Can't authenticate MobileServiceClient in Azure ASP.NET Backend

Question

I have ASP.NET Web Application (.NET Framework) based on Visual Studio 2019 template with custom authentication with individual user accounts.

public void ConfigureAuth(IAppBuilder app)
{


           // Configure the db context and user manager to use a single instance per request
                app.CreatePerOwinContext(ApplicationDbContext.Create);
                app.CreatePerOwinContext<ApplicationUserManager>(ApplicationUserManager.Create);

                // Enable the application to use a cookie to store information for the signed in user
                // and to use a cookie to temporarily store information about a user logging in with a third party login provider
                app.UseCookieAuthentication(new CookieAuthenticationOptions());
                app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

                // Configure the application for OAuth based flow
                PublicClientId = "self";
                OAuthOptions = new OAuthAuthorizationServerOptions
                {
                    TokenEndpointPath = new PathString("/Token"),
                    Provider = new ApplicationOAuthProvider(PublicClientId),
                    AuthorizeEndpointPath = new PathString("/api/Account/ExternalLogin"),
                    AccessTokenExpireTimeSpan = TimeSpan.FromDays(10),
                    // In production mode set AllowInsecureHttp = false
                    AllowInsecureHttp = false
                };

                // Enable the application to use bearer tokens to authenticate users
                app.UseOAuthBearerTokens(OAuthOptions);
    }

It works with Postman. I am able to obtain a token and access controller marked as [Authorize]

I am struggling with authentication of MobileServiceClient that I use for offline sync. Client is initialized in this way:

client = new MobileServiceClient(App.BackendUrl, new NativeMessageHandler());      

         public async Task LoginAsync(string username, string password)
                {
                    try
                    {

                        var token = await GetAuthenticationToken(username, password);

                        MobileServiceUser user = new MobileServiceUser(token.userName);

                        user.MobileServiceAuthenticationToken = token.Access_Token;

                        client.CurrentUser = user;

                    }
                    catch (InvalidGrantException) 
                    {
                        throw; 
                    }
                    catch (MobileServiceInvalidOperationException ex) 
                    { 
                        throw; 
                    }
                    catch (Exception ex)
                    {
                        Crashes.TrackError(ex);
                        Debug.WriteLine(ex);
                        throw;
                    }
                }

            private async Task<AuthenticationToken> GetAuthenticationToken(string username, string password)
            {
                var keyValues = new List<KeyValuePair<string, string>>
                {
                    new KeyValuePair<string, string>("username", username),
                    new KeyValuePair<string, string>("password", password),
                    new KeyValuePair<string, string>("grant_type", "password")
                };

                HttpContent httpContent = new FormUrlEncodedContent(keyValues);
                httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");

                try
                {

                    var response = await client.InvokeApiAsync("/token",
                                            httpContent,
                                            HttpMethod.Post,
                                            null,
                                            null);

                    return JsonConvert.DeserializeObject<AuthenticationToken>(await response.Content.ReadAsStringAsync());
                }
                catch (MobileServiceInvalidOperationException exception)
                {
                    if (string.Equals(exception.Message, "invalid_grant"))
                        throw new InvalidGrantException("invalid credentials",  exception);
                    else
                        throw;
                }
            } 

Here some code for testing:

    public async Task InitializeAsync()
            {
                if (client?.SyncContext?.IsInitialized ?? false)
                    return;
                // Create a reference to the local sqlite store
                const string path = "syncstore.db";

                var store = new MobileServiceSQLiteStore(path);

                // Define the database schema
                 store.DefineTable<Brand>(); brandTable = new AzureCloudTable<Brand>(client, null);

                // Actually create the store and update the schema
                try
                {
                    await client.SyncContext.InitializeAsync(store);
                }
                catch (Exception ex)
                {
                    Crashes.TrackError(ex);
                    Debug.WriteLine(ex);
                }
            }

            async Task Test(string username, string password)
            {
                await LoginAsync("Simulator8", " ");
                await InitializeAsync();

