[backend/signalr] Add authentication & authorization (ISH-244)

Iceshrimp.Backend/Core/Extensions/ServiceExtensions.cs

@@ -9,6 +9,8 @@ using Iceshrimp.Backend.Core.Federation.WebFinger;
 using Iceshrimp.Backend.Core.Helpers.LibMfm.Conversion;
 using Iceshrimp.Backend.Core.Middleware;
 using Iceshrimp.Backend.Core.Services;
+using Iceshrimp.Backend.Hubs.Authentication;
+using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.DataProtection;
 using Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption;
 using Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ConfigurationModel;
@@ -16,6 +18,8 @@ using Microsoft.AspNetCore.RateLimiting;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.OpenApi.Models;
+using AuthenticationMiddleware = Iceshrimp.Backend.Core.Middleware.AuthenticationMiddleware;
+using AuthorizationMiddleware = Iceshrimp.Backend.Core.Middleware.AuthorizationMiddleware;
 using NoteRenderer = Iceshrimp.Backend.Controllers.Renderers.NoteRenderer;
 using NotificationRenderer = Iceshrimp.Backend.Controllers.Renderers.NotificationRenderer;
 using UserRenderer = Iceshrimp.Backend.Controllers.Renderers.UserRenderer;
@@ -242,4 +246,23 @@ public static class ServiceExtensions
 			});
 		});
 	}
+
+	public static void AddAuthorizationPolicies(this IServiceCollection services)
+	{
+		services.AddAuthorizationBuilder()
+		        .AddPolicy("HubAuthorization", policy =>
+		        {
+			        policy.Requirements.Add(new HubAuthorizationRequirement());
+			        policy.AuthenticationSchemes = ["HubAuthenticationScheme"];
+		        });
+
+		services.AddAuthentication(options =>
+		{
+			options.AddScheme<HubAuthenticationHandler>("HubAuthenticationScheme", null);
+			
+			// Add a stub authentication handler to bypass strange ASP.NET Core >=7.0 defaults
+			// Ref: https://github.com/dotnet/aspnetcore/issues/44661
+			options.AddScheme<IAuthenticationHandler>("StubAuthenticationHandler", null);
+		});
+	}
 }

Iceshrimp.Backend/Core/Services/UserService.cs

@@ -506,6 +506,9 @@ public class UserService(
 	{
 		UpdateUserLastActive(session.User);
 
+		if (session.LastActiveDate != null && session.LastActiveDate > DateTime.UtcNow - TimeSpan.FromMinutes(5))
+			return;
+
 		_ = followupTaskSvc.ExecuteTask("UpdateSessionMetadata", async provider =>
 		{
 			var bgDb = provider.GetRequiredService<DatabaseContext>();
@@ -516,7 +519,8 @@ public class UserService(
 
 	private void UpdateUserLastActive(User user)
 	{
-		if (user.LastActiveDate != null && user.LastActiveDate > DateTime.UtcNow - TimeSpan.FromHours(1)) return;
+		if (user.LastActiveDate != null && user.LastActiveDate > DateTime.UtcNow - TimeSpan.FromMinutes(5))
+			return;
 
