Flutter app: How to implement a proper logout function? - azure

I have a flutter App using Azure B2C authentication. To achieve this I use the flutter appAuth package. The login process works fine but appAuth does not provide a logout functionality. After logging in I get an access token. Until now my logout was to delete this access token.
The problem is, that Azure require a web app session lifetime of at least 15 minutes in the SignIn user flow. This means: If a user logs in and out within 15 minutes, he will automatically be logged in again. This makes a login with another user impossible.
I hope to fix this behavior with a real logout instead of only deleting the access tokens. In found the following line of code in the Azure Active Directory documentation. But I cannot manage to get it running. Any suggestions for a logout function?
GET https://{tenant}.b2clogin.com/{tenant}.onmicrosoft.com/{policy}/oauth2/v2.0/logout?post_logout_redirect_uri=https%3A%2F%2Fjwt.ms%2F

I followed the below source to implement the below log out function using app auth written by David White.
Future<void> _logOut() async {
try {
//for some reason the API works differently on iOS and Android
Map<String, String> additionalParameters;
if (Platform.isAndroid) {
//works on Android but will miss p parameter when redirected back to authorize on iOS
additionalParameters = {
"id_token_hint": _idToken,
"post_logout_redirect_uri": _redirectUrl
};
} else if (Platform.isIOS) {
// with p parameter when redirected back to authorize on iOS
additionalParameters = {
"id_token_hint": _idToken,
"post_logout_redirect_uri": _redirectUrl,
'p': '<tenantID>'
};
}
await appAuth.authorizeAndExchangeCode(
AuthorizationTokenRequest(
_clientId,
_redirectUrl,
promptValues: ['login'],
discoveryUrl: _discoveryURL,
additionalParameters: additionalParameters,
scopes: _scopes,
),
);
} catch (e) {
print(e);
}
setState(() {
_jwt = null;
});
}
source: https://www.detroitdave.dev/2020/04/simple-azure-b2c-flutter.html

Related

How to configure Azure App Service (for Mobile) and B2C Authentication and access Azure SQL Database

