Added UserAgent to api request trace log

Co-Authored-By: Taloth <Taloth@users.noreply.github.com>

src/Lidarr.Http/Extensions/RequestExtensions.cs

@@ -1,5 +1,8 @@
 using System;
+using System.Linq;
+using System.Net;
 using Nancy;
+using NzbDrone.Common.Extensions;
 
 namespace Lidarr.Http.Extensions
 {
@@ -90,5 +93,48 @@ namespace Lidarr.Http.Extensions
 
             return defaultValue;
         }
+
+        public static string GetRemoteIP(this NancyContext context)
+        {
+            if (context == null || context.Request == null)
+            {
+                return "Unknown";
+            }
+
+            var remoteAddress = context.Request.UserHostAddress;
+            IPAddress remoteIP;
+
+            // Only check if forwarded by a local network reverse proxy
+            if (IPAddress.TryParse(remoteAddress, out remoteIP) && remoteIP.IsLocalAddress())
+            {
+                var realIPHeader = context.Request.Headers["X-Real-IP"];
+                if (realIPHeader.Any())
+                {
+                    return realIPHeader.First().ToString();
+                }
+
+                var forwardedForHeader = context.Request.Headers["X-Forwarded-For"];
+                if (forwardedForHeader.Any())
+                {
+                    // Get the first address that was forwarded by a local IP to prevent remote clients faking another proxy
+                    foreach (var forwardedForAddress in forwardedForHeader.SelectMany(v => v.Split(',')).Select(v => v.Trim()).Reverse())
+                    {
+                        if (!IPAddress.TryParse(forwardedForAddress, out remoteIP))
+                        {
+                            return remoteAddress;
+                        }
+
+                        if (!remoteIP.IsLocalAddress())
+                        {
+                            return forwardedForAddress;
+                        }
+
+                        remoteAddress = forwardedForAddress;
+                    }
+                }
+            }
+
+            return remoteAddress;
+        }
     }
 }