                //Test pull
                try
                {
                  await brandTable.PullAsync();
                }
                catch (Exception ex)
                {
                }
            }

Test throws exception:

+ ex {Microsoft.WindowsAzure.MobileServices.MobileServiceInvalidOperationException: The request could not be completed. (Unauthorized) at Microsoft.WindowsAzure.MobileServices.MobileServiceHttpClient.ThrowInvalidResponse (System.Net.Http.HttpRequestMessage request, System.Net.Http.HttpResponseMessage response) [0x001d2] in:0 at Microsoft.WindowsAzure.MobileServices.MobileServiceHttpClient.SendRequestAsync (System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, System.Boolean ensureResponseContent, System.Threading.CancellationToken cancellationToken) [0x00121] in:0 at Microsoft.WindowsAzure.MobileServices.MobileServiceHttpClient.RequestAsync (System.Boolean UseHandlers, System.Net.Http.HttpMethod method, System.String uriPathAndQuery, Microsoft.WindowsAzure.MobileServices.MobileServiceUser user, System.String content, System.Boolean ensureResponseConten t, System.Collections.Generic.IDictionary 2[TKey,TValue] requestHeaders, System.Threading.CancellationToken cancellationToken) [0x000f0] in <d385e67aff524dc7bd2d27425b9e81ae>:0 at Microsoft.WindowsAzure.MobileServices.MobileServiceTable.ReadAsync (System.String uriString, Microsoft.WindowsAzure.MobileServices.MobileServiceFeatures features) [0x0009c] in <d385e67aff524dc7bd2d27425b9e81ae>:0 at Microsoft.WindowsAzure.MobileServices.MobileServiceTable.ReadAsync (System.String query, System.Collections.Generic.IDictionary 2[TKey,TValue] parameters, Microsoft.WindowsAzure.MobileServices.MobileServiceFeatures features) [0x00136] in:0 at Microsoft.WindowsAzure.MobileServices.Sync.PullAction.ProcessTableAsync () [0x00134] in:0 at Microsoft.WindowsAzure.MobileServices.Sync.TableAction.ExecuteAsync () [0x00251] in:0 at Microsoft.WindowsAzure.MobileServices.Sync.MobileServiceSyncContext.ExecuteSyncAction (Microsoft.WindowsAzure.MobileServices.Sync.Syn cAction action) [0x00090] in:0 at Microsoft.WindowsAzure.MobileServices.Sync.MobileServiceSyncContext.PullAsync (System.String tableName, Microsoft.WindowsAzure.MobileServices.Sync.MobileServiceTableKind tableKind, System.String queryId, System.String query, Microsoft.WindowsAzure.MobileServices.MobileServiceRemoteTableOptions options, System.Collections.Generic.IDictionary 2[TKey,TValue] parameters, System.Collections.Generic.IEnumerable 1[T] relatedTables, Microsoft.WindowsAzure.MobileServices.MobileServiceObjectReader reader, System.Threading.CancellationToken cancellationToken, Microsoft.WindowsAzure.MobileServices.Sync.PullOptions pullOptions) [0x00361] in:0

1. If I try token that I receive in token.Access_Token in Postman it works
2. If I try sync with controller without [Authorize] it works.
3. This is the message from Azure Log stream:

*2020-04-15 18:20:10 xxxBACKENDxxx POST /token X-ARR-LOG-ID=c0abefa4-8754-47e2-966d-add7716e6a95 443 - 000.000.000 ZUMO/4.1+(lang=Managed;+os=iOS;+os_version=13.3;+arch=MacOSX;+version=4.1.2.0) - - xxxBACKENDxxx.azurewebsites.net 200 0 0 1825 1377 6312

