Implement the RightsAuthorizationHandler

Note the workaround for https://github.com/dotnet/aspnetcore/issues/56272

src/Tgstation.Server.Api/Rights/RightsHelper.cs

@@ -33,6 +33,12 @@ namespace Tgstation.Server.Api.Rights
 		/// <returns>The <see cref="Enum"/> <see cref="Type"/> of the given <paramref name="rightsType"/>.</returns>
 		public static Type RightToType(RightsType rightsType) => TypeMap[rightsType];
 
+		/// <summary>
+		/// Iterate the <see cref="Type"/> of each right.
+		/// </summary>
+		/// <returns>An <see cref="IEnumerable{T}"/> of each <see cref="Type"/> of right.</returns>
+		public static IEnumerable<Type> AllRightTypes() => TypeMap.Values;
+
 		/// <summary>
 		/// Map a given <typeparamref name="TRight"/> to its respective <see cref="RightsType"/>.
 		/// </summary>

src/Tgstation.Server.Host/Core/Application.cs

@@ -17,6 +17,7 @@ using Microsoft.AspNetCore.Authentication;
 using Microsoft.AspNetCore.Authentication.Cookies;
 using Microsoft.AspNetCore.Authentication.JwtBearer;
 using Microsoft.AspNetCore.Authentication.OpenIdConnect;
+using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Cors.Infrastructure;
 using Microsoft.AspNetCore.Hosting;
@@ -45,6 +46,7 @@ using Serilog.Sinks.Elasticsearch;
 using Tgstation.Server.Api;
 using Tgstation.Server.Api.Hubs;
 using Tgstation.Server.Api.Models;
+using Tgstation.Server.Api.Rights;
 using Tgstation.Server.Common.Http;
 using Tgstation.Server.Host.Authority;
 using Tgstation.Server.Host.Authority.Core;
@@ -811,6 +813,10 @@ namespace Tgstation.Server.Host.Core
 			services.AddScoped<AuthenticationContextFactory>();
 			services.AddScoped<ITokenValidator>(provider => provider.GetRequiredService<AuthenticationContextFactory>());
 
+			var genericRightsAuthHandler = typeof(RightsAuthorizationHandler<>);
+			foreach (var rightType in RightsHelper.AllRightTypes())
+				services.AddScoped(typeof(IAuthorizationHandler), genericRightsAuthHandler.MakeGenericType(rightType));
+
 			// what if you
 			// wanted to just do this:
 			// return provider.GetRequiredService<AuthenticationContextFactory>().CurrentAuthenticationContext