I have a xamarin.forms mobile App using Microsoft.WindowsAzure.MobileServices and Microsoft.Identity.Client. Using EasyAuth I successfully got the xamarin mobile app to post data to the AzureSQL tables linked via connection string in the App Service configuration section. I use the local and offline sync methods of MobileServiceClient. I then attempted to change to B2C authentication. I setup a Tenant and under this tenant registered a new App as a native client called "MobileB2C". Redirect URIs were added automatically. I then created the signinsignup UserFlows.
Back to the Azure App Service (Mobile) under Authentication section I added a provider and selected the B2C App, MobileB2C. I did not populate the "allowed token audiences" field and Azure automatically created Client secret setting name "MICROSOFT_PROVIDER_AUTHENTICATION_SECRET" and the issuer URL.
So when I run the xamarin mobile app I can login via azure B2C and I can see that the authResult returns the users correct info along with UserIdentifier,aud, iss, sub, oid etc.
Once authResult is returned the xamarin mobile then tries to use the sync methods of MobileServiceClient to save data to the AzureSQL table. Its at this point that it fails. When the line await mClient.SyncContext.PushAsync().ConfigureAwait(false); is hit an error occurs described as Microsoft.WindowsAzure.MobileServices.Sync.MobileServicePushStatus.CancelledByAuthentication. I continued to try and confirgure the Azure back end differently and now I no linger get the CancelledByAuthentication error but instead get Microsoft.WindowsAzure.MobileServices.Sync.MobileServicePushStatus.CancelledByNetworkError.
The relevant xamarin mobile app code to implement the authentication and AzureSQL table update is as follows;
private B2CAuthenticationService()
{
// default redirectURI; each platform specific project will have to override it with its own
var builder = PublicClientApplicationBuilder.Create(B2CConstants.ClientID)
.WithB2CAuthority(B2CConstants.AuthoritySignInSignUp)
.WithIosKeychainSecurityGroup(B2CConstants.IOSKeyChainGroup)
.WithRedirectUri($"msal{B2CConstants.ClientID}://auth");
// Android implementation is based on https://github.com/jamesmontemagno/CurrentActivityPlugin
// iOS implementation would require to expose the current ViewControler - not currently implemented as it is not required
// UWP does not require this
var windowLocatorService = DependencyService.Get<IParentWindowLocatorService>();
if (windowLocatorService != null)
{
builder = builder.WithParentActivityOrWindow(() => windowLocatorService?.GetCurrentParentWindow());
}
_pca = builder.Build();
}
public async Task<UserContext> SignInAsync()
{
UserContext newContext;
try
{
// acquire token silent
newContext = await AcquireTokenSilent();
}
catch (MsalUiRequiredException)
{
// acquire token interactive
newContext = await SignInInteractively();
}
return newContext;
}
private async Task<UserContext> SignInInteractively()
{
AuthenticationResult authResult = await _pca.AcquireTokenInteractive(B2CConstants.Scopes)
.ExecuteAsync();
var newContext = UpdateUserInfo(authResult);
UserSingleton.Instance.UserId = newContext.UserIdentifier;
return newContext;
}
THe xamarin mobile app adds a record to the local database and then RefreshItemsAsync begins the synchronisation to the AzureSQL.
await azureService.AddUserSurveyAsync(newSurvey).ConfigureAwait(false);
await azureService.RefreshItemsAsync(true).ConfigureAwait(false);
It is at the PushAsync line below that the the code fails.
public async Task InitializeAsync()
{
using (await initializationLock.LockAsync())
{
if (!isInitialized)
{
mClient = new MobileServiceClient(https://mobileservice.azurewebsites.net);
// Define the offline store.
mStore = new MobileServiceSQLiteStore("mobile3.db");
mStore.DefineTable<UserSurvey>();
await mClient.SyncContext.InitializeAsync(mStore, new MobileServiceSyncHandler()).ConfigureAwait(false);
UserSurveyTable = mClient.GetSyncTable<UserSurvey>();
isInitialized = true;
}
}
}
public async Task RefreshItemsAsync(bool syncItems)
{
if (syncItems)
{
await SynchronizeAsync().ConfigureAwait(false);
}
}
public async Task SynchronizeAsync()
{
await InitializeAsync().ConfigureAwait(false);
IReadOnlyCollection<MobileServiceTableOperationError> syncErrors = null;
if (!CrossConnectivity.Current.IsConnected)
return;
try
{
await mClient.SyncContext.PushAsync().ConfigureAwait(false);
await UserSurveyTable.PullAsync("usersurveys", UserSurveyTable.CreateQuery()).ConfigureAwait(false);
}
catch (MobileServicePushFailedException error)
{
if (error.PushResult != null)
{
foreach (var result in error.PushResult.Errors)
{
await ResolveError(result);
}
}
}
}
What is wrong with the Azure back end configuration or perhaps I'm missing code as I can't understand how the xamarin mobile app can then attempt to communicate with the Azure Mobile App Service and AzureSQL as I don't send any token with those lines of code for PushAsync etc or perhaps this is abstracted away?
Here are images of the exceptions;
enter image description here
enter image description here
As promised, here is the succinct version of AAD authentication. For your purposes, B2C authentication is the same as AAD authentication.
There are two application definitions at play here - one for the mobile application (which basically says "this person is authenticated"), and one for the service (which says "a token authenticated for this mobile application can access this service"). So, you create an application ID for your mobile application, and an application ID for your service, and then you configure the service application ID to accept the mobile application.
The "WPF" tutorial for Azure Mobile Apps gives the general overview, although it's for WPF instead of Xamarin. The pieces you need are all the same.
The "WPF" tutorial here: https://learn.microsoft.com/en-us/azure/developer/mobile-apps/azure-mobile-apps/quickstarts/wpf/authentication

ADB2C How to share user token between two different applications?

I would like to achieve this:
I have two applications using adb2c for authentication. I would like a user to be able to sign in interactively in the first application and then be logged in silently in the second application.
What I have for now:
Both applications are registered in Azure environment, with two different client id.
Both applications share the exact same code, same cache and same configuration, except for the client id.
I am coding in C# and using the Microsoft.Identity.Client dll .
My issue is:
If I use the same client id for both applications (as if they were registered as a single application), the user can sign interactively in one application and then be logged in silently in the second one.
But, if I use two different client id, it is no longer working. If the user first signed in interactively in application 1, when I call GetAccountsAsync() in application 2 to get the user account in cache, it returns no account.
My code:
To acquire token interactively:
private async Task<AuthenticationResult> AcquireTokenInteractiveAsync()
{
try
{
AuthenticationResult ar = await pubClientApp.AcquireTokenInteractive(config.ApiScopes).WithB2CAuthority(config.GetAuthoritySignUpSignIn()).WithExtraQueryParameters(ui_locale).ExecuteAsync();
return ar;
}
catch (MsalException ex)
{
}
catch (Exception ex)
{
}
return null;
}
 
