1 files changed, 76 insertions, 0 deletions
diff --git a/Jellyfin.Server/Middleware/LanFilteringMiddleware.cs b/Jellyfin.Server/Middleware/LanFilteringMiddleware.cs
new file mode 100644
index 000000000..9d795145a
--- /dev/null
+++ b/Jellyfin.Server/Middleware/LanFilteringMiddleware.cs
@@ -0,0 +1,76 @@
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using MediaBrowser.Common.Net;
+using MediaBrowser.Controller.Configuration;
+using Microsoft.AspNetCore.Http;
+
+namespace Jellyfin.Server.Middleware
+{
+    /// <summary>
+    /// Validates the LAN host IP based on application configuration.
+    /// </summary>
+    public class LanFilteringMiddleware
+    {
+        private readonly RequestDelegate _next;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="LanFilteringMiddleware"/> class.
+        /// </summary>
+        /// <param name="next">The next delegate in the pipeline.</param>
+        public LanFilteringMiddleware(RequestDelegate next)
+        {
+            _next = next;
+        }
+
+        /// <summary>
+        /// Executes the middleware action.
+        /// </summary>
+        /// <param name="httpContext">The current HTTP context.</param>
+        /// <param name="networkManager">The network manager.</param>
+        /// <param name="serverConfigurationManager">The server configuration manager.</param>
+        /// <returns>The async task.</returns>
+        public async Task Invoke(HttpContext httpContext, INetworkManager networkManager, IServerConfigurationManager serverConfigurationManager)
+        {
+            var currentHost = httpContext.Request.Host.ToString();
+            var hosts = serverConfigurationManager
+                .Configuration
+                .LocalNetworkAddresses
+                .Select(NormalizeConfiguredLocalAddress)
+                .ToList();
+
+            if (hosts.Count == 0)
+            {
+                await _next(httpContext).ConfigureAwait(false);
+                return;
+            }
+
+            currentHost ??= string.Empty;
+
+            if (networkManager.IsInPrivateAddressSpace(currentHost))
+            {
+                hosts.Add("localhost");
+                hosts.Add("127.0.0.1");
+
+                if (hosts.All(i => currentHost.IndexOf(i, StringComparison.OrdinalIgnoreCase) == -1))
+                {
+                    return;
+                }
+            }
+
+            await _next(httpContext).ConfigureAwait(false);
+        }
+
+        private static string NormalizeConfiguredLocalAddress(string address)
+        {
+            var add = address.AsSpan().Trim('/');
+            int index = add.IndexOf('/');
+            if (index != -1)
+            {
+                add = add.Slice(index + 1);
+            }
+
+            return add.TrimStart('/').ToString();
+        }
+    }
+}