From 6a1e79ef2de08fd154c27d8e14ddb5924c782943 Mon Sep 17 00:00:00 2001
From: Vegar Vikan <vegar@vi-kan.net>
Date: Thu, 12 May 2016 23:14:51 +0200
Subject: [PATCH] Suppressing exception thrown when accessing
 HttpContext.Request (#56)

* Suppressing exception thrown when accessing HttpContext.Request
---
 .../AspNetRequestValueLayoutRendererTests.cs  | 24 +++++++++++++++++
 .../AspNetRequestValueLayoutRenderer.cs       | 27 ++++++++++++++++++-
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/NLog.Web.ASPNET5.Tests/LayoutRenderers/AspNetRequestValueLayoutRendererTests.cs b/NLog.Web.ASPNET5.Tests/LayoutRenderers/AspNetRequestValueLayoutRendererTests.cs
index 735409c9..e30f4f0f 100644
--- a/NLog.Web.ASPNET5.Tests/LayoutRenderers/AspNetRequestValueLayoutRendererTests.cs
+++ b/NLog.Web.ASPNET5.Tests/LayoutRenderers/AspNetRequestValueLayoutRendererTests.cs
@@ -1,7 +1,11 @@
 using System.Collections.Specialized;
+using System.IO;
 using System.Web;
+using NLog.Common;
+using NLog.Config;
 using NLog.Web.LayoutRenderers;
 using NSubstitute;
+using NSubstitute.ExceptionExtensions;
 using Xunit;
 
 namespace NLog.Web.Tests.LayoutRenderers
@@ -18,6 +22,26 @@ public void NullHttpContextRendersEmptyString()
             Assert.Empty(result);
         }
 
+        [Fact]
+        public void NullRequestRendersEmptyStringWithoutLoggingError()
+        {
+            var internalLog = new StringWriter();
+            InternalLogger.LogWriter = internalLog;
+            InternalLogger.LogLevel = LogLevel.Error;
+
+            var httpContext = Substitute.For<HttpContextBase>();
+            httpContext.Request.Returns(x => { throw new HttpException(); });
+
+            var renderer = new AspNetRequestValueLayoutRenderer();
+            renderer.HttpContextAccessor = new FakeHttpContextAccessor(httpContext);
+            renderer.Item = "key";
+
+            string result = renderer.Render(new LogEventInfo());
+
+            Assert.Empty(result);
+            Assert.Equal(true, string.IsNullOrEmpty(internalLog.ToString()));
+        }
+
         public class ItemTests
         {
             [Fact]
diff --git a/NLog.Web.ASPNET5/LayoutRenderers/AspNetRequestValueLayoutRenderer.cs b/NLog.Web.ASPNET5/LayoutRenderers/AspNetRequestValueLayoutRenderer.cs
index 302edff3..27bc6ded 100644
--- a/NLog.Web.ASPNET5/LayoutRenderers/AspNetRequestValueLayoutRenderer.cs
+++ b/NLog.Web.ASPNET5/LayoutRenderers/AspNetRequestValueLayoutRenderer.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Text;
+using NLog.Common;
 #if !DNX
 using System.Web;
 #else
@@ -76,7 +77,7 @@ public class AspNetRequestValueLayoutRenderer : AspNetLayoutRendererBase
         /// <param name="logEvent">Logging event.</param>
         protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
         {
-            var httpRequest = HttpContextAccessor.HttpContext.Request;
+            var httpRequest = HttpContextAccessor.HttpContext.TryGetRequest();
             if (httpRequest == null)
             {
                 return;
@@ -137,4 +138,28 @@ protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
             }
         }
     }
+
+    internal static class RequestAccessor
+    {
+#if !DNX
+        internal static HttpRequestBase TryGetRequest(this HttpContextBase context)
+        {
+            try
+            {
+                return context.Request;
+            }
+            catch (HttpException ex)
+            {
+                InternalLogger.Debug("Exception thrown when accessing Request: " + ex);
+                return null;
+            }
+        }
+#else
+        internal static HttpRequest TryGetRequest(this HttpContext context)
+        {
+            return context.Request;
+        }
+#endif
+    }
+
 }
\ No newline at end of file