miniflux_v2/internal/http/request/client_ip.go

// 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"
)

// IsTrustedIP checks if the given remote IP belongs to one of the trusted networks.
func IsTrustedIP(remoteIP string, trustedNetworks []string) bool {
	if remoteIP == "@" || strings.HasPrefix(remoteIP, "/") {
		return true
	}

	ip := net.ParseIP(remoteIP)
	if ip == nil {
		return false
	}

	for _, cidr := range trustedNetworks {
		_, network, err := net.ParseCIDR(cidr)
		if err != nil {
			continue
		}

		if network.Contains(ip) {
			return true
		}
	}

	return false
}

// FindClientIP returns the client real IP address based on trusted Reverse-Proxy HTTP headers.
func FindClientIP(r *http.Request, isTrustedProxyClient bool) string {
	if isTrustedProxyClient {
		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 without considering HTTP headers.
func FindRemoteIP(r *http.Request) string {
	remoteIP, _, err := net.SplitHostPort(r.RemoteAddr)
	if err != nil {
		remoteIP = r.RemoteAddr
	}
	return dropIPv6zone(remoteIP)
}

func dropIPv6zone(address string) string {
	i := strings.IndexByte(address, '%')
	if i != -1 {
		address = address[:i]
	}
	return address
}