tml_admin_sanitize_promotion()

function tml_admin_sanitize_promotion( $promotion, $now ) {
    if ( ! is_array( $promotion ) ) {
        return null;
    }

    foreach ( array( 'name', 'code', 'discount', 'starts', 'ends', 'url' ) as $key ) {
        if ( ! isset( $promotion[ $key ] ) || ! is_scalar( $promotion[ $key ] ) ) {
            return null;
        }
    }

    $starts = (int) $promotion['starts'];
    $ends   = (int) $promotion['ends'];
    $url    = wp_parse_url( (string) $promotion['url'] );

    if (
        $now < $starts
        || $now >= $ends
        || ! preg_match( '/^[A-Za-z0-9_-]{1,50}$/', (string) $promotion['code'] )
        || ! preg_match( '/^\d{1,2}(\.\d+)?%$/', (string) $promotion['discount'] )
        || empty( $url['scheme'] ) || 'https' !== $url['scheme']
        || empty( $url['host'] ) || ! preg_match( '/(^|\.)thememylogin\.com$/', $url['host'] )
    ) {
        return null;
    }

    $timezone = isset( $promotion['timezone'] ) ? (string) $promotion['timezone'] : '';

    return array(
        'name'     => wp_strip_all_tags( substr( (string) $promotion['name'], 0, 80 ) ),
        'code'     => (string) $promotion['code'],
        'discount' => (string) $promotion['discount'],
        'starts'   => $starts,
        'ends'     => $ends,
        'timezone' => in_array( $timezone, timezone_identifiers_list(), true ) ? $timezone : 'UTC',
        'url'      => (string) $promotion['url'],
    );
}

View src/admin/promotions.php, line 181 on GitHub