IpAddressParser.php

<?php

declare(strict_types=1);

namespace Lit\Middleware\IpAddress;

use Lit\Nimo\Middlewares\AbstractMiddleware;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;

class IpAddressParser extends AbstractMiddleware
{
    /**
     * @var array
     */
    protected $trustedProxies;
    /**
     * @var array
     */
    protected $headers;
    /**
     * @var ?string
     */
    protected $ipAddress;

    public function __construct(
        array $trustedProxies = [],
        array $headers = []
    ) {
        $this->trustedProxies = $trustedProxies;
        $this->headers = $headers;
    }

    /**
     * @return string
     */
    public function getIpAddress(): ?string
    {
        return $this->ipAddress;
    }

    public static function getIpAddressFromRequest(
        ServerRequestInterface $request,
        array $trustedProxies = [],
        array $headers = []
    ): ?string {
        $headers = $headers ?: [
            'Forwarded',
            'X-Forwarded-For',
            'X-Forwarded',
            'X-Cluster-Client-Ip',
            'Client-Ip',
        ];

        $params = $request->getServerParams();

        $remoteAddr = $params['REMOTE_ADDR'] ?? '';
        if (!self::isValidIpAddress($remoteAddr)) {
            return null;
        }

        if (empty($trustedProxies) || !in_array($remoteAddr, $trustedProxies)) {
            return $remoteAddr;
        }

        $ip = self::getIpAddressFromHeaders($request, $headers);
        if (!empty($ip)) {
            return $ip;
        }

        return $remoteAddr;
    }

    protected function main(): ResponseInterface
    {
        $this->attachToRequest();
        $this->ipAddress = static::getIpAddressFromRequest($this->request, $this->trustedProxies, $this->headers);

        return $this->delegate();
    }

    protected static function isValidIpAddress(string $ip): bool
    {
        return false !== filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_IPV6);
    }

    /**
     * @param ServerRequestInterface $request
     * @param string[] $headers
     * @return null|string
     */
    protected static function getIpAddressFromHeaders(ServerRequestInterface $request, array $headers): ?string
    {
        foreach ($headers as $headerName) {
            $headerValue = trim(explode(',', $request->getHeaderLine($headerName))[0]);
            if (empty($headerValue)) {
                continue;
            }

            if (strtolower($headerName) == 'forwarded') {
                $headerValue = static::parseForwarded($headerValue);
            }

            if (is_null($headerValue)) {
                continue;
            }

            if (static::isValidIpAddress($headerValue)) {
                return $headerValue;
            }
        }

        return null;
    }

    protected static function parseForwarded($headerValue): ?string
    {
        foreach (explode(';', $headerValue) as $headerPart) {
            if (strtolower(substr($headerPart, 0, 4)) == 'for=') {
                $for = explode(']', $headerPart);
                return trim(substr($for[0], 4), " \t\n\r\0\x0B\"[]");
            }
        }

        return null;
    }
}