captcha.php

<?php
/*
	Question2Answer by Gideon Greenspan and contributors
	http://www.question2answer.org/

	File: qa-include/qa-app-captcha.php
	Description: Wrapper functions and utilities for captcha modules


	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	More about this license: http://www.question2answer.org/license.php
*/

if (!defined('QA_VERSION')) { // don't allow this page to be requested directly from browser
	header('Location: ../');
	exit;
}


/**
 * Return whether a captcha module has been selected and it indicates that it is fully set up to go.
 */
function qa_captcha_available()
{
	$module = qa_load_module('captcha', qa_opt('captcha_module'));

	return isset($module) && (!method_exists($module, 'allow_captcha') || $module->allow_captcha());
}


/**
 * Return an HTML string explaining $captchareason (from qa_user_captcha_reason()) to the user about why they are seeing a captcha
 */
function qa_captcha_reason_note($captchareason)
{
	$notehtml = null;

	switch ($captchareason) {
		case 'login':
			$notehtml = qa_insert_login_links(qa_lang_html('misc/captcha_login_fix'));
			break;

		case 'confirm':
			$notehtml = qa_insert_login_links(qa_lang_html('misc/captcha_confirm_fix'));
			break;

		case 'approve':
			$notehtml = qa_lang_html('misc/captcha_approve_fix');
			break;
	}

	return $notehtml;
}


/**
 * Prepare $qa_content for showing a captcha, adding the element to $fields, given previous $errors, and a $note to display.
 * Returns JavaScript required to load CAPTCHA when field is shown by user (e.g. clicking comment button).
 */
function qa_set_up_captcha_field(&$qa_content, &$fields, $errors, $note=null)
{
	if (!qa_captcha_available())
		return '';

	$captcha = qa_load_module('captcha', qa_opt('captcha_module'));

	// workaround for reCAPTCHA, to load multiple instances via JS
	$count = @++$qa_content['qa_captcha_count'];

	if ($count > 1) {
		// use blank captcha in order to load via JS
		$html = '';
	}
	else {
		// first captcha is always loaded explicitly
		$qa_content['script_var']['qa_captcha_in'] = 'qa_captcha_div_1';
		$html = $captcha->form_html($qa_content, @$errors['captcha']);
	}

	$fields['captcha'] = array(
		'type' => 'custom',
		'label' => qa_lang_html('misc/captcha_label'),
		'html' => '<div id="qa_captcha_div_'.$count.'">'.$html.'</div>',
		'error' => @array_key_exists('captcha', $errors) ? qa_lang_html('misc/captcha_error') : null,
		'note' => $note,
	);

	return "if (!document.getElementById('qa_captcha_div_".$count."').hasChildNodes()) { recaptcha_load('qa_captcha_div_".$count."'); }";
}


/**
 * Check if captcha is submitted correctly, and if not, set $errors['captcha'] to a descriptive string.
 */
function qa_captcha_validate_post(&$errors)
{
	if (qa_captcha_available()) {
		$captcha = qa_load_module('captcha', qa_opt('captcha_module'));

		if (!$captcha->validate_post($error)) {
			$errors['captcha'] = $error;
			return false;
		}
	}

	return true;
}