Improve request package and add more unit tests

http/request/client_ip.go

@@ -0,0 +1,38 @@
+// Copyright 2018 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package request // import "miniflux.app/http/request"
+
+import (
+	"net"
+	"net/http"
+	"strings"
+)
+
+// FindClientIP returns client real IP address.
+func FindClientIP(r *http.Request) string {
+	headers := []string{"X-Forwarded-For", "X-Real-Ip"}
+	for _, header := range headers {
+		value := r.Header.Get(header)
+
+		if value != "" {
+			addresses := strings.Split(value, ",")
+			address := strings.TrimSpace(addresses[0])
+
+			if net.ParseIP(address) != nil {
+				return address
+			}
+		}
+	}
+
+	// Fallback to TCP/IP source IP address.
+	var remoteIP string
+	if strings.ContainsRune(r.RemoteAddr, ':') {
+		remoteIP, _, _ = net.SplitHostPort(r.RemoteAddr)
+	} else {
+		remoteIP = r.RemoteAddr
+	}
+
+	return remoteIP
+}