Merge pull request #1030 from TechnologyEnhancedLearning/Develop/Fixes/TD-3734-Concurrent-Sessions-Allowed

TD-3743: Concurrent Sessions Allowed

Author: swapnamol-abraham

LearningHub.Nhs.WebUI/Helpers/InMemoryTicketStore.cs

@@ -0,0 +1,104 @@
+namespace LearningHub.Nhs.WebUI.Helpers
+{
+    using System;
+    using System.Collections.Concurrent;
+    using System.Linq;
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Authentication;
+    using Microsoft.AspNetCore.Authentication.Cookies;
+
+    /// <summary>
+    /// Defines the <see cref="InMemoryTicketStore" />.
+    /// </summary>
+    public class InMemoryTicketStore : ITicketStore
+    {
+        private readonly ConcurrentDictionary<string, AuthenticationTicket> cache;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="InMemoryTicketStore"/> class.
+        /// The InMemoryTicketStore.
+        /// </summary>
+        /// <param name="cache">the cache.</param>
+        public InMemoryTicketStore(ConcurrentDictionary<string, AuthenticationTicket> cache)
+        {
+            this.cache = cache;
+        }
+
+        /// <summary>
+        /// The StoreAsync.
+        /// </summary>
+        /// <param name="ticket">The ticket.</param>
+        /// <returns>The key.</returns>
+        public async Task<string> StoreAsync(AuthenticationTicket ticket)
+        {
+            var ticketUserId = ticket.Principal.Claims.Where(c => c.Type == "sub")
+                .FirstOrDefault()
+                .Value;
+            var matchingAuthTicket = this.cache.Values.FirstOrDefault(
+                t => t.Principal.Claims.FirstOrDefault(
+                    c => c.Type == "sub"
+                    && c.Value == ticketUserId) != null);
+            if (matchingAuthTicket != null)
+            {
+                var cacheKey = this.cache.Where(
+                    entry => entry.Value == matchingAuthTicket)
+                    .Select(entry => entry.Key)
+                    .FirstOrDefault();
+                this.cache.TryRemove(
+                    cacheKey,
+                    out _);
+            }
+
+            var key = Guid
+                .NewGuid()
+                .ToString();
+            await this.RenewAsync(
+                key,
+                ticket);
+            return key;
+        }
+
+        /// <summary>
+        /// The RenewAsync.
+        /// </summary>
+        /// <param name="key">The key.</param>
+        /// <param name="ticket">The ticket.</param>
+        /// <returns>The Task.</returns>
+        public Task RenewAsync(
+            string key,
+            AuthenticationTicket ticket)
+        {
+            this.cache.AddOrUpdate(
+                key,
+                ticket,
+                (_, _) => ticket);
+            return Task.CompletedTask;
+        }
+
+        /// <summary>
+        /// The RetrieveAsync.
+        /// </summary>
+        /// <param name="key">The Key.</param>
+        /// <returns>The Task.</returns>
+        public Task<AuthenticationTicket> RetrieveAsync(string key)
+        {
+            this.cache.TryGetValue(
+                key,
+                out var ticket);
+            return Task.FromResult(ticket);
+        }
+
+        /// <summary>
+        /// The RemoveAsync.
+        /// </summary>
+        /// <param name="key">The key.</param>
+        /// <returns>The Task.</returns>
+        public Task RemoveAsync(string key)
+        {
+            this.cache.TryRemove(
+                key,
+                out _);
+            return Task.CompletedTask;
+        }
+    }
+}

LearningHub.Nhs.WebUI/Startup/AuthenticationConfiguration.cs

@@ -1,12 +1,14 @@
 namespace LearningHub.Nhs.WebUI.Startup
 {
     using System;
+    using System.Collections.Concurrent;
     using System.Linq;
     using System.Threading.Tasks;
     using IdentityModel;
     using LearningHub.Nhs.Caching;
     using LearningHub.Nhs.WebUI.Configuration;
     using LearningHub.Nhs.WebUI.Handlers;
+    using LearningHub.Nhs.WebUI.Helpers;
     using Microsoft.AspNetCore.Authentication;
     using Microsoft.AspNetCore.Authentication.Cookies;
     using Microsoft.AspNetCore.Authentication.OpenIdConnect;
@@ -41,6 +43,7 @@ public static void ConfigureAuthentication(this IServiceCollection services, Lea
                 options.SlidingExpiration = true;
                 options.EventsType = typeof(CookieEventHandler);
                 options.AccessDeniedPath = "/Home/AccessDenied";
+                options.SessionStore = new InMemoryTicketStore(new ConcurrentDictionary<string, AuthenticationTicket>());
             })
             .AddOpenIdConnect(AuthenticationScheme, options =>
             {