To acquire token silently:
private async Task<AuthenticationResult> AcquireTokenSilentAsync()
{
try
{
var accounts = await pubClientApp.GetAccountsAsync();
if (accounts.Count() > 0)
{
AuthenticationResult ar = await pubClientApp.AcquireTokenSilent(config.ApiScopes,accounts.FirstOrDefault()).ExecuteAsync();
return ar;
}
}
catch (Exception ex)
{
}
return null;
}
Thanks for your help :)
You cannot share tokens between the apps, what your observe is expected.
You have to acquire a token interactively on the second app once a silent call fails, and the interactive flow will rely on AAD B2C session cookies to give the user Single Sign On.
You can read about sessions and single sign on here:
https://learn.microsoft.com/en-us/azure/active-directory-b2c/session-behavior?pivots=b2c-custom-policy

How to enable Windows Authentication with in-process IIS hosting under IdentityServer4?

My ASP.Net Core MVC app accesses a .Net Core API through IdentityServer. It works fine on IIS server running in-process with Entity Framework based identity store. Now I am trying to enable Windows Authentication and getting stuck here.
What I tried is following the identityserver doc section "Windows Authentication" - I added the code below to the ConfigureServices of my IdentityServer's Startup.cs
// configures IIS in-proc settings
services.Configure<IISServerOptions>(iis =>
{
iis.AuthenticationDisplayName = "Windows";
iis.AutomaticAuthentication = false;
});
I also enabled the Windows Authentication in IIS for my API app
The part of the doc that I am confused about is "You trigger Windows authentication by calling ChallengeAsync on the Windows scheme". It doesn't mention where you do that. I am assuming it is in identityserver and I put the code in the Login method of the AccountController of the identityserver as bellow.
/// <summary>
/// Entry point into the login workflow
/// </summary>
[HttpGet]
public async Task<IActionResult> Login(string returnUrl)
{
// trigger Windows authentication by calling ChallengeAsync
await ChallengeWindowsAsync(returnUrl);
// build a model so we know what to show on the login page
var vm = await BuildLoginViewModelAsync(returnUrl);
if (vm.IsExternalLoginOnly)
{
// we only have one option for logging in and it's an external provider
return RedirectToAction("Challenge", "External", new { scheme = vm.ExternalLoginScheme, returnUrl });
}
return View(vm);
}
private async Task<IActionResult> ChallengeWindowsAsync(string returnUrl)
{
// see if windows auth has already been requested and succeeded
var result = await HttpContext.AuthenticateAsync("Windows");
if (result?.Principal is WindowsPrincipal wp)
{
// we will issue the external cookie and then redirect the
// user back to the external callback, in essence, treating windows
// auth the same as any other external authentication mechanism
var props = new AuthenticationProperties()
{
RedirectUri = Url.Action("Callback"),
Items =
{
{ "returnUrl", returnUrl },
{ "scheme", "Windows" },
}
};
var id = new ClaimsIdentity("Windows");
// the sid is a good sub value
id.AddClaim(new Claim(JwtClaimTypes.Subject, wp.FindFirst(ClaimTypes.PrimarySid).Value));
// the account name is the closest we have to a display name
id.AddClaim(new Claim(JwtClaimTypes.Name, wp.Identity.Name));
// add the groups as claims -- be careful if the number of groups is too large
var wi = wp.Identity as WindowsIdentity;
// translate group SIDs to display names
var groups = wi.Groups.Translate(typeof(NTAccount));
var roles = groups.Select(x => new Claim(JwtClaimTypes.Role, x.Value));
id.AddClaims(roles);
await HttpContext.SignInAsync(
IdentityServerConstants.ExternalCookieAuthenticationScheme,
new ClaimsPrincipal(id),
props);
return Redirect(props.RedirectUri);
}
else
{
// trigger windows auth
// since windows auth don't support the redirect uri,
// this URL is re-triggered when we call challenge
return Challenge("Windows");
}
}
What I expect to happen, if everything goes well, is that the authentication happens automatically (without a login box?) because the "Challenge" call will require the client side (the browser) to send in Windows identity info and a token will be issued based on that.
It doesn't seem to work that way now - I am getting an Unauthorized error from API when starting the MVC app:
Am I doing that in the wrong place? Or am I missing something else?

