${aspnet-request-ip}: make ForwardedForHeader configurable

NLog · Apr 14, 2020 · 0d9f856 · 0d9f856
1 parent 85b35f6
commit 0d9f856
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Showing 2 changed files with 44 additions and 9 deletions.
diff --git a/src/Shared/LayoutRenderers/AspNetRequestIpLayoutRenderer.cs b/src/Shared/LayoutRenderers/AspNetRequestIpLayoutRenderer.cs
@@ -1,11 +1,15 @@
 using System;
+using System.ComponentModel;
 using System.Text;
+
 using NLog.Config;
 using NLog.LayoutRenderers;
+using NLog.Layouts;
 using NLog.Web.Internal;
 #if ASP_NET_CORE
 using Microsoft.AspNetCore.Http;
-
+#else
+using System.Web;
 #endif
 
 namespace NLog.Web.LayoutRenderers
@@ -22,10 +26,14 @@ namespace NLog.Web.LayoutRenderers
     [ThreadSafe]
     public class AspNetRequestIpLayoutRenderer : AspNetLayoutRendererBase
     {
-        private const string ForwardedForHeader = "X-Forwarded-For";
+        /// <summary>
+        /// The header name to check for the Forwarded-For. Default "X-Forwarded-For". Needs <see cref="CheckForwardedForHeader"/>
+        /// </summary>
+        [DefaultValue("X-Forwarded-For")]
+        public Layout ForwardedForHeader { get; set; } = "X-Forwarded-For";
 
         /// <summary>
-        /// Gets or sets whether the renderer should check value of X-Forwarded-For header
+        /// Gets or sets whether the renderer should check value of <see cref="ForwardedForHeader"/> header
         /// </summary>
         /// <docgen category='Rendering Options' order='10' />
         public bool CheckForwardedForHeader { get; set; }
@@ -43,7 +51,7 @@ protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
                 return;
             }
 
-            var ip = CheckForwardedForHeader ? TryLookupForwardHeader(request) : string.Empty;
+            var ip = CheckForwardedForHeader && ForwardedForHeader != null ? TryLookupForwardHeader(request, logEvent) : string.Empty;
 
             if (string.IsNullOrEmpty(ip))
             {
@@ -58,9 +66,10 @@ protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
         }
 
 #if !ASP_NET_CORE
-        string TryLookupForwardHeader(System.Web.HttpRequestBase httpRequest)
+        string TryLookupForwardHeader(HttpRequestBase httpRequest, LogEventInfo logEvent)
         {
-            var forwardedHeader = httpRequest.Headers[ForwardedForHeader];
+            var headerName = ForwardedForHeader.Render(logEvent);
+            var forwardedHeader = httpRequest.Headers[headerName];
 
             if (!string.IsNullOrEmpty(forwardedHeader))
             {
@@ -74,11 +83,12 @@ string TryLookupForwardHeader(System.Web.HttpRequestBase httpRequest)
             return string.Empty;
         }
 #else
-        private string TryLookupForwardHeader(HttpRequest httpRequest)
+        private string TryLookupForwardHeader(HttpRequest httpRequest, LogEventInfo logEvent)
         {
-            if (httpRequest.Headers?.ContainsKey(ForwardedForHeader) == true)
+            var headerName = ForwardedForHeader.Render(logEvent);
+            if (httpRequest.Headers?.ContainsKey(headerName) == true)
             {
-                var forwardedHeaders = httpRequest.Headers.GetCommaSeparatedValues(ForwardedForHeader);
+                var forwardedHeaders = httpRequest.Headers.GetCommaSeparatedValues(headerName);
                 if (forwardedHeaders.Length > 0)
                 {
                     return forwardedHeaders[0];

diff --git a/tests/Shared/LayoutRenderers/AspNetRequestIpLayoutRendererTests.cs b/tests/Shared/LayoutRenderers/AspNetRequestIpLayoutRendererTests.cs
@@ -88,6 +88,31 @@ public void ForwardedForHeaderContainsMultipleEntriesRenderFirstValue()
             // Act
             string result = renderer.Render(new LogEventInfo());
 
+            // Assert
+            Assert.Equal("127.0.0.1", result);
+        }  
+
+        [Fact]
+        public void ForwardedForHeaderContainsMultipleEntriesRenderFirstValue_withCustomHeaderName()
+        {
+            // Arrange
+            var (renderer, httpContext) = CreateWithHttpContext();
+
+#if !ASP_NET_CORE
+            httpContext.Request.ServerVariables.Returns(new NameValueCollection {{"REMOTE_ADDR", "192.0.0.0"}});
+            httpContext.Request.Headers.Returns(
+                new NameValueCollection {{"header2", "127.0.0.1, 192.168.1.1"}});
+#else
+            var headers = new HeaderDict();
+            headers.Add("header2", new StringValues("127.0.0.1, 192.168.1.1"));
+            httpContext.Request.Headers.Returns(callinfo => headers);
+#endif
+            renderer.CheckForwardedForHeader = true;
+            renderer.ForwardedForHeader = "header2";
+
+            // Act
+            string result = renderer.Render(new LogEventInfo());
+
             // Assert
             Assert.Equal("127.0.0.1", result);
         }