Add accessor for current principal

samples/BlazorServer/HostingExtensions.cs

@@ -1,6 +1,5 @@
 using BlazorServer.Plumbing;
 using BlazorServer.Services;
-using Duende.AccessTokenManagement.OpenIdConnect;
 using Serilog;
 
 namespace BlazorServer;
@@ -50,27 +49,24 @@ public static WebApplication ConfigureServices(this WebApplicationBuilder builde
             });
 
         // adds access token management
-        builder.Services.AddOpenIdConnectAccessTokenManagement();
+        builder.Services.AddOpenIdConnectAccessTokenManagement()
+            .AddBlazorServerAccessTokenManagement<ServerSideTokenStore>();
 
         // register events to customize authentication handlers
         builder.Services.AddTransient<CookieEvents>();
         builder.Services.AddTransient<OidcEvents>();
 
-        // not allowed to programmatically use HttpContext in Blazor Server.
-        // that's why tokens cannot be managed in the login session
-        builder.Services.AddSingleton<IUserTokenStore, ServerSideTokenStore>();
-
         // registers HTTP client that uses the managed user access token
         builder.Services.AddTransient<RemoteApiService>();
-        builder.Services.AddHttpClient<RemoteApiService>(client =>
+        builder.Services.AddUserAccessTokenHttpClient("demoApiClient", configureClient: client =>
         {
             client.BaseAddress = new Uri("https://demo.duendesoftware.com/api/");
         });
 
         builder.Services.AddControllersWithViews();
         builder.Services.AddRazorPages();
         builder.Services.AddServerSideBlazor();
-        
+
         builder.Services.AddSingleton<WeatherForecastService>();
 
         return builder.Build();

samples/BlazorServer/Plumbing/ServerSideTokenStore.cs

@@ -9,7 +9,7 @@ namespace BlazorServer.Plumbing;
 
 /// <summary>
 /// Simplified implementation of a server-side token store.
-/// Probably want somehting more robust IRL
+/// Probably want something more robust IRL
 /// </summary>
 public class ServerSideTokenStore : IUserTokenStore
 {

samples/BlazorServer/Services/RemoteApiService.cs

@@ -2,45 +2,25 @@
 // Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
 
 using System.Text.Json;
-using Duende.AccessTokenManagement.OpenIdConnect;
-using IdentityModel.Client;
-using Microsoft.AspNetCore.Components.Authorization;
 
 namespace BlazorServer.Services;
 
 public class RemoteApiService
 {
     private readonly HttpClient _client;
-    private readonly AuthenticationStateProvider _authenticationStateProvider;
-    private readonly IUserTokenManagementService _tokenManagementService;
 
     public RemoteApiService(
-        HttpClient client,
-        AuthenticationStateProvider authenticationStateProvider,
-        IUserTokenManagementService tokenManagementService)
+        IHttpClientFactory factory)
     {
-        _client = client;
-        _authenticationStateProvider = authenticationStateProvider;
-        _tokenManagementService = tokenManagementService;
+        _client = factory.CreateClient("demoApiClient");
     }
 
     private record Claim(string type, object value);
 
     public async Task<string> GetData()
     {
-        var request = new HttpRequestMessage(HttpMethod.Get, "test");
-        var response = await SendRequestAsync(request);
-
-        var json = JsonSerializer.Deserialize<IEnumerable<Claim>>(await response.Content.ReadAsStringAsync());
+        var response = await _client.GetStringAsync("test");
+        var json = JsonSerializer.Deserialize<IEnumerable<Claim>>(response);
         return JsonSerializer.Serialize(json, new JsonSerializerOptions { WriteIndented = true });
     }
-
-    private async Task<HttpResponseMessage> SendRequestAsync(HttpRequestMessage request)
-    {
-        var state = await _authenticationStateProvider.GetAuthenticationStateAsync();
-        var token = await _tokenManagementService.GetAccessTokenAsync(state.User);
-
-        request.SetToken(token.AccessTokenType!, token.AccessToken!);
-        return  await _client.SendAsync(request);
-    }
 }

samples/BlazorServer/Shared/RedirectToLogin.razor

@@ -1,9 +1,12 @@
 @inject NavigationManager Navigation
 
 @code {
-    protected override void OnInitialized()
+    // Using the async method prevents NavigationExceptions, even though this method is synchronous
+    #pragma warning disable CS1998 
+    protected override async Task OnInitializedAsync()
     {
         var returnUrl = Uri.EscapeDataString("/" + Navigation.ToBaseRelativePath(Navigation.Uri));
         Navigation.NavigateTo($"account/login?returnUrl={returnUrl}", forceLoad: true);
     }
+    #pragma warning restore CS1998
 }