Spotify node web api - trouble with multiple users

I am working on an app that uses Spotify Node web API and having trouble when multiple users login into my application. I am successfully able to go through authentication flow and get the tokens and user ID after a user logs in. I am using the Authorization Code to authorize user (since I would like to get refresh tokens after expiration). However, the current problem is that getUserPlaylists function described here (FYI, if the first argument is undefined, it will return the playlists of the authenticated user) returns playlists of the most recently authenticated user instead of the user currently using the app.
Example 1: if user A logins in to the application, it will get its playlists fine. If user B logins in to the application, it also sees its own playlists. BUT, if user A refreshes the page, user A sees the playlists of the user B (instead of its own, user A playlists).
Example 2: user A logs in, user B can see user A's playlists just by going to the app/myplaylists route.
My guess is, the problem is with this section of the code
spotifyApi.setAccessToken(access_token);
spotifyApi.setRefreshToken(refresh_token);
The latest user tokens override whatever user was before it and hence the previous user is losing grants to do actions such as viewing its own playlists.
Expected behavior: user A sees own playlists after user B logs in event after refreshing the page.
Actual behavior: user A sees user B's playlists after user B logged in and user A refreshes the page.
I am aware that I could use the tokens without using the Spotify Node API
and just use the tokens to make requests and it should probably be fine, however, it would be great to still be able to use the Node API and to handle multiple users.
Here is the portion of code that most likely has problems:
export const createAuthorizeURL = (
scopes = SCOPE_LIST,
state = 'spotify-auth'
) => {
const authUrl = spotifyApi.createAuthorizeURL(scopes, state);
return {
authUrl,
...arguments
};
};
export async function authorizationCodeGrant(code) {
let params = {
clientAppURL: `${APP_CLIENT_URL || DEV_HOST}/app`
};
try {
const payload = await spotifyApi.authorizationCodeGrant(code);
const { body: { expires_in, access_token, refresh_token } } = payload;
spotifyApi.setAccessToken(access_token);
spotifyApi.setRefreshToken(refresh_token);
params['accessToken'] = access_token;
params['refreshToken'] = refresh_token;
return params;
} catch (error) {
return error;
}
return params;
}
export async function getMyPlaylists(options = {}) {
try {
// if undefined, should return currently authenticated user
return await spotifyApi.getUserPlaylists(undefined, options);
} catch (error) {
return error;
}
}
Would appreciate any help on this. I am really excited about what I am making so it would mean a LOT if someone could help me find the issue...
You're on the right track. When you set your access token and refresh token, though, you're setting it for your entire application, and all users who call your server will use it. Not ideal.
Here's a working example of the Authorization Code Flow in Node: https://glitch.com/edit/#!/spotify-authorization-code
As you can see, it uses a general instance of SpotifyWebApi to handle authentication, but it instantiates a new loggedInSpotifyApi for every request to user data, so you get the data for the user who's asking for it.
If you want to use the above example, you can just start editing to "remix" and create your own copy of the project.
Happy hacking!