src/Tgstation.Server.Host/Security/RightsAuthorizationHandler.cs

@@ -0,0 +1,125 @@
+using System;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.EntityFrameworkCore;
+
+using Tgstation.Server.Api.Models;
+using Tgstation.Server.Api.Models.Internal;
+using Tgstation.Server.Api.Rights;
+using Tgstation.Server.Host.Database;
+using Tgstation.Server.Host.Extensions;
+using Tgstation.Server.Host.Security.RightsEvaluation;
+using Tgstation.Server.Host.Utils;
+
+namespace Tgstation.Server.Host.Security
+{
+	/// <summary>
+	/// <see cref="AuthorizationHandler{TRequirement}"/> for <see cref="RightsConditional{TRights}"/>s.
+	/// </summary>
+	/// <typeparam name="TRights">The <typeparamref name="TRights"/> to evaluate.</typeparam>
+	public sealed class RightsAuthorizationHandler<TRights> : AuthorizationHandler<RightsConditional<TRights>>
+		where TRights : Enum
+	{
+		/// <summary>
+		/// The <see cref="IDatabaseContext"/> for the <see cref="RightsAuthorizationHandler{TRights}"/>.
+		/// </summary>
+		readonly IDatabaseContext databaseContext;
+
+		/// <summary>
+		/// The <see cref="IApiHeadersProvider"/> for the <see cref="RightsAuthorizationHandler{TRights}"/>.
+		/// </summary>
+		readonly IApiHeadersProvider apiHeadersProvider;
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="RightsAuthorizationHandler{TRights}"/> class.
+		/// </summary>
+		/// <param name="databaseContext">The value of <see cref="databaseContext"/>.</param>
+		/// <param name="apiHeadersProvider">The value of <see cref="apiHeadersProvider"/>.</param>
+		public RightsAuthorizationHandler(IDatabaseContext databaseContext, IApiHeadersProvider apiHeadersProvider)
+		{
+			this.databaseContext = databaseContext ?? throw new ArgumentNullException(nameof(databaseContext));
+			this.apiHeadersProvider = apiHeadersProvider ?? throw new ArgumentNullException(nameof(apiHeadersProvider));
+		}
+
+		/// <inheritdoc />
+		protected override async Task HandleRequirementAsync(AuthorizationHandlerContext context, RightsConditional<TRights> requirement)
+		{
+			// https://github.com/dotnet/aspnetcore/issues/56272
+			CancellationToken cancellationToken = CancellationToken.None;
+
+			ArgumentNullException.ThrowIfNull(context);
+			ArgumentNullException.ThrowIfNull(requirement);
+
+			var rightsType = RightsHelper.TypeToRight<TRights>();
+			var isInstance = RightsHelper.IsInstanceRight(rightsType);
+			var userId = context.User.GetTgsUserId();
+
+			object? permissionSet;
+			if (isInstance)
+			{
+				var apiHeaders = apiHeadersProvider.ApiHeaders;
+				if (apiHeaders == null)
+					throw new InvalidOperationException("API headers should have been validated at this point!");
+
+				if (!apiHeaders.InstanceId.HasValue)
+					throw new InvalidOperationException("Instance ID header should have been validated at this point!");
+
+				var queryableUsers = databaseContext
+					.Users
+					.AsQueryable();
+
+				var matchingUniquePermissionSetIds = queryableUsers
+					.Where(user => user.Id == userId && user.PermissionSet != null)
+					.Select(user => user.PermissionSet!.Id);
+
+				var matchingGroupPermissionSetIds = queryableUsers
+					.Where(user => user.Id == userId && user.Group != null)
+					.Select(user => user.Group!.PermissionSet!.Id);
+
+				permissionSet = await databaseContext
+					.InstancePermissionSets
+					.AsQueryable()
+					.Where(ips => ips.InstanceId == apiHeaders.InstanceId.Value
+						&& (matchingUniquePermissionSetIds.Contains(ips.PermissionSetId) || matchingGroupPermissionSetIds.Contains(ips.PermissionSetId)))
+					.TagWith("rights_authorization_handler_instance_permission_set")
+					.FirstOrDefaultAsync(cancellationToken);
+			}
+			else
+				permissionSet = await databaseContext
+					.PermissionSets
+					.AsQueryable()
+					.Where(permissionSet => permissionSet.UserId == userId)
+					.TagWith("rights_authorization_handler_permission_set")
+					.FirstOrDefaultAsync(cancellationToken);
+
+			if (permissionSet == null)
+				return; // fail
+
+			// use the api versions because they're the ones that contain the actual properties
+			var requiredPermissionSetType = isInstance ? typeof(InstancePermissionSet) : typeof(PermissionSet);
+
+			var rightsClrType = typeof(TRights);
+			var nullableRightsType = typeof(Nullable<>).MakeGenericType(rightsClrType);
+
+			var rightPropertyInfo = requiredPermissionSetType
+				.GetProperties()
+				.Where(propertyInfo => propertyInfo.PropertyType == nullableRightsType && propertyInfo.CanRead)
+				.Single();
+
+			var rightPropertyGetMethod = rightPropertyInfo.GetMethod;
+			if (rightPropertyGetMethod == null)
+				throw new InvalidOperationException($"Rights property {rightPropertyInfo.Name} on {rightsClrType.FullName} has no getter!");
+
+			var right = rightPropertyGetMethod.Invoke(
+				permissionSet,
+				Array.Empty<object>())
+				?? throw new InvalidOperationException("A user right was null!");
+
+			if (requirement.Evaluate((TRights)right))
+				context.Succeed(requirement);
+		}
+	}
+}