From dba7604a434528fba9e1266e11f55de954a0fd3b Mon Sep 17 00:00:00 2001
From: Nicolas Carlier <n.carlier@nunux.org>
Date: Fri, 30 Dec 2022 08:26:06 +0000
Subject: [PATCH] feat(middleware): add X-Forwarded-For middleware

close #73
---
 pkg/api/routes.go     |  1 +
 pkg/middleware/xff.go | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100644 pkg/middleware/xff.go

diff --git a/pkg/api/routes.go b/pkg/api/routes.go
index 2521b72..7068dc1 100644
--- a/pkg/api/routes.go
+++ b/pkg/api/routes.go
@@ -9,6 +9,7 @@ import (
 )
 
 var commonMiddlewares = middleware.Middlewares{
+	middleware.XFF,
 	middleware.Cors,
 	middleware.Logger,
 	middleware.Tracing(nextRequestID),
diff --git a/pkg/middleware/xff.go b/pkg/middleware/xff.go
new file mode 100644
index 0000000..5b9afa9
--- /dev/null
+++ b/pkg/middleware/xff.go
@@ -0,0 +1,27 @@
+package middleware
+
+import (
+	"net"
+	"net/http"
+)
+
+const xForwardedFor = "X-Forwarded-For"
+
+func getIP(req *http.Request) string {
+	ip, _, err := net.SplitHostPort(req.RemoteAddr)
+	if err != nil {
+		return req.RemoteAddr
+	}
+	return ip
+}
+
+// XFF is a middleware to identifying the originating IP address using X-Forwarded-For header
+func XFF(inner http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		xff := r.Header.Get(xForwardedFor)
+		if xff == "" {
+			r.Header.Set(xForwardedFor, getIP(r))
+		}
+		inner.ServeHTTP(w, r)
+	})
+}