src/Duende.AccessTokenManagement.OpenIdConnect/BlazorServerPrincipalAccessor.cs

@@ -0,0 +1,55 @@
+// Copyright (c) Brock Allen & Dominick Baier. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+using Microsoft.AspNetCore.Components.Authorization;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using System.Security.Claims;
+using System.Threading.Tasks;
+
+namespace Duende.AccessTokenManagement.OpenIdConnect;
+
+/// <summary>
+/// Accesses the current user from blazor server.  
+/// </summary>
+/// <remarks>
+/// ctor
+/// </remarks>
+public class BlazorServerUserAccessor(
+    // We use the CircuitServicesAccessor to resolve the
+    // AuthenticationStateProvider, rather than injecting it. Injecting the
+    // state provider directly doesn't work here, because this service might be
+    // called in a non-blazor DI scope.
+    CircuitServicesAccessor circuitServicesAccessor, 
+    IHttpContextAccessor? httpContextAccessor,
+    ILogger<BlazorServerUserAccessor> logger) : IUserAccessor
+{
+
+    /// <inheritdoc/>
+    public async Task<ClaimsPrincipal> GetCurrentUserAsync()
+    {
+        var authStateProvider = circuitServicesAccessor.Services?
+            .GetService<AuthenticationStateProvider>();
+        // If we are in blazor server (streaming over a circuit), this provider will be non-null
+        if (authStateProvider != null)
+        {
+            var authState = await authStateProvider.GetAuthenticationStateAsync();
+            return authState.User;
+        }
+        // Otherwise, we should be in an SSR scenario, and the httpContext should be available
+        else if(httpContextAccessor?.HttpContext != null)
+        {
+            return httpContextAccessor.HttpContext.User;
+        }
+        // If we are in neither blazor server or SSR, something weird is going on.
+        else
+        {
+            logger.LogWarning("Neither an authentication state provider or http context are available to obtain the current principal.");
+            return new ClaimsPrincipal();
+        }
+    }
+
+}
+
+

src/Duende.AccessTokenManagement.OpenIdConnect/CircuitServicesAccessor.cs

@@ -0,0 +1,64 @@
+// Copyright (c) Brock Allen & Dominick Baier. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Components.Server.Circuits;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Duende.AccessTokenManagement.OpenIdConnect;
+
+// This code is from the blazor documentation:
+// https://learn.microsoft.com/en-us/aspnet/core/blazor/fundamentals/dependency-injection?view=aspnetcore-8.0#access-server-side-blazor-services-from-a-different-di-scope
+
+/// <summary>
+/// Provides access to scoped blazor services from non-blazor DI scopes, such as
+/// scopes created using IHttpClientFactory.
+/// </summary>
+public class CircuitServicesAccessor
+{
+    static readonly AsyncLocal<IServiceProvider> blazorServices = new();
+
+    internal IServiceProvider? Services
+    {
+        get => blazorServices.Value;
+        set => blazorServices.Value = value!;
+    }
+}
+
+internal class ServicesAccessorCircuitHandler : CircuitHandler
+{
+    readonly IServiceProvider services;
+    readonly CircuitServicesAccessor circuitServicesAccessor;
+
+    internal ServicesAccessorCircuitHandler(IServiceProvider services, 
+        CircuitServicesAccessor servicesAccessor)
+    {
+        this.services = services;
+        this.circuitServicesAccessor = servicesAccessor;
+    }
+
+    public override Func<CircuitInboundActivityContext, Task> CreateInboundActivityHandler(
+        Func<CircuitInboundActivityContext, Task> next)
+    {
+        return async context =>
+        {
+            circuitServicesAccessor.Services = services;
+            await next(context);
+            circuitServicesAccessor.Services = null;
+        };
+    }
+}
+
+internal static class CircuitServicesServiceCollectionExtensions
+{
+    public static IServiceCollection AddCircuitServicesAccessor(
+        this IServiceCollection services)
+    {
+        services.AddScoped<CircuitServicesAccessor>();
+        services.AddScoped<CircuitHandler, ServicesAccessorCircuitHandler>();
+
+        return services;
+    }
+}

