identity: get correct remote address in case of auth failure

Streetwriters.Identity/Extensions/HttpContextExtensions.cs

@@ -18,6 +18,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 using System;
+using System.Linq;
+using System.Net;
 using System.Text;
 using Ng.Services;
 
@@ -25,18 +27,39 @@ namespace Microsoft.AspNetCore.Http
 {
     public static class HttpContextExtensions
     {
+        /// <summary>
+        /// Get remote ip address, optionally allowing for x-forwarded-for header check
+        /// </summary>
+        /// <param name="context">Http context</param>
+        /// <param name="allowForwarded">Whether to allow x-forwarded-for header check</param>
+        /// <returns>IPAddress</returns>
+        public static IPAddress GetRemoteIPAddress(this HttpContext context, bool allowForwarded = true)
+        {
+            if (allowForwarded)
+            {
+                // if you are allowing these forward headers, please ensure you are restricting context.Connection.RemoteIpAddress
+                // to cloud flare ips: https://www.cloudflare.com/ips/
+                string header = (context.Request.Headers["CF-Connecting-IP"].FirstOrDefault() ?? context.Request.Headers["X-Forwarded-For"].FirstOrDefault());
+                if (IPAddress.TryParse(header, out IPAddress ip))
+                {
+                    return ip;
+                }
+            }
+            return context.Connection.RemoteIpAddress;
+        }
+
         static UserAgentService userAgentService = new UserAgentService();
         public static string GetClientInfo(this HttpContext httpContext)
         {
-            var clientIp = httpContext.Connection.RemoteIpAddress;
+            var clientIp = httpContext.GetRemoteIPAddress().ToString();
             var country = httpContext.Request.Headers["CF-IPCountry"];
             var userAgent = httpContext.Request.Headers["User-Agent"];
             var builder = new StringBuilder();
 
             builder.AppendLine($"Date: {DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ss")}");
 
-            if (clientIp != null)
-                builder.AppendLine($"IP: {clientIp.ToString()}");
+            if (!string.IsNullOrEmpty(country))
+                builder.AppendLine($"IP: {clientIp}");
 
             if (!string.IsNullOrEmpty(country))
                 builder.AppendLine($"Country: {country.ToString()}");

Streetwriters.Identity/Startup.cs

@@ -173,7 +173,7 @@ namespace Streetwriters.Identity
             {
                 app.UseForwardedHeaders(new ForwardedHeadersOptions
                 {
-                    ForwardedForHeaderName = "CF_CONNECTING_IP",
+                    ForwardedForHeaderName = "CF-Connecting-IP",
                     ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto
                 });
             }