Move internal packages to an internal folder

For reference: https://go.dev/doc/go1.4#internalpackages

internal/http/request/client_ip.go

@@ -0,0 +1,55 @@
+// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package request // import "miniflux.app/v2/internal/http/request"
+
+import (
+	"net"
+	"net/http"
+	"strings"
+)
+
+// FindClientIP returns the client real IP address based on trusted Reverse-Proxy HTTP headers.
+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])
+			address = dropIPv6zone(address)
+
+			if net.ParseIP(address) != nil {
+				return address
+			}
+		}
+	}
+
+	// Fallback to TCP/IP source IP address.
+	return FindRemoteIP(r)
+}
+
+// FindRemoteIP returns remote client IP address.
+func FindRemoteIP(r *http.Request) string {
+	remoteIP, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err != nil {
+		remoteIP = r.RemoteAddr
+	}
+	remoteIP = dropIPv6zone(remoteIP)
+
+	// When listening on a Unix socket, RemoteAddr is empty.
+	if remoteIP == "" {
+		remoteIP = "127.0.0.1"
+	}
+
+	return remoteIP
+}
+
+func dropIPv6zone(address string) string {
+	i := strings.IndexByte(address, '%')
+	if i != -1 {
+		address = address[:i]
+	}
+	return address
+}