Require user's IP location to be the same as their billing country field [Paid Memberships Pro]

require-ip-location-match.php

<?php
/**
 * Require user's checking out for any level that requires billing to match their IP address with billing country address fields.
 * Only works with levels that require billing fields.
 * Please install and activate the following plugin - https://wordpress.org/plugins/geoip-detect/
 */
 
function pmpro_require_location_match_IP( $continue ) {

    global $pmpro_requirebilling;

    // If something else is wrong or billing fields aren't required, don't run this code further.
    if ( ! $continue || ! $pmpro_requirebilling ) {
        return $continue;
    }

    // If GEOIP plugin not installed, bail.
    if ( ! function_exists( 'geoip_detect2_get_info_from_current_ip') ) {
        pmpro_setMessage("Unable to obtain user's location. Function 'geoip_detect2_get_info_from_current_ip' does not exist.", "pmpro_error");
        return false;
    }

    // Compare IP with billing fields.
    $ip_country = geoip_detect2_get_info_from_current_ip()->country->isoCode;
    $billing_country = isset( $_REQUEST['bcountry'] ) ? sanitize_text_field( $_REQUEST['bcountry'] ) : '';

    // Unable to get IP Country.
    if ( empty( $ip_country ) ) {
        pmpro_setMessage("Unable to obtain user's location.", "pmpro_error");
        return false;
    }

    // Unable to get billing field.
    if ( empty( $billing_country ) ) {
        pmpro_setMessage("Unable to get billing country field.", "pmpro_error");
        return false;
    }

    if ( $ip_country == $billing_country ) {
        $okay = true;
    } else {
        pmpro_setMessage("Your location does not match your billing location.", "pmpro_error");
        $okay = false;
    }

    return $okay;
}
add_filter( 'pmpro_registration_checks', 'pmpro_require_location_match_IP' );

This recipe is included in the blog post on "Prevent Card Fraud by Matching IP Address to Billing Country" at Paid Memberships Pro here: https://www.paidmembershipspro.com/prevent-card-fraud-ip-address-billing-country/