Confused on how to get access tokens from B2C in Blazor App
I have created a sample application with OpenId Connect and Blazor (Server) for you here https://github.com/yberstad/BlazorAuth. It is uses a SameSiteCookie and OpenId Connect.
- In the appsettings.json, fill in your Authority, ClientId and ClientSecret.
- Configure the redirect URi in Azure to http://localhost:62438/signin-oidc/
- Start up the app in debug mode
- Got to http://localhost:62438/api/openidconnect/login
- Login with Azure
- Got to http://localhost:62438/api/openidconnect/user, having a break point in the OpenIdConnectController.GetUser action, there you can see how to getting hold of the access token.
How to get access and refresh token:
var accessToken = await HttpContext.GetTokenAsync("access_token");
var refreshToken = await HttpContext.GetTokenAsync("refresh_token");
SameSiteCookie Info: https://brockallen.com/2019/01/11/same-site-cookies-asp-net-core-and-external-authentication-providers/
Getting Access Token: http://docs.identityserver.io/en/latest/quickstarts/5_hybrid_and_api_access.html#using-the-access-token
Having the tokens stored in a SameSiteCookie makes it only visible for the server, hence not saving and exposing it in an unsafe environment on the client. A SameSiteCookie is also safe for XSS.
Hope this helps.
I was able to solve this myself. My AcquireTokenSilent call was failling because there was no users in the cache when I call it, so I had to make sure to add first entry to the cache when my user logs in. I was able to achieve this by configuring my auth as follows:
services.AddAuthentication(sharedOptions =>
{
sharedOptions.DefaultScheme = AzureADB2CDefaults.AuthenticationScheme;
sharedOptions.DefaultChallengeScheme = AzureADB2CDefaults.OpenIdScheme;
})
.AddAzureADB2C(options => Configuration.Bind("AzureAdB2C", options))
.AddCookie();
services.Configure<OpenIdConnectOptions>(AzureADB2CDefaults.OpenIdScheme, options =>
{
//Configuration.Bind("AzureAdB2C", options);
options.ResponseType = Microsoft.IdentityModel.Protocols.OpenIdConnect.OpenIdConnectResponseType.CodeIdToken;
options.Scope.Add("offline_access");
options.Scope.Add("https://mytenant.onmicrosoft.com/api/api.read.write");
options.SaveTokens = true;
options.GetClaimsFromUserInfoEndpoint = true;
options.Events.OnAuthorizationCodeReceived = async context =>
{
AzureADB2COptions opt = new AzureADB2COptions();
Configuration.Bind("AzureAdB2C", opt);
// As AcquireTokenByAuthorizationCodeAsync is asynchronous we want to tell ASP.NET core that we are handing the code
// even if it's not done yet, so that it does not concurrently call the Token endpoint. (otherwise there will be a
// race condition ending-up in an error from Azure AD telling "code already redeemed")
context.HandleCodeRedemption();
var code = context.ProtocolMessage.Code;
string signedInUserID = context.Principal.FindFirst(ClaimTypes.NameIdentifier).Value;
IConfidentialClientApplication cca = ConfidentialClientApplicationBuilder.Create(opt.ClientId)
.WithB2CAuthority(opt.Authority)
.WithRedirectUri(opt.RedirectUri)
.WithClientSecret(opt.ClientSecret)
.WithClientName("myWebapp")
.WithClientVersion("0.0.0.1")
.Build();
new MSALStaticCache(signedInUserID, context.HttpContext).EnablePersistence(cca.UserTokenCache);
try
{
AuthenticationResult result = await cca.AcquireTokenByAuthorizationCode(opt.ApiScopes.Split(' '), code)
.ExecuteAsync();
context.HandleCodeRedemption(result.AccessToken, result.IdToken);
}
catch (Exception)
{
}
};
});