owner flow, check the AllowedGrantTypes setting{ client_id = WebApplication4.Client } .

With this error message I found this Question:

Question about ASP.NET Core 3 Identity / Identity Server / SPA support for Resource Owner Password Grant Type

There I could read

found that the allowed grant type of password was not being added when the profile is set to IdentityServerSPA.

Looking at appsettings.json the application uses that profile:

"IdentityServer": {
  "Clients": {
    "WebApplication4.Client": {
      "Profile": "IdentityServerSPA"
    }
  }
},

Looking at Microsoft Application profiles what it actually does is this:

• The redirect_uri defaults to /authentication/login-callback.
• The post_logout_redirect_uri defaults to /authentication/logout-callback.
• The set of scopes includes the openid, profile, and every scope defined for the APIs in the app.
• The set of allowed OIDC response types is id_token token or each of them individually (id_token, token).
• The allowed response mode is fragment.

https://docs.microsoft.com/en-us/aspnet/core/security/authentication/identity-api-authorization?view=aspnetcore-5.0#application-profiles

Before starting to modify this I visited the URL https://localhost:44388/.well-known/openid-configuration to get the current configuration. It looked like this and specifically says grant_types_supported: ...password :

{
    "issuer": "https://localhost:44388",
    "jwks_uri": "https://localhost:44388/.well-known/openid-configuration/jwks",
    "authorization_endpoint": "https://localhost:44388/connect/authorize",
    "token_endpoint": "https://localhost:44388/connect/token",
    "userinfo_endpoint": "https://localhost:44388/connect/userinfo",
    "end_session_endpoint": "https://localhost:44388/connect/endsession",
    "check_session_iframe": "https://localhost:44388/connect/checksession",
    "revocation_endpoint": "https://localhost:44388/connect/revocation",
    "introspection_endpoint": "https://localhost:44388/connect/introspect",
    "device_authorization_endpoint": "https://localhost:44388/connect/deviceauthorization",
    "frontchannel_logout_supported": true,
    "frontchannel_logout_session_supported": true,
    "backchannel_logout_supported": true,
    "backchannel_logout_session_supported": true,
    "scopes_supported": [
        "openid",
        "profile",
        "WebApplication4.ServerAPI",
        "offline_access"
    ],
    "claims_supported": [
        "sub",
        "name",
        "family_name",
        "given_name",
        "middle_name",
        "nickname",
        "preferred_username",
        "profile",
        "picture",
        "website",
        "gender",
        "birthdate",
        "zoneinfo",
        "locale",
        "updated_at"
    ],
    "grant_types_supported": [
        "authorization_code",
        "client_credentials",
        "refresh_token",
        "implicit",
        "password",
        "urn:ietf:params:oauth:grant-type:device_code"
    ],
    "response_types_supported": [
        "code",
        "token",
        "id_token",
        "id_token token",
        "code id_token",
        "code token",
        "code id_token token"
    ],
    "response_modes_supported": [
        "form_post",
        "query",
        "fragment"
    ],
    "token_endpoint_auth_methods_supported": [
        "client_secret_basic",
        "client_secret_post"
    ],
    "id_token_signing_alg_values_supported": [
        "RS256"
    ],
    "subject_types_supported": [
        "public"
    ],
    "code_challenge_methods_supported": [
        "plain",
        "S256"
    ],
    "request_parameter_supported": true
}

For some reason IdentityServer Clients can not be configured in code and in appsettings.json . I therefore removed Clients from appsettings.json and added this to Startup.cs:

services.AddIdentityServer()
    .AddApiAuthorization<ApplicationUser, ApplicationDbContext>(options =>
    {
        options.Clients.AddIdentityServerSPA("WebApplication4.Client", builder =>
        {
            builder.WithRedirectUri("/authentication/login-callback");
            builder.WithLogoutRedirectUri("/authentication/logout-callback");
        });
        options.Clients.Add(new IdentityServer4.Models.Client
        {
            ClientId = "WebApplication4.Integration",
            AllowedGrantTypes = { GrantType.ResourceOwnerPassword },
            AllowedScopes = { "WebApplication4.ServerAPI", "openid", "profile" }
        });
    });

Without WithRedirectUri and WithLogoutRedirectUri it did not work, OidcConfigurationController got an exception for ClientRequestParametersProvider.GetClientParameters(HttpContext, clientId); with System.InvalidOperationException: 'Sequence contains no elements' . For some reason this is fixed automatically when using appsettings.json .

I now got the error message when posting to /connect/token :

{
    "error": "invalid_client"
}

But I got a much better error in the log:

Invalid client configuration for client WebApplication4.Integration: Client secret is required for password, but no client secret is configured.

Added a secret to Startup.cs :

services.AddIdentityServer()
    .AddApiAuthorization<ApplicationUser, ApplicationDbContext>(options =>
    {
        options.Clients.AddIdentityServerSPA("WebApplication4.Client", builder =>
        {
            builder.WithRedirectUri("/authentication/login-callback");
            builder.WithLogoutRedirectUri("/authentication/logout-callback");
        });
        options.Clients.Add(new IdentityServer4.Models.Client
        {
            ClientId = "WebApplication4.Integration",
            AllowedGrantTypes = { GrantType.ResourceOwnerPassword },
            //Use Configuration.GetSection("MySecretValue").Value; to get a value from appsettings.json
            ClientSecrets = { new Secret("MySecretValue".Sha256()) },
            AllowedScopes = { "WebApplication4.ServerAPI", "openid", "profile" }
        });
    });

And the request:

POST /connect/token HTTP/1.1
Host: localhost:44388
Content-Type: application/x-www-form-urlencoded
Content-Length: 168

grant_type=password&username=example%40example.com&password=Password1!&client_id=WebApplication4.Integration&scope=WebApplication4.ServerAPI&client_secret=MySecretValue

It finally worked and the normal login flow worked as well!