${AspNetRequestIp} added CheckForwardedForHeader to check for X-Forwarded-For header

NLog.Web.AspNetCore.Tests/LayoutRenderers/AspNetRequestIpLayoutRendererTests.cs

@@ -0,0 +1,87 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+
+#if !ASP_NET_CORE
+using System.Web;
+using System.Web.Routing;
+using System.Collections.Specialized;
+using System.Web.SessionState;
+#else
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Primitives;
+using HttpContextBase = Microsoft.AspNetCore.Http.HttpContext;
+#endif
+using NLog.Web.LayoutRenderers;
+using NSubstitute;
+using Xunit;
+using System.Net;
+
+namespace NLog.Web.Tests.LayoutRenderers
+{
+    public class AspNetRequestIpLayoutRendererTests : TestBase
+    {
+        private const string ForwardedForHeader = "X-Forwarded-For";
+
+        [Fact]
+        public void ForwardedForHeaderNotPresentRenderRemoteAddress()
+        {
+            var httpContext = Substitute.For<HttpContextBase>();
+#if !ASP_NET_CORE
+            httpContext.Request.ServerVariables.Returns(new NameValueCollection {{"REMOTE_ADDR", "192.0.0.0"}});
+            httpContext.Request.Headers.Returns(new NameValueCollection());
+#else
+            var headers = new HeaderDict();
+            httpContext.Request.Headers.Returns(callinfo => headers);
+            httpContext.Connection.RemoteIpAddress.Returns(callinfo => IPAddress.Parse("192.0.0.0"));
+#endif
+            var renderer = new AspNetRequestIpLayoutRenderer {CheckForwardedForHeader = true};
+            renderer.HttpContextAccessor = new FakeHttpContextAccessor(httpContext);
+
+            string result = renderer.Render(new LogEventInfo());
+
+            Assert.Equal("192.0.0.0", result);
+        }
+
+        [Fact]
+        public void ForwardedForHeaderPresentRenderForwardedValue()
+        {
+            var httpContext = Substitute.For<HttpContextBase>();
+#if !ASP_NET_CORE
+            httpContext.Request.ServerVariables.Returns(new NameValueCollection {{"REMOTE_ADDR", "192.0.0.0"}});
+            httpContext.Request.Headers.Returns(new NameValueCollection {{ForwardedForHeader, "127.0.0.1"}});
+#else
+            var headers = new HeaderDict();
+            headers.Add(ForwardedForHeader, new StringValues("127.0.0.1"));
+            httpContext.Request.Headers.Returns(callinfo => headers);
+#endif
+            var renderer = new AspNetRequestIpLayoutRenderer {CheckForwardedForHeader = true};
+            renderer.HttpContextAccessor = new FakeHttpContextAccessor(httpContext);
+
+            string result = renderer.Render(new LogEventInfo());
+
+            Assert.Equal("127.0.0.1", result);
+        }
+
+        [Fact]
+        public void ForwardedForHeaderContainsMultipleEntriesRenderFirstValue()
+        {
+            var httpContext = Substitute.For<HttpContextBase>();
+#if !ASP_NET_CORE
+            httpContext.Request.ServerVariables.Returns(new NameValueCollection {{"REMOTE_ADDR", "192.0.0.0"}});
+            httpContext.Request.Headers.Returns(
+                new NameValueCollection {{ForwardedForHeader, "127.0.0.1, 192.168.1.1"}});
+#else
+            var headers = new HeaderDict();
+            headers.Add(ForwardedForHeader, new StringValues("127.0.0.1, 192.168.1.1"));
+            httpContext.Request.Headers.Returns(callinfo => headers);
+#endif
+            var renderer = new AspNetRequestIpLayoutRenderer {CheckForwardedForHeader = true};
+            renderer.HttpContextAccessor = new FakeHttpContextAccessor(httpContext);
+
+            string result = renderer.Render(new LogEventInfo());
+
+            Assert.Equal("127.0.0.1", result);
+        }
+    }
+}

