software-license-manager/includes/slm-api-utility.php

<?php

class SLM_API_Utility {
    /*
     * The args array can contain the following:
     * result (success or error)
     * message (a message describing the outcome of the action
     */

    static function output_api_response($args) {
        //Log to debug file (if enabled)
        global $slm_debug_logger;
        $slm_debug_logger->log_debug('API Response - Result: ' . $args['result'] . ' Message: ' . $args['message']);

        //Send response
        $args = apply_filters( 'slm_ap_response_args', $args);
        $args = apply_filters( 'slm_api_response_args', $args);

        header('Content-Type: application/json');
        echo json_encode($args);
        exit(0);
    }

    static function verify_secret_key() {
        $slm_options                = get_option('slm_plugin_options');
        $right_secret_key           = $slm_options['lic_verification_secret'];
        $received_secret_key        = strip_tags($_REQUEST['secret_key']);
        if ($received_secret_key    != $right_secret_key) {
            $args = (array(
                'result'        => 'error',
                'message'       => 'Verification API secret key is invalid',
                'error_code'    => SLM_Error_Codes::VERIFY_KEY_INVALID
            ));
            SLM_API_Utility::output_api_response($args);
        }
    }

    static function verify_secret_key_for_creation() {
        $slm_options                = get_option('slm_plugin_options');
        $right_secret_key           = $slm_options['lic_creation_secret'];
        $received_secret_key        = strip_tags($_REQUEST['secret_key']);
        if ($received_secret_key    != $right_secret_key) {
            $args = (array(
                'result'        => 'error',
                'message'       => 'License Creation API secret key is invalid',
                'error_code'    => SLM_Error_Codes::CREATE_KEY_INVALID
            ));
            SLM_API_Utility::output_api_response($args);
        }
    }

    static function insert_license_data_internal($fields) {
        global $wpdb;
        $tbl_name   = SLM_TBL_LICENSE_KEYS;
        $fields     = array_filter($fields);//Remove any null values.
        $result     = $wpdb->insert($tbl_name, $fields);
    }
}