From 9f573a19d698114e0ac63bd9f394f181a3f9293a Mon Sep 17 00:00:00 2001
From: Knut Ahlers <knut@ahlers.me>
Date: Tue, 3 Apr 2018 21:51:39 +0200
Subject: [PATCH] Add proxy IP detection

Signed-off-by: Knut Ahlers <knut@ahlers.me>
---
 http/logHandler.go | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/http/logHandler.go b/http/logHandler.go
index 7a55372..95b7bc6 100644
--- a/http/logHandler.go
+++ b/http/logHandler.go
@@ -3,17 +3,22 @@ package http
 import (
 	"log"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/Luzifer/go_helpers/accessLogger"
 )
 
 type HTTPLogHandler struct {
-	Handler http.Handler
+	Handler          http.Handler
+	TrustedIPHeaders []string
 }
 
 func NewHTTPLogHandler(h http.Handler) http.Handler {
-	return HTTPLogHandler{Handler: h}
+	return HTTPLogHandler{
+		Handler:          h,
+		TrustedIPHeaders: []string{"X-Forwarded-For", "RemoteAddr", "X-Real-IP"},
+	}
 }
 
 func (l HTTPLogHandler) ServeHTTP(res http.ResponseWriter, r *http.Request) {
@@ -23,7 +28,7 @@ func (l HTTPLogHandler) ServeHTTP(res http.ResponseWriter, r *http.Request) {
 	l.Handler.ServeHTTP(ares, r)
 
 	log.Printf("%s - \"%s %s\" %d %d \"%s\" \"%s\" %s",
-		r.RemoteAddr,
+		l.findIP(r),
 		r.Method,
 		r.URL.Path,
 		ares.StatusCode,
@@ -33,3 +38,15 @@ func (l HTTPLogHandler) ServeHTTP(res http.ResponseWriter, r *http.Request) {
 		time.Since(start),
 	)
 }
+
+func (l HTTPLogHandler) findIP(r *http.Request) string {
+	remoteAddr := strings.SplitN(r.RemoteAddr, ":", 2)[0]
+
+	for _, hdr := range l.TrustedIPHeaders {
+		if value := r.Header.Get(hdr); value != "" {
+			return strings.SplitN(value, ",", 2)[0]
+		}
+	}
+
+	return remoteAddr
+}