NLog.Web.AspNetCore/LayoutRenderers/AspNetRequestIpLayoutRenderer.cs

@@ -1,5 +1,8 @@
 using System;
 using System.Text;
+#if ASP_NET_CORE
+using Microsoft.AspNetCore.Http;
+#endif
 using NLog.LayoutRenderers;
 using NLog.Web.Internal;
 
@@ -16,18 +19,72 @@ namespace NLog.Web.LayoutRenderers
     [LayoutRenderer("aspnet-request-ip")]
     public class AspNetRequestIpLayoutRenderer : AspNetLayoutRendererBase
     {
+        private const string ForwardedForHeader = "X-Forwarded-For";
+
+        /// <summary>
+        /// Gets or sets whether the renderer should check value of X-Forwarded-For header
+        /// </summary>
+        /// <docgen category='Rendering Options' order='10' />
+        public bool CheckForwardedForHeader { get; set; }
+
         /// <summary>
         /// Render IP
         /// </summary>
         protected override void DoAppend(StringBuilder builder, LogEventInfo logEvent)
         {
             var httpContext = HttpContextAccessor.HttpContext;
+
+            var request = httpContext.TryGetRequest();
+            if (request == null)
+            {
+                return;
+            }
+
+            var ip = CheckForwardedForHeader ? TryLookupForwardHeader(request) : string.Empty;
+
+            if (string.IsNullOrEmpty(ip))
+            {
 #if !ASP_NET_CORE
-            var ip = httpContext.TryGetRequest()?.ServerVariables["REMOTE_ADDR"];
+                ip = request.ServerVariables["REMOTE_ADDR"];
 #else
-            var ip = httpContext.Connection?.RemoteIpAddress;
+                ip = httpContext.Connection?.RemoteIpAddress?.ToString();
 #endif
+            }
+
             builder.Append(ip);
         }
+
+#if !ASP_NET_CORE
+        string TryLookupForwardHeader(System.Web.HttpRequestBase httpRequest)
+        {
+            var forwardedHeader = httpRequest.Headers[ForwardedForHeader];
+
+            if (!string.IsNullOrEmpty(forwardedHeader))
+            {
+                var addresses = forwardedHeader.Split(',');
+                if (addresses.Length > 0)
+                {
+                    return addresses[0];
+                }
+            }
+
+            return string.Empty;
+        }
+#else
+        string TryLookupForwardHeader(HttpRequest httpRequest)
+        {
+            if (httpRequest.Headers.ContainsKey(ForwardedForHeader))
+            {
+                var forwardedHeaders = httpRequest.Headers.GetCommaSeparatedValues(ForwardedForHeader);
+
+                if (forwardedHeaders.Length > 0)
+                {
+                    return forwardedHeaders[0];
+                }
+            }
+
+            return string.Empty;
+        }
+#endif
     }
 }

NLog.Web.Tests/NLog.Web.Tests.csproj

@@ -95,6 +95,9 @@
     <Compile Include="..\NLog.Web.AspNetCore.Tests\LayoutRenderers\AspNetRequestFormLayoutRendererTests.cs">
       <Link>AspNetRequestFormLayoutRendererTests.cs</Link>
     </Compile>
+    <Compile Include="..\NLog.Web.AspNetCore.Tests\LayoutRenderers\AspNetRequestIpLayoutRendererTests.cs">
+      <Link>AspNetRequestIpLayoutRendererTests.cs</Link>
+    </Compile>
     <Compile Include="..\NLog.Web.AspNetCore.Tests\LayoutRenderers\AspNetRequestValueLayoutRendererTests.cs" />
     <Compile Include="..\NLog.Web.AspNetCore.Tests\LayoutRenderers\AspNetSessionIDLayoutRendererTests.cs" />
     <Compile Include="..\NLog.Web.AspNetCore.Tests\LayoutRenderers\AspNetSessionValueLayoutRendererTests.cs" />