File external/spam-check.php

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<?php

namespace SIW\External;

/**
 * Opzoeken e-mailadres en IP in SFS-spamdatabase
 *
 * @copyright 2019 SIW Internationale Vrijwilligersprojecten
 * @since     3.0.0
 * 
 * @link      https://www.stopforumspam.com/usage
 */
class Spam_Check{

    /**
     * API URL
     *
     * @var string
     */
    const API_URL = 'https://europe.stopforumspam.org/api';

    /**
     * Grens voor Spam
     *
     * @var float
     */
    const SPAM_THRESHOLD = 90.00;

    /**
     * Geldigheidsduur van transient
     *
     * @var int
     */
    const TRANSIENT_EXPIRATION = 1 * DAY_IN_SECONDS;

    /**
     * Algoritme om email-adress te hashen voor opslag
     * 
     * @var string
     */
    const HASH_ALGORITHM = 'sha1';

    /**
     * Geeft aan of IP gecheckt moet worden
     *
     * @var bool
     */
    protected $check_ip = false;

    /**
     * Geeft aan of e-mail gecheckt moet worden
     *
     * @var bool
     */
    protected $check_email = false;

    /**
     * IP-adres
     *
     * @var string
     */
    protected $ip;

    /**
     * E-mailadres
     *
     * @var string
     */
    protected $email;

    /**
     * Hash van e-mailadres
     *
     * @var string
     */
    protected $email_hash;

    /**
     * Zet IP-adres om te controlen
     *
     * @param string $ip
     */
    public function set_ip( string $ip ) {
        if ( filter_var( $ip, FILTER_VALIDATE_IP ) ) {
            $this->ip = $ip;
            $this->check_ip = true;
        }
    }

    /**
     * Zet e-mailadres om te controleren
     *
     * @param string $email
     */
    public function set_email( string $email ) {
        if ( is_email( $email ) ) {
            $this->email = strtolower( $email );
            $this->email_hash = hash( self::HASH_ALGORITHM, $this->email );
            $this->check_email = true;
        }
    }

    /**
     * Geeft aan of het een spammer betreft
     *
     * @return bool
     */
    public function is_spammer() {

        //Afbreken als er niets to controleren is
        if ( ! $this->check_email && ! $this->check_ip ) {
            return false;
        }

        // Check of IP-adres uit transient beschikbaar is en direct afbreken als het vrijwel zeker een spammer is
        if ( $this->check_ip ) {
            $ip_confidence = get_transient( "siw_spam_ip_{$this->ip}" );
            if ( false !== $ip_confidence ) {
                if ( floatval( $ip_confidence ) > self::SPAM_THRESHOLD ) {
                    return true;
                }
                $this->check_ip = false;
            }
        }

        // Check of email-adres uit transient beschikbaar is en direct afbreken als het vrijwel zeker een spammer is
        if ( $this->check_email ) {
            $email_confidence = get_transient( "siw_spam_email_{$this->email_hash}" );
            if ( false !== $email_confidence ) {
                if ( floatval( $email_confidence ) > self::SPAM_THRESHOLD ) {
                    return true;
                }
                $this->check_email = false;
            }
        }

        // Externe check aanroepen indien nog nodig
        if ( $this->check_email || $this->check_ip ) {
            $result = $this->external_lookup();

            if ( isset( $result['email'] ) ) {
                $email_confidence = floatval( $result['email'] ); 
                set_transient( "siw_spam_email_{$this->email_hash}", $email_confidence, self::TRANSIENT_EXPIRATION );
            }

            if ( isset( $result['ip'] ) ) {
                $email_confidence = floatval( $result['ip'] );
                set_transient( "siw_spam_ip_{$this->ip}", $ip_confidence, self::TRANSIENT_EXPIRATION );
            }
    
            //Bepaal of het een spammer betreft
            if ( isset( $email_confidence ) && $email_confidence > self::SPAM_THRESHOLD ) {
                return true;
            }
            
            if ( isset( $ip_confidence ) && $ip_confidence > self::SPAM_THRESHOLD ) {
                return true;
            }
        }
        
        return false;
    }

    /**
     * Zoek email en IP op in externe database
     */
    protected function external_lookup() {

        $body = [
            'json'  => true
        ];
        if ( $this->check_email ) {
            $body['email'] = $this->email;
        }
        if ( $this->check_ip ) {
            $body['ip'] = $this->ip;
        }

        $args = [
            'body'    => $body,
            'timeout' => 10,
        ];

        $response = wp_safe_remote_post( self::API_URL, $args );

        if ( false == $this->check_response( $response ) ) {
            return [];
        }

        $body = json_decode( wp_remote_retrieve_body( $response ), true );
        if ( false == $body['success'] ) {
            return [];
        }

        $result = [];
        if ( $this->check_email && $body['email']['appears'] ) {
            $result['email'] = $body['email']['confidence'];
        }

        if ( $this->check_ip && $body['ip']['appears'] ) {
            $result['ip'] = $body['ip']['confidence'];
        }

        return $result;
    }

    /**
     * Check HTTP response
     *
     * @param \WP_Error|array $response
     * @return bool
     */
    protected function check_response( $response ) {
        if ( is_wp_error( $response ) ) {
            return false;
        }
        if ( \WP_Http::OK !== wp_remote_retrieve_response_code( $response ) ) {
            return false;
        }
        
        return true;
    }
}

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