update documents

README.md

@@ -22,16 +22,21 @@ var middleware func(http.Handler) http.Handler = realip.MustMiddleware(&realip.C
     RealIPHeader:    realip.HeaderXForwardedFor,
     RealIPRecursive: true,
 })
-var handler http.HandlerFunc = func(w http.ResponseWriter, r *http.Request) {
-    fmt.Fprintf(w, "Hello World")
+var handler http.HandlerFunc = func(w http.ResponseWriter, req *http.Request) {
+    fmt.Fprintf(w, req.Header.Get("X-Real-IP"))
 })
 handler = middleware(handler)
 ```
 
 ## Description
 
 The realip package implements detecting client real IP mechanisms from request headers in Go's HTTP middleware layer.
-This have a similar behavior as Nginx's ngx\_http\_realip\_module
+
+This realizes the similar function as Nginx's `ngx_http_realip_module` in the layer inside Go.
+Therefore, the setting property names and behaviors are also close to `ngx_http_realip_module`.
+
+The realip provides Go's HTTP Middleware. It detects the client's real ip from the request and
+sets it in the specified request header (Default: X-Real-IP).
 
 ## Installation
 

doc.go

@@ -0,0 +1,25 @@
+/*
+Package realip provides cliant real ip detection mechanisms from http.Request
+in Go's HTTP middleware layer.
+
+	_, ipnet, _ := net.ParseCIDR("192.168.0.0/16")
+	var middleware func(http.Handler) http.Handler = realip.MustMiddleware(&realip.Config{
+		RealIPFrom:      []*net.IPNet{ipnet},
+		RealIPHeader:    realip.HeaderXForwardedFor,
+		RealIPRecursive: true,
+	})
+	var handler http.HandlerFunc = func(w http.ResponseWriter, req *http.Request) {
+		fmt.Fprintf(w, req.Header.Get("X-Real-IP"))
+	})
+	handler = middleware(handler)
+	l, _ := net.Listen("tcp", "127.0.0.1:8080")
+
+	http.Serve(l, handler)
+
+This realizes the same function as Nginx's ngx_http_realip_module in the layer inside Go.
+Therefore, the setting property names and behaviors are also close to ngx_http_realip_module.
+
+The realip provides Go's HTTP Middleware. It detects the client's real ip from the request and
+sets it in the specified request header (Default: X-Real-IP).
+*/
+package realip

realip_test.go

@@ -143,4 +143,13 @@ func TestMiddleware(t *testing.T) {
 			}
 		})
 	}
+
+	t.Run("error", func(t *testing.T) {
+		_, err := realip.Middleware(&realip.Config{
+			RealIPHeader: "Forwarded",
+		})
+		if err == nil {
+			t.Errorf("error should be occurred but nil")
+		}
+	})
 }