 		_ = followupTaskSvc.ExecuteTask("UpdateUserLastActive", async provider =>
 		{

Iceshrimp.Backend/Hubs/Authentication/AuthenticationHelpers.cs

@@ -0,0 +1,99 @@
+using System.Security.Claims;
+using System.Text.Encodings.Web;
+using Iceshrimp.Backend.Core.Database;
+using Iceshrimp.Backend.Core.Middleware;
+using Iceshrimp.Backend.Core.Services;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.AspNetCore.Authentication.BearerToken;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Options;
+
+namespace Iceshrimp.Backend.Hubs.Authentication;
+
+public class HubAuthorizationRequirement : IAuthorizationRequirement;
+
+public class HubAuthenticationHandler(
+	IOptionsMonitor<BearerTokenOptions> options,
+	ILoggerFactory logger,
+	UrlEncoder encoder,
+	DatabaseContext db,
+	UserService userSvc
+) : AuthenticationHandler<AuthenticationSchemeOptions>(options, logger, encoder)
+{
+	protected override async Task<AuthenticateResult> HandleAuthenticateAsync()
+	{
+		string token;
+		if (Request.Query.ContainsKey("access_token"))
+		{
+			token = Request.Query["access_token"].ToString();
+		}
+		else
+		{
+			var header = Request.Headers.Authorization.ToString();
+			if (!header.ToLowerInvariant().StartsWith("bearer "))
+				return AuthenticateResult.NoResult();
+
+			token = header[7..];
+		}
+
+		var session = await db.Sessions
+		                      .Include(p => p.User.UserProfile)
+		                      .Include(p => p.User.UserSettings)
+		                      .FirstOrDefaultAsync(p => p.Token == token && p.Active);
+
+		if (session is not { Active: true })
+			return AuthenticateResult.NoResult();
+
+		var claims   = new[] { new Claim("token", token), new Claim("userId", session.UserId) };
+		var identity = new ClaimsIdentity(claims, nameof(HubAuthenticationHandler));
+		var ticket   = new AuthenticationTicket(new ClaimsPrincipal(identity), Scheme.Name);
+		userSvc.UpdateSessionMetadata(session);
+		Context.SetSession(session);
+		return AuthenticateResult.Success(ticket);
+	}
+}
+
+public class HubAuthorizationHandler(
+	IHttpContextAccessor httpContextAccessor
+) : AuthorizationHandler<HubAuthorizationRequirement>
+{
+	protected override Task HandleRequirementAsync(
+		AuthorizationHandlerContext context, HubAuthorizationRequirement requirement
+	)
+	{
+		var ctx = httpContextAccessor.HttpContext;
+		if (ctx == null)
+			throw new Exception("HttpContext must not be null at this stage");
+
+		if (ctx.GetUser() == null)
+			context.Fail(new AuthorizationFailureReason(this, "Unauthorized"));
+		else
+			context.Succeed(requirement);
+
+		return Task.CompletedTask;
+	}
+}
+
+public class HubUserIdProvider(IHttpContextAccessor httpContextAccessor) : IUserIdProvider
+{
+	public string GetUserId(HubConnectionContext connection)
+	{
+		if (httpContextAccessor.HttpContext == null)
+			throw new Exception("HttpContext must not be null at this stage");
+
+		return httpContextAccessor.HttpContext.GetUserOrFail().Id;
+	}
+}
+
+public static class AuthenticationServiceExtensions
+{
+	public static void AddAuthenticationServices(this IServiceCollection services)
+	{
+		services.AddScoped<IAuthenticationHandler, HubAuthenticationHandler>()
+		        .AddSingleton<IAuthorizationHandler, HubAuthorizationHandler>()
+		        .AddSingleton<IHttpContextAccessor, HttpContextAccessor>()
+		        .AddSingleton<IUserIdProvider, HubUserIdProvider>();
+	}
+}

Iceshrimp.Backend/Hubs/StreamingHub.cs

@@ -0,0 +1,13 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.SignalR;
+
+namespace Iceshrimp.Backend.Hubs;
+
+[Authorize(Policy = "HubAuthorization")]
+public class StreamingHub : Hub
+{
+	public async Task SendMessage(string user, string message)
+	{
+		await Clients.All.SendAsync("ReceiveMessage", "SignalR", "ping!");
+	}
+}

Iceshrimp.Backend/Startup.cs

@@ -1,5 +1,6 @@
 using Iceshrimp.Backend.Core.Extensions;
 using Iceshrimp.Backend.Hubs;
+using Iceshrimp.Backend.Hubs.Authentication;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -17,6 +18,8 @@ builder.Services.AddLogging(logging => logging.AddCustomConsoleFormatter());
 builder.Services.AddDatabaseContext(builder.Configuration);
 builder.Services.AddSlidingWindowRateLimiter();
 builder.Services.AddCorsPolicies();
+builder.Services.AddAuthorizationPolicies();
+builder.Services.AddAuthenticationServices();
 builder.Services.AddSignalR().AddMessagePackProtocol();
 builder.Services.AddResponseCompression();
 
@@ -50,6 +53,7 @@ app.UseCustomMiddleware();
 app.MapControllers();
 app.MapFallbackToController("/api/{**slug}", "FallbackAction", "Fallback");
 app.MapHub<ExampleHub>("/hubs/example");
+app.MapHub<StreamingHub>("/hubs/streaming");
 app.MapRazorPages();
 app.MapFallbackToPage("/Shared/FrontendSPA");
 

Iceshrimp.Backend/configuration.ini

@@ -90,4 +90,5 @@ Iceshrimp = Information
 Microsoft.AspNetCore = Warning
 Microsoft.EntityFrameworkCore = Warning
 Microsoft.EntityFrameworkCore.Migrations = Information
-Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager = Critical
+Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager = Critical
+Iceshrimp.Backend.Hubs.Authentication.HubAuthenticationHandler = Warning

Iceshrimp.Frontend/Pages/Hub.razor

@@ -40,6 +40,9 @@
                          .WithUrl(Navigation.ToAbsoluteUri("/hubs/example"))
                          .AddMessagePackProtocol()
                          .Build();
+        
+        //TODO: authentication is done like this:
+        //options => { options.AccessTokenProvider = () => Task.FromResult("the_access_token")!; })
 
         _hubConnection.On<string, string>("ReceiveMessage", (user, message) =>
         {