2020-04-15 18:20:10 xxxBACKENDxxx GET /tables/Brand $filter=(updatedAt%20ge%20datetimeoffset'2020-04-06T21%3A05%3A17.7200000%2B00%3A00')&$orderby=updatedAt&$skip=0&$top=50&__includeDeleted=true&X-ARR-LOG-ID=287a5464-caad-43be-a3c5-25245e0f9f49 443 Simulator8 000.000.000 ZUMO/4.1+(lang=Managed;+os=iOS;+os_version=13.3;+arch=MacOSX;+version=4.1.2.0) ARRAffinity=62f587f816224cc3b867889be38db42f5322e4bdb4b71703dac6a261166d1545;+.AspNet.Cookies=rpLpkcIS9jfvK1FyWL6q-2_5ImjYFR9yB1ZiIPd4iiTxHAGL5A0CFu4qihtFZmu-GKKQzVQ5hoxReQGQVpS7w2a0jnjvvFL4dpe_wS9_7nfTxMTBuDXiKDHGZBakbd28UR1CWvyq7iFDUI8AkKj1zrM2uYz93kpg1WMQCSx-Z3tREike74S3LqUOCnRuPjil-wMqOzDDDTJKL9JLQZ750MbQbT_-DLmj31qMa55emfGgUcSEM7I5ksMD2IIMvEeAEqwsp-XKyhp17utOTy5OepSqO8lxrGLng96GY-shVFBP4gDt7YP2bNS3RCtXkCWSOve4g7ckWDud8SAOk1KRpkj4k-B9ZogpAqc9Zuz0idTBruY3HZ3sTHCw__atnd8DQVwNQtEu8kX1Cz2WFbkO35GHOULA7TvKyGiJu-LOpf2-SZPoNl12lqH0jdvT1kI32WF2RDKbQ2W9eyWzURHOsUvekcg5EJOZUDEehXYfbo0 - xxxBACKENDxxx.azurewebsites.net 401 0 0 543 2837 46*

Username is correct. But if I don't call GetAuthenticationToken from LoginAsync and pass token manually to the user.MobileServiceAuthenticationToken then the result is:

//var token = await GetAuthenticationToken(username, password);

MobileServiceUser user = new MobileServiceUser(username);

user.MobileServiceAuthenticationToken = "bearer _F-Bd8_74ZGV2gmKN4dkjPIRgZh7keYa-nIKpbjvSlfBV9wP2Reu9Z9Spy1eqK47LRdnXxKlMsZ5...
client.CurrentUser = user;

2020-04-15 18:15:34 xxxBACKENDxxx GET /tables/Brand $filter=(updatedAt%20ge%20datetimeoffset'2020-04-06T21%3A05%3A17.7200000%2B00%3A00')&$orderby=updatedAt&$skip=0&$top=50&__includeDeleted=true&X-ARR-LOG-ID=c3bcf13e-b270-4d58-897f-58cfb9727e56 443 - 000.000.000. ZUMO/4.1+(lang=Managed;+os=iOS;+os_version=13.3;+arch=MacOSX;+version=4.1.2.0) - - xxxBACKENDxxx.azurewebsites.net 401 0 0 543 2249 4625

So it seems that setting a user doesn't have any effect.

Any ideas why I can't authenticate my MobileServiceClient?

Answer 1

I've found an answer here https://devblogs.microsoft.com/xamarin/personalized-experiences-with-azure-mobile-apps-authentication/

It's necessary to send a token in the header "Authorization". I've create a class used for HttpMessageHandler

public class AuthHandler : DelegatingHandler
{
    public IMobileServiceClient Client { get; set; }
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        if (Client.CurrentUser != null)
            request.Headers.Add("Authorization", "bearer " + Client.CurrentUser.MobileServiceAuthenticationToken);
        return base.SendAsync(request, cancellationToken);
    }
}

I use it for client initialization

var handlers = new AuthHandler();
client = new MobileServiceClient(App.BackendUrl, handlers);
handlers.Client = client;