How to enable App Service Mobile App SSO for UWP

I am building a Universal Windows Platform (UWP) app that uses the Azure App Service Mobile App backend as well as the user's OneDrive account. I have 2 requirements for authentication:
If the user is logged in to their UWP device with a Microsoft account (e.g. Windows 10) then I don't want them to be presented with a login prompt (i.e. Single Sign On, re-using their Microsoft account credentials).
I want to have a single authentication event across Azure & OneDrive, i.e. the user authorises once and I re-use that token for both services.
I did this in Windows Phone 8 with an Azure Mobile Service by logging in with the Live SDK and then passing the returned token to the MobileServiceClient.LoginAsync() method, however I can't get this to work in UWP with an Azure Mobile App. When I call that same method I receive a 401 Unauthorised response.
I have associated my UWP app with the store and set up the
application at the Microsoft Account Developer Centre, including
adding the redirect URI from the Azure Mobile App.
I have set up the Azure App Service Mobile App, including adding the
Client ID & Secret from the Microsoft Account Developer Centre.
I have tried numerous ways to retrieve the token, including the
OnlineIdAuthenticator, WebAuthenticationCoreManager and
WebAuthenticationBroker. None has worked so far.
I currently use the following code in a class LiveAuthenticationService to retrieve an access token:
public async Task<bool> LoginAsync()
{
AccessToken = null;
bool success = false;
OnlineIdAuthenticator onlineIdAuthenticator = new OnlineIdAuthenticator();
EventWaitHandle waithandle = new ManualResetEvent(false);
OnlineIdServiceTicketRequest serviceTicketRequest = new OnlineIdServiceTicketRequest(scopes, "DELEGATION");
UserIdentity result = await onlineIdAuthenticator.AuthenticateUserAsync(serviceTicketRequest);
if (!string.IsNullOrWhiteSpace(result?.Tickets[0]?.Value))
{
currentUserId = result.SafeCustomerId;
AccessToken = result.Tickets[0].Value;
success = true;
waithandle.Set();
}
else
{
await logger.LogErrorAsync("Error signing in to Microsoft Live",
new Dictionary<string, string> { { "errorCode", result?.Tickets[0]?.ErrorCode.ToString() } });
}
waithandle.WaitOne(10000); //10 second timeout
return success;
}
And then this to attempt to login to my Azure Mobile App with that token, which uses LiveAuthenticationService from above:
private async Task RefreshUserIdAndAccessToken()
{
try
{
var tcs = new TaskCompletionSource<MobileServiceUser>();
var authService = new LiveAuthenticationService();
await UiDispatcher.RunAsync(CoreDispatcherPriority.Normal,
async () =>
{
try
{
await authService.LoginAsync();
var jsonAuthenticationToken = JObject.Parse(#"{""authenticationToken"": """ + authService.AccessToken + #"""}");
tcs.SetResult(await mobileService.LoginAsync(MobileServiceAuthenticationProvider.MicrosoftAccount, jsonAuthenticationToken));
}
catch (Exception ex)
{
tcs.SetException(ex);
}
});
var user = await tcs.Task;
currentUserId = user.UserId;
AccessToken = user.MobileServiceAuthenticationToken;
}
catch (Exception ex)
{
await logger.LogExceptionAsync(ex,
Constants.LOGGING_DATAKEY_REFRESHACCESSTOKENFAILURE,
currentUserId);
currentUserId = null;
AccessToken = null;
}
}
As stated this results in a 401 Unauthorised response from Azure. I have run Fiddler and the request seems to be correct, the expected authentication token is included in a JSON payload with the request.
UPDATE
One thing I can see is that the token issued by the code above is almost 900 characters long, all in the form YnElFkAAcK8bRSQab/FK+PT5n/wA4CPU..., while the token issued if I let Azure Mobile App handle the authentication, i.e. call MobileServiceClient.LoginAsync() without passing a token, is only about 350 characters long and in the form hbGciOi.eyJmdWWxsIiwiRGJn... (notice the period towards the beginning).
This issue is really causing me problems now. I can't release the app without the authentication working and I can't figure out how to fix it. Any help will be appreciated.
This was a tough one for me to solve as I was facing this problem too.
The most important part is the OnlineIdServiceTicketRequest the request should look like this:
var mobileServicesTicket = new OnlineIdServiceTicketRequest("https://yourmobileservice.azure-mobile.net/", "JWT");
Note that we are specifying your endpoint and also requesting a JWT token instead of delegation. This will get the 350ish character token you were looking for.
Here is a full code sample of what I'm doing:
public async Task<bool> LoginAsync()
{
var authenticator = new Windows.Security.Authentication.OnlineId.OnlineIdAuthenticator();
var mobileServicesTicket = new Windows.Security.Authentication.OnlineId.OnlineIdServiceTicketRequest("https://yourendpoint.azure-mobile.net/", "JWT");
var ticketRequests = new List<OnlineIdServiceTicketRequest>() { mobileServicesTicket };
var authResult = await authenticator.AuthenticateUserAsync(ticketRequests, CredentialPromptType.PromptIfNeeded);
if ((authResult.Tickets.Count == 1) && (authResult.Tickets[0].ErrorCode == 0))
{
var accessToken = authResult.Tickets[0];
var res = await _mobileServiceClient.LoginWithMicrosoftAccountAsync(accessToken.Value);
return true;
}
else
{
return false;
}
}
_mobileServiceClient is injected into the class and is a reference to Microsoft.WindowsAzure.MobileServices.MobileServiceClient object within the WindowsAzure.MobileServices library.
I actually ended up writing a blog article about this problem here http://jshapland.com/single-sign-on-with-azure-mobile-services-in-a-uwp-app/

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