Restrict Membership Level Signup by Email Domain

my-pmpro-restrict-registration-by-emaildomain.php

<?php

/**
 * Restrict Membership Signup by Email Domain & Level
 * Make sure to edit the $valid_domains array defined further below
 * to include only the domains you'd like to allow.
 *
 * Add this code to a custom plugin. More info: https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_registration_checks_restrict_email_addresses( $value ) {
	global $pmpro_level;

	$protected_levels = array(
		10 => array( 'domain.com', 'domain2.com' ),
		12 => array( 'gmail.com', 'yahoo.com' ),
	);
	if ( ! array_key_exists( $pmpro_level->id, $protected_levels ) ) {
		return $value;
	}
	$email = $_REQUEST['bemail'];

	if ( ! my_checkForValidDomain( $email, $protected_levels[ $pmpro_level->id ] ) ) {
		global $pmpro_msg, $pmpro_msgt;
		$pmpro_msg  = 'Please enter a valid email address';
		$pmpro_msgt = 'pmpro_error';
		$value      = false;
	}

	return $value;
}
add_filter( 'pmpro_registration_checks', 'my_pmpro_registration_checks_restrict_email_addresses', 10, 1 );

// Taken from: http://www.bitrepository.com/how-to-extract-domain-name-from-an-e-mail-address-string.html
function my_getDomainFromEmail( $email ) {
	// Get the data after the @ sign
	$domain = substr( strrchr( $email, '@' ), 1 );

	return $domain;
}

function my_checkForValidDomain( $email, $valid_domains ) {
	$domain = my_getDomainFromEmail( $email );

	if ( ! is_array( $valid_domains ) ) {
		return true;
	}

	foreach ( $valid_domains as $valid_domain ) {
		$components      = explode( '.', $valid_domain );
		$domain_to_check = explode( '.', $domain );

		if ( $components[0] == '*' && ( count( $domain_to_check ) > 2 ) ) {
			if ( $components[1] == $domain_to_check[1] && $components[2] == $domain_to_check[2] ) {
				return true;
			}
		} else {
			if ( ! ( strpos( $valid_domain, $domain ) === false ) ) {
				return true;
			}
		}
	}

	return false;
}