From 8c1c6cef651759a61115b7dca4659fe0905bb74b Mon Sep 17 00:00:00 2001
From: Rolf Kristensen <sweaty1@hotmail.com>
Date: Sun, 2 Dec 2018 19:33:41 +0100
Subject: [PATCH] Added aspnet-traceidentifier for AspNet for NLog.Web

---
 .../AspNetTraceIdentifierLayoutRenderer.cs    | 33 ++++++++++++++++++-
 NLog.Web/NLog.Web.csproj                      |  3 ++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/NLog.Web.AspNetCore/LayoutRenderers/AspNetTraceIdentifierLayoutRenderer.cs b/NLog.Web.AspNetCore/LayoutRenderers/AspNetTraceIdentifierLayoutRenderer.cs
index 0f66ce387..9a5bc0c94 100644
--- a/NLog.Web.AspNetCore/LayoutRenderers/AspNetTraceIdentifierLayoutRenderer.cs
+++ b/NLog.Web.AspNetCore/LayoutRenderers/AspNetTraceIdentifierLayoutRenderer.cs
@@ -17,7 +17,38 @@ public class AspNetTraceIdentifierLayoutRenderer : AspNetLayoutRendererBase
         protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
         {
             var httpContext = HttpContextAccessor.HttpContext;
-            builder.Append(httpContext.TraceIdentifier);
+            builder.Append(LookupTraceIdentifier(httpContext));
         }
+
+#if ASP_NET_CORE
+        private string LookupTraceIdentifier(Microsoft.AspNetCore.Http.HttpContext httpContext)
+        {
+            return httpContext.TraceIdentifier;
+        }
+#else
+        /// <summary>
+        /// Requires IIS ETW feature enabled. https://docs.microsoft.com/en-us/iis/configuration/system.webServer/httpTracing/
+        ///
+        /// See also http://blog.tatham.oddie.com.au/2012/02/07/code-request-correlation-in-asp-net/
+        /// </summary>
+        private string LookupTraceIdentifier(System.Web.HttpContextBase httpContext)
+        {
+            var provider = httpContext as IServiceProvider;
+            if (provider != null)
+            {
+                var workerRequest = (System.Web.HttpWorkerRequest)provider.GetService(typeof(System.Web.HttpWorkerRequest));
+                if (workerRequest != null)
+                {
+                    Guid requestIdGuid = workerRequest.RequestTraceIdentifier;
+                    if (requestIdGuid != Guid.Empty)
+                    {
+                        return requestIdGuid.ToString();
+                    }
+                }
+            }
+
+            return null;
+        }
+#endif
     }
 }
diff --git a/NLog.Web/NLog.Web.csproj b/NLog.Web/NLog.Web.csproj
index 3c177816d..936d3c791 100644
--- a/NLog.Web/NLog.Web.csproj
+++ b/NLog.Web/NLog.Web.csproj
@@ -75,6 +75,9 @@
     <Compile Include="..\NLog.Web.AspNetCore\LayoutRenderers\AspNetRequestIpLayoutRenderer.cs" />
     <Compile Include="..\NLog.Web.AspNetCore\LayoutRenderers\AspNetSessionIdLayoutRenderer.cs" />
     <Compile Include="..\NLog.Web.AspNetCore\LayoutRenderers\AspNetSessionValueLayoutRenderer.cs" />
+    <Compile Include="..\NLog.Web.AspNetCore\LayoutRenderers\AspNetTraceIdentifierLayoutRenderer.cs">
+      <Link>AspNetTraceIdentifierLayoutRenderer.cs</Link>
+    </Compile>
     <Compile Include="..\NLog.Web.AspNetCore\LayoutRenderers\AspNetUserAuthTypeLayoutRenderer.cs" />
     <Compile Include="..\NLog.Web.AspNetCore\LayoutRenderers\AspNetUserIdentityLayoutRenderer.cs" />
     <Compile Include="..\NLog.Web.AspNetCore\LayoutRenderers\AspNetWebRootPathLayoutRenderer.cs" />