src/Duende.AccessTokenManagement.OpenIdConnect/HttpContextPrincipalAccessor.cs

@@ -0,0 +1,30 @@
+// Copyright (c) Brock Allen & Dominick Baier. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+using Microsoft.AspNetCore.Http;
+using System.Security.Claims;
+using System.Threading.Tasks;
+
+namespace Duende.AccessTokenManagement.OpenIdConnect;
+
+/// <summary>
+/// Accesses the current principal based on the HttpContext.User.
+/// </summary>
+public class HttpContextUserAccessor : IUserAccessor
+{
+    private readonly IHttpContextAccessor _httpContextAccessor;
+
+    /// <summary>
+    /// ctor
+    /// </summary>
+    public HttpContextUserAccessor(IHttpContextAccessor httpContextAccessor)
+    {
+        _httpContextAccessor = httpContextAccessor;
+    }
+
+    /// <inheritdoc/>
+    public Task<ClaimsPrincipal> GetCurrentUserAsync()
+    {
+        return Task.FromResult(_httpContextAccessor.HttpContext?.User ?? new ClaimsPrincipal());
+    }
+}

src/Duende.AccessTokenManagement.OpenIdConnect/IPrincipalAccessor.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Brock Allen & Dominick Baier. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+using System.Security.Claims;
+using System.Threading.Tasks;
+
+namespace Duende.AccessTokenManagement.OpenIdConnect;
+
+/// <summary>
+/// Service that retrieves the current principal.
+/// </summary>
+public interface IUserAccessor
+{
+    /// <summary>
+    /// Gets the current user.
+    /// </summary>
+    Task<ClaimsPrincipal> GetCurrentUserAsync();
+}

src/Duende.AccessTokenManagement.OpenIdConnect/OpenIdConnectTokenManagementServiceCollectionExtensions.cs

@@ -5,7 +5,6 @@
 using System.Net.Http;
 using Duende.AccessTokenManagement;
 using Duende.AccessTokenManagement.OpenIdConnect;
-using Microsoft.AspNetCore.Authentication.OpenIdConnect;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.Extensions.Logging;
@@ -35,13 +34,38 @@ public static IServiceCollection AddOpenIdConnectAccessTokenManagement(this ISer
 
         services.TryAddTransient<IUserTokenManagementService, UserAccessAccessTokenManagementService>();
         services.TryAddTransient<IOpenIdConnectConfigurationService, OpenIdConnectConfigurationService>();
-        // scoped since it will be caching per-request authentication results
-        services.TryAddScoped<IUserTokenStore, AuthenticationSessionUserAccessTokenStore>();
         services.TryAddSingleton<IUserTokenRequestSynchronization, UserTokenRequestSynchronization>();
         services.TryAddTransient<IUserTokenEndpointService, UserTokenEndpointService>();
 
         services.ConfigureOptions<ConfigureOpenIdConnectOptions>();
 
+        // By default, we assume that we are in a traditional web application
+        // where we can use the http context. The services below depend on http
+        // context, and we register different ones in blazor
+
+        services.TryAddScoped<IUserAccessor, HttpContextUserAccessor>();
+        // scoped since it will be caching per-request authentication results
+        services.TryAddScoped<IUserTokenStore, AuthenticationSessionUserAccessTokenStore>();
+
+        return services;
+    }
+
+    /// <summary>
+    /// Adds implementations of services that enable access token management in
+    /// Blazor Server.
+    /// </summary>
+    /// <typeparam name="TTokenStore">An IUserTokenStore implementation. Blazor
+    /// Server requires an IUserTokenStore because the default token store
+    /// relies on cookies, which are not present when streaming updates over a
+    /// blazor circuit. </typeparam>
+    public static IServiceCollection AddBlazorServerAccessTokenManagement<TTokenStore>(this IServiceCollection services)
+        where TTokenStore : class, IUserTokenStore
+    {
+        services.AddSingleton<IUserTokenStore, TTokenStore>();
+        services.AddScoped<IUserAccessor, BlazorServerUserAccessor>();
+        services.AddCircuitServicesAccessor();
+        services.AddHttpContextAccessor(); // For SSR
+
         return services;
     }
 
@@ -143,10 +167,12 @@ public static IHttpClientBuilder AddUserAccessTokenHandler(
         {
             var dpopService = provider.GetRequiredService<IDPoPProofService>();
             var dpopNonceStore = provider.GetRequiredService<IDPoPNonceStore>();
-            var contextAccessor = provider.GetRequiredService<IHttpContextAccessor>();
+            var userTokenManagement = provider.GetRequiredService<IUserTokenManagementService>();
             var logger = provider.GetRequiredService<ILogger<OpenIdConnectClientAccessTokenHandler>>();
+            var principalAccessor = provider.GetRequiredService<IUserAccessor>();
 
-            return new OpenIdConnectUserAccessTokenHandler(dpopService, dpopNonceStore, contextAccessor, logger, parameters);
+            return new OpenIdConnectUserAccessTokenHandler(
+                dpopService, dpopNonceStore, principalAccessor, userTokenManagement, logger, parameters);
         });
     }