Check for Ajax request in CodeIgniter

Question

I'm in a PHP script and I want to check whether the request is an Ajax request. (Basically to NOT allow direct script access, other than Ajax calls.)

So, I'm defining IS_AJAX somewhere in the main index.php file:

define('IS_AJAX', 
       isset($_SERVER['HTTP_X_REQUESTED_WITH']) && 
       strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest');

And then checking it at the top of my script:

if (!IS_AJAX) exit('No direct script access allowed');

Since I'm new to CodeIgniter, I would like to know:

• Is there any such built-in functionality?
• Is there a more elegant way to do it?

Answer 1

You can use $this->input->is_ajax_request() from the input class:

if (!$this->input->is_ajax_request()) {
   exit('No direct script access allowed');
}

Answer 2

There is no need to add an if (!$this->input->is_ajax_request()) to every AJAX method if you use hooks (CI docs). This is based on Jorge's solution in here with a few slight improvements:

config/config.php

Enable CI hooks by changing the default value (from FALSE):

$config['enable_hooks'] = TRUE;

config/hooks.php

Add the following at the end:

$hook['post_controller_constructor'] = array(
    'class' => 'Ajax_only',
    'function' => 'show_404_on_illegal_ajax',
    'filename' => 'Ajax_only.php',
    'filepath' => 'hooks'
);

post_controller_constructor: called immediately after your controller is instantiated, but prior to any method calls happening

config/ajax_methods.php

Create a new config file with all the controllers and methods that should only be invoked when an AJAX request is made:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');
/*
|--------------------------------------------------------------------------
| References to all AJAX controllers' methods or the controller itself
|--------------------------------------------------------------------------
|
| Based on Jorge's solution: https://stackoverflow.com/a/43484330/6225838
| Key: controller name
| Possible values:
| - array: method name as key and boolean as value (TRUE => IS_AJAX)
| - boolean: TRUE if all the controller's methods are for AJAX requests
|
*/
$config['welcome'] = [
  'index' => FALSE, // or 0 -> this line can be removed (just for reference)
  'ajax_request_method_1' => TRUE, // or 1
  'ajax_request_method_2' => TRUE, // or 1
];
$config['ajax_troller'] = TRUE;

hooks/Ajax_only.php

Create the hook itself, which detects if the current controller and/or its methods are present on the new config file above. If so, it shows the 404 default page when the current request is not AJAX and the method/controller has a truthy value in the config:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Ajax_only {

  public function __construct()
  {
    $this->CI = &get_instance();
    $this->CI->config->load('ajax_methods');
  }

  public function show_404_on_illegal_ajax()
  {
    $fetched_troller_val = $this->CI->config->item(
      $this->CI->router->fetch_class()
    );
    $fetched_method = $this->CI->router->fetch_method();

    $is_ajax_method = is_array($fetched_troller_val) &&
        // verify if the method's name is present
        isset($fetched_troller_val[$fetched_method]) &&
        // verify if the value is truthy
        $fetched_troller_val[$fetched_method];

    // if the controller is not in the config file then
    // config->item() returned NULL
    if($fetched_troller_val !== NULL &&
        $this->CI->input->is_ajax_request() === FALSE  &&
        ($fetched_troller_val === TRUE || $is_ajax_method)
      ) {
      show_404();
    }
  }
}

Answer 3

if you want customize the requests from your codeigniter app, try this: You must create a hook named Ajax_only.php in application/hooks folder

class Ajax_only {
    private $_controllers = [];

    private $CI;

    public function __construct() {
        $this->CI =& get_instance();
    }

    public function eval_request() {
        $controller = $this->CI->router->fetch_class();
        $method = $this->CI->router->fetch_method();
        if ( array_key_exists( $controller, $this->_controllers ) && $this->CI->input->is_ajax_request() === FALSE  ) {
            if ( ( $this->_controllers[ $controller ] === TRUE || ( is_array( $this->_controllers[ $controller ] ) && array_key_exists( $method, $this->_controllers[ $controller ] ) && $this->_controllers[ $controller ][ $method ] === TRUE ) ) ) {
                show_404();
            }
        }
    }
}


/*Examples
 * $_controllers = [
 *      'my_controller_name' => TRUE //all methods must be ajax
 *      'my_controller_name  => [
 *          'method_name' => TRUE //only the selected methods must be ajax
 *      ]
 * ]
 */

And configure your application/config/hooks.php file

$hook['post_controller_constructor'] = array(
    'class' => 'Ajax_only',
    'function' => 'eval_request',
    'filename' => 'Ajax_only.php',
    'filepath' => 'hooks'
);