${aspnet-request-posted-body}: Use Async reading to prevent "Synchronous operations are disallowed"

src/NLog.Web.AspNetCore/Internal/TaskExtensions.cs

@@ -0,0 +1,25 @@
+#if NETSTANDARD
+
+using System;
+using System.Threading.Tasks;
+
+namespace NLog.Web.Internal
+{
+    internal static class TaskExtensions
+    {
+        public static void RunTaskSynchronously(this Task t)
+        {
+            var task = Task.Run(async () => await t);
+            task.Wait();
+        }
+
+        public static T RunTaskSynchronously<T>(this Task<T> t)
+        {
+            T result = default(T);
+            var task = Task.Run(async () => result = await t);
+            task.Wait();
+            return result;
+        }
+    } 
+}
+#endif

src/Shared/LayoutRenderers/AspNetRequestPostedBody.cs

@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using System.Text;
+using System.Threading;
 using NLog.Common;
 using NLog.Config;
 using NLog.LayoutRenderers;
@@ -10,6 +11,7 @@
 using System.Web;
 using HttpRequest = System.Web.HttpRequestBase;
 #else
+using System.Threading.Tasks;
 using HttpRequest = Microsoft.AspNetCore.Http.HttpRequest;
 #endif
 
@@ -70,7 +72,12 @@ private static string BodyToString(Stream body)
                 // Note: don't dispose the StreamReader, it will close the stream and that's unwanted. You could pass that that
                 // to the StreamReader in some platforms, but then the dispose will be a NOOP, so for platform compat just don't dispose
                 var bodyReader = new StreamReader(body);
+
+#if NETSTANDARD
+                var content = bodyReader.ReadToEndAsync().RunTaskSynchronously();
+#else
                 var content = bodyReader.ReadToEnd();
+#endif
                 return content;
             }
             finally
@@ -80,6 +87,8 @@ private static string BodyToString(Stream body)
             }
         }
 
+
+
         private bool TryGetBody(HttpRequest httpRequest, long? contentLength, out Stream body)
         {
             body = null;