Implement canonical linking

SSO-Auth/Api/RequestHelpers.cs

@@ -0,0 +1,62 @@
+// The following code is a derivative work of the code from the Jellyfin project,
+// which is licensed GPLv2. This code therefore is also licensed under the terms
+// of the GNU Public License, verison 2.
+// https://github.com/jellyfin/jellyfin/blob/a60cb280a3d31ba19ffb3a94cf83ef300a7473b7/Jellyfin.Api/Helpers/RequestHelpers.cs#L63-L77
+
+// Use of this relatively small snippet complies with fair use
+// See https://www.gnu.org/licenses/gpl-faq.en.html#SourceCodeInDocumentation
+// These helpers were not published within a Nuget package, so it was neccessary to re-implement.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Mime;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+using IdentityModel.OidcClient;
+using Jellyfin.Data.Entities;
+using Jellyfin.Data.Enums;
+using Jellyfin.Plugin.SSO_Auth.Config;
+using Jellyfin.Plugin.SSO_Auth.Helpers;
+using MediaBrowser.Controller.Authentication;
+using MediaBrowser.Controller.Library;
+using MediaBrowser.Controller.Net;
+using MediaBrowser.Controller.Session;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Logging;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+
+namespace Jellyfin.Plugin.SSO_Auth.Helpers;
+
+/// <summary>
+/// Request Extensions.
+/// </summary>
+public static class RequestHelpers
+{
+    /// <summary>
+    /// Checks if the user can update an entry.
+    /// </summary>
+    /// <param name="authContext">Instance of the <see cref="IAuthorizationContext"/> interface.</param>
+    /// <param name="requestContext">The <see cref="HttpRequest"/>.</param>
+    /// <param name="userId">The user id.</param>
+    /// <param name="restrictUserPreferences">Whether to restrict the user preferences.</param>
+    /// <returns>A <see cref="bool"/> whether the user can update the entry.</returns>
+    internal static async Task<bool> AssertCanUpdateUser(IAuthorizationContext authContext, HttpRequest requestContext, Guid userId, bool restrictUserPreferences)
+    {
+        var auth = await authContext.GetAuthorizationInfo(requestContext).ConfigureAwait(false);
+
+        var authenticatedUser = auth.User;
+
+        // If they're going to update the record of another user, they must be an administrator
+        if ((!userId.Equals(auth.UserId) && !authenticatedUser.HasPermission(PermissionKind.IsAdministrator))
+            || (restrictUserPreferences && !authenticatedUser.EnableUserPreferenceAccess))
+        {
+            return false;
+        }
+
+        return true;
+    }
+}