Add IHttpMaxRequestBodySizeFeature (#852)

Author: halter73

src/Microsoft.AspNetCore.Http.Features/IHttpMaxRequestBodySizeFeature.cs

@@ -0,0 +1,22 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Http.Features
+{
+    /// <summary>
+    /// Feature to inspect and modify the maximum request body size for a single request.
+    /// </summary>
+    public interface IHttpMaxRequestBodySizeFeature
+    {
+        /// <summary>
+        /// The maximum allowed size of the current request body in bytes.
+        /// When set to null, the maximum request body size is unlimited.
+        /// This cannot be modified after the reading the request body has started.
+        /// This limit does not affect upgraded connections which are always unlimited.
+        /// </summary>
+        /// <remarks>
+        /// Defaults to the server's global max request body size limit.
+        /// </remarks>
+        long? MaxRequestBodySize { get; set; }
+    }
+}